[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/arm/code-stubs-arm.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_ARM
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3301 matching lines @@
   __ ldrb(scratch1, MemOperand(left, index));
   __ ldrb(scratch2, MemOperand(right, index));
   __ cmp(scratch1, scratch2);
   __ b(ne, chars_not_equal);
   __ add(index, index, Operand(1), SetCC);
   __ b(ne, &loop);
 }
 
 
 void StringCompareStub::Generate(MacroAssembler* masm) {
-  Label runtime;
-
-  Counters* counters = isolate()->counters();
-
-  // Stack frame on entry.
-  //  sp[0]: right string
-  //  sp[4]: left string
-  __ Ldrd(r0 , r1, MemOperand(sp));  // Load right in r0, left in r1.
+  // ----------- S t a t e -------------
+  //  -- r1    : left
+  //  -- r0    : right
+  //  -- lr    : return address
+  // -----------------------------------
+  __ AssertString(r1);
+  __ AssertString(r0);
 
   Label not_same;
   __ cmp(r0, r1);
   __ b(ne, &not_same);
-  STATIC_ASSERT(EQUAL == 0);
-  STATIC_ASSERT(kSmiTag == 0);
   __ mov(r0, Operand(Smi::FromInt(EQUAL)));
-  __ IncrementCounter(counters->string_compare_native(), 1, r1, r2);
-  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, r1,
+                      r2);
   __ Ret();
 
   __ bind(&not_same);
 
   // Check that both objects are sequential one-byte strings.
+  Label runtime;
   __ JumpIfNotBothSequentialOneByteStrings(r1, r0, r2, r3, &runtime);
 
-  // Compare flat one-byte strings natively. Remove arguments from stack first.
-  __ IncrementCounter(counters->string_compare_native(), 1, r2, r3);
-  __ add(sp, sp, Operand(2 * kPointerSize));
+  // Compare flat one-byte strings natively.
+  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, r2,
+                      r3);
   StringHelper::GenerateCompareFlatOneByteStrings(masm, r1, r0, r2, r3, r4, r5);
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
+  __ Push(r1, r0);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 
 void BinaryOpICWithAllocationSiteStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- r1    : left
   //  -- r0    : right
   //  -- lr    : return address
   // -----------------------------------
@@ skipping 2174 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM