Re: [9fans] f2c issue

[Fausto Saporito <fausto.saporito@gmail.com>]

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Hi Erik,

yes, it's a FP stack overflow... :-)
I also tried with 9front, and the error message is slightly different:

./arithchk
#define IEEE_8087
#define Arith_Kind_ASL 1
arithchk 8523: suicide: sys: fp: invalid operation fppc=0x12ee
status=0xb8b3 pc=0x000012f2

further checks reveal that the problem is this function:

 void
get_nanbits(unsigned int *b, int k)
{
union { double d; unsigned int z[2]; } u, u1, u2;

k = 2 - k;
 u1.z[k] = u2.z[k] = 0x7ff00000;
u1.z[1-k] = u2.z[1-k] = 0;
u.d = u1.d - u2.d; /* Infinity - Infinity */ <<<<<<<======  this is the
FATAL ERROR.
 b[0] = u.z[0];
b[1] = u.z[1];
}

called as getnanbits(nanbits,1)

I'm sorry but I don't know how to generate the acid code.

regards,
Fausto



2013/11/22 erik quanstrom <quanstro@quanstro.net>

> > By the way I have always the same problem (suicide with stack overflow
> > running arithchk).
>
> that's not a stack overflow, that's a x87 floating point stack overflow.
> if you would post the code around the program counter in your error
> message it would be helpful.  asm(*PC) with acid would be even better.
>
> - erik
>

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