[LLVMdev] some llvm/clang missed optimizations

[Eli Friedman]

On Tue, Jan 26, 2010 at 7:42 PM, John Regehr <regehr at cs.utah.edu> wrote:
>> Umm, can you find one that isn't a popcount implementation?
>
> Ok.
>
> MMX psadbw instruction:
>
> http://embed.cs.utah.edu/embarrassing/jan_10/harvest/source/CE/CE3DA132.shtml
>
> Position of first set bit:
>
> http://embed.cs.utah.edu/embarrassing/jan_10/harvest/source/1F/1F4003C7.shtml
>
> Log2 floor:
>
> http://embed.cs.utah.edu/embarrassing/jan_10/harvest/source/83/837A80E9.shtml
>
> Pixel format conversion:
>
> http://embed.cs.utah.edu/embarrassing/jan_10/harvest/source/EC/EC3353C5.shtml

Okay... it definitely appears that the issue is being introduced by
your test harness duplicating expressions.

-Eli