summaryrefslogtreecommitdiff
path: root/docs
diff options
context:
space:
mode:
authorCliff Click <cliffc@acm.org>2023-10-27 20:35:04 +0100
committerCliff Click <cliffc@acm.org>2026-10-04 13:30:41 -0700
commit0f0ca9396a68b78362ce1ee59e6dc11d6910d56c (patch)
tree601c8da8618e55b7b08cba9dac80b78de532ec34 /docs
parent26c9ce808557ed4c7f6c2c84d9e8f8cd7ebced49 (diff)
downloadSimple-0f0ca9396a68b78362ce1ee59e6dc11d6910d56c.tar.gz
Simple-0f0ca9396a68b78362ce1ee59e6dc11d6910d56c.zip
Chapter 5: If Statement, Phi, and Region
Co-authored-by: Dibyendu Majumdar <mobile@majumdar.org.uk> Co-authored-by: XmiliaH <45106915+XmiliaH@users.noreply.github.com> Co-authored-by: Yichen Yan <oraluben@outlook.com> Co-authored-by: Thalia Archibald <thalia@archibald.dev> Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com> Co-authored-by: Tamas Hadhazy <helsgithub15@gmail.com> Co-authored-by: Symious <14933944+symious@users.noreply.github.com> Co-authored-by: Claude Opus 5 <noreply@anthropic.com> Co-authored-by: tannal <tannal2409@gmail.com> Co-authored-by: hadha <helsgithub15@gmail.com> Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com> Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com> Co-authored-by: RobertObkircher <robert.obkircher@gmail.com> Co-authored-by: David Rubin <87927264+Rexicon226@users.noreply.github.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/chapter05/05-grammar.md79
-rw-r--r--docs/chapter05/05-graph1.gv88
-rw-r--r--docs/chapter05/05-graph1.json25
-rw-r--r--docs/chapter05/05-graph1.svg120
-rw-r--r--docs/chapter05/05-graph2.gv78
-rw-r--r--docs/chapter05/05-graph2.json27
-rw-r--r--docs/chapter05/05-graph2.svg125
-rw-r--r--docs/chapter05/05-graph3.gv66
-rw-r--r--docs/chapter05/05-graph3.json28
-rw-r--r--docs/chapter05/05-graph3.svg127
-rw-r--r--docs/chapter05/05-graph4.gv63
-rw-r--r--docs/chapter05/05-graph4.json19
-rw-r--r--docs/chapter05/05-graph4.svg95
-rw-r--r--docs/chapter05/05-graph5.gv60
-rw-r--r--docs/chapter05/05-graph5.json18
-rw-r--r--docs/chapter05/05-graph5.svg90
-rw-r--r--docs/chapter05/05-graph6.gv58
-rw-r--r--docs/chapter05/05-graph6.json15
-rw-r--r--docs/chapter05/05-graph6.svg78
-rw-r--r--docs/chapter05/05-graph7.gv72
-rw-r--r--docs/chapter05/05-graph7.json22
-rw-r--r--docs/chapter05/05-graph7.svg108
-rw-r--r--docs/chapter05/05-graph8.gv129
-rw-r--r--docs/chapter05/05-graph8.json45
-rw-r--r--docs/chapter05/05-graph8.svg188
-rw-r--r--docs/chapter05/05-graph9.json26
-rw-r--r--docs/chapter05/05-graph9.svg117
-rw-r--r--docs/chapter05/Makefile1
-rw-r--r--docs/chapter05/README.md425
29 files changed, 2392 insertions, 0 deletions
diff --git a/docs/chapter05/05-grammar.md b/docs/chapter05/05-grammar.md
new file mode 100644
index 00000000..8eba1581
--- /dev/null
+++ b/docs/chapter05/05-grammar.md
@@ -0,0 +1,79 @@
+# Grammar for Chapter 1
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+ : statement+ EOF
+ ;
+
+statement
+ : returnStatement
+ | declStatement
+ | blockStatment
+ | expressionStatement
+ | ifStatement
+ ;
+
+ifStatement
+ : 'if' '(' expression ')' statement ('else' statement)?
+ ;
+
+
+expressionStatement
+ : IDENTIFIER '=' expression ';'
+ ;
+
+blockStatement
+ : '{' statement+ '}'
+ ;
+
+declStatement
+ : 'int' IDENTIFIER '=' expression ';'
+ ;
+
+returnStatement
+ : 'return' expression ';'
+ ;
+
+expression
+ : comparisonExpression
+ ;
+
+comparisonExpression
+ : additiveExpression (('==' | '!='| '>'| '<'| '>='| '<=') additiveExpression)*
+ ;
+
+additiveExpression
+ : multiplicativeExpression (('+' | '-') multiplicativeExpression)*
+ ;
+
+multiplicativeExpression
+ : unaryExpression (('*' | '/') unaryExpression)*
+ ;
+
+unaryExpression
+ : ('-') unaryExpression
+ | primaryExpression
+ ;
+
+primaryExpression
+ : IDENTIFIER
+ | INTEGER_LITERAL
+ | 'true'
+ | 'false'
+ | '(' expression ')'
+ ;
+
+INTEGER_LITERAL
+ : [1-9][0-9]*
+ | [0]
+ ;
+
+IDENTIFIER
+ : NON_DIGIT (NON_DIGIT | DIGIT)*
+ ;
+
+NON_DIGIT: [a-zA-Z_];
+DEC_DIGIT: [0-9];
+```
diff --git a/docs/chapter05/05-graph1.gv b/docs/chapter05/05-graph1.gv
new file mode 100644
index 00000000..b5cf8370
--- /dev/null
+++ b/docs/chapter05/05-graph1.gv
@@ -0,0 +1,88 @@
+digraph chapter05 {
+/*
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else {
+ a = arg-3;
+
+}
+
+return a;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_7 [ label="#1" ];
+ EQNode8 [ label="==" ];
+ If9 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_13 [ label="#2" ];
+ Add14 [ label="+" ];
+ Con_15 [ label="#3" ];
+ Sub16 [ label="-" ];
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope1_0 {
+ Scope1_0 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope1_0_$ctrl">$ctrl</TD><TD PORT="Scope1_0_arg">arg</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope1_1 {
+ Scope1_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD><TD PORT="Scope1_1_a">a</TD></TR>
+ </TABLE>>];
+ }
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope12_0 {
+ Scope12_0 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope12_0_$ctrl">$ctrl</TD><TD PORT="Scope12_0_arg">arg</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope12_1 {
+ Scope12_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD><TD PORT="Scope12_1_a">a</TD></TR>
+ </TABLE>>];
+ }
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ EQNode8 -> Start2:p1[taillabel=1];
+ EQNode8 -> Con_7[taillabel=2];
+ If9 -> Start2:p0[taillabel=0; color=red];
+ If9 -> EQNode8[taillabel=1];
+ Add14 -> Start2:p1[taillabel=1];
+ Add14 -> Con_13[taillabel=2];
+ Sub16 -> Start2:p1[taillabel=1];
+ Sub16 -> Con_15[taillabel=2];
+ edge [style=dashed color=cornflowerblue];
+ Scope1_0:"Scope1_0_$ctrl" -> If9:p0;
+ Scope1_0:"Scope1_0_arg" -> Start2:p1;
+ Scope1_1:"Scope1_1_a" -> Add14;
+ edge [style=dashed color=cornflowerblue];
+ Scope12_0:"Scope12_0_$ctrl" -> If9:p1;
+ Scope12_0:"Scope12_0_arg" -> Start2:p1;
+ Scope12_1:"Scope12_1_a" -> Sub16;
+}
diff --git a/docs/chapter05/05-graph1.json b/docs/chapter05/05-graph1.json
new file mode 100644
index 00000000..a2b4a7bd
--- /dev/null
+++ b/docs/chapter05/05-graph1.json
@@ -0,0 +1,25 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph1.svg",
+ "step": 1,
+ "roots": [],
+ "scope": 0,
+ "nodes": [
+ {"id": 1, "label": "Scope", "type": null, "kind": "SCOPE", "edges": [{"idx": 0, "def": 11, "role": "ASSOC", "label": "0: $ctrl"}, {"idx": 1, "def": 10, "role": "ASSOC", "label": "0: arg"}, {"idx": 2, "def": 14, "role": "ASSOC", "label": "1: a"}], "proj": null},
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 4, "label": "Scope", "type": null, "kind": "SCOPE", "edges": [{"idx": 0, "def": 12, "role": "ASSOC", "label": "0: $ctrl"}, {"idx": 1, "def": 10, "role": "ASSOC", "label": "0: arg"}, {"idx": 2, "def": 16, "role": "ASSOC", "label": "1: a"}], "proj": null},
+ {"id": 6, "label": "$ctrl", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 2, "role": "CTRL", "label": null}], "proj": {"par": 2, "idx": 0}},
+ {"id": 7, "label": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 8, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 10, "role": "DATA", "label": null}, {"idx": 2, "def": 7, "role": "DATA", "label": null}], "proj": null},
+ {"id": 9, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 6, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}], "proj": null},
+ {"id": 10, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 11, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 0}},
+ {"id": 12, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 1}},
+ {"id": 13, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 14, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 10, "role": "DATA", "label": null}, {"idx": 2, "def": 13, "role": "DATA", "label": null}], "proj": null},
+ {"id": 15, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 16, "label": "-", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 10, "role": "DATA", "label": null}, {"idx": 2, "def": 15, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter05/05-graph1.svg b/docs/chapter05/05-graph1.svg
new file mode 100644
index 00000000..0a75532a
--- /dev/null
+++ b/docs/chapter05/05-graph1.svg
@@ -0,0 +1,120 @@
+<svg aria-label="Compiler graph" width="1006" height="548" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1006 548" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"/><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge ASSOC" id="e1i0" d="M84,367 C84,391 848.5,364 848.5,388" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[0] → #11 · ASSOC · 0: $ctrl</title></path><path class="edge ASSOC" id="e1i1" d="M224,115 C224,139 906.5,364 906.5,388" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[1] → #10 · ASSOC · 0: arg</title></path><path class="edge ASSOC" id="e1i2" d="M376,219 C376,243 958,364 958,388" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[2] → #14 · ASSOC · 1: a</title></path><path class="edge ASSOC" id="e4i0" d="M204,367 C204,391 848.5,444 848.5,468" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#4[0] → #12 · ASSOC · 0: $ctrl</title></path><path class="edge ASSOC" id="e4i1" d="M224,115 C224,139 906.5,444 906.5,468" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#4[1] → #10 · ASSOC · 0: arg</title></path><path class="edge ASSOC" id="e4i2" d="M528,219 C528,243 958,444 958,468" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#4[2] → #16 · ASSOC · 1: a</title></path><path class="edge DATA" id="e8i1" d="M224,118 L224,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #10 · DATA</title></path><path class="edge DATA" id="e8i2" d="M382,118 L382,123 Q382,128 377,128 L262,128 Q254,128 254,136 L254,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge CTRL" id="e9i0" d="M104,118 L104,270" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#9[0] → #6 · CTRL</title></path><path class="edge DATA" id="e9i1" d="M224,222 L224,227 Q224,232 219,232 L192,232 Q184,232 184,240 L184,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #8 · DATA</title></path><path class="edge DATA" id="e14i1" d="M224,118 L224,130 Q224,138 232,138 L368,138 Q376,138 376,146 L376,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[1] → #10 · DATA</title></path><path class="edge DATA" id="e14i2" d="M534,118 L534,123 Q534,128 529,128 L414,128 Q406,128 406,136 L406,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[2] → #13 · DATA</title></path><path class="edge DATA" id="e16i1" d="M224,118 L224,130 Q224,138 232,138 L520,138 Q528,138 528,146 L528,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[1] → #10 · DATA</title></path><path class="edge DATA" id="e16i2" d="M686,118 L686,123 Q686,128 681,128 L566,128 Q558,128 558,136 L558,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[2] → #15 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n1" data-id="1" transform="translate(818,388)" style="opacity: 1;"><path class="box" d="M4,0H160Q164,0 164,4V52Q164,56 160,56H4Q0,56 0,52V4Q0,0 4,0Z" fill="#e5e0ff"/><text class="label" text-anchor="middle" x="82" y="48"><tspan>Scope</tspan><tspan class="node-id">  #1</tspan></text><text class="type" text-anchor="middle" y="35" x="82"/><title>#1 Scope
+Type not computed
+
+[0] → #11 ASSOC 0: $ctrl
+[1] → #10 ASSOC 0: arg
+[2] → #14 ASSOC 1: a</title><line class="row" x1="0" x2="164" y1="30" y2="30"/><line class="row" x1="61" x2="61" y1="0" y2="30"/><line class="row" x1="116" x2="116" y1="0" y2="30"/><text class="bind" x="30.5" y="20" text-anchor="middle">0: $ctrl</text><text class="bind" x="88.5" y="20" text-anchor="middle">0: arg</text><text class="bind" x="140" y="20" text-anchor="middle">1: a</text><circle class="port" cx="30.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="88.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="140" cy="0" r="3" fill="#536477"/><text class="slot" x="30.5" y="-7" text-anchor="middle">0</text><text class="slot" x="88.5" y="-7" text-anchor="middle">1</text><text class="slot" x="140" y="-7" text-anchor="middle">2</text></g><g class="node" id="n2" data-id="2" transform="translate(44,24)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n4" data-id="4" transform="translate(818,468)" style="opacity: 1;"><path class="box" d="M4,0H160Q164,0 164,4V52Q164,56 160,56H4Q0,56 0,52V4Q0,0 4,0Z" fill="#e5e0ff"/><text class="label" text-anchor="middle" x="82" y="48"><tspan>Scope</tspan><tspan class="node-id">  #4</tspan></text><text class="type" text-anchor="middle" y="35" x="82"/><title>#4 Scope
+Type not computed
+
+[0] → #12 ASSOC 0: $ctrl
+[1] → #10 ASSOC 0: arg
+[2] → #16 ASSOC 1: a</title><line class="row" x1="0" x2="164" y1="30" y2="30"/><line class="row" x1="61" x2="61" y1="0" y2="30"/><line class="row" x1="116" x2="116" y1="0" y2="30"/><text class="bind" x="30.5" y="20" text-anchor="middle">0: $ctrl</text><text class="bind" x="88.5" y="20" text-anchor="middle">0: arg</text><text class="bind" x="140" y="20" text-anchor="middle">1: a</text><circle class="port" cx="30.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="88.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="140" cy="0" r="3" fill="#536477"/><text class="slot" x="30.5" y="-7" text-anchor="middle">0</text><text class="slot" x="88.5" y="-7" text-anchor="middle">1</text><text class="slot" x="140" y="-7" text-anchor="middle">2</text></g><g class="node" id="n6" data-id="6" transform="translate(44,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>$ctrl</tspan><tspan class="node-id">  #6/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 $ctrl
+Projection 0 of #2
+Type not computed
+
+[0] → #2 CTRL</title></g><g class="node" id="n7" data-id="7" transform="translate(322,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#1</tspan><tspan class="node-id">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 #1
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(164,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #8</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#8 ==
+Type not computed
+
+[0] → — DATA
+[1] → #10 DATA
+[2] → #7 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n9" data-id="9" transform="translate(24,276)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#9 If
+Type not computed
+
+[0] → #6 CTRL
+[1] → #8 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n10" data-id="10" transform="translate(164,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #10/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#10 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n11" data-id="11" transform="translate(24,320)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #11/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#11 True
+Projection 0 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n12" data-id="12" transform="translate(144,320)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #12/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#12 False
+Projection 1 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n13" data-id="13" transform="translate(474,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #13</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#13 #2
+Type not computed
+
+</title></g><g class="node" id="n14" data-id="14" transform="translate(316,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>+</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 +
+Type not computed
+
+[0] → — DATA
+[1] → #10 DATA
+[2] → #13 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n15" data-id="15" transform="translate(626,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#15 #3
+Type not computed
+
+</title></g><g class="node" id="n16" data-id="16" transform="translate(468,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>-</tspan><tspan class="node-id">  #16</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 -
+Type not computed
+
+[0] → — DATA
+[1] → #10 DATA
+[2] → #15 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g></g><g class="region-heads" style="opacity: 1;"/><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph2.gv b/docs/chapter05/05-graph2.gv
new file mode 100644
index 00000000..a560bc49
--- /dev/null
+++ b/docs/chapter05/05-graph2.gv
@@ -0,0 +1,78 @@
+digraph chapter05 {
+/*
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else {
+ a = arg-3;
+
+}
+
+return a;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_7 [ label="#1" ];
+ EQNode8 [ label="==" ];
+ If9 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_13 [ label="#2" ];
+ Add14 [ label="+" ];
+ Con_15 [ label="#3" ];
+ Sub16 [ label="-" ];
+ Region17 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a18 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ { rank=same; Region17;Phi_a18;}
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope1_0 {
+ Scope1_0 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope1_0_$ctrl">$ctrl</TD><TD PORT="Scope1_0_arg">arg</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope1_1 {
+ Scope1_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD><TD PORT="Scope1_1_a">a</TD></TR>
+ </TABLE>>];
+ }
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ EQNode8 -> Start2:p1[taillabel=1];
+ EQNode8 -> Con_7[taillabel=2];
+ If9 -> Start2:p0[taillabel=0 color=red];
+ If9 -> EQNode8[taillabel=1];
+ Add14 -> Start2:p1[taillabel=1];
+ Add14 -> Con_13[taillabel=2];
+ Sub16 -> Start2:p1[taillabel=1];
+ Sub16 -> Con_15[taillabel=2];
+ Region17 -> If9:p0[taillabel=1 color=red];
+ Region17 -> If9:p1[taillabel=2 color=red];
+ Phi_a18 -> Region17 [style=dotted taillabel=0];
+ Phi_a18 -> Add14[taillabel=1];
+ Phi_a18 -> Sub16[taillabel=2];
+ edge [style=dashed color=cornflowerblue];
+ Scope1_0:"Scope1_0_$ctrl" -> Region17;
+ Scope1_0:"Scope1_0_arg" -> Start2:p1;
+ Scope1_1:"Scope1_1_a" -> Phi_a18;
+}
diff --git a/docs/chapter05/05-graph2.json b/docs/chapter05/05-graph2.json
new file mode 100644
index 00000000..5980da2b
--- /dev/null
+++ b/docs/chapter05/05-graph2.json
@@ -0,0 +1,27 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph2.svg",
+ "step": 1,
+ "roots": [],
+ "scope": 0,
+ "nodes": [
+ {"id": 1, "label": "Scope", "type": null, "kind": "SCOPE", "edges": [{"idx": 0, "def": 17, "role": "ASSOC", "label": "0: $ctrl"}, {"idx": 1, "def": 5, "role": "ASSOC", "label": "0: arg"}, {"idx": 2, "def": 18, "role": "ASSOC", "label": "1: a"}], "proj": null},
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 4, "label": "$ctrl", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 2, "role": "CTRL", "label": null}], "proj": {"par": 2, "idx": 0}},
+ {"id": 5, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 6, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 0}},
+ {"id": 7, "label": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 8, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 5, "role": "DATA", "label": null}, {"idx": 2, "def": 7, "role": "DATA", "label": null}], "proj": null},
+ {"id": 9, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 4, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}], "proj": null},
+ {"id": 10, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 1}},
+ {"id": 13, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 14, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 5, "role": "DATA", "label": null}, {"idx": 2, "def": 13, "role": "DATA", "label": null}], "proj": null},
+ {"id": 15, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 16, "label": "-", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 5, "role": "DATA", "label": null}, {"idx": 2, "def": 15, "role": "DATA", "label": null}], "proj": null},
+ {"id": 17, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 6, "role": "CTRL", "label": null}, {"idx": 2, "def": 10, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 18, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 17, "role": "ASSOC", "label": null}, {"idx": 1, "def": 14, "role": "DATA", "label": null}, {"idx": 2, "def": 16, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ {"id": 9, "par": 0, "nodes": [6, 8, 9, 10, 14, 16, 17, 18]}
+ ]
+}
diff --git a/docs/chapter05/05-graph2.svg b/docs/chapter05/05-graph2.svg
new file mode 100644
index 00000000..f073e342
--- /dev/null
+++ b/docs/chapter05/05-graph2.svg
@@ -0,0 +1,125 @@
+<svg aria-label="Compiler graph" width="996" height="631" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 996 631" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"><g class="region" transform="translate(144,171)"><rect class="region-box" rx="8" width="574" height="374" fill="#f2f7ef"/></g></g><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge ASSOC" id="e1i0" d="M306,530 C306,554 838.5,527 838.5,551" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[0] → #17 · ASSOC · 0: $ctrl</title></path><path class="edge ASSOC" id="e1i1" d="M356,115 C356,139 896.5,527 896.5,551" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[1] → #5 · ASSOC · 0: arg</title></path><path class="edge ASSOC" id="e1i2" d="M458,530 C458,554 948,527 948,551" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[2] → #18 · ASSOC · 1: a</title></path><path class="edge DATA" id="e8i1" d="M356,118 L356,123 Q356,128 351,128 L315,128 Q307,128 307,136 L307,225" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #5 · DATA</title></path><path class="edge DATA" id="e8i2" d="M84,118 L84,123 Q84,128 89,128 L218,128 Q226,128 226,136 L226,207 Q226,215 234,215 L332,215 Q337,215 337,220 L337,225" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge CTRL" id="e9i0" d="M236,118 L236,329" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#9[0] → #4 · CTRL</title></path><path class="edge DATA" id="e9i1" d="M307,281 L307,286.5 Q307,291 311.5,291 L311.5,291 Q316,291 316,295.5 L316,329" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #8 · DATA</title></path><path class="edge DATA" id="e14i1" d="M356,118 L356,123 Q356,128 361,128 L486,128 Q494,128 494,136 L494,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[1] → #5 · DATA</title></path><path class="edge DATA" id="e14i2" d="M524,118 L524,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[2] → #13 · DATA</title></path><path class="edge DATA" id="e16i1" d="M356,118 L356,123 Q356,128 361,128 L505,128 Q513,128 513,136 L513,283 Q513,291 521,291 L638,291 Q646,291 646,299 L646,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[1] → #5 · DATA</title></path><path class="edge DATA" id="e16i2" d="M676,118 L676,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[2] → #15 · DATA</title></path><path class="edge CTRL" id="e17i1" d="M216,429 L216,434 Q216,439 221,439 L298,439 Q306,439 306,447 L306,477" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[1] → #6 · CTRL</title></path><path class="edge CTRL" id="e17i2" d="M336,429 L336,477" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[2] → #10 · CTRL</title></path><path class="edge DATA" id="e18i1" d="M494,399.66666666666663 L494,431 Q494,439 486,439 L446,439 Q438,439 438,447 L438,477" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #14 · DATA</title></path><path class="edge DATA" id="e18i2" d="M646,399.66666666666663 L646,441 Q646,449 638,449 L486,449 Q478,449 478,457 L478,477" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[2] → #16 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n1" data-id="1" transform="translate(808,551)" style="opacity: 1;"><path class="box" d="M4,0H160Q164,0 164,4V52Q164,56 160,56H4Q0,56 0,52V4Q0,0 4,0Z" fill="#e5e0ff"/><text class="label" text-anchor="middle" x="82" y="48"><tspan>Scope</tspan><tspan class="node-id">  #1</tspan></text><text class="type" text-anchor="middle" y="35" x="82"/><title>#1 Scope
+Type not computed
+
+[0] → #17 ASSOC 0: $ctrl
+[1] → #5 ASSOC 0: arg
+[2] → #18 ASSOC 1: a</title><line class="row" x1="0" x2="164" y1="30" y2="30"/><line class="row" x1="61" x2="61" y1="0" y2="30"/><line class="row" x1="116" x2="116" y1="0" y2="30"/><text class="bind" x="30.5" y="20" text-anchor="middle">0: $ctrl</text><text class="bind" x="88.5" y="20" text-anchor="middle">0: arg</text><text class="bind" x="140" y="20" text-anchor="middle">1: a</text><circle class="port" cx="30.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="88.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="140" cy="0" r="3" fill="#536477"/><text class="slot" x="30.5" y="-7" text-anchor="middle">0</text><text class="slot" x="88.5" y="-7" text-anchor="middle">1</text><text class="slot" x="140" y="-7" text-anchor="middle">2</text></g><g class="node" id="n2" data-id="2" transform="translate(176,24)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n4" data-id="4" transform="translate(176,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>$ctrl</tspan><tspan class="node-id">  #4/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 $ctrl
+Projection 0 of #2
+Type not computed
+
+[0] → #2 CTRL</title></g><g class="node" id="n5" data-id="5" transform="translate(296,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #5/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#5 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n6" data-id="6" transform="translate(156,379)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #6/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 True
+Projection 0 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n7" data-id="7" transform="translate(24,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#1</tspan><tspan class="node-id">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 #1
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(247,231)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #8</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#8 ==
+Type not computed
+
+[0] → — DATA
+[1] → #5 DATA
+[2] → #7 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n9" data-id="9" transform="translate(156,335)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#9 If
+Type not computed
+
+[0] → #4 CTRL
+[1] → #8 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n10" data-id="10" transform="translate(276,379)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #10/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#10 False
+Projection 1 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n13" data-id="13" transform="translate(464,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #13</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#13 #2
+Type not computed
+
+</title></g><g class="node" id="n14" data-id="14" transform="translate(434,349.66666666666663)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>+</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 +
+Type not computed
+
+[0] → — DATA
+[1] → #5 DATA
+[2] → #13 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n15" data-id="15" transform="translate(616,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#15 #3
+Type not computed
+
+</title></g><g class="node" id="n16" data-id="16" transform="translate(586,349.66666666666663)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>-</tspan><tspan class="node-id">  #16</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 -
+Type not computed
+
+[0] → — DATA
+[1] → #5 DATA
+[2] → #15 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n17" data-id="17" transform="translate(246,483)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 Region
+Type not computed
+
+[0] → — DATA
+[1] → #6 CTRL
+[2] → #10 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n18" data-id="18" transform="translate(398,483)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #18</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 φ_a
+Type not computed
+
+[0] → #17 ASSOC
+[1] → #14 DATA
+[2] → #16 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #17</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g></g><g class="region-heads" style="opacity: 1;"><g class="region-head" transform="translate(144,171)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><title>If · 8 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #9"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g></g><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph3.gv b/docs/chapter05/05-graph3.gv
new file mode 100644
index 00000000..688c5ca9
--- /dev/null
+++ b/docs/chapter05/05-graph3.gv
@@ -0,0 +1,66 @@
+digraph chapter05 {
+/*
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else {
+ a = arg-3;
+
+}
+
+return a;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_7 [ label="#1" ];
+ EQNode8 [ label="==" ];
+ If9 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_13 [ label="#2" ];
+ Add14 [ label="+" ];
+ Con_15 [ label="#3" ];
+ Sub16 [ label="-" ];
+ Region17 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a18 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Return19 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Region17;Phi_a18;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return19[taillabel=0 color=red];
+ EQNode8 -> Start2:p1[taillabel=1];
+ EQNode8 -> Con_7[taillabel=2];
+ If9 -> Start2:p0[taillabel=0 color=red];
+ If9 -> EQNode8[taillabel=1];
+ Add14 -> Start2:p1[taillabel=1];
+ Add14 -> Con_13[taillabel=2];
+ Sub16 -> Start2:p1[taillabel=1];
+ Sub16 -> Con_15[taillabel=2];
+ Region17 -> If9:p0[taillabel=1 color=red];
+ Region17 -> If9:p1[taillabel=2 color=red];
+ Phi_a18 -> Region17 [style=dotted taillabel=0];
+ Phi_a18 -> Add14[taillabel=1];
+ Phi_a18 -> Sub16[taillabel=2];
+ Return19 -> Region17[taillabel=0 color=red];
+ Return19 -> Phi_a18[taillabel=1];
+}
diff --git a/docs/chapter05/05-graph3.json b/docs/chapter05/05-graph3.json
new file mode 100644
index 00000000..16d74821
--- /dev/null
+++ b/docs/chapter05/05-graph3.json
@@ -0,0 +1,28 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph3.svg",
+ "step": 1,
+ "roots": [],
+ "scope": 0,
+ "nodes": [
+ {"id": 1, "label": "$ctrl", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 2, "role": "CTRL", "label": null}], "proj": {"par": 2, "idx": 0}},
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 3, "label": "Stop", "type": null, "kind": "STOP", "edges": [{"idx": 0, "def": 19, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 4, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 5, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 0}},
+ {"id": 6, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 1}},
+ {"id": 7, "label": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 8, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 7, "role": "DATA", "label": null}], "proj": null},
+ {"id": 9, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 1, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}], "proj": null},
+ {"id": 13, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 14, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 13, "role": "DATA", "label": null}], "proj": null},
+ {"id": 15, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 16, "label": "-", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 15, "role": "DATA", "label": null}], "proj": null},
+ {"id": 17, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 5, "role": "CTRL", "label": null}, {"idx": 2, "def": 6, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 18, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 17, "role": "ASSOC", "label": null}, {"idx": 1, "def": 14, "role": "DATA", "label": null}, {"idx": 2, "def": 16, "role": "DATA", "label": null}], "proj": null},
+ {"id": 19, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 17, "role": "CTRL", "label": null}, {"idx": 1, "def": 18, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ {"id": 9, "par": 0, "nodes": [5, 6, 8, 9, 14, 16, 17, 18]}
+ ]
+}
diff --git a/docs/chapter05/05-graph3.svg b/docs/chapter05/05-graph3.svg
new file mode 100644
index 00000000..5a8b5706
--- /dev/null
+++ b/docs/chapter05/05-graph3.svg
@@ -0,0 +1,127 @@
+<svg aria-label="Compiler graph" width="760" height="752" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 760 752" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"><g class="region" transform="translate(144,171)"><rect class="region-box" rx="8" width="574" height="374" fill="#f2f7ef"/></g></g><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge CTRL" id="e3i0" d="M326,651 C326,675 380,678 380,702" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#3[0] → #19 · CTRL</title></path><path class="edge DATA" id="e8i1" d="M356,118 L356,123 Q356,128 351,128 L315,128 Q307,128 307,136 L307,225" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #4 · DATA</title></path><path class="edge DATA" id="e8i2" d="M84,118 L84,123 Q84,128 89,128 L218,128 Q226,128 226,136 L226,207 Q226,215 234,215 L332,215 Q337,215 337,220 L337,225" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge CTRL" id="e9i0" d="M236,118 L236,329" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#9[0] → #1 · CTRL</title></path><path class="edge DATA" id="e9i1" d="M307,281 L307,286.5 Q307,291 311.5,291 L311.5,291 Q316,291 316,295.5 L316,329" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #8 · DATA</title></path><path class="edge DATA" id="e14i1" d="M356,118 L356,123 Q356,128 361,128 L486,128 Q494,128 494,136 L494,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[1] → #4 · DATA</title></path><path class="edge DATA" id="e14i2" d="M524,118 L524,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[2] → #13 · DATA</title></path><path class="edge DATA" id="e16i1" d="M356,118 L356,123 Q356,128 361,128 L505,128 Q513,128 513,136 L513,283 Q513,291 521,291 L638,291 Q646,291 646,299 L646,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[1] → #4 · DATA</title></path><path class="edge DATA" id="e16i2" d="M676,118 L676,343.66666666666663" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[2] → #15 · DATA</title></path><path class="edge CTRL" id="e17i1" d="M216,429 L216,434 Q216,439 221,439 L298,439 Q306,439 306,447 L306,477" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[1] → #5 · CTRL</title></path><path class="edge CTRL" id="e17i2" d="M336,429 L336,477" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[2] → #6 · CTRL</title></path><path class="edge DATA" id="e18i1" d="M494,399.66666666666663 L494,431 Q494,439 486,439 L446,439 Q438,439 438,447 L438,477" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #14 · DATA</title></path><path class="edge DATA" id="e18i2" d="M646,399.66666666666663 L646,441 Q646,449 638,449 L486,449 Q478,449 478,457 L478,477" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[2] → #16 · DATA</title></path><path class="edge CTRL" id="e19i0" d="M306,533 L306,598" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#19[0] → #17 · CTRL</title></path><path class="edge DATA" id="e19i1" d="M458,533 L458,552 Q458,560 450,560 L354,560 Q346,560 346,568 L346,598" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#19[1] → #18 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n1" data-id="1" transform="translate(176,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>$ctrl</tspan><tspan class="node-id">  #1/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#1 $ctrl
+Projection 0 of #2
+Type not computed
+
+[0] → #2 CTRL</title></g><g class="node" id="n2" data-id="2" transform="translate(176,24)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n3" data-id="3" transform="translate(344,702)" style="opacity: 1;"><path class="box" d="M0,0H72V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="36" y="17"><tspan>Stop</tspan><tspan class="node-id">  #3</tspan></text><text class="type" text-anchor="middle" y="35" x="36"/><title>#3 Stop
+Type not computed
+
+[0] → #19 CTRL</title><circle class="port" cx="36" cy="0" r="3" fill="#536477"/><text class="slot" x="36" y="-7" text-anchor="middle">0</text></g><g class="node" id="n4" data-id="4" transform="translate(296,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #4/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n5" data-id="5" transform="translate(156,379)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #5/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#5 True
+Projection 0 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n6" data-id="6" transform="translate(276,379)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #6/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 False
+Projection 1 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n7" data-id="7" transform="translate(24,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#1</tspan><tspan class="node-id">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 #1
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(247,231)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #8</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#8 ==
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #7 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n9" data-id="9" transform="translate(156,335)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#9 If
+Type not computed
+
+[0] → #1 CTRL
+[1] → #8 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n13" data-id="13" transform="translate(464,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #13</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#13 #2
+Type not computed
+
+</title></g><g class="node" id="n14" data-id="14" transform="translate(434,349.66666666666663)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>+</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 +
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #13 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n15" data-id="15" transform="translate(616,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#15 #3
+Type not computed
+
+</title></g><g class="node" id="n16" data-id="16" transform="translate(586,349.66666666666663)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>-</tspan><tspan class="node-id">  #16</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 -
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #15 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n17" data-id="17" transform="translate(246,483)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 Region
+Type not computed
+
+[0] → — DATA
+[1] → #5 CTRL
+[2] → #6 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n18" data-id="18" transform="translate(398,483)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #18</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 φ_a
+Type not computed
+
+[0] → #17 ASSOC
+[1] → #14 DATA
+[2] → #16 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #17</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n19" data-id="19" transform="translate(266,604)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #19</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#19 Return
+Type not computed
+
+[0] → #17 CTRL
+[1] → #18 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"><g class="region-head" transform="translate(144,171)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><title>If · 8 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #9"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g></g><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph4.gv b/docs/chapter05/05-graph4.gv
new file mode 100644
index 00000000..88120b4a
--- /dev/null
+++ b/docs/chapter05/05-graph4.gv
@@ -0,0 +1,63 @@
+digraph chapter05 {
+/*
+int a=arg==2;
+if( arg==1 )
+{
+ a=arg==3;
+}
+return a;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_6 [ label="#2" ];
+ EQNode7 [ label="==" ];
+ Con_8 [ label="#1" ];
+ EQNode9 [ label="==" ];
+ If10 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_14 [ label="#3" ];
+ EQNode15 [ label="==" ];
+ Region16 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a17 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Return18 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Region16;Phi_a17;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return18[taillabel=0 color=red];
+ EQNode7 -> Start2:p1[taillabel=1];
+ EQNode7 -> Con_6[taillabel=2];
+ EQNode9 -> Start2:p1[taillabel=1];
+ EQNode9 -> Con_8[taillabel=2];
+ If10 -> Start2:p0[taillabel=0 color=red];
+ If10 -> EQNode9[taillabel=1];
+ EQNode15 -> Start2:p1[taillabel=1];
+ EQNode15 -> Con_14[taillabel=2];
+ Region16 -> If10:p0[taillabel=1 color=red];
+ Region16 -> If10:p1[taillabel=2 color=red];
+ Phi_a17 -> Region16 [style=dotted taillabel=0];
+ Phi_a17 -> EQNode15[taillabel=1];
+ Phi_a17 -> EQNode7[taillabel=2];
+ Return18 -> Region16[taillabel=0 color=red];
+ Return18 -> Phi_a17[taillabel=1];
+}
diff --git a/docs/chapter05/05-graph4.json b/docs/chapter05/05-graph4.json
new file mode 100644
index 00000000..a23b54f7
--- /dev/null
+++ b/docs/chapter05/05-graph4.json
@@ -0,0 +1,19 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph4.svg",
+ "step": 1,
+ "roots": [18],
+ "scope": 0,
+ "nodes": [
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 4, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 6, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 7, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 6, "role": "DATA", "label": null}], "proj": null},
+ {"id": 14, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 15, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 14, "role": "DATA", "label": null}], "proj": null},
+ {"id": 17, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 15, "role": "DATA", "label": null}, {"idx": 2, "def": 7, "role": "DATA", "label": null}], "proj": null},
+ {"id": 18, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 17, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter05/05-graph4.svg b/docs/chapter05/05-graph4.svg
new file mode 100644
index 00000000..45a3d3f3
--- /dev/null
+++ b/docs/chapter05/05-graph4.svg
@@ -0,0 +1,95 @@
+<svg aria-label="Compiler graph" width="478" height="454" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 478 454" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"/><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge DATA" id="e7i1" d="M84,118 L84,130 Q84,138 92,138 L228,138 Q236,138 236,146 L236,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#7[1] → #4 · DATA</title></path><path class="edge DATA" id="e7i2" d="M394,118 L394,123 Q394,128 389,128 L274,128 Q266,128 266,136 L266,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#7[2] → #6 · DATA</title></path><path class="edge DATA" id="e15i1" d="M84,118 L84,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#15[1] → #4 · DATA</title></path><path class="edge DATA" id="e15i2" d="M242,118 L242,123 Q242,128 237,128 L122,128 Q114,128 114,136 L114,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#15[2] → #14 · DATA</title></path><path class="edge DATA" id="e17i1" d="M84,222 L84,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[1] → #15 · DATA</title></path><path class="edge DATA" id="e17i2" d="M236,222 L236,227 Q236,232 231,232 L132,232 Q124,232 124,240 L124,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[2] → #7 · DATA</title></path><path class="edge DATA" id="e18i1" d="M104,326 L104,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #17 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n2" data-id="2" transform="translate(24,24)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n4" data-id="4" transform="translate(24,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #4/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n6" data-id="6" transform="translate(334,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #6</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 #2
+Type not computed
+
+</title></g><g class="node" id="n7" data-id="7" transform="translate(176,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 ==
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #6 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n14" data-id="14" transform="translate(182,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 #3
+Type not computed
+
+</title></g><g class="node" id="n15" data-id="15" transform="translate(24,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#15 ==
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #14 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n17" data-id="17" transform="translate(44,276)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 φ_a
+Type not computed
+
+[0] → — ASSOC
+[1] → #15 DATA
+[2] → #7 DATA</title><circle class="port" cx="0" cy="-3" r="3" fill="white"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="0" y="-10" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n18" data-id="18" transform="translate(24,380)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #18</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #17 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="white"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"/><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph5.gv b/docs/chapter05/05-graph5.gv
new file mode 100644
index 00000000..b03e90b5
--- /dev/null
+++ b/docs/chapter05/05-graph5.gv
@@ -0,0 +1,60 @@
+digraph chapter05 {
+/*
+int a=arg==2;
+if( arg==1 )
+{
+ a=arg==3;
+}
+return a;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_6 [ label="#2" ];
+ Con_8 [ label="#1" ];
+ EQNode9 [ label="==" ];
+ If10 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_14 [ label="#3" ];
+ Region16 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a19 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ EQNode20 [ label="==" ];
+ Return21 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Region16;Phi_a19;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return21[taillabel=0 color=red];
+ EQNode9 -> Start2:p1[taillabel=1];
+ EQNode9 -> Con_8[taillabel=2];
+ If10 -> Start2:p0[taillabel=0 color=red];
+ If10 -> EQNode9[taillabel=1];
+ Region16 -> If10:p0[taillabel=1 color=red];
+ Region16 -> If10:p1[taillabel=2 color=red];
+ Phi_a19 -> Region16 [style=dotted taillabel=0];
+ Phi_a19 -> Con_14[taillabel=1];
+ Phi_a19 -> Con_6[taillabel=2];
+ EQNode20 -> Start2:p1[taillabel=1];
+ EQNode20 -> Phi_a19[taillabel=2];
+ Return21 -> Region16[taillabel=0 color=red];
+ Return21 -> EQNode20[taillabel=1];
+}
diff --git a/docs/chapter05/05-graph5.json b/docs/chapter05/05-graph5.json
new file mode 100644
index 00000000..3bce2865
--- /dev/null
+++ b/docs/chapter05/05-graph5.json
@@ -0,0 +1,18 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph5.svg",
+ "step": 1,
+ "roots": [21],
+ "scope": 0,
+ "nodes": [
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 4, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 6, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 14, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 19, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 14, "role": "DATA", "label": null}, {"idx": 2, "def": 6, "role": "DATA", "label": null}], "proj": null},
+ {"id": 20, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 19, "role": "DATA", "label": null}], "proj": null},
+ {"id": 21, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 20, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter05/05-graph5.svg b/docs/chapter05/05-graph5.svg
new file mode 100644
index 00000000..df1144a9
--- /dev/null
+++ b/docs/chapter05/05-graph5.svg
@@ -0,0 +1,90 @@
+<svg aria-label="Compiler graph" width="369" height="448" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 369 448" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"/><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge DATA" id="e19i1" d="M133,74 L133,79 Q133,84 138,84 L237,84 Q245,84 245,92 L245,134.66666666666666" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#19[1] → #14 · DATA</title></path><path class="edge DATA" id="e19i2" d="M285,74 L285,134.66666666666666" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#19[2] → #6 · DATA</title></path><path class="edge DATA" id="e20i1" d="M104,216 L104,264" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[1] → #4 · DATA</title></path><path class="edge DATA" id="e20i2" d="M265,190.66666666666666 L265,218 Q265,226 257,226 L142,226 Q134,226 134,234 L134,264" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[2] → #19 · DATA</title></path><path class="edge DATA" id="e21i1" d="M104,320 L104,368" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#21[1] → #20 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n2" data-id="2" transform="translate(44,122)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n4" data-id="4" transform="translate(44,166)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #4/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n6" data-id="6" transform="translate(225,24)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #6</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 #2
+Type not computed
+
+</title></g><g class="node" id="n14" data-id="14" transform="translate(73,24)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 #3
+Type not computed
+
+</title></g><g class="node" id="n19" data-id="19" transform="translate(205,140.66666666666666)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #19</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#19 φ_a
+Type not computed
+
+[0] → — ASSOC
+[1] → #14 DATA
+[2] → #6 DATA</title><circle class="port" cx="0" cy="-3" r="3" fill="white"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="0" y="-10" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n20" data-id="20" transform="translate(44,270)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #20</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#20 ==
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #19 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n21" data-id="21" transform="translate(24,374)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #21</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#21 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #20 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="white"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"/><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph6.gv b/docs/chapter05/05-graph6.gv
new file mode 100644
index 00000000..1ad7b94a
--- /dev/null
+++ b/docs/chapter05/05-graph6.gv
@@ -0,0 +1,58 @@
+digraph chapter05 {
+/*
+int c = 3;
+int b = 2;
+if (arg == 1) {
+ b = 3;
+ c = 4;
+}
+return c;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_6 [ label="#3" ];
+ Con_8 [ label="#1" ];
+ EQNode9 [ label="==" ];
+ If10 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_15 [ label="#4" ];
+ Region16 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_c17 [ style=filled fillcolor=lightyellow label="&phi;_c" ];
+ Return19 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Region16;Phi_c17;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return19[taillabel=0 color=red];
+ EQNode9 -> Start2:p1[taillabel=1];
+ EQNode9 -> Con_8[taillabel=2];
+ If10 -> Start2:p0[taillabel=0 color=red];
+ If10 -> EQNode9[taillabel=1];
+ Region16 -> If10:p0[taillabel=1 color=red];
+ Region16 -> If10:p1[taillabel=2 color=red];
+ Phi_c17 -> Region16 [style=dotted taillabel=0];
+ Phi_c17 -> Con_15[taillabel=1];
+ Phi_c17 -> Con_6[taillabel=2];
+ Return19 -> Region16[taillabel=0 color=red];
+ Return19 -> Phi_c17[taillabel=1];
+}
diff --git a/docs/chapter05/05-graph6.json b/docs/chapter05/05-graph6.json
new file mode 100644
index 00000000..536b320c
--- /dev/null
+++ b/docs/chapter05/05-graph6.json
@@ -0,0 +1,15 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph6.svg",
+ "step": 1,
+ "roots": [19],
+ "scope": 0,
+ "nodes": [
+ {"id": 6, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 15, "label": "#4", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 17, "label": "φ_c", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 15, "role": "DATA", "label": null}, {"idx": 2, "def": 6, "role": "DATA", "label": null}], "proj": null},
+ {"id": 19, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 17, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter05/05-graph6.svg b/docs/chapter05/05-graph6.svg
new file mode 100644
index 00000000..f58a541f
--- /dev/null
+++ b/docs/chapter05/05-graph6.svg
@@ -0,0 +1,78 @@
+<svg aria-label="Compiler graph" width="320" height="306" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 320 306" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"/><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge DATA" id="e17i1" d="M84,74 L84,122" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[1] → #15 · DATA</title></path><path class="edge DATA" id="e17i2" d="M236,74 L236,79 Q236,84 231,84 L132,84 Q124,84 124,92 L124,122" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[2] → #6 · DATA</title></path><path class="edge DATA" id="e19i1" d="M104,178 L104,226" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#19[1] → #17 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n6" data-id="6" transform="translate(176,24)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #6</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 #3
+Type not computed
+
+</title></g><g class="node" id="n15" data-id="15" transform="translate(24,24)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#4</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#15 #4
+Type not computed
+
+</title></g><g class="node" id="n17" data-id="17" transform="translate(44,128)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_c</tspan><tspan class="node-id">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 φ_c
+Type not computed
+
+[0] → — ASSOC
+[1] → #15 DATA
+[2] → #6 DATA</title><circle class="port" cx="0" cy="-3" r="3" fill="white"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="0" y="-10" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n19" data-id="19" transform="translate(24,232)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #19</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#19 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #17 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="white"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"/><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph7.gv b/docs/chapter05/05-graph7.gv
new file mode 100644
index 00000000..3abd6455
--- /dev/null
+++ b/docs/chapter05/05-graph7.gv
@@ -0,0 +1,72 @@
+digraph chapter05 {
+/*
+int a=arg+1;
+int b=arg+2;
+if( arg==1 )
+ b=b+a;
+else
+ a=b+1;
+return a+b;
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Phi_b37 [ style=filled fillcolor=lightyellow label="&phi;_b" ];
+ Con_10 [ label="#1" ];
+ Add42 [ label="+" ];
+ EQNode11 [ label="==" ];
+ If12 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_46 [ label="#4" ];
+ Con_48 [ label="#5" ];
+ Phi_ab49 [ style=filled fillcolor=lightyellow label="&phi;_ab" ];
+ Add50 [ label="+" ];
+ Con_19 [ label="#2" ];
+ Return51 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ Mul20 [ label="*" ];
+ Region31 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ { rank=same; Region31;Phi_b37;Phi_ab49;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return51[taillabel=0 color=red];
+ Phi_b37 -> Region31 [style=dotted taillabel=0];
+ Phi_b37 -> Mul20[taillabel=1];
+ Phi_b37 -> Start2:p1[taillabel=2];
+ Add42 -> Phi_b37[taillabel=1];
+ Add42 -> Start2:p1[taillabel=2];
+ EQNode11 -> Start2:p1[taillabel=1];
+ EQNode11 -> Con_10[taillabel=2];
+ If12 -> Start2:p0[taillabel=0 color=red];
+ If12 -> EQNode11[taillabel=1];
+ Phi_ab49 -> Region31 [style=dotted taillabel=0];
+ Phi_ab49 -> Con_46[taillabel=1];
+ Phi_ab49 -> Con_48[taillabel=2];
+ Add50 -> Add42[taillabel=1];
+ Add50 -> Phi_ab49[taillabel=2];
+ Return51 -> Region31[taillabel=0 color=red];
+ Return51 -> Add50[taillabel=1];
+ Mul20 -> Start2:p1[taillabel=1];
+ Mul20 -> Con_19[taillabel=2];
+ Region31 -> If12:p0[taillabel=1 color=red];
+ Region31 -> If12:p1[taillabel=2 color=red];
+}
diff --git a/docs/chapter05/05-graph7.json b/docs/chapter05/05-graph7.json
new file mode 100644
index 00000000..2f4b4336
--- /dev/null
+++ b/docs/chapter05/05-graph7.json
@@ -0,0 +1,22 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph7.svg",
+ "step": 1,
+ "roots": [51],
+ "scope": 0,
+ "nodes": [
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 4, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 19, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 20, "label": "*", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 19, "role": "DATA", "label": null}], "proj": null},
+ {"id": 37, "label": "φ_b", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 20, "role": "DATA", "label": null}, {"idx": 2, "def": 4, "role": "DATA", "label": null}], "proj": null},
+ {"id": 42, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 37, "role": "DATA", "label": null}, {"idx": 2, "def": 4, "role": "DATA", "label": null}], "proj": null},
+ {"id": 46, "label": "#4", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 48, "label": "#5", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 49, "label": "φ_ab", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 46, "role": "DATA", "label": null}, {"idx": 2, "def": 48, "role": "DATA", "label": null}], "proj": null},
+ {"id": 50, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 42, "role": "DATA", "label": null}, {"idx": 2, "def": 49, "role": "DATA", "label": null}], "proj": null},
+ {"id": 51, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 50, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter05/05-graph7.svg b/docs/chapter05/05-graph7.svg
new file mode 100644
index 00000000..b121e1b9
--- /dev/null
+++ b/docs/chapter05/05-graph7.svg
@@ -0,0 +1,108 @@
+<svg aria-label="Compiler graph" width="577" height="662" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 577 662" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"/><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge DATA" id="e20i1" d="M236,118 L236,123 Q236,128 231,128 L154,128 Q146,128 146,136 L146,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[1] → #4 · DATA</title></path><path class="edge DATA" id="e20i2" d="M84,118 L84,130 Q84,138 92,138 L168,138 Q176,138 176,146 L176,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[2] → #19 · DATA</title></path><path class="edge DATA" id="e37i1" d="M146,222 L146,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#37[1] → #20 · DATA</title></path><path class="edge DATA" id="e37i2" d="M236,118 L236,224 Q236,232 228,232 L194,232 Q186,232 186,240 L186,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#37[2] → #4 · DATA</title></path><path class="edge DATA" id="e42i1" d="M166,326 L166,331 Q166,336 171,336 L198,336 Q206,336 206,344 L206,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#42[1] → #37 · DATA</title></path><path class="edge DATA" id="e42i2" d="M236,118 L236,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#42[2] → #4 · DATA</title></path><path class="edge DATA" id="e49i1" d="M341,326 L341,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#49[1] → #46 · DATA</title></path><path class="edge DATA" id="e49i2" d="M493,326 L493,331 Q493,336 488,336 L389,336 Q381,336 381,344 L381,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#49[2] → #48 · DATA</title></path><path class="edge DATA" id="e50i1" d="M206,430 L206,478" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#50[1] → #42 · DATA</title></path><path class="edge DATA" id="e50i2" d="M361,430 L361,435 Q361,440 356,440 L244,440 Q236,440 236,448 L236,478" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#50[2] → #49 · DATA</title></path><path class="edge DATA" id="e51i1" d="M206,534 L206,582" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#51[1] → #50 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n2" data-id="2" transform="translate(176,24)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n4" data-id="4" transform="translate(176,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #4/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n19" data-id="19" transform="translate(24,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #19</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#19 #2
+Type not computed
+
+</title></g><g class="node" id="n20" data-id="20" transform="translate(86,172)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>*</tspan><tspan class="node-id">  #20</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#20 *
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #19 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n37" data-id="37" transform="translate(106,276)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_b</tspan><tspan class="node-id">  #37</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#37 φ_b
+Type not computed
+
+[0] → — ASSOC
+[1] → #20 DATA
+[2] → #4 DATA</title><circle class="port" cx="0" cy="-3" r="3" fill="white"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="0" y="-10" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n42" data-id="42" transform="translate(146,380)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>+</tspan><tspan class="node-id">  #42</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#42 +
+Type not computed
+
+[0] → — DATA
+[1] → #37 DATA
+[2] → #4 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n46" data-id="46" transform="translate(281,276)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#4</tspan><tspan class="node-id">  #46</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#46 #4
+Type not computed
+
+</title></g><g class="node" id="n48" data-id="48" transform="translate(433,276)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#5</tspan><tspan class="node-id">  #48</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#48 #5
+Type not computed
+
+</title></g><g class="node" id="n49" data-id="49" transform="translate(301,380)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_ab</tspan><tspan class="node-id">  #49</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#49 φ_ab
+Type not computed
+
+[0] → — ASSOC
+[1] → #46 DATA
+[2] → #48 DATA</title><circle class="port" cx="0" cy="-3" r="3" fill="white"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="0" y="-10" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n50" data-id="50" transform="translate(146,484)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>+</tspan><tspan class="node-id">  #50</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#50 +
+Type not computed
+
+[0] → — DATA
+[1] → #42 DATA
+[2] → #49 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n51" data-id="51" transform="translate(126,588)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #51</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#51 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #50 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="white"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"/><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph8.gv b/docs/chapter05/05-graph8.gv
new file mode 100644
index 00000000..8f28207c
--- /dev/null
+++ b/docs/chapter05/05-graph8.gv
@@ -0,0 +1,129 @@
+digraph chapter05 {
+/*
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ subgraph cluster_Nodes {
+ Start2 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">Start</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">$ctrl</TD><TD PORT="p1">arg</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_7 [ label="#1" ];
+ EQNode8 [ label="==" ];
+ If9 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_13 [ label="#2" ];
+ EQNode14 [ label="==" ];
+ If15 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_19 [ label="#2" ];
+ Con_20 [ label="#3" ];
+ Region21 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a22 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Con_23 [ label="#3" ];
+ EQNode24 [ label="==" ];
+ If25 [ shape=plaintext label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0" CELLPADDING="4">
+ <TR><TD BGCOLOR="yellow">If</TD></TR>
+ <TR><TD>
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD PORT="p0" BGCOLOR="yellow">True</TD><TD PORT="p1" BGCOLOR="yellow">False</TD></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Con_29 [ label="#4" ];
+ Con_30 [ label="#5" ];
+ Region31 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a32 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Region33 [ shape=box style=filled fillcolor=yellow label="Region" ];
+ Phi_a34 [ style=filled fillcolor=lightyellow label="&phi;_a" ];
+ Return35 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Region21;Phi_a22;}
+ { rank=same; Region31;Phi_a32;}
+ { rank=same; Region33;Phi_a34;}
+ }
+ node [shape=plaintext];
+ subgraph cluster_Scope1_0 {
+ Scope1_0 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">0</TD><TD PORT="Scope1_0_$ctrl">$ctrl</TD><TD PORT="Scope1_0_arg">arg</TD></TR>
+ </TABLE>>];
+ subgraph cluster_Scope1_1 {
+ Scope1_1 [label=<
+ <TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
+ <TR><TD BGCOLOR="cyan">1</TD><TD PORT="Scope1_1_a">a</TD></TR>
+ </TABLE>>];
+ }
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return35[taillabel=0 color=red];
+ EQNode8 -> Start2:p1[taillabel=1];
+ EQNode8 -> Con_7[taillabel=2];
+ If9 -> Start2:p0[taillabel=0 color=red];
+ If9 -> EQNode8[taillabel=1];
+ EQNode14 -> Start2:p1[taillabel=1];
+ EQNode14 -> Con_13[taillabel=2];
+ If15 -> If9:p0[taillabel=0 color=red];
+ If15 -> EQNode14[taillabel=1];
+ Region21 -> If15:p0[taillabel=1 color=red];
+ Region21 -> If15:p1[taillabel=2 color=red];
+ Phi_a22 -> Region21 [style=dotted taillabel=0];
+ Phi_a22 -> Con_19[taillabel=1];
+ Phi_a22 -> Con_20[taillabel=2];
+ EQNode24 -> Start2:p1[taillabel=1];
+ EQNode24 -> Con_23[taillabel=2];
+ If25 -> If9:p1[taillabel=0 color=red];
+ If25 -> EQNode24[taillabel=1];
+ Region31 -> If25:p0[taillabel=1 color=red];
+ Region31 -> If25:p1[taillabel=2 color=red];
+ Phi_a32 -> Region31 [style=dotted taillabel=0];
+ Phi_a32 -> Con_29[taillabel=1];
+ Phi_a32 -> Con_30[taillabel=2];
+ Region33 -> Region21[taillabel=1 color=red];
+ Region33 -> Region31[taillabel=2 color=red];
+ Phi_a34 -> Region33 [style=dotted taillabel=0];
+ Phi_a34 -> Phi_a22[taillabel=1];
+ Phi_a34 -> Phi_a32[taillabel=2];
+ Return35 -> Region33[taillabel=0 color=red];
+ Return35 -> Phi_a34[taillabel=1];
+ edge [style=dashed color=cornflowerblue];
+ Scope1_0:"Scope1_0_arg" -> Start2:p1;
+ Scope1_1:"Scope1_1_a" -> Phi_a34;
+}
diff --git a/docs/chapter05/05-graph8.json b/docs/chapter05/05-graph8.json
new file mode 100644
index 00000000..887d1e8a
--- /dev/null
+++ b/docs/chapter05/05-graph8.json
@@ -0,0 +1,45 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph8.svg",
+ "step": 1,
+ "roots": [],
+ "scope": 0,
+ "nodes": [
+ {"id": 1, "label": "Scope", "type": null, "kind": "SCOPE", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": "0: $ctrl"}, {"idx": 1, "def": 6, "role": "ASSOC", "label": "0: arg"}, {"idx": 2, "def": 34, "role": "ASSOC", "label": "1: a"}], "proj": null},
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 3, "label": "Stop", "type": null, "kind": "STOP", "edges": [{"idx": 0, "def": 35, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 5, "label": "$ctrl", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 2, "role": "CTRL", "label": null}], "proj": {"par": 2, "idx": 0}},
+ {"id": 6, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 7, "label": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 8, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 6, "role": "DATA", "label": null}, {"idx": 2, "def": 7, "role": "DATA", "label": null}], "proj": null},
+ {"id": 9, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 5, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}], "proj": null},
+ {"id": 10, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 0}},
+ {"id": 11, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 9, "role": "CTRL", "label": null}], "proj": {"par": 9, "idx": 1}},
+ {"id": 12, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 15, "role": "CTRL", "label": null}], "proj": {"par": 15, "idx": 0}},
+ {"id": 13, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 14, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 6, "role": "DATA", "label": null}, {"idx": 2, "def": 13, "role": "DATA", "label": null}], "proj": null},
+ {"id": 15, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 10, "role": "CTRL", "label": null}, {"idx": 1, "def": 14, "role": "DATA", "label": null}], "proj": null},
+ {"id": 16, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 15, "role": "CTRL", "label": null}], "proj": {"par": 15, "idx": 1}},
+ {"id": 17, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 25, "role": "CTRL", "label": null}], "proj": {"par": 25, "idx": 0}},
+ {"id": 18, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 25, "role": "CTRL", "label": null}], "proj": {"par": 25, "idx": 1}},
+ {"id": 19, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 20, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 21, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 12, "role": "CTRL", "label": null}, {"idx": 2, "def": 16, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 22, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 21, "role": "ASSOC", "label": null}, {"idx": 1, "def": 19, "role": "DATA", "label": null}, {"idx": 2, "def": 20, "role": "DATA", "label": null}], "proj": null},
+ {"id": 23, "label": "#3", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 24, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 6, "role": "DATA", "label": null}, {"idx": 2, "def": 23, "role": "DATA", "label": null}], "proj": null},
+ {"id": 25, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 11, "role": "CTRL", "label": null}, {"idx": 1, "def": 24, "role": "DATA", "label": null}], "proj": null},
+ {"id": 29, "label": "#4", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 30, "label": "#5", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 31, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 17, "role": "CTRL", "label": null}, {"idx": 2, "def": 18, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 32, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 31, "role": "ASSOC", "label": null}, {"idx": 1, "def": 29, "role": "DATA", "label": null}, {"idx": 2, "def": 30, "role": "DATA", "label": null}], "proj": null},
+ {"id": 33, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 21, "role": "CTRL", "label": null}, {"idx": 2, "def": 31, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 34, "label": "φ_a", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 33, "role": "ASSOC", "label": null}, {"idx": 1, "def": 22, "role": "DATA", "label": null}, {"idx": 2, "def": 32, "role": "DATA", "label": null}], "proj": null},
+ {"id": 35, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 33, "role": "CTRL", "label": null}, {"idx": 1, "def": 34, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ {"id": 9, "par": 0, "nodes": [8, 9, 10, 11, 33, 34]},
+ {"id": 15, "par": 9, "nodes": [12, 14, 15, 16, 21, 22]},
+ {"id": 25, "par": 9, "nodes": [17, 18, 24, 25, 31, 32]}
+ ]
+}
diff --git a/docs/chapter05/05-graph8.svg b/docs/chapter05/05-graph8.svg
new file mode 100644
index 00000000..b1b4da5c
--- /dev/null
+++ b/docs/chapter05/05-graph8.svg
@@ -0,0 +1,188 @@
+<svg aria-label="Compiler graph" width="1594" height="1208" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1594 1208" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"><g class="region" transform="translate(61,193)"><rect class="region-box" rx="8" width="826" height="808" fill="#f2f7ef"/></g><g class="region" transform="translate(73,506)"><rect class="region-box" rx="8" width="410" height="374" fill="#f2f7ef"/></g><g class="region" transform="translate(515,511.7142857142857)"><rect class="region-box" rx="8" width="360" height="354" fill="#f2f7ef"/></g></g><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge ASSOC" id="e1i1" d="M356,115 C356,139 1494.5,0 1494.5,24" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[1] → #6 · ASSOC · 0: arg</title></path><path class="edge ASSOC" id="e1i2" d="M431,986 C431,1010 1546,0 1546,24" stroke="#9396a3" marker-start="url(#arrow-ASSOC)" style="opacity: 1;"><title>#1[2] → #34 · ASSOC · 1: a</title></path><path class="edge CTRL" id="e3i0" d="M299,1107 C299,1131 797,1134 797,1158" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#3[0] → #35 · CTRL</title></path><path class="edge DATA" id="e8i1" d="M356,118 L356,123 Q356,128 351,128 L349,128 Q342,128 342,135 L342,247" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #6 · DATA</title></path><path class="edge DATA" id="e8i2" d="M514,118 L514,123 Q514,128 509,128 L430,128 Q422,128 422,136 L422,229 Q422,237 414,237 L377,237 Q372,237 372,242 L372,247" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge CTRL" id="e9i0" d="M236,118 L236,351" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#9[0] → #5 · CTRL</title></path><path class="edge DATA" id="e9i1" d="M342,303 L342,308 Q342,313 337,313 L324,313 Q316,313 316,321 L316,351" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #8 · DATA</title></path><path class="edge DATA" id="e14i1" d="M356,118 L356,123 Q356,128 351,128 L255,128 Q247,128 247,136 L247,305 Q247,313 239,313 L153,313 Q145,313 145,321 L145,560" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[1] → #6 · DATA</title></path><path class="edge DATA" id="e14i2" d="M84,118 L84,123 Q84,128 89,128 L126,128 Q134,128 134,136 L134,460.5 Q134,461 134.5,461 L134.5,461 Q135,461 135,461.5 L135,542 Q135,550 143,550 L170,550 Q175,550 175,555 L175,560" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#14[2] → #13 · DATA</title></path><path class="edge CTRL" id="e15i0" d="M216,451 L216,460.5 Q216,461 215.5,461 L215.5,461 Q215,461 215,461.5 L215,664" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#15[0] → #10 · CTRL</title></path><path class="edge DATA" id="e15i1" d="M145,616 L145,621 Q145,626 150,626 L287,626 Q295,626 295,634 L295,664" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#15[1] → #14 · DATA</title></path><path class="edge CTRL" id="e21i1" d="M195,764 L195,769 Q195,774 200,774 L251,774 Q259,774 259,782 L259,812" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#21[1] → #12 · CTRL</title></path><path class="edge CTRL" id="e21i2" d="M315,764 L315,769 Q315,774 310,774 L297,774 Q289,774 289,782 L289,812" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#21[2] → #16 · CTRL</title></path><path class="edge DATA" id="e22i1" d="M666,118 L666,130 Q666,138 658,138 L440,138 Q432,138 432,146 L432,463 Q432,471 424,471 L399,471 Q391,471 391,479 L391,812" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#22[1] → #19 · DATA</title></path><path class="edge DATA" id="e22i2" d="M818,118 L818,140 Q818,148 810,148 L451,148 Q443,148 443,156 L443,475 Q443,481 437,481 L437,481 Q431,481 431,487 L431,812" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#22[2] → #20 · DATA</title></path><path class="edge DATA" id="e24i1" d="M356,118 L356,123 Q356,128 361,128 L404,128 Q412,128 412,136 L412,453 Q412,461 420,461 L679,461 Q687,461 687,469 L687,545.7142857142858" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#24[1] → #6 · DATA</title></path><path class="edge DATA" id="e24i2" d="M970,118 L970,150 Q970,158 962,158 L725,158 Q717,158 717,166 L717,545.7142857142858" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#24[2] → #23 · DATA</title></path><path class="edge CTRL" id="e25i0" d="M336,451 L336,483 Q336,491 344,491 L599,491 Q607,491 607,499 L607,649.7142857142858" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#25[0] → #11 · CTRL</title></path><path class="edge DATA" id="e25i1" d="M687,601.7142857142858 L687,649.7142857142858" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#25[1] → #24 · DATA</title></path><path class="edge CTRL" id="e31i1" d="M587,749.7142857142858 L587,754.7142857142858 Q587,759.7142857142858 592,759.7142857142858 L643,759.7142857142858 Q651,759.7142857142858 651,767.7142857142858 L651,797.7142857142858" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#31[1] → #17 · CTRL</title></path><path class="edge CTRL" id="e31i2" d="M707,749.7142857142858 L707,754.7142857142858 Q707,759.7142857142858 702,759.7142857142858 L689,759.7142857142858 Q681,759.7142857142858 681,767.7142857142858 L681,797.7142857142858" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#31[2] → #18 · CTRL</title></path><path class="edge DATA" id="e32i1" d="M1122,118 L1122,160 Q1122,168 1114,168 L791,168 Q783,168 783,176 L783,797.7142857142858" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#32[1] → #29 · DATA</title></path><path class="edge DATA" id="e32i2" d="M1274,118 L1274,170 Q1274,178 1266,178 L831,178 Q823,178 823,186 L823,797.7142857142858" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#32[2] → #30 · DATA</title></path><path class="edge CTRL" id="e33i1" d="M259,868 L259,887 Q259,895 267,895 L271,895 Q279,895 279,903 L279,933" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#33[1] → #21 · CTRL</title></path><path class="edge CTRL" id="e33i2" d="M651,853.7142857142858 L651,887 Q651,895 643,895 L317,895 Q309,895 309,903 L309,933" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#33[2] → #31 · CTRL</title></path><path class="edge DATA" id="e34i1" d="M411,868 L411,933" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#34[1] → #22 · DATA</title></path><path class="edge DATA" id="e34i2" d="M803,853.7142857142858 L803,897 Q803,905 795,905 L459,905 Q451,905 451,913 L451,933" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#34[2] → #32 · DATA</title></path><path class="edge CTRL" id="e35i0" d="M279,989 L279,1054" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#35[0] → #33 · CTRL</title></path><path class="edge DATA" id="e35i1" d="M431,989 L431,1008 Q431,1016 423,1016 L327,1016 Q319,1016 319,1024 L319,1054" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#35[1] → #34 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n1" data-id="1" transform="translate(1406,24)" style="opacity: 1;"><path class="box" d="M4,0H160Q164,0 164,4V52Q164,56 160,56H4Q0,56 0,52V4Q0,0 4,0Z" fill="#e5e0ff"/><text class="label" text-anchor="middle" x="82" y="48"><tspan>Scope</tspan><tspan class="node-id">  #1</tspan></text><text class="type" text-anchor="middle" y="35" x="82"/><title>#1 Scope
+Type not computed
+
+[0] → — ASSOC 0: $ctrl
+[1] → #6 ASSOC 0: arg
+[2] → #34 ASSOC 1: a</title><line class="row" x1="0" x2="164" y1="30" y2="30"/><line class="row" x1="61" x2="61" y1="0" y2="30"/><line class="row" x1="116" x2="116" y1="0" y2="30"/><text class="bind" x="30.5" y="20" text-anchor="middle">0: $ctrl</text><text class="bind" x="88.5" y="20" text-anchor="middle">0: arg</text><text class="bind" x="140" y="20" text-anchor="middle">1: a</text><circle class="port" cx="30.5" cy="0" r="3" fill="white"/><circle class="port" cx="88.5" cy="0" r="3" fill="#536477"/><circle class="port" cx="140" cy="0" r="3" fill="#536477"/><text class="slot" x="30.5" y="-7" text-anchor="middle">0</text><text class="slot" x="88.5" y="-7" text-anchor="middle">1</text><text class="slot" x="140" y="-7" text-anchor="middle">2</text></g><g class="node" id="n2" data-id="2" transform="translate(176,24)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n3" data-id="3" transform="translate(761,1158)" style="opacity: 1;"><path class="box" d="M0,0H72V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="36" y="17"><tspan>Stop</tspan><tspan class="node-id">  #3</tspan></text><text class="type" text-anchor="middle" y="35" x="36"/><title>#3 Stop
+Type not computed
+
+[0] → #35 CTRL</title><circle class="port" cx="36" cy="0" r="3" fill="#536477"/><text class="slot" x="36" y="-7" text-anchor="middle">0</text></g><g class="node" id="n5" data-id="5" transform="translate(176,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>$ctrl</tspan><tspan class="node-id">  #5/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#5 $ctrl
+Projection 0 of #2
+Type not computed
+
+[0] → #2 CTRL</title></g><g class="node" id="n6" data-id="6" transform="translate(296,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #6/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n7" data-id="7" transform="translate(454,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#1</tspan><tspan class="node-id">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 #1
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(282,253)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #8</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#8 ==
+Type not computed
+
+[0] → — DATA
+[1] → #6 DATA
+[2] → #7 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n9" data-id="9" transform="translate(156,357)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#9 If
+Type not computed
+
+[0] → #5 CTRL
+[1] → #8 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n10" data-id="10" transform="translate(156,401)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #10/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#10 True
+Projection 0 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n11" data-id="11" transform="translate(276,401)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #11/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#11 False
+Projection 1 of #9
+Type not computed
+
+[0] → #9 CTRL</title></g><g class="node" id="n12" data-id="12" transform="translate(135,714)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #12/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#12 True
+Projection 0 of #15
+Type not computed
+
+[0] → #15 CTRL</title></g><g class="node" id="n13" data-id="13" transform="translate(24,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #13</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#13 #2
+Type not computed
+
+</title></g><g class="node" id="n14" data-id="14" transform="translate(85,566)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 ==
+Type not computed
+
+[0] → — DATA
+[1] → #6 DATA
+[2] → #13 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n15" data-id="15" transform="translate(135,670)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #15</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#15 If
+Type not computed
+
+[0] → #10 CTRL
+[1] → #14 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n16" data-id="16" transform="translate(255,714)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #16/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 False
+Projection 1 of #15
+Type not computed
+
+[0] → #15 CTRL</title></g><g class="node" id="n17" data-id="17" transform="translate(527,699.7142857142858)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #17/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 True
+Projection 0 of #25
+Type not computed
+
+[0] → #25 CTRL</title></g><g class="node" id="n18" data-id="18" transform="translate(647,699.7142857142858)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #18/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 False
+Projection 1 of #25
+Type not computed
+
+[0] → #25 CTRL</title></g><g class="node" id="n19" data-id="19" transform="translate(606,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#2</tspan><tspan class="node-id">  #19</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#19 #2
+Type not computed
+
+</title></g><g class="node" id="n20" data-id="20" transform="translate(758,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #20</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#20 #3
+Type not computed
+
+</title></g><g class="node" id="n21" data-id="21" transform="translate(199,818)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #21</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#21 Region
+Type not computed
+
+[0] → — DATA
+[1] → #12 CTRL
+[2] → #16 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n22" data-id="22" transform="translate(351,818)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #22</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#22 φ_a
+Type not computed
+
+[0] → #21 ASSOC
+[1] → #19 DATA
+[2] → #20 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #21</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n23" data-id="23" transform="translate(910,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#3</tspan><tspan class="node-id">  #23</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#23 #3
+Type not computed
+
+</title></g><g class="node" id="n24" data-id="24" transform="translate(627,551.7142857142858)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #24</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#24 ==
+Type not computed
+
+[0] → — DATA
+[1] → #6 DATA
+[2] → #23 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n25" data-id="25" transform="translate(527,655.7142857142858)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #25</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#25 If
+Type not computed
+
+[0] → #11 CTRL
+[1] → #24 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n29" data-id="29" transform="translate(1062,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#4</tspan><tspan class="node-id">  #29</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#29 #4
+Type not computed
+
+</title></g><g class="node" id="n30" data-id="30" transform="translate(1214,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>#5</tspan><tspan class="node-id">  #30</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#30 #5
+Type not computed
+
+</title></g><g class="node" id="n31" data-id="31" transform="translate(591,803.7142857142858)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #31</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#31 Region
+Type not computed
+
+[0] → — DATA
+[1] → #17 CTRL
+[2] → #18 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n32" data-id="32" transform="translate(743,803.7142857142858)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #32</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#32 φ_a
+Type not computed
+
+[0] → #31 ASSOC
+[1] → #29 DATA
+[2] → #30 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #31</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n33" data-id="33" transform="translate(219,939)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #33</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#33 Region
+Type not computed
+
+[0] → — DATA
+[1] → #21 CTRL
+[2] → #31 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n34" data-id="34" transform="translate(371,939)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_a</tspan><tspan class="node-id">  #34</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#34 φ_a
+Type not computed
+
+[0] → #33 ASSOC
+[1] → #22 DATA
+[2] → #32 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #33</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n35" data-id="35" transform="translate(239,1060)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #35</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#35 Return
+Type not computed
+
+[0] → #33 CTRL
+[1] → #34 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"><g class="region-head" transform="translate(61,193)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #9</tspan></text><title>If · 18 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #9"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g><g class="region-head" transform="translate(73,506)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #15</tspan></text><title>If · 6 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #15"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g><g class="region-head" transform="translate(515,511.7142857142857)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #25</tspan></text><title>If · 6 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #25"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g></g><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/05-graph9.json b/docs/chapter05/05-graph9.json
new file mode 100644
index 00000000..deb1b540
--- /dev/null
+++ b/docs/chapter05/05-graph9.json
@@ -0,0 +1,26 @@
+{
+ "ver": 1,
+ "comp": "chapter05/docs/05-graph9.svg",
+ "step": 1,
+ "roots": [],
+ "scope": 0,
+ "nodes": [
+ {"id": 1, "label": "$ctrl", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 2, "role": "CTRL", "label": null}], "proj": {"par": 2, "idx": 0}},
+ {"id": 2, "label": "Start", "type": null, "kind": "CTRL", "edges": [], "proj": null},
+ {"id": 3, "label": "Stop", "type": null, "kind": "STOP", "edges": [{"idx": 0, "def": 20, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 4, "label": "arg", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 2, "role": "DATA", "label": null}], "proj": {"par": 2, "idx": 1}},
+ {"id": 5, "label": "True", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 10, "role": "CTRL", "label": null}], "proj": {"par": 10, "idx": 0}},
+ {"id": 6, "label": "False", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 10, "role": "CTRL", "label": null}], "proj": {"par": 10, "idx": 1}},
+ {"id": 8, "label": "1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 9, "label": "==", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 8, "role": "DATA", "label": null}], "proj": null},
+ {"id": 10, "label": "If", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 1, "role": "CTRL", "label": null}, {"idx": 1, "def": 9, "role": "DATA", "label": null}], "proj": null},
+ {"id": 14, "label": "2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 16, "label": "1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 17, "label": "Region", "type": null, "kind": "REGION", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 5, "role": "CTRL", "label": null}, {"idx": 2, "def": 6, "role": "CTRL", "label": null}], "proj": null},
+ {"id": 18, "label": "φ_b", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 17, "role": "ASSOC", "label": null}, {"idx": 1, "def": 14, "role": "DATA", "label": null}, {"idx": 2, "def": 16, "role": "DATA", "label": null}], "proj": null},
+ {"id": 20, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 17, "role": "CTRL", "label": null}, {"idx": 1, "def": 18, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ {"id": 10, "par": 0, "nodes": [5, 6, 9, 10, 17, 18]}
+ ]
+}
diff --git a/docs/chapter05/05-graph9.svg b/docs/chapter05/05-graph9.svg
new file mode 100644
index 00000000..d0f62b69
--- /dev/null
+++ b/docs/chapter05/05-graph9.svg
@@ -0,0 +1,117 @@
+<svg aria-label="Compiler graph" width="782" height="734" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 782 734" style="font-family: sans-serif;"><style>
+ html, body { height:100%; margin:0; font-family:sans-serif; }
+ .viewer { height:100%; display:grid; grid-template-rows:auto minmax(0,1fr) auto; }
+ .source { padding:8px; border-bottom:1px solid #ccc; }
+ #program { width:min(600px,80vw); vertical-align:middle; }
+ #status { margin-top:4px; }
+ #graph { min-height:0; overflow:hidden; position:relative; background:#fafbfc; }
+ #elk { width:100%; height:100%; }
+ #graph svg { display:block; }
+ .tools { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:8px; font-size:12px; }
+ .hint { color:#616c78; }
+ .ctrl { color:#b63838; } .mem { color:#2867b2; } .data { color:#536477; }
+ .edge { fill:none; stroke-width:1.5; }
+ .edge.CTRL { stroke-width:2; }
+ .edge.ASSOC { stroke-dasharray:4 4; }
+ .edge.PARSER { stroke-dasharray:5 4; }
+ .parser rect { fill:#f6f0ff; stroke:#7956a5; stroke-width:1.5; stroke-dasharray:5 4; }
+ .edge.selected { stroke-width:3.5; }
+ .edge.bundle { stroke-width:4; }
+ .edge.bundle.selected { stroke-width:6; }
+ .edge-hit { fill:none; stroke:transparent; stroke-width:12; vector-effect:non-scaling-stroke; pointer-events:stroke; cursor:pointer; }
+ .edge-jump { fill:transparent; pointer-events:all; cursor:pointer; }
+ .node { cursor:pointer; }
+ .box { stroke:#758191; stroke-width:1; }
+ .node.held .box { stroke-dasharray:5 3; }
+ .node.near .box { stroke:#c18221; stroke-width:2; }
+ .node.focus .box { stroke:#9c4900; stroke-width:3; }
+ .node.selected .box { stroke:#1569b9; stroke-width:3; }
+ .node.folded .box { stroke-width:4; }
+ .node.folding .box { fill:#f4ccd7; }
+ .fold-tag { font-size:9px; font-weight:700; fill:#963751; }
+ .peep-area { fill:#fff3d9; fill-opacity:.8; stroke:#c18221; stroke-width:2; pointer-events:none; }
+ .node.peep-edit .box { stroke:#9c4900; stroke-width:3; }
+ .node.error .box { stroke:#b42318; stroke-width:4; }
+ #event.error { color:#b42318; font-weight:600; white-space:pre-wrap; overflow-wrap:anywhere; }
+ .peep-ghosts { pointer-events:none; }
+ .region-box { stroke:#9da9b8; stroke-width:1.5; }
+ .fold-btn { cursor:pointer; }
+ .fold-btn rect { fill:white; stroke:#596674; }
+ .fold-btn text { font-size:14px; fill:#152330; }
+ .fold-btn:focus rect { stroke:#1569b9; stroke-width:2; }
+ .shortcut { cursor:pointer; }
+ .shortcut path { fill:none; stroke-width:1.5; }
+ .shortcut rect { fill:#fff8ec; stroke:#b63838; stroke-dasharray:3 2; }
+ .shortcut text { font-size:11px; fill:#783030; }
+ .shortcut.selected rect, .shortcut:focus rect { stroke-width:2.5; }
+ .label { font-size:12px; fill:#152330; font-weight:600; }
+ .node-id { font-size:10px; fill:#596674; font-weight:400; }
+ .type { font-size:11px; fill:#455768; }
+ .port { stroke:#536477; stroke-width:1; }
+ .row { stroke:#b6afcf; stroke-width:1; }
+ .bind { font-size:12px; fill:#152330; }
+ .slot { font-size:10px; fill:#364352; paint-order:stroke; stroke:#fafbfc; stroke-width:3; }
+ #detail { position:absolute; top:8px; right:8px; margin:0; padding:12px; max-width:320px;
+ max-height:45%; overflow:auto; white-space:pre-wrap; overflow-wrap:anywhere;
+ background:#fffffff2; border:1px solid #bac5d0; border-radius:4px; font-size:12px; }
+ .controls { display:flex; flex-wrap:wrap; justify-content:center; align-items:center; gap:6px; padding:6px; }
+ .button { color:white; background:black; font-size:20px; min-width:30px; }
+ .button:disabled { background:grey; }
+ .count { font-size:20px; min-width:35px; text-align:center; }
+ #N { width:6ch; }
+ #scrub { width:clamp(120px,35vw,600px); }
+ </style><defs><marker id="arrow-CTRL" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#b63838"/></marker><marker id="arrow-DATA" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#536477"/></marker><marker id="arrow-MEM" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#2867b2"/></marker><marker id="arrow-ASSOC" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#9396a3"/></marker><marker id="arrow-PARSER" viewBox="0 -4 8 8" refX="8" refY="0" markerWidth="7" markerHeight="7" orient="auto-start-reverse"><path d="M0,-4L8,0L0,4Z" fill="#7956a5"/></marker></defs><rect width="100%" height="100%" fill="rgb(250, 251, 252)"/><g><g class="regions" style="opacity: 1;"><g class="region" transform="translate(24,173)"><rect class="region-box" rx="8" width="360" height="354" fill="#f2f7ef"/></g></g><rect class="peep-area" rx="36" style="opacity: 0;"/><g class="edges"><path class="edge CTRL" id="e3i0" d="M180,633 C180,657 391,660 391,684" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#3[0] → #20 · CTRL</title></path><path class="edge DATA" id="e9i1" d="M236,118 L236,123 Q236,128 231,128 L204,128 Q196,128 196,136 L196,207" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #4 · DATA</title></path><path class="edge DATA" id="e9i2" d="M394,118 L394,130 Q394,138 386,138 L234,138 Q226,138 226,146 L226,207" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[2] → #8 · DATA</title></path><path class="edge CTRL" id="e10i0" d="M116,118 L116,311" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#10[0] → #1 · CTRL</title></path><path class="edge DATA" id="e10i1" d="M196,263 L196,311" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#10[1] → #9 · DATA</title></path><path class="edge CTRL" id="e17i1" d="M96,411 L96,416 Q96,421 101,421 L152,421 Q160,421 160,429 L160,459" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[1] → #5 · CTRL</title></path><path class="edge CTRL" id="e17i2" d="M216,411 L216,416 Q216,421 211,421 L198,421 Q190,421 190,429 L190,459" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#17[2] → #6 · CTRL</title></path><path class="edge DATA" id="e18i1" d="M546,118 L546,140 Q546,148 538,148 L300,148 Q292,148 292,156 L292,459" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #14 · DATA</title></path><path class="edge DATA" id="e18i2" d="M698,118 L698,150 Q698,158 690,158 L340,158 Q332,158 332,166 L332,459" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[2] → #16 · DATA</title></path><path class="edge CTRL" id="e20i0" d="M160,515 L160,580" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#20[0] → #17 · CTRL</title></path><path class="edge DATA" id="e20i1" d="M312,515 L312,534 Q312,542 304,542 L208,542 Q200,542 200,550 L200,580" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[1] → #18 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n1" data-id="1" transform="translate(56,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>$ctrl</tspan><tspan class="node-id">  #1/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#1 $ctrl
+Projection 0 of #2
+Type not computed
+
+[0] → #2 CTRL</title></g><g class="node" id="n2" data-id="2" transform="translate(56,24)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>Start</tspan><tspan class="node-id">  #2</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#2 Start
+Type not computed
+
+</title></g><g class="node" id="n3" data-id="3" transform="translate(355,684)" style="opacity: 1;"><path class="box" d="M0,0H72V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="36" y="17"><tspan>Stop</tspan><tspan class="node-id">  #3</tspan></text><text class="type" text-anchor="middle" y="35" x="36"/><title>#3 Stop
+Type not computed
+
+[0] → #20 CTRL</title><circle class="port" cx="36" cy="0" r="3" fill="#536477"/><text class="slot" x="36" y="-7" text-anchor="middle">0</text></g><g class="node" id="n4" data-id="4" transform="translate(176,68)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>arg</tspan><tspan class="node-id">  #4/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#4 arg
+Projection 1 of #2
+Type not computed
+
+[0] → #2 DATA</title></g><g class="node" id="n5" data-id="5" transform="translate(36,361)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>True</tspan><tspan class="node-id">  #5/0</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#5 True
+Projection 0 of #10
+Type not computed
+
+[0] → #10 CTRL</title></g><g class="node" id="n6" data-id="6" transform="translate(156,361)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>False</tspan><tspan class="node-id">  #6/1</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 False
+Projection 1 of #10
+Type not computed
+
+[0] → #10 CTRL</title></g><g class="node" id="n8" data-id="8" transform="translate(334,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>1</tspan><tspan class="node-id">  #8</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#8 1
+Type not computed
+
+</title></g><g class="node" id="n9" data-id="9" transform="translate(136,213)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>==</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#9 ==
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #8 DATA</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n10" data-id="10" transform="translate(36,317)" style="opacity: 1;"><path class="box" d="M0,0H240V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="120" y="18"><tspan>If</tspan><tspan class="node-id">  #10</tspan></text><text class="type" text-anchor="middle" y="35" x="120"/><title>#10 If
+Type not computed
+
+[0] → #1 CTRL
+[1] → #9 DATA</title><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><circle class="port" cx="160" cy="-3" r="3" fill="#536477"/><text class="slot" x="80" y="-10" text-anchor="middle">0</text><text class="slot" x="160" y="-10" text-anchor="middle">1</text></g><g class="node" id="n14" data-id="14" transform="translate(486,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>2</tspan><tspan class="node-id">  #14</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#14 2
+Type not computed
+
+</title></g><g class="node" id="n16" data-id="16" transform="translate(638,68)" style="opacity: 1;"><path class="box" d="M14,0H106Q120,0 120,14V30Q120,44 106,44H14Q0,44 0,30V14Q0,0 14,0Z" fill="#edf3f7"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>1</tspan><tspan class="node-id">  #16</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 1
+Type not computed
+
+</title></g><g class="node" id="n17" data-id="17" transform="translate(100,465)" style="opacity: 1;"><path class="box" d="M12,0H108L120,44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Region</tspan><tspan class="node-id">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 Region
+Type not computed
+
+[0] → — DATA
+[1] → #5 CTRL
+[2] → #6 CTRL</title><circle class="port" cx="30" cy="-3" r="3" fill="white"/><circle class="port" cx="60" cy="-3" r="3" fill="#536477"/><circle class="port" cx="90" cy="-3" r="3" fill="#536477"/><text class="slot" x="30" y="-10" text-anchor="middle">0</text><text class="slot" x="60" y="-10" text-anchor="middle">1</text><text class="slot" x="90" y="-10" text-anchor="middle">2</text></g><g class="node" id="n18" data-id="18" transform="translate(252,465)" style="opacity: 1;"><path class="box" d="M12,0H108L120,22L108,44H12L0,22Z" fill="#f5e4fa"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>φ_b</tspan><tspan class="node-id">  #18</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 φ_b
+Type not computed
+
+[0] → #17 ASSOC
+[1] → #14 DATA
+[2] → #16 DATA</title><circle class="port" cx="-3" cy="22" r="3" fill="#536477"/><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><path class="reg" fill="none" stroke="#b63838" d="M-3,22H-18m4,-3l-4,3l4,3"><title>[0] → #17</title></path><text class="slot" x="-10" y="15" text-anchor="middle">0</text><text class="slot" x="40" y="-10" text-anchor="middle">1</text><text class="slot" x="80" y="-10" text-anchor="middle">2</text></g><g class="node" id="n20" data-id="20" transform="translate(120,586)" style="opacity: 1;"><path class="box" d="M0,0H120V44H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="60" y="18"><tspan>Return</tspan><tspan class="node-id">  #20</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#20 Return
+Type not computed
+
+[0] → #17 CTRL
+[1] → #18 DATA</title><circle class="port" cx="40" cy="-3" r="3" fill="#536477"/><circle class="port" cx="80" cy="-3" r="3" fill="#536477"/><text class="slot" x="40" y="-10" text-anchor="middle">0</text><text class="slot" x="80" y="-10" text-anchor="middle">1</text></g></g><g class="region-heads" style="opacity: 1;"><g class="region-head" transform="translate(24,173)"><text class="label" x="26" y="17"><tspan>If</tspan><tspan class="node-id">  #10</tspan></text><title>If · 6 nodes</title><g class="fold-btn" role="button" tabindex="0" transform="translate(4,4)" aria-label="Fold region #10"><rect width="16" height="16" rx="2"/><text x="8" y="12" text-anchor="middle">−</text><title>Fold region</title></g></g></g><g class="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter05/Makefile b/docs/chapter05/Makefile
new file mode 100644
index 00000000..6fa0f057
--- /dev/null
+++ b/docs/chapter05/Makefile
@@ -0,0 +1 @@
+include ../../graph/docs.mk
diff --git a/docs/chapter05/README.md b/docs/chapter05/README.md
new file mode 100644
index 00000000..6f690922
--- /dev/null
+++ b/docs/chapter05/README.md
@@ -0,0 +1,425 @@
+# Chapter 5: If Statement, Phi, and Region
+
+[Previous: Chapter 4](../chapter04/README.md) |
+[Next: Chapter 6](../chapter06/README.md)
+
+# Table of Contents
+
+1. [Recap](#recap)
+2. [New Nodes](#new-nodes)
+3. [`IfNode`](#ifnode)
+4. [`PhiNode`](#phinode)
+5. [`RegionNode`](#regionnode)
+6. [Pinned data nodes](#we-do-not-associate-a-control-edge-on-every-data-node-in-the-graph)
+7. [`Stop` Nodes](#stop-nodes)
+8. [Parsing an `if` Statement](#parsing-an-if-statement)
+9. [Operations on ScopeNodes](#operations-on-scopenodes)
+10. [Duplicating a ScopeNode](#duplicating-a-scopenode)
+11. [Merging two ScopeNodes](#merging-two-scopenodes)
+12. [Example 1](#example-1)
+13. [Before Merging](#before-merging)
+14. [After Merging](#after-merging)
+15. [Finally](#finally)
+16. [Example 2](#example-2)
+17. [Example 3](#example-3)
+18. [Pushing addition up through a Phi](#pushing-addition-up-through-a-phi)
+19. [More Examples](#more-examples)
+
+You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter05) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter04...linear-chapter05) it to the previous chapter.
+
+In this chapter we extend the language grammar with the following features:
+
+* We introduce the `if` statement.
+* To support splitting of control flow and merging, we introduce new nodes: `Region` and `Phi`.
+* Since we can now have multiple return points, we also introduce the `Stop` node as the termination.
+
+Here is the [complete language grammar](05-grammar.md) for this chapter.
+
+## New Nodes
+
+The following new nodes are introduced in this chapter:
+
+| Node Name | Type | Chapter | Description | Inputs | Value |
+|-----------|---------|---------|----------------------------------------------------|------------------------------------------------|----------------------------------------------------|
+| If | Control | 5 | A branching test, sub type of `MultiNode` | A control node and a data predicate node | A tuple of two values: one for true, one for false |
+| Region | Control | 5 | A merge point for multiple control flows | An input for each control flow that is merging | Merged control |
+| Phi | Data | 5 | A phi function picks a value based on control flow | A Region, and data nodes for each control path | Depends on control flow path taken |
+| Stop | Control | 5 | Termination of the program | All return nodes of the function | None |
+
+and keep all nodes from prior chapters.
+
+#### `IfNode`
+
+`If` node takes in both control and data (predicate expression) and routes the
+control token to one of the two control flows, represented by true and false
+`Proj` nodes.
+
+#### `PhiNode`
+
+A `Phi` reads in both data and control, and outputs a data value. The control
+input to the `Phi` points to a `Region` node. The data inputs to the `Phi` are
+one for each of the control inputs to that `Region`. The result computed by a
+`Phi` depends both on the data and the matching control input. At most one
+control input to the `Region` can be active at a time, and the `Phi` passes
+through the data value from the matching input.[^1]
+
+Its type is the meet of its data-input types. Two different integer constants
+merge to `TypeInteger.BOT`: the value is unknown, but it is still an integer.
+Integer arithmetic likewise retains an integer result type when it cannot fold.
+
+#### `RegionNode`
+
+In this Sea of Nodes, there is an embedded Control Flow Graph - and like a
+normal CFG there are merge points where two basic blocks flow into one. The
+`Region` node takes control from each predecessor control (block) as input and
+produces a merged control as an output.[^2]
+
+Both `Return` and `If` take control in slot 0. `PhiNode`s need their
+corresponding `RegionNode` to know when to merge data values, so again slot 0
+is set, and data values show up in slots 1 and onward. `RegionNode`s keep
+their control inputs in sync with `PhiNode`s, so again their control inputs show up
+in slots 1 and onward.
+
+#### We do not associate a control edge on every data node in the graph
+
+If we want to track the basic block a normal instruction is in, we will set the
+control input (always slot 0) to some control-producing Node. Typically we do
+not need to (nor want to) track this - so control is `null` for most data ops.
+The correctness of such a data op is solely determined by the remaining data
+dependencies. It, and the Nodes that depend on it or on which it depends,
+exists in a “sea” of Nodes, with little control structure.
+
+The “sea” of Nodes is useful for optimization, but does not represent any
+traditional intermediate representation such as a CFG. We need a way to
+serialize the graph and get back the control dependences. We do this with a
+simple Global Code Motion [^3] algorithm in [Chapter 13](../chapter13/README.md).
+
+#### `Stop` Nodes
+`StopNode`s only have `ReturnNode` inputs. They mark the program termination.
+
+
+
+## Parsing an `if` Statement
+
+When we parse an `if` statement, the control flow splits at that point. We
+must track the names being updated in each part of the `if` statement, and then
+merge them at the end. The implementation follows the description in *Combining Analyses, Combining Optimizations*[^4].
+
+This involves the following:
+
+1. We create an `IfNode` with the current control token, i.e. the node mapped to
+ `$ctrl`, and the `if` predicate expression as inputs.
+2. We add two `ProjNodes` - one for the `True` branch (call it `ifT`), and the
+ other for the `False` branch (call it `ifF`) - these extract values from the
+ tuple result of the `IfNode`.
+3. We duplicate the current `ScopeNode`. The duplicated `ScopeNode` contains
+ all the same symbol tables as the original, and has the same edges.
+4. We set the control token to the `True` projection node `ifT`, and parse the true
+ branch of the `if` statement.
+5. We set the duplicated `ScopeNode` as the current one.
+6. The control token is set to the `False` projection node `ifF`, and if there is an
+ `else` statement we parse it.
+7. At this point we have two `ScopeNode`s; the original one, potentially updated
+ by the `True` branch, and the duplicate one, potentially updated by the
+ `False` branch.
+8. We create a `Region` node to represent a merge point.
+9. We *merge* the two `ScopeNode`s. We create `Phi` nodes for any names whose
+ bindings differ. The `Phi` nodes take the `Region` node as the control input
+ and the two data nodes from each of the `ScopeNode`s. The name binding is
+ updated to point to the `Phi` node.
+10. Finally, we set the `Region` node as the control token, and discard the duplicated `ScopeNode`.
+
+Implementation is in [`parseIf` method in `Parser`](https://github.com/SeaOfNodes/Simple/blob/main/chapter05/src/main/java/com/seaofnodes/simple/Parser.java#L149-L185).
+
+## Operations on ScopeNodes
+
+As explained above, we duplicate ScopeNodes and merge them at a later point. There are some
+subtleties in how this is implemented that are worth going over.
+
+### Duplicating a ScopeNode
+
+Below is the code for duplicating a ScopeNode.
+
+Our goals are:
+1) Duplicate the name bindings across all stack levels
+2) Make the new ScopeNode a user of all the bound nodes
+3) Ensure that the order of defs in the duplicate is the same to allow easy merging
+
+For implementation [see `scopeNode.dup()`](https://github.com/SeaOfNodes/Simple/blob/main/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java#L142-L154)
+
+### Merging two ScopeNodes
+
+At the merge point we merge two ScopeNodes. The goals are:
+
+1) Merge names whose bindings have changed between the two nodes. For each such name, a Phi node is created, referencing the two original data nodes.
+2) A new Region node is created representing the merged control flow. The phis have this region node as the first input.
+3) After the merge is completed, the duplicate `ScopeNode` is discarded along with its edges.
+
+The merging logic takes advantage of the fact that the two ScopeNodes have the bound nodes in the same order in the list of inputs. This was ensured during duplicating the ScopeNode.
+Although only the innermost occurrence of a name can have its binding changed, we scan all the nodes in our input list, and simply ignore ones where the binding has not changed.
+
+For implementation [see `ScopeNode.mergeScopes()`](https://github.com/SeaOfNodes/Simple/blob/main/chapter05/src/main/java/com/seaofnodes/simple/node/ScopeNode.java#L164-L173)
+
+
+## Example #1
+
+We show the graph for the following code snippet:
+```java
+int a = 1;
+if (arg == 1)
+ a = arg+2;
+else
+ a = arg-3;
+return a;
+```
+
+### Before Merging
+
+The following shows the graph just before we merge the two branches of the `if` statement in a `Region` node.
+
+![Graph1](./05-graph1.svg)
+
+Note the two `ScopeNode`s in the graph.
+One has its `$ctrl` pointing to the `True` projection, while the other has `$ctrl` pointing to `False` projection.
+The variable `a` is bound to the `Add` node in the `True` branch, whereas it is bound to the `Sub` node in the `False` branch.
+Thus `a` will need a `Phi` node when merging the two scopes.
+
+### After Merging
+
+Below is the graph after we created a `Region` node and merged the two definitions of `a` in a `Phi` node.
+
+![Graph2](./05-graph2.svg)
+
+The duplicate `ScopeNode` has been discarded and was merged into the other one.
+Since `a` had two different definitions in both scopes a `Phi` node was created
+and is now referenced from `a`. The `Phi` node's inputs are the `Region` node
+and the `Add` node from the `True` branch, and `Sub` node from the `False`
+branch. The `arg` variable did not get assigned; both scopes agree on the
+value so `arg` does not get a `Phi`.
+
+### Finally
+
+Here is the graph after the `return` statement was parsed and processed.
+
+![Graph3](./05-graph3.svg)
+
+
+
+## Example #2
+
+Consider the following code snippet:
+```java
+int b = 0;
+int c = 0;
+if (arg == 1) {
+ b = 2;
+ c = 1;
+}
+else {
+ b = 1;
+}
+return b;
+```
+
+The value of `b` depends on which path the control flow took.
+To resolve this, a Φ (Phi) function is inserted.
+
+```
+b = Phi(Region,2, 1); // values vary
+c = Phi(Region,1, 0); // values vary, but dead
+```
+
+The `Phi` for `c` will die when the scope where `c` is defined dies. This does
+not happen when merging but after the `return`. `return` is using `b` so `b`
+stays alive.
+
+Before we go ahead and parse down the if statement we duplicate the scope:
+```java
+ScopeNode fScope = _scope.dup();
+/* Scope[$ctrl:$ctrl, arg:arg][b:0, c:0]*/
+```
+
+We then will proceed and parse down the first branch of the if statement:
+```java
+// Parse the true side
+ctrl(ifT); // set ctrl token to ifTrue projection
+parseStatement(); // Parse true-side
+ScopeNode tScope = _scope;
+
+/* Scope[$ctrl:True, arg:arg][b:2, c:1]*/
+```
+
+Notice, this branch modified and set a new value for both symbols currently existing in the symbol table.
+Now, we set the scope back to where we started (without the modifications that `ifT` made)
+
+```java
+_scope = fScope;
+```
+
+We then will proceed and parse down the second branch of the if statement:
+```java
+if (matchx("else")) {
+ parseStatement();
+ fScope = _scope;
+
+ /* Scope[$ctrl:False, arg:arg][b:1, c:0]*/
+}
+```
+
+The two branches modified `b`; only the true branch modified `c`. Since the branch arms are also
+lexical scopes, they cannot introduce new symbols in the current (outer) scope.
+This means that the order of the name bindings stayed the same. Excluding the
+first control node, we loop through and compare the nodes corresponding to the
+same name binding to see if the nodes are different, if so we create a phi node
+representing this conflict:
+
+```java
+ /* in(i); 2 */
+ /* that.in(i); 1 */
+ if( in(i) != that.in(i) ) // No need for redundant Phis
+ setDef(i, new PhiNode(ns[i], r, in(i), that.in(i)).peephole());
+```
+
+![Graph8](./05-graph9.svg)
+
+
+
+## Example #3
+
+Phis implement a peephole illustrated in the example:
+
+```java
+int a=arg==2;
+if( arg==1 )
+{
+ a=arg==3;
+}
+return a;
+```
+
+The next two diagrams focus on the value rewrite. The unchanged `if` and
+Region are omitted; Phi input 1 is the true arm and input 2 the false arm.
+The Phis still use the same Region in the compiler's graph.
+
+Pre-peephole we have:
+
+![Graph4](./05-graph4.svg)
+
+Post-peephole:
+
+![Graph5](./05-graph5.svg)
+
+The common operator was pulled out and the Phi node only got applied to the
+operands. Notice how only the second operand of the `==` changes, the first
+one stays the same (`arg`). The implementation is in
+[`PhiNode.idealize()`](../../src/main/java/com/seaofnodes/simple/node/PhiNode.java).
+
+In graph notation, with `r` denoting the same Region throughout:
+
+```text
+Phi(r, a+b, c+d) -> Phi(r, a, c) + Phi(r, b, d)
+```
+
+We call this **pulling the operation down** through the Phi: the common
+operation moves from the incoming paths to after their merge. Each new Phi
+selects the corresponding operand from the same path. If an operand is shared,
+as `arg` is above, its Phi collapses to that operand.
+
+
+## Pushing addition up through a Phi
+
+The opposite direction can expose constant folding. For example:
+
+```java
+int x = 1;
+if( arg ) x = 2;
+return (arg+x)+3;
+```
+
+The merge gives `x` a Phi of constants. Although `x` itself is not constant,
+adding 3 to each possible value is a compile-time calculation. The addition
+peephole reassociates the expression and **pushes the addition up** onto the
+incoming paths:
+
+```text
+(arg + Phi(r, 2, 1)) + 3
+ -> arg + Phi(r, 2+3, 1+3)
+ -> arg + Phi(r, 5, 4)
+```
+
+The implementation first appears here in
+[`AddNode.idealize()`](../../src/main/java/com/seaofnodes/simple/node/AddNode.java),
+for the shape `(x + Phi(constants)) + constant`. The final operand can also
+be another Phi of constants, but both Phis must use the **same Region** so
+their corresponding arms describe the same path.
+
+Why not push every operation through a Phi? That would duplicate work across
+the incoming paths, and the pull-down peephole could immediately undo it.
+Repeatedly applying the two rewrites would never finish. Here every new
+addition folds to a constant **before** we build the result Phi. There are no
+new additions left for that Phi to pull back down, and one runtime addition
+has disappeared. The folding requirement supplies both the benefit and the
+reason this pair of opposing rewrites terminates.
+
+
+## More examples
+
+The next two simple `if` examples also omit control flow to highlight the
+resulting values. Their Phi inputs retain the true/false order above.
+
+```java
+int c = 3;
+int b = 2;
+if (arg == 1) {
+ b = 3;
+ c = 4;
+}
+return c;
+```
+
+![Graph6](./05-graph6.svg)
+
+```java
+int a=arg+1;
+int b=arg+2;
+if( arg==1 )
+ b=b+a;
+else
+ a=b+1;
+return a+b;
+```
+
+![Graph7](./05-graph7.svg)
+
+For nested branches, the control paths and Regions are shown so each Phi's
+incoming paths remain clear:
+
+```java
+int a=1;
+if( arg==1 )
+ if( arg==2 )
+ a=2;
+ else
+ a=3;
+else if( arg==3 )
+ a=4;
+else
+ a=5;
+return a;
+```
+
+![Graph8](./05-graph8.svg)
+
+
+
+[^1]: Click, C. (1995).
+ Combining Analyses, Combining Optimizations, 132.
+
+[^2]: Click, C. (1995).
+ Combining Analyses, Combining Optimizations, 129.
+
+[^3]: Click, C. (1995).
+ Combining Analyses, Combining Optimizations, 86.
+
+[^4]: Click, C. (1995).
+ Combining Analyses, Combining Optimizations, 102-103.
generated by cgit v1.2.3 (git 2.25.1) at 2026-10-15 15:16:22 +0000