UF LRGs can be null during coloring

SeaOfNodes · Feb 13, 2025 · faa8cbf · faa8cbf
1 parent 9951333
commit faa8cbf
Show file tree

Hide file tree

Showing 3 changed files with 20 additions and 1 deletion.
diff --git a/chapter20/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java b/chapter20/src/main/java/com/seaofnodes/simple/codegen/BuildLRG.java
@@ -2,6 +2,7 @@
 
 import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeMem;
 
 abstract public class BuildLRG {
     // Compute live ranges in a single forwards pass.  Every def is a new live
@@ -32,7 +33,7 @@ public static boolean run(int round, RegAlloc alloc) {
                             }
                         }
 
-                } else if( n instanceof PhiNode phi ) {
+                } else if( n instanceof PhiNode phi && !(phi._type instanceof TypeMem) ) {
                     // All 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);

diff --git a/chapter20/src/main/java/com/seaofnodes/simple/codegen/IFG.java b/chapter20/src/main/java/com/seaofnodes/simple/codegen/IFG.java
@@ -287,6 +287,7 @@ public static boolean color(int round, RegAlloc alloc) {
                 swap(color_stack,sptr,pickRisky(color_stack,sptr));
             // Pick a trivial lrg, and (temporarily) remove from the IFG.
             LRG lrg = color_stack[sptr++];
+            if( lrg==null ) continue;
             // If sptr was swork, then pulled an at-risk lrg
             if( sptr > swork )
                 swork = sptr;
@@ -310,6 +311,7 @@ public static boolean color(int round, RegAlloc alloc) {
         // Reverse simplify (unstack the color stack), and set colors (registers) for live ranges
         while( sptr > 1 ) {
             LRG lrg = color_stack[--sptr];
+            if( lrg==null ) continue;
             RegMaskRW rmask = lrg._mask.copy();
             // Walk neighbors and remove adjacent colors
             if( lrg._adj!=null ) {

diff --git a/chapter20/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter20/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -50,4 +50,20 @@ public void testAlloc2() {
         assertEquals("return .[];", code.print());
     }
 
+    @Test
+    public void testArray1() {
+        CodeGen code = new CodeGen(
+"""
+int[] !ary = new int[arg];
+// Fill [0,1,2,3,4,...]
+for( int i=0; i<ary#; i++ )
+    ary[i] = i;
+// Fill [0,1,3,6,10,...]
+for( int i=0; i<ary#-1; i++ )
+    ary[i+1] += ary[i];
+return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
+""");
+        code.parse().opto().typeCheck().instSelect("x86_64_v2", "SystemV").GCM().localSched().regAlloc();
+        assertEquals("return .[];", code.print());
+    }
 }