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

src/compiler/x87/code-generator-x87.cc

Index: src/compiler/x87/code-generator-x87.cc
diff --git a/src/compiler/x87/code-generator-x87.cc b/src/compiler/x87/code-generator-x87.cc
index e174e709c7784e44e99da7627126681737d194d5..596b7ab775343b251f55e1014dfce84ddcbe78e0 100644
--- a/src/compiler/x87/code-generator-x87.cc
+++ b/src/compiler/x87/code-generator-x87.cc
@@ -1224,6 +1224,10 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ cmp(esp, Operand::StaticVariable(stack_limit));
       break;
     }
+    case kCheckedLoadWord64:
+    case kCheckedStoreWord64:
+      UNREACHABLE();  // currently unsupported checked int64 load/store.
+      break;
   }
 }  // NOLINT(readability/fn_size)