Hi Richi and Martin,

>>
>> Thanks Richi!  One draft (not ready for review) is attached for the further
>> discussion.  It follows the idea of RAII-style cleanup.  I noticed that
>> Martin suggested stepping forward to make tree_predictive_commoning_loop
>> and its callees into one class (Thanks Martin), since there are not many
>> this kind of C++-style work functions, I want to double confirm which option
>> do you guys prefer?
>>
> 
> Such general cleanup is of course desired - Giuliano started some of it within
> GSoC two years ago in the attempt to thread the compilation process.  The
> cleanup then helps to get rid of global state which of course interferes here
> (and avoids unnecessary use of TLS vars).
> 
> So yes, encapsulating global state into a class and making accessors
> member functions is something that is desired (but a lot of mechanical
> work).
> 
> Thanks
> Richard.
> 
> I meant that not necessarily as something to include in this patch
> but as a suggestion for a future improvement.  If you'd like to
> tackle it at any point that would be great of course   In any
> event, thanks for double-checking!
>
> The attached patch looks good to me as well (more for the sake of
> style than anything else, declaring the class copy ctor and copy assignment = delete would > make it clear it's not meant to be
> copied, although in this case it's unlikely to make a practical
> difference). 
> 
> Martin.


Thanks for your explanation!  Sorry for the late response.
As the way to encapsulate global state into a class and making accessors
member functions looks more complete, I gave up the RAII draft and
switched onto this way.

This patch is to encapsulate global states into a class and
making their accessors as member functions, remove some
consequent useless clean up code, and do some clean up with
RAII.

Bootstrapped/regtested on powerpc64le-linux-gnu P9,
x86_64-redhat-linux and aarch64-linux-gnu, also
bootstrapped on ppc64le P9 with bootstrap-O3 config.

Is it ok for trunk?

BR,
Kewen
-----
gcc/ChangeLog:

	* tree-predcom.c (class pcom_worker): New class.
	(release_chain): Renamed to...
	(pcom_worker::release_chain): ...this.
	(release_chains): Renamed to...
	(pcom_worker::release_chains): ...this.
	(aff_combination_dr_offset): Renamed to...
	(pcom_worker::aff_combination_dr_offset): ...this.
	(determine_offset): Renamed to...
	(pcom_worker::determine_offset): ...this.
	(class comp_ptrs): New class.
	(split_data_refs_to_components): Renamed to...
	(pcom_worker::split_data_refs_to_components): ...this,
	and update with class comp_ptrs.
	(suitable_component_p): Renamed to...
	(pcom_worker::suitable_component_p): ...this.
	(filter_suitable_components): Renamed to...
	(pcom_worker::filter_suitable_components): ...this.
	(valid_initializer_p): Renamed to...
	(pcom_worker::valid_initializer_p): ...this.
	(find_looparound_phi): Renamed to...
	(pcom_worker::find_looparound_phi): ...this.
	(add_looparound_copies): Renamed to...
	(pcom_worker::add_looparound_copies): ...this.
	(determine_roots_comp): Renamed to...
	(pcom_worker::determine_roots_comp): ...this.
	(determine_roots): Renamed to...
	(pcom_worker::determine_roots): ...this.
	(single_nonlooparound_use): Renamed to...
	(pcom_worker::single_nonlooparound_use): ...this.
	(remove_stmt): Renamed to...
	(pcom_worker::remove_stmt): ...this.
	(execute_pred_commoning_chain): Renamed to...
	(pcom_worker::execute_pred_commoning_chain): ...this.
	(execute_pred_commoning): Renamed to...
	(pcom_worker::execute_pred_commoning): ...this.
	(struct epcc_data): New member worker.
	(execute_pred_commoning_cbck): Call execute_pred_commoning
	with pcom_worker pointer.
	(find_use_stmt): Renamed to...
	(pcom_worker::find_use_stmt): ...this.
	(find_associative_operation_root): Renamed to...
	(pcom_worker::find_associative_operation_root): ...this.
	(find_common_use_stmt): Renamed to...
	(pcom_worker::find_common_use_stmt): ...this.
	(combinable_refs_p): Renamed to...
	(pcom_worker::combinable_refs_p): ...this.
	(reassociate_to_the_same_stmt): Renamed to...
	(pcom_worker::reassociate_to_the_same_stmt): ...this.
	(stmt_combining_refs): Renamed to...
	(pcom_worker::stmt_combining_refs): ...this.
	(combine_chains): Renamed to...
	(pcom_worker::combine_chains): ...this.
	(try_combine_chains): Renamed to...
	(pcom_worker::try_combine_chains): ...this.
	(prepare_initializers_chain): Renamed to...
	(pcom_worker::prepare_initializers_chain): ...this.
	(prepare_initializers): Renamed to...
	(pcom_worker::prepare_initializers): ...this.
	(prepare_finalizers_chain): Renamed to...
	(pcom_worker::prepare_finalizers_chain): ...this.
	(prepare_finalizers): Renamed to...
	(pcom_worker::prepare_finalizers): ...this.
	(tree_predictive_commoning_loop): Renamed to...
	(pcom_worker::tree_predictive_commoning_loop): ...this, adjust
	some calls and remove some cleanup code.
	(tree_predictive_commoning): Adjusted to use pcom_worker instance.
	(static variable looparound_phis): Remove.
	(static variable name_expansions): Remove.