Re: [RHEL5 PATCH 1/4] Provide fallback full 64-bit divide/modulus ops for gcc

From: David Howells
Date: Tue Aug 15 2006 - 04:27:44 EST

Andi Kleen <ak@xxxxxxx> wrote:

> At least Linus' traditional argument against this is that it's better
> to open code these (do_div) so that it's clear to the coder that they
> are really costly.

do_div() is not a full replacement for __udivdi3(), __umoddi3() or
__udivmoddi4(), though I suspect we don't need divisor >= 2^32 anywhere atm.

There are places where the compiler emits these that aren't entirely obvious,
one of which IIRC is in ext2 inode allocation.

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