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// 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
// a mode defined before it's included. The modes are FLAG_MODE_... below:
#define DEFINE_IMPLICATION(whenflag, thenflag) \
DEFINE_VALUE_IMPLICATION(whenflag, thenflag, true)
// A weak implication will be overwritten by a normal implication or by an
// explicit flag.
#define DEFINE_WEAK_IMPLICATION(whenflag, thenflag) \
DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, true)
#define DEFINE_NEG_IMPLICATION(whenflag, thenflag) \
DEFINE_VALUE_IMPLICATION(whenflag, thenflag, false)
#define DEFINE_NEG_NEG_IMPLICATION(whenflag, thenflag) \
DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, false)
// We want to declare the names of the variables for the header file. Normally
// this will just be an extern declaration, but for a readonly flag we let the
// compiler make better optimizations by giving it the value.
#if defined(FLAG_MODE_DECLARE)
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
#define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
static constexpr ctype FLAG_##nam = def;
// We want to supply the actual storage and value for the flag variable in the
// .cc file. We only do this for writable flags.
#elif defined(FLAG_MODE_DEFINE)
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
V8_EXPORT_PRIVATE ctype FLAG_##nam = def;
// We need to define all of our default values so that the Flag structure can
// access them by pointer. These are just used internally inside of one .cc,
// for MODE_META, so there is no impact on the flags interface.
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
static constexpr ctype FLAGDEFAULT_##nam = def;
// We want to write entries into our meta data table, for internal parsing and
// printing / etc in the flag parser code. We only do this for writable flags.
#elif defined(FLAG_MODE_META)
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
{Flag::TYPE_##ftype, #nam, &FLAG_##nam, &FLAGDEFAULT_##nam, cmt, false},
#define FLAG_ALIAS(ftype, ctype, alias, nam) \
{Flag::TYPE_##ftype, #alias, &FLAG_##nam, &FLAGDEFAULT_##nam, \
"alias for --" #nam, false},
// We produce the code to set flags when it is implied by another flag.
#define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value) \
changed |= TriggerImplication(FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
value, false);
// A weak implication will be overwritten by a normal implication or by an
// explicit flag.
#define DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, value) \
changed |= TriggerImplication(FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
value, true);
#define DEFINE_GENERIC_IMPLICATION(whenflag, statement) \
if (FLAG_##whenflag) statement;
#define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value) \
changed |= TriggerImplication(!FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
value, false);
// We apply a generic macro to the flags.
#elif defined(FLAG_MODE_APPLY)
#error No mode supplied when including flags.defs
// Dummy defines for modes where it is not relevant.
#ifndef FLAG_FULL
#define FLAG_FULL(ftype, ctype, nam, def, cmt)
#define FLAG_READONLY(ftype, ctype, nam, def, cmt)
#ifndef FLAG_ALIAS
#define FLAG_ALIAS(ftype, ctype, alias, nam)
#define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)
#define DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, value)
#define DEFINE_GENERIC_IMPLICATION(whenflag, statement)
#define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)
#define COMMA ,
struct MaybeBoolFlag {
static MaybeBoolFlag Create(bool has_value, bool value) {
MaybeBoolFlag flag;
flag.has_value = has_value;
flag.value = value;
return flag;
bool has_value;
bool value;
bool operator!=(const MaybeBoolFlag& other) const {
return has_value != other.has_value || value != other.value;
#ifdef DEBUG
#define DEBUG_BOOL true
#define DEBUG_BOOL false
#define V8_HEAP_SANDBOX_BOOL true
#define V8_HEAP_SANDBOX_BOOL false
// Supported ARM configurations are:
// "armv6": ARMv6 + VFPv2
// "armv7": ARMv7 + VFPv3-D32 + NEON
// "armv7+sudiv": ARMv7 + VFPv4-D32 + NEON + SUDIV
// "armv8": ARMv8 (including all of the above)
#if !defined(ARM_TEST_NO_FEATURE_PROBE) || \
defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
#define ARM_ARCH_DEFAULT "armv8"
#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
#define ARM_ARCH_DEFAULT "armv7+sudiv"
#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_NEON) && \
#define ARM_ARCH_DEFAULT "armv7"
#define ARM_ARCH_DEFAULT "armv6"
#ifdef V8_OS_WIN
#define ENABLE_LOG_COLOUR false
#define ENABLE_LOG_COLOUR true
#define DEFINE_BOOL(nam, def, cmt) FLAG(BOOL, bool, nam, def, cmt)
#define DEFINE_BOOL_READONLY(nam, def, cmt) \
FLAG_READONLY(BOOL, bool, nam, def, cmt)
#define DEFINE_MAYBE_BOOL(nam, cmt) \
FLAG(MAYBE_BOOL, MaybeBoolFlag, nam, {false COMMA false}, cmt)
#define DEFINE_INT(nam, def, cmt) FLAG(INT, int, nam, def, cmt)
#define DEFINE_UINT(nam, def, cmt) FLAG(UINT, unsigned int, nam, def, cmt)
#define DEFINE_UINT_READONLY(nam, def, cmt) \
FLAG_READONLY(UINT, unsigned int, nam, def, cmt)
#define DEFINE_UINT64(nam, def, cmt) FLAG(UINT64, uint64_t, nam, def, cmt)
#define DEFINE_FLOAT(nam, def, cmt) FLAG(FLOAT, double, nam, def, cmt)
#define DEFINE_SIZE_T(nam, def, cmt) FLAG(SIZE_T, size_t, nam, def, cmt)
#define DEFINE_STRING(nam, def, cmt) FLAG(STRING, const char*, nam, def, cmt)
#define DEFINE_ALIAS_BOOL(alias, nam) FLAG_ALIAS(BOOL, bool, alias, nam)
#define DEFINE_ALIAS_INT(alias, nam) FLAG_ALIAS(INT, int, alias, nam)
#define DEFINE_ALIAS_FLOAT(alias, nam) FLAG_ALIAS(FLOAT, double, alias, nam)
#define DEFINE_ALIAS_SIZE_T(alias, nam) FLAG_ALIAS(SIZE_T, size_t, alias, nam)
#define DEFINE_ALIAS_STRING(alias, nam) \
FLAG_ALIAS(STRING, const char*, alias, nam)
#ifdef DEBUG
// Flags in all modes.
// ATTENTION: This is set to true by default in d8. But for API compatibility,
// it generally defaults to false.
DEFINE_BOOL(abort_on_contradictory_flags, false,
"Disallow flags or implications overriding each other.")
// This implication is also hard-coded into the flags processing to make sure it
// becomes active before we even process subsequent flags.
DEFINE_NEG_IMPLICATION(fuzzing, abort_on_contradictory_flags)
// This is not really a flag, it affects the interpretation of the next flag but
// doesn't become permanently true when specified. This only works for flags
// defined in this file, but not for d8 flags defined in src/d8/
DEFINE_BOOL(allow_overwriting_for_next_flag, false,
"temporary disable flag contradiction to allow overwriting just "
"the next flag")
// Flags for language modes and experimental language features.
DEFINE_BOOL(use_strict, false, "enforce strict mode")
DEFINE_BOOL(es_staging, false,
"enable test-worthy harmony features (for internal use only)")
DEFINE_BOOL(harmony, false, "enable all completed harmony features")
DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
DEFINE_IMPLICATION(es_staging, harmony)
// Enabling FinalizationRegistry#cleanupSome also enables weak refs
DEFINE_IMPLICATION(harmony_weak_refs_with_cleanup_some, harmony_weak_refs)
// Update whenever adding a new feature flag.
// Features that are still work in progress (behind individual flags).
V(harmony_regexp_sequence, "RegExp Unicode sequence properties") \
V(harmony_weak_refs_with_cleanup_some, \
"harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
V(harmony_regexp_match_indices, "harmony regexp match indices") \
V(harmony_import_assertions, "harmony import assertions")
V(harmony_intl_displaynames_date_types, "Intl.DisplayNames date types")
// Features that are complete (but still behind --harmony/es-staging flag).
V(harmony_top_level_await, "harmony top level await")
V(harmony_intl_dateformat_day_period, \
"Add dayPeriod option to DateTimeFormat")
// Features that are shipping (turned on by default, but internal flag remains).
V(harmony_sharedarraybuffer, "harmony sharedarraybuffer") \
V(harmony_atomics, "harmony atomics") \
V(harmony_promise_any, "harmony Promise.any") \
V(harmony_private_methods, "harmony private methods in class literals") \
V(harmony_weak_refs, "harmony weak references") \
V(harmony_string_replaceall, "harmony String.prototype.replaceAll") \
V(harmony_logical_assignment, "harmony logical assignment") \
V(harmony_atomics_waitasync, "harmony Atomics.waitAsync")
V(harmony_intl_segmenter, "Intl.Segmenter")
// Once a shipping feature has proved stable in the wild, it will be dropped
// from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,
// and associated tests are moved from the harmony directory to the appropriate
// esN directory.
#define FLAG_INPROGRESS_FEATURES(id, description) \
DEFINE_BOOL(id, false, "enable " #description " (in progress)")
#define FLAG_STAGED_FEATURES(id, description) \
DEFINE_BOOL(id, false, "enable " #description) \
#define FLAG_SHIPPING_FEATURES(id, description) \
DEFINE_BOOL(id, true, "enable " #description) \
DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
DEFINE_BOOL(icu_timezone_data, true, "get information about timezones from ICU")
#ifdef V8_LITE_MODE
#define V8_LITE_BOOL true
#define V8_LITE_BOOL false
#define V8_SHARED_RO_HEAP_BOOL true
#define V8_SHARED_RO_HEAP_BOOL false
"enables trade-off of performance for memory savings")
// Lite mode implies other flags to trade-off performance for memory.
DEFINE_IMPLICATION(lite_mode, jitless)
DEFINE_IMPLICATION(lite_mode, lazy_feedback_allocation)
DEFINE_IMPLICATION(lite_mode, optimize_for_size)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, inline_new)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, allocation_site_pretenuring)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, turbo_allocation_folding)
"Use third-party heap")
"disable write barriers when GC is non-incremental "
"and heap contains single generation.")
// Disable incremental marking barriers
DEFINE_NEG_IMPLICATION(disable_write_barriers, incremental_marking)
"always use full write barriers")
#define V8_GENERATION_BOOL true
#define V8_GENERATION_BOOL false
single_generation, V8_GENERATION_BOOL,
"allocate all objects from young generation to old generation")
// Prevent inline allocation into new space
DEFINE_NEG_IMPLICATION(single_generation, inline_new)
DEFINE_NEG_IMPLICATION(single_generation, turbo_allocation_folding)
"use conservative stack scanning")
#define FUTURE_BOOL true
#define FUTURE_BOOL false
"Implies all staged features that we want to ship in the "
"not-too-far future")
DEFINE_WEAK_IMPLICATION(future, write_protect_code_memory)
DEFINE_WEAK_IMPLICATION(future, finalize_streaming_on_background)
// Flags for jitless
"Disable runtime allocation of executable memory.")
// Jitless V8 has a few implications:
// Field representation tracking is only used by TurboFan.
DEFINE_NEG_IMPLICATION(jitless, track_field_types)
DEFINE_NEG_IMPLICATION(jitless, track_heap_object_fields)
// Regexps are interpreted.
DEFINE_IMPLICATION(jitless, regexp_interpret_all)
// asm.js validation is disabled since it triggers wasm code generation.
DEFINE_NEG_IMPLICATION(jitless, validate_asm)
// --jitless also implies --no-expose-wasm, see InitializeOncePerProcessImpl.
// Unsupported on arm. See
DEFINE_NEG_IMPLICATION(jitless, interpreted_frames_native_stack)
DEFINE_BOOL(assert_types, false,
"generate runtime type assertions to test the typer")
DEFINE_BOOL(trace_code_dependencies, false, "trace code dependencies")
// Depend on --trace-deopt-verbose for reporting dependency invalidations.
DEFINE_IMPLICATION(trace_code_dependencies, trace_deopt_verbose)
// Flags for experimental implementation features.
DEFINE_BOOL(allocation_site_pretenuring, true,
"pretenure with allocation sites")
DEFINE_BOOL(page_promotion, true, "promote pages based on utilization")
DEFINE_BOOL_READONLY(always_promote_young_mc, true,
"always promote young objects during mark-compact")
DEFINE_INT(page_promotion_threshold, 70,
"min percentage of live bytes on a page to enable fast evacuation")
DEFINE_BOOL(trace_pretenuring, false,
"trace pretenuring decisions of HAllocate instructions")
DEFINE_BOOL(trace_pretenuring_statistics, false,
"trace allocation site pretenuring statistics")
DEFINE_BOOL(track_fields, true, "track fields with only smi values")
DEFINE_BOOL(track_double_fields, true, "track fields with double values")
DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
DEFINE_IMPLICATION(track_double_fields, track_fields)
DEFINE_IMPLICATION(track_heap_object_fields, track_fields)
DEFINE_IMPLICATION(track_computed_fields, track_fields)
DEFINE_BOOL(track_field_types, true, "track field types")
DEFINE_IMPLICATION(track_field_types, track_fields)
DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
DEFINE_BOOL(trace_block_coverage, false,
"trace collected block coverage information")
DEFINE_BOOL(trace_protector_invalidation, false,
"trace protector cell invalidations")
DEFINE_BOOL(feedback_normalization, false,
"feed back normalization to constructors")
// TODO(jkummerow): This currently adds too much load on the stub cache.
DEFINE_BOOL_READONLY(internalize_on_the_fly, true,
"internalize string keys for generic keyed ICs on the fly")
// Flag for one shot optimiztions.
DEFINE_BOOL(enable_one_shot_optimization, false,
"Enable size optimizations for the code that will "
"only be executed once")
// Flag for sealed, frozen elements kind instead of dictionary elements kind
DEFINE_BOOL_READONLY(enable_sealed_frozen_elements_kind, true,
"Enable sealed, frozen elements kind")
// Flags for data representation optimizations
DEFINE_BOOL(unbox_double_arrays, true, "automatically unbox arrays of doubles")
DEFINE_BOOL_READONLY(string_slices, true, "use string slices")
DEFINE_INT(interrupt_budget, 144 * KB,
"interrupt budget which should be used for the profiler counter")
// Flags for inline caching and feedback vectors.
DEFINE_BOOL(use_ic, true, "use inline caching")
DEFINE_INT(budget_for_feedback_vector_allocation, 1 * KB,
"The budget in amount of bytecode executed by a function before we "
"decide to allocate feedback vectors")
DEFINE_BOOL(lazy_feedback_allocation, true, "Allocate feedback vectors lazily")
// Flags for Ignition.
DEFINE_BOOL(ignition_elide_noneffectful_bytecodes, true,
"elide bytecodes which won't have any external effect")
DEFINE_BOOL(ignition_reo, true, "use ignition register equivalence optimizer")
DEFINE_BOOL(ignition_filter_expression_positions, true,
"filter expression positions before the bytecode pipeline")
DEFINE_BOOL(ignition_share_named_property_feedback, true,
"share feedback slots when loading the same named property from "
"the same object")
DEFINE_BOOL(print_bytecode, false,
"print bytecode generated by ignition interpreter")
DEFINE_BOOL(enable_lazy_source_positions, V8_LAZY_SOURCE_POSITIONS_BOOL,
"skip generating source positions during initial compile but "
"regenerate when actually required")
DEFINE_BOOL(stress_lazy_source_positions, false,
"collect lazy source positions immediately after lazy compile")
DEFINE_STRING(print_bytecode_filter, "*",
"filter for selecting which functions to print bytecode")
DEFINE_BOOL(trace_ignition, false,
"trace the bytecodes executed by the ignition interpreter")
trace_feedback_updates, false,
"trace updates to feedback vectors during ignition interpreter execution.")
DEFINE_BOOL(trace_ignition_codegen, false,
"trace the codegen of ignition interpreter bytecode handlers")
DEFINE_BOOL(trace_ignition_dispatches, false,
"traces the dispatches to bytecode handlers by the ignition "
DEFINE_STRING(trace_ignition_dispatches_output_file, nullptr,
"the file to which the bytecode handler dispatch table is "
"written (by default, the table is not written to a file)")
DEFINE_BOOL(fast_math, true, "faster (but maybe less accurate) math functions")
DEFINE_BOOL(trace_track_allocation_sites, false,
"trace the tracking of allocation sites")
DEFINE_BOOL(trace_migration, false, "trace object migration")
DEFINE_BOOL(trace_generalization, false, "trace map generalization")
// Flags for TurboProp.
DEFINE_BOOL(turboprop, false, "enable experimental turboprop mid-tier compiler")
DEFINE_BOOL(turboprop_mid_tier_reg_alloc, true,
"enable mid-tier register allocator for turboprop")
DEFINE_BOOL(turboprop_dynamic_map_checks, false,
"use dynamic map checks when generating code for property accesses "
"if all handlers in an IC are the same for turboprop")
DEFINE_BOOL(turboprop_as_midtier, false,
"enable experimental turboprop mid-tier compiler")
DEFINE_IMPLICATION(turboprop_as_midtier, turboprop)
DEFINE_IMPLICATION(turboprop, concurrent_inlining)
DEFINE_VALUE_IMPLICATION(turboprop, interrupt_budget, 15 * KB)
DEFINE_VALUE_IMPLICATION(turboprop, reuse_opt_code_count, 2)
DEFINE_UINT_READONLY(max_minimorphic_map_checks, 4,
"max number of map checks to perform in minimorphic state")
// Since Turboprop uses much lower value for interrupt budget, we need to wait
// for a higher number of ticks to tierup to Turbofan roughly match the default.
// The default of 10 is approximately the ration of TP to TF interrupt budget.
DEFINE_INT(ticks_scale_factor_for_top_tier, 10,
"scale factor for profiler ticks when tiering up from midtier")
// Flags for concurrent recompilation.
DEFINE_BOOL(concurrent_recompilation, true,
"optimizing hot functions asynchronously on a separate thread")
DEFINE_BOOL(trace_concurrent_recompilation, false,
"track concurrent recompilation")
DEFINE_INT(concurrent_recompilation_queue_length, 8,
"the length of the concurrent compilation queue")
DEFINE_INT(concurrent_recompilation_delay, 0,
"artificial compilation delay in ms")
DEFINE_BOOL(block_concurrent_recompilation, false,
"block queued jobs until released")
DEFINE_BOOL(concurrent_inlining, false,
"run optimizing compiler's inlining phase on a separate thread")
DEFINE_BOOL(turbo_direct_heap_access, false,
"access kNeverSerialized objects directly from the heap")
DEFINE_IMPLICATION(concurrent_inlining, turbo_direct_heap_access)
DEFINE_INT(max_serializer_nesting, 25,
"maximum levels for nesting child serializers")
DEFINE_WEAK_IMPLICATION(future, concurrent_inlining)
DEFINE_BOOL(trace_heap_broker_verbose, false,
"trace the heap broker verbosely (all reports)")
DEFINE_BOOL(trace_heap_broker_memory, false,
"trace the heap broker memory (refs analysis and zone numbers)")
DEFINE_BOOL(trace_heap_broker, false,
"trace the heap broker (reports on missing data only)")
DEFINE_IMPLICATION(trace_heap_broker_verbose, trace_heap_broker)
DEFINE_IMPLICATION(trace_heap_broker_memory, trace_heap_broker)
// Flags for stress-testing the compiler.
DEFINE_INT(stress_runs, 0, "number of stress runs")
DEFINE_INT(deopt_every_n_times, 0,
"deoptimize every n times a deopt point is passed")
DEFINE_BOOL(print_deopt_stress, false, "print number of possible deopt points")
// Flags for TurboFan.
DEFINE_BOOL(opt, true, "use adaptive optimizations")
DEFINE_BOOL(turbo_sp_frame_access, false,
"use stack pointer-relative access to frame wherever possible")
stress_turbo_late_spilling, false,
"optimize placement of all spill instructions, not just loop-top phis")
DEFINE_STRING(turbo_filter, "*", "optimization filter for TurboFan compiler")
DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
DEFINE_STRING(trace_turbo_path, nullptr,
"directory to dump generated TurboFan IR to")
DEFINE_STRING(trace_turbo_filter, "*",
"filter for tracing turbofan compilation")
DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
DEFINE_BOOL(trace_turbo_scheduled, false, "trace TurboFan IR with schedule")
DEFINE_IMPLICATION(trace_turbo_scheduled, trace_turbo_graph)
DEFINE_STRING(trace_turbo_cfg_file, nullptr,
"trace turbo cfg graph (for C1 visualizer) to a given file name")
DEFINE_BOOL(trace_turbo_types, true, "trace TurboFan's types")
DEFINE_BOOL(trace_turbo_scheduler, false, "trace TurboFan's scheduler")
DEFINE_BOOL(trace_turbo_reduction, false, "trace TurboFan's various reducers")
DEFINE_BOOL(trace_turbo_trimming, false, "trace TurboFan's graph trimmer")
DEFINE_BOOL(trace_turbo_jt, false, "trace TurboFan's jump threading")
DEFINE_BOOL(trace_turbo_ceq, false, "trace TurboFan's control equivalence")
DEFINE_BOOL(trace_turbo_loop, false, "trace TurboFan's loop optimizations")
DEFINE_BOOL(trace_turbo_alloc, false, "trace TurboFan's register allocator")
DEFINE_BOOL(trace_all_uses, false, "trace all use positions")
DEFINE_BOOL(trace_representation, false, "trace representation types")
trace_turbo_stack_accesses, false,
"trace stack load/store counters for optimized code in run-time (x64 only)")
DEFINE_BOOL(turbo_verify, DEBUG_BOOL, "verify TurboFan graphs at each phase")
DEFINE_STRING(turbo_verify_machine_graph, nullptr,
"verify TurboFan machine graph before instruction selection")
"verify TurboFan machine graph of code stubs")
// Define the flag as read-only-false so that code still compiles even in the
// non-ENABLE_VERIFY_CSA configuration.
DEFINE_BOOL_READONLY(verify_csa, false,
"verify TurboFan machine graph of code stubs")
DEFINE_BOOL(trace_verify_csa, false, "trace code stubs verification")
DEFINE_STRING(csa_trap_on_node, nullptr,
"trigger break point when a node with given id is created in "
"given stub. The format is: StubName,NodeId")
DEFINE_BOOL_READONLY(fixed_array_bounds_checks, true,
"enable FixedArray bounds checks")
DEFINE_BOOL(turbo_stats, false, "print TurboFan statistics")
DEFINE_BOOL(turbo_stats_nvp, false,
"print TurboFan statistics in machine-readable format")
DEFINE_BOOL(turbo_stats_wasm, false,
"print TurboFan statistics of wasm compilations")
DEFINE_BOOL(turbo_splitting, true, "split nodes during scheduling in TurboFan")
DEFINE_BOOL(function_context_specialization, false,
"enable function context specialization in TurboFan")
DEFINE_BOOL(turbo_inlining, true, "enable inlining in TurboFan")
DEFINE_INT(max_inlined_bytecode_size, 500,
"maximum size of bytecode for a single inlining")
DEFINE_INT(max_inlined_bytecode_size_cumulative, 1000,
"maximum cumulative size of bytecode considered for inlining")
DEFINE_INT(max_inlined_bytecode_size_absolute, 5000,
"maximum cumulative size of bytecode considered for inlining")
DEFINE_FLOAT(reserve_inline_budget_scale_factor, 1.2,
"maximum cumulative size of bytecode considered for inlining")
DEFINE_INT(max_inlined_bytecode_size_small, 30,
"maximum size of bytecode considered for small function inlining")
DEFINE_INT(max_optimized_bytecode_size, 60 * KB,
"maximum bytecode size to "
"be considered for optimization; too high values may cause "
"the compiler to hit (release) assertions")
DEFINE_FLOAT(min_inlining_frequency, 0.15, "minimum frequency for inlining")
DEFINE_BOOL(polymorphic_inlining, true, "polymorphic inlining")
DEFINE_BOOL(stress_inline, false,
"set high thresholds for inlining to inline as much as possible")
DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size, 999999)
DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size_cumulative,
DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size_absolute,
DEFINE_VALUE_IMPLICATION(stress_inline, min_inlining_frequency, 0)
DEFINE_IMPLICATION(stress_inline, polymorphic_inlining)
DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
DEFINE_BOOL(turbo_inline_array_builtins, true,
"inline array builtins in TurboFan code")
DEFINE_BOOL(use_osr, true, "use on-stack replacement")
DEFINE_BOOL(trace_osr, false, "trace on-stack replacement")
DEFINE_BOOL(analyze_environment_liveness, true,
"analyze liveness of environment slots and zap dead values")
DEFINE_BOOL(trace_environment_liveness, false,
"trace liveness of local variable slots")
DEFINE_BOOL(turbo_load_elimination, true, "enable load elimination in TurboFan")
DEFINE_BOOL(trace_turbo_load_elimination, false,
"trace TurboFan load elimination")
DEFINE_BOOL(turbo_profiling, false, "enable basic block profiling in TurboFan")
DEFINE_BOOL(turbo_profiling_verbose, false,
"enable basic block profiling in TurboFan, and include each "
"function's schedule and disassembly in the output")
DEFINE_IMPLICATION(turbo_profiling_verbose, turbo_profiling)
DEFINE_BOOL(turbo_profiling_log_builtins, false,
"emit data about basic block usage in builtins to v8.log (requires "
"that V8 was built with v8_enable_builtins_profiling=true)")
DEFINE_BOOL(turbo_verify_allocation, DEBUG_BOOL,
"verify register allocation in TurboFan")
DEFINE_BOOL(turbo_move_optimization, true, "optimize gap moves in TurboFan")
DEFINE_BOOL(turbo_jt, true, "enable jump threading in TurboFan")
DEFINE_BOOL(turbo_loop_peeling, true, "Turbofan loop peeling")
DEFINE_BOOL(turbo_loop_variable, true, "Turbofan loop variable optimization")
DEFINE_BOOL(turbo_loop_rotation, true, "Turbofan loop rotation")
DEFINE_BOOL(turbo_cf_optimization, true, "optimize control flow in TurboFan")
DEFINE_BOOL(turbo_escape, true, "enable escape analysis")
DEFINE_BOOL(turbo_allocation_folding, true, "Turbofan allocation folding")
DEFINE_BOOL(turbo_instruction_scheduling, false,
"enable instruction scheduling in TurboFan")
DEFINE_BOOL(turbo_stress_instruction_scheduling, false,
"randomly schedule instructions to stress dependency tracking")
DEFINE_BOOL(turbo_store_elimination, true,
"enable store-store elimination in TurboFan")
DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
DEFINE_BOOL(turbo_rewrite_far_jumps, true,
"rewrite far to near jumps (ia32,x64)")
stress_gc_during_compilation, false,
"simulate GC/compiler thread race related to")
DEFINE_BOOL(turbo_fast_api_calls, false, "enable fast API calls from TurboFan")
DEFINE_INT(reuse_opt_code_count, 0,
"don't discard optimized code for the specified number of deopts.")
// Native context independent (NCI) code.
DEFINE_BOOL(turbo_nci, false,
"enable experimental native context independent code.")
// TODO(v8:8888): Temporary until NCI caching is implemented or
// feedback collection is made unconditional.
DEFINE_IMPLICATION(turbo_nci, turbo_collect_feedback_in_generic_lowering)
DEFINE_BOOL(turbo_nci_as_midtier, false,
"insert NCI as a midtier compiler for testing purposes.")
DEFINE_BOOL(print_nci_code, false, "print native context independent code.")
DEFINE_BOOL(trace_turbo_nci, false, "trace native context independent code.")
DEFINE_BOOL(turbo_collect_feedback_in_generic_lowering, true,
"enable experimental feedback collection in generic lowering.")
// TODO(jgruber,v8:8888): Remove this flag once we've settled on a codegen
// strategy.
DEFINE_BOOL(turbo_nci_delayed_codegen, true,
"delay NCI codegen to reduce useless compilation work.")
// TODO(jgruber,v8:8888): Remove this flag once we've settled on an ageing
// strategy.
DEFINE_BOOL(turbo_nci_cache_ageing, false,
"enable ageing of the NCI code cache.")
// TODO(jgruber,v8:8888): Remove this flag once we've settled on an ageing
// strategy.
DEFINE_BOOL(isolate_script_cache_ageing, true,
"enable ageing of the isolate script cache.")
// Favor memory over execution speed.
DEFINE_BOOL(optimize_for_size, false,
"Enables optimizations which favor memory size over execution "
DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
"Enable mitigations for executing untrusted code")
// Flags for native WebAssembly.
DEFINE_BOOL(wasm_generic_wrapper, false,
"use generic js-to-wasm wrapper instead of per-signature wrappers")
DEFINE_BOOL(expose_wasm, true, "expose wasm interface to JavaScript")
DEFINE_INT(wasm_num_compilation_tasks, 128,
"maximum number of parallel compilation tasks for wasm")
DEFINE_DEBUG_BOOL(trace_wasm_native_heap, false,
"trace wasm native heap events")
DEFINE_BOOL(wasm_write_protect_code_memory, false,
"write protect code memory on the wasm native heap")
DEFINE_DEBUG_BOOL(trace_wasm_serialization, false,
"trace serialization/deserialization")
DEFINE_BOOL(wasm_async_compilation, true,
"enable actual asynchronous compilation for WebAssembly.compile")
DEFINE_BOOL(wasm_test_streaming, false,
"use streaming compilation instead of async compilation for tests")
DEFINE_UINT(wasm_max_mem_pages, v8::internal::wasm::kSpecMaxMemoryPages,
"maximum number of 64KiB memory pages per wasm memory")
DEFINE_UINT(wasm_max_table_size, v8::internal::wasm::kV8MaxWasmTableSize,
"maximum table size of a wasm instance")
DEFINE_UINT(wasm_max_code_space, v8::internal::kMaxWasmCodeMB,
"maximum committed code space for wasm (in MB)")
DEFINE_BOOL(wasm_tier_up, true,
"enable tier up to the optimizing compiler (requires --liftoff to "
"have an effect)")
DEFINE_BOOL(wasm_dynamic_tiering, false,
"enable dynamic tier up to the optimizing compiler")
DEFINE_DEBUG_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
DEFINE_DEBUG_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
DEFINE_DEBUG_BOOL(trace_wasm_interpreter, false,
"trace interpretation of wasm code")
DEFINE_DEBUG_BOOL(trace_wasm_streaming, false,
"trace streaming compilation of wasm code")
DEFINE_INT(trace_wasm_ast_start, 0,
"start function for wasm AST trace (inclusive)")
DEFINE_INT(trace_wasm_ast_end, 0, "end function for wasm AST trace (exclusive)")
DEFINE_BOOL(liftoff, true,
"enable Liftoff, the baseline compiler for WebAssembly")
DEFINE_BOOL(experimental_liftoff_extern_ref, false,
"enable support for externref in Liftoff")
// We can't tier up (from Liftoff to TurboFan) in single-threaded mode, hence
// disable Liftoff in that configuration for now. The alternative is disabling
// TurboFan, which would reduce peak performance considerably.
// Note that for debugging, Liftoff will still be used.
DEFINE_NEG_IMPLICATION(single_threaded, liftoff)
DEFINE_DEBUG_BOOL(trace_liftoff, false,
"trace Liftoff, the baseline compiler for WebAssembly")
DEFINE_BOOL(trace_wasm_memory, false,
"print all memory updates performed in wasm code")
// Fuzzers use {wasm_tier_mask_for_testing} together with {liftoff} and
// {no_wasm_tier_up} to force some functions to be compiled with Turbofan.
DEFINE_INT(wasm_tier_mask_for_testing, 0,
"bitmask of functions to compile with TurboFan instead of Liftoff")
DEFINE_BOOL(wasm_expose_debug_eval, true,
"Expose wasm evaluator support on the CDP")
DEFINE_BOOL(validate_asm, true, "validate asm.js modules before compiling")
DEFINE_BOOL(suppress_asm_messages, false,
"don't emit asm.js related messages (for golden file testing)")
DEFINE_BOOL(trace_asm_time, false, "log asm.js timing info to the console")
DEFINE_BOOL(trace_asm_scanner, false,
"log tokens encountered by asm.js scanner")
DEFINE_BOOL(trace_asm_parser, false, "verbose logging of asm.js parse failures")
DEFINE_BOOL(stress_validate_asm, false, "try to validate everything as asm.js")
DEFINE_DEBUG_BOOL(dump_wasm_module, false, "dump wasm module bytes")
DEFINE_STRING(dump_wasm_module_path, nullptr,
"directory to dump wasm modules to")
// Declare command-line flags for Wasm features. Warning: avoid using these
// flags directly in the implementation. Instead accept wasm::WasmFeatures
// for configurability.
#include "src/wasm/wasm-feature-flags.h"
#define DECL_WASM_FLAG(feat, desc, val) \
DEFINE_BOOL(experimental_wasm_##feat, val, \
"enable prototype " desc " for wasm")
DEFINE_IMPLICATION(experimental_wasm_gc, experimental_wasm_typed_funcref)
DEFINE_IMPLICATION(experimental_wasm_typed_funcref, experimental_wasm_reftypes)
DEFINE_BOOL(wasm_staging, false, "enable staged wasm features")
#define WASM_STAGING_IMPLICATION(feat, desc, val) \
DEFINE_IMPLICATION(wasm_staging, experimental_wasm_##feat)
DEFINE_BOOL(wasm_opt, true, "enable wasm optimization")
wasm_bounds_checks, true,
"enable bounds checks (disable for performance testing only)")
DEFINE_BOOL(wasm_stack_checks, true,
"enable stack checks (disable for performance testing only)")
DEFINE_BOOL(wasm_math_intrinsics, true,
"intrinsify some Math imports into wasm")
DEFINE_BOOL(wasm_trap_handler, true,
"use signal handlers to catch out of bounds memory access in wasm"
" (currently Linux x86_64 only)")
DEFINE_BOOL(wasm_fuzzer_gen_test, false,
"generate a test case when running a wasm fuzzer")
DEFINE_IMPLICATION(wasm_fuzzer_gen_test, single_threaded)
DEFINE_BOOL(print_wasm_code, false, "print WebAssembly code")
DEFINE_INT(print_wasm_code_function_index, -1,
"print WebAssembly code for function at index")
DEFINE_BOOL(print_wasm_stub_code, false, "print WebAssembly stub code")
DEFINE_BOOL(asm_wasm_lazy_compilation, false,
"enable lazy compilation for asm-wasm modules")
DEFINE_IMPLICATION(validate_asm, asm_wasm_lazy_compilation)
DEFINE_BOOL(wasm_lazy_compilation, false,
"enable lazy compilation for all wasm modules")
DEFINE_DEBUG_BOOL(trace_wasm_lazy_compilation, false,
"trace lazy compilation of wasm functions")
DEFINE_BOOL(wasm_lazy_validation, false,
"enable lazy validation for lazily compiled wasm functions")
DEFINE_BOOL(wasm_grow_shared_memory, true,
"allow growing shared WebAssembly memory objects")
DEFINE_BOOL(wasm_simd_post_mvp, false,
"allow experimental SIMD operations for prototyping that are not "
"included in the current proposal")
DEFINE_IMPLICATION(wasm_simd_post_mvp, experimental_wasm_simd)
DEFINE_BOOL(wasm_code_gc, true, "enable garbage collection of wasm code")
DEFINE_BOOL(trace_wasm_code_gc, false, "trace garbage collection of wasm code")
DEFINE_BOOL(stress_wasm_code_gc, false,
"stress test garbage collection of wasm code")
DEFINE_INT(wasm_max_initial_code_space_reservation, 0,
"maximum size of the initial wasm code space reservation (in MB)")
DEFINE_BOOL(experimental_wasm_allow_huge_modules, false,
"allow wasm modules bigger than 1GB, but below ~2GB")
// Profiler flags.
DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
DEFINE_INT(stress_sampling_allocation_profiler, 0,
"Enables sampling allocation profiler with X as a sample interval")
// Garbage collections flags.
DEFINE_BOOL(lazy_new_space_shrinking, false,
"Enables the lazy new space shrinking strategy")
DEFINE_SIZE_T(min_semi_space_size, 0,
"min size of a semi-space (in MBytes), the new space consists of "
"two semi-spaces")
DEFINE_SIZE_T(max_semi_space_size, 0,
"max size of a semi-space (in MBytes), the new space consists of "
"two semi-spaces")
DEFINE_INT(semi_space_growth_factor, 2, "factor by which to grow the new space")
DEFINE_SIZE_T(max_old_space_size, 0, "max size of the old space (in Mbytes)")
max_heap_size, 0,
"max size of the heap (in Mbytes) "
"both max_semi_space_size and max_old_space_size take precedence. "
"All three flags cannot be specified at the same time.")
DEFINE_SIZE_T(initial_heap_size, 0, "initial size of the heap (in Mbytes)")
DEFINE_BOOL(huge_max_old_generation_size, true,
"Increase max size of the old space to 4 GB for x64 systems with"
"the physical memory bigger than 16 GB")
DEFINE_SIZE_T(initial_old_space_size, 0, "initial old space size (in Mbytes)")
DEFINE_BOOL(global_gc_scheduling, true,
"enable GC scheduling based on global memory")
DEFINE_BOOL(gc_global, false, "always perform global GCs")
DEFINE_INT(random_gc_interval, 0,
"Collect garbage after random(0, X) allocations. It overrides "
DEFINE_INT(gc_interval, -1, "garbage collect after <n> allocations")
DEFINE_INT(retain_maps_for_n_gc, 2,
"keeps maps alive for <n> old space garbage collections")
DEFINE_BOOL(trace_gc, false,
"print one trace line following each garbage collection")
DEFINE_BOOL(trace_gc_nvp, false,
"print one detailed trace line in name=value format "
"after each garbage collection")
DEFINE_BOOL(trace_gc_ignore_scavenger, false,
"do not print trace line after scavenger collection")
DEFINE_BOOL(trace_idle_notification, false,
"print one trace line following each idle notification")
DEFINE_BOOL(trace_idle_notification_verbose, false,
"prints the heap state used by the idle notification")
DEFINE_BOOL(trace_gc_verbose, false,
"print more details following each garbage collection")
DEFINE_IMPLICATION(trace_gc_verbose, trace_gc)
DEFINE_BOOL(trace_gc_freelists, false,
"prints details of each freelist before and after "
"each major garbage collection")
DEFINE_BOOL(trace_gc_freelists_verbose, false,
"prints details of freelists of each page before and after "
"each major garbage collection")
DEFINE_IMPLICATION(trace_gc_freelists_verbose, trace_gc_freelists)
DEFINE_BOOL(trace_evacuation_candidates, false,
"Show statistics about the pages evacuation by the compaction")
trace_allocations_origins, false,
"Show statistics about the origins of allocations. "
"Combine with --no-inline-new to track allocations from generated code")
DEFINE_INT(trace_allocation_stack_interval, -1,
"print stack trace after <n> free-list allocations")
DEFINE_INT(trace_duplicate_threshold_kb, 0,
"print duplicate objects in the heap if their size is more than "
"given threshold")
DEFINE_BOOL(trace_fragmentation, false, "report fragmentation for old space")
DEFINE_BOOL(trace_fragmentation_verbose, false,
"report fragmentation for old space (detailed)")
DEFINE_BOOL(minor_mc_trace_fragmentation, false,
"trace fragmentation after marking")
DEFINE_BOOL(trace_evacuation, false, "report evacuation statistics")
DEFINE_BOOL(trace_mutator_utilization, false,
"print mutator utilization, allocation speed, gc speed")
DEFINE_BOOL(incremental_marking, true, "use incremental marking")
DEFINE_BOOL(incremental_marking_wrappers, true,
"use incremental marking for marking wrappers")
DEFINE_BOOL(incremental_marking_task, true, "use tasks for incremental marking")
DEFINE_INT(incremental_marking_soft_trigger, 0,
"threshold for starting incremental marking via a task in percent "
"of available space: limit - size")
DEFINE_INT(incremental_marking_hard_trigger, 0,
"threshold for starting incremental marking immediately in percent "
"of available space: limit - size")
DEFINE_BOOL(trace_unmapper, false, "Trace the unmapping")
DEFINE_BOOL(parallel_scavenge, true, "parallel scavenge")
DEFINE_BOOL(scavenge_task, true, "schedule scavenge tasks")
DEFINE_INT(scavenge_task_trigger, 80,
"scavenge task trigger in percent of the current heap limit")
DEFINE_BOOL(scavenge_separate_stack_scanning, false,
"use a separate phase for stack scanning in scavenge")
DEFINE_BOOL(trace_parallel_scavenge, false, "trace parallel scavenge")
DEFINE_BOOL(write_protect_code_memory, true, "write protect code memory")
"use concurrent marking")
DEFINE_BOOL(concurrent_array_buffer_sweeping, true,
"concurrently sweep array buffers")
DEFINE_BOOL(concurrent_allocation, true, "concurrently allocate in old space")
DEFINE_BOOL(stress_concurrent_allocation, false,
"start background threads that allocate memory")
DEFINE_BOOL(local_heaps, true, "allow heap access from background tasks")
// Since the local_heaps flag is enabled by default, we defined reverse
// implications to simplify disabling the flag.
DEFINE_NEG_NEG_IMPLICATION(local_heaps, turbo_direct_heap_access)
DEFINE_NEG_NEG_IMPLICATION(local_heaps, concurrent_inlining)
DEFINE_NEG_NEG_IMPLICATION(local_heaps, concurrent_allocation)
DEFINE_NEG_NEG_IMPLICATION(concurrent_allocation, stress_concurrent_allocation)
"use parallel marking in atomic pause")
DEFINE_INT(ephemeron_fixpoint_iterations, 10,
"number of fixpoint iterations it takes to switch to linear "
"ephemeron algorithm")
DEFINE_BOOL(trace_concurrent_marking, false, "trace concurrent marking")
DEFINE_BOOL(concurrent_store_buffer, true,
"use concurrent store buffer processing")
DEFINE_BOOL(concurrent_sweeping, true, "use concurrent sweeping")
DEFINE_BOOL(parallel_compaction, true, "use parallel compaction")
DEFINE_BOOL(parallel_pointer_update, true,
"use parallel pointer update during compaction")
DEFINE_BOOL(detect_ineffective_gcs_near_heap_limit, true,
"trigger out-of-memory failure to avoid GC storm near heap limit")
DEFINE_BOOL(trace_incremental_marking, false,
"trace progress of the incremental marking")
DEFINE_BOOL(trace_stress_marking, false, "trace stress marking progress")
DEFINE_BOOL(trace_stress_scavenge, false, "trace stress scavenge progress")
DEFINE_BOOL(track_gc_object_stats, false,
"track object counts and memory usage")
DEFINE_BOOL(trace_gc_object_stats, false,
"trace object counts and memory usage")
DEFINE_BOOL(trace_zone_stats, false, "trace zone memory usage")
zone_stats_tolerance, 1 * MB,
"report a tick only when allocated zone memory changes by this amount")
DEFINE_BOOL(trace_zone_type_stats, false, "trace per-type zone memory usage")
DEFINE_BOOL(track_retaining_path, false,
"enable support for tracking retaining path")
DEFINE_DEBUG_BOOL(trace_backing_store, false, "trace backing store events")
DEFINE_BOOL(concurrent_array_buffer_freeing, true,
"free array buffer allocations on a background thread")
DEFINE_INT(gc_stats, 0, "Used by tracing internally to enable gc statistics")
DEFINE_IMPLICATION(trace_gc_object_stats, track_gc_object_stats)
DEFINE_NEG_IMPLICATION(trace_gc_object_stats, incremental_marking)
DEFINE_NEG_IMPLICATION(track_retaining_path, incremental_marking)
DEFINE_NEG_IMPLICATION(track_retaining_path, parallel_marking)
DEFINE_NEG_IMPLICATION(track_retaining_path, concurrent_marking)
DEFINE_BOOL(track_detached_contexts, true,
"track native contexts that are expected to be garbage collected")
DEFINE_BOOL(trace_detached_contexts, false,
"trace native contexts that are expected to be garbage collected")
DEFINE_IMPLICATION(trace_detached_contexts, track_detached_contexts)
DEFINE_BOOL(verify_heap, false, "verify heap pointers before and after GC")
DEFINE_BOOL(verify_heap_skip_remembered_set, false,
"disable remembered set verification")
DEFINE_BOOL(move_object_start, true, "enable moving of object starts")
DEFINE_BOOL(memory_reducer, true, "use memory reducer")
DEFINE_BOOL(memory_reducer_for_small_heaps, true,
"use memory reducer for small heaps")
DEFINE_INT(heap_growing_percent, 0,
"specifies heap growing factor as (1 + heap_growing_percent/100)")
DEFINE_INT(v8_os_page_size, 0, "override OS page size (in KBytes)")
DEFINE_BOOL(always_compact, false, "Perform compaction on every full GC")
DEFINE_BOOL(never_compact, false,
"Never perform compaction on full GC - testing only")
DEFINE_BOOL(compact_code_space, true, "Compact code space on full collections")
DEFINE_BOOL(flush_bytecode, true,
"flush of bytecode when it has not been executed recently")
DEFINE_BOOL(stress_flush_bytecode, false, "stress bytecode flushing")
DEFINE_BOOL(trace_flush_bytecode, false, "trace bytecode flushing")
DEFINE_IMPLICATION(stress_flush_bytecode, flush_bytecode)
DEFINE_BOOL(use_marking_progress_bar, true,
"Use a progress bar to scan large objects in increments when "
"incremental marking is active.")
DEFINE_BOOL(stress_per_context_marking_worklist, false,
"Use per-context worklist for marking")
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 "
DEFINE_BOOL(stress_compaction_random, false,
"Stress GC compaction by selecting random percent of pages as "
"evacuation candidates. It overrides stress_compaction.")
DEFINE_BOOL(stress_incremental_marking, false,
"force incremental marking for small heaps and run it more often")
DEFINE_BOOL(fuzzer_gc_analysis, false,
"prints number of allocations and enables analysis mode for gc "
"fuzz testing, e.g. --stress-marking, --stress-scavenge")
DEFINE_INT(stress_marking, 0,
"force marking at random points between 0 and X (inclusive) percent "
"of the regular marking start limit")
DEFINE_INT(stress_scavenge, 0,
"force scavenge at random points between 0 and X (inclusive) "
"percent of the new space capacity")
DEFINE_VALUE_IMPLICATION(fuzzer_gc_analysis, stress_marking, 99)
DEFINE_VALUE_IMPLICATION(fuzzer_gc_analysis, stress_scavenge, 99)
reclaim_unmodified_wrappers, true,
"reclaim otherwise unreachable unmodified wrapper objects when possible")
// These flags will be removed after experiments. Do not rely on them.
DEFINE_BOOL(gc_experiment_background_schedule, false,
"new background GC schedule heuristics")
DEFINE_BOOL(gc_experiment_less_compaction, false,
"less compaction in non-memory reducing mode")
DEFINE_BOOL(gc_experiment_reduce_concurrent_marking_tasks, false,
"reduce the number of concurrent marking tasks")
DEFINE_BOOL(disable_abortjs, false, "disables AbortJS runtime function")
DEFINE_BOOL(randomize_all_allocations, false,
"randomize virtual memory reservations by ignoring any hints "
"passed when allocating pages")
DEFINE_BOOL(manual_evacuation_candidates_selection, false,
"Test mode only flag. It allows an unit test to select evacuation "
"candidates pages (requires --stress_compaction).")
DEFINE_BOOL(fast_promotion_new_space, false,
"fast promote new space on high survival rates")
DEFINE_BOOL(clear_free_memory, false, "initialize free memory with 0")
young_generation_large_objects, true,
"allocates large objects by default in the young generation large "
"object space")
// / / /
"generate extra code (assertions) for debugging")
DEFINE_BOOL(code_comments, false,
"emit comments in code disassembly; for more readable source "
"positions you should add --no-concurrent_recompilation")
DEFINE_BOOL(enable_sse3, true, "enable use of SSE3 instructions if available")
DEFINE_BOOL(enable_ssse3, true, "enable use of SSSE3 instructions if available")
DEFINE_BOOL(enable_sse4_1, true,
"enable use of SSE4.1 instructions if available")
DEFINE_BOOL(enable_sse4_2, true,
"enable use of SSE4.2 instructions if available")
DEFINE_BOOL(enable_sahf, true,
"enable use of SAHF instruction if available (X64 only)")
DEFINE_BOOL(enable_avx, true, "enable use of AVX instructions if available")
DEFINE_BOOL(enable_fma3, true, "enable use of FMA3 instructions if available")
DEFINE_BOOL(enable_bmi1, true, "enable use of BMI1 instructions if available")
DEFINE_BOOL(enable_bmi2, true, "enable use of BMI2 instructions if available")
DEFINE_BOOL(enable_lzcnt, true, "enable use of LZCNT instruction if available")
DEFINE_BOOL(enable_popcnt, true,
"enable use of POPCNT instruction if available")
"generate instructions for the selected ARM architecture if "
"available: armv6, armv7, armv7+sudiv or armv8")
DEFINE_BOOL(force_long_branches, false,
"force all emitted branches to be in long mode (MIPS/PPC only)")
DEFINE_STRING(mcpu, "auto", "enable optimization for specific cpu")
DEFINE_BOOL(partial_constant_pool, true,
"enable use of partial constant pools (X64 only)")
DEFINE_STRING(sim_arm64_optional_features, "none",
"enable optional features on the simulator for testing: none or "
// Controlling source positions for Torque/CSA code.
DEFINE_BOOL(enable_source_at_csa_bind, false,
"Include source information in the binary at CSA bind locations.")
// Deprecated ARM flags (replaced by arm_arch).
DEFINE_MAYBE_BOOL(enable_armv7, "deprecated (use --arm_arch instead)")
DEFINE_MAYBE_BOOL(enable_vfp3, "deprecated (use --arm_arch instead)")
DEFINE_MAYBE_BOOL(enable_32dregs, "deprecated (use --arm_arch instead)")
DEFINE_MAYBE_BOOL(enable_neon, "deprecated (use --arm_arch instead)")
DEFINE_MAYBE_BOOL(enable_sudiv, "deprecated (use --arm_arch instead)")
DEFINE_MAYBE_BOOL(enable_armv8, "deprecated (use --arm_arch instead)")
// regexp-macro-assembler-*.cc
DEFINE_BOOL(enable_regexp_unaligned_accesses, true,
"enable unaligned accesses for the regexp engine")
DEFINE_BOOL(script_streaming, true, "enable parsing on background")
DEFINE_BOOL(stress_background_compile, false,
"stress test parsing on background")
finalize_streaming_on_background, false,
"perform the script streaming finalization on the background thread")
DEFINE_BOOL(disable_old_api_accessors, false,
"Disable old-style API accessors whose setters trigger through the "
"prototype chain")
DEFINE_BOOL(expose_gc, false, "expose gc extension")
DEFINE_STRING(expose_gc_as, nullptr,
"expose gc extension under the specified name")
DEFINE_IMPLICATION(expose_gc_as, expose_gc)
DEFINE_BOOL(expose_externalize_string, false,
"expose externalize string extension")
DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
DEFINE_BOOL(builtins_in_stack_traces, false,
"show built-in functions in stack traces")
DEFINE_BOOL(experimental_stack_trace_frames, false,
"enable experimental frames (API/Builtins) and stack trace layout")
DEFINE_BOOL(disallow_code_generation_from_strings, false,
"disallow eval and friends")
DEFINE_BOOL(expose_async_hooks, false, "expose async_hooks object")
DEFINE_STRING(expose_cputracemark_as, nullptr,
"expose cputracemark extension under the specified name")
DEFINE_BOOL(enable_vtune_domain_support, true, "enable vtune domain support")
DEFINE_BOOL(allow_unsafe_function_constructor, false,
"allow invoking the function constructor without security checks")
DEFINE_BOOL(force_slow_path, false, "always take the slow path for builtins")
DEFINE_BOOL(test_small_max_function_context_stub_size, false,
"enable testing the function context size overflow path "
"by making the maximum size smaller")
DEFINE_BOOL(inline_new, true, "use fast inline allocation")
DEFINE_NEG_NEG_IMPLICATION(inline_new, turbo_allocation_folding)
// /
DEFINE_BOOL(trace, false, "trace javascript function calls")
DEFINE_BOOL(trace_wasm, false, "trace wasm function calls")
DEFINE_BOOL(lazy, true, "use lazy compilation")
DEFINE_BOOL(max_lazy, false, "ignore eager compilation hints")
DEFINE_IMPLICATION(max_lazy, lazy)
DEFINE_BOOL(trace_opt, false, "trace optimized compilation")
DEFINE_BOOL(trace_opt_verbose, false,
"extra verbose optimized compilation tracing")
DEFINE_IMPLICATION(trace_opt_verbose, trace_opt)
DEFINE_BOOL(trace_opt_stats, false, "trace optimized compilation statistics")
DEFINE_BOOL(trace_deopt, false, "trace deoptimization")
DEFINE_BOOL(trace_deopt_verbose, false, "extra verbose deoptimization tracing")
DEFINE_IMPLICATION(trace_deopt_verbose, trace_deopt)
DEFINE_BOOL(trace_file_names, false,
"include file names in trace-opt/trace-deopt output")
DEFINE_BOOL(always_opt, false, "always try to optimize functions")
DEFINE_BOOL(always_osr, false, "always try to OSR functions")
DEFINE_BOOL(prepare_always_opt, false, "prepare for turning on always opt")
DEFINE_BOOL(trace_serializer, false, "print code serializer trace")
#ifdef DEBUG
DEFINE_BOOL(external_reference_stats, false,
"print statistics on external references used during serialization")
#endif // DEBUG
DEFINE_BOOL(compilation_cache, true, "enable compilation cache")
DEFINE_BOOL(cache_prototype_transitions, true, "cache prototype transitions")
DEFINE_BOOL(parallel_compile_tasks, false, "enable parallel compile tasks")
DEFINE_BOOL(compiler_dispatcher, false, "enable compiler dispatcher")
DEFINE_IMPLICATION(parallel_compile_tasks, compiler_dispatcher)
DEFINE_BOOL(trace_compiler_dispatcher, false,
"trace compiler dispatcher activity")
DEFINE_INT(cpu_profiler_sampling_interval, 1000,
"CPU profiler sampling interval in microseconds")
// debugger
trace_side_effect_free_debug_evaluate, false,
"print debug messages for side-effect-free debug-evaluate for testing")
DEFINE_BOOL(hard_abort, true, "abort by crashing")
// inspector
DEFINE_BOOL(expose_inspector_scripts, false,
"expose injected-script-source.js for debugging")
"default size of stack region v8 is allowed to use (in kBytes)")
DEFINE_INT(max_stack_trace_source_length, 300,
"maximum length of function source code printed in a stack trace.")
DEFINE_BOOL(clear_exceptions_on_js_entry, false,
"clear pending exceptions when entering JavaScript")
DEFINE_INT(histogram_interval, 600000,
"time interval in ms for aggregating memory histograms")
DEFINE_BOOL(heap_profiler_trace_objects, false,
"Dump heap object allocations/movements/size_updates")
DEFINE_BOOL(heap_profiler_use_embedder_graph, true,
"Use the new EmbedderGraph API to get embedder nodes")
DEFINE_INT(heap_snapshot_string_limit, 1024,
"truncate strings to this length in the heap snapshot")
DEFINE_BOOL(sampling_heap_profiler_suppress_randomness, false,
"Use constant sample intervals to eliminate test flakiness")
DEFINE_BOOL(use_idle_notification, true,
"Use idle notification to reduce memory footprint.")
DEFINE_BOOL(trace_ic, false,
"trace inline cache state transitions for tools/ic-processor")
DEFINE_IMPLICATION(trace_ic, log_code)
DEFINE_BOOL_READONLY(fast_map_update, false,
"enable fast map update by caching the migration target")
DEFINE_BOOL(modify_field_representation_inplace, true,
"enable in-place field representation updates")
DEFINE_INT(max_valid_polymorphic_map_count, 4,
"maximum number of valid maps to track in POLYMORPHIC state")
DEFINE_BOOL(native_code_counters, DEBUG_BOOL,
"generate extra code for manipulating stats counters")
DEFINE_BOOL(super_ic, false, "use an IC for super property loads")
DEFINE_BOOL(thin_strings, true, "Enable ThinString support")
DEFINE_BOOL(trace_prototype_users, false,
"Trace updates to prototype user tracking")
DEFINE_BOOL(trace_for_in_enumerate, false, "Trace for-in enumerate slow-paths")
DEFINE_BOOL(trace_maps, false, "trace map creation")
DEFINE_BOOL(trace_maps_details, true, "also log map details")
DEFINE_IMPLICATION(trace_maps, log_code)
DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
DEFINE_BOOL(allow_natives_for_differential_fuzzing, false,
"allow only natives explicitly allowlisted for differential "
DEFINE_IMPLICATION(allow_natives_for_differential_fuzzing, allow_natives_syntax)
DEFINE_IMPLICATION(allow_natives_for_differential_fuzzing, fuzzing)
DEFINE_BOOL(parse_only, false, "only parse the sources")
//, and
DEFINE_BOOL(trace_sim, false, "Trace simulator execution")
DEFINE_BOOL(debug_sim, false, "Enable debugging the simulator")
DEFINE_BOOL(check_icache, false,
"Check icache flushes in ARM and MIPS simulator")
DEFINE_INT(stop_sim_at, 0, "Simulator stop after x number of instructions")
#if defined(V8_TARGET_ARCH_ARM64) || defined(V8_TARGET_ARCH_MIPS64) || \
DEFINE_INT(sim_stack_alignment, 16,
"Stack alignment in bytes in simulator. This must be a power of two "
"and it must be at least 16. 16 is default.")
DEFINE_INT(sim_stack_alignment, 8,
"Stack alingment in bytes in simulator (4 or 8, 8 is default)")
DEFINE_INT(sim_stack_size, 2 * MB / KB,
"Stack size of the ARM64, MIPS, MIPS64 and PPC64 simulator "
"in kBytes (default is 2 MB)")
"When logging, try to use coloured output.")
DEFINE_BOOL(trace_sim_messages, false,
"Trace simulator debug messages. Implied by --trace-sim.")
#if defined V8_TARGET_ARCH_ARM64
DEFINE_DEBUG_BOOL(sim_abort_on_bad_auth, false,
"Stop execution when a pointer authentication fails in the "
"ARM64 simulator.")
DEFINE_BOOL(async_stack_traces, true,
"include async stack traces in Error.stack")
DEFINE_BOOL(stack_trace_on_illegal, false,
"print stack trace when an illegal exception is thrown")
DEFINE_BOOL(abort_on_uncaught_exception, false,
"abort program (dump core) when an uncaught exception is thrown")
DEFINE_BOOL(correctness_fuzzer_suppressions, false,
"Suppress certain unspecified behaviors to ease correctness "
"fuzzing: Abort program when the stack overflows or a string "
"exceeds maximum length (as opposed to throwing RangeError). "
"Use a fixed suppression string for error messages.")
DEFINE_BOOL(randomize_hashes, true,
"randomize hashes to avoid predictable hash collisions "
"(with snapshots this option cannot override the baked-in seed)")
DEFINE_BOOL(rehash_snapshot, true,
"rehash strings from the snapshot to override the baked-in seed")
DEFINE_UINT64(hash_seed, 0,
"Fixed seed to use to hash property keys (0 means random)"
"(with snapshots this option cannot override the baked-in seed)")
DEFINE_INT(random_seed, 0,
"Default seed for initializing random generator "
"(0, the default, means to use system random).")
DEFINE_INT(fuzzer_random_seed, 0,
"Default seed for initializing fuzzer random generator "
"(0, the default, means to use v8's random number generator seed).")
DEFINE_BOOL(trace_rail, false, "trace RAIL mode")
DEFINE_BOOL(print_all_exceptions, false,
"print exception object and stack trace on each thrown exception")
detailed_error_stack_trace, false,
"includes arguments for each function call in the error stack frames array")
DEFINE_BOOL(adjust_os_scheduling_parameters, true,
"adjust OS specific scheduling params for the isolate")
DEFINE_BOOL(experimental_flush_embedded_blob_icache, false,
"Used in an experiment to evaluate icache flushing on certain CPUs")
DEFINE_BOOL(runtime_call_stats, false, "report runtime call counts and times")
DEFINE_BOOL(rcs, false, "report runtime call counts and times")
DEFINE_IMPLICATION(rcs, runtime_call_stats)
DEFINE_BOOL(rcs_cpu_time, false,
"report runtime times in cpu time (the default is wall time)")
DEFINE_IMPLICATION(rcs_cpu_time, rcs)
DEFINE_BOOL(profile_deserialization, false,
"Print the time it takes to deserialize the snapshot.")
DEFINE_BOOL(serialization_statistics, false,
"Collect statistics on serialized objects.")
// Regexp
DEFINE_BOOL(regexp_optimization, true, "generate optimized regexp code")
DEFINE_BOOL(regexp_mode_modifiers, false, "enable inline flags in regexp.")
DEFINE_BOOL(regexp_interpret_all, false, "interpret all regexp code")
DEFINE_BOOL(regexp_tier_up, true,
"enable regexp interpreter and tier up to the compiler after the "
"number of executions set by the tier up ticks flag")
DEFINE_INT(regexp_tier_up_ticks, 1,
"set the number of executions for the regexp interpreter before "
"tiering-up to the compiler")
"enable peephole optimization for regexp bytecode")
DEFINE_BOOL(trace_regexp_peephole_optimization, false,
"trace regexp bytecode peephole optimization")
DEFINE_BOOL(trace_regexp_bytecodes, false, "trace regexp bytecode execution")
DEFINE_BOOL(trace_regexp_assembler, false,
"trace regexp macro assembler calls.")
DEFINE_BOOL(trace_regexp_parser, false, "trace regexp parsing")
DEFINE_BOOL(trace_regexp_tier_up, false, "trace regexp tiering up execution")
DEFINE_BOOL(enable_experimental_regexp_engine, false,
"recognize regexps with 'l' flag, run them on experimental engine")
DEFINE_BOOL(default_to_experimental_regexp_engine, false,
"run regexps with the experimental engine where possible")
DEFINE_BOOL(trace_experimental_regexp_engine, false,
"trace execution of experimental regexp engine")
DEFINE_BOOL(enable_experimental_regexp_engine_on_excessive_backtracks, true,
"fall back to a breadth-first regexp engine on excessive "
DEFINE_UINT(regexp_backtracks_before_fallback, 50000,
"number of backtracks during regexp execution before fall back "
"to experimental engine if "
"enable_experimental_regexp_engine_on_excessive_backtracks is set")
// Testing flags test/cctest/test-{flags,api,serialization}.cc
DEFINE_BOOL(testing_bool_flag, true, "testing_bool_flag")
DEFINE_MAYBE_BOOL(testing_maybe_bool_flag, "testing_maybe_bool_flag")
DEFINE_INT(testing_int_flag, 13, "testing_int_flag")
DEFINE_FLOAT(testing_float_flag, 2.5, "float-flag")
DEFINE_STRING(testing_string_flag, "Hello, world!", "string-flag")
DEFINE_INT(testing_prng_seed, 42, "Seed used for threading test randomness")
// Test flag for a check in %OptimizeFunctionOnNextCall
testing_d8_test_runner, false,
"test runner turns on this flag to enable a check that the function was "
"prepared for optimization before marking it for optimization")
fuzzing, false,
"Fuzzers use this flag to signal that they are ... fuzzing. This causes "
"intrinsics to fail silently (e.g. return undefined) on invalid usage.")
DEFINE_STRING(embedded_src, nullptr,
"Path for the generated embedded data file. (mksnapshot only)")
embedded_variant, nullptr,
"Label to disambiguate symbols in embedded data file. (mksnapshot only)")
DEFINE_STRING(startup_src, nullptr,
"Write V8 startup as C++ src. (mksnapshot only)")
DEFINE_STRING(startup_blob, nullptr,
"Write V8 startup blob file. (mksnapshot only)")
DEFINE_STRING(target_arch, nullptr,
"The mksnapshot target arch. (mksnapshot only)")
DEFINE_STRING(target_os, nullptr, "The mksnapshot target os. (mksnapshot only)")
DEFINE_BOOL(target_is_simulator, false,
"Instruct mksnapshot that the target is meant to run in the "
"simulator and it can generate simulator-specific instructions. "
"(mksnapshot only)")
DEFINE_STRING(turbo_profiling_log_file, nullptr,
"Path of the input file containing basic block counters for "
"builtins. (mksnapshot only)")
// On some platforms, the .text section only has execute permissions.
DEFINE_BOOL(text_is_readable, true,
"Whether the .text section of binary can be read")
DEFINE_NEG_NEG_IMPLICATION(text_is_readable, partial_constant_pool)
// Minor mark compact collector flags.
DEFINE_BOOL(minor_mc_parallel_marking, true,
"use parallel marking for the young generation")
DEFINE_BOOL(trace_minor_mc_parallel_marking, false,
"trace parallel marking for the young generation")
DEFINE_BOOL(minor_mc, false, "perform young generation mark compact GCs")
DEFINE_BOOL_READONLY(minor_mc, false,
"perform young generation mark compact GCs")
// Dev shell flags
DEFINE_BOOL(help, false, "Print usage message, including flags, on console")
DEFINE_BOOL(dump_counters, false, "Dump counters on exit")
DEFINE_BOOL(dump_counters_nvp, false,
"Dump counters as name-value pairs on exit")
DEFINE_BOOL(use_external_strings, false, "Use external strings for source code")
DEFINE_STRING(map_counters, "", "Map counters to a file")
DEFINE_BOOL(mock_arraybuffer_allocator, false,
"Use a mock ArrayBuffer allocator for testing.")
DEFINE_SIZE_T(mock_arraybuffer_allocator_limit, 0,
"Memory limit for mock ArrayBuffer allocator used to simulate "
"OOM for testing.")
DEFINE_BOOL(multi_mapped_mock_allocator, false,
"Use a multi-mapped mock ArrayBuffer allocator for testing.")
// Flags for Wasm GDB remote debugging.
DEFINE_BOOL(wasm_gdb_remote, false,
"enable GDB-remote for WebAssembly debugging")
DEFINE_NEG_IMPLICATION(wasm_gdb_remote, wasm_tier_up)
"default port for WebAssembly debugging with LLDB.")
DEFINE_BOOL(wasm_pause_waiting_for_debugger, false,
"pause at the first Webassembly instruction waiting for a debugger "
"to attach")
// GDB JIT integration flags.
#undef FLAG
DEFINE_BOOL(gdbjit, false, "enable GDBJIT interface")
DEFINE_BOOL(gdbjit_full, false, "enable GDBJIT interface for all code objects")
DEFINE_BOOL(gdbjit_dump, false, "dump elf objects with debug info to disk")
DEFINE_STRING(gdbjit_dump_filter, "",
"dump only objects containing this substring")
DEFINE_IMPLICATION(gdbjit_full, gdbjit)
DEFINE_IMPLICATION(gdbjit_dump, gdbjit)
DEFINE_NEG_IMPLICATION(gdbjit, compact_code_space)
// Debug only flags
#undef FLAG
#ifdef DEBUG
DEFINE_BOOL(enable_slow_asserts, true,
"enable asserts that are slow to execute")
// / / macro-assembler-*.cc
DEFINE_BOOL(print_ast, false, "print source AST")
DEFINE_BOOL(trap_on_abort, false, "replace aborts by breakpoints")
DEFINE_BOOL(print_scopes, false, "print scopes")
DEFINE_BOOL(trace_contexts, false, "trace contexts operations")
DEFINE_BOOL(gc_verbose, false, "print stuff during garbage collection")
DEFINE_BOOL(code_stats, false, "report code statistics after GC")
DEFINE_BOOL(print_handles, false, "report handles after GC")
DEFINE_BOOL(check_handle_count, false,
"Check that there are not too many handles at GC")
DEFINE_BOOL(print_global_handles, false, "report global handles after GC")
// TurboFan debug-only flags.
DEFINE_BOOL(trace_turbo_escape, false, "enable tracing in escape analysis")
DEFINE_BOOL(trace_module_status, false,
"Trace status transitions of ECMAScript modules")
DEFINE_BOOL(trace_normalization, false,
"prints when objects are turned into dictionaries.")
DEFINE_BOOL(trace_lazy, false, "trace lazy compilation")
DEFINE_BOOL(collect_heap_spill_statistics, false,
"report heap spill statistics along with heap_stats "
"(requires heap_stats)")
DEFINE_BOOL(trace_isolates, false, "trace isolate state changes")
// Regexp
DEFINE_BOOL(regexp_possessive_quantifier, false,
"enable possessive quantifier syntax for testing")
// Debugger
DEFINE_BOOL(print_break_location, false, "print source location on debug break")
// wasm instance management
DEFINE_DEBUG_BOOL(trace_wasm_instances, false,
"trace creation and collection of wasm instances")
DEFINE_BOOL(trace_wasm_gdb_remote, false, "trace Webassembly GDB-remote server")
// Logging and profiling flags
#undef FLAG
DEFINE_STRING(logfile, "v8.log",
"Specify the name of the log file, use '-' for console, '+' for "
"a temporary file.")
DEFINE_BOOL(logfile_per_isolate, true, "Separate log files for each isolate.")
DEFINE_BOOL(log, false,
"Minimal logging (no API, code, GC, suspect, or handles samples).")
DEFINE_BOOL(log_all, false, "Log all events to the log file.")
DEFINE_BOOL(log_api, false, "Log API events to the log file.")
DEFINE_BOOL(log_code, false,
"Log code events to the log file without profiling.")
DEFINE_BOOL(log_handles, false, "Log global handle events.")
DEFINE_BOOL(log_suspect, false, "Log suspect operations.")
DEFINE_BOOL(log_source_code, false, "Log source code.")
DEFINE_BOOL(log_function_events, false,
"Log function events "
"(parse, compile, execute) separately.")
DEFINE_IMPLICATION(log_all, log_api)
DEFINE_IMPLICATION(log_all, log_code)
DEFINE_IMPLICATION(log_all, log_suspect)
DEFINE_IMPLICATION(log_all, log_handles)
DEFINE_IMPLICATION(log_all, log_internal_timer_events)
DEFINE_IMPLICATION(log_all, log_function_events)
DEFINE_BOOL(detailed_line_info, false,
"Always generate detailed line information for CPU profiling.")
#if defined(ANDROID)
// Phones and tablets have processors that are much slower than desktop
// and laptop computers for which current heuristics are tuned.
"Interval for --prof samples (in microseconds).")
DEFINE_BOOL(prof_cpp, false, "Like --prof, but ignore generated code.")
DEFINE_BOOL(prof_browser_mode, true,
"Used with --prof, turns on browser-compatible mode for profiling.")
DEFINE_BOOL(prof, false,
"Log statistical profiling information (implies --log-code).")
DEFINE_IMPLICATION(prof, prof_cpp)
DEFINE_IMPLICATION(prof, log_code)
DEFINE_BOOL(ll_prof, false, "Enable low-level linux profiler.")
#define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL(nam, false, cmt)
#define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL_READONLY(nam, false, cmt)
"Enable perf linux profiler (basic support).")
DEFINE_NEG_IMPLICATION(perf_basic_prof, compact_code_space)
"Only report function code ranges to perf (i.e. no stubs).")
DEFINE_PERF_PROF_IMPLICATION(perf_basic_prof_only_functions, perf_basic_prof)
perf_prof, "Enable perf linux profiler (experimental annotate support).")
"Used with --perf-prof, load wasm source map and provide annotate "
"support (experimental).")
"Remove the perf file right after creating it (for testing only).")
DEFINE_NEG_IMPLICATION(perf_prof, compact_code_space)
// TODO(v8:8462) Remove implication once perf supports remapping.
DEFINE_NEG_IMPLICATION(perf_prof, write_protect_code_memory)
DEFINE_NEG_IMPLICATION(perf_prof, wasm_write_protect_code_memory)
// --perf-prof-unwinding-info is available only on selected architectures.
#define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL_READONLY(nam, false, cmt)
"Enable unwinding info for perf linux profiler (experimental).")
DEFINE_PERF_PROF_IMPLICATION(perf_prof, perf_prof_unwinding_info)
DEFINE_STRING(gc_fake_mmap, "/tmp/__v8_gc__",
"Specify the name of the file for fake gc mmap used in ll_prof")
DEFINE_BOOL(log_internal_timer_events, false, "Time internal events.")
DEFINE_IMPLICATION(log_internal_timer_events, prof)
DEFINE_BOOL(redirect_code_traces, false,
"output deopt information and disassembly into file "
"code-<pid>-<isolate id>.asm")
DEFINE_STRING(redirect_code_traces_to, nullptr,
"output deopt information and disassembly into the given file")
DEFINE_BOOL(print_opt_source, false,
"print source code of optimized and inlined functions")
DEFINE_BOOL(vtune_prof_annotate_wasm, false,
"Used when v8_enable_vtunejit is enabled, load wasm source map and "
"provide annotate support (experimental).")
DEFINE_BOOL(win64_unwinding_info, false, "Enable unwinding info for Windows/x64")
// Unsupported on arm. See
interpreted_frames_native_stack, false,
"Show interpreted frames on the native stack (useful for external "
DEFINE_BOOL(interpreted_frames_native_stack, false,
"Show interpreted frames on the native stack (useful for external "
// Disassembler only flags
#undef FLAG
DEFINE_BOOL(trace_elements_transitions, false, "trace elements transitions")
DEFINE_BOOL(trace_creation_allocation_sites, false,
"trace the creation of allocation sites")
DEFINE_BOOL(print_code, false, "print generated code")
DEFINE_BOOL(print_opt_code, false, "print optimized code")
DEFINE_STRING(print_opt_code_filter, "*", "filter for printing optimized code")
DEFINE_BOOL(print_code_verbose, false, "print more information for code")
DEFINE_BOOL(print_builtin_code, false, "print generated code for builtins")
DEFINE_STRING(print_builtin_code_filter, "*",
"filter for printing builtin code")
DEFINE_BOOL(print_regexp_code, false, "print generated regexp code")
DEFINE_BOOL(print_regexp_bytecode, false, "print generated regexp bytecode")
DEFINE_BOOL(print_builtin_size, false, "print code size for builtins")
DEFINE_BOOL(sodium, false,
"print generated code output suitable for use with "
"the Sodium code viewer")
DEFINE_IMPLICATION(sodium, print_code)
DEFINE_IMPLICATION(sodium, print_opt_code)
DEFINE_IMPLICATION(sodium, code_comments)
DEFINE_BOOL(print_all_code, false, "enable all flags related to printing code")
DEFINE_IMPLICATION(print_all_code, print_code)
DEFINE_IMPLICATION(print_all_code, print_opt_code)
DEFINE_IMPLICATION(print_all_code, print_code_verbose)
DEFINE_IMPLICATION(print_all_code, print_builtin_code)
DEFINE_IMPLICATION(print_all_code, print_regexp_code)
DEFINE_IMPLICATION(print_all_code, code_comments)
#undef FLAG
// Predictable mode related flags.
DEFINE_BOOL(predictable, false, "enable predictable mode")
DEFINE_IMPLICATION(predictable, single_threaded)
DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
DEFINE_VALUE_IMPLICATION(single_threaded, wasm_num_compilation_tasks, 0)
DEFINE_NEG_IMPLICATION(single_threaded, wasm_async_compilation)
DEFINE_BOOL(predictable_gc_schedule, false,
"Predictable garbage collection schedule. Fixes heap growing, "
"idle, and memory reducing behavior.")
DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, min_semi_space_size, 4)
DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, max_semi_space_size, 4)
DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, heap_growing_percent, 30)
DEFINE_NEG_IMPLICATION(predictable_gc_schedule, memory_reducer)
// Threading related flags.
DEFINE_BOOL(single_threaded, false, "disable the use of background tasks")
DEFINE_IMPLICATION(single_threaded, single_threaded_gc)
DEFINE_NEG_IMPLICATION(single_threaded, concurrent_recompilation)
DEFINE_NEG_IMPLICATION(single_threaded, compiler_dispatcher)
// Parallel and concurrent GC (Orinoco) related flags.
DEFINE_BOOL(single_threaded_gc, false, "disable the use of background gc tasks")
DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_marking)
DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_sweeping)
DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_compaction)
DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_marking)
DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_pointer_update)
DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_scavenge)
DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_store_buffer)
DEFINE_NEG_IMPLICATION(single_threaded_gc, minor_mc_parallel_marking)
DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_array_buffer_sweeping)
#undef FLAG
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
// assembler.h
DEFINE_BOOL(enable_embedded_constant_pool, V8_EMBEDDED_CONSTANT_POOL,
"enable use of embedded constant pools (PPC only)")
"enable in-object double fields unboxing (64-bit only)")
DEFINE_IMPLICATION(unbox_double_fields, track_double_fields)
// Cleanup...
#undef FLAG_FULL
#undef FLAG
#undef COMMA