Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: GCC 3.4 Heads-up | Date | 25 Dec 2003 23:07:35 -0800 |
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Followup to: <20031226005840.A30827@hexapodia.org> By author: Andy Isaacson <adi@hexapodia.org> In newsgroup: linux.dev.kernel > > On Thu, Dec 25, 2003 at 08:34:33PM -0800, Linus Torvalds wrote: > > The cast/conditional expression as lvalue are _particularly_ ugly > > extensions, since there is absolutely zero point to them. They are very > > much against what C is all about, and writing something like this: > > > > a ? b : c = d; > > > > is something that only a high-level language person could have come up > > with. The _real_ way to do this in C is to just do > > > > *(a ? &b : &c) = d; > > > > which is portable C, does the same thing, and has no strange semantics. > > But doesn't the first one potentially let the compiler avoid spilling to > memory, if b and c are both in registers? > > Not that I'm fond of gccisms, but this one at least seems to have a > potential value. And I'm sure I came up with an instance of it making > my head ache, a while back, but I can't come up with a bad example now. > Care to elaborate on your "strange semantics"? >
A decent compiler should be able to avoid spills in either case.
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