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semantic_analysis.cpp
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semantic_analysis.cpp
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#include <cassert>
#include <algorithm>
#include <memory>
#include <utility>
#include "grammar_symbols.h"
#include "parse.tab.h"
#include "node.h"
#include "ast.h"
#include "exceptions.h"
#include "semantic_analysis.h"
SemanticAnalysis::SemanticAnalysis()
: m_global_symtab(new SymbolTable(nullptr, "root")) {
m_cur_symtab = m_global_symtab;
}
SemanticAnalysis::~SemanticAnalysis() {
}
void SemanticAnalysis::visit_struct_type(Node *n) {
// If struct doesn't exist, declare it
if (m_cur_symtab->has_symbol_recursive("struct " + n->get_kid(0)->get_str())) {
std::shared_ptr<Type> p = m_cur_symtab->lookup_recursive("struct " + n->get_kid(0)->get_str())->get_type();
n->set_type(p);
} else {
SemanticError::raise(n->get_loc(), "Unknown Struct");
}
}
void SemanticAnalysis::visit_union_type(Node *n) {
RuntimeError::raise("union types aren't supported");
}
void SemanticAnalysis::visit_variable_declaration(Node *n) {
// visit type
visit(n->get_kid(1));
// iterate through declarators
for (unsigned i = 0; i < n->get_kid(2)->get_num_kids(); i++) {
// the current declarator
std::shared_ptr<Type> p;
Node * current = n->get_kid(2)->get_kid(i);
// annotate it with its type. recursively
type_switcher(current ,n->get_kid(1)->get_type());
p = current->get_type();
// add it to the Symbol Table
if (m_cur_symtab->has_symbol_local(current->get_kid(0)->get_str())) {
SemanticError::raise(n->get_loc(), "Variable %s already exists", current->get_kid(0)->get_str().c_str());
}
current->clear_type_for_symbol(m_cur_symtab->define(SymbolKind::VARIABLE,current->get_kid(0)->get_str(),p));
}
}
/// Annotate a layered type in the leaf node
/// \param declare pointer to the declarator
/// \param type pointer to the base type node
void SemanticAnalysis::type_switcher(Node *declare, const std::shared_ptr<Type>& type) {
switch (declare->get_tag()) {
case AST_NAMED_DECLARATOR:
declare->set_type(type);
break;
case AST_POINTER_DECLARATOR:
type_switcher(declare->get_kid(0), type);
declare->set_type(declare->get_kid(0)->get_type());
// Possibly remove, dependant on https://courselore.org/courses/5505975532/conversations/100
// To me this is the result of a parser logical error, which means that the Pointer AST node
// is above the array AST node, but fixing that is beyond my scope.
if (declare->get_type()->is_array()) {
unsigned size = declare->get_type()->get_array_size();
declare->un_array();
declare->make_pointer();
declare->make_array(size);
} else {
declare->make_pointer();
}
break;
case AST_ARRAY_DECLARATOR:
type_switcher(declare->get_kid(0), type);
declare->set_type(declare->get_kid(0)->get_type());
declare->make_array(stoi(declare->get_kid(1)->get_str()));
break;
}
// Move variable name up the chain
declare->set_str(declare->get_kid(0)->get_str());
}
void SemanticAnalysis::visit_basic_type(Node *n) {
if (n->get_num_kids() == 0) {
SemanticError::raise(n->get_loc(), "No Type specified");
}
// Find a void, if so make sure it is the only keyword
for (unsigned i = 0; i < n->get_num_kids(); i++) {
if (n->get_kid(i)->get_tag() == TOK_VOID) {
if (n->get_num_kids() == 1) {
// void always signed
std::shared_ptr<Type> p(new BasicType(BasicTypeKind::VOID, true));
n->set_type(p);
return;
}
SemanticError::raise(n->get_loc(), "Cannot have qualifiers on void type");
}
}
// Find any type specifiers
int type = 0;
for (unsigned i = 0; i < n->get_num_kids(); i++) {
if (n->get_kid(i)->get_tag() == TOK_SHORT) {
type = 1;
}
if (n->get_kid(i)->get_tag() == TOK_LONG) {
type = 2;
}
}
int sign = 0;
bool a_char = false;
// Find if char, also looking for signing if present
for (unsigned i = 0; i < n->get_num_kids(); i++) {
if (n->get_kid(i)->get_tag() == TOK_CHAR) {
a_char = true;
}
if (n->get_kid(i)->get_tag() == TOK_UNSIGNED) {
sign = 1;
}
if (n->get_kid(i)->get_tag() == TOK_SIGNED) {
sign = 2;
}
}
// if long or short specify type
BasicTypeKind kind = BasicTypeKind::INT;
switch (type) {
case 0:
break;
case 1:
kind = BasicTypeKind::SHORT;
break;
case 2:
kind = BasicTypeKind::LONG;
break;
default:;
}
// if it's a char, make sure it's not long or short
if (a_char) {
if (type != 0) {
SemanticError::raise(n->get_loc(), "Cannot specify long or short with char");
}
else {
kind = BasicTypeKind::CHAR;
}
}
// BaseType and Sign already determined
std::shared_ptr<Type> p(new BasicType(kind, is_signed(sign)));
// Check for Qualified types which are always first
if (n->get_kid(0)->get_tag() == TOK_VOLATILE) {
std::shared_ptr<QualifiedType> sub(new QualifiedType(p, TypeQualifier::VOLATILE));
n->set_type(sub);
} else if (n->get_kid(0)->get_tag() == TOK_CONST) {
std::shared_ptr<QualifiedType> sub(new QualifiedType(p, TypeQualifier::CONST));
n->set_type(sub);
} else {
n->set_type(p);
}
}
bool SemanticAnalysis::is_signed(int sign) {
// This is necessary because sign has 3 possible positions, so can't use bool
if (sign == 1) {
return false;
}
return true;
}
void SemanticAnalysis::visit_function_definition(Node *n) {
// redeclare function
visit_function_declaration(n);
// Define params in new scope, making the function scope be named after the function, allowing return type checking
enter_scope(n->get_kid(1)->get_str());
define_parameters(n);
// Statement list
visit(n->get_kid(3));
leave_scope();
}
void SemanticAnalysis::define_parameters(Node *n) {
std::shared_ptr<Type> params = n->get_kid(0)->get_type();
for (unsigned i = 0; i < params->get_num_members(); i++) {
Member param = params->get_member(i);
if (m_cur_symtab->has_symbol_local(param.get_name())) {
SemanticError::raise(n->get_loc(), "Cannot have 2 params of the same name");
}
// add to local scope
m_cur_symtab->define(n->get_kid(2)->get_kid(i)->get_symbol());
}
}
void SemanticAnalysis::visit_function_declaration(Node *n) {
// visit function type
visit(n->get_kid(0));
Node * params = n->get_kid(2);
// visit parameters
visit_children(params);
n->get_kid(0)->make_function();
for (unsigned i = 0; i < params->get_num_kids(); i++) {
auto *mem = new Member(params->get_kid(i)->get_str(), params->get_kid(i)->get_kid(1)->get_type());
n->get_kid(0)->get_type()->add_member(*mem);
}
if (m_cur_symtab->has_symbol_local(n->get_kid(1)->get_str())) {
SemanticError::raise(n->get_loc(), "Function with same name declared in same scope");
}
Symbol *sym = m_cur_symtab->declare(SymbolKind::FUNCTION, n->get_kid(1)->get_str(), n->get_kid(0)->get_type());
n->set_symbol(sym);
}
void SemanticAnalysis::visit_function_parameter(Node *n) {
// Get type
visit(n->get_kid(0));
type_switcher(n->get_kid(1), n->get_kid(0)->get_type());
n->set_str(n->get_kid(1)->get_kid(0)->get_str());
auto *sym = new Symbol (SymbolKind::VARIABLE, n->get_str(), n->get_kid(1)->get_type(), m_cur_symtab, false);
n->set_symbol(sym);
}
void SemanticAnalysis::visit_statement_list(Node *n) {
enter_scope(m_cur_symtab->get_name());
visit_children(n);
leave_scope();
}
void SemanticAnalysis::visit_struct_type_definition(Node *n) {
std::string name = n->get_kid(0)->get_str();
if(m_cur_symtab->has_symbol_recursive("struct " + name)) {
SemanticError::raise(n->get_loc(), "Struct already defined");
}
std::shared_ptr<Type> struct_type(new StructType(name));
Symbol * struct_local = m_cur_symtab->define(SymbolKind::TYPE, "struct " + name, struct_type);
enter_scope("struct");
Node * fields = n->get_kid(1);
for (unsigned i = 0; i < fields->get_num_kids(); i++) {
visit(fields->get_kid(i));
}
for (unsigned i = 0; i < m_cur_symtab->get_num_symbols(); i++) {
Symbol * sym = m_cur_symtab->get_symbol(i);
Member mem(sym->get_name(), sym->get_type());
struct_type->add_member(mem);
}
leave_scope();
fields->get_kid(0)->get_kid(2)->set_str(name);
fields->get_kid(0)->get_kid(2)->set_symbol(struct_local);
}
void SemanticAnalysis::visit_binary_expression(Node *n) {
// visit left
visit(n->get_kid(1));
// visit right
visit(n->get_kid(2));
switch (n->get_kid(0)->get_tag()) {
case TOK_ASSIGN:
if (n->get_kid(1)->get_tag() == AST_BINARY_EXPRESSION || n->get_kid(1)->get_tag() == AST_LITERAL_VALUE) {
SemanticError::raise(n->get_loc(), "Tried to assign to non-lvalue");
}
visit_assign(n);
break;
case TOK_PLUS:
case TOK_MINUS:
case TOK_DIVIDE:
case TOK_ASTERISK:
visit_math(n);
break;
case TOK_LT:
case TOK_LTE:
case TOK_GT:
case TOK_GTE:
case TOK_EQUALITY:
case TOK_LOGICAL_AND:
case TOK_LOGICAL_OR:
visit_comparison(n);
break;
}
// annotate with type of result
n->set_type( n->get_kid(1)->get_type());
}
void SemanticAnalysis::visit_assign(Node *n) {
std::shared_ptr<Type> lhs = n->get_kid(1)->get_type();
std::shared_ptr<Type> rhs = n->get_kid(2)->get_type();
// Not base types
if (!lhs->is_basic() && !rhs->is_basic()) {
if (!lhs->get_base_type()->is_volatile() && rhs->get_base_type()->is_volatile()) {
SemanticError::raise(n->get_loc(), "Tried to assign volatile variable to non-volatile variable");
}
if (rhs->get_base_type()->is_const()) {
SemanticError::raise(n->get_loc(), "Tried to assign const to non-const variable");
}
if (lhs->is_pointer() && rhs->is_integral()) {
SemanticError::raise(n->get_loc(), "Cannot assign integral to pointer");
}
}
if (!lhs->is_basic() && rhs->is_basic()) {
if (lhs->is_pointer()) {
if (!lhs->get_base_type()->is_struct() && !lhs->get_base_type()->is_array() && !lhs->get_base_type()->is_pointer()) {
SemanticError::raise(n->get_loc(), "Cannot assign integral to pointer");
}
}
}
// Not lvalue
if (!lhs->is_integral()) {
if (!(n->get_kid(1)->has_symbol() || lhs->is_pointer() || lhs->is_array() || lhs->is_struct() || lhs->is_same(rhs.get()) )) {
SemanticError::raise(n->get_loc(), "Left hand side is not an L-Value");
}
}
// Const error
if (lhs->is_const()) {
SemanticError::raise(n->get_loc(), "Tried to assign value to const variable");
}
// Cannot do arr = arr
if (lhs->is_array() && rhs->is_array()) {
SemanticError::raise(n->get_loc(), "Tried to assign array to array");
}
// bad pointer assignments
if (lhs->is_pointer()) {
if (!rhs->is_pointer() && !rhs->is_array() && !rhs->is_integral()) {
SemanticError::raise(n->get_loc(), "Tried to assign non pointer to pointer");
}
}
if (lhs->is_struct() || rhs->is_struct()) {
if ((lhs->is_struct() != rhs->is_struct() ) && !lhs->is_pointer()) {
SemanticError::raise(n->get_loc(), "Tried to assign struct to non struct");
}
} else {
if (lhs->is_integral() && !rhs->is_integral()) {
SemanticError::raise(n->get_loc(), "Tried to assign non integer to integer");
}
}
}
void SemanticAnalysis::visit_math(Node *n) {
std::shared_ptr<Type> lhs = n->get_kid(1)->get_type();
if (lhs->is_integral() && lhs->get_basic_type_kind() < BasicTypeKind::INT) {
// Promote operand if necessary
n->set_kid(1, promote_to_int(n->get_kid(1)));
lhs = n->get_kid(1)->get_type();
}
std::shared_ptr<Type> rhs = n->get_kid(2)->get_type();
if (lhs->is_void() || rhs->is_void()) {
SemanticError::raise(n->get_loc(), "Cannot do math on Void type");
}
if (rhs->is_pointer() && !lhs->is_pointer()) {
SemanticError::raise(n->get_loc(), "Cannot have pointer on right hand side of equation");
}
}
void SemanticAnalysis::visit_comparison(Node *n) {
std::shared_ptr<Type> lhs = n->get_kid(1)->get_type();
std::shared_ptr<Type> rhs = n->get_kid(2)->get_type();
if (lhs->is_pointer() != rhs->is_pointer()) {
SemanticError::raise(n->get_loc(), "Tried to compare pointer and non pointer");
}
if (lhs->is_function() != rhs->is_function()) {
SemanticError::raise(n->get_loc(), "Tried to compare function and non function");
}
if (lhs->is_struct() != rhs->is_struct()) {
SemanticError::raise(n->get_loc(), "Tried to compare struct and non struct");
}
}
void SemanticAnalysis::visit_unary_expression(Node *n) {
visit(n->get_kid(1));
n->set_type(n->get_kid(1)->get_type());
if (n->get_kid(0)->get_tag() == TOK_AMPERSAND) {
if (n->get_kid(1)->get_tag() == AST_LITERAL_VALUE) {
SemanticError::raise(n->get_loc(), "Tried to reference a literal");
}
n->make_pointer();
n->get_kid(1)->get_symbol()->take_address();
} else if (n->get_kid(0)->get_tag() == TOK_ASTERISK) {
n->make_pointer();
}
}
void SemanticAnalysis::visit_postfix_expression(Node *n) {
// None of these three appear in any example, and frankly I don't even know what they look like
}
void SemanticAnalysis::visit_conditional_expression(Node *n) {
// None of these three appear in any example, and frankly I don't even know what they look like
}
void SemanticAnalysis::visit_cast_expression(Node *n) {
// None of these three appear in any example, and frankly I don't even know what they look like
}
void SemanticAnalysis::visit_function_call_expression(Node *n) {
// visit name
visit(n->get_kid(0));
Symbol *func = m_cur_symtab->lookup_recursive(n->get_kid(0)->get_symbol()->get_name());
if (func == nullptr) {
SemanticError::raise(n->get_loc(), "Function %s does not exist", n->get_kid(0)->get_symbol()->get_name().c_str());
}
// visit args
if (func->get_type()->get_num_members() != n->get_kid(1)->get_num_kids()) {
SemanticError::raise(n->get_loc(), "Number of arguments does not match number of parameters");
}
for (unsigned i = 0; i < func->get_type()->get_num_members(); i++) {
visit(n->get_kid(1)->get_kid(i));
std::shared_ptr<Type> arg = n->get_kid(1)->get_kid(i)->get_type();
std::shared_ptr<Type> param = func->get_type()->get_member(i).get_type();
// Comparing symbol member type to regular type doesn't work, even when the BaseTypeKind is the same
if (!(check_different(arg, param))) {
SemanticError::raise(n->get_loc(), "Argument type does not match parameter type");
}
}
n->set_type(func->get_type()->get_base_type());
}
bool SemanticAnalysis::check_different(const std::shared_ptr<Type>& a, const std::shared_ptr<Type>& b) {
// Clean Param vs Arg dif checker
if (a->is_pointer() != b->is_pointer() || a->is_array() != b->is_array()) {
if ((a->is_pointer() && b->is_array()) || (a->is_array() && b->is_pointer())){
return true;
}
return false;
} else if (a->is_struct() != b->is_struct()) {
return false;
}
if (a->is_basic() != b->is_basic()) {
if (a->get_basic_type_kind() != b->get_basic_type_kind()) {
return false;
}
return false;
}
return true;
}
void SemanticAnalysis::visit_field_ref_expression(Node *n) {
visit(n->get_kid(0));
Symbol * base_struct = n->get_kid(0)->get_symbol();
if (base_struct->get_type()->is_pointer()) {
SemanticError::raise(n->get_loc(), "Direct reference to pointer");
}
std::shared_ptr<Type> field_type = base_struct->get_type()->find_member(n->get_kid(1)->get_str())->get_type();
n->set_type(field_type);
// if it's an array of char's it's actually a pointer to char's
if (field_type->is_array() && field_type->get_base_type()->get_basic_type_kind() == BasicTypeKind::CHAR) {
n->make_pointer();
}
}
void SemanticAnalysis::visit_indirect_field_ref_expression(Node *n) {
// This and the above function are almost identical since they are virtual and thus cannot have default values
visit(n->get_kid(0));
std::shared_ptr<Type> var = n->get_kid(0)->get_type();
// If it's a pointer, which it should be
if (var->is_pointer()) {
// Dereference it, so that the correct base type is passed up the chain
var = var->get_base_type();
} else {
SemanticError::raise(n->get_loc(), "Indirect reference to non-pointer");
}
std::shared_ptr<Type> field_type = var->find_member(n->get_kid(1)->get_str())->get_type();
n->set_type(field_type);
}
void SemanticAnalysis::visit_array_element_ref_expression(Node *n) {
visit(n->get_kid(0));
visit(n->get_kid(1));
n->set_type(n->get_kid(0)->get_type());
if (n->get_type()->is_pointer()) {
n->un_pointer();
}
if (n->get_type()->is_array()) {
n->un_array();
}
}
void SemanticAnalysis::visit_variable_ref(Node *n) {
// annotate with symbol
if (m_cur_symtab->has_symbol_recursive(n->get_kid(0)->get_str())) {
n->set_symbol(m_cur_symtab->lookup_recursive(n->get_kid(0)->get_str()));
} else if (m_cur_symtab->has_symbol_recursive("struct " + n->get_kid(0)->get_str())) {
// Must also search in structs
n->set_symbol(m_cur_symtab->lookup_recursive("struct " + n->get_kid(0)->get_str()));
} else {
SemanticError::raise(n->get_loc(), "Variable %s does not exist in Symbol Table", n->get_kid(0)->get_str().c_str());
}
}
void SemanticAnalysis::visit_literal_value(Node *n) {
std::shared_ptr<Type> p;
switch (n->get_kid(0)->get_tag()) {
case TOK_INT_LIT: {
LiteralValue lit = LiteralValue::from_int_literal(n->get_kid(0)->get_str(), n->get_loc());
p = static_cast<const std::shared_ptr<Type>>(new BasicType((lit.is_long()) ? BasicTypeKind::LONG : BasicTypeKind::INT, !lit.is_unsigned()));
n->set_type(p);
n->set_literal_value(lit);
break;
}
case TOK_CHAR_LIT: {
LiteralValue lit = LiteralValue::from_char_literal(n->get_kid(0)->get_str(), n->get_loc());
p = static_cast<const std::shared_ptr<Type>>(new BasicType(BasicTypeKind::CHAR, true));
n->set_type(p);
n->set_literal_value(lit);
break;
}
case TOK_STR_LIT:{
LiteralValue lit = LiteralValue::from_str_literal(n->get_kid(0)->get_str(), n->get_loc());
p = static_cast<const std::shared_ptr<Type>>(new BasicType(BasicTypeKind::CHAR, true));
n->set_type(p);
// this is just a char pointer so
n->make_pointer();
n->set_literal_value(lit);
}
}
}
void SemanticAnalysis::visit_return_expression_statement(Node *n) {
visit(n->get_kid(0));
std::shared_ptr<Type> return_type = m_cur_symtab->lookup_recursive(m_cur_symtab->get_name(), SymbolKind::FUNCTION)->get_type()->get_base_type();
// check name of symbol table
if (!return_type->is_same(n->get_kid(0)->get_type().get())) {
SemanticError::raise(n->get_loc(), "Return type does not match function declaration");
}
}
Node *SemanticAnalysis::promote_to_int(Node *n) {
assert(n->get_type()->is_integral());
assert(n->get_type()->get_basic_type_kind() < BasicTypeKind::INT);
std::shared_ptr<Type> type(new BasicType(BasicTypeKind::INT, n->get_type()->is_signed()));
return implicit_conversion(n, type);
}
Node *SemanticAnalysis::implicit_conversion(Node *n, const std::shared_ptr<Type> &type) {
std::unique_ptr<Node> conversion(new Node(AST_IMPLICIT_CONVERSION, {n}));
conversion->set_type(type);
return conversion.release();
}
void SemanticAnalysis::enter_scope(std::string name) {
auto *scope = new SymbolTable(m_cur_symtab, std::move(name));
m_cur_symtab = scope;
}
void SemanticAnalysis::leave_scope() {
SymbolTable * temp = m_cur_symtab;
m_cur_symtab = m_cur_symtab->get_parent();
delete temp;
assert(m_cur_symtab != nullptr);
}