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, 16 insertions, 19 deletions

diff --git a/gcc/analyzer/program-point.h b/gcc/analyzer/program-point.h
index 6084c9e..63f7224 100644
--- a/gcc/analyzer/program-point.h
+++ b/gcc/analyzer/program-point.h
@@ -174,7 +174,7 @@ public:
   program_point (const function_point &fn_point,
 		 const call_string &call_string)
   : m_function_point (fn_point),
-    m_call_string (call_string)
+    m_call_string (&call_string)
   {
   }
 
@@ -197,7 +197,7 @@ public:
   /* Accessors.  */
 
   const function_point &get_function_point () const { return m_function_point; }
-  const call_string &get_call_string () const { return m_call_string; }
+  const call_string &get_call_string () const { return *m_call_string; }
 
   const supernode *get_supernode () const
   {
@@ -242,23 +242,14 @@ public:
   {
     if (get_kind () == PK_ORIGIN)
       return 0;
-    return m_call_string.length () + 1;
+    return get_call_string ().length () + 1;
   }
 
   /* Factory functions for making various kinds of program_point.  */
-  static program_point origin ()
-  {
-    return program_point (function_point (NULL, NULL,
-					  0, PK_ORIGIN),
-			  call_string ());
-  }
-
-  static program_point from_function_entry (const supergraph &sg,
-					    function *fun)
-  {
-    return program_point (function_point::from_function_entry (sg, fun),
-			  call_string ());
-  }
+  static program_point origin (const region_model_manager &mgr);
+  static program_point from_function_entry (const region_model_manager &mgr,
+					    const supergraph &sg,
+					    function *fun);
 
   static program_point before_supernode (const supernode *supernode,
 					 const superedge *from_edge,
@@ -288,11 +279,11 @@ public:
 
   static program_point empty ()
   {
-    return program_point (function_point::empty (), call_string ());
+    return program_point (function_point::empty ());
   }
   static program_point deleted ()
   {
-    return program_point (function_point::deleted (), call_string ());
+    return program_point (function_point::deleted ());
   }
 
   bool on_edge (exploded_graph &eg, const superedge *succ);
@@ -306,8 +297,14 @@ public:
   program_point get_next () const;
 
  private:
+  program_point (const function_point &fn_point)
+  : m_function_point (fn_point),
+    m_call_string (NULL)
+  {
+  }
+
   function_point m_function_point;
-  call_string m_call_string;
+  const call_string *m_call_string;
 };
 
 } // namespace ana