feat(es/minifier): Drop expressions using sequential inliner (#6936)

kdy1 · web-flow · commit 246300ae25be · 2023-04-29T22:19:00.000+09:00
diff --git a/crates/swc/tests/tsc-references/ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.2.minified.js b/crates/swc/tests/tsc-references/ClassAndModuleThatMergeWithStaticFunctionAndNonExportedFunctionThatShareAName.2.minified.js
@@ -25,5 +25,5 @@ Point || (Point = {}), function(A) {
             };
         }, Point;
     }();
-    A.Point = Point, Point = A.Point || (A.Point = {});
+    A.Point = Point, A.Point || (A.Point = {});
 }(A || (A = {}));
diff --git a/crates/swc/tests/tsc-references/assignAnyToEveryType.2.minified.js b/crates/swc/tests/tsc-references/assignAnyToEveryType.2.minified.js
@@ -1,6 +1,6 @@
 //// [assignAnyToEveryType.ts]
-var x, E, M;
+var E, M;
 import "@swc/helpers/_/_class_call_check";
 !function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), E.A, (M || (M = {})).foo = 1, M = x;
+}(E || (E = {})), E.A, (M || (M = {})).foo = 1;
diff --git a/crates/swc/tests/tsc-references/assignFromBooleanInterface2.2.minified.js b/crates/swc/tests/tsc-references/assignFromBooleanInterface2.2.minified.js
@@ -1,3 +1,3 @@
 //// [assignFromBooleanInterface2.ts]
 var a, b, x = !0;
-a = !0, b = a = b, b = x, x = a, x = b;
+a = !0, b = a = b, b = x, x = a;
diff --git a/crates/swc/tests/tsc-references/assignFromNumberInterface2.2.minified.js b/crates/swc/tests/tsc-references/assignFromNumberInterface2.2.minified.js
@@ -1,3 +1,3 @@
 //// [assignFromNumberInterface2.ts]
 var a, b, x = 1;
-a = 1, b = a = b, b = x, x = a, x = b;
+a = 1, b = a = b, b = x, x = a;
diff --git a/crates/swc/tests/tsc-references/assignFromStringInterface2.2.minified.js b/crates/swc/tests/tsc-references/assignFromStringInterface2.2.minified.js
@@ -1,3 +1,3 @@
 //// [assignFromStringInterface2.ts]
 var a, b, x = "";
-a = x, b = a = b, b = x, x = a, x = b;
+a = x, b = a = b, b = x, x = a;
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithCallSignatures6.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithCallSignatures6.2.minified.js
@@ -3,4 +3,4 @@ var x, b, b2, b3, b4, b5, b11, b16;
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
 import { _ as _inherits } from "@swc/helpers/_/_inherits";
 import { _ as _create_super } from "@swc/helpers/_/_create_super";
-x.a = b, b = x.a, x.a2 = b2, b2 = x.a2, x.a3 = b3, b3 = x.a3, x.a4 = b4, b4 = x.a4, x.a5 = b5, b5 = x.a5, x.a11 = b11, b11 = x.a11, x.a16 = b16, b16 = x.a16;
+x.a = b, b = x.a, x.a2 = b2, b2 = x.a2, x.a3 = b3, b3 = x.a3, x.a4 = b4, b4 = x.a4, x.a5 = b5, b5 = x.a5, x.a11 = b11, b11 = x.a11, x.a16 = b16, x.a16;
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithConstructSignatures6.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithConstructSignatures6.2.minified.js
@@ -3,4 +3,4 @@ var x, b, b2, b3, b4, b5, b11, b16;
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
 import { _ as _inherits } from "@swc/helpers/_/_inherits";
 import { _ as _create_super } from "@swc/helpers/_/_create_super";
-x.a = b, b = x.a, x.a2 = b2, b2 = x.a2, x.a3 = b3, b3 = x.a3, x.a4 = b4, b4 = x.a4, x.a5 = b5, b5 = x.a5, x.a11 = b11, b11 = x.a11, x.a16 = b16, b16 = x.a16;
+x.a = b, b = x.a, x.a2 = b2, b2 = x.a2, x.a3 = b3, b3 = x.a3, x.a4 = b4, b4 = x.a4, x.a5 = b5, b5 = x.a5, x.a11 = b11, b11 = x.a11, x.a16 = b16, x.a16;
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithDiscriminatedUnion.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithDiscriminatedUnion.2.minified.js
@@ -1,12 +1,6 @@
 //// [assignmentCompatWithDiscriminatedUnion.ts]
 var Example1, Example2, Example3, Example4, Example5, GH14865, GH30170, GH12052, GH18421, GH15907, GH20889, GH39357;
-Example1 || (Example1 = {}), t = s, Example2 || (Example2 = {}), t = s, Example3 || (Example3 = {}), t = s, Example4 || (Example4 = {}), t = s, Example5 || (Example5 = {}), t = s, function(GH14865) {
-    var b1, a = {
-        type: "A",
-        data: "whatevs"
-    };
-    a.type, b1.type, b1 = a;
-}(GH14865 || (GH14865 = {})), GH30170 || (GH30170 = {}), function(GH12052) {
+Example1 || (Example1 = {}), t = s, Example2 || (Example2 = {}), t = s, Example3 || (Example3 = {}), t = s, Example4 || (Example4 = {}), t = s, Example5 || (Example5 = {}), t = s, GH14865 || (GH14865 = {}), (void 0).type, GH30170 || (GH30170 = {}), function(GH12052) {
     var getAxisType = function() {
         return "categorical";
     };
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembers.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembers.2.minified.js
@@ -2,10 +2,10 @@
 var SimpleTypes, ObjectTypes;
 import "@swc/helpers/_/_class_call_check";
 SimpleTypes || (SimpleTypes = {}), function(ObjectTypes) {
-    var t, t2, b, a2 = {
+    var t2, b, a2 = {
         foo: a2
     }, b2 = {
         foo: b2
     };
-    b2 = a2 = b2, a2 = b, a2 = t2, a2 = t;
+    b2 = a2 = b2, a2 = b, a2 = t2;
 }(ObjectTypes || (ObjectTypes = {}));
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembersOptionality.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembersOptionality.2.minified.js
@@ -6,10 +6,4 @@ var TargetHasOptional, SourceHasOptional, Base = function Base() {
     "use strict";
     _class_call_check(this, Base);
 };
-!function(TargetHasOptional) {
-    var c, a, d, e, f;
-    new Base(), c = d, c = e, c = f, c = a, a = d, a = e, a = f, a = c;
-}(TargetHasOptional || (TargetHasOptional = {})), function(SourceHasOptional) {
-    var c, a, d, e, f;
-    new Base(), c = d, c = e, c = f, c = a, a = d, a = e, a = f, a = c;
-}(SourceHasOptional || (SourceHasOptional = {}));
+TargetHasOptional || (TargetHasOptional = {}), new Base(), SourceHasOptional || (SourceHasOptional = {}), new Base();
diff --git a/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembersOptionality2.2.minified.js b/crates/swc/tests/tsc-references/assignmentCompatWithObjectMembersOptionality2.2.minified.js
@@ -6,7 +6,4 @@ var TargetHasOptional, SourceHasOptional, Base = function Base() {
     "use strict";
     _class_call_check(this, Base);
 };
-TargetHasOptional || (TargetHasOptional = {}), new Base(), function(SourceHasOptional) {
-    var c, a, d, e, f;
-    new Base(), c = d, c = e, c = f, c = a, a = d, a = e, a = f, a = c;
-}(SourceHasOptional || (SourceHasOptional = {}));
+TargetHasOptional || (TargetHasOptional = {}), new Base(), SourceHasOptional || (SourceHasOptional = {}), new Base();
diff --git a/crates/swc/tests/tsc-references/assignmentToParenthesizedIdentifiers.2.minified.js b/crates/swc/tests/tsc-references/assignmentToParenthesizedIdentifiers.2.minified.js
@@ -25,4 +25,4 @@ import "@swc/helpers/_/_class_call_check";
     x: ""
 }, function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), E = void 0, E = void 0;
+}(E || (E = {}));
diff --git a/crates/swc/tests/tsc-references/emitCompoundExponentiationOperator1.2.minified.js b/crates/swc/tests/tsc-references/emitCompoundExponentiationOperator1.2.minified.js
@@ -1,3 +1 @@
 //// [emitCompoundExponentiationOperator1.ts]
-var comp;
-comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp, 1), Math.pow(comp, comp)), Math.pow(comp, Math.pow(comp, 2))), Math.pow(comp, comp) + 2), Math.pow(comp, comp) - 2), 2 * Math.pow(comp, comp)), Math.pow(comp, comp) / 2), Math.pow(comp, comp) % 2), Math.pow(comp - 2, 5)), Math.pow(comp + 2, 5)), Math.pow(2 * comp, 5)), Math.pow(comp / 2, 5)), Math.pow(comp % 2, 5)), Math.pow(comp, 7)), Math.pow(comp, 3)), Math.pow(comp, 10)), Math.pow(comp, 2.5)), Math.pow(comp, 1));
diff --git a/crates/swc/tests/tsc-references/emitCompoundExponentiationOperator2.2.minified.js b/crates/swc/tests/tsc-references/emitCompoundExponentiationOperator2.2.minified.js
@@ -1,3 +1 @@
 //// [emitCompoundExponentiationOperator2.ts]
-var comp;
-comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp = Math.pow(comp, 1), comp = Math.pow(comp, 1)), comp = Math.pow(comp, 3)), comp = Math.pow(comp, -1)), comp = Math.pow(comp, 2)), comp = Math.pow(comp, 0.5)), comp = Math.pow(comp, 3)), comp = Math.pow(comp, -1)), comp = Math.pow(comp, 2)), comp = Math.pow(comp, 0.5)), comp = Math.pow(comp, 9)), comp = Math.pow(comp, -15)), comp = Math.pow(comp, 32)), comp = Math.pow(comp, 0.015625)), comp = Math.pow(comp, 27)), comp = Math.pow(comp, 1)), comp = Math.pow(comp, 32)), comp = Math.pow(comp, 0.015625));
diff --git a/crates/swc/tests/tsc-references/intersectionAndUnionTypes.2.minified.js b/crates/swc/tests/tsc-references/intersectionAndUnionTypes.2.minified.js
@@ -1,3 +1,3 @@
 //// [intersectionAndUnionTypes.ts]
 var a, b, anb, aob, cnd, cod, x, y;
-a = anb, b = anb, anb = a, x = anb = b, x = aob, x = cnd, anb = x = cod, aob = x, cnd = x, cod = x, y = anb, y = aob, y = cnd, anb = y = cod, aob = y, cnd = y, cod = y;
+a = anb, b = anb, anb = a, x = anb = b, x = aob, x = cnd, anb = x = cod, aob = x, cnd = x, cod = x, y = anb, y = aob, y = cnd, anb = y = cod, aob = y, cnd = y;
diff --git a/crates/swc/tests/tsc-references/intersectionTypeAssignment.2.minified.js b/crates/swc/tests/tsc-references/intersectionTypeAssignment.2.minified.js
@@ -1,3 +1,3 @@
 //// [intersectionTypeAssignment.ts]
-var a, b, x, y;
-a = x, x = a = y, y = a, b = x, x = b = y, y = x = y = b;
+var a, x, y;
+a = x, x = a = y, x = y = a;
diff --git a/crates/swc/tests/tsc-references/invalidBooleanAssignments.2.minified.js b/crates/swc/tests/tsc-references/invalidBooleanAssignments.2.minified.js
@@ -3,4 +3,4 @@ var E, M;
 import "@swc/helpers/_/_class_call_check";
 !function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), (M || (M = {})).a = 1, M = !0;
+}(E || (E = {})), (M || (M = {})).a = 1;
diff --git a/crates/swc/tests/tsc-references/invalidNumberAssignments.2.minified.js b/crates/swc/tests/tsc-references/invalidNumberAssignments.2.minified.js
@@ -1,4 +1,4 @@
 //// [invalidNumberAssignments.ts]
 var M;
 import "@swc/helpers/_/_class_call_check";
-(M || (M = {})).x = 1, M = 1;
+(M || (M = {})).x = 1;
diff --git a/crates/swc/tests/tsc-references/invalidUndefinedAssignments.2.minified.js b/crates/swc/tests/tsc-references/invalidUndefinedAssignments.2.minified.js
@@ -3,4 +3,4 @@ var x, E, M;
 import "@swc/helpers/_/_class_call_check";
 !function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), (E = x).A = x, I = x, (M || (M = {})).x = 1, M = x;
+}(E || (E = {})), (E = x).A = x, I = x, (M || (M = {})).x = 1;
diff --git a/crates/swc/tests/tsc-references/invalidVoidAssignments.2.minified.js b/crates/swc/tests/tsc-references/invalidVoidAssignments.2.minified.js
@@ -3,6 +3,4 @@ var x, M, E;
 import "@swc/helpers/_/_class_call_check";
 (M || (M = {})).x = 1, M = x, function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), x = E, x = E.A, x = {
-    f: function() {}
-};
+}(E || (E = {})), x = E, x = E.A;
diff --git a/crates/swc/tests/tsc-references/literalTypes2.2.minified.js b/crates/swc/tests/tsc-references/literalTypes2.2.minified.js
@@ -14,11 +14,8 @@ g1(1), g2(1, 1), g2(1, 2), g3(1, "two"), g4(1), g5(1, 2), g6([
     return x;
 }), g8(1, function(x) {
     return x + 1;
-});
-var aa = [
+}), function(a, x) {
+    a.slice().push(1);
+}([
     0
-];
-aa = function(a, x) {
-    var result = a.slice();
-    return result.push(1), result;
-}(aa, 0);
+], 0);
diff --git a/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js b/crates/swc/tests/tsc-references/nonPrimitiveAssignError.2.minified.js
@@ -4,4 +4,4 @@ var a, x = {}, y = {
 };
 x = a, y = a, a = x, a = y;
 var s = "fooo";
-a = 123, a = !0, s = a = s, a = 123, a = !0, a = "string";
+a = 123, a = !0, s = a = s;
diff --git a/crates/swc/tests/tsc-references/recursiveIntersectionTypes.2.minified.js b/crates/swc/tests/tsc-references/recursiveIntersectionTypes.2.minified.js
@@ -1,3 +1,3 @@
 //// [recursiveIntersectionTypes.ts]
-var entityList, productList;
-entityList.name, entityList.next.name, entityList.next.next.name, entityList.next.next.next.name, productList = entityList = productList;
+var entityList;
+entityList.name, entityList.next.name, entityList.next.next.name, entityList.next.next.next.name;
diff --git a/crates/swc/tests/tsc-references/strictTupleLength.2.minified.js b/crates/swc/tests/tsc-references/strictTupleLength.2.minified.js
@@ -1,4 +1,3 @@
 //// [strictTupleLength.ts]
 t0.length, t1.length, t2.length, arr.length;
 var t0, t2, arr, t1 = t2, t2 = t1;
-arr = t1 = arr;
diff --git a/crates/swc/tests/tsc-references/stringLiteralTypeAssertion01.2.minified.js b/crates/swc/tests/tsc-references/stringLiteralTypeAssertion01.2.minified.js
@@ -1,3 +1,3 @@
 //// [stringLiteralTypeAssertion01.ts]
 var s, t, str;
-s = t, s = t, s = str, t = s = str, t = s, t = str, t = str, str = s, str = s, str = t, str = t;
+s = t, s = t, s = str, t = s = str, t = s, t = str, t = str, str = s, str = s, str = t;
diff --git a/crates/swc/tests/tsc-references/typeArgumentsWithStringLiteralTypes01.2.minified.js b/crates/swc/tests/tsc-references/typeArgumentsWithStringLiteralTypes01.2.minified.js
@@ -12,11 +12,11 @@ function fun3() {
 }
 !function(n1) {
     var a = n1.a = fun1("Hello", "World"), b = n1.b = fun1("Hello", "Hello"), c = n1.c = fun2("Hello", "World"), d = n1.d = fun2("Hello", "Hello"), e = n1.e = fun3("Hello", "Hello", "World", "Foo");
-    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), e = takeReturnHelloWorld(e);
+    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), takeReturnHelloWorld(e);
 }(n1 || (n1 = {})), function(n2) {
     var a = n2.a = fun1("Hello", "Hello"), b = n2.b = fun1("Hello", "World"), c = n2.c = fun2("Hello", "Hello"), d = n2.d = fun2("Hello", "World"), e = n2.e = fun3("Hello", "World");
-    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), e = takeReturnHelloWorld(e);
+    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), takeReturnHelloWorld(e);
 }(n2 || (n2 = {})), function(n3) {
     var a = n3.a = fun2("Hello", "World"), b = n3.b = fun2("World", "Hello"), c = n3.c = fun2("Hello", "Hello"), d = n3.d = fun2("World", "World"), e = n3.e = fun3("Hello", "World");
-    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), e = takeReturnHelloWorld(e);
+    a = takeReturnString(a), b = takeReturnString(b), c = takeReturnString(c), d = takeReturnString(d), e = takeReturnString(e), a = takeReturnHello(a), b = takeReturnHello(b), c = takeReturnHello(c), d = takeReturnHello(d), e = takeReturnHello(e), a = takeReturnHelloWorld(a), b = takeReturnHelloWorld(b), c = takeReturnHelloWorld(c), d = takeReturnHelloWorld(d), takeReturnHelloWorld(e);
 }(n3 || (n3 = {}));
diff --git a/crates/swc/tests/tsc-references/typeGuardsInFunction.2.minified.js b/crates/swc/tests/tsc-references/typeGuardsInFunction.2.minified.js
@@ -1,3 +1 @@
 //// [typeGuardsInFunction.ts]
-var strOrNum;
-strOrNum = "string" == typeof strOrNum && strOrNum;
diff --git a/crates/swc/tests/tsc-references/unionTypesAssignability.2.minified.js b/crates/swc/tests/tsc-references/unionTypesAssignability.2.minified.js
@@ -1,6 +1,6 @@
 //// [unionTypesAssignability.ts]
-var unionNumberString, unionDE, num, str, c, d, e, anyVar;
+var unionNumberString, unionDE, num, str, c, d, e;
 import { _ as _class_call_check } from "@swc/helpers/_/_class_call_check";
 import { _ as _inherits } from "@swc/helpers/_/_inherits";
 import { _ as _create_super } from "@swc/helpers/_/_create_super";
-c = d, c = e, c = unionDE, d = e, e = d = unionDE, e = unionDE, num = str, str = num = unionNumberString, str = unionNumberString, d = c, e = c, unionDE = c, e = d, unionDE = d, d = e, unionDE = e, str = num, unionNumberString = num, num = str, unionNumberString = str, anyVar = unionDE, unionDE = anyVar = unionNumberString, unionNumberString = anyVar, unionDE = null, unionNumberString = null, unionDE = void 0, unionNumberString = void 0;
+c = d, c = e, c = unionDE, d = e, e = d = unionDE, e = unionDE, num = str, str = num = unionNumberString, str = unionNumberString, d = c, e = c, unionDE = c, e = d, unionDE = d, d = e, unionDE = e, str = num, unionNumberString = num, num = str;
diff --git a/crates/swc/tests/tsc-references/validEnumAssignments.2.minified.js b/crates/swc/tests/tsc-references/validEnumAssignments.2.minified.js
@@ -1,5 +1,5 @@
 //// [validEnumAssignments.ts]
-var E, n, e;
+var E;
 !function(E) {
     E[E.A = 0] = "A", E[E.B = 1] = "B";
-}(E || (E = {})), n = e, n = E.A, E.A, e = E.A, e = E.B, e = n, e = null, e = void 0, e = 1, e = 1., e = 1.0, e = -1;
+}(E || (E = {})), E.A, E.A, E.A, E.B;
diff --git a/crates/swc/tests/tsc-references/validNullAssignments.2.minified.js b/crates/swc/tests/tsc-references/validNullAssignments.2.minified.js
@@ -3,4 +3,4 @@ var E, M;
 import "@swc/helpers/_/_class_call_check";
 !function(E) {
     E[E.A = 0] = "A";
-}(E || (E = {})), E.A = null, I = null, (M || (M = {})).x = 1, M = null;
+}(E || (E = {})), E.A = null, I = null, (M || (M = {})).x = 1;
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs b/crates/swc_ecma_minifier/src/compress/optimize/dead_code.rs
@@ -33,18 +33,21 @@ where
     ///     throw x();
     /// }
     /// ```
-    pub(super) fn optimize_in_fn_termination(&mut self, e: &mut Expr) {
+    /// # Returns
+    ///
+    /// returns true if `e` is changed.
+    pub(super) fn optimize_last_expr_before_termination(&mut self, e: &mut Expr) -> bool {
         if !self.options.dead_code {
-            return;
+            return false;
         }
 
         // A return statement in a try block may not terminate function.
         if self.ctx.in_try_block {
-            return;
+            return false;
         }
 
         if let Expr::Assign(assign @ AssignExpr { op: op!("="), .. }) = e {
-            self.optimize_in_fn_termination(&mut assign.right);
+            self.optimize_last_expr_before_termination(&mut assign.right);
 
             // We only handle identifiers on lhs for now.
             if let Some(lhs) = assign.left.as_ident() {
@@ -53,7 +56,7 @@ where
                     .data
                     .vars
                     .get(&lhs.to_id())
-                    .map(|var| var.is_fn_local && !var.declared_as_fn_param)
+                    .map(|var| var.declared && var.is_fn_local && !var.declared_as_fn_param)
                     .unwrap_or(false)
                 {
                     report_change!(
@@ -62,7 +65,7 @@ where
                     );
                     self.changed = true;
                     *e = *assign.right.take();
-                    return;
+                    return true;
                 }
             }
         }
@@ -76,7 +79,7 @@ where
                         .data
                         .vars
                         .get(&lhs.to_id())
-                        .map(|var| var.is_fn_local)
+                        .map(|var| var.declared && var.is_fn_local)
                         .unwrap_or(false)
                     {
                         report_change!(
@@ -91,9 +94,12 @@ where
                             left: Box::new(Expr::Ident(lhs.clone())),
                             right: assign.right.take(),
                         });
+                        return true;
                     }
                 }
             }
         }
+
+        false
     }
 }
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/mod.rs b/crates/swc_ecma_minifier/src/compress/optimize/mod.rs
diff --git a/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs b/crates/swc_ecma_minifier/src/compress/optimize/sequences.rs
diff --git a/crates/swc_ecma_minifier/tests/fixture/check/1/input.js b/crates/swc_ecma_minifier/tests/fixture/check/1/input.js
diff --git a/crates/swc_ecma_minifier/tests/fixture/check/1/output.js b/crates/swc_ecma_minifier/tests/fixture/check/1/output.js
diff --git a/crates/swc_ecma_minifier/tests/fixture/check/config.json b/crates/swc_ecma_minifier/tests/fixture/check/config.json
diff --git a/crates/swc_ecma_minifier/tests/fixture/next/react-pdf-renderer/output.js b/crates/swc_ecma_minifier/tests/fixture/next/react-pdf-renderer/output.js
diff --git a/crates/swc_ecma_minifier/tests/fixture/next/syncfusion/933-e9f9a6bf671b96fc/output.js b/crates/swc_ecma_minifier/tests/fixture/next/syncfusion/933-e9f9a6bf671b96fc/output.js
diff --git a/crates/swc_ecma_minifier/tests/fixture/projects/jquery/11/output.js b/crates/swc_ecma_minifier/tests/fixture/projects/jquery/11/output.js
diff --git a/crates/swc_ecma_minifier/tests/projects/output/jquery-1.9.1.js b/crates/swc_ecma_minifier/tests/projects/output/jquery-1.9.1.js
diff --git a/crates/swc_ecma_minifier/tests/projects/output/mootools-1.4.5.js b/crates/swc_ecma_minifier/tests/projects/output/mootools-1.4.5.js

Benchmark suite	Current: `246300a`	Previous: `d6999ba`	Ratio
`es/full/bugs-1`	`298449` ns/iter (`± 6446`)	`316389` ns/iter (`± 5780`)	`0.94`
`es/full/minify/libraries/antd`	`1567754974` ns/iter (`± 20695035`)	`1704885067` ns/iter (`± 26001291`)	`0.92`
`es/full/minify/libraries/d3`	`283250223` ns/iter (`± 7675151`)	`324982645` ns/iter (`± 5913173`)	`0.87`
`es/full/minify/libraries/echarts`	`1192440599` ns/iter (`± 8950670`)	`1295721446` ns/iter (`± 16201335`)	`0.92`
`es/full/minify/libraries/jquery`	`89078660` ns/iter (`± 374179`)	`92554463` ns/iter (`± 1432359`)	`0.96`
`es/full/minify/libraries/lodash`	`104551458` ns/iter (`± 423722`)	`107132776` ns/iter (`± 786595`)	`0.98`
`es/full/minify/libraries/moment`	`51412568` ns/iter (`± 403891`)	`52885098` ns/iter (`± 441972`)	`0.97`
`es/full/minify/libraries/react`	`18806288` ns/iter (`± 80523`)	`19457833` ns/iter (`± 219008`)	`0.97`
`es/full/minify/libraries/terser`	`236610316` ns/iter (`± 1717219`)	`257819514` ns/iter (`± 6422488`)	`0.92`
`es/full/minify/libraries/three`	`420313813` ns/iter (`± 3923666`)	`468373202` ns/iter (`± 10892594`)	`0.90`
`es/full/minify/libraries/typescript`	`3015405387` ns/iter (`± 22961798`)	`3137869150` ns/iter (`± 34701667`)	`0.96`
`es/full/minify/libraries/victory`	`636969280` ns/iter (`± 6174638`)	`699327938` ns/iter (`± 22239937`)	`0.91`
`es/full/minify/libraries/vue`	`127661073` ns/iter (`± 965296`)	`133699586` ns/iter (`± 2518690`)	`0.95`
`es/full/codegen/es3`	`28775` ns/iter (`± 69`)	`28744` ns/iter (`± 321`)	`1.00`
`es/full/codegen/es5`	`28832` ns/iter (`± 61`)	`28883` ns/iter (`± 61`)	`1.00`
`es/full/codegen/es2015`	`28865` ns/iter (`± 202`)	`28806` ns/iter (`± 51`)	`1.00`
`es/full/codegen/es2016`	`28841` ns/iter (`± 69`)	`28807` ns/iter (`± 55`)	`1.00`
`es/full/codegen/es2017`	`28799` ns/iter (`± 127`)	`28840` ns/iter (`± 61`)	`1.00`
`es/full/codegen/es2018`	`28655` ns/iter (`± 145`)	`28828` ns/iter (`± 63`)	`0.99`
`es/full/codegen/es2019`	`28627` ns/iter (`± 135`)	`28844` ns/iter (`± 22`)	`0.99`
`es/full/codegen/es2020`	`28557` ns/iter (`± 72`)	`28839` ns/iter (`± 51`)	`0.99`
`es/full/all/es3`	`181893425` ns/iter (`± 4744324`)	`179514646` ns/iter (`± 2816185`)	`1.01`
`es/full/all/es5`	`174336938` ns/iter (`± 2489280`)	`171491479` ns/iter (`± 3257673`)	`1.02`
`es/full/all/es2015`	`137858379` ns/iter (`± 1929951`)	`135821412` ns/iter (`± 2131973`)	`1.01`
`es/full/all/es2016`	`134664906` ns/iter (`± 1166683`)	`133920688` ns/iter (`± 1119953`)	`1.01`
`es/full/all/es2017`	`133662887` ns/iter (`± 1777677`)	`131599294` ns/iter (`± 1218080`)	`1.02`
`es/full/all/es2018`	`128682297` ns/iter (`± 2481131`)	`127370781` ns/iter (`± 1358835`)	`1.01`
`es/full/all/es2019`	`125293323` ns/iter (`± 1689891`)	`126116442` ns/iter (`± 1091852`)	`0.99`
`es/full/all/es2020`	`118497045` ns/iter (`± 1106031`)	`119108675` ns/iter (`± 1185203`)	`0.99`
`es/full/parser`	`514355` ns/iter (`± 7492`)	`519528` ns/iter (`± 7959`)	`0.99`
`es/full/base/fixer`	`22659` ns/iter (`± 85`)	`22642` ns/iter (`± 50`)	`1.00`
`es/full/base/resolver_and_hygiene`	`86171` ns/iter (`± 271`)	`85483` ns/iter (`± 77`)	`1.01`
`serialization of serde`	`120` ns/iter (`± 0`)	`122` ns/iter (`± 0`)	`0.98`
`css/minify/libraries/bootstrap`	`27123762` ns/iter (`± 86008`)	`27882567` ns/iter (`± 179369`)	`0.97`
`css/visitor/compare/clone`	`2096845` ns/iter (`± 9150`)	`2127321` ns/iter (`± 18562`)	`0.99`
`css/visitor/compare/visit_mut_span`	`2251163` ns/iter (`± 8429`)	`2300681` ns/iter (`± 14850`)	`0.98`
`css/visitor/compare/visit_mut_span_panic`	`2333928` ns/iter (`± 9279`)	`2354526` ns/iter (`± 13361`)	`0.99`
`css/visitor/compare/fold_span`	`3040704` ns/iter (`± 7662`)	`3071831` ns/iter (`± 20626`)	`0.99`
`css/visitor/compare/fold_span_panic`	`3191977` ns/iter (`± 10725`)	`3236761` ns/iter (`± 48374`)	`0.99`
`css/lexer/bootstrap_5_1_3`	`5145179` ns/iter (`± 13565`)	`5211714` ns/iter (`± 65391`)	`0.99`
`css/lexer/foundation_6_7_4`	`4334948` ns/iter (`± 12190`)	`4364090` ns/iter (`± 1772`)	`0.99`
`css/lexer/tailwind_3_1_1`	`819496` ns/iter (`± 2369`)	`824146` ns/iter (`± 365`)	`0.99`
`css/parser/bootstrap_5_1_3`	`20845446` ns/iter (`± 104505`)	`21312420` ns/iter (`± 173640`)	`0.98`
`css/parser/foundation_6_7_4`	`16671333` ns/iter (`± 61007`)	`16942648` ns/iter (`± 81615`)	`0.98`
`css/parser/tailwind_3_1_1`	`3211544` ns/iter (`± 7099`)	`3229576` ns/iter (`± 5824`)	`0.99`
`es/codegen/colors`	`321849` ns/iter (`± 184729`)	`327665` ns/iter (`± 185570`)	`0.98`
`es/codegen/large`	`1250290` ns/iter (`± 642413`)	`1282978` ns/iter (`± 655223`)	`0.97`
`es/codegen/with-parser/colors`	`47594` ns/iter (`± 418`)	`47468` ns/iter (`± 361`)	`1.00`
`es/codegen/with-parser/large`	`507919` ns/iter (`± 2573`)	`513921` ns/iter (`± 1173`)	`0.99`
`es/minify/libraries/antd`	`1364978213` ns/iter (`± 12483184`)	`1465606205` ns/iter (`± 20270224`)	`0.93`
`es/minify/libraries/d3`	`243145402` ns/iter (`± 1325530`)	`265213580` ns/iter (`± 4046003`)	`0.92`
`es/minify/libraries/echarts`	`1032614119` ns/iter (`± 9261018`)	`1113557227` ns/iter (`± 13241023`)	`0.93`
`es/minify/libraries/jquery`	`77423137` ns/iter (`± 508444`)	`80835367` ns/iter (`± 727647`)	`0.96`
`es/minify/libraries/lodash`	`93053414` ns/iter (`± 609981`)	`96642643` ns/iter (`± 831777`)	`0.96`
`es/minify/libraries/moment`	`45055336` ns/iter (`± 196189`)	`46545036` ns/iter (`± 776391`)	`0.97`
`es/minify/libraries/react`	`16934012` ns/iter (`± 92594`)	`17425541` ns/iter (`± 207001`)	`0.97`
`es/minify/libraries/terser`	`203711668` ns/iter (`± 2340352`)	`222328247` ns/iter (`± 4129450`)	`0.92`
`es/minify/libraries/three`	`344627477` ns/iter (`± 3101184`)	`383249421` ns/iter (`± 5942123`)	`0.90`
`es/minify/libraries/typescript`	`2573515395` ns/iter (`± 11096477`)	`2664650268` ns/iter (`± 17715725`)	`0.97`
`es/minify/libraries/victory`	`531856775` ns/iter (`± 8796710`)	`609534090` ns/iter (`± 12098742`)	`0.87`
`es/minify/libraries/vue`	`113340621` ns/iter (`± 707887`)	`119809849` ns/iter (`± 2066263`)	`0.95`
`es/visitor/compare/clone`	`2317491` ns/iter (`± 25920`)	`2342302` ns/iter (`± 22174`)	`0.99`
`es/visitor/compare/visit_mut_span`	`2680238` ns/iter (`± 6924`)	`2704568` ns/iter (`± 5284`)	`0.99`
`es/visitor/compare/visit_mut_span_panic`	`2712184` ns/iter (`± 7494`)	`2748064` ns/iter (`± 7151`)	`0.99`
`es/visitor/compare/fold_span`	`3778365` ns/iter (`± 8539`)	`3818585` ns/iter (`± 12859`)	`0.99`
`es/visitor/compare/fold_span_panic`	`3915056` ns/iter (`± 12086`)	`3945395` ns/iter (`± 7244`)	`0.99`
`es/lexer/colors`	`13142` ns/iter (`± 65`)	`13252` ns/iter (`± 7`)	`0.99`
`es/lexer/angular`	`6357769` ns/iter (`± 17543`)	`6421144` ns/iter (`± 13279`)	`0.99`
`es/lexer/backbone`	`782213` ns/iter (`± 3509`)	`793090` ns/iter (`± 357`)	`0.99`
`es/lexer/jquery`	`4408375` ns/iter (`± 16390`)	`4437193` ns/iter (`± 2742`)	`0.99`
`es/lexer/jquery mobile`	`6890025` ns/iter (`± 44337`)	`6947858` ns/iter (`± 4314`)	`0.99`
`es/lexer/mootools`	`3454376` ns/iter (`± 8173`)	`3482153` ns/iter (`± 1508`)	`0.99`
`es/lexer/underscore`	`646866` ns/iter (`± 2217`)	`652441` ns/iter (`± 466`)	`0.99`
`es/lexer/three`	`20838073` ns/iter (`± 77775`)	`21006511` ns/iter (`± 109626`)	`0.99`
`es/lexer/yui`	`3852238` ns/iter (`± 14606`)	`3877458` ns/iter (`± 1920`)	`0.99`
`es/parser/colors`	`28676` ns/iter (`± 139`)	`29099` ns/iter (`± 78`)	`0.99`
`es/parser/angular`	`14708384` ns/iter (`± 115309`)	`15171205` ns/iter (`± 259052`)	`0.97`
`es/parser/backbone`	`2121787` ns/iter (`± 28898`)	`2153605` ns/iter (`± 10204`)	`0.99`
`es/parser/jquery`	`11478269` ns/iter (`± 110379`)	`11917373` ns/iter (`± 159213`)	`0.96`
`es/parser/jquery mobile`	`17977401` ns/iter (`± 97479`)	`19038358` ns/iter (`± 227946`)	`0.94`
`es/parser/mootools`	`8813834` ns/iter (`± 21191`)	`8934532` ns/iter (`± 34467`)	`0.99`
`es/parser/underscore`	`1792488` ns/iter (`± 11611`)	`1818301` ns/iter (`± 9877`)	`0.99`
`es/parser/three`	`51345805` ns/iter (`± 1853624`)	`55946427` ns/iter (`± 217197`)	`0.92`
`es/parser/yui`	`8932208` ns/iter (`± 86487`)	`9099577` ns/iter (`± 66153`)	`0.98`
`es/preset-env/usage/builtin_type`	`141516` ns/iter (`± 34162`)	`140854` ns/iter (`± 33904`)	`1.00`
`es/preset-env/usage/property`	`20326` ns/iter (`± 114`)	`20468` ns/iter (`± 100`)	`0.99`
`es/resolver/typescript`	`117124945` ns/iter (`± 3370487`)	`121851707` ns/iter (`± 2022229`)	`0.96`
`es/fixer/typescript`	`87261612` ns/iter (`± 1549727`)	`87422755` ns/iter (`± 1146722`)	`1.00`
`es/hygiene/typescript`	`187125584` ns/iter (`± 1341668`)	`189700655` ns/iter (`± 4110668`)	`0.99`
`es/resolver_with_hygiene/typescript`	`322038972` ns/iter (`± 1875265`)	`329692125` ns/iter (`± 3133422`)	`0.98`
`es/visitor/base-perf/module_clone`	`80291` ns/iter (`± 640`)	`80400` ns/iter (`± 444`)	`1.00`
`es/visitor/base-perf/fold_empty`	`90334` ns/iter (`± 279`)	`90588` ns/iter (`± 157`)	`1.00`
`es/visitor/base-perf/fold_noop_impl_all`	`90586` ns/iter (`± 607`)	`91004` ns/iter (`± 479`)	`1.00`
`es/visitor/base-perf/fold_noop_impl_vec`	`90475` ns/iter (`± 646`)	`91846` ns/iter (`± 387`)	`0.99`
`es/visitor/base-perf/boxing_boxed_clone`	`56` ns/iter (`± 0`)	`57` ns/iter (`± 0`)	`0.98`
`es/visitor/base-perf/boxing_unboxed_clone`	`42` ns/iter (`± 0`)	`45` ns/iter (`± 0`)	`0.93`
`es/visitor/base-perf/boxing_boxed`	`103` ns/iter (`± 0`)	`104` ns/iter (`± 0`)	`0.99`
`es/visitor/base-perf/boxing_unboxed`	`78` ns/iter (`± 0`)	`78` ns/iter (`± 0`)	`1`
`es/visitor/base-perf/visit_contains_this`	`3415` ns/iter (`± 95`)	`3486` ns/iter (`± 72`)	`0.98`
`es/base/parallel/resolver/typescript`	`6159839606` ns/iter (`± 543660522`)	`6544827355` ns/iter (`± 607789625`)	`0.94`
`es/base/parallel/hygiene/typescript`	`2180589045` ns/iter (`± 28787817`)	`2217463085` ns/iter (`± 18452064`)	`0.98`
`misc/visitors/time-complexity/time 5`	`96` ns/iter (`± 0`)	`98` ns/iter (`± 0`)	`0.98`
`misc/visitors/time-complexity/time 10`	`323` ns/iter (`± 10`)	`331` ns/iter (`± 6`)	`0.98`
`misc/visitors/time-complexity/time 15`	`632` ns/iter (`± 5`)	`652` ns/iter (`± 6`)	`0.97`
`misc/visitors/time-complexity/time 20`	`1199` ns/iter (`± 20`)	`1205` ns/iter (`± 7`)	`1.00`
`misc/visitors/time-complexity/time 40`	`6071` ns/iter (`± 40`)	`6180` ns/iter (`± 5`)	`0.98`
`misc/visitors/time-complexity/time 60`	`15190` ns/iter (`± 87`)	`15541` ns/iter (`± 12`)	`0.98`
`es/full-target/es2016`	`251386` ns/iter (`± 1392`)	`254216` ns/iter (`± 649`)	`0.99`
`es/full-target/es2017`	`238946` ns/iter (`± 465`)	`245933` ns/iter (`± 348`)	`0.97`
`es/full-target/es2018`	`229396` ns/iter (`± 1425`)	`235388` ns/iter (`± 554`)	`0.97`
`es2020_nullish_coalescing`	`90839` ns/iter (`± 514`)	`92907` ns/iter (`± 375`)	`0.98`
`es2020_optional_chaining`	`120235` ns/iter (`± 612`)	`124415` ns/iter (`± 415`)	`0.97`
`es2022_class_properties`	`145694` ns/iter (`± 847`)	`149153` ns/iter (`± 215`)	`0.98`
`es2018_object_rest_spread`	`93729` ns/iter (`± 722`)	`96067` ns/iter (`± 225`)	`0.98`
`es2019_optional_catch_binding`	`83396` ns/iter (`± 926`)	`85219` ns/iter (`± 225`)	`0.98`
`es2017_async_to_generator`	`83691` ns/iter (`± 598`)	`85851` ns/iter (`± 229`)	`0.97`
`es2016_exponentiation`	`88040` ns/iter (`± 553`)	`90345` ns/iter (`± 214`)	`0.97`
`es2015_arrow`	`90898` ns/iter (`± 538`)	`93803` ns/iter (`± 245`)	`0.97`
`es2015_block_scoped_fn`	`89849` ns/iter (`± 574`)	`92387` ns/iter (`± 318`)	`0.97`
`es2015_block_scoping`	`165039` ns/iter (`± 509`)	`169864` ns/iter (`± 247`)	`0.97`