GGML_CPU_ALL_VARIANTS Apple segfault (no score function)

[peardox]

@danbev - Possibly your stuff? I seem to remember you fixing GGML_CPU_ALL_VARIANTS

Try an Apple build like this....

cmake -B build -DWHISPER_COREML=1 -DWHISPER_SDL2=ON -DBUILD_SHARED_LIBS=ON -DGGML_CPU_ALL_VARIANTS=ON -DGGML_BACKEND_DL=ON

The Apple version now has m1, m2_m3 and m4 CPU variants that will be built

Now run a whisper-bench on the resultant code and it'll segfault

Fixed null pointer issue is #3313

[peardox]

Bit more investigation

ggml_backend_try_load_best: (cpu)
== Trying to load /Volumes/SN770/src/whisper-dev/build/bin/libggml-cpu-apple_m4.so
== Trying to load /Volumes/SN770/src/whisper-dev/build/bin/libggml-cpu-apple_m2_m3.so
== Trying to load /Volumes/SN770/src/whisper-dev/build/bin/libggml-cpu-apple_m1.so
Driver loading for "cpu" failed

Does the same for aarch64 (a Pi5)

ggml_backend_try_load_best: (cpu)
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv9.2_2.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv9.2_1.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.2_2.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.0_1.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.6_2.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.6_1.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.2_1.so
Trying to load /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.2_3.so
Driver loading for "cpu" failed

Dunno why ATM

[peardox]

Found it!

ggml_backend_load_best: failed to find ggml_backend_score in /home/simon/src/whisper-dev/build/bin/libggml-cpu-armv8.2_1.so

This will be the same for all the bad ones

Basically as it can't score the cpu it'll default to returning a score of zero and reject the device

[peardox]

Closer....

Needs building with -DGGML_CPU_ARM_ARCH=OFF for arm to hit the right CMakeLists,txt section (a bit back-to-front?) as well as the normal -DGGML_CPU_ALL_VARIANTS=ON -DGGML_BACKEND_DL=ON -DBUILD_SHARED_LIBS=ON

Can't find any documentation on this - just debugging what happens

[peardox]

Right - worked out the rather convoluted switches needed for shared libs on ARM

I will add the instructions to the main README.md once I've run some more tests