re PR rtl-optimization/88870 (ICE: Segmentation fault (in df_worklist_propagate_backward))

	PR rtl-optimization/88870
	* dce.c (deletable_insn_p): Never delete const/pure calls that can
	throw if we can't alter the cfg or delete dead exceptions.
	(mark_insn): Don't call find_call_stack_args for such calls.

	* gcc.dg/pr88870.c: New test.

From-SVN: r268008