re PR debug/64817 (compilation hangs at -O3 with -g enabled on x86_64-linux-gnu)

re PR debug/64817 (compilation hangs at -O3 with -g enabled on x86_64-linux-gnu)

	PR debug/64817
	* cfgexpand.c (deep_ter_debug_map): New variable.
	(avoid_deep_ter_for_debug): New function.
	(expand_debug_expr): If TERed SSA_NAME is in
	deep_ter_debug_map, use the corresponding DEBUG_EXPR_DECL
	instead of trying to expand SSA_NAME's def stmt.
	(expand_debug_locations): When expanding debug bind
	of a DEBUG_EXPR_DECL to corresponding SSA_NAME,
	temporarily remove the DEBUG_EXPR_DECL from deep_ter_debug_map's
	value.
	(pass_expand::execute): Call avoid_deep_ter_for_debug on
	all debug bind stmts.  Delete deep_ter_debug_map after
	expand_debug_location if non-NULL and clear it.

	* gcc.dg/pr64817-1.c: New test.
	* gcc.dg/pr64817-2.c: New test.

From-SVN: r220320