* [Bug c++/92985] missed optimization opportunity for switch linear transformation
[not found] <bug-92985-4@http.gcc.gnu.org/bugzilla/>
@ 2021-03-27 10:33 ` avi@cloudius-systems.com
2021-04-27 11:38 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 4+ messages in thread
From: avi@cloudius-systems.com @ 2021-03-27 10:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92985
Avi Kivity <avi@cloudius-systems.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |avi@cloudius-systems.com
--- Comment #5 from Avi Kivity <avi@cloudius-systems.com> ---
Here's another example:
#include <compare>
int strong_ordering_to_int(std::strong_ordering x) {
if (x == std::strong_ordering::equal) {
return 0;
} else if (x == std::strong_ordering::less) {
return -1;
} else if (x == std::strong_ordering::greater) {
return 1;
}
__builtin_unreachable();
}
Used to translate the new std::strong_ordering back to int (in this case for
compatibility with older code, but one can imagine many such translations from
opaque enums to another enum when crossing an API boundary).
gcc generates (-O3)
strong_ordering_to_int(std::strong_ordering):
xorl %eax, %eax
testb %dil, %dil
je .L1
xorl %eax, %eax
cmpb $-1, %dil
setne %al
leal -1(%rax,%rax), %eax
.L1:
ret
Where it could have generated
movsx %dil, %eax
ret
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug c++/92985] missed optimization opportunity for switch linear transformation
[not found] <bug-92985-4@http.gcc.gnu.org/bugzilla/>
2021-03-27 10:33 ` [Bug c++/92985] missed optimization opportunity for switch linear transformation avi@cloudius-systems.com
@ 2021-04-27 11:38 ` jakub at gcc dot gnu.org
2021-07-28 7:04 ` rguenth at gcc dot gnu.org
2021-11-29 20:41 ` [Bug tree-optimization/92985] " pinskia at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-04-27 11:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92985
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|11.0 |11.2
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 11.1 has been released, retargeting bugs to GCC 11.2.
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug c++/92985] missed optimization opportunity for switch linear transformation
[not found] <bug-92985-4@http.gcc.gnu.org/bugzilla/>
2021-03-27 10:33 ` [Bug c++/92985] missed optimization opportunity for switch linear transformation avi@cloudius-systems.com
2021-04-27 11:38 ` jakub at gcc dot gnu.org
@ 2021-07-28 7:04 ` rguenth at gcc dot gnu.org
2021-11-29 20:41 ` [Bug tree-optimization/92985] " pinskia at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-07-28 7:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92985
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|11.2 |---
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug tree-optimization/92985] missed optimization opportunity for switch linear transformation
[not found] <bug-92985-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2021-07-28 7:04 ` rguenth at gcc dot gnu.org
@ 2021-11-29 20:41 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-29 20:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92985
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|c++ |tree-optimization
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 4+ messages in thread