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use crate::lua51::ast::*;
use crate::lua51::liveness::is_reg_live_after;
use crate::lua51::opcodes::OpCode;
use super::Lifter;
use super::util::{make_index, is_identifier};
impl<'a> Lifter<'a> {
/// Lift a range of instructions into statements.
pub(super) fn lift_instructions(&mut self, start_pc: usize, end_pc: usize, stmts: &mut Block) {
let mut pc = start_pc;
while pc <= end_pc {
let inst = self.cfg.instructions[pc];
match inst.op {
OpCode::Move => {
let src = self.reg_expr(inst.b());
self.assign_reg_expr(pc, inst.a, src, stmts);
}
OpCode::LoadK => {
let expr = self.const_expr(inst.bx());
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::LoadBool => {
self.assign_reg_expr(pc, inst.a, Expr::Bool(inst.b() != 0), stmts);
if inst.c() != 0 {
pc += 1; // skip next instruction
}
}
OpCode::LoadNil => {
for r in inst.a..=inst.b() {
self.assign_reg_expr(pc, r, Expr::Nil, stmts);
}
}
OpCode::GetUpval => {
let expr = self.upvalue_expr(inst.b());
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::GetGlobal => {
let name = self.const_string(inst.bx());
self.assign_reg_expr(pc, inst.a, Expr::Global(name), stmts);
}
OpCode::GetTable => {
let table = self.reg_expr(inst.b());
let key = self.rk_expr(inst.c());
let expr = make_index(table, key);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::SetGlobal => {
self.flush_pending_table(inst.a);
let name = self.const_string(inst.bx());
let val = self.reg_expr(inst.a);
stmts.push(Stat::Assign {
targets: vec![Expr::Global(name)],
values: vec![val],
});
self.capture_aliases
.insert(inst.a, Expr::Global(self.const_string(inst.bx())));
}
OpCode::SetUpval => {
let val = self.reg_expr(inst.a);
let uv = self.upvalue_expr(inst.b());
stmts.push(Stat::Assign {
targets: vec![uv],
values: vec![val],
});
}
OpCode::SetTable => {
// Check if this is part of table construction
let is_pending = self.pending_tables.contains_key(&inst.a);
if is_pending {
let key = self.rk_expr(inst.b());
let val = self.rk_expr(inst.c());
let fields = self.pending_tables.get_mut(&inst.a).unwrap();
// If key is a string identifier, use NameField
if let Expr::StringLit(ref s) = key {
if let Ok(name) = std::str::from_utf8(s) {
if is_identifier(name) {
fields.push(TableField::NameField(
name.to_string(),
val,
));
pc += 1;
continue;
}
}
}
fields.push(TableField::IndexField(key, val));
pc += 1;
continue;
}
// Flush any pending table first
self.flush_pending_table(inst.a);
let table = self.reg_expr(inst.a);
let key = self.rk_expr(inst.b());
let val = self.rk_expr(inst.c());
let target = make_index(table, key);
stmts.push(Stat::Assign {
targets: vec![target.clone()],
values: vec![val],
});
if !crate::lua51::instruction::is_k(inst.c()) {
self.capture_aliases.insert(inst.c(), target);
}
}
OpCode::NewTable => {
self.assign_reg_expr(pc, inst.a, Expr::Table(Vec::new()), stmts);
self.pending_tables.insert(inst.a, Vec::new());
}
OpCode::Self_ => {
let table = self.reg_expr(inst.b());
let method = self.rk_expr(inst.c());
let method_ref = make_index(table.clone(), method);
self.assign_reg_expr(pc, inst.a + 1, table, stmts);
self.assign_reg_expr(pc, inst.a, method_ref, stmts);
}
OpCode::Add => {
let expr = Expr::BinOp(
BinOp::Add,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Sub => {
let expr = Expr::BinOp(
BinOp::Sub,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Mul => {
let expr = Expr::BinOp(
BinOp::Mul,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Div => {
let expr = Expr::BinOp(
BinOp::Div,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Mod => {
let expr = Expr::BinOp(
BinOp::Mod,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Pow => {
let expr = Expr::BinOp(
BinOp::Pow,
Box::new(self.rk_expr(inst.b())),
Box::new(self.rk_expr(inst.c())),
);
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Unm => {
let expr = Expr::UnOp(UnOp::Neg, Box::new(self.reg_expr(inst.b())));
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Not => {
let expr = Expr::UnOp(UnOp::Not, Box::new(self.reg_expr(inst.b())));
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Len => {
let expr = Expr::UnOp(UnOp::Len, Box::new(self.reg_expr(inst.b())));
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Concat => {
let b = inst.b();
let c = inst.c();
let mut expr = self.reg_expr(b);
for r in (b + 1)..=c {
expr = Expr::BinOp(
BinOp::Concat,
Box::new(expr),
Box::new(self.reg_expr(r)),
);
}
self.assign_reg_expr(pc, inst.a, expr, stmts);
}
OpCode::Jmp => {
// Jumps are handled by the CFG; skip here
}
OpCode::Eq | OpCode::Lt | OpCode::Le => {
// Comparison tests: handled at block level for conditionals
pc += 1; // skip following JMP
}
OpCode::Test => {
// Handled at conditional level
pc += 1;
}
OpCode::TestSet => {
// R(A) := R(B) if R(B) <=> C, else skip
pc += 1;
}
OpCode::Call => {
let func = self.reg_expr(inst.a);
let num_args = if inst.b() == 0 {
0 // variable args - simplified
} else {
inst.b() - 1
};
let args: Vec<Expr> = (0..num_args)
.map(|i| self.reg_expr(inst.a + 1 + i))
.collect();
let call = CallExpr { func, args };
if inst.c() == 1 {
// C==1: no return values -> statement call
stmts.push(Stat::Call(call));
} else if inst.c() == 0 {
// C==0: variable return values (used by next CALL/RETURN/SETLIST)
self.set_reg(inst.a, Expr::FuncCall(Box::new(call)));
} else {
// C>=2: fixed return values (C-1 results)
let num_results = inst.c() - 1;
if num_results == 1 {
let call_expr = Expr::FuncCall(Box::new(call));
// Use liveness: only create a local if the result
// is used later
let live = is_reg_live_after(
&self.cfg, &self.liveness, pc, inst.a,
);
if live {
self.set_reg_local(inst.a, call_expr, stmts);
} else {
// Result not used -> emit as statement
if let Expr::FuncCall(c) = call_expr {
stmts.push(Stat::Call(*c));
}
}
} else {
// Multiple fixed return values -> local multi-assign
let names: Vec<String> = (0..num_results)
.map(|i| {
let r = inst.a + i;
let name = self.make_local_name(r);
self.local_names.insert(r, name.clone());
self.declared_locals.insert(r);
name
})
.collect();
stmts.push(Stat::LocalAssign {
names: names.clone(),
exprs: vec![Expr::FuncCall(Box::new(call))],
});
for (i, name) in names.iter().enumerate() {
let r = (inst.a + i as u32) as usize;
if r < self.regs.len() {
self.regs[r] = Some(Expr::Name(name.clone()));
}
}
}
}
}
OpCode::TailCall => {
let func = self.reg_expr(inst.a);
let num_args = if inst.b() == 0 {
0
} else {
inst.b() - 1
};
let args: Vec<Expr> = (0..num_args)
.map(|i| self.reg_expr(inst.a + 1 + i))
.collect();
let call = CallExpr { func, args };
stmts.push(Stat::Return(vec![Expr::FuncCall(Box::new(call))]));
}
OpCode::Return => {
let num_ret = if inst.b() == 0 {
0
} else {
inst.b() - 1
};
if num_ret == 0 && inst.a == 0 {
// `return` with no values at end of function - may be implicit
if pc != end_pc || end_pc != self.cfg.instructions.len() - 1 {
stmts.push(Stat::Return(Vec::new()));
}
} else {
let vals: Vec<Expr> = (0..num_ret)
.map(|i| self.reg_expr(inst.a + i))
.collect();
stmts.push(Stat::Return(vals));
}
}
OpCode::ForLoop | OpCode::ForPrep => {
// Handled by loop lifting
}
OpCode::TForLoop => {
// Handled by loop lifting
}
OpCode::SetList => {
let table_reg = inst.a;
let num = if inst.b() == 0 { 0 } else { inst.b() };
// Items are in registers A+1 .. A+num
// Flush any pending subtables in those registers first
for i in 1..=num {
self.flush_pending_table(table_reg + i);
}
// Collect values
let values: Vec<Expr> = (1..=num)
.map(|i| self.reg_expr(table_reg + i))
.collect();
if let Some(fields) = self.pending_tables.get_mut(&table_reg) {
for val in values {
fields.push(TableField::Value(val));
}
}
}
OpCode::Close => {
// Internal VM operation, no visible effect in source
}
OpCode::Closure => {
let closure_pc = pc;
let proto_idx = inst.bx() as usize;
let sub_func = if proto_idx < self.chunk.prototypes.len() {
let sub_chunk = &self.chunk.prototypes[proto_idx];
let resolved = self.resolve_closure_upvalues(pc, sub_chunk, stmts);
Lifter::decompile_with_upvalues(sub_chunk, resolved)
} else {
Function {
params: Vec::new(),
is_vararg: false,
body: Vec::new(),
}
};
if proto_idx < self.chunk.prototypes.len() {
pc += self.chunk.prototypes[proto_idx].num_upvalues as usize;
}
self.assign_reg_expr(
closure_pc,
inst.a,
Expr::FunctionDef(Box::new(sub_func)),
stmts,
);
}
OpCode::VarArg => {
self.assign_reg_expr(pc, inst.a, Expr::VarArg, stmts);
}
}
pc += 1;
}
}
}