500 lines
14 KiB
Rust
500 lines
14 KiB
Rust
use std::{iter::Cycle, mem::offset_of, ops::Range};
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use crate::{
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lexer::{self, Ty},
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parser::{Exp, Function, Item, Literal, Struct, Type},
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};
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//| Register | Description | Saver |
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//|:-----------|:--------------------|:-------|
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//| r0 | Hard-wired zero | N/A |
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//| r1 - r2 | Return values | Caller |
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//| r2 - r11 | Function parameters | Caller |
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//| r12 - r30 | General purpose | Caller |
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//| r31 | Return address | Caller |
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//| r32 - r253 | General purpose | Callee |
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//| r254 | Stack pointer | Callee |
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//| r255 | Thread pointer | N/A |
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const STACK_POINTER: Reg = 254;
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struct RegAlloc {
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pub regs: Box<[Option<usize>; 256]>,
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pub used: Box<[bool; 256]>,
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pub spill_cycle: Cycle<Range<u8>>,
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}
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impl RegAlloc {
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fn alloc_return(&mut self, slot: SlotId) -> Option<Reg> {
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self.regs[1..2]
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.iter_mut()
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.position(|reg| {
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if reg.is_none() {
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*reg = Some(slot);
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true
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} else {
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false
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}
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})
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.map(|reg| reg as Reg + 1)
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}
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fn alloc_general(&mut self, slot: SlotId) -> Option<Reg> {
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self.regs[32..254]
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.iter_mut()
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.zip(&mut self.used[32..254])
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.position(|(reg, used)| {
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if reg.is_none() {
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*reg = Some(slot);
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*used = true;
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true
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} else {
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false
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}
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})
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.map(|reg| reg as Reg + 32)
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}
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fn free(&mut self, reg: Reg) {
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assert!(self.regs[reg as usize].take().is_some());
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}
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fn is_used(&self, reg: Reg) -> bool {
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self.regs[reg as usize].is_some()
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}
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fn spill(&mut self, for_slot: SlotId) -> (Reg, Option<SlotId>) {
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let to_spill = self.spill_cycle.next().unwrap();
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let slot = self.spill_specific(to_spill, for_slot);
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(to_spill as Reg + 32, slot)
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}
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fn spill_specific(&mut self, reg: Reg, for_slot: SlotId) -> Option<SlotId> {
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self.regs[reg as usize].replace(for_slot)
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}
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fn restore(&mut self, reg: Reg, slot: SlotId) -> SlotId {
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self.regs[reg as usize].replace(slot).unwrap()
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}
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fn alloc_specific(&mut self, reg: u8, to: usize) {
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assert!(self.regs[reg as usize].replace(to).is_none());
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}
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}
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pub struct ParamAlloc {
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reg_range: Range<Reg>,
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stack: Offset,
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}
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impl ParamAlloc {
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fn new() -> Self {
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Self {
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stack: 16,
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reg_range: 2..12,
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}
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}
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fn alloc(&mut self, size: usize) -> Value {
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match self.try_alloc_regs(size) {
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Some(reg) => reg,
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None => panic!("Too many arguments o7"),
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}
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}
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fn try_alloc_regs(&mut self, size: usize) -> Option<Value> {
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let mut needed = size.div_ceil(8);
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if needed > 2 {
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needed = 1; // passed by ref
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}
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if self.reg_range.len() < needed {
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return None;
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}
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match needed {
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1 => {
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let reg = self.reg_range.start;
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self.reg_range.start += 1;
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Some(Value::Reg(reg, None, 0))
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}
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2 => {
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let reg = self.reg_range.start;
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self.reg_range.start += 2;
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Some(Value::Reg(reg, Some(reg + 1), 0))
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}
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_ => unreachable!(),
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}
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}
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}
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impl Default for RegAlloc {
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fn default() -> Self {
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Self {
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regs: Box::new([None; 256]),
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used: Box::new([false; 256]),
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spill_cycle: (32..254).cycle(),
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}
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}
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}
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struct Variable {
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name: String,
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location: SlotId,
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}
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type SlotId = usize;
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struct Slot {
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ty: Type,
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value: Value,
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}
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#[repr(transparent)]
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struct InstBuffer {
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buffer: Vec<u8>,
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}
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impl InstBuffer {
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fn new(vec: &mut Vec<u8>) -> &mut Self {
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unsafe { &mut *(vec as *mut Vec<u8> as *mut Self) }
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}
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}
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impl hbbytecode::Buffer for InstBuffer {
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fn reserve(&mut self, bytes: usize) {
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self.buffer.reserve(bytes);
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}
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unsafe fn write(&mut self, byte: u8) {
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self.buffer.push(byte);
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}
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}
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type Reg = u8;
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type Offset = i32;
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type Pushed = bool;
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#[derive(Clone, Copy)]
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enum Value {
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Reg(Reg, Option<Reg>, Offset),
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Stack(Offset, Pushed),
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Imm(u64),
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Spilled(Reg, SlotId, Option<Reg>, Option<SlotId>, Offset),
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DoubleSpilled(SlotId, Offset, Option<SlotId>),
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}
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#[derive(Clone, Copy)]
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enum NormalizedValue {
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Reg(Reg, Option<Reg>, Offset),
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Stack(Offset, Pushed),
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Imm(u64),
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}
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impl From<Value> for NormalizedValue {
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fn from(value: Value) -> Self {
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match value {
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Value::Reg(reg, secondary, offset) => NormalizedValue::Reg(reg, secondary, offset),
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Value::Stack(offset, pushed) => NormalizedValue::Stack(offset, pushed),
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Value::Imm(imm) => NormalizedValue::Imm(imm),
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Value::Spilled(reg, _, secondary, _, offset) => {
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NormalizedValue::Reg(reg, secondary, offset)
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}
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Value::DoubleSpilled(_, offset, _) => NormalizedValue::Stack(offset, false),
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}
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}
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}
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type Label = usize;
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type Data = usize;
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pub struct LabelReloc {
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pub label: Label,
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pub offset: usize,
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}
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pub struct DataReloc {
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pub data: Data,
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pub offset: usize,
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}
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#[must_use]
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pub struct Frame {
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pub slot_count: usize,
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pub var_count: usize,
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}
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enum Instr {
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BinOp(lexer::Op, NormalizedValue, NormalizedValue),
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Move(usize, NormalizedValue, NormalizedValue),
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Jump(Label),
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JumpIfZero(NormalizedValue, Label),
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}
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#[derive(Default)]
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pub struct Generator<'a> {
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ast: &'a [Item],
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func_labels: Vec<(String, Label)>,
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stack_size: usize,
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pushed_size: usize,
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regs: RegAlloc,
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variables: Vec<Variable>,
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slots: Vec<Slot>,
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labels: Vec<Option<usize>>,
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label_relocs: Vec<LabelReloc>,
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data: Vec<Option<usize>>,
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data_relocs: Vec<DataReloc>,
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code_section: Vec<u8>,
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data_section: Vec<u8>,
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instrs: Vec<Instr>,
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}
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impl<'a> Generator<'a> {
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fn generate(mut self) -> Vec<u8> {
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for item in self.ast {
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let Item::Function(f) = item else { continue };
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self.generate_function(f);
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}
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self.link()
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}
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fn generate_function(&mut self, f: &Function) {
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let frame = self.push_frame();
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let mut param_alloc = ParamAlloc::new();
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for param in f.args.iter() {
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let param_size = self.size_of(¶m.ty);
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let value = param_alloc.alloc(param_size);
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let slot = self.add_slot(param.ty.clone(), value);
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self.allocate_value_regs(value, slot);
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self.add_variable(param.name.clone(), slot);
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}
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for stmt in f.body.iter() {
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assert!(self
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.generate_expr(Some(Type::Builtin(Ty::Void)), stmt)
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.is_none());
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}
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self.pop_frame(frame);
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}
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fn allocate_value_regs(&mut self, value: Value, to: SlotId) {
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if let Value::Reg(primary, secondary, _) = value {
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self.regs.alloc_specific(primary, to);
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if let Some(secondary) = secondary {
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self.regs.alloc_specific(secondary, to);
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}
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}
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}
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fn generate_expr(&mut self, expected: Option<Type>, expr: &Exp) -> Option<SlotId> {
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let value = match expr {
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Exp::Literal(lit) => match lit {
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Literal::Int(i) => self.add_slot(expected.clone().unwrap(), Value::Imm(*i)),
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Literal::Bool(b) => self.add_slot(Type::Builtin(Ty::Bool), Value::Imm(*b as u64)),
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},
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Exp::Variable(ident) => self.lookup_variable(ident).unwrap().location,
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Exp::Call { name, args } => self.generate_call(expected.clone(), name, args),
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Exp::Ctor { name, fields } => todo!(),
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Exp::Index { base, index } => todo!(),
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Exp::Field { base, field } => todo!(),
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Exp::Unary { op, exp } => todo!(),
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Exp::Binary { op, left, right } => todo!(),
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Exp::If { cond, then, else_ } => todo!(),
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Exp::Let { name, ty, value } => todo!(),
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Exp::For {
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init,
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cond,
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step,
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block,
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} => todo!(),
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Exp::Block(_) => todo!(),
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Exp::Return(_) => todo!(),
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Exp::Break => todo!(),
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Exp::Continue => todo!(),
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};
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if let Some(expected) = expected {
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let actual = self.slots[value].ty.clone();
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assert_eq!(expected, actual);
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}
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Some(value)
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}
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fn generate_call(&mut self, expected: Option<Type>, name: &str, args: &[Exp]) -> SlotId {
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let frame = self.push_frame();
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let func = self.lookup_function(name);
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let mut arg_alloc = ParamAlloc::new();
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for (arg, param) in args.iter().zip(&func.args) {
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let arg_slot = self.generate_expr(Some(param.ty.clone()), arg).unwrap();
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let arg_size = self.size_of(¶m.ty);
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let param_slot = arg_alloc.alloc(arg_size);
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self.set_temporarly(arg_slot, param_slot);
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}
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todo!()
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}
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fn set_temporarly(&mut self, from: SlotId, to: Value) {
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match to {
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Value::Reg(dst, secondary, offset) => {
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let other_slot = secondary.and_then(|s| self.regs.spill_specific(s, usize::MAX));
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if let Some(slot) = self.regs.spill_specific(dst, usize::MAX) {
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self.slots[slot].value =
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Value::Spilled(dst, slot, secondary, other_slot, offset);
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} else if let Some(slot) = other_slot {
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self.slots[slot].value =
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Value::Spilled(secondary.unwrap(), slot, Some(dst), None, offset);
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}
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}
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_ => unreachable!(),
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};
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let size = self.size_of(&self.slots[from].ty);
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self.emit_move(size, self.slots[from].value, to);
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}
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fn emit_move(&mut self, size: usize, from: Value, to: Value) {
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self.instrs.push(Instr::Move(size, from.into(), to.into()));
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}
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fn size_of(&self, ty: &Type) -> usize {
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match ty {
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Type::Builtin(ty) => match ty {
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Ty::U8 | Ty::I8 | Ty::Bool => 1,
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Ty::U16 | Ty::I16 => 2,
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Ty::U32 | Ty::I32 => 4,
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Ty::U64 | Ty::I64 => 8,
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Ty::Void => 0,
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},
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Type::Struct(name) => self
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.lookup_struct(name)
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.fields
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.iter()
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.map(|field| self.size_of(&field.ty))
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.sum(),
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Type::Pinter(_) => 8,
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}
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}
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fn add_variable(&mut self, name: String, location: SlotId) {
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self.variables.push(Variable { name, location });
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}
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fn add_slot(&mut self, ty: Type, value: Value) -> SlotId {
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let slot = self.slots.len();
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self.slots.push(Slot { ty, value });
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slot
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}
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fn link(mut self) -> Vec<u8> {
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for reloc in self.label_relocs {
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let label = self.labels[reloc.label].unwrap();
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let offset = reloc.offset;
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let target = label - offset;
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let target_bytes = u64::to_le_bytes(target as u64);
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self.code_section[offset..offset + 8].copy_from_slice(&target_bytes);
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}
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for reloc in self.data_relocs {
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let data = self.data[reloc.data].unwrap();
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let offset = reloc.offset;
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let target = data;
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let target_bytes = u64::to_le_bytes((target + self.code_section.len()) as u64);
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self.data_section[offset..offset + 8].copy_from_slice(&target_bytes);
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}
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self.code_section.extend_from_slice(&self.data_section);
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self.code_section
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}
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fn lookup_func_label(&mut self, name: &str) -> Label {
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if let Some(label) = self.func_labels.iter().find(|(n, _)| n == name) {
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return label.1;
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}
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panic!("Function not found: {}", name);
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}
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fn declare_label(&mut self) -> Label {
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self.labels.push(None);
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self.labels.len() - 1
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}
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fn define_label(&mut self, label: Label) {
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self.labels[label] = Some(self.code_section.len());
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}
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fn declare_data(&mut self) -> Data {
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self.data.push(None);
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self.data.len() - 1
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}
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fn define_data(&mut self, data: Data, bytes: &[u8]) {
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self.data[data] = Some(self.data.len());
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self.data_section.extend_from_slice(bytes);
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}
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fn lookup_struct(&self, name: &str) -> &Struct {
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self.lookup_item(name)
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.map(|item| match item {
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Item::Struct(s) => s,
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_ => panic!("Not a struct: {}", name),
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})
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.expect("Struct not found")
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}
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fn lookup_function(&self, name: &str) -> &'a Function {
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self.lookup_item(name)
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.map(|item| match item {
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Item::Function(f) => f,
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_ => panic!("Not a function: {}", name),
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})
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.expect("Function not found")
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}
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fn lookup_item(&self, name: &str) -> Option<&'a Item> {
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self.ast.iter().find(|item| match item {
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Item::Import(_) => false,
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Item::Struct(s) => s.name == name,
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Item::Function(f) => f.name == name,
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})
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}
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fn lookup_variable(&self, name: &str) -> Option<&Variable> {
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self.variables.iter().find(|variable| variable.name == name)
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}
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fn push_frame(&mut self) -> Frame {
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Frame {
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slot_count: self.slots.len(),
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var_count: self.variables.len(),
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}
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}
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fn pop_frame(&mut self, frame: Frame) {
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self.slots.truncate(frame.slot_count);
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self.variables.truncate(frame.var_count);
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}
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}
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pub fn generate(ast: &[Item]) -> Vec<u8> {
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Generator {
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ast,
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..Default::default()
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}
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.generate()
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}
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