Add tests for tail-call optimization

ECMAScript 2015 introduced tail call optimization for function calls
occuring in a number of positions in the grammar. Assert expected
behavior by triggering a large (but configurable) number of recursive
function calls in these positions. Compliant runtimes will execute such
programs without error; non-compliant runtimes are expected to fail
these tests by throwing an error or crashing when system resources are
exhausted.

harness/tco-helper.js

+// This defines the number of consecutive recursive function calls that must be
+// made in order to prove that stack frames are properly destroyed according to
+// ES2015 tail call optimization semantics.
+var $MAX_ITERATIONS = 100000;

test/language/expressions/call/tco-call-args.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  function getF() { return f; }
+  return getF()(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/call/tco-member-args.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/comma/tco-final.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return 0, f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/conditional/tco-cond.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return true ? f(n - 1) : 0;
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/conditional/tco-pos.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return false ? 0 : f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/logical-and/tco-right.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return true && f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/logical-or/tco-right.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return false || f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/expressions/tagged-template/tco-call.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+(function() {
+  var finished = false;
+  function getF() {
+    return f;
+  }
+  function f(_, n) {
+    if (n === 0) {
+      finished = true;
+      return;
+    }
+    return getF()`${n-1}`;
+  }
+  f(null, $MAX_ITERATIONS);
+  return finished;
+}());

test/language/expressions/tagged-template/tco-member.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+(function() {
+  var finished = false;
+  function f(_, n) {
+    if (n === 0) {
+      finished = true;
+      return;
+    }
+    return f`${n-1}`;
+  }
+  f(null, $MAX_ITERATIONS);
+  return finished;
+}());

test/language/expressions/tco-pos.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Expression is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  return (f(n - 1));
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/block/tco-stmt-list.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  { void 0; return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/block/tco-stmt.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  { return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/do-while/tco-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  do {
+    return f(n - 1);
+  } while (false)
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/for/tco-const-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  for (const x = 0; ;) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/for/tco-let-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  for (let x = 0; ;) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/for/tco-lhs-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  var x;
+  for (x = 0; x < 1; ++x) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/for/tco-var-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  for (var x = 0; ;) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/if/tco-else-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  if (false) { } else { return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/if/tco-if-body.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Statement within statement is a candidate for tail-call optimization.
+id: static-semantics-hasproductionintailposition
+flags: [onlyStrict]
+features: [tail-call-optimization]
+includes: [tco-helper.js]
+---*/
+
+var callCount = 0;
+(function f(n) {
+  if (n === 0) {
+    callCount += 1
+    return;
+  }
+  if (true) { return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);