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improve unused on assign-only symbols (#2568)

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This commit is contained in:
Alex Lam S.L
2017-12-09 06:19:29 +08:00
committed by GitHub
parent 74a2f53683
commit 0aff037a35
2 changed files with 113 additions and 75 deletions
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38
lib/compress.js
View File

@@ -2487,6 +2487,20 @@ merge(Compressor.prototype, {
// pass 3: we should drop declarations not in_use // pass 3: we should drop declarations not in_use
var tt = new TreeTransformer( var tt = new TreeTransformer(
function before(node, descend, in_list) { function before(node, descend, in_list) {
var parent = tt.parent();
if (drop_vars) {
var sym = assign_as_unused(node);
if (sym instanceof AST_SymbolRef
&& !(sym.definition().id in in_use_ids)) {
if (node instanceof AST_Assign) {
return maintain_this_binding(parent, node, node.right.transform(tt));
}
return make_node(AST_Number, node, {
value: 0
});
}
}
if (scope !== self) return;
if (node instanceof AST_Function if (node instanceof AST_Function
&& node.name && node.name
&& !compressor.option("keep_fnames")) { && !compressor.option("keep_fnames")) {
@@ -2520,9 +2534,7 @@ merge(Compressor.prototype, {
def.eliminated++; def.eliminated++;
return make_node(AST_EmptyStatement, node); return make_node(AST_EmptyStatement, node);
} }
return node;
} }
var parent = tt.parent();
if (node instanceof AST_Definitions && !(parent instanceof AST_ForIn && parent.init === node)) { if (node instanceof AST_Definitions && !(parent instanceof AST_ForIn && parent.init === node)) {
// place uninitialized names at the start // place uninitialized names at the start
var body = [], head = [], tail = []; var body = [], head = [], tail = [];
@@ -2602,18 +2614,6 @@ merge(Compressor.prototype, {
}); });
} }
} }
if (drop_vars) {
var sym = assign_as_unused(node);
if (sym instanceof AST_SymbolRef
&& !(sym.definition().id in in_use_ids)) {
if (node instanceof AST_Assign) {
return maintain_this_binding(parent, node, node.right.transform(tt));
}
return make_node(AST_Number, node, {
value: 0
});
}
}
// certain combination of unused name + side effect leads to: // certain combination of unused name + side effect leads to:
// https://github.com/mishoo/UglifyJS2/issues/44 // https://github.com/mishoo/UglifyJS2/issues/44
// https://github.com/mishoo/UglifyJS2/issues/1830 // https://github.com/mishoo/UglifyJS2/issues/1830
@@ -2645,8 +2645,13 @@ merge(Compressor.prototype, {
} }
return node; return node;
} }
if (node instanceof AST_Scope && node !== self) if (node instanceof AST_Scope) {
var save_scope = scope;
scope = node;
descend(node, this);
scope = save_scope;
return node; return node;
}
function template(sym) { function template(sym) {
return { return {
@@ -2662,8 +2667,7 @@ merge(Compressor.prototype, {
function scan_ref_scoped(node, descend) { function scan_ref_scoped(node, descend) {
var sym; var sym;
if (scope === self if ((sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& (sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& self.variables.get(sym.name) === sym.definition()) { && self.variables.get(sym.name) === sym.definition()) {
if (node instanceof AST_Assign) node.right.walk(tw); if (node instanceof AST_Assign) node.right.walk(tw);
return true; return true;

150
test/compress/drop-unused.js
View File

@@ -179,7 +179,9 @@ keep_fnames: {
} }
drop_assign: { drop_assign: {
options = { unused: true }; options = {
unused: true,
}
input: { input: {
function f1() { function f1() {
var a; var a;
@@ -200,7 +202,7 @@ drop_assign: {
var a; var a;
return function() { return function() {
a = 1; a = 1;
} };
} }
} }
expect: { expect: {
@@ -217,16 +219,17 @@ drop_assign: {
return 1; return 1;
} }
function f5() { function f5() {
var a;
return function() { return function() {
a = 1; 1;
} };
} }
} }
} }
keep_assign: { keep_assign: {
options = { unused: "keep_assign" }; options = {
unused: "keep_assign",
}
input: { input: {
function f1() { function f1() {
var a; var a;
@@ -247,7 +250,7 @@ keep_assign: {
var a; var a;
return function() { return function() {
a = 1; a = 1;
} };
} }
} }
expect: { expect: {
@@ -270,19 +273,22 @@ keep_assign: {
var a; var a;
return function() { return function() {
a = 1; a = 1;
} };
} }
} }
} }
drop_toplevel_funcs: { drop_toplevel_funcs: {
options = { toplevel: "funcs", unused: true }; options = {
toplevel: "funcs",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -298,13 +304,16 @@ drop_toplevel_funcs: {
} }
drop_toplevel_vars: { drop_toplevel_vars: {
options = { toplevel: "vars", unused: true }; options = {
toplevel: "vars",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -312,11 +321,10 @@ drop_toplevel_vars: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
2; 2;
function g() {} function g() {}
@@ -326,13 +334,17 @@ drop_toplevel_vars: {
} }
drop_toplevel_vars_fargs: { drop_toplevel_vars_fargs: {
options = { keep_fargs: false, toplevel: "vars", unused: true }; options = {
keep_fargs: false,
toplevel: "vars",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -340,11 +352,10 @@ drop_toplevel_vars_fargs: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var c = g;
function f() { function f() {
return function() { return function() {
c = 2; 2;
} };
} }
2; 2;
function g() {} function g() {}
@@ -354,13 +365,16 @@ drop_toplevel_vars_fargs: {
} }
drop_toplevel_all: { drop_toplevel_all: {
options = { toplevel: true, unused: true }; options = {
toplevel: true,
unused: true
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -374,13 +388,16 @@ drop_toplevel_all: {
} }
drop_toplevel_retain: { drop_toplevel_retain: {
options = { top_retain: "f,a,o", unused: true }; options = {
top_retain: "f,a,o",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -388,26 +405,28 @@ drop_toplevel_retain: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var a, c = g; var a;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
a = 2; a = 2;
function g() {}
console.log(3); console.log(3);
} }
} }
drop_toplevel_retain_array: { drop_toplevel_retain_array: {
options = { top_retain: [ "f", "a", "o" ], unused: true }; options = {
top_retain: [ "f", "a", "o" ],
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -415,26 +434,28 @@ drop_toplevel_retain_array: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var a, c = g; var a;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
a = 2; a = 2;
function g() {}
console.log(3); console.log(3);
} }
} }
drop_toplevel_retain_regex: { drop_toplevel_retain_regex: {
options = { top_retain: /^[fao]$/, unused: true }; options = {
top_retain: /^[fao]$/,
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -442,26 +463,29 @@ drop_toplevel_retain_regex: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var a, c = g; var a;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
a = 2; a = 2;
function g() {}
console.log(3); console.log(3);
} }
} }
drop_toplevel_all_retain: { drop_toplevel_all_retain: {
options = { toplevel: true, top_retain: "f,a,o", unused: true }; options = {
toplevel: true,
top_retain: "f,a,o",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -469,26 +493,29 @@ drop_toplevel_all_retain: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var a, c = g; var a;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
a = 2; a = 2;
function g() {}
console.log(3); console.log(3);
} }
} }
drop_toplevel_funcs_retain: { drop_toplevel_funcs_retain: {
options = { toplevel: "funcs", top_retain: "f,a,o", unused: true }; options = {
toplevel: "funcs",
top_retain: "f,a,o",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -500,7 +527,7 @@ drop_toplevel_funcs_retain: {
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -509,13 +536,17 @@ drop_toplevel_funcs_retain: {
} }
drop_toplevel_vars_retain: { drop_toplevel_vars_retain: {
options = { toplevel: "vars", top_retain: "f,a,o", unused: true }; options = {
toplevel: "vars",
top_retain: "f,a,o",
unused: true,
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -523,11 +554,11 @@ drop_toplevel_vars_retain: {
console.log(b = 3); console.log(b = 3);
} }
expect: { expect: {
var a, c = g; var a;
function f(d) { function f(d) {
return function() { return function() {
c = 2; 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -537,13 +568,16 @@ drop_toplevel_vars_retain: {
} }
drop_toplevel_keep_assign: { drop_toplevel_keep_assign: {
options = { toplevel: true, unused: "keep_assign" }; options = {
toplevel: true,
unused: "keep_assign",
}
input: { input: {
var a, b = 1, c = g; var a, b = 1, c = g;
function f(d) { function f(d) {
return function() { return function() {
c = 2; c = 2;
} };
} }
a = 2; a = 2;
function g() {} function g() {}
@@ -753,11 +787,11 @@ issue_1583: {
expect: { expect: {
function m(t) { function m(t) {
(function(e) { (function(e) {
t = function() { (function() {
return (function(a) { return (function(a) {
return function(a) {}; return function(a) {};
})(); })();
}(); })();
})(); })();
} }
} }