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? > > gcc/fortran ChangeLog: > > 2012-04-25 Janne Blomqvist <j...@gcc.gnu.org> > > PR fortran/52428 > * gfortran.texi: Update _gfortran_set_options documentation. > * invoke.texi: Remove runtime behavior description of > -fno-range-check. > * trans-decl.c (create_main_function): Don't pass the range-check > setting to the library. > > > libgfortran ChangeLog: > > 2012-04-25 Janne Blomqvist <j...@gcc.gnu.org> > > PR fortran/52428 > * io/io.h (max_value): Rename to si_max, remove second argument. > * io/list_read.c (convert_integer): Use unsigned types when > parsing the digits, set max value depending on the sign. > * io/read.c (max_value): Rename to si_max, remove second argument, > simplify. > (read_decimal): Set max value depending on sign, always check > overflow. > (read_radix): Calculate max unsigned value directly. > * libgfortran.h (struct compile_options_t): Remove range_check > field. > * runtime/compile_options.c (set_options): Skip handling > options[7]. > (init_compile_options): Don't set removed field. > > > gcc/testsuite ChangeLog: > > 2012-04-25 Janne Blomqvist <j...@gcc.gnu.org> > > PR fortran/52428 > * gfortran.dg/int_range_io_1.f90: New test. > > > -- > Janne Blomqvist
-- Janne Blomqvist
