m68k: avoid undue overflow in cexp

diff --git a/ChangeLog.m68k b/ChangeLog.m68k
index 160fb16..a7f4202 100644 (file)
--- a/ChangeLog.m68k
+++ b/ChangeLog.m68k
@@ -1,5 +1,7 @@
 2012-03-23  Andreas Schwab  <schwab@linux-m68k.org>
 
+       * sysdeps/m68k/m680x0/fpu/s_cexp.c: Avoid undue overflow.
+
        * sysdeps/m68k/m680x0/fpu/bits/mathinline.h (__inline_mathop1):
        Mark asm as volatile.
        (__scalbn): Likewise.

diff --git a/sysdeps/m68k/m680x0/fpu/s_cexp.c b/sysdeps/m68k/m680x0/fpu/s_cexp.c
index 62cddbd..c2a9f1d 100644 (file)
--- a/sysdeps/m68k/m680x0/fpu/s_cexp.c
+++ b/sysdeps/m68k/m680x0/fpu/s_cexp.c
@@ -17,6 +17,7 @@
    License along with the GNU C Library.  If not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <float.h>
 #include <complex.h>
 #include <math.h>
 #include "mathimpl.h"
@@ -43,26 +44,46 @@ s(__cexp) (__complex__ float_type x)
   if ((ix_cond & (__M81_COND_NAN|__M81_COND_INF)) == 0)
     {
       /* Imaginary part is finite.  */
-      float_type exp_val = m81(__ieee754_exp) (__real__ x);
+      unsigned long rx_cond = __m81_test (__real__ x);
 
-      __real__ retval = __imag__ retval = exp_val;
-      if (m81(__finite) (exp_val))
+      if ((rx_cond & (__M81_COND_NAN|__M81_COND_INF)) == 0)
        {
-         float_type sin_ix, cos_ix;
-         __asm ("fsincos%.x %2,%1:%0" : "=f" (sin_ix), "=f" (cos_ix)
-                : "f" (__imag__ x));
-         __real__ retval *= cos_ix;
+         const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l);
+         long double sin_ix, cos_ix, exp_val;
+
+         __m81_u (__sincosl) (__imag__ x, &sin_ix, &cos_ix);
+
+         if (__real__ x > t)
+           {
+             long double exp_t = __m81_u(__ieee754_expl) (t);
+             __real__ x -= t;
+             sin_ix *= exp_t;
+             cos_ix *= exp_t;
+             if (__real__ x > t)
+               {
+                 __real__ x -= t;
+                 sin_ix *= exp_t;
+                 cos_ix *= exp_t;
+               }
+           }
+
+         exp_val = __m81_u(__ieee754_expl) (__real__ x);
+         __real__ retval = exp_val * cos_ix;
          if (ix_cond & __M81_COND_ZERO)
            __imag__ retval = __imag__ x;
          else
-           __imag__ retval *= sin_ix;
+           __imag__ retval = exp_val * sin_ix;
        }
       else
        {
          /* Compute the sign of the result.  */
-         float_type remainder, pi_2;
+         long double remainder, pi_2;
          int quadrant;
 
+         if ((rx_cond & (__M81_COND_NAN|__M81_COND_NEG)) == __M81_COND_NEG)
+           __real__ retval = __imag__ retval = 0.0;
+         else
+           __real__ retval = __imag__ retval = __real__ x;
          __asm ("fmovecr %#0,%0\n\tfscale%.w %#-1,%0" : "=f" (pi_2));
          __asm ("fmod%.x %2,%0\n\tfmove%.l %/fpsr,%1"
                 : "=f" (remainder), "=dm" (quadrant)
@@ -83,7 +104,7 @@ s(__cexp) (__complex__ float_type x)
              __imag__ retval = -__imag__ retval;
              break;
            }
-         if (ix_cond & __M81_COND_ZERO && !m81(__isnan) (exp_val))
+         if (ix_cond & __M81_COND_ZERO && (rx_cond & __M81_COND_NAN) == 0)
            __imag__ retval = __imag__ x;
        }
     }