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Re: Optimization of offset computations
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Subject: Re: Optimization of offset computations
- From: Richard Henderson <rth at cygnus dot com>
- Date: Tue, 30 Nov 1999 15:13:53 -0800
- Cc: bernds at pathia dot cygnus dot co dot uk, gcc-patches at gcc dot gnu dot org
- References: <9911301501.AA00867@vlsi1.ultra.nyu.edu>
On Tue, Nov 30, 1999 at 10:01:54AM -0500, Richard Kenner wrote:
> Indeed how about making it more general: adding a TREE_NO_OVERFLOW which
> means that the semantics are such that overflow isn't permitted, so we
> can feel free to optimize in such a way that would make things work
> differently in the case of overflow?
This seems reasonable. (I would use "is undefined" not
"isn't permitted" in any documentation.)
> If we do it this way, it could also be used for expressions where the
> language has overflow undefined (signed operations in C and all in
> Ada, for exmaple).
Should get marked for C pointer arithmetic as well.
r~