[es8] Initial set of changes to support syntactic tail calls.

test/mjsunit/es7/syntactic-tail-call.js

Index: test/mjsunit/es7/syntactic-tail-call.js
diff --git a/test/mjsunit/es6/tail-call.js b/test/mjsunit/es7/syntactic-tail-call.js
similarity index 82%
copy from test/mjsunit/es6/tail-call.js
copy to test/mjsunit/es7/syntactic-tail-call.js
index 318519b3551c0b939e9fdcbfef883c11c384708f..b65fc450590afff8f051e1323dad6a4ec38ceede 100644
--- a/test/mjsunit/es6/tail-call.js
+++ b/test/mjsunit/es7/syntactic-tail-call.js
@@ -2,8 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony-tailcalls
-"use strict";
+// Flags: --allow-natives-syntax --harmony-explicit-tailcalls
 
 Error.prepareStackTrace = (error,stack) => {
   error.strace = stack;
@@ -39,28 +38,28 @@ function f_153(expected_call_stack, a) {
     CheckStackTrace([f1, test]);
     return 10 + a;
   }
-  function g1(a) { return f1(2); }
+  function g1(a) { return continue f1(2); }
 
   // Caller has more arguments than callee.
   function f2(a) {
     CheckStackTrace([f2, test]);
     return 10 + a;
   }
-  function g2(a, b, c) { return f2(2); }
+  function g2(a, b, c) { return continue f2(2); }
 
   // Caller has less arguments than callee.
   function f3(a, b, c) {
     CheckStackTrace([f3, test]);
     return 10 + a + b + c;
   }
-  function g3(a) { return f3(2, 3, 4); }
+  function g3(a) { return continue f3(2, 3, 4); }
 
   // Callee has arguments adaptor frame.
   function f4(a, b, c) {
     CheckStackTrace([f4, test]);
     return 10 + a;
   }
-  function g4(a) { return f4(2); }
+  function g4(a) { return continue f4(2); }
 
   function test() {
     assertEquals(12, g1(1));
@@ -82,28 +81,28 @@ function f_153(expected_call_stack, a) {
     CheckStackTrace([f1, test]);
     return 10 + a;
   }
-  function g1(a) { return f1(2); }
+  function g1(a) { return continue f1(2); }
 
   // Caller has more arguments than callee.
   function f2(a) {
     CheckStackTrace([f2, test]);
     return 10 + a;
   }
-  function g2(a, b, c) { return f2(2); }
+  function g2(a, b, c) { return continue f2(2); }
 
   // Caller has less arguments than callee.
   function f3(a, b, c) {
     CheckStackTrace([f3, test]);
     return 10 + a + b + c;
   }
-  function g3(a) { return f3(2, 3, 4); }
+  function g3(a) { return continue f3(2, 3, 4); }
 
   // Callee has arguments adaptor frame.
   function f4(a, b, c) {
     CheckStackTrace([f4, test]);
     return 10 + a;
   }
-  function g4(a) { return f4(2); }
+  function g4(a) { return continue f4(2); }
 
   function test() {
     assertEquals(12, g1());
@@ -128,7 +127,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b1 = f1.bind({a: 153});
-  function g1(a) { return b1(2); }
+  function g1(a) { return continue b1(2); }
 
   // Caller has more arguments than callee.
   function f2(a) {
@@ -137,7 +136,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b2 = f2.bind({a: 153});
-  function g2(a, b, c) { return b2(2); }
+  function g2(a, b, c) { return continue b2(2); }
 
   // Caller has less arguments than callee.
   function f3(a, b, c) {
@@ -146,7 +145,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a + b + c;
   }
   var b3 = f3.bind({a: 153});
-  function g3(a) { return b3(2, 3, 4); }
+  function g3(a) { return continue b3(2, 3, 4); }
 
   // Callee has arguments adaptor frame.
   function f4(a, b, c) {
@@ -155,7 +154,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b4 = f4.bind({a: 153});
-  function g4(a) { return b4(2); }
+  function g4(a) { return continue b4(2); }
 
   function test() {
     assertEquals(12, g1(1));
@@ -179,7 +178,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b1 = f1.bind({a: 153});
-  function g1(a) { return b1(2); }
+  function g1(a) { return continue b1(2); }
 
   // Caller has more arguments than callee.
   function f2(a) {
@@ -188,7 +187,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b2 = f2.bind({a: 153});
-  function g2(a, b, c) { return b2(2); }
+  function g2(a, b, c) { return continue b2(2); }
 
   // Caller has less arguments than callee.
   function f3(a, b, c) {
@@ -197,7 +196,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a + b + c;
   }
   var b3 = f3.bind({a: 153});
-  function g3(a) { return b3(2, 3, 4); }
+  function g3(a) { return continue b3(2, 3, 4); }
 
   // Callee has arguments adaptor frame.
   function f4(a, b, c) {
@@ -206,7 +205,7 @@ function f_153(expected_call_stack, a) {
     return 10 + a;
   }
   var b4 = f4.bind({a: 153});
-  function g4(a) { return b4(2); }
+  function g4(a) { return continue b4(2); }
 
   function test() {
     assertEquals(12, g1());
@@ -224,15 +223,15 @@ function f_153(expected_call_stack, a) {
 // Tail calling via various expressions.
 (function() {
   function g1(a) {
-    return f([f, g1, test], false) || f([f, test], true);
+    return continue f([f, g1, test], false) || f([f, test], true);
   }
 
   function g2(a) {
-    return f([f, g2, test], true) && f([f, test], true);
+    return continue f([f, g2, test], true) && f([f, test], true);
   }
 
   function g3(a) {
-    return f([f, g3, test], 13), f([f, test], 153);
+    return continue f([f, g3, test], 13), f([f, test], 153);
   }
 
   function test() {
@@ -264,7 +263,7 @@ function f_153(expected_call_stack, a) {
       throw new Error("boom");
     } catch(e) {
       f_153([f_153, tc2, test]);
-      return f_153([f_153, test]);
+      return continue f_153([f_153, test]);
     }
   }
 
@@ -276,7 +275,7 @@ function f_153(expected_call_stack, a) {
       f_153([f_153, tc3, test]);
     }
     f_153([f_153, tc3, test]);
-    return f_153([f_153, test]);
+    return continue f_153([f_153, test]);
   }
 
   function test() {
@@ -308,7 +307,7 @@ function f_153(expected_call_stack, a) {
       throw new Error("boom");
     } finally {
       f_153([f_153, tf2, test]);
-      return f_153([f_153, test]);
+      return continue f_153([f_153, test]);
     }
   }
 
@@ -318,7 +317,7 @@ function f_153(expected_call_stack, a) {
     } finally {
       f_153([f_153, tf3, test]);
     }
-    return f_153([f_153, test]);
+    return continue f_153([f_153, test]);
   }
 
   function test() {
@@ -365,7 +364,7 @@ function f_153(expected_call_stack, a) {
       f_153([f_153, tcf3, test]);
     } finally {
       f_153([f_153, tcf3, test]);
-      return f_153([f_153, test]);
+      return continue f_153([f_153, test]);
     }
   }
 
@@ -378,7 +377,7 @@ function f_153(expected_call_stack, a) {
     } finally {
       f_153([f_153, tcf4, test]);
     }
-    return f_153([f_153, test]);
+    return continue f_153([f_153, test]);
   }
 
   function test() {
@@ -397,16 +396,25 @@ function f_153(expected_call_stack, a) {
 // Test tail calls from arrow functions.
 (function () {
   function g1(a) {
-    return (() => { return f_153([f_153, test]); })();
+    return continue (() => { return continue f_153([f_153, test]); })();
   }
 
   function g2(a) {
-    return (() => f_153([f_153, test]))();
+    return continue (() => continue f_153([f_153, test]))();
+  }
+
+  function g3(a) {
+    var closure = () => continue f([f, closure, test], true)
+                                            ? f_153([f_153, test])
+                                            : f_153([f_153, test]);
+
+    return continue closure();
   }
 
   function test() {
     assertEquals(153, g1());
     assertEquals(153, g2());
+    assertEquals(153, g3());
   }
   test();
   test();