[llvm] r350355 - [X86] Remove terrible DX Register parsing hack in parse operand. NFCI.

[Craig Topper via llvm-commits]

I think there's still a bug that I was trying to fix with that hack, but I
failed because CheckBaseRegAndIndexRegAndScale allows DX through. This
assembles even though it shouldn't

add (%dx), %ax

~Craig


On Thu, Jan 3, 2019 at 1:49 PM Nirav Dave via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: niravd
> Date: Thu Jan  3 13:46:30 2019
> New Revision: 350355
>
> URL: http://llvm.org/viewvc/llvm-project?rev=350355&view=rev
> Log:
> [X86] Remove terrible DX Register parsing hack in parse operand. NFCI.
>
> Fold hack special casing of (%dx) operand parsing into the related
> hack for out*/in* instruction parsing.
>
> Modified:
>     llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp
>     llvm/trunk/lib/Target/X86/AsmParser/X86Operand.h
>
> Modified: llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp?rev=350355&r1=350354&r2=350355&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp (original)
> +++ llvm/trunk/lib/Target/X86/AsmParser/X86AsmParser.cpp Thu Jan  3
> 13:46:30 2019
> @@ -2240,14 +2240,6 @@ std::unique_ptr<X86Operand> X86AsmParser
>    if (parseToken(AsmToken::RParen, "unexpected token in memory operand"))
>      return nullptr;
>
> -  // This is a terrible hack to handle "out[s]?[bwl]? %al, (%dx)" ->
> -  // "outb %al, %dx".  Out doesn't take a memory form, but this is a
> widely
> -  // documented form in various unofficial manuals, so a lot of code uses
> it.
> -  if (BaseReg == X86::DX && IndexReg == 0 && Scale == 1 &&
> -      SegReg == 0 && isa<MCConstantExpr>(Disp) &&
> -      cast<MCConstantExpr>(Disp)->getValue() == 0)
> -    return X86Operand::CreateDXReg(BaseLoc, BaseLoc);
> -
>    StringRef ErrMsg;
>    if (CheckBaseRegAndIndexRegAndScale(BaseReg, IndexReg, Scale,
> is64BitMode(),
>                                        ErrMsg)) {
>
> Modified: llvm/trunk/lib/Target/X86/AsmParser/X86Operand.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/AsmParser/X86Operand.h?rev=350355&r1=350354&r2=350355&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/AsmParser/X86Operand.h (original)
> +++ llvm/trunk/lib/Target/X86/AsmParser/X86Operand.h Thu Jan  3 13:46:30
> 2019
> @@ -30,7 +30,7 @@ namespace llvm {
>  /// X86Operand - Instances of this class represent a parsed X86 machine
>  /// instruction.
>  struct X86Operand final : public MCParsedAsmOperand {
> -  enum KindTy { Token, Register, Immediate, Memory, Prefix, DXRegister }
> Kind;
> +  enum KindTy { Token, Register, Immediate, Memory, Prefix } Kind;
>
>    SMLoc StartLoc, EndLoc;
>    SMLoc OffsetOfLoc;
> @@ -118,9 +118,6 @@ struct X86Operand final : public MCParse
>      case Register:
>        OS << "Reg:" << X86IntelInstPrinter::getRegisterName(Reg.RegNo);
>        break;
> -    case DXRegister:
> -      OS << "DXReg";
> -      break;
>      case Immediate:
>        PrintImmValue(Imm.Val, "Imm:");
>        break;
> @@ -444,7 +441,10 @@ struct X86Operand final : public MCParse
>
>    bool isPrefix() const { return Kind == Prefix; }
>    bool isReg() const override { return Kind == Register; }
> -  bool isDXReg() const { return Kind == DXRegister; }
> +  bool isDXReg() const {
> +    return Kind == Memory && getMemBaseReg() == X86::DX &&
> !getMemIndexReg() &&
> +           getMemScale() == 1;
> +  }
>
>    bool isGR32orGR64() const {
>      return Kind == Register &&
> @@ -544,11 +544,6 @@ struct X86Operand final : public MCParse
>    }
>
>    static std::unique_ptr<X86Operand>
> -  CreateDXReg(SMLoc StartLoc, SMLoc EndLoc) {
> -    return llvm::make_unique<X86Operand>(DXRegister, StartLoc, EndLoc);
> -  }
> -
> -  static std::unique_ptr<X86Operand>
>    CreatePrefix(unsigned Prefixes, SMLoc StartLoc, SMLoc EndLoc) {
>      auto Res = llvm::make_unique<X86Operand>(Prefix, StartLoc, EndLoc);
>      Res->Pref.Prefixes = Prefixes;
>
>
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