llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp

   1 //===- DWARFLinkerCompileUnit.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/DWARFLinker/DWARFLinkerCompileUnit.h"
  10 #include "llvm/DWARFLinker/DWARFLinkerDeclContext.h"
  11
  12 namespace llvm {
  13
  14 /// Check if the DIE at \p Idx is in the scope of a function.
  15 static bool inFunctionScope(CompileUnit &U, unsigned Idx) {
  16   while (Idx) {
  17     if (U.getOrigUnit().getDIEAtIndex(Idx).getTag() == dwarf::DW_TAG_subprogram)
  18       return true;
  19     Idx = U.getInfo(Idx).ParentIdx;
  20   }
  21   return false;
  22 }
  23
  24 uint16_t CompileUnit::getLanguage() {
  25   if (!Language) {
  26     DWARFDie CU = getOrigUnit().getUnitDIE();
  27     Language = dwarf::toUnsigned(CU.find(dwarf::DW_AT_language), 0);
  28   }
  29   return Language;
  30 }
  31
  32 StringRef CompileUnit::getSysRoot() {
  33   if (SysRoot.empty()) {
  34     DWARFDie CU = getOrigUnit().getUnitDIE();
  35     SysRoot = dwarf::toStringRef(CU.find(dwarf::DW_AT_LLVM_sysroot)).str();
  36   }
  37   return SysRoot;
  38 }
  39
  40 void CompileUnit::markEverythingAsKept() {
  41   unsigned Idx = 0;
  42
  43   setHasInterestingContent();
  44
  45   for (auto &I : Info) {
  46     // Mark everything that wasn't explicit marked for pruning.
  47     I.Keep = !I.Prune;
  48     auto DIE = OrigUnit.getDIEAtIndex(Idx++);
  49
  50     // Try to guess which DIEs must go to the accelerator tables. We do that
  51     // just for variables, because functions will be handled depending on
  52     // whether they carry a DW_AT_low_pc attribute or not.
  53     if (DIE.getTag() != dwarf::DW_TAG_variable &&
  54         DIE.getTag() != dwarf::DW_TAG_constant)
  55       continue;
  56
  57     Optional<DWARFFormValue> Value;
  58     if (!(Value = DIE.find(dwarf::DW_AT_location))) {
  59       if ((Value = DIE.find(dwarf::DW_AT_const_value)) &&
  60           !inFunctionScope(*this, I.ParentIdx))
  61         I.InDebugMap = true;
  62       continue;
  63     }
  64     if (auto Block = Value->getAsBlock()) {
  65       if (Block->size() > OrigUnit.getAddressByteSize() &&
  66           (*Block)[0] == dwarf::DW_OP_addr)
  67         I.InDebugMap = true;
  68     }
  69   }
  70 }
  71
  72 uint64_t CompileUnit::computeNextUnitOffset(uint16_t DwarfVersion) {
  73   NextUnitOffset = StartOffset;
  74   if (NewUnit) {
  75     NextUnitOffset += (DwarfVersion >= 5) ? 12 : 11; // Header size
  76     NextUnitOffset += NewUnit->getUnitDie().getSize();
  77   }
  78   return NextUnitOffset;
  79 }
  80
  81 /// Keep track of a forward cross-cu reference from this unit
  82 /// to \p Die that lives in \p RefUnit.
  83 void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
  84                                        DeclContext *Ctxt, PatchLocation Attr) {
  85   ForwardDIEReferences.emplace_back(Die, RefUnit, Ctxt, Attr);
  86 }
  87
  88 void CompileUnit::fixupForwardReferences() {
  89   for (const auto &Ref : ForwardDIEReferences) {
  90     DIE *RefDie;
  91     const CompileUnit *RefUnit;
  92     PatchLocation Attr;
  93     DeclContext *Ctxt;
  94     std::tie(RefDie, RefUnit, Ctxt, Attr) = Ref;
  95     if (Ctxt && Ctxt->getCanonicalDIEOffset())
  96       Attr.set(Ctxt->getCanonicalDIEOffset());
  97     else
  98       Attr.set(RefDie->getOffset() + RefUnit->getStartOffset());
  99   }
 100 }
 101
 102 void CompileUnit::addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset) {
 103   Labels.insert({LabelLowPc, PcOffset});
 104 }
 105
 106 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
 107                                    int64_t PcOffset) {
 108   //  Don't add empty ranges to the interval map.  They are a problem because
 109   //  the interval map expects half open intervals. This is safe because they
 110   //  are empty anyway.
 111   if (FuncHighPc != FuncLowPc)
 112     Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
 113   this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
 114   this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
 115 }
 116
 117 void CompileUnit::noteRangeAttribute(const DIE &Die, PatchLocation Attr) {
 118   if (Die.getTag() != dwarf::DW_TAG_compile_unit)
 119     RangeAttributes.push_back(Attr);
 120   else
 121     UnitRangeAttribute = Attr;
 122 }
 123
 124 void CompileUnit::noteLocationAttribute(PatchLocation Attr, int64_t PcOffset) {
 125   LocationAttributes.emplace_back(Attr, PcOffset);
 126 }
 127
 128 void CompileUnit::addNamespaceAccelerator(const DIE *Die,
 129                                           DwarfStringPoolEntryRef Name) {
 130   Namespaces.emplace_back(Name, Die);
 131 }
 132
 133 void CompileUnit::addObjCAccelerator(const DIE *Die,
 134                                      DwarfStringPoolEntryRef Name,
 135                                      bool SkipPubSection) {
 136   ObjC.emplace_back(Name, Die, SkipPubSection);
 137 }
 138
 139 void CompileUnit::addNameAccelerator(const DIE *Die,
 140                                      DwarfStringPoolEntryRef Name,
 141                                      bool SkipPubSection) {
 142   Pubnames.emplace_back(Name, Die, SkipPubSection);
 143 }
 144
 145 void CompileUnit::addTypeAccelerator(const DIE *Die,
 146                                      DwarfStringPoolEntryRef Name,
 147                                      bool ObjcClassImplementation,
 148                                      uint32_t QualifiedNameHash) {
 149   Pubtypes.emplace_back(Name, Die, QualifiedNameHash, ObjcClassImplementation);
 150 }
 151
 152 } // namespace llvm