DWARFDebugArangeSet.cpp

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//===-- DWARFDebugArangeSet.cpp -------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "DWARFDebugArangeSet.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
using namespace llvm;

void DWARFDebugArangeSet::clear() {
  Offset = -1U;
  std::memset(&HeaderData, 0, sizeof(Header));
  ArangeDescriptors.clear();
}

bool
DWARFDebugArangeSet::extract(DataExtractor data, uint32_t *offset_ptr) {
  if (data.isValidOffset(*offset_ptr)) {
    ArangeDescriptors.clear();
    Offset = *offset_ptr;

    // 7.20 Address Range Table
    //
    // Each set of entries in the table of address ranges contained in
    // the .debug_aranges section begins with a header consisting of: a
    // 4-byte length containing the length of the set of entries for this
    // compilation unit, not including the length field itself; a 2-byte
    // version identifier containing the value 2 for DWARF Version 2; a
    // 4-byte offset into the.debug_infosection; a 1-byte unsigned integer
    // containing the size in bytes of an address (or the offset portion of
    // an address for segmented addressing) on the target system; and a
    // 1-byte unsigned integer containing the size in bytes of a segment
    // descriptor on the target system. This header is followed by a series
    // of tuples. Each tuple consists of an address and a length, each in
    // the size appropriate for an address on the target architecture.
    HeaderData.Length = data.getU32(offset_ptr);
    HeaderData.Version = data.getU16(offset_ptr);
    HeaderData.CuOffset = data.getU32(offset_ptr);
    HeaderData.AddrSize = data.getU8(offset_ptr);
    HeaderData.SegSize = data.getU8(offset_ptr);

    // Perform basic validation of the header fields.
    if (!data.isValidOffsetForDataOfSize(Offset, HeaderData.Length) ||
        (HeaderData.AddrSize != 4 && HeaderData.AddrSize != 8)) {
      clear();
      return false;
    }

    // The first tuple following the header in each set begins at an offset
    // that is a multiple of the size of a single tuple (that is, twice the
    // size of an address). The header is padded, if necessary, to the
    // appropriate boundary.
    const uint32_t header_size = *offset_ptr - Offset;
    const uint32_t tuple_size = HeaderData.AddrSize * 2;
    uint32_t first_tuple_offset = 0;
    while (first_tuple_offset < header_size)
      first_tuple_offset += tuple_size;

    *offset_ptr = Offset + first_tuple_offset;

    Descriptor arangeDescriptor;

    static_assert(sizeof(arangeDescriptor.Address) ==
                      sizeof(arangeDescriptor.Length),
                  "Different datatypes for addresses and sizes!");
    assert(sizeof(arangeDescriptor.Address) >= HeaderData.AddrSize);

    while (data.isValidOffset(*offset_ptr)) {
      arangeDescriptor.Address = data.getUnsigned(offset_ptr, HeaderData.AddrSize);
      arangeDescriptor.Length = data.getUnsigned(offset_ptr, HeaderData.AddrSize);

      // Each set of tuples is terminated by a 0 for the address and 0
      // for the length.
      if (arangeDescriptor.Address || arangeDescriptor.Length)
        ArangeDescriptors.push_back(arangeDescriptor);
      else
        break; // We are done if we get a zero address and length
    }

    return !ArangeDescriptors.empty();
  }
  return false;
}

void DWARFDebugArangeSet::dump(raw_ostream &OS) const {
  OS << format("Address Range Header: length = 0x%8.8x, version = 0x%4.4x, ",
               HeaderData.Length, HeaderData.Version)
     << format("cu_offset = 0x%8.8x, addr_size = 0x%2.2x, seg_size = 0x%2.2x\n",
               HeaderData.CuOffset, HeaderData.AddrSize, HeaderData.SegSize);

  const uint32_t hex_width = HeaderData.AddrSize * 2;
  for (const auto &Desc : ArangeDescriptors) {
    OS << format("[0x%*.*" PRIx64 " -", hex_width, hex_width, Desc.Address)
       << format(" 0x%*.*" PRIx64 ")\n",
                 hex_width, hex_width, Desc.getEndAddress());
  }
}