[llvm] r180641 - Cleanup and document MachineLocation.

[Rafael Espíndola]

Thanks. I think the medium term solution for this is to enable EH in
MCJIT, remove lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp and then
just use MCCFIInstruction everywhere.

I have an old patch for enabling EH in MCJIT that I will try to get
back to now that it should work on MachO too.

On 26 April 2013 17:57, Adrian Prantl <aprantl at apple.com> wrote:
> Author: adrian
> Date: Fri Apr 26 16:57:17 2013
> New Revision: 180641
>
> URL: http://llvm.org/viewvc/llvm-project?rev=180641&view=rev
> Log:
> Cleanup and document MachineLocation.
> Clarify documentation and API to make the difference between register and
> register-indirect addressed locations more explicit. Put in a comment
> to point out that with the current implementation we cannot specify
> a register-indirect location with offset 0 (a breg 0 in DWARF).
> No functionality change intended.
>
> rdar://problem/13658587
>
> Modified:
>     llvm/trunk/include/llvm/MC/MachineLocation.h
>     llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>
> Modified: llvm/trunk/include/llvm/MC/MachineLocation.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MachineLocation.h?rev=180641&r1=180640&r2=180641&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MachineLocation.h (original)
> +++ llvm/trunk/include/llvm/MC/MachineLocation.h Fri Apr 26 16:57:17 2013
> @@ -9,7 +9,7 @@
>  // The MachineLocation class is used to represent a simple location in a machine
>  // frame.  Locations will be one of two forms; a register or an address formed
>  // from a base address plus an offset.  Register indirection can be specified by
> -// using an offset of zero.
> +// explicitly passing an offset to the constructor.
>  //
>  // The MachineMove class is used to represent abstract move operations in the
>  // prolog/epilog of a compiled function.  A collection of these objects can be
> @@ -37,8 +37,10 @@ public:
>    };
>    MachineLocation()
>      : IsRegister(false), Register(0), Offset(0) {}
> +  /// Create a direct register location.
>    explicit MachineLocation(unsigned R)
>      : IsRegister(true), Register(R), Offset(0) {}
> +  /// Create a register-indirect location with an offset.
>    MachineLocation(unsigned R, int O)
>      : IsRegister(false), Register(R), Offset(O) {}
>
> @@ -48,17 +50,20 @@ public:
>    }
>
>    // Accessors
> +  bool isIndirect()      const { return !IsRegister; }
>    bool isReg()           const { return IsRegister; }
>    unsigned getReg()      const { return Register; }
>    int getOffset()        const { return Offset; }
>    void setIsRegister(bool Is)  { IsRegister = Is; }
>    void setRegister(unsigned R) { Register = R; }
>    void setOffset(int O)        { Offset = O; }
> +  /// Make this location a direct register location.
>    void set(unsigned R) {
>      IsRegister = true;
>      Register = R;
>      Offset = 0;
>    }
> +  /// Make this location a register-indirect+offset location.
>    void set(unsigned R, int O) {
>      IsRegister = false;
>      Register = R;
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=180641&r1=180640&r2=180641&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Fri Apr 26 16:57:17 2013
> @@ -813,7 +813,7 @@ void AsmPrinter::EmitDwarfRegOp(const Ma
>    // caller might be in the middle of an dwarf expression. We should
>    // probably assert that Reg >= 0 once debug info generation is more mature.
>
> -  if (int Offset =  MLoc.getOffset()) {
> +  if (MLoc.isIndirect()) {
>      if (Reg < 32) {
>        OutStreamer.AddComment(
>          dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
> @@ -824,7 +824,7 @@ void AsmPrinter::EmitDwarfRegOp(const Ma
>        OutStreamer.AddComment(Twine(Reg));
>        EmitULEB128(Reg);
>      }
> -    EmitSLEB128(Offset);
> +    EmitSLEB128(MLoc.getOffset());
>    } else {
>      if (Reg < 32) {
>        OutStreamer.AddComment(
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=180641&r1=180640&r2=180641&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Fri Apr 26 16:57:17 2013
> @@ -1131,7 +1131,13 @@ static DotDebugLocEntry getDebugLocEntry
>    }
>    if (MI->getOperand(0).isReg() && MI->getOperand(1).isImm()) {
>      MachineLocation MLoc;
> -    MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
> +    // TODO: Currently an offset of 0 in a DBG_VALUE means
> +    // we need to generate a direct register value.
> +    // There is no way to specify an indirect value with offset 0.
> +    if (MI->getOperand(1).getImm() == 0)
> +      MLoc.set(MI->getOperand(0).getReg());
> +    else
> +      MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
>      return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
>    }
>    if (MI->getOperand(0).isImm())
>
>
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