Introduce intrinsics for double values in Javascript.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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
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   // smi
   __ bind(&is_smi);
   __ SmiToInteger32(input_reg, input_reg);
   __ ClampUint8(input_reg);
 
   __ bind(&done);
 }
 
 
+void LCodeGen::DoDoubleBits(LDoubleBits* instr) {
+  XMMRegister value_reg = ToDoubleRegister(instr->value());
+  Register result_reg = ToRegister(instr->result());
+  if (instr->hydrogen()->bits() == HDoubleBits::HIGH) {
+    __ movq(result_reg, value_reg);
+    __ shr(result_reg, Immediate(32));
+  } else {
+    __ movd(result_reg, value_reg);
+  }
+}
+
+
+void LCodeGen::DoConstructDouble(LConstructDouble* instr) {
+  Register hi_reg = ToRegister(instr->hi());
+  Register lo_reg = ToRegister(instr->lo());
+  XMMRegister result_reg = ToDoubleRegister(instr->result());
+  XMMRegister xmm_scratch = double_scratch0();
+  __ movd(result_reg, hi_reg);
+  __ psllq(result_reg, 32);
+  __ movd(xmm_scratch, lo_reg);
+  __ orps(result_reg, xmm_scratch);
+}
+
+
 void LCodeGen::DoAllocate(LAllocate* instr) {
   class DeferredAllocate V8_FINAL : public LDeferredCode {
    public:
     DeferredAllocate(LCodeGen* codegen, LAllocate* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() V8_OVERRIDE {
       codegen()->DoDeferredAllocate(instr_);
     }
     virtual LInstruction* instr() V8_OVERRIDE { return instr_; }
    private:
@@ skipping 520 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64