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refactor(minifier): use the original vec in-place in minimize_statements #13028

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Merged
graphite-app merged 1 commit into from
Aug 12, 2025
Merged

refactor(minifier): use the original vec in-place in minimize_statements #13028

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70 changes: 30 additions & 40 deletions crates/oxc_minifier/src/peephole/minimize_statements.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,12 +31,11 @@ impl<'a> PeepholeOptimizations {
/// ## MinimizeExitPoints:
/// <https://github.com/google/closure-compiler/blob/v20240609/src/com/google/javascript/jscomp/MinimizeExitPoints.java>
pub fn minimize_statements(&self, stmts: &mut Vec<'a, Statement<'a>>, ctx: &mut Ctx<'a, '_>) {
let mut result: Vec<'a, Statement<'a>> = ctx.ast.vec_with_capacity(stmts.len());
let mut old_stmts = stmts.take_in(ctx.ast);
let mut is_control_flow_dead = false;
let mut keep_var = KeepVar::new(ctx.ast);
let mut new_stmts = stmts.take_in(ctx.ast);
for i in 0..new_stmts.len() {
let stmt = new_stmts[i].take_in(ctx.ast);
for i in 0..old_stmts.len() {
let stmt = old_stmts[i].take_in(ctx.ast);
if is_control_flow_dead
&& !stmt.is_module_declaration()
&& !matches!(stmt.as_declaration(), Some(Declaration::FunctionDeclaration(_)))
Expand All @@ -45,31 +44,24 @@ impl<'a> PeepholeOptimizations {
continue;
}
if self
.minimize_statement(
stmt,
i,
&mut new_stmts,
&mut result,
&mut is_control_flow_dead,
ctx,
)
.minimize_statement(stmt, i, &mut old_stmts, stmts, &mut is_control_flow_dead, ctx)
.is_break()
{
break;
}
}
if let Some(stmt) = keep_var.get_variable_declaration_statement() {
result.push(stmt);
stmts.push(stmt);
}

// Drop a trailing unconditional jump statement if applicable
if let Some(last_stmt) = result.last() {
if let Some(last_stmt) = stmts.last() {
match last_stmt {
// "while (x) { y(); continue; }" => "while (x) { y(); }"
Statement::ContinueStatement(s) if s.label.is_none() => {
let mut changed = false;
if let Some(Ancestor::ForStatementBody(_)) = ctx.ancestors().nth(1) {
result.pop();
stmts.pop();
changed = true;
}
if changed {
Expand All @@ -79,7 +71,7 @@ impl<'a> PeepholeOptimizations {
// "function f() { x(); return; }" => "function f() { x(); }"
Statement::ReturnStatement(s) if s.argument.is_none() => {
if let Ancestor::FunctionBodyStatements(_) = ctx.parent() {
result.pop();
stmts.pop();
ctx.state.changed = true;
}
}
Expand All @@ -88,25 +80,25 @@ impl<'a> PeepholeOptimizations {
}

// Merge certain statements in reverse order
if result.len() >= 2 && ctx.options().sequences {
if let Some(Statement::ReturnStatement(_)) = result.last() {
'return_loop: while result.len() >= 2 {
let prev_index = result.len() - 2;
let prev_stmt = &result[prev_index];
if stmts.len() >= 2 && ctx.options().sequences {
if let Some(Statement::ReturnStatement(_)) = stmts.last() {
'return_loop: while stmts.len() >= 2 {
let prev_index = stmts.len() - 2;
let prev_stmt = &stmts[prev_index];
match prev_stmt {
Statement::ExpressionStatement(_) => {
if let Some(Statement::ReturnStatement(last_return)) = result.last() {
if let Some(Statement::ReturnStatement(last_return)) = stmts.last() {
if last_return.argument.is_none() {
break 'return_loop;
}
}
ctx.state.changed = true;
// "a(); return b;" => "return a(), b;"
let last_stmt = result.pop().unwrap();
let last_stmt = stmts.pop().unwrap();
let Statement::ReturnStatement(mut last_return) = last_stmt else {
unreachable!()
};
let prev_stmt = result.pop().unwrap();
let prev_stmt = stmts.pop().unwrap();
let Statement::ExpressionStatement(mut expr_stmt) = prev_stmt else {
unreachable!()
};
Expand All @@ -115,7 +107,7 @@ impl<'a> PeepholeOptimizations {
let right_span = last_return.span;
let last_return_stmt =
ctx.ast.statement_return(right_span, Some(argument));
result.push(last_return_stmt);
stmts.push(last_return_stmt);
}
// Merge the last two statements
Statement::IfStatement(if_stmt) => {
Expand All @@ -129,11 +121,11 @@ impl<'a> PeepholeOptimizations {
};

ctx.state.changed = true;
let last_stmt = result.pop().unwrap();
let last_stmt = stmts.pop().unwrap();
let Statement::ReturnStatement(last_return) = last_stmt else {
unreachable!()
};
let prev_stmt = result.pop().unwrap();
let prev_stmt = stmts.pop().unwrap();
let Statement::IfStatement(prev_if) = prev_stmt else { unreachable!() };
let mut prev_if = prev_if.unbox();
let Statement::ReturnStatement(prev_return) = prev_if.consequent else {
Expand Down Expand Up @@ -181,24 +173,24 @@ impl<'a> PeepholeOptimizations {
};
let last_return_stmt =
ctx.ast.statement_return(right_span, Some(argument));
result.push(last_return_stmt);
stmts.push(last_return_stmt);
}
_ => break 'return_loop,
}
}
} else if let Some(Statement::ThrowStatement(_)) = result.last() {
'throw_loop: while result.len() >= 2 {
let prev_index = result.len() - 2;
let prev_stmt = &result[prev_index];
} else if let Some(Statement::ThrowStatement(_)) = stmts.last() {
'throw_loop: while stmts.len() >= 2 {
let prev_index = stmts.len() - 2;
let prev_stmt = &stmts[prev_index];
match prev_stmt {
Statement::ExpressionStatement(_) => {
ctx.state.changed = true;
// "a(); throw b;" => "throw a(), b;"
let last_stmt = result.pop().unwrap();
let last_stmt = stmts.pop().unwrap();
let Statement::ThrowStatement(mut last_throw) = last_stmt else {
unreachable!()
};
let prev_stmt = result.pop().unwrap();
let prev_stmt = stmts.pop().unwrap();
let Statement::ExpressionStatement(mut expr_stmt) = prev_stmt else {
unreachable!()
};
Expand All @@ -209,7 +201,7 @@ impl<'a> PeepholeOptimizations {
);
let right_span = last_throw.span;
let last_throw_stmt = ctx.ast.statement_throw(right_span, argument);
result.push(last_throw_stmt);
stmts.push(last_throw_stmt);
}
// Merge the last two statements
Statement::IfStatement(if_stmt) => {
Expand All @@ -223,11 +215,11 @@ impl<'a> PeepholeOptimizations {
};

ctx.state.changed = true;
let last_stmt = result.pop().unwrap();
let last_stmt = stmts.pop().unwrap();
let Statement::ThrowStatement(last_throw) = last_stmt else {
unreachable!()
};
let prev_stmt = result.pop().unwrap();
let prev_stmt = stmts.pop().unwrap();
let Statement::IfStatement(prev_if) = prev_stmt else { unreachable!() };
let mut prev_if = prev_if.unbox();
let Statement::ThrowStatement(prev_throw) = prev_if.consequent else {
Expand Down Expand Up @@ -265,15 +257,13 @@ impl<'a> PeepholeOptimizations {
)
};
let last_throw_stmt = ctx.ast.statement_throw(right_span, argument);
result.push(last_throw_stmt);
stmts.push(last_throw_stmt);
}
_ => break 'throw_loop,
}
}
}
}

*stmts = result;
}

fn minimize_statement(
Expand Down
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