[LLVMdev] LLVM 2.8 and MMX

Dale Johannesen
Tue, 21 Sep 2010 18:12:07 -0000

On Sep 21, 2010, at 10:23 AMPDT, Nicolas Capens wrote:

> Hi all,
>
> Sorry for the late reply. I got sidetracked by other fun projects. ;-)
>
> I found that the performance regression is caused by revisions 112804,
> 112805 and 112806. Those changes were made 2 days prior to the 2.8
> branching, so it may have not been the intention to include them there?
> Either way they make my vector-intensive code two times slower so it would
> be much appreciated to revert these changes for the 2.8 release.
>
> Thanks,
>
> Nicolas

Interesting.  These are all Bruno's patches, and I'm pretty sure they
weren't intended to affect MMX.   I doubt reverting them is right since the
effect on SSE is presumably positive.  Unfortunately Bruno is not here any more.

> -----Original Message-----
> From: Chris Lattner [mailto:clattner at apple.com]
>>
>> I think some changes related to MMX landed before 2.8 branched which
>> shouldn't have... please file a bug.

So please file a bug, with example.