A painful bug - LoadInst error in codegen.cpp - c++

Question

Recently, I've been trying to create a toy language based on an old tutorial. I had this idea almost half a year ago, but I don't have the time to do it until now. Anyway, when I'm following the tutorial, I modified the source code to get rid of a handful of compile errors (I believe that most of the errors are related to backward compatibility), but I'm stuck with feeding the "custom-defined code" to the parser.
The error:
eric#pop-os:~/Desktop/my_toy_compiler-master$ echo 'int do_math(int a){ int x = a * 5 + 3 } do_math(10)' | ./parser
0x55a3e10a7580
Generating code...
Generating code for 20NFunctionDeclaration
Creating variable declaration int a
Generating code for 20NVariableDeclaration
Creating variable declaration int x
Creating assignment for x
Creating binary operation 274
Creating integer: 3
Creating binary operation 276
Creating integer: 5
Creating identifier reference: a
parser: /home/eric/llvm-project/llvm/lib/IR/DataLayout.cpp:740: llvm::Align llvm::DataLayout::getAlignment(llvm::Type*, bool) const: Assertion `Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!"' failed.
Aborted (core dumped)
The problem starts after 'Creating identifier reference: a'. Therefore, it is intuitive to take a look at the relevant code. There are two functions in the codegen.cpp that are considered significant to this bug.
excerpt of codegen.cpp:
...
static Type *typeOf(const NIdentifier& type)
{
if (type.name.compare("int") == 0) {
return Type::getInt64Ty(MyContext);
}
else if (type.name.compare("double") == 0) {
return Type::getDoubleTy(MyContext);
}
return Type::getVoidTy(MyContext);
}
...
Value* NIdentifier::codeGen(CodeGenContext& context)
{
std::cout << "Creating identifier reference: " << name << endl;
if (context.locals().find(name) == context.locals().end()) {
std::cerr << "undeclared variable " << name << endl;
return NULL;
}
return new LoadInst(typeOf(name), context.locals()[name], "", false, context.currentBlock());
}
...
The full version of codegen.cpp:
#include "node.h"
#include "codegen.h"
#include "parser.hpp"
using namespace std;
/* Compile the AST into a module */
void CodeGenContext::generateCode(NBlock& root)
{
std::cout << "Generating code...\n";
/* Create the top level interpreter function to call as entry */
vector<Type*> argTypes;
FunctionType *ftype = FunctionType::get(Type::getVoidTy(MyContext), makeArrayRef(argTypes), false);
mainFunction = Function::Create(ftype, GlobalValue::InternalLinkage, "main", module);
BasicBlock *bblock = BasicBlock::Create(MyContext, "entry", mainFunction, 0);
/* Push a new variable/block context */
pushBlock(bblock);
root.codeGen(*this); /* emit bytecode for the toplevel block */
ReturnInst::Create(MyContext, bblock);
popBlock();
/* Print the bytecode in a human-readable format
to see if our program compiled properly
*/
std::cout << "Code is generated.\n";
// module->dump();
legacy::PassManager pm;
pm.add(createPrintModulePass(outs()));
pm.run(*module);
}
/* Executes the AST by running the main function */
GenericValue CodeGenContext::runCode() {
std::cout << "Running code...\n";
ExecutionEngine *ee = EngineBuilder( unique_ptr<Module>(module) ).create();
ee->finalizeObject();
vector<GenericValue> noargs;
GenericValue v = ee->runFunction(mainFunction, noargs);
std::cout << "Code was run.\n";
return v;
}
/* Returns an LLVM type based on the identifier */
static Type *typeOf(const NIdentifier& type)
{
if (type.name.compare("int") == 0) {
return Type::getInt64Ty(MyContext);
}
else if (type.name.compare("double") == 0) {
return Type::getDoubleTy(MyContext);
}
return Type::getVoidTy(MyContext);
}
/* -- Code Generation -- */
Value* NInteger::codeGen(CodeGenContext& context)
{
std::cout << "Creating integer: " << value << endl;
return ConstantInt::get(Type::getInt64Ty(MyContext), value, true);
}
Value* NDouble::codeGen(CodeGenContext& context)
{
std::cout << "Creating double: " << value << endl;
return ConstantFP::get(Type::getDoubleTy(MyContext), value);
}
Value* NIdentifier::codeGen(CodeGenContext& context)
{
std::cout << "Creating identifier reference: " << name << endl;
if (context.locals().find(name) == context.locals().end()) {
std::cerr << "undeclared variable " << name << endl;
return NULL;
}
return new LoadInst(Type::getInt64Ty(MyContext), context.locals()[name], "", false, context.currentBlock());
}
Value* NMethodCall::codeGen(CodeGenContext& context)
{
Function *function = context.module->getFunction(id.name.c_str());
if (function == NULL) {
std::cerr << "no such function " << id.name << endl;
}
std::vector<Value*> args;
ExpressionList::const_iterator it;
for (it = arguments.begin(); it != arguments.end(); it++) {
args.push_back((**it).codeGen(context));
}
CallInst *call = CallInst::Create(function, makeArrayRef(args), "", context.currentBlock());
std::cout << "Creating method call: " << id.name << endl;
return call;
}
Value* NBinaryOperator::codeGen(CodeGenContext& context)
{
std::cout << "Creating binary operation " << op << endl;
Instruction::BinaryOps instr;
switch (op) {
case TPLUS: instr = Instruction::Add; goto math;
case TMINUS: instr = Instruction::Sub; goto math;
case TMUL: instr = Instruction::Mul; goto math;
case TDIV: instr = Instruction::SDiv; goto math;
/* TODO comparison */
}
return NULL;
math:
return BinaryOperator::Create(instr, lhs.codeGen(context),
rhs.codeGen(context), "", context.currentBlock());
}
Value* NAssignment::codeGen(CodeGenContext& context)
{
std::cout << "Creating assignment for " << lhs.name << endl;
if (context.locals().find(lhs.name) == context.locals().end()) {
std::cerr << "undeclared variable " << lhs.name << endl;
return NULL;
}
return new StoreInst(rhs.codeGen(context), context.locals()[lhs.name], false, context.currentBlock());
}
Value* NBlock::codeGen(CodeGenContext& context)
{
StatementList::const_iterator it;
Value *last = NULL;
for (it = statements.begin(); it != statements.end(); it++) {
std::cout << "Generating code for " << typeid(**it).name() << endl;
last = (**it).codeGen(context);
}
std::cout << "Creating block" << endl;
return last;
}
Value* NExpressionStatement::codeGen(CodeGenContext& context)
{
std::cout << "Generating code for " << typeid(expression).name() << endl;
return expression.codeGen(context);
}
Value* NReturnStatement::codeGen(CodeGenContext& context)
{
std::cout << "Generating return code for " << typeid(expression).name() << endl;
Value *returnValue = expression.codeGen(context);
context.setCurrentReturnValue(returnValue);
return returnValue;
}
Value* NVariableDeclaration::codeGen(CodeGenContext& context)
{
std::cout << "Creating variable declaration " << type.name << " " << id.name << endl;
AllocaInst *alloc = new AllocaInst(typeOf(type), NULL, id.name.c_str(), context.currentBlock());
context.locals()[id.name] = alloc;
if (assignmentExpr != NULL) {
NAssignment assn(id, *assignmentExpr);
assn.codeGen(context);
}
return alloc;
}
Value* NExternDeclaration::codeGen(CodeGenContext& context)
{
vector<Type*> argTypes;
VariableList::const_iterator it;
for (it = arguments.begin(); it != arguments.end(); it++) {
argTypes.push_back(typeOf((**it).type));
}
FunctionType *ftype = FunctionType::get(typeOf(type), makeArrayRef(argTypes), false);
Function *function = Function::Create(ftype, GlobalValue::ExternalLinkage, id.name.c_str(), context.module);
return function;
}
Value* NFunctionDeclaration::codeGen(CodeGenContext& context)
{
vector<Type*> argTypes;
VariableList::const_iterator it;
for (it = arguments.begin(); it != arguments.end(); it++) {
argTypes.push_back(typeOf((**it).type));
}
FunctionType *ftype = FunctionType::get(typeOf(type), makeArrayRef(argTypes), false);
Function *function = Function::Create(ftype, GlobalValue::InternalLinkage, id.name.c_str(), context.module);
BasicBlock *bblock = BasicBlock::Create(MyContext, "entry", function, 0);
context.pushBlock(bblock);
Function::arg_iterator argsValues = function->arg_begin();
Value* argumentValue;
for (it = arguments.begin(); it != arguments.end(); it++) {
(**it).codeGen(context);
argumentValue = &*argsValues++;
argumentValue->setName((*it)->id.name.c_str());
StoreInst *inst = new StoreInst(argumentValue, context.locals()[(*it)->id.name], false, bblock);
}
block.codeGen(context);
ReturnInst::Create(MyContext, context.getCurrentReturnValue(), bblock);
context.popBlock();
std::cout << "Creating function: " << id.name << endl;
return function;
}
Note that there are originally only 3 parameters for the LoadInst function. I checked the llvm::LoadInst Class Reference only to see that the LoadInst function now requires at least 4 parameters. I figured out that I (and the author) missed the Type *Ty parameter. Obviously, typeOf(name) in return new LoadInst(typeOf(name), context.locals()[name], "", false, context.currentBlock()); is not a solution since name, which is 'a' according to the error, will always make typeOf(name) void. I suspect that this causes Cannot getTypeInfo() on a type that is unsized!, as stated by the error.
To be short, I believe that I should look for something like this:
Value* NIdentifier::codeGen(CodeGenContext& context)
{
std::cout << "Creating identifier reference: " << name << endl;
if (context.locals().find(name) == context.locals().end()) {
std::cerr << "undeclared variable " << name << endl;
return NULL;
}
return new LoadInst(*some magic that return the llvm::type of name identifier*, context.locals()[name], "", false, context.currentBlock());
}
I'm still a noob in llvm, so excuse me if my guess isn't correct. Big thanks for any tips or ideas.
P.S. I tried return new LoadInst(Type::getInt64Ty(MyContext), context.locals()[name], "", false, context.currentBlock());. The terminal broke my heart again by saying the follow:
eric#pop-os:~/Desktop/my_toy_compiler-master$ echo 'int do_math(int a){ int x = a * 5 + 3 } do_math(10)' | ./parser
0x562120785580
Generating code...
Generating code for 20NFunctionDeclaration
Creating variable declaration int a
Generating code for 20NVariableDeclaration
Creating variable declaration int x
Creating assignment for x
Creating binary operation 274
Creating integer: 3
Creating binary operation 276
Creating integer: 5
Creating identifier reference: a
Creating block
Creating function: do_math
Generating code for 20NExpressionStatement
Generating code for 11NMethodCall
Creating integer: 10
Creating method call: do_math
Creating block
Code is generated.
; ModuleID = 'main'
source_filename = "main"
#.str = private constant [4 x i8] c"%d\0A\00"
declare i32 #printf(i8*, ...)
define internal void #echo(i64 %toPrint) {
entry:
%0 = call i32 (i8*, ...) #printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* #.str, i32 0, i32 0), i64 %toPrint)
ret void
}
define internal void #main() {
entry:
%0 = call i64 #do_math(i64 10)
ret void
}
define internal i64 #do_math(i64 %a1) {
entry:
%a = alloca i64, align 8
store i64 %a1, i64* %a, align 4
%x = alloca i64, align 8
%0 = load i64, i64* %a, align 4
%1 = mul i64 %0, 5
%2 = add i64 %1, 3
store i64 %2, i64* %x, align 4
ret void
}
Running code...
Function context does not match Module context!
void (i64)* #echo
in function echo
LLVM ERROR: Broken function found, compilation aborted!
Aborted (core dumped)
It's sad that my core is dumped anyway.