[llvm] r180171 - Align the __LD,__compact_unwind section.

[Rafael Espíndola]

a testcase would also be cool...


On 23 April 2013 23:11, Bill Wendling <isanbard at gmail.com> wrote:
> Author: void
> Date: Tue Apr 23 22:11:14 2013
> New Revision: 180171
>
> URL: http://llvm.org/viewvc/llvm-project?rev=180171&view=rev
> Log:
> Align the __LD,__compact_unwind section.
>
> I know what would be cool! We should align the compact unwind section because
> aligned data access is faster.
> <rdar://problem/13723271>
>
> Modified:
>     llvm/trunk/lib/MC/MCDwarf.cpp
>
> Modified: llvm/trunk/lib/MC/MCDwarf.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCDwarf.cpp?rev=180171&r1=180170&r2=180171&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCDwarf.cpp (original)
> +++ llvm/trunk/lib/MC/MCDwarf.cpp Tue Apr 23 22:11:14 2013
> @@ -1177,8 +1177,6 @@ void FrameEmitterImpl::EmitCompactUnwind
>    if (!DwarfEHFrameOnly && Frame.Lsda)
>      Encoding |= 0x40000000;
>
> -  Streamer.SwitchSection(MOFI->getCompactUnwindSection());
> -
>    // Range Start
>    unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
>    unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
> @@ -1421,7 +1419,6 @@ MCSymbol *FrameEmitterImpl::EmitFDE(MCSt
>    }
>
>    // Call Frame Instructions
> -
>    EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
>
>    // Padding
> @@ -1482,11 +1479,23 @@ void MCDwarfFrameEmitter::Emit(MCStreame
>    ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
>
>    // Emit the compact unwind info if available.
> -  if (IsEH && MOFI->getCompactUnwindSection())
> -    for (unsigned i = 0, n = Streamer.getNumFrameInfos(); i < n; ++i) {
> -      const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i);
> -      Emitter.EmitCompactUnwind(Streamer, Frame);
> +  if (IsEH && MOFI->getCompactUnwindSection()) {
> +    unsigned NumFrameInfos = Streamer.getNumFrameInfos();
> +    bool SectionEmitted = false;
> +
> +    if (NumFrameInfos) {
> +      for (unsigned i = 0; i < NumFrameInfos; ++i) {
> +        const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i);
> +        if (Frame.CompactUnwindEncoding == 0) continue;
> +        if (!SectionEmitted) {
> +          Streamer.SwitchSection(MOFI->getCompactUnwindSection());
> +          Streamer.EmitValueToAlignment(Context.getAsmInfo().getPointerSize());
> +          SectionEmitted = true;
> +        }
> +        Emitter.EmitCompactUnwind(Streamer, Frame);
> +      }
>      }
> +  }
>
>    const MCSection &Section = IsEH ? *MOFI->getEHFrameSection() :
>                                      *MOFI->getDwarfFrameSection();
>
>
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