public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu
@ 2021-11-17 10:17 zhendong.su at inf dot ethz.ch
2021-11-17 10:24 ` [Bug tree-optimization/103300] [12 Regression] " pinskia at gcc dot gnu.org
` (9 more replies)
0 siblings, 10 replies; 11+ messages in thread
From: zhendong.su at inf dot ethz.ch @ 2021-11-17 10:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Bug ID: 103300
Summary: wrong code at -O3 on x86_64-linux-gnu
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhendong.su at inf dot ethz.ch
Target Milestone: ---
It appears to be a recent regression.
[596] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-languages=c,c++
--disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20211117 (experimental) [master r12-5333-g1a15a91a001] (GCC)
[597] %
[597] % gcctk -O2 small.c; ./a.out
[598] %
[598] % gcc110 -O3 small.c; ./a.out
[599] %
[599] % gcctk -O3 small.c
[600] % ./a.out
Aborted
[601] %
[601] % cat small.c
int a, b[2], c, d, e, f;
int g(int h, int i) { return !i || h && i == 1 ? 0 : h % i; }
void j() {
while (1)
while (1) {
if (d)
L:
if (f)
break;
if (e)
goto L;
return;
}
}
int main() {
j();
for (c = 0; c < 3; c++)
for (a = 0; a < 2; a++)
if (g(0, b[a]++))
while (1)
;
if (b[1] != 3)
__builtin_abort();
return 0;
}
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
@ 2021-11-17 10:24 ` pinskia at gcc dot gnu.org
2021-11-17 11:08 ` [Bug tree-optimization/103300] New: " Jan Hubicka
` (8 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-17 10:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Keywords| |needs-bisection, wrong-code
Last reconfirmed| |2021-11-17
Ever confirmed|0 |1
Target Milestone|--- |12.0
Summary|wrong code at -O3 on |[12 Regression] wrong code
|x86_64-linux-gnu |at -O3 on x86_64-linux-gnu
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2021-11-17 10:24 ` [Bug tree-optimization/103300] [12 Regression] " pinskia at gcc dot gnu.org
@ 2021-11-17 11:08 ` Jan Hubicka
2021-11-17 11:08 ` [Bug tree-optimization/103300] [12 Regression] " hubicka at kam dot mff.cuni.cz
` (7 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: Jan Hubicka @ 2021-11-17 11:08 UTC (permalink / raw)
To: zhendong.su at inf dot ethz.ch; +Cc: gcc-bugs
Needs -O2 -floop-unroll-and-jam --param early-inlining-insns=14
to fail, so I guess it may be issue with unrol-and-jam.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2021-11-17 10:24 ` [Bug tree-optimization/103300] [12 Regression] " pinskia at gcc dot gnu.org
2021-11-17 11:08 ` [Bug tree-optimization/103300] New: " Jan Hubicka
@ 2021-11-17 11:08 ` hubicka at kam dot mff.cuni.cz
2021-11-17 22:32 ` pinskia at gcc dot gnu.org
` (6 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: hubicka at kam dot mff.cuni.cz @ 2021-11-17 11:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
--- Comment #2 from hubicka at kam dot mff.cuni.cz ---
Needs -O2 -floop-unroll-and-jam --param early-inlining-insns=14
to fail, so I guess it may be issue with unrol-and-jam.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (2 preceding siblings ...)
2021-11-17 11:08 ` [Bug tree-optimization/103300] [12 Regression] " hubicka at kam dot mff.cuni.cz
@ 2021-11-17 22:32 ` pinskia at gcc dot gnu.org
2021-11-18 7:47 ` rguenth at gcc dot gnu.org
` (5 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-17 22:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to hubicka from comment #2)
> Needs -O2 -floop-unroll-and-jam --param early-inlining-insns=14
> to fail, so I guess it may be issue with unrol-and-jam.
The major difference I see between GCC 11 and GCC 12 is how tree-loop-im
handles the load/store of a and c. In GCC 11, it was an unconditional move of
the store of a and c while in GCC 12 we get some interesting branches:
<bb 9> [local count: 35059055]:
# a_lsm.21_25 = PHI <_20(D)(6), _15(8)>
# a_lsm_flag.22_8 = PHI <0(6), 1(8)>
# c_lsm.23_22 = PHI <0(6), _5(8)>
if (c_lsm.23_22 <= 2)
goto <bb 17>; [94.50%]
else
goto <bb 10>; [5.50%]
<bb 10> [local count: 1928248]:
# a_lsm_flag.22_14 = PHI <a_lsm_flag.22_8(9)>
# a_lsm.21_28 = PHI <a_lsm.21_25(9)>
c_lsm.23_27 = 3;
if (a_lsm_flag.22_14 != 0)
goto <bb 11>; [66.67%]
else
goto <bb 12>; [33.33%]
<bb 11> [local count: 1285499]:
c = c_lsm.23_27;
<bb 12> [local count: 1285499]:
if (a_lsm_flag.22_14 != 0)
goto <bb 13>; [66.67%]
else
goto <bb 14>; [33.33%]
<bb 13> [local count: 856999]:
a = a_lsm.21_28;
<bb 14> [local count: 1928248]:
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (3 preceding siblings ...)
2021-11-17 22:32 ` pinskia at gcc dot gnu.org
@ 2021-11-18 7:47 ` rguenth at gcc dot gnu.org
2021-11-18 10:37 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-11-18 7:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unknown |12.0
Priority|P3 |P1
CC| |rguenth at gcc dot gnu.org
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (4 preceding siblings ...)
2021-11-18 7:47 ` rguenth at gcc dot gnu.org
@ 2021-11-18 10:37 ` rguenth at gcc dot gnu.org
2021-11-18 10:39 ` [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b marxin at gcc dot gnu.org
` (3 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-11-18 10:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |matz at gcc dot gnu.org
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> (In reply to hubicka from comment #2)
> > Needs -O2 -floop-unroll-and-jam --param early-inlining-insns=14
> > to fail, so I guess it may be issue with unrol-and-jam.
>
> The major difference I see between GCC 11 and GCC 12 is how tree-loop-im
> handles the load/store of a and c. In GCC 11, it was an unconditional move
> of the store of a and c while in GCC 12 we get some interesting branches:
> <bb 9> [local count: 35059055]:
> # a_lsm.21_25 = PHI <_20(D)(6), _15(8)>
> # a_lsm_flag.22_8 = PHI <0(6), 1(8)>
> # c_lsm.23_22 = PHI <0(6), _5(8)>
> if (c_lsm.23_22 <= 2)
> goto <bb 17>; [94.50%]
> else
> goto <bb 10>; [5.50%]
>
> <bb 10> [local count: 1928248]:
> # a_lsm_flag.22_14 = PHI <a_lsm_flag.22_8(9)>
> # a_lsm.21_28 = PHI <a_lsm.21_25(9)>
> c_lsm.23_27 = 3;
> if (a_lsm_flag.22_14 != 0)
> goto <bb 11>; [66.67%]
> else
> goto <bb 12>; [33.33%]
>
> <bb 11> [local count: 1285499]:
> c = c_lsm.23_27;
>
> <bb 12> [local count: 1285499]:
> if (a_lsm_flag.22_14 != 0)
> goto <bb 13>; [66.67%]
> else
> goto <bb 14>; [33.33%]
>
> <bb 13> [local count: 856999]:
> a = a_lsm.21_28;
>
> <bb 14> [local count: 1928248]:
That's likely a missed threading / header copying, the stores are conditional
now and thus need protecting against store data races.
What unroll-and-jam does is make the inner loop enter always, only considering
the loop header check for the second iteration and also fails to include the
increment. That's likely a latent issue, maybe because the latch of the
outer loop is not empty?
Testcase that fails with -O2 -floop-unroll-and-jam:
int a, b[2], c, d, e, f;
int g(int h, int i) { return !i || h && i == 1 ? 0 : h % i; }
static void j() {
while (1)
while (1) {
if (d)
L:
if (f)
break;
if (e)
goto L;
return;
}
}
int main() {
j();
for (c = 0; c < 3; c++)
for (a = 0; a < 2; a++)
if (g(0, b[a]++))
while (1)
;
if (b[1] != 3)
__builtin_abort();
return 0;
}
Micha?
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (5 preceding siblings ...)
2021-11-18 10:37 ` rguenth at gcc dot gnu.org
@ 2021-11-18 10:39 ` marxin at gcc dot gnu.org
2021-12-02 7:22 ` zhendong.su at inf dot ethz.ch
` (2 subsequent siblings)
9 siblings, 0 replies; 11+ messages in thread
From: marxin at gcc dot gnu.org @ 2021-11-18 10:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[12 Regression] wrong code |[12 Regression] wrong code
|at -O3 on x86_64-linux-gnu |at -O3 on x86_64-linux-gnu
| |since
| |r12-4526-gd8edfadfc7a9795b
CC| |marxin at gcc dot gnu.org
Keywords|needs-bisection |
--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
Exposed by r12-4526-gd8edfadfc7a9795b.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (6 preceding siblings ...)
2021-11-18 10:39 ` [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b marxin at gcc dot gnu.org
@ 2021-12-02 7:22 ` zhendong.su at inf dot ethz.ch
2021-12-02 9:14 ` marxin at gcc dot gnu.org
2022-02-15 12:53 ` rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: zhendong.su at inf dot ethz.ch @ 2021-12-02 7:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
--- Comment #6 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
Another test likely for the same issue:
[652] % gcctk -O3 small.c; ./a.out
Aborted
[653] % gcctk -O2 -floop-unroll-and-jam small.c; ./a.out
Aborted
[654] % cat small.c
int printf(const char *, ...);
int a[2], b, c, d, e;
int main() {
if (b) {
printf("0");
goto L2;
}
L1:
b = 0;
L2:
if (d)
L3:
goto L1;
if (e)
goto L3;
if (c)
goto L2;
for (b = 0; b < 3; b++)
for (d = 0; d < 2; d++)
a[d] ^= 1;
if (a[1] != 1)
__builtin_abort();
return 0;
}
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (7 preceding siblings ...)
2021-12-02 7:22 ` zhendong.su at inf dot ethz.ch
@ 2021-12-02 9:14 ` marxin at gcc dot gnu.org
2022-02-15 12:53 ` rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: marxin at gcc dot gnu.org @ 2021-12-02 9:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
--- Comment #7 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Zhendong Su from comment #6)
> Another test likely for the same issue:
>
> [652] % gcctk -O3 small.c; ./a.out
> Aborted
> [653] % gcctk -O2 -floop-unroll-and-jam small.c; ./a.out
> Aborted
> [654] % cat small.c
> int printf(const char *, ...);
> int a[2], b, c, d, e;
> int main() {
> if (b) {
> printf("0");
> goto L2;
> }
> L1:
> b = 0;
> L2:
> if (d)
> L3:
> goto L1;
> if (e)
> goto L3;
> if (c)
> goto L2;
> for (b = 0; b < 3; b++)
> for (d = 0; d < 2; d++)
> a[d] ^= 1;
> if (a[1] != 1)
> __builtin_abort();
> return 0;
> }
Yes, started with the same revision.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (8 preceding siblings ...)
2021-12-02 9:14 ` marxin at gcc dot gnu.org
@ 2022-02-15 12:53 ` rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-02-15 12:53 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103300
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed by the fix for PR104543. Likely caused by less aggressive jump threading
in the end.
*** This bug has been marked as a duplicate of bug 104543 ***
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-02-15 12:53 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-17 10:17 [Bug tree-optimization/103300] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2021-11-17 10:24 ` [Bug tree-optimization/103300] [12 Regression] " pinskia at gcc dot gnu.org
2021-11-17 11:08 ` [Bug tree-optimization/103300] New: " Jan Hubicka
2021-11-17 11:08 ` [Bug tree-optimization/103300] [12 Regression] " hubicka at kam dot mff.cuni.cz
2021-11-17 22:32 ` pinskia at gcc dot gnu.org
2021-11-18 7:47 ` rguenth at gcc dot gnu.org
2021-11-18 10:37 ` rguenth at gcc dot gnu.org
2021-11-18 10:39 ` [Bug tree-optimization/103300] [12 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-4526-gd8edfadfc7a9795b marxin at gcc dot gnu.org
2021-12-02 7:22 ` zhendong.su at inf dot ethz.ch
2021-12-02 9:14 ` marxin at gcc dot gnu.org
2022-02-15 12:53 ` rguenth at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).