https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120295
--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Martin Jambor <jamb...@gcc.gnu.org>: https://gcc.gnu.org/g:0b004c92f5ea239936a403a2a757e12ca82ce6d8 commit r16-960-g0b004c92f5ea239936a403a2a757e12ca82ce6d8 Author: Martin Jambor <mjam...@suse.cz> Date: Thu May 29 16:32:04 2025 +0200 ipa: When inlining, don't combine PT JFs changing signedness (PR120295) In GCC 15 we allowed jump-function generation code to skip over a type-cast converting one integer to another as long as the latter can hold all the values of the former or has at least the same precision. This works well for IPA-CP where we do then evaluate each jump function as we propagate values and value-ranges. However, the test-case in PR 120295 shows a problem with inlining, where we combine pass-through jump-functions so that they are always relative to the function which is the root of the inline tree. Unfortunately, we are happy to combine also those with type-casts to a different signedness which makes us use sign zero extension for the expected value ranges where we should have used sign extension. When the value-range which then leads to wrong insertion of a call to builtin_unreachable is being computed, the information about an existence of a intermediary signed type has already been lost during previous inlining. This patch simply blocks combining such jump-functions so that it is back-portable to GCC 15. Once we switch pass-through jump functions to use a vector of operations rather than having room for just one, we will be able to address this situation with adding an extra conversion instead. gcc/ChangeLog: 2025-05-19 Martin Jambor <mjam...@suse.cz> PR ipa/120295 * ipa-prop.cc (update_jump_functions_after_inlining): Do not combine pass-through jump functions with type-casts changing signedness. gcc/testsuite/ChangeLog: 2025-05-19 Martin Jambor <mjam...@suse.cz> PR ipa/120295 * gcc.dg/ipa/pr120295.c: New test.
