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Diffstat (limited to 'eclass/dot-a.eclass')
| -rw-r--r-- | eclass/dot-a.eclass | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/eclass/dot-a.eclass b/eclass/dot-a.eclass new file mode 100644 index 000000000000..f82e5da5be89 --- /dev/null +++ b/eclass/dot-a.eclass @@ -0,0 +1,119 @@ +# Copyright 2025 Gentoo Authors +# Distributed under the terms of the GNU General Public License v2 + +# @ECLASS: dot-a.eclass +# @MAINTAINER: +# Toolchain Ninjas <toolchain@gentoo.org> +# @AUTHOR: +# Sam James <sam@gentoo.org> +# Eli Schwartz <eschwartz@gentoo.org> +# @SUPPORTED_EAPIS: 8 +# @BLURB: Functions to handle stripping LTO bytecode out of static archives. +# @DESCRIPTION: +# This eclass provides functions to strip LTO bytecode out of static archives +# (.a files). +# +# Static libraries when built with LTO will contain LTO bytecode which is +# not portable across compiler versions or compiler vendors. To avoid pessimising +# the library and always filtering LTO, we can build it with -ffat-lto-objects +# instead, which builds some components twice. The installed part will then +# have the LTO contents stripped out, leaving the regular objects in the +# static archive. +# +# Use should be passing calling lto-guarantee-fat before configure-time +# and calling strip-lto-bytecode after installation. +# +# Most packages installing static libraries should be using this eclass, +# though it's not strictly necessary if the package filters LTO. +# +# @EXAMPLE: +# @CODE +# +# inherit dot-a +# +# src_configure() { +# lto-guarantee-fat +# econf +# } +# +# src_install() { +# default +# strip-lto-bytecode +# } +case ${EAPI} in + 8) ;; + *) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;; +esac + +if [[ -z ${_DOT_A_ECLASS} ]] ; then +_DOT_A_ECLASS=1 + +inherit flag-o-matic toolchain-funcs + +# TODO: QA check + +# @FUNCTION: lto-guarantee-fat +# @DESCRIPTION: +# If LTO is enabled, appends -ffat-lto-objects or any other flags needed +# to provide fat LTO objects. +lto-guarantee-fat() { + tc-is-lto || return + + # We add this for all languages as LTO obviously can't be done + # if different compilers are used for e.g. C vs C++ anyway. + append-flags $(test-flags-CC -ffat-lto-objects) +} + +# @FUNCTION: strip-lto-bytecode +# @USAGE: [library|directory] [...] +# @DESCRIPTION: +# Strips LTO bytecode from libraries (static archives) passed as arguments. +# Defaults to operating on ${ED} as a whole if no arguments are passed. +# +# As an optimisation, if USE=static-libs exists for a package and is disabled, +# the default-searching behaviour with no arguments is suppressed. +strip-lto-bytecode() { + tc-is-lto || return + + local files=() + + if [[ ${#} -eq 0 ]]; then + if ! in_iuse static-libs || use static-libs ; then + # maybe we are USE=static-libs. Alternatively, maybe the ebuild doesn't + # offer such a choice. In both cases, the user specified the function, + # so we expect to be called on *something*, but nothing was explicitly + # passed. Try scanning ${ED} automatically. + set -- "${ED}" + else + return + fi + fi + + mapfile -t -d '' files < <(find -H "${@}" -type f \( -name '*.a' -or -name '*.o' \) -print0) + + toolchain_type= + tc-is-gcc && toolchain_type=gnu + tc-is-clang && toolchain_type=llvm + + local file + for file in "${files[@]}" ; do + case ${toolchain_type} in + gnu) + $(tc-getSTRIP) \ + -R .gnu.lto_* \ + -R .gnu.debuglto_* \ + -N __gnu_lto_v1 \ + "${file}" || die "Stripping bytecode in ${file} failed" + ;; + llvm) + llvm-bitcode-strip \ + -r "${file}" \ + -o "${file}" || die "Stripping bytecode in ${file} failed" + ;; + *) + ;; + esac + done +} + +fi |