Re: (Hardware?) problem with denormal values on mipsel
Am 27.05.2015 um 21:06 schrieb Maciej W. Rozycki:
> On Wed, 27 May 2015, Ole Streicher wrote:
>
>> It is something specific what gfortran produces (and not gcc), and it is not
>> just a missing emulation (since normalized numbers work); it may be an
>> incomplete emulation.
>
> If you suspect a bug in emulation, then please try narrowing it down to
> the machine instruction that produces the wrong result, you might be able
> to track it down in your Fortran program by single-stepping the program in
> GDB.
Sorry, as I wrote in my initial mail: I can't. I initially had the problem
on eder.debian.org, and reported it as a gfortran bug. Now I got a CI20, and
since the problem does not appear there, I suspect that it may be a
processor (or related) problem. However, eder is not available in the
moment, so I can't do anything.
> Then post the instruction including the encoding (`disassemble /r'
> issued in GDB will include it in output), the inputs, preferably as hex
> patterns, and the output produced (or action taken if e.g. a signal is
> raised instead) that you think is incorrect.
I probably don't understand you here; but wasn't this already done by James
Cowgill? I feel myself a bit incompetent when it comes to MIPS assembly. I
can just report my high-level tests:
- denormalized numbers don't work in Fortran on eder
- normalized numbers work in Fortran on eder
- normalized and denormalized numbers work in the equivalent C program on eder
- Fortran and C works with all numbers on a CI20.
Best regards
Ole
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