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Re: General question about types of tree expressions
- From: Jeffrey A Law <law at redhat dot com>
- To: Paul Schlie <schlie at comcast dot net>
- Cc: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>, Andrew Pinski <pinskia at physics dot uc dot edu>, gcc at gcc dot gnu dot org, Daniel Berlin <dberlin at dberlin dot org>
- Date: Wed, 09 Feb 2005 11:01:46 -0700
- Subject: Re: General question about types of tree expressions
- Organization: Red Hat, Inc
- References: <BE2FB5E7.8FA4%schlie@comcast.net>
- Reply-to: law at redhat dot com
On Wed, 2005-02-09 at 12:43 -0500, Paul Schlie wrote:
> > Daniel Berlin writes:
> > The document i've been working on defining the semantics of gimple
> > operations specifically states that all binary and unary operators
> > must have operands of the same type.
>
> Out of curiosity, wouldn't it be both simpler and more efficient to
> define the semantics such that operands are "implied" to have the same
> type as the node itself, thereby eliminate the otherwise necessity to
> literally insert cast operators into the tree, which are already implied
> by the semantics of the operation itself (except as may otherwise be
> required to denote that sign extension for promoted signed integers, but
> not otherwise required for unsigned, down-cast, or other type conversions)?
The problem is that doing so would require every optimizer to convert
operands into the appropriate type before operating on them. That's
rather prone to failure.
jeff