simplify-rtx.c (simplify_subreg): Do not over-extend vector constants.

2003-06-16  Aldy Hernandez  <aldyh@redhat.com>

	* simplify-rtx.c (simplify_subreg): Do not over-extend vector
	constants.

	* testsuite/gcc.c-torture/execute/simd-4.c: New.

[[Split portion of a mixed commit.]]

From-SVN: r68049.2