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Re: simplify_subreg issues
- To: Mark Mitchell <mark at codesourcery dot com>
- Subject: Re: simplify_subreg issues
- From: Jan Hubicka <jh at suse dot cz>
- Date: Tue, 12 Jun 2001 11:04:41 +0200
- Cc: Geoff Keating <geoffk at cygnus dot com>, Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>, Jan Hubicka <jh at suse dot cz>, gcc at gcc dot gnu dot org
- References: <20010611190907Y.mitchell@codesourcery.com>
> I don't know how to fix this. We can revert my patch, but that will
> reintroduce the bugs it was trying to fix, so I would be happier if we
> could figure out to fix the real problem.
Sure, I will try to proceed on fixing the real problem.
The volatility check in simplify_subreg looks somewhat dubious for me.
When I was unifying the code, some copies did contain it, some didn't.
I decided to be on the "safe side" and included it, but it is not 100%
clear to me that it is really required.
Is there someone who sees the rationale behind this?
I believe that volatile means "every time you want to know the value,
you must look to the memory", but it IMO doesn't matter if we look at
whole or part.
I've hypotetized that this may be used by some weird port for MMIO or so.
More to come after exam :)
Honza
>
> Thanks,
>
> --
> Mark Mitchell mark@codesourcery.com
> CodeSourcery, LLC http://www.codesourcery.com