2016-05-13  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/42587
	* tree-ssa-math-opts.c (perform_symbolic_merge): Handle BIT_FIELD_REF.
	(find_bswap_or_nop_1): Likewise.
	(bswap_replace): Likewise.

	* gcc.dg/optimize-bswapsi-4.c: New testcase.

From-SVN: r236204