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* [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
@ 2022-03-11 14:18 acoplan at gcc dot gnu.org
2022-03-11 14:21 ` [Bug target/104882] " acoplan at gcc dot gnu.org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: acoplan at gcc dot gnu.org @ 2022-03-11 14:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
Bug ID: 104882
Summary: [12 Regression] MVE: Wrong code at -O2 since
r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: acoplan at gcc dot gnu.org
Target Milestone: ---
Created attachment 52608
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52608&action=edit
broken assembly output
The following code:
int i;
char src[1072];
char dst[72];
int main() {
for (i = 0; i < 128; i++)
src[i] = i;
__builtin_memcpy(dst, src, 7);
for (i = 0; i < 7; i++)
if (dst[i] != i)
__builtin_abort();
}
is miscompiled at -O2 since vectorization was enabled at -O2. With -O2
-ftree-vectorize, it is miscompiled earlier, starting with:
commit 046a3beb1673bf4a61c131373b6a5e84158e92bf
Author: Christophe Lyon <christophe.lyon@linaro.org>
Date: Thu Jun 3 15:35:50 2021
arm: Auto-vectorization for MVE: add pack/unpack patterns
It looks like we do some dubious packing of vector elements before storing to
src. If I change the last loop to print the elements of dst instead, I see:
0 8 4 12 1 9 5
it should of course print:
0 1 2 3 4 5 6.
The broken code is attached. The testcase above was reduced from
gcc/testsuite/gcc.c-torture/execute/memcpy-1.c.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
@ 2022-03-11 14:21 ` acoplan at gcc dot gnu.org
2022-03-14 5:39 ` pinskia at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: acoplan at gcc dot gnu.org @ 2022-03-11 14:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
--- Comment #1 from Alex Coplan <acoplan at gcc dot gnu.org> ---
For completeness, the options -march=armv8.1-m.main+mve -mfloat-abi=hard -O2
-ftree-vectorize are required to reproduce.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
2022-03-11 14:21 ` [Bug target/104882] " acoplan at gcc dot gnu.org
@ 2022-03-14 5:39 ` pinskia at gcc dot gnu.org
2022-03-14 7:50 ` rguenth at gcc dot gnu.org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-03-14 5:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
2022-03-11 14:21 ` [Bug target/104882] " acoplan at gcc dot gnu.org
2022-03-14 5:39 ` pinskia at gcc dot gnu.org
@ 2022-03-14 7:50 ` rguenth at gcc dot gnu.org
2022-03-16 14:40 ` clyon at gcc dot gnu.org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-03-14 7:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
` (2 preceding siblings ...)
2022-03-14 7:50 ` rguenth at gcc dot gnu.org
@ 2022-03-16 14:40 ` clyon at gcc dot gnu.org
2022-03-22 14:37 ` clyon at gcc dot gnu.org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: clyon at gcc dot gnu.org @ 2022-03-16 14:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
Christophe Lyon <clyon at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2022-03-16
--- Comment #2 from Christophe Lyon <clyon at gcc dot gnu.org> ---
My understanding is that MVE's vmovn instructions do not work like Neon's.
If q0 = { 0x33333333, 0x22222222, 0x11111111, 0 } ( 4x32 bits)
q1 = { 0x77777777, 0x66666666, 0x55555555, 0x44444444 }
With Neon:
vmovn.i32 d4, q0 gives:
d4 = { 0x3333, 0x2222, 0x1111, 0 } (4x16 bits)
vmovn.i32 d5, q1 gives:
d5 = { 0x7777, 0x6666, 0x5555, 0x4444 }
thus q2 = { 0x7777, 0x6666, 0x5555, 0x4444, 0x3333, 0x2222, 0x1111, 0 }
But with MVE:
vmovnb.i32 q2, q0 gives:
q2 = { 0x????, 0x3333, 0x????, 0x2222, 0x????, 0x1111, 0x????, 0 } (8x16 bits,
only the bottom bits of each 32 bits element are updated)
vmovnt.i32 q2, q1 then gives:
q2 = { 0x7777, 0x3333, 0x6666, 0x2222, 0x5555, 0x1111, 0x4444, 0 } (only the
top bits are updated)
This means that the input should be shuffled before using MVE's vmovn[bt] to
have
q0 = { 0x66666666, 0x44444444, 0x22222222, 0 }
q1 = { 0x77777777, 0x55555555, 0x33333333, 0x11111111 }
since MVE's vmovn do not seem to naturally map to GCC's vec_pack_trunc
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
` (3 preceding siblings ...)
2022-03-16 14:40 ` clyon at gcc dot gnu.org
@ 2022-03-22 14:37 ` clyon at gcc dot gnu.org
2022-03-25 17:27 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: clyon at gcc dot gnu.org @ 2022-03-22 14:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
--- Comment #3 from Christophe Lyon <clyon at gcc dot gnu.org> ---
Revert patch posted:
https://gcc.gnu.org/pipermail/gcc-patches/2022-March/592136.html
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
` (4 preceding siblings ...)
2022-03-22 14:37 ` clyon at gcc dot gnu.org
@ 2022-03-25 17:27 ` cvs-commit at gcc dot gnu.org
2022-03-25 17:30 ` clyon at gcc dot gnu.org
2023-03-03 19:10 ` cvs-commit at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-25 17:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Christophe Lyon <clyon@gcc.gnu.org>:
https://gcc.gnu.org/g:3ab5c8cd03d92bf4ec41e351820349d92fbc40c4
commit r12-7818-g3ab5c8cd03d92bf4ec41e351820349d92fbc40c4
Author: Christophe Lyon <christophe.lyon@arm.com>
Date: Fri Mar 18 08:30:00 2022 +0000
arm: Revert Auto-vectorization for MVE: add pack/unpack patterns PR
target/104882
This reverts commit r12-1434-g046a3beb1673bf to fix PR target/104882.
As discussed in the PR, it turns out that the MVE ISA has no natural
mapping with GCC's vec_pack_trunc / vec_unpack standard patterns, unlike
Neon or SVE for instance.
This patch also adds the executable testcase provided in the PR.
This test passes at -O3 because the generated code does not need
to use the pack/unpack patterns, hence the use of -O2 which now
triggers vectorization since a few months ago.
2022-03-18 Christophe Lyon <christohe.lyon@arm.com>
PR target/104882
Revert
2021-06-11 Christophe Lyon <christophe.lyon@linaro.org>
gcc/
* config/arm/mve.md (mve_vec_unpack<US>_lo_<mode>): Delete.
(mve_vec_unpack<US>_hi_<mode>): Delete.
(@mve_vec_pack_trunc_lo_<mode>): Delete.
(mve_vmovntq_<supf><mode>): Remove '@' prefix.
* config/arm/neon.md (vec_unpack<US>_hi_<mode>): Move back
from vec-common.md.
(vec_unpack<US>_lo_<mode>): Likewise.
(vec_pack_trunc_<mode>): Rename from
neon_quad_vec_pack_trunc_<mode>.
* config/arm/vec-common.md (vec_unpack<US>_hi_<mode>): Delete.
(vec_unpack<US>_lo_<mode>): Delete.
(vec_pack_trunc_<mode>): Delete.
PR target/104882
gcc/testsuite/
* gcc.target/arm/simd/mve-vclz.c: Update expected results.
* gcc.target/arm/simd/mve-vshl.c: Likewise.
* gcc.target/arm/simd/mve-vec-pack.c: Delete.
* gcc.target/arm/simd/mve-vec-unpack.c: Delete.
* gcc.target/arm/simd/pr104882.c: New test.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
` (5 preceding siblings ...)
2022-03-25 17:27 ` cvs-commit at gcc dot gnu.org
@ 2022-03-25 17:30 ` clyon at gcc dot gnu.org
2023-03-03 19:10 ` cvs-commit at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: clyon at gcc dot gnu.org @ 2022-03-25 17:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
Christophe Lyon <clyon at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #5 from Christophe Lyon <clyon at gcc dot gnu.org> ---
Fixed on trunk.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug target/104882] [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf
2022-03-11 14:18 [Bug target/104882] New: [12 Regression] MVE: Wrong code at -O2 since r12-1434-g046a3beb1673bf4a61c131373b6a5e84158e92bf acoplan at gcc dot gnu.org
` (6 preceding siblings ...)
2022-03-25 17:30 ` clyon at gcc dot gnu.org
@ 2023-03-03 19:10 ` cvs-commit at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-03-03 19:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104882
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexandre Oliva <aoliva@gcc.gnu.org>:
https://gcc.gnu.org/g:220008eafaaed7433b1c18e394279391e885a138
commit r13-6455-g220008eafaaed7433b1c18e394279391e885a138
Author: Alexandre Oliva <oliva@adacore.com>
Date: Fri Mar 3 15:59:14 2023 -0300
[PR104882] [arm] require mve hw for mve run test
The pr104882.c test is an execution test, but arm_v8_1m_mve_ok only
tests for compile-time support. Add a requirement for mve hardware.
for gcc/testsuite/ChangeLog
PR target/104882
* gcc.target/arm/simd/pr104882.c: Require mve hardware.
^ permalink raw reply [flat|nested] 9+ messages in thread
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2022-03-11 14:21 ` [Bug target/104882] " acoplan at gcc dot gnu.org
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