[Bug target/103316] PowerPC: Gimple folding of int128 comparisons produces suboptimal code
segher at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Fri Nov 19 14:21:31 GMT 2021
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103316
--- Comment #8 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Btw:
> mfvsrd 9,34
> mfvsrld 8,34
> mfvsrd 11,35
> mfvsrld 10,35
> li 7,1
> cmpd 0,9,11
> bgt 0,.L2
> cmpld 0,9,11
> beq 0,.L5
> .L3:
> li 7,0
The fall-through here makes the code worse.
> .L2:
> subfic 10,7,0
> subfe 11,11,11
And we shouldn't generate this for p10 at all anyway! Something
with setbc would be better.
If there were no branches here RTL could have made the code a bit
more reasonable again, but with branches, no such chance :-(
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