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-rw-r--r--docs/chapter09/09-grammar.md94
-rw-r--r--docs/chapter09/09-graph1.gv67
-rw-r--r--docs/chapter09/09-graph1.json23
-rw-r--r--docs/chapter09/09-graph1.svg110
-rw-r--r--docs/chapter09/09-graph2.gv63
-rw-r--r--docs/chapter09/09-graph2.json21
-rw-r--r--docs/chapter09/09-graph2.svg102
-rw-r--r--docs/chapter09/09-graph3.gv37
-rw-r--r--docs/chapter09/09-graph3.json17
-rw-r--r--docs/chapter09/09-graph3.svg89
-rw-r--r--docs/chapter09/09-graph4.gv29
-rw-r--r--docs/chapter09/09-graph4.json13
-rw-r--r--docs/chapter09/09-graph4.svg70
-rw-r--r--docs/chapter09/09-graph5.gv63
-rw-r--r--docs/chapter09/09-graph5.json18
-rw-r--r--docs/chapter09/09-graph5.svg92
-rw-r--r--docs/chapter09/09-graph6.gv60
-rw-r--r--docs/chapter09/09-graph6.json17
-rw-r--r--docs/chapter09/09-graph6.svg87
-rw-r--r--docs/chapter09/Makefile1
-rw-r--r--docs/chapter09/README.md310
21 files changed, 1383 insertions, 0 deletions
diff --git a/docs/chapter09/09-grammar.md b/docs/chapter09/09-grammar.md
new file mode 100644
index 00000000..00f93e04
--- /dev/null
+++ b/docs/chapter09/09-grammar.md
@@ -0,0 +1,94 @@
+# Grammar for Chapter 8
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+ : statement+ EOF
+ ;
+
+statement
+ : returnStatement
+ | declStatement
+ | blockStatment
+ | expressionStatement
+ | ifStatement
+ | whileStatement
+ | breakStatement
+ | continueStatment
+ ;
+
+whileStatement
+ : 'while' '(' expression ')' statement
+ ;
+
+breakStatement
+ : 'break' ';'
+ ;
+
+continueStatement
+ : 'continue' ';'
+ ;
+
+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/chapter09/09-graph1.gv b/docs/chapter09/09-graph1.gv
new file mode 100644
index 00000000..e6d1851a
--- /dev/null
+++ b/docs/chapter09/09-graph1.gv
@@ -0,0 +1,67 @@
+digraph chapter08 {
+/*
+int x = arg + arg;
+if(arg < 10) {
+ return arg + arg;
+}
+else {
+ x = x + 1;
+}
+return x;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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="2" ];
+ Mul8 [ label="*" ];
+ Con_9 [ label="10" ];
+ LT10 [ label="<" ];
+ If11 [ 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_16 [ label="2" ];
+ Mul17 [ label="*" ];
+ Return18 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ Con_20 [ label="1" ];
+ Add21 [ label="+" ];
+ Return24 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return18[taillabel=0 color=red];
+ Stop3 -> Return24[taillabel=1 color=red];
+ Mul8 -> Start2:p1[taillabel=1];
+ Mul8 -> Con_7[taillabel=2];
+ LT10 -> Start2:p1[taillabel=1];
+ LT10 -> Con_9[taillabel=2];
+ If11 -> Start2:p0[taillabel=0 color=red];
+ If11 -> LT10[taillabel=1];
+ Mul17 -> Start2:p1[taillabel=1];
+ Mul17 -> Con_16[taillabel=2];
+ Return18 -> If11:p0[taillabel=0 color=red];
+ Return18 -> Mul17[taillabel=1];
+ Add21 -> Mul8[taillabel=1];
+ Add21 -> Con_20[taillabel=2];
+ Return24 -> If11:p1[taillabel=0 color=red];
+ Return24 -> Add21[taillabel=1];
+}
diff --git a/docs/chapter09/09-graph1.json b/docs/chapter09/09-graph1.json
new file mode 100644
index 00000000..8dfdee0a
--- /dev/null
+++ b/docs/chapter09/09-graph1.json
@@ -0,0 +1,23 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-graph1.svg",
+ "step": 1,
+ "roots": [18, 24],
+ "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": 5, "label": "True", "type": null, "kind": "CTRL", "edges": [], "proj": {"par": 0, "idx": 0}},
+ {"id": 6, "label": "False", "type": null, "kind": "CTRL", "edges": [], "proj": {"par": 0, "idx": 1}},
+ {"id": 7, "label": "2", "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": 16, "label": "2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 17, "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": 16, "role": "DATA", "label": null}], "proj": null},
+ {"id": 18, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 5, "role": "CTRL", "label": null}, {"idx": 1, "def": 17, "role": "DATA", "label": null}], "proj": null},
+ {"id": 20, "label": "1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 21, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}, {"idx": 2, "def": 20, "role": "DATA", "label": null}], "proj": null},
+ {"id": 24, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 6, "role": "CTRL", "label": null}, {"idx": 1, "def": 21, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph1.svg b/docs/chapter09/09-graph1.svg
new file mode 100644
index 00000000..1b53a14a
--- /dev/null
+++ b/docs/chapter09/09-graph1.svg
@@ -0,0 +1,110 @@
+<svg aria-label="Compiler graph" width="587" height="454" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 587 454" 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="e8i1" d="M193,118 L193,130 Q193,138 201,138 L337,138 Q345,138 345,146 L345,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #4 · DATA</title></path><path class="edge DATA" id="e8i2" d="M503,118 L503,123 Q503,128 498,128 L383,128 Q375,128 375,136 L375,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge DATA" id="e17i1" d="M193,118 L193,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[1] → #4 · DATA</title></path><path class="edge DATA" id="e17i2" d="M351,118 L351,123 Q351,128 346,128 L231,128 Q223,128 223,136 L223,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#17[2] → #16 · DATA</title></path><path class="edge CTRL" id="e18i0" d="M64,222 L64,270" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#18[0] → #5 · CTRL</title></path><path class="edge DATA" id="e18i1" d="M193,222 L193,227 Q193,232 188,232 L112,232 Q104,232 104,240 L104,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #17 · DATA</title></path><path class="edge DATA" id="e21i1" d="M345,222 L345,230 Q345,232 347,232 L347,232 Q349,232 349,234 L349,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#21[1] → #8 · DATA</title></path><path class="edge DATA" id="e21i2" d="M497,222 L497,227 Q497,232 492,232 L387,232 Q379,232 379,240 L379,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#21[2] → #20 · DATA</title></path><path class="edge CTRL" id="e24i0" d="M217,326 L217,374" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#24[0] → #6 · CTRL</title></path><path class="edge DATA" id="e24i1" d="M349,326 L349,331 Q349,336 344,336 L265,336 Q257,336 257,344 L257,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#24[1] → #21 · 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(133,24)" 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(133,68)" 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(26,190)" style="opacity: 1;"><path class="box" d="M0,0H75V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="37.5" y="17"><tspan>True</tspan><tspan class="node-id">  #5/0</tspan></text><text class="type" text-anchor="middle" y="35" x="37.5"/><title>#5 True
+Projection 0 of #0
+Type not computed
+
+</title></g><g class="node" id="n6" data-id="6" transform="translate(176,294)" style="opacity: 1;"><path class="box" d="M0,0H81V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="40.5" y="17"><tspan>False</tspan><tspan class="node-id">  #6/1</tspan></text><text class="type" text-anchor="middle" y="35" x="40.5"/><title>#6 False
+Projection 1 of #0
+Type not computed
+
+</title></g><g class="node" id="n7" data-id="7" transform="translate(443,68)" 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">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 2
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(285,172)" 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] → #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="n16" data-id="16" transform="translate(291,68)" 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">  #16</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#16 2
+Type not computed
+
+</title></g><g class="node" id="n17" data-id="17" transform="translate(133,172)" 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">  #17</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#17 *
+Type not computed
+
+[0] → — DATA
+[1] → #4 DATA
+[2] → #16 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="n18" data-id="18" transform="translate(24,276)" 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] → #5 CTRL
+[1] → #17 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 class="node" id="n20" data-id="20" transform="translate(437,172)" 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>1</tspan><tspan class="node-id">  #20</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#20 1
+Type not computed
+
+</title></g><g class="node" id="n21" data-id="21" transform="translate(289,276)" 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>+</tspan><tspan class="node-id">  #21</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#21 +
+Type not computed
+
+[0] → — DATA
+[1] → #8 DATA
+[2] → #20 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="n24" data-id="24" transform="translate(177,380)" 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">  #24</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#24 Return
+Type not computed
+
+[0] → #6 CTRL
+[1] → #21 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="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter09/09-graph2.gv b/docs/chapter09/09-graph2.gv
new file mode 100644
index 00000000..1a1f7a29
--- /dev/null
+++ b/docs/chapter09/09-graph2.gv
@@ -0,0 +1,63 @@
+digraph chapter09 {
+/*
+int x = arg + arg;
+if(arg < 10) {
+ return arg + arg;
+}
+else {
+ x = x + 1;
+}
+return x;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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="#2" ];
+ Mul8 [ label="*" ];
+ LT9 [ label="<" ];
+ Con_10 [ label="#10" ];
+ If11 [ 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>>
+ ];
+ Return18 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ Add20 [ label="+" ];
+ Con_21 [ label="#1" ];
+ Return24 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return18[taillabel=0 color=red];
+ Stop3 -> Return24[taillabel=1 color=red];
+ Mul8 -> Start2:p1[taillabel=1];
+ Mul8 -> Con_7[taillabel=2];
+ LT9 -> Start2:p1[taillabel=1];
+ LT9 -> Con_10[taillabel=2];
+ If11 -> Start2:p0[taillabel=0 color=red];
+ If11 -> LT9[taillabel=1];
+ Return18 -> If11:p0[taillabel=0 color=red];
+ Return18 -> Mul8[taillabel=1];
+ Add20 -> Mul8[taillabel=1];
+ Add20 -> Con_21[taillabel=2];
+ Return24 -> If11:p1[taillabel=0 color=red];
+ Return24 -> Add20[taillabel=1];
+}
diff --git a/docs/chapter09/09-graph2.json b/docs/chapter09/09-graph2.json
new file mode 100644
index 00000000..7b48931f
--- /dev/null
+++ b/docs/chapter09/09-graph2.json
@@ -0,0 +1,21 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-graph2.svg",
+ "step": 1,
+ "roots": [18, 24],
+ "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": 5, "label": "True", "type": null, "kind": "CTRL", "edges": [], "proj": {"par": 0, "idx": 0}},
+ {"id": 6, "label": "False", "type": null, "kind": "CTRL", "edges": [], "proj": {"par": 0, "idx": 1}},
+ {"id": 7, "label": "#2", "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": 18, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 5, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "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": 8, "role": "DATA", "label": null}, {"idx": 2, "def": 21, "role": "DATA", "label": null}], "proj": null},
+ {"id": 21, "label": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 24, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 6, "role": "CTRL", "label": null}, {"idx": 1, "def": 20, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph2.svg b/docs/chapter09/09-graph2.svg
new file mode 100644
index 00000000..59ef5de1
--- /dev/null
+++ b/docs/chapter09/09-graph2.svg
@@ -0,0 +1,102 @@
+<svg aria-label="Compiler graph" width="548" height="454" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 548 454" 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="e8i1" d="M306,118 L306,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #4 · DATA</title></path><path class="edge DATA" id="e8i2" d="M464,118 L464,123 Q464,128 459,128 L344,128 Q336,128 336,136 L336,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge CTRL" id="e18i0" d="M177,222 L177,270" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#18[0] → #5 · CTRL</title></path><path class="edge DATA" id="e18i1" d="M306,222 L306,227 Q306,232 301,232 L225,232 Q217,232 217,240 L217,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #8 · DATA</title></path><path class="edge DATA" id="e20i1" d="M306,222 L306,227 Q306,232 311,232 L341,232 Q349,232 349,240 L349,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[1] → #8 · DATA</title></path><path class="edge DATA" id="e20i2" d="M458,222 L458,227 Q458,232 453,232 L387,232 Q379,232 379,240 L379,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#20[2] → #21 · DATA</title></path><path class="edge CTRL" id="e24i0" d="M65,326 L65,374" stroke="#b63838" marker-start="url(#arrow-CTRL)" style="opacity: 1;"><title>#24[0] → #6 · CTRL</title></path><path class="edge DATA" id="e24i1" d="M349,326 L349,331 Q349,336 344,336 L113,336 Q105,336 105,344 L105,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#24[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(246,24)" 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(246,68)" 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(139,190)" style="opacity: 1;"><path class="box" d="M0,0H75V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="37.5" y="17"><tspan>True</tspan><tspan class="node-id">  #5/0</tspan></text><text class="type" text-anchor="middle" y="35" x="37.5"/><title>#5 True
+Projection 0 of #0
+Type not computed
+
+</title></g><g class="node" id="n6" data-id="6" transform="translate(24,294)" style="opacity: 1;"><path class="box" d="M0,0H81V26H0Z" fill="#fff1c4"/><text class="label" text-anchor="middle" x="40.5" y="17"><tspan>False</tspan><tspan class="node-id">  #6/1</tspan></text><text class="type" text-anchor="middle" y="35" x="40.5"/><title>#6 False
+Projection 1 of #0
+Type not computed
+
+</title></g><g class="node" id="n7" data-id="7" transform="translate(404,68)" 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">  #7</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#7 #2
+Type not computed
+
+</title></g><g class="node" id="n8" data-id="8" transform="translate(246,172)" 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] → #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="n18" data-id="18" transform="translate(137,276)" 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] → #5 CTRL
+[1] → #8 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 class="node" id="n20" data-id="20" transform="translate(289,276)" 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>+</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] → #8 DATA
+[2] → #21 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(398,172)" 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>#1</tspan><tspan class="node-id">  #21</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#21 #1
+Type not computed
+
+</title></g><g class="node" id="n24" data-id="24" transform="translate(25,380)" 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">  #24</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#24 Return
+Type not computed
+
+[0] → #6 CTRL
+[1] → #20 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="shortcuts" style="opacity: 1;"/><g class="peep-ghosts" pointer-events="none"/></g></svg>
diff --git a/docs/chapter09/09-graph3.gv b/docs/chapter09/09-graph3.gv
new file mode 100644
index 00000000..37bb1c53
--- /dev/null
+++ b/docs/chapter09/09-graph3.gv
@@ -0,0 +1,37 @@
+digraph chapter08 {
+/*
+return arg*arg-arg*arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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" ];
+ Mul6 [ label="*" ];
+ Mul7 [ label="*" ];
+ Sub8 [ label="-" ];
+ Return9 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return9[taillabel=0 color=red];
+ Mul6 -> Start2:p1[taillabel=1];
+ Mul6 -> Start2:p1[taillabel=2];
+ Mul7 -> Start2:p1[taillabel=1];
+ Mul7 -> Start2:p1[taillabel=2];
+ Sub8 -> Mul6[taillabel=1];
+ Sub8 -> Mul7[taillabel=2];
+ Return9 -> Start2:p0[taillabel=0 color=red];
+ Return9 -> Sub8[taillabel=1];
+}
diff --git a/docs/chapter09/09-graph3.json b/docs/chapter09/09-graph3.json
new file mode 100644
index 00000000..abdb81b6
--- /dev/null
+++ b/docs/chapter09/09-graph3.json
@@ -0,0 +1,17 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-graph3.svg",
+ "step": 1,
+ "roots": [9],
+ "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": "*", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 4, "role": "DATA", "label": null}], "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": 4, "role": "DATA", "label": null}], "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": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 8, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph3.svg b/docs/chapter09/09-graph3.svg
new file mode 100644
index 00000000..da89b9b9
--- /dev/null
+++ b/docs/chapter09/09-graph3.svg
@@ -0,0 +1,89 @@
+<svg aria-label="Compiler graph" width="340" height="454" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 340 454" 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="e6i1" d="M134,118 L134,123 Q134,128 129,128 L112,128 Q104,128 104,136 L104,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#6[1] → #4 · DATA</title></path><path class="edge DATA" id="e6i2" d="M134,118 L134,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#6[2] → #4 · DATA</title></path><path class="edge DATA" id="e7i1" d="M134,118 L134,123 Q134,128 139,128 L248,128 Q256,128 256,136 L256,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#7[1] → #4 · DATA</title></path><path class="edge DATA" id="e7i2" d="M134,118 L134,123 Q134,128 139,128 L278,128 Q286,128 286,136 L286,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#7[2] → #4 · DATA</title></path><path class="edge DATA" id="e8i1" d="M104,222 L104,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[1] → #6 · DATA</title></path><path class="edge DATA" id="e8i2" d="M256,222 L256,227 Q256,232 251,232 L142,232 Q134,232 134,240 L134,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#8[2] → #7 · DATA</title></path><path class="edge DATA" id="e9i1" d="M104,326 L104,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #8 · 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(74,24)" 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(74,68)" 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(44,172)" 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">  #6</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 *
+Type not computed
+
+[0] → — DATA
+[1] → #4 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="n7" data-id="7" transform="translate(196,172)" 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] → #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="n8" data-id="8" transform="translate(44,276)" 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>-</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(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">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#9 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #8 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/chapter09/09-graph4.gv b/docs/chapter09/09-graph4.gv
new file mode 100644
index 00000000..8886f73a
--- /dev/null
+++ b/docs/chapter09/09-graph4.gv
@@ -0,0 +1,29 @@
+digraph chapter09 {
+/*
+return arg*arg-arg*arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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></TR>
+ </TABLE>
+ </TD></TR>
+ </TABLE>>
+ ];
+ Stop3 [ shape=box style=filled fillcolor=yellow label="Stop" ];
+ Con_9 [ label="#0" ];
+ Return10 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return10[taillabel=0 color=red];
+ Return10 -> Start2:p0[taillabel=0 color=red];
+ Return10 -> Con_9[taillabel=1];
+}
diff --git a/docs/chapter09/09-graph4.json b/docs/chapter09/09-graph4.json
new file mode 100644
index 00000000..1282e87e
--- /dev/null
+++ b/docs/chapter09/09-graph4.json
@@ -0,0 +1,13 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-graph4.svg",
+ "step": 1,
+ "roots": [10],
+ "scope": 0,
+ "nodes": [
+ {"id": 9, "label": "#0", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 10, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 9, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph4.svg b/docs/chapter09/09-graph4.svg
new file mode 100644
index 00000000..3c49a48a
--- /dev/null
+++ b/docs/chapter09/09-graph4.svg
@@ -0,0 +1,70 @@
+<svg aria-label="Compiler graph" width="188" height="202" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 188 202" 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="e10i1" d="M104,74 L104,122" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#10[1] → #9 · DATA</title></path></g><g class="edge-hits"/><g class="parser" style="opacity: 1;"/><g class="nodes"><g class="node" id="n9" data-id="9" transform="translate(44,24)" 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>#0</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#9 #0
+Type not computed
+
+</title></g><g class="node" id="n10" data-id="10" transform="translate(24,128)" 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">  #10</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#10 Return
+Type not computed
+
+[0] → — CTRL
+[1] → #9 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/chapter09/09-graph5.gv b/docs/chapter09/09-graph5.gv
new file mode 100644
index 00000000..72274239
--- /dev/null
+++ b/docs/chapter09/09-graph5.gv
@@ -0,0 +1,63 @@
+digraph chapter09 {
+/*
+int step = 1;
+while (arg < 10) {
+ arg = arg + step + 1;
+}
+return arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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="#1" ];
+ Loop7 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_arg9 [ style=filled fillcolor=lightyellow label="&phi;_arg" ];
+ LT10 [ label="<" ];
+ Con_11 [ label="#10" ];
+ 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>>
+ ];
+ Add16 [ label="+" ];
+ Add18 [ label="+" ];
+ Return21 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ { rank=same; Loop7;Phi_arg9;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return21[taillabel=0 color=red];
+ Loop7 -> Start2:p0[taillabel=1 color=red];
+ Loop7 -> If12:p0[taillabel=2 color=red constraint=false];
+ Phi_arg9 -> Loop7 [style=dotted taillabel=0];
+ Phi_arg9 -> Start2:p1[taillabel=1];
+ Phi_arg9 -> Add18[taillabel=2 constraint=false];
+ LT10 -> Phi_arg9[taillabel=1];
+ LT10 -> Con_11[taillabel=2];
+ If12 -> Loop7[taillabel=0 color=red];
+ If12 -> LT10[taillabel=1];
+ Add16 -> Con_6[taillabel=1];
+ Add16 -> Phi_arg9[taillabel=2];
+ Add18 -> Add16[taillabel=1];
+ Add18 -> Con_6[taillabel=2];
+ Return21 -> If12:p1[taillabel=0 color=red];
+ Return21 -> Phi_arg9[taillabel=1];
+}
diff --git a/docs/chapter09/09-graph5.json b/docs/chapter09/09-graph5.json
new file mode 100644
index 00000000..ff52950d
--- /dev/null
+++ b/docs/chapter09/09-graph5.json
@@ -0,0 +1,18 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-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": "#1", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 9, "label": "φ_arg", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 18, "role": "DATA", "label": null, "backedge": true}], "proj": null},
+ {"id": 16, "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": 9, "role": "DATA", "label": null}], "proj": null},
+ {"id": 18, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 16, "role": "DATA", "label": null}, {"idx": 2, "def": 6, "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": 9, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph5.svg b/docs/chapter09/09-graph5.svg
new file mode 100644
index 00000000..bbaf2227
--- /dev/null
+++ b/docs/chapter09/09-graph5.svg
@@ -0,0 +1,92 @@
+<svg aria-label="Compiler graph" width="402" height="464" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 402 464" 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="e9i1" d="M287,118 L287,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[1] → #4 · DATA</title></path><path class="edge DATA" id="e9i2" d="M155,430 L155,435 Q155,440 160,440 L369,440 Q377,440 377,432 L377,136 Q377,128 369,128 L335,128 Q327,128 327,136 L327,166" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#9[2] → #18 · DATA</title></path><path class="edge DATA" id="e16i1" d="M84,222 L84,227 Q84,232 89,232 L147,232 Q155,232 155,240 L155,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[1] → #6 · DATA</title></path><path class="edge DATA" id="e16i2" d="M307,222 L307,227 Q307,232 302,232 L193,232 Q185,232 185,240 L185,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#16[2] → #9 · DATA</title></path><path class="edge DATA" id="e18i1" d="M155,326 L155,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[1] → #16 · DATA</title></path><path class="edge DATA" id="e18i2" d="M84,222 L84,328 Q84,336 92,336 L177,336 Q185,336 185,344 L185,374" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#18[2] → #6 · DATA</title></path><path class="edge DATA" id="e21i1" d="M307,222 L307,227 Q307,232 312,232 L319,232 Q327,232 327,240 L327,270" stroke="#536477" marker-start="url(#arrow-DATA)" style="opacity: 1;"><title>#21[1] → #9 · 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(227,24)" 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(227,68)" 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(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>#1</tspan><tspan class="node-id">  #6</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#6 #1
+Type not computed
+
+</title></g><g class="node" id="n9" data-id="9" transform="translate(247,172)" 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_arg</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#9 φ_arg
+Type not computed
+
+[0] → — ASSOC
+[1] → #4 DATA
+[2] → #18 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="n16" data-id="16" transform="translate(95,276)" 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>+</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] → #6 DATA
+[2] → #9 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="n18" data-id="18" transform="translate(95,380)" 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">  #18</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#18 +
+Type not computed
+
+[0] → — DATA
+[1] → #16 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="n21" data-id="21" transform="translate(247,276)" 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] → #9 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/chapter09/09-graph6.gv b/docs/chapter09/09-graph6.gv
new file mode 100644
index 00000000..56dc6ada
--- /dev/null
+++ b/docs/chapter09/09-graph6.gv
@@ -0,0 +1,60 @@
+digraph chapter09 {
+/*
+int step = 1;
+while (arg < 10) {
+ arg = arg + step + 1;
+}
+return arg;
+
+*/
+ rankdir=BT;
+ ordering="in";
+ concentrate="true";
+ compound="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" ];
+ Loop7 [ shape=box style=filled fillcolor=yellow label="Loop" ];
+ Phi_arg9 [ style=filled fillcolor=lightyellow label="&phi;_arg" ];
+ LT10 [ label="<" ];
+ Con_11 [ label="#10" ];
+ 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>>
+ ];
+ Return21 [ shape=box style=filled fillcolor=yellow label="Return" ];
+ Con_24 [ label="#2" ];
+ Add25 [ label="+" ];
+ { rank=same; Loop7;Phi_arg9;}
+ }
+ edge [ fontname=Helvetica, fontsize=8 ];
+ Stop3 -> Return21[taillabel=0 color=red];
+ Loop7 -> Start2:p0[taillabel=1 color=red];
+ Loop7 -> If12:p0[taillabel=2 color=red constraint=false];
+ Phi_arg9 -> Loop7 [style=dotted taillabel=0];
+ Phi_arg9 -> Start2:p1[taillabel=1];
+ Phi_arg9 -> Add25[taillabel=2 constraint=false];
+ LT10 -> Phi_arg9[taillabel=1];
+ LT10 -> Con_11[taillabel=2];
+ If12 -> Loop7[taillabel=0 color=red];
+ If12 -> LT10[taillabel=1];
+ Return21 -> If12:p1[taillabel=0 color=red];
+ Return21 -> Phi_arg9[taillabel=1];
+ Add25 -> Phi_arg9[taillabel=1];
+ Add25 -> Con_24[taillabel=2];
+}
diff --git a/docs/chapter09/09-graph6.json b/docs/chapter09/09-graph6.json
new file mode 100644
index 00000000..5b511bd1
--- /dev/null
+++ b/docs/chapter09/09-graph6.json
@@ -0,0 +1,17 @@
+{
+ "ver": 1,
+ "comp": "chapter09/docs/09-graph6.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": 9, "label": "φ_arg", "type": null, "kind": "PHI", "edges": [{"idx": 0, "def": 0, "role": "ASSOC", "label": null}, {"idx": 1, "def": 4, "role": "DATA", "label": null}, {"idx": 2, "def": 25, "role": "DATA", "label": null, "backedge": true}], "proj": null},
+ {"id": 21, "label": "Return", "type": null, "kind": "CTRL", "edges": [{"idx": 0, "def": 0, "role": "CTRL", "label": null}, {"idx": 1, "def": 9, "role": "DATA", "label": null}], "proj": null},
+ {"id": 24, "label": "#2", "type": null, "kind": "DATA", "edges": [], "proj": null},
+ {"id": 25, "label": "+", "type": null, "kind": "DATA", "edges": [{"idx": 0, "def": 0, "role": "DATA", "label": null}, {"idx": 1, "def": 9, "role": "DATA", "label": null}, {"idx": 2, "def": 24, "role": "DATA", "label": null}], "proj": null}
+ ],
+ "groups": [
+ ]
+}
diff --git a/docs/chapter09/09-graph6.svg b/docs/chapter09/09-graph6.svg
new file mode 100644
index 00000000..b573d88a
--- /dev/null
+++ b/docs/chapter09/09-graph6.svg
@@ -0,0 +1,87 @@
+<svg aria-label="Compiler graph" width="350" height="360" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 350 360" 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; }
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+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="n9" data-id="9" transform="translate(44,172)" 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_arg</tspan><tspan class="node-id">  #9</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#9 φ_arg
+Type not computed
+
+[0] → — ASSOC
+[1] → #4 DATA
+[2] → #25 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="n21" data-id="21" transform="translate(24,276)" 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
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+Type not computed
+
+</title></g><g class="node" id="n25" data-id="25" transform="translate(176,276)" 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>+</tspan><tspan class="node-id">  #25</tspan></text><text class="type" text-anchor="middle" y="35" x="60"/><title>#25 +
+Type not computed
+
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+[1] → #9 DATA
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diff --git a/docs/chapter09/Makefile b/docs/chapter09/Makefile
new file mode 100644
index 00000000..6fa0f057
--- /dev/null
+++ b/docs/chapter09/Makefile
@@ -0,0 +1 @@
+include ../../graph/docs.mk
diff --git a/docs/chapter09/README.md b/docs/chapter09/README.md
new file mode 100644
index 00000000..c327b20d
--- /dev/null
+++ b/docs/chapter09/README.md
@@ -0,0 +1,310 @@
+# Chapter 9: Global Value Numbering and Iterative Peepholes
+
+[Previous: Chapter 8](../chapter08/README.md) |
+[Next: Chapter 10](../chapter10/README.md)
+
+# Table of Contents
+
+1. [Engineering Peepholes](#engineering-peepholes)
+2. [Global Value Numbering](#global-value-numbering)
+3. [Post-Parse Iterative Peepholes](#post-parse-iterative-peepholes)
+4. [Distant Neighbors](#distant-neighbors)
+5. [Other Concerns](#other-concerns)
+6. [Common SubExpressions via GVN](#common-subexpressions-via-gvn)
+ - [Example 1](#example-1)
+ - [Example 2](#example-2)
+7. [Post Parse Iterative Optimizations](#post-parse-iterative-optimizations)
+
+You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter09) 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-chapter08...linear-chapter09) it to the previous chapter.
+
+In this chapter:
+
+* We add Global Value Numbering (Common Subexpression Elimination)
+* We add a post-parse iterate-peepholes-to-fixed-point optimization
+
+No language changes in this chapter, just adding optimizations.
+
+
+## Engineering Peepholes
+
+The goal for Ch 9 is to "finish out" the Peepholes. Not that no more peeps will
+appear, on the contrary lots will - but this is the infrastructure to organize
+them, engineer them safe and sane; to apply them until a fixed point is reached.
+
+Really the goal here is to be fearless about adding a new peephole; if you got
+it wrong you'll assert pretty fast. If you got it right, that new peep will
+just run alongside all the others and they will all mutually benefit each other.
+
+
+## Global Value Numbering
+
+Global Value Numbering works via a classic hash table, hashing on a Node's
+opcode and inputs. If two Nodes do the same function on the same inputs, they
+get the same result - and can be shared.
+
+* We add a global static hash table `GVN` in Node.
+* We add a `Node.equals` call. Two Nodes are equal if they have the same
+ opcode - same Java class - on the same inputs.
+* We add a `hashCode` on the Node opcode (proxy: Node string name) and inputs.
+* `ConstantNode` and a few others need some extra custom bits here: the
+ constant 17 is not the same as 99, but both are the same `ConstantNode` class
+ and label. The `eq` and `hash` calls check (or hash) these extra bits.
+
+Note the intentional *value* equality here. In many places in Simple we use
+*reference* equality - e.g. node/edge maintenance is via reference equality, not
+value equality, so e.g. the `Utils.find()` call finds via reference. Throughout the Simple project whenever a Node lookup is happening, beware if it's via
+*value* or *reference* equality; this is not always explicitly called out but
+should be obvious from context.
+
+
+Since we edit the graph a lot, Nodes can have their inputs change which changes
+their hash which means they can't be found in the GVN table. E.g. we swap out
+the `Add` for a `Con` in:
+
+ (Mul (Add 4 8) x) // Fold the constant
+ (Mul 12 x) // The `Mul` changes hash and inputs
+
+The fix for this is to require Nodes NOT be in the `GVN` table when their edges
+modify; they need some sort of "edge lock". If "edges are locked", we need to
+remove the Node from `GVN` first, before modifying the edges.
+
+* We use the `_hash` field as both a cached hash code and as the edge lock. If
+ zero the Node is unlocked and NOT in `GVN`. If non-zero, the Node is
+ "edge-locked" and IS in `GVN`.
+* The `hashCode` function uses the cached hash if available and disallows an
+ accidental zero hash.
+* We add an `unlock()` call to remove a Node from `GVN` before any edge is
+ changed. This is inserted in front of all calls which hack Node edges. All
+ edge modify code paths already ensure the Node is re-peepholed, and during
+ this revisit the Node will get re-inserted in the `GVN` table.
+
+This new `GVN` table is used in `peepholeOpt()` (and `peephole()`) to look for common
+subexpressions on every peephole'd Node. If the Node has a zero hash, we look
+for a hit against some previous identical Node. If found, we use the prior
+Node and dead-code-eliminate this one. If not found, we insert this Node
+into `GVN` as the "golden instance". If a Node already has a non-zero hash
+we know it IS the "golden instance" and do not need to look in `GVN`.
+
+This entire optimization takes about a dozen lines in `iter()`, plus the common
+shared `equals` and `hashCode` (about 50 more lines counting comments).
+
+One of our invariants is that Types monotonically increase while running
+peepholes. GVN can break this briefly: of the two equivalent Nodes one has
+already had its `_type` lifted but not the other. Depending on which of the
+two Nodes is kept, we might choose the Node with the "lower" `_type`. This is
+"lower" in the Type lattice sense. Both types must be correct, and a
+`compute()` call on both nodes must produce the same Type, which must be equal
+to the JOIN. A fix is to compute a JOIN (not a MEET) over the two Nodes' types.
+
+
+## Post-Parse Iterative Peepholes
+
+The post-Parse `IterPeeps` iterates the peepholes to a fixed point - so
+no more peepholes apply. This should be linear because peepholes rarely
+(never?) increase code size. The graph should monotonically reduce in some
+dimension, which is usually size. It might also reduce in e.g. number of
+MulNodes or Load/Store nodes, swapping out more "expensive" Nodes for cheaper
+ones.
+
+The theoretical overall worklist is mindless just grabbing the next thing and
+doing it. If the graph changes, put the neighbors on the worklist. Lather,
+Rinse, Repeat until the worklist runs dry.
+
+The main issues we have to deal with:
+
+* Nodes have uses; replacing some set of Nodes with another requires more graph
+ reworking. Not rocket science, but it can be fiddly. It's helpful to have a
+ small set of graph munging utilities, and the strong invariant that the graph
+ is stable and correct between peepholes. In our case `Node.subsume` does
+ most of the munging, building on our prior stable Node utilities.
+
+* Changing a Node also changes the graph "neighborhood". The neighbors need to
+ be checked to see if THEY can also peephole, and so on. After any peephole
+ or graph update we put a Node's uses and defs on the worklist.
+
+* Our strong invariant is that for all Nodes, either they are on the worklist
+ OR no peephole applies. This invariant is easy to check, although expensive.
+ Basically the normal "iterate peepholes to a fixed point" is linear, and this
+ check is linear at each peephole step... so quadratic overall. It's a useful
+ assert, but one we can disable once the overall algorithm is stable - and
+ then turn it back on again when some new set of peepholes is misbehaving.
+ The code for this is turned on in `IterPeeps.iterate` as `assert
+ progressOnList(stop);`
+
+
+## Distant Neighbors
+
+For some peepholes the "neighborhood" is farther away than just the immediate
+uses or defs, and for these we need a longer range plan. E.g. some peephole
+inspects "this -> A -> B -> C" and will swap itself for "D"; however it fails
+some test at "B". Should "B" ever update we want to revisit "this" and recheck
+his peepholes. So we will need to record a dependence of "this" in "B".
+Updating "B" throws the dependent list ("this") onto the "todo" list.
+
+An example of a distant neighbor check is in `AddNode`, where we check for
+stacked constants: `(Add (Add x 2) 1)` and we'd like `(Add x 3)` instead.
+Suppose we're doing this check and we find instead `(Add (Phi (Add x 2) self)
+1)` The check naturally bails out at the `Phi` since it's not an `Add`, but the
+`(Phi y self)` only has one unique input, and will itself peephole to `y`
+eventually. When it does, our stacked `Add` peephole can apply. So the
+failing Add peephole calls `phi.addDep(Add)` and registers a dependency on the
+`Phi`. If the `Phi` indeed later optimizes, we add its dependencies (e.g. the
+`Add`) back on our `IterPeeps` worklist and retry the stacked Add peephole.
+
+The general rule is:
+* **If a peephole pattern inspects a remote node, it must go on the dependency list!**
+* `node.in(1).in(2)` becomes `node.in(1).in(2).addDep(node)`
+
+
+In this chapter we trigger on following patterns
+
+* Some peeps interact with `Phi` inputs; this can be direct or indirect,
+ e.g. `(Add Add( (Phi x) 2 ) 1)`. The peep can progress if all of the `Phi`'s
+ inputs are `Constant`'s. Thus, we make the node a dependent on the `Phi`'s
+ input. We also make the node a dependent of the `Phi`'s region. See
+ `Node.allCons()` and `PhiNode.allCons()`.
+* The pattern `(Add (Add x 1) 2)` adds the outer `Add` as dependency of `x`
+ because `x` becoming a constant would enable progress. See
+ `AddNode.idealize()`
+* When computing a `Phi`'s type, if we observe that the associated region's
+ corresponding control is live, we add the `Phi` as a dependent of the
+ region's control input, because if that control goes dead, it would allow the
+ `Phi` to undergo peephole. See `PhiNode.compute()` and
+ `PhiNode.singleUniqueInput()`.
+
+Changes:
+
+* We add an `ArrayList<Node> _deps` field to Node; initially null.
+* Some peepholes (see above) add dependencies if they fail a remote check, by calling
+ `distant.addDep(this)`. The `addDep` call creates `_deps` and
+ filters for various kinds of duplicate adds.
+* The `IterPeeps` loop, when it finds a change, also moves all the
+ dependents onto the worklist.
+
+
+
+# Examples
+
+## Common SubExpressions via GVN
+
+These diagrams focus on value dependencies. Routine control flow is omitted;
+small True/False projections distinguish the two Returns in the first example.
+Empty control slots can stand for omitted context, not missing compiler inputs.
+
+### Example 1
+
+Here is a small example that illustrates how GVN enables finding common sub-expressions.
+
+```java
+int x = arg + arg;
+if(arg < 10) {
+ return arg + arg;
+}
+else {
+ x = x + 1;
+}
+return x;
+```
+
+Prior to GVN, this would result in the following graph. Note that the `arg+arg` is translated to `arg*2`.
+
+![Graph1](./09-graph1.svg)
+
+Adding GVN, we get below. Note how the `arg*2` expression is now reused rather than appearing twice.
+
+![Graph2](./09-graph2.svg)
+
+### Example 2
+
+Being able to reuse common expressions, enables additional optimizations. Here is a simple example:
+
+```java
+return arg*arg-arg*arg;
+```
+
+Without GVN the peepholes cannot see that both sides of the subtraction have the same value.
+
+![Graph3](./09-graph3.svg)
+
+- Each multiplication(*) node has two edges going to `arg`.
+- The input-slot labels distinguish these two uses of the same definition.
+
+With GVN, the peepholes can do a better job:
+
+![Graph4](./09-graph4.svg)
+
+## Post Parse Iterative Optimizations
+
+The worklist based post parse optimization enables certain optimizations that are not available
+during parsing. For example:
+
+```java
+int step = 1;
+while (arg < 10) {
+ arg = arg + step + 1;
+}
+return arg;
+```
+
+While parsing the `while` loop it is not yet known that `step` is a constant and will not change. Therefore,
+without the post parse optimization we get the following:
+
+The loop test and control backedge are omitted in both diagrams. The Phi's
+data backedge remains, making the repeated additions and their replacement
+easy to compare; its input 1 is the entry value and input 2 the next iteration.
+
+![Graph5](./09-graph5.svg)
+
+Enabling the post parse worklist based optimization yields below. Notice that now the graph shows `arg+2` inside the
+loop body:
+
+![Graph6](./09-graph6.svg)
+
+
+## Future Work
+
+There are more issues we will want to deal with in a later Chapter:
+
+* Blindly running peepholes in any order has some drawbacks:
+
+ - Dead and dying stuff might get peepholes done... and then die. Wasted work.
+ - Dead infinite loops often lead to infinite peephole cycles... if only we
+ would get around to working on the "base" of the dead loop it would fold
+ up.
+ - Some peepholes naturally reduce the graph directly; while some keep its
+ size the same but reduce other things (e.g. swapping a Mul-by-2 with a
+ Shift), and we might end up with a few which try to grow the graph briefly
+ before collapsing.
+
+* All this means is there's some benefit to running peepholes that reduce the
+ graph directly (e.g. Dead Code Eliminate), before running peeps that reduce
+ other things, before running all other peeps. This implies a sorted
+ worklist, but the count of unique orders is really limited - a radix sort is
+ all that is needed. We'll have to break up the peepholes into some
+ categories like
+ - "strictly reducing" vs
+ - "same Nodes but swapping e.g. `Mul` for `Shift`, vs
+ - getting more freedom (edge bypass), vs
+ - "grow now because shrink later" (inlining lands in this camp).
+
+* Also there's a benefit to not always grabbing from either end of the list -
+ many peep patterns might go quadratic if approached from one end or another,
+ because they modify something then push it back onto the list where it
+ immediately gets pulled again. I.e., you end up spinning in a loop repeating
+ the same peeps while slowly migrating e.g. left-spine add-tree into a
+ right-spine add-tree. A pseudo-random pull uses randomization to defeat bad
+ peep patterns.
+
+* Why isn't `IterPeeps` just passing over all of the Nodes once or twice,
+ instead of using a worklist with the `addDeps` mechanism? We could even
+ visit them in a defs-before-uses order (e.g. Reverse Post Order).
+
+ In the absence of loops exactly one such pass will find all local peepholes,
+ and indeed the Parser already does this. However, this will fail to find
+ opportunities at loops and farther remote cases - and to get those peepholes
+ around loops will require another visit. It is easy to construct a case
+ requiring O(N) passes, each of cost O(N) and the algorithm quickly goes
+ quadratic.
+
+ The `addDeps` solution avoids this quadratic cost, in exchange for some more
+ costs in writing peepholes.
generated by cgit v1.2.3 (git 2.25.1) at 2026-10-15 16:01:57 +0000