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Re: Pessimization
- To: Jim Wilson <wilson at cygnus dot com>
- Subject: Re: Pessimization
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Wed, 20 May 1998 23:00:41 -0600
- cc: John Carr <jfc at mit dot edu>, drepper at cygnus dot com (Ulrich Drepper), egcs at cygnus dot com
- Reply-To: law at cygnus dot com
In message <199805200303.UAA12511@rtl.cygnus.com>you write:
> Even better would be to fix the bug, but no one has volunteered to do this
> yet. It will be quite a bit of work to fix the problem. Fixing it means
> computing the `varying' info from the trees, and then progating it through
> the RTL (like MEM_IN_STRUCT_P) instead of computing it on demand in alias.c.
> This would require a very large patch, which would be hard to test.
Right, but this is the direction we need to head anyway. We need
other information from the trees to do more aggressive alias analysis.
And yes, information from teh trees must be propagated into the RTL.
Interestingly enough you just described at a very high level how
Muchnick's book approaches alias analysis :-)
It's certainly a lot of work.
jeff