[turbofan] Fix a bug in the RawMachineAssembler

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index bc8c13c07a0153546a1220ca74295e934d2672c5..935459243a4a5dd2bb25b4b77b251e49bdb70f92 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1449,17 +1449,26 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
       case IrOpcode::kWord32Equal:
       case IrOpcode::kWord64Equal: {
         Int64BinopMatcher m(value);
+        bool is_word64 = value->opcode() == IrOpcode::kWord64Equal;
         if (m.right().Is(0)) {
           user = value;
           value = m.left().node();
-          cont.Negate();
-          continue;
+          switch (value->opcode()) {
+            case IrOpcode::kLoad:

[Benedikt Meurer, 2016/02/11 05:13:53]

This looks rather hacky to me, esp. hunting for Load/Phi and special casing
those. Only Word32Equal with 0 is ever used to negate a condition (actually
maybe we should really consider introducing BitEqual to avoid the confusion), so
performing this optimization for Word64Equal will probably not help anyway.

[epertoso, 2016/02/11 13:47:47]

Yeah, I traced back the issue to the use of Word64BinaryNot. I've removed it
from the RawMachineAssembler.

+            case IrOpcode::kPhi:
+              cont.OverwriteAndNegateIfEqual(kEqual);
+              return VisitCompareZero(this, value,
+                                      is_word64 ? kX64Cmp : kX64Cmp32, &cont);
+            default:
+              cont.Negate();
+              continue;
+          }
         }
         cont.OverwriteAndNegateIfEqual(kEqual);
-        return VisitWordCompare(
-            this, value,
-            value->opcode() == IrOpcode::kWord64Equal ? kX64Cmp : kX64Cmp32,
-            &cont);
+        if (is_word64) {
+          return VisitWord64Compare(this, value, &cont);
+        }
+        return VisitWordCompare(this, value, kX64Cmp32, &cont);
       }
       case IrOpcode::kInt32LessThan:
         cont.OverwriteAndNegateIfEqual(kSignedLessThan);
@@ -1542,12 +1551,6 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
         return VisitWordCompare(this, value, kX64Test32, &cont);
       case IrOpcode::kWord64And:
         return VisitWordCompare(this, value, kX64Test, &cont);
-      case IrOpcode::kLoad:
-        if (LoadRepresentationOf(value->op()).representation() ==
-            MachineRepresentation::kWord64) {
-          return VisitCompareZero(this, value, kX64Cmp, &cont);
-        }
-        break;
       default:
         break;
     }
@@ -1555,7 +1558,7 @@ void InstructionSelector::VisitBranch(Node* branch, BasicBlock* tbranch,
   }
 
   // Branch could not be combined with a compare, emit compare against 0.
-  VisitCompareZero(this, value, kX64Cmp32, &cont);
+  VisitCompareZero(this, value, kX64Cmp, &cont);
 }