Merge 423d0146be into 604caa09e7

lib/minify.js

@@ -75,6 +75,7 @@ function minify(files, options) {
             options.mangle = defaults(options.mangle, {
                 cache: options.nameCache && (options.nameCache.vars || {}),
                 eval: false,
+                group_voids: false,
                 ie8: false,
                 keep_fnames: false,
                 properties: false,

lib/scope.js

@@ -400,6 +400,7 @@ AST_Symbol.DEFMETHOD("global", function(){
 AST_Toplevel.DEFMETHOD("_default_mangler_options", function(options) {
     options = defaults(options, {
         eval        : false,
+        group_voids : false,
         ie8         : false,
         keep_fnames : false,
         reserved    : [],
@@ -457,6 +458,15 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options){
     this.walk(tw);
     to_mangle.forEach(function(def){ def.mangle(options) });
 
+    if (!options.group_voids) return;
+    if (options.toplevel) this.group_voids(options);
+    else this.walk(new TreeWalker(function(node) {
+        if (node instanceof AST_Scope && !(node instanceof AST_Toplevel)) {
+            node.group_voids(options);
+            return true;
+        }
+    }));
+
     function collect(symbol) {
         if (!member(symbol.name, options.reserved)) {
             to_mangle.push(symbol);
@@ -522,6 +532,73 @@ AST_Toplevel.DEFMETHOD("expand_names", function(options) {
     }
 });
 
+AST_Scope.DEFMETHOD("group_voids", function(options) {
+    var self = this, enclosed = [];
+    var scopes = [], count = 0;
+    self.walk(new TreeWalker(function(node, descend) {
+        if (node instanceof AST_Scope && node !== self) {
+            scopes.unshift(node);
+            descend();
+            if (scopes[0] === node) scopes.shift();
+            return true;
+        }
+        if (count > 0 && scopes.length == 0) return;
+        if (is_undefined(node)) {
+            count++;
+            var scope;
+            while (scope = scopes.shift()) {
+                scope.enclosed.forEach(function(def) {
+                    push_uniq(enclosed, def);
+                });
+            }
+        }
+    }));
+    if (count < 1) return;
+    var save = self.enclosed;
+    self.enclosed = enclosed;
+    var name = next_mangled(self, options);
+    self.enclosed = save;
+    this.transform(new TreeTransformer(function(node) {
+        if (is_undefined(node)) return new AST_SymbolRef({
+            name: name,
+            start: node.start,
+            end: node.end
+        });
+    }));
+    for (var i = 0, len = this.body.length; i < len; i++) {
+        var stat = this.body[i];
+        if (stat instanceof AST_Var) {
+            stat.definitions.push(make_var_def(stat));
+            return;
+        }
+    }
+    this.body.push(new AST_Var({
+        definitions: [ make_var_def(this) ],
+        start: this.start,
+        end: this.end
+    }));
+
+    function is_undefined(node) {
+        return node instanceof AST_Undefined
+            || node instanceof AST_UnaryPrefix
+                && node.operator == "void"
+                && node.expression.is_constant();
+    }
+
+    function make_var_def(node) {
+        return new AST_VarDef({
+            name: new AST_SymbolVar({
+                name: name,
+                start: node.start,
+                end: node.end
+            }),
+            value: null,
+            start: node.start,
+            end: node.end
+        });
+    }
+});
+
 AST_Node.DEFMETHOD("tail_node", return_this);
 AST_Sequence.DEFMETHOD("tail_node", function() {
     return this.expressions[this.expressions.length - 1];

test/compress/group_voids.js

@@ -0,0 +1,196 @@
+group_voids: {
+    options = {
+    }
+    mangle = {
+        group_voids: true,
+        toplevel: false,
+    }
+    input: {
+        var a = 0;
+        x = void 0;
+        if (void 0 === b)
+            c = void 0;
+        function f1() {
+            var a = 1;
+            console.log(void 0);
+        }
+        function f2(undefined) {
+            var a = 2;
+            console.log(void 0);
+        }
+        function f3() {
+            var undefined = 3;
+            console.log(void 0);
+        }
+        function f4() {
+            console.log(void 0);
+            for (var a = 4;;);
+            var b = 4;
+            function g() {
+                var c = 5;
+                var d = 5;
+                console.log(void 0);
+            }
+        }
+        function f5() {
+            try {
+                var a = 6;
+                console.log(void 0);
+            } catch (e) {
+                console.log(void 0);
+            }
+        }
+    }
+    expect: {
+        var a = 0;
+        x = void 0;
+        if (void 0 === b)
+            c = void 0;
+        function f1() {
+            var o = 1, n;
+            console.log(n);
+        }
+        function f2(o) {
+            var n = 2, v;
+            console.log(v);
+        }
+        function f3() {
+            var o = 3, n;
+            console.log(n);
+        }
+        function f4() {
+            console.log(i);
+            for(var o = 4;;);
+            var n = 4, i;
+            function v() {
+                var o = 5;
+                var n = 5;
+                console.log(i);
+            }
+        }
+        function f5() {
+            try {
+                var o = 6;
+                console.log(n);
+            } catch (o) {
+                console.log(n);
+            }
+            var n;
+        }
+    }
+}
+
+group_voids_toplevel: {
+    options = {
+    }
+    mangle = {
+        group_voids: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0;
+        x = void 0;
+        if (void 0 === b)
+            c = void 0;
+        function f1() {
+            var a = 1;
+            console.log(void 0);
+        }
+        function f2(undefined) {
+            var a = 2;
+            console.log(void 0);
+        }
+        function f3() {
+            var undefined = 3;
+            console.log(void 0);
+        }
+        function f4() {
+            console.log(void 0);
+            for (var a = 4;;);
+            var b = 4;
+            function g() {
+                var c = 5;
+                var d = 5;
+                console.log(void 0);
+            }
+        }
+        function f5() {
+            try {
+                var a = 6;
+                console.log(void 0);
+            } catch (e) {
+                console.log(void 0);
+            }
+        }
+    }
+    expect: {
+        var o = 0, a;
+        x = a;
+        if (a === b)
+            c = a;
+        function n() {
+            var o = 1;
+            console.log(a);
+        }
+        function v(o) {
+            var n = 2;
+            console.log(a);
+        }
+        function i() {
+            var o = 3;
+            console.log(a);
+        }
+        function l() {
+            console.log(a);
+            for(var o = 4;;);
+            var n = 4;
+            function v() {
+                var o = 5;
+                var n = 5;
+                console.log(a);
+            }
+        }
+        function r() {
+            try {
+                var o = 6;
+                console.log(a);
+            } catch (o) {
+                console.log(a);
+            }
+        }
+    }
+}
+
+group_voids_catch: {
+    options = {
+    }
+    mangle = {
+        group_voids: true,
+    }
+    input: {
+        (function() {
+            var a = 1;
+            console.log(void 0);
+            try {
+                throw "FAIL";
+            } catch (undefined) {
+                console.log(void 0);
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            var o = 1, c;
+            console.log(c);
+            try {
+                throw "FAIL";
+            } catch (o) {
+                console.log(c);
+            }
+        })();
+    }
+    expect_stdout: [
+        "undefined",
+        "undefined",
+    ]
+}