https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115154
--- Comment #16 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:49c87d22535ac4f8aacf088b3f462861c26cacb4 commit r15-755-g49c87d22535ac4f8aacf088b3f462861c26cacb4 Author: Andrew Pinski <quic_apin...@quicinc.com> Date: Mon May 20 00:16:40 2024 -0700 match: Disable `(type)zero_one_valuep*CST` for 1bit signed types [PR115154] The problem here is the pattern added in r13-1162-g9991d84d2a8435 assumes that it is well defined to multiply zero_one_valuep by the truncated converted integer constant. It is well defined for all types except for signed 1bit types. Where `a * -1` is produced which is undefined/ So disable this pattern for 1bit signed types. Note the pattern added in r14-3432-gddd64a6ec3b38e is able to workaround the undefinedness except when `-fsanitize=undefined` is turned on, this is why I added a testcase for that. Bootstrapped and tested on x86_64-linux-gnu with no regressions. PR tree-optimization/115154 gcc/ChangeLog: * match.pd (convert (mult zero_one_valued_p@1 INTEGER_CST@2)): Disable for 1bit signed types. gcc/testsuite/ChangeLog: * c-c++-common/ubsan/signed1bitfield-1.c: New test. * gcc.c-torture/execute/signed1bitfield-1.c: New test. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
