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0212bc82e0
PDBs can be extremely large. We're already mapping the entire PDB into the process's address space, but to make matters worse the blocks of the PDB are not arranged contiguously. So, when we have something like an array or a string embedded into the stream, we have to make a copy. Since it's convenient to use traditional data structures to iterate and manipulate these records, we need the memory to be contiguous. As a result of this, we were using roughly twice as much memory as the file size of the PDB, because every stream was copied out and re-stitched together contiguously. This patch addresses this by improving the MappedBlockStream to allocate from a BumpPtrAllocator only when a read requires a discontiguous read. Furthermore, it introduces some data structures backed by a stream which can iterate over both fixed and variable length records of a PDB. Since everything is backed by a stream and not a buffer, we can read almost everything from the PDB with zero copies. Differential Revision: http://reviews.llvm.org/D20654 Reviewed By: ruiu git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270951 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.4 KiB
C++
54 lines
1.4 KiB
C++
//===- ByteStream.h - Reads stream data from a byte sequence ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_DEBUGINFO_CODEVIEW_BYTESTREAM_H
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#define LLVM_DEBUGINFO_CODEVIEW_BYTESTREAM_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/DebugInfo/CodeView/StreamInterface.h"
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#include "llvm/Support/Error.h"
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#include <cstdint>
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#include <memory>
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namespace llvm {
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namespace codeview {
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class StreamReader;
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class ByteStream : public StreamInterface {
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public:
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ByteStream();
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explicit ByteStream(MutableArrayRef<uint8_t> Data);
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~ByteStream() override;
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void reset();
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void load(uint32_t Length);
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Error load(StreamReader &Reader, uint32_t Length);
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Error readBytes(uint32_t Offset,
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MutableArrayRef<uint8_t> Buffer) const override;
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Error readBytes(uint32_t Offset, uint32_t Size,
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ArrayRef<uint8_t> &Buffer) const override;
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uint32_t getLength() const override;
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ArrayRef<uint8_t> data() const { return Data; }
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StringRef str() const;
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private:
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MutableArrayRef<uint8_t> Data;
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std::unique_ptr<uint8_t[]> Ownership;
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};
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} // end namespace pdb
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} // end namespace llvm
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#endif // LLVM_DEBUGINFO_CODEVIEW_BYTESTREAM_H
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