[turbofan] support for Int64 in CheckedLoad/CheckedStore on 64-bit platforms.

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 55f808883eca8b3e8641eb6be77d19c471ea5749..56260804806fd904a506bf5c776b2ee7005cf200 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -1271,6 +1271,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kCheckedLoadWord32:
       ASSEMBLE_CHECKED_LOAD_INTEGER(movl);
       break;
+    case kCheckedLoadWord64:
+      ASSEMBLE_CHECKED_LOAD_INTEGER(movq);
+      break;
     case kCheckedLoadFloat32:
       ASSEMBLE_CHECKED_LOAD_FLOAT(movss);
       break;
@@ -1286,6 +1289,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kCheckedStoreWord32:
       ASSEMBLE_CHECKED_STORE_INTEGER(movl);
       break;
+    case kCheckedStoreWord64:
+      ASSEMBLE_CHECKED_STORE_INTEGER(movq);
+      break;
     case kCheckedStoreFloat32:
       ASSEMBLE_CHECKED_STORE_FLOAT(movss);
       break;