Commit 77cfcd75 authored by David Blaikie's avatar David Blaikie
Browse files

DebugInfo: Use loclistx for DWARFv5 location lists to reduce the number of relocations 

This only implements the non-dwo part, but loclistx is necessary to use
location lists in DWARFv5, so it's a precursor to that work - and
generally reduces relocations (only using one reloc, then
indexes/relative offsets for all location list references) in non-split
DWARF.
parent 97c742e6

llvm/include/llvm/DebugInfo/DWARF/DWARFDie.h

+1 −0
Original line number Diff line number Diff line
@@ -188,6 +188,7 @@ public: 
  ///

  /// \returns anm optional absolute section offset value for the attribute.

  Optional<uint64_t> getRangesBaseAttribute() const;

  Optional<uint64_t> getLocBaseAttribute() const;



  /// Get the DW_AT_high_pc attribute value as an address.

  ///

llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h

+16 −0
Original line number Diff line number Diff line
@@ -200,6 +200,8 @@ class DWARFUnit { 
  const DWARFDebugAbbrev *Abbrev;

  const DWARFSection *RangeSection;

  uint64_t RangeSectionBase;

  const DWARFSection *LocSection;

  uint64_t LocSectionBase;



  /// Location table of this unit.

  std::unique_ptr<DWARFLocationTable> LocTable;
@@ -219,6 +221,7 @@ class DWARFUnit { 


  /// A table of range lists (DWARF v5 and later).

  Optional<DWARFDebugRnglistTable> RngListTable;

  Optional<DWARFListTableHeader> LoclistTableHeader;



  mutable const DWARFAbbreviationDeclarationSet *Abbrevs;

  llvm::Optional<object::SectionedAddress> BaseAddr;
@@ -305,6 +308,14 @@ public: 
    RangeSection = RS;

    RangeSectionBase = Base;

  }

  void setLocSection(const DWARFSection *LS, uint64_t Base) {

    LocSection = LS;

    LocSectionBase = Base;

  }



  uint64_t getLocSectionBase() const {

    return LocSectionBase;

  }



  Optional<object::SectionedAddress>

  getAddrOffsetSectionItem(uint32_t Index) const;
@@ -421,6 +432,11 @@ public: 
    return None;

  }



  Optional<uint64_t> getLoclistOffset(uint32_t Index) {

    if (LoclistTableHeader)

      return LoclistTableHeader->getOffsetEntry(Index);

    return None;

  }

  Expected<DWARFAddressRangesVector> collectAddressRanges();



  /// Returns subprogram DIE with address range encompassing the provided

llvm/lib/CodeGen/AsmPrinter/DIE.cpp

+6 −0
Original line number Diff line number Diff line
@@ -798,6 +798,8 @@ void DIEBlock::print(raw_ostream &O) const { 
//===----------------------------------------------------------------------===//



unsigned DIELocList::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {

  if (Form == dwarf::DW_FORM_loclistx)

    return getULEB128Size(Index);

  if (Form == dwarf::DW_FORM_data4)

    return 4;

  if (Form == dwarf::DW_FORM_sec_offset)
@@ -808,6 +810,10 @@ unsigned DIELocList::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const { 
/// EmitValue - Emit label value.

///

void DIELocList::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {

  if (Form == dwarf::DW_FORM_loclistx) {

    AP->EmitULEB128(Index);

    return;

  }

  DwarfDebug *DD = AP->getDwarfDebug();

  MCSymbol *Label = DD->getDebugLocs().getList(Index).Label;

  AP->emitDwarfSymbolReference(Label, /*ForceOffset*/ DD->useSplitDwarf());

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

+5 −2
Original line number Diff line number Diff line
@@ -1220,8 +1220,11 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die, 
/// Add a Dwarf loclistptr attribute data and value.

void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,

                                       unsigned Index) {

  dwarf::Form Form = DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset

                                                : dwarf::DW_FORM_data4;

  dwarf::Form Form = dwarf::DW_FORM_data4;

  if (DD->getDwarfVersion() == 4)

    Form =dwarf::DW_FORM_sec_offset;

  if (DD->getDwarfVersion() >= 5)

    Form =dwarf::DW_FORM_loclistx;

  Die.addValue(DIEValueAllocator, Attribute, Form, DIELocList(Index));

}

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

+4 −1
Original line number Diff line number Diff line
@@ -2323,9 +2323,12 @@ static MCSymbol *emitLoclistsTableHeader(AsmPrinter *Asm, 
  // FIXME: Generate the offsets table and use DW_FORM_loclistx with the

  // DW_AT_loclists_base attribute. Until then set the number of offsets to 0.

  Asm->OutStreamer->AddComment("Offset entry count");

  Asm->emitInt32(0);

  Asm->emitInt32(DebugLocs.getLists().size());

  Asm->OutStreamer->EmitLabel(DebugLocs.getSym());



  for (const auto &List : DebugLocs.getLists())

    Asm->EmitLabelDifference(List.Label, DebugLocs.getSym(), 4);



  return TableEnd;

}