ARM: optimize Lithium Allocate

src/arm/lithium-codegen-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.
 
 #include "src/v8.h"
 
 #include "src/arm/lithium-codegen-arm.h"
 #include "src/arm/lithium-gap-resolver-arm.h"
 #include "src/code-stubs.h"
 #include "src/hydrogen-osr.h"
@@ skipping 5258 matching lines @@
 
   if (instr->size()->IsConstantOperand()) {
     int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
     if (size <= Page::kMaxRegularHeapObjectSize) {
       __ Allocate(size, result, scratch, scratch2, deferred->entry(), flags);
     } else {
       __ jmp(deferred->entry());
     }
   } else {
     Register size = ToRegister(instr->size());
-    __ Allocate(size,
-                result,
-                scratch,
-                scratch2,
-                deferred->entry(),
-                flags);
+    __ Allocate(size, result, scratch, scratch2, deferred->entry(), flags);
   }
 
   __ bind(deferred->exit());
 
   if (instr->hydrogen()->MustPrefillWithFiller()) {
+    STATIC_ASSERT(kHeapObjectTag == 1);
     if (instr->size()->IsConstantOperand()) {
       int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
-      __ mov(scratch, Operand(size));
+      __ mov(scratch, Operand(size - kHeapObjectTag));
     } else {
-      scratch = ToRegister(instr->size());
+      __ sub(scratch, ToRegister(instr->size()), Operand(kHeapObjectTag));
     }
-    __ sub(scratch, scratch, Operand(kPointerSize));
-    __ sub(result, result, Operand(kHeapObjectTag));
+    __ mov(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
     Label loop;
     __ bind(&loop);
-    __ mov(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    __ sub(scratch, scratch, Operand(kPointerSize), SetCC);
     __ str(scratch2, MemOperand(result, scratch));
-    __ sub(scratch, scratch, Operand(kPointerSize));
-    __ cmp(scratch, Operand(0));
     __ b(ge, &loop);
-    __ add(result, result, Operand(kHeapObjectTag));
   }
 }
 
 
 void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
   Register result = ToRegister(instr->result());
 
   // TODO(3095996): Get rid of this. For now, we need to make the
   // result register contain a valid pointer because it is already
   // contained in the register pointer map.
@@ skipping 517 matching lines @@
   __ Push(scope_info);
   __ push(ToRegister(instr->function()));
   CallRuntime(Runtime::kHiddenPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal