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Re: [PATCH][4.3] Deprecate -ftrapv
- From: Richard Guenther <rguenther at suse dot de>
- To: Robert Dewar <dewar at adacore dot com>
- Cc: gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org, mark at codesourcery dot com
- Date: Sat, 1 Mar 2008 13:32:47 +0100 (CET)
- Subject: Re: [PATCH][4.3] Deprecate -ftrapv
- References: <Pine.LNX.4.64.0803010041110.4133@zhemvz.fhfr.qr> <47C8B7F3.2000508@adacore.com>
On Fri, 29 Feb 2008, Robert Dewar wrote:
> Richard Guenther wrote:
> > This is a request to depcrecate -ftrapv which has numerous problems
> > making it not work as expected since a long time. As nobody seems
> > to have the energy to ensure it is working I propose to deprecate it
> > for GCC 4.3 to make it possible to remove it during 4.4 (and not
> > block removing libcall notes by it).
>
> Seems a pity, this feature is really needed for Ada, which requires
> efficient overflow checking for signed arithmetic, and it seems
> useful for C, where signed overflow is undefined, and it would be
> nice to enable trapping.
>
> Right now, Ada uses really horrible double length arithmetic to
> do trapping.
>
> So I would hestitate to deprecate it so quickly
Maybe you should organize some resources to fix its implementation
then?
Richard.