https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106378
Bug ID: 106378
Summary: Miss to handle ifn .LEN_STORE in DSE
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: linkw at gcc dot gnu.org
CC: rguenth at gcc dot gnu.org, rsandifo at gcc dot gnu.org,
segher at gcc dot gnu.org
Depends on: 106365
Target Milestone: ---
Target: powerpc*-linux-gnu
+++ This bug was initially created as a clone of Bug #106365 +++
In PR106365, Richi has fixed the miss optimization on {MASK/LEN}_STORE by
teaching VN about these IFNs. But it further exposes one miss optimization in
DSE for LEN_STORE.
With the option -O3 -mcpu=power10 -fno-vect-cost-model, check the optimized
dumpings.
--------------
for the case gcc/testsuite/gcc.dg/tree-ssa/pr84512.c, we expect to get:
int foo ()
{
<bb 2> [local count: 97603129]:
return 285;
}
but it gets now:
int foo ()
{
int a[10];
<bb 2> [local count: 97603129]:
.LEN_STORE (&MEM <int[10]> [(void *)&a + 32B], 128B, 8, { 64, 0, 0, 0, 81, 0,
0, 0, 100, 0, 0, 0, 121, 0, 0, 0 }, 0);
a ={v} {CLOBBER(eol)};
return 285;
}
--------------
for the case Richi posted:
int __attribute__((noinline,noclone))
foo ()
{
int out[10];
int i;
for (i = 0; i < 10; ++i)
{
out[i] = i;
}
return out[9];
}
it gets:
__attribute__((noclone, noinline))
int foo ()
{
int out[10];
<bb 2> [local count: 97603129]:
.LEN_STORE (&MEM <int[10]> [(void *)&out + 32B], 128B, 8, { 8, 0, 0, 0, 9, 0,
0, 0, 10, 0, 0, 0, 11, 0, 0, 0 }, 0);
out ={v} {CLOBBER(eol)};
return 9;
}
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106365
[Bug 106365] Miss to handle ifn .LEN_STORE in FRE
