[llvm] r200695 - Don't use -ffunction-sections if -fno-function-sections is not supported in the compiler.

[Evgeniy Stepanov]

Author: eugenis
Date: Mon Feb  3 07:57:09 2014
New Revision: 200695

URL: http://llvm.org/viewvc/llvm-project?rev=200695&view=rev
Log:
Don't use -ffunction-sections if -fno-function-sections is not supported in the compiler.

This will disable -ffunction-sections in older versions of Clang where it
breaks build of sanitizer runtime library.

Modified:
    llvm/trunk/cmake/modules/HandleLLVMOptions.cmake

Modified: llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/modules/HandleLLVMOptions.cmake?rev=200695&r1=200694&r2=200695&view=diff
==============================================================================
--- llvm/trunk/cmake/modules/HandleLLVMOptions.cmake (original)
+++ llvm/trunk/cmake/modules/HandleLLVMOptions.cmake Mon Feb  3 07:57:09 2014
@@ -350,13 +350,23 @@ if (UNIX AND
   append("-fcolor-diagnostics" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 
+# Clang prior to 3.5 ignored -fno-function-sections.
+# It's pretty hard to test directly, so we rely on the version number.
+if( ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") AND (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.5) )
+  set(LLVM_COMPILER_HAS_BROKEN_FNO_FUNCTION_SECTIONS ON)
+endif()
+
 # Add flags for add_dead_strip().
 # FIXME: With MSVS, consider compiling with /Gy and linking with /OPT:REF?
 # But MinSizeRel seems to add that automatically, so maybe disable these
 # flags instead if LLVM_NO_DEAD_STRIP is set.
 if(NOT CYGWIN AND NOT WIN32)
   if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-    append("-ffunction-sections -fdata-sections" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+    # Don't add -ffunction-section if it can be disabled with -fno-function-sections.
+    # Doing so will break sanitizers.
+    if (NOT LLVM_COMPILER_HAS_BROKEN_FNO_FUNCTION_SECTIONS)
+      append("-ffunction-sections -fdata-sections" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+    endif()
   endif()
 endif()