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Re: [PATCH] variable size arrays in nested functions
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Subject: Re: [PATCH] variable size arrays in nested functions
- From: Richard Henderson <rth at redhat dot com>
- Date: Fri, 9 Feb 2001 16:39:09 -0800
- Cc: gcc-patches at gcc dot gnu dot org
- References: <10102100025.AA09145@vlsi1.ultra.nyu.edu>
On Fri, Feb 09, 2001 at 07:25:11PM -0500, Richard Kenner wrote:
> But then it's no longer an expression, but a sequence of statements.
Err, a VAR_DECL certainly is an expression. I'm not suggesting that
its _initialization_ is part of that expression.
In fact, I'll claim that the fact that the initialization of a SAVE_EXPR
might or might not be part of the expression (being dependant on whether
or not it has been previously evaluated) that is the source of all pain
associated with this tree code.
So that a sequence of statements is needed in order to use a VAR_DECL in
this context is in fact a feature.
> I never did understand UNSAVE_EXPR. What was the motivation for that?
To work around problems encountered with evaluating SAVE_EXPRs.
I won't pretend to know exactly which ones, or why UNSAVE_EXPR
was thought to be a "solution".