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

[Rafael Avila de Espindola via llvm-commits]

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