Add support for writing through StreamInterface.
This adds method and tests for writing to a PDB stream. With
this, even a PDB stream which is discontiguous can be treated
as a sequential stream of bytes for the purposes of writing.
Reviewed By: ruiu
Differential Revision: http://reviews.llvm.org/D21157
llvm-svn: 272369
diff --git a/llvm/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp b/llvm/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
index cae3376..86e799c 100644
--- a/llvm/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Raw/MappedBlockStream.cpp
@@ -29,6 +29,12 @@
};
}
+typedef std::pair<uint32_t, uint32_t> Interval;
+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(std::unique_ptr<IPDBStreamData> Data,
const IPDBFile &Pdb)
: Pdb(Pdb), Data(std::move(Data)) {}
@@ -46,26 +52,99 @@
auto CacheIter = CacheMap.find(Offset);
if (CacheIter != CacheMap.end()) {
- // In a more general solution, we would need to guarantee that the
- // cached allocation is at least the requested size. In practice, since
- // these are CodeView / PDB records, we know they are always formatted
- // the same way and never change, so we should never be requesting two
- // allocations from the same address with different sizes.
- Buffer = ArrayRef<uint8_t>(CacheIter->second, Size);
+ // 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.
+ // 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 = Pool.Allocate<uint8_t>(Size);
-
if (auto EC = readBytes(Offset, MutableArrayRef<uint8_t>(WriteBuffer, Size)))
return EC;
- CacheMap.insert(std::make_pair(Offset, WriteBuffer));
+
+ 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) const {
+ // Make sure we aren't trying to read beyond the end of the stream.
+ if (Offset >= Data->getLength())
+ return make_error<RawError>(raw_error_code::insufficient_buffer);
+ uint32_t First = Offset / Pdb.getBlockSize();
+ uint32_t Last = First;
+
+ auto BlockList = Data->getStreamBlocks();
+ while (Last < Pdb.getBlockCount() - 1) {
+ if (BlockList[Last] != BlockList[Last + 1] - 1)
+ break;
+ ++Last;
+ }
+
+ uint32_t OffsetInFirstBlock = Offset % Pdb.getBlockSize();
+ uint32_t BytesFromFirstBlock = Pdb.getBlockSize() - OffsetInFirstBlock;
+ uint32_t BlockSpan = Last - First + 1;
+ uint32_t ByteSpan =
+ BytesFromFirstBlock + (BlockSpan - 1) * Pdb.getBlockSize();
+ Buffer = Pdb.getBlockData(BlockList[First], Pdb.getBlockSize());
+ Buffer = Buffer.drop_front(OffsetInFirstBlock);
+ Buffer = ArrayRef<uint8_t>(Buffer.data(), ByteSpan);
+ return Error::success();
+}
+
uint32_t MappedBlockStream::getLength() const { return Data->getLength(); }
bool MappedBlockStream::tryReadContiguously(uint32_t Offset, uint32_t Size,
@@ -130,7 +209,73 @@
}
return Error::success();
+}
+Error MappedBlockStream::writeBytes(uint32_t Offset,
+ ArrayRef<uint8_t> Buffer) const {
+ // Make sure we aren't trying to write beyond the end of the stream.
+ if (Buffer.size() > Data->getLength())
+ return make_error<RawError>(raw_error_code::insufficient_buffer);
+
+ if (Offset > Data->getLength() - Buffer.size())
+ return make_error<RawError>(raw_error_code::insufficient_buffer);
+
+ uint32_t BlockNum = Offset / Pdb.getBlockSize();
+ uint32_t OffsetInBlock = Offset % Pdb.getBlockSize();
+
+ uint32_t BytesLeft = Buffer.size();
+ auto BlockList = Data->getStreamBlocks();
+ uint32_t BytesWritten = 0;
+ while (BytesLeft > 0) {
+ uint32_t StreamBlockAddr = BlockList[BlockNum];
+ uint32_t BytesToWriteInChunk =
+ std::min(BytesLeft, Pdb.getBlockSize() - OffsetInBlock);
+
+ const uint8_t *Chunk = Buffer.data() + BytesWritten;
+ ArrayRef<uint8_t> ChunkData(Chunk, BytesToWriteInChunk);
+ if (auto EC = Pdb.setBlockData(StreamBlockAddr, OffsetInBlock, ChunkData))
+ return EC;
+
+ BytesLeft -= BytesToWriteInChunk;
+ BytesWritten += BytesToWriteInChunk;
+ ++BlockNum;
+ OffsetInBlock = 0;
+ }
+
+ // 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 + BytesWritten < 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 + BytesWritten);
+ 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, Buffer.data() + SrcOffset, Length);
+ }
+ }
+
+ return Error::success();
}
uint32_t MappedBlockStream::getNumBytesCopied() const {