re PR rtl-optimization/80500 (ICE: internal consistency failure (error: invalid rtl sharing found in the insn))

	PR rtl-optimization/80500
	* loop-unroll.c (combine_var_copies_in_loop_exit): Call copy_rtx on
	sum's initial value.

	* gcc.dg/pr80500.c: New test.

From-SVN: r247126