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Take operator || precendence into account for AST_If optimization.

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Fixes #979.
This commit is contained in:
kzc
2016-02-21 12:05:02 -05:00
parent bdd8e34f63
commit 5486b68850
2 changed files with 101 additions and 1 deletions
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13
lib/compress.js
View File

@@ -1688,9 +1688,13 @@ merge(Compressor.prototype, {
}
if (is_empty(self.alternative)) self.alternative = null;
var negated = self.condition.negate(compressor);
var negated_is_best = best_of(self.condition, negated) === negated;
var self_condition_length = self.condition.print_to_string().length;
var negated_length = negated.print_to_string().length;
var negated_is_best = negated_length < self_condition_length;
if (self.alternative && negated_is_best) {
negated_is_best = false; // because we already do the switch here.
// no need to swap values of self_condition_length and negated_length
// here because they are only used in an equality comparison later on.
self.condition = negated;
var tmp = self.body;
self.body = self.alternative || make_node(AST_EmptyStatement);
@@ -1712,6 +1716,13 @@ merge(Compressor.prototype, {
}).transform(compressor);
}
if (is_empty(self.alternative) && self.body instanceof AST_SimpleStatement) {
if (self_condition_length === negated_length && !negated_is_best
&& self.condition instanceof AST_Binary && self.condition.operator == "||") {
// although the code length of self.condition and negated are the same,
// negated does not require additional surrounding parentheses.
// see https://github.com/mishoo/UglifyJS2/issues/979
negated_is_best = true;
}
if (negated_is_best) return make_node(AST_SimpleStatement, self, {
body: make_node(AST_Binary, self, {
operator : "||",

89
test/compress/issue-979.js Normal file
View File

@@ -0,0 +1,89 @@
issue979_reported: {
options = {
sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
}
input: {
function f1() {
if (a == 1 || b == 2) {
foo();
}
}
function f2() {
if (!(a == 1 || b == 2)) {
}
else {
foo();
}
}
}
expect: {
function f1() {
1!=a&&2!=b||foo();
}
function f2() {
1!=a&&2!=b||foo();
}
}
}
issue979_test_negated_is_best: {
options = {
sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
}
input: {
function f3() {
if (a == 1 | b == 2) {
foo();
}
}
function f4() {
if (!(a == 1 | b == 2)) {
}
else {
foo();
}
}
function f5() {
if (a == 1 && b == 2) {
foo();
}
}
function f6() {
if (!(a == 1 && b == 2)) {
}
else {
foo();
}
}
function f7() {
if (a == 1 || b == 2) {
foo();
}
else {
return bar();
}
}
}
expect: {
function f3() {
1==a|2==b&&foo();
}
function f4() {
1==a|2==b&&foo();
}
function f5() {
1==a&&2==b&&foo();
}
function f6() {
1!=a||2!=b||foo();
}
function f7() {
return 1!=a&&2!=b?bar():void foo();
}
}
}