Messages in this thread |  | | | Date | Wed, 7 Mar 2007 18:24:49 +0100 | | Subject | Re: ALIGN via ilog2 without gccisms (Re: [PATCH] Fix get_order()) | | From | Oleg Verych <> |
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On Wed, Mar 07, 2007 at 08:38:27AM -0800, Linus Torvalds wrote: > > > On Wed, 7 Mar 2007, Oleg Verych wrote: > > > > Probably it can be used to get rid of gccisms and "type fluff" due to > > bitwise arithmetics in ALIGN? > > Hell no. > > The typeof is there to make sure we have the right type, and it's simple. > > The current ALIGN() macro is efficient as hell (generating just a simple > mask+add). Turning it into some kind of horrible thing that uses ilog2() > would be a total mistake.
GCC's assembler version of this macro is optimized as needed.
But i wanted to address Al's statement about using typeof():
,-*- [ Message-ID: <20061127044138.GA3078@ftp.linux.org.uk> ] |IOW, gcc allows type to leak out of scope it's been defined in (and |typeof adds even more fun to the picture). It not only goes against |a _lot_ in C, it's actually not thought through by gcc folks. Just |try to mix that with variable-length arrays and watch it blow up |in interesting ways... `-*-
As for me, this is example of assembler's need, that very hard to implement in C. Also, i doubt, C's shift doing any "type fluff" on its only argument.
> Also, your ALIGN() macro was broken. That's not how ALIGN() is supposed to > work.
Yes, maybe so. ____ - 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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