Optimization bug(?) in egcs 1.0.3a on i686

[Trond Myklebust <trond dot myklebust at fys dot uio dot no>]

Hi,

  The following test-case seems to miscompile on my i686 when I
compile using egcs 1.0.3a with '-O2'. The program will segfault upon
entry to the inlined 'pow' function (included below).

Cheers,
  Trond

test.c------------------
#include <math.h>

main()
{
  volatile double a;
  double c;
  a = 32.0;
  c = pow(a, 1.0/3.0);
}
-------------------------



(listing of the 'pow' function from __math.h  glibc-2.0.7)


extern __inline double
pow (double __x, double __y)
{
  register double __value, __exponent;
  long long int __p = (long long int) __y;

  if (__x == 0.0 && __y > 0.0)
    return 0.0;
  if (__y == (double) __p)
    {
      double __r = 1.0;
      if (__p == 0)
        return 1.0;
      if (__p < 0)
        {
          __p = -__p;
          __x = 1.0 / __x;
        }
      while (1)
        {
          if (__p & 1)
            __r *= __x;
          __p >>= 1;
          if (__p == 0)
            return __r;
          __x *= __x;
        }
      /* NOTREACHED */
    }
  __asm __volatile__
    ("fmul      %%st(1)         # y * log2(x)\n\t"
     "fstl      %%st(1)\n\t"
     "frndint                   # int(y * log2(x))\n\t"
     "fxch\n\t"
     "fsub      %%st(1)         # fract(y * log2(x))\n\t"
     "f2xm1                     # 2^(fract(y * log2(x))) - 1\n\t"
     : "=t" (__value), "=u" (__exponent) :  "0" (__log2 (__x)), "1" (__y));
  __value += 1.0;
  __asm __volatile__
    ("fscale"
     : "=t" (__value) : "0" (__value), "u" (__exponent));

  return __value;
}