https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114577
--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:86dce005a1d440154dbf585dde5a2dd4cfac7a05 commit r14-9787-g86dce005a1d440154dbf585dde5a2dd4cfac7a05 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Thu Apr 4 14:15:49 2024 +0100 aarch64: Recognise svundef idiom [PR114577] GCC 14 adds the header file arm_neon_sve_bridge.h to help interface SVE and Advanced SIMD code. One of the defined idioms is: svset_neonq (svundef_TYPE (), advsimd_vector) which simply reinterprets advsimd_vector as an SVE vector without regard for what's in the upper bits. GCC was failing to recognise this idiom, which was likely to significantly hamper adoption. There is (AFAIK) no good way of representing an extension with undefined bits in gimple. We could add an internal-only builtin to represent it, but the current framework makes that somewhat awkward. It also doesn't seem very forward-looking. This patch instead goes for the simpler approach of recognising undefined arguments at expansion time. gcc/ PR target/114577 * config/aarch64/aarch64-sve-builtins.h (aarch64_sve::lookup_fndecl): Declare. * config/aarch64/aarch64-sve-builtins.cc (aarch64_sve::lookup_fndecl): New function. * config/aarch64/aarch64-sve-builtins-base.cc (is_undef): Likewise. (svset_neonq_impl::expand): Optimise expansions whose first argument is undefined. gcc/testsuite/ PR target/114577 * gcc.target/aarch64/sve/acle/general/pr114577_1.c: New test. * gcc.target/aarch64/sve/acle/general/pr114577_2.c: Likewise.
