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optimize unmodified variables

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This commit is contained in:
alexlamsl 2016-09-20 22:23:27 +08:00
parent 0111497fc9
commit 8646b15314
3 changed files with 69 additions and 5 deletions
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3
lib/compress.js
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@ -67,6 +67,7 @@ function Compressor(options, false_by_default) {
if_return : !false_by_default,
join_vars : !false_by_default,
collapse_vars : false,
reduce_vars : false,
cascade : !false_by_default,
side_effects : !false_by_default,
pure_getters : false,
@ -1107,7 +1108,7 @@ merge(Compressor.prototype, {
this._evaluating = true;
try {
var d = this.definition();
if (d && d.constant && d.init) {
if (d && (d.constant || compressor.option("reduce_vars") && !d.global && !d.modified) && d.init) {
return ev(d.init, compressor);
}
} finally {

9
lib/scope.js
View File

@ -197,7 +197,8 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
}
if (node instanceof AST_SymbolRef) {
var name = node.name;
if (name == "eval" && tw.parent() instanceof AST_Call) {
var parent = tw.parent();
if (name == "eval" && parent instanceof AST_Call) {
for (var s = node.scope; s && !s.uses_eval; s = s.parent_scope) {
s.uses_eval = true;
}
@ -213,12 +214,14 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
g.global = true;
globals.set(name, g);
}
node.thedef = g;
sym = g;
if (func && name == "arguments") {
func.uses_arguments = true;
}
} else {
}
node.thedef = sym;
if (parent instanceof AST_Assign || parent instanceof AST_Unary && (parent.operator === '++' || parent.operator === '--')) {
sym.modified = true;
}
node.reference();
return true;

60
test/compress/reduce_vars.js Normal file
View File

@ -0,0 +1,60 @@
reduce_vars: {
options = {
conditionals : true,
evaluate : true,
global_defs : {
C : 0
},
reduce_vars : true,
unused : true
}
input: {
var A = 1;
(function f0() {
var a = 2;
console.log(a - 5);
console.log(A - 5);
})();
(function f1() {
var a = 2;
console.log(a - 5);
eval("console.log(a);");
})();
(function f2(eval) {
var a = 2;
console.log(a - 5);
eval("console.log(a);");
})(eval);
(function f3() {
var b = typeof C !== "undefined";
var c = 4;
if (b) {
return 'yes';
} else {
return 'no';
}
})();
console.log(A + 1);
}
expect: {
var A = 1;
(function() {
console.log(-3);
console.log(A - 5);
})();
(function f1() {
var a = 2;
console.log(-3);
eval("console.log(a);");
})();
(function f2(eval) {
var a = 2;
console.log(-3);
eval("console.log(a);");
})(eval);
(function() {
return "yes";
})();
console.log(A + 1);
}
}