[PATCH 0/3] ARM with only 32-bit floats do not have fast 64-bit FMA

[Sebastian Huber]

On 01/09/2020 18:32, Sebastian Huber wrote:

> Hello,
>
> with the latest Newlib, I get a linker error in the RTEMS test suite:
>
>
> undefined reference to `fma'
> undefined reference to `fmaf'
>
> The following machine flags are used:
>
> '-march=armv7-a', '-mthumb', '-mfpu=neon', '-mfloat-abi=hard', 
> '-mtune=cortex-a9'
>
> It seems to be missing in the corresponding multilib:
>
> nm /build/rtems/6/arm-rtems6/lib/thumb/armv7-a+simd/hard/libm.a | grep 
> fma
> lib_a-fmal.o:
>          U fma
> 00000000 T fmal
> lib_a-fmaxl.o:
>          U fmax
> 00000000 T fmaxl
> lib_a-s_fma.o:
> lib_a-s_fmax.o:
> 00000000 T fmax
> lib_a-sf_fma.o:
> lib_a-sf_fmax.o:
> 00000000 T fmaxf
>
It seems to be present in only some multilibs:

for i in $(find /build/rtems/6/arm-rtems6/lib -name libm.a); do echo $i 
; nm --defined-only $i | grep 'T.*\<fma\>'; done
/build/rtems/6/arm-rtems6/lib/eb/thumb/armv7-r+fp/hard/libm.a
/build/rtems/6/arm-rtems6/lib/eb/thumb/armv7-r/libm.a
/build/rtems/6/arm-rtems6/lib/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m4/hard/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m3/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m7/hard/libm.a
00000000 T fma
/build/rtems/6/arm-rtems6/lib/thumb/armv6-m/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-r+fp/hard/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-r/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m4+nofp/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-a+simd/hard/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-a/libm.a
/build/rtems/6/arm-rtems6/lib/armv5te+fp/hard/libm.a

for i in $(find /build/rtems/6/arm-rtems6/lib -name libm.a); do echo $i 
; nm --defined-only $i | grep 'T.*\<fmaf\>'; done
/build/rtems/6/arm-rtems6/lib/eb/thumb/armv7-r+fp/hard/libm.a
/build/rtems/6/arm-rtems6/lib/eb/thumb/armv7-r/libm.a
/build/rtems/6/arm-rtems6/lib/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m4/hard/libm.a
00000000 T fmaf
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m3/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m7/hard/libm.a
00000000 T fmaf
/build/rtems/6/arm-rtems6/lib/thumb/armv6-m/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-r+fp/hard/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-r/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/cortex-m4+nofp/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-a+simd/hard/libm.a
/build/rtems/6/arm-rtems6/lib/thumb/armv7-a/libm.a
/build/rtems/6/arm-rtems6/lib/armv5te+fp/hard/libm.a