[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 3049ddbce2544e4ad20122e603b3f37c34665787..b163061458ec1376cfd4623c957df2138a0df90c 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -1065,11 +1065,6 @@ 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();
   }
@@ -2534,17 +2529,14 @@ static Condition ComputeCompareCondition(Token::Value op) {
 
 void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
-  Token::Value op = instr->op();
+  DCHECK(ToRegister(instr->left()).is(r1));
+  DCHECK(ToRegister(instr->right()).is(r0));
 
-  Handle<Code> ic =
-      CodeFactory::CompareIC(isolate(), op, Strength::WEAK).code();
-  CallCode(ic, RelocInfo::CODE_TARGET, instr);
-  // This instruction also signals no smi code inlined.
+  Handle<Code> code = CodeFactory::StringCompare(isolate()).code();
+  CallCode(code, RelocInfo::CODE_TARGET, instr);
   __ cmp(r0, Operand::Zero());
 
-  Condition condition = ComputeCompareCondition(op);
-
-  EmitBranch(instr, condition);
+  EmitBranch(instr, ComputeCompareCondition(instr->op()));
 }