Avoid effect of element access expression (#39174)

* Avoid effect of element access expression

* Avoid unnecessary copy

* Add more tests

src/compiler/transformers/esnext.ts

@@ -25,7 +25,7 @@ namespace ts {
                     if (isLogicalOrCoalescingAssignmentExpression(binaryExpression)) {
                         return transformLogicalAssignment(binaryExpression);
                     }
-                    // falls through
+                // falls through
                 default:
                     return visitEachChild(node, visitor, context);
             }
@@ -37,32 +37,41 @@ namespace ts {
             let left = skipParentheses(visitNode(binaryExpression.left, visitor, isLeftHandSideExpression));
             let assignmentTarget = left;
             const right = skipParentheses(visitNode(binaryExpression.right, visitor, isExpression));
+
             if (isAccessExpression(left)) {
-                const tempVariable = factory.createTempVariable(hoistVariableDeclaration);
+                const propertyAccessTargetSimpleCopiable = isSimpleCopiableExpression(left.expression);
+                const propertyAccessTarget = propertyAccessTargetSimpleCopiable ? left.expression :
+                    factory.createTempVariable(hoistVariableDeclaration);
+                const propertyAccessTargetAssignment = propertyAccessTargetSimpleCopiable ? left.expression : factory.createAssignment(
+                    propertyAccessTarget,
+                    left.expression
+                );
+
                 if (isPropertyAccessExpression(left)) {
                     assignmentTarget = factory.createPropertyAccessExpression(
-                        tempVariable,
+                        propertyAccessTarget,
                         left.name
                     );
                     left = factory.createPropertyAccessExpression(
-                        factory.createAssignment(
-                            tempVariable,
-                            left.expression
-                        ),
+                        propertyAccessTargetAssignment,
                         left.name
                     );
                 }
                 else {
+                    const elementAccessArgumentSimpleCopiable = isSimpleCopiableExpression(left.argumentExpression);
+                    const elementAccessArgument = elementAccessArgumentSimpleCopiable ? left.argumentExpression :
+                        factory.createTempVariable(hoistVariableDeclaration);
+
                     assignmentTarget = factory.createElementAccessExpression(
-                        tempVariable,
-                        left.argumentExpression
+                        propertyAccessTarget,
+                        elementAccessArgument
                     );
                     left = factory.createElementAccessExpression(
-                        factory.createAssignment(
-                            tempVariable,
-                            left.expression
-                        ),
-                        left.argumentExpression
+                        propertyAccessTargetAssignment,
+                        elementAccessArgumentSimpleCopiable ? left.argumentExpression : factory.createAssignment(
+                            elementAccessArgument,
+                            left.argumentExpression
+                        )
                     );
                 }
             }

tests/baselines/reference/logicalAssignment10(target=es2015).js

@@ -0,0 +1,28 @@
+//// [logicalAssignment10.ts]
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+
+const oobj = {
+    obj
+}
+
+obj[incr()] ??= incr();
+oobj["obj"][incr()] ??= incr();
+
+
+//// [logicalAssignment10.js]
+var _a, _b;
+var _c, _d, _e;
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+const oobj = {
+    obj
+};
+(_a = obj[_c = incr()]) !== null && _a !== void 0 ? _a : (obj[_c] = incr());
+(_b = (_d = oobj["obj"])[_e = incr()]) !== null && _b !== void 0 ? _b : (_d[_e] = incr());

tests/baselines/reference/logicalAssignment10(target=es2015).symbols

@@ -0,0 +1,32 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+
+var obj = {};
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+
+function incr() {
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+    return ++count;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+}
+
+const oobj = {
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+
+    obj
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+}
+
+obj[incr()] ??= incr();
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+oobj["obj"][incr()] ??= incr();
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+>"obj" : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+

tests/baselines/reference/logicalAssignment10(target=es2015).types

@@ -0,0 +1,45 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : number
+>0 : 0
+
+var obj = {};
+>obj : {}
+>{} : {}
+
+function incr() {
+>incr : () => number
+
+    return ++count;
+>++count : number
+>count : number
+}
+
+const oobj = {
+>oobj : { obj: {}; }
+>{    obj} : { obj: {}; }
+
+    obj
+>obj : {}
+}
+
+obj[incr()] ??= incr();
+>obj[incr()] ??= incr() : any
+>obj[incr()] : error
+>obj : {}
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+
+oobj["obj"][incr()] ??= incr();
+>oobj["obj"][incr()] ??= incr() : any
+>oobj["obj"][incr()] : error
+>oobj["obj"] : {}
+>oobj : { obj: {}; }
+>"obj" : "obj"
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+

tests/baselines/reference/logicalAssignment10(target=es2020).js

@@ -0,0 +1,27 @@
+//// [logicalAssignment10.ts]
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+
+const oobj = {
+    obj
+}
+
+obj[incr()] ??= incr();
+oobj["obj"][incr()] ??= incr();
+
+
+//// [logicalAssignment10.js]
+var _a, _b, _c;
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+const oobj = {
+    obj
+};
+obj[_a = incr()] ?? (obj[_a] = incr());
+(_b = oobj["obj"])[_c = incr()] ?? (_b[_c] = incr());

tests/baselines/reference/logicalAssignment10(target=es2020).symbols

@@ -0,0 +1,32 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+
+var obj = {};
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+
+function incr() {
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+    return ++count;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+}
+
+const oobj = {
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+
+    obj
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+}
+
+obj[incr()] ??= incr();
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+oobj["obj"][incr()] ??= incr();
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+>"obj" : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+

tests/baselines/reference/logicalAssignment10(target=es2020).types

@@ -0,0 +1,45 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : number
+>0 : 0
+
+var obj = {};
+>obj : {}
+>{} : {}
+
+function incr() {
+>incr : () => number
+
+    return ++count;
+>++count : number
+>count : number
+}
+
+const oobj = {
+>oobj : { obj: {}; }
+>{    obj} : { obj: {}; }
+
+    obj
+>obj : {}
+}
+
+obj[incr()] ??= incr();
+>obj[incr()] ??= incr() : any
+>obj[incr()] : error
+>obj : {}
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+
+oobj["obj"][incr()] ??= incr();
+>oobj["obj"][incr()] ??= incr() : any
+>oobj["obj"][incr()] : error
+>oobj["obj"] : {}
+>oobj : { obj: {}; }
+>"obj" : "obj"
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+

tests/baselines/reference/logicalAssignment10(target=esnext).js

@@ -0,0 +1,26 @@
+//// [logicalAssignment10.ts]
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+
+const oobj = {
+    obj
+}
+
+obj[incr()] ??= incr();
+oobj["obj"][incr()] ??= incr();
+
+
+//// [logicalAssignment10.js]
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+const oobj = {
+    obj
+};
+obj[incr()] ??= incr();
+oobj["obj"][incr()] ??= incr();

tests/baselines/reference/logicalAssignment10(target=esnext).symbols

@@ -0,0 +1,32 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+
+var obj = {};
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+
+function incr() {
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+    return ++count;
+>count : Symbol(count, Decl(logicalAssignment10.ts, 0, 3))
+}
+
+const oobj = {
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+
+    obj
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+}
+
+obj[incr()] ??= incr();
+>obj : Symbol(obj, Decl(logicalAssignment10.ts, 1, 3))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+
+oobj["obj"][incr()] ??= incr();
+>oobj : Symbol(oobj, Decl(logicalAssignment10.ts, 6, 5))
+>"obj" : Symbol(obj, Decl(logicalAssignment10.ts, 6, 14))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+>incr : Symbol(incr, Decl(logicalAssignment10.ts, 1, 13))
+

tests/baselines/reference/logicalAssignment10(target=esnext).types

@@ -0,0 +1,45 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts ===
+var count = 0;
+>count : number
+>0 : 0
+
+var obj = {};
+>obj : {}
+>{} : {}
+
+function incr() {
+>incr : () => number
+
+    return ++count;
+>++count : number
+>count : number
+}
+
+const oobj = {
+>oobj : { obj: {}; }
+>{    obj} : { obj: {}; }
+
+    obj
+>obj : {}
+}
+
+obj[incr()] ??= incr();
+>obj[incr()] ??= incr() : any
+>obj[incr()] : error
+>obj : {}
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+
+oobj["obj"][incr()] ??= incr();
+>oobj["obj"][incr()] ??= incr() : any
+>oobj["obj"][incr()] : error
+>oobj["obj"] : {}
+>oobj : { obj: {}; }
+>"obj" : "obj"
+>incr() : number
+>incr : () => number
+>incr() : number
+>incr : () => number
+

tests/baselines/reference/logicalAssignment2(target=es2015).js

@@ -31,13 +31,13 @@ c.foo.bar().baz ??= result.foo.bar().baz
 //// [logicalAssignment2.js]
 "use strict";
 var _a, _b, _c;
-var _d, _e, _f, _g, _h, _j, _k, _l, _m;
-(_d = a).baz && (_d.baz = result.baz);
-(_e = b).baz || (_e.baz = result.baz);
-(_a = (_f = c).baz) !== null && _a !== void 0 ? _a : (_f.baz = result.baz);
-(_g = a.foo)["baz"] && (_g["baz"] = result.foo.baz);
-(_h = b.foo)["baz"] || (_h["baz"] = result.foo.baz);
-(_b = (_j = c.foo)["baz"]) !== null && _b !== void 0 ? _b : (_j["baz"] = result.foo.baz);
-(_k = a.foo.bar()).baz && (_k.baz = result.foo.bar().baz);
-(_l = b.foo.bar()).baz || (_l.baz = result.foo.bar().baz);
-(_c = (_m = c.foo.bar()).baz) !== null && _c !== void 0 ? _c : (_m.baz = result.foo.bar().baz);
+var _d, _e, _f, _g, _h, _j;
+a.baz && (a.baz = result.baz);
+b.baz || (b.baz = result.baz);
+(_a = c.baz) !== null && _a !== void 0 ? _a : (c.baz = result.baz);
+(_d = a.foo)["baz"] && (_d["baz"] = result.foo.baz);
+(_e = b.foo)["baz"] || (_e["baz"] = result.foo.baz);
+(_b = (_f = c.foo)["baz"]) !== null && _b !== void 0 ? _b : (_f["baz"] = result.foo.baz);
+(_g = a.foo.bar()).baz && (_g.baz = result.foo.bar().baz);
+(_h = b.foo.bar()).baz || (_h.baz = result.foo.bar().baz);
+(_c = (_j = c.foo.bar()).baz) !== null && _c !== void 0 ? _c : (_j.baz = result.foo.bar().baz);

tests/baselines/reference/logicalAssignment2(target=es2020).js

@@ -30,13 +30,13 @@ c.foo.bar().baz ??= result.foo.bar().baz
 
 //// [logicalAssignment2.js]
 "use strict";
-var _a, _b, _c, _d, _e, _f, _g, _h, _j;
-(_a = a).baz && (_a.baz = result.baz);
-(_b = b).baz || (_b.baz = result.baz);
-(_c = c).baz ?? (_c.baz = result.baz);
-(_d = a.foo)["baz"] && (_d["baz"] = result.foo.baz);
-(_e = b.foo)["baz"] || (_e["baz"] = result.foo.baz);
-(_f = c.foo)["baz"] ?? (_f["baz"] = result.foo.baz);
-(_g = a.foo.bar()).baz && (_g.baz = result.foo.bar().baz);
-(_h = b.foo.bar()).baz || (_h.baz = result.foo.bar().baz);
-(_j = c.foo.bar()).baz ?? (_j.baz = result.foo.bar().baz);
+var _a, _b, _c, _d, _e, _f;
+a.baz && (a.baz = result.baz);
+b.baz || (b.baz = result.baz);
+c.baz ?? (c.baz = result.baz);
+(_a = a.foo)["baz"] && (_a["baz"] = result.foo.baz);
+(_b = b.foo)["baz"] || (_b["baz"] = result.foo.baz);
+(_c = c.foo)["baz"] ?? (_c["baz"] = result.foo.baz);
+(_d = a.foo.bar()).baz && (_d.baz = result.foo.bar().baz);
+(_e = b.foo.bar()).baz || (_e.baz = result.foo.bar().baz);
+(_f = c.foo.bar()).baz ?? (_f.baz = result.foo.bar().baz);

tests/baselines/reference/logicalAssignment3(target=es2015).js

@@ -17,7 +17,6 @@ declare const c: A;
 //// [logicalAssignment3.js]
 "use strict";
 var _a;
-var _b, _c, _d;
-(_b = a).baz && (_b.baz = result.baz);
-(_c = b).baz || (_c.baz = result.baz);
-(_a = (_d = c).baz) !== null && _a !== void 0 ? _a : (_d.baz = result.baz);
+a.baz && (a.baz = result.baz);
+b.baz || (b.baz = result.baz);
+(_a = c.baz) !== null && _a !== void 0 ? _a : (c.baz = result.baz);

tests/baselines/reference/logicalAssignment3(target=es2020).js

@@ -16,7 +16,6 @@ declare const c: A;
 
 //// [logicalAssignment3.js]
 "use strict";
-var _a, _b, _c;
-(_a = a).baz && (_a.baz = result.baz);
-(_b = b).baz || (_b.baz = result.baz);
-(_c = c).baz ?? (_c.baz = result.baz);
+a.baz && (a.baz = result.baz);
+b.baz || (b.baz = result.baz);
+c.baz ?? (c.baz = result.baz);

tests/baselines/reference/logicalAssignment9.js

@@ -8,6 +8,5 @@ x.a &&= false;
 //// [logicalAssignment9.js]
 "use strict";
 var _a;
-var _b, _c;
-(_a = (_b = x).a) !== null && _a !== void 0 ? _a : (_b.a = true);
-(_c = x).a && (_c.a = false);
+(_a = x.a) !== null && _a !== void 0 ? _a : (x.a = true);
+x.a && (x.a = false);

tests/cases/conformance/esnext/logicalAssignment/logicalAssignment10.ts

@@ -0,0 +1,14 @@
+// @target: esnext, es2020, es2015
+
+var count = 0;
+var obj = {};
+function incr() {
+    return ++count;
+}
+
+const oobj = {
+    obj
+}
+
+obj[incr()] ??= incr();
+oobj["obj"][incr()] ??= incr();