Use auxv to check for CRC32 instructions on ARM. Previously we probed for CRC32 instructions by testing if they caused SIGILL. Some have expressed doubts about that technique, the Linux documentation advises not to use it, and it's not exactly beautiful. Now that more operating systems expose CPU features to userspace via the ELF loader in approximately the same way, let's use that instead.
This is expected to work on Linux, FreeBSD and recent OpenBSD. OpenBSD/ARM has not been tested and is not present in our build farm, but the API matches FreeBSD. On macOS, compilers use a more recent baseline ISA so the runtime test mechanism isn't reached. (A similar situation is expected for Windows/ARM when that port lands.) On NetBSD, runtime feature probing is lost for armv8-a builds. It looks potentially doable with sysctl following the example of the cpuctl program; patches are welcome. No back-patch for now, since we don't have any evidence of actual breakage from the previous technique. Suggested-by: Bastien Roucariès <ro...@debian.org> Discussion: https://postgr.es/m/4496616.iHFcN1HehY%40portable-bastien Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/aac831cafa6f3106dfcbd3298757801c299351fc Modified Files -------------- configure | 2 +- configure.ac | 2 ++ meson.build | 2 ++ src/include/pg_config.h.in | 6 ++++ src/port/pg_crc32c_armv8_choose.c | 66 ++++++++++++++------------------------- 5 files changed, 34 insertions(+), 44 deletions(-)
