[X86] Use addAliasForDirective to support the .word directive

[asb]

Summary

The X86 asm parser currently has custom parsing logic for .word. Rather than use this custom logic, we can just use addAliasForDirective to enable the reuse of AsmParser::parseDirectiveValue.

[asb]

Ping?

[asb]

Ping?

[RKSimon]

I'm not very familiar with this code but it looks OK and the same approach is used in AARCH64, Sparc and Hexagon.

X86AsmParser::ParseDirectiveWord is approximately the same as AsmParser::parseDirectiveValue although AsmParser has extra checks (is asm in valid section, error checks for parseMany call).

@craig.topper Any comments?

[RKSimon]

LGTM - thanks.

[RKSimon]

@asb What's the plan for this patch?

[RKSimon]

@asb This still hasn't landed - are you waiting on anything?

[asb]

Thanks for the review and sorry for the delay in committing. Committed in rL336100.

lib/Target/X86/AsmParser/X86AsmParser.cpp

private:
   bool ParseIntelMemoryOperandSize(unsigned &Size);
   std::unique_ptr<X86Operand>
   CreateMemForInlineAsm(unsigned SegReg, const MCExpr *Disp, unsigned BaseReg,
                         unsigned IndexReg, unsigned Scale, SMLoc Start,
                         SMLoc End, unsigned Size, StringRef Identifier,
                         const InlineAsmIdentifierInfo &Info);
 
   bool parseDirectiveEven(SMLoc L);
-  bool ParseDirectiveWord(unsigned Size, SMLoc L);
   bool ParseDirectiveCode(StringRef IDVal, SMLoc L);
 
   /// CodeView FPO data directives.
   bool parseDirectiveFPOProc(SMLoc L);
   bool parseDirectiveFPOSetFrame(SMLoc L);
   bool parseDirectiveFPOPushReg(SMLoc L);
   bool parseDirectiveFPOStackAlloc(SMLoc L);
   bool parseDirectiveFPOEndPrologue(SMLoc L);

 
 public:
 
   X86AsmParser(const MCSubtargetInfo &sti, MCAsmParser &Parser,
                const MCInstrInfo &mii, const MCTargetOptions &Options)
       : MCTargetAsmParser(Options, sti, mii),  InstInfo(nullptr),
         Code16GCC(false) {
 
+    Parser.addAliasForDirective(".word", ".4byte");
+
     // Initialize the set of available features.
     setAvailableFeatures(ComputeAvailableFeatures(getSTI().getFeatureBits()));
     Instrumentation.reset(
         CreateX86AsmInstrumentation(Options, Parser.getContext(), STI));
   }
 
   bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc, SMLoc &EndLoc) override;
 

 
 bool X86AsmParser::OmitRegisterFromClobberLists(unsigned RegNo) {
   return X86MCRegisterClasses[X86::SEGMENT_REGRegClassID].contains(RegNo);
 }
 
 bool X86AsmParser::ParseDirective(AsmToken DirectiveID) {
   MCAsmParser &Parser = getParser();
   StringRef IDVal = DirectiveID.getIdentifier();
-  if (IDVal == ".word")
-    return ParseDirectiveWord(2, DirectiveID.getLoc());
-  else if (IDVal.startswith(".code"))
+  if (IDVal.startswith(".code"))
     return ParseDirectiveCode(IDVal, DirectiveID.getLoc());
   else if (IDVal.startswith(".att_syntax")) {
     getParser().setParsingInlineAsm(false);
     if (getLexer().isNot(AsmToken::EndOfStatement)) {
       if (Parser.getTok().getString() == "prefix")
         Parser.Lex();
       else if (Parser.getTok().getString() == "noprefix")
         return Error(DirectiveID.getLoc(), "'.att_syntax noprefix' is not "
if (!Section) {
     Section = getStreamer().getCurrentSectionOnly();
   }
   if (Section->UseCodeAlign())
     getStreamer().EmitCodeAlignment(2, 0);
   else
     getStreamer().EmitValueToAlignment(2, 0, 1, 0);
   return false;
 }
-/// ParseDirectiveWord
-///  ::= .word [ expression (, expression)* ]
-bool X86AsmParser::ParseDirectiveWord(unsigned Size, SMLoc L) {
-  auto parseOp = [&]() -> bool {
-    const MCExpr *Value;
-    SMLoc ExprLoc = getLexer().getLoc();
-    if (getParser().parseExpression(Value))
-      return true;
-    if (const auto *MCE = dyn_cast<MCConstantExpr>(Value)) {
-      assert(Size <= 8 && "Invalid size");
-      uint64_t IntValue = MCE->getValue();
-      if (!isUIntN(8 * Size, IntValue) && !isIntN(8 * Size, IntValue))
-        return Error(ExprLoc, "literal value out of range for directive");
-      getStreamer().EmitIntValue(IntValue, Size);
-    } else
-      getStreamer().EmitValue(Value, Size, ExprLoc);
-    return false;
-  };
-  parseMany(parseOp);
-  return false;
-}
 
 /// ParseDirectiveCode
 ///  ::= .code16 | .code32 | .code64
 bool X86AsmParser::ParseDirectiveCode(StringRef IDVal, SMLoc L) {
   MCAsmParser &Parser = getParser();
   Code16GCC = false;
   if (IDVal == ".code16") {
     Parser.Lex();