diff options
Diffstat (limited to 'eclass/flag-o-matic.eclass')
| -rw-r--r-- | eclass/flag-o-matic.eclass | 80 |
1 files changed, 19 insertions, 61 deletions
diff --git a/eclass/flag-o-matic.eclass b/eclass/flag-o-matic.eclass index 5ce7601fdde2..0e5271c7824f 100644 --- a/eclass/flag-o-matic.eclass +++ b/eclass/flag-o-matic.eclass @@ -1015,69 +1015,27 @@ test-compile() { } # @FUNCTION: append-atomic-flags -# @USAGE: [bytes] # @DESCRIPTION: -# Attempts to detect if appending -latomic is required to use -# a specific-sized atomic intrinsic, and if so, appends it. If the bytesize -# is not specified, then check the four most common byte sizes (1, 2, 4, 8). -# >=16-byte atomics are not included in this default set and must be explicitly -# passed if required. This may require you to add a macro definition like -# -Duint128_t=__uint128_t to your CFLAGS. +# Attempts to detect if appending -latomic works, and does so. append-atomic-flags() { - # this implementation is as described in bug #820101 - local code - - # first, ensure we can compile a trivial program - # this is because we can't distinguish if test-compile - # fails because -latomic is actually needed or if we have a - # broken toolchain (like due to bad FLAGS) - read -r -d '' code <<- EOF - int main(void) - { - return 0; - } - EOF - - # if toolchain is broken, just return silently. it's better to - # let other pieces of the build fail later down the line than to - # make people think that something to do with atomic support is the - # cause of their problems. - test-compile "c+ld" "${code}" || return - - local bytesizes - [[ "${#}" == "0" ]] && bytesizes=( "1" "2" "4" "8" ) || bytesizes="${@}" - - for bytesize in ${bytesizes[@]} - do - # this sample program is informed by the great testing from the buildroot project: - # https://github.com/buildroot/buildroot/commit/6856e417da4f3aa77e2a814db2a89429af072f7d - read -r -d '' code <<- EOF - #include <stdint.h> - int main(void) - { - uint$((${bytesize} * 8))_t a = 0; - __atomic_add_fetch(&a, 3, __ATOMIC_RELAXED); - __atomic_compare_exchange_n(&a, &a, 2, 1, __ATOMIC_RELAXED, __ATOMIC_RELAXED); - return 0; - } - EOF - - # do nothing if test program links fine - test-compile "c+ld" "${code}" && continue - - # ensure that the toolchain supports -latomic - test-flags-CCLD "-latomic" &>/dev/null || die "-latomic is required but not supported by $(tc-getCC)" - - append-libs "-latomic" - - # verify that this did indeed fix the problem - test-compile "c+ld" "${code}" || \ - die "libatomic does not include an implementation of ${bytesize}-byte atomics for this toolchain" - - # if any of the required bytesizes require -latomic, no need to continue - # checking the others - return - done + # Make sure that the flag is actually valid. If it isn't, then maybe the + # library both doesn't exist and is redundant, or maybe the toolchain is + # broken, but let the build succeed or fail on its own. + test-flags-CCLD "-latomic" &>/dev/null || return + + # We unconditionally append this flag. In the case that it's needed, the + # flag is, well, needed. In the case that it's not needed, it causes no + # harm, because we ensure that this specific library is definitely + # certainly linked with as-needed. + # + # Really, this should be implemented directly in the compiler, including + # the use of push/pop for as-needed. It's exactly what the gcc spec file + # does for e.g. -lgcc_s, but gcc is concerned about doing so due to build + # system internals and as a result all users have to deal with this mess + # instead. + # + # See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81358 + append-libs "-Wl,--push-state,--as-needed,-latomic,--pop-state" } fi |