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SubjectRe: [patch] string.h speedup, cld-2.3.30-A1
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Henrik Olsen <henrik@iaeste.dk> writes:

|> On Sat, 27 Nov 1999, Linus Torvalds wrote:
|> > On Sat, 27 Nov 1999, Oliver Xymoron wrote:
|> > > On Sat, 27 Nov 1999, Ingo Molnar wrote:
|> > >
|> > > > much of the remaining 284 cld's is still unjustified, because '*a = *b;'
|> > > > type of structure copies are inlined by GCC. (GCC generates a cld because
|> > > > user-space has to be prepared to be interrupted by uncooperative signal
|> > > > handlers and the like).
|> > >
|> > > What!? A signal handler can change flags? Then there's a lot more for GCC
|> > > to worry about than the direction flag..
|> >
|> > A normal signal handler cannot change flags, because they will obviously
|> > be restored on signal exit.
|> >
|> > However, I'm not sure that "longjmp()" does the same. You'd have to check
|> > libc souces to see if setjmp saves the flags..
|> >
|> > Linus
|> Libc longjmp() does, glibc longjmp() doesn't.

The flags are considered call clobbered, so setjmp does not save them.

--
Andreas Schwab "And now for something
SuSE Labs completely different."
schwab@suse.de
SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg

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