​MIPS: Improve Cvt_d_uw on mips32.

src/crankshaft/mips/lithium-codegen-mips.cc

Index: src/crankshaft/mips/lithium-codegen-mips.cc
diff --git a/src/crankshaft/mips/lithium-codegen-mips.cc b/src/crankshaft/mips/lithium-codegen-mips.cc
index fe0c1880ad66f84b8a1673ef33c41eb37af2653f..f8a38c0c60a34b4712f1fafa539f5ae1b3c2c260 100644
--- a/src/crankshaft/mips/lithium-codegen-mips.cc
+++ b/src/crankshaft/mips/lithium-codegen-mips.cc
@@ -4520,9 +4520,7 @@ 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);
 }
 
 
@@ -4607,8 +4605,7 @@ void LCodeGen::DoDeferredNumberTagIU(LInstruction* instr,
     __ 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) {