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Rewrite MCCAS Debug Info creation as iterative #8626

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Apr 25, 2024
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Rewrite MCCAS Debug Info creation as iterative #8626

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93 changes: 47 additions & 46 deletions llvm/lib/MCCAS/MCCASObjectV1.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2298,14 +2298,16 @@ struct DIEToCASConverter {
bool IsLittleEndian;
uint8_t AddressSize;

Error convertInNewDIEBlock(
DWARFDie DIE, DistinctDataWriter &DistinctWriter,
AbbrevSetWriter &AbbrevWriter,
SmallVectorImpl<std::unique_ptr<DIEDataWriter>> &DIEWriters);
struct ParentAndChildDIE {
DWARFDie Parent;
bool ParentAlreadyWritten;
DIEDataWriter &Writer;
std::optional<DWARFDie> Child;
};

Error
convertImpl(DWARFDie &DIE, DIEDataWriter &DIEWriter,
DistinctDataWriter &DistinctWriter, AbbrevSetWriter &AbbrevWriter,
convertImpl(DWARFDie DIE, DistinctDataWriter &DistinctWriter,
AbbrevSetWriter &AbbrevWriter,
SmallVectorImpl<std::unique_ptr<DIEDataWriter>> &DIEWriters);
};

Expand Down Expand Up @@ -3650,6 +3652,12 @@ static void writeDIEAttrs(DWARFDie &DIE, ArrayRef<char> DebugInfoData,
}
}

static void
pushNewDIEWriter(SmallVectorImpl<std::unique_ptr<DIEDataWriter>> &DIEWriters) {
auto DIEWriter = std::make_unique<DIEDataWriter>();
DIEWriters.push_back(std::move(DIEWriter));
}

/// Creates an abbreviation for DIE using AbbrevWriter.
/// Stores the contents of the DIE using DistinctWriter and DIEWriter following
/// the format:
Expand All @@ -3665,61 +3673,54 @@ static void writeDIEAttrs(DWARFDie &DIE, ArrayRef<char> DebugInfoData,
/// DIEAbbrevSetRef block. In this case, raw_data should be interpreted
/// according to the corresponding DIEAbbrevRefs block.
Error DIEToCASConverter::convertImpl(
DWARFDie &DIE, DIEDataWriter &DIEWriter, DistinctDataWriter &DistinctWriter,
DWARFDie DIE, DistinctDataWriter &DistinctWriter,
AbbrevSetWriter &AbbrevWriter,
SmallVectorImpl<std::unique_ptr<DIEDataWriter>> &DIEWriters) {
Expected<unsigned> MaybeAbbrevIndex =
AbbrevWriter.createAbbrevEntry(DIE, CASBuilder);
if (!MaybeAbbrevIndex)
return MaybeAbbrevIndex.takeError();

DistinctWriter.writeULEB128(encodeAbbrevIndex(*MaybeAbbrevIndex));
writeDIEAttrs(DIE, DebugInfoData, DIEWriter, DistinctWriter, IsLittleEndian,
AddressSize);

for (DWARFDie Child = DIE.getFirstChild(); Child;
Child = Child.getSibling()) {
dwarf::Tag ChildTag = Child.getTag();
if (ChildTag == dwarf::Tag::DW_TAG_null) {
DistinctWriter.writeULEB128(getEndOfDIESiblingsMarker());
break;
SmallVector<ParentAndChildDIE> DIEStack;
pushNewDIEWriter(DIEWriters);
DIEStack.push_back({DIE, false, *DIEWriters.back(), std::nullopt});
while (!DIEStack.empty()) {
auto ParentAndChild = DIEStack.pop_back_val();
DWARFDie CurrDIE = ParentAndChild.Parent;

if (!ParentAndChild.ParentAlreadyWritten) {
Expected<unsigned> MaybeAbbrevIndex =
AbbrevWriter.createAbbrevEntry(CurrDIE, CASBuilder);
if (!MaybeAbbrevIndex)
return MaybeAbbrevIndex.takeError();

DistinctWriter.writeULEB128(encodeAbbrevIndex(*MaybeAbbrevIndex));
writeDIEAttrs(CurrDIE, DebugInfoData, ParentAndChild.Writer,
DistinctWriter, IsLittleEndian, AddressSize);
}

// FIXME: don't use recursion.
if (shouldCreateSeparateBlockFor(Child)) {
DistinctWriter.writeULEB128(getDIEInAnotherBlockMarker());
if (auto E = convertInNewDIEBlock(Child, DistinctWriter, AbbrevWriter,
DIEWriters))
return E;
continue;
DWARFDie Child = ParentAndChild.Child ? ParentAndChild.Child->getSibling()
: CurrDIE.getFirstChild();
if (Child) {
dwarf::Tag ChildTag = Child.getTag();
if (ChildTag == dwarf::Tag::DW_TAG_null)
DistinctWriter.writeULEB128(getEndOfDIESiblingsMarker());
else if (shouldCreateSeparateBlockFor(Child)) {
DistinctWriter.writeULEB128(getDIEInAnotherBlockMarker());
DIEStack.push_back({CurrDIE, true, ParentAndChild.Writer, Child});
pushNewDIEWriter(DIEWriters);
DIEStack.push_back({Child, false, *DIEWriters.back(), std::nullopt});
} else {
DIEStack.push_back({CurrDIE, true, ParentAndChild.Writer, Child});
DIEStack.push_back({Child, false, ParentAndChild.Writer, std::nullopt});
}
}
if (auto E = convertImpl(Child, DIEWriter, DistinctWriter, AbbrevWriter,
DIEWriters))
return E;
}
return Error::success();
}

Error DIEToCASConverter::convertInNewDIEBlock(
DWARFDie DIE, DistinctDataWriter &DistinctWriter,
AbbrevSetWriter &AbbrevWriter,
SmallVectorImpl<std::unique_ptr<DIEDataWriter>> &DIEWriters) {
auto DIEWriter = std::make_unique<DIEDataWriter>();
DIEWriters.push_back(std::move(DIEWriter));
if (auto E = convertImpl(DIE, *DIEWriters.back(), DistinctWriter,
AbbrevWriter, DIEWriters))
return E;
return Error::success();
}

Expected<DIETopLevelRef>
DIEToCASConverter::convert(DWARFDie DIE, ArrayRef<char> HeaderData,
AbbrevSetWriter &AbbrevWriter) {
DistinctDataWriter DistinctWriter;
DistinctWriter.writeData(HeaderData);
SmallVector<std::unique_ptr<DIEDataWriter>> DIEWriters;
if (Error E =
convertInNewDIEBlock(DIE, DistinctWriter, AbbrevWriter, DIEWriters))
if (Error E = convertImpl(DIE, DistinctWriter, AbbrevWriter, DIEWriters))
return std::move(E);

Expected<DIEAbbrevSetRef> MaybeAbbrevSet =
Expand Down