[Pkg-javascript-commits] [uglifyjs] 316/491: improve `unused` on assign-only symbols (#2568)

Jonas Smedegaard dr at jones.dk
Wed Feb 14 19:51:48 UTC 2018


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js pushed a commit to annotated tag debian/3.3.10-1
in repository uglifyjs.

commit 0aff037a3574dfcf856484f4db67dd1b0d66c1c8
Author: Alex Lam S.L <alexlamsl at gmail.com>
Date:   Sat Dec 9 06:19:29 2017 +0800

    improve `unused` on assign-only symbols (#2568)
---
 lib/compress.js              |  38 ++++++-----
 test/compress/drop-unused.js | 150 ++++++++++++++++++++++++++-----------------
 2 files changed, 113 insertions(+), 75 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 7f1b46e..ce0fbdd 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2487,6 +2487,20 @@ merge(Compressor.prototype, {
         // pass 3: we should drop declarations not in_use
         var tt = new TreeTransformer(
             function before(node, descend, in_list) {
+                var parent = tt.parent();
+                if (drop_vars) {
+                    var sym = assign_as_unused(node);
+                    if (sym instanceof AST_SymbolRef
+                        && !(sym.definition().id in in_use_ids)) {
+                        if (node instanceof AST_Assign) {
+                            return maintain_this_binding(parent, node, node.right.transform(tt));
+                        }
+                        return make_node(AST_Number, node, {
+                            value: 0
+                        });
+                    }
+                }
+                if (scope !== self) return;
                 if (node instanceof AST_Function
                     && node.name
                     && !compressor.option("keep_fnames")) {
@@ -2520,9 +2534,7 @@ merge(Compressor.prototype, {
                         def.eliminated++;
                         return make_node(AST_EmptyStatement, node);
                     }
-                    return node;
                 }
-                var parent = tt.parent();
                 if (node instanceof AST_Definitions && !(parent instanceof AST_ForIn && parent.init === node)) {
                     // place uninitialized names at the start
                     var body = [], head = [], tail = [];
@@ -2602,18 +2614,6 @@ merge(Compressor.prototype, {
                         });
                     }
                 }
-                if (drop_vars) {
-                    var sym = assign_as_unused(node);
-                    if (sym instanceof AST_SymbolRef
-                        && !(sym.definition().id in in_use_ids)) {
-                        if (node instanceof AST_Assign) {
-                            return maintain_this_binding(parent, node, node.right.transform(tt));
-                        }
-                        return make_node(AST_Number, node, {
-                            value: 0
-                        });
-                    }
-                }
                 // certain combination of unused name + side effect leads to:
                 //    https://github.com/mishoo/UglifyJS2/issues/44
                 //    https://github.com/mishoo/UglifyJS2/issues/1830
@@ -2645,8 +2645,13 @@ merge(Compressor.prototype, {
                     }
                     return node;
                 }
-                if (node instanceof AST_Scope && node !== self)
+                if (node instanceof AST_Scope) {
+                    var save_scope = scope;
+                    scope = node;
+                    descend(node, this);
+                    scope = save_scope;
                     return node;
+                }
 
                 function template(sym) {
                     return {
@@ -2662,8 +2667,7 @@ merge(Compressor.prototype, {
 
         function scan_ref_scoped(node, descend) {
             var sym;
-            if (scope === self
-                && (sym = assign_as_unused(node)) instanceof AST_SymbolRef
+            if ((sym = assign_as_unused(node)) instanceof AST_SymbolRef
                 && self.variables.get(sym.name) === sym.definition()) {
                 if (node instanceof AST_Assign) node.right.walk(tw);
                 return true;
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index 189a000..f9ef787 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -179,7 +179,9 @@ keep_fnames: {
 }
 
 drop_assign: {
-    options = { unused: true };
+    options = {
+        unused: true,
+    }
     input: {
         function f1() {
             var a;
@@ -200,7 +202,7 @@ drop_assign: {
             var a;
             return function() {
                 a = 1;
-            }
+            };
         }
     }
     expect: {
@@ -217,16 +219,17 @@ drop_assign: {
             return 1;
         }
         function f5() {
-            var a;
             return function() {
-                a = 1;
-            }
+                1;
+            };
         }
     }
 }
 
 keep_assign: {
-    options = { unused: "keep_assign" };
+    options = {
+        unused: "keep_assign",
+    }
     input: {
         function f1() {
             var a;
@@ -247,7 +250,7 @@ keep_assign: {
             var a;
             return function() {
                 a = 1;
-            }
+            };
         }
     }
     expect: {
@@ -270,19 +273,22 @@ keep_assign: {
             var a;
             return function() {
                 a = 1;
-            }
+            };
         }
     }
 }
 
 drop_toplevel_funcs: {
-    options = { toplevel: "funcs", unused: true };
+    options = {
+        toplevel: "funcs",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -298,13 +304,16 @@ drop_toplevel_funcs: {
 }
 
 drop_toplevel_vars: {
-    options = { toplevel: "vars", unused: true };
+    options = {
+        toplevel: "vars",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -312,11 +321,10 @@ drop_toplevel_vars: {
         console.log(b = 3);
     }
     expect: {
-        var c = g;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         2;
         function g() {}
@@ -326,13 +334,17 @@ drop_toplevel_vars: {
 }
 
 drop_toplevel_vars_fargs: {
-    options = { keep_fargs: false, toplevel: "vars", unused: true };
+    options = {
+        keep_fargs: false,
+        toplevel: "vars",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -340,11 +352,10 @@ drop_toplevel_vars_fargs: {
         console.log(b = 3);
     }
     expect: {
-        var c = g;
         function f() {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         2;
         function g() {}
@@ -354,13 +365,16 @@ drop_toplevel_vars_fargs: {
 }
 
 drop_toplevel_all: {
-    options = { toplevel: true, unused: true };
+    options = {
+        toplevel: true,
+        unused: true
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -374,13 +388,16 @@ drop_toplevel_all: {
 }
 
 drop_toplevel_retain: {
-    options = { top_retain: "f,a,o", unused: true };
+    options = {
+        top_retain: "f,a,o",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -388,26 +405,28 @@ drop_toplevel_retain: {
         console.log(b = 3);
     }
     expect: {
-        var a, c = g;
+        var a;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         a = 2;
-        function g() {}
         console.log(3);
     }
 }
 
 drop_toplevel_retain_array: {
-    options = { top_retain: [ "f", "a", "o" ], unused: true };
+    options = {
+        top_retain: [ "f", "a", "o" ],
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -415,26 +434,28 @@ drop_toplevel_retain_array: {
         console.log(b = 3);
     }
     expect: {
-        var a, c = g;
+        var a;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         a = 2;
-        function g() {}
         console.log(3);
     }
 }
 
 drop_toplevel_retain_regex: {
-    options = { top_retain: /^[fao]$/, unused: true };
+    options = {
+        top_retain: /^[fao]$/,
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -442,26 +463,29 @@ drop_toplevel_retain_regex: {
         console.log(b = 3);
     }
     expect: {
-        var a, c = g;
+        var a;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         a = 2;
-        function g() {}
         console.log(3);
     }
 }
 
 drop_toplevel_all_retain: {
-    options = { toplevel: true, top_retain: "f,a,o", unused: true };
+    options = {
+        toplevel: true,
+        top_retain: "f,a,o",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -469,26 +493,29 @@ drop_toplevel_all_retain: {
         console.log(b = 3);
     }
     expect: {
-        var a, c = g;
+        var a;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         a = 2;
-        function g() {}
         console.log(3);
     }
 }
 
 drop_toplevel_funcs_retain: {
-    options = { toplevel: "funcs", top_retain: "f,a,o", unused: true };
+    options = {
+        toplevel: "funcs",
+        top_retain: "f,a,o",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -500,7 +527,7 @@ drop_toplevel_funcs_retain: {
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -509,13 +536,17 @@ drop_toplevel_funcs_retain: {
 }
 
 drop_toplevel_vars_retain: {
-    options = { toplevel: "vars", top_retain: "f,a,o", unused: true };
+    options = {
+        toplevel: "vars",
+        top_retain: "f,a,o",
+        unused: true,
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -523,11 +554,11 @@ drop_toplevel_vars_retain: {
         console.log(b = 3);
     }
     expect: {
-        var a, c = g;
+        var a;
         function f(d) {
             return function() {
-                c = 2;
-            }
+                2;
+            };
         }
         a = 2;
         function g() {}
@@ -537,13 +568,16 @@ drop_toplevel_vars_retain: {
 }
 
 drop_toplevel_keep_assign: {
-    options = { toplevel: true, unused: "keep_assign" };
+    options = {
+        toplevel: true,
+        unused: "keep_assign",
+    }
     input: {
         var a, b = 1, c = g;
         function f(d) {
             return function() {
                 c = 2;
-            }
+            };
         }
         a = 2;
         function g() {}
@@ -753,11 +787,11 @@ issue_1583: {
     expect: {
         function m(t) {
             (function(e) {
-                t = function() {
+                (function() {
                     return (function(a) {
                         return function(a) {};
                     })();
-                }();
+                })();
             })();
         }
     }

-- 
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