tree-ssa-structalias: Put solver into its own file

tree-ssa-structalias: Put solver into its own file

This patch cuts out the points-to solver from tree-ssa-structalias.cc
and places it into a new file pta-andersen.cc.  It is the first part of
my effort to split tree-ssa-structalias.cc into smaller parts.

I had to give external linkage to some static functions and variables.
I put those in the new header files tree-ssa-structalias.h and
pta-andersen.h.  Those header files are meant as an internal interface
between parts of the points-to analyzer.

Some functions and variables already had external linkage and were declared in
tree-ssa-alias.h.  I considered moving the declarations to
tree-ssa-structalias.h but decided to leave them as is.  I see those functions
and variables as an external interface -- facing outwards to the rest of the
compiler.

For the internal interface, I made a new namespace "pointer_analysis".
I didn't want to clutter the global namespace and possibly run into ODR
problems.

I wanted to encapsulate the constraint graph within the solver. To achieve
that, I had to make some changes beyond just moving things around. They were
only very small changes, though:
- Add delete_graph() which gets called at the end of solve_constraints()
- Problem: The solver assigns representatives to variables (union-find).  To
  then get the solution for variable v, one has to look up the representative
  of v.  The information needed to look up the representative is part of the
  graph.
- Solution: Let the solver output an array that maps variables to their
  representatives and let this array outlive the graph (array var_rep).
  - Constructing the array means doing find() for every variable.  That should
    amortize to O(size of the union-find structure).  So this won't hurt the
    asymptotic time complexity.
  - We replace all calls to find(var) in tree-ssa-structalias.cc with
    just an array lookup var_rep[var].
- predbitmap_obstack gets initialized in init_graph().

gcc/ChangeLog:

	* Makefile.in: Add pta-andersen.o.
	* tree-ssa-structalias.cc (create_variable_info_for): Just move
	around.
	(unify_nodes): Move to pta-andersen.cc.
	(struct constraint): Move to tree-ssa-structalias.h.
	(EXECUTE_IF_IN_NONNULL_BITMAP): Move to pta-andersen.cc.
	(struct variable_info): Move to tree-ssa-structalias.h.
	(struct constraint_stats): Move to tree-ssa-structalias.h.
	(first_vi_for_offset): External linkage, move to namespace
	pointer_analysis.
	(first_or_preceding_vi_for_offset): External linkage, move to namespace
	pointer_analysis.
	(dump_constraint): External linkage, move to namespace
	pointer_analysis.
	(debug_constraint): External linkage, move to namespace
	pointer_analysis.
	(dump_constraints): External linkage, move to namespace
	pointer_analysis.
	(debug_constraints): External linkage, move to namespace
	pointer_analysis.
	(lookup_vi_for_tree): Move around inside tree-ssa-structalias.cc.
	(type_can_have_subvars): Move around inside tree-ssa-structalias.cc.
	(make_param_constraints): Move around inside tree-ssa-structalias.cc.
	(dump_solution_for_var): External linkage, move to namespace
	pointer_analysis.  find (...) -> var_rep[...].
	(get_varinfo): Move to tree-ssa-structalias.h.
	(debug_solution_for_var): External linkage, move to namespace
	pointer_analysis.
	(vi_next): Move to tree-ssa-structalias.h.
	(dump_sa_stats): External linkage, move to namespace pointer_analysis.
	(new_var_info): Just move around.
	(dump_sa_points_to_info): External linkage, move to namespace
	pointer_analysis.
	(debug_sa_points_to_info): External linkage, move to namespace
	pointer_analysis.
	(get_call_vi): Just move around.
	(dump_varinfo): External linkage, move to namespace pointer_analysis.
	(lookup_call_use_vi): Just move around.
	(lookup_call_clobber_vi): Just move around.
	(get_call_use_vi): Just move around.
	(get_call_clobber_vi): Just move around.
	(enum constraint_expr_type): Move to tree-ssa-structalias.h.
	(struct constraint_expr): Move to tree-ssa-structalias.h.
	(UNKNOWN_OFFSET): Move to tree-ssa-structalias.h.
	(get_constraint_for_1): Just move around.
	(get_constraint_for): Just move around.
	(get_constraint_for_rhs): Just move around.
	(do_deref): Just move around.
	(constraint_pool): Just move around.
	(struct constraint_graph): Move to pta-andersen.h.
	(FIRST_REF_NODE): Move to pta-andersen.cc.
	(LAST_REF_NODE): Move to pta-andersen.cc.
	(find): Move to pta-andersen.cc.
	(unite): Move to pta-andersen.cc.
	(new_constraint): Just move around.
	(debug_constraint_graph): External linkage, move to namespace
	pointer_analysis.
	(debug_varinfo): External linkage, move to namespace pointer_analysis.
	(debug_varmap): External linkage, move to namespace pointer_analysis.
	(dump_constraint_graph): External linkage, move to namespace
	pointer_analysis.
	(constraint_expr_equal): Move to pta-andersen.cc.
	(constraint_expr_less): Move to pta-andersen.cc.
	(constraint_less): Move to pta-andersen.cc.
	(constraint_equal): Move to pta-andersen.cc.
	(constraint_vec_find): Move to pta-andersen.cc.
	(constraint_set_union): Move to pta-andersen.cc.
	(solution_set_expand): Move to pta-andersen.cc.
	(set_union_with_increment): Move to pta-andersen.cc.
	(insert_into_complex): Move to pta-andersen.cc.
	(merge_node_constraints): Move to pta-andersen.cc.
	(clear_edges_for_node): Move to pta-andersen.cc.
	(merge_graph_nodes): Move to pta-andersen.cc.
	(add_implicit_graph_edge): Move to pta-andersen.cc.
	(add_pred_graph_edge): Move to pta-andersen.cc.
	(add_graph_edge): Move to pta-andersen.cc.
	(init_graph): Move to pta-andersen.cc.  Initialize
	predbitmap_obstack here.
	(build_pred_graph): Move to pta-andersen.cc.
	(build_succ_graph): Move to pta-andersen.cc.
	(class scc_info): Move to pta-andersen.cc.
	(scc_visit): Move to pta-andersen.cc.
	(solve_add_graph_edge): Move to pta-andersen.cc.
	(do_sd_constraint): Move to pta-andersen.cc.
	(do_ds_constraint): Move to pta-andersen.cc.
	(do_complex_constraint): Move to pta-andersen.cc.
	(scc_info::scc_info): Move to pta-andersen.cc.
	(scc_info::~scc_info): Move to pta-andersen.cc.
	(find_indirect_cycles): Move to pta-andersen.cc.
	(topo_visit): Move to pta-andersen.cc.
	(compute_topo_order): Move to pta-andersen.cc.
	(struct equiv_class_hasher): Move to pta-andersen.cc.
	(equiv_class_hasher::hash): Move to pta-andersen.cc.
	(equiv_class_hasher::equal): Move to pta-andersen.cc.
	(equiv_class_lookup_or_add): Move to pta-andersen.cc.
	(condense_visit): Move to pta-andersen.cc.
	(label_visit): Move to pta-andersen.cc.
	(dump_pred_graph): External linkage, move to namespace
	pointer_analysis.
	(dump_varmap): External linkage, move to namespace pointer_analysis.
	(perform_var_substitution): Move to pta-andersen.cc.
	(free_var_substitution_info): Move to pta-andersen.cc.
	(find_equivalent_node): Move to pta-andersen.cc.
	(unite_pointer_equivalences): Move to pta-andersen.cc.
	(move_complex_constraints): Move to pta-andersen.cc.
	(rewrite_constraints): Move to pta-andersen.cc.
	(eliminate_indirect_cycles): Move to pta-andersen.cc.
	(solve_graph): Move to pta-andersen.cc.
	(set_uids_in_ptset): find (...) -> var_rep[...].
	(find_what_var_points_to): find (...) -> var_rep[...].
	(init_alias_vars): Don't initialize predbitmap_obstack here.
	(remove_preds_and_fake_succs): Move to pta-andersen.cc.
	(solve_constraints): Move to pta-andersen.cc.  Call
	delete_graph() at the end.
	(delete_points_to_sets): Don't delete graph here.  Delete var_rep here.
	(visit_loadstore): find (...) -> var_rep[...].
	(compute_dependence_clique): find (...) -> var_rep[...].
	(ipa_pta_execute): find (...) -> var_rep[...].
	* pta-andersen.cc: New file.
	* pta-andersen.h: New file.
	* tree-ssa-structalias.h: New file.

Signed-off-by: Filip Kastl <fkastl@suse.cz>