Generate index types for long type in MLIR

Author: georgestagg

flang/include/flang/Optimizer/Builder/Runtime/RTBuilder.h

@@ -132,7 +132,7 @@ constexpr TypeBuilderFunc getModel<void **>() {
 template <>
 constexpr TypeBuilderFunc getModel<long>() {
   return [](mlir::MLIRContext *context) -> mlir::Type {
-    return mlir::IntegerType::get(context, 8 * sizeof(long));
+    return mlir::IndexType::get(context);
   };
 }
 template <>
@@ -173,7 +173,7 @@ constexpr TypeBuilderFunc getModel<long long *>() {
 template <>
 constexpr TypeBuilderFunc getModel<unsigned long>() {
   return [](mlir::MLIRContext *context) -> mlir::Type {
-    return mlir::IntegerType::get(context, 8 * sizeof(unsigned long));
+    return mlir::IndexType::get(context);
   };
 }
 template <>