[turbofan][x64] Fix instruction selection for Word32Equal.

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 2054 matching lines @@
                 return VisitBinop(selector, node, kX64Sub, cont);
               default:
                 break;
             }
           }
         }
         break;
       case IrOpcode::kInt32Sub:
         return VisitWordCompare(selector, value, kX64Cmp32, cont);
       case IrOpcode::kInt64Sub:
         return VisitWord64Compare(selector, value, cont);

[Jarin, 2017/02/01 08:39:56]

UNREACHABLE() ?

       case IrOpcode::kWord32And:
         return VisitWordCompare(selector, value, kX64Test32, cont);
       case IrOpcode::kWord64And:
         return VisitWordCompare(selector, value, kX64Test, cont);

[Jarin, 2017/02/01 08:39:56]

UNREACHABLE() ?

       default:
         break;
     }
   }
 
   // Branch could not be combined with a compare, emit compare against 0.
   VisitCompareZero(selector, value, kX64Cmp32, cont);
 }
 
 }  // namespace
@@ skipping 58 matching lines @@
   // Generate a sequence of conditional jumps.
   return EmitLookupSwitch(sw, value_operand);
 }
 
 
 void InstructionSelector::VisitWord32Equal(Node* const node) {
   Node* user = node;
   FlagsContinuation cont = FlagsContinuation::ForSet(kEqual, node);
   Int32BinopMatcher m(user);
   if (m.right().Is(0)) {
-    Node* value = m.left().node();
-
-    // Try to combine with comparisons against 0 by simply inverting the branch.
-    while (CanCover(user, value) && value->opcode() == IrOpcode::kWord32Equal) {
-      Int32BinopMatcher m(value);
-      if (m.right().Is(0)) {
-        user = value;
-        value = m.left().node();
-        cont.Negate();
-      } else {
-        break;
-      }
-    }
-
-    // Try to combine the branch with a comparison.
-    if (CanCover(user, value)) {
-      switch (value->opcode()) {
-        case IrOpcode::kInt32Sub:
-          return VisitWordCompare(this, value, kX64Cmp32, &cont);
-        case IrOpcode::kWord32And:
-          return VisitWordCompare(this, value, kX64Test32, &cont);
-        default:
-          break;
-      }
-    }
-    return VisitCompareZero(this, value, kX64Cmp32, &cont);
+    return VisitWordCompareZero(this, m.node(), m.left().node(), &cont);
   }
   VisitWordCompare(this, node, kX64Cmp32, &cont);
 }
 
 
 void InstructionSelector::VisitInt32LessThan(Node* node) {
   FlagsContinuation cont = FlagsContinuation::ForSet(kSignedLessThan, node);
   VisitWordCompare(this, node, kX64Cmp32, &cont);
 }
 
@@ skipping 287 matching lines @@
 // static
 MachineOperatorBuilder::AlignmentRequirements
 InstructionSelector::AlignmentRequirements() {
   return MachineOperatorBuilder::AlignmentRequirements::
       FullUnalignedAccessSupport();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8