From 65fc11a49ec939261ca9a3dbfa534a9c3354825e Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sun, 8 Jun 2014 16:13:17 +0200
Subject: Add ENABLE_LTO cmake option

Tested with GCC and clang; unlikely to work with other toolchains, so it's
disabled by default.
---
 cmake/CMakeFindBinUtils.cmake                 |  8 +++++---
 cmake/checks.cmake                            | 15 +++++++++++++++
 cmake/config.cmake                            |  2 ++
 src/CMakeLists.txt                            |  4 ++--
 src/crypto/mac/ghash/pclmulqdq/CMakeLists.txt |  2 +-
 5 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/cmake/CMakeFindBinUtils.cmake b/cmake/CMakeFindBinUtils.cmake
index 83d1a4e..753577a 100644
--- a/cmake/CMakeFindBinUtils.cmake
+++ b/cmake/CMakeFindBinUtils.cmake
@@ -1,5 +1,7 @@
-find_program(CMAKE_AR NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-ar HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
-find_program(CMAKE_NM NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-nm HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
-find_program(CMAKE_RANLIB NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-ranlib HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+if(CMAKE_COMPILER_IS_GNUCC)
+  find_program(CMAKE_AR NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-ar HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+  find_program(CMAKE_NM NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-nm HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+  find_program(CMAKE_RANLIB NAMES ${_CMAKE_TOOLCHAIN_PREFIX}gcc-ranlib HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+endif(CMAKE_COMPILER_IS_GNUCC)
 
 include(${CMAKE_ROOT}/Modules/CMakeFindBinUtils.cmake)
diff --git a/cmake/checks.cmake b/cmake/checks.cmake
index 225c443..62d10d0 100644
--- a/cmake/checks.cmake
+++ b/cmake/checks.cmake
@@ -9,6 +9,21 @@ if(ARCH_X86 OR ARCH_X86_64)
   check_c_compiler_flag("-mpclmul" HAVE_PCLMUL)
 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/cmake/config.cmake b/cmake/config.cmake
index e08955e..e77abc8 100644
--- a/cmake/config.cmake
+++ b/cmake/config.cmake
@@ -23,6 +23,8 @@ set(WITH_CAPABILITIES ${LINUX} CACHE BOOL "Include support for POSIX capabilitie
 set(ENABLE_LIBSODIUM TRUE CACHE BOOL "Use libsodium instead of NaCl")
 set(ENABLE_OPENSSL FALSE CACHE BOOL "Enable crypto implementations using OpenSSL")
 
+set(ENABLE_LTO FALSE CACHE BOOL "Enable link-time optimization")
+
 if(LINUX)
   set(ENABLE_SYSTEMD TRUE CACHE BOOL "Enable systemd support")
 endif(LINUX)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9802883..792d9cb 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,5 +1,5 @@
 set_directory_properties(PROPERTIES COMPILE_DEFINITIONS _GNU_SOURCE)
-set(FASTD_CFLAGS "-pthread -std=c99 ${UECC_CFLAGS_OTHER} ${NACL_CFLAGS_OTHER} ${OPENSSL_CRYPTO_CFLAGS_OTHER} -Wall")
+set(FASTD_CFLAGS "-pthread -std=c99 ${UECC_CFLAGS_OTHER} ${NACL_CFLAGS_OTHER} ${OPENSSL_CRYPTO_CFLAGS_OTHER} ${CFLAGS_LTO} -Wall")
 
 include_directories(${FASTD_SOURCE_DIR} ${FASTD_BINARY_DIR}/src)
 link_directories(${UECC_LIBRARY_DIRS} ${NACL_LIBRARY_DIRS} ${OPENSSL_CRYPTO_LIBRARY_DIRS})
@@ -43,7 +43,7 @@ add_executable(fastd
   ${BISON_fastd_config_parse_OUTPUTS}
 )
 set_property(TARGET fastd PROPERTY COMPILE_FLAGS "${FASTD_CFLAGS}")
-set_property(TARGET fastd PROPERTY LINK_FLAGS "-pthread ${UECC_LDFLAGS_OTHER} ${NACL_LDFLAGS_OTHER} ${OPENSSL_CRYPTO_LDFLAGS_OTHER}")
+set_property(TARGET fastd PROPERTY LINK_FLAGS "-pthread ${UECC_LDFLAGS_OTHER} ${NACL_LDFLAGS_OTHER} ${OPENSSL_CRYPTO_LDFLAGS_OTHER} ${LDFLAGS_LTO}")
 set_property(TARGET fastd APPEND PROPERTY INCLUDE_DIRECTORIES ${CAP_INCLUDE_DIR} ${NACL_INCLUDE_DIRS})
 target_link_libraries(fastd protocols methods ciphers macs ${RT_LIBRARY} ${CAP_LIBRARY} ${UECC_LIBRARIES} ${NACL_LIBRARIES} ${OPENSSL_CRYPTO_LIBRARIES})
 
diff --git a/src/crypto/mac/ghash/pclmulqdq/CMakeLists.txt b/src/crypto/mac/ghash/pclmulqdq/CMakeLists.txt
index f96f680..f3b407e 100644
--- a/src/crypto/mac/ghash/pclmulqdq/CMakeLists.txt
+++ b/src/crypto/mac/ghash/pclmulqdq/CMakeLists.txt
@@ -3,7 +3,7 @@ if(ARCH_X86 OR ARCH_X86_64)
     ghash_pclmulqdq.c
     ghash_pclmulqdq_impl.c
     )
-  fastd_mac_impl_compile_flags(ghash pclmulqdq ghash_pclmulqdq_impl.c "-mssse3 -mpclmul")
+  fastd_mac_impl_compile_flags(ghash pclmulqdq ghash_pclmulqdq_impl.c "-mssse3 -mpclmul ${CFLAGS_NO_LTO}")
 
   if(WITH_MAC_GHASH_PCLMULQDQ AND NOT HAVE_PCLMUL)
     message(FATAL_ERROR "WITH_MAC_GHASH_PCLMULQDQ enabled, but there is no compiler support for -mpclmul")
-- 
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