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@JacobLett
Created January 16, 2017 15:45
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node.js help flags
Options:
--experimental_extras (enable code compiled in via v8_experimental_extra_library_files)
type: bool default: false
--use_strict (enforce strict mode)
type: bool default: false
--es_staging (enable test-worthy harmony features (for internal use only))
type: bool default: false
--harmony (enable all completed harmony features)
type: bool default: false
--harmony_shipping (enable all shipped harmony features)
type: bool default: true
--intl_extra (additional V8 Intl functions)
type: bool default: false
--harmony_array_prototype_values (enable "harmony Array.prototype.values" (in progress))
type: bool default: false
--harmony_function_sent (enable "harmony function.sent" (in progress))
type: bool default: false
--harmony_sharedarraybuffer (enable "harmony sharedarraybuffer" (in progress))
type: bool default: false
--harmony_simd (enable "harmony simd" (in progress))
type: bool default: false
--harmony_explicit_tailcalls (enable "harmony explicit tail calls" (in progress))
type: bool default: false
--harmony_do_expressions (enable "harmony do-expressions" (in progress))
type: bool default: false
--harmony_restrictive_generators (enable "harmony restrictions on generator declarations" (in progress))
type: bool default: false
--harmony_regexp_named_captures (enable "harmony regexp named captures" (in progress))
type: bool default: false
--harmony_regexp_property (enable "harmony unicode regexp property classes" (in progress))
type: bool default: false
--harmony_for_in (enable "harmony for-in syntax" (in progress))
type: bool default: false
--harmony_trailing_commas (enable "harmony trailing commas in function parameter lists" (in progress))
type: bool default: false
--harmony_regexp_lookbehind (enable "harmony regexp lookbehind")
type: bool default: false
--harmony_tailcalls (enable "harmony tail calls")
type: bool default: false
--harmony_async_await (enable "harmony async-await")
type: bool default: false
--harmony_string_padding (enable "harmony String-padding methods")
type: bool default: false
--icu_case_mapping (enable "case mapping with ICU rather than Unibrow")
type: bool default: false
--harmony_restrictive_declarations (enable "harmony limitations on sloppy mode function declarations")
type: bool default: true
--harmony_object_values_entries (enable "harmony Object.values / Object.entries")
type: bool default: true
--harmony_object_own_property_descriptors (enable "harmony Object.getOwnPropertyDescriptors()")
type: bool default: true
--compiled_keyed_generic_loads (use optimizing compiler to generate keyed generic load stubs)
type: bool default: false
--allocation_site_pretenuring (pretenure with allocation sites)
type: bool default: true
--page_promotion (promote pages based on utilization)
type: bool default: true
--page_promotion_threshold (min percentage of live bytes on a page to enable fast evacuation)
type: int default: 70
--trace_pretenuring (trace pretenuring decisions of HAllocate instructions)
type: bool default: false
--trace_pretenuring_statistics (trace allocation site pretenuring statistics)
type: bool default: false
--track_fields (track fields with only smi values)
type: bool default: true
--track_double_fields (track fields with double values)
type: bool default: true
--track_heap_object_fields (track fields with heap values)
type: bool default: true
--track_computed_fields (track computed boilerplate fields)
type: bool default: true
--track_field_types (track field types)
type: bool default: true
--smi_binop (support smi representation in binary operations)
type: bool default: true
--optimize_for_size (Enables optimizations which favor memory size over execution speed)
type: bool default: false
--unbox_double_arrays (automatically unbox arrays of doubles)
type: bool default: true
--string_slices (use string slices)
type: bool default: true
--ignition (use ignition interpreter)
type: bool default: false
--ignition_staging (use ignition with all staged features)
type: bool default: false
--ignition_eager (eagerly compile and parse with ignition)
type: bool default: false
--ignition_filter (filter for ignition interpreter)
type: string default: *
--ignition_deadcode (use ignition dead code elimination optimizer)
type: bool default: true
--ignition_osr (enable support for OSR from ignition code)
type: bool default: false
--ignition_peephole (use ignition peephole optimizer)
type: bool default: true
--ignition_reo (use ignition register equivalence optimizer)
type: bool default: true
--ignition_filter_expression_positions (filter expression positions before the bytecode pipeline)
type: bool default: true
--ignition_preserve_bytecode (preserve generated bytecode even when switching tiers)
type: bool default: false
--print_bytecode (print bytecode generated by ignition interpreter)
type: bool default: false
--trace_ignition (trace the bytecodes executed by the ignition interpreter)
type: bool default: false
--trace_ignition_codegen (trace the codegen of ignition interpreter bytecode handlers)
type: bool default: false
--trace_ignition_dispatches (traces the dispatches to bytecode handlers by the ignition interpreter)
type: bool default: false
--trace_ignition_dispatches_output_file (the file to which the bytecode handler dispatch table is written (by default, the table is not written to a file))
type: string default: NULL
--crankshaft (use crankshaft)
type: bool default: true
--hydrogen_filter (optimization filter)
type: string default: *
--use_gvn (use hydrogen global value numbering)
type: bool default: true
--gvn_iterations (maximum number of GVN fix-point iterations)
type: int default: 3
--use_canonicalizing (use hydrogen instruction canonicalizing)
type: bool default: true
--use_inlining (use function inlining)
type: bool default: true
--use_escape_analysis (use hydrogen escape analysis)
type: bool default: true
--use_allocation_folding (use allocation folding)
type: bool default: true
--use_local_allocation_folding (only fold in basic blocks)
type: bool default: false
--use_write_barrier_elimination (eliminate write barriers targeting allocations in optimized code)
type: bool default: true
--max_inlining_levels (maximum number of inlining levels)
type: int default: 5
--max_inlined_source_size (maximum source size in bytes considered for a single inlining)
type: int default: 600
--max_inlined_nodes (maximum number of AST nodes considered for a single inlining)
type: int default: 196
--max_inlined_nodes_cumulative (maximum cumulative number of AST nodes considered for inlining)
type: int default: 400
--loop_invariant_code_motion (loop invariant code motion)
type: bool default: true
--fast_math (faster (but maybe less accurate) math functions)
type: bool default: true
--collect_megamorphic_maps_from_stub_cache (crankshaft harvests type feedback from stub cache)
type: bool default: false
--hydrogen_stats (print statistics for hydrogen)
type: bool default: false
--trace_check_elimination (trace check elimination phase)
type: bool default: false
--trace_environment_liveness (trace liveness of local variable slots)
type: bool default: false
--trace_hydrogen (trace generated hydrogen to file)
type: bool default: false
--trace_hydrogen_filter (hydrogen tracing filter)
type: string default: *
--trace_hydrogen_stubs (trace generated hydrogen for stubs)
type: bool default: false
--trace_hydrogen_file (trace hydrogen to given file name)
type: string default: NULL
--trace_phase (trace generated IR for specified phases)
type: string default: HLZ
--trace_inlining (trace inlining decisions)
type: bool default: false
--trace_load_elimination (trace load elimination)
type: bool default: false
--trace_store_elimination (trace store elimination)
type: bool default: false
--turbo_verify_store_elimination (verify store elimination more rigorously)
type: bool default: false
--trace_alloc (trace register allocator)
type: bool default: false
--trace_all_uses (trace all use positions)
type: bool default: false
--trace_range (trace range analysis)
type: bool default: false
--trace_gvn (trace global value numbering)
type: bool default: false
--trace_representation (trace representation types)
type: bool default: false
--trace_removable_simulates (trace removable simulates)
type: bool default: false
--trace_escape_analysis (trace hydrogen escape analysis)
type: bool default: false
--trace_allocation_folding (trace allocation folding)
type: bool default: false
--trace_track_allocation_sites (trace the tracking of allocation sites)
type: bool default: false
--trace_migration (trace object migration)
type: bool default: false
--trace_generalization (trace map generalization)
type: bool default: false
--stress_pointer_maps (pointer map for every instruction)
type: bool default: false
--stress_environments (environment for every instruction)
type: bool default: false
--deopt_every_n_times (deoptimize every n times a deopt point is passed)
type: int default: 0
--deopt_every_n_garbage_collections (deoptimize every n garbage collections)
type: int default: 0
--print_deopt_stress (print number of possible deopt points)
type: bool default: false
--trap_on_deopt (put a break point before deoptimizing)
type: bool default: false
--trap_on_stub_deopt (put a break point before deoptimizing a stub)
type: bool default: false
--deoptimize_uncommon_cases (deoptimize uncommon cases)
type: bool default: true
--polymorphic_inlining (polymorphic inlining)
type: bool default: true
--use_osr (use on-stack replacement)
type: bool default: true
--array_bounds_checks_elimination (perform array bounds checks elimination)
type: bool default: true
--trace_bce (trace array bounds check elimination)
type: bool default: false
--array_index_dehoisting (perform array index dehoisting)
type: bool default: true
--analyze_environment_liveness (analyze liveness of environment slots and zap dead values)
type: bool default: true
--load_elimination (use load elimination)
type: bool default: true
--check_elimination (use check elimination)
type: bool default: true
--store_elimination (use store elimination)
type: bool default: false
--dead_code_elimination (use dead code elimination)
type: bool default: true
--fold_constants (use constant folding)
type: bool default: true
--trace_dead_code_elimination (trace dead code elimination)
type: bool default: false
--unreachable_code_elimination (eliminate unreachable code)
type: bool default: true
--trace_osr (trace on-stack replacement)
type: bool default: false
--stress_runs (number of stress runs)
type: int default: 0
--lookup_sample_by_shared (when picking a function to optimize, watch for shared function info, not JSFunction itself)
type: bool default: true
--flush_optimized_code_cache (flushes the cache of optimized code for closures on every GC)
type: bool default: false
--inline_construct (inline constructor calls)
type: bool default: true
--inline_arguments (inline functions with arguments object)
type: bool default: true
--inline_accessors (inline JavaScript accessors)
type: bool default: true
--escape_analysis_iterations (maximum number of escape analysis fix-point iterations)
type: int default: 2
--concurrent_recompilation (optimizing hot functions asynchronously on a separate thread)
type: bool default: true
--trace_concurrent_recompilation (track concurrent recompilation)
type: bool default: false
--concurrent_recompilation_queue_length (the length of the concurrent compilation queue)
type: int default: 8
--concurrent_recompilation_delay (artificial compilation delay in ms)
type: int default: 0
--block_concurrent_recompilation (block queued jobs until released)
type: bool default: false
--omit_map_checks_for_leaf_maps (do not emit check maps for constant values that have a leaf map, deoptimize the optimized code if the layout of the maps changes.)
type: bool default: true
--turbo (enable TurboFan compiler)
type: bool default: false
--turbo_from_bytecode (enable building graphs from bytecode)
type: bool default: false
--turbo_sp_frame_access (use stack pointer-relative access to frame wherever possible)
type: bool default: false
--turbo_preprocess_ranges (run pre-register allocation heuristics)
type: bool default: true
--turbo_loop_stackcheck (enable stack checks in loops)
type: bool default: true
--turbo_filter (optimization filter for TurboFan compiler)
type: string default: ~~
--trace_turbo (trace generated TurboFan IR)
type: bool default: false
--trace_turbo_graph (trace generated TurboFan graphs)
type: bool default: false
--trace_turbo_cfg_file (trace turbo cfg graph (for C1 visualizer) to a given file name)
type: string default: NULL
--trace_turbo_types (trace TurboFan's types)
type: bool default: true
--trace_turbo_scheduler (trace TurboFan's scheduler)
type: bool default: false
--trace_turbo_reduction (trace TurboFan's various reducers)
type: bool default: false
--trace_turbo_trimming (trace TurboFan's graph trimmer)
type: bool default: false
--trace_turbo_jt (trace TurboFan's jump threading)
type: bool default: false
--trace_turbo_ceq (trace TurboFan's control equivalence)
type: bool default: false
--trace_turbo_loop (trace TurboFan's loop optimizations)
type: bool default: false
--turbo_asm (enable TurboFan for asm.js code)
type: bool default: true
--turbo_asm_deoptimization (enable deoptimization in TurboFan for asm.js code)
type: bool default: false
--turbo_verify (verify TurboFan graphs at each phase)
type: bool default: false
--turbo_stats (print TurboFan statistics)
type: bool default: false
--turbo_stats_nvp (print TurboFan statistics in machine-readable format)
type: bool default: false
--turbo_splitting (split nodes during scheduling in TurboFan)
type: bool default: true
--turbo_type_feedback (use typed feedback for representation inference in Turbofan)
type: bool default: true
--turbo_source_positions (track source code positions when building TurboFan IR)
type: bool default: false
--function_context_specialization (enable function context specialization in TurboFan)
type: bool default: false
--native_context_specialization (enable native context specialization in TurboFan)
type: bool default: true
--turbo_inlining (enable inlining in TurboFan)
type: bool default: true
--trace_turbo_inlining (trace TurboFan inlining)
type: bool default: false
--turbo_load_elimination (enable load elimination in TurboFan)
type: bool default: true
--trace_turbo_load_elimination (trace TurboFan load elimination)
type: bool default: false
--loop_assignment_analysis (perform loop assignment analysis)
type: bool default: true
--turbo_profiling (enable profiling in TurboFan)
type: bool default: false
--turbo_verify_allocation (verify register allocation in TurboFan)
type: bool default: false
--turbo_move_optimization (optimize gap moves in TurboFan)
type: bool default: true
--turbo_jt (enable jump threading in TurboFan)
type: bool default: true
--turbo_stress_loop_peeling (stress loop peeling optimization)
type: bool default: false
--turbo_loop_peeling (Turbofan loop peeling)
type: bool default: false
--turbo_loop_variable (Turbofan loop variable optimization)
type: bool default: true
--turbo_cf_optimization (optimize control flow in TurboFan)
type: bool default: true
--turbo_frame_elision (elide frames in TurboFan)
type: bool default: true
--turbo_cache_shared_code (cache context-independent code)
type: bool default: true
--turbo_preserve_shared_code (keep context-independent code)
type: bool default: false
--turbo_escape (enable escape analysis)
type: bool default: false
--turbo_instruction_scheduling (enable instruction scheduling in TurboFan)
type: bool default: false
--turbo_stress_instruction_scheduling (randomly schedule instructions to stress dependency tracking)
type: bool default: false
--turbo_store_elimination (enable store-store elimination in TurboFan)
type: bool default: false
--minimal (simplifies execution model to make porting easier (e.g. always use Ignition, never use Crankshaft)
type: bool default: false
--expose_wasm (expose WASM interface to JavaScript)
type: bool default: false
--wasm_num_compilation_tasks (number of parallel compilation tasks for wasm)
type: int default: 10
--trace_wasm_encoder (trace encoding of wasm code)
type: bool default: false
--trace_wasm_decoder (trace decoding of wasm code)
type: bool default: false
--trace_wasm_decode_time (trace decoding time of wasm code)
type: bool default: false
--trace_wasm_compiler (trace compiling of wasm code)
type: bool default: false
--trace_wasm_interpreter (trace interpretation of wasm code)
type: bool default: false
--trace_wasm_ast_start (start function for WASM AST trace (inclusive))
type: int default: 0
--trace_wasm_ast_end (end function for WASM AST trace (exclusive))
type: int default: 0
--skip_compiling_wasm_funcs (start compiling at function N)
type: int default: 0
--wasm_break_on_decoder_error (debug break when wasm decoder encounters an error)
type: bool default: false
--wasm_loop_assignment_analysis (perform loop assignment analysis for WASM)
type: bool default: true
--validate_asm (validate asm.js modules before compiling)
type: bool default: false
--dump_wasm_module (dump WASM module bytes)
type: bool default: false
--dump_wasm_module_path (directory to dump wasm modules to)
type: string default: NULL
--typed_array_max_size_in_heap (threshold for in-heap typed array)
type: int default: 64
--wasm_simd_prototype (enable prototype simd opcodes for wasm)
type: bool default: false
--wasm_eh_prototype (enable prototype exception handling opcodes for wasm)
type: bool default: false
--frame_count (number of stack frames inspected by the profiler)
type: int default: 1
--interrupt_budget (execution budget before interrupt is triggered)
type: int default: 6144
--type_info_threshold (percentage of ICs that must have type info to allow optimization)
type: int default: 25
--generic_ic_threshold (max percentage of megamorphic/generic ICs to allow optimization)
type: int default: 30
--self_opt_count (call count before self-optimization)
type: int default: 130
--trace_opt_verbose (extra verbose compilation tracing)
type: bool default: false
--debug_code (generate extra code (assertions) for debugging)
type: bool default: false
--code_comments (emit comments in code disassembly)
type: bool default: false
--enable_sse3 (enable use of SSE3 instructions if available)
type: bool default: true
--enable_sse4_1 (enable use of SSE4.1 instructions if available)
type: bool default: true
--enable_sahf (enable use of SAHF instruction if available (X64 only))
type: bool default: true
--enable_avx (enable use of AVX instructions if available)
type: bool default: true
--enable_fma3 (enable use of FMA3 instructions if available)
type: bool default: true
--enable_bmi1 (enable use of BMI1 instructions if available)
type: bool default: true
--enable_bmi2 (enable use of BMI2 instructions if available)
type: bool default: true
--enable_lzcnt (enable use of LZCNT instruction if available)
type: bool default: true
--enable_popcnt (enable use of POPCNT instruction if available)
type: bool default: true
--enable_vfp3 (enable use of VFP3 instructions if available)
type: bool default: true
--enable_armv7 (enable use of ARMv7 instructions if available (ARM only))
type: bool default: true
--enable_armv8 (enable use of ARMv8 instructions if available (ARM 32-bit only))
type: bool default: true
--enable_neon (enable use of NEON instructions if available (ARM only))
type: bool default: true
--enable_sudiv (enable use of SDIV and UDIV instructions if available (ARM only))
type: bool default: true
--enable_movw_movt (enable loading 32-bit constant by means of movw/movt instruction pairs (ARM only))
type: bool default: false
--enable_32dregs (enable use of d16-d31 registers on ARM - this requires VFP3)
type: bool default: true
--enable_vldr_imm (enable use of constant pools for double immediate (ARM only))
type: bool default: false
--force_long_branches (force all emitted branches to be in long mode (MIPS/PPC only))
type: bool default: false
--mcpu (enable optimization for specific cpu)
type: string default: auto
--enable_regexp_unaligned_accesses (enable unaligned accesses for the regexp engine)
type: bool default: true
--expose_natives_as (expose natives in global object)
type: string default: NULL
--expose_debug_as (expose debug in global object)
type: string default: NULL
--expose_free_buffer (expose freeBuffer extension)
type: bool default: false
--expose_gc (expose gc extension)
type: bool default: false
--expose_gc_as (expose gc extension under the specified name)
type: string default: NULL
--expose_externalize_string (expose externalize string extension)
type: bool default: false
--expose_trigger_failure (expose trigger-failure extension)
type: bool default: false
--stack_trace_limit (number of stack frames to capture)
type: int default: 10
--builtins_in_stack_traces (show built-in functions in stack traces)
type: bool default: false
--allow_unsafe_function_constructor (allow invoking the function constructor without security checks)
type: bool default: false
--inline_new (use fast inline allocation)
type: bool default: true
--trace_codegen (print name of functions for which code is generated)
type: bool default: false
--trace (trace function calls)
type: bool default: false
--mask_constants_with_cookie (use random jit cookie to mask large constants)
type: bool default: true
--lazy (use lazy compilation)
type: bool default: true
--trace_opt (trace lazy optimization)
type: bool default: false
--trace_opt_stats (trace lazy optimization statistics)
type: bool default: false
--trace_file_names (include file names in trace-opt/trace-deopt output)
type: bool default: false
--opt (use adaptive optimizations)
type: bool default: true
--always_opt (always try to optimize functions)
type: bool default: false
--always_osr (always try to OSR functions)
type: bool default: false
--prepare_always_opt (prepare for turning on always opt)
type: bool default: false
--trace_deopt (trace optimize function deoptimization)
type: bool default: false
--trace_stub_failures (trace deoptimization of generated code stubs)
type: bool default: false
--serialize_toplevel (enable caching of toplevel scripts)
type: bool default: true
--serialize_eager (compile eagerly when caching scripts)
type: bool default: false
--serialize_age_code (pre age code in the code cache)
type: bool default: false
--trace_serializer (print code serializer trace)
type: bool default: false
--min_preparse_length (minimum length for automatic enable preparsing)
type: int default: 1024
--max_opt_count (maximum number of optimization attempts before giving up.)
type: int default: 10
--compilation_cache (enable compilation cache)
type: bool default: true
--cache_prototype_transitions (cache prototype transitions)
type: bool default: true
--cpu_profiler_sampling_interval (CPU profiler sampling interval in microseconds)
type: int default: 1000
--trace_js_array_abuse (trace out-of-bounds accesses to JS arrays)
type: bool default: false
--trace_external_array_abuse (trace out-of-bounds-accesses to external arrays)
type: bool default: false
--trace_array_abuse (trace out-of-bounds accesses to all arrays)
type: bool default: false
--trace_debug_json (trace debugging JSON request/response)
type: bool default: false
--enable_liveedit (enable liveedit experimental feature)
type: bool default: true
--hard_abort (abort by crashing)
type: bool default: true
--stack_size (default size of stack region v8 is allowed to use (in kBytes))
type: int default: 984
--max_stack_trace_source_length (maximum length of function source code printed in a stack trace.)
type: int default: 300
--always_inline_smi_code (always inline smi code in non-opt code)
type: bool default: false
--verify_operand_stack_depth (emit debug code that verifies the static tracking of the operand stack depth)
type: bool default: false
--min_semi_space_size (min size of a semi-space (in MBytes), the new space consists of twosemi-spaces)
type: int default: 0
--max_semi_space_size (max size of a semi-space (in MBytes), the new space consists of twosemi-spaces)
type: int default: 0
--semi_space_growth_factor (factor by which to grow the new space)
type: int default: 2
--experimental_new_space_growth_heuristic (Grow the new space based on the percentage of survivors instead of their absolute value.)
type: bool default: false
--max_old_space_size (max size of the old space (in Mbytes))
type: int default: 0
--initial_old_space_size (initial old space size (in Mbytes))
type: int default: 0
--max_executable_size (max size of executable memory (in Mbytes))
type: int default: 0
--gc_global (always perform global GCs)
type: bool default: false
--gc_interval (garbage collect after <n> allocations)
type: int default: -1
--retain_maps_for_n_gc (keeps maps alive for <n> old space garbage collections)
type: int default: 2
--trace_gc (print one trace line following each garbage collection)
type: bool default: false
--trace_gc_nvp (print one detailed trace line in name=value format after each garbage collection)
type: bool default: false
--trace_gc_ignore_scavenger (do not print trace line after scavenger collection)
type: bool default: false
--trace_idle_notification (print one trace line following each idle notification)
type: bool default: false
--trace_idle_notification_verbose (prints the heap state used by the idle notification)
type: bool default: false
--print_cumulative_gc_stat (print cumulative GC statistics in name=value format on exit)
type: bool default: false
--print_max_heap_committed (print statistics of the maximum memory committed for the heap in name=value format on exit)
type: bool default: false
--trace_gc_verbose (print more details following each garbage collection)
type: bool default: false
--trace_allocation_stack_interval (print stack trace after <n> free-list allocations)
type: int default: -1
--trace_fragmentation (report fragmentation for old space)
type: bool default: false
--trace_fragmentation_verbose (report fragmentation for old space (detailed))
type: bool default: false
--trace_evacuation (report evacuation statistics)
type: bool default: false
--trace_mutator_utilization (print mutator utilization, allocation speed, gc speed)
type: bool default: false
--weak_embedded_maps_in_optimized_code (make maps embedded in optimized code weak)
type: bool default: true
--weak_embedded_objects_in_optimized_code (make objects embedded in optimized code weak)
type: bool default: true
--flush_code (flush code that we expect not to use again)
type: bool default: true
--trace_code_flushing (trace code flushing progress)
type: bool default: false
--age_code (track un-executed functions to age code and flush only old code (required for code flushing))
type: bool default: true
--incremental_marking (use incremental marking)
type: bool default: true
--incremental_marking_wrappers (use incremental marking for marking wrappers)
type: bool default: true
--min_progress_during_incremental_marking_finalization (keep finalizing incremental marking as long as we discover at least this many unmarked objects)
type: int default: 32
--max_incremental_marking_finalization_rounds (at most try this many times to finalize incremental marking)
type: int default: 3
--black_allocation (use black allocation)
type: bool default: false
--concurrent_sweeping (use concurrent sweeping)
type: bool default: true
--parallel_compaction (use parallel compaction)
type: bool default: true
--parallel_pointer_update (use parallel pointer update during compaction)
type: bool default: true
--trace_incremental_marking (trace progress of the incremental marking)
type: bool default: false
--track_gc_object_stats (track object counts and memory usage)
type: bool default: false
--trace_gc_object_stats (trace object counts and memory usage)
type: bool default: false
--track_detached_contexts (track native contexts that are expected to be garbage collected)
type: bool default: true
--trace_detached_contexts (trace native contexts that are expected to be garbage collected)
type: bool default: false
--move_object_start (enable moving of object starts)
type: bool default: true
--memory_reducer (use memory reducer)
type: bool default: true
--scavenge_reclaim_unmodified_objects (remove unmodified and unreferenced objects)
type: bool default: true
--heap_growing_percent (specifies heap growing factor as (1 + heap_growing_percent/100))
type: int default: 0
--clear_exceptions_on_js_entry (clear pending exceptions when entering JavaScript)
type: bool default: false
--histogram_interval (time interval in ms for aggregating memory histograms)
type: int default: 600000
--trace_object_groups (print object groups detected during each garbage collection)
type: bool default: false
--heap_profiler_trace_objects (Dump heap object allocations/movements/size_updates)
type: bool default: false
--sampling_heap_profiler_suppress_randomness (Use constant sample intervals to eliminate test flakiness)
type: bool default: false
--use_idle_notification (Use idle notification to reduce memory footprint.)
type: bool default: true
--use_ic (use inline caching)
type: bool default: true
--trace_ic (trace inline cache state transitions)
type: bool default: false
--tf_load_ic_stub (use TF LoadIC stub)
type: bool default: true
--native_code_counters (generate extra code for manipulating stats counters)
type: bool default: false
--always_compact (Perform compaction on every full GC)
type: bool default: false
--never_compact (Never perform compaction on full GC - testing only)
type: bool default: false
--compact_code_space (Compact code space on full collections)
type: bool default: true
--cleanup_code_caches_at_gc (Flush inline caches prior to mark compact collection and flush code caches in maps during mark compact cycle.)
type: bool default: true
--use_marking_progress_bar (Use a progress bar to scan large objects in increments when incremental marking is active.)
type: bool default: true
--zap_code_space (Zap free memory in code space with 0xCC while sweeping.)
type: bool default: false
--random_seed (Default seed for initializing random generator (0, the default, means to use system random).)
type: int default: 0
--trace_weak_arrays (Trace WeakFixedArray usage)
type: bool default: false
--trace_prototype_users (Trace updates to prototype user tracking)
type: bool default: false
--use_verbose_printer (allows verbose printing)
type: bool default: true
--trace_for_in_enumerate (Trace for-in enumerate slow-paths)
type: bool default: false
--allow_natives_syntax (allow natives syntax)
type: bool default: false
--trace_parse (trace parsing and preparsing)
type: bool default: false
--trace_sim (Trace simulator execution)
type: bool default: false
--debug_sim (Enable debugging the simulator)
type: bool default: false
--check_icache (Check icache flushes in ARM and MIPS simulator)
type: bool default: false
--stop_sim_at (Simulator stop after x number of instructions)
type: int default: 0
--sim_stack_alignment (Stack alingment in bytes in simulator (4 or 8, 8 is default))
type: int default: 8
--sim_stack_size (Stack size of the ARM64, MIPS64 and PPC64 simulator in kBytes (default is 2 MB))
type: int default: 2048
--log_regs_modified (When logging register values, only print modified registers.)
type: bool default: true
--log_colour (When logging, try to use coloured output.)
type: bool default: true
--ignore_asm_unimplemented_break (Don't break for ASM_UNIMPLEMENTED_BREAK macros.)
type: bool default: false
--trace_sim_messages (Trace simulator debug messages. Implied by --trace-sim.)
type: bool default: false
--stack_trace_on_illegal (print stack trace when an illegal exception is thrown)
type: bool default: false
--abort_on_uncaught_exception (abort program (dump core) when an uncaught exception is thrown)
type: bool default: false
--randomize_hashes (randomize hashes to avoid predictable hash collisions (with snapshots this option cannot override the baked-in seed))
type: bool default: true
--hash_seed (Fixed seed to use to hash property keys (0 means random)(with snapshots this option cannot override the baked-in seed))
type: int default: 0
--trace_rail (trace RAIL mode)
type: bool default: false
--runtime_call_stats (report runtime call counts and times)
type: bool default: false
--profile_deserialization (Print the time it takes to deserialize the snapshot.)
type: bool default: false
--serialization_statistics (Collect statistics on serialized objects.)
type: bool default: false
--regexp_optimization (generate optimized regexp code)
type: bool default: true
--testing_bool_flag (testing_bool_flag)
type: bool default: true
--testing_maybe_bool_flag (testing_maybe_bool_flag)
type: maybe_bool default: unset
--testing_int_flag (testing_int_flag)
type: int default: 13
--testing_float_flag (float-flag)
type: float default: 2.5
--testing_string_flag (string-flag)
type: string default: Hello, world!
--testing_prng_seed (Seed used for threading test randomness)
type: int default: 42
--startup_src (Write V8 startup as C++ src. (mksnapshot only))
type: string default: NULL
--startup_blob (Write V8 startup blob file. (mksnapshot only))
type: string default: NULL
--profile_hydrogen_code_stub_compilation (Print the time it takes to lazily compile hydrogen code stubs.)
type: bool default: false
--predictable (enable predictable mode)
type: bool default: false
--force_marking_deque_overflows (force overflows of marking deque by reducing it's size to 64 words)
type: bool default: false
--stress_compaction (stress the GC compactor to flush out bugs (implies --force_marking_deque_overflows))
type: bool default: false
--manual_evacuation_candidates_selection (Test mode only flag. It allows an unit test to select evacuation candidates pages (requires --stress_compaction).)
type: bool default: false
--external_allocation_limit_incremental_time (Time spent in incremental marking steps (in ms) once the external allocation limit is reached)
type: int default: 1
--disable_old_api_accessors (Disable old-style API accessors whose setters trigger through the prototype chain)
type: bool default: false
--help (Print usage message, including flags, on console)
type: bool default: true
--dump_counters (Dump counters on exit)
type: bool default: false
--map_counters (Map counters to a file)
type: string default:
--js_arguments (Pass all remaining arguments to the script. Alias for "--".)
type: arguments default:
--log (Minimal logging (no API, code, GC, suspect, or handles samples).)
type: bool default: false
--log_all (Log all events to the log file.)
type: bool default: false
--log_api (Log API events to the log file.)
type: bool default: false
--log_code (Log code events to the log file without profiling.)
type: bool default: false
--log_gc (Log heap samples on garbage collection for the hp2ps tool.)
type: bool default: false
--log_handles (Log global handle events.)
type: bool default: false
--log_suspect (Log suspect operations.)
type: bool default: false
--prof (Log statistical profiling information (implies --log-code).)
type: bool default: false
--prof_cpp (Like --prof, but ignore generated code.)
type: bool default: false
--prof_browser_mode (Used with --prof, turns on browser-compatible mode for profiling.)
type: bool default: true
--log_regexp (Log regular expression execution.)
type: bool default: false
--logfile (Specify the name of the log file.)
type: string default: v8.log
--logfile_per_isolate (Separate log files for each isolate.)
type: bool default: true
--ll_prof (Enable low-level linux profiler.)
type: bool default: false
--perf_basic_prof (Enable perf linux profiler (basic support).)
type: bool default: false
--perf_basic_prof_only_functions (Only report function code ranges to perf (i.e. no stubs).)
type: bool default: false
--perf_prof (Enable perf linux profiler (experimental annotate support).)
type: bool default: false
--perf_prof_debug_info (Enable debug info for perf linux profiler (experimental).)
type: bool default: false
--perf_prof_unwinding_info (Enable unwinding info for perf linux profiler (experimental).)
type: bool default: false
--gc_fake_mmap (Specify the name of the file for fake gc mmap used in ll_prof)
type: string default: /tmp/__v8_gc__
--log_internal_timer_events (Time internal events.)
type: bool default: false
--log_timer_events (Time events including external callbacks.)
type: bool default: false
--log_instruction_stats (Log AArch64 instruction statistics.)
type: bool default: false
--log_instruction_file (AArch64 instruction statistics log file.)
type: string default: arm64_inst.csv
--log_instruction_period (AArch64 instruction statistics logging period.)
type: int default: 4194304
--redirect_code_traces (output deopt information and disassembly into file code-<pid>-<isolate id>.asm)
type: bool default: false
--redirect_code_traces_to (output deopt information and disassembly into the given file)
type: string default: NULL
--hydrogen_track_positions (track source code positions when building IR)
type: bool default: false
--trace_elements_transitions (trace elements transitions)
type: bool default: false
--trace_creation_allocation_sites (trace the creation of allocation sites)
type: bool default: false
--print_code_stubs (print code stubs)
type: bool default: false
--test_secondary_stub_cache (test secondary stub cache by disabling the primary one)
type: bool default: false
--test_primary_stub_cache (test primary stub cache by disabling the secondary one)
type: bool default: false
--print_code (print generated code)
type: bool default: false
--print_opt_code (print optimized code)
type: bool default: false
--print_unopt_code (print unoptimized code before printing optimized code based on it)
type: bool default: false
--print_code_verbose (print more information for code)
type: bool default: false
--print_builtin_code (print generated code for builtins)
type: bool default: false
--sodium (print generated code output suitable for use with the Sodium code viewer)
type: bool default: false
--print_all_code (enable all flags related to printing code)
type: bool default: false
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