[SAB] Validate index before value conversion

src/compiler/ia32/instruction-selector-ia32.cc

Index: src/compiler/ia32/instruction-selector-ia32.cc
diff --git a/src/compiler/ia32/instruction-selector-ia32.cc b/src/compiler/ia32/instruction-selector-ia32.cc
index 6fd1ad56564e8f976705909f4105ab5d702875ea..84b6a4f3d1ef5551b18ecd6a2fc8895e29f90b3a 100644
--- a/src/compiler/ia32/instruction-selector-ia32.cc
+++ b/src/compiler/ia32/instruction-selector-ia32.cc
@@ -1864,11 +1864,7 @@ void InstructionSelector::VisitAtomicBinaryOperation(
   AddressingMode addressing_mode;
   InstructionOperand inputs[3];
   size_t input_count = 0;
-  if (type == MachineType::Int8() || type == MachineType::Uint8()) {
-    inputs[input_count++] = g.UseByteRegister(value);
-  } else {
-    inputs[input_count++] = g.UseUniqueRegister(value);
-  }
+  inputs[input_count++] = g.UseUniqueRegister(value);
   inputs[input_count++] = g.UseUniqueRegister(base);
   if (g.CanBeImmediate(index)) {
     inputs[input_count++] = g.UseImmediate(index);
@@ -1879,7 +1875,7 @@ void InstructionSelector::VisitAtomicBinaryOperation(
   }
   outputs[0] = g.DefineAsFixed(node, eax);
   InstructionOperand temp[1];
-  temp[0] = g.TempRegister();
+  temp[0] = g.UseByteRegister(node);

[aseemgarg, 2017/04/11 23:11:50]

Although this is correct, it might be better to force byte-register (edx) only
if it is Int8 or Uint8 type.

[binji, 2017/04/11 23:49:12]

Done.

   InstructionCode code = opcode | AddressingModeField::encode(addressing_mode);
   Emit(code, 1, outputs, input_count, inputs, 1, temp);
 }