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fix unsafe on evaluate of reduce_vars (#1870)
Determine if variables with non-constant values can escape and be modified.

fixes #1865
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alexlamsl committed May 6, 2017
1 parent ecf3563 commit 2c7ee95
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Showing 2 changed files with 85 additions and 35 deletions.
28 changes: 17 additions & 11 deletions lib/compress.js
Expand Up @@ -283,6 +283,14 @@ merge(Compressor.prototype, {
if (d.fixed === undefined || !safe_to_read(d)
|| is_modified(node, 0, is_immutable(node.fixed_value()))) {
d.fixed = false;
} else {
var parent = tw.parent();
if (parent instanceof AST_Assign && parent.operator == "=" && node === parent.right
|| parent instanceof AST_Call && node !== parent.expression
|| parent instanceof AST_Return && node === parent.value && node.scope !== d.scope
|| parent instanceof AST_VarDef && node === parent.value) {
d.escaped = true;
}
}
}
if (node instanceof AST_SymbolCatch) {
Expand Down Expand Up @@ -482,6 +490,7 @@ merge(Compressor.prototype, {
}

function reset_def(def) {
def.escaped = false;
if (!def.global || def.orig[0] instanceof AST_SymbolConst || compressor.toplevel(def)) {
def.fixed = undefined;
} else {
Expand Down Expand Up @@ -1595,23 +1604,20 @@ merge(Compressor.prototype, {
: ev(this.alternative, compressor);
});
def(AST_SymbolRef, function(compressor){
if (this._evaluating) throw def;
if (!compressor.option("reduce_vars") || this._evaluating) throw def;
this._evaluating = true;
try {
var fixed = this.fixed_value();
if (compressor.option("reduce_vars") && fixed) {
if (compressor.option("unsafe")) {
if (!HOP(fixed, "_evaluated")) {
fixed._evaluated = ev(fixed, compressor);
}
return fixed._evaluated;
}
return ev(fixed, compressor);
}
if (!fixed) throw def;
var value = ev(fixed, compressor);
if (!HOP(fixed, "_eval")) fixed._eval = function() {
return value;
};
if (value && typeof value == "object" && this.definition().escaped) throw def;
return value;
} finally {
this._evaluating = false;
}
throw def;
});
def(AST_PropAccess, function(compressor){
if (compressor.option("unsafe")) {
Expand Down
92 changes: 68 additions & 24 deletions test/compress/reduce_vars.js
Expand Up @@ -297,55 +297,70 @@ unsafe_evaluate_array: {
}
}

unsafe_evaluate_equality: {
unsafe_evaluate_equality_1: {
options = {
evaluate : true,
reduce_vars : true,
unsafe : true,
unused : true
}
input: {
function f0(){
function f0() {
var a = {};
console.log(a === a);
return a === a;
}

function f1(){
function f1() {
var a = [];
console.log(a === a);
return a === a;
}
console.log(f0(), f1());
}
expect: {
function f0() {
return true;
}
function f1() {
return true;
}
console.log(f0(), f1());
}
expect_stdout: true
}

function f2(){
unsafe_evaluate_equality_2: {
options = {
collapse_vars: true,
evaluate : true,
passes : 2,
reduce_vars : true,
unsafe : true,
unused : true
}
input: {
function f2() {
var a = {a:1, b:2};
var b = a;
var c = a;
console.log(b === c);
return b === c;
}

function f3(){
function f3() {
var a = [1, 2, 3];
var b = a;
var c = a;
console.log(b === c);
return b === c;
}
console.log(f2(), f3());
}
expect: {
function f0(){
console.log(true);
}

function f1(){
console.log(true);
}

function f2(){
console.log(true);
function f2() {
return true;
}

function f3(){
console.log(true);
function f3() {
return true;
}
console.log(f2(), f3());
}
expect_stdout: true
}

passes: {
Expand Down Expand Up @@ -2417,3 +2432,32 @@ issue_1850_4: {
}
expect_stdout: true
}

issue_1865: {
options = {
evaluate: true,
reduce_vars: true,
unsafe: true,
}
input: {
function f(a) {
a.b = false;
}
console.log(function() {
var some = { thing: true };
f(some);
return some.thing;
}());
}
expect: {
function f(a) {
a.b = false;
}
console.log(function() {
var some = { thing: true };
f(some);
return some.thing;
}());
}
expect_stdout: true
}

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