PR rtl-optimization/79909
	* combine.c (try_combine): Use simplify_replace_rtx on individual
	CALL_INSN_FUNCTION_USAGE elements instead of replace_rtx on copy_rtx
	of the whole CALL_INSN_FUNCTION_USAGE.

	* gcc.target/powerpc/pr79909.c: New test.

From-SVN: r246023