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* [Bug tree-optimization/50756] New: request to better handle non-constant distance vectors to avoid unnecessary alias check
@ 2011-10-17 9:54 vincenzo.innocente at cern dot ch
2021-08-07 22:19 ` [Bug tree-optimization/50756] " pinskia at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: vincenzo.innocente at cern dot ch @ 2011-10-17 9:54 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50756
Bug #: 50756
Summary: request to better handle non-constant distance vectors
to avoid unnecessary alias check
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: vincenzo.innocente@cern.ch
this is a follow up to PR50698
this snippet
void loop(float * x, int n) {
for (int i=0;i!=n; ++i)
x[i]=x[i+n]+x[i+2*n];
}
generates aliasing checks even if memory regions are clearly disjoint
(see analysis in comments 6 and 7 of PR50698)
I'm now experimenting with "structure of arrays" in place of "array of
structures" to make better use of vectorization (and cpu-caches). Reducing
unecessary aliasing will further improve performance (and reduce code size).It
will also avoid the need to set --param vect-max-version-for-alias-checks=100
or so.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug tree-optimization/50756] request to better handle non-constant distance vectors to avoid unnecessary alias check
2011-10-17 9:54 [Bug tree-optimization/50756] New: request to better handle non-constant distance vectors to avoid unnecessary alias check vincenzo.innocente at cern dot ch
@ 2021-08-07 22:19 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-07 22:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50756
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-08-07
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, still happens.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-10-17 9:54 [Bug tree-optimization/50756] New: request to better handle non-constant distance vectors to avoid unnecessary alias check vincenzo.innocente at cern dot ch
2021-08-07 22:19 ` [Bug tree-optimization/50756] " pinskia at gcc dot gnu.org
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