[PATCH] D30415: Fix -mno-altivec cannot overwrite -maltivec option

[Hal Finkel via cfe-commits]

On 03/21/2017 12:19 PM, Ulrich Weigand via Phabricator wrote:
> uweigand added a comment.
>
> In https://reviews.llvm.org/D30415#705889, @echristo wrote:
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>> In https://reviews.llvm.org/D30415#705196, @uweigand wrote:
>>
>>> Well, mainline GCC doesn't have -faltivec at all and never had, I think this was only an Apple GCC extension ...  Not sure what exactly the semantics of that was.
>>
>> Sure it does and has for years. Check out rs6000/darwin.h :)
>>
>> FWIW: It turns on maltivec and adds a -include of altivec.h
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> Huh, I wasn't aware of that feature on Darwin, thanks for pointing it out ...
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>> Nearly all of the code in lib/Driver/ToolChains/Clang.cpp and lib/Driver/ToolChains/Arch/PPC.cpp that deal with altivec. Simplifying the interface by getting rid of needing to check multiple options.
> But why would that code no longer be necessary for -maltivec?  Well, I guess I'll wait for your patch ...
>
> If we indeed get rid of -faltivec, I'm wondering whether it would also make sense to get rid of -fzvector.  This is just an alias for -mzvector, and it isn't supported by GCC either.  I added it only because Richard Smith specifically asked for it when I contributed the feature here:
> https://reviews.llvm.org/D11001

Perhaps what consistency giveth, consistency shall taketh away.

  -Hal

>
>> This should be a -f flag, not a -m flag. (I think we only support -maltivec for GCC compatibility.)
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> https://reviews.llvm.org/D30415
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-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory