lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp

   1 //===- DWARFDebugInfoEntry.cpp --------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
  10 #include "llvm/ADT/Optional.h"
  11 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
  12 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
  13 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
  14 #include "llvm/Support/DataExtractor.h"
  15 #include <cstddef>
  16 #include <cstdint>
  17
  18 using namespace llvm;
  19 using namespace dwarf;
  20
  21 bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U,
  22                                              uint64_t *OffsetPtr) {
  23   DWARFDataExtractor DebugInfoData = U.getDebugInfoExtractor();
  24   const uint64_t UEndOffset = U.getNextUnitOffset();
  25   return extractFast(U, OffsetPtr, DebugInfoData, UEndOffset, 0);
  26 }
  27
  28 bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint64_t *OffsetPtr,
  29                                       const DWARFDataExtractor &DebugInfoData,
  30                                       uint64_t UEndOffset, uint32_t D) {
  31   Offset = *OffsetPtr;
  32   Depth = D;
  33   if (Offset >= UEndOffset || !DebugInfoData.isValidOffset(Offset))
  34     return false;
  35   uint64_t AbbrCode = DebugInfoData.getULEB128(OffsetPtr);
  36   if (0 == AbbrCode) {
  37     // NULL debug tag entry.
  38     AbbrevDecl = nullptr;
  39     return true;
  40   }
  41   AbbrevDecl = U.getAbbreviations()->getAbbreviationDeclaration(AbbrCode);
  42   if (nullptr == AbbrevDecl) {
  43     // Restore the original offset.
  44     *OffsetPtr = Offset;
  45     return false;
  46   }
  47   // See if all attributes in this DIE have fixed byte sizes. If so, we can
  48   // just add this size to the offset to skip to the next DIE.
  49   if (Optional<size_t> FixedSize = AbbrevDecl->getFixedAttributesByteSize(U)) {
  50     *OffsetPtr += *FixedSize;
  51     return true;
  52   }
  53
  54   // Skip all data in the .debug_info for the attributes
  55   for (const auto &AttrSpec : AbbrevDecl->attributes()) {
  56     // Check if this attribute has a fixed byte size.
  57     if (auto FixedSize = AttrSpec.getByteSize(U)) {
  58       // Attribute byte size if fixed, just add the size to the offset.
  59       *OffsetPtr += *FixedSize;
  60     } else if (!DWARFFormValue::skipValue(AttrSpec.Form, DebugInfoData,
  61                                           OffsetPtr, U.getFormParams())) {
  62       // We failed to skip this attribute's value, restore the original offset
  63       // and return the failure status.
  64       *OffsetPtr = Offset;
  65       return false;
  66     }
  67   }
  68   return true;
  69 }