libstdc++: Prevent std::stacktrace from using atomics on arm-eabi [PR120567]HEADtrunkmaster

The conftest.cc in GLIBCXX_ENABLE_BACKTRACE checks if calls to
__atomic_load and __atomic_store result in libatomic calls. For arm-eabi
those expand to normal loads with a call to __sync_synchronize to ensure
correct ordering. That means the generated assembly does not match the
grep pattern "__atomic_" and so configure incorrectly assumes we can use
atomics in libbacktrace.

The fix is to grep for "__atomic_|__sync_" instead of just "__atomic_".

As explained in the bug comments, the similar grep for "__atomic_" in
the GLIBCXX_ENABLE_ATOMIC_BUILTINS macro doesn't need the same change.
That conftest.cc program does emit a call to a libatomic function that
matches the grep pattern "__atomic_" so the test gives the right answer
for arm-eabi.

libstdc++-v3/ChangeLog:

	PR libstdc++/120567
	* acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): Include "__sync_" in
	grep command to check for extern calls to libatomic.
	* configure: Regenerate.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

0 files changed, 0 insertions, 0 deletions