[compiler] Introduce StringEqualStub and StringNotEqualStub.

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

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2257 matching lines @@
       return kNoCondition;
   }
 }
 
 
 void LCodeGen::DoStringCompareAndBranch(LStringCompareAndBranch* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
   DCHECK(ToRegister(instr->left()).is(a1));
   DCHECK(ToRegister(instr->right()).is(a0));
 
-  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);
 
-  EmitBranch(instr, ComputeCompareCondition(instr->op()), v0,
-             Operand(zero_reg));
+    EmitBranch(instr, ComputeCompareCondition(instr->op()), v0,
+               Operand(zero_reg));
+  } else {
+    Handle<Code> code = CodeFactory::StringEqual(isolate()).code();
+    CallCode(code, RelocInfo::CODE_TARGET, instr);
+    __ LoadRoot(at, Heap::kTrueValueRootIndex);
+
+    EmitBranch(instr, ComputeCompareCondition(instr->op()), v0, Operand(at));
+  }
 }
 
 
 static InstanceType TestType(HHasInstanceTypeAndBranch* instr) {
   InstanceType from = instr->from();
   InstanceType to = instr->to();
   if (from == FIRST_TYPE) return to;
   DCHECK(from == to || to == LAST_TYPE);
   return from;
 }
@@ skipping 3196 matching lines @@
 void LCodeGen::DoStoreFrameContext(LStoreFrameContext* instr) {
   Register context = ToRegister(instr->context());
   __ sw(context, MemOperand(fp, StandardFrameConstants::kContextOffset));
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8