implement compress option reduce_funcs

- inline single-use function declarations as expressions when permissible
- depend on `reduce_vars`
- enabled by default
- disable for speed critical code

fixes #2464

README.md

@@ -689,6 +689,11 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
   Specify `"strict"` to treat `foo.bar` as side-effect-free only when
   `foo` is certain to not throw, i.e. not `null` or `undefined`.
 
+- `reduce_funcs` (default: `true`) -- Allows single-use functions
+  to be inlined as function expressions when permissible.
+  Enabled by default.  Option depends on `reduce_vars` being enabled.
+  For speed critical code this option should be disabled.
+
 - `reduce_vars` (default: `true`) -- Improve optimization on variables assigned with and
   used as constant values.
 

lib/compress.js

@@ -75,6 +75,7 @@ function Compressor(options, false_by_default) {
         properties    : !false_by_default,
         pure_getters  : !false_by_default && "strict",
         pure_funcs    : null,
+        reduce_funcs  : !false_by_default,
         reduce_vars   : !false_by_default,
         sequences     : !false_by_default,
         side_effects  : !false_by_default,
@@ -4255,6 +4256,7 @@ merge(Compressor.prototype, {
             var fixed = self.fixed_value();
             if (fixed instanceof AST_Defun) {
                 d.fixed = fixed = make_node(AST_Function, fixed, fixed);
+                if (!compressor.option("reduce_funcs")) d.single_use = false;
             }
             if (d.single_use && fixed instanceof AST_Function) {
                 if (d.escaped && d.scope !== self.scope || recursive_ref(compressor, d)) {

test/compress/collapse_vars.js

@@ -2369,6 +2369,7 @@ duplicate_argname: {
 issue_2298: {
     options = {
         collapse_vars: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3037,6 +3038,7 @@ issue_2437: {
         inline: true,
         join_vars: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         sequences: true,

test/compress/drop-unused.js

@@ -673,6 +673,7 @@ issue_1539: {
 vardef_value: {
     options = {
         keep_fnames: false,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -1080,6 +1081,7 @@ var_catch_toplevel: {
     options = {
         conditionals: true,
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -1114,6 +1116,7 @@ issue_2105_1: {
         collapse_vars: true,
         inline: true,
         passes: 3,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -1156,6 +1159,7 @@ issue_2105_2: {
         passes: 3,
         properties: true,
         pure_getters: "strict",
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unsafe: true,

test/compress/functions.js

@@ -305,6 +305,7 @@ issue_2084: {
         evaluate: true,
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -340,6 +341,7 @@ issue_2084: {
 issue_2097: {
     options = {
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -515,6 +517,7 @@ issue_2428: {
         inline: true,
         passes: 3,
         pure_getters: "strict",
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,

test/compress/issue-1656.js

@@ -15,6 +15,7 @@ f7: {
         negate_iife: true,
         passes: 3,
         properties: true,
+        reduce_funcs: true,
         reduce_vars: true,
         sequences: true,
         side_effects: true,

test/compress/issue-1673.js

@@ -1,5 +1,6 @@
 side_effects_catch: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -34,6 +35,7 @@ side_effects_catch: {
 
 side_effects_else: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -62,6 +64,7 @@ side_effects_else: {
 
 side_effects_finally: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -98,6 +101,7 @@ side_effects_finally: {
 
 side_effects_label: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -130,6 +134,7 @@ side_effects_label: {
 
 side_effects_switch: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,

test/compress/issue-1833.js

@@ -1,6 +1,7 @@
 iife_for: {
     options = {
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -26,6 +27,7 @@ iife_for: {
 iife_for_in: {
     options = {
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -51,6 +53,7 @@ iife_for_in: {
 iife_do: {
     options = {
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -80,6 +83,7 @@ iife_do: {
 iife_while: {
     options = {
         negate_iife: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,

test/compress/pure_getters.js

@@ -185,6 +185,7 @@ issue_2110_1: {
         pure_getters: "strict",
         sequences: true,
         side_effects: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -215,6 +216,7 @@ issue_2110_2: {
     options = {
         collapse_vars: true,
         pure_getters: "strict",
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }

test/compress/reduce_vars.js

@@ -1292,6 +1292,7 @@ defun_reference: {
 
 defun_inline_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -1320,6 +1321,7 @@ defun_inline_1: {
 
 defun_inline_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -1351,6 +1353,7 @@ defun_inline_3: {
         evaluate: true,
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -1460,6 +1463,7 @@ func_inline: {
 func_modified: {
     options = {
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -1487,6 +1491,7 @@ func_modified: {
 defun_label: {
     options = {
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -1629,6 +1634,7 @@ iife_eval_2: {
 
 iife_func_side_effects: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2001,6 +2007,7 @@ redefine_arguments_1: {
     options = {
         evaluate: true,
         keep_fargs: false,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2041,6 +2048,7 @@ redefine_arguments_2: {
         evaluate: true,
         inline: true,
         keep_fargs: false,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -2079,6 +2087,7 @@ redefine_arguments_3: {
         inline: true,
         keep_fargs: false,
         passes: 3,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -2115,6 +2124,7 @@ redefine_farg_1: {
     options = {
         evaluate: true,
         keep_fargs: false,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2154,6 +2164,7 @@ redefine_farg_2: {
         evaluate: true,
         inline: true,
         keep_fargs: false,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -2192,6 +2203,7 @@ redefine_farg_3: {
         inline: true,
         keep_fargs: false,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -2701,6 +2713,7 @@ iife_assign: {
 
 issue_1850_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: false,
         unused: true,
@@ -2724,6 +2737,7 @@ issue_1850_1: {
 
 issue_1850_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: "funcs",
         unused: true,
@@ -2746,6 +2760,7 @@ issue_1850_2: {
 
 issue_1850_3: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: "vars",
         unused: true,
@@ -2769,6 +2784,7 @@ issue_1850_3: {
 
 issue_1850_4: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3002,6 +3018,7 @@ obj_arg_1: {
         evaluate: true,
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3033,6 +3050,7 @@ obj_arg_2: {
         inline: true,
         passes: 2,
         properties: true,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -3105,6 +3123,7 @@ func_arg_2: {
 
 regex_loop: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3277,6 +3296,7 @@ escaped_prop_1: {
         evaluate: true,
         inline: true,
         pure_getters: "strict",
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -3302,6 +3322,7 @@ escaped_prop_1: {
 
 escaped_prop_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3420,6 +3441,7 @@ issue_2420_2: {
 
 issue_2423_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3444,6 +3466,7 @@ issue_2423_1: {
 issue_2423_2: {
     options = {
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3467,6 +3490,7 @@ issue_2423_2: {
 
 issue_2423_3: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3485,6 +3509,7 @@ issue_2423_3: {
 issue_2423_4: {
     options = {
         inline: true,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -3505,6 +3530,7 @@ issue_2423_5: {
     options = {
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -3543,6 +3569,7 @@ issue_2423_6: {
     options = {
         inline: true,
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -3583,6 +3610,7 @@ issue_2423_6: {
 
 issue_2440_eval_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3613,6 +3641,7 @@ issue_2440_eval_1: {
 
 issue_2440_eval_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3643,6 +3672,7 @@ issue_2440_eval_2: {
 
 issue_2440_with_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3669,6 +3699,7 @@ issue_2440_with_1: {
 
 issue_2440_with_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3695,6 +3726,7 @@ issue_2440_with_2: {
 
 issue_2442: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3709,6 +3741,7 @@ issue_2442: {
 
 recursive_inlining_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3729,6 +3762,7 @@ recursive_inlining_1: {
 
 recursive_inlining_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3751,6 +3785,7 @@ recursive_inlining_2: {
 recursive_inlining_3: {
     options = {
         passes: 2,
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3788,6 +3823,7 @@ recursive_inlining_3: {
 
 recursive_inlining_4: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3834,6 +3870,7 @@ recursive_inlining_4: {
 
 recursive_inlining_5: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3887,6 +3924,7 @@ recursive_inlining_5: {
 
 issue_2450_1: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3910,6 +3948,7 @@ issue_2450_1: {
 
 issue_2450_2: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3932,6 +3971,7 @@ issue_2450_2: {
 
 issue_2450_3: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         unused: true,
     }
@@ -3962,6 +4002,7 @@ issue_2450_3: {
 
 issue_2450_4: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -3995,6 +4036,7 @@ issue_2450_4: {
 
 issue_2450_5: {
     options = {
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -4030,6 +4072,7 @@ issue_2450_5: {
 issue_2449: {
     options = {
         passes: 10,
+        reduce_funcs: true,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -4061,3 +4104,74 @@ issue_2449: {
     }
     expect_stdout: "PASS"
 }
+
+perf_1: {
+    options = {
+        passes: 10,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function foo(x, y, z) {
+            return x < y ? x * y + z : x * z - y;
+        }
+        function indirect_foo(x, y, z) {
+            return foo(x, y, z);
+        }
+        var sum = 0;
+        for (var i = 0; i < 100; ++i) {
+            sum += indirect_foo(i, i+1, i*3);
+        }
+        console.log(sum);
+    }
+    expect: {
+        function indirect_foo(x, y, z) {
+            return function(x, y, z) {
+                return x < y ? x * y + z : x * z - y;
+            }(x, y, z);
+        }
+        var sum = 0;
+        for (var i = 0; i < 100; ++i)
+            sum += indirect_foo(i, i + 1, 3 * i);
+        console.log(sum);
+    }
+    expect_stdout: "348150"
+}
+
+perf_2: {
+    options = {
+        passes: 10,
+        reduce_funcs: false,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function foo(x, y, z) {
+            return x < y ? x * y + z : x * z - y;
+        }
+        function indirect_foo(x, y, z) {
+            return foo(x, y, z);
+        }
+        var sum = 0;
+        for (var i = 0; i < 100; ++i) {
+            sum += indirect_foo(i, i+1, i*3);
+        }
+        console.log(sum);
+    }
+    expect: {
+        function foo(x, y, z) {
+            return x < y ? x * y + z : x * z - y;
+        }
+        function indirect_foo(x, y, z) {
+            return foo(x, y, z);
+        }
+        var sum = 0;
+        for (var i = 0; i < 100; ++i)
+            sum += indirect_foo(i, i + 1, 3 * i);
+        console.log(sum);
+    }
+    expect_stdout: "348150"
+}