2016-08-26  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/69047
	* tree-ssa.c (maybe_rewrite_mem_ref_base): Handle general bitfield
	extracts similar to what FRE does.
	(non_rewritable_mem_ref_base): Likewise.

	* gcc.dg/pr69047.c: New testcase.

From-SVN: r239778