https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119537
--- Comment #9 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:a6c2248cfd4bc922378f554578ee44e6b4690f5d commit r15-9124-ga6c2248cfd4bc922378f554578ee44e6b4690f5d Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Apr 1 11:40:58 2025 +0200 gimple-low: Diagnose assume attr expressions defining labels which are used as unary && operands outside of those [PR119537] The following testcases ICE on invalid code which defines labels inside of statement expressions and then uses &&label from code outside of the statement expressions. The C++ FE diagnoses that with a warning (not specifically for assume attribute, genericallly about taking address of a label outside of a statement expression so computed goto could violate the requirement that statement expression is not entered from outside of it through a jump into it), the C FE doesn't diagnose anything. Normal direct gotos to such labels are diagnosed by both C and C++. In the assume attribute case it is actually worse than for addresses of labels in normal statement expressions, in that case the labels are still in the current function, so invalid program can still jump to those (and in case of OpenMP/OpenACC where it is also invalid and stuff is moved to a separate function, such movement is done post cfg discovery of FORCED_LABELs and worst case one can run into cases which fail to assemble, but I haven't succeeded in creating ICE for that). For assume at -O0 we'd just throw away the assume expression if it is not a simple condition and so the label is then not defined anywhere and we ICE during cfg pass. The gimplify.cc hunks fix that, as we don't have FORCED_LABELs discovery done yet, it preserves all assume expressions which contain used user labels. With that we ICE during IRA, which is upset about an indirect jump to a label which doesn't exist. So, the gimple-low.cc hunks add diagnostics of the problem, it gathers uids of all the user used labels inside of the assume expressions (usually none) and if it finds any, walks the IL to find uses of those from outside of those expressions now outlined into separate magic functions. 2025-04-01 Jakub Jelinek <ja...@redhat.com> PR middle-end/119537 * gimplify.cc (find_used_user_labels): New function. (gimplify_call_expr): Don't remove complex assume expression at -O0 if it defines any user labels. * gimple-low.cc: Include diagnostic-core.h. (assume_labels): New variable. (diagnose_assume_labels): New function. (lower_function_body): Call it via walk_gimple_seq if assume_labels is non-NULL, then BITMAP_FREE assume_labels. (find_assumption_locals_r): Record in assume_labels uids of user labels defined in assume attribute expressions. * c-c++-common/pr119537-1.c: New test. * c-c++-common/pr119537-2.c: New test.
