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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/109907] Missed optimization for bit extraction (uses shift instead of single bit-test)
Date: Sat, 27 May 2023 04:02:39 +0000 [thread overview]
Message-ID: <bug-109907-4-1XilPbUUzT@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109907-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109907
--- Comment #28 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #26)
> (In reply to Andrew Pinski from comment #25)
> > Created attachment 55175 [details]
> > Patch which fixes `signed < 0`
> >
> > This patch improves comment #20 .
>
> Note this patch does not work for the case of normalizep == -1 but I have a
> fix for that.
Also note this patch improves (a lot):
```
unsigned char f(long long t)
{
return t < 0;
}
```
Down to:
```
f:
/* prologue: function */
/* frame size = 0 */
/* stack size = 0 */
.L__stack_usage = 0
mov r24,r25
rol r24
clr r24
rol r24
/* epilogue start */
ret
```
Rather than what it was in GCC 13:
```
f:
push r16
ldi r16,lo8(63)
rcall __lshrdi3
mov r24,r18
pop r16
ret
```
next prev parent reply other threads:[~2023-05-27 4:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-19 10:10 [Bug middle-end/109907] New: [avr] " gjl at gcc dot gnu.org
2023-05-19 14:14 ` [Bug middle-end/109907] " pinskia at gcc dot gnu.org
2023-05-19 15:42 ` [Bug middle-end/109907] " pinskia at gcc dot gnu.org
2023-05-19 15:45 ` pinskia at gcc dot gnu.org
2023-05-19 20:03 ` pinskia at gcc dot gnu.org
2023-05-19 20:12 ` pinskia at gcc dot gnu.org
2023-05-19 20:41 ` gjl at gcc dot gnu.org
2023-05-19 20:55 ` pinskia at gcc dot gnu.org
2023-05-19 20:59 ` gjl at gcc dot gnu.org
2023-05-20 0:46 ` pinskia at gcc dot gnu.org
2023-05-20 5:09 ` pinskia at gcc dot gnu.org
2023-05-20 7:36 ` gjl at gcc dot gnu.org
2023-05-20 7:50 ` gjl at gcc dot gnu.org
2023-05-20 22:23 ` pinskia at gcc dot gnu.org
2023-05-20 22:40 ` pinskia at gcc dot gnu.org
2023-05-21 5:15 ` pinskia at gcc dot gnu.org
2023-05-21 5:36 ` pinskia at gcc dot gnu.org
2023-05-21 9:09 ` gjl at gcc dot gnu.org
2023-05-21 9:55 ` gjl at gcc dot gnu.org
2023-05-23 9:58 ` gjl at gcc dot gnu.org
2023-05-26 8:49 ` gjl at gcc dot gnu.org
2023-05-26 11:14 ` gjl at gcc dot gnu.org
2023-05-26 15:21 ` pinskia at gcc dot gnu.org
2023-05-26 16:08 ` gjl at gcc dot gnu.org
2023-05-26 23:11 ` pinskia at gcc dot gnu.org
2023-05-26 23:34 ` pinskia at gcc dot gnu.org
2023-05-26 23:49 ` pinskia at gcc dot gnu.org
2023-05-27 0:36 ` pinskia at gcc dot gnu.org
2023-05-27 4:02 ` pinskia at gcc dot gnu.org [this message]
2023-05-27 20:09 ` pinskia at gcc dot gnu.org
2023-06-11 9:22 ` cvs-commit at gcc dot gnu.org
2023-06-11 9:26 ` gjl at gcc dot gnu.org
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