Introduce PushInt64AsTwoSmis and PopInt64AsTwoSmis macro instructions for X64

src/x64/debug-x64.cc

Index: src/x64/debug-x64.cc
diff --git a/src/x64/debug-x64.cc b/src/x64/debug-x64.cc
index e6bc92950a9c43f984c9b87e275eb9e35c75fab6..c8e1c96d9689da2ee3543154cd30c3c754c913b9 100644
--- a/src/x64/debug-x64.cc
+++ b/src/x64/debug-x64.cc
@@ -123,14 +123,8 @@ static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
       if ((object_regs & (1 << r)) != 0) {
         __ push(reg);
       }
-      // Store the 64-bit value as two smis.
       if ((non_object_regs & (1 << r)) != 0) {
-        __ movq(kScratchRegister, reg);
-        __ Integer32ToSmi(reg, reg);
-        __ push(reg);
-        __ sar(kScratchRegister, Immediate(32));
-        __ Integer32ToSmi(kScratchRegister, kScratchRegister);
-        __ push(kScratchRegister);
+        __ PushInt64AsTwoSmis(reg);
       }
     }
 
@@ -155,12 +149,7 @@ static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
       }
       // Reconstruct the 64-bit value from two smis.
       if ((non_object_regs & (1 << r)) != 0) {
-        __ pop(kScratchRegister);
-        __ SmiToInteger32(kScratchRegister, kScratchRegister);
-        __ shl(kScratchRegister, Immediate(32));
-        __ pop(reg);
-        __ SmiToInteger32(reg, reg);
-        __ or_(reg, kScratchRegister);
+        __ PopInt64AsTwoSmis(reg);
       }
     }