// maybeUpdateRTTILinkage - Will update the linkage of the RTTI data structures
// from available_externally to the correct linkage if necessary. An example of
// this is:
//
// struct A {
// virtual void f();
// };
//
// const std::type_info &g() {
// return typeid(A);
// }
//
// void A::f() { }
//
// When we're generating the typeid(A) expression, we do not yet know that
// A's key function is defined in this translation unit, so we will give the
// typeinfo and typename structures available_externally linkage. When A::f
// forces the vtable to be generated, we need to change the linkage of the
// typeinfo and typename structs, otherwise we'll end up with undefined
// externals when linking.
static void
maybeUpdateRTTILinkage(CodeGenModule &CGM, llvm::GlobalVariable *GV,
QualType Ty) {
// We're only interested in globals with available_externally linkage.
if (!GV->hasAvailableExternallyLinkage())
return;
// Get the real linkage for the type.
llvm::GlobalVariable::LinkageTypes Linkage = getTypeInfoLinkage(CGM, Ty);
// If variable is supposed to have available_externally linkage, we don't
// need to do anything.
if (Linkage == llvm::GlobalVariable::AvailableExternallyLinkage)
return;
// Update the typeinfo linkage.
GV->setLinkage(Linkage);
// Get the typename global.
SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().mangleCXXRTTIName(Ty, Out);
Out.flush();
StringRef Name = OutName.str();
llvm::GlobalVariable *TypeNameGV = CGM.getModule().getNamedGlobal(Name);
assert(TypeNameGV->hasAvailableExternallyLinkage() &&
"Type name has different linkage from type info!");
// And update its linkage.
TypeNameGV->setLinkage(Linkage);
}
CodeGenTypes::CodeGenTypes(CodeGenModule &cgm)
: CGM(cgm), Context(cgm.getContext()), TheModule(cgm.getModule()),
TheDataLayout(cgm.getDataLayout()),
Target(cgm.getTarget()), TheCXXABI(cgm.getCXXABI()),
TheABIInfo(cgm.getTargetCodeGenInfo().getABIInfo()) {
SkippedLayout = false;
}
CodeGenTypes::CodeGenTypes(CodeGenModule &CGM)
: Context(CGM.getContext()), Target(Context.getTargetInfo()),
TheModule(CGM.getModule()), TheTargetData(CGM.getTargetData()),
TheABIInfo(CGM.getTargetCodeGenInfo().getABIInfo()),
TheCXXABI(CGM.getCXXABI()),
CodeGenOpts(CGM.getCodeGenOpts()), CGM(CGM) {
SkippedLayout = false;
}
static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk,
llvm::Function *ThunkFn, bool ForVTable,
GlobalDecl GD) {
CGM.setFunctionLinkage(GD, ThunkFn);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD,
!Thunk.Return.isEmpty());
// Set the right visibility.
CGM.setGVProperties(ThunkFn, GD);
if (!CGM.getCXXABI().exportThunk()) {
ThunkFn->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
ThunkFn->setDSOLocal(true);
}
if (CGM.supportsCOMDAT() && ThunkFn->isWeakForLinker())
ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
}
static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk,
llvm::Function *ThunkFn, bool ForVTable,
GlobalDecl GD) {
CGM.setFunctionLinkage(GD, ThunkFn);
CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD,
!Thunk.Return.isEmpty());
// Set the right visibility.
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
setThunkVisibility(CGM, MD, Thunk, ThunkFn);
if (CGM.supportsCOMDAT() && ThunkFn->isWeakForLinker())
ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
}
static bool shouldEmitAvailableExternallyVTable(const CodeGenModule &CGM,
const CXXRecordDecl *RD) {
return CGM.getCodeGenOpts().OptimizationLevel > 0 &&
CGM.getCXXABI().canSpeculativelyEmitVTable(RD);
}
