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* [Bug tree-optimization/106217] New: [11/12/13 Regression] sinking of loads prevents vectorization
@ 2022-07-06 18:19 tnfchris at gcc dot gnu.org
2022-07-06 20:34 ` [Bug tree-optimization/106217] " pinskia at gcc dot gnu.org
2022-07-06 21:17 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: tnfchris at gcc dot gnu.org @ 2022-07-06 18:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106217
Bug ID: 106217
Summary: [11/12/13 Regression] sinking of loads prevents
vectorization
Product: gcc
Version: 11.3.1
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: tnfchris at gcc dot gnu.org
Target Milestone: ---
The following example
void f(int n, float * __restrict x, float *mass, float max, float &ax)
{
float lax = 0.0f;
for (int i = 0; i < n; ++i) {
float f = x[i] * mass[i];
lax += x[i] >= max ? 0 : f * x[i];
}
ax += lax;
return;
}
vectorizes with GCC 10 with -Ofast but fails starting with GCC 11.
The difference is that in the sink1 pass we now sink the unconditional load of
mass[i] into the conditional.
Sinking # VUSE <.MEM_14(D)>
_7 = *_6;
from bb 3 to bb 4
Sinking _6 = mass_18(D) + _2;
from bb 3 to bb 4
consequently this causes if-convert to no longer be able to if-convert the loop
because the load is now conditional, and we only accept unconditional loads in
ifcvt_memrefs_wont_trap.
-------------------------
_6 = mass_18(D) + _2;
-------------------------
_7 = *_6;
tree could trap...
perhaps during the sinking we should mark the load as non-trapping? as it was
originally unconditional anyway.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/106217] [11/12/13 Regression] sinking of loads prevents vectorization
2022-07-06 18:19 [Bug tree-optimization/106217] New: [11/12/13 Regression] sinking of loads prevents vectorization tnfchris at gcc dot gnu.org
@ 2022-07-06 20:34 ` pinskia at gcc dot gnu.org
2022-07-06 21:17 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-07-06 20:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106217
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-07-06
Target Milestone|--- |11.4
CC| |pinskia at gcc dot gnu.org
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
Note changing mass[i] to mass[0] will vectorize the loop still as LIM is done
before the first sinking pass (this changed with r7-879-g43c0068e60ad15) and we
don't sink loads into loops.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/106217] [11/12/13 Regression] sinking of loads prevents vectorization
2022-07-06 18:19 [Bug tree-optimization/106217] New: [11/12/13 Regression] sinking of loads prevents vectorization tnfchris at gcc dot gnu.org
2022-07-06 20:34 ` [Bug tree-optimization/106217] " pinskia at gcc dot gnu.org
@ 2022-07-06 21:17 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-07-06 21:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106217
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Dup of bug 95084.
*** This bug has been marked as a duplicate of bug 95084 ***
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-07-06 18:19 [Bug tree-optimization/106217] New: [11/12/13 Regression] sinking of loads prevents vectorization tnfchris at gcc dot gnu.org
2022-07-06 20:34 ` [Bug tree-optimization/106217] " pinskia at gcc dot gnu.org
2022-07-06 21:17 ` pinskia at gcc dot gnu.org
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