https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103335
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jan Hubicka <hubi...@gcc.gnu.org>: https://gcc.gnu.org/g:6033b27eade9c31c0be50657094c89ef9068892d commit r12-5466-g6033b27eade9c31c0be50657094c89ef9068892d Author: Jan Hubicka <j...@suse.cz> Date: Tue Nov 23 10:55:56 2021 +0100 Improve bytewise DSE testcase modref-dse-4.c and modref-dse-5.c fails on some targets because they depend on store merging. What really happens is that without store merging we produce for kill_me combined write that is ao_ref with offset=0, size=32 and max_size=96. We have size != max_size becaue we do ont track the info that all 3 writes must happen in a group and conider case only some of them are done. This disables byte-wise DSE which checks that size == max_size. This is completely unnecesary for store being proved to be dead or load being checked to not read live bytes. It is only necessary for kill store that is used to prove that given store is dead. While looking into this I also noticed that we check that everything is byte aligned. This is also unnecessary and with access merging in modref may more commonly fire on accesses that we could otherwise handle. This patch fixes both also also changes interface to normalize_ref that I found confusing since it modifies the ref. Instead of that we have get_byte_range that is computing range in bytes (since that is what we need to maintain the bitmap) and has additional parameter specifying if the store in question should be turned into sub-range or super-range depending whether we compute range for kill or load. gcc/ChangeLog: 2021-11-23 Jan Hubicka <hubi...@ucw.cz> PR tree-optimization/103335 * tree-ssa-dse.c (valid_ao_ref_for_dse): Rename to ... (valid_ao_ref_kill_for_dse): ... this; do not check that boundaries are divisible by BITS_PER_UNIT. (get_byte_aligned_range_containing_ref): New function. (get_byte_aligned_range_contained_in_ref): New function. (normalize_ref): Rename to ... (get_byte_range): ... this one; handle accesses not aligned to byte boundary; return range in bytes rater than updating ao_ref. (clear_live_bytes_for_ref): Take write ref by reference; simplify using get_byte_access. (setup_live_bytes_from_ref): Likewise. (clear_bytes_written_by): Update. (live_bytes_read): Update. (dse_classify_store): Simplify tech before live_bytes_read checks. gcc/testsuite/ChangeLog: 2021-11-23 Jan Hubicka <hubi...@ucw.cz> * gcc.dg/tree-ssa/modref-dse-4.c: Update template. * gcc.dg/tree-ssa/modref-dse-5.c: Update template.
