re PR rtl-optimization/87507 (IRA unnecessarily uses non-volatile registers during register assignment)

gcc/
	PR rtl-optimization/87507
	* lower-subreg.c (operand_for_swap_move_operator): New function.
	(simple_move): Strip simple operators.
	(find_pseudo_copy): Likewise.
	(resolve_operand_for_swap_move_operator): New function.
	(resolve_simple_move): Strip simple operators and swap operands.

gcc/testsuite/
	PR rtl-optimization/87507
	* gcc.target/powerpc/pr87507.c: New test.
	* gcc.target/powerpc/pr68805.c: Update expected results.

From-SVN: r266097