PR target/21623:

[pf3gnuchains/gcc-fork.git] / gcc / real.c

diff --git a/gcc/real.c b/gcc/real.c
index 81bce44..9b165ec 100644 (file)
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -18,8 +18,8 @@
 
    You should have received a copy of the GNU General Public License
    along with GCC; see the file COPYING.  If not, write to the Free
-   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-   02111-1307, USA.  */
+   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+   02110-1301, USA.  */
 
 #include "config.h"
 #include "system.h"
@@ -1789,6 +1789,10 @@ real_from_string (REAL_VALUE_TYPE *r, const char *str)
                |= (unsigned long) d << (pos % HOST_BITS_PER_LONG);
              pos -= 4;
            }
+         else if (d)
+           /* Ensure correct rounding by setting last bit if there is
+              a subsequent nonzero digit.  */
+           r->sig[0] |= 1;
          exp += 4;
          str++;
        }
@@ -1811,6 +1815,10 @@ real_from_string (REAL_VALUE_TYPE *r, const char *str)
                    |= (unsigned long) d << (pos % HOST_BITS_PER_LONG);
                  pos -= 4;
                }
+             else if (d)
+               /* Ensure correct rounding by setting last bit if there is
+                  a subsequent nonzero digit.  */
+               r->sig[0] |= 1;
              str++;
            }
        }
@@ -2391,7 +2399,19 @@ real_value_truncate (enum machine_mode mode, REAL_VALUE_TYPE a)
 bool
 exact_real_truncate (enum machine_mode mode, const REAL_VALUE_TYPE *a)
 {
+  const struct real_format *fmt;
   REAL_VALUE_TYPE t;
+  int emin2m1;
+
+  fmt = REAL_MODE_FORMAT (mode);
+  gcc_assert (fmt);
+
+  /* Don't allow conversion to denormals.  */
+  emin2m1 = (fmt->emin - 1) * fmt->log2_b;
+  if (REAL_EXP (a) <= emin2m1)
+    return false;
+
+  /* After conversion to the new mode, the value must be identical.  */
   real_convert (&t, mode, a);
   return real_identical (&t, a);
 }