[CMake] When disabling PIC, also pass -fno-pie when linking if it is supported.

Building clang with -fno-pie generates slightly faster code. In my not-very-rigorous testing I saw about a 4% speed up using the clang test-suite sources.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253959 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index c984a19e85f56811501158082feb291a5f45d304..4b342bc586bee2432ef8a1ba4f3410a394f50ae3 100755 (executable)
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -299,6 +299,10 @@ if( LLVM_ENABLE_PIC )
   set(ENABLE_PIC 1)
 else()
   set(ENABLE_PIC 0)
   set(ENABLE_PIC 1)
 else()
   set(ENABLE_PIC 0)

+  check_cxx_compiler_flag("-fno-pie" SUPPORTS_NO_PIE_FLAG)
+  if(SUPPORTS_NO_PIE_FLAG)
+    list(APPEND CMAKE_EXE_LINKER_FLAGS "-fno-pie")
+  endif()

 endif()
 
 check_cxx_compiler_flag("-Wno-variadic-macros" SUPPORTS_NO_VARIADIC_MACROS_FLAG)
 endif()
 
 check_cxx_compiler_flag("-Wno-variadic-macros" SUPPORTS_NO_VARIADIC_MACROS_FLAG)