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Re: [patch] for PR 18040
- From: Zack Weinberg <zack at codesourcery dot com>
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sun, 17 Oct 2004 20:21:10 -0700
- Subject: Re: [patch] for PR 18040
- References: <10410180255.AA02540@vlsi1.ultra.nyu.edu>
email@example.com (Richard Kenner) writes:
> Your opinion on my alternative suggestion - hoist the type conversion
> to the outermost type, thus reducing the nested case to the unnested
> case - would be appreciated (and please read the whole message before
> answering the question, because I address another objection below).
> Aside from the issue of possible quadratic behavior, I don't completely
> understand the proposal here, so I can't fully comment on it. I should
> point out, though, that some of these expressions in practice are
> quite complex: there are lots of implicit conversions and dereferences
> generated by the front end.
If you provide an example which produces a type conversion in the
middle of a chain of dereference expressions, I will endeavor to
clarify what I mean.
> > This stuff is *very* tricky and, as I said, we've been
> > throught it before.
> The PR indicates that the solution which has already been
> implemented does not work. Thus, the entire topic is open for
> The PR indicates that a particular optimizer has problems with the
> overall approach. One way of dealing with that is to change the
> approach. But a more local way is to fix that particular optimizer.
Fair point, however, comments upthread indicate that lots of people
are not happy with the overall approach.