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* [Bug tree-optimization/96714] New: Failure to optimize sqrt*sqrt of same variable with ffast-math
@ 2020-08-19 20:23 gabravier at gmail dot com
2020-08-25 11:14 ` [Bug tree-optimization/96714] " rguenth at gcc dot gnu.org
2020-08-25 12:09 ` gabravier at gmail dot com
0 siblings, 2 replies; 3+ messages in thread
From: gabravier at gmail dot com @ 2020-08-19 20:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96714
Bug ID: 96714
Summary: Failure to optimize sqrt*sqrt of same variable with
ffast-math
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
float f(float x)
{
return __builtin_sqrtf(x) * __builtin_sqrtf(x);
}
This can be optimized to `return x;` (with fast math enabled). This
transformation is done by LLVM, but not by GCC.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/96714] Failure to optimize sqrt*sqrt of same variable with ffast-math
2020-08-19 20:23 [Bug tree-optimization/96714] New: Failure to optimize sqrt*sqrt of same variable with ffast-math gabravier at gmail dot com
@ 2020-08-25 11:14 ` rguenth at gcc dot gnu.org
2020-08-25 12:09 ` gabravier at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-08-25 11:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96714
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |WORKSFORME
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Huh.
(if (flag_unsafe_math_optimizations)
/* Simplify sqrt(x) * sqrt(x) -> x. */
(simplify
(mult (SQRT_ALL@1 @0) @1)
(if (!HONOR_SNANS (type))
@0))
and it works for me, with -ffast-math as you say.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/96714] Failure to optimize sqrt*sqrt of same variable with ffast-math
2020-08-19 20:23 [Bug tree-optimization/96714] New: Failure to optimize sqrt*sqrt of same variable with ffast-math gabravier at gmail dot com
2020-08-25 11:14 ` [Bug tree-optimization/96714] " rguenth at gcc dot gnu.org
@ 2020-08-25 12:09 ` gabravier at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: gabravier at gmail dot com @ 2020-08-25 12:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96714
--- Comment #2 from Gabriel Ravier <gabravier at gmail dot com> ---
Hmm, I can't reproduce it either, either I was simply wrong (on something like
whether I had fast math enabled) or there is some peculiarity on my setup from
6 days ago that I missed.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-08-25 12:09 UTC | newest]
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2020-08-19 20:23 [Bug tree-optimization/96714] New: Failure to optimize sqrt*sqrt of same variable with ffast-math gabravier at gmail dot com
2020-08-25 11:14 ` [Bug tree-optimization/96714] " rguenth at gcc dot gnu.org
2020-08-25 12:09 ` gabravier at gmail dot com
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