[AIX] Add dummy XCOFF MCAsmParserExtension

[jsji]

Summary

Implement XCOFFMCAsmParser so that we can use MC to parse inline asm.

The directives and storage mapping classes will be added later
iteratively.

[xgupta]

LGTM, Thanks!

Tested the patch locally on my system and most code is common with ELF/COFF AsmParser implementation. Will look for further AIX/COFF specific implementation.

llvm/lib/MC/MCParser/AsmParser.cpp

 
 } // end anonymous namespace
 
 namespace llvm {
 
 extern MCAsmParserExtension *createDarwinAsmParser();
 extern MCAsmParserExtension *createELFAsmParser();
 extern MCAsmParserExtension *createCOFFAsmParser();
+extern MCAsmParserExtension *createXCOFFAsmParser();
 extern MCAsmParserExtension *createWasmAsmParser();
 
 } // end namespace llvm
 
 enum { DEFAULT_ADDRSPACE = 0 };
 
 AsmParser::AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
                      const MCAsmInfo &MAI, unsigned CB = 0)
case MCContext::IsMachO:
     break;
   case MCContext::IsELF:
     PlatformParser.reset(createELFAsmParser());
     break;
   case MCContext::IsWasm:
     PlatformParser.reset(createWasmAsmParser());
     break;
   case MCContext::IsXCOFF:
-    report_fatal_error(
-        "Need to implement createXCOFFAsmParser for XCOFF format.");
+    PlatformParser.reset(createXCOFFAsmParser());
     break;
   }
 
   PlatformParser->Initialize(*this);
   initializeDirectiveKindMap();
   initializeCVDefRangeTypeMap();
 
   NumOfMacroInstantiations = 0;

llvm/lib/MC/MCParser/CMakeLists.txt

 add_llvm_component_library(LLVMMCParser
   AsmLexer.cpp
   AsmParser.cpp
   COFFAsmParser.cpp
   COFFMasmParser.cpp
   DarwinAsmParser.cpp
   ELFAsmParser.cpp
   MCAsmLexer.cpp
   MCAsmParser.cpp
   MCAsmParserExtension.cpp
   MCTargetAsmParser.cpp
   MasmParser.cpp
   WasmAsmParser.cpp
+  XCOFFAsmParser.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/MC/MCParser
 
   LINK_COMPONENTS
   MC
   Support
   )

llvm/lib/MC/MCParser/XCOFFAsmParser.cpp

+//===- XCOFFAsmParser.cpp - XCOFF Assembly Parser
+//-----------------------------===//
+//
+// 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/BinaryFormat/XCOFF.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCParser/MCAsmLexer.h"
+#include "llvm/MC/MCParser/MCAsmParser.h"
+#include "llvm/MC/MCParser/MCAsmParserExtension.h"
+#include "llvm/MC/MCSectionXCOFF.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCSymbolXCOFF.h"
+#include "llvm/Support/MachineValueType.h"
+
+using namespace llvm;
+
+namespace {
+
+class XCOFFAsmParser : public MCAsmParserExtension {
+  MCAsmParser *Parser = nullptr;
+  MCAsmLexer *Lexer = nullptr;
+
+  template <bool (XCOFFAsmParser::*HandlerMethod)(StringRef, SMLoc)>
+  void addDirectiveHandler(StringRef Directive) {
+    MCAsmParser::ExtensionDirectiveHandler Handler =
+        std::make_pair(this, HandleDirective<XCOFFAsmParser, HandlerMethod>);
+
+    getParser().addDirectiveHandler(Directive, Handler);
+  }
+
+public:
+  XCOFFAsmParser() {}
+
+  void Initialize(MCAsmParser &P) override {
+    Parser = &P;
+    Lexer = &Parser->getLexer();
+    // Call the base implementation.
+    MCAsmParserExtension::Initialize(*Parser);
+
+    addDirectiveHandler<&XCOFFAsmParser::ParseDirectiveCSect>(".csect");
+  }
+  bool ParseDirectiveCSect(StringRef, SMLoc);
+};
+
+} // end anonymous namespace
+
+namespace llvm {
+
+MCAsmParserExtension *createXCOFFAsmParser() { return new XCOFFAsmParser; }
+
+} // end namespace llvm
+
+// .csect QualName [, Number ]
+bool XCOFFAsmParser::ParseDirectiveCSect(StringRef, SMLoc) {
+  report_fatal_error("XCOFFAsmParser directive not yet supported!");
+  return false;
+}

llvm/test/MC/XCOFF/inlineasm.s

+// RUN: llvm-mc -filetype=asm -triple powerpc-ibm-aix-xcoff %s | FileCheck %s
+
+// CHECK-label:       .csect .text[PR],2
+// CHECK:L..tmp0:
+// CHECK-NEXT:        lwarx 3, 0, 4
+// CHECK-NEXT:        cmpw    5, 3
+// CHECK-NEXT:        bne-    0, L..tmp1
+// CHECK-NEXT:        stwcx. 6, 0, 4
+// CHECK-NEXT:        bne-    0, L..tmp0
+// CHECK-NEXT:L..tmp1:
+
+
+        #APP
+1:
+        lwarx 3, 0, 4
+        cmpw    5, 3
+        bne-    2f
+        stwcx. 6, 0, 4
+        bne-    1b
+2:
+
+        #NO_APP
+

llvm/test/MC/XCOFF/lit.local.cfg

+if not 'PowerPC' in config.root.targets:
+    config.unsupported = True