Re: [PATCH 09/10] Change table chaining layout

From: Linus Torvalds
Date: Mon Oct 22 2007 - 17:48:24 EST




On Mon, 22 Oct 2007, Alan Cox wrote:

> For structures, not array elements or stack objects. Does gcc now get
> aligned correct as an attribute on a stack object ?

I think m68k stack layout still guarantees 4-byte-alignment, no?

> Still doesn't answer the rather more important question - why not just
> stick a NULL on the end instead of all the nutty hacks ?

You still do need one bit for the discontiguous case, so it's not like you
can avoid the hacks anyway (unless you just blow up the structure
entirely) and make it a separate member). So once you have that
bit+pointer, using a separate NULL entry isn't exactly prettier.

Especially as we actally want to see the difference between
"end-of-allocation" and "not yet filled in", so you shouldn't use NULL
anyway, you should probably use something like "all-ones".

Linus
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