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* [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms
@ 2020-08-05 8:53 kurkindmit at gmail dot com
2020-08-05 11:22 ` [Bug c++/96480] [8/9/10/11 Regression] " jakub at gcc dot gnu.org
` (11 more replies)
0 siblings, 12 replies; 13+ messages in thread
From: kurkindmit at gmail dot com @ 2020-08-05 8:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Bug ID: 96480
Summary: missed optimisation: unnecessary compare in standard
algorithms
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: kurkindmit at gmail dot com
Target Milestone: ---
Consider the C++ code:
#include <algorithm>
#include <array>
enum ENUM { A, B, C, D, E, F, G, };
const std::array<ENUM, 4> foo{A, B, C, D};
bool is_foo(ENUM e) {
return std::any_of(foo.begin(), foo.end(),
[e] (auto ee) { return e == ee; });
}
GCC 7.4 optimizes if_foo to a single compare operation e <= 3,
but newer GCC versions do two comare operations e <= 2 || e == 3.
see https://godbolt.org/z/5a6aPa
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
@ 2020-08-05 11:22 ` jakub at gcc dot gnu.org
2020-08-05 11:26 ` jakub at gcc dot gnu.org
` (10 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-08-05 11:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |8.5
Ever confirmed|0 |1
Summary|missed optimisation: |[8/9/10/11 Regression]
|unnecessary compare in |missed optimisation:
|standard algorithms |unnecessary compare in
| |standard algorithms
Last reconfirmed| |2020-08-05
CC| |jakub at gcc dot gnu.org
Status|UNCONFIRMED |NEW
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r8-565-g7581ce9a1ad6df9c8998a3c74256837a1ff6f7cc
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug c++/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
2020-08-05 11:22 ` [Bug c++/96480] [8/9/10/11 Regression] " jakub at gcc dot gnu.org
@ 2020-08-05 11:26 ` jakub at gcc dot gnu.org
2020-08-05 11:32 ` [Bug tree-optimization/96480] " rguenth at gcc dot gnu.org
` (9 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-08-05 11:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
That commit changes the pre-reassoc2 dump like:
--- pr96480.ii.172t.printf-return-value2_ 2020-08-05 07:22:42.000000000
-0400
+++ pr96480.ii.172t.printf-return-value2 2020-08-05 07:23:32.000000000
-0400
@@ -31,13 +31,13 @@ bool is_foo(ENUM) (ENUM e)
<bb 5> [12.87%]:
if (e_2(D) == 3)
- goto <bb 7> (<L4>); [3.00%]
+ goto <bb 6>; [3.00%]
else
- goto <bb 6>; [97.00%]
+ goto <bb 7> (<L4>); [97.00%]
- <bb 6> [12.48%]:
+ <bb 6> [0.39%]:
- # prephitmp_5 = PHI <1(2), 1(3), 1(4), 1(5), 0(6)>
+ # prephitmp_5 = PHI <1(2), 1(3), 1(4), 1(6), 0(5)>
<L4> [14.13%]:
return prephitmp_5;
So I guess I need to debug why reassoc doesn't like that form.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
2020-08-05 11:22 ` [Bug c++/96480] [8/9/10/11 Regression] " jakub at gcc dot gnu.org
2020-08-05 11:26 ` jakub at gcc dot gnu.org
@ 2020-08-05 11:32 ` rguenth at gcc dot gnu.org
2020-08-05 11:44 ` jakub at gcc dot gnu.org
` (8 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-08-05 11:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
Component|c++ |tree-optimization
Keywords| |missed-optimization
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (2 preceding siblings ...)
2020-08-05 11:32 ` [Bug tree-optimization/96480] " rguenth at gcc dot gnu.org
@ 2020-08-05 11:44 ` jakub at gcc dot gnu.org
2020-08-05 14:29 ` jakub at gcc dot gnu.org
` (7 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-08-05 11:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Simplified testcase:
int v[4];
int
foo (int x)
{
int *p;
if (x == 0)
p = &v[0];
else if (x == 1)
p = &v[1];
else if (x == 2)
p = &v[2];
else if (x == 3)
p = &v[3];
else
p = &v[4];
return p != &v[4];
}
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (3 preceding siblings ...)
2020-08-05 11:44 ` jakub at gcc dot gnu.org
@ 2020-08-05 14:29 ` jakub at gcc dot gnu.org
2020-08-06 13:48 ` cvs-commit at gcc dot gnu.org
` (6 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-08-05 14:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org
Status|NEW |ASSIGNED
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 49005
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49005&action=edit
gcc11-pr96480.patch
Untested fix.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [8/9/10/11 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (4 preceding siblings ...)
2020-08-05 14:29 ` jakub at gcc dot gnu.org
@ 2020-08-06 13:48 ` cvs-commit at gcc dot gnu.org
2020-08-06 13:53 ` [Bug tree-optimization/96480] [8/9/10 " jakub at gcc dot gnu.org
` (5 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-08-06 13:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:b3aa137212b1af0c824a9890eba2ca27a7271d56
commit r11-2593-gb3aa137212b1af0c824a9890eba2ca27a7271d56
Author: Jakub Jelinek <jakub@redhat.com>
Date: Thu Aug 6 15:47:25 2020 +0200
reassoc: Improve maybe_optimize_range_tests [PR96480]
On the following testcase, if the IL before reassoc would be:
...
<bb 4> [local count: 354334800]:
if (x_3(D) == 2)
goto <bb 7>; [34.00%]
else
goto <bb 5>; [66.00%]
<bb 5> [local count: 233860967]:
if (x_3(D) == 3)
goto <bb 7>; [34.00%]
else
goto <bb 6>; [66.00%]
<bb 6> [local count: 79512730]:
<bb 7> [local count: 1073741824]:
# prephitmp_7 = PHI <1(3), 1(4), 1(5), 1(2), 0(6)>
then we'd optimize it properly, but as bb 5-7 is instead:
<bb 5> [local count: 233860967]:
if (x_3(D) == 3)
goto <bb 6>; [34.00%]
else
goto <bb 7>; [66.00%]
<bb 6> [local count: 79512730]:
<bb 7> [local count: 1073741824]:
# prephitmp_7 = PHI <1(3), 1(4), 0(5), 1(2), 1(6)>
(i.e. the true/false edges on the last bb with condition swapped
and ditto for the phi args), we don't recognize it. If bb 6
is empty, there should be no functional difference between the two IL
representations.
This patch handles those special cases.
2020-08-06 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/96480
* tree-ssa-reassoc.c (suitable_cond_bb): Add TEST_SWAPPED_P
argument.
If TEST_BB ends in cond and has one edge to *OTHER_BB and another
through an empty bb to that block too, if PHI args don't match,
retry
them through the other path from TEST_BB.
(maybe_optimize_range_tests): Adjust callers. Handle such LAST_BB
through inversion of the condition.
* gcc.dg/tree-ssa/pr96480.c: New test.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [8/9/10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (5 preceding siblings ...)
2020-08-06 13:48 ` cvs-commit at gcc dot gnu.org
@ 2020-08-06 13:53 ` jakub at gcc dot gnu.org
2021-05-14 9:53 ` [Bug tree-optimization/96480] [9/10 " jakub at gcc dot gnu.org
` (4 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2020-08-06 13:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[8/9/10/11 Regression] |[8/9/10 Regression] missed
|missed optimisation: |optimisation: unnecessary
|unnecessary compare in |compare in standard
|standard algorithms |algorithms
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be fixed on the trunk.
As it is essentially a new optimization, not sure if it is a good idea to
backport it, even when it has been a regression on this testcase.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/96480] [9/10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (6 preceding siblings ...)
2020-08-06 13:53 ` [Bug tree-optimization/96480] [8/9/10 " jakub at gcc dot gnu.org
@ 2021-05-14 9:53 ` jakub at gcc dot gnu.org
2021-06-01 8:18 ` rguenth at gcc dot gnu.org
` (3 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-05-14 9:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
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] 13+ messages in thread
* [Bug tree-optimization/96480] [9/10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (7 preceding siblings ...)
2021-05-14 9:53 ` [Bug tree-optimization/96480] [9/10 " jakub at gcc dot gnu.org
@ 2021-06-01 8:18 ` rguenth at gcc dot gnu.org
2022-05-27 9:43 ` [Bug tree-optimization/96480] [10 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-06-01 8:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
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] 13+ messages in thread
* [Bug tree-optimization/96480] [10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (8 preceding siblings ...)
2021-06-01 8:18 ` rguenth at gcc dot gnu.org
@ 2022-05-27 9:43 ` rguenth at gcc dot gnu.org
2022-06-28 10:41 ` jakub at gcc dot gnu.org
2023-07-07 9:01 ` rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-05-27 9:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
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] 13+ messages in thread
* [Bug tree-optimization/96480] [10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (9 preceding siblings ...)
2022-05-27 9:43 ` [Bug tree-optimization/96480] [10 " rguenth at gcc dot gnu.org
@ 2022-06-28 10:41 ` jakub at gcc dot gnu.org
2023-07-07 9:01 ` rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-06-28 10:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
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] 13+ messages in thread
* [Bug tree-optimization/96480] [10 Regression] missed optimisation: unnecessary compare in standard algorithms
2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
` (10 preceding siblings ...)
2022-06-28 10:41 ` jakub at gcc dot gnu.org
@ 2023-07-07 9:01 ` rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-07-07 9:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |10.5.0
Status|ASSIGNED |RESOLVED
Known to work| |11.0
Target Milestone|10.5 |11.0
Resolution|--- |FIXED
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed in GCC 11.
^ permalink raw reply [flat|nested] 13+ messages in thread
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2020-08-05 8:53 [Bug c++/96480] New: missed optimisation: unnecessary compare in standard algorithms kurkindmit at gmail dot com
2020-08-05 11:22 ` [Bug c++/96480] [8/9/10/11 Regression] " jakub at gcc dot gnu.org
2020-08-05 11:26 ` jakub at gcc dot gnu.org
2020-08-05 11:32 ` [Bug tree-optimization/96480] " rguenth at gcc dot gnu.org
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2020-08-05 14:29 ` jakub at gcc dot gnu.org
2020-08-06 13:48 ` cvs-commit at gcc dot gnu.org
2020-08-06 13:53 ` [Bug tree-optimization/96480] [8/9/10 " jakub at gcc dot gnu.org
2021-05-14 9:53 ` [Bug tree-optimization/96480] [9/10 " jakub at gcc dot gnu.org
2021-06-01 8:18 ` rguenth at gcc dot gnu.org
2022-05-27 9:43 ` [Bug tree-optimization/96480] [10 " rguenth at gcc dot gnu.org
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