* arm-tdep.c (arm_frame_is_thumb): New.
	(arm_pc_is_thumb): Clarify comment.
	(thumb_analyze_prologue): Remove PC special case.
	(thumb_scan_prologue): Take a block_addr argument.  Use it for
	find_pc_partial_function.  Remove unused variables.
	(arm_scan_prologue): Use arm_frame_is_thumb.  Use the block address
	for find_pc_partial_function.  Remove PC special case.
	(arm_prologue_prev_register): Add special handling for PC and CPSR.
	(arm_dwarf2_prev_register, arm_dwarf2_frame_init_reg): New.
	(arm_get_next_pc): Use arm_frame_is_thumb.
	(arm_write_pc): Use CPSR_T instead of 0x20.
	(arm_gdbarch_init): Call dwarf2_frame_set_init_reg.
	* arm-tdep.h (enum gdb_regnum): Add ARM_CPSR_REGNUM.
	(CPSR_T): Define.
	* dwarf2-frame.c (dwarf2_frame_prev_register): Handle
	DWARF2_FRAME_REG_FN.
	* dwarf2-frame.h (enum dwarf2_frame_reg_rule): Add
	DWARF2_FRAME_REG_FN.
	(struct dwarf2_frame_state_reg): Add FN to loc union.

	* gdb.arch/thumb-prologue.exp: Do not expect a saved PC.