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authorTobias Hieta <tobias@plex.tv>2020-01-09 12:10:55 +0100
committerDaniel Stenberg <daniel@haxx.se>2020-01-13 23:14:49 +0100
commit4ccf7622db04af58442c460b8091b952585de5c7 (patch)
tree7451edcf604d1703661c28eea1238ef73402ef72
parentf128c00a99ffb7482740f3579f42f5e026a1ee74 (diff)
CMake: Add support for CMAKE_LTO option.
This enables Link Time Optimization. LTO is a proven technique for optimizing across compilation units. Closes #4799
-rw-r--r--CMakeLists.txt18
-rw-r--r--lib/CMakeLists.txt6
-rw-r--r--src/CMakeLists.txt6
3 files changed, 30 insertions, 0 deletions
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3ef8d0e48..a8be8a332 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -80,6 +80,7 @@ if(WIN32)
option(CURL_STATIC_CRT "Set to ON to build libcurl with static CRT on Windows (/MT)." OFF)
option(ENABLE_INET_PTON "Set to OFF to prevent usage of inet_pton when building against modern SDKs while still requiring compatibility with older Windows versions, such as Windows XP, Windows Server 2003 etc." ON)
endif()
+option(CURL_LTO "Turn on compiler Link Time Optimizations" OFF)
cmake_dependent_option(ENABLE_THREADED_RESOLVER "Set to ON to enable threaded DNS lookup"
ON "NOT ENABLE_ARES"
@@ -1165,6 +1166,23 @@ if(CURL_WERROR)
endif()
endif()
+if(CURL_LTO)
+ if(CMAKE_VERSION VERSION_LESS 3.9)
+ message(FATAL_ERROR "Requested LTO but your cmake version ${CMAKE_VERSION} is to old. You need at least 3.9")
+ endif()
+
+ cmake_policy(SET CMP0069 NEW)
+
+ include(CheckIPOSupported)
+ check_ipo_supported(RESULT CURL_HAS_LTO OUTPUT CURL_LTO_ERROR LANGUAGES C)
+ if(CURL_HAS_LTO)
+ message(STATUS "LTO supported and enabled")
+ else()
+ message(FATAL_ERROR "LTO was requested - but compiler doesn't support it\n${CURL_LTO_ERROR}")
+ endif()
+endif()
+
+
# Ugly (but functional) way to include "Makefile.inc" by transforming it (= regenerate it).
function(transform_makefile_inc INPUT_FILE OUTPUT_FILE)
file(READ ${INPUT_FILE} MAKEFILE_INC_TEXT)
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index a9c90b665..e73efb90a 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -96,6 +96,12 @@ endif()
set_target_properties(${LIB_NAME} PROPERTIES PREFIX "")
set_target_properties(${LIB_NAME} PROPERTIES IMPORT_PREFIX "")
+if(CURL_HAS_LTO)
+ set_target_properties(${LIB_NAME} PROPERTIES
+ INTERPROCEDURAL_OPTIMIZATION_RELEASE TRUE
+ INTERPROCEDURAL_OPTIMIZATION_RELWITHDEBINFO TRUE)
+endif()
+
if(WIN32)
if(BUILD_SHARED_LIBS)
# Add "_imp" as a suffix before the extension to avoid conflicting with the statically linked "libcurl.lib"
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 63e2b943d..054541e40 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -46,6 +46,12 @@ add_executable(
${CURL_FILES}
)
+if(CURL_HAS_LTO)
+ set_target_properties(${EXE_NAME} PROPERTIES
+ INTERPROCEDURAL_OPTIMIZATION_RELEASE TRUE
+ INTERPROCEDURAL_OPTIMIZATION_RELWITHDEBINFO TRUE)
+endif()
+
source_group("curlX source files" FILES ${CURLX_CFILES})
source_group("curl source files" FILES ${CURL_CFILES})
source_group("curl header files" FILES ${CURL_HFILES})