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* [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu
@ 2022-06-24 8:06 zhendong.su at inf dot ethz.ch
2022-06-24 8:06 ` [Bug tree-optimization/106073] " zhendong.su at inf dot ethz.ch
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: zhendong.su at inf dot ethz.ch @ 2022-06-24 8:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Bug ID: 106073
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 seems to be a regression from 11.*. The test is still quite complicated, but
seems difficult to be reduced much further.
[507] % 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/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-sanitizers
--enable-languages=c,c++ --disable-werror --disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220624 (experimental) [master r12-4647-g3f861a5c8fd] (GCC)
[508] %
[508] % gcctk -O2 small.c; ./a.out
[509] %
[509] % gcctk -O3 small.c
[510] % ./a.out
Aborted
[511] %
[511] % cat small.c
int a, f = 1, h, l, m = 1, o, r = 4, q, s, x, e, aa, ab, ac, *ad, ae = 5, **y,
**af, ag, ah, ai, aj;
static int c[6], d, g[6][5], n, *v = &s, ak;
volatile int p;
const volatile int al;
static volatile int t, u, w = 3, z, am, an;
static int ao();
void ap();
static void aq() {
int ar[4] = {6, 6, 6, 6}, as[1], i, j;
as[0] = 0;
if (m) {
int at[11] = {4, 4, 6, 5, 7, 0, 7, 6, 7, 6, 6}, *au, *av[7], k;
au = (int*) &au;
for (i = 0; i < 1; i++)
for (j = 0; j < 1; j++)
for (k = 0; k < 7; k++) {
(t || n) && u;
av[k] = 0;
}
y = av;
while (o) {
int *b[2] = {as, ar};
*af = at;
}
m = 0;
}
}
inline void ap() {
for (; l <= 4; l++) {
*v = 0;
aq();
if (a)
break;
for (; q; q++)
;
}
}
int ao() {
int be = 0, j;
if (n)
aa = d = 0;
l = 0;
for (; be < 2; be++) {
int bf[7][2];
for (ai = 0; ai < 7; ai++)
for (j = 0; j < 2; j++)
bf[ai][j] = 5;
if (be) {
for (; h >= 0; h--) {
while (z >= w) {
ap();
*ad = 0;
}
ap();
}
return bf[3][0];
}
if (bf[3][0])
continue;
while (1)
;
}
return 0;
}
static void aw() {
for (; ah; ah++) {
p = 0;
p = 0;
}
int ax = ~e;
L1:
e = a = 0;
L2:
if (!r)
goto L3;
if (!ax)
goto L2;
if (d)
goto L1;
if (!ae)
goto L1;
if (w && x <= 808 && f)
ag = ao();
g[0][4] = ag;
if (a) {
int bd;
n++;
while (n)
for (bd = 0; bd < 7; bd++) {
am;
am;
am;
am;
d = c[d ^ am];
}
} else {
L3:
an;
for (; ak; ak++) {
int bc = 7;
for (; bc >= 0; bc--) {
al;
al;
d = f && an;
an;
}
}
}
}
int main() {
int k;
for (; aj < 6; aj++)
c[0] = aj;
aw();
for (aj = 0; aj < 6; aj++)
for (k = 0; k < 5; k++)
d = c[d ^ g[aj][k]];
if (d != 5)
__builtin_abort();
return 0;
}
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] wrong code at -O3 on x86_64-linux-gnu
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
@ 2022-06-24 8:06 ` zhendong.su at inf dot ethz.ch
2022-06-24 8:28 ` [Bug tree-optimization/106073] [12/13 Regression] " pinskia at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: zhendong.su at inf dot ethz.ch @ 2022-06-24 8:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
--- Comment #1 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
Compiler Explorer: https://godbolt.org/z/o3jq85vYK
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2022-06-24 8:06 ` [Bug tree-optimization/106073] " zhendong.su at inf dot ethz.ch
@ 2022-06-24 8:28 ` pinskia at gcc dot gnu.org
2022-06-24 10:33 ` rguenth at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-06-24 8:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Keywords| |needs-bisection, wrong-code
Last reconfirmed| |2022-06-24
Summary|wrong code at -O3 on |[12/13 Regression] wrong
|x86_64-linux-gnu |code at -O3 on
| |x86_64-linux-gnu
Target Milestone|--- |12.2
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
When we remove:
au = (int*) &au;
The testcase works; au is otherwise unused.
I noticed that the major different between with and without that line was a
loop was unrolled and then SLP vectorized.
I have not looked into it any further really.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2022-06-24 8:06 ` [Bug tree-optimization/106073] " zhendong.su at inf dot ethz.ch
2022-06-24 8:28 ` [Bug tree-optimization/106073] [12/13 Regression] " pinskia at gcc dot gnu.org
@ 2022-06-24 10:33 ` rguenth at gcc dot gnu.org
2022-06-27 8:57 ` [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669 marxin at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-06-24 10:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
Version|unknown |12.1.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (2 preceding siblings ...)
2022-06-24 10:33 ` rguenth at gcc dot gnu.org
@ 2022-06-27 8:57 ` marxin at gcc dot gnu.org
2022-07-29 12:08 ` rguenth at gcc dot gnu.org
2023-05-08 12:24 ` [Bug tree-optimization/106073] [12/13/14 " rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: marxin at gcc dot gnu.org @ 2022-06-27 8:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |aldyh at gcc dot gnu.org,
| |amacleod at redhat dot com,
| |marxin at gcc dot gnu.org
Summary|[12/13 Regression] wrong |[12/13 Regression] wrong
|code at -O3 on |code at -O3 on
|x86_64-linux-gnu |x86_64-linux-gnu since
| |r12-3903-g0288527f47cec669
--- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r12-3903-g0288527f47cec669.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (3 preceding siblings ...)
2022-06-27 8:57 ` [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669 marxin at gcc dot gnu.org
@ 2022-07-29 12:08 ` rguenth at gcc dot gnu.org
2023-05-08 12:24 ` [Bug tree-optimization/106073] [12/13/14 " rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-07-29 12:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=90348
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Options reduced to
-O2 -funroll-loops -fno-tree-vectorize -fdisable-tree-cunrolli
-fdbg-cnt=gimple_unroll:3-6:8-8
in particular reducing late unrolling more will no longer reproduce the issue.
Disabling all threading after cunroll still reproduces the issue, thus
adding
-fdisable-tree-thread2 -fdisable-tree-threadfull2 -fdisable-tree-vrp2
-fdisable-tree-dom3
disabling IVOPTs hides the issue. Making all functions but main static also
still reproduces the issue (so there's just one function left for late opts).
With that simplification
-O2 -funroll-loops -fno-tree-vectorize -fdisable-tree-cunrolli
-fdbg-cnt=gimple_unroll:3-6:8-8 -fdisable-tree-thread2
-fdisable-tree-threadfull2 -fdisable-tree-dom3 -fno-tree-vrp -fdump-tree-all
-fdbg-cnt=ivopts_loop:13-13:15-15
reproduces it, less IVOPTs does not.
So one difference triggering the issue is (good vs bad in .optimized):
@@ -328,20 +326,21 @@
<bb 19> [local count: 60532]:
l = 0;
+ ivtmp.151_212 = (unsigned long) &bf;
+ _507 = ivtmp.151_212 + 56;
<bb 20> [local count: 412224]:
- # ai_lsm.108_510 = PHI <d.13_27(19), _516(21)>
- # ivtmp_511 = PHI <8(19), ivtmp_512(21)>
- ivtmp_512 = ivtmp_511 - 1;
- if (ivtmp_512 != 0)
+ # ivtmp.151_254 = PHI <ivtmp.151_212(19), ivtmp.151_380(21)>
+ if (ivtmp.151_254 != _507)
goto <bb 21>; [89.00%]
else
goto <bb 22>; [11.00%]
<bb 21> [local count: 366880]:
- bf[ai_lsm.108_510][0] = 5;
- bf[ai_lsm.108_510][1] = 5;
- _516 = ai_lsm.108_510 + 1;
+ _506 = (void *) ivtmp.151_254;
+ MEM[(int *)_506] = 5;
+ MEM[(int *)_506 + 4B] = 5;
+ ivtmp.151_380 = ivtmp.151_254 + 8;
goto <bb 20>; [100.00%]
<bb 22> [local count: 45347]:
@@ -353,8 +352,6 @@
<bb 23> [local count: 40253]:
bf ={v} {CLOBBER(eol)};
- ivtmp.132_498 = (unsigned long) &bf;
- _480 = ivtmp.132_498 + 56;
goto <bb 25>; [100.00%]
<bb 24> [local count: 325681]:
@@ -364,8 +361,8 @@
ivtmp.132_245 = ivtmp.132_383 + 8;
<bb 25> [local count: 365933]:
- # ivtmp.132_383 = PHI <ivtmp.132_498(23), ivtmp.132_245(24)>
- if (ivtmp.132_383 != _480)
+ # ivtmp.132_383 = PHI <ivtmp.151_212(23), ivtmp.132_245(24)>
+ if (ivtmp.151_254 != ivtmp.132_383)
goto <bb 24>; [89.00%]
else
goto <bb 26>; [11.00%]
that already causes quite some assembler changes :/
It's still not clear what goes wrong here.
Interestingly again, -fstack-reuse=none avoids the issue. So maybe the
above hints at 'bf' being the issue here:
Partition 3: size 56 align 16
av au bf
Partition 5: size 56 align 16
av
Partition 1: size 44 align 16
at
Partition 2: size 8 align 8
au
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/106073] [12/13/14 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669
2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
` (4 preceding siblings ...)
2022-07-29 12:08 ` rguenth at gcc dot gnu.org
@ 2023-05-08 12:24 ` rguenth at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-05-08 12:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106073
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|12.3 |12.4
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 12.3 is being released, retargeting bugs to GCC 12.4.
^ permalink raw reply [flat|nested] 7+ messages in thread
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2022-06-24 8:06 [Bug tree-optimization/106073] New: wrong code at -O3 on x86_64-linux-gnu zhendong.su at inf dot ethz.ch
2022-06-24 8:06 ` [Bug tree-optimization/106073] " zhendong.su at inf dot ethz.ch
2022-06-24 8:28 ` [Bug tree-optimization/106073] [12/13 Regression] " pinskia at gcc dot gnu.org
2022-06-24 10:33 ` rguenth at gcc dot gnu.org
2022-06-27 8:57 ` [Bug tree-optimization/106073] [12/13 Regression] wrong code at -O3 on x86_64-linux-gnu since r12-3903-g0288527f47cec669 marxin at gcc dot gnu.org
2022-07-29 12:08 ` rguenth at gcc dot gnu.org
2023-05-08 12:24 ` [Bug tree-optimization/106073] [12/13/14 " rguenth at gcc dot gnu.org
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