diff options
author | Alexandru Croitor <alexandru.croitor@qt.io> | 2021-12-16 13:25:43 +0100 |
---|---|---|
committer | Qt Cherry-pick Bot <cherrypick_bot@qt-project.org> | 2022-01-21 03:05:42 +0000 |
commit | 086dcd151f8cb492e20555700c840b5bed6f8c83 (patch) | |
tree | ae0b6abe8f0b9486d5ea1ae0645972fb28e0273d | |
parent | 3b83168eb878a68d89a60618717a6f9aff9d4b60 (diff) |
CMake: Add support building Qt with the 'mold' linker
The mold linker is a new linker for Linux that provides faster link
times compared to BFD ld, ld.gold and lld.
It can be found at https://github.com/rui314/mold
To build Qt with mold, ensure that the binary in your PATH and then
configure Qt with with either
cmake /path/to/qtbase -DINPUT_linker=mold
or
/path/to/qtbase/configure --linker mold
The change was tested with gcc 9, clang 10, clang 12, mold
1.0.0. Only qtbase and qtdeclarative (and dependencies) were tested.
Task-number: QTBUG-99270
Change-Id: I2e64a1f4257c37ff5b64a9326e548b9b46e07c80
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 158287c726b9ee7031c6e832dc159d02473e34d7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
-rw-r--r-- | cmake/QtFeature.cmake | 59 | ||||
-rw-r--r-- | configure.cmake | 30 | ||||
-rw-r--r-- | qt_cmdline.cmake | 2 |
3 files changed, 89 insertions, 2 deletions
diff --git a/cmake/QtFeature.cmake b/cmake/QtFeature.cmake index 3ade942f17..bca31660b9 100644 --- a/cmake/QtFeature.cmake +++ b/cmake/QtFeature.cmake @@ -1118,6 +1118,62 @@ function(qt_config_compiler_supports_flag_test name) set(TEST_${name} "${TEST_${name}}" CACHE INTERNAL "${label}") endfunction() +# gcc expects -fuse-ld=mold (no absolute path can be given) (gcc >= 12.1) +# or an 'ld' symlink to 'mold' in a dir that is passed via -B flag (gcc < 12.1) +# +# clang expects -fuse-ld=mold +# or -fuse-ld=<mold-abs-path> +# or --ldpath=<mold-abs-path> (clang >= 12) +# https://github.com/rui314/mold/#how-to-use +# TODO: In the gcc < 12.1 case, the qt_internal_check_if_linker_is_available(mold) check will +# always return TRUE because gcc will not error out if it is given a -B flag pointing to an +# invalid dir, as well as when the the symlink to the linker in the -B dir is not actually +# a valid linker. +# It would be nice to handle that case in a better way, but it's not that important +# given that gcc > 12.1 now supports -fuse-ld=mold +# NOTE: In comparison to clang, in the gcc < 12.1 case, we pass the full path to where mold is +# and that is recorded in PlatformCommonInternal's INTERFACE_LINK_OPTIONS target. +# Moving such a Qt to a different machine and trying to build another repo won't +# work because the recorded path will be invalid. This is not a problem with +# the gcc >= 12.1 case +function(qt_internal_get_mold_linker_flags out_var) + cmake_parse_arguments(PARSE_ARGV 1 arg "ERROR_IF_EMPTY" "" "") + + find_program(QT_INTERNAL_LINKER_MOLD mold) + + set(flag "") + if(QT_INTERNAL_LINKER_MOLD) + if(GCC) + if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "12.1") + set(flag "-fuse-ld=mold") + else() + set(mold_linker_dir "${CMAKE_CURRENT_BINARY_DIR}/.qt_linker") + set(mold_linker_path "${mold_linker_dir}/ld") + if(NOT EXISTS "${mold_linker_dir}") + file(MAKE_DIRECTORY "${mold_linker_dir}") + endif() + if(NOT EXISTS "${mold_linker_path}") + file(CREATE_LINK + "${QT_INTERNAL_LINKER_MOLD}" + "${mold_linker_path}" + SYMBOLIC) + endif() + set(flag "-B${mold_linker_dir}") + endif() + elseif(CLANG) + if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "12") + set(flag "--ld-path=mold") + else() + set(flag "-fuse-ld=mold") + endif() + endif() + endif() + if(arg_ERROR_IS_EMPTY AND NOT flag) + message(FATAL_ERROR "Could not determine the flags to use the mold linker.") + endif() + set(${out_var} "${flag}" PARENT_SCOPE) +endfunction() + function(qt_internal_get_active_linker_flags out_var) set(flags "") if(GCC OR CLANG) @@ -1127,6 +1183,9 @@ function(qt_internal_get_active_linker_flags out_var) list(APPEND flags "-fuse-ld=bfd") elseif(QT_FEATURE_use_lld_linker) list(APPEND flags "-fuse-ld=lld") + elseif(QT_FEATURE_use_mold_linker) + qt_internal_get_mold_linker_flags(mold_flags ERROR_IF_EMPTY) + list(APPEND flags "${mold_flags}") endif() endif() set(${out_var} "${flags}" PARENT_SCOPE) diff --git a/configure.cmake b/configure.cmake index 6cb93ad918..2818db7281 100644 --- a/configure.cmake +++ b/configure.cmake @@ -39,6 +39,18 @@ qt_internal_check_if_linker_is_available(use_lld_linker FLAG "-fuse-ld=lld" ) +# We set an invalid flag as a default flag so the compile test fails +# in case if no mold is found in PATH. +set(__qt_internal_mold_linker_flags "-Wl,-invalid-flag") +if(NOT QT_CONFIGURE_RUNNING) + qt_internal_get_mold_linker_flags(__qt_internal_mold_linker_flags) +endif() +qt_internal_check_if_linker_is_available(use_mold_linker + LABEL "mold linker" + FLAG "${__qt_internal_mold_linker_flags}" + ) +unset(__qt_internal_mold_linker_flags) + qt_feature("use_bfd_linker" PRIVATE LABEL "bfd" @@ -46,6 +58,7 @@ qt_feature("use_bfd_linker" CONDITION NOT WIN32 AND NOT INTEGRITY AND NOT WASM AND TEST_use_bfd_linker ENABLE INPUT_linker STREQUAL 'bfd' DISABLE INPUT_linker STREQUAL 'gold' OR INPUT_linker STREQUAL 'lld' + OR INPUT_linker STREQUAL 'mold' ) qt_feature_config("use_bfd_linker" QMAKE_PRIVATE_CONFIG) @@ -60,6 +73,7 @@ qt_feature("use_gold_linker" CONDITION NOT WIN32 AND NOT INTEGRITY AND NOT WASM AND NOT rtems AND TEST_use_gold_linker ENABLE INPUT_linker STREQUAL 'gold' OR QT_FEATURE_use_gold_linker_alias DISABLE INPUT_linker STREQUAL 'bfd' OR INPUT_linker STREQUAL 'lld' + OR INPUT_linker STREQUAL 'mold' ) qt_feature_config("use_gold_linker" QMAKE_PRIVATE_CONFIG) @@ -70,14 +84,27 @@ qt_feature("use_lld_linker" CONDITION NOT WIN32 AND NOT INTEGRITY AND NOT WASM AND TEST_use_lld_linker ENABLE INPUT_linker STREQUAL 'lld' DISABLE INPUT_linker STREQUAL 'bfd' OR INPUT_linker STREQUAL 'gold' + OR INPUT_linker STREQUAL 'mold' ) qt_feature_config("use_lld_linker" QMAKE_PRIVATE_CONFIG) +qt_feature("use_mold_linker" + PRIVATE + LABEL "mold" + AUTODETECT FALSE + CONDITION NOT WIN32 AND NOT INTEGRITY AND NOT WASM AND TEST_use_mold_linker + ENABLE INPUT_linker STREQUAL 'mold' + DISABLE INPUT_linker STREQUAL 'bfd' OR INPUT_linker STREQUAL 'gold' + OR INPUT_linker STREQUAL 'lld' +) +qt_feature_config("use_mold_linker" QMAKE_PRIVATE_CONFIG) + if(NOT QT_CONFIGURE_RUNNING) qt_evaluate_feature(use_bfd_linker) qt_evaluate_feature(use_gold_linker_alias) qt_evaluate_feature(use_gold_linker) qt_evaluate_feature(use_lld_linker) + qt_evaluate_feature(use_mold_linker) endif() @@ -1004,9 +1031,10 @@ qt_configure_add_summary_entry( ) qt_configure_add_summary_entry( TYPE "firstAvailableFeature" - ARGS "use_bfd_linker use_gold_linker use_lld_linker" + ARGS "use_bfd_linker use_gold_linker use_lld_linker use_mold_linker" MESSAGE "Linker" CONDITION QT_FEATURE_use_bfd_linker OR QT_FEATURE_use_gold_linker OR QT_FEATURE_use_lld_linker + OR QT_FEATURE_use_mold_linker ) qt_configure_add_summary_entry( ARGS "enable_new_dtags" diff --git a/qt_cmdline.cmake b/qt_cmdline.cmake index ce9889045c..737cd9710b 100644 --- a/qt_cmdline.cmake +++ b/qt_cmdline.cmake @@ -63,7 +63,7 @@ qt_commandline_option(gui TYPE boolean) qt_commandline_option(headersclean TYPE boolean) qt_commandline_option(incredibuild-xge TYPE boolean NAME incredibuild_xge) qt_commandline_option(libudev TYPE boolean) -qt_commandline_option(linker TYPE optionalString VALUES bfd gold lld) +qt_commandline_option(linker TYPE optionalString VALUES bfd gold lld mold) qt_commandline_option(ltcg TYPE boolean) # special case begin qt_commandline_option(make TYPE addString VALUES examples libs tests tools |