[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 16fe6694afbb664df1ad9dea458f4e5a8edf8574..99c0938b6a4b5110d0b28a7f70c61c2c9ac9c732 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -1071,11 +1071,6 @@ void LCodeGen::DoCallStub(LCallStub* instr) {
       CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
       break;
     }
-    case CodeStub::StringCompare: {
-      StringCompareStub stub(isolate());
-      CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-      break;
-    }
     default:
       UNREACHABLE();
   }
@@ -2441,16 +2436,15 @@ static Condition ComputeCompareCondition(Token::Value op) {
 
 
 void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
-  Token::Value op = instr->op();
-
-  Handle<Code> ic =
-      CodeFactory::CompareIC(isolate(), op, Strength::WEAK).code();
-  CallCode(ic, RelocInfo::CODE_TARGET, instr);
+  DCHECK(ToRegister(instr->context()).is(esi));
+  DCHECK(ToRegister(instr->left()).is(edx));
+  DCHECK(ToRegister(instr->right()).is(eax));
 
-  Condition condition = ComputeCompareCondition(op);
-  __ test(eax, Operand(eax));
+  Handle<Code> code = CodeFactory::StringCompare(isolate()).code();
+  CallCode(code, RelocInfo::CODE_TARGET, instr);
+  __ test(eax, eax);
 
-  EmitBranch(instr, condition);
+  EmitBranch(instr, ComputeCompareCondition(instr->op()));
 }