re PR middle-end/21720 (GCC incorrectly rounds hex floats)

	PR c/21720
	* real.c (real_from_string): Also set last bit if there is a
	nonzero hex digit beyond GCC's internal precision after ".".

testsuite:
	* gcc.dg/hex-round-1.c: Test more cases.
	* gcc.dg/hex-round-2.c: New test.

From-SVN: r102567

1 files changed, 4 insertions, 0 deletions

diff --git a/gcc/real.c b/gcc/real.c
index 045a803..2d26185 100644
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -1815,6 +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++;
 	    }
 	}