​MIPS: Improve Cvt_d_uw on mips32.

src/crankshaft/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 4502 matching lines @@
     __ mtc1(ToRegister(input), single_scratch);
   }
   __ cvt_d_w(ToDoubleRegister(output), single_scratch);
 }
 
 
 void LCodeGen::DoUint32ToDouble(LUint32ToDouble* instr) {
   LOperand* input = instr->value();
   LOperand* output = instr->result();
 
-  FPURegister dbl_scratch = double_scratch0();
-  __ mtc1(ToRegister(input), dbl_scratch);
-  __ Cvt_d_uw(ToDoubleRegister(output), dbl_scratch, f22);
+  __ Cvt_d_uw(ToDoubleRegister(output), ToRegister(input), f22);
 }
 
 
 void LCodeGen::DoNumberTagI(LNumberTagI* instr) {
   class DeferredNumberTagI final : public LDeferredCode {
    public:
     DeferredNumberTagI(LCodeGen* codegen, LNumberTagI* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     void Generate() override {
       codegen()->DoDeferredNumberTagIU(instr_,
@@ skipping 64 matching lines @@
     // There was overflow, so bits 30 and 31 of the original integer
     // disagree. Try to allocate a heap number in new space and store
     // the value in there. If that fails, call the runtime system.
     if (dst.is(src)) {
       __ SmiUntag(src, dst);
       __ Xor(src, src, Operand(0x80000000));
     }
     __ mtc1(src, dbl_scratch);
     __ cvt_d_w(dbl_scratch, dbl_scratch);
   } else {
-    __ mtc1(src, dbl_scratch);
-    __ Cvt_d_uw(dbl_scratch, dbl_scratch, f22);
+    __ Cvt_d_uw(dbl_scratch, src, f22);
   }
 
   if (FLAG_inline_new) {
     __ LoadRoot(tmp3, Heap::kHeapNumberMapRootIndex);
     __ AllocateHeapNumber(dst, tmp1, tmp2, tmp3, &slow, DONT_TAG_RESULT);
     __ Branch(&done);
   }
 
   // Slow case: Call the runtime system to do the number allocation.
   __ bind(&slow);
@@ skipping 1209 matching lines @@
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8