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drop assignment in AST_VarDef.value (#2522)

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fixes #2516
This commit is contained in:
Alex Lam S.L
2017-11-28 13:08:40 +08:00
committed by GitHub
parent b37a68c84f
commit ecc9f6b770
3 changed files with 118 additions and 37 deletions
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59
lib/compress.js
View File

@@ -1088,6 +1088,7 @@ merge(Compressor.prototype, {
function get_lhs(expr) {
if (expr instanceof AST_VarDef) {
var def = expr.name.definition();
if (!member(expr.name, def.orig)) return;
var declared = def.orig.length - def.eliminated;
var referenced = def.references.length - def.replaced;
if (declared > 1 && !(expr.name instanceof AST_SymbolFunarg)
@@ -2434,47 +2435,18 @@ merge(Compressor.prototype, {
});
return true;
}
var sym;
if (scope === self
&& (sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& self.variables.get(sym.name) === sym.definition()) {
if (node instanceof AST_Assign) node.right.walk(tw);
return true;
}
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
return true;
}
if (node instanceof AST_Scope) {
var save_scope = scope;
scope = node;
descend();
scope = save_scope;
return true;
}
return scan_ref_scoped(node, descend);
});
self.walk(tw);
// pass 2: for every used symbol we need to walk its
// initialization code to figure out if it uses other
// symbols (that may not be in_use).
tw = new TreeWalker(scan_ref_scoped);
for (var i = 0; i < in_use.length; ++i) {
in_use[i].orig.forEach(function(decl){
// undeclared globals will be instanceof AST_SymbolRef
var init = initializations.get(decl.name);
if (init) init.forEach(function(init){
var tw = new TreeWalker(function(node){
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
}
});
init.walk(tw);
});
});
@@ -2663,6 +2635,31 @@ merge(Compressor.prototype, {
}
);
self.transform(tt);
function scan_ref_scoped(node, descend) {
var sym;
if (scope === self
&& (sym = assign_as_unused(node)) instanceof AST_SymbolRef
&& self.variables.get(sym.name) === sym.definition()) {
if (node instanceof AST_Assign) node.right.walk(tw);
return true;
}
if (node instanceof AST_SymbolRef) {
var node_def = node.definition();
if (!(node_def.id in in_use_ids)) {
in_use_ids[node_def.id] = true;
in_use.push(node_def);
}
return true;
}
if (node instanceof AST_Scope) {
var save_scope = scope;
scope = node;
descend();
scope = save_scope;
return true;
}
}
});
AST_Scope.DEFMETHOD("hoist_declarations", function(compressor){

16
test/compress/collapse_vars.js
View File

@@ -705,7 +705,7 @@ collapse_vars_lvalues_drop_assign: {
function f2(x) { var z = x, a = ++z; return z += a; }
function f3(x) { var a = (x -= 3); return x + a; }
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { e1(); var v = e2(), c = v = --x; return x - c; }
function f5(x) { e1(), e2(); var c = --x; return x - c; }
function f6(x) { e1(), e2(); return --x - x; }
function f7(x) { e1(); return x - (e2() - x); }
function f8(x) { e1(); return x - (e2() - x); }
@@ -2386,6 +2386,7 @@ duplicate_argname: {
issue_2298: {
options = {
collapse_vars: true,
passes: 2,
reduce_funcs: true,
reduce_vars: true,
unused: true,
@@ -3087,13 +3088,14 @@ issue_2437: {
}
expect: {
!function() {
if (xhrDesc)
return result = !!(req = new XMLHttpRequest()).onreadystatechange,
Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {}),
if (xhrDesc) {
var result = !!(req = new XMLHttpRequest()).onreadystatechange;
return Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {}),
result;
}
var req = new XMLHttpRequest(), detectFunc = function() {};
req.onreadystatechange = detectFunc;
var result = req[SYMBOL_FAKE_ONREADYSTATECHANGE_1] === detectFunc;
req.onreadystatechange = detectFunc,
result = req[SYMBOL_FAKE_ONREADYSTATECHANGE_1] === detectFunc,
req.onreadystatechange = null;
}();
}
@@ -3522,6 +3524,7 @@ issue_2436_12: {
issue_2436_13: {
options = {
collapse_vars: true,
passes: 2,
reduce_vars: true,
unused: true,
}
@@ -3622,6 +3625,7 @@ issue_2497: {
issue_2506: {
options = {
collapse_vars: true,
passes: 2,
reduce_vars: true,
unused: true,
}

80
test/compress/drop-unused.js
View File

@@ -1299,3 +1299,83 @@ issue_2288: {
}
}
}
issue_2516_1: {
options = {
collapse_vars: true,
reduce_funcs: true,
reduce_vars: true,
unused: true,
}
input: {
function foo() {
function qux(x) {
bar.call(null, x);
}
function bar(x) {
var FOUR = 4;
var trouble = x || never_called();
var value = (FOUR - 1) * trouble;
console.log(value == 6 ? "PASS" : value);
}
Baz = qux;
}
var Baz;
foo();
Baz(2);
}
expect: {
function foo() {
Baz = function(x) {
(function(x) {
var trouble = x || never_called();
var value = (4 - 1) * trouble;
console.log(6 == value ? "PASS" : value);
}).call(null, x);
};
}
var Baz;
foo();
Baz(2);
}
}
issue_2516_2: {
options = {
collapse_vars: true,
reduce_funcs: true,
reduce_vars: true,
passes: 2,
unused: true,
}
input: {
function foo() {
function qux(x) {
bar.call(null, x);
}
function bar(x) {
var FOUR = 4;
var trouble = x || never_called();
var value = (FOUR - 1) * trouble;
console.log(value == 6 ? "PASS" : value);
}
Baz = qux;
}
var Baz;
foo();
Baz(2);
}
expect: {
function foo() {
Baz = function(x) {
(function(x) {
var value = (4 - 1) * (x || never_called());
console.log(6 == value ? "PASS" : value);
}).call(null, x);
};
}
var Baz;
foo();
Baz(2);
}
}