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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)
#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) \
if (FLAG_##whenflag) FLAG_##thenflag = value;
#define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value) \
if (!FLAG_##whenflag) FLAG_##thenflag = value;
#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_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;
#ifdef DEBUG
#define DEBUG_BOOL true
#define DEBUG_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_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.
// 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 import.meta requires to also enable import()
DEFINE_IMPLICATION(harmony_import_meta, harmony_dynamic_import)
DEFINE_IMPLICATION(harmony_class_fields, harmony_public_fields)
DEFINE_IMPLICATION(harmony_class_fields, harmony_static_fields)
DEFINE_IMPLICATION(harmony_class_fields, harmony_private_fields)
DEFINE_IMPLICATION(harmony_private_methods, harmony_private_fields)
// Update whenever adding a new feature flag.
// Features that are still work in progress (behind individual flags).
V(harmony_class_fields, "harmony fields in class literals") \
V(harmony_private_methods, "harmony private methods in class literals") \
V(harmony_regexp_sequence, "RegExp Unicode sequence properties") \
V(harmony_weak_refs, "harmony weak references") \
V(harmony_intl_bigint, "BigInt.prototype.toLocaleString") \
V(harmony_intl_datetime_style, "dateStyle timeStyle for DateTimeFormat") \
V(harmony_locale, "Intl.Locale")
// Features that are complete (but still behind --harmony/es-staging flag).
V(harmony_private_fields, "harmony private fields in class literals") \
V(harmony_numeric_separator, "harmony numeric separator between digits") \
V(harmony_hashbang, "harmony hashbang syntax")
V(harmony_intl_segmenter, "Intl.Segmenter")
// Features that are shipping (turned on by default, but internal flag remains).
V(harmony_namespace_exports, \
"harmony namespace exports (export * as foo from 'bar')") \
V(harmony_sharedarraybuffer, "harmony sharedarraybuffer") \
V(harmony_import_meta, "harmony import.meta property") \
V(harmony_dynamic_import, "harmony dynamic import") \
V(harmony_global, "harmony global") \
V(harmony_json_stringify, "well-formed JSON.stringify") \
V(harmony_public_fields, "harmony public instance fields in class literals") \
V(harmony_static_fields, "harmony static fields in class literals") \
V(harmony_string_matchall, "harmony String.prototype.matchAll") \
V(harmony_object_from_entries, "harmony Object.fromEntries()") \
V(harmony_await_optimization, "harmony await taking 1 tick")
// 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 FUTURE_BOOL true
#define FUTURE_BOOL false
"Implies all staged features that we want to ship in the "
"not-too-far future")
DEFINE_IMPLICATION(future, write_protect_code_memory)
// 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_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(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, true,
"Enable size optimizations for the code that will "
"only be executed once")
// 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")
// Flags for Ignition for no-snapshot builds.
#undef FLAG
DEFINE_INT(interrupt_budget, 144 * KB,
"interrupt budget which should be used for the profiler counter")
#undef FLAG
// 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, false,
"skip generating source positions during initial compile but "
"regenerate when actually required")
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 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_IMPLICATION(future, concurrent_inlining)
DEFINE_BOOL(trace_heap_broker, false, "trace the 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(turbo_sp_frame_access, false,
"use stack pointer-relative access to frame wherever possible")
DEFINE_BOOL(turbo_preprocess_ranges, true,
"run pre-register allocation heuristics")
DEFINE_BOOL(turbo_control_flow_aware_allocation, false,
"consider control flow while allocating registers")
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_alloc, false, "trace register allocator")
DEFINE_BOOL(trace_all_uses, false, "trace all use positions")
DEFINE_BOOL(trace_representation, false, "trace representation types")
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_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_VALUE_IMPLICATION(stress_inline, polymorphic_inlining, true)
DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
DEFINE_BOOL(inline_accessors, true, "inline JavaScript accessors")
DEFINE_BOOL(inline_into_try, true, "inline into try blocks")
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 profiling in TurboFan")
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)")
DEFINE_BOOL(experimental_inline_promise_constructor, true,
"inline the Promise constructor in TurboFan")
stress_gc_during_compilation, false,
"simulate GC/compiler thread race related to")
"Enable mitigations for executing untrusted code")
// Flags for native WebAssembly.
DEFINE_BOOL(expose_wasm, true, "expose wasm interface to JavaScript")
DEFINE_BOOL(assume_asmjs_origin, false,
"force wasm decoder to assume input is internal asm-wasm format")
DEFINE_BOOL(wasm_disable_structured_cloning, false,
"disable wasm structured cloning")
DEFINE_INT(wasm_num_compilation_tasks, 10,
"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_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::kV8MaxWasmMemoryPages,
"maximum number of 64KiB memory pages of a wasm instance")
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)")
// Enable Liftoff by default on ia32 and x64. More architectures will follow
// once they are implemented and sufficiently tested.
wasm_tier_up, true,
"enable wasm baseline compilation and tier up to the optimizing compiler")
wasm_tier_up, false,
"enable wasm baseline compilation and tier up to the optimizing compiler")
DEFINE_IMPLICATION(future, wasm_tier_up)
DEFINE_IMPLICATION(wasm_tier_up, liftoff)
DEFINE_DEBUG_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
DEFINE_DEBUG_BOOL(trace_wasm_decode_time, false,
"trace decoding time 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, false,
"enable Liftoff, the baseline compiler for WebAssembly")
DEFINE_DEBUG_BOOL(trace_liftoff, false,
"trace Liftoff, the baseline compiler for WebAssembly")
DEFINE_DEBUG_BOOL(wasm_break_on_decoder_error, false,
"debug break when wasm decoder encounters an error")
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(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 SPACE
#define DECL_WASM_FLAG(feat, desc, val) \
DEFINE_BOOL(experimental_wasm_##feat, val, \
"enable prototype " desc " for wasm")
#undef SPACE
DEFINE_BOOL(wasm_opt, false, "enable wasm optimization")
DEFINE_BOOL(wasm_no_bounds_checks, false,
"disable bounds checks (performance testing only)")
DEFINE_BOOL(wasm_no_stack_checks, false,
"disable stack checks (performance testing only)")
DEFINE_BOOL(wasm_math_intrinsics, true,
"intrinsify some Math imports into wasm")
DEFINE_BOOL(wasm_shared_engine, true,
"shares one wasm engine between all isolates within a process")
DEFINE_IMPLICATION(future, wasm_shared_engine)
DEFINE_BOOL(wasm_shared_code, true,
"shares code underlying a wasm module when it is transferred")
DEFINE_IMPLICATION(future, wasm_shared_code)
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_trap_handler_fallback, false,
"Use bounds checks if guarded memory is not available")
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_BOOL(print_wasm_stub_code, false, "Print WebAssembly stub code")
DEFINE_BOOL(wasm_interpret_all, false,
"Execute all wasm code in the wasm interpreter")
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")
// wasm-interpret-all resets {asm-,}wasm-lazy-compilation.
DEFINE_NEG_IMPLICATION(wasm_interpret_all, asm_wasm_lazy_compilation)
DEFINE_NEG_IMPLICATION(wasm_interpret_all, wasm_lazy_compilation)
// Profiler flags.
DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
DEFINE_INT(type_info_threshold, 25,
"percentage of ICs that must have type info to allow optimization")
DEFINE_INT(stress_sampling_allocation_profiler, 0,
"Enables sampling allocation profiler with X as a sample interval")
// Garbage collections flags.
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_BOOL(experimental_new_space_growth_heuristic, false,
"Grow the new space based on the percentage of survivors instead "
"of their absolute value.")
DEFINE_SIZE_T(max_old_space_size, 0, "max size of the old space (in Mbytes)")
DEFINE_SIZE_T(initial_old_space_size, 0, "initial old space size (in Mbytes)")
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_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(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(trace_unmapper, false, "Trace the unmapping")
DEFINE_BOOL(parallel_scavenge, true, "parallel 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(parallel_marking, true, "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")
DEFINE_BOOL(track_retaining_path, false,
"enable support for tracking retaining path")
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_VALUE_IMPLICATION(track_gc_object_stats, gc_stats, 1)
DEFINE_VALUE_IMPLICATION(trace_gc_object_stats, gc_stats, 1)
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_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_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(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_IMPLICATION(fuzzer_gc_analysis, stress_marking)
DEFINE_IMPLICATION(fuzzer_gc_analysis, stress_scavenge)
DEFINE_BOOL(disable_abortjs, false, "disables AbortJS runtime function")
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")
DEFINE_BOOL(young_generation_large_objects, false,
"allocates large objects by default in the young generation large "
"object space")
DEFINE_BOOL(idle_time_scavenge, true, "Perform scavenges in idle time.")
// / /
"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_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)")
// 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(disable_old_api_accessors, false,
"Disable old-style API accessors whose setters trigger through the "
"prototype chain")
DEFINE_BOOL(expose_free_buffer, false, "expose freeBuffer extension")
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(disallow_code_generation_from_strings, false,
"disallow eval and friends")
DEFINE_BOOL(expose_async_hooks, false, "expose async_hooks object")
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_BOOL(trace, false, "trace 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 lazy optimization")
DEFINE_BOOL(trace_opt_verbose, false, "extra verbose compilation tracing")
DEFINE_IMPLICATION(trace_opt_verbose, trace_opt)
DEFINE_BOOL(trace_opt_stats, false, "trace lazy optimization statistics")
DEFINE_BOOL(trace_deopt, false, "trace optimize function deoptimization")
DEFINE_BOOL(trace_file_names, false,
"include file names in trace-opt/trace-deopt output")
DEFINE_BOOL(trace_interrupts, false, "trace interrupts when they are handled")
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")
// Array abuse tracing
DEFINE_BOOL(trace_js_array_abuse, false,
"trace out-of-bounds accesses to JS arrays")
DEFINE_BOOL(trace_external_array_abuse, false,
"trace out-of-bounds-accesses to external arrays")
DEFINE_BOOL(trace_array_abuse, false,
"trace out-of-bounds accesses to all arrays")
DEFINE_IMPLICATION(trace_array_abuse, trace_js_array_abuse)
DEFINE_IMPLICATION(trace_array_abuse, trace_external_array_abuse)
// 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_INT(ic_stats, 0, "inline cache state transitions statistics")
DEFINE_VALUE_IMPLICATION(trace_ic, ic_stats, 1)
DEFINE_BOOL_READONLY(track_constant_fields, true,
"enable constant field tracking")
DEFINE_BOOL_READONLY(modify_map_inplace, true, "enable in-place map updates")
DEFINE_BOOL_READONLY(fast_map_update, false,
"enable fast map update by caching the migration target")
DEFINE_INT(max_polymorphic_map_count, 4,
"maximum number of maps to track in POLYMORPHIC state")
DEFINE_BOOL(native_code_counters, false,
"generate extra code for manipulating stats counters")
DEFINE_BOOL(thin_strings, true, "Enable ThinString support")
DEFINE_BOOL(trace_prototype_users, false,
"Trace updates to prototype user tracking")
DEFINE_BOOL(use_verbose_printer, true, "allows verbose printing")
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(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, MIPS64 and PPC64 simulator "
"in kBytes (default is 2 MB)")
"When logging, try to use coloured output.")
DEFINE_BOOL(ignore_asm_unimplemented_break, false,
"Don't break for ASM_UNIMPLEMENTED_BREAK macros.")
DEFINE_BOOL(trace_sim_messages, false,
"Trace simulator debug messages. Implied by --trace-sim.")
DEFINE_BOOL(async_stack_traces, true,
"include async stack traces in Error.stack")
DEFINE_IMPLICATION(async_stack_traces, harmony_await_optimization)
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(abort_on_stack_or_string_length_overflow, false,
"Abort program when the stack overflows or a string exceeds "
"maximum length (as opposed to throwing RangeError). This is "
"useful for fuzzing where the spec behaviour would introduce "
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(runtime_call_stats, false, "report runtime call counts and times")
DEFINE_INT(runtime_stats, 0,
"internal usage only for controlling runtime statistics")
DEFINE_VALUE_IMPLICATION(runtime_call_stats, runtime_stats, 1)
"Embed builtin code into the binary.")
DEFINE_BOOL(profile_deserialization, false,
"Print the time it takes to deserialize the snapshot.")
DEFINE_BOOL(serialization_statistics, false,
"Collect statistics on serialized objects.")
DEFINE_UINT(serialization_chunk_size, 4096,
"Custom size for serialization chunks")
// 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")
// 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")
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)")
// 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")
// 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.")
// Flags only available in non-Lite modes.
#undef FLAG
#ifdef V8_LITE_MODE
"Disable runtime allocation of executable memory.")
// Jitless V8 has a few implications:
#ifndef V8_LITE_MODE
// Optimizations (i.e. jitting) are disabled.
// 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)
// Wasm is put into interpreter-only mode. We repeat flag implications down
// here to ensure they're applied correctly by setting the --jitless flag.
DEFINE_IMPLICATION(jitless, wasm_interpret_all)
DEFINE_NEG_IMPLICATION(jitless, asm_wasm_lazy_compilation)
DEFINE_NEG_IMPLICATION(jitless, wasm_lazy_compilation)
// Even in interpreter-only mode, wasm currently still creates executable
// memory at runtime. Disable until this changes.
// TODO(jgruber): Remove this once / if wasm can run without executable memory.
DEFINE_NEG_IMPLICATION(jitless, expose_wasm)
// Enable recompilation of function with optimized code.
DEFINE_BOOL(opt, !V8_LITE_BOOL, "use adaptive optimizations")
// Enable use of inline caches to optimize object access operations.
DEFINE_BOOL(use_ic, !V8_LITE_BOOL, "use inline caching")
// Favor memory over execution speed.
DEFINE_BOOL(optimize_for_size, V8_LITE_BOOL,
"Enables optimizations which favor memory size over execution "
DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
// 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_builtin_scopes, false, "print scopes for builtins")
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")
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")
// 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")
// Logging and profiling flags
#undef FLAG
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_BOOL(prof, false,
"Log statistical profiling information (implies --log-code).")
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_IMPLICATION(prof, prof_cpp)
DEFINE_BOOL(prof_browser_mode, true,
"Used with --prof, turns on browser-compatible mode for profiling.")
DEFINE_STRING(logfile, "v8.log", "Specify the name of the log file.")
DEFINE_BOOL(logfile_per_isolate, true, "Separate log files for each isolate.")
DEFINE_BOOL(ll_prof, false, "Enable low-level linux profiler.")
DEFINE_BOOL(perf_basic_prof, false,
"Enable perf linux profiler (basic support).")
DEFINE_NEG_IMPLICATION(perf_basic_prof, compact_code_space)
DEFINE_BOOL(perf_basic_prof_only_functions, false,
"Only report function code ranges to perf (i.e. no stubs).")
DEFINE_IMPLICATION(perf_basic_prof_only_functions, perf_basic_prof)
DEFINE_BOOL(perf_prof, false,
"Enable perf linux profiler (experimental annotate support).")
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)
DEFINE_BOOL(perf_prof_unwinding_info, false,
"Enable unwinding info for perf linux profiler (experimental).")
DEFINE_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_BOOL(log_timer_events, false,
"Time events including external callbacks.")
DEFINE_IMPLICATION(log_timer_events, log_internal_timer_events)
DEFINE_IMPLICATION(log_internal_timer_events, prof)
DEFINE_BOOL(log_instruction_stats, false, "Log AArch64 instruction statistics.")
DEFINE_STRING(log_instruction_file, "arm64_inst.csv",
"AArch64 instruction statistics log file.")
DEFINE_INT(log_instruction_period, 1 << 22,
"AArch64 instruction statistics logging period.")
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")
// 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_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, 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, idle_time_scavenge)
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_freeing)
#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)
"enables trade-off of performance for memory savings "
"(Lite mode only)")
// Cleanup...
#undef FLAG_FULL
#undef FLAG
#undef COMMA