[turbofan] Fix a bug in the RawMachineAssembler

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
@@ skipping 1431 matching lines @@
   Node* value = branch->InputAt(0);
 
   FlagsContinuation cont(kNotEqual, tbranch, fbranch);
 
   // Try to combine the branch with a comparison.
   while (CanCover(user, value)) {
     switch (value->opcode()) {
       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);
         return VisitWordCompare(this, value, kX64Cmp32, &cont);
       case IrOpcode::kInt32LessThanOrEqual:
         cont.OverwriteAndNegateIfEqual(kSignedLessThanOrEqual);
         return VisitWordCompare(this, value, kX64Cmp32, &cont);
       case IrOpcode::kUint32LessThan:
         cont.OverwriteAndNegateIfEqual(kUnsignedLessThan);
         return VisitWordCompare(this, value, kX64Cmp32, &cont);
@@ skipping 62 matching lines @@
         }
         break;
       case IrOpcode::kInt32Sub:
         return VisitWordCompare(this, value, kX64Cmp32, &cont);
       case IrOpcode::kInt64Sub:
         return VisitWord64Compare(this, value, &cont);
       case IrOpcode::kWord32And:
         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;
     }
     break;
   }
 
   // Branch could not be combined with a compare, emit compare against 0.
-  VisitCompareZero(this, value, kX64Cmp32, &cont);
+  VisitCompareZero(this, value, kX64Cmp, &cont);
 }
 
 
 void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   X64OperandGenerator g(this);
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
   size_t table_space_cost = 4 + sw.value_range;
   size_t table_time_cost = 3;
@@ skipping 243 matching lines @@
              MachineOperatorBuilder::kFloat64RoundTruncate |
              MachineOperatorBuilder::kFloat32RoundTiesEven |
              MachineOperatorBuilder::kFloat64RoundTiesEven;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8