public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug middle-end/101251] New: Optimize i % (b ? C0 : C1) into i & (b ? C0-1 : C1-1) for power of 2 C0 and C1
@ 2021-06-29 8:41 antoshkka at gmail dot com
2021-07-01 20:43 ` [Bug middle-end/101251] " pinskia at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: antoshkka at gmail dot com @ 2021-06-29 8:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101251
Bug ID: 101251
Summary: Optimize i % (b ? C0 : C1) into i & (b ? C0-1 : C1-1)
for power of 2 C0 and C1
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: antoshkka at gmail dot com
Target Milestone: ---
Consider the following code
bool test_optim01(bool b, short i) {
return i % (b ? 4 : 16)==0;
}
It could be optimized into
bool test_optim0(bool b, short i) {
return (i & (b ? 15 : 3))==0;
}
Godbolt playground: https://godbolt.org/z/j15br4Kd4
P.S.: Inspired by the manual optimizations in libstdc++
https://github.com/gcc-mirror/gcc/commit/b92d12d3fe3f1aa56d190d960e40c62869a6cfbb
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug middle-end/101251] Optimize i % (b ? C0 : C1) into i & (b ? C0-1 : C1-1) for power of 2 C0 and C1
2021-06-29 8:41 [Bug middle-end/101251] New: Optimize i % (b ? C0 : C1) into i & (b ? C0-1 : C1-1) for power of 2 C0 and C1 antoshkka at gmail dot com
@ 2021-07-01 20:43 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-07-01 20:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101251
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 101179.
*** This bug has been marked as a duplicate of bug 101179 ***
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-07-01 20:43 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-29 8:41 [Bug middle-end/101251] New: Optimize i % (b ? C0 : C1) into i & (b ? C0-1 : C1-1) for power of 2 C0 and C1 antoshkka at gmail dot com
2021-07-01 20:43 ` [Bug middle-end/101251] " pinskia at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).