path: root/lib/CodeGen/SelectionDAG/LegalizeTypes.h

//===-- LegalizeTypes.h - Definition of the DAG Type Legalizer class ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the DAGTypeLegalizer class.  This is a private interface
// shared between the code that implements the SelectionDAG::LegalizeTypes
// method.
//
//===----------------------------------------------------------------------===//

#ifndef SELECTIONDAG_LEGALIZETYPES_H
#define SELECTIONDAG_LEGALIZETYPES_H

#define DEBUG_TYPE "legalize-types"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetLowering.h"

namespace llvm {

//===----------------------------------------------------------------------===//
/// DAGTypeLegalizer - This takes an arbitrary SelectionDAG as input and hacks
/// on it until only value types the target machine can handle are left.  This
/// involves promoting small sizes to large sizes or splitting up large values
/// into small values.
///
class LLVM_LIBRARY_VISIBILITY DAGTypeLegalizer {
  const TargetLowering &TLI;
  SelectionDAG &DAG;
public:
  // NodeIdFlags - This pass uses the NodeId on the SDNodes to hold information
  // about the state of the node.  The enum has all the values.
  enum NodeIdFlags {
    /// ReadyToProcess - All operands have been processed, so this node is ready
    /// to be handled.
    ReadyToProcess = 0,

    /// NewNode - This is a new node, not before seen, that was created in the
    /// process of legalizing some other node.
    NewNode = -1,

    /// Unanalyzed - This node's ID needs to be set to the number of its
    /// unprocessed operands.
    Unanalyzed = -2,

    /// Processed - This is a node that has already been processed.
    Processed = -3

    // 1+ - This is a node which has this many unprocessed operands.
  };
private:

  /// ValueTypeActions - This is a bitvector that contains two bits for each
  /// simple value type, where the two bits correspond to the LegalizeAction
  /// enum from TargetLowering.  This can be queried with "getTypeAction(VT)".
  TargetLowering::ValueTypeActionImpl ValueTypeActions;

  /// getTypeAction - Return how we should legalize values of this type.
  TargetLowering::LegalizeTypeAction getTypeAction(EVT VT) const {
    return TLI.getTypeAction(*DAG.getContext(), VT);
  }

  /// isTypeLegal - Return true if this type is legal on this target.
  bool isTypeLegal(EVT VT) const {
    return TLI.getTypeAction(*DAG.getContext(), VT) == TargetLowering::TypeLegal;
  }

  /// IgnoreNodeResults - Pretend all of this node's results are legal.
  bool IgnoreNodeResults(SDNode *N) const {
    return N->getOpcode() == ISD::TargetConstant;
  }

  /// PromotedIntegers - For integer nodes that are below legal width, this map
  /// indicates what promoted value to use.
  SmallDenseMap<SDValue, SDValue, 8> PromotedIntegers;

  /// ExpandedIntegers - For integer nodes that need to be expanded this map
  /// indicates which operands are the expanded version of the input.
  SmallDenseMap<SDValue, std::pair<SDValue, SDValue>, 8> ExpandedIntegers;

  /// SoftenedFloats - For floating point nodes converted to integers of
  /// the same size, this map indicates the converted value to use.
  SmallDenseMap<SDValue, SDValue, 8> SoftenedFloats;

  /// ExpandedFloats - For float nodes that need to be expanded this map
  /// indicates which operands are the expanded version of the input.
  SmallDenseMap<SDValue, std::pair<SDValue, SDValue>, 8> ExpandedFloats;

  /// ScalarizedVectors - For nodes that are <1 x ty>, this map indicates the
  /// scalar value of type 'ty' to use.
  SmallDenseMap<SDValue, SDValue, 8> ScalarizedVectors;

  /// SplitVectors - For nodes that need to be split this map indicates
  /// which operands are the expanded version of the input.
  SmallDenseMap<SDValue, std::pair<SDValue, SDValue>, 8> SplitVectors;

  /// WidenedVectors - For vector nodes that need to be widened, indicates
  /// the widened value to use.
  SmallDenseMap<SDValue, SDValue, 8> WidenedVectors;

  /// ReplacedValues - For values that have been replaced with another,
  /// indicates the replacement value to use.
  SmallDenseMap<SDValue, SDValue, 8> ReplacedValues;

  /// Worklist - This defines a worklist of nodes to process.  In order to be
  /// pushed onto this worklist, all operands of a node must have already been
  /// processed.
  SmallVector<SDNode*, 128> Worklist;

public:
  explicit DAGTypeLegalizer(SelectionDAG &dag)
    : TLI(dag.getTargetLoweringInfo()), DAG(dag),
    ValueTypeActions(TLI.getValueTypeActions()) {
    assert(MVT::LAST_VALUETYPE <= MVT::MAX_ALLOWED_VALUETYPE &&
           "Too many value types for ValueTypeActions to hold!");
  }

  /// run - This is the main entry point for the type legalizer.  This does a
  /// top-down traversal of the dag, legalizing types as it goes.  Returns
  /// "true" if it made any changes.
  bool run();

  void NoteDeletion(SDNode *Old, SDNode *New) {
    ExpungeNode(Old);
    ExpungeNode(New);
    for (unsigned i = 0, e = Old->getNumValues(); i != e; ++i)
      ReplacedValues[SDValue(Old, i)] = SDValue(New, i);
  }

  SelectionDAG &getDAG() const { return DAG; }

private:
  SDNode *AnalyzeNewNode(SDNode *N);
  void AnalyzeNewValue(SDValue &Val);
  void ExpungeNode(SDNode *N);
  void PerformExpensiveChecks();
  void RemapValue(SDValue &N);

  // Common routines.
  SDValue BitConvertToInteger(SDValue Op);
  SDValue BitConvertVectorToIntegerVector(SDValue Op);
  SDValue CreateStackStoreLoad(SDValue Op, EVT DestVT);
  bool CustomLowerNode(SDNode *N, EVT VT, bool LegalizeResult);
  bool CustomWidenLowerNode(SDNode *N, EVT VT);

  /// DisintegrateMERGE_VALUES - Replace each result of the given MERGE_VALUES
  /// node with the corresponding input operand, except for the result 'ResNo',
  /// for which the corresponding input operand is returned.
  SDValue DisintegrateMERGE_VALUES(SDNode *N, unsigned ResNo);

  SDValue GetVectorElementPointer(SDValue VecPtr, EVT EltVT, SDValue Index);
  SDValue JoinIntegers(SDValue Lo, SDValue Hi);
  SDValue LibCallify(RTLIB::Libcall LC, SDNode *N, bool isSigned);
  
  std::pair<SDValue, SDValue> ExpandChainLibCall(RTLIB::Libcall LC,
                                                 SDNode *Node, bool isSigned);
  std::pair<SDValue, SDValue> ExpandAtomic(SDNode *Node);

  SDValue PromoteTargetBoolean(SDValue Bool, EVT VT);
  void ReplaceValueWith(SDValue From, SDValue To);
  void SplitInteger(SDValue Op, SDValue &Lo, SDValue &Hi);
  void SplitInteger(SDValue Op, EVT LoVT, EVT HiVT,
                    SDValue &Lo, SDValue &Hi);

  //===--------------------------------------------------------------------===//
  // Integer Promotion Support: LegalizeIntegerTypes.cpp
  //===--------------------------------------------------------------------===//

  /// GetPromotedInteger - Given a processed operand Op which was promoted to a
  /// larger integer type, this returns the promoted value.  The low bits of the
  /// promoted value corresponding to the original type are exactly equal to Op.
  /// The extra bits contain rubbish, so the promoted value may need to be zero-
  /// or sign-extended from the original type before it is usable (the helpers
  /// SExtPromotedInteger and ZExtPromotedInteger can do this for you).
  /// For example, if Op is an i16 and was promoted to an i32, then this method
  /// returns an i32, the lower 16 bits of which coincide with Op, and the upper
  /// 16 bits of which contain rubbish.
  SDValue GetPromotedInteger(SDValue Op) {
    SDValue &PromotedOp = PromotedIntegers[Op];
    RemapValue(PromotedOp);
    assert(PromotedOp.getNode() && "Operand wasn't promoted?");
    return PromotedOp;
  }
  void SetPromotedInteger(SDValue Op, SDValue Res