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Re: Reusing stack slots
- From: Joern Rennecke <joern dot rennecke at superh dot com>
- To: rth at redhat dot com (Richard Henderson)
- Cc: zack at codesourcery dot com (Zack Weinberg), wilson at specifixinc dot com (Jim Wilson), drow at false dot org (Daniel Jacobowitz), gcc-patches at gcc dot gnu dot org
- Date: Thu, 8 Jul 2004 19:18:13 +0100 (BST)
- Subject: Re: Reusing stack slots
> On Wed, Jul 07, 2004 at 07:28:11PM -0700, Zack Weinberg wrote:
> > Or, possibly more easily, we could make stack-slot allocation aware of
> > the actual lifetimes of the variables on the list? I would think this
> > information would be readily available as long as we are in SSA form.
>
> We actually don't have this the way you think, particularly when
> it comes to TREE_ADDRESSABLE variables. It's something I've been
> pondering the last couple of days.
Maybe there should be a psudo-operations that indicates that an
addressable variable comes into or gets out of scope.
Sort of like a constructor / destructor pair.
You can the use alias information to see if the lifetime can be
reduced further - the start / end points may be moved across anything that
definitely doesn't alias the variable.