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24 
25 #ifndef SHARE_OPTO_REPLACEDNODES_HPP
26 #define SHARE_OPTO_REPLACEDNODES_HPP
27 
28 #include "opto/connode.hpp"
29 
30 // During parsing, when a node is "improved",
31 // GraphKit::replace_in_map() is called to update the current map so
32 // that the improved node is used from that point
33 // on. GraphKit::replace_in_map() doesn't operate on the callers maps
34 // and so some optimization opportunities may be lost. The
35 // ReplacedNodes class addresses that problem.
36 //
37 // A ReplacedNodes object is a list of pair of nodes. Every
38 // SafePointNode carries a ReplacedNodes object. Every time
39 // GraphKit::replace_in_map() is called, a new pair of nodes is pushed
40 // on the list of replaced nodes. When control flow paths merge, their
41 // replaced nodes are also merged. When parsing exits a method to
42 // return to a caller, the replaced nodes on the exit path are used to
43 // update the caller's map.
44 class ReplacedNodes {
45  private:
46   class ReplacedNode {
47   private:
48     Node* _initial;
49     Node* _improved;
50   public:
ReplacedNode()51     ReplacedNode() : _initial(NULL), _improved(NULL) {}
ReplacedNode(Node * initial,Node * improved)52     ReplacedNode(Node* initial, Node* improved) : _initial(initial), _improved(improved) {}
initial() const53     Node* initial() const  { return _initial; }
improved() const54     Node* improved() const { return _improved; }
55 
operator ==(const ReplacedNode & other)56     bool operator==(const ReplacedNode& other) {
57       return _initial == other._initial && _improved == other._improved;
58     }
59   };
60   GrowableArray<ReplacedNode>* _replaced_nodes;
61 
62   void allocate_if_necessary();
63   bool has_node(const ReplacedNode& r) const;
64   bool has_target_node(Node* n) const;
65 
66  public:
ReplacedNodes()67   ReplacedNodes()
68     : _replaced_nodes(NULL) {}
69 
70   void clone();
71   void record(Node* initial, Node* improved);
72   void transfer_from(const ReplacedNodes& other, uint idx);
73   void reset();
74   void apply(Node* n, uint idx);
75   void merge_with(const ReplacedNodes& other);
76   bool is_empty() const;
77   void dump(outputStream *st) const;
78   void apply(Compile* C, Node* ctl);
79 };
80 
81 #endif // SHARE_OPTO_REPLACEDNODES_HPP
82