diff --git a/README.md b/README.md
index 368492c342a..96014f4c17f 100644
--- a/README.md
+++ b/README.md
@@ -75,8 +75,6 @@ The available options are:
   --support-ie8                 Use this flag to support Internet Explorer 6/7/8.
                                 Equivalent to setting `screw_ie8: false` in `minify()`
                                 for `compress`, `mangle` and `output` options.
-                                Note: `--support-ie8` may generate incorrect code
-                                for `try`/`catch` in ES5 compliant browsers.
   --expr                        Parse a single expression, rather than a
                                 program (for parsing JSON)
   -p, --prefix                  Skip prefix for original filenames that appear
@@ -350,6 +348,9 @@ to set `true`; it's effectively a shortcut for `foo=true`).
   comparison are switching. Compression only works if both `comparisons` and
   `unsafe_comps` are both set to true.
 
+- `unsafe_math` (default: false) -- optimize numerical expressions like
+  `2 * x * 3` into `6 * x`, which may give imprecise floating point results.
+
 - `unsafe_proto` (default: false) -- optimize expressions like
   `Array.prototype.slice.call(a)` into `[].slice.call(a)`
 
@@ -423,6 +424,9 @@ to set `true`; it's effectively a shortcut for `foo=true`).
   such as `console.info` and/or retain side effects from function arguments
   after dropping the function call then use `pure_funcs` instead.
 
+- `expression` -- default `false`.  Pass `true` to preserve completion values
+  from terminal statements without `return`, e.g. in bookmarklets.
+
 - `keep_fargs` -- default `true`.  Prevents the
   compressor from discarding unused function arguments.  You need this
   for code which relies on `Function.length`.
diff --git a/bin/uglifyjs b/bin/uglifyjs
index 367d66e2cb0..e39a4b4bf27 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -8,7 +8,6 @@ var sys = require("util");
 var yargs = require("yargs");
 var fs = require("fs");
 var path = require("path");
-var async = require("async");
 var acorn;
 var screw_ie8 = true;
 var ARGS = yargs
@@ -27,7 +26,7 @@ mangling you need to use `-c` and `-m`.\
     .describe("source-map-include-sources", "Pass this flag if you want to include the content of source files in the source map as sourcesContent property.")
     .describe("in-source-map", "Input source map, useful if you're compressing JS that was generated from some other original code.")
     .describe("screw-ie8", "Do not support Internet Explorer 6/7/8. This flag is enabled by default.")
-    .describe("support-ie8", "Support non-standard Internet Explorer 6/7/8 javascript. Note: may generate incorrect code for try/catch in ES5 compliant browsers.")
+    .describe("support-ie8", "Support non-standard Internet Explorer 6/7/8 javascript.")
     .describe("expr", "Parse a single expression, rather than a program (for parsing JSON)")
     .describe("p", "Skip prefix for original filenames that appear in source maps. \
 For example -p 3 will drop 3 directories from file names and ensure they are relative paths. \
@@ -319,8 +318,11 @@ var STATS = {};
 var TOPLEVEL = null;
 var P_RELATIVE = ARGS.p && ARGS.p == "relative";
 var SOURCES_CONTENT = {};
+var index = 0;
 
-async.eachLimit(files, 1, function (file, cb) {
+!function cb() {
+    if (index == files.length) return done();
+    var file = files[index++];
     read_whole_file(file, function (err, code) {
         if (err) {
             print_error("ERROR: can't read file: " + file);
@@ -388,7 +390,9 @@ async.eachLimit(files, 1, function (file, cb) {
         });
         cb();
     });
-}, function () {
+}();
+
+function done() {
     var OUTPUT_FILE = ARGS.o;
 
     var SOURCE_MAP = (ARGS.source_map || ARGS.source_map_inline) ? UglifyJS.SourceMap({
@@ -537,7 +541,7 @@ async.eachLimit(files, 1, function (file, cb) {
             }));
         }
     }
-});
+}
 
 /* -----[ functions ]----- */
 
diff --git a/lib/ast.js b/lib/ast.js
index 64352ae04ea..cd32ead769c 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -1104,9 +1104,6 @@ var AST_SymbolAccessor = DEFNODE("SymbolAccessor", null, {
 
 var AST_SymbolDeclaration = DEFNODE("SymbolDeclaration", "init", {
     $documentation: "A declaration symbol (symbol in var/const, function name or argument, symbol in catch)",
-    $propdoc: {
-        init: "[AST_Node*/S] array of initializers for this declaration."
-    },
 }, AST_Symbol);
 
 var AST_SymbolVar = DEFNODE("SymbolVar", null, {
diff --git a/lib/compress.js b/lib/compress.js
index 253d5699c75..11a1ff1cc03 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -54,6 +54,7 @@ function Compressor(options, false_by_default) {
         drop_debugger : !false_by_default,
         unsafe        : false,
         unsafe_comps  : false,
+        unsafe_math   : false,
         unsafe_proto  : false,
         conditionals  : !false_by_default,
         comparisons   : !false_by_default,
@@ -80,6 +81,7 @@ function Compressor(options, false_by_default) {
         ecma          : 5,
         drop_console  : false,
         angular       : false,
+        expression    : false,
         warnings      : true,
         global_defs   : {},
         passes        : 1,
@@ -116,12 +118,18 @@ Compressor.prototype = new TreeTransformer;
 merge(Compressor.prototype, {
     option: function(key) { return this.options[key] },
     compress: function(node) {
+        if (this.option("expression")) {
+            node = node.process_expression(true);
+        }
         var passes = +this.options.passes || 1;
         for (var pass = 0; pass < passes && pass < 3; ++pass) {
             if (pass > 0 || this.option("reduce_vars"))
                 node.reset_opt_flags(this, true);
             node = node.transform(this);
         }
+        if (this.option("expression")) {
+            node = node.process_expression(false);
+        }
         return node;
     },
     warn: function(text, props) {
@@ -178,8 +186,45 @@ merge(Compressor.prototype, {
         return this.print_to_string() == node.print_to_string();
     });
 
+    AST_Node.DEFMETHOD("process_expression", function(insert) {
+        var self = this;
+        var tt = new TreeTransformer(function(node) {
+            if (insert && node instanceof AST_SimpleStatement) {
+                return make_node(AST_Return, node, {
+                    value: node.body
+                });
+            }
+            if (!insert && node instanceof AST_Return) {
+                return make_node(AST_SimpleStatement, node, {
+                    body: node.value || make_node(AST_Undefined, node)
+                });
+            }
+            if (node instanceof AST_Lambda && node !== self) {
+                return node;
+            }
+            if (node instanceof AST_Block) {
+                var index = node.body.length - 1;
+                if (index >= 0) {
+                    node.body[index] = node.body[index].transform(tt);
+                }
+            }
+            if (node instanceof AST_If) {
+                node.body = node.body.transform(tt);
+                if (node.alternative) {
+                    node.alternative = node.alternative.transform(tt);
+                }
+            }
+            if (node instanceof AST_With) {
+                node.body = node.body.transform(tt);
+            }
+            return node;
+        });
+        return self.transform(tt);
+    });
+
     AST_Node.DEFMETHOD("reset_opt_flags", function(compressor, rescan){
         var reduce_vars = rescan && compressor.option("reduce_vars");
+        var ie8 = !compressor.option("screw_ie8");
         var safe_ids = [];
         push();
         var suppressor = new TreeWalker(function(node) {
@@ -189,7 +234,7 @@ merge(Compressor.prototype, {
                 d.fixed = false;
             }
         });
-        var tw = new TreeWalker(function(node){
+        var tw = new TreeWalker(function(node, descend){
             if (!(node instanceof AST_Directive || node instanceof AST_Constant)) {
                 node._squeezed = false;
                 node._optimized = false;
@@ -204,6 +249,9 @@ merge(Compressor.prototype, {
                         d.fixed = false;
                     }
                 }
+                if (ie8 && node instanceof AST_SymbolCatch) {
+                    node.definition().fixed = false;
+                }
                 if (node instanceof AST_VarDef) {
                     if (node.name instanceof AST_Destructuring) {
                         node.name.walk(suppressor);
@@ -262,6 +310,12 @@ merge(Compressor.prototype, {
                     pop();
                     return true;
                 }
+                if (node instanceof AST_Catch) {
+                    push();
+                    descend();
+                    pop();
+                    return true;
+                }
             }
         });
         this.walk(tw);
@@ -494,11 +548,10 @@ merge(Compressor.prototype, {
                     // Constant single use vars can be replaced in any scope.
                     if (var_decl.value.is_constant()) {
                         var ctt = new TreeTransformer(function(node) {
-                            if (node === ref) {
-                                var parent = ctt.parent();
-                                if (!(parent instanceof AST_ForIn && parent.init === node)) {
-                                    return replace_var(node, parent, true);
-                                }
+                            if (node === ref
+                                && !ctt.find_parent(AST_Destructuring)
+                                && !ctt.find_parent(AST_ForIn)) {
+                                return replace_var(node, ctt.parent(), true);
                             }
                         });
                         stat.transform(ctt);
@@ -529,6 +582,7 @@ merge(Compressor.prototype, {
                             if (unwind) return node;
                             var parent = tt.parent();
                             if (node instanceof AST_Lambda
+                                || node instanceof AST_Destructuring
                                 || node instanceof AST_Try
                                 || node instanceof AST_With
                                 || node instanceof AST_Case
@@ -568,10 +622,7 @@ merge(Compressor.prototype, {
             return statements;
 
             function is_lvalue(node, parent) {
-                return node instanceof AST_SymbolRef && (
-                    (parent instanceof AST_Assign && node === parent.left)
-                    || (parent instanceof AST_Unary && parent.expression === node
-                        && (parent.operator == "++" || parent.operator == "--")));
+                return node instanceof AST_SymbolRef && isLHS(node, parent);
             }
             function replace_var(node, parent, is_constant) {
                 if (is_lvalue(node, parent)) return node;
@@ -744,7 +795,7 @@ merge(Compressor.prototype, {
                             CHANGED = true;
                             stat = stat.clone();
                             stat.alternative = ret[0] || make_node(AST_Return, stat, {
-                                value: make_node(AST_Undefined, stat)
+                                value: null
                             });
                             ret[0] = stat.transform(compressor);
                             continue loop;
@@ -777,7 +828,7 @@ merge(Compressor.prototype, {
                             && !stat.alternative) {
                             CHANGED = true;
                             ret.push(make_node(AST_Return, ret[0], {
-                                value: make_node(AST_Undefined, ret[0])
+                                value: null
                             }).transform(compressor));
                             ret.unshift(stat);
                             continue loop;
@@ -1034,6 +1085,10 @@ merge(Compressor.prototype, {
         }));
     };
 
+    function is_undefined(node) {
+        return node instanceof AST_Undefined || node.is_undefined;
+    }
+
     /* -----[ boolean/negation helpers ]----- */
 
     // methods to determine whether an expression has a boolean result type
@@ -1064,6 +1119,34 @@ merge(Compressor.prototype, {
         node.DEFMETHOD("is_boolean", func);
     });
 
+    // methods to determine if an expression has a numeric result type
+    (function (def){
+        def(AST_Node, return_false);
+        def(AST_Number, return_true);
+        var unary = makePredicate("+ - ~ ++ --");
+        def(AST_Unary, function(){
+            return unary(this.operator);
+        });
+        var binary = makePredicate("- * / % & | ^ << >> >>>");
+        def(AST_Binary, function(compressor){
+            return binary(this.operator) || this.operator == "+"
+                && this.left.is_number(compressor)
+                && this.right.is_number(compressor);
+        });
+        var assign = makePredicate("-= *= /= %= &= |= ^= <<= >>= >>>=");
+        def(AST_Assign, function(compressor){
+            return assign(this.operator) || this.right.is_number(compressor);
+        });
+        def(AST_Seq, function(compressor){
+            return this.cdr.is_number(compressor);
+        });
+        def(AST_Conditional, function(compressor){
+            return this.consequent.is_number(compressor) && this.alternative.is_number(compressor);
+        });
+    })(function(node, func){
+        node.DEFMETHOD("is_number", func);
+    });
+
     // methods to determine if an expression has a string result type
     (function (def){
         def(AST_Node, function(){ return false });
@@ -1092,7 +1175,7 @@ merge(Compressor.prototype, {
     });
 
     function isLHS(node, parent) {
-        return parent instanceof AST_Unary && (parent.operator === "++" || parent.operator === "--")
+        return parent instanceof AST_Unary && (parent.operator == "++" || parent.operator == "--")
             || parent instanceof AST_Assign && parent.left === node;
     }
 
@@ -2117,7 +2200,14 @@ merge(Compressor.prototype, {
         def(AST_Constant, return_null);
         def(AST_This, return_null);
         def(AST_Call, function(compressor, first_in_statement){
-            if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) return this;
+            if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) {
+                if (this.expression instanceof AST_Function) {
+                    var node = this.clone();
+                    node.expression = node.expression.process_expression(false);
+                    return node;
+                }
+                return this;
+            }
             if (this.pure) {
                 compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start);
                 this.pure.value = this.pure.value.replace(/[@#]__PURE__/g, ' ');
@@ -2441,8 +2531,8 @@ merge(Compressor.prototype, {
             return make_node(self.body.CTOR, self, {
                 value: make_node(AST_Conditional, self, {
                     condition   : self.condition,
-                    consequent  : self.body.value || make_node(AST_Undefined, self.body).optimize(compressor),
-                    alternative : self.alternative.value || make_node(AST_Undefined, self.alternative).optimize(compressor)
+                    consequent  : self.body.value || make_node(AST_Undefined, self.body),
+                    alternative : self.alternative.value || make_node(AST_Undefined, self.alternative)
                 })
             }).transform(compressor);
         }
@@ -2623,12 +2713,13 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_Call, function(self, compressor){
+        var exp = self.expression;
         if (compressor.option("unused")
-            && self.expression instanceof AST_Function
-            && !self.expression.uses_arguments
-            && !self.expression.uses_eval
-            && self.args.length > self.expression.argnames.length) {
-            var end = self.expression.argnames.length;
+            && exp instanceof AST_Function
+            && !exp.uses_arguments
+            && !exp.uses_eval
+            && self.args.length > exp.argnames.length) {
+            var end = exp.argnames.length;
             for (var i = end, len = self.args.length; i < len; i++) {
                 var node = self.args[i].drop_side_effect_free(compressor);
                 if (node) {
@@ -2638,7 +2729,6 @@ merge(Compressor.prototype, {
             self.args.length = end;
         }
         if (compressor.option("unsafe")) {
-            var exp = self.expression;
             if (exp instanceof AST_SymbolRef && exp.undeclared()) {
                 switch (exp.name) {
                   case "Array":
@@ -2817,17 +2907,24 @@ merge(Compressor.prototype, {
                 return best_of(self, node);
             }
         }
-        if (compressor.option("side_effects")) {
-            if (self.expression instanceof AST_Function
-                && !self.expression.is_generator
-                && self.args.length == 0
-                && !AST_Block.prototype.has_side_effects.call(self.expression, compressor)) {
-                return make_node(AST_Undefined, self).transform(compressor);
+        if (exp instanceof AST_Function && !self.expression.is_generator) {
+            if (exp.body[0] instanceof AST_Return) {
+                var value = exp.body[0].value;
+                if (!value || value.is_constant()) {
+                    var args = self.args.concat(value || make_node(AST_Undefined, self));
+                    return AST_Seq.from_array(args).transform(compressor);
+                }
+            }
+            if (compressor.option("side_effects")) {
+                if (!AST_Block.prototype.has_side_effects.call(exp, compressor)) {
+                    var args = self.args.concat(make_node(AST_Undefined, self));
+                    return AST_Seq.from_array(args).transform(compressor);
+                }
             }
         }
         if (compressor.option("drop_console")) {
-            if (self.expression instanceof AST_PropAccess) {
-                var name = self.expression.expression;
+            if (exp instanceof AST_PropAccess) {
+                var name = exp.expression;
                 while (name.expression) {
                     name = name.expression;
                 }
@@ -2838,12 +2935,6 @@ merge(Compressor.prototype, {
                 }
             }
         }
-        if (self.args.length == 0
-            && self.expression instanceof AST_Function
-            && self.expression.body[0] instanceof AST_Return
-            && self.expression.body[0].value.is_constant()) {
-            return self.expression.body[0].value;
-        }
         if (compressor.option("negate_iife")
             && compressor.parent() instanceof AST_SimpleStatement
             && is_iife_call(self)) {
@@ -2875,23 +2966,41 @@ merge(Compressor.prototype, {
         self.car = self.car.drop_side_effect_free(compressor, first_in_statement(compressor));
         if (!self.car) return maintain_this_binding(compressor.parent(), self, self.cdr);
         if (compressor.option("cascade")) {
+            var left;
             if (self.car instanceof AST_Assign
                 && !self.car.left.has_side_effects(compressor)) {
-                if (self.car.left.equivalent_to(self.cdr)) {
-                    return self.car;
-                }
-                if (self.cdr instanceof AST_Call
-                    && self.cdr.expression.equivalent_to(self.car.left)) {
-                    self.cdr.expression = self.car;
-                    return self.cdr;
+                left = self.car.left;
+            } else if (self.car instanceof AST_Unary
+                && (self.car.operator == "++" || self.car.operator == "--")) {
+                left = self.car.expression;
+            }
+            if (left) {
+                var parent, field;
+                var cdr = self.cdr;
+                while (true) {
+                    if (cdr.equivalent_to(left)) {
+                        var car = self.car instanceof AST_UnaryPostfix ? make_node(AST_UnaryPrefix, self.car, {
+                            operator: self.car.operator,
+                            expression: left
+                        }) : self.car;
+                        if (parent) {
+                            parent[field] = car;
+                            return self.cdr;
+                        }
+                        return car;
+                    }
+                    if (cdr instanceof AST_Binary && !(cdr instanceof AST_Assign)) {
+                        field = cdr.left.is_constant() ? "right" : "left";
+                    } else if (cdr instanceof AST_Call
+                        || cdr instanceof AST_Unary && cdr.operator != "++" && cdr.operator != "--") {
+                        field = "expression";
+                    } else break;
+                    parent = cdr;
+                    cdr = cdr[field];
                 }
             }
-            if (!self.car.has_side_effects(compressor)
-                && self.car.equivalent_to(self.cdr)) {
-                return self.car;
-            }
         }
-        if (self.cdr instanceof AST_Undefined) {
+        if (is_undefined(self.cdr)) {
             return make_node(AST_UnaryPrefix, self, {
                 operator   : "void",
                 expression : self.car
@@ -2930,7 +3039,7 @@ merge(Compressor.prototype, {
                 self.expression = e;
                 return self;
             } else {
-                return make_node(AST_Undefined, self);
+                return make_node(AST_Undefined, self).transform(compressor);
             }
         }
         if (compressor.option("booleans") && compressor.in_boolean_context()) {
@@ -3003,8 +3112,14 @@ merge(Compressor.prototype, {
                 right: rhs[0]
             }).optimize(compressor);
         }
-        function reverse(op, force) {
-            if (force || !(self.left.has_side_effects(compressor) || self.right.has_side_effects(compressor))) {
+        function reversible() {
+            return self.left instanceof AST_Constant
+                || self.right instanceof AST_Constant
+                || !self.left.has_side_effects(compressor)
+                    && !self.right.has_side_effects(compressor);
+        }
+        function reverse(op) {
+            if (reversible()) {
                 if (op) self.operator = op;
                 var tmp = self.left;
                 self.left = self.right;
@@ -3020,7 +3135,7 @@ merge(Compressor.prototype, {
 
                 if (!(self.left instanceof AST_Binary
                       && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
-                    reverse(null, true);
+                    reverse();
                 }
             }
             if (/^[!=]==?$/.test(self.operator)) {
@@ -3055,6 +3170,7 @@ merge(Compressor.prototype, {
           case "===":
           case "!==":
             if ((self.left.is_string(compressor) && self.right.is_string(compressor)) ||
+                (self.left.is_number(compressor) && self.right.is_number(compressor)) ||
                 (self.left.is_boolean() && self.right.is_boolean())) {
                 self.operator = self.operator.substr(0, 2);
             }
@@ -3192,7 +3308,10 @@ merge(Compressor.prototype, {
                 }
                 break;
             }
-            if (self.operator == "+") {
+            var associative = true;
+            switch (self.operator) {
+              case "+":
+                // "foo" + ("bar" + x) => "foobar" + x
                 if (self.left instanceof AST_Constant
                     && self.right instanceof AST_Binary
                     && self.right.operator == "+"
@@ -3200,7 +3319,7 @@ merge(Compressor.prototype, {
                     && self.right.is_string(compressor)) {
                     self = make_node(AST_Binary, self, {
                         operator: "+",
-                        left: make_node(AST_String, null, {
+                        left: make_node(AST_String, self.left, {
                             value: "" + self.left.getValue() + self.right.left.getValue(),
                             start: self.left.start,
                             end: self.right.left.end
@@ -3208,6 +3327,7 @@ merge(Compressor.prototype, {
                         right: self.right.right
                     });
                 }
+                // (x + "foo") + "bar" => x + "foobar"
                 if (self.right instanceof AST_Constant
                     && self.left instanceof AST_Binary
                     && self.left.operator == "+"
@@ -3216,13 +3336,14 @@ merge(Compressor.prototype, {
                     self = make_node(AST_Binary, self, {
                         operator: "+",
                         left: self.left.left,
-                        right: make_node(AST_String, null, {
+                        right: make_node(AST_String, self.right, {
                             value: "" + self.left.right.getValue() + self.right.getValue(),
                             start: self.left.right.start,
                             end: self.right.end
                         })
                     });
                 }
+                // (x + "foo") + ("bar" + y) => (x + "foobar") + y
                 if (self.left instanceof AST_Binary
                     && self.left.operator == "+"
                     && self.left.is_string(compressor)
@@ -3236,7 +3357,7 @@ merge(Compressor.prototype, {
                         left: make_node(AST_Binary, self.left, {
                             operator: "+",
                             left: self.left.left,
-                            right: make_node(AST_String, null, {
+                            right: make_node(AST_String, self.left.right, {
                                 value: "" + self.left.right.getValue() + self.right.left.getValue(),
                                 start: self.left.right.start,
                                 end: self.right.left.end
@@ -3245,6 +3366,122 @@ merge(Compressor.prototype, {
                         right: self.right.right
                     });
                 }
+                // a + -b => a - b
+                if (self.right instanceof AST_UnaryPrefix
+                    && self.right.operator == "-"
+                    && self.left.is_number(compressor)) {
+                    self = make_node(AST_Binary, self, {
+                        operator: "-",
+                        left: self.left,
+                        right: self.right.expression
+                    });
+                }
+                // -a + b => b - a
+                if (self.left instanceof AST_UnaryPrefix
+                    && self.left.operator == "-"
+                    && reversible()
+                    && self.right.is_number(compressor)) {
+                    self = make_node(AST_Binary, self, {
+                        operator: "-",
+                        left: self.right,
+                        right: self.left.expression
+                    });
+                }
+              case "*":
+                associative = compressor.option("unsafe_math");
+              case "&":
+              case "|":
+              case "^":
+                // a + +b => +b + a
+                if (self.left.is_number(compressor)
+                    && self.right.is_number(compressor)
+                    && reversible()
+                    && !(self.left instanceof AST_Binary
+                        && self.left.operator != self.operator
+                        && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
+                    var reversed = make_node(AST_Binary, self, {
+                        operator: self.operator,
+                        left: self.right,
+                        right: self.left
+                    });
+                    if (self.right instanceof AST_Constant
+                        && !(self.left instanceof AST_Constant)) {
+                        self = best_of(reversed, self);
+                    } else {
+                        self = best_of(self, reversed);
+                    }
+                }
+                if (associative && self.is_number(compressor)) {
+                    // a + (b + c) => (a + b) + c
+                    if (self.right instanceof AST_Binary
+                        && self.right.operator == self.operator) {
+                        self = make_node(AST_Binary, self, {
+                            operator: self.operator,
+                            left: make_node(AST_Binary, self.left, {
+                                operator: self.operator,
+                                left: self.left,
+                                right: self.right.left,
+                                start: self.left.start,
+                                end: self.right.left.end
+                            }),
+                            right: self.right.right
+                        });
+                    }
+                    // (n + 2) + 3 => 5 + n
+                    // (2 * n) * 3 => 6 + n
+                    if (self.right instanceof AST_Constant
+                        && self.left instanceof AST_Binary
+                        && self.left.operator == self.operator) {
+                        if (self.left.left instanceof AST_Constant) {
+                            self = make_node(AST_Binary, self, {
+                                operator: self.operator,
+                                left: make_node(AST_Binary, self.left, {
+                                    operator: self.operator,
+                                    left: self.left.left,
+                                    right: self.right,
+                                    start: self.left.left.start,
+                                    end: self.right.end
+                                }),
+                                right: self.left.right
+                            });
+                        } else if (self.left.right instanceof AST_Constant) {
+                            self = make_node(AST_Binary, self, {
+                                operator: self.operator,
+                                left: make_node(AST_Binary, self.left, {
+                                    operator: self.operator,
+                                    left: self.left.right,
+                                    right: self.right,
+                                    start: self.left.right.start,
+                                    end: self.right.end
+                                }),
+                                right: self.left.left
+                            });
+                        }
+                    }
+                    // (a | 1) | (2 | d) => (3 | a) | b
+                    if (self.left instanceof AST_Binary
+                        && self.left.operator == self.operator
+                        && self.left.right instanceof AST_Constant
+                        && self.right instanceof AST_Binary
+                        && self.right.operator == self.operator
+                        && self.right.left instanceof AST_Constant) {
+                        self = make_node(AST_Binary, self, {
+                            operator: self.operator,
+                            left: make_node(AST_Binary, self.left, {
+                                operator: self.operator,
+                                left: make_node(AST_Binary, self.left.left, {
+                                    operator: self.operator,
+                                    left: self.left.right,
+                                    right: self.right.left,
+                                    start: self.left.right.start,
+                                    end: self.right.left.end
+                                }),
+                                right: self.left.left
+                            }),
+                            right: self.right.right
+                        });
+                    }
+                }
             }
         }
         // x && (y && z)  ==>  x && y && z
@@ -3277,11 +3514,13 @@ merge(Compressor.prototype, {
             return def;
         }
         // testing against !self.scope.uses_with first is an optimization
-        if (self.undeclared() && !isLHS(self, compressor.parent())
+        if (compressor.option("screw_ie8")
+            && self.undeclared()
+            && !isLHS(self, compressor.parent())
             && (!self.scope.uses_with || !compressor.find_parent(AST_With))) {
             switch (self.name) {
               case "undefined":
-                return make_node(AST_Undefined, self);
+                return make_node(AST_Undefined, self).transform(compressor);
               case "NaN":
                 return make_node(AST_NaN, self).transform(compressor);
               case "Infinity":
@@ -3324,11 +3563,13 @@ merge(Compressor.prototype, {
             var scope = compressor.find_parent(AST_Scope);
             var undef = scope.find_variable("undefined");
             if (undef) {
-                return make_node(AST_SymbolRef, self, {
+                var ref = make_node(AST_SymbolRef, self, {
                     name   : "undefined",
                     scope  : scope,
                     thedef : undef
                 });
+                ref.is_undefined = true;
+                return ref;
             }
         }
         return self;
@@ -3631,7 +3872,7 @@ merge(Compressor.prototype, {
     OPT(AST_RegExp, literals_in_boolean_context);
 
     OPT(AST_Return, function(self, compressor){
-        if (self.value instanceof AST_Undefined) {
+        if (self.value && is_undefined(self.value)) {
             self.value = null;
         }
         return self;
diff --git a/lib/output.js b/lib/output.js
index 1e0ff175149..cb2b62bba3f 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -46,17 +46,8 @@
 var EXPECT_DIRECTIVE = /^$|[;{][\s\n]*$/;
 
 function is_some_comments(comment) {
-    var text = comment.value;
-    var type = comment.type;
-    if (type == "comment2") {
-        // multiline comment
-        return /@preserve|@license|@cc_on/i.test(text);
-    }
-    return type == "comment5";
-}
-
-function is_comment5(comment) {
-    return comment.type == "comment5";
+    // multiline comment
+    return comment.type == "comment2" && /@preserve|@license|@cc_on/i.test(comment.value);
 }
 
 function OutputStream(options) {
@@ -95,7 +86,7 @@ function OutputStream(options) {
         options.shorthand = options.ecma > 5;
 
     // Convert comment option to RegExp if neccessary and set up comments filter
-    var comment_filter = options.shebang ? is_comment5 : return_false; // Default case, throw all comments away except shebangs
+    var comment_filter = return_false; // Default case, throw all comments away
     if (options.comments) {
         var comments = options.comments;
         if (typeof options.comments === "string" && /^\/.*\/[a-zA-Z]*$/.test(options.comments)) {
@@ -107,12 +98,12 @@ function OutputStream(options) {
         }
         if (comments instanceof RegExp) {
             comment_filter = function(comment) {
-                return comment.type == "comment5" || comments.test(comment.value);
+                return comment.type != "comment5" && comments.test(comment.value);
             };
         }
         else if (typeof comments === "function") {
             comment_filter = function(comment) {
-                return comment.type == "comment5" || comments(this, comment);
+                return comment.type != "comment5" && comments(this, comment);
             };
         }
         else if (comments === "some") {
@@ -444,10 +435,6 @@ function OutputStream(options) {
         return OUTPUT;
     };
 
-    if (options.preamble) {
-        print(options.preamble.replace(/\r\n?|[\n\u2028\u2029]|\s*$/g, "\n"));
-    }
-
     var stack = [];
     return {
         get             : get,
@@ -572,6 +559,17 @@ function OutputStream(options) {
                 }));
             }
 
+            if (comments.length > 0 && output.pos() == 0) {
+                if (output.option("shebang") && comments[0].type == "comment5") {
+                    output.print("#!" + comments.shift().value + "\n");
+                    output.indent();
+                }
+                var preamble = output.option("preamble");
+                if (preamble) {
+                    output.print(preamble.replace(/\r\n?|[\n\u2028\u2029]|\s*$/g, "\n"));
+                }
+            }
+
             comments = comments.filter(output.comment_filter, self);
 
             // Keep single line comments after nlb, after nlb
@@ -596,10 +594,6 @@ function OutputStream(options) {
                         output.space();
                     }
                 }
-                else if (output.pos() === 0 && c.type == "comment5" && output.option("shebang")) {
-                    output.print("#!" + c.value + "\n");
-                    output.indent();
-                }
             });
         }
     });
diff --git a/lib/parse.js b/lib/parse.js
index 2164e52a98b..4e671da451a 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -700,6 +700,11 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
     function next_token(force_regexp) {
         if (force_regexp != null)
             return read_regexp(force_regexp);
+        if (shebang && S.pos == 0 && looking_at("#!")) {
+            start_token();
+            forward(2);
+            skip_line_comment("comment5");
+        }
         for (;;) {
             skip_whitespace();
             start_token();
@@ -742,13 +747,6 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             if (PUNC_CHARS(ch)) return token("punc", next());
             if (OPERATOR_CHARS(ch)) return read_operator();
             if (code == 92 || is_identifier_start(ch)) return read_word();
-            if (shebang) {
-                if (S.pos == 0 && looking_at("#!")) {
-                    forward(2);
-                    skip_line_comment("comment5");
-                    continue;
-                }
-            }
             break;
         }
         parse_error("Unexpected character '" + ch + "'");
diff --git a/lib/scope.js b/lib/scope.js
index 42afe87cabb..2edea20e739 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -209,14 +209,13 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             (node.scope = defun.parent_scope).def_function(node, in_export, in_block);
         }
         else if (node instanceof AST_SymbolVar
-                 || node instanceof AST_SymbolConst
-                 || node instanceof AST_SymbolLet) {
+            || node instanceof AST_SymbolLet
+            || node instanceof AST_SymbolConst) {
             var def = ((node instanceof AST_SymbolBlockDeclaration) ? scope : defun).def_variable(node, in_export, in_block);
             def.destructuring = in_destructuring;
-            def.init = tw.parent().value;
         }
         else if (node instanceof AST_SymbolCatch) {
-            (options.screw_ie8 ? scope : defun).def_variable(node, in_export, in_block);
+            scope.def_variable(node, in_export, in_block);
         }
         else if (node instanceof AST_LabelRef) {
             var sym = labels.get(node.name);
@@ -274,6 +273,23 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
     });
     self.walk(tw);
 
+    // pass 3: fix up any scoping issue with IE8
+    if (!options.screw_ie8) {
+        self.walk(new TreeWalker(function(node, descend) {
+            if (node instanceof AST_SymbolCatch) {
+                var name = node.name;
+                var scope = node.thedef.scope.parent_scope;
+                var def = scope.find_variable(name) || self.globals.get(name) || scope.def_variable(node);
+                node.thedef.references.forEach(function(ref) {
+                    ref.thedef = def;
+                    ref.reference(options);
+                });
+                node.thedef = def;
+                return true;
+            }
+        }));
+    }
+
     if (options.cache) {
         this.cname = options.cache.cname;
     }
diff --git a/package.json b/package.json
index f152a51e68a..31aaf9515d1 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "homepage": "http://lisperator.net/uglifyjs",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "2.8.5",
+  "version": "2.8.7",
   "engines": {
     "node": ">=0.8.0"
   },
@@ -29,7 +29,6 @@
     "LICENSE"
   ],
   "dependencies": {
-    "async": "~0.2.6",
     "source-map": "~0.5.1",
     "uglify-to-browserify": "~1.0.0",
     "yargs": "~3.10.0"
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index c8fa046051b..6d9961ff463 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -1343,3 +1343,81 @@ issue_1537_for_of: {
         for (k of {prop: 'val'});
     }
 }
+
+issue_1537_destructuring_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var x = 1, y = 2;
+        [x] = [y];
+    }
+    expect: {
+        var x = 1;
+        [x] = [2];
+    }
+}
+
+issue_1537_destructuring_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var x = foo();
+        [x] = [1];
+    }
+    expect: {
+        var x = foo();
+        [x] = [1];
+    }
+}
+
+issue_1537_destructuring_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var x = Math.random();
+        ({p: x = 9} = {v: 1});
+    }
+    expect: {
+        var x = Math.random();
+        ({p: x = 9} = {v: 1});
+    }
+}
+
+issue_1537_destructuring_for_in: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var x = 1, y = 2;
+        (function() {
+            for ([[x], y] in a);
+        })();
+    }
+    expect: {
+        var x = 1, y = 2;
+        (function() {
+            for ([[x], y] in a);
+        })();
+    }
+}
+
+issue_1537_destructuring_for_of: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var x = 1, y = 2;
+        (function() {
+            for ([[x], y] of a);
+        })();
+    }
+    expect: {
+        var x = 1, y = 2;
+        (function() {
+            for ([[x], y] of a);
+        })();
+    }
+}
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index d8dd0ea4e7d..fd1c2fb3368 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -713,7 +713,7 @@ iife: {
     }
     expect: {
         function f() {
-            ~function() {}(b);
+            b;
         }
     }
 }
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index ef0c4c78df4..5adbc9ea11b 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -734,9 +734,7 @@ call_args: {
     expect: {
         const a = 1;
         console.log(1);
-        +function(a) {
-            return 1;
-        }(1);
+        +(1, 1);
     }
 }
 
@@ -757,9 +755,7 @@ call_args_drop_param: {
     expect: {
         const a = 1;
         console.log(1);
-        +function() {
-            return 1;
-        }(b);
+        +(b, 1);
     }
 }
 
diff --git a/test/compress/functions.js b/test/compress/functions.js
index d3d99b57a18..a1a515a13d0 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -35,9 +35,9 @@ iifes_returning_constants_keep_fargs_true: {
         console.log("okay");
         console.log(123);
         console.log(void 0);
-        console.log(function(x,y,z){return 2}(1,2,3));
-        console.log(function(x,y){return 6}(2,3));
-        console.log(function(x, y){return 6}(2,3,a(),b()));
+        console.log(2);
+        console.log(6);
+        console.log((a(), b(), 6));
     }
 }
 
@@ -71,6 +71,23 @@ iifes_returning_constants_keep_fargs_false: {
         console.log(void 0);
         console.log(2);
         console.log(6);
-        console.log(function(){return 6}(a(),b()));
+        console.log((a(), b(), 6));
+    }
+}
+
+issue_485_crashing_1530: {
+    options = {
+        conditionals: true,
+        dead_code: true,
+        evaluate: true,
+    }
+    input: {
+        (function(a) {
+            if (true) return;
+            var b = 42;
+        })(this);
+    }
+    expect: {
+        this, void 0;
     }
 }
diff --git a/test/compress/issue-1443.js b/test/compress/issue-1443.js
index a2565872d0c..304a71ac0ce 100644
--- a/test/compress/issue-1443.js
+++ b/test/compress/issue-1443.js
@@ -2,6 +2,7 @@
 
 unsafe_undefined: {
     options = {
+        conditionals: true,
         if_return: true,
         unsafe: true
     }
@@ -19,12 +20,7 @@ unsafe_undefined: {
     expect: {
         function f(n) {
             return function() {
-                if (a)
-                    return b;
-                if (c)
-                    return d;
-                else
-                    return n;
+                return a ? b : c ? d : n;
             };
         }
     }
@@ -32,6 +28,7 @@ unsafe_undefined: {
 
 keep_fnames: {
     options = {
+        conditionals: true,
         if_return: true,
         unsafe: true
     }
@@ -57,12 +54,7 @@ keep_fnames: {
                 function n(n) {
                     return n * n;
                 }
-                if (a)
-                    return b;
-                if (c)
-                    return d;
-                else
-                    return r;
+                return a ? b : c ? d : r;
             };
         }
     }
diff --git a/test/compress/issue-368.js b/test/compress/issue-368.js
new file mode 100644
index 00000000000..5960aa64ab4
--- /dev/null
+++ b/test/compress/issue-368.js
@@ -0,0 +1,55 @@
+collapse: {
+    options = {
+        cascade: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f1() {
+            var a;
+            a = typeof b === 'function' ? b() : b;
+            return a !== undefined && c();
+        }
+        function f2(b) {
+            var a;
+            b = c();
+            a = typeof b === 'function' ? b() : b;
+            return 'stirng' == typeof a && d();
+        }
+        function f3(c) {
+            var a;
+            a = b(a / 2);
+            if (a < 0) {
+                a++;
+                ++c;
+                return c / 2;
+            }
+        }
+        function f4(c) {
+            var a;
+            a = b(a / 2);
+            if (a < 0) {
+                a++;
+                c++;
+                return c / 2;
+            }
+        }
+    }
+    expect: {
+        function f1() {
+            return void 0 !== ('function' === typeof b ? b() : b) && c();
+        }
+        function f2(b) {
+            return b = c(), 'stirng' == typeof ('function' === typeof b ? b() : b) && d();
+        }
+        function f3(c) {
+            var a;
+            if ((a = b(a / 2)) < 0) return a++, ++c / 2;
+        }
+        function f4(c) {
+            var a;
+            if ((a = b(a / 2)) < 0) return a++, ++c / 2;
+        }
+    }
+}
diff --git a/test/compress/issue-640.js b/test/compress/issue-640.js
new file mode 100644
index 00000000000..dd3f3f2196a
--- /dev/null
+++ b/test/compress/issue-640.js
@@ -0,0 +1,317 @@
+cond_5: {
+    options = {
+        conditionals: true,
+        expression: true,
+    }
+    input: {
+        if (some_condition()) {
+            if (some_other_condition()) {
+                do_something();
+            } else {
+                alternate();
+            }
+        } else {
+            alternate();
+        }
+
+        if (some_condition()) {
+            if (some_other_condition()) {
+                do_something();
+            }
+        }
+    }
+    expect: {
+        some_condition() && some_other_condition() ? do_something() : alternate();
+        if (some_condition() && some_other_condition()) do_something();
+    }
+}
+
+dead_code_const_annotation_regex: {
+    options = {
+        booleans     : true,
+        conditionals : true,
+        dead_code    : true,
+        evaluate     : true,
+        expression   : true,
+        loops        : true,
+    }
+    input: {
+        var unused;
+        // @constraint this shouldn't be a constant
+        var CONST_FOO_ANN = false;
+        if (CONST_FOO_ANN) {
+            console.log("reachable");
+        }
+    }
+    expect: {
+        var unused;
+        var CONST_FOO_ANN = !1;
+        if (CONST_FOO_ANN) console.log('reachable');
+    }
+}
+
+drop_console_2: {
+    options = {
+        drop_console: true,
+        expression: true,
+    }
+    input: {
+        console.log('foo');
+        console.log.apply(console, arguments);
+    }
+    expect: {
+        // with regular compression these will be stripped out as well
+        void 0;
+        void 0;
+    }
+}
+
+drop_value: {
+    options = {
+        expression: true,
+        side_effects: true,
+    }
+    input: {
+        (1, [2, foo()], 3, {a:1, b:bar()});
+    }
+    expect: {
+        foo(), {a:1, b:bar()};
+    }
+}
+
+wrongly_optimized: {
+    options = {
+        conditionals: true,
+        booleans: true,
+        evaluate: true,
+        expression: true,
+    }
+    input: {
+        function func() {
+            foo();
+        }
+        if (func() || true) {
+            bar();
+        }
+    }
+    expect: {
+        function func() {
+            foo();
+        }
+        // TODO: optimize to `func(), bar()`
+        if (func(), !0) bar();
+    }
+}
+
+negate_iife_1: {
+    options = {
+        expression: true,
+        negate_iife: true,
+    }
+    input: {
+        (function(){ stuff() })();
+    }
+    expect: {
+        (function(){ stuff() })();
+    }
+}
+
+negate_iife_3: {
+    options = {
+        conditionals: true,
+        expression: true,
+        negate_iife: true,
+    }
+    input: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+    }
+    expect: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+    }
+}
+
+negate_iife_3_off: {
+    options = {
+        conditionals: true,
+        expression: true,
+        negate_iife: false,
+    }
+    input: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+    }
+    expect: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+    }
+}
+
+negate_iife_4: {
+    options = {
+        conditionals: true,
+        expression: true,
+        negate_iife: true,
+        sequences: true,
+    }
+    input: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+        (function(){
+            console.log("something");
+        })();
+    }
+    expect: {
+        (function(){ return t })() ? console.log(true) : console.log(false), function(){
+            console.log("something");
+        }();
+    }
+}
+
+negate_iife_5: {
+    options = {
+        conditionals: true,
+        expression: true,
+        negate_iife: true,
+        sequences: true,
+    }
+    input: {
+        if ((function(){ return t })()) {
+            foo(true);
+        } else {
+            bar(false);
+        }
+        (function(){
+            console.log("something");
+        })();
+    }
+    expect: {
+        (function(){ return t })() ? foo(true) : bar(false), function(){
+            console.log("something");
+        }();
+    }
+}
+
+negate_iife_5_off: {
+    options = {
+        conditionals: true,
+        expression: true,
+        negate_iife: false,
+        sequences: true,
+    };
+    input: {
+        if ((function(){ return t })()) {
+            foo(true);
+        } else {
+            bar(false);
+        }
+        (function(){
+            console.log("something");
+        })();
+    }
+    expect: {
+        (function(){ return t })() ? foo(true) : bar(false), function(){
+            console.log("something");
+        }();
+    }
+}
+
+issue_1254_negate_iife_true: {
+    options = {
+        expression: true,
+        negate_iife: true,
+    }
+    input: {
+        (function() {
+            return function() {
+                console.log('test')
+            };
+        })()();
+    }
+    expect_exact: '(function(){return function(){console.log("test")}})()();'
+}
+
+issue_1254_negate_iife_nested: {
+    options = {
+        expression: true,
+        negate_iife: true,
+    }
+    input: {
+        (function() {
+            return function() {
+                console.log('test')
+            };
+        })()()()()();
+    }
+    expect_exact: '(function(){return function(){console.log("test")}})()()()()();'
+}
+
+conditional: {
+    options = {
+        expression: true,
+        pure_funcs: [ "pure" ],
+        side_effects: true,
+    }
+    input: {
+        pure(1 | a() ? 2 & b() : 7 ^ c());
+        pure(1 | a() ? 2 & b() : 5);
+        pure(1 | a() ? 4 : 7 ^ c());
+        pure(1 | a() ? 4 : 5);
+        pure(3 ? 2 & b() : 7 ^ c());
+        pure(3 ? 2 & b() : 5);
+        pure(3 ? 4 : 7 ^ c());
+        pure(3 ? 4 : 5);
+    }
+    expect: {
+        1 | a() ? b() : c();
+        1 | a() && b();
+        1 | a() || c();
+        a();
+        3 ? b() : c();
+        3 && b();
+        3 || c();
+        pure(3 ? 4 : 5);
+    }
+}
+
+limit_1: {
+    options = {
+        expression: true,
+        sequences: 3,
+    }
+    input: {
+        a;
+        b;
+        c;
+        d;
+        e;
+        f;
+        g;
+        h;
+        i;
+        j;
+        k;
+    }
+    expect: {
+        // Turned into a single return statement
+        // so it can no longer be split into lines
+        a,b,c,d,e,f,g,h,i,j,k;
+    }
+}
+
+iife: {
+    options = {
+        expression: true,
+        sequences: true,
+    }
+    input: {
+        x = 42;
+        (function a() {})();
+        !function b() {}();
+        ~function c() {}();
+        +function d() {}();
+        -function e() {}();
+        void function f() {}();
+        typeof function g() {}();
+    }
+    expect: {
+        x = 42, function a() {}(), function b() {}(), function c() {}(),
+        function d() {}(), function e() {}(), function f() {}(), typeof function g() {}();
+    }
+}
diff --git a/test/compress/negate-iife.js b/test/compress/negate-iife.js
index f17ae206ce9..9a0b5a46867 100644
--- a/test/compress/negate-iife.js
+++ b/test/compress/negate-iife.js
@@ -32,6 +32,19 @@ negate_iife_2: {
     }
 }
 
+negate_iife_2_side_effects: {
+    options = {
+        negate_iife: true,
+        side_effects: true,
+    }
+    input: {
+        (function(){ return {} })().x = 10; // should not transform this one
+    }
+    expect: {
+        (function(){ return {} })().x = 10;
+    }
+}
+
 negate_iife_3: {
     options = {
         negate_iife: true,
@@ -45,6 +58,34 @@ negate_iife_3: {
     }
 }
 
+negate_iife_3_evaluate: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        negate_iife: true,
+    }
+    input: {
+        (function(){ return true })() ? console.log(true) : console.log(false);
+    }
+    expect: {
+        console.log(true);
+    }
+}
+
+negate_iife_3_side_effects: {
+    options = {
+        conditionals: true,
+        negate_iife: true,
+        side_effects: true,
+    }
+    input: {
+        (function(){ return t })() ? console.log(true) : console.log(false);
+    }
+    expect: {
+        !function(){ return t }() ? console.log(false) : console.log(true);
+    }
+}
+
 negate_iife_3_off: {
     options = {
         negate_iife: false,
@@ -58,6 +99,20 @@ negate_iife_3_off: {
     }
 }
 
+negate_iife_3_off_evaluate: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        negate_iife: false,
+    }
+    input: {
+        (function(){ return true })() ? console.log(true) : console.log(false);
+    }
+    expect: {
+        console.log(true);
+    }
+}
+
 negate_iife_4: {
     options = {
         negate_iife: true,
@@ -320,3 +375,35 @@ issue_1288: {
         }(0);
     }
 }
+
+issue_1288_side_effects: {
+    options = {
+        conditionals: true,
+        negate_iife: true,
+        side_effects: true,
+    }
+    input: {
+        if (w) ;
+        else {
+            (function f() {})();
+        }
+        if (!x) {
+            (function() {
+                x = {};
+            })();
+        }
+        if (y)
+            (function() {})();
+        else
+            (function(z) {
+                return z;
+            })(0);
+    }
+    expect: {
+        w;
+        x || function() {
+            x = {};
+        }();
+        y;
+    }
+}
diff --git a/test/compress/numbers.js b/test/compress/numbers.js
index 8e32ad02a75..0b40bb9c88d 100644
--- a/test/compress/numbers.js
+++ b/test/compress/numbers.js
@@ -17,3 +17,139 @@ hex_numbers_in_parentheses_for_prototype_functions: {
     }
     expect_exact: "-2;(-2).toFixed(0);2;2..toFixed(0);.2;.2.toFixed(0);2e-8;2e-8.toFixed(0);0xde0b6b3a7640080;(0xde0b6b3a7640080).toFixed(0);"
 }
+
+comparisons: {
+    options = {
+        comparisons: true,
+    }
+    input: {
+        console.log(
+            ~x === 42,
+            x % n === 42
+        );
+    }
+    expect: {
+        console.log(
+            42 == ~x,
+            x % n == 42
+        );
+    }
+}
+
+evaluate_1: {
+    options = {
+        evaluate: true,
+        unsafe_math: false,
+    }
+    input: {
+        console.log(
+            x + 1 + 2,
+            x * 1 * 2,
+            +x + 1 + 2,
+            1 + x + 2 + 3,
+            1 | x | 2 | 3,
+            1 + x-- + 2 + 3,
+            1 + (x*y + 2) + 3,
+            1 + (2 + x + 3),
+            1 + (2 + ~x + 3),
+            -y + (2 + ~x + 3),
+            1 & (2 & x & 3),
+            1 + (2 + (x |= 0) + 3)
+        );
+    }
+    expect: {
+        console.log(
+            x + 1 + 2,
+            1 * x * 2,
+            +x + 1 + 2,
+            1 + x + 2 + 3,
+            3 | x,
+            1 + x-- + 2 + 3,
+            x*y + 2 + 1 + 3,
+            1 + (2 + x + 3),
+            2 + ~x + 3 + 1,
+            -y + (2 + ~x + 3),
+            0 & x,
+            2 + (x |= 0) + 3 + 1
+        );
+    }
+}
+
+evaluate_2: {
+    options = {
+        evaluate: true,
+        unsafe_math: true,
+    }
+    input: {
+        console.log(
+            x + 1 + 2,
+            x * 1 * 2,
+            +x + 1 + 2,
+            1 + x + 2 + 3,
+            1 | x | 2 | 3,
+            1 + x-- + 2 + 3,
+            1 + (x*y + 2) + 3,
+            1 + (2 + x + 3),
+            1 & (2 & x & 3),
+            1 + (2 + (x |= 0) + 3)
+        );
+    }
+    expect: {
+        console.log(
+            x + 1 + 2,
+            2 * x,
+            3 + +x,
+            1 + x + 2 + 3,
+            3 | x,
+            6 + x--,
+            6 + x*y,
+            1 + (2 + x + 3),
+            0 & x,
+            6 + (x |= 0)
+        );
+    }
+}
+
+evaluate_3: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+        unsafe_math: true,
+    }
+    input: {
+        console.log(1 + Number(x) + 2);
+    }
+    expect: {
+        console.log(3 + +x);
+    }
+}
+
+evaluate_4: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        console.log(
+            1+ +a,
+            +a+1,
+            1+-a,
+            -a+1,
+            +a+ +b,
+            +a+-b,
+            -a+ +b,
+            -a+-b
+        );
+    }
+    expect: {
+        console.log(
+            +a+1,
+            +a+1,
+            1-a,
+            1-a,
+            +a+ +b,
+            +a-b,
+            -a+ +b,
+            -a-b
+        );
+    }
+}
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 557631bd19a..70e915d3283 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -605,6 +605,29 @@ inner_var_for_in_2: {
     }
 }
 
+inner_var_catch: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        try {
+            a();
+        } catch (e) {
+            var b = 1;
+        }
+        console.log(b);
+    }
+    expect: {
+        try {
+            a();
+        } catch (e) {
+            var b = 1;
+        }
+        console.log(b);
+    }
+}
+
 issue_1533_1: {
     options = {
         collapse_vars: true,
diff --git a/test/compress/screw-ie8.js b/test/compress/screw-ie8.js
index 31c448fd091..36eb4d3a1da 100644
--- a/test/compress/screw-ie8.js
+++ b/test/compress/screw-ie8.js
@@ -17,6 +17,26 @@ dont_screw: {
     expect_exact: 'f("\\x0B");';
 }
 
+do_screw_constants: {
+    options = {
+        screw_ie8: true,
+    }
+    input: {
+        f(undefined, Infinity);
+    }
+    expect_exact: "f(void 0,1/0);"
+}
+
+dont_screw_constants: {
+    options = {
+        screw_ie8: false,
+    }
+    input: {
+        f(undefined, Infinity);
+    }
+    expect_exact: "f(undefined,Infinity);"
+}
+
 do_screw_try_catch: {
     options = { screw_ie8: true };
     mangle = { screw_ie8: true };
@@ -46,8 +66,6 @@ do_screw_try_catch: {
 }
 
 dont_screw_try_catch: {
-    // This test is known to generate incorrect code for screw_ie8=false.
-    // Update expected result in the event this bug is ever fixed.
     options = { screw_ie8: false };
     mangle = { screw_ie8: false };
     beautify = { screw_ie8: false };
@@ -64,11 +82,11 @@ dont_screw_try_catch: {
     }
     expect: {
         bad = function(n){
-            return function(n){
+            return function(t){
                 try{
-                    t()
-                } catch(t) {
-                    n(t)
+                    n()
+                } catch(n) {
+                    t(n)
                 }
             }
         };
@@ -104,8 +122,6 @@ do_screw_try_catch_undefined: {
 }
 
 dont_screw_try_catch_undefined: {
-    // This test is known to generate incorrect code for screw_ie8=false.
-    // Update expected result in the event this bug is ever fixed.
     options = { screw_ie8: false };
     mangle = { screw_ie8: false };
     beautify = { screw_ie8: false };
@@ -121,14 +137,48 @@ dont_screw_try_catch_undefined: {
         };
     }
     expect: {
-        function a(o){
+        function a(n){
             try{
                 throw "Stuff"
-            } catch (n) {
-                console.log("caught: "+n)
+            } catch (undefined) {
+                console.log("caught: " + undefined)
+            }
+            console.log("undefined is " + undefined);
+            return n === undefined
+        }
+    }
+}
+
+reduce_vars: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        screw_ie8: false,
+        unused: true,
+    }
+    mangle = {
+        screw_ie8: false,
+    }
+    input: {
+        function f() {
+            var a;
+            try {
+                x();
+            } catch (a) {
+                y();
+            }
+            alert(a);
+        }
+    }
+    expect: {
+        function f() {
+            var t;
+            try {
+                x();
+            } catch (t) {
+                y();
             }
-            console.log("undefined is " + n);
-            return o === n
+            alert(t);
         }
     }
 }
diff --git a/test/compress/sequences.js b/test/compress/sequences.js
index d93f5237259..41cfc726159 100644
--- a/test/compress/sequences.js
+++ b/test/compress/sequences.js
@@ -248,6 +248,39 @@ iife: {
     }
     expect: {
         x = 42, function a() {}(), function b() {}(), function c() {}(),
-        function d() {}(), function e() {}(), function f() {}(), function g() {}()
+        function d() {}(), function e() {}(), function f() {}(), function g() {}();
+    }
+}
+
+unsafe_undefined: {
+    options = {
+        conditionals: true,
+        if_return: true,
+        sequences: true,
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        function f(undefined) {
+            if (a)
+                return b;
+            if (c)
+                return d;
+        }
+        function g(undefined) {
+            if (a)
+                return b;
+            if (c)
+                return d;
+            e();
+        }
+    }
+    expect: {
+        function f(undefined) {
+            return a ? b : c ? d : undefined;
+        }
+        function g(undefined) {
+            return a ? b : c ? d : void e();
+        }
     }
 }
diff --git a/test/mocha/comment-filter.js b/test/mocha/comment-filter.js
index 01580c87dbf..9474e73208b 100644
--- a/test/mocha/comment-filter.js
+++ b/test/mocha/comment-filter.js
@@ -72,4 +72,12 @@ describe("comment filters", function() {
         assert.strictEqual(UglifyJS.parse("/* ok */ function a(){}").print_to_string(options), "/* ok */function a(){}");
         assert.strictEqual(UglifyJS.parse("/* ok */ function a(){}").print_to_string(options), "/* ok */function a(){}");
     });
+
+    it("Should handle shebang and preamble correctly", function() {
+        var code = UglifyJS.minify("#!/usr/bin/node\nvar x = 10;", {
+            fromString: true,
+            output: { preamble: "/* Build */" }
+        }).code;
+        assert.strictEqual(code, "#!/usr/bin/node\n/* Build */\nvar x=10;");
+    })
 });