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feat(es/minifier): Make sequential inliner self-repeat #6168

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merged 9 commits into from Oct 18, 2022
Merged

feat(es/minifier): Make sequential inliner self-repeat #6168

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79097a1
Add tests
kdy1 Oct 15, 2022
d13169c
Repeat
kdy1 Oct 15, 2022
1315a93
Update test refs
kdy1 Oct 15, 2022
d18733b
Reduce
kdy1 Oct 15, 2022
3267f75
Test
kdy1 Oct 15, 2022
b9fb976
Revert "Reduce"
kdy1 Oct 15, 2022
91588a7
config.json
kdy1 Oct 15, 2022
afc8d74
Update test refs
kdy1 Oct 15, 2022
266fad5
Merge branch 'main' into seq-repeat
swc-bot Oct 18, 2022
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7 changes: 5 additions & 2 deletions crates/swc/tests/tsc-references/computedPropertyNames12_ES5.2.minified.js
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@@ -1,4 +1,7 @@
//// [computedPropertyNames12_ES5.ts]
var a;
import _class_call_check from "@swc/helpers/src/_class_call_check.mjs";
"hello ".concat(a, " bye");
var n, a, _ref = (void 0) + n;
(function C() {
"use strict";
_class_call_check(this, C), this[n] = n, this[_ref] = 2, this["hello bye"] = 0;
})["hello ".concat(a, " bye")] = 0;
254 changes: 133 additions & 121 deletions crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
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Expand Up @@ -771,166 +771,178 @@ where
)
};

for idx in 0..exprs.len() {
for j in idx..exprs.len() {
let (a1, a2) = exprs.split_at_mut(idx);
loop {
let mut did_work = false;

if a1.is_empty() || a2.is_empty() {
break;
}

let a = a1.last_mut().unwrap();
for idx in 0..exprs.len() {
for j in idx..exprs.len() {
let (a1, a2) = exprs.split_at_mut(idx);

if self.options.unused && self.options.sequences() {
if let (Mergable::Var(av), Mergable::Var(bv)) = (&mut *a, &mut a2[j - idx]) {
// We try dropping variable assignments first.
if a1.is_empty() || a2.is_empty() {
break;
}

// Currently, we only drop variable declarations if they have the same name.
if let (Pat::Ident(an), Pat::Ident(bn)) = (&av.name, &bv.name) {
if an.to_id() == bn.to_id() {
// We need to preserve side effect of `av.init`
let a = a1.last_mut().unwrap();

match bv.init.as_deref_mut() {
Some(b_init) => {
if IdentUsageFinder::find(&an.to_id(), b_init) {
log_abort!(
"We can't duplicated binding because initializer \
uses the previous declaration of the variable"
);
break;
}
if self.options.unused && self.options.sequences() {
if let (Mergable::Var(av), Mergable::Var(bv)) = (&mut *a, &mut a2[j - idx])
{
// We try dropping variable assignments first.

// Currently, we only drop variable declarations if they have the same
// name.
if let (Pat::Ident(an), Pat::Ident(bn)) = (&av.name, &bv.name) {
if an.to_id() == bn.to_id() {
// We need to preserve side effect of `av.init`

match bv.init.as_deref_mut() {
Some(b_init) => {
if IdentUsageFinder::find(&an.to_id(), b_init) {
log_abort!(
"We can't duplicated binding because \
initializer uses the previous declaration of \
the variable"
);
break;
}

if let Some(a_init) = av.init.take() {
let b_seq = b_init.force_seq();
b_seq.exprs.insert(0, a_init);
if let Some(a_init) = av.init.take() {
let b_seq = b_init.force_seq();
b_seq.exprs.insert(0, a_init);

self.changed = true;
report_change!(
"Moving initializer sequentially as they have \
a same name"
);
av.name.take();
continue;
} else {
self.changed = true;
report_change!(
"Dropping the previous var declaration of {} \
which does not have an initializer",
an.id
);
av.name.take();
continue;
}
}
None => {
// As variable name is same, we can move initializer

// Th code below
//
// var a = 5;
// var a;
//
// console.log(a)
//
// prints 5
bv.init = av.init.take();
self.changed = true;
report_change!(
"Moving initializer sequentially as they have a \
same name"
);
av.name.take();
continue;
} else {
self.changed = true;
report_change!(
"Dropping the previous var declaration of {} \
which does not have an initializer",
an.id
"Moving initializer to the next variable \
declaration as they have the same name"
);
av.name.take();
continue;
}
}
None => {
// As variable name is same, we can move initializer

// Th code below
//
// var a = 5;
// var a;
//
// console.log(a)
//
// prints 5
bv.init = av.init.take();
self.changed = true;
report_change!(
"Moving initializer to the next variable declaration \
as they have the same name"
);
av.name.take();
continue;
}
}
}
}
}
}

// Merge sequentially
// Merge sequentially

if self.merge_sequential_expr(
a,
match &mut a2[j - idx] {
Mergable::Var(b) => match b.init.as_deref_mut() {
Some(v) => v,
None => continue,
if self.merge_sequential_expr(
a,
match &mut a2[j - idx] {
Mergable::Var(b) => match b.init.as_deref_mut() {
Some(v) => v,
None => continue,
},
Mergable::Expr(e) => e,
},
Mergable::Expr(e) => e,
},
)? {
break;
}
)? {
did_work = true;
break;
}

// This logic is required to handle
//
// var b;
// (function () {
// function f() {
// a++;
// }
// f();
// var c = f();
// var a = void 0;
// c || (b = a);
// })();
// console.log(b);
//
//
// at the code above, c cannot be shifted to `c` in `c || (b = a)`
//
// This logic is required to handle
//
// var b;
// (function () {
// function f() {
// a++;
// }
// f();
// var c = f();
// var a = void 0;
// c || (b = a);
// })();
// console.log(b);
//
//
// at the code above, c cannot be shifted to `c` in `c || (b = a)`
//

match a {
Mergable::Var(VarDeclarator {
init: Some(init), ..
}) => {
if !self.is_skippable_for_seq(None, init) {
break;
}
}
Mergable::Expr(Expr::Assign(a)) => {
if let Some(a) = a.left.as_expr() {
if !self.is_skippable_for_seq(None, a) {
match a {
Mergable::Var(VarDeclarator {
init: Some(init), ..
}) => {
if !self.is_skippable_for_seq(None, init) {
break;
}
}
Mergable::Expr(Expr::Assign(a)) => {
if let Some(a) = a.left.as_expr() {
if !self.is_skippable_for_seq(None, a) {
break;
}
}

if !self.is_skippable_for_seq(None, &a.right) {
break;
if !self.is_skippable_for_seq(None, &a.right) {
break;
}
}
_ => {}
}
_ => {}
}

match &a2[j - idx] {
Mergable::Var(e2) => {
if let Some(e2) = &e2.init {
if !self.is_skippable_for_seq(Some(a), e2) {
break;
match &a2[j - idx] {
Mergable::Var(e2) => {
if let Some(e2) = &e2.init {
if !self.is_skippable_for_seq(Some(a), e2) {
break;
}
}
}

if let Some(id) = a1.last_mut().unwrap().id() {
if IdentUsageFinder::find(&id, &**e2) {
break;
if let Some(id) = a1.last_mut().unwrap().id() {
if IdentUsageFinder::find(&id, &**e2) {
break;
}
}
}
}
Mergable::Expr(e2) => {
if !self.is_skippable_for_seq(Some(a), e2) {
break;
}

if let Some(id) = a1.last_mut().unwrap().id() {
// TODO(kdy1): Optimize
if IdentUsageFinder::find(&id, &**e2) {
Mergable::Expr(e2) => {
if !self.is_skippable_for_seq(Some(a), e2) {
break;
}

if let Some(id) = a1.last_mut().unwrap().id() {
// TODO(kdy1): Optimize
if IdentUsageFinder::find(&id, &**e2) {
break;
}
}
}
}
}
}

if !did_work {
break;
}
}

Ok(())
Expand Down