dwarf2out.c: Added explanation of abbreviations.

dwarf2out.c: Added explanation of abbreviations.

2001-02-01  Jeffrey Oldham  <oldham@codesourcery.com>

	* dwarf2out.c: Added explanation of abbreviations.
	(def_cfa_1): Added comments listing DWARF2 instructions.
	(cfa_temp_reg): Removed in favor of cfa_temp.
	(cfa_temp_value): Removed in favor of cfa_temp.
	(cfa_temp): New global variable.
	(dwarf2out_frame_debug_expr): Added extensive introductory
	comments explaining the function's transformations.  Revised to
	use cfa_temp.  Added some rtx checking.  Generalize IOR case.
	(dwarf2out_frame_debug): Revised to use cfa_temp.
	(output_aranges): Cast as "unsigned" to avoid warning.
	* rtl.texi (RTX_FRAME_RELATED_P): Revise entry to emphasize better
	explain which instructions must be marked.

From-SVN: r39405