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Re: [gfortran] Fix NULL reference types.

From: Richard Henderson <rth at redhat dot com>
To: Mark Mitchell <mark at codesourcery dot com>
Cc: Paul Brook <paul at nowt dot org>, fortran at gcc dot gnu dot org, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Date: Wed, 18 Aug 2004 23:33:08 -0700
Subject: Re: [gfortran] Fix NULL reference types.
References: <200408181410.29111.paul@nowt.org> <20040818193358.GB28527@redhat.com> <412442E4.9070707@codesourcery.com>

On Wed, Aug 18, 2004 at 11:04:20PM -0700, Mark Mitchell wrote:
> RTH, do you object to Nathan's documentation patch?  It would give us an 
> easy way to give the optimizers a little more information.

I think I do, at least for the moment.

Paul was explaining on IRC how Fortran optional arguments work.
They're passed by reference, but NULL of the argument is omitted.
And there's an intrinsic that you can query to see if the argument
was omitted and so avoid accessing the argument.

Now, from an optimization standpoint, sure he can go ahead and
use a pointer type and everything works.  But from a debugging
standpoint, we've just messed things up.  And I'm not sure how
best to go about rectifying that.

r~

Follow-Ups:
- Re: [gfortran] Fix NULL reference types.
  - From: Nathan Sidwell

References:
- [gfortran] Fix NULL reference types.
  - From: Paul Brook
- Re: [gfortran] Fix NULL reference types.
  - From: Richard Henderson
- Re: [gfortran] Fix NULL reference types.
  - From: Mark Mitchell

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