Improve handling of emitting 'null' pointers to data members.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@95066 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprConstant.cpp b/lib/CodeGen/CGExprConstant.cpp
index fba70cb..d843d02 100644
--- a/lib/CodeGen/CGExprConstant.cpp
+++ b/lib/CodeGen/CGExprConstant.cpp
@@ -911,7 +911,24 @@
return C;
}
-static inline bool isDataMemberPointerType(QualType T) {
+static bool containsPointerToDataMember(CodeGenTypes &Types, QualType T) {
+ // No need to check for member pointers when not compiling C++.
+ if (!Types.getContext().getLangOptions().CPlusPlus)
+ return false;
+
+ T = Types.getContext().getBaseElementType(T);
+
+ if (const RecordType *RT = T->getAs<RecordType>()) {
+ const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+
+ // FIXME: It would be better if there was a way to explicitly compute the
+ // record layout instead of converting to a type.
+ Types.ConvertTagDeclType(RD);
+
+ const CGRecordLayout &Layout = Types.getCGRecordLayout(RD);
+ return Layout.containsPointerToDataMember();
+ }
+
if (const MemberPointerType *MPT = T->getAs<MemberPointerType>())
return !MPT->getPointeeType()->isFunctionType();
@@ -919,45 +936,58 @@
}
llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
- // No need to check for member pointers when not compiling C++.
- if (!getContext().getLangOptions().CPlusPlus)
+ if (!containsPointerToDataMember(getTypes(), T))
return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
-
+
if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) {
QualType ElementTy = CAT->getElementType();
- // FIXME: Handle arrays of structs that contain member pointers.
- if (isDataMemberPointerType(Context.getBaseElementType(ElementTy))) {
- llvm::Constant *Element = EmitNullConstant(ElementTy);
- uint64_t NumElements = CAT->getSize().getZExtValue();
- std::vector<llvm::Constant *> Array(NumElements);
- for (uint64_t i = 0; i != NumElements; ++i)
- Array[i] = Element;
+ llvm::Constant *Element = EmitNullConstant(ElementTy);
+ unsigned NumElements = CAT->getSize().getZExtValue();
+ std::vector<llvm::Constant *> Array(NumElements);
+ for (unsigned i = 0; i != NumElements; ++i)
+ Array[i] = Element;
- const llvm::ArrayType *ATy =
- cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
- return llvm::ConstantArray::get(ATy, Array);
- }
+ const llvm::ArrayType *ATy =
+ cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
+ return llvm::ConstantArray::get(ATy, Array);
}
if (const RecordType *RT = T->getAs<RecordType>()) {
- const RecordDecl *RD = RT->getDecl();
- // FIXME: It would be better if there was a way to explicitly compute the
- // record layout instead of converting to a type.
- Types.ConvertTagDeclType(RD);
+ const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+ assert(!RD->getNumBases() &&
+ "FIXME: Handle zero-initializing structs with bases and "
+ "pointers to data members.");
+ const llvm::StructType *STy =
+ cast<llvm::StructType>(getTypes().ConvertTypeForMem(T));
+ unsigned NumElements = STy->getNumElements();
+ std::vector<llvm::Constant *> Elements(NumElements);
- const CGRecordLayout &Layout = Types.getCGRecordLayout(RD);
- if (Layout.containsMemberPointer()) {
- assert(0 && "FIXME: No support for structs with member pointers yet!");
+ for (RecordDecl::field_iterator I = RD->field_begin(),
+ E = RD->field_end(); I != E; ++I) {
+ const FieldDecl *FD = *I;
+
+ unsigned FieldNo = getTypes().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);
}
- // FIXME: Handle structs that contain member pointers.
- if (isDataMemberPointerType(T))
- return llvm::Constant::getAllOnesValue(getTypes().ConvertTypeForMem(T));
-
- return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
+ assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() &&
+ "Should only see pointers to data members here!");
+
+ // Itanium C++ ABI 2.3:
+ // A NULL pointer is represented as -1.
+ return llvm::ConstantInt::get(getTypes().ConvertTypeForMem(T), -1,
+ /*isSigned=*/true);
}
llvm::Constant *