Prior to version 3.3 cmake would always use -rdynamic. That in itself
causes all the internal symbols to be exported, increasing the binaries
by 5-10% and making it impossible for the compiler to reason, optimise
and discard unused code.
The -rdynamic is useful in two cases:
- having a third party module (say /usr/lib/foo/foobar.so) which is
underlinked and depends on symbols from the main binary - apps like
irssi, bash and zsh use that
- uses the glibc backtrace, which relies on dlopen/dlsym to fetch the
symbol data. Unwind is much better solution, since it replies on the
DWARF data
Our binaries do not use either of these - so drop the -rdynamic. The
autotools build doesn't use it either.
text data bss dec hex filename
229000 2120 4424 235544 39818 bsdcat -- before
208324 2120 4424 214868 34754 bsdcat -- after
1093939 12128 24176
1130243 113f03 bsdcpio -- before
1059181 12128 24176
1095485 10b73d bsdcpio -- after
1130091 14264 6608
1150963 118ff3 bsdtar -- before
1093690 14264 6608
1114562 1101c2 bsdtar -- after
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
#
CMAKE_MINIMUM_REQUIRED(VERSION 2.8.12 FATAL_ERROR)
+if(POLICY CMP0065)
+ cmake_policy(SET CMP0065 NEW) #3.4 don't use `-rdynamic` with executables
+endif()
if(POLICY CMP0074)
cmake_policy(SET CMP0074 NEW) #3.12.0 `find_package()`` uses ``<PackageName>_ROOT`` variables.
endif()