use vmmlaq_s32 for compile option i8mm check

Author: chaxu01

ggml/src/ggml-cpu/CMakeLists.txt

@@ -99,21 +99,36 @@ if (CMAKE_OSX_ARCHITECTURES      STREQUAL "arm64" OR
         set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_PREV})
     elseif (APPLE)
         if (GGML_NATIVE)
-            set(MARCH_FLAGS "-march=armv8.2a")
+            set(USER_PROVIDED_MARCH FALSE)
+            foreach(flag_var IN ITEMS CMAKE_C_FLAGS CMAKE_CXX_FLAGS CMAKE_REQUIRED_FLAGS)
+                if ("${${flag_var}}" MATCHES "-march=[a-zA-Z0-9+._-]+")
+                    set(USER_PROVIDED_MARCH TRUE)
+                    break()
+                endif()
+            endforeach()
 
-            check_cxx_source_compiles("#include <arm_neon.h>\nint main() { int8x16_t _a, _b; int32x4_t _s = vdotq_s32(_s, _a, _b); return 0; }" GGML_COMPILER_SUPPORT_DOTPROD)
-            if (GGML_COMPILER_SUPPORT_DOTPROD)
-                set(MARCH_FLAGS "${MARCH_FLAGS}+dotprod")
-                add_compile_definitions(__ARM_FEATURE_DOTPROD)
-            endif ()
+            if (NOT USER_PROVIDED_MARCH)
+                set(MARCH_FLAGS "-march=armv8.2a")
 
-            check_cxx_source_compiles("#include <arm_neon.h>\nint main() { int8x16_t _a, _b; int32x4_t _s = vmlaq_f32(_s, _a, _b); return 0; }" GGML_COMPILER_SUPPORT_MATMUL_INT8)
-            if (GGML_COMPILER_SUPPORT_MATMUL_INT8)
-                add_compile_definitions(__ARM_FEATURE_MATMUL_INT8)
-                set(MARCH_FLAGS "${MARCH_FLAGS}+i8mm")
-            endif ()
+                check_cxx_source_compiles("#include <arm_neon.h>\nint main() { int8x16_t _a, _b; int32x4_t _s = vdotq_s32(_s, _a, _b); return 0; }" GGML_COMPILER_SUPPORT_DOTPROD)
+                if (GGML_COMPILER_SUPPORT_DOTPROD)
+                    set(MARCH_FLAGS "${MARCH_FLAGS}+dotprod")
+                    add_compile_definitions(__ARM_FEATURE_DOTPROD)
+                endif ()
 
-            list(APPEND ARCH_FLAGS "${MARCH_FLAGS}")
+                set(TEST_I8MM_FLAGS "-march=armv8.2a+i8mm")
+
+                set(CMAKE_REQUIRED_FLAGS_SAVE ${CMAKE_REQUIRED_FLAGS})
+                set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} ${TEST_I8MM_FLAGS}")
+                check_cxx_source_compiles("#include <arm_neon.h>\nint main() { int8x16_t _a, _b; int32x4_t _s = vmmlaq_s32(_s, _a, _b); return 0; }" GGML_COMPILER_SUPPORT_MATMUL_INT8)
+                if (GGML_COMPILER_SUPPORT_MATMUL_INT8)
+                    set(MARCH_FLAGS "${MARCH_FLAGS}+i8mm")
+                    add_compile_definitions(__ARM_FEATURE_MATMUL_INT8)
+                endif ()
+                set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS_SAVE})
+
+                list(APPEND ARCH_FLAGS "${MARCH_FLAGS}")
+            endif ()
         endif ()
     else()
         check_cxx_compiler_flag(-mfp16-format=ieee COMPILER_SUPPORTS_FP16_FORMAT_I3E)