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Re: who owns stack args?

From: Jeff Law <law at redhat dot com>
To: Alexander Monakov <amonakov at ispras dot ru>, DJ Delorie <dj at redhat dot com>
Cc: gcc at gcc dot gnu dot org
Date: Wed, 24 Feb 2016 13:54:20 -0700
Subject: Re: who owns stack args?
Authentication-results: sourceware.org; auth=none
References: <201602241920 dot u1OJKXXL022846 at greed dot delorie dot com> <alpine dot LNX dot 2 dot 20 dot 1602242304460 dot 20973 at monopod dot intra dot ispras dot ru>

On 02/24/2016 01:42 PM, Alexander Monakov wrote:

On Wed, 24 Feb 2016, DJ Delorie wrote:

The real question is: are stack arguments call-clobbered or
call-preserved?  Does the answer depend on the "pure" attribute?


Stack area holding stack arguments should belong to the callee for tail-calls
to work (the callee will trash that area when laying out arguments for the
tail call; thanks to Rich Felker for pointing that out to me).

Thus it cannot depend on attribute-pure.

Which would imply that the outgoing argument stack slots must always beconsidered clobbered by a call.


FWIW, I'm fine with that interpretation ;-)

jeff

References:
- who owns stack args?
  - From: DJ Delorie
- Re: who owns stack args?
  - From: Alexander Monakov

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