On Wed, Jun 29, 2011 at 4:19 AM, Richard Guenther <rguent...@suse.de> wrote: > > The following patch makes us handle invariant loads during vectorization. > Dependence analysis currently isn't clever enough to disambiguate them > thus we insert versioning-for-alias checks. For the testcase hoisting > the load is still always possible though, and for a read-after-write > dependence it would be possible for the vectorized loop copy as the > may-aliasing write is varying by the scalar variable size. > > The existing code for vectorizing invariant accesses looks very > suspicious - it generates a vector load at the scalar address > to then just extract the first vector element. Huh. IMHO this > can be simplified as done, by just re-using the scalar load result. > But maybe this code was supposed to deal with something entirely > different? > > This patch gives a 33% speedup to the phoronix himeno testcase > if you bump the maximum alias versioning checks we want to insert. > > I'm currently re-bootstrapping & testing this but an earlier version > was ok on x86_64-unknown-linux-gnu. > > 2011-06-29 Richard Guenther <rguent...@suse.de> > > PR tree-optimization/46787 > * tree-data-ref.c (dr_address_invariant_p): Remove. > (find_data_references_in_stmt): Invariant accesses are ok now. > * tree-vect-stmts.c (vectorizable_load): Handle invariant > loads. > * tree-vect-data-refs.c (vect_analyze_data_ref_access): Allow > invariant loads. > > * gcc.dg/vect/vect-121.c: New testcase. >
This also caused: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49628 -- H.J.
