https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101340
Bug ID: 101340
Summary: SLP discovery via vect_slp_linearize_chain is
imperfect
Product: gcc
Version: 12.0
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: ---
For polyhedron capacita we have the hot fourir routine which with -ffast-math
suffers from reassoc perturbing the SLP lanes to not match. SLP discovery
reassociation could help here but it's limited by the single_use check.
For loop vect we could allow uses outside of the chain but of course we
do not want to expand multi-uses inside. That doesn't fit well with the
simple worklist approach but would need sth more elaborate.
