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

On Fri, 2015-05-22 at 16:12 +0100, James Cowgill wrote:
> On Fri, 2015-05-22 at 16:41 +0200, Ole Streicher wrote:
> > Program received signal SIGILL: Illegal instruction.
> 
> eder and all the other machines eso-midas has failed on are Loongson
> machines. I'll have a further investigate but I wouldn't be too
> surprised if this was yet another Loongson FPU bug...

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
===

There is now only one non-loongson build machine (mayer) so it doesn't
look good. All the solutions I can think of for this sound really
horrible (stuff like disabling the FPUs) :(

Thanks,
James

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