use crate::ParserOptions;
use alloc::vec::Vec;
use tinywasm_types::{Instruction, WasmFunctionData};
pub(crate) fn optimize_instructions(
mut instructions: Vec<Instruction>,
function_data: &mut WasmFunctionData,
self_func_addr: u32,
options: &ParserOptions,
) -> Vec<Instruction> {
rewrite(&mut instructions, self_func_addr);
if options.dce {
dce(&mut instructions, function_data);
}
instructions
}
fn rewrite(instructions: &mut [Instruction], self_func_addr: u32) {
for read in 0..instructions.len() {
match instructions[read] {
Instruction::LocalCopy32(a, b) if a == b => instructions[read] = Instruction::Nop,
Instruction::LocalCopy64(a, b) if a == b => instructions[read] = Instruction::Nop,
Instruction::LocalCopy128(a, b) if a == b => instructions[read] = Instruction::Nop,
Instruction::Call(addr) if addr == self_func_addr => instructions[read] = Instruction::CallSelf,
Instruction::ReturnCall(addr) if addr == self_func_addr => instructions[read] = Instruction::ReturnCallSelf,
Instruction::I32Add => {
if read > 1
&& let (Instruction::LocalGet32(a), Instruction::LocalGet32(b)) =
(instructions[read - 2], instructions[read - 1])
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32AddLocals(a, b);
}
if read > 0 {
match instructions[read - 1] {
Instruction::I32Const(c) if read > 1 => {
if let Instruction::LocalGet32(local) = instructions[read - 2] {
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::LocalGet32(local);
instructions[read] = Instruction::I32AddConst(c);
} else {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32AddConst(c);
}
}
Instruction::I32Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32AddConst(c);
}
_ => {}
}
}
}
Instruction::I64Add => {
if read > 1
&& let (Instruction::LocalGet64(a), Instruction::LocalGet64(b)) =
(instructions[read - 2], instructions[read - 1])
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64AddLocals(a, b);
}
if read > 0 {
match instructions[read - 1] {
Instruction::I64Const(c) if read > 1 => {
if let Instruction::LocalGet64(local) = instructions[read - 2] {
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::LocalGet64(local);
instructions[read] = Instruction::I64AddConst(c);
} else {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64AddConst(c);
}
}
Instruction::I64Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64AddConst(c);
}
_ => {}
}
}
}
Instruction::I64Rotl => {
if read > 1
&& let (Instruction::I64Xor, Instruction::I64Const(c)) =
(instructions[read - 2], instructions[read - 1])
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64XorRotlConst(c);
}
}
Instruction::I32Store(memarg) => {
if read > 1
&& let (Instruction::LocalGet32(addr_local), Instruction::LocalGet32(value_local)) =
(instructions[read - 2], instructions[read - 1])
&& let (Ok(addr_local), Ok(value_local)) = (u8::try_from(addr_local), u8::try_from(value_local))
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32StoreLocalLocal(memarg, addr_local, value_local);
}
}
Instruction::I64Store(memarg) => {
if read > 1
&& let (Instruction::LocalGet32(addr_local), Instruction::LocalGet64(value_local)) =
(instructions[read - 2], instructions[read - 1])
&& let (Ok(addr_local), Ok(value_local)) = (u8::try_from(addr_local), u8::try_from(value_local))
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64StoreLocalLocal(memarg, addr_local, value_local);
}
}
Instruction::MemoryFill(mem) => {
if read > 1
&& let (Instruction::I32Const(val), Instruction::I32Const(size)) =
(instructions[read - 2], instructions[read - 1])
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::MemoryFillImm(mem, val as u8, size);
}
}
Instruction::LocalGet32(dst) => {
if read > 0
&& let Instruction::LocalSet32(src) = instructions[read - 1]
&& src == dst
{
instructions[read - 1] = Instruction::LocalTee32(src);
instructions[read] = Instruction::Nop;
}
}
Instruction::LocalGet64(dst) => {
if read > 0
&& let Instruction::LocalSet64(src) = instructions[read - 1]
&& src == dst
{
instructions[read - 1] = Instruction::LocalTee64(src);
instructions[read] = Instruction::Nop;
}
}
Instruction::LocalGet128(dst) => {
if read > 0
&& let Instruction::LocalSet128(src) = instructions[read - 1]
&& src == dst
{
instructions[read - 1] = Instruction::LocalTee128(src);
instructions[read] = Instruction::Nop;
}
}
Instruction::LocalSet32(dst) => {
if read > 0 {
match instructions[read - 1] {
Instruction::LocalGet32(src) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] =
if src == dst { Instruction::Nop } else { Instruction::LocalCopy32(src, dst) };
}
Instruction::I32Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::LocalSetConst32(dst, c);
}
Instruction::F32Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] =
Instruction::LocalSetConst32(dst, i32::from_ne_bytes(c.to_bits().to_ne_bytes()));
}
_ => {}
}
}
if read > 1 {
match (instructions[read - 2], instructions[read - 1]) {
(Instruction::LocalGet32(src), Instruction::I32AddConst(c)) if src == dst => {
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::LocalAddConst32(dst, c);
}
(Instruction::LocalGet32(addr), Instruction::I32Load(memarg)) => {
if let (Ok(addr), Ok(dst)) = (u8::try_from(addr), u8::try_from(dst)) {
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32LoadLocalSet(memarg, addr, dst);
}
}
_ => {}
}
}
}
Instruction::LocalSet64(dst) => {
if read > 0 {
match instructions[read - 1] {
Instruction::LocalGet64(src) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] =
if src == dst { Instruction::Nop } else { Instruction::LocalCopy64(src, dst) };
}
Instruction::I64Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::LocalSetConst64(dst, c);
}
Instruction::F64Const(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] =
Instruction::LocalSetConst64(dst, i64::from_ne_bytes(c.to_bits().to_ne_bytes()));
}
_ => {}
}
}
if read > 1
&& let (Instruction::LocalGet64(src), Instruction::I64AddConst(c)) =
(instructions[read - 2], instructions[read - 1])
&& src == dst
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::LocalAddConst64(dst, c);
}
}
Instruction::LocalSet128(dst) => {
if read > 0
&& let Instruction::LocalGet128(src) = instructions[read - 1]
{
instructions[read - 1] = Instruction::Nop;
instructions[read] =
if src == dst { Instruction::Nop } else { Instruction::LocalCopy128(src, dst) };
}
}
Instruction::LocalTee32(dst) => {
if read > 0
&& let Instruction::LocalGet32(src) = instructions[read - 1]
&& src == dst
{
instructions[read] = Instruction::Nop;
}
if read > 1
&& let (Instruction::LocalGet32(addr), Instruction::I32Load(memarg)) =
(instructions[read - 2], instructions[read - 1])
&& let (Ok(addr), Ok(dst)) = (u8::try_from(addr), u8::try_from(dst))
{
instructions[read - 2] = Instruction::Nop;
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I32LoadLocalTee(memarg, addr, dst);
}
}
Instruction::LocalTee64(dst) if read > 0 => match instructions[read - 1] {
Instruction::LocalGet64(src) if src == dst => {
instructions[read] = Instruction::Nop;
}
Instruction::I64XorRotlConst(c) => {
instructions[read - 1] = Instruction::Nop;
instructions[read] = Instruction::I64XorRotlConstTee(c, dst);
}
_ => {}
},
Instruction::LocalTee128(dst) => {
if read > 0
&& let Instruction::LocalGet128(src) = instructions[read - 1]
&& src == dst
{
instructions[read] = Instruction::Nop;
}
}
Instruction::Drop32 => {
if read > 0
&& let Instruction::LocalTee32(local) = instructions[read - 1]
{
instructions[read - 1] = Instruction::LocalSet32(local);
instructions[read] = Instruction::Nop;
}
}
Instruction::Drop64 => {
if read > 0
&& let Instruction::LocalTee64(local) = instructions[read - 1]
{
instructions[read - 1] = Instruction::LocalSet64(local);
instructions[read] = Instruction::Nop;
}
}
Instruction::Drop128 => {
if read > 0
&& let Instruction::LocalTee128(local) = instructions[read - 1]
{
instructions[read - 1] = Instruction::LocalSet128(local);
instructions[read] = Instruction::Nop;
}
}
_ => {}
}
}
}
fn dce(instructions: &mut Vec<Instruction>, function_data: &mut WasmFunctionData) {
let old_len = instructions.len();
if old_len == 0 {
return;
}
let mut removed_before = Vec::with_capacity(old_len + 1);
removed_before.push(0u32);
instructions.iter().for_each(|instr| {
let removed = removed_before.last().copied().unwrap_or(0) + u32::from(matches!(instr, Instruction::Nop));
removed_before.push(removed);
});
let removed_total = removed_before[old_len];
if removed_total == 0 {
return;
}
let compacted_len = old_len as u32 - removed_total;
function_data.branch_table_targets.iter_mut().for_each(|ip| {
let old_target = *ip as usize;
if old_target <= old_len {
*ip -= removed_before[old_target];
debug_assert!(*ip < compacted_len, "remapped jump target points past end of function");
}
});
instructions.retain_mut(|instr| {
let ip = match instr {
Instruction::Jump(ip)
| Instruction::JumpIfZero(ip)
| Instruction::JumpIfNonZero(ip)
| Instruction::BranchTable(ip, _, _) => ip,
_ => return !matches!(instr, Instruction::Nop),
};
let old_target = *ip as usize;
if old_target > old_len {
return !matches!(instr, Instruction::Nop);
}
*ip -= removed_before[old_target];
debug_assert!(*ip < compacted_len, "remapped jump target points past end of function");
!matches!(instr, Instruction::Nop)
});
}
|
