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Re: [PATCH] Fix PR middle-end/17793
- From: Jason Merrill <jason at redhat dot com>
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 19 Oct 2004 19:28:51 -0400
- Subject: Re: [PATCH] Fix PR middle-end/17793
- References: <10410192317.AA14937@vlsi1.ultra.nyu.edu>
On Tue, 19 Oct 04 19:17:15 EDT, kenner@vlsi1.ultra.nyu.edu (Richard Kenner) wrote:
> VIEW_CONVERT_EXPR operates on the reference, NOP_EXPR on the value.
>
> No. VIEW_CONVERT_EXPR conceptually operates on a *value*. In Ada, it's
> the equivalent of an unchecked conversion, which is semantically a
> *function*. In C, it's the equivalent of a conversion of a value into
> a union and then an extraction of another field of that union, which
> is also a value.
That would seem to imply making a copy of the (possibly aggregate) value,
which I thought we were trying to avoid. If we're using a
VIEW_CONVERT_EXPR on the lhs of a COMPONENT_REF, where does the extraction
come in?
Jason