https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121294
--- Comment #9 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-13 branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:43f7e74037fca2806ea6e7ae809ff5eb590d1409 commit r13-9836-g43f7e74037fca2806ea6e7ae809ff5eb590d1409 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Thu Aug 14 21:55:28 2025 +0100 aarch64: Use VNx16BI for more permutations [PR121294] The patterns for the predicate forms of svtrn1/2, svuzp1/2, and svzip1/2 are shared with aarch64_vectorize_vec_perm_const. The .H, .S, and .D forms operate on VNx8BI, VNx4BI, and VNx2BI respectively. Thus, for all four element widths, there is one significant bit per element, for both the inputs and the output. That's appropriate for aarch64_vectorize_vec_perm_const but not for the ACLE intrinsics, where every bit of the output is significant, and where every bit of the selected input elements is therefore also significant. The current expansion can lead the optimisers to simplify inputs by changing the upper bits of the input elements (since the current patterns claim that those bits don't matter), which in turn leads to wrong code. The ACLE expansion should operate on VNx16BI instead, for all element widths. There was already a pattern for a VNx16BI-only form of TRN1, for constructing certain predicate constants. The patch generalises it to handle the other five permutations as well. For the reasons given in the comments, this is done by making the permutation unspec an operand to a new UNSPEC_PERMUTE_PRED, rather than overloading the existing unspecs, and rather than adding a new unspec for each permutation. gcc/ PR target/121294 * config/aarch64/iterators.md (UNSPEC_TRN1_CONV): Delete. (UNSPEC_PERMUTE_PRED): New unspec. * config/aarch64/aarch64-sve.md (@aarch64_sve_trn1_conv<mode>): Replace with... (@aarch64_sve_<perm_insn><mode>_acle) (*aarch64_sve_<perm_insn><mode>_acle): ...these new patterns. * config/aarch64/aarch64.cc (aarch64_expand_sve_const_pred_trn): Update accordingly. * config/aarch64/aarch64-sve-builtins-functions.h (binary_permute::expand): Use the new _acle patterns for predicate operations. gcc/testsuite/ PR target/121294 * gcc.target/aarch64/sve/acle/general/perm_2.c: New test. * gcc.target/aarch64/sve/acle/general/perm_3.c: Likewise. * gcc.target/aarch64/sve/acle/general/perm_4.c: Likewise. * gcc.target/aarch64/sve/acle/general/perm_5.c: Likewise. * gcc.target/aarch64/sve/acle/general/perm_6.c: Likewise. * gcc.target/aarch64/sve/acle/general/perm_7.c: Likewise. (cherry picked from commit 4cf9d4ebdd68a724eb41044cd8f2a4d466d81c7f)
