* [Bug tree-optimization/96923] Failure to optimize a select-related bool pattern to or+not
2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
@ 2020-09-03 14:49 ` gabravier at gmail dot com
2020-09-06 23:45 ` pinskia at gcc dot gnu.org
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From: gabravier at gmail dot com @ 2020-09-03 14:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
--- Comment #1 from Gabriel Ravier <gabravier at gmail dot com> ---
_Bool f2(_Bool a, _Bool b)
{
return a ? !b : 1;
}
This similar pattern can be optimized to `return !(a & b);`. This
transformation is done by LLVM, but not by GCC.
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
2020-09-03 14:49 ` [Bug tree-optimization/96923] " gabravier at gmail dot com
@ 2020-09-06 23:45 ` pinskia at gcc dot gnu.org
2020-09-06 23:47 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2020-09-06 23:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
2020-09-03 14:49 ` [Bug tree-optimization/96923] " gabravier at gmail dot com
2020-09-06 23:45 ` pinskia at gcc dot gnu.org
@ 2020-09-06 23:47 ` pinskia at gcc dot gnu.org
2021-06-01 21:02 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2020-09-06 23:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Depends on| |25290
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note if we spell out the ?:, this would require PR 25290 too.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25290
[Bug 25290] PHI-OPT could be rewritten so that is uses match
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
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2020-09-06 23:47 ` pinskia at gcc dot gnu.org
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2021-06-01 21:40 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2021-06-01 21:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2021-06-01
Ever confirmed|0 |1
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Mine, I have a patch which implements this.
It needs https://gcc.gnu.org/pipermail/gcc-patches/2021-June/571616.html first.
I will be posting this once I write some testcases and do a bootstrap/test
cycle.
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
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2021-06-01 21:02 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2021-06-01 21:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 50905
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50905&action=edit
Patch which is in testing (needs testcases)
As I said for the case in this PR, it needs
https://gcc.gnu.org/pipermail/gcc-patches/2021-June/571616.html too.
If you change !b to b; that is "!a ? b : 0", this patch will optimize it. The
other patch is needed to allow to move !b out of the conditional.
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
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2021-06-01 21:40 ` pinskia at gcc dot gnu.org
@ 2021-06-01 23:19 ` pinskia at gcc dot gnu.org
2021-06-01 23:49 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2021-06-01 23:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #4)
> Created attachment 50905 [details]
> Patch which is in testing (needs testcases)
>
> As I said for the case in this PR, it needs
> https://gcc.gnu.org/pipermail/gcc-patches/2021-June/571616.html too.
>
> If you change !b to b; that is "!a ? b : 0", this patch will optimize it.
> The other patch is needed to allow to move !b out of the conditional.
This patch has one bug in it where we need a convert added.
BUT then we run into a different missed optimization issue.
_51 = p2_22 <= prephitmp_122;
_44 = (logical(kind=4)) _51;
_37 = p2_22 > prephitmp_122;
_49 = (logical(kind=4)) _37;
_38 = _49 & found_p_63;
_46 = _38 | _44;
This is really just:
_51 = p2_22 <= prephitmp_122;
_44 = (logical(kind=4)) _51;
_46 = found_p_63| _44;
That is we don't optimize:
(a & ~b) | b into a | b if ~b has been converted already.
The other thing I noticed is the cast should not be really needed but nothing
removes it; I will look at that later.
Note I could rewrite the pattern to do the simplification of the constants
manually but I want to try to avoid that.
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
` (5 preceding siblings ...)
2021-06-01 23:19 ` pinskia at gcc dot gnu.org
@ 2021-06-01 23:49 ` pinskia at gcc dot gnu.org
2023-05-24 0:01 ` pinskia at gcc dot gnu.org
2023-07-31 17:14 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2021-06-01 23:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Depends on| |100864
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This depends on PR 100864 if I don't want to write out the 4 patterns.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100864
[Bug 100864] (a&!b) | b is not opimized to a | b for conditionals
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
` (6 preceding siblings ...)
2021-06-01 23:49 ` pinskia at gcc dot gnu.org
@ 2023-05-24 0:01 ` pinskia at gcc dot gnu.org
2023-07-31 17:14 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2023-05-24 0:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Ok, this in the end is a dup of bug 89263.
*** This bug has been marked as a duplicate of bug 89263 ***
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2020-09-03 14:06 [Bug tree-optimization/96923] New: Failure to optimize a select-related bool pattern to or+not gabravier at gmail dot com
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2023-05-24 0:01 ` pinskia at gcc dot gnu.org
@ 2023-07-31 17:14 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2023-07-31 17:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96923
Bug 96923 depends on bug 100864, which changed state.
Bug 100864 Summary: (a&!b) | b is not opimized to a | b for comparisons
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100864
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
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