*** empty log message ***

From-SVN: r764

diff --git a/gcc/combine.c b/gcc/combine.c
index bee3287bb8e3d1e7b66e404dd6beb60e81cb1172..247f66ac2d4f4b9f689e2a97c47d65e0ebfa42c0 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -2583,10 +2583,13 @@ subst (x, from, to, in_dest, unique_copy)
        }
 
       /* For a constant, try to pick up the part we want.  Handle a full
-        word and low-order part.  */
+        word and low-order part.  Only do this if we are narrowing
+        the constant; if it is being widened, we have no idea what
+        the extra bits will have been set to.  */
 
       if (CONSTANT_P (SUBREG_REG (x)) && op0_mode != VOIDmode
          && GET_MODE_SIZE (mode) == UNITS_PER_WORD
+         && GET_MODE_SIZE (op0_mode) < UNITS_PER_WORD
          && GET_MODE_CLASS (mode) == MODE_INT)
        {
          temp = operand_subword (SUBREG_REG (x), SUBREG_WORD (x),
@@ -2595,7 +2598,8 @@ subst (x, from, to, in_dest, unique_copy)
            return temp;
        }
        
-      if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_p (x))
+      if (CONSTANT_P (SUBREG_REG (x)) && subreg_lowpart_p (x)
+         && GET_MODE_SIZE (mode) < GET_MODE_SIZE (op0_mode))
        return gen_lowpart_for_combine (mode, SUBREG_REG (x));
 
       /* If we are narrowing the object, we need to see if we can simplify