James Almer: > > > On 1/19/2022 8:54 AM, Anton Khirnov wrote: >> C11 atomics in some configurations (e.g. 64bit operations on ppc64 with >> GCC) require linking to libatomic. >> --- >> Testing welcome, especially in configurations where >> * libatomic is not present >> * libatomic is actually needed >> --- >> configure | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/configure b/configure >> index 1413122d87..1ff5dbee5b 100755 >> --- a/configure >> +++ b/configure >> @@ -6324,7 +6324,14 @@ check_headers asm/types.h >> # it seems there are versions of clang in some distros that try to >> use the >> # gcc headers, which explodes for stdatomic >> # so we also check that atomics actually work here >> -check_builtin stdatomic stdatomic.h "atomic_int foo, bar = >> ATOMIC_VAR_INIT(-1); atomic_store(&foo, 0); foo += bar" >> +# >> +# some configurations also require linking to libatomic, so try >> +# both with -latomic and without >> +for LATOMIC in "-latomic" ""; do > > Shouldn't you try without it first? On my toolchain libatomic is > present, but libraries compile without linking to it just fine. That > changes after this patch, where it starts linking to it explicitly. >
This would work if this test checked for all the atomic operations that might be needed; but it doesn't: It checks just for atomic increment and only for atomic_int. What is if atomic_increment can be done without recourse to libatomic because of hardware support whereas another atomic operation needs libatomic? >> + check_builtin stdatomic >> stdatomic.h \ >> + "atomic_int foo, bar = ATOMIC_VAR_INIT(-1); >> atomic_store(&foo, 0); foo += bar" \ >> + $LATOMIC && add_extralibs $LATOMIC && break > > You should probably add it to the required libraries' extralibs only. > Just replace the add_extralibs part with setting stdatomic_extralibs to > $LATOMIC, and then add stdatomic to all the libraries' _suggest lists, > same as we do for libm. > >> +done >> check_lib advapi32 "windows.h" RegCloseKey >> -ladvapi32 >> check_lib bcrypt "windows.h bcrypt.h" BCryptGenRandom >> -lbcrypt && _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
