feat(backend): Add backend
This commit is contained in:
@@ -0,0 +1,192 @@
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use std::collections::BTreeMap;
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use crate::{backend::{arm_instr::{ARMInstr, AddInstr, BlInstr, LoadInstr, LoadPseudoInstr, MoveInstr, MulInstr, PopInstr, PushInstr, RegisterOrImm, SDivInstr, StoreInstr, SubInstr}, register_allocator::{REG_R0, REG_R1, REG_R2, REG_R3, Register, RegisterAlloc, RegisterAllocator}, types::ARMAsmVar}, ir::types::{Function, IRInstr, MoveRValue, Variable, VariableType}};
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use crate::ir::types::BinaryOp as IRBinaryOp;
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pub const ARM_STACK_ALIGNMENT: usize = 8;
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pub struct Generator {
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instrs: Vec<ARMInstr>,
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var_inited: Vec<ARMAsmVar>,
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var_uninited: Vec<ARMAsmVar>,
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register_allocator: RegisterAllocator,
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}
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impl Generator {
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pub fn new() -> Self {
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Self {
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instrs: Vec::new(),
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var_inited: Vec::new(),
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var_uninited: Vec::new(),
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register_allocator: RegisterAllocator::new(),
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}
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}
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pub fn emit(&mut self, ir_instrs: Vec<IRInstr>) {
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for ir_instr in ir_instrs {
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match ir_instr {
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IRInstr::DefineFunc(func, args, body) => self.emit_func_def(func, args, body),
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IRInstr::Declare(var) => self.emit_global_decl(var),
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_ => unreachable!(),
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}
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}
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}
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pub fn to_text(&self) -> String {
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let mut text = String::new();
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text.push_str(".arch armv7ve
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.arm
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.fpu vfpv4
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.text");
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for var in &self.var_uninited {
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text.push_str(&format!(".comm {}, {}\n", var.name, var.size));
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}
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for var in &self.var_inited {
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text.push_str(&format!(".data\n.align 4\n.global {}\n.type {}, @object\n:{}\n", var.name, var.name, var.name));
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text.push_str(&format!(".word 0\n"));
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}
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for instr in &self.instrs {
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text.push_str(&format!("{}\n", instr));
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}
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text
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}
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fn emit_global_decl(&mut self, var: Variable) {
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self.var_uninited.push(ARMAsmVar {
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name: format!("global_var_{}", var.index),
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size: var.data_type.size_in_bytes(),
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});
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}
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fn emit_func_def(&mut self, func: Function, _args: Vec<Variable>, body: Vec<IRInstr>) {
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self.instrs.push(ARMInstr::FunctionHead(func.name.clone(), 4)); // Assuming 4-byte alignment for simplicity
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self.instrs.push(PushInstr::new_push_fp_lr());
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self.instrs.push(MoveInstr::new_sp_to_fp());
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self.emit_func(body);
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}
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fn emit_func(&mut self, instrs: Vec<IRInstr>) {
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let mut encounter_entry = false;
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let mut stack_size_needed = 0;
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let mut var_index_to_stack_offset = BTreeMap::new();
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for ir_instr in instrs {
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match ir_instr {
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IRInstr::Binary(dest, left, op, right) => self.emit_binary(dest, left, op, right, &var_index_to_stack_offset),
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IRInstr::Exit(v) => {
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self.instrs.push(MoveInstr::new_fp_to_sp());
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self.instrs.push(PopInstr::new_pop_fp_pc());
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},
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IRInstr::FuncCall(func, args, ret) => self.emit_func_call(func, args, ret, &var_index_to_stack_offset),
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IRInstr::Move(dest, src) => self.emit_move(dest, src, &var_index_to_stack_offset),
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IRInstr::Declare(variable) => {
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assert!(!encounter_entry, "Variable declarations must come before entry instruction");
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let size = variable.data_type.size_in_bytes();
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stack_size_needed = (stack_size_needed + size).next_multiple_of(ARM_STACK_ALIGNMENT);
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var_index_to_stack_offset.insert(variable.index, stack_size_needed);
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},
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IRInstr::Entry => {
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assert!(!encounter_entry, "Multiple entry instructions are not allowed");
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encounter_entry = true;
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self.instrs.push(SubInstr::new_sp(stack_size_needed as i32));
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},
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IRInstr::DefineFunc(_, _, _) => unreachable!(),
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}
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}
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}
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fn emit_func_call(&mut self, func: Function, args: Vec<Variable>, ret: Option<Variable>, var_index_to_stack_offset: &BTreeMap<usize, usize>) {
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self.instrs.push(PushInstr::new_push_caller_save());
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if args.len() > 4 {
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todo!("More than 4 arguments not supported yet");
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}
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const ARG_REGS: [Register; 4] = [REG_R0, REG_R1, REG_R2, REG_R3];
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for (i, arg) in args.into_iter().enumerate() {
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let arg_alloc = self.register_allocator.alloc(arg).expect("Ran out of registers");
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let arg_reg = arg_alloc.reg;
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if !arg_alloc.is_reused {
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let arg_stack_offset = var_index_to_stack_offset.get(&arg.index).expect("Variable not declared");
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self.instrs.push(LoadInstr::new_stack(arg_reg, *arg_stack_offset as i32));
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}
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self.instrs.push(MoveInstr::new_uncond(ARG_REGS[i], RegisterOrImm::Reg(arg_reg)));
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}
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self.instrs.push(BlInstr::new(func.name.clone()));
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if let Some(ret) = ret {
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let ret_alloc = self.register_allocator.alloc(ret).expect("Ran out of registers");
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let ret_reg = ret_alloc.reg;
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self.instrs.push(MoveInstr::new_uncond(ret_reg, RegisterOrImm::Reg(REG_R0)));
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}
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self.instrs.push(PopInstr::new_pop_caller_save());
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}
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fn emit_move(&mut self, dest: Variable, src: MoveRValue, var_index_to_stack_offset: &BTreeMap<usize, usize>) {
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let dest_alloc = self.register_allocator.alloc(dest).expect("Ran out of registers");
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let dest_register = dest_alloc.reg;
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match src {
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MoveRValue::Var(variable) => {
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if !dest_alloc.is_reused {
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let var_stack_offset = var_index_to_stack_offset.get(&variable.index).expect("Variable not found");
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self.instrs.push(LoadInstr::new_stack(dest_register, *var_stack_offset as i32));
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}
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},
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MoveRValue::ConstInt(literal_int) => self.instrs.push(MoveInstr::new_uncond(dest_register, RegisterOrImm::Imm(literal_int))),
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};
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match dest.var_type {
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VariableType::Global => {
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let address_reg = self.register_allocator.alloc_any().expect("Ran out of registers");
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self.instrs.push(LoadPseudoInstr::new(address_reg, format!("global_var_{}", dest.index)));
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self.instrs.push(StoreInstr::new(dest_register, address_reg, None));
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},
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VariableType::ParamTemp => {
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todo!()
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},
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_ => {
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let offset = *var_index_to_stack_offset.get(&dest.index).expect("Variable not declared");
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self.instrs.push(StoreInstr::new_stack(dest_register, offset as i32));
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}
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}
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}
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fn emit_binary(&mut self, dest: Variable, left: Variable, op: IRBinaryOp, right: Variable, var_index_to_stack_offset: &BTreeMap<usize, usize>) {
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let left_alloc = self.register_allocator.alloc(left).expect("Ran out of registers");
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let right_alloc = self.register_allocator.alloc(right).expect("Ran out of registers");
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let dest_alloc = self.register_allocator.alloc(dest).expect("Ran out of registers");
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let left_reg = left_alloc.reg;
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let right_reg = right_alloc.reg;
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let dest_reg = dest_alloc.reg;
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if !left_alloc.is_reused {
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let left_offset = var_index_to_stack_offset.get(&left.index).expect("Variable not declared");
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self.instrs.push(LoadInstr::new_stack(left_reg, *left_offset as i32));
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}
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if !right_alloc.is_reused {
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let right_offset = var_index_to_stack_offset.get(&right.index).expect("Variable not declared");
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self.instrs.push(LoadInstr::new_stack(right_reg, *right_offset as i32));
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}
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match op {
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IRBinaryOp::Add => {
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self.instrs.push(AddInstr::new(dest_reg, left_reg, RegisterOrImm::Reg(right_reg)));
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},
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IRBinaryOp::Sub => {
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self.instrs.push(SubInstr::new(dest_reg, left_reg, RegisterOrImm::Reg(right_reg)));
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},
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IRBinaryOp::Mul => {
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self.instrs.push(MulInstr::new(dest_reg, left_reg, RegisterOrImm::Reg(right_reg)));
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},
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IRBinaryOp::Div => {
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self.instrs.push(SDivInstr::new(dest_reg, left_reg, RegisterOrImm::Reg(right_reg)));
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},
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IRBinaryOp::Mod => {
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let temp_reg = self.register_allocator.alloc_any().expect("Ran out of registers");
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self.instrs.push(SDivInstr::new(temp_reg, left_reg, RegisterOrImm::Reg(right_reg)));
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self.instrs.push(MulInstr::new(temp_reg, temp_reg, RegisterOrImm::Reg(right_reg)));
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self.instrs.push(SubInstr::new(dest_reg, left_reg, RegisterOrImm::Reg(temp_reg)));
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},
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IRBinaryOp::Le => todo!(),
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IRBinaryOp::Lt => todo!(),
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IRBinaryOp::Gt => todo!(),
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IRBinaryOp::Ge => todo!(),
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IRBinaryOp::Ne => todo!(),
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IRBinaryOp::Eq => todo!(),
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}
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let dest_stack_offset = var_index_to_stack_offset.get(&dest.index).expect("Variable not declared");
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self.instrs.push(StoreInstr::new_stack(dest_reg, *dest_stack_offset as i32));
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}
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}
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