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Re: [PATCH][no-undefined-overflow] Teach VRP to produce *NV_EXPR, fix unsigned overflow detection in int_const_binop
- From: Richard Guenther <rguenther at suse dot de>
- To: Paolo Bonzini <bonzini at gnu dot org>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 9 Mar 2009 10:54:41 +0100 (CET)
- Subject: Re: [PATCH][no-undefined-overflow] Teach VRP to produce *NV_EXPR, fix unsigned overflow detection in int_const_binop
- References: <alpine.LNX.2.00.0903091032210.10965@zhemvz.fhfr.qr> <49B4E5E9.8050003@gnu.org>
On Mon, 9 Mar 2009, Paolo Bonzini wrote:
> I wonder if you can produce some testcases where
> -Wunsafe-loop-optimizations would warn before but not with this patch...
> which means it's great work.
I guess not yet (because I didn't yet look into SCEV and related analysis
to see if the need to handle *NV_EXPR tree codes). But likely there
will be. Of course I completely forgot to set TREE_NO_WARNING on the
VRP generated ones ... (I was thinking to preserve the undefined
overflow warnings somehow only for the frontend provided *NV_EXPR
operations).
Richard.