buildroot

From: Alexander Dahl <alex@netz39.de>

Date: Wed, 28 Oct 2015 16:04:13 +0100

Subject: [PATCH] cmake: use INTERPROCEDURAL_OPTIMIZATION target property

​

Instead of hacking on compiler flags use the cmake way for handling

interprocedural optimization. Tests showed cmake currently ignores this

for gcc and clang, at least on Debian Wheezy and Jessie. This actually

results in no interprocedural optimization for the moment. However it

allows to compile fastd against a toolchain without LTO support, which

was broken because of a hack included here for finding binutils.

​

According to the upstream author of fastd the main reason for enabling

LTO was binary size on an OpenWRT target for Freifunk Gluon, where they

have very few space left on devices with only 4 MB flash memory.

​

Signed-off-by: Alexander Dahl <post@lespocky.de>

---

 cmake/checks.cmake | 14 --------------

 src/CMakeLists.txt |  9 +++++++++

 2 files changed, 9 insertions(+), 14 deletions(-)

​

diff --git a/cmake/checks.cmake b/cmake/checks.cmake

index 27c073f..8a671a1 100644

--- a/cmake/checks.cmake

+++ b/cmake/checks.cmake

@@ -10,20 +10,6 @@ if(ARCH_X86 OR ARCH_X86_64)

 endif(ARCH_X86 OR ARCH_X86_64)

-

-if(ENABLE_LTO)

-  set(CFLAGS_LTO "-flto")

-  set(CFLAGS_NO_LTO "-fno-lto")

-

-  check_c_compiler_flag("-fwhole-program" HAVE_FLAG_WHOLE_PROGRAM)

-  if(HAVE_FLAG_WHOLE_PROGRAM)

-    set(LDFLAGS_LTO "-flto -fwhole-program")

-  else(HAVE_FLAG_WHOLE_PROGRAM)

-    set(LDFLAGS_LTO "-flto")

-  endif(HAVE_FLAG_WHOLE_PROGRAM)

-endif(ENABLE_LTO)

-

-

 check_c_source_compiles("

 #include <sys/types.h>

 #include <sys/socket.h>

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt

index 829b3ab..7612b40 100644

--- a/src/CMakeLists.txt

+++ b/src/CMakeLists.txt

@@ -48,6 +48,15 @@ add_executable(fastd

 set_property(TARGET fastd PROPERTY COMPILE_FLAGS "${FASTD_CFLAGS}")

 set_property(TARGET fastd PROPERTY LINK_FLAGS "${PTHREAD_LDFLAGS} ${LIBUECC_LDFLAGS_OTHER} ${NACL_LDFLAGS_OTHER} ${JSON_C_LDFLAGS_OTHER} ${LDFLAGS_LTO}")

 set_property(TARGET fastd APPEND PROPERTY INCLUDE_DIRECTORIES ${LIBCAP_INCLUDE_DIR} ${NACL_INCLUDE_DIRS} ${JSON_C_INCLUDE_DIR})

+if(ENABLE_LTO)

+   set_target_properties(fastd PROPERTIES

+       INTERPROCEDURAL_OPTIMIZATION ON

+   )

+else(ENABLE_LTO)

+   set_target_properties(fastd PROPERTIES

+       INTERPROCEDURAL_OPTIMIZATION OFF

+   )

+endif(ENABLE_LTO)

 target_link_libraries(fastd protocols methods ciphers macs ${RT_LIBRARY} ${LIBCAP_LIBRARY} ${LIBUECC_LIBRARIES} ${NACL_LIBRARIES} ${OPENSSL_CRYPTO_LIBRARY} ${JSON_C_LIBRARIES})

 add_dependencies(fastd version)

-- 

2.1.4

​