https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113757
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Martin Jambor <jamb...@gcc.gnu.org>: https://gcc.gnu.org/g:2183e5b5aa3a080624cb95a06993e34dedd09cb2 commit r12-10443-g2183e5b5aa3a080624cb95a06993e34dedd09cb2 Author: Martin Jambor <mjam...@suse.cz> Date: Mon Apr 8 17:34:33 2024 +0200 ipa: Self-DCE of uses of removed call LHSs (PR 108007) PR 108007 is another manifestation where we rely on DCE to clean-up after IPA-SRA and if the user explicitely switches DCE off, IPA-SRA can leave behind statements which are fed uninitialized values and trap, even though their results are themselves never used. I have already fixed this for unused parameters in callees, this bug shows that almost the same thing can happen for removed returns, on the side of callers. This means that the issue has to be fixed elsewhere, in call redirection. This patch adds a function which looks for (and through, using a work-list) uses of operations fed specific SSA names and removes them all. That would have been easy if it wasn't for debug statements during tree-inline (from which call redirection is also invoked). Debug statements are decoupled from the rest at this point and iterating over uses of SSAs does not bring them up. During tree-inline they are handled especially at the end, I assume in order to make sure that relative ordering of UIDs are the same with and without debug info. This means that during tree-inline we need to make a hash of killed SSAs, that we already have in copy_body_data, available to the function making the purging. So the patch duly does also that, making the interface slightly ugly. Moreover, all newly unused SSA names need to be freed and as PR 112616 showed, it must be done in a defined order, which is what newly added ipa_release_ssas_in_hash does. This backport to gcc-13 also contains 54e505d0446f86b7ad383acbb8e5501f20872b64 in order not to reintroduce PR 113757. gcc/ChangeLog: 2024-04-05 Martin Jambor <mjam...@suse.cz> PR ipa/108007 PR ipa/112616 * cgraph.h (cgraph_edge): Add a parameter to redirect_call_stmt_to_callee. * ipa-param-manipulation.h (ipa_param_adjustments): Add a parameter to modify_call. (ipa_release_ssas_in_hash): Declare. * cgraph.cc (cgraph_edge::redirect_call_stmt_to_callee): New parameter killed_ssas, pass it to padjs->modify_call. * ipa-param-manipulation.cc (purge_all_uses): New function. (ipa_param_adjustments::modify_call): New parameter killed_ssas. Instead of substituting uses, invoke purge_all_uses. If hash of killed SSAs has not been provided, create a temporary one and release SSAs that have been added to it. (compare_ssa_versions): New function. (ipa_release_ssas_in_hash): Likewise. * tree-inline.cc (redirect_all_calls): Create id->killed_new_ssa_names earlier, pass it to edge redirection, adjust a comment. (copy_body): Release SSAs in id->killed_new_ssa_names. gcc/testsuite/ChangeLog: 2024-01-15 Martin Jambor <mjam...@suse.cz> PR ipa/108007 PR ipa/112616 * gcc.dg/ipa/pr108007.c: New test. * gcc.dg/ipa/pr112616.c: Likewise. (cherry picked from commit 40ddc0b05a47f999b24f20c1becb79004995731b)
