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Promote expr block.

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This commit is contained in:
Stephen Chung 2021-04-05 14:57:07 +08:00
parent 00784d39ad
commit f5d3a0ef4f
1 changed files with 18 additions and 18 deletions
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36
src/optimize.rs
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@ -546,19 +546,21 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut State, preserve_result: bool) {
Stmt::Import(expr, _, _) => optimize_expr(expr, state),
// { block }
Stmt::Block(statements, pos) => {
let block = mem::take(statements);
*stmt = match optimize_stmt_block(block, state, preserve_result, true, false) {
statements if statements.is_empty() => {
let mut block =
optimize_stmt_block(mem::take(statements), state, preserve_result, true, false);
match block.as_mut_slice() {
[] => {
state.set_dirty();
Stmt::Noop(*pos)
*stmt = Stmt::Noop(*pos);
}
// Only one statement - promote
mut statements if statements.len() == 1 => {
[s] => {
state.set_dirty();
statements.pop().unwrap()
*stmt = mem::take(s);
}
statements => Stmt::Block(statements, *pos),
};
_ => *stmt = Stmt::Block(block, *pos),
}
}
// try { pure try_block } catch ( var ) { catch_block } -> try_block
Stmt::TryCatch(x, _, _) if x.0.statements.iter().all(Stmt::is_pure) => {
@ -609,18 +611,16 @@ fn optimize_expr(expr: &mut Expr, state: &mut State) {
match expr {
// {}
Expr::Stmt(x) if x.statements.is_empty() => { state.set_dirty(); *expr = Expr::Unit(x.pos) }
// { Stmt(Expr) }
Expr::Stmt(x) if x.statements.len() == 1 && x.statements[0].is_pure() && matches!(x.statements[0], Stmt::Expr(_)) =>
{
state.set_dirty();
if let Stmt::Expr(e) = mem::take(&mut x.statements[0]) {
*expr = e;
} else {
unreachable!();
// { stmt; ... } - do not count promotion as dirty because it gets turned back into an array
Expr::Stmt(x) => {
x.statements = optimize_stmt_block(mem::take(&mut x.statements).into_vec(), state, true, true, false).into();
// { Stmt(Expr) } - promote
match x.statements.as_mut() {
[ Stmt::Expr(e) ] => { state.set_dirty(); *expr = mem::take(e); }
_ => ()
}
}
// { stmt; ... } - do not count promotion as dirty because it gets turned back into an array
Expr::Stmt(x) => x.statements = optimize_stmt_block(mem::take(&mut x.statements).into_vec(), state, true, true, false).into(),
// lhs.rhs
#[cfg(not(feature = "no_object"))]
Expr::Dot(x, _) => match (&mut x.lhs, &mut x.rhs) {