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.

test/language/statements/labeled/tco.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;
+  }
+  test262: return f(n - 1);
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/return/tco.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 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/switch/tco-case-body-dflt.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;
+  }
+  switch(0) { case 0: return f(n - 1); default: }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/switch/tco-case-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;
+  }
+  switch(0) { case 0: return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/switch/tco-dftl-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;
+  }
+  switch(0) { default: return f(n - 1); }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/try/tco-catch-finally.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;
+  }
+  try { } catch (err) { } finally {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/try/tco-catch.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;
+  }
+  try {
+    throw null;
+  } catch (err) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/try/tco-finally.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;
+  }
+  try { } finally {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);

test/language/statements/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;
+  }
+  while (true) {
+    return f(n - 1);
+  }
+}($MAX_ITERATIONS));
+assert.sameValue(callCount, 1);