[turbofan] Implemented the ChangeFloat64ToInt64 TurboFan operator.

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index c4be56d5859b98ec3dffe0fabb7765d0c1c56561..1c80ad85baa8fd6eb5eec196ea8e00fa17f47782 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -1020,6 +1020,13 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ AssertZeroExtended(i.OutputRegister());
       break;
     }
+    case kSSEFloat64ToInt64:
+      if (instr->InputAt(0)->IsDoubleRegister()) {
+        __ Cvttsd2siq(i.OutputRegister(), i.InputDoubleRegister(0));
+      } else {
+        __ Cvttsd2siq(i.OutputRegister(), i.InputOperand(0));
+      }
+      break;
     case kSSEInt32ToFloat64:
       if (instr->InputAt(0)->IsRegister()) {
         __ Cvtlsi2sd(i.OutputDoubleRegister(), i.InputRegister(0));