New CSEMap datastructure impl

llvm-svn: 29555

include/llvm/CodeGen/SelectionDAGCSEMap.h

@@ -0,0 +1,114 @@
+//===-- llvm/CodeGen/SelectionDAGCSEMap.h - CSE Map for SD ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the SelectionDAG class, and transitively defines the
+// SDNode class and subclasses.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SELECTIONDAGCSEMAP_H
+#define LLVM_CODEGEN_SELECTIONDAGCSEMAP_H
+
+#include "llvm/ADT/SmallVector.h"
+
+namespace llvm {
+  class SDNode;
+  class SDOperand;
+  
+  /// SelectionDAGCSEMap - This class is used for two purposes:
+  ///   1. Given information (e.g. opcode and operand info) about a node we want
+  ///      to create, look up the unique instance of the node in the map.  If
+  ///      the node already exists, return it, otherwise return the bucket it
+  ///      should be inserted into.
+  ///   2. Given a node that has already been created, remove it from the CSE
+  ///      map.
+  /// 
+  /// This class is implemented as a chained hash table, where the "buckets" are
+  /// actually the SDNodes themselves (the next pointer is in the SDNode).
+  ///
+  class SelectionDAGCSEMap {
+    void **Buckets;
+    unsigned NumBuckets;  // Always a power of 2.
+  public:
+    class NodeID;
+    SelectionDAGCSEMap();
+    ~SelectionDAGCSEMap();
+    
+    /// RemoveNode - Remove a node from the CSE map, returning true if one was
+    /// removed or false if the node was not in the CSE map.
+    bool RemoveNode(SDNode *N);
+    
+    /// GetOrInsertSimpleNode - If there is an existing simple SDNode exactly
+    /// equal to the specified node, return it.  Otherwise, insert 'N' and it
+    /// instead.  This only works on *simple* SDNodes, not ConstantSDNode or any
+    /// other classes derived from SDNode.
+    SDNode *GetOrInsertNode(SDNode *N);
+    
+    /// FindNodeOrInsertPos - Look up the node specified by ID.  If it exists,
+    /// return it.  If not, return the insertion token that will make insertion
+    /// faster.
+    SDNode *FindNodeOrInsertPos(const NodeID &ID, void *&InsertPos);
+    
+    /// InsertNode - Insert the specified node into the CSE Map, knowing that it
+    /// is not already in the map.  InsertPos must be obtained from 
+    /// FindNodeOrInsertPos.
+    void InsertNode(SDNode *N, void *InsertPos);
+    
+    class NodeID {
+      /// Use a SmallVector to avoid a heap allocation in the common case.
+      ///
+      SmallVector<unsigned char, 256> Bits;
+    public:
+      NodeID() {}
+      NodeID(SDNode *N);
+      NodeID(unsigned short ID, const void *VTList);
+      NodeID(unsigned short ID, const void *VTList, SDOperand Op);
+      NodeID(unsigned short ID, const void *VTList, 
+             SDOperand Op1, SDOperand Op2);
+      NodeID(unsigned short ID, const void *VTList, 
+             SDOperand Op1, SDOperand Op2, SDOperand Op3);
+      NodeID(unsigned short ID, const void *VTList, 
+             const SDOperand *OpList, unsigned N);
+      
+      void SetOpcode(unsigned short ID) {
+        Bits.push_back(ID & 0xFF);
+        Bits.push_back(ID >> 8);
+      }
+      
+      /// getOpcode - If the opcode has been set for this NodeID, return it.
+      unsigned getOpcode() const {
+        return Bits[0] + (Bits[1] << 8);
+      }
+
+      void SetValueTypes(const void *VTList) { AddPointer(VTList); }
+      void SetOperands() {}
+      void SetOperands(SDOperand Op) { AddOperand(Op); }
+      void SetOperands(SDOperand Op1, SDOperand Op2) {
+        AddOperand(Op1); AddOperand(Op2);
+      }
+      void SetOperands(SDOperand Op1, SDOperand Op2, SDOperand Op3) {
+        AddOperand(Op1); AddOperand(Op2); AddOperand(Op3);
+      }
+      void SetOperands(const SDOperand *Ops, unsigned NumOps);
+      void AddOperand(SDOperand Op);
+      void AddPointer(const void *Ptr);
+      
+      unsigned ComputeHash() const;
+      
+      bool operator==(const NodeID &RHS) const;
+    };
+    
+  private:
+    SDNode *GetNextPtr(void *NextInBucketPtr);
+    void **GetBucketPtr(void *NextInBucketPtr);
+    void **GetBucketFor(const NodeID &ID) const;
+  };
+}  // end namespace llvm
+
+#endif