https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122038
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <[email protected]>: https://gcc.gnu.org/g:8590b32deac05e6eb368b72bd353749134120a1f commit r16-4637-g8590b32deac05e6eb368b72bd353749134120a1f Author: Andrew Pinski <[email protected]> Date: Fri Oct 24 17:13:26 2025 -0700 forwprop: Fix copy prop for alignment after the final folding [PR122086] After r16-4081-g966cdec2b2 which added folding of __builtin_assume_aligned, forwprop would propagate pointers that lower alignment replacing ones with greater alignment. This causes us to lose alignment information that __builtin_assume_aligned provided to expand. Normally this just loses some optimizations except in the s390 case where the alignment is specifically checked and was for inlining of the atomics; without this patch an infininite loop would happen. Note this was previously broken for -Og before r16-4081-g966cdec2b2. This fixes -Og case as forwprop is used instead of copyprop. This moves the testcase for pr107389.c to torture to get a generic testcase. pr107389.c was originally for -O0 case but we should test for other optimization levels so this is not lost again. align-5.c is xfailed because __builtin_assume_aligned is not instrumented for ubsan alignment and ubsan check to see pointer is aligned before emitting a check for the load (based on the known alignment in compiling). See PR 122038 too. I had mentioned this issue previously in r16-4081-g966cdec2b2 too. PR middle-end/107389 PR tree-optimization/122086 gcc/ChangeLog: * tree-ssa-forwprop.cc (forwprop_may_propagate_copy): New function. (pass_forwprop::execute): Use forwprop_may_propagate_copy instead of may_propagate_copy. gcc/testsuite/ChangeLog: * gcc.dg/pr107389.c: Move to... * gcc.dg/torture/pr107389.c: ...here. Skip for lto. Use dg-additional-options rather than dg-options. * c-c++-common/ubsan/align-5.c: xfail. Signed-off-by: Andrew Pinski <[email protected]>
