https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302
Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
(In reply to nsz from comment #0)
> i think the following inconsistency is problematic:
>
> on a hard float toolchain (-mfloat-abi=hard):
>
> $ arm-none-linux-gnueabihf-gcc -mfpu=auto -march=armv7-a a.c ; echo $?
> cc1: error: -mfloat-abi=hard: selected processor lacks an FPU
> 1
This is the correct response, you haven't specified the expected floating
point/simd extensions in the architecture.
> $ arm-none-linux-gnueabihf-gcc -mfpu=auto -march=armv7-a+fp a.c ; echo $?
> 0
correct response.
> $ arm-none-linux-gnueabihf-gcc -mfpu=auto -march=armv8-a a.c ; echo $?
> cc1: error: -mfloat-abi=hard: selected processor lacks an FPU
> 1
Correct response, floating point/simd extension not enabled.
> $ arm-none-linux-gnueabihf-gcc -mfpu=auto -march=armv8-a+fp a.c ; echo $?
> arm-none-linux-gnueabihf-gcc: error: 'armv8-a' does not support feature 'fp'
> arm-none-linux-gnueabihf-gcc: note: valid feature names are: crc simd crypto
> nocrypto nofp; did you mean 'nofp'?
> 1
Correct response. Fp without SIMD is not an option in Arm v8.
> $ arm-none-linux-gnueabihf-gcc -mfpu=auto -march=armv8-a+simd a.c ; echo $?
> 0
>
> so it seems neither armv8-a nor armv8-a+fp work with -mfpu=auto, but
> armv8-a+simd and armv7-a+fp do.
this is all as it should be. The documentation describes which options are
available for which architecture.
