emit-rtl.c (init_emit_once): Zero unused memory in a CONST_DOUBLE.

        * emit-rtl.c (init_emit_once): Zero unused memory in a
        CONST_DOUBLE.

From-SVN: r42423

gcc/ChangeLog

+2001-05-21  Richard Henderson  <rth@redhat.com>
+
+	* emit-rtl.c (init_emit_once): Zero unused memory in a
+	CONST_DOUBLE.
+
 2001-05-21  Mark Mitchell  <mark@codesourcery.com>
 
 	* tree.h (type_num_arguments): Declare it.

gcc/emit-rtl.c

@@ -4336,9 +4336,16 @@ init_emit_once (line_numbers)
 	  rtx tem = rtx_alloc (CONST_DOUBLE);
 	  union real_extract u;
 
-	  memset ((char *) &u, 0, sizeof u);  /* Zero any holes in a structure.  */
+	  /* Zero any holes in a structure.  */
+	  memset ((char *) &u, 0, sizeof u);
 	  u.d = i == 0 ? dconst0 : i == 1 ? dconst1 : dconst2;
 
+	  /* Avoid trailing garbage in the rtx.  */
+	  if (sizeof (u) < sizeof (HOST_WIDE_INT))
+	    CONST_DOUBLE_LOW (tem) = 0;
+	  if (sizeof (u) < 2 * sizeof (HOST_WIDE_INT))
+	    CONST_DOUBLE_HIGH (tem) = 0;
+
 	  memcpy (&CONST_DOUBLE_LOW (tem), &u, sizeof u);
 	  CONST_DOUBLE_MEM (tem) = cc0_rtx;
 	  CONST_DOUBLE_CHAIN (tem) = NULL_RTX;