Add predictable mode to test driver.

tools/run-tests.py

 #!/usr/bin/env python
 #
 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 153 matching lines @@
   result.add_option("--no-stress", "--nostress",
                     help="Don't run crankshaft --always-opt --stress-op test",
                     default=False, dest="no_stress", action="store_true")
   result.add_option("--no-variants", "--novariants",
                     help="Don't run any testing variants",
                     default=False, dest="no_variants", action="store_true")
   result.add_option("--variants",
                     help="Comma-separated list of testing variants")
   result.add_option("--outdir", help="Base directory with compile output",
                     default="out")
+  result.add_option("--predictable",
+                    help="Compare output of several reruns of each test",
+                    default=False, action="store_true")
   result.add_option("-p", "--progress",
                     help=("The style of progress indicator"
                           " (verbose, dots, color, mono)"),
                     choices=progress.PROGRESS_INDICATORS.keys(), default="mono")
   result.add_option("--quickcheck", default=False, action="store_true",
                     help=("Quick check mode (skip slow/flaky tests)"))
   result.add_option("--report", help="Print a summary of the tests to be run",
                     default=False, action="store_true")
   result.add_option("--json-test-results",
                     help="Path to a file for storing json results.")
@@ skipping 110 matching lines @@
   if options.variants:
     VARIANTS = options.variants.split(",")
     if not set(VARIANTS).issubset(VARIANT_FLAGS.keys()):
       print "All variants must be in %s" % str(VARIANT_FLAGS.keys())
       return False
   if options.quickcheck:
     VARIANTS = ["default", "stress"]
     options.flaky_tests = "skip"
     options.slow_tests = "skip"
     options.pass_fail_tests = "skip"
+  if options.predictable:
+    VARIANTS = ["default"]
+    options.extra_flags.append("--predictable")
+    options.extra_flags.append("--verify_predictable")
+    options.extra_flags.append("--no-inline-new")
 
   if not options.shell_dir:
     if options.shell:
       print "Warning: --shell is deprecated, use --shell-dir instead."
       options.shell_dir = os.path.dirname(options.shell)
   if options.valgrind:
     run_valgrind = os.path.join("tools", "run-valgrind.py")
     # This is OK for distributed running, so we don't need to set no_network.
     options.command_prefix = (["python", "-u", run_valgrind] +
                               options.command_prefix)
@@ skipping 95 matching lines @@
   mode_flags = MODE_FLAGS[mode]
   timeout = options.timeout
   if timeout == -1:
     # Simulators are slow, therefore allow a longer default timeout.
     if arch in SLOW_ARCHS:
       timeout = 2 * TIMEOUT_DEFAULT;
     else:
       timeout = TIMEOUT_DEFAULT;
 
   timeout *= TIMEOUT_SCALEFACTOR[mode]
+
+  if options.predictable:
+    # Predictable mode is slower.
+    timeout *= 2
+
   ctx = context.Context(arch, mode, shell_dir,
                         mode_flags, options.verbose,
                         timeout, options.isolates,
                         options.command_prefix,
                         options.extra_flags,
                         options.no_i18n,
                         options.random_seed,
                         options.no_sorting,
                         options.rerun_failures_count,
-                        options.rerun_failures_max)
+                        options.rerun_failures_max,
+                        options.predictable)
 
   # TODO(all): Combine "simulator" and "simulator_run".
   simulator_run = not options.dont_skip_simulator_slow_tests and \
       arch in ['arm64', 'arm', 'mips'] and ARCH_GUESS and arch != ARCH_GUESS
   # Find available test suites and read test cases from them.
   variables = {
     "arch": arch,
     "asan": options.asan,
     "deopt_fuzzer": False,
     "gc_stress": options.gc_stress,
@@ skipping 77 matching lines @@
   exit_code = runner.Run(options.j)
   overall_duration = time.time() - start_time
 
   if options.time:
     verbose.PrintTestDurations(suites, overall_duration)
   return exit_code
 
 
 if __name__ == "__main__":
   sys.exit(Main())