compiler: reclaim memory of escape analysis Nodes

Reclaim the memory of escape analysis Nodes before kicking off
    the backend, as they are not needed in get_backend.
    
    Reviewed-on: https://go-review.googlesource.com/86243

From-SVN: r256707

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-afac7d7bed07ebe3add1784aaa9547c4d660d0ed
+ff851e1190923f8612004c6c214a7c202471b0ba
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/escape.cc

@@ -445,6 +445,17 @@ Node::state(Escape_context* context, Named_object* fn)
   return this->state_;
 }
 
+Node::~Node()
+{
+  if (this->state_ != NULL)
+    {
+      if (this->expr() == NULL || this->expr()->var_expression() == NULL)
+        // Var expression Node is excluded since it shares state with the
+        // underlying var Node.
+        delete this->state_;
+    }
+}
+
 int
 Node::encoding()
 {
@@ -552,6 +563,7 @@ Node::is_sink() const
 std::map<Named_object*, Node*> Node::objects;
 std::map<Expression*, Node*> Node::expressions;
 std::map<Statement*, Node*> Node::statements;
+std::vector<Node*> Node::indirects;
 
 // Make a object node or return a cached node for this object.
 
@@ -601,6 +613,7 @@ Node*
 Node::make_indirect_node(Node* child)
 {
   Node* n = new Node(child);
+  Node::indirects.push_back(n);
   return n;
 }
 
@@ -3335,3 +3348,39 @@ Gogo::tag_function(Escape_context* context, Named_object* fn)
   Escape_analysis_tag eat(context);
   eat.tag(fn);
 }
+
+// Reclaim memory of escape analysis Nodes.
+
+void
+Gogo::reclaim_escape_nodes()
+{
+  Node::reclaim_nodes();
+}
+
+void
+Node::reclaim_nodes()
+{
+  for (std::map<Named_object*, Node*>::iterator p = Node::objects.begin();
+       p != Node::objects.end();
+       ++p)
+    delete p->second;
+  Node::objects.clear();
+
+  for (std::map<Expression*, Node*>::iterator p = Node::expressions.begin();
+       p != Node::expressions.end();
+       ++p)
+    delete p->second;
+  Node::expressions.clear();
+
+  for (std::map<Statement*, Node*>::iterator p = Node::statements.begin();
+       p != Node::statements.end();
+       ++p)
+    delete p->second;
+  Node::statements.clear();
+
+  for (std::vector<Node*>::iterator p = Node::indirects.begin();
+       p != Node::indirects.end();
+       ++p)
+    delete *p;
+  Node::indirects.clear();
+}

gcc/go/gofrontend/escape.h

@@ -191,6 +191,8 @@ class Node
       child_(n)
   {}
 
+  ~Node();
+
   // Return this node's type.
   Type*
   type() const;
@@ -296,6 +298,10 @@ class Node
   static int
   note_inout_flows(int e, int index, Level level);
 
+  // Reclaim nodes.
+  static void
+  reclaim_nodes();
+
  private:
   // The classification of this Node.
   Node_classification classification_;
@@ -326,6 +332,10 @@ class Node
   static std::map<Named_object*, Node*> objects;
   static std::map<Expression*, Node*> expressions;
   static std::map<Statement*, Node*> statements;
+
+  // Collection of all NODE_INDIRECT Nodes, used for reclaiming memory. This
+  // is not a cache -- each make_indirect_node will make a fresh Node.
+  static std::vector<Node*> indirects;
 };
 
 // The amount of bits used for the escapement encoding.

gcc/go/gofrontend/go.cc

@@ -167,6 +167,9 @@ go_parse_input_files(const char** filenames, unsigned int filename_count,
   // Flatten the parse tree.
   ::gogo->flatten();
 
+  // Reclaim memory of escape analysis Nodes.
+  ::gogo->reclaim_escape_nodes();
+
   // Dump ast, use filename[0] as the base name
   ::gogo->dump_ast(filenames[0]);
 }

gcc/go/gofrontend/gogo.h

@@ -682,6 +682,10 @@ class Gogo
   void
   tag_function(Escape_context*, Named_object*);
 
+  // Reclaim memory of escape analysis Nodes.
+  void
+  reclaim_escape_nodes();
+
   // Do all exports.
   void
   do_exports();