lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp

   1 //===- DWARFDebugInfoEntry.cpp --------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
  11 #include "llvm/ADT/Optional.h"
  12 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
  13 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
  14 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
  15 #include "llvm/Support/DataExtractor.h"
  16 #include <cstddef>
  17 #include <cstdint>
  18
  19 using namespace llvm;
  20 using namespace dwarf;
  21
  22 bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U,
  23                                              uint32_t *OffsetPtr) {
  24   DWARFDataExtractor DebugInfoData = U.getDebugInfoExtractor();
  25   const uint32_t UEndOffset = U.getNextUnitOffset();
  26   return extractFast(U, OffsetPtr, DebugInfoData, UEndOffset, 0);
  27 }
  28
  29 bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint32_t *OffsetPtr,
  30                                       const DWARFDataExtractor &DebugInfoData,
  31                                       uint32_t UEndOffset, uint32_t D) {
  32   Offset = *OffsetPtr;
  33   Depth = D;
  34   if (Offset >= UEndOffset || !DebugInfoData.isValidOffset(Offset))
  35     return false;
  36   uint64_t AbbrCode = DebugInfoData.getULEB128(OffsetPtr);
  37   if (0 == AbbrCode) {
  38     // NULL debug tag entry.
  39     AbbrevDecl = nullptr;
  40     return true;
  41   }
  42   AbbrevDecl = U.getAbbreviations()->getAbbreviationDeclaration(AbbrCode);
  43   if (nullptr == AbbrevDecl) {
  44     // Restore the original offset.
  45     *OffsetPtr = Offset;
  46     return false;
  47   }
  48   // See if all attributes in this DIE have fixed byte sizes. If so, we can
  49   // just add this size to the offset to skip to the next DIE.
  50   if (Optional<size_t> FixedSize = AbbrevDecl->getFixedAttributesByteSize(U)) {
  51     *OffsetPtr += *FixedSize;
  52     return true;
  53   }
  54
  55   // Skip all data in the .debug_info for the attributes
  56   for (const auto &AttrSpec : AbbrevDecl->attributes()) {
  57     // Check if this attribute has a fixed byte size.
  58     if (auto FixedSize = AttrSpec.getByteSize(U)) {
  59       // Attribute byte size if fixed, just add the size to the offset.
  60       *OffsetPtr += *FixedSize;
  61     } else if (!DWARFFormValue::skipValue(AttrSpec.Form, DebugInfoData,
  62                                           OffsetPtr, U.getFormParams())) {
  63       // We failed to skip this attribute's value, restore the original offset
  64       // and return the failure status.
  65       *OffsetPtr = Offset;
  66       return false;
  67     }
  68   }
  69   return true;
  70 }