Parallelize test/mjsunit/es6/tail-call-megatest.js in order to avoid timeouts on slow architectures.

test/mjsunit/es6/tail-call-megatest.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // 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
 // TODO(v8:4698), TODO(ishell): support these cases.
 // Flags: --turbo --nostress-opt
 
 
 Error.prepareStackTrace = (error,stack) => {
@@ skipping 21 matching lines @@
   }
   return line;
 })();
 
 
 function ident_source(source, ident) {
   ident = " ".repeat(ident);
   return ident + source.replace(/\n/gi, "\n" + ident);
 }
 
+var SHARDS_COUNT = 10;
 
-function run_tests() {
+function run_tests(shard) {
   function inlinable_comment(inlinable) {
     return inlinable ? CAN_INLINE_COMMENT : DONT_INLINE_COMMENT;
   }
 
   // Check arguments manually to avoid bailing out with reason "bad value
   // context for arguments value".
   function check_arguments_template(expected_name) {
     var lines = [
       `  assertEquals_(${expected_name}.length, arguments.length);`,
       `  for (var i = 0; i < ${expected_name}.length; i++) {`,
@@ skipping 264 matching lines @@
       f_cfg_possibly_eval,
   ];
   var g_variants = [
       g_cfg_normal,
       g_cfg_function_call,
       g_cfg_function_apply,
       g_cfg_function_apply_arguments_object,
   ];
   var test_warmup_counts = [0, 1, 2];
 
+  var iter = 0;
+  if (shard !== undefined) {
+    print("Running shard #" + shard);
+  }
   f_variants.forEach((f_cfg) => {
     g_variants.forEach((g_cfg) => {
       f_args_variants.forEach((f_args) => {
         g_args_variants.forEach((g_args) => {
           f_inlinable_variants.forEach((f_inlinable) => {
             g_inlinable_variants.forEach((g_inlinable) => {
               test_warmup_counts.forEach((test_warmup_count) => {
+                if (shard !== undefined && (iter++) % SHARDS_COUNT != shard) {
+                  print("skipping...");
+                  return;
+                }
                 var cfg = {
                   f_source_template: f_cfg.source_template,
                   f_inlinable,
                   f_args,
                   f_name: f_cfg.func_name,
                   f_receiver: g_cfg.receiver,
                   g_source_template: g_cfg.source_template,
                   g_inlinable,
                   g_args,
                   test_warmup_count,
                 };
                 var source = test_template(cfg);
                 print("====================");
                 print(source);
                 eval(source);
               });
             });
           });
         });
       });
     });
   });
 }
 
-run_tests();
+// Uncomment to run all the tests at once or use shard runners.
+//run_tests();