On 05/11/2012 09:07 AM, Janne Blomqvist wrote:
PING #2!
On Wed, May 2, 2012 at 10:22 PM, Janne Blomqvist
<blomqvist.ja...@gmail.com> wrote:
PING
On Thu, Apr 26, 2012 at 12:08 AM, Janne Blomqvist
<blomqvist.ja...@gmail.com> wrote:
Hi,
currently when -frange-check is enabled, we check for overflow when
doing a formatted read of an integer value. This check, however, is
against the Fortran numerical model (see 13.4 in F2008), which defines
a symmetric interval [-huge(), huge()], whereas all targets gfortran
supports use a two's complement representation with a range of
[-huge()-1, huge()].
However, there is no checking against the numerical model when doing
arithmetic, and thus we can generate and write the value -huge()-1,
but we cannot read it back in! With the -fno-range-check option, this
overflow checking can be disabled, but at the cost of disabling all
overflow checking, which leads to reading nonsense values if the
hardware supported range overflows.
The attached patch changes this logic such that overflow checking
against the hardware supported range [-huge()-1, huge()] is always
done when reading, regardless of the -frange-check flag setting. This
also seems to be what ifort 12.0 does, I haven't checked other
compilers.
For some more arguments back and forth, see the PR.
Regtested on x86_64-unknown-linux-gnu, Ok for trunk?
Patch OK for trunk. In spite of myself, it does not hurt anything.
Regards,
Jerry
