[Bug tree-optimization/81354] [5/6 Regression] Segmentation fault in SSA Strength Reduction using -O3

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81354

--- Comment #6 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Hm, the symptom looks very much like another issue I've been looking at on
trunk.  There may be an issue with the statement->candidate mapping hash table
that's responsible for both.  It appears to be a somewhat rare issue involving
chains of phis where one of the "more recent" phis is receiving the same value
from at least two different incoming edges, but I don't yet have a complete
answer.