/// Read-Eval-Print-Loop
static void repl(CEnv& cenv, ExecutionEngine* engine)
{
while (1) {
std::cout << "> ";
std::cout.flush();
SExp exp = readExpression(std::cin);
try {
AST* ast = parseExpression(exp);
if (ast->evaluatable()) {
ASTPrototype* proto = new ASTPrototype(false, "", vector<string>());
ASTFunction* func = new ASTFunction(proto, ast);
Function* code = func->Funcgen(cenv);
void* fp = engine->getPointerToFunction(code);
double (*f)() = (double (*)())fp;
std::cout << f() << endl;
} else {
Value* code = ast->Codegen(cenv);
std::cout << "Generated code:" << endl;
code->dump();
}
} catch (SyntaxError e) {
std::cerr << "Syntax error: " << e.what() << endl;
}
}
}
Value* ASTIf::Codegen(CEnv& cenv)
{
Value* condV = _cond->Codegen(cenv);
// Convert condition to a bool by comparing equal to 0.0.
condV = cenv.builder.CreateFCmpONE(
condV, ConstantFP::get(APFloat(0.0)), "ifcond");
Function* parent = cenv.builder.GetInsertBlock()->getParent();
// Create blocks for the then and else cases.
// Insert the 'then' block at the end of the function.
BasicBlock* thenBB = BasicBlock::Create("then", parent);
BasicBlock* elseBB = BasicBlock::Create("else");
BasicBlock* mergeBB = BasicBlock::Create("ifcont");
cenv.builder.CreateCondBr(condV, thenBB, elseBB);
// Emit then value.
cenv.builder.SetInsertPoint(thenBB);
Value* thenV = _then->Codegen(cenv);
cenv.builder.CreateBr(mergeBB);
// Codegen of 'Then' can change the current block, update thenBB
thenBB = cenv.builder.GetInsertBlock();
// Emit else block.
parent->getBasicBlockList().push_back(elseBB);
cenv.builder.SetInsertPoint(elseBB);
Value* elseV = _else->Codegen(cenv);
cenv.builder.CreateBr(mergeBB);
// Codegen of 'Else' can change the current block, update elseBB
elseBB = cenv.builder.GetInsertBlock();
// Emit merge block.
parent->getBasicBlockList().push_back(mergeBB);
cenv.builder.SetInsertPoint(mergeBB);
PHINode* pn = cenv.builder.CreatePHI(Type::DoubleTy, "iftmp");
pn->addIncoming(thenV, thenBB);
pn->addIncoming(elseV, elseBB);
return pn;
}
Function* ASTFunction::Funcgen(CEnv& cenv)
{
cenv.env.clear();
Function* f = _proto->Funcgen(cenv);
// Create a new basic block to start insertion into.
BasicBlock* bb = BasicBlock::Create("entry", f);
cenv.builder.SetInsertPoint(bb);
try {
Value* retVal = _body->Codegen(cenv);
cenv.builder.CreateRet(retVal); // Finish function
verifyFunction(*f); // Validate generated code
cenv.fpm.run(*f); // Optimize function
return f;
} catch (SyntaxError e) {
f->eraseFromParent(); // Error reading body, remove function
throw e;
}
return 0; // Never reached
}