https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114855
--- Comment #42 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:f9dfe8dea31bf5c56aa7798a0905707faf9e7ec4 commit r15-3818-gf9dfe8dea31bf5c56aa7798a0905707faf9e7ec4 Author: Richard Biener <rguent...@suse.de> Date: Mon Sep 23 15:41:14 2024 +0200 tree-optimization/114855 - high update_ssa time Part of the problem in PR114855 is high update_ssa time. When one fixes the backward jump threading issue tree SSA incremental is at 439.91s ( 26%), mostly doing bitmap element searches for blocks_with_phis_to_rewrite. The following turns that bitmap to tree view noticing the two-dimensional vector of PHIs it guards is excessive compared to what we actually save with it - walking all PHI nodes in a block, something we already do once to initialize stmt flags. So instead of optimizing that walk we use the stmt flag, saving allocations and global state that lives throughout the whole compilation. This reduces the tree SSA incremental time to 203.13 ( 14%) The array was added in r0-74758-g2ce798794df8e1 when we still possibly had gazillion virtual operands for PR26830, I checked the testcase still behaves OK. PR tree-optimization/114855 * tree-into-ssa.cc (phis_to_rewrite): Remove global var. (mark_phi_for_rewrite): Simplify. (rewrite_update_phi_arguments): Walk all PHIs, process those satisfying rewrite_uses_p. (delete_update_ssa): Simplify. (update_ssa): Likewise. Switch blocks_with_phis_to_rewrite to tree view.
