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Re: Question on vrp_meet in tree-vrp.c
- From: Sebastian Pop <sebastian dot pop at cri dot ensmp dot fr>
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 6 Sep 2005 11:13:38 +0200
- Subject: Re: Question on vrp_meet in tree-vrp.c
- References: <10509052127.AA02439@vlsi1.ultra.nyu.edu>
Richard Kenner wrote:
> [Sorry for the missing line in my last message.]
>
> I'm watching it deal with
>
> # small_1 = PHI <32(0), 1(1)>
>
> vrp_meet is called with [32, 32] and [1,1].
>
> It determines that the ranges don't intersect and then comes up with
> ~[0,0] since neither contain zero. But wouldn't [1,32] be a better
> result?
yes, [1, 32] is included in [MIN_type, MAX_type] - [0,0] and thus it
is more precise.