MIPS: optimize Lithium Allocate.

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // 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 5273 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()));
-      __ li(scratch, Operand(size));
+      __ li(scratch, Operand(size - kHeapObjectTag));
     } else {
-      scratch = ToRegister(instr->size());
+      __ Subu(scratch, ToRegister(instr->size()), Operand(kHeapObjectTag));
     }
-    __ Subu(scratch, scratch, Operand(kPointerSize));
-    __ Subu(result, result, Operand(kHeapObjectTag));
+    __ li(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
     Label loop;
     __ bind(&loop);
-    __ li(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    __ Subu(scratch, scratch, Operand(kPointerSize));
     __ Addu(at, result, Operand(scratch));
     __ sw(scratch2, MemOperand(at));
-    __ Subu(scratch, scratch, Operand(kPointerSize));
     __ Branch(&loop, ge, scratch, Operand(zero_reg));
-    __ Addu(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 560 matching lines @@
   __ li(at, scope_info);
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kHiddenPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal