MIPS: Lithium: avoid registers for constants when possible.

src/mips/lithium-codegen-mips.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 5132 matching lines @@
                 scratch2,
                 deferred->entry(),
                 flags);
   }
 
   __ bind(deferred->exit());
 }
 
 
 void LCodeGen::DoDeferredAllocate(LAllocate* instr) {
-  Register size = ToRegister(instr->size());
   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.
   __ mov(result, zero_reg);
 
   PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
-  __ SmiTag(size, size);
-  __ push(size);
+  if (instr->size()->IsRegister()) {
+    Register size = ToRegister(instr->size());
+    ASSERT(!size.is(result));
+    __ SmiTag(size);
+    __ push(size);
+  } else {
+    int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
+    __ Push(Smi::FromInt(size));
+  }
+
   if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
     CallRuntimeFromDeferred(
         Runtime::kAllocateInOldPointerSpace, 1, instr);
   } else {
     CallRuntimeFromDeferred(
         Runtime::kAllocateInNewSpace, 1, instr);
   }
   __ StoreToSafepointRegisterSlot(v0, result);
 }
 
@@ skipping 560 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal