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/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.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 VISIBILITY_HIDDEN DAGTypeLegalizer {
  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 that was created in the process of
    /// legalizing some other node.
    NewNode = -1,

    /// Processed - This is a node that has already been processed.
    Processed = -2

    // 1+ - This is a node which has this many unlegalized operands.
  };
private:
  enum LegalizeAction {
    Legal,           // The target natively supports this type.
    PromoteInteger,  // Replace this integer type with a larger one.
    ExpandInteger,   // Split this integer type into two of half the size.
    SoftenFloat,     // Convert this float type to a same size integer type.
    ExpandFloat,     // Split this float type into two of half the size.
    ScalarizeVector, // Replace this one-element vector with its element type.
    SplitVector      // This vector type should be split into smaller vectors.
  };

  /// 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, either
  /// it is already legal, or we need to promote it to a larger integer type, or
  /// we need to expand it into multiple registers of a smaller integer type, or
  /// we need to split a vector type into smaller vector types, or we need to
  /// convert it to a different type of the same size.
  LegalizeAction getTypeAction(MVT VT) const {
    switch (ValueTypeActions.getTypeAction(VT)) {
    default:
      assert(false && "Unknown legalize action!");
    case TargetLowering::Legal:
      return Legal;
    case TargetLowering::Promote:
      return PromoteInteger;
    case TargetLowering::Expand:
      // Expand can mean
      // 1) split scalar in half, 2) convert a float to an integer,
      // 3) scalarize a single-element vector, 4) split a vector in two.
      if (!VT.isVector()) {
        if (VT.isInteger())
          return ExpandInteger;
        else if (VT.getSizeInBits() ==
                 TLI.getTypeToTransformTo(VT).getSizeInBits())
          return SoftenFloat;
        else
          return ExpandFloat;
      } else if (VT.getVectorNumElements() == 1) {
        return ScalarizeVector;
      } else {
        return SplitVector;
      }
    }
  }

  /// isTypeLegal - Return true if this type is legal on this target.
  bool isTypeLegal(MVT VT) const {
    return ValueTypeActions.getTypeAction(VT) == TargetLowering::Legal;
  }

  /// 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.
  DenseMap<SDValue, SDValue> PromotedIntegers;

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

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

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

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

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

  /// ReplacedNodes - For nodes that have been replaced with another,
  /// indicates the replacement node to use.
  DenseMap<SDValue, SDValue> ReplacedNodes;

  /// 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 <= 32 &&
           "Too many value types for ValueTypeActions to hold!");
  }

  void run();

  /// ReanalyzeNode - Recompute the NodeID and correct processed operands
  /// for the specified node, adding it to the worklist if ready.
  void ReanalyzeNode(SDNode *N) {
    N->setNodeId(NewNode);
    AnalyzeNewNode(N);
  }

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

private:
  void AnalyzeNewNode(SDNode *&N);

  void ReplaceValueWith(SDValue From, SDValue To);
  void ReplaceNodeWith(SDNode *From, SDNode *To);

  void RemapNode(SDValue &N);
  void ExpungeNode(SDNode *N);

  // Common routines.
  SDValue CreateStackStoreLoad(SDValue Op, MVT DestVT);
  SDValue MakeLibCall(RTLIB::Libcall LC, MVT RetVT,
                        const SDValue *Ops, unsigned NumOps, bool isSigned);

  SDValue BitConvertToInteger(SDValue Op);
  SDValue JoinIntegers(SDValue Lo, SDValue Hi);
  void SplitInteger(SDValue Op, SDValue &Lo, SDValue &Hi);
  void SplitInteger(SDValue Op, MVT LoVT, MVT HiVT,
                    SDValue &Lo, SDValue &Hi);

  SDValue GetVectorElementPointer(SDValue VecPtr, MVT EltVT,
                                    SDValue Index);

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

  SDValue GetPromotedInteger(SDValue Op) {
    SDValue &PromotedOp = PromotedIntegers[Op];
    RemapNode(PromotedOp);
    assert(PromotedOp.Val && "Operand wasn't promoted?");
    return PromotedOp;
  }
  void SetPromotedInteger(SDValue Op, SDValue Result);

  /// ZExtPromotedInteger - Get a promoted operand and zero extend it to the
  /// final size.
  SDValue ZExtPromotedInteger(SDValue Op) {
    MVT OldVT = Op.getValueType();
    Op = GetPromotedInteger(Op);
    return DAG.getZeroExtendInReg(Op, OldVT);
  }

  // Integer Result Promotion.
  void PromoteIntegerResult(SDNode *N, unsigned ResNo);
  SDValue PromoteIntRes_AssertSext(SDNode *N);
  SDValue PromoteIntRes_AssertZext(SDNode *N);
  SDValue PromoteIntRes_BIT_CONVERT(SDNode *N);
  SDValue PromoteIntRes_BSWAP(SDNode *N);
  SDValue PromoteIntRes_BUILD_PAIR(SDNode *N);
  SDValue PromoteIntRes_Constant(SDNode *N);
  SDValue PromoteIntRes_CTLZ(SDNode *N);
  SDValue PromoteIntRes_CTPOP(SDNode *N);
  SDValue PromoteIntRes_CTTZ(SDNode *N);
  SDValue PromoteIntRes_EXTRACT_VECTOR_ELT(SDNode *N);
  SDValue PromoteIntRes_FP_TO_XINT(SDNode *N);
  SDValue PromoteIntRes_INT_EXTEND(SDNode *N);
  SDValue PromoteIntRes_LOAD(LoadSDNode *N);
  SDValue PromoteIntRes_SDIV(SDNode *N);
  SDValue PromoteIntRes_SELECT   (SDNode *N);
  SDValue PromoteIntRes_SELECT_CC(SDNode *N);
  SDValue PromoteIntRes_SETCC