https://gcc.gnu.org/bugzilla/show_bug.cgi?id=13421
--- Comment #17 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:667c19de86b33648f5f4599f589a5e02adbb35cb commit r15-67-g667c19de86b33648f5f4599f589a5e02adbb35cb Author: Richard Biener <rguent...@suse.de> Date: Tue Apr 16 14:05:35 2024 +0200 middle-end/13421 - -ftrapv vs. POINTER_DIFF_EXPR Currently we expand POINTER_DIFF_EXPR using subv_optab when -ftrapv (but -fsanitize=undefined does nothing). That's not consistent with the behavior of POINTER_PLUS_EXPR which never uses addv_optab with -ftrapv. Both are because of the way we select whether to use the trapping or the non-trapping optab - we look at the result type of the expression and check trapv = INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_TRAPS (type); the bugreport correctly complains that -ftrapv affects pointer subtraction (there's no -ftrapv-pointer). Now that we have POINTER_DIFF_EXPR we can honor that appropriately. The patch moves both POINTER_DIFF_EXPR and POINTER_PLUS_EXPR handling so they will never consider trapping (or saturating) optabs. PR middle-end/13421 * optabs-tree.cc (optab_for_tree_code): Do not consider {add,sub}v or {us,ss}{add,sub} optabs for POINTER_DIFF_EXPR or POINTER_PLUS_EXPR.
