* [Bug tree-optimization/98516] Wrong code generated by tree vectorizer
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
@ 2021-01-04 18:59 ` martin@mpa-garching.mpg.de
2021-01-05 10:30 ` [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853 marxin at gcc dot gnu.org
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From: martin@mpa-garching.mpg.de @ 2021-01-04 18:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #1 from Martin Reinecke <martin@mpa-garching.mpg.de> ---
Minimal set of flags to trigger the problem seems to be
g++ -std=c++17 -O1 -ftree-vectorize -fno-signed-zeros bug.cc
^ permalink raw reply [flat|nested] 11+ messages in thread* [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
2021-01-04 18:59 ` [Bug tree-optimization/98516] " martin@mpa-garching.mpg.de
@ 2021-01-05 10:30 ` marxin at gcc dot gnu.org
2021-01-05 10:37 ` marxin at gcc dot gnu.org
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From: marxin at gcc dot gnu.org @ 2021-01-05 10:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2021-01-05
Status|UNCONFIRMED |NEW
Summary|Wrong code generated by |[11 Regression] Wrong code
|tree vectorizer |generated by tree
| |vectorizer since
| |r11-3823-g126ed72b9f48f853
CC| |marxin at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Thanks, started with r11-3823-g126ed72b9f48f853.
^ permalink raw reply [flat|nested] 11+ messages in thread* [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
2021-01-04 18:59 ` [Bug tree-optimization/98516] " martin@mpa-garching.mpg.de
2021-01-05 10:30 ` [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853 marxin at gcc dot gnu.org
@ 2021-01-05 10:37 ` marxin at gcc dot gnu.org
2021-01-05 11:28 ` rguenth at gcc dot gnu.org
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From: marxin at gcc dot gnu.org @ 2021-01-05 10:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> ---
Minimal options:
g++ pr98516.c -std=c++17 -O1 -ftree-slp-vectorize -fno-signed-zeros
-fdbg-cnt=vect_slp:2
while this one is fine:
g++ pr98516.c -std=c++17 -O1 -ftree-slp-vectorize -fno-signed-zeros
-fdbg-cnt=vect_slp:1
^ permalink raw reply [flat|nested] 11+ messages in thread* [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 10:37 ` marxin at gcc dot gnu.org
@ 2021-01-05 11:28 ` rguenth at gcc dot gnu.org
2021-01-05 14:33 ` rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2021-01-05 11:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Priority|P3 |P1
Target Milestone|--- |11.0
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Mine.
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2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
` (3 preceding siblings ...)
2021-01-05 11:28 ` rguenth at gcc dot gnu.org
@ 2021-01-05 14:33 ` rguenth at gcc dot gnu.org
2021-01-05 14:41 ` rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2021-01-05 14:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Meh, it's very hard to spot the actual problem :/
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index d8a2ceb0fa1..dee360307d0 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -5058,8 +5059,7 @@ vect_slp_region (vec<basic_block> bbs,
vec<data_reference_p> datarefs,
bb_vinfo->shared->check_datarefs ();
bb_vinfo->vector_mode = next_vector_mode;
- if (vect_slp_analyze_bb_1 (bb_vinfo, n_stmts, fatal, dataref_groups)
- && dbg_cnt (vect_slp))
+ if (vect_slp_analyze_bb_1 (bb_vinfo, n_stmts, fatal, dataref_groups))
{
if (dump_enabled_p ())
{
@@ -5090,6 +5090,9 @@ vect_slp_region (vec<basic_block> bbs,
vec<data_reference_p> datarefs,
continue;
}
+ if (!dbg_cnt (vect_slp))
+ continue;
+
if (!vectorized && dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location,
"Basic block will be vectorized "
helps to narrow down the bogus vectorization, -fdbg-cnt=vect_slp:2:2 triggers
it but the SLP region is quite big still.
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index d8a2ceb0fa1..dee360307d0 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -3310,6 +3310,7 @@ vect_optimize_slp (vec_info *vinfo)
auto_vec<int> leafs;
vect_slp_build_vertices (vinfo, vertices, leafs);
+#if 0
struct graph *slpg = new_graph (vertices.length ());
FOR_EACH_VEC_ELT (vertices, i, node)
{
@@ -3619,7 +3620,7 @@ vect_optimize_slp (vec_info *vinfo)
while (!perms.is_empty ())
perms.pop ().release ();
free_graph (slpg);
-
+#endif
/* Now elide load permutations that are not necessary. */
for (i = 0; i < leafs.length (); ++i)
avoids the miscompilation. The key transform we're doing is
eliding load permutations that swap real/imag parts and instead
adjust the lane permutation of a blend created for plus/minus ops
which is where the bug is I think. We're changing
t.C:80:7: note: node 0x4204018 (max_nunits=2, refcnt=1)
t.C:80:7: note: op: VEC_PERM_EXPR
t.C:80:7: note: stmt 0 _37 = _35 - _36;
t.C:80:7: note: stmt 1 _34 = _32 + _33;
t.C:80:7: note: lane permutation { 0[0] 1[1] }
t.C:80:7: note: children 0x42045f0 0x4204678
to
t.C:80:7: note: node 0x4207018 (max_nunits=2, refcnt=1)
t.C:80:7: note: op: VEC_PERM_EXPR
t.C:80:7: note: stmt 0 _37 = _35 - _36;
t.C:80:7: note: stmt 1 _34 = _32 + _33;
t.C:80:7: note: lane permutation { 1[1] 0[0] }
t.C:80:7: note: children 0x42075f0 0x4207678
but that's not what is necessary - we have permuted the lanes of the
children but permuting the blend will not materialize properly
instead we need to generate { 0[1] 1[0] } I think.
I'm trying to create a simpler C testcase now.
^ permalink raw reply [flat|nested] 11+ messages in thread* [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 14:33 ` rguenth at gcc dot gnu.org
@ 2021-01-05 14:41 ` rguenth at gcc dot gnu.org
2021-01-05 16:41 ` cvs-commit at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2021-01-05 14:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
/* { dg-do run } */
double a[4], b[2];
void __attribute__((noipa))
foo ()
{
double a0 = a[0];
double a1 = a[1];
double a2 = a[2];
double a3 = a[3];
b[0] = a1 - a3;
b[1] = a0 + a2;
}
int main()
{
a[0] = 1.;
a[1] = 2.;
a[2] = 3.;
a[3] = 4.;
foo ();
if (b[0] != -2 || b[1] != 4)
__builtin_abort ();
return 0;
}
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2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 14:41 ` rguenth at gcc dot gnu.org
@ 2021-01-05 16:41 ` cvs-commit at gcc dot gnu.org
2021-01-05 16:41 ` rguenth at gcc dot gnu.org
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From: cvs-commit at gcc dot gnu.org @ 2021-01-05 16:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #7 from CVS 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:33a63257701c8d94ee375e32ff1837c989d8ded6
commit r11-6478-g33a63257701c8d94ee375e32ff1837c989d8ded6
Author: Richard Biener <rguenther@suse.de>
Date: Tue Jan 5 16:17:15 2021 +0100
tree-optimization/98516 - fix SLP permute opt materialization
When materializing on a VEC_PERM node we have to permute the
incoming vectors, not the outgoing one.
2021-01-05 Richard Biener <rguenther@suse.de>
PR tree-optimization/98516
* tree-vect-slp.c (vect_optimize_slp): Permute the incoming
lanes when materializing on a VEC_PERM node.
(vectorizable_slp_permutation): Dump the permute properly.
* gcc.dg/vect/bb-slp-pr98516-1.c: New testcase.
* gcc.dg/vect/bb-slp-pr98516-2.c: Likewise.
^ permalink raw reply [flat|nested] 11+ messages in thread* [Bug tree-optimization/98516] [11 Regression] Wrong code generated by tree vectorizer since r11-3823-g126ed72b9f48f853
2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 16:41 ` cvs-commit at gcc dot gnu.org
@ 2021-01-05 16:41 ` rguenth at gcc dot gnu.org
2021-01-05 18:06 ` martin@mpa-garching.mpg.de
2021-01-06 7:41 ` rguenther at suse dot de
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From: rguenth at gcc dot gnu.org @ 2021-01-05 16:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
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2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 16:41 ` rguenth at gcc dot gnu.org
@ 2021-01-05 18:06 ` martin@mpa-garching.mpg.de
2021-01-06 7:41 ` rguenther at suse dot de
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From: martin@mpa-garching.mpg.de @ 2021-01-05 18:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #9 from Martin Reinecke <martin@mpa-garching.mpg.de> ---
Thanks, this fixes the reduced test case for me as well!
Unfortunately there seems to be more where this one came from, since my
comprehensive test suite still fails ... I'll try to produce test cases and
open another bug report.
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2021-01-04 17:01 [Bug tree-optimization/98516] New: Wrong code generated by tree vectorizer martin@mpa-garching.mpg.de
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2021-01-05 18:06 ` martin@mpa-garching.mpg.de
@ 2021-01-06 7:41 ` rguenther at suse dot de
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From: rguenther at suse dot de @ 2021-01-06 7:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
--- Comment #10 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 5 Jan 2021, martin@mpa-garching.mpg.de wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98516
>
> --- Comment #9 from Martin Reinecke <martin@mpa-garching.mpg.de> ---
> Thanks, this fixes the reduced test case for me as well!
>
> Unfortunately there seems to be more where this one came from, since my
> comprehensive test suite still fails ... I'll try to produce test cases and
> open another bug report.
Thanks, that's appreciated!
^ permalink raw reply [flat|nested] 11+ messages in thread