void ModuleLinker::dropReplacedComdat(
GlobalValue &GV, const DenseSet<const Comdat *> &ReplacedDstComdats) {
Comdat *C = GV.getComdat();
if (!C)
return;
if (!ReplacedDstComdats.count(C))
return;
if (GV.use_empty()) {
GV.eraseFromParent();
return;
}
if (auto *F = dyn_cast<Function>(&GV)) {
F->deleteBody();
} else if (auto *Var = dyn_cast<GlobalVariable>(&GV)) {
Var->setInitializer(nullptr);
} else {
auto &Alias = cast<GlobalAlias>(GV);
Module &M = *Alias.getParent();
PointerType &Ty = *cast<PointerType>(Alias.getType());
GlobalValue *Declaration;
if (auto *FTy = dyn_cast<FunctionType>(Alias.getValueType())) {
Declaration = Function::Create(FTy, GlobalValue::ExternalLinkage, "", &M);
} else {
Declaration =
new GlobalVariable(M, Ty.getElementType(), /*isConstant*/ false,
GlobalValue::ExternalLinkage,
/*Initializer*/ nullptr);
}
Declaration->takeName(&Alias);
Alias.replaceAllUsesWith(Declaration);
Alias.eraseFromParent();
}
}
/// Predicate for Internalize pass.
static bool mustPreserveGV(const GlobalValue &GV) {
if (const Function *F = dyn_cast<Function>(&GV))
return F->isDeclaration() || AMDGPU::isEntryFunctionCC(F->getCallingConv());
return !GV.use_empty();
}
// RemoveUnusedGlobalValue - Loop over all of the uses of the specified
// GlobalValue, looking for the constant pointer ref that may be pointing to it.
// If found, check to see if the constant pointer ref is safe to destroy, and if
// so, nuke it. This will reduce the reference count on the global value, which
// might make it deader.
//
bool GlobalDCE::RemoveUnusedGlobalValue(GlobalValue &GV) {
if (GV.use_empty()) return false;
GV.removeDeadConstantUsers();
return GV.use_empty();
}
// emit_alias_to_llvm - Given decl and target emit alias to target.
void emit_alias_to_llvm(tree decl, tree target, tree target_decl) {
if (errorcount || sorrycount) return;
timevar_push(TV_LLVM_GLOBALS);
// Get or create LLVM global for our alias.
GlobalValue *V = cast<GlobalValue>(DECL_LLVM(decl));
GlobalValue *Aliasee = NULL;
if (target_decl)
Aliasee = cast<GlobalValue>(DECL_LLVM(target_decl));
else {
// This is something insane. Probably only LTHUNKs can be here
// Try to grab decl from IDENTIFIER_NODE
// Query SymTab for aliasee
const char* AliaseeName = IDENTIFIER_POINTER(target);
Aliasee =
dyn_cast_or_null<GlobalValue>(TheModule->
getValueSymbolTable().lookup(AliaseeName));
// Last resort. Query for name set via __asm__
if (!Aliasee) {
std::string starred = std::string("\001") + AliaseeName;
Aliasee =
dyn_cast_or_null<GlobalValue>(TheModule->
getValueSymbolTable().lookup(starred));
}
if (!Aliasee) {
error ("%J%qD aliased to undefined symbol %qE",
decl, decl, target);
timevar_pop(TV_LLVM_GLOBALS);
return;
}
}
GlobalValue::LinkageTypes Linkage;
// Check for external weak linkage
if (DECL_EXTERNAL(decl) && DECL_WEAK(decl))
Linkage = GlobalValue::WeakLinkage;
else if (!TREE_PUBLIC(decl))
Linkage = GlobalValue::InternalLinkage;
else
Linkage = GlobalValue::ExternalLinkage;
GlobalAlias* GA = new GlobalAlias(Aliasee->getType(), Linkage, "",
Aliasee, TheModule);
// Handle visibility style
if (TREE_PUBLIC(decl)) {
if (DECL_VISIBILITY(decl) == VISIBILITY_HIDDEN)
GA->setVisibility(GlobalValue::HiddenVisibility);
else if (DECL_VISIBILITY(decl) == VISIBILITY_PROTECTED)
GA->setVisibility(GlobalValue::ProtectedVisibility);
}
if (V->getType() == GA->getType())
V->replaceAllUsesWith(GA);
else if (!V->use_empty()) {
error ("%J Alias %qD used with invalid type!", decl, decl);
timevar_pop(TV_LLVM_GLOBALS);
return;
}
changeLLVMValue(V, GA);
GA->takeName(V);
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
GV->eraseFromParent();
else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
GA->eraseFromParent();
else if (Function *F = dyn_cast<Function>(V))
F->eraseFromParent();
else
assert(0 && "Unsuported global value");
TREE_ASM_WRITTEN(decl) = 1;
timevar_pop(TV_LLVM_GLOBALS);
return;
}