[turbofan] Do not produce 2 ops for Int32AddWithOverflow.

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 1768 matching lines @@
     }
   }
   VisitWord64Compare(this, node, &cont);
 }
 
 
 void InstructionSelector::VisitInt32AddWithOverflow(Node* node) {
   if (Node* ovf = NodeProperties::FindProjection(node, 1)) {
     FlagsContinuation cont = FlagsContinuation::ForSet(kOverflow, ovf);
     VisitBinop(this, node, kX64Add32, &cont);
+  } else {

[Benedikt Meurer, 2016/03/03 17:48:09]

Please leave the version w/o the else, and instead add return above similar to
the rest of the file.

+    FlagsContinuation cont;
+    VisitBinop(this, node, kX64Add32, &cont);
   }
-  FlagsContinuation cont;
-  VisitBinop(this, node, kX64Add32, &cont);
 }
 
 
 void InstructionSelector::VisitInt32SubWithOverflow(Node* node) {
   if (Node* ovf = NodeProperties::FindProjection(node, 1)) {
     FlagsContinuation cont = FlagsContinuation::ForSet(kOverflow, ovf);
     return VisitBinop(this, node, kX64Sub32, &cont);
   }
   FlagsContinuation cont;
   VisitBinop(this, node, kX64Sub32, &cont);
@@ skipping 126 matching lines @@
              MachineOperatorBuilder::kFloat64RoundTruncate |
              MachineOperatorBuilder::kFloat32RoundTiesEven |
              MachineOperatorBuilder::kFloat64RoundTiesEven;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8