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Re: [RFC] Tightening up the type system

From: Nathan Sidwell <nathan at codesourcery dot com>
To: Andrew Haley <aph at redhat dot com>
Cc: Diego Novillo <dnovillo at redhat dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
Date: Tue, 28 Sep 2004 18:34:22 +0100
Subject: Re: [RFC] Tightening up the type system
Organization: Codesourcery LLC
References: <1096385758.18087.55.camel@localhost.localdomain> <16729.39370.815293.198564@cuddles.cambridge.redhat.com>

Andrew Haley wrote:

Diego Novillo writes: > > > My question to the FE folks is: what are the right semantics for > checking MODIFY_EXPR? Is compatible_types_p too strict? Should we have > had a cast operation in the above assignment? > > Not having the right types is increasingly getting in the way of the > optimizers because we use compatible_types_p quite often to validate > propagation opportunities.
It's an interesting view.  I'm pretty sure that we violate this is the
Java FE in a few places, but perhaps we shouldn't.  The trouble is
that the GENERIC type system has never been so well-defined.
I'm sure that enforcing this would break things and it would take some time to find and fix them all.


It'd force us to treat an lvalue packed field as incompatible to an
unpacked one, at last.

nathan

--
Nathan Sidwell    ::   http://www.codesourcery.com   ::     CodeSourcery LLC
nathan@codesourcery.com    ::     http://www.planetfall.pwp.blueyonder.co.uk

References:
- [RFC] Tightening up the type system
  - From: Diego Novillo
- [RFC] Tightening up the type system
  - From: Andrew Haley

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