Reland "Introduce intrinsics for double values in Javascript."

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index a37a562cc9c560c8163812620cf083004d754e19..4df350d3e5ca82c48052b2b4f1c8fd9ed4d6285b 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -80,6 +80,7 @@ class LCodeGen;
   V(ConstantI)                                  \
   V(ConstantS)                                  \
   V(ConstantT)                                  \
+  V(ConstructDouble)                            \
   V(Context)                                    \
   V(DateField)                                  \
   V(DebugBreak)                                 \
@@ -88,6 +89,7 @@ class LCodeGen;
   V(DivByConstI)                                \
   V(DivByPowerOf2I)                             \
   V(DivI)                                       \
+  V(DoubleBits)                                 \
   V(DoubleToI)                                  \
   V(DoubleToSmi)                                \
   V(Drop)                                       \
@@ -2429,6 +2431,33 @@ class LCheckNonSmi V8_FINAL : public LTemplateInstruction<0, 1, 0> {
 };
 
 
+class LDoubleBits V8_FINAL : public LTemplateInstruction<1, 1, 0> {
+ public:
+  explicit LDoubleBits(LOperand* value) {
+    inputs_[0] = value;
+  }
+
+  LOperand* value() { return inputs_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(DoubleBits, "double-bits")
+  DECLARE_HYDROGEN_ACCESSOR(DoubleBits)
+};
+
+
+class LConstructDouble V8_FINAL : public LTemplateInstruction<1, 2, 0> {
+ public:
+  LConstructDouble(LOperand* hi, LOperand* lo) {
+    inputs_[0] = hi;
+    inputs_[1] = lo;
+  }
+
+  LOperand* hi() { return inputs_[0]; }
+  LOperand* lo() { return inputs_[1]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(ConstructDouble, "construct-double")
+};
+
+
 class LAllocate V8_FINAL : public LTemplateInstruction<1, 2, 1> {
  public:
   LAllocate(LOperand* context, LOperand* size, LOperand* temp) {