Make wasi-nn backends as separated shared libraries (#3509)

- All files under *core/iwasm/libraries/wasi-nn* are compiled as shared libraries
- *wasi-nn.c* is shared between backends
- Every backend has a separated shared library
- If wasi-nn feature is enabled, iwasm will depend on shared library libiwasm.so
  instead of linking static library libvmlib.a

product-mini/platforms/linux/CMakeLists.txt

@@ -123,6 +123,18 @@ if (WAMR_BUILD_DEBUG_INTERP EQUAL 1)
   set (WAMR_BUILD_SIMD 0)
 endif ()
 
+# if enable wasi-nn, both wasi-nn-backends and iwasm
+# need to use same WAMR (dynamic) libraries
+if (WAMR_BUILD_WASI_NN EQUAL 1)
+  set (WAMR_BUILD_SHARED 1)
+endif ()
+
+if (NOT DEFINED WAMR_BUILD_SHARED)
+  set (WAMR_BUILD_SHARED 0)
+elseif (WAMR_BUILD_SHARED EQUAL 1)
+  message ("build WAMR as shared libraries")
+endif ()
+
 set (WAMR_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 
 include (${WAMR_ROOT_DIR}/build-scripts/runtime_lib.cmake)
@@ -160,9 +172,16 @@ add_executable (iwasm main.c ${UNCOMMON_SHARED_SOURCE})
 
 set_target_properties (iwasm PROPERTIES POSITION_INDEPENDENT_CODE ON)
 
-install (TARGETS iwasm DESTINATION bin)
+target_link_libraries(iwasm
+  $<$<BOOL:${WAMR_BUILD_SHARED}>:libiwasm> $<$<NOT:$<BOOL:${WAMR_BUILD_SHARED}>>:vmlib>
+  ${LLVM_AVAILABLE_LIBS}
+  ${UV_A_LIBS}
+  -lm
+  -ldl
+  -lpthread
+)
 
-target_link_libraries (iwasm vmlib ${LLVM_AVAILABLE_LIBS} ${UV_A_LIBS} ${WASI_NN_LIBS} -lm -ldl -lpthread)
+install (TARGETS iwasm DESTINATION bin)
 
 add_library (libiwasm SHARED ${WAMR_RUNTIME_LIB_SOURCE})
 
@@ -170,4 +189,4 @@ install (TARGETS libiwasm DESTINATION lib)
 
 set_target_properties (libiwasm PROPERTIES OUTPUT_NAME iwasm)
 
-target_link_libraries (libiwasm ${LLVM_AVAILABLE_LIBS} ${UV_A_LIBS} ${WASI_NN_LIBS} -lm -ldl -lpthread)
+target_link_libraries (libiwasm ${LLVM_AVAILABLE_LIBS} ${UV_A_LIBS} -lm -ldl -lpthread)

product-mini/platforms/posix/main.c

@@ -295,7 +295,8 @@ load_native_lib(const char *name)
     /* open the native library */
     if (!(lib->handle = dlopen(name, RTLD_NOW | RTLD_GLOBAL))
         && !(lib->handle = dlopen(name, RTLD_LAZY))) {
-        LOG_WARNING("warning: failed to load native library %s", name);
+        LOG_WARNING("warning: failed to load native library %s. %s", name,
+                    dlerror());
         goto fail;
     }