path: root/include/llvm/CodeGen/SelectionDAG.h

//===-- llvm/CodeGen/SelectionDAG.h - InstSelection DAG ---------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group 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_SELECTIONDAG_H
#define LLVM_CODEGEN_SELECTIONDAG_H

#include "llvm/CodeGen/SelectionDAGNodes.h"
#include <map>
#include <string> // FIXME remove eventually, turning map into const char* map.

namespace llvm {
  class TargetLowering;
  class TargetMachine;
  class MachineFunction;

/// SelectionDAG class - This is used to represent a portion of an LLVM function
/// in a low-level Data Dependence DAG representation suitable for instruction
/// selection.  This DAG is constructed as the first step of instruction
/// selection in order to allow implementation of machine specific optimizations
/// and code simplifications.
///
/// The representation used by the SelectionDAG is a target-independent
/// representation, which has some similarities to the GCC RTL representation,
/// but is significantly more simple, powerful, and is a graph form instead of a
/// linear form.
///
class SelectionDAG {
  TargetLowering &TLI;
  MachineFunction &MF;

  // Root - The root of the entire DAG.  EntryNode - The starting token.
  SDOperand Root, EntryNode;

  // AllNodes - All of the nodes in the DAG
  std::vector<SDNode*> AllNodes;

  // ValueNodes - track SrcValue nodes
  std::map<std::pair<const Value*, int>, SDNode*> ValueNodes;

public:
  SelectionDAG(TargetLowering &tli, MachineFunction &mf) : TLI(tli), MF(mf) {
    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
  }
  ~SelectionDAG();

  MachineFunction &getMachineFunction() const { return MF; }
  const TargetMachine &getTarget() const;
  TargetLowering &getTargetLoweringInfo() const { return TLI; }

  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
  ///
  void viewGraph();


  typedef std::vector<SDNode*>::const_iterator allnodes_iterator;
  allnodes_iterator allnodes_begin() const { return AllNodes.begin(); }
  allnodes_iterator allnodes_end() const { return AllNodes.end(); }

  /// getRoot - Return the root tag of the SelectionDAG.
  ///
  const SDOperand &getRoot() const { return Root; }

  /// getEntryNode - Return the token chain corresponding to the entry of the
  /// function.
  const SDOperand &getEntryNode() const { return EntryNode; }

  /// setRoot - Set the current root tag of the SelectionDAG.
  ///
  const SDOperand &setRoot(SDOperand N) { return Root = N; }

  /// Combine - This iterates over the nodes in the SelectionDAG, folding
  /// certain types of nodes together, or eliminating superfluous nodes.  When
  /// the AfterLegalize argument is set to 'true', Combine takes care not to
  /// generate any nodes that will be illegal on the target.
  void Combine(bool AfterLegalize);
  
  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
  /// compatible with the target instruction selector, as indicated by the
  /// TargetLowering object.
  ///
  /// Note that this is an involved process that may invalidate pointers into
  /// the graph.
  void Legalize();

  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
  /// SelectionDAG, including nodes (like loads) that have uses of their token
  /// chain but no other uses and no side effect.  If a node is passed in as an
  /// argument, it is used as the seed for node deletion.
  void RemoveDeadNodes(SDNode *N = 0);

  SDOperand getConstant(uint64_t Val, MVT::ValueType VT);
  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT);
  SDOperand getConstantFP(double Val, MVT::ValueType VT);
  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT);
  SDOperand getConstantPool(Constant *C, MVT::ValueType VT);
  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT);
  SDOperand getBasicBlock(MachineBasicBlock *MBB);
  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
  SDOperand getValueType(MVT::ValueType);
  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);

  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
    return getNode(ISD::CopyToReg, MVT::Other, Chain,
                   getRegister(Reg, N.getValueType()), N);
  }

  // This version of the getCopyToReg method takes an extra operand, which
  // indicates that there is potentially an incoming flag value (if Flag is not
  // null) and that there should be a flag result.
  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
                         SDOperand Flag) {
    std::vector<MVT::ValueType> VTs;
    VTs.push_back(MVT::Other);
    VTs.push_back(MVT::Flag);
    std::vector<SDOperand> Ops;
    Ops.push_back(Chain);
    Ops.push_back(getRegister(Reg, N.getValueType()));
    Ops.push_back(N);
    if (Flag.Val) Ops.push_back(Flag);
    return getNode(ISD::CopyToReg, VTs, Ops);
  }
  
  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
    std::vector<MVT::ValueType> ResultTys;
    ResultTys.push_back(VT);
    ResultTys.push_back(MVT::Other);
    std::vector<SDOperand> Ops;
    Ops.push_back(Chain);
    Ops.push_back(getRegister(Reg, VT));
    return getNode(ISD::CopyFromReg, ResultTys, Ops);
  }
  
  // This version of the getCopyFromReg method takes an extra operand, which
  // indicates that there is potentially an incoming flag value (if Flag is not
  // null) and that there should be a flag result.
  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
                           SDOperand Flag) {
    std::vector<MVT::ValueType> ResultTys;
    ResultTys.push_back(VT);
    ResultTys.push_back(MVT::Other);
    ResultTys.push_back(MVT::Flag);
    std::vector<SDOperand> Ops;
    Ops.push_back(Chain);
    Ops.push_back(getRegister(Reg, VT));
    if (Flag.Val) Ops.push_back(Flag);
    return getNode(ISD::CopyFromReg, ResultTys, Ops);
  }

  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
    return getNode(ISD::ImplicitDef, MVT::Other, Chain, getRegister(Reg, VT));
  }

  /// getCall - Note that this destroys the vector of RetVals passed in.
  ///
  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
                  SDOperand Callee, bool isTailCall = false) {
    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
                            Callee);
    NN->setValueTypes(RetVals);
    AllNodes.push_back(NN);
    return NN;
  }

  /// getCall - This is identical to the one above, and should be used for calls
  /// where arguments are passed in physical registers.  This destroys the
  /// RetVals and ArgsInRegs vectors.
  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
                  bool isTailCall = false) {
    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
    NN->setValueTypes(RetVals);
    AllNodes.push_back(NN);
    return NN;
  }

  SDOperand getCondCode(ISD::CondCode Cond);

  /// getZeroExtendInReg - Return the expression required to zero extend the Op
  /// value assuming it was the smaller SrcTy value.
  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);

  /// getNode - Gets or creates the specified node.
  ///
  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
                    SDOperand N1, SDOperand N2);
  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
                    SDOperand N1, SDOperand N2, SDOperand N3);
  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
  SDOperand getNode(unsigned Opcode,