From: Viktor Szakats Date: Mon, 19 Jan 2026 11:34:59 +0000 (+0100) Subject: cmake: add `CURL_DROP_UNUSED` option to reduce binary sizes X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=66ad54e46b934e17e786e10e0292fa6f1f3fa816;p=thirdparty%2Fcurl.git cmake: add `CURL_DROP_UNUSED` option to reduce binary sizes To enable known linker options dropping unused, dead, code and data from the executables built. Useful to reduce binary sizes for curl, libcurl shared lib and apps linking static libcurl. It's effective on both "unity" and non-unity builds. Aligning "unity" build sizes with default, non-unity ones. Supported platforms: Apple, MSVC, llvm/clang and GCC on all tested platforms: Linux, BSDs, Windows, MSYS2/Cygwin, Android, MS-DOS. Notes: - Static libraries grow 20-30% with non-Apple toolchains. This effect is controlled by separate, optional compiler flags on non-Apple. This patch enables them automatically for public binaries (libcurl and curl tool), and leaves them off for internal/test ones. - MSVC enables this option by default for 'Release' configurations. The curl build option has no effect on it. - Observed effect on VS2010 is negligible. VS2012+ is recommended. - Works with LTO, Fil-C. - No observed/conclusive effect on build speed. - On Windows with clang/gcc (mingw-w64/MSYS2/Cygwin) it also enables `-fno-asynchronous-unwind-tables` as a workaround to make the toolchain options actually work. Ref: https://sourceware.org/bugzilla/show_bug.cgi?id=11539 Thanks-to: Andarwinux Also: - GHA: enable in Linux and MinGW jobs to test it. Size changes: - linux aws-lc H3: curl: 2000000 -> 1937152, libcurl.a: 2065724 -> 2716532 bytes - macos clang HTTP-only: curl: 1364376 -> 128799 bytes, libcurl.a: unchanged - macos llvm MultiSSL: curl: 410056 -> 405720, libcurl.dylib: 1350336 -> 1348480 bytes - mingw schannel c-ares U: curl: 1588736 -> 1507328, libcurl-d.a: 3322040 -> 3884746 bytes bld: 34 -> 35MB - GHA: enable in MSVC and Apple jobs to reduce disk footprint, with no obvious downside. Size changes: - AppVeyor CI VS2019: curl: 2339840 -> 1295872, libcurl-d.dll: 3155968 -> 1900544 bytes bld: 161 -> 97MB - AppVeyor CI VS2022 clang-cl: curl: 2933248 -> 2332160, libcurl-d.lib: 4762688 -> 5511330 bytes bld: 133 -> 121MB - AppVeyor CI VS2022 HTTP-only: curl: 3514368 -> 2177024, libcurl-d.lib: 2538420 -> 3151740 bytes bld: 137 -> 83MB - GHA intel: curl: 2629120 -> 2023424, libcurl-d.lib: 4366652 -> 5350670 bytes bld: 86 -> 69MB - GHA arm64: curl: 2832896 -> 2063872, libcurl-d.lib: 4690616 -> 5597250 bytes bld: 82 -> 66MB Refs: https://maskray.me/blog/2021-02-28-linker-garbage-collection https://web.archive.org/web/20110811230637/msdn.microsoft.com/en-us/library/bxwfs976.aspx (VS2010) https://learn.microsoft.com/cpp/build/reference/opt-optimizations https://learn.microsoft.com/cpp/build/reference/gy-enable-function-level-linking Closes #20357 --- diff --git a/.github/workflows/http3-linux.yml b/.github/workflows/http3-linux.yml index a1465f6d4a..5a9e1fdd9e 100644 --- a/.github/workflows/http3-linux.yml +++ b/.github/workflows/http3-linux.yml @@ -389,7 +389,7 @@ jobs: tflags: '--min=1790' generate: >- -DOPENSSL_ROOT_DIR=/home/runner/awslc/build -DUSE_NGTCP2=ON -DBUILD_SHARED_LIBS=OFF - -DCMAKE_UNITY_BUILD=ON + -DCMAKE_UNITY_BUILD=ON -DCURL_DROP_UNUSED=ON - name: 'boringssl' install_steps: skipall diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml index 52492695c3..4ed36b6741 100644 --- a/.github/workflows/linux.yml +++ b/.github/workflows/linux.yml @@ -121,7 +121,7 @@ jobs: tflags: '--min=830 1 to 950' LDFLAGS: -Wl,-rpath,/home/runner/mbedtls/lib PKG_CONFIG_PATH: /home/runner/mbedtls/lib/pkgconfig - generate: -DCURL_USE_MBEDTLS=ON -DENABLE_DEBUG=ON -DCURL_USE_GSSAPI=ON + generate: -DCURL_USE_MBEDTLS=ON -DENABLE_DEBUG=ON -DCURL_USE_GSSAPI=ON -DCURL_DROP_UNUSED=ON - name: 'mbedtls gss valgrind 2' install_packages: libnghttp2-dev libidn2-dev libldap-dev libgss-dev valgrind @@ -163,7 +163,7 @@ jobs: - name: 'awslc' install_packages: libidn2-dev install_steps: awslc - generate: -DOPENSSL_ROOT_DIR=/home/runner/awslc -DUSE_ECH=ON -DCMAKE_UNITY_BUILD=OFF + generate: -DOPENSSL_ROOT_DIR=/home/runner/awslc -DUSE_ECH=ON -DCMAKE_UNITY_BUILD=OFF -DCURL_DROP_UNUSED=ON - name: 'boringssl' install_steps: boringssl pytest diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml index 754d9f6a23..443828146f 100644 --- a/.github/workflows/macos.yml +++ b/.github/workflows/macos.yml @@ -151,7 +151,7 @@ jobs: # https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling-for-ios-tvos-visionos-or-watchos [ -n "${MATRIX_GENERATOR}" ] && options="-G ${MATRIX_GENERATOR}" cmake -B bld -G Ninja -D_CURL_PREFILL=ON \ - -DCMAKE_UNITY_BUILD=ON -DCURL_WERROR=ON \ + -DCMAKE_UNITY_BUILD=ON -DCURL_DROP_UNUSED=ON -DCURL_WERROR=ON \ -DCMAKE_SYSTEM_NAME=iOS \ -DUSE_APPLE_IDN=ON \ ${MATRIX_GENERATE} ${options} @@ -417,7 +417,7 @@ jobs: [ "${_chkprefill}" = '_chkprefill' ] && options+=' -D_CURL_PREFILL=OFF' cmake -B "bld${_chkprefill}" -G Ninja -D_CURL_PREFILL=ON \ -DCMAKE_INSTALL_PREFIX="$HOME"/curl-install \ - -DCMAKE_UNITY_BUILD=ON -DCURL_WERROR=ON \ + -DCMAKE_UNITY_BUILD=ON -DCURL_DROP_UNUSED=ON -DCURL_WERROR=ON \ -DCMAKE_OSX_SYSROOT="${sysroot}" \ -DCMAKE_C_COMPILER_TARGET="$(uname -m | sed 's/arm64/aarch64e/')-apple-darwin$(uname -r)" \ ${MATRIX_GENERATE} ${options} @@ -652,7 +652,7 @@ jobs: [ -n "${MATRIX_MACOS_VERSION_MIN}" ] && options+=" -DCMAKE_OSX_DEPLOYMENT_TARGET=${MATRIX_MACOS_VERSION_MIN}" # would pick up nghttp2, libidn2, and libssh2 cmake -B bld -G Ninja -D_CURL_PREFILL=ON \ - -DCMAKE_UNITY_BUILD=ON -DCURL_WERROR=ON \ + -DCMAKE_UNITY_BUILD=ON -DCURL_DROP_UNUSED=ON -DCURL_WERROR=ON \ -DCMAKE_OSX_SYSROOT="${sysroot}" \ -DCMAKE_C_COMPILER_TARGET="$(uname -m | sed 's/arm64/aarch64e/')-apple-darwin$(uname -r)" \ -DCMAKE_IGNORE_PREFIX_PATH=/opt/homebrew \ diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml index 94602febdb..ed25d58e04 100644 --- a/.github/workflows/windows.yml +++ b/.github/workflows/windows.yml @@ -204,7 +204,7 @@ jobs: # MinGW - { build: 'autotools', sys: 'mingw64' , env: 'x86_64' , tflags: 'skiprun' , config: '--enable-debug --with-openssl --disable-threaded-resolver --enable-static --without-zlib', install: 'mingw-w64-x86_64-openssl mingw-w64-x86_64-libssh2', name: 'default' } - { build: 'autotools', sys: 'mingw64' , env: 'x86_64' , tflags: '' , config: '--enable-debug --with-openssl --enable-windows-unicode --enable-ares --enable-static --disable-shared --enable-ca-native', install: 'mingw-w64-x86_64-c-ares mingw-w64-x86_64-openssl mingw-w64-x86_64-nghttp3 mingw-w64-x86_64-libssh2', name: 'c-ares U' } - - { build: 'cmake' , sys: 'mingw64' , env: 'x86_64' , tflags: '--min=1650', config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_ARES=ON', install: 'mingw-w64-x86_64-c-ares mingw-w64-x86_64-libssh2', type: 'Debug', name: 'schannel c-ares U' } + - { build: 'cmake' , sys: 'mingw64' , env: 'x86_64' , tflags: '--min=1650', config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_ARES=ON -DCURL_DROP_UNUSED=ON', install: 'mingw-w64-x86_64-c-ares mingw-w64-x86_64-libssh2', type: 'Debug', name: 'schannel c-ares U' } # MinGW torture - { build: 'cmake' , sys: 'mingw64' , env: 'x86_64' , tflags: '-t --shallow=13 --min=700 1 to 950' , config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_ARES=ON', install: 'mingw-w64-x86_64-c-ares mingw-w64-x86_64-libssh2', type: 'Debug', name: 'schannel U torture 1' } - { build: 'cmake' , sys: 'mingw64' , env: 'x86_64' , tflags: '-t --shallow=13 --min=700 951 to 9999', config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DENABLE_ARES=ON', install: 'mingw-w64-x86_64-c-ares mingw-w64-x86_64-libssh2', type: 'Debug', name: 'schannel U torture 2' } @@ -213,7 +213,7 @@ jobs: # Windows. Do not use this component till there is a fix for these. # https://github.com/curl/curl-for-win/blob/3951808deb04df9489ee17430f236ed54436f81a/libssh.sh#L6-L8 - { build: 'cmake' , sys: 'clang64' , env: 'clang-x86_64' , tflags: '' , config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_GNUTLS=ON -DENABLE_UNICODE=OFF -DUSE_NGTCP2=ON -DCURL_USE_LIBSSH2=OFF -DCURL_USE_LIBSSH=ON', install: 'mingw-w64-clang-x86_64-gnutls mingw-w64-clang-x86_64-nghttp3 mingw-w64-clang-x86_64-ngtcp2 mingw-w64-clang-x86_64-libssh', type: 'Debug', name: 'gnutls libssh' } - - { build: 'cmake' , sys: 'clangarm64', env: 'clang-aarch64', tflags: 'skiprun' , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON', install: 'mingw-w64-clang-aarch64-libssh2', type: 'Release', name: 'schannel R', image: 'windows-11-arm' } + - { build: 'cmake' , sys: 'clangarm64', env: 'clang-aarch64', tflags: 'skiprun' , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON -DCURL_USE_SCHANNEL=ON -DENABLE_UNICODE=ON -DCURL_DROP_UNUSED=ON', install: 'mingw-w64-clang-aarch64-libssh2', type: 'Release', name: 'schannel R', image: 'windows-11-arm' } - { build: 'cmake' , sys: 'clang64' , env: 'clang-x86_64' , tflags: 'skiprun' , config: '-DENABLE_DEBUG=ON -DBUILD_SHARED_LIBS=OFF -DCURL_USE_OPENSSL=ON -DENABLE_UNICODE=OFF -DUSE_NGTCP2=ON', install: 'mingw-w64-clang-x86_64-openssl mingw-w64-clang-x86_64-nghttp3 mingw-w64-clang-x86_64-ngtcp2 mingw-w64-clang-x86_64-libssh2', type: 'Release', name: 'openssl', chkprefill: '_chkprefill' } - { build: 'cmake' , sys: 'ucrt64' , env: 'ucrt-x86_64' , tflags: 'skiprun' , config: '-DENABLE_DEBUG=OFF -DBUILD_SHARED_LIBS=ON -DCURL_USE_OPENSSL=ON', install: 'mingw-w64-ucrt-x86_64-openssl mingw-w64-ucrt-x86_64-libssh2', type: 'Release', test: 'uwp', name: 'schannel' } # { build: 'autotools', sys: 'ucrt64' , env: 'ucrt-x86_64' , tflags: 'skiprun' , config: '--without-debug --with-schannel --disable-static', install: 'mingw-w64-ucrt-x86_64-libssh2', type: 'Release', test: 'uwp', name: 'schannel' } @@ -528,6 +528,7 @@ jobs: -DCMAKE_C_COMPILER=gcc \ -DCMAKE_BUILD_TYPE="${MATRIX_TYPE}" \ -DCMAKE_UNITY_BUILD=ON -DCMAKE_UNITY_BUILD_BATCH_SIZE=30 \ + -DCURL_DROP_UNUSED=ON \ -DCURL_WERROR=ON \ -DUSE_LIBIDN2=OFF \ ${MATRIX_CONFIG} @@ -891,6 +892,7 @@ jobs: -DCMAKE_EXE_LINKER_FLAGS="-INCREMENTAL:NO ${ldflags}" \ -DCMAKE_SHARED_LINKER_FLAGS="-INCREMENTAL:NO ${ldflags}" \ -DCMAKE_UNITY_BUILD=ON \ + -DCURL_DROP_UNUSED=ON \ -DCURL_WERROR=ON \ -DLIBPSL_INCLUDE_DIR="${MINGW_PREFIX}/include" \ -DLIBPSL_LIBRARY="${MINGW_PREFIX}/lib/libpsl.dll.a" \ diff --git a/CMakeLists.txt b/CMakeLists.txt index 20cd74542b..e2b93389ee 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -300,6 +300,40 @@ if(CURL_CODE_COVERAGE) endif() endif() +set(CURL_CFLAGS "") # C flags set for libcurl and curl tool (aka public binaries) only + +option(CURL_DROP_UNUSED "Drop unused code and data from built binaries" OFF) +if(CURL_DROP_UNUSED OR TRUE) + if(APPLE) + if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13) + set_property(DIRECTORY APPEND PROPERTY LINK_OPTIONS "-Wl,-dead_strip") + else() + set_property(DIRECTORY APPEND PROPERTY LINK_FLAGS "-Wl,-dead_strip") + endif() + elseif(MSVC) # Options below are toolchain defaults in Release configurations. + # This option does not seem to have an effect with VS2010: + if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13) + set_property(DIRECTORY APPEND PROPERTY LINK_OPTIONS "-OPT:REF") + else() + set_property(DIRECTORY APPEND PROPERTY LINK_FLAGS "-OPT:REF") + endif() + # Optional, but reduces binary size further, with the cost of larger objects/static libraries: + list(APPEND CURL_CFLAGS "-Gy") + elseif(CMAKE_C_COMPILER_ID STREQUAL "GNU" OR CMAKE_C_COMPILER_ID MATCHES "Clang") + if(WIN32) + # To make -Wl,--gc-sections work on Windows: https://sourceware.org/bugzilla/show_bug.cgi?id=11539 + set_property(DIRECTORY APPEND PROPERTY COMPILE_OPTIONS "-fno-asynchronous-unwind-tables") + endif() + if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13) + set_property(DIRECTORY APPEND PROPERTY LINK_OPTIONS "-Wl,--gc-sections") + else() + set_property(DIRECTORY APPEND PROPERTY LINK_FLAGS "-Wl,--gc-sections") + endif() + # Optional, but reduces binary size further, with the cost of larger objects/static libraries: + list(APPEND CURL_CFLAGS "-ffunction-sections" "-fdata-sections") + endif() +endif() + # For debug libs and exes, add "-d" postfix if(NOT DEFINED CMAKE_DEBUG_POSTFIX) set(CMAKE_DEBUG_POSTFIX "-d") diff --git a/appveyor.sh b/appveyor.sh index 0701127c26..e98fe2f613 100644 --- a/appveyor.sh +++ b/appveyor.sh @@ -87,6 +87,7 @@ if [ -n "${CMAKE_GENERATOR:-}" ]; then time cmake -G "${CMAKE_GENERATOR}" \ -DENABLE_DEBUG=ON -DCURL_WERROR=ON \ -DCURL_STATIC_CRT=ON \ + -DCURL_DROP_UNUSED=ON \ -DCURL_USE_SCHANNEL=ON -DCURL_USE_LIBPSL=OFF \ ${CMAKE_GENERATE:-} \ ${options} \ diff --git a/docs/INSTALL-CMAKE.md b/docs/INSTALL-CMAKE.md index c446832544..63c9f3103e 100644 --- a/docs/INSTALL-CMAKE.md +++ b/docs/INSTALL-CMAKE.md @@ -243,6 +243,7 @@ target_link_libraries(my_target PRIVATE CURL::libcurl) - `CURL_LIBCURL_VERSIONED_SYMBOLS_PREFIX`: Override default versioned symbol prefix. Default: `_` or `MULTISSL_` - `CURL_LINT`: Run lint checks while building. Default: `OFF` - `CURL_LTO`: Enable compiler Link Time Optimizations. Default: `OFF` +- `CURL_DROP_UNUSED`: Drop unused code and data from built binaries. Default: `OFF` - `CURL_STATIC_CRT`: Build libcurl with static CRT with MSVC (`/MT`) (requires UCRT, static libcurl or no curl executable). Default: `OFF` - `CURL_TARGET_WINDOWS_VERSION`: Minimum target Windows version as hex string. - `CURL_WERROR`: Turn compiler warnings into errors. Default: `OFF` diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt index 0f842f0cc1..174f3b7450 100644 --- a/lib/CMakeLists.txt +++ b/lib/CMakeLists.txt @@ -111,6 +111,7 @@ if(SHARE_LIB_OBJECT AND CMAKE_VERSION VERSION_GREATER_EQUAL 3.12) target_link_libraries(${LIB_OBJECT} PRIVATE ${CURL_LIBS}) set_target_properties(${LIB_OBJECT} PROPERTIES POSITION_INDEPENDENT_CODE ON) + set_property(TARGET ${LIB_OBJECT} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAGS}") if(CURL_HIDES_PRIVATE_SYMBOLS) set_property(TARGET ${LIB_OBJECT} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAG_SYMBOLS_HIDE}") set_property(TARGET ${LIB_OBJECT} APPEND PROPERTY COMPILE_DEFINITIONS "CURL_HIDDEN_SYMBOLS") @@ -152,6 +153,7 @@ if(BUILD_STATIC_LIBS) PREFIX "" OUTPUT_NAME "${LIBCURL_OUTPUT_NAME}" SUFFIX "${STATIC_LIB_SUFFIX}${CMAKE_STATIC_LIBRARY_SUFFIX}" INTERFACE_COMPILE_DEFINITIONS "CURL_STATICLIB") + set_property(TARGET ${LIB_STATIC} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAGS}") if(CURL_HIDES_PRIVATE_SYMBOLS) set_property(TARGET ${LIB_STATIC} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAG_SYMBOLS_HIDE}") set_property(TARGET ${LIB_STATIC} APPEND PROPERTY COMPILE_DEFINITIONS "CURL_HIDDEN_SYMBOLS") @@ -213,6 +215,7 @@ if(BUILD_SHARED_LIBS) PREFIX "" OUTPUT_NAME "${LIBCURL_OUTPUT_NAME}" IMPORT_PREFIX "" IMPORT_SUFFIX "${IMPORT_LIB_SUFFIX}${CMAKE_IMPORT_LIBRARY_SUFFIX}" POSITION_INDEPENDENT_CODE ON) + set_property(TARGET ${LIB_SHARED} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAGS}") if(CURL_HIDES_PRIVATE_SYMBOLS) set_property(TARGET ${LIB_SHARED} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAG_SYMBOLS_HIDE}") set_property(TARGET ${LIB_SHARED} APPEND PROPERTY COMPILE_DEFINITIONS "CURL_HIDDEN_SYMBOLS") diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt index 6d3d6e3d48..519a3b491e 100644 --- a/src/CMakeLists.txt +++ b/src/CMakeLists.txt @@ -105,6 +105,7 @@ set_property(DIRECTORY APPEND PROPERTY INCLUDE_DIRECTORIES add_executable(${EXE_NAME} ${CURL_CFILES} ${CURL_HFILES} ${_curl_cfiles_gen} ${_curl_hfiles_gen} ${CURLX_CFILES} ${CURLX_HFILES}) target_compile_definitions(${EXE_NAME} PRIVATE ${_curl_definitions}) target_link_libraries(${EXE_NAME} ${LIB_SELECTED_FOR_EXE} ${CURL_LIBS}) +set_property(TARGET ${EXE_NAME} APPEND PROPERTY COMPILE_OPTIONS "${CURL_CFLAGS}") add_executable(${PROJECT_NAME}::${EXE_NAME} ALIAS ${EXE_NAME})