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Re: [PATCH,RFC] Do not assign stack slots to ssa names
- From: Michael Matz <matz at suse dot de>
- To: Andrey Belevantsev <abel at ispras dot ru>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 15 Jun 2009 13:51:53 +0200 (CEST)
- Subject: Re: [PATCH,RFC] Do not assign stack slots to ssa names
- References: <4A300B3C.email@example.com>
On Wed, 10 Jun 2009, Andrey Belevantsev wrote:
> When processing stack vars partitions for alias export patch, I have
> noticed that sometimes we get SSA_NAMEs being allocated on stack, e.g.
> V2SF vectors. Richard suggested the attached patch to fix it.
Yeah, while discussing this I tried the same. But it actually changes the
underlying assumptions of the stack slot allocation code, in precisely the
way that is tested ...
> patch is bootstrapped and tested (Ada enabled) on x86-64. The only
> failing test is stack protector test ssp-2.c, in which an array and a
> loop counter get allocated on stack in a different order and thus
> instead of overflowing the array the test overflows the loop counter and
... here. _All_ stack slot allocations need to be deferred when stack
protector is on (for the reason the comment therein explains), so that the
reordering gets a chance to do it's job. So ...
> So I've also fixed the test.
> Michael, what do you think of the patch?
... I don't think this is going to fly. What was the real problem again?
IIRC it could also be fixed by giving those stack slots their own