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Diffstat (limited to 'contrib/llvm-project/llvm/lib/DebugInfo/CodeView/ContinuationRecordBuilder.cpp')
| -rw-r--r-- | contrib/llvm-project/llvm/lib/DebugInfo/CodeView/ContinuationRecordBuilder.cpp | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/DebugInfo/CodeView/ContinuationRecordBuilder.cpp b/contrib/llvm-project/llvm/lib/DebugInfo/CodeView/ContinuationRecordBuilder.cpp new file mode 100644 index 000000000000..799cffb7116e --- /dev/null +++ b/contrib/llvm-project/llvm/lib/DebugInfo/CodeView/ContinuationRecordBuilder.cpp @@ -0,0 +1,251 @@ +#include "llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h" + +using namespace llvm; +using namespace llvm::codeview; + +namespace { +struct ContinuationRecord { + ulittle16_t Kind{uint16_t(TypeLeafKind::LF_INDEX)}; + ulittle16_t Size{0}; + ulittle32_t IndexRef{0xB0C0B0C0}; +}; + +struct SegmentInjection { + SegmentInjection(TypeLeafKind Kind) { Prefix.RecordKind = Kind; } + + ContinuationRecord Cont; + RecordPrefix Prefix; +}; +} // namespace + +static void addPadding(BinaryStreamWriter &Writer) { + uint32_t Align = Writer.getOffset() % 4; + if (Align == 0) + return; + + int PaddingBytes = 4 - Align; + while (PaddingBytes > 0) { + uint8_t Pad = static_cast<uint8_t>(LF_PAD0 + PaddingBytes); + cantFail(Writer.writeInteger(Pad)); + --PaddingBytes; + } +} + +static SegmentInjection InjectFieldList(TypeLeafKind::LF_FIELDLIST); +static SegmentInjection InjectMethodOverloadList(TypeLeafKind::LF_METHODLIST); + +static constexpr uint32_t ContinuationLength = sizeof(ContinuationRecord); +static constexpr uint32_t MaxSegmentLength = + MaxRecordLength - ContinuationLength; + +static inline TypeLeafKind getTypeLeafKind(ContinuationRecordKind CK) { + return (CK == ContinuationRecordKind::FieldList) ? LF_FIELDLIST + : LF_METHODLIST; +} + +ContinuationRecordBuilder::ContinuationRecordBuilder() + : SegmentWriter(Buffer), Mapping(SegmentWriter) {} + +ContinuationRecordBuilder::~ContinuationRecordBuilder() {} + +void ContinuationRecordBuilder::begin(ContinuationRecordKind RecordKind) { + assert(!Kind.hasValue()); + Kind = RecordKind; + Buffer.clear(); + SegmentWriter.setOffset(0); + SegmentOffsets.clear(); + SegmentOffsets.push_back(0); + assert(SegmentWriter.getOffset() == 0); + assert(SegmentWriter.getLength() == 0); + + const SegmentInjection *FLI = + (RecordKind == ContinuationRecordKind::FieldList) + ? &InjectFieldList + : &InjectMethodOverloadList; + const uint8_t *FLIB = reinterpret_cast<const uint8_t *>(FLI); + InjectedSegmentBytes = + ArrayRef<uint8_t>(FLIB, FLIB + sizeof(SegmentInjection)); + + // Seed the first record with an appropriate record prefix. + RecordPrefix Prefix(getTypeLeafKind(RecordKind)); + CVType Type(&Prefix, sizeof(Prefix)); + cantFail(Mapping.visitTypeBegin(Type)); + + cantFail(SegmentWriter.writeObject(Prefix)); +} + +template <typename RecordType> +void ContinuationRecordBuilder::writeMemberType(RecordType &Record) { + assert(Kind.hasValue()); + + uint32_t OriginalOffset = SegmentWriter.getOffset(); + CVMemberRecord CVMR; + CVMR.Kind = static_cast<TypeLeafKind>(Record.getKind()); + + // Member Records aren't length-prefixed, they only have a 2-byte TypeLeafKind + // at the beginning. + cantFail(SegmentWriter.writeEnum(CVMR.Kind)); + + // Let the Mapping handle the rest. + cantFail(Mapping.visitMemberBegin(CVMR)); + cantFail(Mapping.visitKnownMember(CVMR, Record)); + cantFail(Mapping.visitMemberEnd(CVMR)); + + // Make sure it's padded to 4 bytes. + addPadding(SegmentWriter); + assert(getCurrentSegmentLength() % 4 == 0); + + // The maximum length of a single segment is 64KB minus the size to insert a + // continuation. So if we are over that, inject a continuation between the + // previous member and the member that was just written, then end the previous + // segment after the continuation and begin a new one with the just-written + // member. + if (getCurrentSegmentLength() > MaxSegmentLength) { + // We need to inject some bytes before the member we just wrote but after + // the previous member. Save off the length of the member we just wrote so + // that we can do some sanity checking on it. + uint32_t MemberLength = SegmentWriter.getOffset() - OriginalOffset; + (void) MemberLength; + insertSegmentEnd(OriginalOffset); + // Since this member now becomes a new top-level record, it should have + // gotten a RecordPrefix injected, and that RecordPrefix + the member we + // just wrote should now constitute the entirety of the current "new" + // segment. + assert(getCurrentSegmentLength() == MemberLength + sizeof(RecordPrefix)); + } + + assert(getCurrentSegmentLength() % 4 == 0); + assert(getCurrentSegmentLength() <= MaxSegmentLength); +} + +uint32_t ContinuationRecordBuilder::getCurrentSegmentLength() const { + return SegmentWriter.getOffset() - SegmentOffsets.back(); +} + +void ContinuationRecordBuilder::insertSegmentEnd(uint32_t Offset) { + uint32_t SegmentBegin = SegmentOffsets.back(); + (void)SegmentBegin; + assert(Offset > SegmentBegin); + assert(Offset - SegmentBegin <= MaxSegmentLength); + + // We need to make space for the continuation record. For now we can't fill + // out the length or the TypeIndex of the back-reference, but we need the + // space to at least be there. + Buffer.insert(Offset, InjectedSegmentBytes); + + uint32_t NewSegmentBegin = Offset + ContinuationLength; + uint32_t SegmentLength = NewSegmentBegin - SegmentOffsets.back(); + (void) SegmentLength; + + assert(SegmentLength % 4 == 0); + assert(SegmentLength <= MaxRecordLength); + SegmentOffsets.push_back(NewSegmentBegin); + + // Seek to the end so that we can keep writing against the new segment. + SegmentWriter.setOffset(SegmentWriter.getLength()); + assert(SegmentWriter.bytesRemaining() == 0); +} + +CVType ContinuationRecordBuilder::createSegmentRecord( + uint32_t OffBegin, uint32_t OffEnd, Optional<TypeIndex> RefersTo) { + assert(OffEnd - OffBegin <= USHRT_MAX); + + MutableArrayRef<uint8_t> Data = Buffer.data(); + Data = Data.slice(OffBegin, OffEnd - OffBegin); + + // Write the length to the RecordPrefix, making sure it does not include + // sizeof(RecordPrefix.Length) + RecordPrefix *Prefix = reinterpret_cast<RecordPrefix *>(Data.data()); + Prefix->RecordLen = Data.size() - sizeof(RecordPrefix::RecordLen); + + if (RefersTo.hasValue()) { + auto Continuation = Data.take_back(ContinuationLength); + ContinuationRecord *CR = + reinterpret_cast<ContinuationRecord *>(Continuation.data()); + assert(CR->Kind == TypeLeafKind::LF_INDEX); + assert(CR->IndexRef == 0xB0C0B0C0); + CR->IndexRef = RefersTo->getIndex(); + } + + return CVType(Data); +} + +std::vector<CVType> ContinuationRecordBuilder::end(TypeIndex Index) { + RecordPrefix Prefix(getTypeLeafKind(*Kind)); + CVType Type(&Prefix, sizeof(Prefix)); + cantFail(Mapping.visitTypeEnd(Type)); + + // We're now done, and we have a series of segments each beginning at an + // offset specified in the SegmentOffsets array. We now need to iterate + // over each segment and post-process them in the following two ways: + // 1) Each top-level record has a RecordPrefix whose type is either + // LF_FIELDLIST or LF_METHODLIST, but the Length field is still 0. + // Those should all be set to the correct length now. + // 2) Each continuation record has an IndexRef field which we set to the + // magic value 0xB0C0B0C0. Now that the caller has told us the TypeIndex + // they want this sequence to start from, we can go through and update + // each one. + // + // Logically, the sequence of records we've built up looks like this: + // + // SegmentOffsets[0]: <Length> (Initially: uninitialized) + // SegmentOffsets[0]+2: LF_FIELDLIST + // SegmentOffsets[0]+4: Member[0] + // SegmentOffsets[0]+?: ... + // SegmentOffsets[0]+?: Member[4] + // SegmentOffsets[1]-8: LF_INDEX + // SegmentOffsets[1]-6: 0 + // SegmentOffsets[1]-4: <Type Index of Next Record> (Initially: 0xB0C0B0C0) + // + // SegmentOffsets[1]: <Length> (Initially: uninitialized) + // SegmentOffsets[1]+2: LF_FIELDLIST + // SegmentOffsets[1]+4: Member[0] + // SegmentOffsets[1]+?: ... + // SegmentOffsets[1]+?: Member[s] + // SegmentOffsets[2]-8: LF_INDEX + // SegmentOffsets[2]-6: 0 + // SegmentOffsets[2]-4: <Type Index of Next Record> (Initially: 0xB0C0B0C0) + // + // ... + // + // SegmentOffsets[N]: <Length> (Initially: uninitialized) + // SegmentOffsets[N]+2: LF_FIELDLIST + // SegmentOffsets[N]+4: Member[0] + // SegmentOffsets[N]+?: ... + // SegmentOffsets[N]+?: Member[t] + // + // And this is the way we have laid them out in the serialization buffer. But + // we cannot actually commit them to the underlying stream this way, due to + // the topological sorting requirement of a type stream (specifically, + // TypeIndex references can only point backwards, not forwards). So the + // sequence that we return to the caller contains the records in reverse + // order, which is the proper order for committing the serialized records. + + std::vector<CVType> Types; + Types.reserve(SegmentOffsets.size()); + + auto SO = makeArrayRef(SegmentOffsets); + + uint32_t End = SegmentWriter.getOffset(); + + Optional<TypeIndex> RefersTo; + for (uint32_t Offset : reverse(SO)) { + Types.push_back(createSegmentRecord(Offset, End, RefersTo)); + + End = Offset; + RefersTo = Index++; + } + + Kind.reset(); + return Types; +} + +// Explicitly instantiate the member function for each known type so that we can +// implement this in the cpp file. +#define TYPE_RECORD(EnumName, EnumVal, Name) +#define TYPE_RECORD_ALIAS(EnumName, EnumVal, Name, AliasName) +#define MEMBER_RECORD(EnumName, EnumVal, Name) \ + template void llvm::codeview::ContinuationRecordBuilder::writeMemberType( \ + Name##Record &Record); +#define MEMBER_RECORD_ALIAS(EnumName, EnumVal, Name, AliasName) +#include "llvm/DebugInfo/CodeView/CodeViewTypes.def" |