https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86174
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |alias, missed-optimization
Target| |x86_64-*-*, i?86-*-*
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-06-18
CC| |rguenth at gcc dot gnu.org
Component|c |tree-optimization
Blocks| |53947
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. There's two things in the way - first we transform the
#pragma omp simd
for (int kk=0; kk<Sk; kk++) {
c[(i+ii)*p+k+kk] = C[ii][kk];
}
loop to memcpy (we could simply avoid that for force_vectorize loops as a
hack).
And if we avoid that, for example with -fno-tree-loop-distribute-patterns then
we fail to elide the stores to C[]. That happens because unrolling doesn't
preserve restrict info and when vectorization makes C addressable it doesn't
make restrict info reflect that it doesn't alias with anything.
We also do not have a late enough scalarization pass that would elide
the array - we'd rely on LIM/DSE here.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
