llvm/lib/DebugInfo/PDB/Raw/MsfBuilder.cpp

//===- MSFBuilder.cpp - MSF Directory & Metadata Builder --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/DebugInfo/PDB/Raw/MsfBuilder.h"
#include "llvm/DebugInfo/PDB/Raw/RawError.h"

using namespace llvm;
using namespace llvm::pdb;
using namespace llvm::pdb::msf;
using namespace llvm::support;

namespace {
const uint32_t kSuperBlockBlock = 0;
const uint32_t kDefaultBlockMapAddr = 1;
}

MsfBuilder::MsfBuilder(uint32_t BlockSize, uint32_t MinBlockCount, bool CanGrow,
                       BumpPtrAllocator &Allocator)
    : Allocator(Allocator), IsGrowable(CanGrow), BlockSize(BlockSize),
      MininumBlocks(MinBlockCount), BlockMapAddr(kDefaultBlockMapAddr),
      FreeBlocks(MinBlockCount + 2U, true) {
  FreeBlocks[kSuperBlockBlock] = false;
  FreeBlocks[BlockMapAddr] = false;
}

Expected<MsfBuilder> MsfBuilder::create(BumpPtrAllocator &Allocator,
                                        uint32_t BlockSize,
                                        uint32_t MinBlockCount, bool CanGrow) {
  if (!msf::isValidBlockSize(BlockSize))
    return make_error<RawError>(raw_error_code::unspecified,
                                "The requested block size is unsupported");

  return MsfBuilder(BlockSize, MinBlockCount, CanGrow, Allocator);
}

Error MsfBuilder::setBlockMapAddr(uint32_t Addr) {
  if (Addr == BlockMapAddr)
    return Error::success();

  if (Addr >= FreeBlocks.size()) {
    if (!IsGrowable)
      return make_error<RawError>(raw_error_code::unspecified,
                                  "Cannot grow the number of blocks");
    FreeBlocks.resize(Addr + 1);
  }

  if (!isBlockFree(Addr))
    return make_error<RawError>(raw_error_code::unspecified,
                                "Attempt to reuse an allocated block");
  FreeBlocks[BlockMapAddr] = true;
  FreeBlocks[Addr] = false;
  BlockMapAddr = Addr;
  return Error::success();
}

Error MsfBuilder::allocateBlocks(uint32_t NumBlocks,
                                 MutableArrayRef<uint32_t> Blocks) {
  if (NumBlocks == 0)
    return Error::success();

  uint32_t NumFreeBlocks = FreeBlocks.count();
  if (NumFreeBlocks < NumBlocks) {
    if (!IsGrowable)
      return make_error<RawError>(raw_error_code::unspecified,
                                  "There are no free Blocks in the file");
    uint32_t AllocBlocks = NumBlocks - NumFreeBlocks;
    FreeBlocks.resize(AllocBlocks + FreeBlocks.size(), true);
  }

  int I = 0;
  int Block = FreeBlocks.find_first();
  do {
    assert(Block != -1 && "We ran out of Blocks!");

    uint32_t NextBlock = static_cast<uint32_t>(Block);
    Blocks[I++] = NextBlock;
    FreeBlocks.reset(NextBlock);
    Block = FreeBlocks.find_next(Block);
  } while (--NumBlocks > 0);
  return Error::success();
}

uint32_t MsfBuilder::getNumUsedBlocks() const {
  return getTotalBlockCount() - getNumFreeBlocks();
}

uint32_t MsfBuilder::getNumFreeBlocks() const { return FreeBlocks.count(); }

uint32_t MsfBuilder::getTotalBlockCount() const { return FreeBlocks.size(); }

bool MsfBuilder::isBlockFree(uint32_t Idx) const { return FreeBlocks[Idx]; }

Error MsfBuilder::addStream(uint32_t Size, ArrayRef<uint32_t> Blocks) {
  // Add a new stream mapped to the specified blocks.  Verify that the specified
  // blocks are both necessary and sufficient for holding the requested number
  // of bytes, and verify that all requested blocks are free.
  uint32_t ReqBlocks = bytesToBlocks(Size, BlockSize);
  if (ReqBlocks != Blocks.size())
    return make_error<RawError>(
        raw_error_code::unspecified,
        "Incorrect number of blocks for requested stream size");
  for (auto Block : Blocks) {
    if (Block >= FreeBlocks.size())
      FreeBlocks.resize(Block + 1, true);

    if (!FreeBlocks.test(Block))
      return make_error<RawError>(
          raw_error_code::unspecified,
          "Attempt to re-use an already allocated block");
  }
  // Mark all the blocks occupied by the new stream as not free.
  for (auto Block : Blocks) {
    FreeBlocks.reset(Block);
  }
  StreamData.push_back(std::make_pair(Size, Blocks));
  return Error::success();
}

Error MsfBuilder::addStream(uint32_t Size) {
  uint32_t ReqBlocks = bytesToBlocks(Size, BlockSize);
  std::vector<uint32_t> NewBlocks;
  NewBlocks.resize(ReqBlocks);
  if (auto EC = allocateBlocks(ReqBlocks, NewBlocks))
    return EC;
  StreamData.push_back(std::make_pair(Size, NewBlocks));
  return Error::success();
}

Error MsfBuilder::setStreamSize(uint32_t Idx, uint32_t Size) {
  uint32_t OldSize = getStreamSize(Idx);
  if (OldSize == Size)
    return Error::success();

  uint32_t NewBlocks = bytesToBlocks(Size, BlockSize);
  uint32_t OldBlocks = bytesToBlocks(OldSize, BlockSize);

  if (NewBlocks > OldBlocks) {
    uint32_t AddedBlocks = NewBlocks - OldBlocks;
    // If we're growing, we have to allocate new Blocks.
    std::vector<uint32_t> AddedBlockList;
    AddedBlockList.resize(AddedBlocks);
    if (auto EC = allocateBlocks(AddedBlocks, AddedBlockList))
      return EC;
    auto &CurrentBlocks = StreamData[Idx].second;
    CurrentBlocks.insert(CurrentBlocks.end(), AddedBlockList.begin(),
                         AddedBlockList.end());
  } else if (OldBlocks > NewBlocks) {
    // For shrinking, free all the Blocks in the Block map, update the stream
    // data, then shrink the directory.
    uint32_t RemovedBlocks = OldBlocks - NewBlocks;
    auto CurrentBlocks = ArrayRef<uint32_t>(StreamData[Idx].second);
    auto RemovedBlockList = CurrentBlocks.drop_front(NewBlocks);
    for (auto P : RemovedBlockList)
      FreeBlocks[P] = true;
    StreamData[Idx].second = CurrentBlocks.drop_back(RemovedBlocks);
  }

  StreamData[Idx].first = Size;
  return Error::success();
}

uint32_t MsfBuilder::getNumStreams() const { return StreamData.size(); }

uint32_t MsfBuilder::getStreamSize(uint32_t StreamIdx) const {
  return StreamData[StreamIdx].first;
}

ArrayRef<uint32_t> MsfBuilder::getStreamBlocks(uint32_t StreamIdx) const {
  return StreamData[StreamIdx].second;
}

uint32_t MsfBuilder::computeDirectoryByteSize() const {
  // The directory has the following layout, where each item is a ulittle32_t:
  //    NumStreams
  //    StreamSizes[NumStreams]
  //    StreamBlocks[NumStreams][]
  uint32_t Size = sizeof(ulittle32_t);             // NumStreams
  Size += StreamData.size() * sizeof(ulittle32_t); // StreamSizes
  for (const auto &D : StreamData) {
    uint32_t ExpectedNumBlocks = bytesToBlocks(D.first, BlockSize);
    assert(ExpectedNumBlocks == D.second.size() &&
           "Unexpected number of blocks");
    Size += ExpectedNumBlocks * sizeof(ulittle32_t);
  }
  return Size;
}

Expected<Layout> MsfBuilder::build() {
  Layout L;
  L.SB = Allocator.Allocate<SuperBlock>();
  std::memcpy(L.SB->MagicBytes, Magic, sizeof(Magic));
  L.SB->BlockMapAddr = BlockMapAddr;
  L.SB->BlockSize = BlockSize;
  L.SB->NumDirectoryBytes = computeDirectoryByteSize();
  L.SB->Unknown0 = 0;
  L.SB->Unknown1 = 0;

  uint32_t NumDirectoryBlocks =
      bytesToBlocks(L.SB->NumDirectoryBytes, BlockSize);
  // The directory blocks should be re-allocated as a stable pointer.
  std::vector<uint32_t> DirectoryBlocks;
  DirectoryBlocks.resize(NumDirectoryBlocks);
  if (auto EC = allocateBlocks(NumDirectoryBlocks, DirectoryBlocks))
    return std::move(EC);

  // Don't set the number of blocks in the file until after allocating Blocks
  // for
  // the directory, since the allocation might cause the file to need to grow.
  L.SB->NumBlocks = FreeBlocks.size();

  ulittle32_t *DirBlocks = Allocator.Allocate<ulittle32_t>(NumDirectoryBlocks);
  std::uninitialized_copy_n(DirectoryBlocks.begin(), NumDirectoryBlocks,
                            DirBlocks);
  L.DirectoryBlocks = ArrayRef<ulittle32_t>(DirBlocks, NumDirectoryBlocks);

  // The stream sizes should be re-allocated as a stable pointer and the stream
  // map should have each of its entries allocated as a separate stable pointer.
  if (StreamData.size() > 0) {
    ulittle32_t *Sizes = Allocator.Allocate<ulittle32_t>(StreamData.size());
    L.StreamSizes = ArrayRef<ulittle32_t>(Sizes, StreamData.size());
    L.StreamMap.resize(StreamData.size());
    for (uint32_t I = 0; I < StreamData.size(); ++I) {
      Sizes[I] = StreamData[I].first;
      ulittle32_t *BlockList =
          Allocator.Allocate<ulittle32_t>(StreamData[I].second.size());
      std::uninitialized_copy_n(StreamData[I].second.begin(),
                                StreamData[I].second.size(), BlockList);
      L.StreamMap[I] =
          ArrayRef<ulittle32_t>(BlockList, StreamData[I].second.size());
    }
  }

  return L;
}