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Refactor the null-initialization for record types and make it handle bases that aren't i8 arrays. 

llvm-svn: 119980
This commit is contained in:
Anders Carlsson 2010-11-22 18:42:14 +00:00
parent a262546df7
commit 849ea413c6
1 changed files with 85 additions and 75 deletions
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160
clang/lib/CodeGen/CGExprConstant.cpp
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@ -964,8 +964,7 @@ FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T,
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
if (I->isVirtual()) {
// FIXME: We should initialize null pointer to data members in virtual
// bases here.
// Ignore virtual bases.
continue;
}
@ -1015,6 +1014,89 @@ FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T,
}
}
static llvm::Constant *EmitNullConstant(CodeGenModule &CGM,
const CXXRecordDecl *RD) {
QualType T = CGM.getContext().getTagDeclType(RD);
const llvm::StructType *STy =
cast<llvm::StructType>(CGM.getTypes().ConvertTypeForMem(T));
unsigned NumElements = STy->getNumElements();
std::vector<llvm::Constant *> Elements(NumElements);
const CGRecordLayout &Layout = CGM.getTypes().getCGRecordLayout(RD);
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
if (I->isVirtual()) {
// Ignore virtual bases.
continue;
}
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Ignore empty bases.
if (BaseDecl->isEmpty())
continue;
// Ignore bases that don't have any pointer to data members.
if (CGM.getTypes().isZeroInitializable(BaseDecl))
continue;
unsigned BaseFieldNo = Layout.getNonVirtualBaseLLVMFieldNo(BaseDecl);
const llvm::Type *BaseTy = STy->getElementType(BaseFieldNo);
if (isa<llvm::StructType>(BaseTy)) {
// We can just emit the base as a null constant.
Elements[BaseFieldNo] = EmitNullConstant(CGM, BaseDecl);
continue;
}
// Some bases are represented as arrays of i8 if the size of the
// base is smaller than its corresponding LLVM type.
// Figure out how many elements this base array has.
const llvm::ArrayType *BaseArrayTy = cast<llvm::ArrayType>(BaseTy);
unsigned NumBaseElements = BaseArrayTy->getNumElements();
// Fill in null data member pointers.
std::vector<llvm::Constant *> BaseElements(NumBaseElements);
FillInNullDataMemberPointers(CGM, I->getType(), BaseElements, 0);
// Now go through all other elements and zero them out.
if (NumBaseElements) {
const llvm::Type* Int8Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext());
llvm::Constant *Zero = llvm::Constant::getNullValue(Int8Ty);
for (unsigned I = 0; I != NumBaseElements; ++I) {
if (!BaseElements[I])
BaseElements[I] = Zero;
}
}
Elements[BaseFieldNo] = llvm::ConstantArray::get(BaseArrayTy, BaseElements);
}
// Visit all fields.
for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
I != E; ++I) {
const FieldDecl *FD = *I;
// Ignore bit fields.
if (FD->isBitField())
continue;
unsigned FieldNo = Layout.getLLVMFieldNo(FD);
Elements[FieldNo] = CGM.EmitNullConstant(FD->getType());
}
// Now go through all other fields and zero them out.
for (unsigned i = 0; i != NumElements; ++i) {
if (!Elements[i])
Elements[i] = llvm::Constant::getNullValue(STy->getElementType(i));
}
return llvm::ConstantStruct::get(STy, Elements);
}
llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
if (getTypes().isZeroInitializable(T))
return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
@ -1036,79 +1118,7 @@ llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
if (const RecordType *RT = T->getAs<RecordType>()) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
const llvm::StructType *STy =
cast<llvm::StructType>(getTypes().ConvertTypeForMem(T));
unsigned NumElements = STy->getNumElements();
std::vector<llvm::Constant *> Elements(NumElements);
const CGRecordLayout &Layout = getTypes().getCGRecordLayout(RD);
// Go through all bases and fill in any null pointer to data members.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
if (I->isVirtual()) {
// FIXME: We should initialize null pointer to data members in virtual
// bases here.
continue;
}
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Ignore empty bases.
if (BaseDecl->isEmpty())
continue;
// Ignore bases that don't have any pointer to data members.
if (getTypes().isZeroInitializable(BaseDecl))
continue;
// Currently, all bases are arrays of i8. Figure out how many elements
// this base array has.
unsigned BaseFieldNo = Layout.getNonVirtualBaseLLVMFieldNo(BaseDecl);
const llvm::ArrayType *BaseArrayTy =
cast<llvm::ArrayType>(STy->getElementType(BaseFieldNo));
unsigned NumBaseElements = BaseArrayTy->getNumElements();
std::vector<llvm::Constant *> BaseElements(NumBaseElements);
// Now fill in null data member pointers.
FillInNullDataMemberPointers(*this, I->getType(), BaseElements, 0);
// Now go through all other elements and zero them out.
if (NumBaseElements) {
llvm::Constant *Zero =
llvm::ConstantInt::get(llvm::Type::getInt8Ty(getLLVMContext()), 0);
for (unsigned I = 0; I != NumBaseElements; ++I) {
if (!BaseElements[I])
BaseElements[I] = Zero;
}
}
Elements[BaseFieldNo] = llvm::ConstantArray::get(BaseArrayTy,
BaseElements);
}
for (RecordDecl::field_iterator I = RD->field_begin(),
E = RD->field_end(); I != E; ++I) {
const FieldDecl *FD = *I;
// Ignore bit fields.
if (FD->isBitField())
continue;
unsigned FieldNo = Layout.getLLVMFieldNo(FD);
Elements[FieldNo] = EmitNullConstant(FD->getType());
}
// Now go through all other fields and zero them out.
for (unsigned i = 0; i != NumElements; ++i) {
if (!Elements[i])
Elements[i] = llvm::Constant::getNullValue(STy->getElementType(i));
}
return llvm::ConstantStruct::get(STy, Elements);
return ::EmitNullConstant(*this, RD);
}
assert(T->isMemberPointerType() && "Should only see member pointers here!");