/
flag-definitions.h
2399 lines (2130 loc) · 106 KB
/
flag-definitions.h
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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:
//
// PRESUBMIT_INTENTIONALLY_MISSING_INCLUDE_GUARD
#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_WEAK_NEG_IMPLICATION(whenflag, thenflag) \
DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, false)
#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)
// With FLAG_MODE_DECLARE we declare the fields in the {FlagValues} struct.
// Read-only flags are static constants instead of fields.
#if defined(FLAG_MODE_DECLARE)
#define FLAG_FULL(ftype, ctype, nam, def, cmt) FlagValue<ctype> nam{def};
#define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
static constexpr FlagValue<ctype> nam{def};
// Define a {FLAG_foo} alias per flag, pointing to {v8_flags.foo}.
// This allows to still use the old and deprecated syntax for accessing flag
// values. This will be removed after v10.7.
// TODO(clemensb): Remove this after v10.7.
#elif defined(FLAG_MODE_DEFINE_GLOBAL_ALIASES)
#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
inline auto& FLAG_##nam = v8_flags.nam;
#define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
inline auto constexpr& FLAG_##nam = v8_flags.nam;
// 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.
#elif defined(FLAG_MODE_DEFINE_DEFAULTS)
#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, &v8_flags.nam, &FLAGDEFAULT_##nam, cmt, false},
#define FLAG_ALIAS(ftype, ctype, alias, nam) \
{Flag::TYPE_##ftype, #alias, &v8_flags.nam, &FLAGDEFAULT_##nam, \
"alias for --" #nam, false}, // NOLINT(whitespace/indent)
// We produce the code to set flags when it is implied by another flag.
#elif defined(FLAG_MODE_DEFINE_IMPLICATIONS)
#define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value) \
changed |= TriggerImplication(v8_flags.whenflag, #whenflag, \
&v8_flags.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(v8_flags.whenflag, #whenflag, \
&v8_flags.thenflag, value, true);
#define DEFINE_GENERIC_IMPLICATION(whenflag, statement) \
if (v8_flags.whenflag) statement;
#define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value) \
changed |= TriggerImplication(!v8_flags.whenflag, "!" #whenflag, \
&v8_flags.thenflag, value, false);
// We apply a generic macro to the flags.
#elif defined(FLAG_MODE_APPLY)
#define FLAG_FULL FLAG_MODE_APPLY
#else
#error No mode supplied when including flags.defs
#endif
// Dummy defines for modes where it is not relevant.
#ifndef FLAG_FULL
#define FLAG_FULL(ftype, ctype, nam, def, cmt)
#endif
#ifndef FLAG_READONLY
#define FLAG_READONLY(ftype, ctype, nam, def, cmt)
#endif
#ifndef FLAG_ALIAS
#define FLAG_ALIAS(ftype, ctype, alias, nam)
#endif
#ifndef DEFINE_VALUE_IMPLICATION
#define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)
#endif
#ifndef DEFINE_WEAK_VALUE_IMPLICATION
#define DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, value)
#endif
#ifndef DEFINE_GENERIC_IMPLICATION
#define DEFINE_GENERIC_IMPLICATION(whenflag, statement)
#endif
#ifndef DEFINE_NEG_VALUE_IMPLICATION
#define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)
#endif
#ifndef DEBUG_BOOL
#error DEBUG_BOOL must be defined at this point.
#endif // DEBUG_BOOL
#ifndef ENABLE_SPARKPLUG
#error ENABLE_SPARKPLUG must be defined at this point.
#endif // ENABLE_SPARKPLUG
#if ENABLE_SPARKPLUG && !defined(ANDROID)
// Enable Sparkplug by default on desktop-only.
#define ENABLE_SPARKPLUG_BY_DEFAULT true
#else
#define ENABLE_SPARKPLUG_BY_DEFAULT false
#endif
// 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_ARMV8_INSTRUCTIONS) && \
defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS))
#define ARM_ARCH_DEFAULT "armv8"
#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS)
#define ARM_ARCH_DEFAULT "armv7+sudiv"
#elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_NEON) && \
defined(CAN_USE_VFP3_INSTRUCTIONS)
#define ARM_ARCH_DEFAULT "armv7"
#else
#define ARM_ARCH_DEFAULT "armv6"
#endif
#ifdef V8_OS_WIN
#define ENABLE_LOG_COLOUR false
#else
#define ENABLE_LOG_COLOUR true
#endif
#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, base::Optional<bool>, nam, base::nullopt, 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
#define DEFINE_DEBUG_BOOL DEFINE_BOOL
#else
#define DEFINE_DEBUG_BOOL DEFINE_BOOL_READONLY
#endif
//
// Flags in all modes.
//
#define FLAG FLAG_FULL
// 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)
// As abort_on_contradictory_flags, but it will simply exit with return code 0.
DEFINE_BOOL(exit_on_contradictory_flags, false,
"Exit with return code 0 on contradictory flags.")
// We rely on abort_on_contradictory_flags to turn on the analysis.
DEFINE_WEAK_IMPLICATION(exit_on_contradictory_flags,
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/d8.cc.
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(trace_temporal, false, "trace temporal code")
DEFINE_BOOL(harmony, false, "enable all completed harmony features")
DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
// Update bootstrapper.cc whenever adding a new feature flag.
// Features that are still work in progress (behind individual flags).
#define HARMONY_INPROGRESS_BASE(V) \
V(harmony_weak_refs_with_cleanup_some, \
"harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
V(harmony_temporal, "Temporal") \
V(harmony_shadow_realm, "harmony ShadowRealm") \
V(harmony_struct, "harmony structs, shared structs, and shared arrays") \
V(harmony_regexp_unicode_sets, "harmony RegExp Unicode Sets") \
V(harmony_json_parse_with_source, "harmony json parse with source")
#ifdef V8_INTL_SUPPORT
#define HARMONY_INPROGRESS(V) \
HARMONY_INPROGRESS_BASE(V) \
V(harmony_intl_best_fit_matcher, "Intl BestFitMatcher") \
V(harmony_intl_duration_format, "Intl DurationFormat API")
#else
#define HARMONY_INPROGRESS(V) HARMONY_INPROGRESS_BASE(V)
#endif
// Features that are complete (but still behind the --harmony flag).
#define HARMONY_STAGED_BASE(V) \
V(harmony_rab_gsab, \
"harmony ResizableArrayBuffer / GrowableSharedArrayBuffer") \
V(harmony_array_grouping, "harmony array grouping") \
V(harmony_change_array_by_copy, "harmony change-Array-by-copy") \
V(harmony_symbol_as_weakmap_key, "harmony symbols as weakmap keys")
#ifdef V8_INTL_SUPPORT
#define HARMONY_STAGED(V) HARMONY_STAGED_BASE(V)
#else
#define HARMONY_STAGED(V) HARMONY_STAGED_BASE(V)
#endif
// Features that are shipping (turned on by default, but internal flag remains).
#define HARMONY_SHIPPING_BASE(V) \
V(harmony_sharedarraybuffer, "harmony sharedarraybuffer") \
V(harmony_atomics, "harmony atomics") \
V(harmony_class_static_blocks, "harmony static initializer blocks") \
V(harmony_array_find_last, "harmony array find last helpers") \
V(harmony_import_assertions, "harmony import assertions")
#ifdef V8_INTL_SUPPORT
#define HARMONY_SHIPPING(V) \
HARMONY_SHIPPING_BASE(V) \
V(harmony_intl_number_format_v3, "Intl.NumberFormat v3")
#else
#define HARMONY_SHIPPING(V) HARMONY_SHIPPING_BASE(V)
#endif
// 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)")
HARMONY_INPROGRESS(FLAG_INPROGRESS_FEATURES)
#undef FLAG_INPROGRESS_FEATURES
#define FLAG_STAGED_FEATURES(id, description) \
DEFINE_BOOL(id, false, "enable " #description) \
DEFINE_IMPLICATION(harmony, id)
HARMONY_STAGED(FLAG_STAGED_FEATURES)
#undef FLAG_STAGED_FEATURES
#define FLAG_SHIPPING_FEATURES(id, description) \
DEFINE_BOOL(id, true, "enable " #description) \
DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
#undef FLAG_SHIPPING_FEATURES
DEFINE_BOOL(builtin_subclassing, true,
"subclassing support in built-in methods")
// If the following flag is set to `true`, the SharedArrayBuffer constructor is
// enabled per context depending on the callback set via
// `SetSharedArrayBufferConstructorEnabledCallback`. If no callback is set, the
// SharedArrayBuffer constructor is disabled.
DEFINE_BOOL(enable_sharedarraybuffer_per_context, false,
"enable the SharedArrayBuffer constructor per context")
#ifdef V8_INTL_SUPPORT
DEFINE_BOOL(icu_timezone_data, true, "get information about timezones from ICU")
#endif
#ifdef V8_ENABLE_DOUBLE_CONST_STORE_CHECK
#define V8_ENABLE_DOUBLE_CONST_STORE_CHECK_BOOL true
#else
#define V8_ENABLE_DOUBLE_CONST_STORE_CHECK_BOOL false
#endif
#ifdef V8_LITE_MODE
#define V8_LITE_BOOL true
#else
#define V8_LITE_BOOL false
#endif
#ifdef V8_ENABLE_LAZY_SOURCE_POSITIONS
#define V8_LAZY_SOURCE_POSITIONS_BOOL true
#else
#define V8_LAZY_SOURCE_POSITIONS_BOOL false
#endif
#ifdef V8_SHARED_RO_HEAP
#define V8_SHARED_RO_HEAP_BOOL true
#else
#define V8_SHARED_RO_HEAP_BOOL false
#endif
DEFINE_BOOL(stress_snapshot, false,
"disables sharing of the read-only heap for testing")
// Incremental marking is incompatible with the stress_snapshot mode;
// specifically, serialization may clear bytecode arrays from shared function
// infos which the MarkCompactCollector (running concurrently) may still need.
// See also https://crbug.com/v8/10882.
//
// Note: This is not an issue in production because we don't clear SFI's
// there (that only happens in mksnapshot and in --stress-snapshot mode).
DEFINE_NEG_IMPLICATION(stress_snapshot, incremental_marking)
DEFINE_BOOL(lite_mode, V8_LITE_BOOL,
"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)
#ifdef V8_ENABLE_THIRD_PARTY_HEAP
#define V8_ENABLE_THIRD_PARTY_HEAP_BOOL true
#else
#define V8_ENABLE_THIRD_PARTY_HEAP_BOOL false
#endif
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)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, concurrent_recompilation)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, script_streaming)
DEFINE_NEG_IMPLICATION(enable_third_party_heap,
parallel_compile_tasks_for_eager_toplevel)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, use_marking_progress_bar)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, move_object_start)
DEFINE_NEG_IMPLICATION(enable_third_party_heap, concurrent_marking)
DEFINE_BOOL_READONLY(enable_third_party_heap, V8_ENABLE_THIRD_PARTY_HEAP_BOOL,
"Use third-party heap")
#ifdef V8_ALLOCATION_FOLDING
#define V8_ALLOCATION_FOLDING_BOOL true
#else
#define V8_ALLOCATION_FOLDING_BOOL false
#endif
DEFINE_BOOL_READONLY(enable_allocation_folding, V8_ALLOCATION_FOLDING_BOOL,
"Use allocation folding globally")
DEFINE_NEG_NEG_IMPLICATION(enable_allocation_folding, turbo_allocation_folding)
#ifdef V8_DISABLE_WRITE_BARRIERS
#define V8_DISABLE_WRITE_BARRIERS_BOOL true
#else
#define V8_DISABLE_WRITE_BARRIERS_BOOL false
#endif
DEFINE_BOOL_READONLY(disable_write_barriers, V8_DISABLE_WRITE_BARRIERS_BOOL,
"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)
DEFINE_NEG_IMPLICATION(disable_write_barriers, concurrent_marking)
DEFINE_NEG_IMPLICATION(disable_write_barriers, cppheap_incremental_marking)
DEFINE_NEG_IMPLICATION(disable_write_barriers, cppheap_concurrent_marking)
#ifdef V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS
#define V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL true
#else
#define V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL false
#endif
DEFINE_BOOL_READONLY(enable_unconditional_write_barriers,
V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL,
"always use full write barriers")
#ifdef V8_ENABLE_SINGLE_GENERATION
#define V8_SINGLE_GENERATION_BOOL true
#else
#define V8_SINGLE_GENERATION_BOOL false
#endif
DEFINE_BOOL_READONLY(
single_generation, V8_SINGLE_GENERATION_BOOL,
"allocate all objects from young generation to old generation")
#ifdef V8_ENABLE_CONSERVATIVE_STACK_SCANNING
#define V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL true
#else
#define V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL false
#endif
DEFINE_BOOL_READONLY(conservative_stack_scanning,
V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL,
"use conservative stack scanning")
#ifdef V8_ENABLE_INNER_POINTER_RESOLUTION_OSB
#define V8_ENABLE_INNER_POINTER_RESOLUTION_OSB_BOOL true
#else
#define V8_ENABLE_INNER_POINTER_RESOLUTION_OSB_BOOL false
#endif
DEFINE_BOOL_READONLY(inner_pointer_resolution_osb,
V8_ENABLE_INNER_POINTER_RESOLUTION_OSB_BOOL,
"use object start bitmap for IPR")
#ifdef V8_ENABLE_INNER_POINTER_RESOLUTION_MB
#define V8_ENABLE_INNER_POINTER_RESOLUTION_MB_BOOL true
#else
#define V8_ENABLE_INNER_POINTER_RESOLUTION_MB_BOOL false
#endif
DEFINE_BOOL_READONLY(inner_pointer_resolution_mb,
V8_ENABLE_INNER_POINTER_RESOLUTION_MB_BOOL,
"use marking bitmap for IPR")
#ifdef V8_ENABLE_FUTURE
#define FUTURE_BOOL true
#else
#define FUTURE_BOOL false
#endif
DEFINE_BOOL(future, FUTURE_BOOL,
"Implies all staged features that we want to ship in the "
"not-too-far future")
#ifdef V8_ENABLE_MAGLEV
#define V8_ENABLE_MAGLEV_BOOL true
DEFINE_BOOL(maglev, false, "enable the maglev optimizing compiler")
DEFINE_BOOL(maglev_inlining, false,
"enable inlining in the maglev optimizing compiler")
DEFINE_BOOL(maglev_reuse_stack_slots, true,
"reuse stack slots in the maglev optimizing compiler")
// We stress maglev by setting a very low interrupt budget for maglev. This
// way, we still gather *some* feedback before compiling optimized code.
DEFINE_BOOL(stress_maglev, false, "trigger maglev compilation earlier")
DEFINE_IMPLICATION(stress_maglev, maglev)
DEFINE_VALUE_IMPLICATION(stress_maglev, interrupt_budget_for_maglev, 128)
#else
#define V8_ENABLE_MAGLEV_BOOL false
DEFINE_BOOL_READONLY(maglev, false, "enable the maglev optimizing compiler")
DEFINE_BOOL_READONLY(stress_maglev, false, "trigger maglev compilation earlier")
#endif // V8_ENABLE_MAGLEV
DEFINE_STRING(maglev_filter, "*", "optimization filter for the maglev compiler")
DEFINE_BOOL(maglev_assert, false, "insert extra assertion in maglev code")
DEFINE_BOOL(maglev_break_on_entry, false, "insert an int3 on maglev entries")
DEFINE_BOOL(print_maglev_graph, false, "print maglev graph")
DEFINE_BOOL(print_maglev_code, false, "print maglev code")
DEFINE_BOOL(trace_maglev_graph_building, false, "trace maglev graph building")
DEFINE_BOOL(trace_maglev_regalloc, false, "trace maglev register allocation")
// TODO(v8:7700): Remove once stable.
DEFINE_BOOL(maglev_function_context_specialization, true,
"enable function context specialization in maglev")
DEFINE_BOOL(maglev_ool_prologue, false, "use the Maglev out of line prologue")
#if ENABLE_SPARKPLUG
DEFINE_WEAK_IMPLICATION(future, sparkplug)
DEFINE_WEAK_IMPLICATION(future, flush_baseline_code)
#endif
#if V8_SHORT_BUILTIN_CALLS
DEFINE_WEAK_IMPLICATION(future, short_builtin_calls)
#endif
DEFINE_WEAK_NEG_IMPLICATION(future, write_protect_code_memory)
DEFINE_WEAK_NEG_IMPLICATION(future, use_map_space)
DEFINE_WEAK_IMPLICATION(
future, merge_background_deserialized_script_with_compilation_cache)
DEFINE_BOOL_READONLY(dict_property_const_tracking,
V8_DICT_PROPERTY_CONST_TRACKING_BOOL,
"Use const tracking on dictionary properties")
DEFINE_UINT(max_opt, 999,
"Set the maximal optimisation tier: "
"> 3 == any, 0 == ignition/interpreter, 1 == sparkplug/baseline, "
"2 == maglev, 3 == turbofan")
DEFINE_WEAK_VALUE_IMPLICATION(max_opt < 3, turbofan, false)
#ifdef V8_ENABLE_MAGLEV
DEFINE_WEAK_VALUE_IMPLICATION(max_opt < 2, maglev, false)
#endif // V8_ENABLE_MAGLEV
#if ENABLE_SPARKPLUG
DEFINE_WEAK_VALUE_IMPLICATION(max_opt < 1, sparkplug, false)
#endif // ENABLE_SPARKPLUG
//
// Flag to select wasm trace mark type
DEFINE_STRING(
wasm_trace_native, nullptr,
"Select which native code sequence to use for wasm trace instruction: "
"default or cpuid")
// Flags for jitless
DEFINE_BOOL(jitless, V8_LITE_BOOL,
"Disable runtime allocation of executable memory.")
// Jitless V8 has a few implications:
DEFINE_NEG_IMPLICATION(jitless, turbofan)
// Field type tracking is only used by TurboFan.
DEFINE_NEG_IMPLICATION(jitless, track_field_types)
// Regexps are interpreted.
DEFINE_IMPLICATION(jitless, regexp_interpret_all)
#if ENABLE_SPARKPLUG
// No Sparkplug compilation.
DEFINE_NEG_IMPLICATION(jitless, sparkplug)
DEFINE_NEG_IMPLICATION(jitless, always_sparkplug)
#endif // ENABLE_SPARKPLUG
#ifdef V8_ENABLE_MAGLEV
// No Maglev compilation.
DEFINE_NEG_IMPLICATION(jitless, maglev)
#endif // V8_ENABLE_MAGLEV
DEFINE_NEG_IMPLICATION(jitless, interpreted_frames_native_stack)
DEFINE_BOOL(assert_types, false,
"generate runtime type assertions to test the typer")
// TODO(tebbi): Support allocating types from background thread.
DEFINE_NEG_IMPLICATION(assert_types, concurrent_recompilation)
// Enable verification of SimplifiedLowering in debug builds.
DEFINE_BOOL(verify_simplified_lowering, DEBUG_BOOL,
"verify graph generated by simplified lowering")
DEFINE_BOOL(trace_compilation_dependencies, false, "trace code dependencies")
// Depend on --trace-deopt-verbose for reporting dependency invalidations.
DEFINE_IMPLICATION(trace_compilation_dependencies, trace_deopt_verbose)
#ifdef V8_ALLOCATION_SITE_TRACKING
#define V8_ALLOCATION_SITE_TRACKING_BOOL true
#else
#define V8_ALLOCATION_SITE_TRACKING_BOOL false
#endif
DEFINE_BOOL_READONLY(allocation_site_tracking, V8_ALLOCATION_SITE_TRACKING_BOOL,
"Enable allocation site tracking")
DEFINE_NEG_NEG_IMPLICATION(allocation_site_tracking,
allocation_site_pretenuring)
// 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_field_types, true, "track field types")
DEFINE_BOOL(trace_block_coverage, false,
"trace collected block coverage information")
DEFINE_BOOL(trace_protector_invalidation, false,
"trace protector cell invalidations")
DEFINE_BOOL(trace_web_snapshot, false, "trace web snapshot deserialization")
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 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")
// Tiering: Sparkplug / feedback vector allocation.
DEFINE_INT(interrupt_budget_for_feedback_allocation, 940,
"The fixed interrupt budget (in bytecode size) for allocating "
"feedback vectors")
DEFINE_INT(interrupt_budget_factor_for_feedback_allocation, 8,
"The interrupt budget factor (applied to bytecode size) for "
"allocating feedback vectors, used when bytecode size is known")
// Tiering: Maglev.
// The Maglev interrupt budget is chosen to be roughly 1/10th of Turbofan's
// overall budget (including the multiple required ticks).
DEFINE_INT(interrupt_budget_for_maglev, 40 * KB,
"interrupt budget which should be used for the profiler counter")
// Tiering: Turbofan.
DEFINE_INT(interrupt_budget, 66 * KB,
"interrupt budget which should be used for the profiler counter")
DEFINE_INT(ticks_before_optimization, 3,
"the number of times we have to go through the interrupt budget "
"before considering this function for optimization")
DEFINE_INT(bytecode_size_allowance_per_tick, 150,
"increases the number of ticks required for optimization by "
"bytecode.length/X")
DEFINE_INT(
max_bytecode_size_for_early_opt, 81,
"Maximum bytecode length for a function to be optimized on the first tick")
// Flags for inline caching and feedback vectors.
DEFINE_BOOL(use_ic, true, "use inline caching")
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(omit_default_ctors, false, "omit calling default ctors in bytecode")
#ifdef V8_TRACE_UNOPTIMIZED
DEFINE_BOOL(trace_unoptimized, false,
"trace the bytecodes executed by all unoptimized execution")
DEFINE_BOOL(trace_ignition, false,
"trace the bytecodes executed by the ignition interpreter")
DEFINE_BOOL(trace_baseline_exec, false,
"trace the bytecodes executed by the baseline code")
DEFINE_WEAK_IMPLICATION(trace_unoptimized, trace_ignition)
DEFINE_WEAK_IMPLICATION(trace_unoptimized, trace_baseline_exec)
#endif
#ifdef V8_TRACE_FEEDBACK_UPDATES
DEFINE_BOOL(
trace_feedback_updates, false,
"trace updates to feedback vectors during ignition interpreter execution.")
#endif
DEFINE_BOOL(trace_ignition_codegen, false,
"trace the codegen of ignition interpreter bytecode handlers")
DEFINE_STRING(
trace_ignition_dispatches_output_file, nullptr,
"write the bytecode handler dispatch table to the specified file (d8 only) "
"(requires building with v8_enable_ignition_dispatch_counting)")
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 Sparkplug
#undef FLAG
#if ENABLE_SPARKPLUG
#define FLAG FLAG_FULL
#else
#define FLAG FLAG_READONLY
#endif
DEFINE_BOOL(sparkplug, ENABLE_SPARKPLUG_BY_DEFAULT,
"enable Sparkplug baseline compiler")
DEFINE_BOOL(always_sparkplug, false, "directly tier up to Sparkplug code")
#if ENABLE_SPARKPLUG
DEFINE_IMPLICATION(always_sparkplug, sparkplug)
DEFINE_BOOL(baseline_batch_compilation, true, "batch compile Sparkplug code")
#if defined(V8_OS_DARWIN) && defined(V8_HOST_ARCH_ARM64) && \
!V8_HEAP_USE_PTHREAD_JIT_WRITE_PROTECT
// M1 requires W^X.
DEFINE_BOOL_READONLY(concurrent_sparkplug, false,
"compile Sparkplug code in a background thread")
#else
DEFINE_BOOL(concurrent_sparkplug, false,
"compile Sparkplug code in a background thread")
DEFINE_WEAK_IMPLICATION(future, concurrent_sparkplug)
DEFINE_NEG_IMPLICATION(predictable, concurrent_sparkplug)
DEFINE_NEG_IMPLICATION(single_threaded, concurrent_sparkplug)
DEFINE_NEG_IMPLICATION(jitless, concurrent_sparkplug)
#endif
DEFINE_UINT(
concurrent_sparkplug_max_threads, 0,
"max number of threads that concurrent Sparkplug can use (0 for unbounded)")
DEFINE_BOOL(concurrent_sparkplug_high_priority_threads, false,
"use high priority compiler threads for concurrent Sparkplug")
#else
DEFINE_BOOL(baseline_batch_compilation, false, "batch compile Sparkplug code")
DEFINE_BOOL_READONLY(concurrent_sparkplug, false,
"compile Sparkplug code in a background thread")
#endif
DEFINE_STRING(sparkplug_filter, "*", "filter for Sparkplug baseline compiler")
DEFINE_BOOL(sparkplug_needs_short_builtins, false,
"only enable Sparkplug baseline compiler when "
"--short-builtin-calls are also enabled")
DEFINE_INT(baseline_batch_compilation_threshold, 4 * KB,
"the estimated instruction size of a batch to trigger compilation")
DEFINE_BOOL(trace_baseline, false, "trace baseline compilation")
DEFINE_BOOL(trace_baseline_batch_compilation, false,
"trace baseline batch compilation")
DEFINE_BOOL(trace_baseline_concurrent_compilation, false,
"trace baseline concurrent compilation")
#undef FLAG
#define FLAG FLAG_FULL
// Internalize into a shared string table in the shared isolate
DEFINE_BOOL(shared_string_table, false, "internalize strings into shared table")
DEFINE_IMPLICATION(harmony_struct, shared_string_table)
DEFINE_BOOL(
always_use_string_forwarding_table, false,
"use string forwarding table instead of thin strings for all strings")
// With --always-use-string-forwarding-table, we can have young generation
// string entries in the forwarding table, requiring table updates when these
// strings get promoted to old space. Parallel GCs in client isolates
// (enabled by --shared-string-table) are not supported using a single shared
// forwarding table.
DEFINE_NEG_IMPLICATION(shared_string_table, always_use_string_forwarding_table)
DEFINE_SIZE_T(initial_shared_heap_size, 0,
"initial size of the shared heap (in Mbytes); "
"other heap size flags (e.g. initial_heap_size) take precedence")
DEFINE_SIZE_T(
max_shared_heap_size, 0,
"max size of the shared heap (in Mbytes); "
"other heap size flags (e.g. max_shared_heap_size) take precedence")
DEFINE_BOOL(write_code_using_rwx, true,
"flip permissions to rwx to write page instead of rw")
DEFINE_NEG_IMPLICATION(jitless, write_code_using_rwx)
// 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(
stress_concurrent_inlining, false,
"create additional concurrent optimization jobs but throw away result")
DEFINE_IMPLICATION(stress_concurrent_inlining, concurrent_recompilation)
DEFINE_NEG_IMPLICATION(stress_concurrent_inlining, lazy_feedback_allocation)
DEFINE_WEAK_VALUE_IMPLICATION(stress_concurrent_inlining, interrupt_budget,
15 * KB)
DEFINE_BOOL(stress_concurrent_inlining_attach_code, false,
"create additional concurrent optimization jobs")
DEFINE_IMPLICATION(stress_concurrent_inlining_attach_code,
stress_concurrent_inlining)
DEFINE_INT(max_serializer_nesting, 25,
"maximum levels for nesting child serializers")
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)
DEFINE_IMPLICATION(trace_heap_broker, trace_pending_allocations)
// 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(turbofan, true, "use the Turbofan optimizing compiler")
// TODO(leszeks): Temporary alias until we make sure all our infra is passing
// --turbofan instead of --opt.
DEFINE_ALIAS_BOOL(opt, turbofan)
DEFINE_BOOL(turbo_sp_frame_access, false,
"use stack pointer-relative access to frame wherever possible")
DEFINE_BOOL(
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_file_prefix, "turbo",
"trace turbo graph to a file with given prefix")
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")
DEFINE_BOOL(
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")
#ifdef ENABLE_VERIFY_CSA
DEFINE_BOOL(verify_csa, DEBUG_BOOL,
"verify TurboFan machine graph of code stubs")
#else
// 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")
#endif
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(turbo_inlining, true, "enable inlining in TurboFan")
DEFINE_INT(max_inlined_bytecode_size, 460,
"maximum size of bytecode for a single inlining")
DEFINE_INT(max_inlined_bytecode_size_cumulative, 920,
"maximum cumulative size of bytecode considered for inlining")
DEFINE_INT(max_inlined_bytecode_size_absolute, 4600,
"maximum absolute size of bytecode considered for inlining")
DEFINE_FLOAT(
reserve_inline_budget_scale_factor, 1.2,
"scale factor of bytecode size used to calculate the inlining budget")
DEFINE_INT(max_inlined_bytecode_size_small, 27,
"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,
999999)
DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size_absolute,
999999)
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(concurrent_osr, true, "enable concurrent OSR")
DEFINE_WEAK_IMPLICATION(future, concurrent_osr)
DEFINE_BOOL(trace_osr, false, "trace on-stack replacement")
DEFINE_BOOL(log_or_trace_osr, false,
"internal helper flag, please use --trace-osr instead.")
DEFINE_IMPLICATION(trace_osr, log_or_trace_osr)
DEFINE_IMPLICATION(log_function_events, log_or_trace_osr)
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_STRING(
turbo_profiling_output, nullptr,
"emit data about basic block usage in builtins to this file "
"(requires that V8 was built with v8_enable_builtins_profiling=true)")
DEFINE_BOOL(
warn_about_builtin_profile_data, false,
"flag for mksnapshot, emit warnings when applying builtin profile data")
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_IMPLICATION(turbo_stress_instruction_scheduling,
turbo_instruction_scheduling)
DEFINE_BOOL(turbo_store_elimination, true,
"enable store-store elimination in TurboFan")
DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
#if defined(V8_TARGET_ARCH_X64) || defined(V8_TARGET_ARCH_IA32)
DEFINE_BOOL(turbo_rewrite_far_jumps, true,
"rewrite far to near jumps (ia32,x64)")
#else
DEFINE_BOOL_READONLY(turbo_rewrite_far_jumps, false,
"rewrite far to near jumps (ia32,x64)")
#endif
DEFINE_BOOL(
stress_gc_during_compilation, false,
"simulate GC/compiler thread race related to https://crbug.com/v8/8520")
DEFINE_BOOL(turbo_fast_api_calls, true, "enable fast API calls from TurboFan")
#ifdef V8_USE_ZLIB
DEFINE_BOOL(turbo_compress_translation_arrays, false,
"compress translation arrays (experimental)")
#else
DEFINE_BOOL_READONLY(turbo_compress_translation_arrays, false,
"compress translation arrays (experimental)")
#endif // V8_USE_ZLIB
DEFINE_BOOL(turbo_inline_js_wasm_calls, true, "inline JS->Wasm calls")
DEFINE_BOOL(turbo_use_mid_tier_regalloc_for_huge_functions, true,
"fall back to the mid-tier register allocator for huge functions")
DEFINE_BOOL(turbo_force_mid_tier_regalloc, false,
"always use the mid-tier register allocator (for testing)")
DEFINE_BOOL(turbo_optimize_apply, true, "optimize Function.prototype.apply")
DEFINE_BOOL(turbo_collect_feedback_in_generic_lowering, true,
"enable experimental feedback collection in generic lowering.")
DEFINE_BOOL(isolate_script_cache_ageing, true,
"enable ageing of the isolate script cache.")
DEFINE_FLOAT(script_delay, 0, "busy wait [ms] on every Script::Run")
DEFINE_FLOAT(script_delay_once, 0, "busy wait [ms] on the first Script::Run")
DEFINE_FLOAT(script_delay_fraction, 0.0,
"busy wait after each Script::Run by the given fraction of the "
"run's duration")
DEFINE_BOOL(turboshaft, false, "enable TurboFan's Turboshaft phases for JS")
DEFINE_WEAK_IMPLICATION(future, turboshaft)
DEFINE_BOOL(turboshaft_trace_reduction, false,
"trace individual Turboshaft reduction steps")
DEFINE_BOOL(turboshaft_wasm, false,
"enable TurboFan's Turboshaft phases for wasm")
#ifdef DEBUG
DEFINE_UINT64(turboshaft_opt_bisect_limit, std::numeric_limits<uint64_t>::max(),
"stop applying optional optimizations after a specified number "
"of steps, useful for bisecting optimization bugs")
DEFINE_UINT64(turboshaft_opt_bisect_break, std::numeric_limits<uint64_t>::max(),
"abort after a specified number of steps, useful for bisecting "
"optimization bugs")
#endif // DEBUG
// Favor memory over execution speed.
DEFINE_BOOL(optimize_for_size, false,
"Enables optimizations which favor memory size over execution "
"speed")
DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, size_t{1})
// Flags for WebAssembly.
#if V8_ENABLE_WEBASSEMBLY
DEFINE_BOOL(wasm_generic_wrapper, true,
"allow use of the generic js-to-wasm wrapper instead of "
"per-signature wrappers")
DEFINE_BOOL(enable_wasm_arm64_generic_wrapper, false,
"allow use of the generic js-to-wasm wrapper instead of "
"per-signature wrappers on arm64")
DEFINE_WEAK_IMPLICATION(future, enable_wasm_arm64_generic_wrapper)
DEFINE_BOOL(expose_wasm, true, "expose wasm interface to JavaScript")