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

[Robinson, Paul]

Huh.  Okay, *on Windows* they're alternate names.  Windows is still a supported environment?  So the remark about not being there on Linux/Mac is really pretty irrelevant.

That said…  we'll see if we can get LZCNT out of the more complicated expression often enough to keep our users happy.
--paulr

From: Craig Topper [mailto:craig.topper at gmail.com]
Sent: Monday, October 27, 2014 7:03 PM
To: Robinson, Paul
Cc: Chandler Carruth; cfe-commits at cs.uiuc.edu
Subject: Re: [PATCH][X86] __builtin_ctz/clz sometimed defined for zero input

Intrin.h does an #include_next and nothing else if MSC_VER is not defined.

On Mon, Oct 27, 2014 at 6:16 PM, Robinson, Paul <Paul_Robinson at playstation.sony.com<mailto: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

From: Chandler Carruth [mailto:chandlerc at google.com<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<mailto: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<mailto: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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--
~Craig
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