void
CodeGenFunction::ExpandTypeToArgs(QualType Ty, RValue RV,
llvm::SmallVector<llvm::Value*, 16> &Args) {
const RecordType *RT = Ty->getAsStructureType();
assert(RT && "Can only expand structure types.");
RecordDecl *RD = RT->getDecl();
assert(RV.isAggregate() && "Unexpected rvalue during struct expansion");
llvm::Value *Addr = RV.getAggregateAddr();
for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
i != e; ++i) {
FieldDecl *FD = *i;
QualType FT = FD->getType();
// FIXME: What are the right qualifiers here?
LValue LV = EmitLValueForField(Addr, FD, false, 0);
if (CodeGenFunction::hasAggregateLLVMType(FT)) {
ExpandTypeToArgs(FT, RValue::getAggregate(LV.getAddress()), Args);
} else {
RValue RV = EmitLoadOfLValue(LV, FT);
assert(RV.isScalar() &&
"Unexpected non-scalar rvalue during struct expansion.");
Args.push_back(RV.getScalarVal());
}
}
}
llvm::Function::arg_iterator
CodeGenFunction::ExpandTypeFromArgs(QualType Ty, LValue LV,
llvm::Function::arg_iterator AI) {
const RecordType *RT = Ty->getAsStructureType();
assert(RT && "Can only expand structure types.");
RecordDecl *RD = RT->getDecl();
assert(LV.isSimple() &&
"Unexpected non-simple lvalue during struct expansion.");
llvm::Value *Addr = LV.getAddress();
for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
i != e; ++i) {
FieldDecl *FD = *i;
QualType FT = FD->getType();
// FIXME: What are the right qualifiers here?
LValue LV = EmitLValueForField(Addr, FD, false, 0);
if (CodeGenFunction::hasAggregateLLVMType(FT)) {
AI = ExpandTypeFromArgs(FT, LV, AI);
} else {
EmitStoreThroughLValue(RValue::get(AI), LV, FT);
++AI;
}
}
return AI;
}
//---------------------------------------------------------
void VisitExpr(Expr* Node)
{
for (RecordDecl::field_iterator i = RD->field_begin(),
e = RD->field_end(); i != e; ++i)
{
compoundStmts.push_back(Assign_(
MemberPoint_(Paren_(Clone_(LHS)), *i),
MemberPoint_(Paren_(Clone_(Node)), *i)));
}
}
/// GetNumNonZeroBytesInInit - Get an approximate count of the number of
/// non-zero bytes that will be stored when outputting the initializer for the
/// specified initializer expression.
static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
E = E->IgnoreParens();
// 0 and 0.0 won't require any non-zero stores!
if (isSimpleZero(E, CGF)) return CharUnits::Zero();
// If this is an initlist expr, sum up the size of sizes of the (present)
// elements. If this is something weird, assume the whole thing is non-zero.
const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType()))
return CGF.getContext().getTypeSizeInChars(E->getType());
// InitListExprs for structs have to be handled carefully. If there are
// reference members, we need to consider the size of the reference, not the
// referencee. InitListExprs for unions and arrays can't have references.
if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
if (!RT->isUnionType()) {
RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
CharUnits NumNonZeroBytes = CharUnits::Zero();
unsigned ILEElement = 0;
for (RecordDecl::field_iterator Field = SD->field_begin(),
FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) {
// We're done once we hit the flexible array member or run out of
// InitListExpr elements.
if (Field->getType()->isIncompleteArrayType() ||
ILEElement == ILE->getNumInits())
break;
if (Field->isUnnamedBitfield())
continue;
const Expr *E = ILE->getInit(ILEElement++);
// Reference values are always non-null and have the width of a pointer.
if (Field->getType()->isReferenceType())
NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
CGF.getContext().getTargetInfo().getPointerWidth(0));
else
NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
}
return NumNonZeroBytes;
}
}
CharUnits NumNonZeroBytes = CharUnits::Zero();
for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
return NumNonZeroBytes;
}
//---------------------------------------------------------
void VisitInitListExpr(InitListExpr *RHS)
{
unsigned elementNo = 0;
for (RecordDecl::field_iterator i = RD->field_begin(),
e = RD->field_end(); i != e; ++i)
{
// how to handle?
if (i->isUnnamedBitfield())
continue;
compoundStmts.push_back(Assign_(
MemberPoint_(Paren_(Clone_(LHS)), *i),
elementNo < RHS->getNumInits() ?
Clone_ (RHS->getInit(elementNo)) :
Int_(0)));
elementNo++;
}
}
void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
#if 0
// FIXME: Assess perf here? Figure out what cases are worth optimizing here
// (Length of globals? Chunks of zeroed-out space?).
//
// If we can, prefer a copy from a global; this is a lot less code for long
// globals, and it's easier for the current optimizers to analyze.
if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
llvm::GlobalVariable* GV =
new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
llvm::GlobalValue::InternalLinkage, C, "");
EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType()));
return;
}
#endif
if (E->hadArrayRangeDesignator())
CGF.ErrorUnsupported(E, "GNU array range designator extension");
llvm::Value *DestPtr = Dest.getAddr();
// Handle initialization of an array.
if (E->getType()->isArrayType()) {
llvm::PointerType *APType =
cast<llvm::PointerType>(DestPtr->getType());
llvm::ArrayType *AType =
cast<llvm::ArrayType>(APType->getElementType());
uint64_t NumInitElements = E->getNumInits();
if (E->getNumInits() > 0) {
QualType T1 = E->getType();
QualType T2 = E->getInit(0)->getType();
if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
EmitAggLoadOfLValue(E->getInit(0));
return;
}
}
uint64_t NumArrayElements = AType->getNumElements();
assert(NumInitElements <= NumArrayElements);
QualType elementType = E->getType().getCanonicalType();
elementType = CGF.getContext().getQualifiedType(
cast<ArrayType>(elementType)->getElementType(),
elementType.getQualifiers() + Dest.getQualifiers());
// DestPtr is an array*. Construct an elementType* by drilling
// down a level.
llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
llvm::Value *indices[] = { zero, zero };
llvm::Value *begin =
Builder.CreateInBoundsGEP(DestPtr, indices, "arrayinit.begin");
// Exception safety requires us to destroy all the
// already-constructed members if an initializer throws.
// For that, we'll need an EH cleanup.
QualType::DestructionKind dtorKind = elementType.isDestructedType();
llvm::AllocaInst *endOfInit = 0;
EHScopeStack::stable_iterator cleanup;
llvm::Instruction *cleanupDominator = 0;
if (CGF.needsEHCleanup(dtorKind)) {
// In principle we could tell the cleanup where we are more
// directly, but the control flow can get so varied here that it
// would actually be quite complex. Therefore we go through an
// alloca.
endOfInit = CGF.CreateTempAlloca(begin->getType(),
"arrayinit.endOfInit");
cleanupDominator = Builder.CreateStore(begin, endOfInit);
CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
CGF.getDestroyer(dtorKind));
cleanup = CGF.EHStack.stable_begin();
// Otherwise, remember that we didn't need a cleanup.
} else {
dtorKind = QualType::DK_none;
}
llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
// The 'current element to initialize'. The invariants on this
// variable are complicated. Essentially, after each iteration of
// the loop, it points to the last initialized element, except
// that it points to the beginning of the array before any
// elements have been initialized.
llvm::Value *element = begin;
// Emit the explicit initializers.
for (uint64_t i = 0; i != NumInitElements; ++i) {
// Advance to the next element.
if (i > 0) {
element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
// Tell the cleanup that it needs to destroy up to this
// element. TODO: some of these stores can be trivially
// observed to be unnecessary.
if (endOfInit) Builder.CreateStore(element, endOfInit);
}
LValue elementLV = CGF.MakeAddrLValue(element, elementType);
EmitInitializationToLValue(E->getInit(i), elementLV);
}
// Check whether there's a non-trivial array-fill expression.
// Note that this will be a CXXConstructExpr even if the element
// type is an array (or array of array, etc.) of class type.
Expr *filler = E->getArrayFiller();
bool hasTrivialFiller = true;
if (CXXConstructExpr *cons = dyn_cast_or_null<CXXConstructExpr>(filler)) {
assert(cons->getConstructor()->isDefaultConstructor());
hasTrivialFiller = cons->getConstructor()->isTrivial();
}
// Any remaining elements need to be zero-initialized, possibly
// using the filler expression. We can skip this if the we're
// emitting to zeroed memory.
if (NumInitElements != NumArrayElements &&
!(Dest.isZeroed() && hasTrivialFiller &&
CGF.getTypes().isZeroInitializable(elementType))) {
// Use an actual loop. This is basically
// do { *array++ = filler; } while (array != end);
// Advance to the start of the rest of the array.
if (NumInitElements) {
element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
if (endOfInit) Builder.CreateStore(element, endOfInit);
}
// Compute the end of the array.
llvm::Value *end = Builder.CreateInBoundsGEP(begin,
llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
"arrayinit.end");
llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
// Jump into the body.
CGF.EmitBlock(bodyBB);
llvm::PHINode *currentElement =
Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
currentElement->addIncoming(element, entryBB);
// Emit the actual filler expression.
LValue elementLV = CGF.MakeAddrLValue(currentElement, elementType);
if (filler)
EmitInitializationToLValue(filler, elementLV);
else
EmitNullInitializationToLValue(elementLV);
// Move on to the next element.
llvm::Value *nextElement =
Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
// Tell the EH cleanup that we finished with the last element.
if (endOfInit) Builder.CreateStore(nextElement, endOfInit);
// Leave the loop if we're done.
llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
"arrayinit.done");
llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
Builder.CreateCondBr(done, endBB, bodyBB);
currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
CGF.EmitBlock(endBB);
}
// Leave the partial-array cleanup if we entered one.
if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
return;
}
assert(E->getType()->isRecordType() && "Only support structs/unions here!");
// Do struct initialization; this code just sets each individual member
// to the approprate value. This makes bitfield support automatic;
// the disadvantage is that the generated code is more difficult for
// the optimizer, especially with bitfields.
unsigned NumInitElements = E->getNumInits();
RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
if (record->isUnion()) {
// Only initialize one field of a union. The field itself is
// specified by the initializer list.
if (!E->getInitializedFieldInUnion()) {
// Empty union; we have nothing to do.
#ifndef NDEBUG
// Make sure that it's really an empty and not a failure of
// semantic analysis.
for (RecordDecl::field_iterator Field = record->field_begin(),
FieldEnd = record->field_end();
Field != FieldEnd; ++Field)
assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
#endif
return;
}
// FIXME: volatility
FieldDecl *Field = E->getInitializedFieldInUnion();
LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
if (NumInitElements) {
// Store the initializer into the field
EmitInitializationToLValue(E->getInit(0), FieldLoc);
} else {
// Default-initialize to null.
EmitNullInitializationToLValue(FieldLoc);
}
return;
}
// We'll need to enter cleanup scopes in case any of the member
// initializers throw an exception.
SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
llvm::Instruction *cleanupDominator = 0;
// Here we iterate over the fields; this makes it simpler to both
// default-initialize fields and skip over unnamed fields.
unsigned curInitIndex = 0;
for (RecordDecl::field_iterator field = record->field_begin(),
fieldEnd = record->field_end();
field != fieldEnd; ++field) {
// We're done once we hit the flexible array member.
if (field->getType()->isIncompleteArrayType())
break;
// Always skip anonymous bitfields.
if (field->isUnnamedBitfield())
continue;
// We're done if we reach the end of the explicit initializers, we
// have a zeroed object, and the rest of the fields are
// zero-initializable.
if (curInitIndex == NumInitElements && Dest.isZeroed() &&
CGF.getTypes().isZeroInitializable(E->getType()))
break;
// FIXME: volatility
LValue LV = CGF.EmitLValueForFieldInitialization(DestPtr, *field, 0);
// We never generate write-barries for initialized fields.
LV.setNonGC(true);
if (curInitIndex < NumInitElements) {
// Store the initializer into the field.
EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
} else {
// We're out of initalizers; default-initialize to null
EmitNullInitializationToLValue(LV);
}
// Push a destructor if necessary.
// FIXME: if we have an array of structures, all explicitly
// initialized, we can end up pushing a linear number of cleanups.
bool pushedCleanup = false;
if (QualType::DestructionKind dtorKind
= field->getType().isDestructedType()) {
assert(LV.isSimple());
if (CGF.needsEHCleanup(dtorKind)) {
if (!cleanupDominator)
cleanupDominator = CGF.Builder.CreateUnreachable(); // placeholder
CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
CGF.getDestroyer(dtorKind), false);
cleanups.push_back(CGF.EHStack.stable_begin());
pushedCleanup = true;
}
}
// If the GEP didn't get used because of a dead zero init or something
// else, clean it up for -O0 builds and general tidiness.
if (!pushedCleanup && LV.isSimple())
if (llvm::GetElementPtrInst *GEP =
dyn_cast<llvm::GetElementPtrInst>(LV.getAddress()))
if (GEP->use_empty())
GEP->eraseFromParent();
}
// Deactivate all the partial cleanups in reverse order, which
// generally means popping them.
for (unsigned i = cleanups.size(); i != 0; --i)
CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
// Destroy the placeholder if we made one.
if (cleanupDominator)
cleanupDominator->eraseFromParent();
}
void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
#if 0
// FIXME: Assess perf here? Figure out what cases are worth optimizing here
// (Length of globals? Chunks of zeroed-out space?).
//
// If we can, prefer a copy from a global; this is a lot less code for long
// globals, and it's easier for the current optimizers to analyze.
if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
llvm::GlobalVariable* GV =
new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
llvm::GlobalValue::InternalLinkage, C, "");
EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType()));
return;
}
#endif
if (E->hadArrayRangeDesignator()) {
CGF.ErrorUnsupported(E, "GNU array range designator extension");
}
// Handle initialization of an array.
if (E->getType()->isArrayType()) {
const llvm::PointerType *APType =
cast<llvm::PointerType>(DestPtr->getType());
const llvm::ArrayType *AType =
cast<llvm::ArrayType>(APType->getElementType());
uint64_t NumInitElements = E->getNumInits();
if (E->getNumInits() > 0) {
QualType T1 = E->getType();
QualType T2 = E->getInit(0)->getType();
if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
EmitAggLoadOfLValue(E->getInit(0));
return;
}
}
uint64_t NumArrayElements = AType->getNumElements();
QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
// FIXME: were we intentionally ignoring address spaces and GC attributes?
for (uint64_t i = 0; i != NumArrayElements; ++i) {
llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
LValue LV = CGF.MakeAddrLValue(NextVal, ElementType);
if (i < NumInitElements)
EmitInitializationToLValue(E->getInit(i), LV, ElementType);
else
EmitNullInitializationToLValue(LV, ElementType);
}
return;
}
assert(E->getType()->isRecordType() && "Only support structs/unions here!");
// Do struct initialization; this code just sets each individual member
// to the approprate value. This makes bitfield support automatic;
// the disadvantage is that the generated code is more difficult for
// the optimizer, especially with bitfields.
unsigned NumInitElements = E->getNumInits();
RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
// If we're initializing the whole aggregate, just do it in place.
// FIXME: This is a hack around an AST bug (PR6537).
if (NumInitElements == 1 && E->getType() == E->getInit(0)->getType()) {
EmitInitializationToLValue(E->getInit(0),
CGF.MakeAddrLValue(DestPtr, E->getType()),
E->getType());
return;
}
if (E->getType()->isUnionType()) {
// Only initialize one field of a union. The field itself is
// specified by the initializer list.
if (!E->getInitializedFieldInUnion()) {
// Empty union; we have nothing to do.
#ifndef NDEBUG
// Make sure that it's really an empty and not a failure of
// semantic analysis.
for (RecordDecl::field_iterator Field = SD->field_begin(),
FieldEnd = SD->field_end();
Field != FieldEnd; ++Field)
assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
#endif
return;
}
// FIXME: volatility
FieldDecl *Field = E->getInitializedFieldInUnion();
LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
if (NumInitElements) {
// Store the initializer into the field
EmitInitializationToLValue(E->getInit(0), FieldLoc, Field->getType());
} else {
// Default-initialize to null
EmitNullInitializationToLValue(FieldLoc, Field->getType());
}
return;
}
// Here we iterate over the fields; this makes it simpler to both
// default-initialize fields and skip over unnamed fields.
unsigned CurInitVal = 0;
for (RecordDecl::field_iterator Field = SD->field_begin(),
FieldEnd = SD->field_end();
Field != FieldEnd; ++Field) {
// We're done once we hit the flexible array member
if (Field->getType()->isIncompleteArrayType())
break;
if (Field->isUnnamedBitfield())
continue;
// FIXME: volatility
LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, *Field, 0);
// We never generate write-barries for initialized fields.
FieldLoc.setNonGC(true);
if (CurInitVal < NumInitElements) {
// Store the initializer into the field.
EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc,
Field->getType());
} else {
// We're out of initalizers; default-initialize to null
EmitNullInitializationToLValue(FieldLoc, Field->getType());
}
}
}
/// CreateType - get structure or union type.
llvm::DIType CGDebugInfo::CreateType(const RecordType *Ty,
llvm::DICompileUnit Unit) {
RecordDecl *Decl = Ty->getDecl();
unsigned Tag;
if (Decl->isStruct())
Tag = llvm::dwarf::DW_TAG_structure_type;
else if (Decl->isUnion())
Tag = llvm::dwarf::DW_TAG_union_type;
else {
assert(Decl->isClass() && "Unknown RecordType!");
Tag = llvm::dwarf::DW_TAG_class_type;
}
SourceManager &SM = M->getContext().getSourceManager();
// Get overall information about the record type for the debug info.
std::string Name = Decl->getNameAsString();
llvm::DICompileUnit DefUnit = getOrCreateCompileUnit(Decl->getLocation());
unsigned Line = SM.getInstantiationLineNumber(Decl->getLocation());
// Records and classes and unions can all be recursive. To handle them, we
// first generate a debug descriptor for the struct as a forward declaration.
// Then (if it is a definition) we go through and get debug info for all of
// its members. Finally, we create a descriptor for the complete type (which
// may refer to the forward decl if the struct is recursive) and replace all
// uses of the forward declaration with the final definition.
llvm::DIType FwdDecl =
DebugFactory.CreateCompositeType(Tag, Unit, Name, DefUnit, Line, 0, 0, 0, 0,
llvm::DIType(), llvm::DIArray());
// If this is just a forward declaration, return it.
if (!Decl->getDefinition(M->getContext()))
return FwdDecl;
// Otherwise, insert it into the TypeCache so that recursive uses will find
// it.
TypeCache[QualType(Ty, 0).getAsOpaquePtr()] = FwdDecl;
// Convert all the elements.
llvm::SmallVector<llvm::DIDescriptor, 16> EltTys;
const ASTRecordLayout &RL = M->getContext().getASTRecordLayout(Decl);
unsigned FieldNo = 0;
for (RecordDecl::field_iterator I = Decl->field_begin(M->getContext()),
E = Decl->field_end(M->getContext());
I != E; ++I, ++FieldNo) {
FieldDecl *Field = *I;
llvm::DIType FieldTy = getOrCreateType(Field->getType(), Unit);
std::string FieldName = Field->getNameAsString();
// Get the location for the field.
SourceLocation FieldDefLoc = Field->getLocation();
llvm::DICompileUnit FieldDefUnit = getOrCreateCompileUnit(FieldDefLoc);
unsigned FieldLine = SM.getInstantiationLineNumber(FieldDefLoc);
QualType FType = Field->getType();
uint64_t FieldSize = 0;
unsigned FieldAlign = 0;
if (!FType->isIncompleteArrayType()) {
// Bit size, align and offset of the type.
FieldSize = M->getContext().getTypeSize(FType);
Expr *BitWidth = Field->getBitWidth();
if (BitWidth)
FieldSize =
BitWidth->getIntegerConstantExprValue(M->getContext()).getZExtValue();
FieldAlign = M->getContext().getTypeAlign(FType);
}
uint64_t FieldOffset = RL.getFieldOffset(FieldNo);
// Create a DW_TAG_member node to remember the offset of this field in the
// struct. FIXME: This is an absolutely insane way to capture this
// information. When we gut debug info, this should be fixed.
FieldTy = DebugFactory.CreateDerivedType(llvm::dwarf::DW_TAG_member, Unit,
FieldName, FieldDefUnit,
FieldLine, FieldSize, FieldAlign,
FieldOffset, 0, FieldTy);
EltTys.push_back(FieldTy);
}
llvm::DIArray Elements =
DebugFactory.GetOrCreateArray(&EltTys[0], EltTys.size());
// Bit size, align and offset of the type.
uint64_t Size = M->getContext().getTypeSize(Ty);
uint64_t Align = M->getContext().getTypeAlign(Ty);
llvm::DIType RealDecl =
DebugFactory.CreateCompositeType(Tag, Unit, Name, DefUnit, Line, Size,
Align, 0, 0, llvm::DIType(), Elements);
// Now that we have a real decl for the struct, replace anything using the
// old decl with the new one. This will recursively update the debug info.
FwdDecl.getGV()->replaceAllUsesWith(RealDecl.getGV());
FwdDecl.getGV()->eraseFromParent();
return RealDecl;
}
