https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108783
--- Comment #6 from CVS 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:55db240d28d29aac90a2d2af3768283ba6288752 commit r13-6074-g55db240d28d29aac90a2d2af3768283ba6288752 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Feb 16 10:41:18 2023 +0100 reassoc: Fix up (ab) handling in eliminate_redundant_comparison [PR108783] The following testcase ICEs because eliminate_redundant_comparison sees redundant comparisons in &&/|| where the comparison has (ab) SSA_NAME, maybe_fold_{and,or}_comparisons optimizes them into a single comparison and build_and_add_sum emits a new comparison close to the definition operands, which in this case is before a returns_twice call (which is invalid). Generally reassoc just punts on (ab) SSA_NAMEs, declares them non-reassociable etc., so the second half of this patch does that. Though we can do better in this case; the function has special code when maybe_fold_{and,or}_comparisons returns INTEGER_CST (false/true) or when what it returns is the same as curr->op (the first of the comparisons we are considering) - in that case we just remove the second one and keep the first one. The reason it doesn't match is that curr->op is a SSA_NAME whose SSA_NAME_DEF_STMT is checked to be a comparison, in this case _42 = a_1(ab) != 0 and the other comparison is also like that. maybe_fold_{and,or}_comparisons looks through the definitions though and so returns a_1(ab) != 0 as tree. So the first part of the patch checks whether that returned comparison isn't the same as the curr->op comparison and if yes, it just overrides t back to curr->op so that its SSA_NAME is reused. In that case we can handle even (ab) in {,new}op{1,2} because we don't create a new comparison of that, just keep using the existing one. And t can't be (ab) because otherwise it wouldn't be considered a reassociable operand. The (ab) checks are needed say when we have a_1(ab) == 42 || a_1(ab) > 42 kind of comparisons where maybe_fold_{and,or}_comparisons returns a new comparison not existing in the IL yet. 2023-02-16 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/108783 * tree-ssa-reassoc.cc (eliminate_redundant_comparison): If lcode is equal to TREE_CODE (t), op1 to newop1 and op2 to newop2, set t to curr->op. Otherwise, punt if either newop1 or newop2 are SSA_NAME_OCCURS_IN_ABNORMAL_PHI SSA_NAMEs. * gcc.c-torture/compile/pr108783.c: New test.
