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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
82 lines
2.5 KiB
C++
82 lines
2.5 KiB
C++
//===- StreamReader.h - Reads bytes and objects from a stream ---*- 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_STREAMREADER_H
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#define LLVM_DEBUGINFO_CODEVIEW_STREAMREADER_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/DebugInfo/CodeView/CodeViewError.h"
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#include "llvm/DebugInfo/CodeView/StreamArray.h"
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#include "llvm/DebugInfo/CodeView/StreamInterface.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Error.h"
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#include <string>
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namespace llvm {
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namespace codeview {
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class StreamRef;
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class StreamReader {
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public:
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StreamReader(const StreamInterface &S);
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Error readBytes(uint32_t Size, ArrayRef<uint8_t> &Buffer);
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Error readBytes(MutableArrayRef<uint8_t> Buffer);
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Error readInteger(uint16_t &Dest);
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Error readInteger(uint32_t &Dest);
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Error readZeroString(StringRef &Dest);
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Error readFixedString(StringRef &Dest, uint32_t Length);
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Error readStreamRef(StreamRef &Ref);
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Error readStreamRef(StreamRef &Ref, uint32_t Length);
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template <typename T> Error readObject(const T *&Dest) {
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ArrayRef<uint8_t> Buffer;
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if (auto EC = readBytes(sizeof(T), Buffer))
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return EC;
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Dest = reinterpret_cast<const T *>(Buffer.data());
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return Error::success();
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}
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template <typename T>
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Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) {
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if (NumItems == 0) {
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Array = FixedStreamArray<T>();
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return Error::success();
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}
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uint32_t Length = NumItems * sizeof(T);
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if (Offset + Length > Stream.getLength())
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return make_error<CodeViewError>(cv_error_code::insufficient_buffer);
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StreamRef View(Stream, Offset, Length);
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Array = FixedStreamArray<T>(View);
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Offset += Length;
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return Error::success();
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}
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template <typename T> Error readArray(MutableArrayRef<T> Array) {
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MutableArrayRef<uint8_t> Casted(reinterpret_cast<uint8_t *>(Array.data()),
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Array.size() * sizeof(T));
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return readBytes(Casted);
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}
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void setOffset(uint32_t Off) { Offset = Off; }
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uint32_t getOffset() const { return Offset; }
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uint32_t getLength() const { return Stream.getLength(); }
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uint32_t bytesRemaining() const { return getLength() - getOffset(); }
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private:
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const StreamInterface &Stream;
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uint32_t Offset;
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};
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} // namespace codeview
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} // namespace llvm
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#endif // LLVM_DEBUGINFO_CODEVIEW_STREAMREADER_H
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