rs6000: Separate shrink-wrapping

rs6000: Separate shrink-wrapping

This implements the hooks for separate shrink-wrapping for rs6000.
It handles GPRs and LR.  The GPRs get a component number corresponding
to their register number; LR gets component number 0.

	* config/rs6000/rs6000.c (machine_function): Add new fields
	gpr_is_wrapped_separately and lr_is_wrapped_separately.
	(TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS,
	TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB,
	TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS,
	TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS,
	TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS,
	TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS): Define.
	(rs6000_get_separate_components): New function.
	(rs6000_components_for_bb): New function.
	(rs6000_disqualify_components): New function.
	(rs6000_emit_prologue_components): New function.
	(rs6000_emit_epilogue_components): New function.
	(rs6000_set_handled_components): New function.
	(rs6000_emit_prologue): Don't emit LR save if lr_is_wrapped_separately.
	Don't emit GPR saves if gpr_is_wrapped_separately for that register.
	(restore_saved_lr): Don't restore LR if lr_is_wrapped_separately.
	(rs6000_emit_epilogue): Don't emit GPR restores if
	gpr_is_wrapped_separately for that register.  Don't make a
	REG_CFA_RESTORE note for registers we did not restore, either.

From-SVN: r241065