xref: /llvm-project-15.0.7/llvm/utils/TableGen/RegisterInfoEmitter.cpp (revision 21dfcd9d)

//===- RegisterInfoEmitter.cpp - Generate a Register File Desc. -*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend is responsible for emitting a description of a target
// register file for a code generator.  It uses instances of the Register,
// RegisterAliases, and RegisterClass classes to gather this information.
//
//===----------------------------------------------------------------------===//

#include "CodeGenRegisters.h"
#include "CodeGenTarget.h"
#include "SequenceToOffsetTable.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Format.h"
#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <algorithm>
#include <set>
#include <vector>
using namespace llvm;

namespace {
class RegisterInfoEmitter {
  RecordKeeper &Records;
public:
  RegisterInfoEmitter(RecordKeeper &R) : Records(R) {}

  // runEnums - Print out enum values for all of the registers.
  void runEnums(raw_ostream &o, CodeGenTarget &Target, CodeGenRegBank &Bank);

  // runMCDesc - Print out MC register descriptions.
  void runMCDesc(raw_ostream &o, CodeGenTarget &Target, CodeGenRegBank &Bank);

  // runTargetHeader - Emit a header fragment for the register info emitter.
  void runTargetHeader(raw_ostream &o, CodeGenTarget &Target,
                       CodeGenRegBank &Bank);

  // runTargetDesc - Output the target register and register file descriptions.
  void runTargetDesc(raw_ostream &o, CodeGenTarget &Target,
                     CodeGenRegBank &Bank);

  // run - Output the register file description.
  void run(raw_ostream &o);

private:
  void EmitRegMapping(raw_ostream &o,
                      const std::vector<CodeGenRegister*> &Regs, bool isCtor);
  void EmitRegMappingTables(raw_ostream &o,
                            const std::vector<CodeGenRegister*> &Regs,
                            bool isCtor);
  void EmitRegClasses(raw_ostream &OS, CodeGenTarget &Target);

  void EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
                           const std::string &ClassName);
};
} // End anonymous namespace

// runEnums - Print out enum values for all of the registers.
void RegisterInfoEmitter::runEnums(raw_ostream &OS,
                                   CodeGenTarget &Target, CodeGenRegBank &Bank) {
  const std::vector<CodeGenRegister*> &Registers = Bank.getRegisters();

  // Register enums are stored as uint16_t in the tables. Make sure we'll fit.
  assert(Registers.size() <= 0xffff && "Too many regs to fit in tables");

  std::string Namespace = Registers[0]->TheDef->getValueAsString("Namespace");

  emitSourceFileHeader("Target Register Enum Values", OS);

  OS << "\n#ifdef GET_REGINFO_ENUM\n";
  OS << "#undef GET_REGINFO_ENUM\n";

  OS << "namespace llvm {\n\n";

  OS << "class MCRegisterClass;\n"
     << "extern const MCRegisterClass " << Namespace
     << "MCRegisterClasses[];\n\n";

  if (!Namespace.empty())
    OS << "namespace " << Namespace << " {\n";
  OS << "enum {\n  NoRegister,\n";

  for (unsigned i = 0, e = Registers.size(); i != e; ++i)
    OS << "  " << Registers[i]->getName() << " = " <<
      Registers[i]->EnumValue << ",\n";
  assert(Registers.size() == Registers[Registers.size()-1]->EnumValue &&
         "Register enum value mismatch!");
  OS << "  NUM_TARGET_REGS \t// " << Registers.size()+1 << "\n";
  OS << "};\n";
  if (!Namespace.empty())
    OS << "}\n";

  ArrayRef<CodeGenRegisterClass*> RegisterClasses = Bank.getRegClasses();
  if (!RegisterClasses.empty()) {

    // RegisterClass enums are stored as uint16_t in the tables.
    assert(RegisterClasses.size() <= 0xffff &&
           "Too many register classes to fit in tables");

    OS << "\n// Register classes\n";
    if (!Namespace.empty())
      OS << "namespace " << Namespace << " {\n";
    OS << "enum {\n";
    for (unsigned i = 0, e = RegisterClasses.size(); i != e; ++i) {
      if (i) OS << ",\n";
      OS << "  " << RegisterClasses[i]->getName() << "RegClassID";
      OS << " = " << i;
    }
    OS << "\n  };\n";
    if (!Namespace.empty())
      OS << "}\n";
  }

  const std::vector<Record*> RegAltNameIndices = Target.getRegAltNameIndices();
  // If the only definition is the default NoRegAltName, we don't need to
  // emit anything.
  if (RegAltNameIndices.size() > 1) {
    OS << "\n// Register alternate name indices\n";
    if (!Namespace.empty())
      OS << "namespace " << Namespace << " {\n";
    OS << "enum {\n";
    for (unsigned i = 0, e = RegAltNameIndices.size(); i != e; ++i)
      OS << "  " << RegAltNameIndices[i]->getName() << ",\t// " << i << "\n";
    OS << "  NUM_TARGET_REG_ALT_NAMES = " << RegAltNameIndices.size() << "\n";
    OS << "};\n";
    if (!Namespace.empty())
      OS << "}\n";
  }

  ArrayRef<CodeGenSubRegIndex*> SubRegIndices = Bank.getSubRegIndices();
  if (!SubRegIndices.empty()) {
    OS << "\n// Subregister indices\n";
    std::string Namespace =
      SubRegIndices[0]->getNamespace();
    if (!Namespace.empty())
      OS << "namespace " << Namespace << " {\n";
    OS << "enum {\n  NoSubRegister,\n";
    for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i)
      OS << "  " << SubRegIndices[i]->getName() << ",\t// " << i+1 << "\n";
    OS << "  NUM_TARGET_SUBREGS\n};\n";
    if (!Namespace.empty())
      OS << "}\n";
  }

  OS << "} // End llvm namespace \n";
  OS << "#endif // GET_REGINFO_ENUM\n\n";
}

void RegisterInfoEmitter::
EmitRegUnitPressure(raw_ostream &OS, const CodeGenRegBank &RegBank,
                    const std::string &ClassName) {
  unsigned NumRCs = RegBank.getRegClasses().size();
  unsigned NumSets = RegBank.getNumRegPressureSets();

  OS << "/// Get the weight in units of pressure for this register class.\n"
     << "const RegClassWeight &" << ClassName << "::\n"
     << "getRegClassWeight(const TargetRegisterClass *RC) const {\n"
     << "  static const RegClassWeight RCWeightTable[] = {\n";
  for (unsigned i = 0, e = NumRCs; i != e; ++i) {
    const CodeGenRegisterClass &RC = *RegBank.getRegClasses()[i];
    const CodeGenRegister::Set &Regs = RC.getMembers();
    if (Regs.empty())
      OS << "    {0, 0";
    else {
      std::vector<unsigned> RegUnits;
      RC.buildRegUnitSet(RegUnits);
      OS << "    {" << (*Regs.begin())->getWeight(RegBank)
         << ", " << RegBank.getRegUnitSetWeight(RegUnits);
    }
    OS << "},  \t// " << RC.getName() << "\n";
  }
  OS << "    {0, 0} };\n"
     << "  return RCWeightTable[RC->getID()];\n"
     << "}\n\n";

  OS << "\n"
     << "// Get the number of dimensions of register pressure.\n"
     << "unsigned " << ClassName << "::getNumRegPressureSets() const {\n"
     << "  return " << NumSets << ";\n}\n\n";

  OS << "// Get the name of this register unit pressure set.\n"
     << "const char *" << ClassName << "::\n"
     << "getRegPressureSetName(unsigned Idx) const {\n"
     << "  static const char *PressureNameTable[] = {\n";
  for (unsigned i = 0; i < NumSets; ++i ) {
    OS << "    \"" << RegBank.getRegPressureSet(i).Name << "\",\n";
  }
  OS << "    0 };\n"
     << "  return PressureNameTable[Idx];\n"
     << "}\n\n";

  OS << "// Get the register unit pressure limit for this dimension.\n"
     << "// This limit must be adjusted dynamically for reserved registers.\n"
     << "unsigned " << ClassName << "::\n"
     << "getRegPressureSetLimit(unsigned Idx) const {\n"
     << "  static const unsigned PressureLimitTable[] = {\n";
  for (unsigned i = 0; i < NumSets; ++i ) {
    const RegUnitSet &RegUnits = RegBank.getRegPressureSet(i);
    OS << "    " << RegBank.getRegUnitSetWeight(RegUnits.Units)
       << ",  \t// " << i << ": " << RegUnits.Name << "\n";
  }
  OS << "    0 };\n"
     << "  return PressureLimitTable[Idx];\n"
     << "}\n\n";

  OS << "/// Get the dimensions of register pressure "
     << "impacted by this register class.\n"
     << "/// Returns a -1 terminated array of pressure set IDs\n"
     << "const int* " << ClassName << "::\n"
     << "getRegClassPressureSets(const TargetRegisterClass *RC) const {\n"
     << "  static const int RCSetsTable[] = {\n    ";
  std::vector<unsigned> RCSetStarts(NumRCs);
  for (unsigned i = 0, StartIdx = 0, e = NumRCs; i != e; ++i) {
    RCSetStarts[i] = StartIdx;
    ArrayRef<unsigned> PSetIDs = RegBank.getRCPressureSetIDs(i);
    for (ArrayRef<unsigned>::iterator PSetI = PSetIDs.begin(),
           PSetE = PSetIDs.end(); PSetI != PSetE; ++PSetI) {
      OS << *PSetI << ",  ";
      ++StartIdx;
    }
    OS << "-1,  \t// " << RegBank.getRegClasses()[i]->getName() << "\n    ";
    ++StartIdx;
  }
  OS << "-1 };\n";
  OS << "  static const unsigned RCSetStartTable[] = {\n    ";
  for (unsigned i = 0, e = NumRCs; i != e; ++i) {
    OS << RCSetStarts[i] << ",";
  }
  OS << "0 };\n"
     << "  unsigned SetListStart = RCSetStartTable[RC->getID()];\n"
     << "  return &RCSetsTable[SetListStart];\n"
     << "}\n\n";
}

void
RegisterInfoEmitter::EmitRegMappingTables(raw_ostream &OS,
                                       const std::vector<CodeGenRegister*> &Regs,
                                          bool isCtor) {
  // Collect all information about dwarf register numbers
  typedef std::map<Record*, std::vector<int64_t>, LessRecord> DwarfRegNumsMapTy;
  DwarfRegNumsMapTy DwarfRegNums;

  // First, just pull all provided information to the map
  unsigned maxLength = 0;
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    Record *Reg = Regs[i]->TheDef;
    std::vector<int64_t> RegNums = Reg->getValueAsListOfInts("DwarfNumbers");
    maxLength = std::max((size_t)maxLength, RegNums.size());
    if (DwarfRegNums.count(Reg))
      PrintWarning(Reg->getLoc(), Twine("DWARF numbers for register ") +
                   getQualifiedName(Reg) + "specified multiple times");
    DwarfRegNums[Reg] = RegNums;
  }

  if (!maxLength)
    return;

  // Now we know maximal length of number list. Append -1's, where needed
  for (DwarfRegNumsMapTy::iterator
       I = DwarfRegNums.begin(), E = DwarfRegNums.end(); I != E; ++I)
    for (unsigned i = I->second.size(), e = maxLength; i != e; ++i)
      I->second.push_back(-1);

  std::string Namespace = Regs[0]->TheDef->getValueAsString("Namespace");

  OS << "// " << Namespace << " Dwarf<->LLVM register mappings.\n";

  // Emit reverse information about the dwarf register numbers.
  for (unsigned j = 0; j < 2; ++j) {
    for (unsigned i = 0, e = maxLength; i != e; ++i) {
      OS << "extern const MCRegisterInfo::DwarfLLVMRegPair " << Namespace;
      OS << (j == 0 ? "DwarfFlavour" : "EHFlavour");
      OS << i << "Dwarf2L[]";

      if (!isCtor) {
        OS << " = {\n";

        // Store the mapping sorted by the LLVM reg num so lookup can be done
        // with a binary search.
        std::map<uint64_t, Record*> Dwarf2LMap;
        for (DwarfRegNumsMapTy::iterator
               I = DwarfRegNums.begin(), E = DwarfRegNums.end(); I != E; ++I) {
          int DwarfRegNo = I->second[i];
          if (DwarfRegNo < 0)
            continue;
          Dwarf2LMap[DwarfRegNo] = I->first;
        }

        for (std::map<uint64_t, Record*>::iterator
               I = Dwarf2LMap.begin(), E = Dwarf2LMap.end(); I != E; ++I)
          OS << "  { " << I->first << "U, " << getQualifiedName(I->second)
             << " },\n";

        OS << "};\n";
      } else {
        OS << ";\n";
      }

      // We have to store the size in a const global, it's used in multiple
      // places.
      OS << "extern const unsigned " << Namespace
         << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i << "Dwarf2LSize";
      if (!isCtor)
        OS << " = sizeof(" << Namespace
           << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i
           << "Dwarf2L)/sizeof(MCRegisterInfo::DwarfLLVMRegPair);\n\n";
      else
        OS << ";\n\n";
    }
  }

  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    Record *Reg = Regs[i]->TheDef;
    const RecordVal *V = Reg->getValue("DwarfAlias");
    if (!V || !V->getValue())
      continue;

    DefInit *DI = dynamic_cast<DefInit*>(V->getValue());
    Record *Alias = DI->getDef();
    DwarfRegNums[Reg] = DwarfRegNums[Alias];
  }

  // Emit information about the dwarf register numbers.
  for (unsigned j = 0; j < 2; ++j) {
    for (unsigned i = 0, e = maxLength; i != e; ++i) {
      OS << "extern const MCRegisterInfo::DwarfLLVMRegPair " << Namespace;
      OS << (j == 0 ? "DwarfFlavour" : "EHFlavour");
      OS << i << "L2Dwarf[]";
      if (!isCtor) {
        OS << " = {\n";
        // Store the mapping sorted by the Dwarf reg num so lookup can be done
        // with a binary search.
        for (DwarfRegNumsMapTy::iterator
               I = DwarfRegNums.begin(), E = DwarfRegNums.end(); I != E; ++I) {
          int RegNo = I->second[i];
          if (RegNo == -1) // -1 is the default value, don't emit a mapping.
            continue;

          OS << "  { " << getQualifiedName(I->first) << ", " << RegNo
             << "U },\n";
        }
        OS << "};\n";
      } else {
        OS << ";\n";
      }

      // We have to store the size in a const global, it's used in multiple
      // places.
      OS << "extern const unsigned " << Namespace
         << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i << "L2DwarfSize";
      if (!isCtor)
        OS << " = sizeof(" << Namespace
           << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i
           << "L2Dwarf)/sizeof(MCRegisterInfo::DwarfLLVMRegPair);\n\n";
      else
        OS << ";\n\n";
    }
  }
}

void
RegisterInfoEmitter::EmitRegMapping(raw_ostream &OS,
                                    const std::vector<CodeGenRegister*> &Regs,
                                    bool isCtor) {
  // Emit the initializer so the tables from EmitRegMappingTables get wired up
  // to the MCRegisterInfo object.
  unsigned maxLength = 0;
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    Record *Reg = Regs[i]->TheDef;
    maxLength = std::max((size_t)maxLength,
                         Reg->getValueAsListOfInts("DwarfNumbers").size());
  }

  if (!maxLength)
    return;

  std::string Namespace = Regs[0]->TheDef->getValueAsString("Namespace");

  // Emit reverse information about the dwarf register numbers.
  for (unsigned j = 0; j < 2; ++j) {
    OS << "  switch (";
    if (j == 0)
      OS << "DwarfFlavour";
    else
      OS << "EHFlavour";
    OS << ") {\n"
     << "  default:\n"
     << "    llvm_unreachable(\"Unknown DWARF flavour\");\n";

    for (unsigned i = 0, e = maxLength; i != e; ++i) {
      OS << "  case " << i << ":\n";
      OS << "    ";
      if (!isCtor)
        OS << "RI->";
      std::string Tmp;
      raw_string_ostream(Tmp) << Namespace
                              << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i
                              << "Dwarf2L";
      OS << "mapDwarfRegsToLLVMRegs(" << Tmp << ", " << Tmp << "Size, ";
      if (j == 0)
          OS << "false";
        else
          OS << "true";
      OS << ");\n";
      OS << "    break;\n";
    }
    OS << "  }\n";
  }

  // Emit information about the dwarf register numbers.
  for (unsigned j = 0; j < 2; ++j) {
    OS << "  switch (";
    if (j == 0)
      OS << "DwarfFlavour";
    else
      OS << "EHFlavour";
    OS << ") {\n"
       << "  default:\n"
       << "    llvm_unreachable(\"Unknown DWARF flavour\");\n";

    for (unsigned i = 0, e = maxLength; i != e; ++i) {
      OS << "  case " << i << ":\n";
      OS << "    ";
      if (!isCtor)
        OS << "RI->";
      std::string Tmp;
      raw_string_ostream(Tmp) << Namespace
                              << (j == 0 ? "DwarfFlavour" : "EHFlavour") << i
                              << "L2Dwarf";
      OS << "mapLLVMRegsToDwarfRegs(" << Tmp << ", " << Tmp << "Size, ";
      if (j == 0)
          OS << "false";
        else
          OS << "true";
      OS << ");\n";
      OS << "    break;\n";
    }
    OS << "  }\n";
  }
}

// Print a BitVector as a sequence of hex numbers using a little-endian mapping.
// Width is the number of bits per hex number.
static void printBitVectorAsHex(raw_ostream &OS,
                                const BitVector &Bits,
                                unsigned Width) {
  assert(Width <= 32 && "Width too large");
  unsigned Digits = (Width + 3) / 4;
  for (unsigned i = 0, e = Bits.size(); i < e; i += Width) {
    unsigned Value = 0;
    for (unsigned j = 0; j != Width && i + j != e; ++j)
      Value |= Bits.test(i + j) << j;
    OS << format("0x%0*x, ", Digits, Value);
  }
}

// Helper to emit a set of bits into a constant byte array.
class BitVectorEmitter {
  BitVector Values;
public:
  void add(unsigned v) {
    if (v >= Values.size())
      Values.resize(((v/8)+1)*8); // Round up to the next byte.
    Values[v] = true;
  }

  void print(raw_ostream &OS) {
    printBitVectorAsHex(OS, Values, 8);
  }
};

static void printSimpleValueType(raw_ostream &OS, MVT::SimpleValueType VT) {
  OS << getEnumName(VT);
}

static void printSubRegIndex(raw_ostream &OS, const CodeGenSubRegIndex *Idx) {
  OS << Idx->EnumValue;
}

// Differentially encoded register and regunit lists allow for better
// compression on regular register banks. The sequence is computed from the
// differential list as:
//
//   out[0] = InitVal;
//   out[n+1] = out[n] + diff[n]; // n = 0, 1, ...
//
// The initial value depends on the specific list. The list is terminated by a
// 0 differential which means we can't encode repeated elements.

typedef SmallVector<uint16_t, 4> DiffVec;

// Differentially encode a sequence of numbers into V. The starting value and
// terminating 0 are not added to V, so it will have the same size as List.
static
DiffVec &diffEncode(DiffVec &V, unsigned InitVal, ArrayRef<unsigned> List) {
  assert(V.empty() && "Clear DiffVec before diffEncode.");
  uint16_t Val = uint16_t(InitVal);
  for (unsigned i = 0; i != List.size(); ++i) {
    uint16_t Cur = List[i];
    V.push_back(Cur - Val);
    Val = Cur;
  }
  return V;
}

template<typename Iter>
static
DiffVec &diffEncode(DiffVec &V, unsigned InitVal, Iter Begin, Iter End) {
  assert(V.empty() && "Clear DiffVec before diffEncode.");
  uint16_t Val = uint16_t(InitVal);
  for (Iter I = Begin; I != End; ++I) {
    uint16_t Cur = (*I)->EnumValue;
    V.push_back(Cur - Val);
    Val = Cur;
  }
  return V;
}

static void printDiff16(raw_ostream &OS, uint16_t Val) {
  OS << Val;
}

//
// runMCDesc - Print out MC register descriptions.
//
void
RegisterInfoEmitter::runMCDesc(raw_ostream &OS, CodeGenTarget &Target,
                               CodeGenRegBank &RegBank) {
  emitSourceFileHeader("MC Register Information", OS);

  OS << "\n#ifdef GET_REGINFO_MC_DESC\n";
  OS << "#undef GET_REGINFO_MC_DESC\n";

  const std::vector<CodeGenRegister*> &Regs = RegBank.getRegisters();

  // The lists of sub-registers, super-registers, and overlaps all go in the
  // same array. That allows us to share suffixes.
  typedef std::vector<const CodeGenRegister*> RegVec;

  // Differentially encoded lists.
  SequenceToOffsetTable<DiffVec> DiffSeqs;
  SmallVector<DiffVec, 4> SubRegLists(Regs.size());
  SmallVector<DiffVec, 4> SuperRegLists(Regs.size());
  SmallVector<DiffVec, 4> OverlapLists(Regs.size());
  SmallVector<DiffVec, 4> RegUnitLists(Regs.size());
  SmallVector<unsigned, 4> RegUnitInitScale(Regs.size());

  // Keep track of sub-register names as well. These are not differentially
  // encoded.
  typedef SmallVector<const CodeGenSubRegIndex*, 4> SubRegIdxVec;
  SequenceToOffsetTable<SubRegIdxVec> SubRegIdxSeqs;
  SmallVector<SubRegIdxVec, 4> SubRegIdxLists(Regs.size());

  SequenceToOffsetTable<std::string> RegStrings;

  // Precompute register lists for the SequenceToOffsetTable.
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    const CodeGenRegister *Reg = Regs[i];

    RegStrings.add(Reg->getName());

    // Compute the ordered sub-register list.
    SetVector<const CodeGenRegister*> SR;
    Reg->addSubRegsPreOrder(SR, RegBank);
    diffEncode(SubRegLists[i], Reg->EnumValue, SR.begin(), SR.end());
    DiffSeqs.add(SubRegLists[i]);

    // Compute the corresponding sub-register indexes.
    SubRegIdxVec &SRIs = SubRegIdxLists[i];
    for (unsigned j = 0, je = SR.size(); j != je; ++j)
      SRIs.push_back(Reg->getSubRegIndex(SR[j]));
    SubRegIdxSeqs.add(SRIs);

    // Super-registers are already computed.
    const RegVec &SuperRegList = Reg->getSuperRegs();
    diffEncode(SuperRegLists[i], Reg->EnumValue,
               SuperRegList.begin(), SuperRegList.end());
    DiffSeqs.add(SuperRegLists[i]);

    // The list of overlaps doesn't need to have any particular order, and Reg
    // itself must be omitted.
    DiffVec &OverlapList = OverlapLists[i];
    CodeGenRegister::Set OSet;
    Reg->computeOverlaps(OSet, RegBank);
    OSet.erase(Reg);
    diffEncode(OverlapList, Reg->EnumValue, OSet.begin(), OSet.end());
    DiffSeqs.add(OverlapList);

    // Differentially encode the register unit list, seeded by register number.
    // First compute a scale factor that allows more diff-lists to be reused:
    //
    //   D0 -> (S0, S1)
    //   D1 -> (S2, S3)
    //
    // A scale factor of 2 allows D0 and D1 to share a diff-list. The initial
    // value for the differential decoder is the register number multiplied by
    // the scale.
    //
    // Check the neighboring registers for arithmetic progressions.
    unsigned ScaleA = ~0u, ScaleB = ~0u;
    ArrayRef<unsigned> RUs = Reg->getNativeRegUnits();
    if (i > 0 && Regs[i-1]->getNativeRegUnits().size() == RUs.size())
      ScaleB = RUs.front() - Regs[i-1]->getNativeRegUnits().front();
    if (i+1 != Regs.size() &&
        Regs[i+1]->getNativeRegUnits().size() == RUs.size())
      ScaleA = Regs[i+1]->getNativeRegUnits().front() - RUs.front();
    unsigned Scale = std::min(ScaleB, ScaleA);
    // Default the scale to 0 if it can't be encoded in 4 bits.
    if (Scale >= 16)
      Scale = 0;
    RegUnitInitScale[i] = Scale;
    DiffSeqs.add(diffEncode(RegUnitLists[i], Scale * Reg->EnumValue, RUs));
  }

  // Compute the final layout of the sequence table.
  DiffSeqs.layout();
  SubRegIdxSeqs.layout();

  OS << "namespace llvm {\n\n";

  const std::string &TargetName = Target.getName();

  // Emit the shared table of differential lists.
  OS << "extern const uint16_t " << TargetName << "RegDiffLists[] = {\n";
  DiffSeqs.emit(OS, printDiff16);
  OS << "};\n\n";

  // Emit the table of sub-register indexes.
  OS << "extern const uint16_t " << TargetName << "SubRegIdxLists[] = {\n";
  SubRegIdxSeqs.emit(OS, printSubRegIndex);
  OS << "};\n\n";

  // Emit the string table.
  RegStrings.layout();
  OS << "extern const char " << TargetName << "RegStrings[] = {\n";
  RegStrings.emit(OS, printChar);
  OS << "};\n\n";

  OS << "extern const MCRegisterDesc " << TargetName
     << "RegDesc[] = { // Descriptors\n";
  OS << "  { " << RegStrings.get("") << ", 0, 0, 0, 0, 0 },\n";

  // Emit the register descriptors now.
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    const CodeGenRegister *Reg = Regs[i];
    OS << "  { " << RegStrings.get(Reg->getName()) << ", "
       << DiffSeqs.get(OverlapLists[i]) << ", "
       << DiffSeqs.get(SubRegLists[i]) << ", "
       << DiffSeqs.get(SuperRegLists[i]) << ", "
       << SubRegIdxSeqs.get(SubRegIdxLists[i]) << ", "
       << (DiffSeqs.get(RegUnitLists[i])*16 + RegUnitInitScale[i]) << " },\n";
  }
  OS << "};\n\n";      // End of register descriptors...

  // Emit the table of register unit roots. Each regunit has one or two root
  // registers.
  OS << "extern const uint16_t " << TargetName << "RegUnitRoots[][2] = {\n";
  for (unsigned i = 0, e = RegBank.getNumNativeRegUnits(); i != e; ++i) {
    ArrayRef<const CodeGenRegister*> Roots = RegBank.getRegUnit(i).getRoots();
    assert(!Roots.empty() && "All regunits must have a root register.");
    assert(Roots.size() <= 2 && "More than two roots not supported yet.");
    OS << "  { " << getQualifiedName(Roots.front()->TheDef);
    for (unsigned r = 1; r != Roots.size(); ++r)
      OS << ", " << getQualifiedName(Roots[r]->TheDef);
    OS << " },\n";
  }
  OS << "};\n\n";

  ArrayRef<CodeGenRegisterClass*> RegisterClasses = RegBank.getRegClasses();

  // Loop over all of the register classes... emitting each one.
  OS << "namespace {     // Register classes...\n";

  // Emit the register enum value arrays for each RegisterClass
  for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc) {
    const CodeGenRegisterClass &RC = *RegisterClasses[rc];
    ArrayRef<Record*> Order = RC.getOrder();

    // Give the register class a legal C name if it's anonymous.
    std::string Name = RC.getName();

    // Emit the register list now.
    OS << "  // " << Name << " Register Class...\n"
       << "  const uint16_t " << Name
       << "[] = {\n    ";
    for (unsigned i = 0, e = Order.size(); i != e; ++i) {
      Record *Reg = Order[i];
      OS << getQualifiedName(Reg) << ", ";
    }
    OS << "\n  };\n\n";

    OS << "  // " << Name << " Bit set.\n"
       << "  const uint8_t " << Name
       << "Bits[] = {\n    ";
    BitVectorEmitter BVE;
    for (unsigned i = 0, e = Order.size(); i != e; ++i) {
      Record *Reg = Order[i];
      BVE.add(Target.getRegBank().getReg(Reg)->EnumValue);
    }
    BVE.print(OS);
    OS << "\n  };\n\n";

  }
  OS << "}\n\n";

  OS << "extern const MCRegisterClass " << TargetName
     << "MCRegisterClasses[] = {\n";

  for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc) {
    const CodeGenRegisterClass &RC = *RegisterClasses[rc];

    // Asserts to make sure values will fit in table assuming types from
    // MCRegisterInfo.h
    assert((RC.SpillSize/8) <= 0xffff && "SpillSize too large.");
    assert((RC.SpillAlignment/8) <= 0xffff && "SpillAlignment too large.");
    assert(RC.CopyCost >= -128 && RC.CopyCost <= 127 && "Copy cost too large.");

    OS << "  { " << '\"' << RC.getName() << "\", "
       << RC.getName() << ", " << RC.getName() << "Bits, "
       << RC.getOrder().size() << ", sizeof(" << RC.getName() << "Bits), "
       << RC.getQualifiedName() + "RegClassID" << ", "
       << RC.SpillSize/8 << ", "
       << RC.SpillAlignment/8 << ", "
       << RC.CopyCost << ", "
       << RC.Allocatable << " },\n";
  }

  OS << "};\n\n";

  ArrayRef<CodeGenSubRegIndex*> SubRegIndices = RegBank.getSubRegIndices();

  EmitRegMappingTables(OS, Regs, false);

  // Emit Reg encoding table
  OS << "extern const uint16_t " << TargetName;
  OS << "RegEncodingTable[] = {\n";
  // Add entry for NoRegister
  OS << "  0,\n";
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    Record *Reg = Regs[i]->TheDef;
    BitsInit *BI = Reg->getValueAsBitsInit("HWEncoding");
    uint64_t Value = 0;
    for (unsigned b = 0, be = BI->getNumBits(); b != be; ++b) {
      if (BitInit *B = dynamic_cast<BitInit*>(BI->getBit(b)))
      Value |= (uint64_t)B->getValue() << b;
    }
    OS << "  " << Value << ",\n";
  }
  OS << "};\n";       // End of HW encoding table

  // MCRegisterInfo initialization routine.
  OS << "static inline void Init" << TargetName
     << "MCRegisterInfo(MCRegisterInfo *RI, unsigned RA, "
     << "unsigned DwarfFlavour = 0, unsigned EHFlavour = 0) {\n"
     << "  RI->InitMCRegisterInfo(" << TargetName << "RegDesc, "
     << Regs.size()+1 << ", RA, " << TargetName << "MCRegisterClasses, "
     << RegisterClasses.size() << ", "
     << TargetName << "RegUnitRoots, "
     << RegBank.getNumNativeRegUnits() << ", "
     << TargetName << "RegDiffLists, "
     << TargetName << "RegStrings, "
     << TargetName << "SubRegIdxLists, "
     << (SubRegIndices.size() + 1) << ",\n"
     << "  " << TargetName << "RegEncodingTable);\n\n";

  EmitRegMapping(OS, Regs, false);

  OS << "}\n\n";

  OS << "} // End llvm namespace \n";
  OS << "#endif // GET_REGINFO_MC_DESC\n\n";
}

void
RegisterInfoEmitter::runTargetHeader(raw_ostream &OS, CodeGenTarget &Target,
                                     CodeGenRegBank &RegBank) {
  emitSourceFileHeader("Register Information Header Fragment", OS);

  OS << "\n#ifdef GET_REGINFO_HEADER\n";
  OS << "#undef GET_REGINFO_HEADER\n";

  const std::string &TargetName = Target.getName();
  std::string ClassName = TargetName + "GenRegisterInfo";

  OS << "#include \"llvm/Target/TargetRegisterInfo.h\"\n\n";

  OS << "namespace llvm {\n\n";

  OS << "struct " << ClassName << " : public TargetRegisterInfo {\n"
     << "  explicit " << ClassName
     << "(unsigned RA, unsigned D = 0, unsigned E = 0);\n"
     << "  virtual bool needsStackRealignment(const MachineFunction &) const\n"
     << "     { return false; }\n";
  if (!RegBank.getSubRegIndices().empty()) {
    OS << "  virtual unsigned composeSubRegIndices(unsigned, unsigned) const;\n"
      << "  virtual const TargetRegisterClass *"
      "getSubClassWithSubReg(const TargetRegisterClass*, unsigned) const;\n";
  }
  OS << "  virtual const RegClassWeight &getRegClassWeight("
     << "const TargetRegisterClass *RC) const;\n"
     << "  virtual unsigned getNumRegPressureSets() const;\n"
     << "  virtual const char *getRegPressureSetName(unsigned Idx) const;\n"
     << "  virtual unsigned getRegPressureSetLimit(unsigned Idx) const;\n"
     << "  virtual const int *getRegClassPressureSets("
     << "const TargetRegisterClass *RC) const;\n"
     << "};\n\n";

  ArrayRef<CodeGenRegisterClass*> RegisterClasses = RegBank.getRegClasses();

  if (!RegisterClasses.empty()) {
    OS << "namespace " << RegisterClasses[0]->Namespace
       << " { // Register classes\n";

    for (unsigned i = 0, e = RegisterClasses.size(); i != e; ++i) {
      const CodeGenRegisterClass &RC = *RegisterClasses[i];
      const std::string &Name = RC.getName();

      // Output the extern for the instance.
      OS << "  extern const TargetRegisterClass " << Name << "RegClass;\n";
    }
    OS << "} // end of namespace " << TargetName << "\n\n";
  }
  OS << "} // End llvm namespace \n";
  OS << "#endif // GET_REGINFO_HEADER\n\n";
}

//
// runTargetDesc - Output the target register and register file descriptions.
//
void
RegisterInfoEmitter::runTargetDesc(raw_ostream &OS, CodeGenTarget &Target,
                                   CodeGenRegBank &RegBank){
  emitSourceFileHeader("Target Register and Register Classes Information", OS);

  OS << "\n#ifdef GET_REGINFO_TARGET_DESC\n";
  OS << "#undef GET_REGINFO_TARGET_DESC\n";

  OS << "namespace llvm {\n\n";

  // Get access to MCRegisterClass data.
  OS << "extern const MCRegisterClass " << Target.getName()
     << "MCRegisterClasses[];\n";

  // Start out by emitting each of the register classes.
  ArrayRef<CodeGenRegisterClass*> RegisterClasses = RegBank.getRegClasses();
  ArrayRef<CodeGenSubRegIndex*> SubRegIndices = RegBank.getSubRegIndices();

  // Collect all registers belonging to any allocatable class.
  std::set<Record*> AllocatableRegs;

  // Collect allocatable registers.
  for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc) {
    const CodeGenRegisterClass &RC = *RegisterClasses[rc];
    ArrayRef<Record*> Order = RC.getOrder();

    if (RC.Allocatable)
      AllocatableRegs.insert(Order.begin(), Order.end());
  }

  // Build a shared array of value types.
  SequenceToOffsetTable<std::vector<MVT::SimpleValueType> > VTSeqs;
  for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc)
    VTSeqs.add(RegisterClasses[rc]->VTs);
  VTSeqs.layout();
  OS << "\nstatic const MVT::SimpleValueType VTLists[] = {\n";
  VTSeqs.emit(OS, printSimpleValueType, "MVT::Other");
  OS << "};\n";

  // Emit SubRegIndex names, skipping 0.
  OS << "\nstatic const char *const SubRegIndexNameTable[] = { \"";
  for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i) {
    OS << SubRegIndices[i]->getName();
    if (i + 1 != e)
      OS << "\", \"";
  }
  OS << "\" };\n\n";

  // Emit SubRegIndex lane masks, including 0.
  OS << "\nstatic const unsigned SubRegIndexLaneMaskTable[] = {\n  ~0u,\n";
  for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i) {
    OS << format("  0x%08x, // ", SubRegIndices[i]->LaneMask)
       << SubRegIndices[i]->getName() << '\n';
  }
  OS << " };\n\n";

  OS << "\n";

  // Now that all of the structs have been emitted, emit the instances.
  if (!RegisterClasses.empty()) {
    OS << "\nstatic const TargetRegisterClass *const "
       << "NullRegClasses[] = { NULL };\n\n";

    // Emit register class bit mask tables. The first bit mask emitted for a
    // register class, RC, is the set of sub-classes, including RC itself.
    //
    // If RC has super-registers, also create a list of subreg indices and bit
    // masks, (Idx, Mask). The bit mask has a bit for every superreg regclass,
    // SuperRC, that satisfies:
    //
    //   For all SuperReg in SuperRC: SuperReg:Idx in RC
    //
    // The 0-terminated list of subreg indices starts at:
    //
    //   RC->getSuperRegIndices() = SuperRegIdxSeqs + ...
    //
    // The corresponding bitmasks follow the sub-class mask in memory. Each
    // mask has RCMaskWords uint32_t entries.
    //
    // Every bit mask present in the list has at least one bit set.

    // Compress the sub-reg index lists.
    typedef std::vector<const CodeGenSubRegIndex*> IdxList;
    SmallVector<IdxList, 8> SuperRegIdxLists(RegisterClasses.size());
    SequenceToOffsetTable<IdxList> SuperRegIdxSeqs;
    BitVector MaskBV(RegisterClasses.size());

    for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc) {
      const CodeGenRegisterClass &RC = *RegisterClasses[rc];
      OS << "static const uint32_t " << RC.getName() << "SubClassMask[] = {\n  ";
      printBitVectorAsHex(OS, RC.getSubClasses(), 32);

      // Emit super-reg class masks for any relevant SubRegIndices that can
      // project into RC.
      IdxList &SRIList = SuperRegIdxLists[rc];
      for (unsigned sri = 0, sre = SubRegIndices.size(); sri != sre; ++sri) {
        CodeGenSubRegIndex *Idx = SubRegIndices[sri];
        MaskBV.reset();
        RC.getSuperRegClasses(Idx, MaskBV);
        if (MaskBV.none())
          continue;
        SRIList.push_back(Idx);
        OS << "\n  ";
        printBitVectorAsHex(OS, MaskBV, 32);
        OS << "// " << Idx->getName();
      }
      SuperRegIdxSeqs.add(SRIList);
      OS << "\n};\n\n";
    }

    OS << "static const uint16_t SuperRegIdxSeqs[] = {\n";
    SuperRegIdxSeqs.layout();
    SuperRegIdxSeqs.emit(OS, printSubRegIndex);
    OS << "};\n\n";

    // Emit NULL terminated super-class lists.
    for (unsigned rc = 0, e = RegisterClasses.size(); rc != e; ++rc) {
      const CodeGenRegisterClass &RC = *RegisterClasses[rc];
      ArrayRef<CodeGenRegisterClass*> Supers = RC.getSuperClasses();

      // Skip classes without supers.  We can reuse NullRegClasses.
      if (Supers.empty())
        continue;

      OS << "static const TargetRegisterClass *const "
         << RC.getName() << "Superclasses[] = {\n";
      for (unsigned i = 0; i != Supers.size(); ++i)
        OS << "  &" << Supers[i]->getQualifiedName() << "RegClass,\n";
      OS << "  NULL\n};\n\n";
    }

    // Emit methods.
    for (unsigned i = 0, e = RegisterClasses.size(); i != e; ++i) {
      const CodeGenRegisterClass &RC = *RegisterClasses[i];
      if (!RC.AltOrderSelect.empty()) {
        OS << "\nstatic inline unsigned " << RC.getName()
           << "AltOrderSelect(const MachineFunction &MF) {"
           << RC.AltOrderSelect << "}\n\n"
           << "static ArrayRef<uint16_t> " << RC.getName()
           << "GetRawAllocationOrder(const MachineFunction &MF) {\n";
        for (unsigned oi = 1 , oe = RC.getNumOrders(); oi != oe; ++oi) {
          ArrayRef<Record*> Elems = RC.getOrder(oi);
          if (!Elems.empty()) {
            OS << "  static const uint16_t AltOrder" << oi << "[] = {";
            for (unsigned elem = 0; elem != Elems.size(); ++elem)
              OS << (elem ? ", " : " ") << getQualifiedName(Elems[elem]);
            OS << " };\n";
          }
        }
        OS << "  const MCRegisterClass &MCR = " << Target.getName()
           << "MCRegisterClasses[" << RC.getQualifiedName() + "RegClassID];\n"
           << "  const ArrayRef<uint16_t> Order[] = {\n"
           << "    makeArrayRef(MCR.begin(), MCR.getNumRegs()";
        for (unsigned oi = 1, oe = RC.getNumOrders(); oi != oe; ++oi)
          if (RC.getOrder(oi).empty())
            OS << "),\n    ArrayRef<uint16_t>(";
          else
            OS << "),\n    makeArrayRef(AltOrder" << oi;
        OS << ")\n  };\n  const unsigned Select = " << RC.getName()
           << "AltOrderSelect(MF);\n  assert(Select < " << RC.getNumOrders()
           << ");\n  return Order[Select];\n}\n";
        }
    }

    // Now emit the actual value-initialized register class instances.
    OS << "namespace " << RegisterClasses[0]->Namespace
       << " {   // Register class instances\n";

    for (unsigned i = 0, e = RegisterClasses.size(); i != e; ++i) {
      const CodeGenRegisterClass &RC = *RegisterClasses[i];
      OS << "  extern const TargetRegisterClass "
         << RegisterClasses[i]->getName() << "RegClass = {\n    "
         << '&' << Target.getName() << "MCRegisterClasses[" << RC.getName()
         << "RegClassID],\n    "
         << "VTLists + " << VTSeqs.get(RC.VTs) << ",\n    "
         << RC.getName() << "SubClassMask,\n    SuperRegIdxSeqs + "
         << SuperRegIdxSeqs.get(SuperRegIdxLists[i]) << ",\n    ";
      if (RC.getSuperClasses().empty())
        OS << "NullRegClasses,\n    ";
      else
        OS << RC.getName() << "Superclasses,\n    ";
      if (RC.AltOrderSelect.empty())
        OS << "0\n";
      else
        OS << RC.getName() << "GetRawAllocationOrder\n";
      OS << "  };\n\n";
    }

    OS << "}\n";
  }

  OS << "\nnamespace {\n";
  OS << "  const TargetRegisterClass* const RegisterClasses[] = {\n";
  for (unsigned i = 0, e = RegisterClasses.size(); i != e; ++i)
    OS << "    &" << RegisterClasses[i]->getQualifiedName()
       << "RegClass,\n";
  OS << "  };\n";
  OS << "}\n";       // End of anonymous namespace...

  // Emit extra information about registers.
  const std::string &TargetName = Target.getName();
  OS << "\nstatic const TargetRegisterInfoDesc "
     << TargetName << "RegInfoDesc[] = { // Extra Descriptors\n";
  OS << "  { 0, 0 },\n";

  const std::vector<CodeGenRegister*> &Regs = RegBank.getRegisters();
  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
    const CodeGenRegister &Reg = *Regs[i];
    OS << "  { ";
    OS << Reg.CostPerUse << ", "
       << int(AllocatableRegs.count(Reg.TheDef)) << " },\n";
  }
  OS << "};\n";      // End of register descriptors...


  std::string ClassName = Target.getName() + "GenRegisterInfo";

  // Emit composeSubRegIndices
  if (!SubRegIndices.empty()) {
    OS << "unsigned " << ClassName
      << "::composeSubRegIndices(unsigned IdxA, unsigned IdxB) const {\n"
      << "  switch (IdxA) {\n"
      << "  default:\n    return IdxB;\n";
    for (unsigned i = 0, e = SubRegIndices.size(); i != e; ++i) {
      bool Open = false;
      for (unsigned j = 0; j != e; ++j) {
        CodeGenSubRegIndex *Comp = SubRegIndices[i]->compose(SubRegIndices[j]);
        if (Comp && Comp != SubRegIndices[j]) {
          if (!Open) {
            OS << "  case " << SubRegIndices[i]->getQualifiedName()
              << ": switch(IdxB) {\n    default: return IdxB;\n";
            Open = true;
          }
          OS << "    case " << SubRegIndices[j]->getQualifiedName()
            << ": return " << Comp->getQualifiedName() << ";\n";
        }
      }
      if (Open)
        OS << "    }\n";
    }
    OS << "  }\n}\n\n";
  }

  // Emit getSubClassWithSubReg.
  if (!SubRegIndices.empty()) {
    OS << "const TargetRegisterClass *" << ClassName
       << "::getSubClassWithSubReg(const TargetRegisterClass *RC, unsigned Idx)"
       << " const {\n";
    // Use the smallest type that can hold a regclass ID with room for a
    // sentinel.
    if (RegisterClasses.size() < UINT8_MAX)
      OS << "  static const uint8_t Table[";
    else if (RegisterClasses.size() < UINT16_MAX)
      OS << "  static const uint16_t Table[";
    else
      throw "Too many register classes.";
    OS << RegisterClasses.size() << "][" << SubRegIndices.size() << "] = {\n";
    for (unsigned rci = 0, rce = RegisterClasses.size(); rci != rce; ++rci) {
      const CodeGenRegisterClass &RC = *RegisterClasses[rci];
      OS << "    {\t// " << RC.getName() << "\n";
      for (unsigned sri = 0, sre = SubRegIndices.size(); sri != sre; ++sri) {
        CodeGenSubRegIndex *Idx = SubRegIndices[sri];
        if (CodeGenRegisterClass *SRC = RC.getSubClassWithSubReg(Idx))
          OS << "      " << SRC->EnumValue + 1 << ",\t// " << Idx->getName()
             << " -> " << SRC->getName() << "\n";
        else
          OS << "      0,\t// " << Idx->getName() << "\n";
      }
      OS << "    },\n";
    }
    OS << "  };\n  assert(RC && \"Missing regclass\");\n"
       << "  if (!Idx) return RC;\n  --Idx;\n"
       << "  assert(Idx < " << SubRegIndices.size() << " && \"Bad subreg\");\n"
       << "  unsigned TV = Table[RC->getID()][Idx];\n"
       << "  return TV ? getRegClass(TV - 1) : 0;\n}\n\n";
  }

  EmitRegUnitPressure(OS, RegBank, ClassName);

  // Emit the constructor of the class...
  OS << "extern const MCRegisterDesc " << TargetName << "RegDesc[];\n";
  OS << "extern const uint16_t " << TargetName << "RegDiffLists[];\n";
  OS << "extern const char " << TargetName << "RegStrings[];\n";
  OS << "extern const uint16_t " << TargetName << "RegUnitRoots[][2];\n";
  OS << "extern const uint16_t " << TargetName << "SubRegIdxLists[];\n";
  OS << "extern const uint16_t " << TargetName << "RegEncodingTable[];\n";

  EmitRegMappingTables(OS, Regs, true);

  OS << ClassName << "::\n" << ClassName
     << "(unsigned RA, unsigned DwarfFlavour, unsigned EHFlavour)\n"
     << "  : TargetRegisterInfo(" << TargetName << "RegInfoDesc"
     << ", RegisterClasses, RegisterClasses+" << RegisterClasses.size() <<",\n"
     << "             SubRegIndexNameTable, SubRegIndexLaneMaskTable) {\n"
     << "  InitMCRegisterInfo(" << TargetName << "RegDesc, "
     << Regs.size()+1 << ", RA,\n                     " << TargetName
     << "MCRegisterClasses, " << RegisterClasses.size() << ",\n"
     << "                     " << TargetName << "RegUnitRoots,\n"
     << "                     " << RegBank.getNumNativeRegUnits() << ",\n"
     << "                     " << TargetName << "RegDiffLists,\n"
     << "                     " << TargetName << "RegStrings,\n"
     << "                     " << TargetName << "SubRegIdxLists,\n"
     << "                     " << SubRegIndices.size() + 1 << ",\n"
     << "                     " << TargetName << "RegEncodingTable);\n\n";

  EmitRegMapping(OS, Regs, true);

  OS << "}\n\n";


  // Emit CalleeSavedRegs information.
  std::vector<Record*> CSRSets =
    Records.getAllDerivedDefinitions("CalleeSavedRegs");
  for (unsigned i = 0, e = CSRSets.size(); i != e; ++i) {
    Record *CSRSet = CSRSets[i];
    const SetTheory::RecVec *Regs = RegBank.getSets().expand(CSRSet);
    assert(Regs && "Cannot expand CalleeSavedRegs instance");

    // Emit the *_SaveList list of callee-saved registers.
    OS << "static const uint16_t " << CSRSet->getName()
       << "_SaveList[] = { ";
    for (unsigned r = 0, re = Regs->size(); r != re; ++r)
      OS << getQualifiedName((*Regs)[r]) << ", ";
    OS << "0 };\n";

    // Emit the *_RegMask bit mask of call-preserved registers.
    OS << "static const uint32_t " << CSRSet->getName()
       << "_RegMask[] = { ";
    printBitVectorAsHex(OS, RegBank.computeCoveredRegisters(*Regs), 32);
    OS << "};\n";
  }
  OS << "\n\n";

  OS << "} // End llvm namespace \n";
  OS << "#endif // GET_REGINFO_TARGET_DESC\n\n";
}

void RegisterInfoEmitter::run(raw_ostream &OS) {
  CodeGenTarget Target(Records);
  CodeGenRegBank &RegBank = Target.getRegBank();
  RegBank.computeDerivedInfo();

  runEnums(OS, Target, RegBank);
  runMCDesc(OS, Target, RegBank);
  runTargetHeader(OS, Target, RegBank);
  runTargetDesc(OS, Target, RegBank);
}

namespace llvm {

void EmitRegisterInfo(RecordKeeper &RK, raw_ostream &OS) {
  RegisterInfoEmitter(RK).run(OS);
}

} // End llvm namespace