https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122991
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-15 branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:d6b210bc7f9f13be241cf6e16bc39e4885c45a2e commit r15-10585-gd6b210bc7f9f13be241cf6e16bc39e4885c45a2e Author: Jakub Jelinek <[email protected]> Date: Thu Dec 4 12:17:45 2025 +0100 i386: Fix crc_rev<SWI124:mode>si4 expander [PR122991] The following testcase ICEs on x86_64, because the crc_rev_optab expander assumes the last operand will be a CONST_INT. That assumption comes from it being created with rtx polynomial; if (TREE_CODE (rhs3) != INTEGER_CST) { error ("third argument to %<crc%> builtins must be a constant"); polynomial = const0_rtx; } else polynomial = convert_to_mode (TYPE_MODE (result_type), expand_normal (rhs3), 0); and so it doesn't bother adding a predicate for it. Except that maybe_legitimize_operands which expand_insn calls has: This avoids duplicate rtl and ensures that tied operands remain tied. This search is linear, but NOPS is bounded at compile time to a small number (current a single digit). */ unsigned int j = 0; for (; j < i; ++j) if (can_reuse_operands_p (icode, opno + j, opno + i, &ops[j], &ops[i]) && rtx_equal_p (orig_values[j], orig_values[i]) && ops[j].value && insn_operand_matches (icode, opno + i, ops[j].value)) { ops[i].value = copy_rtx (ops[j].value); break; } in it, so if one of the earlier operands has equal original value to the polynomial argument, but has a predicate like register_operand or nonimmediate_operand, the earlier iteration forced that value into a pseudo and when the last operand doesn't have a predicate, this happily reuses that pseudo as the last operand. And then it either with RTL checking fails on INTVAL use on that operand, or without rtl checking ICEs during expansion of the insn e.g. using table lookup. The following patch fixes it by using const_int_operand predicate for it. That is what loongarch and riscv backends use for it too. Aarch64 doesn't and I'll send a fix for that once tested on aarch64-linux. 2025-12-04 Jakub Jelinek <[email protected]> PR target/122991 * gcc.dg/pr122991.c: New test. (cherry picked from commit 37062ea54ad571a4ea1be0d9d65d0ddd4008e118)
