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Date: Tue, 07 Jun 2011 14:00:00 -0000
From: "Joseph S. Myers" <joseph@codesourcery.com>
To: Paolo Bonzini <bonzini@gnu.org>
cc: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>, gcc-patches@gcc.gnu.org,     Ralf Wildenhues <Ralf.Wildenhues@gmx.de>,     Mike Stump <mikestump@comcast.net>, "Loren J. Rittle" <ljrittle@acm.org>,     Kai Tietz <ktietz@redhat.com>, Dave Korn <dave.korn.cygwin@gmail.com>,     Jason Thorpe <thorpej@netbsd.org>,     Krister Walfridsson <krister.walfridsson@gmail.com>,     Uros Bizjak <ubizjak@gmail.com>, Richard Henderson <rth@redhat.com>,     Eric Botcazou <ebotcazou@adacore.com>
Subject: Re: [build] Move ENABLE_EXECUTE_STACK to toplevel libgcc
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On Tue, 31 May 2011, Paolo Bonzini wrote:

> > I'd thought about it, but refrained since HAVE_ENABLE_EXECUTE_STACK
> > affects only three cpus.  Currently, our documentation of libgcc
> > configury and macros used is close to non-existant.  That's probably for
> > someone who has implemented this stuff.
> 
> True, OTOH HAVE_ENABLE_EXECUTE_STACK is a target macro, and those are well
> documented.  Just say that it has to be defined if libgcc provides a
> non-trivial implementation of __enable_execute_stack; it doesn't need to delve
> into how to hack libgcc.

As I understand it, HAVE_ENABLE_EXECUTE_STACK is only used in code under 
gcc/config/.  That is, it is not a target macro as usually understood but 
is logically private to a few back ends (and it would be a bug to 
introduce uses of it elsewhere, just like it was a bug to introduce uses 
of TARGET_64BIT outside gcc/config/ when that macro also is logically 
private).

-- 
Joseph S. Myers
joseph@codesourcery.com