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* [Bug target/81456] [9/10/11/12 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
@ 2021-05-14 9:49 ` jakub at gcc dot gnu.org
2021-06-01 8:09 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-05-14 9:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|8.5 |9.4
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/81456] [9/10/11/12 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
2021-05-14 9:49 ` [Bug target/81456] [9/10/11/12 Regression] x86-64 optimizer makes wrong decision when optimizing for size jakub at gcc dot gnu.org
@ 2021-06-01 8:09 ` rguenth at gcc dot gnu.org
2022-05-27 9:37 ` [Bug target/81456] [10/11/12/13 " rguenth at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-06-01 8:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.4 |9.5
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/81456] [10/11/12/13 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
2021-05-14 9:49 ` [Bug target/81456] [9/10/11/12 Regression] x86-64 optimizer makes wrong decision when optimizing for size jakub at gcc dot gnu.org
2021-06-01 8:09 ` rguenth at gcc dot gnu.org
@ 2022-05-27 9:37 ` rguenth at gcc dot gnu.org
2022-06-28 10:33 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-05-27 9:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.5 |10.4
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/81456] [10/11/12/13 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2022-05-27 9:37 ` [Bug target/81456] [10/11/12/13 " rguenth at gcc dot gnu.org
@ 2022-06-28 10:33 ` jakub at gcc dot gnu.org
2023-07-07 10:32 ` [Bug target/81456] [11/12/13/14 " rguenth at gcc dot gnu.org
2023-12-28 2:58 ` lh_mouse at 126 dot com
5 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-06-28 10:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.4 |10.5
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/81456] [11/12/13/14 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2022-06-28 10:33 ` jakub at gcc dot gnu.org
@ 2023-07-07 10:32 ` rguenth at gcc dot gnu.org
2023-12-28 2:58 ` lh_mouse at 126 dot com
5 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-07-07 10:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.5 |11.5
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/81456] [11/12/13/14 Regression] x86-64 optimizer makes wrong decision when optimizing for size
[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
` (4 preceding siblings ...)
2023-07-07 10:32 ` [Bug target/81456] [11/12/13/14 " rguenth at gcc dot gnu.org
@ 2023-12-28 2:58 ` lh_mouse at 126 dot com
5 siblings, 0 replies; 6+ messages in thread
From: lh_mouse at 126 dot com @ 2023-12-28 2:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81456
LIU Hao <lh_mouse at 126 dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |lh_mouse at 126 dot com
--- Comment #12 from LIU Hao <lh_mouse at 126 dot com> ---
Is this the same issue?
https://gcc.godbolt.org/z/sTs3E9EP1
```
struct stack
{
void** base;
unsigned int top, cap;
};
struct context
{
void* data;
stack* st;
};
int
clear_stack(context& ctx)
{
ctx.st->top = 0;
return 0;
}
```
GCC reuses RAX for `ctx.st` and the return value, so an extra XOR is generated:
```
clear_stack(context&):
mov rax,QWORD PTR [rdi+0x8]
xor edx,edx <-- this would be unnecessary if
`xor eax, eax` was lifted here
mov DWORD PTR [rax+0x8],edx
xor eax,eax
ret
```
as in
```
clear_stack_2(context&):
mov rcx,QWORD PTR [rdi+0x8] # 48 8b 4f 08
xor eax,eax # 31 c0
mov DWORD PTR [rcx+0x8],eax # 89 41 08
ret # c3
```
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-12-28 2:58 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <bug-81456-4@http.gcc.gnu.org/bugzilla/>
2021-05-14 9:49 ` [Bug target/81456] [9/10/11/12 Regression] x86-64 optimizer makes wrong decision when optimizing for size jakub at gcc dot gnu.org
2021-06-01 8:09 ` rguenth at gcc dot gnu.org
2022-05-27 9:37 ` [Bug target/81456] [10/11/12/13 " rguenth at gcc dot gnu.org
2022-06-28 10:33 ` jakub at gcc dot gnu.org
2023-07-07 10:32 ` [Bug target/81456] [11/12/13/14 " rguenth at gcc dot gnu.org
2023-12-28 2:58 ` lh_mouse at 126 dot com
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