Messages in this thread |  | | Subject | Re: Linux 2.4.10-pre11 -- __builtin_expect | From | Andreas Schwab <> | Date | 27 Sep 2001 14:51:44 +0200 |
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James Antill <james@and.org> writes:
|> Andi Kleen <ak@suse.de> writes: |> |> > Good point. I somehow assumed that __builtin_expect would just signify |> > a boolean, but if I read gcc source correctly this was wrong. |> |> Yeh, it's a long so you'll get no cast warnings too. |> |> > Here is an updated patch. |> |> [snip ... ] |> |> > --- include/linux/kernel.h-LIKELY Tue Sep 18 11:12:20 2001 |> > +++ include/linux/kernel.h Tue Sep 18 14:35:17 2001 |> > @@ -171,4 +171,14 @@ |> > char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */ |> > }; |> > |> > + |> > +/* This loses on a few early 2.96 snapshots, but hopefully nobody uses them anymore. */ |> > +#if __GNUC__ > 2 || (__GNUC__ == 2 && _GNUC_MINOR__ == 96) |> > +#define likely(x) __builtin_expect(!!(x), 1) |> > +#define unlikely(x) __builtin_expect((x), 0) |> |> unlikely() also needs to be... |> |> #define unlikely(x) __builtin_expect(!(x), 1) |> |> ...or... |> |> #define unlikely(x) __builtin_expect(!!(x), 0)
This is not needed, since only 0 is the likely value and !! does not change that.
Andreas.
-- Andreas Schwab "And now for something Andreas.Schwab@suse.de completely different." SuSE Labs, SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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