Re: [PATCH] x86: unify x86 Makefile(s)

Adrian Bunk
2007-12-29T12:54:24Z

On Sat, Dec 29, 2007 at 01:16:07PM +0100, Andi Kleen wrote:
>
> If -funit-at-a-time really increases stack size too much on some compiler
> version the right fix would be to check where it does that using make checkstack
> and then add "noinline" attributes there to prevent the compiler from inlining.
> That would prevent them.
>
> Globally disabling it is too big a hammer.
>
> e.g. I know XFS did it in a similar way to prevent this problem.
>
> So I would reenable it for now and if you know it causes problems on specific
> compiler versions, Adrian, you could watch make checkstack there and submit
> noinline patches as needed.

The main point is that we are _only_ talking about gcc 3.4 on i386 - for
more recent compilers we do not disable unit-at-a-time.

First of all our user - and therefore tester - base with this compiler
has become quite small. And checkstack alone doesn't help that much with
finding the problems since it only lists per-function stack usage, not
the stack usage of the complete call chain.

People who want maximum performance and/or minimum code size anyway
won't use a more than 3 years old compiler.

If we were talking about gcc 4.2 I would agree with you, but I simply do
not see the point in risking regressions for gcc 3.4 users when the only
benefit would be better code with an ancient compiler.

> -Andi

cu
Adrian

--

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"Only a promise," Lao Er said.
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