change code

[leikang123]

[NFC][llvm]
add xtensa.h head file code
define xtensa.td file,not define xtensa.h head file code.

llvm/lib/Target/Xtensa/Xtensa.h

 
 #include "MCTargetDesc/XtensaMCTargetDesc.h"
 #include "llvm/Target/TargetMachine.h"
 
 namespace llvm {
   class XtensaTargetMachine;
   class FunctionPass;
 }
-
 #define ENABLE_GPRESTORE 
 #endif

llvm/lib/Target/Xtensa/Xtensa.td

+//===- Xtensa.td - Describe the Xtensa Target Machine ------*- tablegen -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Target-independent interfaces
+//===----------------------------------------------------------------------===//
+
+include "llvm/Target/Target.td"
+
+//===----------------------------------------------------------------------===//
+// xtensa Subtarget Features.
+//===----------------------------------------------------------------------===//
+def FeatureDensity : SubtargetFeature<"density", "HasDensity", "true",
+                    "Enable Density instructions">;
+def HasDensity : Predicate<"Subtarget->hasDensity()">,
+                     AssemblerPredicate<(all_of FeatureDensity)>;
+//===----------------------------------------------------------------------===//
+// Xtensa supported processors.
+//===----------------------------------------------------------------------===//
+class Proc<string Name, list<SubtargetFeature> Features>
+    : Processor<Name, NoItineraries, Features>;
+
+def : Proc<"generic", []>;
+
+//===----------------------------------------------------------------------===//
+// Register File Description
+//===----------------------------------------------------------------------===//
+
+include "XtensaRegisterInfo.td"
+
+//===----------------------------------------------------------------------===//
+// Instruction Descriptions
+//===----------------------------------------------------------------------===//
+
+include "XtensaInstrInfo.td"
+
+def XtensaInstrInfo : InstrInfo;
+
+//===----------------------------------------------------------------------===//
+// Target Declaration
+//===----------------------------------------------------------------------===//
+
+def XtensaAsmParser : AsmParser {
+  let ShouldEmitMatchRegisterAltName = 1;
+}
+
+def XtensaInstPrinter : AsmWriter {
+  string AsmWriterClassName  = "InstPrinter";
+}
+
+def Xtensa : Target {
+  let InstructionSet = XtensaInstrInfo;
+  let AssemblyWriters = [XtensaInstPrinter];
+  let AssemblyParsers = [XtensaAsmParser];
+}
 No newline at end of file