PR tree-optimization/50693
	* tree-cfg.c (gimple_can_merge_blocks_p): Allow merging with
	non-forced user labels.
	(gimple_merge_blocks): Turn non-forced user labels into
	debug bind stmt with the label as first operand and reset value.
	(gimple_duplicate_bb): Don't duplicate label debug stmts.
	* dwarf2out.c (gen_label_die): Handle NOTE_INSN_DELETED_DEBUG_LABEL.
	* final.c (final_scan_insn): Likewise.
	(rest_of_clean_state): Don't dump NOTE_INSN_DELETED_DEBUG_LABEL.
	* var-tracking.c (debug_label_num): New variable.
	(delete_debug_insns): Don't delete DEBUG_INSNs for LABEL_DECLs,
	instead turn them into NOTE_INSN_DELETED_DEBUG_LABEL notes.
	* cfglayout.c (skip_insns_after_block, duplicate_insn_chain): Handle
	NOTE_INSN_DELETED_DEBUG_LABEL.
	(duplicate_insn_chain): Don't duplicate LABEL_DECL DEBUG_INSNs.
	* insn-notes.def (DELETED_DEBUG_LABEL): New note kind.
	* print-rtl.c (print_rtx): Handle NOTE_INSN_DELETED_DEBUG_LABEL.
	* gengtype.c (adjust_field_rtx_def): Likewise.
	* config/i386/i386.c (ix86_output_function_epilogue): For MachO
	clear CODE_LABEL_NUMBER of NOTE_INSN_DELETED_DEBUG_LABEL
	if their are at the end of function and nop hasn't been emitted.
	* config/rs6000/rs6000.c (rs6000_output_function_epilogue): Likewise.

From-SVN: r181014