This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH, i386]: Insert "cld" via optimize mode switching
On Mon, Dec 04, 2006 at 02:53:28PM +0100, Paolo Bonzini wrote:
> this is not an atomic pair anyway. If the ABI does not require that DF
> be cleared on exit from a subroutine, then there is no guarantee that a
> signal handler occurring between the cld and "rep movsb" doesn't set the
> direction flag.
Please do not confuse "on exit from a subroutine" and "after a signal
handler". Any OS worth its salt ought to restore this flag after
exiting a signal handler, whether by taking advantage of an ABI or
restoring it from an internal saved copy; this is a non-issue.
%eflags is saved in the GNU/Linux signal handler frame; I can't speak
for other OS's directly, but...
--
Daniel Jacobowitz
CodeSourcery