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[Bitcode] Improve support for opaque-pointer bitcode upgrade
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This is step two of supporting autoupgrade of old bitcode to opaque
pointers. Rather than tracking the element type ID of pointers in
particular, track all type IDs that a type contains. This allows us
to recover the element type in more complex situations, e.g. when
we need to determine the pointer element type of a vector element
or function type parameter.

Differential Revision: https://reviews.llvm.org/D119339
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@nikic
nikic committed Feb 15, 2022
1 parent 32389d0 commit 1c456a8
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Showing 2 changed files with 56 additions and 20 deletions.
73 changes: 54 additions & 19 deletions llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View file
Expand Up @@ -484,9 +484,10 @@ class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
std::vector<std::string> GCTable;

std::vector<Type *> TypeList;
/// Stores pointer element type for a given type ID. This is used during
/// upgrades of typed pointer IR in opaque pointer mode.
std::vector<Type *> ElementTypeList;
/// Track type IDs of contained types. Order is the same as the contained
/// types of a Type*. This is used during upgrades of typed pointer IR in
/// opaque pointer mode.
DenseMap<unsigned, SmallVector<unsigned, 1>> ContainedTypeIDs;
DenseMap<Function *, FunctionType *> FunctionTypes;
BitcodeReaderValueList ValueList;
Optional<MetadataLoader> MDLoader;
Expand Down Expand Up @@ -593,8 +594,11 @@ class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
StructType *createIdentifiedStructType(LLVMContext &Context, StringRef Name);
StructType *createIdentifiedStructType(LLVMContext &Context);

static constexpr unsigned InvalidTypeID = ~0u;

Type *getTypeByID(unsigned ID);
Type *getPtrElementTypeByID(unsigned ID);
unsigned getContainedTypeID(unsigned ID, unsigned Idx);

Value *getFnValueByID(unsigned ID, Type *Ty) {
if (Ty && Ty->isMetadataTy())
Expand Down Expand Up @@ -1180,6 +1184,17 @@ Type *BitcodeReader::getTypeByID(unsigned ID) {
return TypeList[ID] = createIdentifiedStructType(Context);
}

unsigned BitcodeReader::getContainedTypeID(unsigned ID, unsigned Idx) {
auto It = ContainedTypeIDs.find(ID);
if (It == ContainedTypeIDs.end())
return InvalidTypeID;

if (Idx >= It->second.size())
return InvalidTypeID;

return It->second[Idx];
}

Type *BitcodeReader::getPtrElementTypeByID(unsigned ID) {
if (ID >= TypeList.size())
return nullptr;
Expand All @@ -1188,7 +1203,7 @@ Type *BitcodeReader::getPtrElementTypeByID(unsigned ID) {
if (!Ty->isPointerTy())
return nullptr;

Type *ElemTy = ElementTypeList[ID];
Type *ElemTy = getTypeByID(getContainedTypeID(ID, 0));
if (!ElemTy)
return nullptr;

Expand Down Expand Up @@ -1733,7 +1748,7 @@ Error BitcodeReader::parseTypeTableBody() {
// Read a record.
Record.clear();
Type *ResultTy = nullptr;
Type *ElemTy = nullptr;
SmallVector<unsigned> ContainedIDs;
Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
if (!MaybeRecord)
return MaybeRecord.takeError();
Expand All @@ -1746,7 +1761,6 @@ Error BitcodeReader::parseTypeTableBody() {
if (Record.empty())
return error("Invalid record");
TypeList.resize(Record[0]);
ElementTypeList.resize(Record[0]);
continue;
case bitc::TYPE_CODE_VOID: // VOID
ResultTy = Type::getVoidTy(Context);
Expand Down Expand Up @@ -1809,7 +1823,7 @@ Error BitcodeReader::parseTypeTableBody() {
if (!ResultTy ||
!PointerType::isValidElementType(ResultTy))
return error("Invalid type");
ElemTy = ResultTy;
ContainedIDs.push_back(Record[0]);
ResultTy = PointerType::get(ResultTy, AddressSpace);
break;
}
Expand Down Expand Up @@ -1840,6 +1854,7 @@ Error BitcodeReader::parseTypeTableBody() {
if (!ResultTy || ArgTys.size() < Record.size()-3)
return error("Invalid type");

ContainedIDs.append(Record.begin() + 2, Record.end());
ResultTy = FunctionType::get(ResultTy, ArgTys, Record[0]);
break;
}
Expand All @@ -1862,6 +1877,7 @@ Error BitcodeReader::parseTypeTableBody() {
if (!ResultTy || ArgTys.size() < Record.size()-2)
return error("Invalid type");

ContainedIDs.append(Record.begin() + 1, Record.end());
ResultTy = FunctionType::get(ResultTy, ArgTys, Record[0]);
break;
}
Expand All @@ -1877,6 +1893,7 @@ Error BitcodeReader::parseTypeTableBody() {
}
if (EltTys.size() != Record.size()-1)
return error("Invalid type");
ContainedIDs.append(Record.begin() + 1, Record.end());
ResultTy = StructType::get(Context, EltTys, Record[0]);
break;
}
Expand Down Expand Up @@ -1911,6 +1928,7 @@ Error BitcodeReader::parseTypeTableBody() {
if (EltTys.size() != Record.size()-1)
return error("Invalid record");
Res->setBody(EltTys, Record[0]);
ContainedIDs.append(Record.begin() + 1, Record.end());
ResultTy = Res;
break;
}
Expand Down Expand Up @@ -1938,6 +1956,7 @@ Error BitcodeReader::parseTypeTableBody() {
ResultTy = getTypeByID(Record[1]);
if (!ResultTy || !ArrayType::isValidElementType(ResultTy))
return error("Invalid type");
ContainedIDs.push_back(Record[1]);
ResultTy = ArrayType::get(ResultTy, Record[0]);
break;
case bitc::TYPE_CODE_VECTOR: // VECTOR: [numelts, eltty] or
Expand All @@ -1950,6 +1969,7 @@ Error BitcodeReader::parseTypeTableBody() {
if (!ResultTy || !VectorType::isValidElementType(ResultTy))
return error("Invalid type");
bool Scalable = Record.size() > 2 ? Record[2] : false;
ContainedIDs.push_back(Record[1]);
ResultTy = VectorType::get(ResultTy, Record[0], Scalable);
break;
}
Expand All @@ -1961,7 +1981,8 @@ Error BitcodeReader::parseTypeTableBody() {
"Invalid TYPE table: Only named structs can be forward referenced");
assert(ResultTy && "Didn't read a type?");
TypeList[NumRecords] = ResultTy;
ElementTypeList[NumRecords] = ElemTy;
if (!ContainedIDs.empty())
ContainedTypeIDs[NumRecords] = std::move(ContainedIDs);
++NumRecords;
}
}
Expand Down Expand Up @@ -2726,10 +2747,8 @@ Error BitcodeReader::parseConstants() {
InBounds = true;

SmallVector<Constant*, 16> Elts;
Type *Elt0FullTy = nullptr;
unsigned BaseTypeID = Record[OpNum];
while (OpNum != Record.size()) {
if (!Elt0FullTy)
Elt0FullTy = getTypeByID(Record[OpNum]);
Type *ElTy = getTypeByID(Record[OpNum++]);
if (!ElTy)
return error("Invalid record");
Expand All @@ -2739,10 +2758,21 @@ Error BitcodeReader::parseConstants() {
if (Elts.size() < 1)
return error("Invalid gep with no operands");

PointerType *OrigPtrTy = cast<PointerType>(Elt0FullTy->getScalarType());
if (!PointeeType)
PointeeType = OrigPtrTy->getPointerElementType();
else if (!OrigPtrTy->isOpaqueOrPointeeTypeMatches(PointeeType))
Type *BaseType = getTypeByID(BaseTypeID);
if (isa<VectorType>(BaseType)) {
BaseTypeID = getContainedTypeID(BaseTypeID, 0);
BaseType = getTypeByID(BaseTypeID);
}

PointerType *OrigPtrTy = dyn_cast_or_null<PointerType>(BaseType);
if (!OrigPtrTy)
return error("GEP base operand must be pointer or vector of pointer");

if (!PointeeType) {
PointeeType = getPtrElementTypeByID(BaseTypeID);
if (!PointeeType)
return error("Missing element type for old-style constant GEP");
} else if (!OrigPtrTy->isOpaqueOrPointeeTypeMatches(PointeeType))
return error("Explicit gep operator type does not match pointee type "
"of pointer operand");

Expand Down Expand Up @@ -3414,11 +3444,13 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {

if (Record.size() < 8)
return error("Invalid record");
Type *FTy = getTypeByID(Record[0]);
unsigned FTyID = Record[0];
Type *FTy = getTypeByID(FTyID);
if (!FTy)
return error("Invalid record");
if (isa<PointerType>(FTy)) {
FTy = getPtrElementTypeByID(Record[0]);
FTyID = getContainedTypeID(FTyID, 0);
FTy = getTypeByID(FTyID);
if (!FTy)
return error("Missing element type for old-style function");
}
Expand Down Expand Up @@ -3461,8 +3493,11 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {

Func->removeParamAttr(i, Kind);

Type *PTy = cast<FunctionType>(FTy)->getParamType(i);
Type *PtrEltTy = PTy->getPointerElementType();
unsigned ParamTypeID = getContainedTypeID(FTyID, i + 1);
Type *PtrEltTy = getPtrElementTypeByID(ParamTypeID);
if (!PtrEltTy)
return error("Missing param element type for attribute upgrade");

Attribute NewAttr;
switch (Kind) {
case Attribute::ByVal:
Expand Down
3 changes: 2 additions & 1 deletion llvm/test/Bitcode/DIExpression-aggresult.ll
View file
@@ -1,4 +1,5 @@
; RUN: llvm-dis -o - %s.bc | FileCheck %s
; RUN: llvm-dis -opaque-pointers=0 -o - %s.bc | FileCheck %s
; RUN: llvm-dis -opaque-pointers=1 -o - %s.bc | FileCheck %s
%class.A = type { i32, i32, i32, i32 }

define void @_Z3fooi(%class.A* sret(%class.A) %agg.result) #0 !dbg !3 {
Expand Down

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