rtl-ssa: Rework _ignoring interfaces

rtl-ssa: Rework _ignoring interfaces

rtl-ssa has routines for scanning forwards or backwards for something
under the control of an exclusion set.  These searches are currently
used for two main things:

- to work out where an instruction can be moved within its EBB
- to work out whether recog can add a new hard register clobber

The exclusion set was originally a callback function that returned
true for insns that should be ignored.  However, for the late-combine
work, I'd also like to be able to skip an entire definition, along
with all its uses.

This patch prepares for that by turning the exclusion set into an
object that provides predicate member functions.  Currently the
only two member functions are:

- should_ignore_insn: what the old callback did
- should_ignore_def: the new functionality

but more could be added later.

Doing this also makes it easy to remove some asymmetry that I think
in hindsight was a mistake: in forward scans, ignoring an insn meant
ignoring all definitions in that insn (ok) and all uses of those
definitions (non-obvious).  The new interface makes it possible
to select the required behaviour, with that behaviour being applied
consistently in both directions.

Now that the exclusion set is a dedicated object, rather than
just a "random" function, I think it makes sense to remove the
_ignoring suffix from the function names.  The suffix was originally
there to describe the callback, and in particular to emphasise that
a true return meant "ignore" rather than "heed".

gcc/
	* rtl-ssa.h: Include predicates.h.
	* rtl-ssa/predicates.h: New file.
	* rtl-ssa/access-utils.h (prev_call_clobbers_ignoring): Rename to...
	(prev_call_clobbers): ...this and treat the ignore parameter as an
	object with the same interface as ignore_nothing.
	(next_call_clobbers_ignoring): Rename to...
	(next_call_clobbers): ...this and treat the ignore parameter as an
	object with the same interface as ignore_nothing.
	(first_nondebug_insn_use_ignoring): Rename to...
	(first_nondebug_insn_use): ...this and treat the ignore parameter as
	an object with the same interface as ignore_nothing.
	(last_nondebug_insn_use_ignoring): Rename to...
	(last_nondebug_insn_use): ...this and treat the ignore parameter as
	an object with the same interface as ignore_nothing.
	(last_access_ignoring): Rename to...
	(last_access): ...this and treat the ignore parameter as an object
	with the same interface as ignore_nothing.  Conditionally skip
	definitions.
	(prev_access_ignoring): Rename to...
	(prev_access): ...this and treat the ignore parameter as an object
	with the same interface as ignore_nothing.
	(first_def_ignoring): Replace with...
	(first_access): ...this new function.
	(next_access_ignoring): Rename to...
	(next_access): ...this and treat the ignore parameter as an object
	with the same interface as ignore_nothing.  Conditionally skip
	definitions.
	* rtl-ssa/change-utils.h (insn_is_changing): Delete.
	(restrict_movement_ignoring): Rename to...
	(restrict_movement): ...this and treat the ignore parameter as an
	object with the same interface as ignore_nothing.
	(recog_ignoring): Rename to...
	(recog): ...this and treat the ignore parameter as an object with
	the same interface as ignore_nothing.
	* rtl-ssa/changes.h (insn_is_changing_closure): Delete.
	* rtl-ssa/functions.h (function_info::add_regno_clobber): Treat
	the ignore parameter as an object with the same interface as
	ignore_nothing.
	* rtl-ssa/insn-utils.h (insn_is): Delete.
	* rtl-ssa/insns.h (insn_is_closure): Delete.
	* rtl-ssa/member-fns.inl
	(insn_is_changing_closure::insn_is_changing_closure): Delete.
	(insn_is_changing_closure::operator()): Likewise.
	(function_info::add_regno_clobber): Treat the ignore parameter
	as an object with the same interface as ignore_nothing.
	(ignore_changing_insns::ignore_changing_insns): New function.
	(ignore_changing_insns::should_ignore_insn): Likewise.
	* rtl-ssa/movement.h (restrict_movement_for_dead_range): Treat
	the ignore parameter as an object with the same interface as
	ignore_nothing.
	(restrict_movement_for_defs_ignoring): Rename to...
	(restrict_movement_for_defs): ...this and treat the ignore parameter
	as an object with the same interface as ignore_nothing.
	(restrict_movement_for_uses_ignoring): Rename to...
	(restrict_movement_for_uses): ...this and treat the ignore parameter
	as an object with the same interface as ignore_nothing.  Conditionally
	skip definitions.
	* doc/rtl.texi: Update for above name changes.  Use
	ignore_changing_insns instead of insn_is_changing.
	* config/aarch64/aarch64-cc-fusion.cc (cc_fusion::parallelize_insns):
	Likewise.
	* pair-fusion.cc (no_ignore): Delete.
	(latest_hazard_before, first_hazard_after): Update for above name
	changes.  Use ignore_nothing instead of no_ignore.
	(pair_fusion_bb_info::fuse_pair): Update for above name changes.
	Use ignore_changing_insns instead of insn_is_changing.
	(pair_fusion::try_promote_writeback): Likewise.