FileWriter.cpp

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//===- FileWriter.cpp -------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "llvm/DebugInfo/GSYM/FileWriter.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
 
using namespace llvm;
using namespace gsym;
 
FileWriter::~FileWriter() { OS.flush(); }
 
void FileWriter::writeSLEB(int64_t S) {
  uint8_t Bytes[32];
  auto Length = encodeSLEB128(S, Bytes);
  assert(Length < sizeof(Bytes));
  OS.write(reinterpret_cast<const char *>(Bytes), Length);
}
 
void FileWriter::writeULEB(uint64_t U) {
  uint8_t Bytes[32];
  auto Length = encodeULEB128(U, Bytes);
  assert(Length < sizeof(Bytes));
  OS.write(reinterpret_cast<const char *>(Bytes), Length);
}
 
void FileWriter::writeU8(uint8_t U) {
  OS.write(reinterpret_cast<const char *>(&U), sizeof(U));
}
 
void FileWriter::writeU16(uint16_t U) {
  const uint16_t Swapped = support::endian::byte_swap(U, ByteOrder);
  OS.write(reinterpret_cast<const char *>(&Swapped), sizeof(Swapped));
}
 
void FileWriter::writeU32(uint32_t U) {
  const uint32_t Swapped = support::endian::byte_swap(U, ByteOrder);
  OS.write(reinterpret_cast<const char *>(&Swapped), sizeof(Swapped));
}
 
void FileWriter::writeU64(uint64_t U) {
  const uint64_t Swapped = support::endian::byte_swap(U, ByteOrder);
  OS.write(reinterpret_cast<const char *>(&Swapped), sizeof(Swapped));
}
 
void FileWriter::writeUnsigned(uint64_t Value, size_t ByteSize) {
  assert(ByteSize <= 8 && "invalid byte size");
  // Make sure the value fits in the number of bytes specified.
  assert((ByteSize == 8 || (Value & (uint64_t)-1 << (8 * ByteSize)) == 0) &&
         "potential data loss: higher bits are non-zero");
  // Swap and shift bytes if endianness doesn't match.
  if (ByteOrder != llvm::endianness::native) {
    // Say ByteSize is 3.
    //                high                low
    // Input bytes:   00 00 00 00 00 AA BB CC
    // Swapped bytes: CC BB AA 00 00 00 00 00
    // Shifted bytes: 00 00 00 00 00 CC BB AA
    Value = sys::getSwappedBytes(Value) >> (8 * (8 - ByteSize));
  }
  OS.write(reinterpret_cast<const char *>(&Value), ByteSize);
}
 
void FileWriter::fixup32(uint32_t U, uint64_t Offset) {
  const uint32_t Swapped = support::endian::byte_swap(U, ByteOrder);
  OS.pwrite(reinterpret_cast<const char *>(&Swapped), sizeof(Swapped),
            Offset);
}
 
void FileWriter::writeData(llvm::ArrayRef<uint8_t> Data) {
  OS.write(reinterpret_cast<const char *>(Data.data()), Data.size());
}
 
void FileWriter::writeNullTerminated(llvm::StringRef Str) {
  OS << Str << '\0';
}
 
uint64_t FileWriter::tell() {
  return OS.tell();
}
 
void FileWriter::alignTo(size_t Align) {
  off_t Offset = OS.tell();
  off_t AlignedOffset = (Offset + Align - 1) / Align * Align;
  if (AlignedOffset == Offset)
    return;
  off_t PadCount = AlignedOffset - Offset;
  OS.write_zeros(PadCount);
}