[compiler] Introduce StringEqualStub and StringNotEqualStub.

src/crankshaft/arm64/lithium-codegen-arm64.cc

 // Copyright 2013 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 "src/crankshaft/arm64/lithium-codegen-arm64.h"
 
 #include "src/arm64/frames-arm64.h"
 #include "src/base/bits.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 5175 matching lines @@
                           instr->context());
   __ StoreToSafepointRegisterSlot(x0, result);
 }
 
 
 void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
   DCHECK(ToRegister(instr->left()).is(x1));
   DCHECK(ToRegister(instr->right()).is(x0));
 
-  Handle<Code> code = CodeFactory::StringCompare(isolate()).code();
-  CallCode(code, RelocInfo::CODE_TARGET, instr);
+  if (Token::IsOrderedRelationalCompareOp(instr->op())) {
+    Handle<Code> code = CodeFactory::StringCompare(isolate()).code();
+    CallCode(code, RelocInfo::CODE_TARGET, instr);
 
-  EmitCompareAndBranch(instr, TokenToCondition(instr->op(), false), x0, 0);
+    EmitCompareAndBranch(instr, TokenToCondition(instr->op(), false), x0, 0);
+  } else {
+    Handle<Code> code = CodeFactory::StringEqual(isolate()).code();
+    CallCode(code, RelocInfo::CODE_TARGET, instr);
+    __ CompareRoot(x0, Heap::kTrueValueRootIndex);
+
+    EmitBranch(instr, TokenToCondition(instr->op(), false));
+  }
 }
 
 
 void LCodeGen::DoSubI(LSubI* instr) {
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
   Register result = ToRegister32(instr->result());
   Register left = ToRegister32(instr->left());
   Operand right = ToShiftedRightOperand32(instr->right(), instr);
 
   if (can_overflow) {
@@ skipping 443 matching lines @@
 
 
 void LCodeGen::DoStoreFrameContext(LStoreFrameContext* instr) {
   Register context = ToRegister(instr->context());
   __ Str(context, MemOperand(fp, StandardFrameConstants::kContextOffset));
 }
 
 
 }  // namespace internal
 }  // namespace v8