[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/mips/code-stubs-mips.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3464 matching lines @@
   __ lbu(scratch1, MemOperand(scratch3));
   __ Addu(scratch3, right, index);
   __ lbu(scratch2, MemOperand(scratch3));
   __ Branch(chars_not_equal, ne, scratch1, Operand(scratch2));
   __ Addu(index, index, 1);
   __ Branch(&loop, ne, index, Operand(zero_reg));
 }
 
 
 void StringCompareStub::Generate(MacroAssembler* masm) {
-  Label runtime;
-
-  Counters* counters = isolate()->counters();
-
-  // Stack frame on entry.
-  //  sp[0]: right string
-  //  sp[4]: left string
-  __ lw(a1, MemOperand(sp, 1 * kPointerSize));  // Left.
-  __ lw(a0, MemOperand(sp, 0 * kPointerSize));  // Right.
+  // ----------- S t a t e -------------
+  //  -- a1    : left
+  //  -- a0    : right
+  //  -- ra    : return address
+  // -----------------------------------
+  __ AssertString(a1);
+  __ AssertString(a0);
 
   Label not_same;
   __ Branch(&not_same, ne, a0, Operand(a1));
-  STATIC_ASSERT(EQUAL == 0);
-  STATIC_ASSERT(kSmiTag == 0);
   __ li(v0, Operand(Smi::FromInt(EQUAL)));
-  __ IncrementCounter(counters->string_compare_native(), 1, a1, a2);
-  __ DropAndRet(2);
+  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, a1,
+                      a2);
+  __ Ret();
 
   __ bind(&not_same);
 
   // Check that both objects are sequential one-byte strings.
+  Label runtime;
   __ JumpIfNotBothSequentialOneByteStrings(a1, a0, a2, a3, &runtime);
 
-  // Compare flat ASCII strings natively. Remove arguments from stack first.
-  __ IncrementCounter(counters->string_compare_native(), 1, a2, a3);
-  __ Addu(sp, sp, Operand(2 * kPointerSize));
+  // Compare flat ASCII strings natively.
+  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, a2,
+                      a3);
   StringHelper::GenerateCompareFlatOneByteStrings(masm, a1, a0, a2, a3, t0, t1);
 
   __ bind(&runtime);
+  __ Push(a1, a0);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 
 void BinaryOpICWithAllocationSiteStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- a1    : left
   //  -- a0    : right
   //  -- ra    : return address
   // -----------------------------------
@@ skipping 2213 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS