From d32f97238c903765dec4e9a9f3cbfa5fd12cded6 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Mon, 10 Aug 2026 11:11:18 -0700
Subject: Chapter 25: Modules, Separate Compilation, and SSA Construction

Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: Symious <14933944+symious@users.noreply.github.com>
Co-authored-by: Jun Kawasaki <jun784@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
---
 .../java/com/seaofnodes/simple/codegen/BuildLRG.java | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

(limited to 'src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java')

diff --git a/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java b/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java
index 2319714b..0b314978 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java
@@ -15,11 +15,16 @@ abstract public class BuildLRG {
     // since it will not color, just split the conflicted ranges now).  Returns
     // true if no hard-conflicts, although we still might not color.
     public static boolean run(int round, RegAlloc alloc) {
-        for( Node bb : alloc._code._cfg )
+        FunNode fun = null;
+        for( Node bb : alloc._code._cfg ) {
+            if( bb instanceof FunNode fun2 )
+                fun = fun2;
             for( Node n : bb.outs() ) {
                 // A synthetic never-exit value has no runtime definition.
                 if( n._type==Type.TOP ) continue;
                 if( n instanceof PhiNode phi && !(phi._type instanceof TypeMem) ) {
+                    if( phi instanceof MachNode mach && mach.outregmap()==null )
+                        continue;
                     // All real Phi inputs end up with the same LRG.
                     // Pass 1: find any pre-existing LRG, to avoid make-then-Union a LRG
                     LRG lrg = alloc.lrg(phi);
@@ -28,8 +33,8 @@ abstract public class BuildLRG {
                             if( (lrg = alloc.lrg(phi.in(i))) != null )
                                 break;
                     // If none, make one.
-                    if( lrg==null ) lrg = alloc.newLRG(n);
-                    if( phi instanceof MachNode ) defLRG(alloc,n);
+                    if( lrg==null ) lrg = alloc.newLRG(n,fun);
+                    if( phi instanceof MachNode ) defLRG(alloc,n,fun);
                     // Pass 2: everybody uses the same LRG
                     lrg=alloc.union(lrg,phi);
                     for( int i=phi instanceof ParmNode ? 2 : 1; i<n.nIns(); i++ )
@@ -51,7 +56,7 @@ abstract public class BuildLRG {
                     }
 
                     // Define live range
-                    defLRG(alloc,n);
+                    defLRG(alloc,n,fun);
 
                     // Now, look in the opposite direction. How are incoming
                     // LRGs affected by this node: For all uses, make live lrgs
@@ -71,8 +76,9 @@ abstract public class BuildLRG {
                 if( n instanceof MultiNode && !(n instanceof CFGNode) )
                     for( Node proj : n.outs() )
                         if( proj instanceof MachNode )
-                            defLRG(alloc,proj);
+                            defLRG(alloc,proj,fun);
             }
+        }
 
         // Collect live ranges
         alloc.unify();
@@ -80,12 +86,12 @@ abstract public class BuildLRG {
         return alloc.success();
     }
 
-    private static void defLRG( RegAlloc alloc, Node n ) {
+    private static void defLRG( RegAlloc alloc, Node n, FunNode fun ) {
         MachNode mach = (MachNode)n;
         RegMask def_mask = mach.outregmap();
         if( def_mask == null ) return;
         LRG lrg = mach.twoAddress() == 0
-            ? alloc.newLRG(n)                  // Define a new LRG for N
+            ? alloc.newLRG(n,fun)              // Define a new LRG for N
             : alloc.lrg2(n,mach.twoAddress()); // Use the matching 2-adr input
         // Record mask and mach
         if( !lrg.machDef(mach,def_mask.size1()).and(def_mask) )
-- 
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