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fix escape analysis on AST_PropAccess (#2636)
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@alexlamsl
alexlamsl committed Dec 23, 2017
1 parent edb4e3b commit c07ea17
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Showing 2 changed files with 76 additions and 50 deletions.
95 changes: 45 additions & 50 deletions lib/compress.js
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Expand Up @@ -418,29 +418,27 @@ merge(Compressor.prototype, {
}
}

function mark_escaped(tw, d, scope, node, value, level) {
function mark_escaped(tw, d, scope, node, value, level, depth) {
var parent = tw.parent(level);
if (value) {
if (value.is_constant()) return;
if (level > 0 && value.is_constant_expression(scope)) return;
}
if (value && value.is_constant()) return;
if (parent instanceof AST_Assign && parent.operator == "=" && node === parent.right
|| parent instanceof AST_Call && node !== parent.expression
|| parent instanceof AST_Exit && node === parent.value && node.scope !== d.scope
|| parent instanceof AST_VarDef && node === parent.value) {
d.escaped = true;
if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1;
if (!d.escaped || d.escaped > depth) d.escaped = depth;
return;
} else if (parent instanceof AST_Array
|| parent instanceof AST_Binary && lazy_op(parent.operator)
|| parent instanceof AST_Conditional && node !== parent.condition
|| parent instanceof AST_Sequence && node === parent.tail_node()) {
mark_escaped(tw, d, scope, parent, parent, level + 1);
mark_escaped(tw, d, scope, parent, parent, level + 1, depth);
} else if (parent instanceof AST_ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1);
mark_escaped(tw, d, scope, obj, obj, level + 2);
mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
} else if (parent instanceof AST_PropAccess && node === parent.expression) {
value = read_property(value, parent.property);
mark_escaped(tw, d, scope, parent, value, level + 1);
mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
if (value) return;
}
if (level == 0) d.direct_access = true;
Expand Down Expand Up @@ -637,7 +635,7 @@ merge(Compressor.prototype, {
}
}
}
mark_escaped(tw, d, this.scope, this, value, 0);
mark_escaped(tw, d, this.scope, this, value, 0, 1);
});
def(AST_Toplevel, function(tw, descend, compressor) {
this.globals.each(function(def) {
Expand Down Expand Up @@ -1909,7 +1907,7 @@ merge(Compressor.prototype, {
// descendant of AST_Node.
AST_Node.DEFMETHOD("evaluate", function(compressor){
if (!compressor.option("evaluate")) return this;
var val = this._eval(compressor);
var val = this._eval(compressor, 1);
return !val || val instanceof RegExp || typeof val != "object" ? val : this;
});
var unaryPrefix = makePredicate("! ~ - + void");
Expand All @@ -1928,30 +1926,25 @@ merge(Compressor.prototype, {
throw new Error(string_template("Cannot evaluate a statement [{file}:{line},{col}]", this.start));
});
def(AST_Lambda, return_this);
function ev(node, compressor) {
if (!compressor) throw new Error("Compressor must be passed");

return node._eval(compressor);
};
def(AST_Node, return_this);
def(AST_Constant, function(){
return this.getValue();
});
def(AST_Array, function(compressor){
def(AST_Array, function(compressor, depth) {
if (compressor.option("unsafe")) {
var elements = [];
for (var i = 0, len = this.elements.length; i < len; i++) {
var element = this.elements[i];
if (element instanceof AST_Function) continue;
var value = ev(element, compressor);
var value = element._eval(compressor, depth);
if (element === value) return this;
elements.push(value);
}
return elements;
}
return this;
});
def(AST_Object, function(compressor){
def(AST_Object, function(compressor, depth) {
if (compressor.option("unsafe")) {
var val = {};
for (var i = 0, len = this.properties.length; i < len; i++) {
Expand All @@ -1960,21 +1953,21 @@ merge(Compressor.prototype, {
if (key instanceof AST_Symbol) {
key = key.name;
} else if (key instanceof AST_Node) {
key = ev(key, compressor);
key = key._eval(compressor, depth);
if (key === prop.key) return this;
}
if (typeof Object.prototype[key] === 'function') {
return this;
}
if (prop.value instanceof AST_Function) continue;
val[key] = ev(prop.value, compressor);
val[key] = prop.value._eval(compressor, depth);
if (val[key] === prop.value) return this;
}
return val;
}
return this;
});
def(AST_UnaryPrefix, function(compressor){
def(AST_UnaryPrefix, function(compressor, depth) {
var e = this.expression;
// Function would be evaluated to an array and so typeof would
// incorrectly return 'object'. Hence making is a special case.
Expand All @@ -1985,7 +1978,7 @@ merge(Compressor.prototype, {
&& e.fixed_value() instanceof AST_Lambda)) {
return typeof function(){};
}
e = ev(e, compressor);
e = e._eval(compressor, depth);
if (e === this.expression) return this;
switch (this.operator) {
case "!": return !e;
Expand All @@ -2001,10 +1994,10 @@ merge(Compressor.prototype, {
}
return this;
});
def(AST_Binary, function(compressor){
var left = ev(this.left, compressor);
def(AST_Binary, function(compressor, depth) {
var left = this.left._eval(compressor, depth);
if (left === this.left) return this;
var right = ev(this.right, compressor);
var right = this.right._eval(compressor, depth);
if (right === this.right) return this;
var result;
switch (this.operator) {
Expand Down Expand Up @@ -2038,30 +2031,32 @@ merge(Compressor.prototype, {
}
return result;
});
def(AST_Conditional, function(compressor){
var condition = ev(this.condition, compressor);
def(AST_Conditional, function(compressor, depth) {
var condition = this.condition._eval(compressor, depth);
if (condition === this.condition) return this;
var node = condition ? this.consequent : this.alternative;
var value = ev(node, compressor);
var value = node._eval(compressor, depth);
return value === node ? this : value;
});
def(AST_SymbolRef, function(compressor){
def(AST_SymbolRef, function(compressor, depth) {
var fixed = this.fixed_value();
if (!fixed) return this;
this._eval = return_this;
var value = ev(fixed, compressor);
if (value === fixed) {
var value;
if (HOP(fixed, "_eval")) {
value = fixed._eval();
} else {
this._eval = return_this;
value = fixed._eval(compressor, depth);
delete this._eval;
return this;
if (value === fixed) return this;
fixed._eval = function() {
return value;
};
}
if (!HOP(fixed, "_eval")) fixed._eval = function() {
return value;
};
if (value && typeof value == "object" && this.definition().escaped) {
delete this._eval;
return this;
if (value && typeof value == "object") {
var escaped = this.definition().escaped;
if (escaped && depth > escaped) return this;
}
this._eval = fixed._eval;
return value;
});
var global_objs = {
Expand Down Expand Up @@ -2095,11 +2090,11 @@ merge(Compressor.prototype, {
],
};
convert_to_predicate(static_values);
def(AST_PropAccess, function(compressor){
def(AST_PropAccess, function(compressor, depth) {
if (compressor.option("unsafe")) {
var key = this.property;
if (key instanceof AST_Node) {
key = ev(key, compressor);
key = key._eval(compressor, depth);
if (key === this.property) return this;
}
var exp = this.expression;
Expand All @@ -2108,7 +2103,7 @@ merge(Compressor.prototype, {
if (!(static_values[exp.name] || return_false)(key)) return this;
val = global_objs[exp.name];
} else {
val = ev(exp, compressor);
val = exp._eval(compressor, depth + 1);
if (!val || val === exp || !HOP(val, key)) return this;
}
return val[key];
Expand Down Expand Up @@ -2186,12 +2181,12 @@ merge(Compressor.prototype, {
],
};
convert_to_predicate(static_fns);
def(AST_Call, function(compressor){
def(AST_Call, function(compressor, depth) {
var exp = this.expression;
if (compressor.option("unsafe") && exp instanceof AST_PropAccess) {
var key = exp.property;
if (key instanceof AST_Node) {
key = ev(key, compressor);
key = key._eval(compressor, depth);
if (key === exp.property) return this;
}
var val;
Expand All @@ -2200,13 +2195,13 @@ merge(Compressor.prototype, {
if (!(static_fns[e.name] || return_false)(key)) return this;
val = global_objs[e.name];
} else {
val = ev(e, compressor);
val = e._eval(compressor, depth + 1);
if (val === e || !(val && native_fns[val.constructor.name] || return_false)(key)) return this;
}
var args = [];
for (var i = 0, len = this.args.length; i < len; i++) {
var arg = this.args[i];
var value = ev(arg, compressor);
var value = arg._eval(compressor, depth);
if (arg === value) return this;
args.push(value);
}
Expand Down Expand Up @@ -3083,7 +3078,7 @@ merge(Compressor.prototype, {
if (node instanceof AST_VarDef) {
var sym = node.name, def, value;
if (sym.scope === self
&& !(def = sym.definition()).escaped
&& (def = sym.definition()).escaped != 1
&& !def.single_use
&& !def.direct_access
&& !top_retain(def)
Expand Down Expand Up @@ -4698,7 +4693,7 @@ merge(Compressor.prototype, {
if (d.single_use && fixed instanceof AST_Function) {
if (d.scope !== self.scope
&& (!compressor.option("reduce_funcs")
|| d.escaped
|| d.escaped == 1
|| fixed.inlined)) {
d.single_use = false;
} else if (recursive_ref(compressor, d)) {
Expand Down
31 changes: 31 additions & 0 deletions test/compress/reduce_vars.js
View file
Expand Up @@ -3422,6 +3422,37 @@ escaped_prop_1: {
}

escaped_prop_2: {
options = {
collapse_vars: true,
evaluate: true,
inline: true,
passes: 2,
pure_getters: "strict",
reduce_funcs: true,
reduce_vars: true,
side_effects: true,
toplevel: true,
unsafe: true,
unused: true,
}
input: {
var obj = { o: { a: 1 } };
(function(o) {
o.a++;
})(obj.o);
(function(o) {
console.log(o.a);
})(obj.o);
}
expect: {
var obj = { o: { a: 1 } };
obj.o.a++;
console.log(obj.o.a);
}
expect_stdout: "2"
}

escaped_prop_3: {
options = {
reduce_funcs: true,
reduce_vars: true,
Expand Down

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