* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Simplify.
	* config/rs6000/rs6000.c (rs6000_emit_move): Use adjust_address
	rather than simplify_subreg.  Check for volatile-ness.  Check that
	we're not splitting one slow operation into two slow operations.
In gcc/testsuite/:
	* gcc.c-torture/compile/structs.c: New testcase from GDB.

From-SVN: r47524