vDSP functions in ggml-cpu/binary-ops.cpp need type casting on at least one older version of OS X

[exprez135]

While testing my work on updating whisper.cpp packaging on MacPorts, @barracuda156 discovered an issue with older OS X versions (output copied below), in which apparently vDSP functions like vDSP_vadd were not using const float as they are now, which leads to an error.

using vDSP_fn_t = void (*)(const float *, vDSP_Stride, const float *, vDSP_Stride, float *, vDSP_Stride, vDSP_Length); AKA {aka 'void (*)(const float*, long int, const float*, long int, float*, long int, long unsigned int)'}

But it appears that on his OS X 10.6, vDSP_v{div,add,sub,mul} were void (*)(float*, long int, float*, long int, float*, long int, long unsigned int)?

I think that a potential fix would be to put each of these (starting https://github.com/ggml-org/whisper.cpp/blob/adaea088bca383ac7abebdce26546f1885bd9376/ggml/src/ggml-cpu/binary-ops.cpp#L73C1-L73C33) inside a reinterpret_cast<>()?

vDSP_op = reinterpret_cast<vDSP_fn_t>(vDSP_vadd); etc.

His error output:

/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu -I/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/../include -F//System/Library/Frameworks -pipe -Os -DNDEBUG -isystem/opt/local/include/LegacySupport -I/opt/local/include -D_GLIBCXX_USE_CXX11_ABI=0 -std=gnu++17 -arch ppc -mmacosx-version-min=10.6 -fPIC -Wmissing-declarations -Wmissing-noreturn -Wall -Wextra -Wpedantic -Wcast-qual -Wno-unused-function -Wno-array-bounds -Wextra-semi -fopenmp -MD -MT ggml/src/CMakeFiles/ggml-cpu.dir/ggml-cpu/unary-ops.cpp.o -MF CMakeFiles/ggml-cpu.dir/ggml-cpu/unary-ops.cpp.o.d -o CMakeFiles/ggml-cpu.dir/ggml-cpu/unary-ops.cpp.o -c /opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/unary-ops.cpp
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp: In instantiation of 'void apply_binary_op(const ggml_compute_params*, ggml_tensor*) [with float (* op)(float, float) = op_add; src0_t = float; src1_t = float; dst_t = float]':
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:125:49:   required from 'void binary_op(const ggml_compute_params*, ggml_tensor*) [with float (* op)(float, float) = op_add]'
  125 |         apply_binary_op<op, float, float, float>(params, dst);
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:145:22:   required from here
  145 |     binary_op<op_add>(params, dst);
      |     ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:79:23: error: invalid conversion from 'void (*)(float*, vDSP_Stride, float*, vDSP_Stride, float*, vDSP_Stride, vDSP_Length)' {aka 'void (*)(float*, long int, float*, long int, float*, long int, long unsigned int)'} to 'vDSP_fn_t' {aka 'void (*)(const float*, long int, const float*, long int, float*, long int, long unsigned int)'} [-fpermissive]
   79 |             vDSP_op = vDSP_vdiv;
      |                       ^~~~~~~~~
      |                       |
      |                       void (*)(float*, vDSP_Stride, float*, vDSP_Stride, float*, vDSP_Stride, vDSP_Length) {aka void (*)(float*, long int, float*, long int, float*, long int, long unsigned int)}
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp: In instantiation of 'void apply_binary_op(const ggml_compute_params*, ggml_tensor*) [with float (* op)(float, float) = op_add; src0_t = short unsigned int; src1_t = short unsigned int; dst_t = short unsigned int]':
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:127:67:   required from 'void binary_op(const ggml_compute_params*, ggml_tensor*) [with float (* op)(float, float) = op_add]'
  127 |         apply_binary_op<op, ggml_fp16_t, ggml_fp16_t, ggml_fp16_t>(params, dst);
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:145:22:   required from here
  145 |     binary_op<op_add>(params, dst);
      |     ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
/opt/local/var/macports/build/_opt_local_ppcports_audio_whisper/whisper/work/whisper.cpp-1.7.5/ggml/src/ggml-cpu/binary-ops.cpp:79:23: error: invalid conversion from 'void (*)(float*, vDSP_Stride, float*, vDSP_Stride, float*, vDSP_Stride, vDSP_Length)' {aka 'void (*)(float*, long int, float*, long int, float*, long int, long unsigned int)'} to 'vDSP_fn_t' {aka 'void (*)(const float*, long int, const float*, long int, float*, long int, long unsigned int)'} [-fpermissive]
   79 |             vDSP_op = vDSP_vdiv;
      |                       ^~~~~~~~~
      |                       |

[barracuda156]

Just in case, I can test suggested patches.