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* [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1`
@ 2024-04-10 20:49 pinskia at gcc dot gnu.org
2024-04-10 20:57 ` [Bug tree-optimization/114684] " pinskia at gcc dot gnu.org
2024-04-11 6:41 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-10 20:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114684
Bug ID: 114684
Summary: `-(int)(unsigned:1)signed:1` could just be
`(int)signed:1`
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
struct t{
signed s1 : 1;
unsigned u1 : 1;
} b = {-1};
int f()
{
struct t tt = b;
return tt.s1;
}
int f1()
{
struct t tt = b;
tt.u1 = tt.s1;
int ttt = tt.u1;
return -ttt;
}
```
These 2 functions should produce the same code. (For aarch64 it almost does,
there is an extra sign extend in f). I noticed this while fixing PR 114666. It
is also related to PR 101955. Note this only works for 1bit signed values.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/114684] `-(int)(unsigned:1)signed:1` could just be `(int)signed:1`
2024-04-10 20:49 [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1` pinskia at gcc dot gnu.org
@ 2024-04-10 20:57 ` pinskia at gcc dot gnu.org
2024-04-11 6:41 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-10 20:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114684
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note clang Canonicalizes it into `-([b]&1)` (though on aarch64, they don't use
sbfx while GCC does uses that).
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/114684] `-(int)(unsigned:1)signed:1` could just be `(int)signed:1`
2024-04-10 20:49 [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1` pinskia at gcc dot gnu.org
2024-04-10 20:57 ` [Bug tree-optimization/114684] " pinskia at gcc dot gnu.org
@ 2024-04-11 6:41 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-04-11 6:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114684
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2024-04-11
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-04-10 20:49 [Bug tree-optimization/114684] New: `-(int)(unsigned:1)signed:1` could just be `(int)signed:1` pinskia at gcc dot gnu.org
2024-04-10 20:57 ` [Bug tree-optimization/114684] " pinskia at gcc dot gnu.org
2024-04-11 6:41 ` rguenth at gcc dot gnu.org
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