/
mod.rs
128 lines (120 loc) · 5.17 KB
/
mod.rs
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use std::collections::HashMap;
use crate::{ast::model::*, lex::{UnaryOperator, BinaryOperator}, utility::{generate_clause, generate_end, SyntaxError}};
static FUNCTION_PROLOGUE_START: &str = "push\t%rbp\n\tmov\t%rsp, %rbp";
static FUNCTION_PROLOGUE_END: &str = "mov\t%rbp, %rsp\n\tpop\t%rbp\n\tret\n";
pub struct CodeGenerator {
symbol_table: HashMap<String, i64>,
stack_index: i64,
}
impl CodeGenerator {
pub fn new() -> Self {
Self { symbol_table: HashMap::new(), stack_index: 0 }
}
pub fn generate(&mut self, root: &Program) -> Result<String, SyntaxError> {
self.generate_function(&root.func)
}
fn generate_function(&mut self, func: &Function) -> Result<String, SyntaxError> {
let mut body = vec![];
let mut return_flag = false;
for x in &func.body {
let mut st = self.generate_statement(x)?;
st = st.replace("\n", "\n\t");
match x {
Statement::Return(_) => {
st = format!("{}\n\t{}", st, FUNCTION_PROLOGUE_END);
return_flag = true;
},
_ => {}
}
body.push(st);
}
let end = if return_flag {format!("")} else {format!("mov\t$0, %rax\n\t{}", FUNCTION_PROLOGUE_END)};
Ok(format!("
\t.globl {name}
{name}:
\t{start}
\t{body_text}
\t{end}
", start = FUNCTION_PROLOGUE_START, name = func.name, body_text = body.join("\n\t")))
}
fn generate_statement(&mut self, st: &Statement) -> Result<String, SyntaxError> {
match st {
Statement::Return(val) => {
let exp = self.generate_expression(val)?;
Ok(format!("{}", exp))
},
Statement::Declare { name, exp } => {
if self.symbol_table.contains_key(name.as_ref()) {
Err(SyntaxError::new_codegen_error(format!("re-declaration of variable {}", name).to_string()))
}
else {
let mut assembly_exp = self.generate_expression(&Expression::Const(0))?;
if let Some(exp_some) = exp {
assembly_exp = self.generate_expression(exp_some)?;
};
self.stack_index -= 8;
self.symbol_table.insert(name.to_string(), self.stack_index);
Ok(format!("{}\npush\t%rax", assembly_exp))
}
},
Statement::Exp(val) => self.generate_expression(val)
}
}
fn generate_expression(&self, exp: &Expression) -> Result<String, SyntaxError> {
match exp {
Expression::Const(val) => Ok(format!("mov\t${}, %rax", val.to_string())),
Expression::Unary { op, exp } => {
let inner_exp = self.generate_expression(exp)?;
let ext_exp = match op {
UnaryOperator::Negation => format!("neg\t%rax"),
UnaryOperator::BitwiseComplement => format!("not\t%rax"),
UnaryOperator::LogicalNegation => {
format!("cmp\t$0, %rax\nmov\t$0, %rax\nsete\t%al")
}
};
Ok(format!("{}\n{}", inner_exp, ext_exp))
},
Expression::Binary { exp1, op, exp2 } => {
let exp1 = self.generate_expression(exp1)?;
let exp2 = self.generate_expression(exp2)?;
let inner_exp = format!("{}\npush\t%rax\n{}\npop\t%rcx", exp1, exp2);
let ext_exp = match op {
BinaryOperator::Addition => format!("add\t%rcx, %rax"),
BinaryOperator::Multiplication => format!("imul\t%rcx, %rax"),
BinaryOperator::Minus => format!("sub\t%rax, %rcx\nmov\t%rcx, %rax"),
BinaryOperator::Division => format!("mov\t%rax, %rbx\nmov\t%rcx, %rax\ncqo\nidiv\t%rbx"),
BinaryOperator::Equal => format!("cmp\t%rax, %rcx\nsete\t%al"),
BinaryOperator::NotEqual => format!("cmp\t%rax, %rcx\ncmp\t$0, %rax\nsetne\t%al"),
BinaryOperator::LessThan => format!("cmp\t%rax, %rcx\nsetl\t%al"),
BinaryOperator::LessThanOrEqual => format!("cmp\t%rax, %rcx\nsetle\t%al"),
BinaryOperator::GreaterThan => format!("cmp\t%rax, %rcx\nsetg\t%al"),
BinaryOperator::GreaterThanOrEqual => format!("cmp\t%rax, %rcx\nsetge\t%al"),
BinaryOperator::And => {
return Ok(format!("{}\ncmp\t$0, %rax\njne\t{_clause2}\njmp\t{_end}\n{_clause2}:\n{}\ncmp\t$0, %rax\ncmp $0, %rax\nsetne\t%al\n{_end}:", exp1, exp2, _clause2 = generate_clause(), _end = generate_end()));
},
BinaryOperator::Or => {
return Ok(format!("{}\ncmp\t$0, %rax\nje\t{_clause2}\nmov\t$1, %rax\njmp\t{_end}\n{_clause2}:\n{}\ncmp\t$0, %rax\ncmp $0, %rax\nsetne\t%al\n{_end}:", exp1, exp2, _clause2 = generate_clause(), _end = generate_end()));
},
};
Ok(format!("{}\n{}", inner_exp, ext_exp))
},
Expression::Assign { name, exp } => {
match self.symbol_table.get(name.as_ref()) {
None => Err(SyntaxError::new_codegen_error(format!("variable not declared {}", name).to_string())),
Some(&offset) => {
let assign_exp = self.generate_expression(exp)?;
Ok(format!("{}\nmov\t%rax, {}(%rbp)", assign_exp, offset))
}
}
},
Expression::Var { name } => {
match self.symbol_table.get(name.as_ref()) {
None => Err(SyntaxError::new_codegen_error(format!("variable not declared {}", name).to_string())),
Some(&offset) => {
Ok(format!("mov\t{}(%rbp), %rax", offset))
}
}
}
}
}
}