From: Alex Lam S.L <alexlamsl@gmail.com>
Date: Wed, 13 Dec 2017 17:20:36 +0000 (+0800)
Subject: fold `cascade` functionality into `collapse_vars` (#2586)
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=ef618332ea92db57e59f90f166035a0e7cf8a509;p=UglifyJS.git

fold `cascade` functionality into `collapse_vars` (#2586)
---

diff --git a/README.md b/README.md
index 8a34f6e4..ef496178 100644
--- a/README.md
+++ b/README.md
@@ -601,9 +601,6 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 - `booleans` (default: `true`) -- various optimizations for boolean context,
   for example `!!a ? b : c → a ? b : c`
 
-- `cascade` (default: `true`) -- small optimization for sequences, transform
-  `x, x` into `x` and `x = something(), x` into `x = something()`
-
 - `collapse_vars` (default: `true`) -- Collapse single-use non-constant variables,
   side effects permitting.
 
diff --git a/lib/compress.js b/lib/compress.js
index 004858ac..6e984ffa 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -49,7 +49,6 @@ function Compressor(options, false_by_default) {
     TreeTransformer.call(this, this.before, this.after);
     this.options = defaults(options, {
         booleans      : !false_by_default,
-        cascade       : !false_by_default,
         collapse_vars : !false_by_default,
         comparisons   : !false_by_default,
         conditionals  : !false_by_default,
@@ -884,6 +883,8 @@ merge(Compressor.prototype, {
                 if (!hit) {
                     if (node === candidate) {
                         hit = true;
+                        stop_after = find_stop(node, 0);
+                        if (stop_after === node) abort = true;
                         return node;
                     }
                     return;
@@ -963,12 +964,13 @@ merge(Compressor.prototype, {
                         && (parent instanceof AST_Binary && lazy_op(parent.operator)
                             || parent instanceof AST_Conditional
                             || parent instanceof AST_If)) {
-                    if (!(node instanceof AST_Scope)) descend(node, scanner);
-                    abort = true;
-                    return node;
+                    stop_after = node;
+                    if (node instanceof AST_Scope) abort = true;
                 }
                 // Skip (non-executed) functions
                 if (node instanceof AST_Scope) return node;
+            }, function(node) {
+                if (!abort && stop_after === node) abort = true;
             });
             var multi_replacer = new TreeTransformer(function(node) {
                 if (abort) return node;
@@ -1003,6 +1005,7 @@ merge(Compressor.prototype, {
                 while (candidates.length > 0) {
                     var candidate = candidates.pop();
                     var value_def = null;
+                    var stop_after = null;
                     var lhs = get_lhs(candidate);
                     if (!lhs || is_lhs_read_only(lhs) || lhs.has_side_effects(compressor)) continue;
                     // Locate symbols which may execute code outside of scanning range
@@ -1094,19 +1097,43 @@ merge(Compressor.prototype, {
                 if (expr instanceof AST_Assign && !expr.left.has_side_effects(compressor)
                     || expr instanceof AST_Unary && (expr.operator == "++" || expr.operator == "--")) {
                     candidates.push(expr);
-                } else if (expr instanceof AST_Sequence) {
-                    expr.expressions.forEach(extract_candidates);
+                } else if (expr instanceof AST_Case) {
+                    extract_candidates(expr.expression);
+                } else if (expr instanceof AST_Conditional) {
+                    extract_candidates(expr.condition);
+                    extract_candidates(expr.consequent);
+                    extract_candidates(expr.alternative);
                 } else if (expr instanceof AST_Definitions) {
                     expr.definitions.forEach(function(var_def) {
                         if (var_def.value) candidates.push(var_def);
                     });
+                } else if (expr instanceof AST_Exit) {
+                    if (expr.value) extract_candidates(expr.value);
+                } else if (expr instanceof AST_For) {
+                    if (expr.init) extract_candidates(expr.init);
+                } else if (expr instanceof AST_If) {
+                    extract_candidates(expr.condition);
+                } else if (expr instanceof AST_Sequence) {
+                    expr.expressions.forEach(extract_candidates);
                 } else if (expr instanceof AST_SimpleStatement) {
                     extract_candidates(expr.body);
-                } else if (expr instanceof AST_For && expr.init) {
-                    extract_candidates(expr.init);
+                } else if (expr instanceof AST_Switch) {
+                    extract_candidates(expr.expression);
+                    expr.body.forEach(extract_candidates);
                 }
             }
 
+            function find_stop(node, level) {
+                var parent = scanner.parent(level);
+                if (parent instanceof AST_Case) return node;
+                if (parent instanceof AST_Conditional) return node;
+                if (parent instanceof AST_Exit) return node;
+                if (parent instanceof AST_If) return node;
+                if (parent instanceof AST_Sequence) return find_stop(parent, level + 1);
+                if (parent instanceof AST_Switch) return node;
+                return null;
+            }
+
             function mangleable_var(var_def) {
                 var value = var_def.value;
                 if (!(value instanceof AST_SymbolRef)) return;
@@ -3898,7 +3925,6 @@ merge(Compressor.prototype, {
         filter_for_side_effects();
         var end = expressions.length - 1;
         trim_right_for_undefined();
-        if (end > 0 && compressor.option("cascade")) trim_left_for_assignment();
         if (end == 0) {
             self = maintain_this_binding(compressor.parent(), compressor.self(), expressions[0]);
             if (!(self instanceof AST_Sequence)) self = self.optimize(compressor);
@@ -3929,71 +3955,6 @@ merge(Compressor.prototype, {
                 expressions.length = end + 1;
             }
         }
-
-        function trim_left_for_assignment() {
-            for (var i = 0, j = 1; j <= end; j++) {
-                var left = expressions[i];
-                var cdr = expressions[j];
-                if (left instanceof AST_Assign
-                    && !left.left.has_side_effects(compressor)) {
-                    left = left.left;
-                } else if (left instanceof AST_Unary
-                    && (left.operator == "++" || left.operator == "--")) {
-                    left = left.expression;
-                } else left = null;
-                if (!left || is_lhs_read_only(left) || left.has_side_effects(compressor)) {
-                    expressions[++i] = cdr;
-                    continue;
-                }
-                var parent = null, field;
-                expressions[j] = cdr = cdr.clone();
-                while (true) {
-                    if (cdr.equivalent_to(left)) {
-                        var car = expressions[i];
-                        if (car instanceof AST_UnaryPostfix) {
-                            car = make_node(AST_UnaryPrefix, car, {
-                                operator: car.operator,
-                                expression: left
-                            });
-                        } else {
-                            car.write_only = false;
-                        }
-                        if (parent) {
-                            parent[field] = car;
-                            expressions[i] = expressions[j];
-                        } else {
-                            expressions[i] = car;
-                        }
-                        break;
-                    }
-                    if (cdr instanceof AST_Binary && !(cdr instanceof AST_Assign)) {
-                        if (cdr.left.is_constant()) {
-                            if (lazy_op(cdr.operator)) {
-                                expressions[++i] = expressions[j];
-                                break;
-                            }
-                            field = "right";
-                        } else {
-                            field = "left";
-                        }
-                    } else if (cdr instanceof AST_Call
-                            && !(left instanceof AST_PropAccess && cdr.expression.equivalent_to(left))
-                        || cdr instanceof AST_PropAccess
-                        || cdr instanceof AST_Unary && !unary_side_effects(cdr.operator)) {
-                        field = "expression";
-                    } else if (cdr instanceof AST_Conditional) {
-                        field = "condition";
-                    } else {
-                        expressions[++i] = expressions[j];
-                        break;
-                    }
-                    parent = cdr;
-                    cdr = cdr[field] = cdr[field].clone();
-                }
-            }
-            end = i;
-            expressions.length = end + 1;
-        }
     });
 
     AST_Unary.DEFMETHOD("lift_sequences", function(compressor){
diff --git a/test/compress/asm.js b/test/compress/asm.js
index 527e6b43..a9047c5d 100644
--- a/test/compress/asm.js
+++ b/test/compress/asm.js
@@ -16,7 +16,6 @@ asm_mixed: {
         hoist_vars    : true,
         if_return     : true,
         join_vars     : true,
-        cascade       : true,
         side_effects  : true,
         negate_iife   : true
     };
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 9dd69019..1323116a 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2,7 +2,7 @@ collapse_vars_side_effects_1: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -83,7 +83,7 @@ collapse_vars_side_effects_2: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function fn(x) { return console.log(x), x; }
@@ -151,7 +151,7 @@ collapse_vars_issue_721: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true, passes:2
     }
     input: {
@@ -218,7 +218,7 @@ collapse_vars_properties: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -246,7 +246,7 @@ collapse_vars_if: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -297,7 +297,7 @@ collapse_vars_while: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:false, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -346,7 +346,7 @@ collapse_vars_do_while: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:false, loops:false, unused:"keep_assign",
-        hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true, cascade:true,
+        hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true,
         side_effects:true
     }
     input: {
@@ -422,7 +422,7 @@ collapse_vars_do_while_drop_assign: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:false, loops:false, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1(y) {
@@ -497,7 +497,7 @@ collapse_vars_seq: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         var f1 = function(x, y) {
@@ -505,20 +505,23 @@ collapse_vars_seq: {
             a = z, b = 7;
             return a + b;
         };
+        console.log(f1(1, 2));
     }
     expect: {
         var f1 = function(x, y) {
-            var a, b, r = x + y;
-            return a = r * r - r, b = 7, a + b
+            var r = x + y;
+            return r * r - r + 7;
         };
+        console.log(f1(1, 2));
     }
+    expect_stdout: "13"
 }
 
 collapse_vars_throw: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         var f1 = function(x, y) {
@@ -526,20 +529,31 @@ collapse_vars_throw: {
             a = z, b = 7;
             throw a + b;
         };
+        try {
+            f1(1, 2);
+        } catch (e) {
+            console.log(e);
+        }
     }
     expect: {
         var f1 = function(x, y) {
-            var a, b, r = x + y;
-            throw a = r * r - r, b = 7, a + b
+            var r = x + y;
+            throw r * r - r + 7;
         };
+        try {
+            f1(1, 2);
+        } catch (e) {
+            console.log(e);
+        }
     }
+    expect_stdout: "13"
 }
 
 collapse_vars_switch: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1() {
@@ -579,7 +593,7 @@ collapse_vars_assignment: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function log(x) { return console.log(x), x; }
@@ -652,7 +666,7 @@ collapse_vars_lvalues: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:"keep_assign",
-        hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true, cascade:true,
+        hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true,
         side_effects:true
     }
     input: {
@@ -685,7 +699,7 @@ collapse_vars_lvalues_drop_assign: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, passes:3
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true, passes:3
     }
     input: {
         function f0(x) { var i = ++x; return x += i; }
@@ -717,7 +731,7 @@ collapse_vars_misc1: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -765,7 +779,7 @@ collapse_vars_self_reference: {
         collapse_vars:true, unused:false,
         sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         // avoid bug in self-referential declaration.
@@ -795,7 +809,7 @@ collapse_vars_repeated: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -838,7 +852,7 @@ collapse_vars_closures: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -866,7 +880,7 @@ collapse_vars_unary: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f0(o, p) {
@@ -929,7 +943,7 @@ collapse_vars_try: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -985,7 +999,7 @@ collapse_vars_array: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1(x, y) {
@@ -1019,7 +1033,7 @@ collapse_vars_object: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f0(x, y) {
@@ -1087,7 +1101,7 @@ collapse_vars_eval_and_with: {
     options = {
         collapse_vars:true, sequences:false, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         // Don't attempt to collapse vars in presence of eval() or with statement.
@@ -1127,7 +1141,7 @@ collapse_vars_constants: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -1165,7 +1179,7 @@ collapse_vars_arguments: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true,
         toplevel:true, reduce_funcs: true, reduce_vars:true
     }
     input: {
@@ -1188,7 +1202,7 @@ collapse_vars_short_circuit: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f0(x) { var a = foo(), b = bar(); return b || x; }
@@ -1241,7 +1255,6 @@ collapse_vars_short_circuited_conditions: {
         keep_fargs:    true,
         if_return:     false,
         join_vars:     true,
-        cascade:       true,
         side_effects:  true,
     }
     input: {
@@ -1279,7 +1292,6 @@ collapse_vars_short_circuited_conditions: {
 collapse_vars_regexp: {
     options = {
         booleans:      true,
-        cascade:       true,
         collapse_vars: true,
         comparisons:   true,
         conditionals:  true,
@@ -1443,7 +1455,6 @@ issue_1605_2: {
 
 issue_1631_1: {
     options = {
-        cascade: true,
         collapse_vars: true,
         hoist_funs: true,
         join_vars: true,
@@ -1479,7 +1490,6 @@ issue_1631_1: {
 
 issue_1631_2: {
     options = {
-        cascade: true,
         collapse_vars: true,
         hoist_funs: true,
         join_vars: true,
@@ -1515,7 +1525,6 @@ issue_1631_2: {
 
 issue_1631_3: {
     options = {
-        cascade: true,
         collapse_vars: true,
         hoist_funs: true,
         join_vars: true,
@@ -1690,7 +1699,7 @@ var_defs: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         var f1 = function(x, y) {
@@ -3881,3 +3890,91 @@ recursive_function_replacement: {
         console.log(f(c));
     }
 }
+
+cascade_conditional: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f(a, b) {
+            (a = x(), a) ? a++ : (b = y(a), b(a));
+        }
+    }
+    expect: {
+        function f(a, b) {
+            (a = x()) ? a++ : (b = y(a))(a);
+        }
+    }
+}
+
+cascade_if_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        if (a = x(), a)
+            if (a == y()) z();
+    }
+    expect: {
+        var a;
+        if (a = x())
+            if (a == y()) z();
+    }
+}
+
+cascade_if_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f(a, b) {
+            if (a(), b = x()) return b;
+        }
+    }
+    expect: {
+        function f(a, b) {
+            if (a(), b = x()) return b;
+        }
+    }
+}
+
+cascade_return: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f(a) {
+            return a = x();
+            return a;
+        }
+    }
+    expect: {
+        function f(a) {
+            return a = x();
+            return a;
+        }
+    }
+}
+
+cascade_switch: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f(a, b) {
+            switch(a = x(), a) {
+              case a = x(), b(a):
+                break;
+            }
+        }
+    }
+    expect: {
+        function f(a, b) {
+            switch(a = x()) {
+              case b(a = x()):
+                break;
+            }
+        }
+    }
+}
diff --git a/test/compress/conditionals.js b/test/compress/conditionals.js
index 143ece4a..4d61d39f 100644
--- a/test/compress/conditionals.js
+++ b/test/compress/conditionals.js
@@ -649,7 +649,7 @@ ternary_boolean_consequent: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1() { return a == b ? true : x; }
@@ -677,7 +677,7 @@ ternary_boolean_alternative: {
     options = {
         collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1() { return a == b ? x : true; }
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index f9ef7877..275e0f76 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -685,7 +685,7 @@ drop_value: {
 
 issue_1539: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         sequences: true,
         side_effects: true,
         unused: true,
@@ -732,7 +732,7 @@ vardef_value: {
 
 assign_binding: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
         unused: true,
     }
@@ -1273,7 +1273,7 @@ issue_2226_1: {
 
 issue_2226_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         sequences: true,
         side_effects: true,
         unused: true,
@@ -1286,8 +1286,8 @@ issue_2226_2: {
     }
     expect: {
         console.log(function(a, b) {
-            return a += b;
-        }(1, 2));
+            return a += 2;
+        }(1));
     }
     expect_stdout: "3"
 }
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 15727fc2..7e87692d 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -21,7 +21,7 @@ iifes_returning_constants_keep_fargs_true: {
         join_vars     : true,
         reduce_funcs  : true,
         reduce_vars   : true,
-        cascade       : true,
+        collapse_vars : true,
         inline        : true,
     }
     input: {
@@ -58,7 +58,7 @@ iifes_returning_constants_keep_fargs_false: {
         join_vars     : true,
         reduce_funcs  : true,
         reduce_vars   : true,
-        cascade       : true,
+        collapse_vars : true,
         inline        : true,
     }
     input: {
@@ -423,9 +423,9 @@ inner_ref: {
 
 issue_2107: {
     options = {
-        cascade: true,
         collapse_vars: true,
         inline: true,
+        passes: 3,
         sequences: true,
         side_effects: true,
         unused: true,
diff --git a/test/compress/issue-1034.js b/test/compress/issue-1034.js
index f312408c..860a597f 100644
--- a/test/compress/issue-1034.js
+++ b/test/compress/issue-1034.js
@@ -2,7 +2,7 @@ non_hoisted_function_after_return: {
     options = {
         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
+        if_return: true, join_vars: true, side_effects: true
     }
     input: {
         function foo(x) {
@@ -38,7 +38,7 @@ non_hoisted_function_after_return_2a: {
     options = {
         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,
+        if_return: true, join_vars: true, side_effects: true,
         collapse_vars: false, passes: 2, warnings: "verbose"
     }
     input: {
@@ -85,7 +85,7 @@ non_hoisted_function_after_return_2b: {
     options = {
         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,
+        if_return: true, join_vars: true, side_effects: true,
         collapse_vars: false
     }
     input: {
@@ -123,7 +123,7 @@ non_hoisted_function_after_return_strict: {
     options = {
         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
+        if_return: true, join_vars: true, side_effects: true
     }
     input: {
         "use strict";
@@ -164,7 +164,7 @@ non_hoisted_function_after_return_2a_strict: {
     options = {
         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,
+        if_return: true, join_vars: true, side_effects: true,
         collapse_vars: false, passes: 2, warnings: "verbose"
     }
     input: {
@@ -216,7 +216,7 @@ non_hoisted_function_after_return_2b_strict: {
     options = {
         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,
+        if_return: true, join_vars: true, side_effects: true,
         collapse_vars: false
     }
     input: {
diff --git a/test/compress/issue-1105.js b/test/compress/issue-1105.js
index ea957930..151ca810 100644
--- a/test/compress/issue-1105.js
+++ b/test/compress/issue-1105.js
@@ -190,7 +190,6 @@ assorted_Infinity_NaN_undefined_in_with_scope: {
         keep_fargs:    true,
         if_return:     true,
         join_vars:     true,
-        cascade:       true,
         side_effects:  true,
         sequences:     false,
         keep_infinity: false,
@@ -253,7 +252,6 @@ assorted_Infinity_NaN_undefined_in_with_scope_keep_infinity: {
         keep_fargs:    true,
         if_return:     true,
         join_vars:     true,
-        cascade:       true,
         side_effects:  true,
         sequences:     false,
         keep_infinity: true,
diff --git a/test/compress/issue-1261.js b/test/compress/issue-1261.js
index 994a00b3..9f4f466f 100644
--- a/test/compress/issue-1261.js
+++ b/test/compress/issue-1261.js
@@ -8,7 +8,6 @@ pure_function_calls: {
         unused       : true,
         if_return    : true,
         join_vars    : true,
-        cascade      : true,
         negate_iife  : true,
     }
     input: {
@@ -49,13 +48,13 @@ pure_function_calls: {
         a.b(), f.g();
     }
     expect_warnings: [
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:17,8]",
-        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:17,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:30,37]",
-        "WARN: Dropping unused variable iife2 [test/compress/issue-1261.js:30,16]",
-        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:28,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:38,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:39,31]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:16,8]",
+        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:16,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:29,37]",
+        "WARN: Dropping unused variable iife2 [test/compress/issue-1261.js:29,16]",
+        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:27,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:37,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:38,31]",
     ]
 }
 
@@ -69,7 +68,6 @@ pure_function_calls_toplevel: {
         unused       : true,
         if_return    : true,
         join_vars    : true,
-        cascade      : true,
         negate_iife  : true,
         toplevel     : true,
     }
@@ -112,17 +110,17 @@ pure_function_calls_toplevel: {
         a.b(), f.g();
     }
     expect_warnings: [
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:79,8]",
-        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:79,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:92,37]",
-        "WARN: Dropping unused variable iife2 [test/compress/issue-1261.js:92,16]",
-        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:90,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:107,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:108,31]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:84,33]",
-        "WARN: Dropping unused variable iife1 [test/compress/issue-1261.js:84,12]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:100,45]",
-        "WARN: Dropping unused variable MyClass [test/compress/issue-1261.js:100,12]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:77,8]",
+        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:77,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:90,37]",
+        "WARN: Dropping unused variable iife2 [test/compress/issue-1261.js:90,16]",
+        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:88,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:105,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:106,31]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:82,33]",
+        "WARN: Dropping unused variable iife1 [test/compress/issue-1261.js:82,12]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:98,45]",
+        "WARN: Dropping unused variable MyClass [test/compress/issue-1261.js:98,12]",
     ]
 }
 
@@ -157,29 +155,29 @@ should_warn: {
         baz();
     }
     expect_warnings: [
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:137,61]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:137,23]",
-        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:137,23]",
-        "WARN: Boolean || always true [test/compress/issue-1261.js:138,23]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:135,61]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:135,23]",
+        "WARN: Dropping side-effect-free statement [test/compress/issue-1261.js:135,23]",
+        "WARN: Boolean || always true [test/compress/issue-1261.js:136,23]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:136,23]",
+        "WARN: Condition always true [test/compress/issue-1261.js:136,23]",
+        "WARN: Condition left of || always true [test/compress/issue-1261.js:137,8]",
+        "WARN: Condition always true [test/compress/issue-1261.js:137,8]",
+        "WARN: Boolean && always false [test/compress/issue-1261.js:138,23]",
         "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:138,23]",
-        "WARN: Condition always true [test/compress/issue-1261.js:138,23]",
-        "WARN: Condition left of || always true [test/compress/issue-1261.js:139,8]",
-        "WARN: Condition always true [test/compress/issue-1261.js:139,8]",
-        "WARN: Boolean && always false [test/compress/issue-1261.js:140,23]",
+        "WARN: Condition always false [test/compress/issue-1261.js:138,23]",
+        "WARN: Condition left of && always false [test/compress/issue-1261.js:139,8]",
+        "WARN: Condition always false [test/compress/issue-1261.js:139,8]",
+        "WARN: + in boolean context always true [test/compress/issue-1261.js:140,23]",
         "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:140,23]",
-        "WARN: Condition always false [test/compress/issue-1261.js:140,23]",
-        "WARN: Condition left of && always false [test/compress/issue-1261.js:141,8]",
-        "WARN: Condition always false [test/compress/issue-1261.js:141,8]",
-        "WARN: + in boolean context always true [test/compress/issue-1261.js:142,23]",
+        "WARN: Condition always true [test/compress/issue-1261.js:140,23]",
+        "WARN: + in boolean context always true [test/compress/issue-1261.js:141,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:141,31]",
+        "WARN: Condition always true [test/compress/issue-1261.js:141,8]",
         "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:142,23]",
-        "WARN: Condition always true [test/compress/issue-1261.js:142,23]",
-        "WARN: + in boolean context always true [test/compress/issue-1261.js:143,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:143,31]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:143,24]",
         "WARN: Condition always true [test/compress/issue-1261.js:143,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:144,23]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:145,24]",
-        "WARN: Condition always true [test/compress/issue-1261.js:145,8]",
-        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:146,31]",
-        "WARN: Condition always false [test/compress/issue-1261.js:146,8]",
+        "WARN: Dropping __PURE__ call [test/compress/issue-1261.js:144,31]",
+        "WARN: Condition always false [test/compress/issue-1261.js:144,8]",
     ]
 }
diff --git a/test/compress/issue-1275.js b/test/compress/issue-1275.js
index 5d4f5b70..2553c74f 100644
--- a/test/compress/issue-1275.js
+++ b/test/compress/issue-1275.js
@@ -9,7 +9,6 @@ string_plus_optimization: {
         unused        : true,
         if_return     : true,
         join_vars     : true,
-        cascade       : true,
         hoist_funs    : true,
     };
     input: {
diff --git a/test/compress/issue-1447.js b/test/compress/issue-1447.js
index a7f35e5a..0a765685 100644
--- a/test/compress/issue-1447.js
+++ b/test/compress/issue-1447.js
@@ -32,7 +32,6 @@ conditional_false_stray_else_in_loop: {
         hoist_vars   : true,
         join_vars    : true,
         if_return    : true,
-        cascade      : true,
         conditionals : false,
     }
     input: {
diff --git a/test/compress/issue-1639.js b/test/compress/issue-1639.js
index fc3db983..80d45a76 100644
--- a/test/compress/issue-1639.js
+++ b/test/compress/issue-1639.js
@@ -2,7 +2,7 @@
 issue_1639_1: {
     options = {
         booleans: true,
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         evaluate: true,
         join_vars: true,
@@ -35,7 +35,7 @@ issue_1639_1: {
 issue_1639_2: {
     options = {
         booleans: true,
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         evaluate: true,
         join_vars: true,
@@ -68,7 +68,7 @@ issue_1639_2: {
 issue_1639_3: {
     options = {
         booleans: true,
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         evaluate: true,
         sequences: true,
diff --git a/test/compress/issue-1656.js b/test/compress/issue-1656.js
index 27d87652..e44e2094 100644
--- a/test/compress/issue-1656.js
+++ b/test/compress/issue-1656.js
@@ -1,7 +1,6 @@
 f7: {
     options = {
         booleans: true,
-        cascade: true,
         collapse_vars: true,
         comparisons: true,
         conditionals: true,
diff --git a/test/compress/issue-281.js b/test/compress/issue-281.js
index 6a93136f..1e532dfb 100644
--- a/test/compress/issue-281.js
+++ b/test/compress/issue-281.js
@@ -453,7 +453,7 @@ pure_annotation_2: {
 
 drop_fargs: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         inline: true,
         keep_fargs: false,
         side_effects: true,
@@ -476,7 +476,7 @@ drop_fargs: {
 
 keep_fargs: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         inline: true,
         keep_fargs: true,
         side_effects: true,
diff --git a/test/compress/issue-368.js b/test/compress/issue-368.js
index 5960aa64..b0491c29 100644
--- a/test/compress/issue-368.js
+++ b/test/compress/issue-368.js
@@ -1,6 +1,6 @@
 collapse: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         sequences: true,
         side_effects: true,
         unused: true,
@@ -41,7 +41,7 @@ collapse: {
             return void 0 !== ('function' === typeof b ? b() : b) && c();
         }
         function f2(b) {
-            return b = c(), 'stirng' == typeof ('function' === typeof b ? b() : b) && d();
+            return 'stirng' == typeof ('function' === typeof (b = c()) ? b() : b) && d();
         }
         function f3(c) {
             var a;
diff --git a/test/compress/issue-892.js b/test/compress/issue-892.js
index b6938c42..81df1cab 100644
--- a/test/compress/issue-892.js
+++ b/test/compress/issue-892.js
@@ -18,7 +18,6 @@ dont_mangle_arguments: {
         hoist_vars    : true,
         if_return     : true,
         join_vars     : true,
-        cascade       : true,
         side_effects  : true,
         negate_iife   : false
     };
diff --git a/test/compress/issue-976.js b/test/compress/issue-976.js
index b711051b..54d7dad5 100644
--- a/test/compress/issue-976.js
+++ b/test/compress/issue-976.js
@@ -2,7 +2,7 @@ eval_collapse_vars: {
     options = {
         collapse_vars:true, sequences:false, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     };
     input: {
         function f1() {
diff --git a/test/compress/issue-979.js b/test/compress/issue-979.js
index 7ed5801d..b2500126 100644
--- a/test/compress/issue-979.js
+++ b/test/compress/issue-979.js
@@ -2,7 +2,7 @@ issue979_reported: {
     options = {
         sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f1() {
@@ -32,7 +32,7 @@ issue979_test_negated_is_best: {
     options = {
         sequences:true, properties:true, dead_code:true, conditionals:true,
         comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
-        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+        keep_fargs:true, if_return:true, join_vars:true, side_effects:true
     }
     input: {
         function f3() {
diff --git a/test/compress/pure_getters.js b/test/compress/pure_getters.js
index 5c16b2cd..4174bc1b 100644
--- a/test/compress/pure_getters.js
+++ b/test/compress/pure_getters.js
@@ -185,7 +185,7 @@ impure_getter_2: {
 
 issue_2110_1: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         pure_getters: "strict",
         sequences: true,
         side_effects: true,
@@ -274,7 +274,7 @@ set_immutable_1: {
 
 set_immutable_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         pure_getters: "strict",
         reduce_funcs: true,
@@ -324,7 +324,7 @@ set_immutable_3: {
 
 set_immutable_4: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         pure_getters: "strict",
         reduce_funcs: true,
@@ -375,7 +375,7 @@ set_mutable_1: {
 
 set_mutable_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         pure_getters: "strict",
         reduce_funcs: true,
@@ -400,7 +400,7 @@ set_mutable_2: {
 
 issue_2313_1: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         pure_getters: "strict",
         sequences: true,
@@ -446,7 +446,7 @@ issue_2313_1: {
 
 issue_2313_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         pure_getters: true,
         sequences: true,
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 6c8bd639..504ce6f0 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -2262,7 +2262,7 @@ redefine_farg_2: {
 
 redefine_farg_3: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         evaluate: true,
         inline: true,
         keep_fargs: false,
diff --git a/test/compress/return_undefined.js b/test/compress/return_undefined.js
index 4d2b4257..c7e09067 100644
--- a/test/compress/return_undefined.js
+++ b/test/compress/return_undefined.js
@@ -17,7 +17,6 @@ return_undefined: {
         keep_fnames   : false,
         hoist_vars    : true,
         join_vars     : true,
-        cascade       : true,
         negate_iife   : true
     };
     input: {
diff --git a/test/compress/sequences.js b/test/compress/sequences.js
index 26f38c25..81b06881 100644
--- a/test/compress/sequences.js
+++ b/test/compress/sequences.js
@@ -317,7 +317,7 @@ unsafe_undefined: {
 
 issue_1685: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -341,7 +341,7 @@ issue_1685: {
 
 func_def_1: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -361,7 +361,7 @@ func_def_1: {
 
 func_def_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -379,7 +379,7 @@ func_def_2: {
 
 func_def_3: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -401,7 +401,7 @@ func_def_3: {
 
 func_def_4: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -427,7 +427,7 @@ func_def_4: {
 
 func_def_5: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -634,7 +634,7 @@ side_effects: {
 
 side_effects_cascade_1: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         sequences: true,
         side_effects: true,
@@ -655,7 +655,7 @@ side_effects_cascade_1: {
 
 side_effects_cascade_2: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         side_effects: true,
     }
     input: {
@@ -677,7 +677,7 @@ side_effects_cascade_2: {
 
 side_effects_cascade_3: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         side_effects: true,
     }
@@ -692,14 +692,14 @@ side_effects_cascade_3: {
     expect: {
         function f(a, b) {
             !(b += a) && ((b = a) || (b -= a, b ^= a)),
-            --a;
+            a--;
         }
     }
 }
 
 issue_27: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         passes: 2,
         sequences: true,
         side_effects: true,
@@ -722,7 +722,7 @@ issue_27: {
 issue_2062: {
     options = {
         booleans: true,
-        cascade: true,
+        collapse_vars: true,
         conditionals: true,
         side_effects: true,
     }
@@ -741,7 +741,7 @@ issue_2062: {
 
 issue_2313: {
     options = {
-        cascade: true,
+        collapse_vars: true,
         sequences: true,
         side_effects: true,
     }
@@ -779,3 +779,20 @@ issue_2313: {
     }
     expect_stdout: "2 1"
 }
+
+cascade_assignment_in_return: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        function f(a, b) {
+            return a = x(), b(a);
+        }
+    }
+    expect: {
+        function f(a, b) {
+            return b(x());
+        }
+    }
+}