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* [Bug tree-optimization/115363] New: Missing loop vectorization due to loop bound load not being pulled out
@ 2024-06-05 17:55 pinskia at gcc dot gnu.org
2024-06-06 6:48 ` [Bug tree-optimization/115363] " rguenth at gcc dot gnu.org
2024-06-07 14:19 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-06-05 17:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115363
Bug ID: 115363
Summary: Missing loop vectorization due to loop bound load not
being pulled out
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
struct out {
unsigned *array;
};
struct m{
void f(out *output);
void f1(out *output);
int size;
};
void m::f(out *output)
{
for (int k = 0; k < size; k++) {
output->array[k] += 1;
}
}
void m::f1(out *output)
{
int tmp = size;
for (int k = 0; k < size; k++) {
output->array[k] += 1;
}
}
```
We should be able to vectorize `m::f` but currently does not since this->size
might alias array[k].
But we could version the loop to pull out the this->size out of the loop and we
could vectorize the loop then.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/115363] Missing loop vectorization due to loop bound load not being pulled out
2024-06-05 17:55 [Bug tree-optimization/115363] New: Missing loop vectorization due to loop bound load not being pulled out pinskia at gcc dot gnu.org
@ 2024-06-06 6:48 ` rguenth at gcc dot gnu.org
2024-06-07 14:19 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-06-06 6:48 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115363
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2024-06-06
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Invariant motion doesn't do versioning for aliasing. But in fact once the
loop iterates array[k] can no longer alias this->size but this is difficult
to exploit (peeling the loop once would help).
I'm not sure we should start to version all those loops where the exit
condition depends on a not hoistable but invariant expression?
But maybe we can diagnose this so people can rewrite their code.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/115363] Missing loop vectorization due to loop bound load not being pulled out
2024-06-05 17:55 [Bug tree-optimization/115363] New: Missing loop vectorization due to loop bound load not being pulled out pinskia at gcc dot gnu.org
2024-06-06 6:48 ` [Bug tree-optimization/115363] " rguenth at gcc dot gnu.org
@ 2024-06-07 14:19 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-06-07 14:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115363
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> Invariant motion doesn't do versioning for aliasing. But in fact once the
> loop iterates array[k] can no longer alias this->size but this is difficult
> to exploit (peeling the loop once would help).
So I should mention that this was noticed from some code internally which is
optimized by LLVM's polly (graphite) infrastructure and yes it is an important
loop in this code.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-06-07 14:19 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2024-06-05 17:55 [Bug tree-optimization/115363] New: Missing loop vectorization due to loop bound load not being pulled out pinskia at gcc dot gnu.org
2024-06-06 6:48 ` [Bug tree-optimization/115363] " rguenth at gcc dot gnu.org
2024-06-07 14:19 ` pinskia at gcc dot gnu.org
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