https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108657
--- Comment #11 from Mikael Pettersson <mikpelinux at gmail dot com> --- Bisected on x86_64-linux-gnu: dc477ffb4aba21e9cf47de22a4df6f2b23849505 is the first bad commit commit dc477ffb4aba21e9cf47de22a4df6f2b23849505 Author: Richard Biener <rguent...@suse.de> Date: Thu Jul 21 10:13:46 2022 +0200 tree-optimization/106378 - DSE of LEN_STORE and MASK_STORE The following enhances DSE to handle LEN_STORE (optimally) and MASK_STORE (conservatively). PR tree-optimization/106378 * tree-ssa-dse.cc (initialize_ao_ref_for_dse): Handle LEN_STORE, add mode to initialize a may-def and handle MASK_STORE that way. (dse_optimize_stmt): Query may-defs. Handle internal functions LEN_STORE and MASK_STORE similar to how we handle memory builtins but without byte tracking.