re PR target/46030 (registers trashed with -Os)

re PR target/46030 (registers trashed with -Os)

	PR target/46030
	* config/rs6000/rs6000.c (struct rs6000_stack): Add reload_completed
	and savres_strategy.
	(stack_info): New file scope var.
	(rs6000_init_machine_status): Init stack_info.
	(SAVRES_INLINE_FPRS, SAVRES_INLINE_GPRS,
	SAVRES_NOINLINE_GPRS_SAVES_LR, SAVRES_NOINLINE_FPRS_SAVES_LR,
	SAVRES_NOINLINE_FPRS_DOESNT_RESTORE_LR): Replace with..
	(SAVE_INLINE_FPRS, SAVE_INLINE_GPRS, REST_INLINE_FPRS, REST_INLINE_GPRS,
	SAVE_NOINLINE_GPRS_SAVES_LR, SAVE_NOINLINE_FPRS_SAVES_LR
	REST_NOINLINE_FPRS_DOESNT_RESTORE_LR): ..this.  Update all refs.
	(rs6000_savres_strategy): Rewrite.
	(rs6000_stack_info): Use "stack_info" in place of local "info".
	Return cached stack info when reload_completed unless ENABLE_CHECKING
	in which case confirm newly calculated stack info matches old info.
	Delay calculation of lr_save_p, set it for out of line gp save/restore
	as well as fp.  Call rs6000_savres_strategy from here..
	(rs6000_emit_prologue, rs6000_emit_epilogue): ..rather than here.
	(rs6000_output_function_prologue): Use info->savres_strategy to
	determine whether fp save/restore externs need to be emitted.

From-SVN: r166125