Add passes compress option. Fix duplicate compress warnings.

README.md

@@ -356,6 +356,9 @@ to set `true`; it's effectively a shortcut for `foo=true`).
   compressor from mangling/discarding function names.  Useful for code relying on
   `Function.prototype.name`.
 
+- `passes` -- default `1`. Number of times to run compress. Use an
+  integer argument larger than 1 to further reduce code size in some cases.
+  Note: raising the number of passes will increase uglify compress time.
 
 ### The `unsafe` option
 

bin/uglifyjs

@@ -423,7 +423,7 @@ async.eachLimit(files, 1, function (file, cb) {
 
     if (COMPRESS) {
         time_it("squeeze", function(){
-            TOPLEVEL = TOPLEVEL.transform(compressor);
+            TOPLEVEL = compressor.compress(TOPLEVEL);
         });
     }
 

lib/compress.js

@@ -75,18 +75,36 @@ function Compressor(options, false_by_default) {
         screw_ie8     : false,
         drop_console  : false,
         angular       : false,
-
         warnings      : true,
-        global_defs   : {}
+        global_defs   : {},
+        passes        : 1,
     }, true);
+    this.warnings_produced = {};
 };
 
 Compressor.prototype = new TreeTransformer;
 merge(Compressor.prototype, {
     option: function(key) { return this.options[key] },
-    warn: function() {
+    compress: function(node) {
-        if (this.options.warnings)
+        var passes = +this.options.passes || 1;
-            AST_Node.warn.apply(AST_Node, arguments);
+        for (var pass = 0; pass < passes && pass < 3; ++pass) {
+            if (pass > 0) node.clear_opt_flags();
+            node = node.transform(this);
+        }
+        return node;
+    },
+    warn: function(text, props) {
+        if (this.options.warnings) {
+            // only emit unique warnings
+            var message = string_template(text, props);
+            if (!(message in this.warnings_produced)) {
+                this.warnings_produced[message] = true;
+                AST_Node.warn.apply(AST_Node, arguments);
+            }
+        }
+    },
+    clear_warnings: function() {
+        this.warnings_produced = {};
     },
     before: function(node, descend, in_list) {
         if (node._squeezed) return node;
@@ -129,6 +147,15 @@ merge(Compressor.prototype, {
         return this.print_to_string() == node.print_to_string();
     });
 
+    AST_Node.DEFMETHOD("clear_opt_flags", function(){
+        this.walk(new TreeWalker(function(node){
+            if (!(node instanceof AST_Directive || node instanceof AST_Constant)) {
+                node._squeezed = false;
+                node._optimized = false;
+            }
+        }));
+    });
+
     function make_node(ctor, orig, props) {
         if (!props) props = {};
         if (orig) {
@@ -392,10 +419,7 @@ merge(Compressor.prototype, {
                     var_defs_removed = true;
                 }
                 // Further optimize statement after substitution.
-                stat.walk(new TreeWalker(function(node){
+                stat.clear_opt_flags();
-                    delete node._squeezed;
-                    delete node._optimized;
-                }));
 
                 compressor.warn("Replacing " + (is_constant ? "constant" : "variable") +
                     " " + var_name + " [{file}:{line},{col}]", node.start);

test/compress/issue-1034.js

@@ -39,7 +39,7 @@ non_hoisted_function_after_return_2a: {
         hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
         evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
         if_return: true, join_vars: true, cascade: true, side_effects: true,
-        collapse_vars: false
+        collapse_vars: false, passes: 2
     }
     input: {
         function foo(x) {
@@ -57,20 +57,11 @@ non_hoisted_function_after_return_2a: {
         }
     }
     expect: {
-        // NOTE: Output is correct, but suboptimal. Not a regression. Can be improved in future.
-        //       This output is run through non_hoisted_function_after_return_2b with same flags.
         function foo(x) {
-            if (x) {
+            return bar(x ? 1 : 2);
-                return bar(1);
-            } else {
-                return bar(2);
-                var b;
-            }
-            var c = bar(3);
             function bar(x) {
                 return 7 - x;
             }
-            return b || c;
         }
     }
     expect_warnings: [
@@ -79,7 +70,12 @@ non_hoisted_function_after_return_2a: {
         "WARN: Dropping unreachable code [test/compress/issue-1034.js:51,16]",
         "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:51,16]",
         "WARN: Dropping unused variable a [test/compress/issue-1034.js:48,20]",
-        "WARN: Dropping unused function nope [test/compress/issue-1034.js:55,21]"
+        "WARN: Dropping unused function nope [test/compress/issue-1034.js:55,21]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:53,12]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:53,12]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:56,12]",
+        "WARN: Dropping unused variable b [test/compress/issue-1034.js:51,20]",
+        "WARN: Dropping unused variable c [test/compress/issue-1034.js:53,16]"
     ]
 }
 
@@ -91,7 +87,6 @@ non_hoisted_function_after_return_2b: {
         collapse_vars: false
     }
     input: {
-        // Note: output of test non_hoisted_function_after_return_2a run through compress again
         function foo(x) {
             if (x) {
                 return bar(1);
@@ -107,31 +102,20 @@ non_hoisted_function_after_return_2b: {
         }
     }
     expect: {
-        // the output we would have liked to see from non_hoisted_function_after_return_2a
         function foo(x) {
             return bar(x ? 1 : 2);
             function bar(x) { return 7 - x; }
         }
     }
     expect_warnings: [
-        // Notice that some warnings are repeated by multiple compress passes.
+        // duplicate warnings no longer emitted
-        // Not a regression. There is room for improvement here.
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:95,16]",
-        // Warnings should be cached and only output if unique.
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:95,16]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:97,12]",
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:97,12]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:101,12]",
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unused variable b [test/compress/issue-1034.js:95,20]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unused variable c [test/compress/issue-1034.js:97,16]"
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:102,12]",
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:102,12]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:106,12]",
-        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
-        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
-        "WARN: Dropping unused variable b [test/compress/issue-1034.js:100,20]",
-        "WARN: Dropping unused variable c [test/compress/issue-1034.js:102,16]"
     ]
 }
 

test/mocha/minify.js

@@ -0,0 +1,11 @@
+var Uglify = require('../../');
+var assert = require("assert");
+
+describe("minify", function() {
+    it("Should test basic sanity of minify with default options", function() {
+        var js = 'function foo(bar) { if (bar) return 3; else return 7; var u = not_called(); }';
+        var result = Uglify.minify(js, {fromString: true});
+        assert.strictEqual(result.code, 'function foo(n){return n?3:7}');
+    });
+});
+

test/run-tests.js

@@ -110,7 +110,7 @@ function run_compress_tests() {
             if (test.mangle_props) {
                 input = U.mangle_properties(input, test.mangle_props);
             }
-            var output = input.transform(cmp);
+            var output = cmp.compress(input);
             output.figure_out_scope();
             if (test.mangle) {
                 output.compute_char_frequency(test.mangle);

tools/node.js

@@ -78,7 +78,7 @@ exports.minify = function(files, options) {
         UglifyJS.merge(compress, options.compress);
         toplevel.figure_out_scope();
         var sq = UglifyJS.Compressor(compress);
-        toplevel = toplevel.transform(sq);
+        toplevel = sq.compress(toplevel);
     }
 
     // 3. mangle properties