https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115337
--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:b82a816000791e7a286c7836b3a473ec0e2a577b commit r15-1011-gb82a816000791e7a286c7836b3a473ec0e2a577b Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jun 4 15:49:41 2024 +0200 fold-const: Fix up CLZ handling in tree_call_nonnegative_warnv_p [PR115337] The function currently incorrectly assumes all the __builtin_clz* and .CLZ calls have non-negative result. That is the case of the former which is UB on zero and has [0, prec-1] return value otherwise, and is the case of the single argument .CLZ as well (again, UB on zero), but for two argument .CLZ is the case only if the second argument is also nonnegative (or if we know the argument can't be zero, but let's do that just in the ranger IMHO). The following patch does that. 2024-06-04 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/115337 * fold-const.cc (tree_call_nonnegative_warnv_p) <CASE_CFN_CLZ>: If arg1 is non-NULL, RECURSE on it, otherwise return true. * gcc.dg/bitint-106.c: New test.
