[PATCH][X86] __builtin_ctz/clz sometimed defined for zero input

[Richard Smith]

On Mon, Oct 27, 2014 at 7:09 PM, Sean Silva <chisophugis at gmail.com> wrote:

>
>
> On Mon, Oct 27, 2014 at 6:16 PM, Robinson, Paul <
> Paul_Robinson at playstation.sony.com> wrote:
>
>>  I don't know about Mac, but on my Ubuntu, Intrin.h shows up in the
>> expected place:
>>
>>
>>
>> ~/projects/upstream/writeable/obj$ find . -name Intrin.h
>>
>> ./Debug+Asserts/lib/clang/3.6.0/include/Intrin.h
>>
>> ./Debug+Asserts/lib/clang/3.5.0/include/Intrin.h
>>
>> ./Debug+Asserts/lib/clang/3.4/include/Intrin.h
>>
>> ./Debug+Asserts/lib/clang/3.5/include/Intrin.h
>>
>
> I presume that isn't where existing software for those platforms looks for
> them.
>

It is, but they do nothing but #include_next the next Intrin.h if you're
not targeting win32, so they act as if they don't exist.


> -- Sean Silva
>
>
>>
>>
>> *From:* Chandler Carruth [mailto:chandlerc at google.com]
>> *Sent:* Monday, October 27, 2014 5:17 PM
>> *To:* Robinson, Paul
>> *Cc:* Sean Silva; cfe-commits at cs.uiuc.edu
>> *Subject:* Re: [PATCH][X86] __builtin_ctz/clz sometimed defined for zero
>> input
>>
>>
>>
>>
>>
>> On Mon, Oct 27, 2014 at 5:02 PM, Robinson, Paul <
>> Paul_Robinson at playstation.sony.com> wrote:
>>
>> That makes lzcntintrin.h completely pointless.  They'd just be alternate
>> names for the functions in Intrin.h.
>>
>>
>> If those names need to be supported for compatibility and portability
>> then it still seems to have a point.
>>
>>
>>
>> Note that Intrin.h doesn't exist on Linux or Mac.
>>
>
>
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