[CMake] Add a linker test for -Bsymbolic-functions to AddLLVM (#79539)

Add a linker test for -Bsymbolic-functions to AddLLVM and remove
the illumos hardcoded bits for its handling. OpenBSD also has a
local patch for linking with the old BFD linker on mips64 and
sparc64.

Author: brad0

clang/tools/clang-shlib/CMakeLists.txt

@@ -57,7 +57,7 @@ endif()
 
 # Optimize function calls for default visibility definitions to avoid PLT and
 # reduce dynamic relocations.
-if (NOT APPLE AND NOT MINGW AND NOT CYGWIN AND NOT LLVM_LINKER_IS_SOLARISLD_ILLUMOS)
+if (NOT APPLE AND LLVM_LINKER_SUPPORTS_B_SYMBOLIC_FUNCTIONS)
   target_link_options(clang-cpp PRIVATE LINKER:-Bsymbolic-functions)
 endif()
 if (MINGW OR CYGWIN)

llvm/cmake/modules/AddLLVM.cmake

@@ -257,12 +257,6 @@ if (NOT DEFINED LLVM_LINKER_DETECTED AND NOT WIN32)
       set(LLVM_LINKER_DETECTED YES CACHE INTERNAL "")
       set(LLVM_LINKER_IS_GNULD YES CACHE INTERNAL "")
       message(STATUS "Linker detection: GNU ld")
-    elseif("${stderr}" MATCHES "(illumos)" OR
-           "${stdout}" MATCHES "(illumos)")
-      set(LLVM_LINKER_DETECTED YES CACHE INTERNAL "")
-      set(LLVM_LINKER_IS_SOLARISLD YES CACHE INTERNAL "")
-      set(LLVM_LINKER_IS_SOLARISLD_ILLUMOS YES CACHE INTERNAL "")
-      message(STATUS "Linker detection: Solaris ld (illumos)")
     elseif("${stderr}" MATCHES "Solaris Link Editors" OR
            "${stdout}" MATCHES "Solaris Link Editors")
       set(LLVM_LINKER_DETECTED YES CACHE INTERNAL "")
@@ -296,6 +290,7 @@ if (NOT DEFINED LLVM_LINKER_DETECTED AND NOT WIN32)
 endif()
 
 function(add_link_opts target_name)
+  include(CheckLinkerFlag)
   get_llvm_distribution(${target_name} in_distribution in_distribution_var)
   if(NOT in_distribution)
     # Don't LTO optimize targets that aren't part of any distribution.
@@ -327,7 +322,6 @@ function(add_link_opts target_name)
       elseif(${CMAKE_SYSTEM_NAME} MATCHES "SunOS" AND LLVM_LINKER_IS_SOLARISLD)
         # Support for ld -z discard-unused=sections was only added in
         # Solaris 11.4.  GNU ld ignores it, but warns every time.
-        include(CheckLinkerFlag)
         check_linker_flag(CXX "-Wl,-z,discard-unused=sections" LINKER_SUPPORTS_Z_DISCARD_UNUSED)
         if (LINKER_SUPPORTS_Z_DISCARD_UNUSED)
           set_property(TARGET ${target_name} APPEND_STRING PROPERTY
@@ -355,6 +349,12 @@ function(add_link_opts target_name)
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-brtl")
   endif()
+
+  # Check for existence of symbolic functions flag. Not supported
+  # by the older BFD linker (such as on some OpenBSD archs), the
+  # MinGW driver for LLD, and the Solaris native linker.
+  check_linker_flag(CXX "-Wl,-Bsymbolic-functions"
+                    LLVM_LINKER_SUPPORTS_B_SYMBOLIC_FUNCTIONS)
 endfunction(add_link_opts)
 
 # Set each output directory according to ${CMAKE_CONFIGURATION_TYPES}.

llvm/tools/llvm-shlib/CMakeLists.txt

@@ -70,7 +70,7 @@ if(LLVM_BUILD_LLVM_DYLIB)
         # Solaris ld does not accept global: *; so there is no way to version *all* global symbols
         set(LIB_NAMES -Wl,--version-script,${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map ${LIB_NAMES})
       endif()
-      if (NOT MINGW AND NOT LLVM_LINKER_IS_SOLARISLD_ILLUMOS)
+      if (LLVM_LINKER_SUPPORTS_B_SYMBOLIC_FUNCTIONS)
         # Optimize function calls for default visibility definitions to avoid PLT and
         # reduce dynamic relocations.
         # Note: for -fno-pic default, the address of a function may be different from