[Bug tree-optimization/83253] -ftree-slsr causes performance regression
wschmidt at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Dec 13 22:31:00 GMT 2017
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83253
--- Comment #9 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
I was able to build an i386 cross, and this wasn't sufficient to solve the
problem. I see:
Processing dependency tree rooted at 1.
Inserting initializer: slsr_10 = scale_7(D) * 3;
Increment vector:
0 increment: 1
count: 0
cost: 1000
initializer:
1 increment: 3
count: 1
cost: -4
initializer: slsr_10
Replacing: _4 = ptr_6(D) + _3;
With: _4 = _1 + slsr_10;
The cost model thinks the replacement is still profitable. I'll look into what
i386 is reporting for the costs tomorrow.
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