re PR rtl-optimization/55845 (454.calculix miscompares with -march=btver2 -O3 -ffastmath -fschedule-insns -mvzeroupper for test data run)

	PR rtl-optimization/55845
	* df-problems.c (can_move_insns_across): Stop scanning at
	volatile_insn_p source instruction or give up if
	across_from .. across_to range contains any volatile_insn_p
	instructions.

	* gcc.target/i386/pr55845.c: New test.

From-SVN: r195028