llvm::GlobalVariable * IrStruct::getInterfaceVtbl(BaseClass * b, bool new_instance, size_t interfaces_index)
{
ClassGlobalMap::iterator it = interfaceVtblMap.find(b->base);
if (it != interfaceVtblMap.end())
return it->second;
IF_LOG Logger::println("Building vtbl for implementation of interface %s in class %s",
b->base->toPrettyChars(), aggrdecl->toPrettyChars());
LOG_SCOPE;
ClassDeclaration* cd = aggrdecl->isClassDeclaration();
assert(cd && "not a class aggregate");
FuncDeclarations vtbl_array;
b->fillVtbl(cd, &vtbl_array, new_instance);
std::vector<llvm::Constant*> constants;
constants.reserve(vtbl_array.dim);
// start with the interface info
VarDeclarationIter interfaces_idx(ClassDeclaration::classinfo->fields, 3);
// index into the interfaces array
llvm::Constant* idxs[2] = {
DtoConstSize_t(0),
DtoConstSize_t(interfaces_index)
};
llvm::Constant* c = llvm::ConstantExpr::getGetElementPtr(
getInterfaceArraySymbol(), idxs, true);
constants.push_back(c);
// add virtual function pointers
size_t n = vtbl_array.dim;
for (size_t i = 1; i < n; i++)
{
Dsymbol* dsym = static_cast<Dsymbol*>(vtbl_array.data[i]);
if (dsym == NULL)
{
// FIXME
// why is this null?
// happens for mini/s.d
constants.push_back(getNullValue(getVoidPtrType()));
continue;
}
FuncDeclaration* fd = dsym->isFuncDeclaration();
assert(fd && "vtbl entry not a function");
assert((!fd->isAbstract() || fd->fbody) &&
"null symbol in interface implementation vtable");
fd->codegen(Type::sir);
assert(fd->ir.irFunc && "invalid vtbl function");
constants.push_back(fd->ir.irFunc->func);
}
// build the vtbl constant
llvm::Constant* vtbl_constant = LLConstantStruct::getAnon(gIR->context(), constants, false);
// create the global variable to hold it
llvm::GlobalValue::LinkageTypes _linkage = DtoExternalLinkage(aggrdecl);
std::string mangle("_D");
mangle.append(cd->mangle());
mangle.append("11__interface");
mangle.append(b->base->mangle());
mangle.append("6__vtblZ");
llvm::GlobalVariable* GV = new llvm::GlobalVariable(
*gIR->module,
vtbl_constant->getType(),
true,
_linkage,
vtbl_constant,
mangle
);
// insert into the vtbl map
interfaceVtblMap.insert(std::make_pair(b->base, GV));
return GV;
}
llvm::GlobalVariable * IrAggr::getInterfaceVtbl(BaseClass * b, bool new_instance, size_t interfaces_index)
{
ClassGlobalMap::iterator it = interfaceVtblMap.find(b->base);
if (it != interfaceVtblMap.end())
return it->second;
IF_LOG Logger::println("Building vtbl for implementation of interface %s in class %s",
b->base->toPrettyChars(), aggrdecl->toPrettyChars());
LOG_SCOPE;
ClassDeclaration* cd = aggrdecl->isClassDeclaration();
assert(cd && "not a class aggregate");
FuncDeclarations vtbl_array;
b->fillVtbl(cd, &vtbl_array, new_instance);
std::vector<llvm::Constant*> constants;
constants.reserve(vtbl_array.dim);
if (!b->base->isCPPinterface()) { // skip interface info for CPP interfaces
// start with the interface info
VarDeclarationIter interfaces_idx(ClassDeclaration::classinfo->fields, 3);
// index into the interfaces array
llvm::Constant* idxs[2] = {
DtoConstSize_t(0),
DtoConstSize_t(interfaces_index)
};
llvm::Constant* c = llvm::ConstantExpr::getGetElementPtr(
getInterfaceArraySymbol(), idxs, true);
constants.push_back(c);
}
// add virtual function pointers
size_t n = vtbl_array.dim;
for (size_t i = b->base->vtblOffset(); i < n; i++)
{
Dsymbol* dsym = static_cast<Dsymbol*>(vtbl_array.data[i]);
if (dsym == NULL)
{
// FIXME
// why is this null?
// happens for mini/s.d
constants.push_back(getNullValue(getVoidPtrType()));
continue;
}
FuncDeclaration* fd = dsym->isFuncDeclaration();
assert(fd && "vtbl entry not a function");
assert((!fd->isAbstract() || fd->fbody) &&
"null symbol in interface implementation vtable");
fd->codegen(Type::sir);
assert(fd->ir.irFunc && "invalid vtbl function");
LLFunction *fn = fd->ir.irFunc->func;
// If the base is a cpp interface, 'this' parameter is a pointer to
// the interface not the underlying object as expected. Instead of
// the function, we place into the vtable a small wrapper, called thunk,
// that casts 'this' to the object and then pass it to the real function.
if (b->base->isCPPinterface()) {
TypeFunction *f = (TypeFunction*)fd->type->toBasetype();
assert(f->fty.arg_this);
// create the thunk function
OutBuffer name;
name.writestring("Th");
name.printf("%i", b->offset);
name.writestring(fd->mangle());
LLFunction *thunk = LLFunction::Create(isaFunction(fn->getType()->getContainedType(0)),
DtoLinkage(fd), name.toChars(), gIR->module);
// create entry and end blocks
llvm::BasicBlock* beginbb = llvm::BasicBlock::Create(gIR->context(), "entry", thunk);
llvm::BasicBlock* endbb = llvm::BasicBlock::Create(gIR->context(), "endentry", thunk);
gIR->scopes.push_back(IRScope(beginbb, endbb));
// copy the function parameters, so later we can pass them to the real function
std::vector<LLValue*> args;
llvm::Function::arg_iterator iarg = thunk->arg_begin();
for (; iarg != thunk->arg_end(); ++iarg)
args.push_back(iarg);
// cast 'this' to Object
LLValue* &thisArg = args[(f->fty.arg_sret == 0) ? 0 : 1];
LLType* thisType = thisArg->getType();
thisArg = DtoBitCast(thisArg, getVoidPtrType());
thisArg = DtoGEP1(thisArg, DtoConstInt(-b->offset));
thisArg = DtoBitCast(thisArg, thisType);
// call the real vtbl function.
LLValue *retVal = gIR->ir->CreateCall(fn, args);
// return from the thunk
if (thunk->getReturnType() == LLType::getVoidTy(gIR->context()))
llvm::ReturnInst::Create(gIR->context(), beginbb);
else
llvm::ReturnInst::Create(gIR->context(), retVal, beginbb);
// clean up
gIR->scopes.pop_back();
thunk->getBasicBlockList().pop_back();
fn = thunk;
}
constants.push_back(fn);
}
// build the vtbl constant
llvm::Constant* vtbl_constant = LLConstantStruct::getAnon(gIR->context(), constants, false);
// create the global variable to hold it
llvm::GlobalValue::LinkageTypes _linkage = DtoExternalLinkage(aggrdecl);
std::string mangle("_D");
mangle.append(cd->mangle());
mangle.append("11__interface");
mangle.append(b->base->mangle());
mangle.append("6__vtblZ");
llvm::GlobalVariable* GV = getOrCreateGlobal(cd->loc,
*gIR->module,
vtbl_constant->getType(),
true,
_linkage,
vtbl_constant,
mangle
);
// insert into the vtbl map
interfaceVtblMap.insert(std::make_pair(b->base, GV));
return GV;
}
