MIPS: DoNumberTagD performance improvement

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 4233 matching lines @@
     }
     __ mtc1(src, dbl_scratch);
     __ cvt_d_w(dbl_scratch, dbl_scratch);
   } else {
     __ mtc1(src, dbl_scratch);
     __ Cvt_d_uw(dbl_scratch, dbl_scratch, f22);
   }
 
   if (FLAG_inline_new) {
     __ LoadRoot(t2, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(t1, a3, t0, t2, &slow);
+    __ AllocateHeapNumber(t1, a3, t0, t2, &slow, DONT_TAG_RESULT);
     __ Move(dst, t1);
     __ Branch(&done);
   }
 
   // Slow case: Call the runtime system to do the number allocation.
   __ bind(&slow);
 
   // TODO(3095996): Put a valid pointer value in the stack slot where the result
   // register is stored, as this register is in the pointer map, but contains an
   // integer value.
   __ StoreToSafepointRegisterSlot(zero_reg, dst);
   CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr);
   __ Move(dst, v0);
+  __ Subu(dst, dst, kHeapObjectTag);
 
   // Done. Put the value in dbl_scratch into the value of the allocated heap
   // number.
   __ bind(&done);
-  __ sdc1(dbl_scratch, FieldMemOperand(dst, HeapNumber::kValueOffset));
+  __ sdc1(dbl_scratch, MemOperand(dst, HeapNumber::kValueOffset));
+  __ Addu(dst, dst, kHeapObjectTag);
   __ StoreToSafepointRegisterSlot(dst, dst);
 }
 
 
 void LCodeGen::DoNumberTagD(LNumberTagD* instr) {
   class DeferredNumberTagD: public LDeferredCode {
    public:
     DeferredNumberTagD(LCodeGen* codegen, LNumberTagD* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() { codegen()->DoDeferredNumberTagD(instr_); }
     virtual LInstruction* instr() { return instr_; }
    private:
     LNumberTagD* instr_;
   };
 
   DoubleRegister input_reg = ToDoubleRegister(instr->value());
   Register scratch = scratch0();
   Register reg = ToRegister(instr->result());
   Register temp1 = ToRegister(instr->temp());
   Register temp2 = ToRegister(instr->temp2());
 
   DeferredNumberTagD* deferred = new(zone()) DeferredNumberTagD(this, instr);
   if (FLAG_inline_new) {
     __ LoadRoot(scratch, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry());
+    // We want the untagged address first for performance
+    __ AllocateHeapNumber(reg, temp1, temp2, scratch, deferred->entry(),
+                          DONT_TAG_RESULT);
   } else {
     __ Branch(deferred->entry());
   }
   __ bind(deferred->exit());
-  __ sdc1(input_reg, FieldMemOperand(reg, HeapNumber::kValueOffset));
+  __ sdc1(input_reg, MemOperand(reg, HeapNumber::kValueOffset));
+  // Now that we have finished with the object's real address tag it
+  __ Addu(reg, reg, kHeapObjectTag);
 }
 
 
 void LCodeGen::DoDeferredNumberTagD(LNumberTagD* instr) {
   // 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.
   Register reg = ToRegister(instr->result());
   __ mov(reg, zero_reg);
 
   PushSafepointRegistersScope scope(this, Safepoint::kWithRegisters);
   CallRuntimeFromDeferred(Runtime::kAllocateHeapNumber, 0, instr);
+  __ Subu(v0, v0, kHeapObjectTag);
   __ StoreToSafepointRegisterSlot(v0, reg);
 }
 
 
 void LCodeGen::DoSmiTag(LSmiTag* instr) {
   ASSERT(!instr->hydrogen_value()->CheckFlag(HValue::kCanOverflow));
   __ SmiTag(ToRegister(instr->result()), ToRegister(instr->value()));
 }
 
 
@@ skipping 1176 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal