re PR middle-end/47968 (ICE: in gen_lowpart_general, at rtlhooks.c:51 when converting vector of double to vector of float)

2011-03-04  Richard Guenther  <rguenther@suse.de>

	PR middle-end/47968
	* expmed.c (extract_bit_field_1): Prefer vector modes that
	vec_extract patterns can handle.

	* gcc.dg/torture/pr47968.c: New testcase.

From-SVN: r170673