[clang] [CIR] Integral types; simple global variables (PR #118743)

[Erich Keane via cfe-commits]

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+//===- CIRTypes.td - CIR dialect types ---------------------*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the CIR dialect types.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_CIR_DIALECT_CIR_TYPES
+#define MLIR_CIR_DIALECT_CIR_TYPES
+
+include "clang/CIR/Dialect/IR/CIRDialect.td"
+include "mlir/Interfaces/DataLayoutInterfaces.td"
+include "mlir/IR/AttrTypeBase.td"
+
+//===----------------------------------------------------------------------===//
+// CIR Types
+//===----------------------------------------------------------------------===//
+
+class CIR_Type<string name, string typeMnemonic, list<Trait> traits = [],
+               string baseCppClass = "::mlir::Type">
+    : TypeDef<CIR_Dialect, name, traits, baseCppClass> {
+  let mnemonic = typeMnemonic;
+}
+
+//===----------------------------------------------------------------------===//
+// IntType
+//===----------------------------------------------------------------------===//
+
+def CIR_IntType : CIR_Type<"Int", "int",
+    [DeclareTypeInterfaceMethods<DataLayoutTypeInterface>]> {
+  let summary = "Integer type with arbitrary precision up to a fixed limit";
+  let description = [{
+    CIR type that represents integer types with arbitrary precision.
+
+    Those integer types that are directly available in C/C++ standard are called
+    primitive integer types. Said types are: `signed char`, `short`, `int`,
+    `long`, `long long`, and their unsigned variations.
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erichkeane wrote:

How is `_BitInt` represented? 

https://github.com/llvm/llvm-project/pull/118743