swc_ecma_minifier/compress/pure/numbers.rs
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use swc_common::{util::take::Take, EqIgnoreSpan, Spanned, DUMMY_SP};
use swc_ecma_ast::*;
use swc_ecma_utils::num_from_str;
use super::Pure;
impl Pure<'_> {
pub(super) fn optimize_expr_in_num_ctx(&mut self, e: &mut Expr) {
match e {
Expr::Lit(Lit::Str(Str { span, value, .. })) => {
let value = if value.is_empty() {
0f64
} else {
match num_from_str(value).into_result() {
Ok(f) if f.is_finite() => f,
_ => return,
}
};
self.changed = true;
report_change!("numbers: Converting a string literal to {:?}", value);
*e = Lit::Num(Number {
span: *span,
value,
raw: None,
})
.into();
}
Expr::Unary(UnaryExpr {
arg,
op: op!(unary, "+"),
..
}) => {
self.changed = true;
report_change!("numbers: remove useless to number");
let new_expr = *arg.take();
*e = new_expr
}
_ => (),
}
}
///
/// - `1 / -0` => `- 1 / 0`
pub(super) fn lift_minus(&mut self, e: &mut Expr) {
if !self.options.evaluate {
return;
}
if let Expr::Bin(arg) = e {
if arg.op != op!("*") && arg.op != op!("/") {
return;
}
match &mut *arg.right {
Expr::Unary(UnaryExpr {
op: op!(unary, "-"),
arg: right_arg,
..
}) => {
self.changed = true;
report_change!("numbers: Lifting `-`");
*e = UnaryExpr {
span: arg.span,
op: op!(unary, "-"),
arg: BinExpr {
span: arg.span,
op: arg.op,
left: arg.left.take(),
right: right_arg.take(),
}
.into(),
}
.into();
}
Expr::Lit(Lit::Num(Number { span, value, .. })) => {
if value.is_sign_negative() {
self.changed = true;
report_change!("numbers: Lifting `-` in a literal");
*e = UnaryExpr {
span: arg.span,
op: op!(unary, "-"),
arg: BinExpr {
span: arg.span,
op: arg.op,
left: arg.left.take(),
right: Box::new(Expr::Lit(Lit::Num(Number {
span: *span,
value: -*value,
raw: None,
}))),
}
.into(),
}
.into();
}
}
_ => {}
}
}
}
pub(super) fn optimize_to_number(&mut self, e: &mut Expr) {
match e {
Expr::Bin(bin) => {
if bin.op == op!("*")
&& matches!(&*bin.left, Expr::Lit(Lit::Num(Number { value: 1.0, .. })))
{
report_change!("numbers: Turn '1 *' into '+'");
self.changed = true;
let value = bin.right.take();
let span = bin.span;
*e = Expr::Unary(UnaryExpr {
span,
op: op!(unary, "+"),
arg: value,
})
}
}
Expr::Assign(a @ AssignExpr { op: op!("="), .. }) => {
if let (
AssignTarget::Simple(SimpleAssignTarget::Ident(l_id)),
Expr::Unary(UnaryExpr {
op: op!(unary, "+"),
arg,
..
}),
) = (&a.left, &*a.right)
{
if let Expr::Ident(r_id) = &**arg {
if l_id.id.eq_ignore_span(r_id) {
report_change!("numbers: Turn a = +a into a *= 1");
self.changed = true;
a.op = op!("*=");
a.right = Box::new(Expr::Lit(Lit::Num(Number {
span: DUMMY_SP,
value: 1.0,
raw: None,
})))
}
}
}
}
_ => (),
}
}
pub(super) fn optimize_to_int(&mut self, e: &mut Expr) {
let span = e.span();
match e {
Expr::Bin(bin) => match (bin.op, &mut *bin.left, &mut *bin.right) {
(op!("|"), Expr::Bin(bin_inner), Expr::Lit(Lit::Num(n)))
| (op!("|"), Expr::Lit(Lit::Num(n)), Expr::Bin(bin_inner))
if matches!(
bin_inner.op,
op!("<<") | op!(">>") | op!(">>>") | op!("|") | op!("^") | op!("&")
) && n.value == 0.0 =>
{
report_change!("numbers: Turn '(a & b) | 0' into 'a & b'");
self.changed = true;
let value = bin_inner.take();
*bin = BinExpr { span, ..value };
}
(
op!("|"),
Expr::Unary(u @ UnaryExpr { op: op!("~"), .. }),
Expr::Lit(Lit::Num(Number { value: 0.0, .. })),
)
| (
op!("|"),
Expr::Lit(Lit::Num(Number { value: 0.0, .. })),
Expr::Unary(u @ UnaryExpr { op: op!("~"), .. }),
) => {
report_change!("numbers: Turn '~a | 0' into '~a'");
self.changed = true;
let value = u.take();
*e = Expr::Unary(value);
}
(
op!("<<") | op!(">>") | op!("^"),
_,
Expr::Lit(Lit::Num(Number { value: 0.0, .. })),
) => {
report_change!("numbers: Turn 'a << 0' into 'a | 0'");
self.changed = true;
bin.op = op!("|");
}
(
op!("&"),
_,
Expr::Lit(Lit::Num(
n @ Number {
value: 4294967295.0, // 2^32 - 1
..
},
)),
)
| (
op!("&"),
Expr::Lit(Lit::Num(
n @ Number {
value: 4294967295.0, // 2^32 - 1
..
},
)),
_,
) => {
report_change!("numbers: Turn 'a & 0XFFFFFFFF' into 'a | 0'");
self.changed = true;
bin.op = op!("|");
n.value = 0.0;
n.raw = None;
}
_ => (),
},
Expr::Assign(
a @ AssignExpr {
op: op!("<<=") | op!(">>=") | op!(">>>=") | op!("|=") | op!("^=") | op!("&="),
..
},
) => {
if let Expr::Bin(BinExpr {
op: op!("|"),
left,
right,
..
}) = &mut *a.right
{
if let (e, Expr::Lit(Lit::Num(Number { value: 0.0, .. })))
| (Expr::Lit(Lit::Num(Number { value: 0.0, .. })), e) =
(&mut **left, &mut **right)
{
report_change!("numbers: Turn 'a |= b | 0' into 'a |= b'");
self.changed = true;
let value = e.take();
*a.right = value;
}
}
}
_ => (),
}
}
}