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In order to efficiently write PDBs, we need to be able to make a StreamWriter class similar to a StreamReader, which can transparently deal with writing to discontiguous streams, and we need to use this for all writing, similar to how we use StreamReader for all reading. Most discontiguous streams are the typical numbered streams that appear in a PDB file and are described by the directory, but the exception to this, that until now has been parsed by hand, is the directory itself. MappedBlockStream works by querying the directory to find out which blocks a stream occupies and various other things, so naturally the same logic could not possibly work to describe the blocks that the directory itself resided on. To solve this, I've introduced an abstraction IPDBStreamData, which allows the client to query for the list of blocks occupied by the stream, as well as the stream length. I provide two implementations of this: one which queries the directory (for indexed streams), and one which queries the super block (for the directory stream). This has the side benefit of vastly simplifying the code to parse the directory. Whereas before a mini state machine was rolled by hand, now we simply use FixedStreamArray to read out the stream sizes, then build a vector of FixedStreamArrays for the stream map, all in just a few lines of code. Reviewed By: ruiu Differential Revision: http://reviews.llvm.org/D21046 llvm-svn: 271982
39 lines
1.4 KiB
C++
39 lines
1.4 KiB
C++
//===- IPDBStreamData.h - Base interface for PDB Stream Data ----*- 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_PDB_RAW_IPDBSTREAMDATA_H
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#define LLVM_DEBUGINFO_PDB_RAW_IPDBSTREAMDATA_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/Support/Endian.h"
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namespace llvm {
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namespace pdb {
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/// IPDBStream abstracts the notion of PDB stream data. Although we already
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/// have another stream abstraction (namely in the form of StreamInterface
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/// and MappedBlockStream), they assume that the stream data is referenced
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/// the same way. Namely, by looking in the directory to get the list of
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/// stream blocks, and by looking in the array of stream lengths to get the
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/// length. This breaks down for the directory itself, however, since its
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/// length and list of blocks are stored elsewhere. By abstracting the
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/// notion of stream data further, we can use a MappedBlockStream to read
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/// from the directory itself, or from an indexed stream which references
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/// the directory.
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class IPDBStreamData {
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public:
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virtual ~IPDBStreamData() {}
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virtual uint32_t getLength() = 0;
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virtual ArrayRef<support::ulittle32_t> getStreamBlocks() = 0;
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};
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}
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}
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#endif
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