https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113910
--- Comment #19 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:db0f236aa1c30f703ff564960bd9f3dbd747ea7b commit r12-10490-gdb0f236aa1c30f703ff564960bd9f3dbd747ea7b Author: Richard Biener <rguent...@suse.de> Date: Wed Feb 14 12:33:13 2024 +0100 tree-optimization/113910 - huge compile time during PTA For the testcase in PR113910 we spend a lot of time in PTA comparing bitmaps for looking up equivalence class members. This points to the very weak bitmap_hash function which effectively hashes set and a subset of not set bits. The major problem with it is that it simply truncates the BITMAP_WORD sized intermediate hash to hashval_t which is unsigned int, effectively not hashing half of the bits. This reduces the compile-time for the testcase from tens of minutes to 42 seconds and PTA time from 99% to 46%. PR tree-optimization/113910 * bitmap.cc (bitmap_hash): Mix the full element "hash" to the hashval_t hash. (cherry picked from commit ad7a365aaccecd23ea287c7faaab9c7bd50b944a)
