re PR tree-optimization/87263 (ICE on valid code at -O1: verify_ssa failed)
2018-09-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/87263
* tree-ssa-sccvn.c (visit_phi): Revert some earlier changes.
(struct unwind_state): Add max_rpo field.
(do_rpo_vn): Allow up-to-date loop state to be used when not iterating.
Compute max_rpo, the max RPO number a block can be backwards reached
from. Re-write non-iterating mode to a RPO ordered worklist approach,
separating it from the iterating mode.