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

src/compiler/ppc/instruction-selector-ppc.cc

Index: src/compiler/ppc/instruction-selector-ppc.cc
diff --git a/src/compiler/ppc/instruction-selector-ppc.cc b/src/compiler/ppc/instruction-selector-ppc.cc
index 197dcc13ea688e8cef0268bab731a6f395a96b89..d8543a377dacadaadc60fdd444401f4b5a90bcfc 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -282,6 +282,9 @@ void InstructionSelector::VisitCheckedLoad(Node* node) {
     case kRepWord32:
       opcode = kCheckedLoadWord32;
       break;
+    case kRepWord64:
+      opcode = kCheckedLoadWord64;
+      break;
     case kRepFloat32:
       opcode = kCheckedLoadFloat32;
       break;
@@ -317,6 +320,9 @@ void InstructionSelector::VisitCheckedStore(Node* node) {
     case kRepWord32:
       opcode = kCheckedStoreWord32;
       break;
+    case kRepWord64:
+      opcode = kCheckedStoreWord64;
+      break;
     case kRepFloat32:
       opcode = kCheckedStoreFloat32;
       break;