Messages in this thread |  | | Date | Thu, 02 Nov 2000 13:14:49 +0100 | From | Martin Dalecki <> | Subject | Re: 2.4.0-test10-pre6: Use of abs() |
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Richard Henderson wrote: > > On Wed, Nov 01, 2000 at 09:46:19AM -0500, tytso@mit.edu wrote: > > What versions of gcc produce the built-in functions? > > 2.95 and previous. In 2.96 somewhere we fixed a bug that > automatically prototypes these builtin functions for you; > ie with current code you get an undeclared function warning. > > > And does it do so for *all* platforms? (i.e., PPC, Alpha, > > IA64, etc., etc., etc.) > > Yes. The thing about abs, though, is that it's "int abs(int)" > which does naughty things with longs on 64-bit targets. You're > much better off writing (x < 0 ? -x : x) directly.
Thank's for answering it... I was already looking up the GCC source for an exact answer ;-). However what's the difference in respect of optimization between unrolling the abs function by hand and relying on the built in? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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