Re: (Hardware?) problem with denormal values on mipsel

James Cowgill <[email protected]> Tue, 26 May 2015 10:13:35 +0100

Newsgroups	gmane.linux.debian.ports.mips
Message-ID	<[email protected]>

On Sun, 2015-05-24 at 22:32 +0300, Aaro Koskinen wrote:
> On Fri, May 22, 2015 at 11:00:18PM +0100, James Cowgill wrote:
> > On Sat, 2015-05-23 at 00:04 +0300, Aaro Koskinen wrote:
> > > On Fri, May 22, 2015 at 05:27:14PM +0100, James Cowgill wrote:
> > > > Yep it's a hardware problem. The following assembly dies (raises SIGILL)
> > > > at 'sqrt.s' on the Loongsons and works everywhere else:
> > > > 
> > > > ===
> > > >         .set mips2
> > > >         .text
> > > >         .global main
> > > >         .type main, @function
> > > > main:
> > > >         lui $t0, %hi(value)
> > > >         lwc1 $f0, %lo(value)($t0)
> > > >         nop
> > > >         sqrt.s $f0, $f0
> > > >         jr $ra
> > > > 
> > > >         .data
> > > > value:
> > > >         .float 1.1342362e-39
> > > > ===
> > > 
> > > Is this a standalone reproducer program for the problem? Because
> > > I tried it on on my Loongson box and didn't get any SIGILL...
> > 
> > It should be. I tried it on some 3A machines at work and it crashed
> > there (and then some other machines which didn't crash). There's a 2F I
> > can try on Tuesday.
> 
> My Loongson is 2F...

I tried it on my 2F (it's a Lemote Fuloong) and it crashed there as well
(both the gfortran and my testcase). It's running up to date jessie.

What compiler versions do you have?
What does the 'cpu model' line say in /proc/cpuinfo?

> > Does the original gfortran code crash for you?
> 
> I don't have gfortran available on my system.

Don't you run Debian?

Thanks,
James

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