Add flag --single-threaded

src/flag-definitions.h

 // Copyright 2012 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.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 891 matching lines @@
 // mksnapshot.cc
 DEFINE_STRING(startup_src, NULL,
               "Write V8 startup as C++ src. (mksnapshot only)")
 DEFINE_STRING(startup_blob, NULL,
               "Write V8 startup blob file. (mksnapshot only)")
 
 // code-stubs-hydrogen.cc
 DEFINE_BOOL(profile_hydrogen_code_stub_compilation, false,
             "Print the time it takes to lazily compile hydrogen code stubs.")
 
-DEFINE_BOOL(predictable, false, "enable predictable mode")
-DEFINE_NEG_IMPLICATION(predictable, concurrent_recompilation)
-DEFINE_NEG_IMPLICATION(predictable, concurrent_sweeping)
-DEFINE_NEG_IMPLICATION(predictable, parallel_compaction)
-DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
-
 // mark-compact.cc
 DEFINE_BOOL(force_marking_deque_overflows, false,
             "force overflows of marking deque by reducing it's size "
             "to 64 words")
 
 DEFINE_BOOL(stress_compaction, false,
             "stress the GC compactor to flush out bugs (implies "
             "--force_marking_deque_overflows)")
 
 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
@@ skipping 223 matching lines @@
 DEFINE_IMPLICATION(print_all_code, print_unopt_code)
 DEFINE_IMPLICATION(print_all_code, print_code_verbose)
 DEFINE_IMPLICATION(print_all_code, print_builtin_code)
 DEFINE_IMPLICATION(print_all_code, print_code_stubs)
 DEFINE_IMPLICATION(print_all_code, code_comments)
 #ifdef DEBUG
 DEFINE_IMPLICATION(print_all_code, trace_codegen)
 #endif
 #endif
 
+#undef FLAG
+#define FLAG FLAG_FULL
 
 //
-// VERIFY_PREDICTABLE related flags
+// Threading related flags.
 //
+
+DEFINE_BOOL(single_threaded, false, "disable the use of background tasks")
+DEFINE_NEG_IMPLICATION(single_threaded, concurrent_recompilation)
+DEFINE_NEG_IMPLICATION(single_threaded, concurrent_sweeping)
+DEFINE_NEG_IMPLICATION(single_threaded, parallel_compaction)
+
+//
+// Predictable mode related flags.
+//
+
+DEFINE_BOOL(predictable, false, "enable predictable mode")
+DEFINE_IMPLICATION(predictable, single_threaded)
+DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
+
 #undef FLAG
 
 #ifdef VERIFY_PREDICTABLE
 #define FLAG FLAG_FULL
 #else
 #define FLAG FLAG_READONLY
 #endif
 
 DEFINE_BOOL(verify_predictable, false,
             "this mode is used for checking that V8 behaves predictably")
 DEFINE_INT(dump_allocations_digest_at_alloc, -1,
            "dump allocations digest each n-th allocation")
 
-
 //
 // Read-only flags
 //
 #undef FLAG
 #define FLAG FLAG_READONLY
 
 // assembler.h
 DEFINE_BOOL(enable_embedded_constant_pool, V8_EMBEDDED_CONSTANT_POOL,
             "enable use of embedded constant pools (ARM/PPC only)")
 
 DEFINE_BOOL(unbox_double_fields, V8_DOUBLE_FIELDS_UNBOXING,
             "enable in-object double fields unboxing (64-bit only)")
 DEFINE_IMPLICATION(unbox_double_fields, track_double_fields)
 
-
 // Cleanup...
 #undef FLAG_FULL
 #undef FLAG_READONLY
 #undef FLAG
 #undef FLAG_ALIAS
 
 #undef DEFINE_BOOL
 #undef DEFINE_MAYBE_BOOL
 #undef DEFINE_INT
 #undef DEFINE_STRING
 #undef DEFINE_FLOAT
 #undef DEFINE_ARGS
 #undef DEFINE_IMPLICATION
 #undef DEFINE_NEG_IMPLICATION
 #undef DEFINE_NEG_VALUE_IMPLICATION
 #undef DEFINE_VALUE_IMPLICATION
 #undef DEFINE_ALIAS_BOOL
 #undef DEFINE_ALIAS_INT
 #undef DEFINE_ALIAS_STRING
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA