File size: 7,416 Bytes
1d3f990 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 | //! SUBLEQ Codegen — Bytecode to SUBLEQ memory layout
//!
//! Maps bytecode instructions to SUBLEQ memory layout.
//! Each SUBLEQ instruction: M[b] ← M[b] - M[a]; if M[b] ≤ 0 then IP ← c
use crate::bytecode::*;
use anyhow::{Result, anyhow};
use std::collections::HashMap;
pub struct SubleqCodegen {
memory: Vec<i64>,
next_addr: usize,
register_map: HashMap<Register, usize>, // Reg → Memory address
label_map: HashMap<String, usize>, // Label → Instruction address
}
impl SubleqCodegen {
pub fn new(memory_size: usize) -> Self {
let mut codegen = Self {
memory: vec![0; memory_size],
next_addr: 0,
register_map: HashMap::new(),
label_map: HashMap::new(),
};
// Allocate fixed addresses for registers
// R0-R15 at addresses 0-15
for i in 0..16 {
codegen.register_map.insert(Register(i as u8), i);
}
codegen.next_addr = 16; // Code starts at 16
codegen
}
/// Compile bytecode to SUBLEQ memory layout
pub fn compile(&mut self, bytecode: &Bytecode) -> Result<Vec<i64>> {
// First pass: load constants into high memory
for (idx, val) in bytecode.constants.iter().enumerate() {
let addr = self.allocate_addr();
if let Some(n) = val.as_i64() {
self.memory[addr] = n;
}
}
// Second pass: generate SUBLEQ instructions
for (i, instr) in bytecode.instructions.iter().enumerate() {
self.compile_instr(instr, bytecode)?;
}
// Emit halt instruction at end (suicide: M[0] ← M[0] - M[0])
self.emit_subleq(0, 0, 0);
Ok(self.memory.clone())
}
fn compile_instr(&mut self, instr: &Instr, bytecode: &Bytecode) -> Result<()> {
match instr {
Instr::LoadConst { reg, idx } => {
// Copy constant to register
let const_addr = 16 + idx; // Constants start at 16
let reg_addr = self.get_register_addr(*reg)?;
self.emit_copy(const_addr, reg_addr)?;
}
Instr::Move { dst, src } => {
let src_addr = self.get_register_addr(*src)?;
let dst_addr = self.get_register_addr(*dst)?;
self.emit_copy(src_addr, dst_addr)?;
}
Instr::BinOp { dst, op, src1, src2 } => {
let src1_addr = self.get_register_addr(*src1)?;
let src2_addr = self.get_register_addr(*src2)?;
let dst_addr = self.get_register_addr(*dst)?;
match op {
BinOpCode::Add => self.emit_add(src1_addr, src2_addr, dst_addr)?,
BinOpCode::Sub => self.emit_sub(src1_addr, src2_addr, dst_addr)?,
BinOpCode::Mul => self.emit_mul(src1_addr, src2_addr, dst_addr)?,
_ => return Err(anyhow!("Unsupported binary operation")),
}
}
Instr::Label(label) => {
self.label_map.insert(label.clone(), self.next_addr);
}
Instr::Jump(label) => {
let target_addr = *self.label_map.get(label)
.ok_or_else(|| anyhow!("Undefined label: {}", label))?;
// Unconditional jump: make M[0] <= 0 and jump to target
self.emit_subleq(0, 0, target_addr);
}
Instr::Return(_) => {
// Halt: suicide instruction
self.emit_subleq(0, 0, 0);
}
_ => {}
}
Ok(())
}
/// Emit SUBLEQ instruction: M[b] ← M[b] - M[a]; if M[b] ≤ 0 then IP ← c
fn emit_subleq(&mut self, a: usize, b: usize, c: usize) {
let ip = self.next_addr;
self.memory[ip] = a as i64;
self.memory[ip + 1] = b as i64;
self.memory[ip + 2] = c as i64;
self.next_addr += 3;
}
/// Copy M[src] to M[dst]
fn emit_copy(&mut self, src: usize, dst: usize) -> Result<()> {
// Clear destination: M[dst] ← M[dst] - M[dst]
let next_instr_addr = self.next_addr;
self.emit_subleq(dst, dst, next_instr_addr + 3);
// Decrement source to accumulator: M[acc] ← M[acc] - M[src]
let acc = 16; // Use a temporary accumulator
self.emit_subleq(src, acc, next_instr_addr + 6);
// Decrement accumulator to destination: M[dst] ← M[dst] - M[acc]
self.emit_subleq(acc, dst, next_instr_addr + 9);
// Restore source: M[src] ← M[src] - M[acc] (now negative)
self.emit_subleq(acc, src, next_instr_addr + 12);
Ok(())
}
/// Add src1 + src2 → dst
fn emit_add(&mut self, src1: usize, src2: usize, dst: usize) -> Result<()> {
let temp = 17;
// Clear destination
self.emit_subleq(dst, dst, self.next_addr + 3);
// Copy src1 to destination (modifies src1)
self.emit_copy(src1, dst)?;
// Subtract negative src2 (equivalent to adding)
self.emit_subleq(temp, src2, self.next_addr + 3);
self.emit_subleq(src2, dst, self.next_addr + 3);
Ok(())
}
/// Subtract src1 - src2 → dst
fn emit_sub(&mut self, src1: usize, src2: usize, dst: usize) -> Result<()> {
// Clear destination
self.emit_subleq(dst, dst, self.next_addr + 3);
// Copy src1 to dst
self.emit_copy(src1, dst)?;
// Subtract src2 from dst: M[dst] ← M[dst] - M[src2]
self.emit_subleq(src2, dst, self.next_addr + 3);
Ok(())
}
/// Multiply src1 * src2 → dst (naive implementation)
fn emit_mul(&mut self, src1: usize, src2: usize, dst: usize) -> Result<()> {
let counter = 18;
let temp = 19;
// Clear destination
self.emit_subleq(dst, dst, self.next_addr + 3);
// Copy src2 to counter
self.emit_copy(src2, counter)?;
// Loop: while counter > 0, add src1 to dst
let loop_label = self.next_addr;
self.emit_subleq(counter, counter, self.next_addr + 3);
// If counter <= 0, jump to end
let end_label = self.next_addr + 6;
self.emit_subleq(counter, temp, end_label);
// Add src1 to dst
self.emit_subleq(src1, temp, loop_label);
// Jump back
self.emit_subleq(temp, temp, loop_label);
Ok(())
}
fn get_register_addr(&self, reg: Register) -> Result<usize> {
self.register_map.get(®)
.copied()
.ok_or_else(|| anyhow!("Invalid register"))
}
fn allocate_addr(&mut self) -> usize {
let addr = self.next_addr;
self.next_addr += 1;
addr
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_codegen_create() {
let codegen = SubleqCodegen::new(1024);
assert_eq!(codegen.next_addr, 16);
}
#[test]
fn test_emit_subleq() {
let mut codegen = SubleqCodegen::new(1024);
codegen.emit_subleq(0, 1, 3);
assert_eq!(codegen.memory[0], 0);
assert_eq!(codegen.memory[1], 1);
assert_eq!(codegen.memory[2], 3);
}
}
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