https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121422
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>: https://gcc.gnu.org/g:899e7284bfa0b736165c3d9d5c18d5d883c5cbfb commit r16-3094-g899e7284bfa0b736165c3d9d5c18d5d883c5cbfb Author: Andrew Pinski <quic_apin...@quicinc.com> Date: Sun Jun 8 23:13:23 2025 -0700 forwprop: Change proping memset into memcpy into a forwprop rather than a backwalk One thing I noticed while working on copy prop for aggregates is that we start with a memcpy like statement and then walk backwards. This means we could have a few walks backwards to see there was no statement for zeroing. Instead this changes the walk backwards into a true forwprop. In the future we can expand to forwprop the zeroing into say an function argument or something more than memcpy like statement. This should speed up slightly the compile time performance since there will be less memsets like statements than memcpy and there is only one walk forwards for memset like staments instead of multiple walk backwards to find the memset. Note this does add one extra improvement, the memcpy now does not need to have an address as its dest argument; this could have been done before too but it was even more noticable now because of the variable became only set so it was removed and the check was removed as well. There is also a fix on how ao_ref for the memset/memcpy is done, before it was just using ao_ref_init which is wrong since it should instead of used ao_ref_init_from_ptr_and_size. This part fixes PR 121422. Changes since v1: * v2: Add back limit on the walk which was missed in v1. Move the call to get_addr_base_and_unit_offset outside of the vuse loop. * v3: Remove extra check before the call to optimize_aggr_zeroprop_1. Fix setting up of ao_ref for memset (PR121422). PR tree-optimization/118946 PR tree-optimization/121422 gcc/ChangeLog: * tree-ssa-forwprop.cc (optimize_memcpy_to_memset): Remove. (optimize_aggr_zeroprop_1): New function. (optimize_aggr_zeroprop): New function. (simplify_builtin_call): Don't call optimize_memcpy_to_memset for memcpy but call optimize_aggr_zeroprop for memset. (pass_forwprop::execute): Don't call optimize_memcpy_to_memset for aggregate copies but rather call optimize_aggr_zeroprop for aggregate stores. gcc/testsuite/ChangeLog: * gcc.dg/pr118946-1.c: New test. * gcc.dg/torture/pr121422-1.c: New test. * gcc.dg/torture/pr121422-2.c: New test. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
