[CSKY 2/n] Add basic tablegen infra for CSKY

This introduce basic tablegen infra such as CSKY{InstrFormats,InstrInfo,RegisterInfo,}.td.
For now, only add instruction definitions for basic CSKY ISA operations, and the instruction format and register info are almost complete.

Our initial target is a working MC layer rather than codegen, so appropriate SelectionDAG patterns will come later.

Differential Revision: https://reviews.llvm.org/D89180

llvm/lib/Target/CSKY/CMakeLists.txt

@@ -1,5 +1,12 @@
 add_llvm_component_group(CSKY)
 
+set(LLVM_TARGET_DEFINITIONS CSKY.td)
+
+tablegen(LLVM CSKYGenRegisterInfo.inc -gen-register-info)
+tablegen(LLVM CSKYGenInstrInfo.inc -gen-instr-info)
+
+add_public_tablegen_target(CSKYCommonTableGen)
+
 add_llvm_target(CSKYCodeGen
   CSKYTargetMachine.cpp
 

llvm/lib/Target/CSKY/CSKY.td

@@ -0,0 +1,32 @@
+//===-- CSKY.td - Describe the CSKY Target Machine ---------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+include "llvm/Target/Target.td"
+
+//===----------------------------------------------------------------------===//
+// Registers, calling conventions, instruction descriptions.
+//===----------------------------------------------------------------------===//
+
+include "CSKYRegisterInfo.td"
+include "CSKYInstrInfo.td"
+
+//===----------------------------------------------------------------------===//
+// CSKY processors supported.
+//===----------------------------------------------------------------------===//
+
+def : ProcessorModel<"generic-csky", NoSchedModel, []>;
+
+//===----------------------------------------------------------------------===//
+// Define the CSKY target.
+//===----------------------------------------------------------------------===//
+
+def CSKYInstrInfo : InstrInfo;
+
+def CSKY : Target {
+  let InstructionSet = CSKYInstrInfo;
+}