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93e240a658
Summary: This patch adds support for ULEB128 and SLEB128 encoding and decoding to BinaryStreamWriter and BinaryStreamReader respectively. Support for ULEB128/SLEB128 will be used for eh-frame parsing in the JITLink library currently under development (see https://reviews.llvm.org/D58704). Reviewers: zturner, dblaikie Subscribers: kristina, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D60810 llvm-svn: 358584
104 lines
3.4 KiB
C++
104 lines
3.4 KiB
C++
//===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/BinaryStreamWriter.h"
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#include "llvm/Support/BinaryStreamError.h"
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#include "llvm/Support/BinaryStreamReader.h"
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#include "llvm/Support/BinaryStreamRef.h"
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#include "llvm/Support/LEB128.h"
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using namespace llvm;
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BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)
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: Stream(Ref) {}
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BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
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: Stream(Stream) {}
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BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
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llvm::support::endianness Endian)
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: Stream(Data, Endian) {}
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Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
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if (auto EC = Stream.writeBytes(Offset, Buffer))
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return EC;
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Offset += Buffer.size();
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return Error::success();
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}
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Error BinaryStreamWriter::writeULEB128(uint64_t Value) {
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uint8_t EncodedBytes[10] = {0};
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unsigned Size = encodeULEB128(Value, &EncodedBytes[0]);
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return writeBytes({EncodedBytes, Size});
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}
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Error BinaryStreamWriter::writeSLEB128(int64_t Value) {
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uint8_t EncodedBytes[10] = {0};
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unsigned Size = encodeSLEB128(Value, &EncodedBytes[0]);
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return writeBytes({EncodedBytes, Size});
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}
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Error BinaryStreamWriter::writeCString(StringRef Str) {
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if (auto EC = writeFixedString(Str))
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return EC;
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if (auto EC = writeObject('\0'))
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return EC;
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return Error::success();
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}
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Error BinaryStreamWriter::writeFixedString(StringRef Str) {
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return writeBytes(arrayRefFromStringRef(Str));
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}
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Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
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return writeStreamRef(Ref, Ref.getLength());
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}
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Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
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BinaryStreamReader SrcReader(Ref.slice(0, Length));
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// This is a bit tricky. If we just call readBytes, we are requiring that it
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// return us the entire stream as a contiguous buffer. There is no guarantee
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// this can be satisfied by returning a reference straight from the buffer, as
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// an implementation may not store all data in a single contiguous buffer. So
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// we iterate over each contiguous chunk, writing each one in succession.
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while (SrcReader.bytesRemaining() > 0) {
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ArrayRef<uint8_t> Chunk;
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if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
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return EC;
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if (auto EC = writeBytes(Chunk))
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return EC;
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}
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return Error::success();
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}
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std::pair<BinaryStreamWriter, BinaryStreamWriter>
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BinaryStreamWriter::split(uint32_t Off) const {
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assert(getLength() >= Off);
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WritableBinaryStreamRef First = Stream.drop_front(Offset);
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WritableBinaryStreamRef Second = First.drop_front(Off);
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First = First.keep_front(Off);
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BinaryStreamWriter W1{First};
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BinaryStreamWriter W2{Second};
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return std::make_pair(W1, W2);
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}
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Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
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uint32_t NewOffset = alignTo(Offset, Align);
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if (NewOffset > getLength())
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return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
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while (Offset < NewOffset)
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if (auto EC = writeInteger('\0'))
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return EC;
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return Error::success();
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}
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