* [Bug tree-optimization/115669] [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
@ 2024-06-26 17:56 ` pinskia at gcc dot gnu.org
2024-06-26 21:12 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2024-06-26 17:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=115450
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Patrick O'Neill from comment #0)
> Found via fuzzer but Vineet bisected the 502.gcc_r benchmark breakage in
> spec2017 for the riscv target to the same commit so this _might_ be the same
> issue.
So the 502.gcc_r miscompile might be PR 115450 since that is for aarch64 SVE
even.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
2024-06-26 17:56 ` [Bug tree-optimization/115669] " pinskia at gcc dot gnu.org
@ 2024-06-26 21:12 ` pinskia at gcc dot gnu.org
2024-06-26 21:15 ` pinskia at gcc dot gnu.org
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From: pinskia at gcc dot gnu.org @ 2024-06-26 21:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |15.0
CC| |pinskia at gcc dot gnu.org
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
2024-06-26 17:56 ` [Bug tree-optimization/115669] " pinskia at gcc dot gnu.org
2024-06-26 21:12 ` pinskia at gcc dot gnu.org
@ 2024-06-26 21:15 ` pinskia at gcc dot gnu.org
2024-06-27 5:56 ` [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve " rguenth at gcc dot gnu.org
` (6 subsequent siblings)
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From: pinskia at gcc dot gnu.org @ 2024-06-26 21:15 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Target|riscv*-*-* |riscv*-*-*
| |aarch64-linux-gnu
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-06-26
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. Also reproduced for aarch64:
[apinski@xeond2 upstream-full-cross]$ ./install/bin/aarch64-linux-gnu-gcc -O3
-march=armv9-a+sve2 -fno-vect-cost-model t67.c -static -O0
[apinski@xeond2 upstream-full-cross]$ ./install-qemu/bin/qemu-aarch64 a.out
-10
[apinski@xeond2 upstream-full-cross]$ ./install/bin/aarch64-linux-gnu-gcc -O3
-march=armv9-a+sve2 -fno-vect-cost-model t67.c -static -fwrapv
[apinski@xeond2 upstream-full-cross]$ ./install-qemu/bin/qemu-aarch64 a.out
-16
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (2 preceding siblings ...)
2024-06-26 21:15 ` pinskia at gcc dot gnu.org
@ 2024-06-27 5:56 ` rguenth at gcc dot gnu.org
2024-06-27 6:30 ` rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2024-06-27 5:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Status|NEW |ASSIGNED
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
I will have a look.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (3 preceding siblings ...)
2024-06-27 5:56 ` [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve " rguenth at gcc dot gnu.org
@ 2024-06-27 6:30 ` rguenth at gcc dot gnu.org
2024-06-27 8:21 ` rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2024-06-27 6:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
I can reproduce on aarch64 with -O2 -march=armv8.3-a+sve -fno-vect-cost-model
-fwrapv. The reduction is
<bb 3> [local count: 955630224]:
# b_lsm.9_11 = PHI <_9(7), pretmp_42(6)>
_4 = *_3;
_5 = (signed int) _4;
b.2_7 = (signed int) b_lsm.9_11;
_15 = b.2_7 + -1;
_8 = _15 - _5;
_9 = (unsigned int) _8;
with -fwrapv and
# b_lsm.9_11 = PHI <_7(7), pretmp_40(6)>
_4 = *_3;
_5 = (unsigned int) _4;
_15 = b_lsm.9_11 + 4294967295;
_7 = _15 - _5;
without. So it seems the support for singed/unsigned converted reductions
is somehow broken. At least for VLA vectors.
The epilog does
# vect__9.22_59 = PHI <vect__9.22_58(3)>
_60 = (vector([4,4]) signed int) vect__9.22_59;
_61 = .REDUC_PLUS (_60);
I don't see where it goes wrong yet.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (4 preceding siblings ...)
2024-06-27 6:30 ` rguenth at gcc dot gnu.org
@ 2024-06-27 8:21 ` rguenth at gcc dot gnu.org
2024-06-27 8:32 ` rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2024-06-27 8:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think we use a wrong ELSE value:
vect_b.19_54 = VIEW_CONVERT_EXPR<vector([4,4]) signed int>(vect_b_lsm.18_53);
vect__15.20_56 = .COND_ADD (loop_mask_55, { -1, ... }, vect_b.19_54, { -1,
... });
^^^
vect__8.21_57 = .COND_SUB (loop_mask_55, vect__15.20_56, vect__5.17_51,
vect__15.20_56);
vect__9.22_58 = VIEW_CONVERT_EXPR<vector([4,4]) unsigned int>(vect__8.21_57);
I'll see how that happens. Possibly an operand order issue.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (5 preceding siblings ...)
2024-06-27 8:21 ` rguenth at gcc dot gnu.org
@ 2024-06-27 8:32 ` rguenth at gcc dot gnu.org
2024-06-27 12:11 ` cvs-commit at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2024-06-27 8:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, so the issue is the SLP child order is different than the scalar stmt
operand order and inconsistent with what we have recorded in reduc_idx.
Likely because we do
t.c:6:23: note: pre-sorted chains of plus_expr
plus_expr -1 plus_expr b.2_7 minus_expr _5
and that requires -fwrapv. I think this is a latent issue possibly triggerable
with a masked SLP reduction.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (6 preceding siblings ...)
2024-06-27 8:32 ` rguenth at gcc dot gnu.org
@ 2024-06-27 12:11 ` cvs-commit at gcc dot gnu.org
2024-06-27 12:12 ` rguenth at gcc dot gnu.org
2024-06-27 12:24 ` [Bug tree-optimization/115669] [12/13/14 " rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2024-06-27 12:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:7886830bb45c4f5dca0496d4deae9a45204d78f5
commit r15-1694-g7886830bb45c4f5dca0496d4deae9a45204d78f5
Author: Richard Biener <rguenther@suse.de>
Date: Thu Jun 27 11:26:08 2024 +0200
tree-optimization/115669 - fix SLP reduction association
The following avoids associating a reduction path as that might
get STMT_VINFO_REDUC_IDX out-of-sync with the SLP operand order.
This is a latent issue with SLP reductions but now easily exposed
as we're doing single-lane SLP reductions.
When we achieved SLP only we can move and update this meta-data.
PR tree-optimization/115669
* tree-vect-slp.cc (vect_build_slp_tree_2): Do not reassociate
chains that participate in a reduction.
* gcc.dg/vect/pr115669.c: New testcase.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [15 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (7 preceding siblings ...)
2024-06-27 12:11 ` cvs-commit at gcc dot gnu.org
@ 2024-06-27 12:12 ` rguenth at gcc dot gnu.org
2024-06-27 12:24 ` [Bug tree-optimization/115669] [12/13/14 " rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-06-27 12:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed (verified on aarch64).
^ permalink raw reply [flat|nested] 11+ messages in thread
* [Bug tree-optimization/115669] [12/13/14 Regression] rv64gcv/aarch64+sve -fwrapv miscompile since r15-1006-gd93353e6423
2024-06-26 17:45 [Bug tree-optimization/115669] New: [15 Regression] rv64gcv -fwrapv miscompile since r15-1006-gd93353e6423 patrick at rivosinc dot com
` (8 preceding siblings ...)
2024-06-27 12:12 ` rguenth at gcc dot gnu.org
@ 2024-06-27 12:24 ` rguenth at gcc dot gnu.org
9 siblings, 0 replies; 11+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-06-27 12:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115669
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |15.0
Status|RESOLVED |ASSIGNED
Priority|P3 |P2
Target Milestone|15.0 |12.5
Resolution|FIXED |---
Summary|[15 Regression] |[12/13/14 Regression]
|rv64gcv/aarch64+sve -fwrapv |rv64gcv/aarch64+sve -fwrapv
|miscompile since |miscompile since
|r15-1006-gd93353e6423 |r15-1006-gd93353e6423
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Let me re-open for backports, the issue is latent with a true SLP reduction.
Unfortunately getting a SLP reduction like the following to work seems
difficult.
int a = 10;
unsigned b, f;
long long c[100];
int main() {
long long *d = c;
for (short e = 0; e < a; e++)
{
b += ~(d ? d[2*e] : 0);
f += ~(d ? d[2*e+1] : 0);
}
__builtin_printf("%d %d\n", b, f);
}
^ permalink raw reply [flat|nested] 11+ messages in thread