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Diffstat (limited to 'docs/contributing/development_tools.md')
| -rw-r--r-- | docs/contributing/development_tools.md | 994 |
1 files changed, 977 insertions, 17 deletions
diff --git a/docs/contributing/development_tools.md b/docs/contributing/development_tools.md index 523293bc7..c05a1ee98 100644 --- a/docs/contributing/development_tools.md +++ b/docs/contributing/development_tools.md @@ -86,19 +86,8 @@ To learn more about `d8` and profiling, check out the following links: ### Debugging with LLDB -We can use LLDB to debug Deno. - -```shell -$ lldb -- target/debug/deno run tests/worker.js -> run -> bt -> up -> up -> l -``` - -To debug Rust code, we can use `rust-lldb`. It should come with `rustc` and is a -wrapper around LLDB. +To debug the deno binary, we can use `rust-lldb`. It should come with `rustc` +and is a wrapper around LLDB. ```shell $ rust-lldb -- ./target/debug/deno run --allow-net tests/http_bench.ts @@ -121,11 +110,982 @@ Current executable set to '../deno/target/debug/deno' (x86_64). V8 has many many internal command-line flags. ```shell -# list available v8 flags -$ deno --v8-flags=--help +$ deno run --v8-flags=--help _ +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 +Synopsis: + shell [options] [--shell] [<file>...] + d8 [options] [-e <string>] [--shell] [[--module] <file>...] + + -e execute a string in V8 + --shell run an interactive JavaScript shell + --module execute a file as a JavaScript module + +Note: the --module option is implicitly enabled for *.mjs files. + +The following syntax for options is accepted (both '-' and '--' are ok): + --flag (bool flags only) + --no-flag (bool flags only) + --flag=value (non-bool flags only, no spaces around '=') + --flag value (non-bool flags only) + -- (captures all remaining args in JavaScript) -# example for applying multiple flags -$ deno --v8-flags=--expose-gc,--use-strict +Options: + --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 + --harmony-regexp-sequence (enable "RegExp Unicode sequence properties" (in progress)) + type: bool default: false + --harmony-weak-refs-with-cleanup-some (enable "harmony weak references with FinalizationRegistry.prototype.cleanupSome" (in progress)) + type: bool default: false + --harmony-regexp-match-indices (enable "harmony regexp match indices" (in progress)) + type: bool default: false + --harmony-top-level-await (enable "harmony top level await") + type: bool default: false + --harmony-namespace-exports (enable "harmony namespace exports (export * as foo from 'bar')") + type: bool default: true + --harmony-sharedarraybuffer (enable "harmony sharedarraybuffer") + type: bool default: true + --harmony-import-meta (enable "harmony import.meta property") + type: bool default: true + --harmony-dynamic-import (enable "harmony dynamic import") + type: bool default: true + --harmony-promise-all-settled (enable "harmony Promise.allSettled") + type: bool default: true + --harmony-promise-any (enable "harmony Promise.any") + type: bool default: true + --harmony-private-methods (enable "harmony private methods in class literals") + type: bool default: true + --harmony-weak-refs (enable "harmony weak references") + type: bool default: true + --harmony-string-replaceall (enable "harmony String.prototype.replaceAll") + type: bool default: true + --harmony-logical-assignment (enable "harmony logical assignment") + type: bool default: true + --lite-mode (enables trade-off of performance for memory savings) + type: bool default: false + --future (Implies all staged features that we want to ship in the not-too-far future) + type: bool default: false + --assert-types (generate runtime type assertions to test the typer) + 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 + --always-promote-young-mc (always promote young objects during mark-compact) + 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 + --trace-block-coverage (trace collected block coverage information) + type: bool default: false + --trace-protector-invalidation (trace protector cell invalidations) + type: bool default: false + --feedback-normalization (feed back normalization to constructors) + type: bool default: false + --enable-one-shot-optimization (Enable size optimizations for the code that will only be executed once) + type: bool default: false + --unbox-double-arrays (automatically unbox arrays of doubles) + type: bool default: true + --interrupt-budget (interrupt budget which should be used for the profiler counter) + type: int default: 147456 + --jitless (Disable runtime allocation of executable memory.) + type: bool default: false + --use-ic (use inline caching) + type: bool default: true + --budget-for-feedback-vector-allocation (The budget in amount of bytecode executed by a function before we decide to allocate feedback vectors) + type: int default: 1024 + --lazy-feedback-allocation (Allocate feedback vectors lazily) + type: bool default: true + --ignition-elide-noneffectful-bytecodes (elide bytecodes which won't have any external effect) + 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-share-named-property-feedback (share feedback slots when loading the same named property from the same object) + type: bool default: true + --print-bytecode (print bytecode generated by ignition interpreter) + type: bool default: false + --enable-lazy-source-positions (skip generating source positions during initial compile but regenerate when actually required) + type: bool default: true + --stress-lazy-source-positions (collect lazy source positions immediately after lazy compile) + type: bool default: false + --print-bytecode-filter (filter for selecting which functions to print bytecode) + type: string default: * + --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: nullptr + --fast-math (faster (but maybe less accurate) math functions) + type: bool default: true + --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 + --turboprop (enable experimental turboprop mid-tier compiler.) + type: bool default: false + --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 + --concurrent-inlining (run optimizing compiler's inlining phase on a separate thread) + type: bool default: false + --max-serializer-nesting (maximum levels for nesting child serializers) + type: int default: 25 + --trace-heap-broker-verbose (trace the heap broker verbosely (all reports)) + type: bool default: false + --trace-heap-broker-memory (trace the heap broker memory (refs analysis and zone numbers)) + type: bool default: false + --trace-heap-broker (trace the heap broker (reports on missing data only)) + type: bool default: false + --stress-runs (number of stress runs) + type: int default: 0 + --deopt-every-n-times (deoptimize every n times a deopt point is passed) + type: int default: 0 + --print-deopt-stress (print number of possible deopt points) + type: bool default: false + --opt (use adaptive optimizations) + type: bool default: true + --turbo-sp-frame-access (use stack pointer-relative access to frame wherever possible) + type: bool default: false + --turbo-control-flow-aware-allocation (consider control flow while allocating registers) + 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-path (directory to dump generated TurboFan IR to) + type: string default: nullptr + --trace-turbo-filter (filter for tracing turbofan compilation) + type: string default: * + --trace-turbo-graph (trace generated TurboFan graphs) + type: bool default: false + --trace-turbo-scheduled (trace TurboFan IR with schedule) + type: bool default: false + --trace-turbo-cfg-file (trace turbo cfg graph (for C1 visualizer) to a given file name) + type: string default: nullptr + --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 + --trace-turbo-alloc (trace TurboFan's register allocator) + type: bool default: false + --trace-all-uses (trace all use positions) + type: bool default: false + --trace-representation (trace representation types) + type: bool default: false + --turbo-verify (verify TurboFan graphs at each phase) + type: bool default: false + --turbo-verify-machine-graph (verify TurboFan machine graph before instruction selection) + type: string default: nullptr + --trace-verify-csa (trace code stubs verification) + type: bool default: false + --csa-trap-on-node (trigger break point when a node with given id is created in given stub. The format is: StubName,NodeId) + type: string default: nullptr + --turbo-stats (print TurboFan statistics) + type: bool default: false + --turbo-stats-nvp (print TurboFan statistics in machine-readable format) + type: bool default: false + --turbo-stats-wasm (print TurboFan statistics of wasm compilations) + type: bool default: false + --turbo-splitting (split nodes during scheduling in TurboFan) + type: bool default: true + --function-context-specialization (enable function context specialization in TurboFan) + type: bool default: false + --turbo-inlining (enable inlining in TurboFan) + type: bool default: true + --max-inlined-bytecode-size (maximum size of bytecode for a single inlining) + type: int default: 500 + --max-inlined-bytecode-size-cumulative (maximum cumulative size of bytecode considered for inlining) + type: int default: 1000 + --max-inlined-bytecode-size-absolute (maximum cumulative size of bytecode considered for inlining) + type: int default: 5000 + --reserve-inline-budget-scale-factor (maximum cumulative size of bytecode considered for inlining) + type: float default: 1.2 + --max-inlined-bytecode-size-small (maximum size of bytecode considered for small function inlining) + type: int default: 30 + --max-optimized-bytecode-size (maximum bytecode size to be considered for optimization; too high values may cause the compiler to hit (release) assertions) + type: int default: 61440 + --min-inlining-frequency (minimum frequency for inlining) + type: float default: 0.15 + --polymorphic-inlining (polymorphic inlining) + type: bool default: true + --stress-inline (set high thresholds for inlining to inline as much as possible) + type: bool default: false + --trace-turbo-inlining (trace TurboFan inlining) + type: bool default: false + --turbo-inline-array-builtins (inline array builtins in TurboFan code) + type: bool default: true + --use-osr (use on-stack replacement) + type: bool default: true + --trace-osr (trace on-stack replacement) + type: bool default: false + --analyze-environment-liveness (analyze liveness of environment slots and zap dead values) + type: bool default: true + --trace-environment-liveness (trace liveness of local variable slots) + 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 + --turbo-profiling (enable basic block profiling in TurboFan) + type: bool default: false + --turbo-profiling-verbose (enable basic block profiling in TurboFan, and include each function's schedule and disassembly in the output) + 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-loop-peeling (Turbofan loop peeling) + type: bool default: true + --turbo-loop-variable (Turbofan loop variable optimization) + type: bool default: true + --turbo-loop-rotation (Turbofan loop rotation) + type: bool default: true + --turbo-cf-optimization (optimize control flow in TurboFan) + type: bool default: true + --turbo-escape (enable escape analysis) + type: bool default: true + --turbo-allocation-folding (Turbofan allocation folding) + type: bool default: true + --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: true + --trace-store-elimination (trace store elimination) + type: bool default: false + --turbo-rewrite-far-jumps (rewrite far to near jumps (ia32,x64)) + type: bool default: true + --stress-gc-during-compilation (simulate GC/compiler thread race related to https://crbug.com/v8/8520) + type: bool default: false + --turbo-fast-api-calls (enable fast API calls from TurboFan) + type: bool default: false + --reuse-opt-code-count (don't discard optimized code for the specified number of deopts.) + type: int default: 0 + --turbo-nci (enable experimental native context independent code.) + type: bool default: false + --turbo-nci-as-highest-tier (replace default TF with NCI code as the highest tier for testing purposes.) + type: bool default: false + --print-nci-code (print native context independent code.) + type: bool default: false + --trace-turbo-nci (trace native context independent code.) + type: bool default: false + --turbo-collect-feedback-in-generic-lowering (enable experimental feedback collection in generic lowering.) + type: bool default: false + --optimize-for-size (Enables optimizations which favor memory size over execution speed) + type: bool default: false + --untrusted-code-mitigations (Enable mitigations for executing untrusted code) + type: bool default: false + --expose-wasm (expose wasm interface to JavaScript) + type: bool default: true + --assume-asmjs-origin (force wasm decoder to assume input is internal asm-wasm format) + type: bool default: false + --wasm-num-compilation-tasks (maximum number of parallel compilation tasks for wasm) + type: int default: 128 + --wasm-write-protect-code-memory (write protect code memory on the wasm native heap) + type: bool default: false + --wasm-async-compilation (enable actual asynchronous compilation for WebAssembly.compile) + type: bool default: true + --wasm-test-streaming (use streaming compilation instead of async compilation for tests) + type: bool default: false + --wasm-max-mem-pages (maximum initial number of 64KiB memory pages of a wasm instance) + type: uint default: 32767 + --wasm-max-mem-pages-growth (maximum number of 64KiB pages a Wasm memory can grow to) + type: uint default: 65536 + --wasm-max-table-size (maximum table size of a wasm instance) + type: uint default: 10000000 + --wasm-max-code-space (maximum committed code space for wasm (in MB)) + type: uint default: 1024 + --wasm-tier-up (enable tier up to the optimizing compiler (requires --liftoff to have an effect)) + type: bool default: true + --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 + --liftoff (enable Liftoff, the baseline compiler for WebAssembly) + type: bool default: true + --trace-wasm-memory (print all memory updates performed in wasm code) + type: bool default: false + --wasm-tier-mask-for-testing (bitmask of functions to compile with TurboFan instead of Liftoff) + type: int default: 0 + --wasm-expose-debug-eval (Expose wasm evaluator support on the CDP) + type: bool default: false + --validate-asm (validate asm.js modules before compiling) + type: bool default: true + --suppress-asm-messages (don't emit asm.js related messages (for golden file testing)) + type: bool default: false + --trace-asm-time (log asm.js timing info to the console) + type: bool default: false + --trace-asm-scanner (log tokens encountered by asm.js scanner) + type: bool default: false + --trace-asm-parser (verbose logging of asm.js parse failures) + type: bool default: false + --stress-validate-asm (try to validate everything as asm.js) + type: bool default: false + --dump-wasm-module-path (directory to dump wasm modules to) + type: string default: nullptr + --experimental-wasm-eh (enable prototype exception handling opcodes for wasm) + type: bool default: false + --experimental-wasm-simd (enable prototype SIMD opcodes for wasm) + type: bool default: false + --experimental-wasm-return-call (enable prototype return call opcodes for wasm) + type: bool default: false + --experimental-wasm-compilation-hints (enable prototype compilation hints section for wasm) + type: bool default: false + --experimental-wasm-gc (enable prototype garbage collection for wasm) + type: bool default: false + --experimental-wasm-typed-funcref (enable prototype typed function references for wasm) + type: bool default: false + --experimental-wasm-reftypes (enable prototype reference type opcodes for wasm) + type: bool default: false + --experimental-wasm-threads (enable prototype thread opcodes for wasm) + type: bool default: false + --experimental-wasm-type-reflection (enable prototype wasm type reflection in JS for wasm) + type: bool default: false + --experimental-wasm-bigint (enable prototype JS BigInt support for wasm) + type: bool default: true + --experimental-wasm-bulk-memory (enable prototype bulk memory opcodes for wasm) + type: bool default: true + --experimental-wasm-mv (enable prototype multi-value support for wasm) + type: bool default: true + --wasm-staging (enable staged wasm features) + type: bool default: false + --wasm-opt (enable wasm optimization) + type: bool default: false + --wasm-bounds-checks (enable bounds checks (disable for performance testing only)) + type: bool default: true + --wasm-stack-checks (enable stack checks (disable for performance testing only)) + type: bool default: true + --wasm-math-intrinsics (intrinsify some Math imports into wasm) + type: bool default: true + --wasm-trap-handler (use signal handlers to catch out of bounds memory access in wasm (currently Linux x86_64 only)) + type: bool default: true + --wasm-fuzzer-gen-test (generate a test case when running a wasm fuzzer) + type: bool default: false + --print-wasm-code (Print WebAssembly code) + type: bool default: false + --print-wasm-stub-code (Print WebAssembly stub code) + type: bool default: false + --asm-wasm-lazy-compilation (enable lazy compilation for asm-wasm modules) + type: bool default: false + --wasm-lazy-compilation (enable lazy compilation for all wasm modules) + type: bool default: false + --wasm-lazy-validation (enable lazy validation for lazily compiled wasm functions) + type: bool default: false + --wasm-atomics-on-non-shared-memory (allow atomic operations on non-shared WebAssembly memory) + type: bool default: true + --wasm-grow-shared-memory (allow growing shared WebAssembly memory objects) + type: bool default: true + --wasm-simd-post-mvp (allow experimental SIMD operations for prototyping that are not included in the current proposal) + type: bool default: false + --wasm-code-gc (enable garbage collection of wasm code) + type: bool default: true + --trace-wasm-code-gc (trace garbage collection of wasm code) + type: bool default: false + --stress-wasm-code-gc (stress test garbage collection of wasm code) + type: bool default: false + --wasm-max-initial-code-space-reservation (maximum size of the initial wasm code space reservation (in MB)) + type: int default: 0 + --frame-count (number of stack frames inspected by the profiler) + type: int default: 1 + --stress-sampling-allocation-profiler (Enables sampling allocation profiler with X as a sample interval) + type: int default: 0 + --lazy-new-space-shrinking (Enables the lazy new space shrinking strategy) + type: bool default: false + --min-semi-space-size (min size of a semi-space (in MBytes), the new space consists of two semi-spaces) + type: size_t default: 0 + --max-semi-space-size (max size of a semi-space (in MBytes), the new space consists of two semi-spaces) + type: size_t default: 0 + --semi-space-growth-factor (factor by which to grow the new space) + type: int default: 2 + --max-old-space-size (max size of the old space (in Mbytes)) + type: size_t default: 0 + --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.) + type: size_t default: 0 + --initial-heap-size (initial size of the heap (in Mbytes)) + type: size_t default: 0 + --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) + type: bool default: true + --initial-old-space-size (initial old space size (in Mbytes)) + type: size_t default: 0 + --global-gc-scheduling (enable GC scheduling based on global memory) + type: bool default: true + --gc-global (always perform global GCs) + type: bool default: false + --random-gc-interval (Collect garbage after random(0, X) allocations. It overrides gc_interval.) + type: int default: 0 + --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 + --trace-gc-verbose (print more details following each garbage collection) + type: bool default: false + --trace-gc-freelists (prints details of each freelist before and after each major garbage collection) + type: bool default: false + --trace-gc-freelists-verbose (prints details of freelists of each page before and after each major garbage collection) + type: bool default: false + --trace-evacuation-candidates (Show statistics about the pages evacuation by the compaction) + type: bool default: false + --trace-allocations-origins (Show statistics about the origins of allocations. Combine with --no-inline-new to track allocations from generated code) + type: bool default: false + --trace-allocation-stack-interval (print stack trace after <n> free-list allocations) + type: int default: -1 + --trace-duplicate-threshold-kb (print duplicate objects in the heap if their size is more than given threshold) + type: int default: 0 + --trace-fragmentation (report fragmentation for old space) + type: bool default: false + --trace-fragmentation-verbose (report fragmentation for old space (detailed)) + type: bool default: false + --minor-mc-trace-fragmentation (trace fragmentation after marking) + 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 + --incremental-marking (use incremental marking) + type: bool default: true + --incremental-marking-wrappers (use incremental marking for marking wrappers) + type: bool default: true + --incremental-marking-task (use tasks for incremental marking) + type: bool default: true + --incremental-marking-soft-trigger (threshold for starting incremental marking via a task in percent of available space: limit - size) + type: int default: 0 + --incremental-marking-hard-trigger (threshold for starting incremental marking immediately in percent of available space: limit - size) + type: int default: 0 + --trace-unmapper (Trace the unmapping) + type: bool default: false + --parallel-scavenge (parallel scavenge) + type: bool default: true + --scavenge-task (schedule scavenge tasks) + type: bool default: true + --scavenge-task-trigger (scavenge task trigger in percent of the current heap limit) + type: int default: 80 + --scavenge-separate-stack-scanning (use a separate phase for stack scanning in scavenge) + type: bool default: false + --trace-parallel-scavenge (trace parallel scavenge) + type: bool default: false + --write-protect-code-memory (write protect code memory) + type: bool default: true + --concurrent-marking (use concurrent marking) + type: bool default: true + --concurrent-array-buffer-sweeping (concurrently sweep array buffers) + type: bool default: true + --concurrent-allocation (concurrently allocate in old space) + type: bool default: false + --local-heaps (allow heap access from background tasks) + type: bool default: false + --stress-concurrent-allocation (start background threads that allocate memory) + type: bool default: false + --parallel-marking (use parallel marking in atomic pause) + type: bool default: true + --ephemeron-fixpoint-iterations (number of fixpoint iterations it takes to switch to linear ephemeron algorithm) + type: int default: 10 + --trace-concurrent-marking (trace concurrent marking) + type: bool default: false + --concurrent-store-buffer (use concurrent store buffer processing) + type: bool default: true + --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 + --detect-ineffective-gcs-near-heap-limit (trigger out-of-memory failure to avoid GC storm near heap limit) + type: bool default: true + --trace-incremental-marking (trace progress of the incremental marking) + type: bool default: false + --trace-stress-marking (trace stress marking progress) + type: bool default: false + --trace-stress-scavenge (trace stress scavenge progress) + 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 + --trace-zone-stats (trace zone memory usage) + type: bool default: false + --zone-stats-tolerance (report a tick only when allocated zone memory changes by this amount) + type: size_t default: 1048576 + --track-retaining-path (enable support for tracking retaining path) + type: bool default: false + --concurrent-array-buffer-freeing (free array buffer allocations on a background thread) + type: bool default: true + --gc-stats (Used by tracing internally to enable gc statistics) + type: int default: 0 + --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 + --memory-reducer-for-small-heaps (use memory reducer for small heaps) + type: bool default: true + --heap-growing-percent (specifies heap growing factor as (1 + heap_growing_percent/100)) + type: int default: 0 + --v8-os-page-size (override OS page size (in KBytes)) + type: int default: 0 + --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 + --flush-bytecode (flush of bytecode when it has not been executed recently) + type: bool default: true + --stress-flush-bytecode (stress bytecode flushing) + type: bool default: false + --use-marking-progress-bar (Use a progress bar to scan large objects in increments when incremental marking is active.) + type: bool default: true + --stress-per-context-marking-worklist (Use per-context worklist for marking) + 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 + --stress-compaction-random (Stress GC compaction by selecting random percent of pages as evacuation candidates. It overrides stress_compaction.) + type: bool default: false + --stress-incremental-marking (force incremental marking for small heaps and run it more often) + type: bool default: false + --fuzzer-gc-analysis (prints number of allocations and enables analysis mode for gc fuzz testing, e.g. --stress-marking, --stress-scavenge) + type: bool default: false + --stress-marking (force marking at random points between 0 and X (inclusive) percent of the regular marking start limit) + type: int default: 0 + --stress-scavenge (force scavenge at random points between 0 and X (inclusive) percent of the new space capacity) + type: int default: 0 + --gc-experiment-background-schedule (new background GC schedule heuristics) + type: bool default: false + --gc-experiment-less-compaction (less compaction in non-memory reducing mode) + type: bool default: false + --disable-abortjs (disables AbortJS runtime function) + type: bool default: false + --randomize-all-allocations (randomize virtual memory reservations by ignoring any hints passed when allocating pages) + 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 + --fast-promotion-new-space (fast promote new space on high survival rates) + type: bool default: false + --clear-free-memory (initialize free memory with 0) + type: bool default: false + --young-generation-large-objects (allocates large objects by default in the young generation large object space) + type: bool default: true + --debug-code (generate extra code (assertions) for debugging) + type: bool default: false + --code-comments (emit comments in code disassembly; for more readable source positions you should add --no-concurrent_recompilation) + type: bool default: false + --enable-sse3 (enable use of SSE3 instructions if available) + type: bool default: true + --enable-ssse3 (enable use of SSSE3 instructions if available) + type: bool default: true + --enable-sse4-1 (enable use of SSE4.1 instructions if available) + type: bool default: true + --enable-sse4-2 (enable use of SSE4.2 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 + --arm-arch (generate instructions for the selected ARM architecture if available: armv6, armv7, armv7+sudiv or armv8) + type: string default: armv8 + --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 + --partial-constant-pool (enable use of partial constant pools (X64 only)) + type: bool default: true + --sim-arm64-optional-features (enable optional features on the simulator for testing: none or all) + type: string default: none + --enable-source-at-csa-bind (Include source information in the binary at CSA bind locations.) + type: bool default: false + --enable-armv7 (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-vfp3 (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-32dregs (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-neon (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-sudiv (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-armv8 (deprecated (use --arm_arch instead)) + type: maybe_bool default: unset + --enable-regexp-unaligned-accesses (enable unaligned accesses for the regexp engine) + type: bool default: true + --script-streaming (enable parsing on background) + type: bool default: true + --stress-background-compile (stress test parsing on background) + type: bool default: false + --finalize-streaming-on-background (perform the script streaming finalization on the background thread) + type: bool default: false + --disable-old-api-accessors (Disable old-style API accessors whose setters trigger through the prototype chain) + 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: nullptr + --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 + --experimental-stack-trace-frames (enable experimental frames (API/Builtins) and stack trace layout) + type: bool default: false + --disallow-code-generation-from-strings (disallow eval and friends) + type: bool default: false + --expose-async-hooks (expose async_hooks object) + type: bool default: false + --expose-cputracemark-as (expose cputracemark extension under the specified name) + type: string default: nullptr + --allow-unsafe-function-constructor (allow invoking the function constructor without security checks) + type: bool default: false + --force-slow-path (always take the slow path for builtins) + type: bool default: false + --test-small-max-function-context-stub-size (enable testing the function context size overflow path by making the maximum size smaller) + type: bool default: false + --inline-new (use fast inline allocation) + type: bool default: true + --trace (trace javascript function calls) + type: bool default: false + --trace-wasm (trace wasm function calls) + type: bool default: false + --lazy (use lazy compilation) + type: bool default: true + --max-lazy (ignore eager compilation hints) + type: bool default: false + --trace-opt (trace lazy optimization) + type: bool default: false + --trace-opt-verbose (extra verbose compilation tracing) + type: bool default: false + --trace-opt-stats (trace lazy optimization statistics) + type: bool default: false + --trace-deopt (trace optimize function deoptimization) + type: bool default: false + --trace-file-names (include file names in trace-opt/trace-deopt output) + type: bool default: false + --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-serializer (print code serializer trace) + type: bool default: false + --compilation-cache (enable compilation cache) + type: bool default: true + --cache-prototype-transitions (cache prototype transitions) + type: bool default: true + --parallel-compile-tasks (enable parallel compile tasks) + type: bool default: false + --compiler-dispatcher (enable compiler dispatcher) + type: bool default: false + --trace-compiler-dispatcher (trace compiler dispatcher activity) + type: bool default: false + --cpu-profiler-sampling-interval (CPU profiler sampling interval in microseconds) + type: int default: 1000 + --trace-side-effect-free-debug-evaluate (print debug messages for side-effect-free debug-evaluate for testing) + type: bool default: false + --hard-abort (abort by crashing) + type: bool default: true + --expose-inspector-scripts (expose injected-script-source.js for debugging) + type: bool default: false + --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 + --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 + --heap-profiler-trace-objects (Dump heap object allocations/movements/size_updates) + type: bool default: false + --heap-profiler-use-embedder-graph (Use the new EmbedderGraph API to get embedder nodes) + type: bool default: true + --heap-snapshot-string-limit (truncate strings to this length in the heap snapshot) + type: int default: 1024 + --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 + --trace-ic (trace inline cache state transitions for tools/ic-processor) + type: bool default: false + --modify-field-representation-inplace (enable in-place field representation updates) + type: bool default: true + --max-polymorphic-map-count (maximum number of maps to track in POLYMORPHIC state) + type: int default: 4 + --native-code-counters (generate extra code for manipulating stats counters) + type: bool default: false + --thin-strings (Enable ThinString support) + type: bool default: true + --trace-prototype-users (Trace updates to prototype user tracking) + type: bool default: false + --trace-for-in-enumerate (Trace for-in enumerate slow-paths) + type: bool default: false + --trace-maps (trace map creation) + type: bool default: false + --trace-maps-details (also log map details) + type: bool default: true + --allow-natives-syntax (allow natives syntax) + type: bool default: false + --allow-natives-for-differential-fuzzing (allow only natives explicitly allowlisted for differential fuzzers) + type: bool default: false + --parse-only (only parse the sources) + 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-colour (When logging, try to use coloured output.) + type: bool default: true + --trace-sim-messages (Trace simulator debug messages. Implied by --trace-sim.) + type: bool default: false + --async-stack-traces (include async stack traces in Error.stack) + type: bool default: true + --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 + --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.) + 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 + --rehash-snapshot (rehash strings from the snapshot to 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: uint64 default: 0 + --random-seed (Default seed for initializing random generator (0, the default, means to use system random).) + type: int default: 0 + --fuzzer-random-seed (Default seed for initializing fuzzer random generator (0, the default, means to use v8's random number generator seed).) + type: int default: 0 + --trace-rail (trace RAIL mode) + type: bool default: false + --print-all-exceptions (print exception object and stack trace on each thrown exception) + type: bool default: false + --detailed-error-stack-trace (includes arguments for each function call in the error stack frames array) + type: bool default: false + --adjust-os-scheduling-parameters (adjust OS specific scheduling params for the isolate) + type: bool default: true + --runtime-call-stats (report runtime call counts and times) + type: bool default: false + --rcs (report runtime call counts and times) + type: bool default: false + --rcs-cpu-time (report runtime times in cpu time (the default is wall time)) + 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 + --serialization-chunk-size (Custom size for serialization chunks) + type: uint default: 4096 + --regexp-optimization (generate optimized regexp code) + type: bool default: true + --regexp-mode-modifiers (enable inline flags in regexp.) + type: bool default: false + --regexp-interpret-all (interpret all regexp code) + type: bool default: false + --regexp-tier-up (enable regexp interpreter and tier up to the compiler after the number of executions set by the tier up ticks flag) + type: bool default: true + --regexp-tier-up-ticks (set the number of executions for the regexp interpreter before tiering-up to the compiler) + type: int default: 1 + --regexp-peephole-optimization (enable peephole optimization for regexp bytecode) + type: bool default: true + --trace-regexp-peephole-optimization (trace regexp bytecode peephole optimization) + type: bool default: false + --trace-regexp-bytecodes (trace regexp bytecode execution) + type: bool default: false + --trace-regexp-assembler (trace regexp macro assembler calls.) + type: bool default: false + --trace-regexp-parser (trace regexp parsing) + type: bool default: false + --trace-regexp-tier-up (trace regexp tiering up execution) + type: bool default: false + --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 + --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) + type: bool default: false + --fuzzing (Fuzzers use this flag to signal that they are ... fuzzing. This causes intrinsics to fail silently (e.g. return undefined) on invalid usage.) + type: bool default: false + --embedded-src (Path for the generated embedded data file. (mksnapshot only)) + type: string default: nullptr + --embedded-variant (Label to disambiguate symbols in embedded data file. (mksnapshot only)) + type: string default: nullptr + --startup-src (Write V8 startup as C++ src. (mksnapshot only)) + type: string default: nullptr + --startup-blob (Write V8 startup blob file. (mksnapshot only)) + type: string default: nullptr + --target-arch (The mksnapshot target arch. (mksnapshot only)) + type: string default: nullptr + --target-os (The mksnapshot target os. (mksnapshot only)) + type: string default: nullptr + --target-is-simulator (Instruct mksnapshot that the target is meant to run in the simulator and it can generate simulator-specific instructions. (mksnapshot only)) + type: bool default: false + --minor-mc-parallel-marking (use parallel marking for the young generation) + type: bool default: true + --trace-minor-mc-parallel-marking (trace parallel marking for the young generation) + type: bool default: false + --minor-mc (perform young generation mark compact GCs) + 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 + --dump-counters-nvp (Dump counters as name-value pairs on exit) + type: bool default: false + --use-external-strings (Use external strings for source code) + type: bool default: false + --map-counters (Map counters to a file) + type: string default: + --mock-arraybuffer-allocator (Use a mock ArrayBuffer allocator for testing.) + type: bool default: false + --mock-arraybuffer-allocator-limit (Memory limit for mock ArrayBuffer allocator used to simulate OOM for testing.) + type: size_t default: 0 + --gdbjit (enable GDBJIT interface) + type: bool default: false + --gdbjit-full (enable GDBJIT interface for all code objects) + type: bool default: false + --gdbjit-dump (dump elf objects with debug info to disk) + type: bool default: false + --gdbjit-dump-filter (dump only objects containing this substring) + type: string 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-handles (Log global handle events.) + type: bool default: false + --log-suspect (Log suspect operations.) + type: bool default: false + --log-source-code (Log source code.) + type: bool default: false + --log-function-events (Log function events (parse, compile, execute) separately.) + type: bool default: false + --prof (Log statistical profiling information (implies --log-code).) + type: bool default: false + --detailed-line-info (Always generate detailed line information for CPU profiling.) + type: bool default: false + --prof-sampling-interval (Interval for --prof samples (in microseconds).) + type: int default: 1000 + --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 + --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 + --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 + --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: nullptr + --print-opt-source (print source code of optimized and inlined functions) + type: bool default: false + --vtune-prof-annotate-wasm (Used when v8_enable_vtunejit is enabled, load wasm source map and provide annotate support (experimental).) + type: bool default: false + --win64-unwinding-info (Enable unwinding info for Windows/x64) + type: bool default: true + --interpreted-frames-native-stack (Show interpreted frames on the native stack (useful for external profilers).) + type: bool default: false + --predictable (enable predictable mode) + type: bool default: false + --predictable-gc-schedule (Predictable garbage collection schedule. Fixes heap growing, idle, and memory reducing behavior.) + type: bool default: false + --single-threaded (disable the use of background tasks) + type: bool default: false + --single-threaded-gc (disable the use of background gc tasks) + type: bool default: false ``` Particularly useful ones: |