rs6000: Separate shrink-wrapping for the TOC register

rs6000: Separate shrink-wrapping for the TOC register

This makes the TOC register save a component.  If -msave-toc-indirect
is not explicitly disabled, it enables it, and then moves the prologue
code generated for that to a better place.  So far this only matters
for indirect calls (for direct calls the save is done in the PLT stub).
The restore is always done directly after the bl insn (the compiler
generates a nop there, the linker replaces it with a load).

	* config/rs6000/rs6000.c (machine_function): Add a bool,
	"toc_is_wrapped_separately".
	(rs6000_option_override_internal): Enable OPTION_MASK_SAVE_TOC_INDIRECT
	if it wasn't explicitly set or unset, we are optimizing for speed, and
	doing separate shrink-wrapping.
	(rs6000_get_separate_components): Enable the TOC component if
	saving the TOC register in the prologue.
	(rs6000_components_for_bb): Handle the TOC component.
	(rs6000_emit_prologue_components): Store the TOC register where needed.
	(rs6000_set_handled_components): Mark TOC as handled, if handled.
	(rs6000_emit_prologue): Don't save the TOC if that is already done.

From-SVN: r254599