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* [Bug target/110588] New: btl (on x86_64) not always generated
@ 2023-07-07 10:02 pinskia at gcc dot gnu.org
2023-07-08 21:12 ` [Bug target/110588] " roger at nextmovesoftware dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-07-07 10:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110588
Bug ID: 110588
Summary: btl (on x86_64) not always generated
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Target: x86_64-linux-gnu
Take C+ code (since I am too lazy to figure out the types):
```
unsigned char clr1_bb (unsigned char x, int y)
{
return (x & (1<<y)) == 0;
}
unsigned char clr1_bb1 (unsigned char x, int y)
{
auto _1 = (int) x;
auto _2 = _1 >> y;
auto _3 = _2 & 1;
auto _8 = (unsigned char) _3;
auto _6 = _8 ^ 1;
return _6;
}
unsigned char clr1_bb2 (unsigned char x, int y)
{
auto _1 = (int) x;
auto _2 = _1 >> y;
auto _3 = _2 & 1;
auto _6 = _3 ^ 1;
auto _8 = (unsigned char) _6;
return _6;
}
```
Right now clr1_bb and clr1_bb2 produce the btl/setnc but clr1_bb1 does not.
Note I noticed this while working on PR 110539 (I changed my patch to put the
cast after the ^1 rather than before so this is not blocking that patch).
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/110588] btl (on x86_64) not always generated
2023-07-07 10:02 [Bug target/110588] New: btl (on x86_64) not always generated pinskia at gcc dot gnu.org
@ 2023-07-08 21:12 ` roger at nextmovesoftware dot com
2023-07-09 8:08 ` ubizjak at gmail dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: roger at nextmovesoftware dot com @ 2023-07-08 21:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110588
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |roger at nextmovesoftware dot com
Status|UNCONFIRMED |ASSIGNED
Ever confirmed|0 |1
Assignee|unassigned at gcc dot gnu.org |roger at nextmovesoftware dot com
Last reconfirmed| |2023-07-08
--- Comment #1 from Roger Sayle <roger at nextmovesoftware dot com> ---
Thanks Andrew. I have a patch (a define_split in i386.md) that's currently
bootstrapping and regression testing. But perhaps this should also be fixed at
the tree-level by match.pd canonicalizing ((T)(x & C)) ^ C to (T)((~x) & C)
when T is not wider than X and X is not wider than WORD_MODE. It's tricky to
compare the costs of integer operations in different precisions, but WORD_MODE
(and int) operations are (typically) always cheap (and I believe unary
operations are preferred over binary operations (with immediate constants)).
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/110588] btl (on x86_64) not always generated
2023-07-07 10:02 [Bug target/110588] New: btl (on x86_64) not always generated pinskia at gcc dot gnu.org
2023-07-08 21:12 ` [Bug target/110588] " roger at nextmovesoftware dot com
@ 2023-07-09 8:08 ` ubizjak at gmail dot com
2023-07-14 17:22 ` cvs-commit at gcc dot gnu.org
2023-07-23 5:06 ` roger at nextmovesoftware dot com
3 siblings, 0 replies; 5+ messages in thread
From: ubizjak at gmail dot com @ 2023-07-09 8:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110588
Uroš Bizjak <ubizjak at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=107671
--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
Similar missed optimization is reported in PR107671.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/110588] btl (on x86_64) not always generated
2023-07-07 10:02 [Bug target/110588] New: btl (on x86_64) not always generated pinskia at gcc dot gnu.org
2023-07-08 21:12 ` [Bug target/110588] " roger at nextmovesoftware dot com
2023-07-09 8:08 ` ubizjak at gmail dot com
@ 2023-07-14 17:22 ` cvs-commit at gcc dot gnu.org
2023-07-23 5:06 ` roger at nextmovesoftware dot com
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-07-14 17:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110588
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>:
https://gcc.gnu.org/g:43a0a5cd57eefd5a5bbead606ec4f6959af31802
commit r14-2528-g43a0a5cd57eefd5a5bbead606ec4f6959af31802
Author: Roger Sayle <roger@nextmovesoftware.com>
Date: Fri Jul 14 18:21:56 2023 +0100
PR target/110588: Add *bt<mode>_setncqi_2 to generate btl on x86.
This patch resolves PR target/110588 to catch another case in combine
where the i386 backend should be generating a btl instruction. This adds
another define_insn_and_split to recognize the RTL representation for this
case.
I also noticed that two related define_insn_and_split weren't using the
preferred string style for single statement preparation-statements, so
I've reformatted these to be consistent in style with the new one.
2023-07-14 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
PR target/110588
* config/i386/i386.md (*bt<mode>_setcqi): Prefer string form
preparation statement over braces for a single statement.
(*bt<mode>_setncqi): Likewise.
(*bt<mode>_setncqi_2): New define_insn_and_split.
gcc/testsuite/ChangeLog
PR target/110588
* gcc.target/i386/pr110588.c: New test case.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/110588] btl (on x86_64) not always generated
2023-07-07 10:02 [Bug target/110588] New: btl (on x86_64) not always generated pinskia at gcc dot gnu.org
` (2 preceding siblings ...)
2023-07-14 17:22 ` cvs-commit at gcc dot gnu.org
@ 2023-07-23 5:06 ` roger at nextmovesoftware dot com
3 siblings, 0 replies; 5+ messages in thread
From: roger at nextmovesoftware dot com @ 2023-07-23 5:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110588
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #4 from Roger Sayle <roger at nextmovesoftware dot com> ---
This is now fixed on mainline for GCC 14.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2023-07-07 10:02 [Bug target/110588] New: btl (on x86_64) not always generated pinskia at gcc dot gnu.org
2023-07-08 21:12 ` [Bug target/110588] " roger at nextmovesoftware dot com
2023-07-09 8:08 ` ubizjak at gmail dot com
2023-07-14 17:22 ` cvs-commit at gcc dot gnu.org
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