static bool shouldInternalize(const GlobalValue &GV,
const std::set<std::string> &ExternalNames,
const std::set<std::string> &DSONames) {
// Function must be defined here
if (GV.isDeclaration())
return false;
// Available externally is really just a "declaration with a body".
if (GV.hasAvailableExternallyLinkage())
return false;
// Already has internal linkage
if (GV.hasLocalLinkage())
return false;
// Marked to keep external?
if (ExternalNames.count(GV.getName()))
return false;
// Not needed for the symbol table?
if (!DSONames.count(GV.getName()))
return true;
// Not a linkonce. Someone can depend on it being on the symbol table.
if (!GV.hasLinkOnceLinkage())
return false;
// The address is not important, we can hide it.
if (GV.hasUnnamedAddr())
return true;
// FIXME: Check if the address is used.
return false;
}
bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
GlobalValue *DGV = getLinkedToGlobal(&GV);
if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
return false;
if (DGV && !GV.hasLocalLinkage() && !GV.hasAppendingLinkage()) {
auto *DGVar = dyn_cast<GlobalVariable>(DGV);
auto *SGVar = dyn_cast<GlobalVariable>(&GV);
if (DGVar && SGVar) {
if (DGVar->isDeclaration() && SGVar->isDeclaration() &&
(!DGVar->isConstant() || !SGVar->isConstant())) {
DGVar->setConstant(false);
SGVar->setConstant(false);
}
if (DGVar->hasCommonLinkage() && SGVar->hasCommonLinkage()) {
unsigned Align = std::max(DGVar->getAlignment(), SGVar->getAlignment());
SGVar->setAlignment(Align);
DGVar->setAlignment(Align);
}
}
GlobalValue::VisibilityTypes Visibility =
getMinVisibility(DGV->getVisibility(), GV.getVisibility());
DGV->setVisibility(Visibility);
GV.setVisibility(Visibility);
bool HasUnnamedAddr = GV.hasUnnamedAddr() && DGV->hasUnnamedAddr();
DGV->setUnnamedAddr(HasUnnamedAddr);
GV.setUnnamedAddr(HasUnnamedAddr);
}
// Don't want to append to global_ctors list, for example, when we
// are importing for ThinLTO, otherwise the global ctors and dtors
// get executed multiple times for local variables (the latter causing
// double frees).
if (GV.hasAppendingLinkage() && isPerformingImport())
return false;
if (isPerformingImport()) {
if (!doImportAsDefinition(&GV))
return false;
} else if (!DGV && !shouldOverrideFromSrc() &&
(GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
GV.hasAvailableExternallyLinkage()))
return false;
if (GV.isDeclaration())
return false;
if (const Comdat *SC = GV.getComdat()) {
bool LinkFromSrc;
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
if (!LinkFromSrc)
return false;
}
bool LinkFromSrc = true;
if (DGV && shouldLinkFromSource(LinkFromSrc, *DGV, GV))
return true;
if (LinkFromSrc)
ValuesToLink.insert(&GV);
return false;
}