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* [Bug tree-optimization/105295] New: missed optimization with -ftrapv for conditional constants
@ 2022-04-16 19:02 roland.illig at gmx dot de
2022-04-17 21:18 ` [Bug tree-optimization/105295] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: roland.illig at gmx dot de @ 2022-04-16 19:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105295
Bug ID: 105295
Summary: missed optimization with -ftrapv for conditional
constants
Product: gcc
Version: 12.0
URL: https://godbolt.org/z/4rojo77a7
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: roland.illig at gmx dot de
Target Milestone: ---
~~~c
int sum_const(_Bool a, _Bool b)
{
return (a ? 1 : 0 ) + (b ? 1 : 0);
}
int sum_unknown(int a, int b)
{
return a + b;
}
~~~
For both functions, GCC calls __addvsi3, even though in sum_const, it is easy
to see that no overflow can ever happen since the sum is always in the range [0
... 2].
Clang optimizes this code reasonably.
ICC apparently does not care about -ftrapv at all.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/105295] missed optimization with -ftrapv for conditional constants
2022-04-16 19:02 [Bug tree-optimization/105295] New: missed optimization with -ftrapv for conditional constants roland.illig at gmx dot de
@ 2022-04-17 21:18 ` pinskia at gcc dot gnu.org
2022-04-17 21:18 ` pinskia at gcc dot gnu.org
2022-04-17 21:19 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-04-17 21:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105295
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
URL|https://godbolt.org/z/4rojo |
|77a7 |
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
https://godbolt.org/z/4rojo77a7
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/105295] missed optimization with -ftrapv for conditional constants
2022-04-16 19:02 [Bug tree-optimization/105295] New: missed optimization with -ftrapv for conditional constants roland.illig at gmx dot de
2022-04-17 21:18 ` [Bug tree-optimization/105295] " pinskia at gcc dot gnu.org
@ 2022-04-17 21:18 ` pinskia at gcc dot gnu.org
2022-04-17 21:19 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-04-17 21:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105295
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Yes trapv is implemented during expansion (from gimple to RTL) and not really
optimized.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/105295] missed optimization with -ftrapv for conditional constants
2022-04-16 19:02 [Bug tree-optimization/105295] New: missed optimization with -ftrapv for conditional constants roland.illig at gmx dot de
2022-04-17 21:18 ` [Bug tree-optimization/105295] " pinskia at gcc dot gnu.org
2022-04-17 21:18 ` pinskia at gcc dot gnu.org
@ 2022-04-17 21:19 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-04-17 21:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105295
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Depends on| |101521
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
PR 101521 records on how it should be implemented differently. Maybe for GCC
13, it will change.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101521
[Bug 101521] -ftrapv should become something like -fsanitize=undefined
-fsanitize-undefined-trap-on-error
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-04-17 21:19 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-04-16 19:02 [Bug tree-optimization/105295] New: missed optimization with -ftrapv for conditional constants roland.illig at gmx dot de
2022-04-17 21:18 ` [Bug tree-optimization/105295] " pinskia at gcc dot gnu.org
2022-04-17 21:18 ` pinskia at gcc dot gnu.org
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