re PR middle-end/48722 (ICE in df_refs_verify() with -mno-push-args)

re PR middle-end/48722 (ICE in df_refs_verify() with -mno-push-args)

	PR middle-end/48722
	* emit-rtl.c (unshare_all_rtl_again): For CALL_INSNs,
	reset_used_flags also in CALL_INSN_FUNCTION_USAGE.
	(verify_rtl_sharing): Likewise and verify_rtx_sharing
	in there too.
	(unshare_all_rtl_in_chain): For CALL_INSNs
	copy_rtx_if_shared also CALL_INSN_FUNCTION_USAGE.

	* gcc.target/i386/pr48722.c: New test.

From-SVN: r178208