[Bug tree-optimization/56531] New: SLP load permutations cannot share the load between and inside SLP instances

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56531



             Bug #: 56531

           Summary: SLP load permutations cannot share the load between

                    and inside SLP instances

    Classification: Unclassified

           Product: gcc

           Version: 4.8.0

            Status: UNCONFIRMED

          Keywords: missed-optimization, wrong-code

          Severity: normal

          Priority: P3

         Component: tree-optimization

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: rgue...@gcc.gnu.org

            Blocks: 56270





SLP load permutations are currently severely restricted (only 000..111... is

supported) and they do not share the load (ICE before the fix for PR56270).

This is because vinfo->vectorized_stmt of the underlying group load includes

the very first permutation of the very first SLP instance.



The fix here is to make vinfo->vectorized_stmt the group load itself and

hook in the permutation only on the consumer.