[lld] r374332 - Make nullptr check more robust

[Roman Lebedev via llvm-commits]

Thank you!

On Thu, Oct 10, 2019 at 3:38 PM Rui Ueyama via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
> Author: ruiu
> Date: Thu Oct 10 05:41:08 2019
> New Revision: 374332
>
> URL: http://llvm.org/viewvc/llvm-project?rev=374332&view=rev
> Log:
> Make nullptr check more robust
>
> The only condition that isecLoc becomes null is
>
>   Out::bufferStart == nullptr,
>   isec->getParent()->offset == 0, and
>   isec->outSecOff == 0.
>
> We can check the first condition only once.
>
> Modified:
>     lld/trunk/ELF/Target.cpp
>
> Modified: lld/trunk/ELF/Target.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=374332&r1=374331&r2=374332&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Target.cpp (original)
> +++ lld/trunk/ELF/Target.cpp Thu Oct 10 05:41:08 2019
> @@ -91,18 +91,16 @@ TargetInfo *getTarget() {
>  }
>
>  template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *loc) {
> +  if (!Out::bufferStart)
> +    return {};
> +
>    for (InputSectionBase *d : inputSections) {
>      auto *isec = cast<InputSection>(d);
>      if (!isec->getParent())
>        continue;
>
>      uint8_t *isecLoc = Out::bufferStart + isec->getParent()->offset + isec->outSecOff;
> -    if (isecLoc > loc)
> -      continue;
> -    // isecLoc might be nullptr here, with isec->getSize() being non-zero.
> -    // Adding these two together is not defined in C++.
> -    if (loc < reinterpret_cast<uint8_t *>(
> -                  reinterpret_cast<std::uintptr_t>(isecLoc) + isec->getSize()))
> +    if (isecLoc <= loc && loc < isecLoc + isec->getSize())
>        return {isec, isec->template getLocation<ELFT>(loc - isecLoc) + ": "};
>    }
>    return {};
>
>
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