llvm-for-llvmta/lib/DebugInfo/MSF/MappedBlockStream.cpp

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//===- MappedBlockStream.cpp - Reads stream data from an MSF file ---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/DebugInfo/MSF/MSFCommon.h"
#include "llvm/Support/BinaryStreamWriter.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstring>
#include <utility>
#include <vector>
using namespace llvm;
using namespace llvm::msf;
namespace {
template <typename Base> class MappedBlockStreamImpl : public Base {
public:
template <typename... Args>
MappedBlockStreamImpl(Args &&... Params)
: Base(std::forward<Args>(Params)...) {}
};
} // end anonymous namespace
using Interval = std::pair<uint32_t, uint32_t>;
static Interval intersect(const Interval &I1, const Interval &I2) {
return std::make_pair(std::max(I1.first, I2.first),
std::min(I1.second, I2.second));
}
MappedBlockStream::MappedBlockStream(uint32_t BlockSize,
const MSFStreamLayout &Layout,
BinaryStreamRef MsfData,
BumpPtrAllocator &Allocator)
: BlockSize(BlockSize), StreamLayout(Layout), MsfData(MsfData),
Allocator(Allocator) {}
std::unique_ptr<MappedBlockStream> MappedBlockStream::createStream(
uint32_t BlockSize, const MSFStreamLayout &Layout, BinaryStreamRef MsfData,
BumpPtrAllocator &Allocator) {
return std::make_unique<MappedBlockStreamImpl<MappedBlockStream>>(
BlockSize, Layout, MsfData, Allocator);
}
std::unique_ptr<MappedBlockStream> MappedBlockStream::createIndexedStream(
const MSFLayout &Layout, BinaryStreamRef MsfData, uint32_t StreamIndex,
BumpPtrAllocator &Allocator) {
assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
MSFStreamLayout SL;
SL.Blocks = Layout.StreamMap[StreamIndex];
SL.Length = Layout.StreamSizes[StreamIndex];
return std::make_unique<MappedBlockStreamImpl<MappedBlockStream>>(
Layout.SB->BlockSize, SL, MsfData, Allocator);
}
std::unique_ptr<MappedBlockStream>
MappedBlockStream::createDirectoryStream(const MSFLayout &Layout,
BinaryStreamRef MsfData,
BumpPtrAllocator &Allocator) {
MSFStreamLayout SL;
SL.Blocks = Layout.DirectoryBlocks;
SL.Length = Layout.SB->NumDirectoryBytes;
return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
}
std::unique_ptr<MappedBlockStream>
MappedBlockStream::createFpmStream(const MSFLayout &Layout,
BinaryStreamRef MsfData,
BumpPtrAllocator &Allocator) {
MSFStreamLayout SL(getFpmStreamLayout(Layout));
return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
}
Error MappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
ArrayRef<uint8_t> &Buffer) {
// Make sure we aren't trying to read beyond the end of the stream.
if (auto EC = checkOffsetForRead(Offset, Size))
return EC;
if (tryReadContiguously(Offset, Size, Buffer))
return Error::success();
auto CacheIter = CacheMap.find(Offset);
if (CacheIter != CacheMap.end()) {
// Try to find an alloc that was large enough for this request.
for (auto &Entry : CacheIter->second) {
if (Entry.size() >= Size) {
Buffer = Entry.slice(0, Size);
return Error::success();
}
}
}
// We couldn't find a buffer that started at the correct offset (the most
// common scenario). Try to see if there is a buffer that starts at some
// other offset but overlaps the desired range.
for (auto &CacheItem : CacheMap) {
Interval RequestExtent = std::make_pair(Offset, Offset + Size);
// We already checked this one on the fast path above.
if (CacheItem.first == Offset)
continue;
// If the initial extent of the cached item is beyond the ending extent
// of the request, there is no overlap.
if (CacheItem.first >= Offset + Size)
continue;
// We really only have to check the last item in the list, since we append
// in order of increasing length.
if (CacheItem.second.empty())
continue;
auto CachedAlloc = CacheItem.second.back();
// If the initial extent of the request is beyond the ending extent of
// the cached item, there is no overlap.
Interval CachedExtent =
std::make_pair(CacheItem.first, CacheItem.first + CachedAlloc.size());
if (RequestExtent.first >= CachedExtent.first + CachedExtent.second)
continue;
Interval Intersection = intersect(CachedExtent, RequestExtent);
// Only use this if the entire request extent is contained in the cached
// extent.
if (Intersection != RequestExtent)
continue;
uint32_t CacheRangeOffset =
AbsoluteDifference(CachedExtent.first, Intersection.first);
Buffer = CachedAlloc.slice(CacheRangeOffset, Size);
return Error::success();
}
// Otherwise allocate a large enough buffer in the pool, memcpy the data
// into it, and return an ArrayRef to that. Do not touch existing pool
// allocations, as existing clients may be holding a pointer which must
// not be invalidated.
uint8_t *WriteBuffer = static_cast<uint8_t *>(Allocator.Allocate(Size, 8));
if (auto EC = readBytes(Offset, MutableArrayRef<uint8_t>(WriteBuffer, Size)))
return EC;
if (CacheIter != CacheMap.end()) {
CacheIter->second.emplace_back(WriteBuffer, Size);
} else {
std::vector<CacheEntry> List;
List.emplace_back(WriteBuffer, Size);
CacheMap.insert(std::make_pair(Offset, List));
}
Buffer = ArrayRef<uint8_t>(WriteBuffer, Size);
return Error::success();
}
Error MappedBlockStream::readLongestContiguousChunk(uint32_t Offset,
ArrayRef<uint8_t> &Buffer) {
// Make sure we aren't trying to read beyond the end of the stream.
if (auto EC = checkOffsetForRead(Offset, 1))
return EC;
uint32_t First = Offset / BlockSize;
uint32_t Last = First;
while (Last < getNumBlocks() - 1) {
if (StreamLayout.Blocks[Last] != StreamLayout.Blocks[Last + 1] - 1)
break;
++Last;
}
uint32_t OffsetInFirstBlock = Offset % BlockSize;
uint32_t BytesFromFirstBlock = BlockSize - OffsetInFirstBlock;
uint32_t BlockSpan = Last - First + 1;
uint32_t ByteSpan = BytesFromFirstBlock + (BlockSpan - 1) * BlockSize;
ArrayRef<uint8_t> BlockData;
uint32_t MsfOffset = blockToOffset(StreamLayout.Blocks[First], BlockSize);
if (auto EC = MsfData.readBytes(MsfOffset, BlockSize, BlockData))
return EC;
BlockData = BlockData.drop_front(OffsetInFirstBlock);
Buffer = ArrayRef<uint8_t>(BlockData.data(), ByteSpan);
return Error::success();
}
uint32_t MappedBlockStream::getLength() { return StreamLayout.Length; }
bool MappedBlockStream::tryReadContiguously(uint32_t Offset, uint32_t Size,
ArrayRef<uint8_t> &Buffer) {
if (Size == 0) {
Buffer = ArrayRef<uint8_t>();
return true;
}
// Attempt to fulfill the request with a reference directly into the stream.
// This can work even if the request crosses a block boundary, provided that
// all subsequent blocks are contiguous. For example, a 10k read with a 4k
// block size can be filled with a reference if, from the starting offset,
// 3 blocks in a row are contiguous.
uint32_t BlockNum = Offset / BlockSize;
uint32_t OffsetInBlock = Offset % BlockSize;
uint32_t BytesFromFirstBlock = std::min(Size, BlockSize - OffsetInBlock);
uint32_t NumAdditionalBlocks =
alignTo(Size - BytesFromFirstBlock, BlockSize) / BlockSize;
uint32_t RequiredContiguousBlocks = NumAdditionalBlocks + 1;
uint32_t E = StreamLayout.Blocks[BlockNum];
for (uint32_t I = 0; I < RequiredContiguousBlocks; ++I, ++E) {
if (StreamLayout.Blocks[I + BlockNum] != E)
return false;
}
// Read out the entire block where the requested offset starts. Then drop
// bytes from the beginning so that the actual starting byte lines up with
// the requested starting byte. Then, since we know this is a contiguous
// cross-block span, explicitly resize the ArrayRef to cover the entire
// request length.
ArrayRef<uint8_t> BlockData;
uint32_t FirstBlockAddr = StreamLayout.Blocks[BlockNum];
uint32_t MsfOffset = blockToOffset(FirstBlockAddr, BlockSize);
if (auto EC = MsfData.readBytes(MsfOffset, BlockSize, BlockData)) {
consumeError(std::move(EC));
return false;
}
BlockData = BlockData.drop_front(OffsetInBlock);
Buffer = ArrayRef<uint8_t>(BlockData.data(), Size);
return true;
}
Error MappedBlockStream::readBytes(uint32_t Offset,
MutableArrayRef<uint8_t> Buffer) {
uint32_t BlockNum = Offset / BlockSize;
uint32_t OffsetInBlock = Offset % BlockSize;
// Make sure we aren't trying to read beyond the end of the stream.
if (auto EC = checkOffsetForRead(Offset, Buffer.size()))
return EC;
uint32_t BytesLeft = Buffer.size();
uint32_t BytesWritten = 0;
uint8_t *WriteBuffer = Buffer.data();
while (BytesLeft > 0) {
uint32_t StreamBlockAddr = StreamLayout.Blocks[BlockNum];
ArrayRef<uint8_t> BlockData;
uint32_t Offset = blockToOffset(StreamBlockAddr, BlockSize);
if (auto EC = MsfData.readBytes(Offset, BlockSize, BlockData))
return EC;
const uint8_t *ChunkStart = BlockData.data() + OffsetInBlock;
uint32_t BytesInChunk = std::min(BytesLeft, BlockSize - OffsetInBlock);
::memcpy(WriteBuffer + BytesWritten, ChunkStart, BytesInChunk);
BytesWritten += BytesInChunk;
BytesLeft -= BytesInChunk;
++BlockNum;
OffsetInBlock = 0;
}
return Error::success();
}
void MappedBlockStream::invalidateCache() { CacheMap.shrink_and_clear(); }
void MappedBlockStream::fixCacheAfterWrite(uint32_t Offset,
ArrayRef<uint8_t> Data) const {
// If this write overlapped a read which previously came from the pool,
// someone may still be holding a pointer to that alloc which is now invalid.
// Compute the overlapping range and update the cache entry, so any
// outstanding buffers are automatically updated.
for (const auto &MapEntry : CacheMap) {
// If the end of the written extent precedes the beginning of the cached
// extent, ignore this map entry.
if (Offset + Data.size() < MapEntry.first)
continue;
for (const auto &Alloc : MapEntry.second) {
// If the end of the cached extent precedes the beginning of the written
// extent, ignore this alloc.
if (MapEntry.first + Alloc.size() < Offset)
continue;
// If we get here, they are guaranteed to overlap.
Interval WriteInterval = std::make_pair(Offset, Offset + Data.size());
Interval CachedInterval =
std::make_pair(MapEntry.first, MapEntry.first + Alloc.size());
// If they overlap, we need to write the new data into the overlapping
// range.
auto Intersection = intersect(WriteInterval, CachedInterval);
assert(Intersection.first <= Intersection.second);
uint32_t Length = Intersection.second - Intersection.first;
uint32_t SrcOffset =
AbsoluteDifference(WriteInterval.first, Intersection.first);
uint32_t DestOffset =
AbsoluteDifference(CachedInterval.first, Intersection.first);
::memcpy(Alloc.data() + DestOffset, Data.data() + SrcOffset, Length);
}
}
}
WritableMappedBlockStream::WritableMappedBlockStream(
uint32_t BlockSize, const MSFStreamLayout &Layout,
WritableBinaryStreamRef MsfData, BumpPtrAllocator &Allocator)
: ReadInterface(BlockSize, Layout, MsfData, Allocator),
WriteInterface(MsfData) {}
std::unique_ptr<WritableMappedBlockStream>
WritableMappedBlockStream::createStream(uint32_t BlockSize,
const MSFStreamLayout &Layout,
WritableBinaryStreamRef MsfData,
BumpPtrAllocator &Allocator) {
return std::make_unique<MappedBlockStreamImpl<WritableMappedBlockStream>>(
BlockSize, Layout, MsfData, Allocator);
}
std::unique_ptr<WritableMappedBlockStream>
WritableMappedBlockStream::createIndexedStream(const MSFLayout &Layout,
WritableBinaryStreamRef MsfData,
uint32_t StreamIndex,
BumpPtrAllocator &Allocator) {
assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
MSFStreamLayout SL;
SL.Blocks = Layout.StreamMap[StreamIndex];
SL.Length = Layout.StreamSizes[StreamIndex];
return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
}
std::unique_ptr<WritableMappedBlockStream>
WritableMappedBlockStream::createDirectoryStream(
const MSFLayout &Layout, WritableBinaryStreamRef MsfData,
BumpPtrAllocator &Allocator) {
MSFStreamLayout SL;
SL.Blocks = Layout.DirectoryBlocks;
SL.Length = Layout.SB->NumDirectoryBytes;
return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
}
std::unique_ptr<WritableMappedBlockStream>
WritableMappedBlockStream::createFpmStream(const MSFLayout &Layout,
WritableBinaryStreamRef MsfData,
BumpPtrAllocator &Allocator,
bool AltFpm) {
// We only want to give the user a stream containing the bytes of the FPM that
// are actually valid, but we want to initialize all of the bytes, even those
// that come from reserved FPM blocks where the entire block is unused. To do
// this, we first create the full layout, which gives us a stream with all
// bytes and all blocks, and initialize everything to 0xFF (all blocks in the
// file are unused). Then we create the minimal layout (which contains only a
// subset of the bytes previously initialized), and return that to the user.
MSFStreamLayout MinLayout(getFpmStreamLayout(Layout, false, AltFpm));
MSFStreamLayout FullLayout(getFpmStreamLayout(Layout, true, AltFpm));
auto Result =
createStream(Layout.SB->BlockSize, FullLayout, MsfData, Allocator);
if (!Result)
return Result;
std::vector<uint8_t> InitData(Layout.SB->BlockSize, 0xFF);
BinaryStreamWriter Initializer(*Result);
while (Initializer.bytesRemaining() > 0)
cantFail(Initializer.writeBytes(InitData));
return createStream(Layout.SB->BlockSize, MinLayout, MsfData, Allocator);
}
Error WritableMappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
ArrayRef<uint8_t> &Buffer) {
return ReadInterface.readBytes(Offset, Size, Buffer);
}
Error WritableMappedBlockStream::readLongestContiguousChunk(
uint32_t Offset, ArrayRef<uint8_t> &Buffer) {
return ReadInterface.readLongestContiguousChunk(Offset, Buffer);
}
uint32_t WritableMappedBlockStream::getLength() {
return ReadInterface.getLength();
}
Error WritableMappedBlockStream::writeBytes(uint32_t Offset,
ArrayRef<uint8_t> Buffer) {
// Make sure we aren't trying to write beyond the end of the stream.
if (auto EC = checkOffsetForWrite(Offset, Buffer.size()))
return EC;
uint32_t BlockNum = Offset / getBlockSize();
uint32_t OffsetInBlock = Offset % getBlockSize();
uint32_t BytesLeft = Buffer.size();
uint32_t BytesWritten = 0;
while (BytesLeft > 0) {
uint32_t StreamBlockAddr = getStreamLayout().Blocks[BlockNum];
uint32_t BytesToWriteInChunk =
std::min(BytesLeft, getBlockSize() - OffsetInBlock);
const uint8_t *Chunk = Buffer.data() + BytesWritten;
ArrayRef<uint8_t> ChunkData(Chunk, BytesToWriteInChunk);
uint32_t MsfOffset = blockToOffset(StreamBlockAddr, getBlockSize());
MsfOffset += OffsetInBlock;
if (auto EC = WriteInterface.writeBytes(MsfOffset, ChunkData))
return EC;
BytesLeft -= BytesToWriteInChunk;
BytesWritten += BytesToWriteInChunk;
++BlockNum;
OffsetInBlock = 0;
}
ReadInterface.fixCacheAfterWrite(Offset, Buffer);
return Error::success();
}
Error WritableMappedBlockStream::commit() { return WriteInterface.commit(); }