2005-01-21  Kenneth Zadeck <zadeck@naturalbridge.com>

	* df-scan.c (problem_SCAN): Added NULL reset function.
	(df_scan_reset_blocks): Added code to call reset block function
	(df_bb_refs_delete) Fixed comment.
	(df_insn_refs_delete): Made tolerant of deleting non existent info
	for dataflow problems that need to be reset.
	* df-core.c (df_set_blocks): Ditto.
	* df.h (struct df_problem): Added reset_fun.
	* df-problems.c (problem_RU, problem_RD, problem_LR, problem_UR,
	problem_UREC, problem_CHAIN, problem_RI): Initialized reset_fun field.
	(df_chain_insn_reset, df_chain_bb_reset, df_chain_reset): New
	functions to clear out all references to def-use or use-def chains.

From-SVN: r110066