Test std/:

    1. cargo test std_tests

    Lint and format

    Lint the code:

    1. deno run -A --unstable ./tools/lint.js

    Format the code:

    To start profiling:

    1. # Make sure we're only building release.
    2. # Build deno and V8's d8.
    3. ninja -C target/release d8
    5. # Start the program we want to benchmark with --prof
    6. ./target/release/deno run tests/http_bench.ts --allow-net --v8-flags=--prof &
    8. # Exercise it.
    9. third_party/wrk/linux/wrk http://localhost:4500/
    10. kill `pgrep deno`
    1. D8_PATH=target/release/ ./third_party/v8/tools/linux-tick-processor
    2. isolate-0x7fad98242400-v8.log > prof.log
    3. # on macOS, use ./third_party/v8/tools/mac-tick-processor instead

    prof.log will contain information about tick distribution of different calls.

    To view the log with Web UI, generate JSON file of the log:

    Open third_party/v8/tools/profview/index.html in your browser, and select prof.json to view the distribution graphically.

    Useful V8 flags during profiling:

    • --prof
    • --log-internal-timer-events
    • --log-timer-events
    • --track-gc
    • --log-source-code
    • --track-gc-object-stats

    Debugging with LLDB

    To debug the deno binary, we can use rust-lldb. It should come with rustc and is a wrapper around LLDB.

    1. $ rust-lldb -- ./target/debug/deno run --allow-net tests/http_bench.ts
    2. # On macOS, you might get warnings like
    3. # `ImportError: cannot import name _remove_dead_weakref`
    4. # In that case, use system python by setting PATH, e.g.
    5. # PATH=/System/Library/Frameworks/Python.framework/Versions/2.7/bin:$PATH
    6. (lldb) command script import "/Users/kevinqian/.rustup/toolchains/1.36.0-x86_64-apple-darwin/lib/rustlib/etc/lldb_rust_formatters.py"
    7. (lldb) type summary add --no-value --python-function lldb_rust_formatters.print_val -x ".*" --category Rust
    8. (lldb) type category enable Rust
    9. (lldb) target create "../deno/target/debug/deno"
    10. Current executable set to '../deno/target/debug/deno' (x86_64).
    11. (lldb) settings set -- target.run-args  "tests/http_bench.ts" "--allow-net"
    12. (lldb) b op_start
    13. (lldb) r

    V8 has many many internal command-line flags:

    1. $ deno run --v8-flags=--help _
    2. SSE3=1 SSSE3=1 SSE4_1=1 SSE4_2=1 SAHF=1 AVX=1 FMA3=1 BMI1=1 BMI2=1 LZCNT=1 POPCNT=1 ATOM=0
    3. Synopsis:
    4.   shell [options] [--shell] [<file>...]
    5.   d8 [options] [-e <string>] [--shell] [[--module] <file>...]
    7.   -e        execute a string in V8
    8.   --shell   run an interactive JavaScript shell
    9.   --module  execute a file as a JavaScript module
    11. Note: the --module option is implicitly enabled for *.mjs files.
    13. The following syntax for options is accepted (both '-' and '--' are ok):
    14.   --flag        (bool flags only)
    15.   --no-flag     (bool flags only)
    16.   --flag=value  (non-bool flags only, no spaces around '=')
    17.   --flag value  (non-bool flags only)
    18.   --            (captures all remaining args in JavaScript)
    20. Options:
    21.   --use-strict (enforce strict mode)
    22.         type: bool  default: false
    23.   --es-staging (enable test-worthy harmony features (for internal use only))
    24.         type: bool  default: false
    25.   --harmony (enable all completed harmony features)
    26.         type: bool  default: false
    27.   --harmony-shipping (enable all shipped harmony features)
    28.         type: bool  default: true
    29.   --harmony-regexp-sequence (enable "RegExp Unicode sequence properties" (in progress))
    30.         type: bool  default: false
    31.   --harmony-weak-refs-with-cleanup-some (enable "harmony weak references with FinalizationRegistry.prototype.cleanupSome" (in progress))
    32.         type: bool  default: false
    33.   --harmony-regexp-match-indices (enable "harmony regexp match indices" (in progress))
    34.         type: bool  default: false
    35.   --harmony-top-level-await (enable "harmony top level await")
    36.         type: bool  default: false
    37.   --harmony-namespace-exports (enable "harmony namespace exports (export * as foo from 'bar')")
    38.         type: bool  default: true
    39.   --harmony-sharedarraybuffer (enable "harmony sharedarraybuffer")
    40.         type: bool  default: true
    41.   --harmony-import-meta (enable "harmony import.meta property")
    42.         type: bool  default: true
    43.   --harmony-dynamic-import (enable "harmony dynamic import")
    44.         type: bool  default: true
    45.   --harmony-promise-all-settled (enable "harmony Promise.allSettled")
    46.         type: bool  default: true
    47.   --harmony-promise-any (enable "harmony Promise.any")
    48.         type: bool  default: true
    49.   --harmony-private-methods (enable "harmony private methods in class literals")
    50.         type: bool  default: true
    51.   --harmony-weak-refs (enable "harmony weak references")
    52.         type: bool  default: true
    53.   --harmony-string-replaceall (enable "harmony String.prototype.replaceAll")
    54.         type: bool  default: true
    55.   --harmony-logical-assignment (enable "harmony logical assignment")
    56.         type: bool  default: true
    57.   --lite-mode (enables trade-off of performance for memory savings)
    58.         type: bool  default: false
    59.   --future (Implies all staged features that we want to ship in the not-too-far future)
    60.         type: bool  default: false
    61.   --assert-types (generate runtime type assertions to test the typer)
    62.         type: bool  default: false
    63.   --allocation-site-pretenuring (pretenure with allocation sites)
    64.         type: bool  default: true
    65.   --page-promotion (promote pages based on utilization)
    66.         type: bool  default: true
    67.   --always-promote-young-mc (always promote young objects during mark-compact)
    68.         type: bool  default: true
    69.   --page-promotion-threshold (min percentage of live bytes on a page to enable fast evacuation)
    70.         type: int  default: 70
    71.   --trace-pretenuring (trace pretenuring decisions of HAllocate instructions)
    72.         type: bool  default: false
    73.   --trace-pretenuring-statistics (trace allocation site pretenuring statistics)
    74.         type: bool  default: false
    75.   --track-fields (track fields with only smi values)
    76.         type: bool  default: true
    77.   --track-double-fields (track fields with double values)
    78.         type: bool  default: true
    79.   --track-heap-object-fields (track fields with heap values)
    80.         type: bool  default: true
    81.   --track-computed-fields (track computed boilerplate fields)
    82.         type: bool  default: true
    83.   --track-field-types (track field types)
    84.         type: bool  default: true
    85.   --trace-block-coverage (trace collected block coverage information)
    86.         type: bool  default: false
    87.   --trace-protector-invalidation (trace protector cell invalidations)
    88.         type: bool  default: false
    89.   --feedback-normalization (feed back normalization to constructors)
    90.         type: bool  default: false
    91.   --enable-one-shot-optimization (Enable size optimizations for the code that will only be executed once)
    92.         type: bool  default: false
    93.   --unbox-double-arrays (automatically unbox arrays of doubles)
    94.         type: bool  default: true
    95.   --interrupt-budget (interrupt budget which should be used for the profiler counter)
    96.         type: int  default: 147456
    97.   --jitless (Disable runtime allocation of executable memory.)
    98.         type: bool  default: false
    99.   --use-ic (use inline caching)
    100.         type: bool  default: true
    101.   --budget-for-feedback-vector-allocation (The budget in amount of bytecode executed by a function before we decide to allocate feedback vectors)
    102.         type: int  default: 1024
    103.   --lazy-feedback-allocation (Allocate feedback vectors lazily)
    104.         type: bool  default: true
    105.   --ignition-elide-noneffectful-bytecodes (elide bytecodes which won't have any external effect)
    106.         type: bool  default: true
    107.   --ignition-reo (use ignition register equivalence optimizer)
    108.         type: bool  default: true
    109.   --ignition-filter-expression-positions (filter expression positions before the bytecode pipeline)
    110.         type: bool  default: true
    111.   --ignition-share-named-property-feedback (share feedback slots when loading the same named property from the same object)
    112.         type: bool  default: true
    113.   --print-bytecode (print bytecode generated by ignition interpreter)
    114.         type: bool  default: false
    115.   --enable-lazy-source-positions (skip generating source positions during initial compile but regenerate when actually required)
    116.         type: bool  default: true
    117.   --stress-lazy-source-positions (collect lazy source positions immediately after lazy compile)
    118.         type: bool  default: false
    119.   --print-bytecode-filter (filter for selecting which functions to print bytecode)
    120.         type: string  default: *
    121.   --trace-ignition-codegen (trace the codegen of ignition interpreter bytecode handlers)
    122.         type: bool  default: false
    123.   --trace-ignition-dispatches (traces the dispatches to bytecode handlers by the ignition interpreter)
    124.         type: bool  default: false
    125.   --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))
    126.         type: string  default: nullptr
    127.   --fast-math (faster (but maybe less accurate) math functions)
    128.         type: bool  default: true
    129.   --trace-track-allocation-sites (trace the tracking of allocation sites)
    130.         type: bool  default: false
    131.   --trace-migration (trace object migration)
    132.         type: bool  default: false
    133.   --trace-generalization (trace map generalization)
    134.         type: bool  default: false
    135.   --turboprop (enable experimental turboprop mid-tier compiler.)
    136.         type: bool  default: false
    137.   --concurrent-recompilation (optimizing hot functions asynchronously on a separate thread)
    138.         type: bool  default: true
    139.   --trace-concurrent-recompilation (track concurrent recompilation)
    140.         type: bool  default: false
    141.   --concurrent-recompilation-queue-length (the length of the concurrent compilation queue)
    142.         type: int  default: 8
    143.   --concurrent-recompilation-delay (artificial compilation delay in ms)
    144.         type: int  default: 0
    145.   --block-concurrent-recompilation (block queued jobs until released)
    146.         type: bool  default: false
    147.   --concurrent-inlining (run optimizing compiler's inlining phase on a separate thread)
    148.         type: bool  default: false
    149.   --max-serializer-nesting (maximum levels for nesting child serializers)
    150.         type: int  default: 25
    151.   --trace-heap-broker-verbose (trace the heap broker verbosely (all reports))
    152.         type: bool  default: false
    153.   --trace-heap-broker-memory (trace the heap broker memory (refs analysis and zone numbers))
    154.         type: bool  default: false
    155.   --trace-heap-broker (trace the heap broker (reports on missing data only))
    156.         type: bool  default: false
    157.   --stress-runs (number of stress runs)
    158.         type: int  default: 0
    159.   --deopt-every-n-times (deoptimize every n times a deopt point is passed)
    160.         type: int  default: 0
    161.   --print-deopt-stress (print number of possible deopt points)
    162.         type: bool  default: false
    163.   --opt (use adaptive optimizations)
    164.         type: bool  default: true
    165.   --turbo-sp-frame-access (use stack pointer-relative access to frame wherever possible)
    166.         type: bool  default: false
    167.   --turbo-control-flow-aware-allocation (consider control flow while allocating registers)
    168.         type: bool  default: true
    169.   --turbo-filter (optimization filter for TurboFan compiler)
    170.         type: string  default: *
    171.   --trace-turbo (trace generated TurboFan IR)
    172.         type: bool  default: false
    173.   --trace-turbo-path (directory to dump generated TurboFan IR to)
    174.         type: string  default: nullptr
    175.   --trace-turbo-filter (filter for tracing turbofan compilation)
    176.         type: string  default: *
    177.   --trace-turbo-graph (trace generated TurboFan graphs)
    178.         type: bool  default: false
    179.   --trace-turbo-scheduled (trace TurboFan IR with schedule)
    180.         type: bool  default: false
    181.   --trace-turbo-cfg-file (trace turbo cfg graph (for C1 visualizer) to a given file name)
    182.         type: string  default: nullptr
    183.   --trace-turbo-types (trace TurboFan's types)
    184.         type: bool  default: true
    185.   --trace-turbo-scheduler (trace TurboFan's scheduler)
    186.         type: bool  default: false
    187.   --trace-turbo-reduction (trace TurboFan's various reducers)
    188.         type: bool  default: false
    189.   --trace-turbo-trimming (trace TurboFan's graph trimmer)
    190.         type: bool  default: false
    191.   --trace-turbo-jt (trace TurboFan's jump threading)
    192.         type: bool  default: false
    193.   --trace-turbo-ceq (trace TurboFan's control equivalence)
    194.         type: bool  default: false
    195.   --trace-turbo-loop (trace TurboFan's loop optimizations)
    196.         type: bool  default: false
    197.   --trace-turbo-alloc (trace TurboFan's register allocator)
    198.         type: bool  default: false
    199.   --trace-all-uses (trace all use positions)
    200.         type: bool  default: false
    201.   --trace-representation (trace representation types)
    202.         type: bool  default: false
    203.   --turbo-verify (verify TurboFan graphs at each phase)
    204.         type: bool  default: false
    205.   --turbo-verify-machine-graph (verify TurboFan machine graph before instruction selection)
    206.         type: string  default: nullptr
    207.   --trace-verify-csa (trace code stubs verification)
    208.         type: bool  default: false
    209.   --csa-trap-on-node (trigger break point when a node with given id is created in given stub. The format is: StubName,NodeId)
    210.         type: string  default: nullptr
    211.   --turbo-stats (print TurboFan statistics)
    212.         type: bool  default: false
    213.   --turbo-stats-nvp (print TurboFan statistics in machine-readable format)
    214.         type: bool  default: false
    215.   --turbo-stats-wasm (print TurboFan statistics of wasm compilations)
    216.         type: bool  default: false
    217.   --turbo-splitting (split nodes during scheduling in TurboFan)
    218.         type: bool  default: true
    219.   --function-context-specialization (enable function context specialization in TurboFan)
    220.         type: bool  default: false
    221.   --turbo-inlining (enable inlining in TurboFan)
    222.         type: bool  default: true
    223.   --max-inlined-bytecode-size (maximum size of bytecode for a single inlining)
    224.         type: int  default: 500
    225.   --max-inlined-bytecode-size-cumulative (maximum cumulative size of bytecode considered for inlining)
    226.         type: int  default: 1000
    227.   --max-inlined-bytecode-size-absolute (maximum cumulative size of bytecode considered for inlining)
    228.         type: int  default: 5000
    229.   --reserve-inline-budget-scale-factor (maximum cumulative size of bytecode considered for inlining)
    230.         type: float  default: 1.2
    231.   --max-inlined-bytecode-size-small (maximum size of bytecode considered for small function inlining)
    232.         type: int  default: 30
    233.   --max-optimized-bytecode-size (maximum bytecode size to be considered for optimization; too high values may cause the compiler to hit (release) assertions)
    234.         type: int  default: 61440
    235.   --min-inlining-frequency (minimum frequency for inlining)
    236.         type: float  default: 0.15
    237.   --polymorphic-inlining (polymorphic inlining)
    238.         type: bool  default: true
    239.   --stress-inline (set high thresholds for inlining to inline as much as possible)
    240.         type: bool  default: false
    241.   --trace-turbo-inlining (trace TurboFan inlining)
    242.         type: bool  default: false
    243.   --turbo-inline-array-builtins (inline array builtins in TurboFan code)
    244.         type: bool  default: true
    245.   --use-osr (use on-stack replacement)
    246.         type: bool  default: true
    247.   --trace-osr (trace on-stack replacement)
    248.         type: bool  default: false
    249.   --analyze-environment-liveness (analyze liveness of environment slots and zap dead values)
    250.         type: bool  default: true
    251.   --trace-environment-liveness (trace liveness of local variable slots)
    252.         type: bool  default: false
    253.   --turbo-load-elimination (enable load elimination in TurboFan)
    254.         type: bool  default: true
    255.   --trace-turbo-load-elimination (trace TurboFan load elimination)
    256.         type: bool  default: false
    257.   --turbo-profiling (enable basic block profiling in TurboFan)
    258.         type: bool  default: false
    259.   --turbo-profiling-verbose (enable basic block profiling in TurboFan, and include each function's schedule and disassembly in the output)
    260.         type: bool  default: false
    261.   --turbo-verify-allocation (verify register allocation in TurboFan)
    262.         type: bool  default: false
    263.   --turbo-move-optimization (optimize gap moves in TurboFan)
    264.         type: bool  default: true
    265.   --turbo-jt (enable jump threading in TurboFan)
    266.         type: bool  default: true
    267.   --turbo-loop-peeling (Turbofan loop peeling)
    268.         type: bool  default: true
    269.   --turbo-loop-variable (Turbofan loop variable optimization)
    270.         type: bool  default: true
    271.   --turbo-loop-rotation (Turbofan loop rotation)
    272.         type: bool  default: true
    273.   --turbo-cf-optimization (optimize control flow in TurboFan)
    274.         type: bool  default: true
    275.   --turbo-escape (enable escape analysis)
    276.         type: bool  default: true
    277.   --turbo-allocation-folding (Turbofan allocation folding)
    278.         type: bool  default: true
    279.   --turbo-instruction-scheduling (enable instruction scheduling in TurboFan)
    280.         type: bool  default: false
    281.   --turbo-stress-instruction-scheduling (randomly schedule instructions to stress dependency tracking)
    282.         type: bool  default: false
    283.   --turbo-store-elimination (enable store-store elimination in TurboFan)
    284.         type: bool  default: true
    285.   --trace-store-elimination (trace store elimination)
    286.         type: bool  default: false
    287.   --turbo-rewrite-far-jumps (rewrite far to near jumps (ia32,x64))
    288.         type: bool  default: true
    289.   --stress-gc-during-compilation (simulate GC/compiler thread race related to https://crbug.com/v8/8520)
    290.         type: bool  default: false
    291.   --turbo-fast-api-calls (enable fast API calls from TurboFan)
    292.         type: bool  default: false
    293.   --reuse-opt-code-count (don't discard optimized code for the specified number of deopts.)
    294.         type: int  default: 0
    295.   --turbo-nci (enable experimental native context independent code.)
    296.         type: bool  default: false
    297.   --turbo-nci-as-highest-tier (replace default TF with NCI code as the highest tier for testing purposes.)
    298.         type: bool  default: false
    299.   --print-nci-code (print native context independent code.)
    300.         type: bool  default: false
    301.   --trace-turbo-nci (trace native context independent code.)
    302.         type: bool  default: false
    303.   --turbo-collect-feedback-in-generic-lowering (enable experimental feedback collection in generic lowering.)
    304.         type: bool  default: false
    305.   --optimize-for-size (Enables optimizations which favor memory size over execution speed)
    306.   --untrusted-code-mitigations (Enable mitigations for executing untrusted code)
    307.         type: bool  default: false
    308.   --expose-wasm (expose wasm interface to JavaScript)
    310.   --assume-asmjs-origin (force wasm decoder to assume input is internal asm-wasm format)
    311.         type: bool  default: false
    312.   --wasm-num-compilation-tasks (maximum number of parallel compilation tasks for wasm)
    313.         type: int  default: 128
    314.   --wasm-write-protect-code-memory (write protect code memory on the wasm native heap)
    315.         type: bool  default: false
    316.   --wasm-async-compilation (enable actual asynchronous compilation for WebAssembly.compile)
    317.         type: bool  default: true
    318.   --wasm-test-streaming (use streaming compilation instead of async compilation for tests)
    319.         type: bool  default: false
    320.   --wasm-max-mem-pages (maximum initial number of 64KiB memory pages of a wasm instance)
    321.         type: uint  default: 32767
    322.   --wasm-max-mem-pages-growth (maximum number of 64KiB pages a Wasm memory can grow to)
    323.         type: uint  default: 65536
    324.   --wasm-max-table-size (maximum table size of a wasm instance)
    325.         type: uint  default: 10000000
    326.   --wasm-max-code-space (maximum committed code space for wasm (in MB))
    327.         type: uint  default: 1024
    328.   --wasm-tier-up (enable tier up to the optimizing compiler (requires --liftoff to have an effect))
    329.         type: bool  default: true
    330.   --trace-wasm-ast-start (start function for wasm AST trace (inclusive))
    331.         type: int  default: 0
    332.   --trace-wasm-ast-end (end function for wasm AST trace (exclusive))
    333.         type: int  default: 0
    334.   --liftoff (enable Liftoff, the baseline compiler for WebAssembly)
    335.         type: bool  default: true
    336.   --trace-wasm-memory (print all memory updates performed in wasm code)
    337.         type: bool  default: false
    338.   --wasm-tier-mask-for-testing (bitmask of functions to compile with TurboFan instead of Liftoff)
    339.         type: int  default: 0
    340.   --wasm-expose-debug-eval (Expose wasm evaluator support on the CDP)
    341.         type: bool  default: false
    342.   --validate-asm (validate asm.js modules before compiling)
    343.         type: bool  default: true
    344.   --suppress-asm-messages (don't emit asm.js related messages (for golden file testing))
    345.         type: bool  default: false
    346.   --trace-asm-time (log asm.js timing info to the console)
    347.         type: bool  default: false
    348.   --trace-asm-scanner (log tokens encountered by asm.js scanner)
    349.         type: bool  default: false
    350.   --trace-asm-parser (verbose logging of asm.js parse failures)
    351.         type: bool  default: false
    352.   --stress-validate-asm (try to validate everything as asm.js)
    353.         type: bool  default: false
    354.   --dump-wasm-module-path (directory to dump wasm modules to)
    355.         type: string  default: nullptr
    356.   --experimental-wasm-eh (enable prototype exception handling opcodes for wasm)
    357.         type: bool  default: false
    358.   --experimental-wasm-simd (enable prototype SIMD opcodes for wasm)
    359.         type: bool  default: false
    360.   --experimental-wasm-return-call (enable prototype return call opcodes for wasm)
    361.         type: bool  default: false
    362.   --experimental-wasm-compilation-hints (enable prototype compilation hints section for wasm)
    363.         type: bool  default: false
    364.   --experimental-wasm-gc (enable prototype garbage collection for wasm)
    365.         type: bool  default: false
    366.   --experimental-wasm-typed-funcref (enable prototype typed function references for wasm)
    367.         type: bool  default: false
    368.   --experimental-wasm-reftypes (enable prototype reference type opcodes for wasm)
    369.         type: bool  default: false
    370.   --experimental-wasm-threads (enable prototype thread opcodes for wasm)
    371.         type: bool  default: false
    372.   --experimental-wasm-type-reflection (enable prototype wasm type reflection in JS for wasm)
    373.         type: bool  default: false
    374.   --experimental-wasm-bigint (enable prototype JS BigInt support for wasm)
    375.         type: bool  default: true
    376.   --experimental-wasm-bulk-memory (enable prototype bulk memory opcodes for wasm)
    377.         type: bool  default: true
    378.   --experimental-wasm-mv (enable prototype multi-value support for wasm)
    379.         type: bool  default: true
    380.   --wasm-staging (enable staged wasm features)
    381.         type: bool  default: false
    382.   --wasm-opt (enable wasm optimization)
    383.         type: bool  default: false
    384.   --wasm-bounds-checks (enable bounds checks (disable for performance testing only))
    385.         type: bool  default: true
    386.   --wasm-stack-checks (enable stack checks (disable for performance testing only))
    387.         type: bool  default: true
    388.   --wasm-math-intrinsics (intrinsify some Math imports into wasm)
    389.         type: bool  default: true
    390.   --wasm-trap-handler (use signal handlers to catch out of bounds memory access in wasm (currently Linux x86_64 only))
    391.         type: bool  default: true
    392.   --wasm-fuzzer-gen-test (generate a test case when running a wasm fuzzer)
    393.         type: bool  default: false
    394.   --print-wasm-code (Print WebAssembly code)
    395.         type: bool  default: false
    396.   --print-wasm-stub-code (Print WebAssembly stub code)
    397.         type: bool  default: false
    398.   --asm-wasm-lazy-compilation (enable lazy compilation for asm-wasm modules)
    399.         type: bool  default: false
    400.   --wasm-lazy-compilation (enable lazy compilation for all wasm modules)
    401.         type: bool  default: false
    402.   --wasm-lazy-validation (enable lazy validation for lazily compiled wasm functions)
    403.         type: bool  default: false
    404.   --wasm-atomics-on-non-shared-memory (allow atomic operations on non-shared WebAssembly memory)
    405.         type: bool  default: true
    406.   --wasm-grow-shared-memory (allow growing shared WebAssembly memory objects)
    407.         type: bool  default: true
    408.   --wasm-simd-post-mvp (allow experimental SIMD operations for prototyping that are not included in the current proposal)
    409.         type: bool  default: false
    410.   --wasm-code-gc (enable garbage collection of wasm code)
    411.         type: bool  default: true
    412.   --trace-wasm-code-gc (trace garbage collection of wasm code)
    413.         type: bool  default: false
    414.   --stress-wasm-code-gc (stress test garbage collection of wasm code)
    415.         type: bool  default: false
    416.   --wasm-max-initial-code-space-reservation (maximum size of the initial wasm code space reservation (in MB))
    417.         type: int  default: 0
    418.   --frame-count (number of stack frames inspected by the profiler)
    419.         type: int  default: 1
    420.   --stress-sampling-allocation-profiler (Enables sampling allocation profiler with X as a sample interval)
    421.         type: int  default: 0
    422.   --lazy-new-space-shrinking (Enables the lazy new space shrinking strategy)
    423.         type: bool  default: false
    424.   --min-semi-space-size (min size of a semi-space (in MBytes), the new space consists of two semi-spaces)
    425.         type: size_t  default: 0
    426.   --max-semi-space-size (max size of a semi-space (in MBytes), the new space consists of two semi-spaces)
    427.         type: size_t  default: 0
    428.   --semi-space-growth-factor (factor by which to grow the new space)
    429.         type: int  default: 2
    430.   --max-old-space-size (max size of the old space (in Mbytes))
    431.         type: size_t  default: 0
    432.   --max-heap-size (max size of the heap (in Mbytes) both max_semi_space_size and max_old_space_size take precedence. All three flags cannot be specified at the same time.)
    433.         type: size_t  default: 0
    434.   --initial-heap-size (initial size of the heap (in Mbytes))
    435.         type: size_t  default: 0
    436.   --huge-max-old-generation-size (Increase max size of the old space to 4 GB for x64 systems withthe physical memory bigger than 16 GB)
    437.         type: bool  default: true
    438.   --initial-old-space-size (initial old space size (in Mbytes))
    439.         type: size_t  default: 0
    440.   --global-gc-scheduling (enable GC scheduling based on global memory)
    441.         type: bool  default: true
    442.   --gc-global (always perform global GCs)
    443.         type: bool  default: false
    444.   --random-gc-interval (Collect garbage after random(0, X) allocations. It overrides gc_interval.)
    445.         type: int  default: 0
    446.   --gc-interval (garbage collect after <n> allocations)
    447.         type: int  default: -1
    448.   --retain-maps-for-n-gc (keeps maps alive for <n> old space garbage collections)
    449.         type: int  default: 2
    450.   --trace-gc (print one trace line following each garbage collection)
    451.         type: bool  default: false
    452.   --trace-gc-nvp (print one detailed trace line in name=value format after each garbage collection)
    453.         type: bool  default: false
    454.   --trace-gc-ignore-scavenger (do not print trace line after scavenger collection)
    455.         type: bool  default: false
    456.   --trace-idle-notification (print one trace line following each idle notification)
    457.         type: bool  default: false
    458.   --trace-idle-notification-verbose (prints the heap state used by the idle notification)
    459.         type: bool  default: false
    460.   --trace-gc-verbose (print more details following each garbage collection)
    461.         type: bool  default: false
    462.   --trace-gc-freelists (prints details of each freelist before and after each major garbage collection)
    463.         type: bool  default: false
    464.   --trace-gc-freelists-verbose (prints details of freelists of each page before and after each major garbage collection)
    465.         type: bool  default: false
    466.   --trace-evacuation-candidates (Show statistics about the pages evacuation by the compaction)
    467.         type: bool  default: false
    468.   --trace-allocations-origins (Show statistics about the origins of allocations. Combine with --no-inline-new to track allocations from generated code)
    469.         type: bool  default: false
    470.   --trace-allocation-stack-interval (print stack trace after <n> free-list allocations)
    471.         type: int  default: -1
    472.   --trace-duplicate-threshold-kb (print duplicate objects in the heap if their size is more than given threshold)
    473.         type: int  default: 0
    474.   --trace-fragmentation (report fragmentation for old space)
    475.         type: bool  default: false
    476.   --trace-fragmentation-verbose (report fragmentation for old space (detailed))
    477.         type: bool  default: false
    478.   --minor-mc-trace-fragmentation (trace fragmentation after marking)
    479.         type: bool  default: false
    480.   --trace-evacuation (report evacuation statistics)
    481.         type: bool  default: false
    482.   --trace-mutator-utilization (print mutator utilization, allocation speed, gc speed)
    483.         type: bool  default: false
    484.   --incremental-marking (use incremental marking)
    485.         type: bool  default: true
    486.   --incremental-marking-wrappers (use incremental marking for marking wrappers)
    487.         type: bool  default: true
    488.   --incremental-marking-task (use tasks for incremental marking)
    489.         type: bool  default: true
    490.   --incremental-marking-soft-trigger (threshold for starting incremental marking via a task in percent of available space: limit - size)
    491.         type: int  default: 0
    492.   --incremental-marking-hard-trigger (threshold for starting incremental marking immediately in percent of available space: limit - size)
    493.         type: int  default: 0
    494.   --trace-unmapper (Trace the unmapping)
    495.         type: bool  default: false
    496.   --parallel-scavenge (parallel scavenge)
    497.         type: bool  default: true
    498.   --scavenge-task (schedule scavenge tasks)
    499.         type: bool  default: true
    500.   --scavenge-task-trigger (scavenge task trigger in percent of the current heap limit)
    501.         type: int  default: 80
    502.   --scavenge-separate-stack-scanning (use a separate phase for stack scanning in scavenge)
    503.         type: bool  default: false
    504.   --trace-parallel-scavenge (trace parallel scavenge)
    505.         type: bool  default: false
    506.   --write-protect-code-memory (write protect code memory)
    507.         type: bool  default: true
    508.   --concurrent-marking (use concurrent marking)
    509.         type: bool  default: true
    510.   --concurrent-array-buffer-sweeping (concurrently sweep array buffers)
    511.         type: bool  default: true
    512.   --concurrent-allocation (concurrently allocate in old space)
    513.         type: bool  default: false
    514.   --local-heaps (allow heap access from background tasks)
    515.         type: bool  default: false
    516.   --stress-concurrent-allocation (start background threads that allocate memory)
    517.         type: bool  default: false
    518.   --parallel-marking (use parallel marking in atomic pause)
    519.         type: bool  default: true
    520.   --ephemeron-fixpoint-iterations (number of fixpoint iterations it takes to switch to linear ephemeron algorithm)
    521.         type: int  default: 10
    522.   --trace-concurrent-marking (trace concurrent marking)
    523.         type: bool  default: false
    524.   --concurrent-store-buffer (use concurrent store buffer processing)
    525.         type: bool  default: true
    526.   --concurrent-sweeping (use concurrent sweeping)
    527.         type: bool  default: true
    528.   --parallel-compaction (use parallel compaction)
    529.         type: bool  default: true
    530.   --parallel-pointer-update (use parallel pointer update during compaction)
    531.         type: bool  default: true
    532.   --detect-ineffective-gcs-near-heap-limit (trigger out-of-memory failure to avoid GC storm near heap limit)
    533.         type: bool  default: true
    534.   --trace-incremental-marking (trace progress of the incremental marking)
    535.         type: bool  default: false
    536.   --trace-stress-marking (trace stress marking progress)
    537.         type: bool  default: false
    538.   --trace-stress-scavenge (trace stress scavenge progress)
    539.         type: bool  default: false
    540.   --track-gc-object-stats (track object counts and memory usage)
    541.         type: bool  default: false
    542.   --trace-gc-object-stats (trace object counts and memory usage)
    543.         type: bool  default: false
    544.   --trace-zone-stats (trace zone memory usage)
    545.         type: bool  default: false
    546.   --zone-stats-tolerance (report a tick only when allocated zone memory changes by this amount)
    547.         type: size_t  default: 1048576
    548.   --track-retaining-path (enable support for tracking retaining path)
    549.         type: bool  default: false
    550.   --concurrent-array-buffer-freeing (free array buffer allocations on a background thread)
    551.         type: bool  default: true
    552.   --gc-stats (Used by tracing internally to enable gc statistics)
    553.         type: int  default: 0
    554.   --track-detached-contexts (track native contexts that are expected to be garbage collected)
    555.         type: bool  default: true
    556.   --trace-detached-contexts (trace native contexts that are expected to be garbage collected)
    557.         type: bool  default: false
    558.   --move-object-start (enable moving of object starts)
    559.         type: bool  default: true
    560.   --memory-reducer (use memory reducer)
    561.         type: bool  default: true
    562.   --memory-reducer-for-small-heaps (use memory reducer for small heaps)
    563.         type: bool  default: true
    564.   --heap-growing-percent (specifies heap growing factor as (1 + heap_growing_percent/100))
    565.         type: int  default: 0
    566.   --v8-os-page-size (override OS page size (in KBytes))
    567.         type: int  default: 0
    568.   --always-compact (Perform compaction on every full GC)
    569.         type: bool  default: false
    570.   --never-compact (Never perform compaction on full GC - testing only)
    571.         type: bool  default: false
    572.   --compact-code-space (Compact code space on full collections)
    573.         type: bool  default: true
    574.   --flush-bytecode (flush of bytecode when it has not been executed recently)
    575.         type: bool  default: true
    576.   --stress-flush-bytecode (stress bytecode flushing)
    577.         type: bool  default: false
    578.   --use-marking-progress-bar (Use a progress bar to scan large objects in increments when incremental marking is active.)
    579.         type: bool  default: true
    580.   --stress-per-context-marking-worklist (Use per-context worklist for marking)
    581.         type: bool  default: false
    582.   --force-marking-deque-overflows (force overflows of marking deque by reducing it's size to 64 words)
    583.         type: bool  default: false
    584.   --stress-compaction (stress the GC compactor to flush out bugs (implies --force_marking_deque_overflows))
    585.         type: bool  default: false
    586.   --stress-compaction-random (Stress GC compaction by selecting random percent of pages as evacuation candidates. It overrides stress_compaction.)
    587.         type: bool  default: false
    588.   --stress-incremental-marking (force incremental marking for small heaps and run it more often)
    589.         type: bool  default: false
    590.   --fuzzer-gc-analysis (prints number of allocations and enables analysis mode for gc fuzz testing, e.g. --stress-marking, --stress-scavenge)
    591.         type: bool  default: false
    592.   --stress-marking (force marking at random points between 0 and X (inclusive) percent of the regular marking start limit)
    593.         type: int  default: 0
    594.   --stress-scavenge (force scavenge at random points between 0 and X (inclusive) percent of the new space capacity)
    595.         type: int  default: 0
    596.   --gc-experiment-background-schedule (new background GC schedule heuristics)
    597.         type: bool  default: false
    598.   --gc-experiment-less-compaction (less compaction in non-memory reducing mode)
    599.         type: bool  default: false
    600.   --disable-abortjs (disables AbortJS runtime function)
    601.         type: bool  default: false
    602.   --randomize-all-allocations (randomize virtual memory reservations by ignoring any hints passed when allocating pages)
    603.         type: bool  default: false
    604.   --manual-evacuation-candidates-selection (Test mode only flag. It allows an unit test to select evacuation candidates pages (requires --stress_compaction).)
    605.         type: bool  default: false
    606.   --fast-promotion-new-space (fast promote new space on high survival rates)
    607.         type: bool  default: false
    608.   --clear-free-memory (initialize free memory with 0)
    609.         type: bool  default: false
    610.   --young-generation-large-objects (allocates large objects by default in the young generation large object space)
    611.         type: bool  default: true
    612.   --debug-code (generate extra code (assertions) for debugging)
    613.         type: bool  default: false
    614.   --code-comments (emit comments in code disassembly; for more readable source positions you should add --no-concurrent_recompilation)
    615.         type: bool  default: false
    616.   --enable-sse3 (enable use of SSE3 instructions if available)
    617.         type: bool  default: true
    618.   --enable-ssse3 (enable use of SSSE3 instructions if available)
    619.         type: bool  default: true
    620.   --enable-sse4-1 (enable use of SSE4.1 instructions if available)
    621.         type: bool  default: true
    622.   --enable-sse4-2 (enable use of SSE4.2 instructions if available)
    623.         type: bool  default: true
    624.   --enable-sahf (enable use of SAHF instruction if available (X64 only))
    625.         type: bool  default: true
    626.   --enable-avx (enable use of AVX instructions if available)
    627.         type: bool  default: true
    628.   --enable-fma3 (enable use of FMA3 instructions if available)
    629.         type: bool  default: true
    630.   --enable-bmi1 (enable use of BMI1 instructions if available)
    631.         type: bool  default: true
    632.   --enable-bmi2 (enable use of BMI2 instructions if available)
    633.         type: bool  default: true
    634.   --enable-lzcnt (enable use of LZCNT instruction if available)
    635.         type: bool  default: true
    636.   --enable-popcnt (enable use of POPCNT instruction if available)
    637.         type: bool  default: true
    638.   --arm-arch (generate instructions for the selected ARM architecture if available: armv6, armv7, armv7+sudiv or armv8)
    639.         type: string  default: armv8
    640.   --force-long-branches (force all emitted branches to be in long mode (MIPS/PPC only))
    641.         type: bool  default: false
    642.   --mcpu (enable optimization for specific cpu)
    643.         type: string  default: auto
    644.   --partial-constant-pool (enable use of partial constant pools (X64 only))
    645.         type: bool  default: true
    646.   --sim-arm64-optional-features (enable optional features on the simulator for testing: none or all)
    647.         type: string  default: none
    648.   --enable-source-at-csa-bind (Include source information in the binary at CSA bind locations.)
    649.         type: bool  default: false
    650.   --enable-armv7 (deprecated (use --arm_arch instead))
    651.         type: maybe_bool  default: unset
    652.   --enable-vfp3 (deprecated (use --arm_arch instead))
    653.   --enable-32dregs (deprecated (use --arm_arch instead))
    655.   --enable-neon (deprecated (use --arm_arch instead))
    656.         type: maybe_bool  default: unset
    657.   --enable-sudiv (deprecated (use --arm_arch instead))
    658.         type: maybe_bool  default: unset
    659.   --enable-armv8 (deprecated (use --arm_arch instead))
    660.         type: maybe_bool  default: unset
    661.   --enable-regexp-unaligned-accesses (enable unaligned accesses for the regexp engine)
    662.         type: bool  default: true
    663.   --script-streaming (enable parsing on background)
    664.         type: bool  default: true
    665.   --stress-background-compile (stress test parsing on background)
    666.         type: bool  default: false
    667.   --finalize-streaming-on-background (perform the script streaming finalization on the background thread)
    668.         type: bool  default: false
    669.   --disable-old-api-accessors (Disable old-style API accessors whose setters trigger through the prototype chain)
    670.         type: bool  default: false
    671.   --expose-gc (expose gc extension)
    672.         type: bool  default: false
    673.   --expose-gc-as (expose gc extension under the specified name)
    674.         type: string  default: nullptr
    675.   --expose-externalize-string (expose externalize string extension)
    676.         type: bool  default: false
    677.   --expose-trigger-failure (expose trigger-failure extension)
    678.         type: bool  default: false
    679.   --stack-trace-limit (number of stack frames to capture)
    680.         type: int  default: 10
    681.   --builtins-in-stack-traces (show built-in functions in stack traces)
    682.         type: bool  default: false
    683.   --experimental-stack-trace-frames (enable experimental frames (API/Builtins) and stack trace layout)
    684.         type: bool  default: false
    685.   --disallow-code-generation-from-strings (disallow eval and friends)
    686.         type: bool  default: false
    687.   --expose-async-hooks (expose async_hooks object)
    688.         type: bool  default: false
    689.   --expose-cputracemark-as (expose cputracemark extension under the specified name)
    690.         type: string  default: nullptr
    691.   --allow-unsafe-function-constructor (allow invoking the function constructor without security checks)
    692.         type: bool  default: false
    693.   --force-slow-path (always take the slow path for builtins)
    694.         type: bool  default: false
    695.   --test-small-max-function-context-stub-size (enable testing the function context size overflow path by making the maximum size smaller)
    696.         type: bool  default: false
    697.   --inline-new (use fast inline allocation)
    698.         type: bool  default: true
    699.   --trace (trace javascript function calls)
    700.         type: bool  default: false
    701.   --trace-wasm (trace wasm function calls)
    702.         type: bool  default: false
    703.   --lazy (use lazy compilation)
    704.         type: bool  default: true
    705.   --max-lazy (ignore eager compilation hints)
    706.         type: bool  default: false
    707.   --trace-opt (trace lazy optimization)
    708.         type: bool  default: false
    709.   --trace-opt-verbose (extra verbose compilation tracing)
    710.         type: bool  default: false
    711.   --trace-opt-stats (trace lazy optimization statistics)
    712.         type: bool  default: false
    713.   --trace-deopt (trace optimize function deoptimization)
    714.         type: bool  default: false
    715.   --trace-file-names (include file names in trace-opt/trace-deopt output)
    716.         type: bool  default: false
    717.   --always-opt (always try to optimize functions)
    718.         type: bool  default: false
    719.   --always-osr (always try to OSR functions)
    720.         type: bool  default: false
    721.   --prepare-always-opt (prepare for turning on always opt)
    722.         type: bool  default: false
    723.   --trace-serializer (print code serializer trace)
    724.         type: bool  default: false
    725.   --compilation-cache (enable compilation cache)
    726.         type: bool  default: true
    727.   --cache-prototype-transitions (cache prototype transitions)
    728.         type: bool  default: true
    729.   --parallel-compile-tasks (enable parallel compile tasks)
    730.         type: bool  default: false
    731.   --compiler-dispatcher (enable compiler dispatcher)
    732.         type: bool  default: false
    733.   --trace-compiler-dispatcher (trace compiler dispatcher activity)
    734.         type: bool  default: false
    735.   --cpu-profiler-sampling-interval (CPU profiler sampling interval in microseconds)
    736.         type: int  default: 1000
    737.   --trace-side-effect-free-debug-evaluate (print debug messages for side-effect-free debug-evaluate for testing)
    738.         type: bool  default: false
    739.   --hard-abort (abort by crashing)
    740.         type: bool  default: true
    741.   --expose-inspector-scripts (expose injected-script-source.js for debugging)
    742.         type: bool  default: false
    743.   --stack-size (default size of stack region v8 is allowed to use (in kBytes))
    744.         type: int  default: 984
    745.   --max-stack-trace-source-length (maximum length of function source code printed in a stack trace.)
    746.         type: int  default: 300
    747.   --clear-exceptions-on-js-entry (clear pending exceptions when entering JavaScript)
    748.         type: bool  default: false
    749.   --histogram-interval (time interval in ms for aggregating memory histograms)
    750.         type: int  default: 600000
    751.   --heap-profiler-trace-objects (Dump heap object allocations/movements/size_updates)
    752.         type: bool  default: false
    753.   --heap-profiler-use-embedder-graph (Use the new EmbedderGraph API to get embedder nodes)
    754.         type: bool  default: true
    755.   --heap-snapshot-string-limit (truncate strings to this length in the heap snapshot)
    756.         type: int  default: 1024
    757.   --sampling-heap-profiler-suppress-randomness (Use constant sample intervals to eliminate test flakiness)
    758.         type: bool  default: false
    759.   --use-idle-notification (Use idle notification to reduce memory footprint.)
    760.         type: bool  default: true
    761.   --trace-ic (trace inline cache state transitions for tools/ic-processor)
    762.         type: bool  default: false
    763.   --modify-field-representation-inplace (enable in-place field representation updates)
    764.         type: bool  default: true
    765.   --max-polymorphic-map-count (maximum number of maps to track in POLYMORPHIC state)
    766.         type: int  default: 4
    767.   --native-code-counters (generate extra code for manipulating stats counters)
    768.         type: bool  default: false
    769.   --thin-strings (Enable ThinString support)
    770.         type: bool  default: true
    771.   --trace-prototype-users (Trace updates to prototype user tracking)
    772.         type: bool  default: false
    773.   --trace-for-in-enumerate (Trace for-in enumerate slow-paths)
    774.         type: bool  default: false
    775.   --trace-maps (trace map creation)
    776.         type: bool  default: false
    777.   --trace-maps-details (also log map details)
    778.         type: bool  default: true
    779.   --allow-natives-syntax (allow natives syntax)
    780.         type: bool  default: false
    781.   --allow-natives-for-differential-fuzzing (allow only natives explicitly allowlisted for differential fuzzers)
    782.         type: bool  default: false
    783.   --parse-only (only parse the sources)
    784.         type: bool  default: false
    785.   --trace-sim (Trace simulator execution)
    786.         type: bool  default: false
    787.   --debug-sim (Enable debugging the simulator)
    788.         type: bool  default: false
    789.   --check-icache (Check icache flushes in ARM and MIPS simulator)
    790.         type: bool  default: false
    791.   --stop-sim-at (Simulator stop after x number of instructions)
    792.         type: int  default: 0
    793.   --sim-stack-alignment (Stack alingment in bytes in simulator (4 or 8, 8 is default))
    794.         type: int  default: 8
    795.   --sim-stack-size (Stack size of the ARM64, MIPS64 and PPC64 simulator in kBytes (default is 2 MB))
    796.         type: int  default: 2048
    797.   --log-colour (When logging, try to use coloured output.)
    798.         type: bool  default: true
    799.   --trace-sim-messages (Trace simulator debug messages. Implied by --trace-sim.)
    800.         type: bool  default: false
    801.   --async-stack-traces (include async stack traces in Error.stack)
    802.         type: bool  default: true
    803.   --stack-trace-on-illegal (print stack trace when an illegal exception is thrown)
    804.         type: bool  default: false
    805.   --abort-on-uncaught-exception (abort program (dump core) when an uncaught exception is thrown)
    806.         type: bool  default: false
    807.   --correctness-fuzzer-suppressions (Suppress certain unspecified behaviors to ease correctness fuzzing: Abort program when the stack overflows or a string exceeds maximum length (as opposed to throwing RangeError). Use a fixed suppression string for error messages.)
    808.         type: bool  default: false
    809.   --randomize-hashes (randomize hashes to avoid predictable hash collisions (with snapshots this option cannot override the baked-in seed))
    810.         type: bool  default: true
    811.   --rehash-snapshot (rehash strings from the snapshot to override the baked-in seed)
    812.         type: bool  default: true
    813.   --hash-seed (Fixed seed to use to hash property keys (0 means random)(with snapshots this option cannot override the baked-in seed))
    814.         type: uint64  default: 0
    815.   --random-seed (Default seed for initializing random generator (0, the default, means to use system random).)
    816.         type: int  default: 0
    817.   --fuzzer-random-seed (Default seed for initializing fuzzer random generator (0, the default, means to use v8's random number generator seed).)
    818.         type: int  default: 0
    819.   --trace-rail (trace RAIL mode)
    820.         type: bool  default: false
    821.   --print-all-exceptions (print exception object and stack trace on each thrown exception)
    822.         type: bool  default: false
    823.   --detailed-error-stack-trace (includes arguments for each function call in the error stack frames array)
    824.         type: bool  default: false
    825.   --adjust-os-scheduling-parameters (adjust OS specific scheduling params for the isolate)
    826.         type: bool  default: true
    827.   --runtime-call-stats (report runtime call counts and times)
    828.         type: bool  default: false
    829.   --rcs (report runtime call counts and times)
    830.         type: bool  default: false
    831.   --rcs-cpu-time (report runtime times in cpu time (the default is wall time))
    832.         type: bool  default: false
    833.   --profile-deserialization (Print the time it takes to deserialize the snapshot.)
    834.         type: bool  default: false
    835.   --serialization-statistics (Collect statistics on serialized objects.)
    836.         type: bool  default: false
    837.   --serialization-chunk-size (Custom size for serialization chunks)
    838.         type: uint  default: 4096
    839.   --regexp-optimization (generate optimized regexp code)
    840.         type: bool  default: true
    841.   --regexp-mode-modifiers (enable inline flags in regexp.)
    842.         type: bool  default: false
    843.   --regexp-interpret-all (interpret all regexp code)
    844.         type: bool  default: false
    845.   --regexp-tier-up (enable regexp interpreter and tier up to the compiler after the number of executions set by the tier up ticks flag)
    846.         type: bool  default: true
    847.   --regexp-tier-up-ticks (set the number of executions for the regexp interpreter before tiering-up to the compiler)
    848.         type: int  default: 1
    849.   --regexp-peephole-optimization (enable peephole optimization for regexp bytecode)
    850.         type: bool  default: true
    851.   --trace-regexp-peephole-optimization (trace regexp bytecode peephole optimization)
    852.         type: bool  default: false
    853.   --trace-regexp-bytecodes (trace regexp bytecode execution)
    854.         type: bool  default: false
    855.   --trace-regexp-assembler (trace regexp macro assembler calls.)
    856.         type: bool  default: false
    857.   --trace-regexp-parser (trace regexp parsing)
    858.         type: bool  default: false
    859.   --trace-regexp-tier-up (trace regexp tiering up execution)
    860.         type: bool  default: false
    861.   --testing-bool-flag (testing_bool_flag)
    862.         type: bool  default: true
    863.   --testing-maybe-bool-flag (testing_maybe_bool_flag)
    864.         type: maybe_bool  default: unset
    865.   --testing-int-flag (testing_int_flag)
    866.         type: int  default: 13
    867.   --testing-float-flag (float-flag)
    868.         type: float  default: 2.5
    869.   --testing-string-flag (string-flag)
    870.         type: string  default: Hello, world!
    871.   --testing-prng-seed (Seed used for threading test randomness)
    872.         type: int  default: 42
    873.   --testing-d8-test-runner (test runner turns on this flag to enable a check that the function was prepared for optimization before marking it for optimization)
    874.         type: bool  default: false
    875.   --fuzzing (Fuzzers use this flag to signal that they are ... fuzzing. This causes intrinsics to fail silently (e.g. return undefined) on invalid usage.)
    876.         type: bool  default: false
    877.   --embedded-src (Path for the generated embedded data file. (mksnapshot only))
    878.         type: string  default: nullptr
    879.   --embedded-variant (Label to disambiguate symbols in embedded data file. (mksnapshot only))
    880.         type: string  default: nullptr
    881.   --startup-src (Write V8 startup as C++ src. (mksnapshot only))
    882.         type: string  default: nullptr
    883.   --startup-blob (Write V8 startup blob file. (mksnapshot only))
    884.         type: string  default: nullptr
    885.   --target-arch (The mksnapshot target arch. (mksnapshot only))
    886.         type: string  default: nullptr
    887.   --target-os (The mksnapshot target os. (mksnapshot only))
    888.         type: string  default: nullptr
    889.   --target-is-simulator (Instruct mksnapshot that the target is meant to run in the simulator and it can generate simulator-specific instructions. (mksnapshot only))
    890.         type: bool  default: false
    891.   --minor-mc-parallel-marking (use parallel marking for the young generation)
    892.         type: bool  default: true
    893.   --trace-minor-mc-parallel-marking (trace parallel marking for the young generation)
    894.         type: bool  default: false
    895.   --minor-mc (perform young generation mark compact GCs)
    896.         type: bool  default: false
    897.   --help (Print usage message, including flags, on console)
    898.         type: bool  default: true
    899.   --dump-counters (Dump counters on exit)
    900.         type: bool  default: false
    901.   --dump-counters-nvp (Dump counters as name-value pairs on exit)
    902.         type: bool  default: false
    903.   --use-external-strings (Use external strings for source code)
    904.         type: bool  default: false
    905.   --map-counters (Map counters to a file)
    906.         type: string  default:
    907.   --mock-arraybuffer-allocator (Use a mock ArrayBuffer allocator for testing.)
    908.         type: bool  default: false
    909.   --mock-arraybuffer-allocator-limit (Memory limit for mock ArrayBuffer allocator used to simulate OOM for testing.)
    910.         type: size_t  default: 0
    911.   --gdbjit (enable GDBJIT interface)
    912.         type: bool  default: false
    913.   --gdbjit-full (enable GDBJIT interface for all code objects)
    914.         type: bool  default: false
    915.   --gdbjit-dump (dump elf objects with debug info to disk)
    916.         type: bool  default: false
    917.   --gdbjit-dump-filter (dump only objects containing this substring)
    918.         type: string  default:
    919.   --log (Minimal logging (no API, code, GC, suspect, or handles samples).)
    920.         type: bool  default: false
    921.   --log-all (Log all events to the log file.)
    922.         type: bool  default: false
    923.   --log-api (Log API events to the log file.)
    924.         type: bool  default: false
    925.   --log-code (Log code events to the log file without profiling.)
    926.         type: bool  default: false
    927.   --log-handles (Log global handle events.)
    928.         type: bool  default: false
    929.   --log-suspect (Log suspect operations.)
    930.         type: bool  default: false
    931.   --log-source-code (Log source code.)
    932.         type: bool  default: false
    933.   --log-function-events (Log function events (parse, compile, execute) separately.)
    934.         type: bool  default: false
    935.   --prof (Log statistical profiling information (implies --log-code).)
    936.         type: bool  default: false
    937.   --detailed-line-info (Always generate detailed line information for CPU profiling.)
    938.         type: bool  default: false
    939.   --prof-sampling-interval (Interval for --prof samples (in microseconds).)
    940.         type: int  default: 1000
    941.   --prof-cpp (Like --prof, but ignore generated code.)
    942.         type: bool  default: false
    943.   --prof-browser-mode (Used with --prof, turns on browser-compatible mode for profiling.)
    944.         type: bool  default: true
    945.   --logfile (Specify the name of the log file.)
    946.         type: string  default: v8.log
    947.   --logfile-per-isolate (Separate log files for each isolate.)
    948.         type: bool  default: true
    949.   --ll-prof (Enable low-level linux profiler.)
    950.         type: bool  default: false
    951.   --gc-fake-mmap (Specify the name of the file for fake gc mmap used in ll_prof)
    952.         type: string  default: /tmp/__v8_gc__
    953.   --log-internal-timer-events (Time internal events.)
    954.         type: bool  default: false
    955.   --redirect-code-traces (output deopt information and disassembly into file code-<pid>-<isolate id>.asm)
    956.         type: bool  default: false
    957.   --redirect-code-traces-to (output deopt information and disassembly into the given file)
    958.         type: string  default: nullptr
    959.   --print-opt-source (print source code of optimized and inlined functions)
    960.         type: bool  default: false
    961.   --vtune-prof-annotate-wasm (Used when v8_enable_vtunejit is enabled, load wasm source map and provide annotate support (experimental).)
    962.         type: bool  default: false
    963.   --win64-unwinding-info (Enable unwinding info for Windows/x64)
    964.         type: bool  default: true
    965.   --interpreted-frames-native-stack (Show interpreted frames on the native stack (useful for external profilers).)
    966.         type: bool  default: false
    967.   --predictable (enable predictable mode)
    968.         type: bool  default: false
    969.   --predictable-gc-schedule (Predictable garbage collection schedule. Fixes heap growing, idle, and memory reducing behavior.)
    970.         type: bool  default: false
    971.   --single-threaded (disable the use of background tasks)
    972.         type: bool  default: false
    973.   --single-threaded-gc (disable the use of background gc tasks)
    974.         type: bool  default: false

    Particularly useful ones:

    Continuous Benchmarks

    See our benchmarks over here

    1. interface ExecTimeData {
    2.   mean: number;
    3.   stddev: number;
    4.   user: number;
    5.   system: number;
    6.   min: number;
    7.   max: number;
    8. }
    10. interface BenchmarkData {
    11.   created_at: string;
    12.   sha1: string;
    13.   benchmark: {
    14.     [key: string]: ExecTimeData;
    15.   };
    16.   binarySizeData: {
    17.     [key: string]: number;
    18.   };
    19.   threadCountData: {
    20.     [key: string]: number;
    21.   };
    22.   syscallCountData: {
    23.     [key: string]: number;
    25. }