llvm::Function* LocalStack::getStackPrepareFunc()
{
static const auto c_funcName = "stack.prepare";
if (auto func = getModule()->getFunction(c_funcName))
return func;
llvm::Type* argsTys[] = {Type::WordPtr, Type::Size->getPointerTo(), Type::Size, Type::Size, Type::Size, Type::BytePtr};
auto func = llvm::Function::Create(llvm::FunctionType::get(Type::WordPtr, argsTys, false), llvm::Function::PrivateLinkage, c_funcName, getModule());
func->setDoesNotThrow();
func->setDoesNotAccessMemory(1);
func->setDoesNotAlias(2);
func->setDoesNotCapture(2);
auto checkBB = llvm::BasicBlock::Create(func->getContext(), "Check", func);
auto updateBB = llvm::BasicBlock::Create(func->getContext(), "Update", func);
auto outOfStackBB = llvm::BasicBlock::Create(func->getContext(), "OutOfStack", func);
auto iter = func->arg_begin();
llvm::Argument* base = &(*iter++);
base->setName("base");
llvm::Argument* sizePtr = &(*iter++);
sizePtr->setName("size.ptr");
llvm::Argument* min = &(*iter++);
min->setName("min");
llvm::Argument* max = &(*iter++);
max->setName("max");
llvm::Argument* diff = &(*iter++);
diff->setName("diff");
llvm::Argument* jmpBuf = &(*iter);
jmpBuf->setName("jmpBuf");
InsertPointGuard guard{m_builder};
m_builder.SetInsertPoint(checkBB);
auto sizeAlignment = getModule()->getDataLayout().getABITypeAlignment(Type::Size);
auto size = m_builder.CreateAlignedLoad(sizePtr, sizeAlignment, "size");
auto minSize = m_builder.CreateAdd(size, min, "size.min", false, true);
auto maxSize = m_builder.CreateAdd(size, max, "size.max", true, true);
auto minOk = m_builder.CreateICmpSGE(minSize, m_builder.getInt64(0), "ok.min");
auto maxOk = m_builder.CreateICmpULE(maxSize, m_builder.getInt64(RuntimeManager::stackSizeLimit), "ok.max");
auto ok = m_builder.CreateAnd(minOk, maxOk, "ok");
m_builder.CreateCondBr(ok, updateBB, outOfStackBB, Type::expectTrue);
m_builder.SetInsertPoint(updateBB);
auto newSize = m_builder.CreateNSWAdd(size, diff, "size.next");
m_builder.CreateAlignedStore(newSize, sizePtr, sizeAlignment);
auto sp = m_builder.CreateGEP(base, size, "sp");
m_builder.CreateRet(sp);
m_builder.SetInsertPoint(outOfStackBB);
auto longjmp = llvm::Intrinsic::getDeclaration(getModule(), llvm::Intrinsic::eh_sjlj_longjmp);
m_builder.CreateCall(longjmp, {jmpBuf});
m_builder.CreateUnreachable();
return func;
}
llvm::Function* createLLVMFunction(Module& module, const ArgInfo& argInfo, llvm::GlobalValue::LinkageTypes linkage, const String& name) {
const auto llvmFunction = llvm::Function::Create(argInfo.makeFunctionType(), linkage, name.c_str(), module.getLLVMModulePtr());
if (argInfo.noMemoryAccess()) {
llvmFunction->setDoesNotAccessMemory();
}
if (argInfo.noExcept()) {
llvmFunction->setDoesNotThrow();
}
if (argInfo.noReturn()) {
llvmFunction->setDoesNotReturn();
}
return llvmFunction;
}
