Lithium: avoid registers for constants when possible.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // 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 6007 matching lines @@
   } else {
     Register size = ToRegister(instr->size());
     __ Allocate(size, result, temp, no_reg, deferred->entry(), flags);
   }
 
   __ bind(deferred->exit());
 }
 
 
 void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
-  Register size = ToRegister(instr->size());
   Register result = ToRegister(instr->result());
 
-  __ SmiTag(size);
-  PushSafepointRegistersScope scope(this);
   // 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.
-  if (!size.is(result)) {
-    __ StoreToSafepointRegisterSlot(result, size);
+  __ mov(result, Immediate(Smi::FromInt(0)));
+
+  PushSafepointRegistersScope scope(this);
+  if (instr->size()->IsRegister()) {
+    Register size = ToRegister(instr->size());
+    ASSERT(!size.is(result));
+    __ SmiTag(ToRegister(instr->size()));
+    __ push(size);
+  } else {
+    int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
+    __ push(Immediate(Smi::FromInt(size)));
   }
-  __ push(size);
+
   if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
     CallRuntimeFromDeferred(
         Runtime::kAllocateInOldPointerSpace, 1, instr, instr->context());
   } else {
     CallRuntimeFromDeferred(
         Runtime::kAllocateInNewSpace, 1, instr, instr->context());
   }
   __ StoreToSafepointRegisterSlot(result, eax);
 }
 
@@ skipping 533 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32