[llvm] r295765 - Don't modify archive members unless really needed.

[Rui Ueyama via llvm-commits]

Huh, that's right. Maybe it was an MSVC thing that it cannot defer that the
end of function is unreachable.

On Wed, Feb 22, 2017 at 6:17 AM, Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> Rui Ueyama <ruiu at google.com> writes:
>
> > On Tue, Feb 21, 2017 at 12:40 PM, Rafael Espindola via llvm-commits <
> > llvm-commits at lists.llvm.org> wrote:
> >
> >> Author: rafael
> >> Date: Tue Feb 21 14:40:54 2017
> >> New Revision: 295765
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=295765&view=rev
> >> Log:
> >> Don't modify archive members unless really needed.
> >>
> >> For whatever reason ld64 requires that member headers (not the member
> >> themselves) should be aligned. The only way to do that is to edit the
> >> previous member so that it ends at an aligned boundary.
> >>
> >> Since modifying data put in an archive is an undesirable property,
> >> llvm-ar should only do it when it is absolutely necessary.
> >>
> >> Added:
> >>     llvm/trunk/test/Object/archive-pad.test
> >> Modified:
> >>     llvm/trunk/include/llvm/Object/Archive.h
> >>     llvm/trunk/lib/Object/ArchiveWriter.cpp
> >>     llvm/trunk/test/Object/archive-extract.test
> >>     llvm/trunk/test/Object/archive-format.test
> >>     llvm/trunk/tools/llvm-ar/llvm-ar.cpp
> >>
> >> Modified: llvm/trunk/include/llvm/Object/Archive.h
> >> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> >> llvm/Object/Archive.h?rev=295765&r1=295764&r2=295765&view=diff
> >> ============================================================
> >> ==================
> >> --- llvm/trunk/include/llvm/Object/Archive.h (original)
> >> +++ llvm/trunk/include/llvm/Object/Archive.h Tue Feb 21 14:40:54 2017
> >> @@ -212,6 +212,7 @@ public:
> >>      K_GNU,
> >>      K_MIPS64,
> >>      K_BSD,
> >> +    K_DARWIN,
> >>      K_DARWIN64,
> >>      K_COFF
> >>    };
> >>
> >> Modified: llvm/trunk/lib/Object/ArchiveWriter.cpp
> >> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/
> >> ArchiveWriter.cpp?rev=295765&r1=295764&r2=295765&view=diff
> >> ============================================================
> >> ==================
> >> --- llvm/trunk/lib/Object/ArchiveWriter.cpp (original)
> >> +++ llvm/trunk/lib/Object/ArchiveWriter.cpp Tue Feb 21 14:40:54 2017
> >> @@ -122,12 +122,26 @@ static void printWithSpacePadding(raw_fd
> >>    }
> >>  }
> >>
> >> +static bool isBSDLike(object::Archive::Kind Kind) {
> >> +  switch (Kind) {
> >> +  case object::Archive::K_GNU:
> >> +    return false;
> >> +  case object::Archive::K_BSD:
> >> +  case object::Archive::K_DARWIN:
> >> +    return true;
> >> +  case object::Archive::K_MIPS64:
> >> +  case object::Archive::K_DARWIN64:
> >> +  case object::Archive::K_COFF:
> >> +    llvm_unreachable("not supported for writting");
> >> +  }
> >> +}
> >>
> >
> > This `switch` doesn't cover all Kind enums, which is bad because this
> > function should return a value.
>
> I am pretty sure it covers all the enum values. Which one do you think
> is missing?
>
> Cheers,
> Rafael
>
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