https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109176
--- Comment #16 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:484c41c747d95f9cee15a33b75b32ae2e7eb45f3 commit r13-6827-g484c41c747d95f9cee15a33b75b32ae2e7eb45f3 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Mar 23 10:02:25 2023 +0100 tree-vect-generic: Fix up expand_vector_condition [PR109176] The following testcase ICEs on aarch64-linux, because expand_vector_condition attempts to piecewise lower SVE d_3 = a_1(D) < b_2(D); _5 = VEC_COND_EXPR <d_3, c_4(D), d_3>; which isn't possible - nunits_for_known_piecewise_op ICEs but the rest of the code assumes constant number of elements too. expand_vector_condition attempts to find if a (rhs1) is a SSA_NAME for comparison and calls expand_vec_cond_expr_p (type, TREE_TYPE (a1), code) where a1 is one of the operands of the comparison and code is the comparison code. That one indeed isn't supported here, but what aarch64 SVE supports are the individual statements, comparison (expand_vec_cmp_expr_p) and expand_vec_cond_expr_p (type, TREE_TYPE (a), SSA_NAME), the latter because that function starts with if (VECTOR_BOOLEAN_TYPE_P (cmp_op_type) && get_vcond_mask_icode (TYPE_MODE (value_type), TYPE_MODE (cmp_op_type)) != CODE_FOR_nothing) return true; In an earlier version of the patch (in the PR), we did this if (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (a)) && expand_vec_cond_expr_p (type, TREE_TYPE (a), ERROR_MARK)) return true; before the code == SSA_NAME handling plus some further tweaks later. While that fixed the ICE, it broke quite a few tests on x86 and some on aarch64 too. The problem is that expand_vector_comparison doesn't lower comparisons which aren't supported and only feed VEC_COND_EXPR first operand and expand_vector_condition succeeds for those, so with the above mentioned change we'd verify the VEC_COND_EXPR is implementable using optab alone, but nothing would verify the tcc_comparison which relied on expand_vector_condition to verify. So, the following patch instead queries whether optabs can handle the comparison and VEC_COND_EXPR together (if a (rhs1) is a comparison; otherwise as before it checks only the VEC_COND_EXPR) and if that fails, also checks whether the two operations could be supported individually and only if even that fails does the piecewise lowering. 2023-03-23 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/109176 * tree-vect-generic.cc (expand_vector_condition): If a has vector boolean type and is a comparison, also check if both the comparison and VEC_COND_EXPR could be successfully expanded individually. * gcc.target/aarch64/sve/pr109176.c: New test.
