ggml: link MATH_LIBRARY not by its full path

[Xarbirus]

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The current MATH_LIBRARY linkage method works if the llama.cpp library is installed on the same machine where it will be used. If the built and installed artefacts were transferred to another machine, an error like this may occur:

error: '/Applications/Xcode_14.3.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.3.sdk/usr/lib/libm.tbd', needed by '***/llama-inference', missing and no known rule to make it

due to the fact that the llama-config.cmake specifies the full path to the library. The proposed fix changes the config to
set(_llama_link_deps "${ggml_LIBRARY}" "Threads::Threads;m"). Which helps with portability.

[ggerganov]

The proposed solution generates the following warning on my system:

[ 63%] Linking CXX shared library libggml.dylib
cd /Users/ggerganov/development/github/llama.cpp/build/ggml/src && /opt/homebrew/Cellar/cmake/3.27.1/bin/cmake -E cmake_link_script CMakeFiles/ggml.dir/link.txt --verbose=1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -O3 -DNDEBUG -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.5.sdk -dynamiclib -Wl,-headerpad_max_install_names -o libggml.dylib -install_name @rpath/libggml.dylib CMakeFiles/ggml.dir/ggml.c.o "CMakeFiles/ggml.dir/ggml-alloc.c.o" "CMakeFiles/ggml.dir/ggml-backend.c.o" "CMakeFiles/ggml.dir/ggml-quants.c.o" "CMakeFiles/ggml.dir/ggml-metal.m.o" "CMakeFiles/ggml.dir/__/__/autogenerated/ggml-metal-embed.s.o" "CMakeFiles/ggml.dir/ggml-blas.cpp.o" CMakeFiles/ggml.dir/llamafile/sgemm.cpp.o "CMakeFiles/ggml.dir/ggml-aarch64.c.o"  -Xlinker -framework -Xlinker Accelerate -Xlinker -framework -Xlinker Foundation -Xlinker -framework -Xlinker Metal -Xlinker -framework -Xlinker MetalKit -Xlinker -framework -Xlinker Accelerate -lm -Xlinker -framework -Xlinker Foundation -Xlinker -framework -Xlinker Metal -Xlinker -framework -Xlinker MetalKit -lm 
ld: warning: ignoring duplicate libraries: '-lm'

Isn't it better to do something like this instead:

diff --git a/ggml/src/CMakeLists.txt b/ggml/src/CMakeLists.txt
index cd2dcd06..0c7b5cad 100644
--- a/ggml/src/CMakeLists.txt
+++ b/ggml/src/CMakeLists.txt
@@ -1334,6 +1334,9 @@ find_library(MATH_LIBRARY m)
 if (MATH_LIBRARY)
     if (NOT WIN32 OR NOT GGML_SYCL)
         target_link_libraries(ggml PRIVATE ${MATH_LIBRARY})
+        if (BUILD_SHARED_LIBS)
+            set_target_properties(ggml PROPERTIES INTERFACE_LINK_LIBRARIES "m")
+        endif()
     endif()
 endif()

[Xarbirus]

I think I found one problem. Even now the default build from the master branch on MacOS results in a duplicate problem.
When GGML_ACCELERATE and GGML_BLAS are ON and GGML_BLAS_VENDOR_DEFAULT is Apple, we link with Accelerate framework twice.
build/ggml/src/CMakeFiles/ggml.dir/link.txt:

/Library/Developer/CommandLineTools/usr/bin/c++ -g -arch arm64 \
-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX14.4.sdk \
-dynamiclib -Wl,-headerpad_max_install_names -o libggml.dylib -install_name @rpath/libggml.dylib \
CMakeFiles/ggml.dir/ggml.c.o "CMakeFiles/ggml.dir/ggml-alloc.c.o" \
"CMakeFiles/ggml.dir/ggml-backend.c.o" "CMakeFiles/ggml.dir/ggml-quants.c.o" \
"CMakeFiles/ggml.dir/ggml-blas.cpp.o" CMakeFiles/ggml.dir/llamafile/sgemm.cpp.o \
"CMakeFiles/ggml.dir/ggml-aarch64.c.o" \
-framework Accelerate \
-framework Accelerate \
/Library/Developer/CommandLineTools/SDKs/MacOSX14.4.sdk/usr/lib/libm.tbd

But when Metal (GGML_METAL is ON) comes into play, we get a more complex picture.
build/ggml/src/CMakeFiles/ggml.dir/link.txt:

/Library/Developer/CommandLineTools/usr/bin/c++ -g -arch arm64 \
-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX14.4.sdk \
-dynamiclib -Wl,-headerpad_max_install_names -o libggml.dylib -install_name @rpath/libggml.dylib \
CMakeFiles/ggml.dir/ggml.c.o "CMakeFiles/ggml.dir/ggml-alloc.c.o" \
"CMakeFiles/ggml.dir/ggml-backend.c.o" "CMakeFiles/ggml.dir/ggml-quants.c.o" \
"CMakeFiles/ggml.dir/ggml-metal.m.o" "CMakeFiles/ggml.dir/__/__/autogenerated/ggml-metal-embed.s.o" \
"CMakeFiles/ggml.dir/ggml-blas.cpp.o" CMakeFiles/ggml.dir/llamafile/sgemm.cpp.o \
"CMakeFiles/ggml.dir/ggml-aarch64.c.o" \
-framework Accelerate \
-framework Foundation \
-framework Metal \
-framework MetalKit \
-framework Accelerate \
/Library/Developer/CommandLineTools/SDKs/MacOSX14.4.sdk/usr/lib/libm.tbd \
-framework Foundation \
-framework Metal \
-framework MetalKit \
/Library/Developer/CommandLineTools/SDKs/MacOSX14.4.sdk/usr/lib/libm.tbd

Thus, all libraries and frameworks end up being duplicated. Moreover, this problem appears only with all three variables (GGML_ACCELERATE, GGML_BLAS and GGML_METAL) ON, any other two do not duplicate libm. It seems that the solution to the problem is to eliminate Accelerate double linking. But I'm not a professional in CMake, maybe you know another option or knew about this problem? I'll try to post my solution today.

[ggerganov]

I'm also not 100% confident about the correct CMake way, though here is an attempt to remove fix the double linkage: #9463. PTAL

[Xarbirus]

@ggerganov yes, that was exactly my solution! Rebased my branch onto gg/cmake-dedup-link

[Xarbirus]

Waiting for #9463 to be merged.

[Xarbirus]

Also added a change to avoid duplicating the m library with SYCL. And placed public libraries in a separate list.

[ggerganov]

Let's rebase on latest master

[Xarbirus]

Finally the work is finished😊