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Re: [PATCH] Improve PR30911 and PR31023, Ada and VRP

From: Duncan Sands <duncan dot sands at math dot u-psud dot fr>
To: gcc-patches at gcc dot gnu dot org
Cc: Richard Guenther <rguenther at suse dot de>, Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>, ebotcazou at adacore dot com
Date: Mon, 31 Mar 2008 15:59:18 +0200
Subject: Re: [PATCH] Improve PR30911 and PR31023, Ada and VRP
References: <Pine.LNX.4.64.0803291749290.4133@zhemvz.fhfr.qr> <10803311214.AA16925@vlsi1.ultra.nyu.edu> <Pine.LNX.4.64.0803311455320.4133@zhemvz.fhfr.qr>

Hi,

> So I see only harm in the current non-existing middle-end semantics
> of integral sub-types.  Thus I recommend to disallow using them
> for variables exposed to the middle-end.

I have to agree, it is all just too error prone.  How about having
the Ada front-end add ASSERT_EXPR's (or maybe an equivalent builtin)
at points where it knows an interesting bound?  Unlike the current
situation, these should mean what they say: the value is guaranteed
to be in the range.  As such they wouldn't apply to uninitialized
variables and so forth, which would remove the need for a VRP barrier
like VIEW_CONVERT_EXPR.

Ciao,

Duncan.

Follow-Ups:
- Re: [PATCH] Improve PR30911 and PR31023, Ada and VRP
  - From: Richard Guenther

References:
- [PATCH] Improve PR30911 and PR31023, Ada and VRP
  - From: Richard Guenther
- Re: [PATCH] Improve PR30911 and PR31023, Ada and VRP
  - From: Richard Kenner
- Re: [PATCH] Improve PR30911 and PR31023, Ada and VRP
  - From: Richard Guenther

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