Special case shifting by zero in operator_rshift::op1_range.

gcc/ChangeLog:

	* range-op.cc (operator_rshift::op1_range): Special case
	shifting by zero.

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 21d98de2240621ed2ef2a6a534981b3b67703335..ee62f103598aff16549f45a0949be350f98f1848 100644 (file)
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -1642,6 +1642,11 @@ operator_rshift::op1_range (irange &r,
                    wi::uhwi (prec, TYPE_PRECISION (TREE_TYPE (shift))),
                    UNSIGNED))
        return false;
+      if (wi::to_wide (shift) == 0)
+       {
+         r = lhs;
+         return true;
+       }
 
       // Folding the original operation may discard some impossible
       // ranges from the LHS.