https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111133
Bug ID: 111133
Summary: SLP of scatters not implemented
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
There is no scatter support for (single-lane) SLP. For example
#define N 16
void __attribute__((noipa))
f (float *restrict y, float *restrict x, int *restrict indices)
{
for (int i = 0; i < N; ++i)
{
x[indices[i * 2]] = y[i * 2] + 1;
x[indices[i * 2 + 1]] = y[i * 2 + 1] + 2;
}
}
doesn't vectorize. Note this is also due to
t.c:6:21: note: === vect_analyze_data_ref_dependences ===
t.c:8:25: missed: possible alias involving gather/scatter between *_10 and
*_20
t.c:6:21: missed: bad data dependence.
but with SLP scatters guarantee left-to-right commit so that shouldn't
be an issue there and also shows why SLP is even required for this
to vectorize.
