[cmake] move SONAME handling to llvm_add_library

[axw]

Summary

Move handling of the SONAME option from add_llvm_library
to llvm_add_library, so that it can be used in sub-projects.
In particular, this makes it possible to have consistently
named shared libraries for LLVM, Clang and LLDB.

Also, base the SONAME and symlinks on the output name
by extracting the OUTPUT_NAME property, rather than assuming
it is the same as the target name.

[beanz]

LGTM.

cmake/modules/AddLLVM.cmake

if(ARG_MODULE OR ARG_SHARED)
     # macros.
     set_target_properties( ${name} PROPERTIES DEFINE_SYMBOL "" )
 
     if (LLVM_EXPORTED_SYMBOL_FILE)
       add_llvm_symbol_exports( ${name} ${LLVM_EXPORTED_SYMBOL_FILE} )
     endif()
   endif()
 
+  if(ARG_SHARED AND UNIX)
+    if(NOT APPLE AND ARG_SONAME)
+      get_target_property(output_name ${name} OUTPUT_NAME)
+      if(${output_name} STREQUAL "output_name-NOTFOUND")
+        set(output_name ${name})
+      endif()
+      set(library_name ${output_name}-${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}${LLVM_VERSION_SUFFIX})
+      set(api_name ${output_name}-${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}${LLVM_VERSION_SUFFIX})
+      set_target_properties(${name} PROPERTIES OUTPUT_NAME ${library_name})
+      llvm_install_library_symlink(${api_name} ${library_name} SHARED
+        COMPONENT ${name}
+        ALWAYS_GENERATE)
+      llvm_install_library_symlink(${output_name} ${library_name} SHARED
+        COMPONENT ${name}
+        ALWAYS_GENERATE)
+    endif()
+  endif()
+
   # Add the explicit dependency information for this library.
   #
   # It would be nice to verify that we have the dependencies for this library
   # name, but using get_property(... SET) doesn't suffice to determine if a
   # property has been set to an empty value.
   get_property(lib_deps GLOBAL PROPERTY LLVMBUILD_LIB_DEPS_${name})
 
   if (LLVM_LINK_LLVM_DYLIB AND NOT ARG_STATIC AND NOT ARG_DISABLE_LLVM_LINK_LLVM_DYLIB)
if(LLVM_COMMON_DEPENDS)
     foreach(objlib ${objlibs})
       add_dependencies(${objlib} ${LLVM_COMMON_DEPENDS})
     endforeach()
   endif()
 endfunction()
 
 macro(add_llvm_library name)
   cmake_parse_arguments(ARG
-    "SHARED;SONAME"
+    "SHARED"
     ""
     ""
     ${ARGN})
   if( BUILD_SHARED_LIBS )
     llvm_add_library(${name} SHARED ${ARGN})
   else()
     llvm_add_library(${name} ${ARGN})
   endif()
if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "LTO")
 
       if (NOT CMAKE_CONFIGURATION_TYPES)
         add_custom_target(install-${name}
                           DEPENDS ${name}
                           COMMAND "${CMAKE_COMMAND}"
                                   -DCMAKE_INSTALL_COMPONENT=${name}
                                   -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")
       endif()
-      if(ARG_SHARED AND UNIX)
-        if(NOT APPLE AND ARG_SONAME)
-          set(library_name ${name}-${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}${LLVM_VERSION_SUFFIX})
-          set(api_name ${name}-${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}${LLVM_VERSION_SUFFIX})
-          set_target_properties(${name} PROPERTIES OUTPUT_NAME ${library_name})
-          llvm_install_library_symlink(${api_name} ${library_name} SHARED
-            COMPONENT ${name}
-            ALWAYS_GENERATE)
-          llvm_install_library_symlink(${name} ${library_name} SHARED
-            COMPONENT ${name}
-            ALWAYS_GENERATE)
-        endif()
-      endif()
     endif()
     set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${name})
   endif()
   set_target_properties(${name} PROPERTIES FOLDER "Libraries")
 endmacro(add_llvm_library name)
 
 macro(add_llvm_loadable_module name)
   llvm_add_library(${name} MODULE ${ARGN})