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Re: vrp extracts range from negative multiply/divide ranges incorrectly
- From: Diego Novillo <dnovillo at redhat dot com>
- To: Alexandre Oliva <aoliva at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 20 Apr 2005 15:41:24 -0400
- Subject: Re: vrp extracts range from negative multiply/divide ranges incorrectly
- Organization: Red Hat Canada
- References: <ork6n1tb6a.fsf@livre.redhat.lsd.ic.unicamp.br>
On Sun, Apr 17, 2005 at 05:12:29PM -0300, Alexandre Oliva wrote:
> If negative values are present in the ranges of operands of a multiply
> or a divide expression, the ranges we compute may be incorrect. This
> patch appears to fix them all. Tested on amd64-linux-gnu. Ok to
> install?
>
Test case? The code in extract_range_from_binary_expr is a bit
eager about setting the resulting range to VARYING when it finds
that the two range endpoints get swapped around, but it shouldn't
be generating invalid ranges.
The additional cases you are adding will probably allow better
range precision. Got a test case for that too?
Diego.