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* [Bug tree-optimization/109044] New: Missed fold for (n - 1) / 2 when n is odd
@ 2023-03-06 18:18 llvm at rifkin dot dev
2023-03-06 18:20 ` [Bug tree-optimization/109044] " pinskia at gcc dot gnu.org
2023-03-07 9:10 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: llvm at rifkin dot dev @ 2023-03-06 18:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109044
Bug ID: 109044
Summary: Missed fold for (n - 1) / 2 when n is odd
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: llvm at rifkin dot dev
Target Milestone: ---
int foo(unsigned n) {
if(n % 2 == 0) __builtin_unreachable();
return (n - 1) / 2;
}
int bar(unsigned n) {
return n >> 1;
}
foo(unsigned int):
lea eax, [rdi-1]
shr eax
ret
bar(unsigned int):
mov eax, edi
shr eax
ret
https://godbolt.org/z/3G7enYdnM
https://alive2.llvm.org/ce/z/m3qbdN
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/109044] Missed fold for (n - 1) / 2 when n is odd
2023-03-06 18:18 [Bug tree-optimization/109044] New: Missed fold for (n - 1) / 2 when n is odd llvm at rifkin dot dev
@ 2023-03-06 18:20 ` pinskia at gcc dot gnu.org
2023-03-07 9:10 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-03-06 18:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109044
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/109044] Missed fold for (n - 1) / 2 when n is odd
2023-03-06 18:18 [Bug tree-optimization/109044] New: Missed fold for (n - 1) / 2 when n is odd llvm at rifkin dot dev
2023-03-06 18:20 ` [Bug tree-optimization/109044] " pinskia at gcc dot gnu.org
@ 2023-03-07 9:10 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-03-07 9:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109044
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2023-03-07
Ever confirmed|0 |1
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-03-07 9:10 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2023-03-06 18:18 [Bug tree-optimization/109044] New: Missed fold for (n - 1) / 2 when n is odd llvm at rifkin dot dev
2023-03-06 18:20 ` [Bug tree-optimization/109044] " pinskia at gcc dot gnu.org
2023-03-07 9:10 ` rguenth at gcc dot gnu.org
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