analyzer: consolidate call_string instances

ana::call_string is a wrapper around an auto_vec of callsites, leading
to non-trivial copying when copying around call_string instances, e.g.
in ana::program_point.

This patch consolidates call_string instances within the
region_model_manager: it now owns the root/empty call_string, and
each call_string instance tracks its children, lazily creating them on
demand, so that the call_string instances form a tree-like hierarchy in
memory.  Doing this requires passing the region_model_manager to the
various program_point factory methods, so that they can get at the root
call_string.

Instances of call_string become immutable (apart from their internal
cache for looking up their children); operations that previously
modified them now return the call_string for the result of the
operation.

I wasn't able to observe any performance impact of this, but it
simplifies call_string and program_point management, and thus I hope
will make it easier to improve call summarization.  In particular,
region_model_manager::log_stats will now print a hierarchical dump of
all the call_string instances used in the analysis (in -fdump-analyzer
and -fdump-analyzer-stderr).

gcc/analyzer/ChangeLog:
	* call-string.cc: Add includes of "analyzer/analyzer.h"
	and "analyzer/analyzer-logging.h".
	(call_string::call_string): Delete copy ctor.
	(call_string::operator=): Delete.
	(call_string::operator==): Delete.
	(call_string::hash): Delete.
	(call_string::push_call): Make const, returning the resulting
	call_string.
	(call_string::pop): Delete.
	(call_string::cmp_ptr_ptr): New.
	(call_string::validate): Assert that m_parent is non-NULL, or
	m_elements is empty.
	(call_string::call_string): Move default ctor here from
	call-string.h and reimplement.  Add ctor taking a parent
	and an element.
	(call_string::~call_string): New.
	(call_string::recursive_log): New.
	* call-string.h (call_string::call_string): Move default ctor's
	defn to call-string.cc.  Delete copy ctor.  Add ctor taking a
	parent and an element.
	(call_string::operator=): Delete.
	(call_string::operator==): Delete.
	(call_string::hash): Delete.
	(call_string::push_call): Make const, returning the resulting
	call_string.
	(call_string::pop): Delete decl.
	(call_string::get_parent): New.
	(call_string::cmp_ptr_ptr): New decl.
	(call_string::get_top_of_stack): New.
	(struct call_string::hashmap_traits_t): New.
	(class call_string): Add friend class region_model_manager.  Add
	DISABLE_COPY_AND_ASSIGN.
	(call_string::~call_string): New decl.
	(call_string::recursive_log): New decl.
	(call_string::m_parent): New field.
	(call_string::m_children): New field.
	* constraint-manager.cc (selftest::test_many_constants): Pass
	model manager to program_point::origin.
	* engine.cc (exploded_graph::exploded_graph): Likewise.
	(exploded_graph::add_function_entry): Likewise for
	program_point::from_function_entry.
	(add_tainted_args_callback): Likewise.
	(exploded_graph::maybe_process_run_of_before_supernode_enodes):
	Update for change to program_point.get_call_string.
	(exploded_graph::process_node): Likewise.
	(class function_call_string_cluster): Convert m_cs from a
	call_string to a const call_string &.
	(struct function_call_string): Likewise.
	(pod_hash_traits<function_call_string>::hash): Use pointer_hash
	for m_cs.
	(pod_hash_traits<function_call_string>::equal): Update for change
	to m_cs.
	(root_cluster::add_node): Update for change to
	function_call_string.
	(viz_callgraph_node::dump_dot): Update for change to call_string.
	* exploded-graph.h (per_call_string_data::m_key): Convert to a
	reference.
	(struct eg_call_string_hash_map_traits): Delete.
	(exploded_graph::call_string_data_map_t): Remove traits class.
	* program-point.cc: Move include of "analyzer/call-string.h" to
	after "analyzer/analyzer-logging.h".
	(program_point::print): Update for conversion of m_call_string to
	a pointer.
	(program_point::to_json): Likewise.
	(program_point::push_to_call_stack): Update for immutability of
	call strings.
	(program_point::pop_from_call_stack): Likewise.
	(program_point::hash): Use pointer hashing for m_call_string.
	(program_point::get_function_at_depth): Update for change to
	m_call_string.
	(program_point::validate): Update for changes to call_string.
	(program_point::on_edge): Likewise.
	(program_point::origin): Move here from call-string.h.  Add
	region_model_manager param and use it to get empty call string.
	(program_point::from_function_entry): Likewise.
	(selftest::test_function_point_ordering): Likewise.
	(selftest::test_function_point_ordering): Likewise.
	* program-point.h (program_point::program_point): Update for
	change to m_call_string.
	(program_point::get_call_string): Likewise.
	(program_point::get_stack_depth): Likewise.
	(program_point::origin): Add region_model_manager param, and move
	defn to call-string.cc.
	(program_point::from_function_entry): Likewise.
	(program_point::empty): Drop call_string.
	(program_point::deleted): Likewise.
	(program_point::program_point): New private ctor.
	(program_point::m_call_string): Convert from call_string to const
	call_string *.
	* program-state.cc (selftest::test_program_state_merging): Update
	for call_string changes.
	(selftest::test_program_state_merging_2): Likewise.
	* region-model-manager.cc
	(region_model_manager::region_model_manager): Construct
	m_empty_call_string.
	(region_model_manager::log_stats): Log the call strings.
	* region-model.cc (assert_region_models_merge): Pass the
	region_model_manager when creating program_point instances.
	(selftest::test_state_merging): Likewise.
	(selftest::test_constraint_merging): Likewise.
	(selftest::test_widening_constraints): Likewise.
	(selftest::test_iteration_1): Likewise.
	* region-model.h (region_model_manager::get_empty_call_string):
	New.
	(region_model_manager::m_empty_call_string): New.
	* sm-signal.cc (register_signal_handler::impl_transition): Update
	for changes to call_string.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/gcc/analyzer/program-state.cc b/gcc/analyzer/program-state.cc
index 7ad581c..295c6ae 100644
--- a/gcc/analyzer/program-state.cc
+++ b/gcc/analyzer/program-state.cc
@@ -1668,12 +1668,12 @@ test_program_state_merging ()
      malloc sm-state, pointing to a region on the heap.  */
   tree p = build_global_decl ("p", ptr_type_node);
 
-  program_point point (program_point::origin ());
+  engine eng;
+  region_model_manager *mgr = eng.get_model_manager ();
+  program_point point (program_point::origin (*mgr));
   auto_delete_vec <state_machine> checkers;
   checkers.safe_push (make_malloc_state_machine (NULL));
-  engine eng;
   extrinsic_state ext_state (checkers, &eng);
-  region_model_manager *mgr = eng.get_model_manager ();
 
   program_state s0 (ext_state);
   uncertainty_t uncertainty;
@@ -1736,10 +1736,11 @@ test_program_state_merging ()
 static void
 test_program_state_merging_2 ()
 {
-  program_point point (program_point::origin ());
+  engine eng;
+  region_model_manager *mgr = eng.get_model_manager ();
+  program_point point (program_point::origin (*mgr));
   auto_delete_vec <state_machine> checkers;
   checkers.safe_push (make_signal_state_machine (NULL));
-  engine eng;
   extrinsic_state ext_state (checkers, &eng);
 
   const state_machine::state test_state_0 ("test state 0", 0);