enhance conditionals, if_return & side_effects (#5348)

lib/compress.js

@@ -3336,23 +3336,24 @@ Compressor.prototype.compress = function(node) {
                         if (ab.label) remove(ab.label.thedef.references, ab);
                         changed = true;
                         stat = stat.clone();
-                        stat.condition = stat.condition.negate(compressor);
-                        var body = as_statement_array_with_return(stat.body, ab);
                         stat.body = make_node(AST_BlockStatement, stat, {
+                            body: as_statement_array_with_return(stat.body, ab),
+                        });
+                        stat.alternative = make_node(AST_BlockStatement, stat, {
                             body: as_statement_array(stat.alternative).concat(extract_functions()),
                         });
-                        stat.alternative = make_node(AST_BlockStatement, stat, { body: body });
                         statements[i] = stat;
                         statements[i] = stat.transform(compressor);
                         continue;
                     }
 
-                    if (ab && !stat.alternative && stat.body instanceof AST_BlockStatement && next instanceof AST_Jump) {
+                    if (ab && !stat.alternative && next instanceof AST_Jump) {
-                        var negated = stat.condition.negate(compressor);
+                        var cond = stat.condition;
-                        if (negated.print_to_string().length <= stat.condition.print_to_string().length) {
+                        cond = best_of_expression(cond, cond.negate(compressor), stat.body instanceof AST_BlockStatement);
+                        if (cond !== stat.condition) {
                             changed = true;
                             stat = stat.clone();
-                            stat.condition = negated;
+                            stat.condition = cond;
                             statements[j] = stat.body;
                             stat.body = next;
                             statements[i] = stat;
@@ -3369,8 +3370,9 @@ Compressor.prototype.compress = function(node) {
                         stat.body = make_node(AST_BlockStatement, stat.body, {
                             body: as_statement_array(stat.body).concat(extract_functions()),
                         });
-                        var body = as_statement_array_with_return(stat.alternative, alt);
+                        stat.alternative = make_node(AST_BlockStatement, stat.alternative, {
-                        stat.alternative = make_node(AST_BlockStatement, stat.alternative, { body: body });
+                            body: as_statement_array_with_return(stat.alternative, alt),
+                        });
                         statements[i] = stat;
                         statements[i] = stat.transform(compressor);
                         continue;
@@ -3392,15 +3394,6 @@ Compressor.prototype.compress = function(node) {
                     var value = stat.body.value;
                     var in_bool = stat.body.in_bool || next instanceof AST_Return && next.in_bool;
                     //---
-                    // pretty silly case, but:
-                    // if (foo()) return; return; ---> foo(); return;
-                    if (!value && !stat.alternative
-                        && (in_lambda && !next || next instanceof AST_Return && !next.value)) {
-                        changed = true;
-                        statements[i] = make_node(AST_SimpleStatement, stat.condition, { body: stat.condition });
-                        continue;
-                    }
-                    //---
                     // if (foo()) return x; return y; ---> return foo() ? x : y;
                     if (!stat.alternative && next instanceof AST_Return) {
                         changed = true;
@@ -8211,12 +8204,12 @@ Compressor.prototype.compress = function(node) {
                     node.right = rhs.drop_side_effect_free(compressor);
                 }
                 if (op == "??") return node;
-                var negated = make_node(AST_Binary, this, {
+                var negated = node.clone();
-                    operator: op == "&&" ? "||" : "&&",
+                negated.operator = op == "&&" ? "||" : "&&";
-                    left: left.negate(compressor, first_in_statement),
+                negated.left = left.negate(compressor, first_in_statement);
-                    right: node.right,
+                if (negated.operator == negated.right.operator) swap_chain(negated);
-                });
+                var best = first_in_statement ? best_of_statement : best_of_expression;
-                return first_in_statement ? best_of_statement(node, negated) : best_of_expression(node, negated);
+                return op == "&&" ? best(node, negated) : best(negated, node);
             }
             var lhs = left.drop_side_effect_free(compressor, first_in_statement);
             if (!lhs) return rhs;
@@ -9082,8 +9075,8 @@ Compressor.prototype.compress = function(node) {
             // here because they are only used in an equality comparison later on.
             self.condition = negated;
             var tmp = self.body;
-            self.body = self.alternative || make_node(AST_EmptyStatement, self);
+            self.body = self.alternative;
-            self.alternative = tmp;
+            self.alternative = is_empty(tmp) ? null : tmp;
         }
         var body_defuns = [];
         var body_var_defs = [];
@@ -9220,10 +9213,12 @@ Compressor.prototype.compress = function(node) {
                     var line = stat.body[i];
                     if (line instanceof AST_EmptyStatement) continue;
                     if (line instanceof AST_Exit) {
-                        if (exprs.length == 0) return;
+                        if (i == 0) return;
+                        if (exprs.length > 0) {
                             line = line.clone();
                             exprs.push(line.value || make_node(AST_Undefined, line).transform(compressor));
                             line.value = make_sequence(stat, exprs);
+                        }
                         var block = stat.clone();
                         block.body = block.body.slice(i + 1);
                         block.body.unshift(line);
@@ -10962,6 +10957,23 @@ Compressor.prototype.compress = function(node) {
         return !node.has_side_effects(compressor);
     }
 
+    function swap_chain(self, compressor) {
+        var rhs = self.right;
+        self.left = make_node(AST_Binary, self, {
+            operator: self.operator,
+            left: self.left,
+            right: rhs.left,
+            start: self.left.start,
+            end: rhs.left.end
+        });
+        self.right = rhs.right;
+        if (compressor) {
+            self.left = self.left.transform(compressor);
+        } else if (self.operator == rhs.left.operator) {
+            swap_chain(self.left);
+        }
+    }
+
     OPT(AST_Binary, function(self, compressor) {
         if (commutativeOperators[self.operator]
             && self.right.is_constant()
@@ -11132,7 +11144,7 @@ Compressor.prototype.compress = function(node) {
             && lazy_op[self.operator]
             && self.right instanceof AST_Binary
             && self.operator == self.right.operator) {
-            swap_chain();
+            swap_chain(self, compressor);
         }
         if (compressor.option("strings") && self.operator == "+") {
             // "foo" + 42 + "" ---> "foo" + 42
@@ -11164,7 +11176,7 @@ Compressor.prototype.compress = function(node) {
                 && (self.left.is_string(compressor) && self.right.is_string(compressor)
                     || self.right.left.is_string(compressor)
                         && (self.left.is_constant() || !self.right.right.has_side_effects(compressor)))) {
-                swap_chain();
+                swap_chain(self, compressor);
             }
         }
         if (compressor.option("evaluate")) {
@@ -11631,19 +11643,6 @@ Compressor.prototype.compress = function(node) {
                 self.right = tmp;
             }
         }
-
-        function swap_chain() {
-            var rhs = self.right;
-            self.left = make_node(AST_Binary, self, {
-                operator: self.operator,
-                left: self.left,
-                right: rhs.left,
-                start: self.left.start,
-                end: rhs.left.end
-            });
-            self.right = rhs.right;
-            self.left = self.left.transform(compressor);
-        }
     });
 
     OPT(AST_SymbolExport, function(self) {
@@ -12747,7 +12746,7 @@ Compressor.prototype.compress = function(node) {
                         if (flatten && value.has_side_effects(compressor)) flatten = false;
                     }
                 }
-                if (!flatten) values.unshift(retValue);
+                values.unshift(retValue);
                 while (--i >= 0) {
                     var value = elements[i].drop_side_effect_free(compressor);
                     if (value) {
@@ -12758,10 +12757,7 @@ Compressor.prototype.compress = function(node) {
                         index--;
                     }
                 }
-                if (flatten) {
+                return flatten ? make_sequence(self, values).optimize(compressor) : make_node(AST_Sub, self, {
-                    values.push(retValue);
-                    return make_sequence(self, values).optimize(compressor);
-                } else return make_node(AST_Sub, self, {
                     expression: make_node(AST_Array, expr, { elements: values }),
                     property: make_node(AST_Number, prop, { value: index }),
                 });

test/compress/comparisons.js

@@ -489,7 +489,7 @@ issue_3413: {
     }
     expect: {
         var b;
-        void 0 !== ("" < b || void 0) || console.log("PASS");
+        void 0 === ("" < b || void 0) && console.log("PASS");
     }
     expect_stdout: "PASS"
 }

test/compress/const.js

@@ -597,8 +597,7 @@ do_if_continue_1: {
     }
     expect: {
         do {
-            if (!console);
+            if (console) {
-            else {
                 console.log("PASS");
                 {
                     const a = 0;
@@ -628,8 +627,7 @@ do_if_continue_2: {
     }
     expect: {
         do {
-            if (!console);
+            if (console) {
-            else {
                 console.log("PASS");
                 {
                     const a = 0;
@@ -1518,6 +1516,7 @@ issue_4689: {
 
 issue_4691: {
     options = {
+        conditionals: true,
         if_return: true,
         toplevel: true,
     }

test/compress/functions.js

@@ -7981,6 +7981,7 @@ issue_5264_2: {
 
 issue_5283: {
     options = {
+        conditionals: true,
         if_return: true,
         inline: true,
         pure_getters: "strict",
@@ -8005,11 +8006,10 @@ issue_5283: {
         var a = "FAIL 1";
         (function() {
             a = "PASS";
-            if (!console)
+            console || function(a) {
-                (function(a) {
                 console.log("FAIL 2");
                 a.p;
-                })();
+            }();
         })();
         console.log(a);
     }

test/compress/if_return.js

@@ -698,7 +698,9 @@ iife_if_return_simple: {
 
 nested_if_break: {
     options = {
+        conditionals: true,
         if_return: true,
+        side_effects: true,
     }
     input: {
         for (var i = 0; i < 3; i++)
@@ -709,8 +711,7 @@ nested_if_break: {
     }
     expect: {
         for (var i = 0; i < 3; i++)
-            L1: if ("number" == typeof i)
+            L1: "number" == typeof i && 0 !== i && console.log(i);
-                if (0 !== i) console.log(i);
     }
     expect_stdout: [
         "1",
@@ -749,11 +750,11 @@ nested_if_continue: {
         function f(n) {
             for (var i = 0;
                 "number" == typeof n
-                    && (0 !== n
+                    && (0 === n
-                        ? 1 !== n
+                        ? console.log("even", i)
-                            ? i++
+                        : 1 === n
-                            : console.log("odd", i)
+                        ? console.log("odd", i)
-                        : console.log("even", i)),
+                        : i++),
                 0 <= (n -= 2););
         }
         f(37);

test/compress/issue-1052.js

@@ -5,9 +5,8 @@ multiple_functions: {
     }
     input: {
         (function() {
-            if ( !window ) {
+            if (!window)
                 return;
-            }
             function f() {}
             function g() {}
         })();
@@ -30,9 +29,8 @@ single_function: {
     }
     input: {
         (function() {
-            if ( !window ) {
+            if (!window)
                 return;
-            }
             function f() {}
         })();
     }
@@ -51,14 +49,12 @@ deeply_nested: {
     }
     input: {
         (function() {
-            if ( !window ) {
+            if (!window)
                 return;
-            }
             function f() {}
             function g() {}
-            if ( !document ) {
+            if (!document)
                 return;
-            }
             function h() {}
         })();
     }
@@ -66,8 +62,8 @@ deeply_nested: {
         (function() {
             // NOTE: other compression steps will reduce this
             // down to just `window`.
-            if ( window )
+            if (!window);
-                if ( !document );
+            else if (!document);
             function f() {}
             function g() {}
             function h() {}
@@ -82,16 +78,16 @@ not_hoisted_when_already_nested: {
     }
     input: {
         (function() {
-            if ( !window ) {
+            if (!window)
                 return;
-            }
             if (foo) function f() {}
         })();
     }
     expect: {
         (function() {
-            if ( window )
+            if (!window);
-                if ( foo ) function f() {}
+            else if (foo)
+                function f() {}
         })();
     }
 }
@@ -104,15 +100,19 @@ defun_if_return: {
     input: {
         function e() {
             function f() {}
-            if (!window) return;
+            if (!window)
-            else function g() {}
+                return;
+            else
+                function g() {}
             function h() {}
         }
     }
     expect: {
         function e() {
             function f() {}
-            if (window) function g() {}
+            if (!window);
+            else
+                function g() {}
             function h() {}
         }
     }
@@ -126,8 +126,10 @@ defun_hoist_funs: {
     input: {
         function e() {
             function f() {}
-            if (!window) return;
+            if (!window)
-            else function g() {}
+                return;
+            else
+                function g() {}
             function h() {}
         }
     }
@@ -136,7 +138,7 @@ defun_hoist_funs: {
             function f() {}
             function g() {}
             function h() {}
-            if (window);
+            if (!window);
         }
     }
 }
@@ -149,15 +151,18 @@ defun_else_if_return: {
     input: {
         function e() {
             function f() {}
-            if (window) function g() {}
+            if (window)
-            else return;
+                function g() {}
+            else
+                return;
             function h() {}
         }
     }
     expect: {
         function e() {
             function f() {}
-            if (window) function g() {}
+            if (window)
+                function g() {}
             function h() {}
         }
     }

test/compress/issue-1447.js

@@ -40,6 +40,9 @@ conditional_false_stray_else_in_loop: {
             console.log(i);
         }
     }
-    expect_exact: "for(var i=1;i<=4;++i)if(!(i<=2))console.log(i);"
+    expect_exact: "for(var i=1;i<=4;++i)if(i<=2);else console.log(i);"
-    expect_stdout: true
+    expect_stdout: [
+        "3",
+        "4",
+    ]
 }

test/compress/issue-979.js

@@ -1,4 +1,4 @@
-issue979_reported: {
+reported: {
     options = {
         booleans: true,
         comparisons: true,
@@ -17,18 +17,15 @@ issue979_reported: {
     }
     input: {
         function f1() {
-            if (a == 1 || b == 2) {
+            if (a == 1 || b == 2)
                 foo();
         }
-        }
         function f2() {
-            if (!(a == 1 || b == 2)) {
+            if (!(a == 1 || b == 2));
-            }
+            else
-            else {
                 foo();
         }
     }
-    }
     expect: {
         function f1() {
             1 != a && 2 != b || foo();
@@ -39,7 +36,7 @@ issue979_reported: {
     }
 }
 
-issue979_test_negated_is_best: {
+test_negated_is_best: {
     options = {
         booleans: true,
         comparisons: true,
@@ -58,38 +55,30 @@ issue979_test_negated_is_best: {
     }
     input: {
         function f3() {
-            if (a == 1 | b == 2) {
+            if (a == 1 | b == 2)
                 foo();
         }
-        }
         function f4() {
-            if (!(a == 1 | b == 2)) {
+            if (!(a == 1 | b == 2));
-            }
+            else
-            else {
                 foo();
         }
-        }
         function f5() {
-            if (a == 1 && b == 2) {
+            if (a == 1 && b == 2)
                 foo();
         }
-        }
         function f6() {
-            if (!(a == 1 && b == 2)) {
+            if (!(a == 1 && b == 2));
-            }
+            else
-            else {
                 foo();
         }
-        }
         function f7() {
-            if (a == 1 || b == 2) {
+            if (a == 1 || b == 2)
                 foo();
-            }
+            else
-            else {
                 return bar();
         }
     }
-    }
     expect: {
         function f3() {
             1 == a | 2 == b && foo();
@@ -101,10 +90,12 @@ issue979_test_negated_is_best: {
             1 == a && 2 == b && foo();
         }
         function f6() {
-            1!=a||2!=b||foo();
+            1 == a && 2 == b && foo();
         }
         function f7() {
-            if(1!=a&&2!=b)return bar();foo()
+            if (1 != a && 2 != b)
+                return bar();
+            foo();
         }
     }
 }

test/compress/let.js

@@ -912,8 +912,7 @@ do_if_continue_1: {
     expect: {
         "use strict";
         do {
-            if (!console);
+            if (console) {
-            else {
                 console.log("PASS");
                 {
                     let a = 0;
@@ -946,8 +945,7 @@ do_if_continue_2: {
     expect: {
         "use strict";
         do {
-            if (!console);
+            if (console) {
-            else {
                 console.log("FAIL");
                 {
                     let a = 0;
@@ -1667,9 +1665,7 @@ issue_4438: {
     expect: {
         "use strict";
         function f() {
-            if (!console)
+            if (console) {
-                ;
-            else {
                 let a = console.log;
                 void a("PASS");
             }
@@ -1757,6 +1753,7 @@ issue_4689: {
 
 issue_4691: {
     options = {
+        conditionals: true,
         if_return: true,
         toplevel: true,
     }

test/compress/side_effects.js

@@ -617,7 +617,7 @@ issue_4730_2: {
     }
     expect: {
         var a;
-        !console.log("PASS") || a && a[a.p];
+        console.log("PASS") && a && a[a.p];
     }
     expect_stdout: "PASS"
 }

test/compress/typeof.js

@@ -307,7 +307,7 @@ typeof_defined_1: {
     }
     expect: {
         "undefined" == typeof A && A;
-        "undefined" != typeof A || A;
+        "undefined" == typeof A && A;
     }
 }
 
@@ -324,7 +324,7 @@ typeof_defined_2: {
     }
     expect: {
         "function" != typeof A && A;
-        "function" == typeof A || A;
+        "function" != typeof A && A;
     }
 }
 
@@ -355,16 +355,19 @@ typeof_defined_3: {
         "undefined" == typeof A && "undefined" == typeof B && (A, B);
         "undefined" == typeof A && "undefined" != typeof B && A;
         "undefined" != typeof A && "undefined" == typeof B && B;
+        // dropped
         "undefined" == typeof A && "undefined" == typeof B || (A, B);
         "undefined" == typeof A && "undefined" != typeof B || (A, B);
         "undefined" != typeof A && "undefined" == typeof B || (A, B);
         "undefined" != typeof A && "undefined" != typeof B || (A, B);
-        "undefined" == typeof A || "undefined" == typeof B && B;
+        "undefined" != typeof A && "undefined" == typeof B && B;
-        "undefined" != typeof A || "undefined" == typeof B && (A, B);
+        // dropped
-        "undefined" != typeof A || "undefined" != typeof B && A;
+        "undefined" == typeof A && "undefined" == typeof B && (A, B);
-        "undefined" == typeof A || "undefined" != typeof B || B;
+        "undefined" == typeof A && "undefined" != typeof B && A;
-        "undefined" != typeof A || "undefined" == typeof B || A;
+        // dropped
-        "undefined" != typeof A || "undefined" != typeof B || (A, B);
+        "undefined" != typeof A && "undefined" == typeof B && B;
+        "undefined" == typeof A && "undefined" != typeof B && A;
+        "undefined" == typeof A && "undefined" == typeof B && (A, B);
     }
 }
 
@@ -392,6 +395,7 @@ typeof_defined_4: {
         "object" != typeof A || "object" != typeof B || (A, B);
     }
     expect: {
+        // dropped
         "object" == typeof A && "object" != typeof B && B;
         "object" != typeof A && "object" == typeof B && A;
         "object" != typeof A && "object" != typeof B && (A, B);
@@ -399,12 +403,14 @@ typeof_defined_4: {
         "object" == typeof A && "object" != typeof B || (A, B);
         "object" != typeof A && "object" == typeof B || (A, B);
         "object" != typeof A && "object" != typeof B || (A, B);
-        "object" == typeof A || "object" == typeof B && A;
+        "object" != typeof A && "object" == typeof B && A;
-        "object" == typeof A || "object" != typeof B && (A, B);
+        "object" != typeof A && "object" != typeof B && (A, B);
-        "object" != typeof A || "object" != typeof B && B;
+        // dropped
-        "object" == typeof A || "object" == typeof B || (A, B);
+        "object" == typeof A && "object" != typeof B && B;
-        "object" == typeof A || "object" != typeof B || A;
+        "object" != typeof A && "object" != typeof B && (A, B);
-        "object" != typeof A || "object" == typeof B || B;
+        "object" != typeof A && "object" == typeof B && A;
+        "object" == typeof A && "object" != typeof B && B;
+        // dropped
     }
 }