https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83206
Bug ID: 83206 Summary: -mfpu=auto does not work on ARM (armv7l-unknown-linux-gnueabihf) Product: gcc Version: 8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: driver Assignee: unassigned at gcc dot gnu.org Reporter: andrewm.roberts at sky dot com Target Milestone: --- On ARM an option to -mfpu is auto, this is given when you do: /usr/local/gcc/bin/gcc -mcpu=native -Q --help=target ... Known ARM FPUs (for use with the -mfpu= option): auto crypto-neon-fp-armv8 fp-armv8 fpv4-sp-d16 fpv5-d16 fpv5-sp-d16 neon neon-fp-armv8 neon-fp16 neon-vfpv3 neon-vfpv4 vfp vfp3 vfpv2 vfpv3 vfpv3-d16 vfpv3-d16-fp16 vfpv3-fp16 vfpv3xd vfpv3xd-fp16 vfpv4 vfpv4-d16 If you try: /usr/local/gcc/bin/gcc -mcpu=native -mfpu=auto -Q --help=target You get: -mfpu= auto But if you try to use it: gcc -march=native -mcpu=native -mtune=native -mfpu=auto -Ofast -o matrix matrix.c You get: cc1: error: -mfloat-abi=hard: selected processor lacks an FPU which isn't true as: gcc -march=native -mcpu=native -mtune=native -mfpu=neon -Ofast -o matrix matrix.c works as does -mfpu=vfpv3-d16 etc This is true on: armv7l and armv6l at least, tested on: ODROID-XU3: (ARM big/little Cortex-A15/A7) Raspbery Pi B: (ARM ARM1176) Raspberry Pi 2B v1: (ARM Cortex-A7) Raspberry Pi 3B: (ARM Cortex-A53)