int main()
{
llvm::LLVMContext &context = llvm::getGlobalContext();
llvm::Module *module = new llvm::Module("hello_world", context);
llvm::IRBuilder<> builder(context);
// define main() as void
llvm::FunctionType *funcType = llvm::FunctionType::get(builder.getVoidTy(), false);
llvm::Function *mainFunc = llvm::Function::Create(funcType, llvm::Function::ExternalLinkage, "main", module);
llvm::BasicBlock *entry = llvm::BasicBlock::Create(context, "entrypoint", mainFunc);
builder.SetInsertPoint(entry);
// define the 'hello world' string constant
llvm::Value *helloWorld = builder.CreateGlobalStringPtr("Hello world!");
// define the args to puts()
std::vector<llvm::Type*> putsArgs;
putsArgs.push_back(builder.getInt8Ty()->getPointerTo());
llvm::ArrayRef<llvm::Type*> argsRef(putsArgs);
llvm::FunctionType *putsType = llvm::FunctionType::get(builder.getInt32Ty(), // return type
argsRef, // argument vector
false); // no variable number of args
llvm::Constant *putsFunc = module->getOrInsertFunction("puts", putsType);
// call puts(hello_world)
builder.CreateCall(putsFunc, helloWorld);
builder.CreateRetVoid();
module->dump();
}
bool CodeGen::wrapTopLevelBlockInMain(BlockAST *ast) {
// add main to scope
addScope("main");
vector<unique_ptr<ASTNode> > * body = ast->body.get();
// generate void main()
llvm::FunctionType *voidType = llvm::FunctionType::get(Builder.getVoidTy(), false);
llvm::Function *mainFunc =
llvm::Function::Create(voidType, llvm::Function::ExternalLinkage, "main", module.get());
// basic block for the top level block
llvm::BasicBlock *MainBlock = llvm::BasicBlock::Create(context, "entry", mainFunc);
Builder.SetInsertPoint(MainBlock);
llvm::Value * lastExpr;
for (auto it = body->begin() ; it != body->end(); ++it) {
ASTNode * node = it->get();
if (auto x = dynamic_cast<ValueAST*>(node)) {
auto code = generateCodeValue(x);
if (!code) return false;
} else if (auto x = dynamic_cast<DefAST*>(node)) {
generateCodeDef(x);
Builder.SetInsertPoint(MainBlock);
} else if (auto x = dynamic_cast<NumberExprAST*>(node)) {
auto code = generateCodeNumber(x);
if (!code) return false;
lastExpr = code;
} else if (auto x = dynamic_cast<BinaryExprAST*>(node)) {
auto code = generateCodeBinOp(x);
if (!code) return false;
lastExpr = code;
} else if (auto x = dynamic_cast<CallAST*>(node)) {
auto code = generateCodeCall(x);
if (!code) return false;
lastExpr = code;
} else {
error = "can't handle ast";
return false;
}
}
llvm::Value *fmt = Builder.CreateGlobalStringPtr("%lg\n");
vector<llvm::Type *> putsArgs;
putsArgs.push_back(Builder.getInt8Ty()->getPointerTo());
llvm::ArrayRef<llvm::Type*> argsRef(putsArgs);
llvm::FunctionType *putsType =
llvm::FunctionType::get(Builder.getInt32Ty(), argsRef, true);
llvm::Constant *putsFunc = module->getOrInsertFunction("printf", putsType);
vector<llvm::Value *> CallArgs;
CallArgs.push_back(fmt);
CallArgs.push_back(lastExpr);
Builder.CreateCall(putsFunc, CallArgs);
Builder.CreateRetVoid();
string verifyS;
llvm::raw_string_ostream verifyE(verifyS);
if (verifyFunction(*mainFunc, &verifyE)) {
mainFunc->eraseFromParent();
error = "something wrong with auto-generated main function: " + verifyS;
return false;
}
// remove the main scope
removeScope();
return true;
}