MIPS: [turbofan] Support for %_DoubleHi, %_DoubleLo and %_ConstructDouble.

src/compiler/mips64/code-generator-mips64.cc

Index: src/compiler/mips64/code-generator-mips64.cc
diff --git a/src/compiler/mips64/code-generator-mips64.cc b/src/compiler/mips64/code-generator-mips64.cc
index 190001228c091c620fd501dc63800ff9745efeb3..ec290c2b4e3e06617ca982a45b94ba05df846a3d 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -685,6 +685,22 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ Trunc_uw_d(i.InputDoubleRegister(0), i.OutputRegister(), scratch);
       break;
     }
+    case kMips64FmoveLowUwD:
+      __ FmoveLow(i.OutputRegister(), i.InputDoubleRegister(0));
+      // remove sign.
+      __ li(at, Operand(32));
+      __ dsllv(i.OutputRegister(), i.OutputRegister(), at);
+      __ dsrlv(i.OutputRegister(), i.OutputRegister(), at);

[paul.l..., 2015/03/05 17:40:48]

You can avoid the load and use of 'at' register here by using:
__ dsll32(i.OutputRegister(), i.OutputRegister(), 0);
__ dsrl32(i.OutputRegister(), i.OutputRegister(), 0);

[balazs.kilvady, 2015/03/05 18:07:08]

Thanks, I modify it. Anyway test are passed without the 2 shifts I just added
them to ensure unsigned result. Could I drop it? 

[paul.l..., 2015/03/05 18:43:49]

Let's leave the shifts to strip sign extension for now, and re-check later.

+      break;
+    case kMips64FmoveLowDUw:
+      __ FmoveLow(i.OutputDoubleRegister(), i.InputRegister(1));
+      break;
+    case kMips64FmoveHighUwD:
+      __ FmoveHigh(i.OutputRegister(), i.InputDoubleRegister(0));
+      break;
+    case kMips64FmoveHighDUw:
+      __ FmoveHigh(i.OutputDoubleRegister(), i.InputRegister(1));
+      break;
     // ... more basic instructions ...
 
     case kMips64Lbu: