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1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 // This file defines all of the flags.  It is separated into different section,
6 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
7 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
8 //
9 // This include does not have a guard, because it is a template-style include,
10 // which can be included multiple times in different modes.  It expects to have
11 // a mode defined before it's included.  The modes are FLAG_MODE_... below:
12 //
13 // PRESUBMIT_INTENTIONALLY_MISSING_INCLUDE_GUARD
14 
15 #define DEFINE_IMPLICATION(whenflag, thenflag) \
16   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, true)
17 
18 // A weak implication will be overwritten by a normal implication or by an
19 // explicit flag.
20 #define DEFINE_WEAK_IMPLICATION(whenflag, thenflag) \
21   DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, true)
22 
23 #define DEFINE_NEG_IMPLICATION(whenflag, thenflag) \
24   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, false)
25 
26 #define DEFINE_NEG_NEG_IMPLICATION(whenflag, thenflag) \
27   DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, false)
28 
29 // We want to declare the names of the variables for the header file.  Normally
30 // this will just be an extern declaration, but for a readonly flag we let the
31 // compiler make better optimizations by giving it the value.
32 #if defined(FLAG_MODE_DECLARE)
33 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
34   V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
35 #define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
36   static constexpr ctype FLAG_##nam = def;
37 
38 // We want to supply the actual storage and value for the flag variable in the
39 // .cc file.  We only do this for writable flags.
40 #elif defined(FLAG_MODE_DEFINE)
41 #ifdef USING_V8_SHARED
42 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
43   V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
44 #else
45 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
46   V8_EXPORT_PRIVATE ctype FLAG_##nam = def;
47 #endif
48 
49 // We need to define all of our default values so that the Flag structure can
50 // access them by pointer.  These are just used internally inside of one .cc,
51 // for MODE_META, so there is no impact on the flags interface.
52 #elif defined(FLAG_MODE_DEFINE_DEFAULTS)
53 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
54   static constexpr ctype FLAGDEFAULT_##nam = def;
55 
56 // We want to write entries into our meta data table, for internal parsing and
57 // printing / etc in the flag parser code.  We only do this for writable flags.
58 #elif defined(FLAG_MODE_META)
59 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
60   {Flag::TYPE_##ftype, #nam, &FLAG_##nam, &FLAGDEFAULT_##nam, cmt, false},
61 #define FLAG_ALIAS(ftype, ctype, alias, nam)                     \
62   {Flag::TYPE_##ftype,  #alias, &FLAG_##nam, &FLAGDEFAULT_##nam, \
63     "alias for --" #nam, false},
64 
65 // We produce the code to set flags when it is implied by another flag.
66 #elif defined(FLAG_MODE_DEFINE_IMPLICATIONS)
67 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)                   \
68   changed |= TriggerImplication(FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
69                                 value, false);
70 
71 // A weak implication will be overwritten by a normal implication or by an
72 // explicit flag.
73 #define DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, value)              \
74   changed |= TriggerImplication(FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
75                                 value, true);
76 
77 #define DEFINE_GENERIC_IMPLICATION(whenflag, statement) \
78   if (FLAG_##whenflag) statement;
79 
80 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)                \
81   changed |= TriggerImplication(!FLAG_##whenflag, #whenflag, &FLAG_##thenflag, \
82                                 value, false);
83 
84 // We apply a generic macro to the flags.
85 #elif defined(FLAG_MODE_APPLY)
86 
87 #define FLAG_FULL FLAG_MODE_APPLY
88 
89 #else
90 #error No mode supplied when including flags.defs
91 #endif
92 
93 // Dummy defines for modes where it is not relevant.
94 #ifndef FLAG_FULL
95 #define FLAG_FULL(ftype, ctype, nam, def, cmt)
96 #endif
97 
98 #ifndef FLAG_READONLY
99 #define FLAG_READONLY(ftype, ctype, nam, def, cmt)
100 #endif
101 
102 #ifndef FLAG_ALIAS
103 #define FLAG_ALIAS(ftype, ctype, alias, nam)
104 #endif
105 
106 #ifndef DEFINE_VALUE_IMPLICATION
107 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)
108 #endif
109 
110 #ifndef DEFINE_WEAK_VALUE_IMPLICATION
111 #define DEFINE_WEAK_VALUE_IMPLICATION(whenflag, thenflag, value)
112 #endif
113 
114 #ifndef DEFINE_GENERIC_IMPLICATION
115 #define DEFINE_GENERIC_IMPLICATION(whenflag, statement)
116 #endif
117 
118 #ifndef DEFINE_NEG_VALUE_IMPLICATION
119 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)
120 #endif
121 
122 #define COMMA ,
123 
124 #ifdef FLAG_MODE_DECLARE
125 
126 struct MaybeBoolFlag {
CreateMaybeBoolFlag127   static MaybeBoolFlag Create(bool has_value, bool value) {
128     MaybeBoolFlag flag;
129     flag.has_value = has_value;
130     flag.value = value;
131     return flag;
132   }
133   bool has_value;
134   bool value;
135 
136   bool operator!=(const MaybeBoolFlag& other) const {
137     return has_value != other.has_value || value != other.value;
138   }
139 };
140 #endif
141 
142 #ifdef DEBUG
143 #define DEBUG_BOOL true
144 #else
145 #define DEBUG_BOOL false
146 #endif
147 
148 #ifdef V8_COMPRESS_POINTERS
149 #define COMPRESS_POINTERS_BOOL true
150 #else
151 #define COMPRESS_POINTERS_BOOL false
152 #endif
153 
154 #ifdef V8_HEAP_SANDBOX
155 #define V8_HEAP_SANDBOX_BOOL true
156 #else
157 #define V8_HEAP_SANDBOX_BOOL false
158 #endif
159 
160 #ifdef V8_ENABLE_CONTROL_FLOW_INTEGRITY
161 #define ENABLE_CONTROL_FLOW_INTEGRITY_BOOL true
162 #else
163 #define ENABLE_CONTROL_FLOW_INTEGRITY_BOOL false
164 #endif
165 
166 // Supported ARM configurations are:
167 //  "armv6":       ARMv6 + VFPv2
168 //  "armv7":       ARMv7 + VFPv3-D32 + NEON
169 //  "armv7+sudiv": ARMv7 + VFPv4-D32 + NEON + SUDIV
170 //  "armv8":       ARMv8 (including all of the above)
171 #if !defined(ARM_TEST_NO_FEATURE_PROBE) ||                            \
172     (defined(CAN_USE_ARMV8_INSTRUCTIONS) &&                           \
173      defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
174      defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS))
175 #define ARM_ARCH_DEFAULT "armv8"
176 #elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
177     defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS)
178 #define ARM_ARCH_DEFAULT "armv7+sudiv"
179 #elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_NEON) && \
180     defined(CAN_USE_VFP3_INSTRUCTIONS)
181 #define ARM_ARCH_DEFAULT "armv7"
182 #else
183 #define ARM_ARCH_DEFAULT "armv6"
184 #endif
185 
186 #ifdef V8_OS_WIN
187 #define ENABLE_LOG_COLOUR false
188 #else
189 #define ENABLE_LOG_COLOUR true
190 #endif
191 
192 #define DEFINE_BOOL(nam, def, cmt) FLAG(BOOL, bool, nam, def, cmt)
193 #define DEFINE_BOOL_READONLY(nam, def, cmt) \
194   FLAG_READONLY(BOOL, bool, nam, def, cmt)
195 #define DEFINE_MAYBE_BOOL(nam, cmt) \
196   FLAG(MAYBE_BOOL, MaybeBoolFlag, nam, {false COMMA false}, cmt)
197 #define DEFINE_INT(nam, def, cmt) FLAG(INT, int, nam, def, cmt)
198 #define DEFINE_UINT(nam, def, cmt) FLAG(UINT, unsigned int, nam, def, cmt)
199 #define DEFINE_UINT_READONLY(nam, def, cmt) \
200   FLAG_READONLY(UINT, unsigned int, nam, def, cmt)
201 #define DEFINE_UINT64(nam, def, cmt) FLAG(UINT64, uint64_t, nam, def, cmt)
202 #define DEFINE_FLOAT(nam, def, cmt) FLAG(FLOAT, double, nam, def, cmt)
203 #define DEFINE_SIZE_T(nam, def, cmt) FLAG(SIZE_T, size_t, nam, def, cmt)
204 #define DEFINE_STRING(nam, def, cmt) FLAG(STRING, const char*, nam, def, cmt)
205 #define DEFINE_ALIAS_BOOL(alias, nam) FLAG_ALIAS(BOOL, bool, alias, nam)
206 #define DEFINE_ALIAS_INT(alias, nam) FLAG_ALIAS(INT, int, alias, nam)
207 #define DEFINE_ALIAS_FLOAT(alias, nam) FLAG_ALIAS(FLOAT, double, alias, nam)
208 #define DEFINE_ALIAS_SIZE_T(alias, nam) FLAG_ALIAS(SIZE_T, size_t, alias, nam)
209 #define DEFINE_ALIAS_STRING(alias, nam) \
210   FLAG_ALIAS(STRING, const char*, alias, nam)
211 
212 #ifdef DEBUG
213 #define DEFINE_DEBUG_BOOL DEFINE_BOOL
214 #else
215 #define DEFINE_DEBUG_BOOL DEFINE_BOOL_READONLY
216 #endif
217 
218 //
219 // Flags in all modes.
220 //
221 #define FLAG FLAG_FULL
222 
223 // ATTENTION: This is set to true by default in d8. But for API compatibility,
224 // it generally defaults to false.
225 DEFINE_BOOL(abort_on_contradictory_flags, false,
226             "Disallow flags or implications overriding each other.")
227 // This implication is also hard-coded into the flags processing to make sure it
228 // becomes active before we even process subsequent flags.
229 DEFINE_NEG_IMPLICATION(fuzzing, abort_on_contradictory_flags)
230 // This is not really a flag, it affects the interpretation of the next flag but
231 // doesn't become permanently true when specified. This only works for flags
232 // defined in this file, but not for d8 flags defined in src/d8/d8.cc.
233 DEFINE_BOOL(allow_overwriting_for_next_flag, false,
234             "temporary disable flag contradiction to allow overwriting just "
235             "the next flag")
236 
237 // Flags for language modes and experimental language features.
238 DEFINE_BOOL(use_strict, false, "enforce strict mode")
239 
240 DEFINE_BOOL(es_staging, false,
241             "enable test-worthy harmony features (for internal use only)")
242 DEFINE_BOOL(harmony, false, "enable all completed harmony features")
243 DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
244 DEFINE_IMPLICATION(es_staging, harmony)
245 // Enabling FinalizationRegistry#cleanupSome also enables weak refs
246 DEFINE_IMPLICATION(harmony_weak_refs_with_cleanup_some, harmony_weak_refs)
247 
248 // Update bootstrapper.cc whenever adding a new feature flag.
249 
250 // Features that are still work in progress (behind individual flags).
251 #define HARMONY_INPROGRESS_BASE(V)                                             \
252   V(harmony_regexp_sequence, "RegExp Unicode sequence properties")             \
253   V(harmony_weak_refs_with_cleanup_some,                                       \
254     "harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
255   V(harmony_regexp_match_indices, "harmony regexp match indices")              \
256   V(harmony_import_assertions, "harmony import assertions")
257 
258 #ifdef V8_INTL_SUPPORT
259 #define HARMONY_INPROGRESS(V)                       \
260   HARMONY_INPROGRESS_BASE(V)                        \
261   V(harmony_intl_displaynames_date_types, "Intl.DisplayNames date types")
262 #else
263 #define HARMONY_INPROGRESS(V) HARMONY_INPROGRESS_BASE(V)
264 #endif
265 
266 // Features that are complete (but still behind --harmony/es-staging flag).
267 #define HARMONY_STAGED_BASE(V) \
268   V(harmony_top_level_await, "harmony top level await")
269 
270 #ifdef V8_INTL_SUPPORT
271 #define HARMONY_STAGED(V)               \
272   HARMONY_STAGED_BASE(V)                \
273   V(harmony_intl_dateformat_day_period, \
274     "Add dayPeriod option to DateTimeFormat")
275 #else
276 #define HARMONY_STAGED(V) HARMONY_STAGED_BASE(V)
277 #endif
278 
279 // Features that are shipping (turned on by default, but internal flag remains).
280 #define HARMONY_SHIPPING_BASE(V)                                          \
281   V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")               \
282   V(harmony_atomics, "harmony atomics")                                   \
283   V(harmony_promise_any, "harmony Promise.any")                           \
284   V(harmony_private_methods, "harmony private methods in class literals") \
285   V(harmony_weak_refs, "harmony weak references")                         \
286   V(harmony_string_replaceall, "harmony String.prototype.replaceAll")     \
287   V(harmony_logical_assignment, "harmony logical assignment")             \
288   V(harmony_atomics_waitasync, "harmony Atomics.waitAsync")
289 
290 #ifdef V8_INTL_SUPPORT
291 #define HARMONY_SHIPPING(V) \
292   HARMONY_SHIPPING_BASE(V)  \
293   V(harmony_intl_segmenter, "Intl.Segmenter")
294 #else
295 #define HARMONY_SHIPPING(V) HARMONY_SHIPPING_BASE(V)
296 #endif
297 
298 // Once a shipping feature has proved stable in the wild, it will be dropped
299 // from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,
300 // and associated tests are moved from the harmony directory to the appropriate
301 // esN directory.
302 
303 #define FLAG_INPROGRESS_FEATURES(id, description) \
304   DEFINE_BOOL(id, false, "enable " #description " (in progress)")
305 HARMONY_INPROGRESS(FLAG_INPROGRESS_FEATURES)
306 #undef FLAG_INPROGRESS_FEATURES
307 
308 #define FLAG_STAGED_FEATURES(id, description)    \
309   DEFINE_BOOL(id, false, "enable " #description) \
310   DEFINE_IMPLICATION(harmony, id)
311 HARMONY_STAGED(FLAG_STAGED_FEATURES)
312 #undef FLAG_STAGED_FEATURES
313 
314 #define FLAG_SHIPPING_FEATURES(id, description) \
315   DEFINE_BOOL(id, true, "enable " #description) \
316   DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
317 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
318 #undef FLAG_SHIPPING_FEATURES
319 
320 #ifdef V8_INTL_SUPPORT
321 DEFINE_BOOL(icu_timezone_data, true, "get information about timezones from ICU")
322 #endif
323 
324 #ifdef V8_ENABLE_DOUBLE_CONST_STORE_CHECK
325 #define V8_ENABLE_DOUBLE_CONST_STORE_CHECK_BOOL true
326 #else
327 #define V8_ENABLE_DOUBLE_CONST_STORE_CHECK_BOOL false
328 #endif
329 
330 #ifdef V8_LITE_MODE
331 #define V8_LITE_BOOL true
332 #else
333 #define V8_LITE_BOOL false
334 #endif
335 
336 #ifdef V8_ENABLE_LAZY_SOURCE_POSITIONS
337 #define V8_LAZY_SOURCE_POSITIONS_BOOL true
338 #else
339 #define V8_LAZY_SOURCE_POSITIONS_BOOL false
340 #endif
341 
342 #ifdef V8_SHARED_RO_HEAP
343 #define V8_SHARED_RO_HEAP_BOOL true
344 #else
345 #define V8_SHARED_RO_HEAP_BOOL false
346 #endif
347 
348 DEFINE_BOOL(lite_mode, V8_LITE_BOOL,
349             "enables trade-off of performance for memory savings")
350 
351 // Lite mode implies other flags to trade-off performance for memory.
352 DEFINE_IMPLICATION(lite_mode, jitless)
353 DEFINE_IMPLICATION(lite_mode, lazy_feedback_allocation)
354 DEFINE_IMPLICATION(lite_mode, optimize_for_size)
355 
356 #ifdef V8_ENABLE_THIRD_PARTY_HEAP
357 #define V8_ENABLE_THIRD_PARTY_HEAP_BOOL true
358 #else
359 #define V8_ENABLE_THIRD_PARTY_HEAP_BOOL false
360 #endif
361 
362 DEFINE_NEG_IMPLICATION(enable_third_party_heap, inline_new)
363 DEFINE_NEG_IMPLICATION(enable_third_party_heap, allocation_site_pretenuring)
364 DEFINE_NEG_IMPLICATION(enable_third_party_heap, turbo_allocation_folding)
365 
366 DEFINE_BOOL_READONLY(enable_third_party_heap, V8_ENABLE_THIRD_PARTY_HEAP_BOOL,
367                      "Use third-party heap")
368 
369 #ifdef V8_DISABLE_WRITE_BARRIERS
370 #define V8_DISABLE_WRITE_BARRIERS_BOOL true
371 #else
372 #define V8_DISABLE_WRITE_BARRIERS_BOOL false
373 #endif
374 
375 DEFINE_BOOL_READONLY(disable_write_barriers, V8_DISABLE_WRITE_BARRIERS_BOOL,
376                      "disable write barriers when GC is non-incremental "
377                      "and heap contains single generation.")
378 
379 // Disable incremental marking barriers
380 DEFINE_NEG_IMPLICATION(disable_write_barriers, incremental_marking)
381 
382 #ifdef V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS
383 #define V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL true
384 #else
385 #define V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL false
386 #endif
387 
388 DEFINE_BOOL_READONLY(enable_unconditional_write_barriers,
389                      V8_ENABLE_UNCONDITIONAL_WRITE_BARRIERS_BOOL,
390                      "always use full write barriers")
391 
392 #ifdef V8_ENABLE_SINGLE_GENERATION
393 #define V8_GENERATION_BOOL true
394 #else
395 #define V8_GENERATION_BOOL false
396 #endif
397 
398 DEFINE_BOOL_READONLY(
399     single_generation, V8_GENERATION_BOOL,
400     "allocate all objects from young generation to old generation")
401 
402 // Prevent inline allocation into new space
403 DEFINE_NEG_IMPLICATION(single_generation, inline_new)
404 DEFINE_NEG_IMPLICATION(single_generation, turbo_allocation_folding)
405 
406 #ifdef V8_ENABLE_CONSERVATIVE_STACK_SCANNING
407 #define V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL true
408 #else
409 #define V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL false
410 #endif
411 DEFINE_BOOL_READONLY(conservative_stack_scanning,
412                      V8_ENABLE_CONSERVATIVE_STACK_SCANNING_BOOL,
413                      "use conservative stack scanning")
414 
415 #ifdef V8_ENABLE_FUTURE
416 #define FUTURE_BOOL true
417 #else
418 #define FUTURE_BOOL false
419 #endif
420 DEFINE_BOOL(future, FUTURE_BOOL,
421             "Implies all staged features that we want to ship in the "
422             "not-too-far future")
423 
424 DEFINE_WEAK_IMPLICATION(future, write_protect_code_memory)
425 DEFINE_WEAK_IMPLICATION(future, finalize_streaming_on_background)
426 DEFINE_WEAK_IMPLICATION(future, super_ic)
427 
428 // Flags for jitless
429 DEFINE_BOOL(jitless, V8_LITE_BOOL,
430             "Disable runtime allocation of executable memory.")
431 
432 // Jitless V8 has a few implications:
433 DEFINE_NEG_IMPLICATION(jitless, opt)
434 // Field representation tracking is only used by TurboFan.
435 DEFINE_NEG_IMPLICATION(jitless, track_field_types)
436 DEFINE_NEG_IMPLICATION(jitless, track_heap_object_fields)
437 // Regexps are interpreted.
438 DEFINE_IMPLICATION(jitless, regexp_interpret_all)
439 // asm.js validation is disabled since it triggers wasm code generation.
440 DEFINE_NEG_IMPLICATION(jitless, validate_asm)
441 // --jitless also implies --no-expose-wasm, see InitializeOncePerProcessImpl.
442 
443 #ifndef V8_TARGET_ARCH_ARM
444 // Unsupported on arm. See https://crbug.com/v8/8713.
445 DEFINE_NEG_IMPLICATION(jitless, interpreted_frames_native_stack)
446 #endif
447 
448 DEFINE_BOOL(assert_types, false,
449             "generate runtime type assertions to test the typer")
450 
451 DEFINE_BOOL(trace_code_dependencies, false, "trace code dependencies")
452 // Depend on --trace-deopt-verbose for reporting dependency invalidations.
453 DEFINE_IMPLICATION(trace_code_dependencies, trace_deopt_verbose)
454 
455 // Flags for experimental implementation features.
456 DEFINE_BOOL(allocation_site_pretenuring, true,
457             "pretenure with allocation sites")
458 DEFINE_BOOL(page_promotion, true, "promote pages based on utilization")
459 DEFINE_BOOL_READONLY(always_promote_young_mc, true,
460                      "always promote young objects during mark-compact")
461 DEFINE_INT(page_promotion_threshold, 70,
462            "min percentage of live bytes on a page to enable fast evacuation")
463 DEFINE_BOOL(trace_pretenuring, false,
464             "trace pretenuring decisions of HAllocate instructions")
465 DEFINE_BOOL(trace_pretenuring_statistics, false,
466             "trace allocation site pretenuring statistics")
467 DEFINE_BOOL(track_fields, true, "track fields with only smi values")
468 DEFINE_BOOL(track_double_fields, true, "track fields with double values")
469 DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
470 DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
471 DEFINE_IMPLICATION(track_double_fields, track_fields)
472 DEFINE_IMPLICATION(track_heap_object_fields, track_fields)
473 DEFINE_IMPLICATION(track_computed_fields, track_fields)
474 DEFINE_BOOL(track_field_types, true, "track field types")
475 DEFINE_IMPLICATION(track_field_types, track_fields)
476 DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
477 DEFINE_BOOL(trace_block_coverage, false,
478             "trace collected block coverage information")
479 DEFINE_BOOL(trace_protector_invalidation, false,
480             "trace protector cell invalidations")
481 DEFINE_BOOL(feedback_normalization, false,
482             "feed back normalization to constructors")
483 // TODO(jkummerow): This currently adds too much load on the stub cache.
484 DEFINE_BOOL_READONLY(internalize_on_the_fly, true,
485                      "internalize string keys for generic keyed ICs on the fly")
486 
487 // Flag for one shot optimiztions.
488 DEFINE_BOOL(enable_one_shot_optimization, false,
489             "Enable size optimizations for the code that will "
490             "only be executed once")
491 
492 // Flag for sealed, frozen elements kind instead of dictionary elements kind
493 DEFINE_BOOL_READONLY(enable_sealed_frozen_elements_kind, true,
494                      "Enable sealed, frozen elements kind")
495 
496 // Flags for data representation optimizations
497 DEFINE_BOOL(unbox_double_arrays, true, "automatically unbox arrays of doubles")
498 DEFINE_BOOL_READONLY(string_slices, true, "use string slices")
499 
500 DEFINE_INT(interrupt_budget, 144 * KB,
501            "interrupt budget which should be used for the profiler counter")
502 
503 // Flags for inline caching and feedback vectors.
504 DEFINE_BOOL(use_ic, true, "use inline caching")
505 DEFINE_INT(budget_for_feedback_vector_allocation, 1 * KB,
506            "The budget in amount of bytecode executed by a function before we "
507            "decide to allocate feedback vectors")
508 DEFINE_BOOL(lazy_feedback_allocation, true, "Allocate feedback vectors lazily")
509 
510 // Flags for Ignition.
511 DEFINE_BOOL(ignition_elide_noneffectful_bytecodes, true,
512             "elide bytecodes which won't have any external effect")
513 DEFINE_BOOL(ignition_reo, true, "use ignition register equivalence optimizer")
514 DEFINE_BOOL(ignition_filter_expression_positions, true,
515             "filter expression positions before the bytecode pipeline")
516 DEFINE_BOOL(ignition_share_named_property_feedback, true,
517             "share feedback slots when loading the same named property from "
518             "the same object")
519 DEFINE_BOOL(print_bytecode, false,
520             "print bytecode generated by ignition interpreter")
521 DEFINE_BOOL(enable_lazy_source_positions, V8_LAZY_SOURCE_POSITIONS_BOOL,
522             "skip generating source positions during initial compile but "
523             "regenerate when actually required")
524 DEFINE_BOOL(stress_lazy_source_positions, false,
525             "collect lazy source positions immediately after lazy compile")
526 DEFINE_STRING(print_bytecode_filter, "*",
527               "filter for selecting which functions to print bytecode")
528 #ifdef V8_TRACE_IGNITION
529 DEFINE_BOOL(trace_ignition, false,
530             "trace the bytecodes executed by the ignition interpreter")
531 #endif
532 #ifdef V8_TRACE_FEEDBACK_UPDATES
533 DEFINE_BOOL(
534     trace_feedback_updates, false,
535     "trace updates to feedback vectors during ignition interpreter execution.")
536 #endif
537 DEFINE_BOOL(trace_ignition_codegen, false,
538             "trace the codegen of ignition interpreter bytecode handlers")
539 DEFINE_BOOL(trace_ignition_dispatches, false,
540             "traces the dispatches to bytecode handlers by the ignition "
541             "interpreter")
542 DEFINE_STRING(trace_ignition_dispatches_output_file, nullptr,
543               "the file to which the bytecode handler dispatch table is "
544               "written (by default, the table is not written to a file)")
545 
546 DEFINE_BOOL(fast_math, true, "faster (but maybe less accurate) math functions")
547 DEFINE_BOOL(trace_track_allocation_sites, false,
548             "trace the tracking of allocation sites")
549 DEFINE_BOOL(trace_migration, false, "trace object migration")
550 DEFINE_BOOL(trace_generalization, false, "trace map generalization")
551 
552 // Flags for TurboProp.
553 DEFINE_BOOL(turboprop, false, "enable experimental turboprop mid-tier compiler")
554 DEFINE_BOOL(turboprop_mid_tier_reg_alloc, true,
555             "enable mid-tier register allocator for turboprop")
556 DEFINE_BOOL(turboprop_dynamic_map_checks, false,
557             "use dynamic map checks when generating code for property accesses "
558             "if all handlers in an IC are the same for turboprop")
559 DEFINE_BOOL(turboprop_as_midtier, false,
560             "enable experimental turboprop mid-tier compiler")
561 DEFINE_IMPLICATION(turboprop_as_midtier, turboprop)
562 DEFINE_IMPLICATION(turboprop, concurrent_inlining)
563 DEFINE_VALUE_IMPLICATION(turboprop, interrupt_budget, 15 * KB)
564 DEFINE_VALUE_IMPLICATION(turboprop, reuse_opt_code_count, 2)
565 DEFINE_UINT_READONLY(max_minimorphic_map_checks, 4,
566                      "max number of map checks to perform in minimorphic state")
567 // Since Turboprop uses much lower value for interrupt budget, we need to wait
568 // for a higher number of ticks to tierup to Turbofan roughly match the default.
569 // The default of 10 is approximately the ration of TP to TF interrupt budget.
570 DEFINE_INT(ticks_scale_factor_for_top_tier, 10,
571            "scale factor for profiler ticks when tiering up from midtier")
572 
573 // Flags for concurrent recompilation.
574 DEFINE_BOOL(concurrent_recompilation, true,
575             "optimizing hot functions asynchronously on a separate thread")
576 DEFINE_BOOL(trace_concurrent_recompilation, false,
577             "track concurrent recompilation")
578 DEFINE_INT(concurrent_recompilation_queue_length, 8,
579            "the length of the concurrent compilation queue")
580 DEFINE_INT(concurrent_recompilation_delay, 0,
581            "artificial compilation delay in ms")
582 DEFINE_BOOL(block_concurrent_recompilation, false,
583             "block queued jobs until released")
584 DEFINE_BOOL(concurrent_inlining, false,
585             "run optimizing compiler's inlining phase on a separate thread")
586 DEFINE_BOOL(turbo_direct_heap_access, false,
587             "access kNeverSerialized objects directly from the heap")
588 DEFINE_IMPLICATION(concurrent_inlining, turbo_direct_heap_access)
589 DEFINE_INT(max_serializer_nesting, 25,
590            "maximum levels for nesting child serializers")
591 DEFINE_WEAK_IMPLICATION(future, concurrent_inlining)
592 DEFINE_BOOL(trace_heap_broker_verbose, false,
593             "trace the heap broker verbosely (all reports)")
594 DEFINE_BOOL(trace_heap_broker_memory, false,
595             "trace the heap broker memory (refs analysis and zone numbers)")
596 DEFINE_BOOL(trace_heap_broker, false,
597             "trace the heap broker (reports on missing data only)")
598 DEFINE_IMPLICATION(trace_heap_broker_verbose, trace_heap_broker)
599 DEFINE_IMPLICATION(trace_heap_broker_memory, trace_heap_broker)
600 
601 // Flags for stress-testing the compiler.
602 DEFINE_INT(stress_runs, 0, "number of stress runs")
603 DEFINE_INT(deopt_every_n_times, 0,
604            "deoptimize every n times a deopt point is passed")
605 DEFINE_BOOL(print_deopt_stress, false, "print number of possible deopt points")
606 
607 // Flags for TurboFan.
608 DEFINE_BOOL(opt, true, "use adaptive optimizations")
609 DEFINE_BOOL(turbo_sp_frame_access, false,
610             "use stack pointer-relative access to frame wherever possible")
611 DEFINE_BOOL(
612     stress_turbo_late_spilling, false,
613     "optimize placement of all spill instructions, not just loop-top phis")
614 
615 DEFINE_STRING(turbo_filter, "*", "optimization filter for TurboFan compiler")
616 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
617 DEFINE_STRING(trace_turbo_path, nullptr,
618               "directory to dump generated TurboFan IR to")
619 DEFINE_STRING(trace_turbo_filter, "*",
620               "filter for tracing turbofan compilation")
621 DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
622 DEFINE_BOOL(trace_turbo_scheduled, false, "trace TurboFan IR with schedule")
623 DEFINE_IMPLICATION(trace_turbo_scheduled, trace_turbo_graph)
624 DEFINE_STRING(trace_turbo_cfg_file, nullptr,
625               "trace turbo cfg graph (for C1 visualizer) to a given file name")
626 DEFINE_BOOL(trace_turbo_types, true, "trace TurboFan's types")
627 DEFINE_BOOL(trace_turbo_scheduler, false, "trace TurboFan's scheduler")
628 DEFINE_BOOL(trace_turbo_reduction, false, "trace TurboFan's various reducers")
629 DEFINE_BOOL(trace_turbo_trimming, false, "trace TurboFan's graph trimmer")
630 DEFINE_BOOL(trace_turbo_jt, false, "trace TurboFan's jump threading")
631 DEFINE_BOOL(trace_turbo_ceq, false, "trace TurboFan's control equivalence")
632 DEFINE_BOOL(trace_turbo_loop, false, "trace TurboFan's loop optimizations")
633 DEFINE_BOOL(trace_turbo_alloc, false, "trace TurboFan's register allocator")
634 DEFINE_BOOL(trace_all_uses, false, "trace all use positions")
635 DEFINE_BOOL(trace_representation, false, "trace representation types")
636 DEFINE_BOOL(
637     trace_turbo_stack_accesses, false,
638     "trace stack load/store counters for optimized code in run-time (x64 only)")
639 DEFINE_BOOL(turbo_verify, DEBUG_BOOL, "verify TurboFan graphs at each phase")
640 DEFINE_STRING(turbo_verify_machine_graph, nullptr,
641               "verify TurboFan machine graph before instruction selection")
642 #ifdef ENABLE_VERIFY_CSA
643 DEFINE_BOOL(verify_csa, DEBUG_BOOL,
644             "verify TurboFan machine graph of code stubs")
645 #else
646 // Define the flag as read-only-false so that code still compiles even in the
647 // non-ENABLE_VERIFY_CSA configuration.
648 DEFINE_BOOL_READONLY(verify_csa, false,
649                      "verify TurboFan machine graph of code stubs")
650 #endif
651 DEFINE_BOOL(trace_verify_csa, false, "trace code stubs verification")
652 DEFINE_STRING(csa_trap_on_node, nullptr,
653               "trigger break point when a node with given id is created in "
654               "given stub. The format is: StubName,NodeId")
655 DEFINE_BOOL_READONLY(fixed_array_bounds_checks, true,
656                      "enable FixedArray bounds checks")
657 DEFINE_BOOL(turbo_stats, false, "print TurboFan statistics")
658 DEFINE_BOOL(turbo_stats_nvp, false,
659             "print TurboFan statistics in machine-readable format")
660 DEFINE_BOOL(turbo_stats_wasm, false,
661             "print TurboFan statistics of wasm compilations")
662 DEFINE_BOOL(turbo_splitting, true, "split nodes during scheduling in TurboFan")
663 DEFINE_BOOL(function_context_specialization, false,
664             "enable function context specialization in TurboFan")
665 DEFINE_BOOL(turbo_inlining, true, "enable inlining in TurboFan")
666 DEFINE_INT(max_inlined_bytecode_size, 500,
667            "maximum size of bytecode for a single inlining")
668 DEFINE_INT(max_inlined_bytecode_size_cumulative, 1000,
669            "maximum cumulative size of bytecode considered for inlining")
670 DEFINE_INT(max_inlined_bytecode_size_absolute, 5000,
671            "maximum cumulative size of bytecode considered for inlining")
672 DEFINE_FLOAT(reserve_inline_budget_scale_factor, 1.2,
673              "maximum cumulative size of bytecode considered for inlining")
674 DEFINE_INT(max_inlined_bytecode_size_small, 30,
675            "maximum size of bytecode considered for small function inlining")
676 DEFINE_INT(max_optimized_bytecode_size, 60 * KB,
677            "maximum bytecode size to "
678            "be considered for optimization; too high values may cause "
679            "the compiler to hit (release) assertions")
680 DEFINE_FLOAT(min_inlining_frequency, 0.15, "minimum frequency for inlining")
681 DEFINE_BOOL(polymorphic_inlining, true, "polymorphic inlining")
682 DEFINE_BOOL(stress_inline, false,
683             "set high thresholds for inlining to inline as much as possible")
684 DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size, 999999)
685 DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size_cumulative,
686                          999999)
687 DEFINE_VALUE_IMPLICATION(stress_inline, max_inlined_bytecode_size_absolute,
688                          999999)
689 DEFINE_VALUE_IMPLICATION(stress_inline, min_inlining_frequency, 0)
690 DEFINE_IMPLICATION(stress_inline, polymorphic_inlining)
691 DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
692 DEFINE_BOOL(turbo_inline_array_builtins, true,
693             "inline array builtins in TurboFan code")
694 DEFINE_BOOL(use_osr, true, "use on-stack replacement")
695 DEFINE_BOOL(trace_osr, false, "trace on-stack replacement")
696 DEFINE_BOOL(analyze_environment_liveness, true,
697             "analyze liveness of environment slots and zap dead values")
698 DEFINE_BOOL(trace_environment_liveness, false,
699             "trace liveness of local variable slots")
700 DEFINE_BOOL(turbo_load_elimination, true, "enable load elimination in TurboFan")
701 DEFINE_BOOL(trace_turbo_load_elimination, false,
702             "trace TurboFan load elimination")
703 DEFINE_BOOL(turbo_profiling, false, "enable basic block profiling in TurboFan")
704 DEFINE_BOOL(turbo_profiling_verbose, false,
705             "enable basic block profiling in TurboFan, and include each "
706             "function's schedule and disassembly in the output")
707 DEFINE_IMPLICATION(turbo_profiling_verbose, turbo_profiling)
708 DEFINE_BOOL(turbo_profiling_log_builtins, false,
709             "emit data about basic block usage in builtins to v8.log (requires "
710             "that V8 was built with v8_enable_builtins_profiling=true)")
711 DEFINE_BOOL(turbo_verify_allocation, DEBUG_BOOL,
712             "verify register allocation in TurboFan")
713 DEFINE_BOOL(turbo_move_optimization, true, "optimize gap moves in TurboFan")
714 DEFINE_BOOL(turbo_jt, true, "enable jump threading in TurboFan")
715 DEFINE_BOOL(turbo_loop_peeling, true, "Turbofan loop peeling")
716 DEFINE_BOOL(turbo_loop_variable, true, "Turbofan loop variable optimization")
717 DEFINE_BOOL(turbo_loop_rotation, true, "Turbofan loop rotation")
718 DEFINE_BOOL(turbo_cf_optimization, true, "optimize control flow in TurboFan")
719 DEFINE_BOOL(turbo_escape, true, "enable escape analysis")
720 DEFINE_BOOL(turbo_allocation_folding, true, "Turbofan allocation folding")
721 DEFINE_BOOL(turbo_instruction_scheduling, false,
722             "enable instruction scheduling in TurboFan")
723 DEFINE_BOOL(turbo_stress_instruction_scheduling, false,
724             "randomly schedule instructions to stress dependency tracking")
725 DEFINE_IMPLICATION(turbo_stress_instruction_scheduling,
726                    turbo_instruction_scheduling)
727 DEFINE_BOOL(turbo_store_elimination, true,
728             "enable store-store elimination in TurboFan")
729 DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
730 DEFINE_BOOL(turbo_rewrite_far_jumps, true,
731             "rewrite far to near jumps (ia32,x64)")
732 DEFINE_BOOL(
733     stress_gc_during_compilation, false,
734     "simulate GC/compiler thread race related to https://crbug.com/v8/8520")
735 DEFINE_BOOL(turbo_fast_api_calls, false, "enable fast API calls from TurboFan")
736 DEFINE_INT(reuse_opt_code_count, 0,
737            "don't discard optimized code for the specified number of deopts.")
738 
739 // Native context independent (NCI) code.
740 DEFINE_BOOL(turbo_nci, false,
741             "enable experimental native context independent code.")
742 // TODO(v8:8888): Temporary until NCI caching is implemented or
743 // feedback collection is made unconditional.
744 DEFINE_IMPLICATION(turbo_nci, turbo_collect_feedback_in_generic_lowering)
745 DEFINE_BOOL(turbo_nci_as_midtier, false,
746             "insert NCI as a midtier compiler for testing purposes.")
747 DEFINE_BOOL(print_nci_code, false, "print native context independent code.")
748 DEFINE_BOOL(trace_turbo_nci, false, "trace native context independent code.")
749 DEFINE_BOOL(turbo_collect_feedback_in_generic_lowering, true,
750             "enable experimental feedback collection in generic lowering.")
751 // TODO(jgruber,v8:8888): Remove this flag once we've settled on a codegen
752 // strategy.
753 DEFINE_BOOL(turbo_nci_delayed_codegen, true,
754             "delay NCI codegen to reduce useless compilation work.")
755 // TODO(jgruber,v8:8888): Remove this flag once we've settled on an ageing
756 // strategy.
757 DEFINE_BOOL(turbo_nci_cache_ageing, false,
758             "enable ageing of the NCI code cache.")
759 // TODO(jgruber,v8:8888): Remove this flag once we've settled on an ageing
760 // strategy.
761 DEFINE_BOOL(isolate_script_cache_ageing, true,
762             "enable ageing of the isolate script cache.")
763 
764 // Favor memory over execution speed.
765 DEFINE_BOOL(optimize_for_size, false,
766             "Enables optimizations which favor memory size over execution "
767             "speed")
768 DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
769 
770 #ifdef DISABLE_UNTRUSTED_CODE_MITIGATIONS
771 #define V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS false
772 #else
773 #define V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS true
774 #endif
775 DEFINE_BOOL(untrusted_code_mitigations, V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS,
776             "Enable mitigations for executing untrusted code")
777 #undef V8_DEFAULT_UNTRUSTED_CODE_MITIGATIONS
778 
779 // Flags for native WebAssembly.
780 DEFINE_BOOL(wasm_generic_wrapper, false,
781             "use generic js-to-wasm wrapper instead of per-signature wrappers")
782 DEFINE_BOOL(expose_wasm, true, "expose wasm interface to JavaScript")
783 DEFINE_INT(wasm_num_compilation_tasks, 128,
784            "maximum number of parallel compilation tasks for wasm")
785 DEFINE_DEBUG_BOOL(trace_wasm_native_heap, false,
786                   "trace wasm native heap events")
787 DEFINE_BOOL(wasm_write_protect_code_memory, false,
788             "write protect code memory on the wasm native heap")
789 DEFINE_DEBUG_BOOL(trace_wasm_serialization, false,
790                   "trace serialization/deserialization")
791 DEFINE_BOOL(wasm_async_compilation, true,
792             "enable actual asynchronous compilation for WebAssembly.compile")
793 DEFINE_BOOL(wasm_test_streaming, false,
794             "use streaming compilation instead of async compilation for tests")
795 DEFINE_UINT(wasm_max_mem_pages, v8::internal::wasm::kSpecMaxMemoryPages,
796             "maximum number of 64KiB memory pages per wasm memory")
797 DEFINE_UINT(wasm_max_table_size, v8::internal::wasm::kV8MaxWasmTableSize,
798             "maximum table size of a wasm instance")
799 DEFINE_UINT(wasm_max_code_space, v8::internal::kMaxWasmCodeMB,
800             "maximum committed code space for wasm (in MB)")
801 DEFINE_BOOL(wasm_tier_up, true,
802             "enable tier up to the optimizing compiler (requires --liftoff to "
803             "have an effect)")
804 DEFINE_BOOL(wasm_dynamic_tiering, false,
805             "enable dynamic tier up to the optimizing compiler")
806 DEFINE_DEBUG_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
807 DEFINE_DEBUG_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
808 DEFINE_DEBUG_BOOL(trace_wasm_interpreter, false,
809                   "trace interpretation of wasm code")
810 DEFINE_DEBUG_BOOL(trace_wasm_streaming, false,
811                   "trace streaming compilation of wasm code")
812 DEFINE_INT(trace_wasm_ast_start, 0,
813            "start function for wasm AST trace (inclusive)")
814 DEFINE_INT(trace_wasm_ast_end, 0, "end function for wasm AST trace (exclusive)")
815 DEFINE_BOOL(liftoff, true,
816             "enable Liftoff, the baseline compiler for WebAssembly")
817 DEFINE_BOOL(experimental_liftoff_extern_ref, false,
818             "enable support for externref in Liftoff")
819 // We can't tier up (from Liftoff to TurboFan) in single-threaded mode, hence
820 // disable Liftoff in that configuration for now. The alternative is disabling
821 // TurboFan, which would reduce peak performance considerably.
822 // Note that for debugging, Liftoff will still be used.
823 DEFINE_NEG_IMPLICATION(single_threaded, liftoff)
824 DEFINE_DEBUG_BOOL(trace_liftoff, false,
825                   "trace Liftoff, the baseline compiler for WebAssembly")
826 DEFINE_BOOL(trace_wasm_memory, false,
827             "print all memory updates performed in wasm code")
828 // Fuzzers use {wasm_tier_mask_for_testing} together with {liftoff} and
829 // {no_wasm_tier_up} to force some functions to be compiled with Turbofan.
830 DEFINE_INT(wasm_tier_mask_for_testing, 0,
831            "bitmask of functions to compile with TurboFan instead of Liftoff")
832 
833 DEFINE_BOOL(wasm_expose_debug_eval, true,
834             "Expose wasm evaluator support on the CDP")
835 
836 DEFINE_BOOL(validate_asm, true, "validate asm.js modules before compiling")
837 DEFINE_BOOL(suppress_asm_messages, false,
838             "don't emit asm.js related messages (for golden file testing)")
839 DEFINE_BOOL(trace_asm_time, false, "log asm.js timing info to the console")
840 DEFINE_BOOL(trace_asm_scanner, false,
841             "log tokens encountered by asm.js scanner")
842 DEFINE_BOOL(trace_asm_parser, false, "verbose logging of asm.js parse failures")
843 DEFINE_BOOL(stress_validate_asm, false, "try to validate everything as asm.js")
844 
845 DEFINE_DEBUG_BOOL(dump_wasm_module, false, "dump wasm module bytes")
846 DEFINE_STRING(dump_wasm_module_path, nullptr,
847               "directory to dump wasm modules to")
848 
849 // Declare command-line flags for Wasm features. Warning: avoid using these
850 // flags directly in the implementation. Instead accept wasm::WasmFeatures
851 // for configurability.
852 #include "src/wasm/wasm-feature-flags.h"
853 
854 #define DECL_WASM_FLAG(feat, desc, val)      \
855   DEFINE_BOOL(experimental_wasm_##feat, val, \
856               "enable prototype " desc " for wasm")
857 FOREACH_WASM_FEATURE_FLAG(DECL_WASM_FLAG)
858 #undef DECL_WASM_FLAG
859 
860 DEFINE_IMPLICATION(experimental_wasm_gc, experimental_wasm_typed_funcref)
861 DEFINE_IMPLICATION(experimental_wasm_typed_funcref, experimental_wasm_reftypes)
862 
863 DEFINE_BOOL(wasm_staging, false, "enable staged wasm features")
864 
865 #define WASM_STAGING_IMPLICATION(feat, desc, val) \
866   DEFINE_IMPLICATION(wasm_staging, experimental_wasm_##feat)
867 FOREACH_WASM_STAGING_FEATURE_FLAG(WASM_STAGING_IMPLICATION)
868 #undef WASM_STAGING_IMPLICATION
869 
870 DEFINE_BOOL(wasm_opt, true, "enable wasm optimization")
871 DEFINE_BOOL(
872     wasm_bounds_checks, true,
873     "enable bounds checks (disable for performance testing only)")
874 DEFINE_BOOL(wasm_stack_checks, true,
875             "enable stack checks (disable for performance testing only)")
876 DEFINE_BOOL(wasm_math_intrinsics, true,
877             "intrinsify some Math imports into wasm")
878 
879 DEFINE_BOOL(wasm_trap_handler, true,
880             "use signal handlers to catch out of bounds memory access in wasm"
881             " (currently Linux x86_64 only)")
882 DEFINE_BOOL(wasm_fuzzer_gen_test, false,
883             "generate a test case when running a wasm fuzzer")
884 DEFINE_IMPLICATION(wasm_fuzzer_gen_test, single_threaded)
885 DEFINE_BOOL(print_wasm_code, false, "print WebAssembly code")
886 DEFINE_INT(print_wasm_code_function_index, -1,
887            "print WebAssembly code for function at index")
888 DEFINE_BOOL(print_wasm_stub_code, false, "print WebAssembly stub code")
889 DEFINE_BOOL(asm_wasm_lazy_compilation, false,
890             "enable lazy compilation for asm-wasm modules")
891 DEFINE_IMPLICATION(validate_asm, asm_wasm_lazy_compilation)
892 DEFINE_BOOL(wasm_lazy_compilation, false,
893             "enable lazy compilation for all wasm modules")
894 DEFINE_DEBUG_BOOL(trace_wasm_lazy_compilation, false,
895                   "trace lazy compilation of wasm functions")
896 DEFINE_BOOL(wasm_lazy_validation, false,
897             "enable lazy validation for lazily compiled wasm functions")
898 
899 DEFINE_BOOL(wasm_grow_shared_memory, true,
900             "allow growing shared WebAssembly memory objects")
901 DEFINE_BOOL(wasm_simd_post_mvp, false,
902             "allow experimental SIMD operations for prototyping that are not "
903             "included in the current proposal")
904 DEFINE_IMPLICATION(wasm_simd_post_mvp, experimental_wasm_simd)
905 
906 DEFINE_BOOL(wasm_code_gc, true, "enable garbage collection of wasm code")
907 DEFINE_BOOL(trace_wasm_code_gc, false, "trace garbage collection of wasm code")
908 DEFINE_BOOL(stress_wasm_code_gc, false,
909             "stress test garbage collection of wasm code")
910 DEFINE_INT(wasm_max_initial_code_space_reservation, 0,
911            "maximum size of the initial wasm code space reservation (in MB)")
912 
913 DEFINE_BOOL(experimental_wasm_allow_huge_modules, false,
914             "allow wasm modules bigger than 1GB, but below ~2GB")
915 
916 // Profiler flags.
917 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
918 
919 DEFINE_INT(stress_sampling_allocation_profiler, 0,
920            "Enables sampling allocation profiler with X as a sample interval")
921 
922 // Garbage collections flags.
923 DEFINE_BOOL(lazy_new_space_shrinking, false,
924             "Enables the lazy new space shrinking strategy")
925 DEFINE_SIZE_T(min_semi_space_size, 0,
926               "min size of a semi-space (in MBytes), the new space consists of "
927               "two semi-spaces")
928 DEFINE_SIZE_T(max_semi_space_size, 0,
929               "max size of a semi-space (in MBytes), the new space consists of "
930               "two semi-spaces")
931 DEFINE_INT(semi_space_growth_factor, 2, "factor by which to grow the new space")
932 DEFINE_SIZE_T(max_old_space_size, 0, "max size of the old space (in Mbytes)")
933 DEFINE_SIZE_T(
934     max_heap_size, 0,
935     "max size of the heap (in Mbytes) "
936     "both max_semi_space_size and max_old_space_size take precedence. "
937     "All three flags cannot be specified at the same time.")
938 DEFINE_SIZE_T(initial_heap_size, 0, "initial size of the heap (in Mbytes)")
939 DEFINE_BOOL(huge_max_old_generation_size, true,
940             "Increase max size of the old space to 4 GB for x64 systems with"
941             "the physical memory bigger than 16 GB")
942 DEFINE_SIZE_T(initial_old_space_size, 0, "initial old space size (in Mbytes)")
943 DEFINE_BOOL(global_gc_scheduling, true,
944             "enable GC scheduling based on global memory")
945 DEFINE_BOOL(gc_global, false, "always perform global GCs")
946 DEFINE_INT(random_gc_interval, 0,
947            "Collect garbage after random(0, X) allocations. It overrides "
948            "gc_interval.")
949 DEFINE_INT(gc_interval, -1, "garbage collect after <n> allocations")
950 DEFINE_INT(retain_maps_for_n_gc, 2,
951            "keeps maps alive for <n> old space garbage collections")
952 DEFINE_BOOL(trace_gc, false,
953             "print one trace line following each garbage collection")
954 DEFINE_BOOL(trace_gc_nvp, false,
955             "print one detailed trace line in name=value format "
956             "after each garbage collection")
957 DEFINE_BOOL(trace_gc_ignore_scavenger, false,
958             "do not print trace line after scavenger collection")
959 DEFINE_BOOL(trace_idle_notification, false,
960             "print one trace line following each idle notification")
961 DEFINE_BOOL(trace_idle_notification_verbose, false,
962             "prints the heap state used by the idle notification")
963 DEFINE_BOOL(trace_gc_verbose, false,
964             "print more details following each garbage collection")
965 DEFINE_IMPLICATION(trace_gc_verbose, trace_gc)
966 DEFINE_BOOL(trace_gc_freelists, false,
967             "prints details of each freelist before and after "
968             "each major garbage collection")
969 DEFINE_BOOL(trace_gc_freelists_verbose, false,
970             "prints details of freelists of each page before and after "
971             "each major garbage collection")
972 DEFINE_IMPLICATION(trace_gc_freelists_verbose, trace_gc_freelists)
973 DEFINE_BOOL(trace_evacuation_candidates, false,
974             "Show statistics about the pages evacuation by the compaction")
975 DEFINE_BOOL(
976     trace_allocations_origins, false,
977     "Show statistics about the origins of allocations. "
978     "Combine with --no-inline-new to track allocations from generated code")
979 
980 DEFINE_INT(trace_allocation_stack_interval, -1,
981            "print stack trace after <n> free-list allocations")
982 DEFINE_INT(trace_duplicate_threshold_kb, 0,
983            "print duplicate objects in the heap if their size is more than "
984            "given threshold")
985 DEFINE_BOOL(trace_fragmentation, false, "report fragmentation for old space")
986 DEFINE_BOOL(trace_fragmentation_verbose, false,
987             "report fragmentation for old space (detailed)")
988 DEFINE_BOOL(minor_mc_trace_fragmentation, false,
989             "trace fragmentation after marking")
990 DEFINE_BOOL(trace_evacuation, false, "report evacuation statistics")
991 DEFINE_BOOL(trace_mutator_utilization, false,
992             "print mutator utilization, allocation speed, gc speed")
993 DEFINE_BOOL(incremental_marking, true, "use incremental marking")
994 DEFINE_BOOL(incremental_marking_wrappers, true,
995             "use incremental marking for marking wrappers")
996 DEFINE_BOOL(incremental_marking_task, true, "use tasks for incremental marking")
997 DEFINE_INT(incremental_marking_soft_trigger, 0,
998            "threshold for starting incremental marking via a task in percent "
999            "of available space: limit - size")
1000 DEFINE_INT(incremental_marking_hard_trigger, 0,
1001            "threshold for starting incremental marking immediately in percent "
1002            "of available space: limit - size")
1003 DEFINE_BOOL(trace_unmapper, false, "Trace the unmapping")
1004 DEFINE_BOOL(parallel_scavenge, true, "parallel scavenge")
1005 DEFINE_BOOL(scavenge_task, true, "schedule scavenge tasks")
1006 DEFINE_INT(scavenge_task_trigger, 80,
1007            "scavenge task trigger in percent of the current heap limit")
1008 DEFINE_BOOL(scavenge_separate_stack_scanning, false,
1009             "use a separate phase for stack scanning in scavenge")
1010 DEFINE_BOOL(trace_parallel_scavenge, false, "trace parallel scavenge")
1011 DEFINE_BOOL(write_protect_code_memory, true, "write protect code memory")
1012 #if defined(V8_ATOMIC_MARKING_STATE) && defined(V8_ATOMIC_OBJECT_FIELD_WRITES)
1013 #define V8_CONCURRENT_MARKING_BOOL true
1014 #else
1015 #define V8_CONCURRENT_MARKING_BOOL false
1016 #endif
1017 DEFINE_BOOL(concurrent_marking, V8_CONCURRENT_MARKING_BOOL,
1018             "use concurrent marking")
1019 DEFINE_BOOL(concurrent_array_buffer_sweeping, true,
1020             "concurrently sweep array buffers")
1021 DEFINE_BOOL(concurrent_allocation, true, "concurrently allocate in old space")
1022 DEFINE_BOOL(stress_concurrent_allocation, false,
1023             "start background threads that allocate memory")
1024 DEFINE_BOOL(local_heaps, true, "allow heap access from background tasks")
1025 // Since the local_heaps flag is enabled by default, we defined reverse
1026 // implications to simplify disabling the flag.
1027 DEFINE_NEG_NEG_IMPLICATION(local_heaps, turbo_direct_heap_access)
1028 DEFINE_NEG_NEG_IMPLICATION(local_heaps, concurrent_inlining)
1029 DEFINE_NEG_NEG_IMPLICATION(local_heaps, concurrent_allocation)
1030 DEFINE_NEG_NEG_IMPLICATION(concurrent_allocation,
1031                            finalize_streaming_on_background)
1032 DEFINE_NEG_NEG_IMPLICATION(concurrent_allocation, stress_concurrent_allocation)
1033 DEFINE_BOOL(parallel_marking, V8_CONCURRENT_MARKING_BOOL,
1034             "use parallel marking in atomic pause")
1035 DEFINE_INT(ephemeron_fixpoint_iterations, 10,
1036            "number of fixpoint iterations it takes to switch to linear "
1037            "ephemeron algorithm")
1038 DEFINE_BOOL(trace_concurrent_marking, false, "trace concurrent marking")
1039 DEFINE_BOOL(concurrent_store_buffer, true,
1040             "use concurrent store buffer processing")
1041 DEFINE_BOOL(concurrent_sweeping, true, "use concurrent sweeping")
1042 DEFINE_BOOL(parallel_compaction, true, "use parallel compaction")
1043 DEFINE_BOOL(parallel_pointer_update, true,
1044             "use parallel pointer update during compaction")
1045 DEFINE_BOOL(detect_ineffective_gcs_near_heap_limit, true,
1046             "trigger out-of-memory failure to avoid GC storm near heap limit")
1047 DEFINE_BOOL(trace_incremental_marking, false,
1048             "trace progress of the incremental marking")
1049 DEFINE_BOOL(trace_stress_marking, false, "trace stress marking progress")
1050 DEFINE_BOOL(trace_stress_scavenge, false, "trace stress scavenge progress")
1051 DEFINE_BOOL(track_gc_object_stats, false,
1052             "track object counts and memory usage")
1053 DEFINE_BOOL(trace_gc_object_stats, false,
1054             "trace object counts and memory usage")
1055 DEFINE_BOOL(trace_zone_stats, false, "trace zone memory usage")
1056 DEFINE_GENERIC_IMPLICATION(
1057     trace_zone_stats,
1058     TracingFlags::zone_stats.store(
1059         v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1060 DEFINE_SIZE_T(
1061     zone_stats_tolerance, 1 * MB,
1062     "report a tick only when allocated zone memory changes by this amount")
1063 DEFINE_BOOL(trace_zone_type_stats, false, "trace per-type zone memory usage")
1064 DEFINE_GENERIC_IMPLICATION(
1065     trace_zone_type_stats,
1066     TracingFlags::zone_stats.store(
1067         v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1068 DEFINE_BOOL(track_retaining_path, false,
1069             "enable support for tracking retaining path")
1070 DEFINE_DEBUG_BOOL(trace_backing_store, false, "trace backing store events")
1071 DEFINE_BOOL(concurrent_array_buffer_freeing, true,
1072             "free array buffer allocations on a background thread")
1073 DEFINE_INT(gc_stats, 0, "Used by tracing internally to enable gc statistics")
1074 DEFINE_IMPLICATION(trace_gc_object_stats, track_gc_object_stats)
1075 DEFINE_GENERIC_IMPLICATION(
1076     track_gc_object_stats,
1077     TracingFlags::gc_stats.store(
1078         v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1079 DEFINE_GENERIC_IMPLICATION(
1080     trace_gc_object_stats,
1081     TracingFlags::gc_stats.store(
1082         v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1083 DEFINE_NEG_IMPLICATION(trace_gc_object_stats, incremental_marking)
1084 DEFINE_NEG_IMPLICATION(track_retaining_path, incremental_marking)
1085 DEFINE_NEG_IMPLICATION(track_retaining_path, parallel_marking)
1086 DEFINE_NEG_IMPLICATION(track_retaining_path, concurrent_marking)
1087 DEFINE_BOOL(track_detached_contexts, true,
1088             "track native contexts that are expected to be garbage collected")
1089 DEFINE_BOOL(trace_detached_contexts, false,
1090             "trace native contexts that are expected to be garbage collected")
1091 DEFINE_IMPLICATION(trace_detached_contexts, track_detached_contexts)
1092 #ifdef VERIFY_HEAP
1093 DEFINE_BOOL(verify_heap, false, "verify heap pointers before and after GC")
1094 DEFINE_BOOL(verify_heap_skip_remembered_set, false,
1095             "disable remembered set verification")
1096 #endif
1097 DEFINE_BOOL(move_object_start, true, "enable moving of object starts")
1098 DEFINE_BOOL(memory_reducer, true, "use memory reducer")
1099 DEFINE_BOOL(memory_reducer_for_small_heaps, true,
1100             "use memory reducer for small heaps")
1101 DEFINE_INT(heap_growing_percent, 0,
1102            "specifies heap growing factor as (1 + heap_growing_percent/100)")
1103 DEFINE_INT(v8_os_page_size, 0, "override OS page size (in KBytes)")
1104 DEFINE_BOOL(always_compact, false, "Perform compaction on every full GC")
1105 DEFINE_BOOL(never_compact, false,
1106             "Never perform compaction on full GC - testing only")
1107 DEFINE_BOOL(compact_code_space, true, "Compact code space on full collections")
1108 DEFINE_BOOL(flush_bytecode, true,
1109             "flush of bytecode when it has not been executed recently")
1110 DEFINE_BOOL(stress_flush_bytecode, false, "stress bytecode flushing")
1111 DEFINE_BOOL(trace_flush_bytecode, false, "trace bytecode flushing")
1112 DEFINE_IMPLICATION(stress_flush_bytecode, flush_bytecode)
1113 DEFINE_BOOL(use_marking_progress_bar, true,
1114             "Use a progress bar to scan large objects in increments when "
1115             "incremental marking is active.")
1116 DEFINE_BOOL(stress_per_context_marking_worklist, false,
1117             "Use per-context worklist for marking")
1118 DEFINE_BOOL(force_marking_deque_overflows, false,
1119             "force overflows of marking deque by reducing it's size "
1120             "to 64 words")
1121 DEFINE_BOOL(stress_compaction, false,
1122             "stress the GC compactor to flush out bugs (implies "
1123             "--force_marking_deque_overflows)")
1124 DEFINE_BOOL(stress_compaction_random, false,
1125             "Stress GC compaction by selecting random percent of pages as "
1126             "evacuation candidates. It overrides stress_compaction.")
1127 DEFINE_BOOL(stress_incremental_marking, false,
1128             "force incremental marking for small heaps and run it more often")
1129 
1130 DEFINE_BOOL(fuzzer_gc_analysis, false,
1131             "prints number of allocations and enables analysis mode for gc "
1132             "fuzz testing, e.g. --stress-marking, --stress-scavenge")
1133 DEFINE_INT(stress_marking, 0,
1134            "force marking at random points between 0 and X (inclusive) percent "
1135            "of the regular marking start limit")
1136 DEFINE_INT(stress_scavenge, 0,
1137            "force scavenge at random points between 0 and X (inclusive) "
1138            "percent of the new space capacity")
1139 DEFINE_VALUE_IMPLICATION(fuzzer_gc_analysis, stress_marking, 99)
1140 DEFINE_VALUE_IMPLICATION(fuzzer_gc_analysis, stress_scavenge, 99)
1141 DEFINE_BOOL(
1142     reclaim_unmodified_wrappers, true,
1143     "reclaim otherwise unreachable unmodified wrapper objects when possible")
1144 
1145 // These flags will be removed after experiments. Do not rely on them.
1146 DEFINE_BOOL(gc_experiment_background_schedule, false,
1147             "new background GC schedule heuristics")
1148 DEFINE_BOOL(gc_experiment_less_compaction, false,
1149             "less compaction in non-memory reducing mode")
1150 DEFINE_BOOL(gc_experiment_reduce_concurrent_marking_tasks, false,
1151             "reduce the number of concurrent marking tasks")
1152 
1153 DEFINE_BOOL(disable_abortjs, false, "disables AbortJS runtime function")
1154 
1155 DEFINE_BOOL(randomize_all_allocations, false,
1156             "randomize virtual memory reservations by ignoring any hints "
1157             "passed when allocating pages")
1158 
1159 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
1160             "Test mode only flag. It allows an unit test to select evacuation "
1161             "candidates pages (requires --stress_compaction).")
1162 DEFINE_BOOL(fast_promotion_new_space, false,
1163             "fast promote new space on high survival rates")
1164 
1165 DEFINE_BOOL(clear_free_memory, false, "initialize free memory with 0")
1166 
1167 DEFINE_BOOL_READONLY(
1168     young_generation_large_objects, true,
1169     "allocates large objects by default in the young generation large "
1170     "object space")
1171 
1172 // assembler-ia32.cc / assembler-arm.cc / assembler-arm64.cc / assembler-x64.cc
1173 DEFINE_BOOL(debug_code, DEBUG_BOOL,
1174             "generate extra code (assertions) for debugging")
1175 DEFINE_BOOL(code_comments, false,
1176             "emit comments in code disassembly; for more readable source "
1177             "positions you should add --no-concurrent_recompilation")
1178 DEFINE_BOOL(enable_sse3, true, "enable use of SSE3 instructions if available")
1179 DEFINE_BOOL(enable_ssse3, true, "enable use of SSSE3 instructions if available")
1180 DEFINE_BOOL(enable_sse4_1, true,
1181             "enable use of SSE4.1 instructions if available")
1182 DEFINE_BOOL(enable_sse4_2, true,
1183             "enable use of SSE4.2 instructions if available")
1184 DEFINE_BOOL(enable_sahf, true,
1185             "enable use of SAHF instruction if available (X64 only)")
1186 DEFINE_BOOL(enable_avx, true, "enable use of AVX instructions if available")
1187 DEFINE_BOOL(enable_fma3, true, "enable use of FMA3 instructions if available")
1188 DEFINE_BOOL(enable_bmi1, true, "enable use of BMI1 instructions if available")
1189 DEFINE_BOOL(enable_bmi2, true, "enable use of BMI2 instructions if available")
1190 DEFINE_BOOL(enable_lzcnt, true, "enable use of LZCNT instruction if available")
1191 DEFINE_BOOL(enable_popcnt, true,
1192             "enable use of POPCNT instruction if available")
1193 DEFINE_STRING(arm_arch, ARM_ARCH_DEFAULT,
1194               "generate instructions for the selected ARM architecture if "
1195               "available: armv6, armv7, armv7+sudiv or armv8")
1196 DEFINE_BOOL(force_long_branches, false,
1197             "force all emitted branches to be in long mode (MIPS/PPC only)")
1198 DEFINE_STRING(mcpu, "auto", "enable optimization for specific cpu")
1199 DEFINE_BOOL(partial_constant_pool, true,
1200             "enable use of partial constant pools (X64 only)")
1201 DEFINE_STRING(sim_arm64_optional_features, "none",
1202               "enable optional features on the simulator for testing: none or "
1203               "all")
1204 
1205 // Controlling source positions for Torque/CSA code.
1206 DEFINE_BOOL(enable_source_at_csa_bind, false,
1207             "Include source information in the binary at CSA bind locations.")
1208 
1209 // Deprecated ARM flags (replaced by arm_arch).
1210 DEFINE_MAYBE_BOOL(enable_armv7, "deprecated (use --arm_arch instead)")
1211 DEFINE_MAYBE_BOOL(enable_vfp3, "deprecated (use --arm_arch instead)")
1212 DEFINE_MAYBE_BOOL(enable_32dregs, "deprecated (use --arm_arch instead)")
1213 DEFINE_MAYBE_BOOL(enable_neon, "deprecated (use --arm_arch instead)")
1214 DEFINE_MAYBE_BOOL(enable_sudiv, "deprecated (use --arm_arch instead)")
1215 DEFINE_MAYBE_BOOL(enable_armv8, "deprecated (use --arm_arch instead)")
1216 
1217 // regexp-macro-assembler-*.cc
1218 DEFINE_BOOL(enable_regexp_unaligned_accesses, true,
1219             "enable unaligned accesses for the regexp engine")
1220 
1221 // api.cc
1222 DEFINE_BOOL(script_streaming, true, "enable parsing on background")
1223 DEFINE_BOOL(stress_background_compile, false,
1224             "stress test parsing on background")
1225 DEFINE_BOOL(
1226     finalize_streaming_on_background, false,
1227     "perform the script streaming finalization on the background thread")
1228 DEFINE_BOOL(disable_old_api_accessors, false,
1229             "Disable old-style API accessors whose setters trigger through the "
1230             "prototype chain")
1231 
1232 // bootstrapper.cc
1233 DEFINE_BOOL(expose_gc, false, "expose gc extension")
1234 DEFINE_STRING(expose_gc_as, nullptr,
1235               "expose gc extension under the specified name")
1236 DEFINE_IMPLICATION(expose_gc_as, expose_gc)
1237 DEFINE_BOOL(expose_externalize_string, false,
1238             "expose externalize string extension")
1239 DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
1240 DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
1241 DEFINE_BOOL(builtins_in_stack_traces, false,
1242             "show built-in functions in stack traces")
1243 DEFINE_BOOL(experimental_stack_trace_frames, false,
1244             "enable experimental frames (API/Builtins) and stack trace layout")
1245 DEFINE_BOOL(disallow_code_generation_from_strings, false,
1246             "disallow eval and friends")
1247 DEFINE_BOOL(expose_async_hooks, false, "expose async_hooks object")
1248 DEFINE_STRING(expose_cputracemark_as, nullptr,
1249               "expose cputracemark extension under the specified name")
1250 #ifdef ENABLE_VTUNE_TRACEMARK
1251 DEFINE_BOOL(enable_vtune_domain_support, true, "enable vtune domain support")
1252 #endif  // ENABLE_VTUNE_TRACEMARK
1253 
1254 // builtins.cc
1255 DEFINE_BOOL(allow_unsafe_function_constructor, false,
1256             "allow invoking the function constructor without security checks")
1257 DEFINE_BOOL(force_slow_path, false, "always take the slow path for builtins")
1258 DEFINE_BOOL(test_small_max_function_context_stub_size, false,
1259             "enable testing the function context size overflow path "
1260             "by making the maximum size smaller")
1261 
1262 DEFINE_BOOL(inline_new, true, "use fast inline allocation")
1263 DEFINE_NEG_NEG_IMPLICATION(inline_new, turbo_allocation_folding)
1264 
1265 // codegen-ia32.cc / codegen-arm.cc
1266 DEFINE_BOOL(trace, false, "trace javascript function calls")
1267 DEFINE_BOOL(trace_wasm, false, "trace wasm function calls")
1268 
1269 // codegen.cc
1270 DEFINE_BOOL(lazy, true, "use lazy compilation")
1271 DEFINE_BOOL(max_lazy, false, "ignore eager compilation hints")
1272 DEFINE_IMPLICATION(max_lazy, lazy)
1273 DEFINE_BOOL(trace_opt, false, "trace optimized compilation")
1274 DEFINE_BOOL(trace_opt_verbose, false,
1275             "extra verbose optimized compilation tracing")
1276 DEFINE_IMPLICATION(trace_opt_verbose, trace_opt)
1277 DEFINE_BOOL(trace_opt_stats, false, "trace optimized compilation statistics")
1278 DEFINE_BOOL(trace_deopt, false, "trace deoptimization")
1279 DEFINE_BOOL(trace_deopt_verbose, false, "extra verbose deoptimization tracing")
1280 DEFINE_IMPLICATION(trace_deopt_verbose, trace_deopt)
1281 DEFINE_BOOL(trace_file_names, false,
1282             "include file names in trace-opt/trace-deopt output")
1283 DEFINE_BOOL(always_opt, false, "always try to optimize functions")
1284 DEFINE_BOOL(always_osr, false, "always try to OSR functions")
1285 DEFINE_BOOL(prepare_always_opt, false, "prepare for turning on always opt")
1286 
1287 DEFINE_BOOL(trace_serializer, false, "print code serializer trace")
1288 #ifdef DEBUG
1289 DEFINE_BOOL(external_reference_stats, false,
1290             "print statistics on external references used during serialization")
1291 #endif  // DEBUG
1292 
1293 // compilation-cache.cc
1294 DEFINE_BOOL(compilation_cache, true, "enable compilation cache")
1295 
1296 DEFINE_BOOL(cache_prototype_transitions, true, "cache prototype transitions")
1297 
1298 // compiler-dispatcher.cc
1299 DEFINE_BOOL(parallel_compile_tasks, false, "enable parallel compile tasks")
1300 DEFINE_BOOL(compiler_dispatcher, false, "enable compiler dispatcher")
1301 DEFINE_IMPLICATION(parallel_compile_tasks, compiler_dispatcher)
1302 DEFINE_BOOL(trace_compiler_dispatcher, false,
1303             "trace compiler dispatcher activity")
1304 
1305 // cpu-profiler.cc
1306 DEFINE_INT(cpu_profiler_sampling_interval, 1000,
1307            "CPU profiler sampling interval in microseconds")
1308 
1309 // debugger
1310 DEFINE_BOOL(
1311     trace_side_effect_free_debug_evaluate, false,
1312     "print debug messages for side-effect-free debug-evaluate for testing")
1313 DEFINE_BOOL(hard_abort, true, "abort by crashing")
1314 
1315 // inspector
1316 DEFINE_BOOL(expose_inspector_scripts, false,
1317             "expose injected-script-source.js for debugging")
1318 
1319 // execution.cc
1320 DEFINE_INT(stack_size, V8_DEFAULT_STACK_SIZE_KB,
1321            "default size of stack region v8 is allowed to use (in kBytes)")
1322 
1323 // frames.cc
1324 DEFINE_INT(max_stack_trace_source_length, 300,
1325            "maximum length of function source code printed in a stack trace.")
1326 
1327 // execution.cc, messages.cc
1328 DEFINE_BOOL(clear_exceptions_on_js_entry, false,
1329             "clear pending exceptions when entering JavaScript")
1330 
1331 // counters.cc
1332 DEFINE_INT(histogram_interval, 600000,
1333            "time interval in ms for aggregating memory histograms")
1334 
1335 // heap-snapshot-generator.cc
1336 DEFINE_BOOL(heap_profiler_trace_objects, false,
1337             "Dump heap object allocations/movements/size_updates")
1338 DEFINE_BOOL(heap_profiler_use_embedder_graph, true,
1339             "Use the new EmbedderGraph API to get embedder nodes")
1340 DEFINE_INT(heap_snapshot_string_limit, 1024,
1341            "truncate strings to this length in the heap snapshot")
1342 
1343 // sampling-heap-profiler.cc
1344 DEFINE_BOOL(sampling_heap_profiler_suppress_randomness, false,
1345             "Use constant sample intervals to eliminate test flakiness")
1346 
1347 // v8.cc
1348 DEFINE_BOOL(use_idle_notification, true,
1349             "Use idle notification to reduce memory footprint.")
1350 // ic.cc
1351 DEFINE_BOOL(trace_ic, false,
1352             "trace inline cache state transitions for tools/ic-processor")
1353 DEFINE_IMPLICATION(trace_ic, log_code)
1354 DEFINE_GENERIC_IMPLICATION(
1355     trace_ic, TracingFlags::ic_stats.store(
1356                   v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1357 DEFINE_BOOL_READONLY(fast_map_update, false,
1358                      "enable fast map update by caching the migration target")
1359 DEFINE_BOOL(modify_field_representation_inplace, true,
1360             "enable in-place field representation updates")
1361 DEFINE_INT(max_valid_polymorphic_map_count, 4,
1362            "maximum number of valid maps to track in POLYMORPHIC state")
1363 
1364 DEFINE_BOOL(native_code_counters, DEBUG_BOOL,
1365             "generate extra code for manipulating stats counters")
1366 
1367 DEFINE_BOOL(super_ic, false, "use an IC for super property loads")
1368 
1369 // objects.cc
1370 DEFINE_BOOL(thin_strings, true, "Enable ThinString support")
1371 DEFINE_BOOL(trace_prototype_users, false,
1372             "Trace updates to prototype user tracking")
1373 DEFINE_BOOL(trace_for_in_enumerate, false, "Trace for-in enumerate slow-paths")
1374 DEFINE_BOOL(trace_maps, false, "trace map creation")
1375 DEFINE_BOOL(trace_maps_details, true, "also log map details")
1376 DEFINE_IMPLICATION(trace_maps, log_code)
1377 
1378 // parser.cc
1379 DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
1380 DEFINE_BOOL(allow_natives_for_differential_fuzzing, false,
1381             "allow only natives explicitly allowlisted for differential "
1382             "fuzzers")
1383 DEFINE_IMPLICATION(allow_natives_for_differential_fuzzing, allow_natives_syntax)
1384 DEFINE_IMPLICATION(allow_natives_for_differential_fuzzing, fuzzing)
1385 DEFINE_BOOL(parse_only, false, "only parse the sources")
1386 
1387 // simulator-arm.cc, simulator-arm64.cc and simulator-mips.cc
1388 DEFINE_BOOL(trace_sim, false, "Trace simulator execution")
1389 DEFINE_BOOL(debug_sim, false, "Enable debugging the simulator")
1390 DEFINE_BOOL(check_icache, false,
1391             "Check icache flushes in ARM and MIPS simulator")
1392 DEFINE_INT(stop_sim_at, 0, "Simulator stop after x number of instructions")
1393 #if defined(V8_TARGET_ARCH_ARM64) || defined(V8_TARGET_ARCH_MIPS64) || \
1394     defined(V8_TARGET_ARCH_PPC64)
1395 DEFINE_INT(sim_stack_alignment, 16,
1396            "Stack alignment in bytes in simulator. This must be a power of two "
1397            "and it must be at least 16. 16 is default.")
1398 #else
1399 DEFINE_INT(sim_stack_alignment, 8,
1400            "Stack alingment in bytes in simulator (4 or 8, 8 is default)")
1401 #endif
1402 DEFINE_INT(sim_stack_size, 2 * MB / KB,
1403            "Stack size of the ARM64, MIPS, MIPS64 and PPC64 simulator "
1404            "in kBytes (default is 2 MB)")
1405 DEFINE_BOOL(log_colour, ENABLE_LOG_COLOUR,
1406             "When logging, try to use coloured output.")
1407 DEFINE_BOOL(trace_sim_messages, false,
1408             "Trace simulator debug messages. Implied by --trace-sim.")
1409 
1410 #if defined V8_TARGET_ARCH_ARM64
1411 // pointer-auth-arm64.cc
1412 DEFINE_DEBUG_BOOL(sim_abort_on_bad_auth, false,
1413                   "Stop execution when a pointer authentication fails in the "
1414                   "ARM64 simulator.")
1415 #endif
1416 
1417 // isolate.cc
1418 DEFINE_BOOL(async_stack_traces, true,
1419             "include async stack traces in Error.stack")
1420 DEFINE_BOOL(stack_trace_on_illegal, false,
1421             "print stack trace when an illegal exception is thrown")
1422 DEFINE_BOOL(abort_on_uncaught_exception, false,
1423             "abort program (dump core) when an uncaught exception is thrown")
1424 DEFINE_BOOL(correctness_fuzzer_suppressions, false,
1425             "Suppress certain unspecified behaviors to ease correctness "
1426             "fuzzing: Abort program when the stack overflows or a string "
1427             "exceeds maximum length (as opposed to throwing RangeError). "
1428             "Use a fixed suppression string for error messages.")
1429 DEFINE_BOOL(randomize_hashes, true,
1430             "randomize hashes to avoid predictable hash collisions "
1431             "(with snapshots this option cannot override the baked-in seed)")
1432 DEFINE_BOOL(rehash_snapshot, true,
1433             "rehash strings from the snapshot to override the baked-in seed")
1434 DEFINE_UINT64(hash_seed, 0,
1435               "Fixed seed to use to hash property keys (0 means random)"
1436               "(with snapshots this option cannot override the baked-in seed)")
1437 DEFINE_INT(random_seed, 0,
1438            "Default seed for initializing random generator "
1439            "(0, the default, means to use system random).")
1440 DEFINE_INT(fuzzer_random_seed, 0,
1441            "Default seed for initializing fuzzer random generator "
1442            "(0, the default, means to use v8's random number generator seed).")
1443 DEFINE_BOOL(trace_rail, false, "trace RAIL mode")
1444 DEFINE_BOOL(print_all_exceptions, false,
1445             "print exception object and stack trace on each thrown exception")
1446 DEFINE_BOOL(
1447     detailed_error_stack_trace, false,
1448     "includes arguments for each function call in the error stack frames array")
1449 DEFINE_BOOL(adjust_os_scheduling_parameters, true,
1450             "adjust OS specific scheduling params for the isolate")
1451 DEFINE_BOOL(experimental_flush_embedded_blob_icache, false,
1452             "Used in an experiment to evaluate icache flushing on certain CPUs")
1453 
1454 // runtime.cc
1455 DEFINE_BOOL(runtime_call_stats, false, "report runtime call counts and times")
1456 DEFINE_GENERIC_IMPLICATION(
1457     runtime_call_stats,
1458     TracingFlags::runtime_stats.store(
1459         v8::tracing::TracingCategoryObserver::ENABLED_BY_NATIVE))
1460 DEFINE_BOOL(rcs, false, "report runtime call counts and times")
1461 DEFINE_IMPLICATION(rcs, runtime_call_stats)
1462 
1463 DEFINE_BOOL(rcs_cpu_time, false,
1464             "report runtime times in cpu time (the default is wall time)")
1465 DEFINE_IMPLICATION(rcs_cpu_time, rcs)
1466 
1467 // snapshot-common.cc
1468 DEFINE_BOOL(profile_deserialization, false,
1469             "Print the time it takes to deserialize the snapshot.")
1470 DEFINE_BOOL(serialization_statistics, false,
1471             "Collect statistics on serialized objects.")
1472 // Regexp
1473 DEFINE_BOOL(regexp_optimization, true, "generate optimized regexp code")
1474 DEFINE_BOOL(regexp_mode_modifiers, false, "enable inline flags in regexp.")
1475 DEFINE_BOOL(regexp_interpret_all, false, "interpret all regexp code")
1476 #ifdef V8_TARGET_BIG_ENDIAN
1477 #define REGEXP_PEEPHOLE_OPTIMIZATION_BOOL false
1478 #else
1479 #define REGEXP_PEEPHOLE_OPTIMIZATION_BOOL true
1480 #endif
1481 DEFINE_BOOL(regexp_tier_up, true,
1482             "enable regexp interpreter and tier up to the compiler after the "
1483             "number of executions set by the tier up ticks flag")
1484 DEFINE_INT(regexp_tier_up_ticks, 1,
1485            "set the number of executions for the regexp interpreter before "
1486            "tiering-up to the compiler")
1487 DEFINE_BOOL(regexp_peephole_optimization, REGEXP_PEEPHOLE_OPTIMIZATION_BOOL,
1488             "enable peephole optimization for regexp bytecode")
1489 DEFINE_BOOL(trace_regexp_peephole_optimization, false,
1490             "trace regexp bytecode peephole optimization")
1491 DEFINE_BOOL(trace_regexp_bytecodes, false, "trace regexp bytecode execution")
1492 DEFINE_BOOL(trace_regexp_assembler, false,
1493             "trace regexp macro assembler calls.")
1494 DEFINE_BOOL(trace_regexp_parser, false, "trace regexp parsing")
1495 DEFINE_BOOL(trace_regexp_tier_up, false, "trace regexp tiering up execution")
1496 
1497 DEFINE_BOOL(enable_experimental_regexp_engine, false,
1498             "recognize regexps with 'l' flag, run them on experimental engine")
1499 DEFINE_BOOL(default_to_experimental_regexp_engine, false,
1500             "run regexps with the experimental engine where possible")
1501 DEFINE_IMPLICATION(default_to_experimental_regexp_engine,
1502                    enable_experimental_regexp_engine)
1503 DEFINE_BOOL(trace_experimental_regexp_engine, false,
1504             "trace execution of experimental regexp engine")
1505 
1506 DEFINE_BOOL(enable_experimental_regexp_engine_on_excessive_backtracks, false,
1507             "fall back to a breadth-first regexp engine on excessive "
1508             "backtracking")
1509 DEFINE_UINT(regexp_backtracks_before_fallback, 50000,
1510             "number of backtracks during regexp execution before fall back "
1511             "to experimental engine if "
1512             "enable_experimental_regexp_engine_on_excessive_backtracks is set")
1513 
1514 // Testing flags test/cctest/test-{flags,api,serialization}.cc
1515 DEFINE_BOOL(testing_bool_flag, true, "testing_bool_flag")
1516 DEFINE_MAYBE_BOOL(testing_maybe_bool_flag, "testing_maybe_bool_flag")
1517 DEFINE_INT(testing_int_flag, 13, "testing_int_flag")
1518 DEFINE_FLOAT(testing_float_flag, 2.5, "float-flag")
1519 DEFINE_STRING(testing_string_flag, "Hello, world!", "string-flag")
1520 DEFINE_INT(testing_prng_seed, 42, "Seed used for threading test randomness")
1521 
1522 // Test flag for a check in %OptimizeFunctionOnNextCall
1523 DEFINE_BOOL(
1524     testing_d8_test_runner, false,
1525     "test runner turns on this flag to enable a check that the function was "
1526     "prepared for optimization before marking it for optimization")
1527 
1528 DEFINE_BOOL(
1529     fuzzing, false,
1530     "Fuzzers use this flag to signal that they are ... fuzzing. This causes "
1531     "intrinsics to fail silently (e.g. return undefined) on invalid usage.")
1532 
1533 // mksnapshot.cc
1534 DEFINE_STRING(embedded_src, nullptr,
1535               "Path for the generated embedded data file. (mksnapshot only)")
1536 DEFINE_STRING(
1537     embedded_variant, nullptr,
1538     "Label to disambiguate symbols in embedded data file. (mksnapshot only)")
1539 DEFINE_STRING(startup_src, nullptr,
1540               "Write V8 startup as C++ src. (mksnapshot only)")
1541 DEFINE_STRING(startup_blob, nullptr,
1542               "Write V8 startup blob file. (mksnapshot only)")
1543 DEFINE_STRING(target_arch, nullptr,
1544               "The mksnapshot target arch. (mksnapshot only)")
1545 DEFINE_STRING(target_os, nullptr, "The mksnapshot target os. (mksnapshot only)")
1546 DEFINE_BOOL(target_is_simulator, false,
1547             "Instruct mksnapshot that the target is meant to run in the "
1548             "simulator and it can generate simulator-specific instructions. "
1549             "(mksnapshot only)")
1550 DEFINE_STRING(turbo_profiling_log_file, nullptr,
1551               "Path of the input file containing basic block counters for "
1552               "builtins. (mksnapshot only)")
1553 
1554 // On some platforms, the .text section only has execute permissions.
1555 DEFINE_BOOL(text_is_readable, true,
1556             "Whether the .text section of binary can be read")
1557 DEFINE_NEG_NEG_IMPLICATION(text_is_readable, partial_constant_pool)
1558 
1559 //
1560 // Minor mark compact collector flags.
1561 //
1562 #ifdef ENABLE_MINOR_MC
1563 DEFINE_BOOL(minor_mc_parallel_marking, true,
1564             "use parallel marking for the young generation")
1565 DEFINE_BOOL(trace_minor_mc_parallel_marking, false,
1566             "trace parallel marking for the young generation")
1567 DEFINE_BOOL(minor_mc, false, "perform young generation mark compact GCs")
1568 #else
1569 DEFINE_BOOL_READONLY(minor_mc, false,
1570                      "perform young generation mark compact GCs")
1571 #endif  // ENABLE_MINOR_MC
1572 
1573 //
1574 // Dev shell flags
1575 //
1576 
1577 DEFINE_BOOL(help, false, "Print usage message, including flags, on console")
1578 DEFINE_BOOL(dump_counters, false, "Dump counters on exit")
1579 DEFINE_BOOL(dump_counters_nvp, false,
1580             "Dump counters as name-value pairs on exit")
1581 DEFINE_BOOL(use_external_strings, false, "Use external strings for source code")
1582 DEFINE_STRING(map_counters, "", "Map counters to a file")
1583 DEFINE_BOOL(mock_arraybuffer_allocator, false,
1584             "Use a mock ArrayBuffer allocator for testing.")
1585 DEFINE_SIZE_T(mock_arraybuffer_allocator_limit, 0,
1586               "Memory limit for mock ArrayBuffer allocator used to simulate "
1587               "OOM for testing.")
1588 #if V8_OS_LINUX
1589 DEFINE_BOOL(multi_mapped_mock_allocator, false,
1590             "Use a multi-mapped mock ArrayBuffer allocator for testing.")
1591 #endif
1592 
1593 // Flags for Wasm GDB remote debugging.
1594 #ifdef V8_ENABLE_WASM_GDB_REMOTE_DEBUGGING
1595 #define DEFAULT_WASM_GDB_REMOTE_PORT 8765
1596 DEFINE_BOOL(wasm_gdb_remote, false,
1597             "enable GDB-remote for WebAssembly debugging")
1598 DEFINE_NEG_IMPLICATION(wasm_gdb_remote, wasm_tier_up)
1599 DEFINE_INT(wasm_gdb_remote_port, DEFAULT_WASM_GDB_REMOTE_PORT,
1600            "default port for WebAssembly debugging with LLDB.")
1601 DEFINE_BOOL(wasm_pause_waiting_for_debugger, false,
1602             "pause at the first Webassembly instruction waiting for a debugger "
1603             "to attach")
1604 #endif  // V8_ENABLE_WASM_GDB_REMOTE_DEBUGGING
1605 
1606 //
1607 // GDB JIT integration flags.
1608 //
1609 #undef FLAG
1610 #ifdef ENABLE_GDB_JIT_INTERFACE
1611 #define FLAG FLAG_FULL
1612 #else
1613 #define FLAG FLAG_READONLY
1614 #endif
1615 
1616 DEFINE_BOOL(gdbjit, false, "enable GDBJIT interface")
1617 DEFINE_BOOL(gdbjit_full, false, "enable GDBJIT interface for all code objects")
1618 DEFINE_BOOL(gdbjit_dump, false, "dump elf objects with debug info to disk")
1619 DEFINE_STRING(gdbjit_dump_filter, "",
1620               "dump only objects containing this substring")
1621 
1622 #ifdef ENABLE_GDB_JIT_INTERFACE
1623 DEFINE_IMPLICATION(gdbjit_full, gdbjit)
1624 DEFINE_IMPLICATION(gdbjit_dump, gdbjit)
1625 #endif
1626 DEFINE_NEG_IMPLICATION(gdbjit, compact_code_space)
1627 
1628 //
1629 // Debug only flags
1630 //
1631 #undef FLAG
1632 #ifdef DEBUG
1633 #define FLAG FLAG_FULL
1634 #else
1635 #define FLAG FLAG_READONLY
1636 #endif
1637 
1638 // checks.cc
1639 #ifdef ENABLE_SLOW_DCHECKS
1640 DEFINE_BOOL(enable_slow_asserts, true,
1641             "enable asserts that are slow to execute")
1642 #endif
1643 
1644 // codegen-ia32.cc / codegen-arm.cc / macro-assembler-*.cc
1645 DEFINE_BOOL(print_ast, false, "print source AST")
1646 DEFINE_BOOL(trap_on_abort, false, "replace aborts by breakpoints")
1647 
1648 // compiler.cc
1649 DEFINE_BOOL(print_scopes, false, "print scopes")
1650 
1651 // contexts.cc
1652 DEFINE_BOOL(trace_contexts, false, "trace contexts operations")
1653 
1654 // heap.cc
1655 DEFINE_BOOL(gc_verbose, false, "print stuff during garbage collection")
1656 DEFINE_BOOL(code_stats, false, "report code statistics after GC")
1657 DEFINE_BOOL(print_handles, false, "report handles after GC")
1658 DEFINE_BOOL(check_handle_count, false,
1659             "Check that there are not too many handles at GC")
1660 DEFINE_BOOL(print_global_handles, false, "report global handles after GC")
1661 
1662 // TurboFan debug-only flags.
1663 DEFINE_BOOL(trace_turbo_escape, false, "enable tracing in escape analysis")
1664 
1665 // objects.cc
1666 DEFINE_BOOL(trace_module_status, false,
1667             "Trace status transitions of ECMAScript modules")
1668 DEFINE_BOOL(trace_normalization, false,
1669             "prints when objects are turned into dictionaries.")
1670 
1671 // runtime.cc
1672 DEFINE_BOOL(trace_lazy, false, "trace lazy compilation")
1673 
1674 // spaces.cc
1675 DEFINE_BOOL(collect_heap_spill_statistics, false,
1676             "report heap spill statistics along with heap_stats "
1677             "(requires heap_stats)")
1678 DEFINE_BOOL(trace_isolates, false, "trace isolate state changes")
1679 
1680 // Regexp
1681 DEFINE_BOOL(regexp_possessive_quantifier, false,
1682             "enable possessive quantifier syntax for testing")
1683 
1684 // Debugger
1685 DEFINE_BOOL(print_break_location, false, "print source location on debug break")
1686 
1687 // wasm instance management
1688 DEFINE_DEBUG_BOOL(trace_wasm_instances, false,
1689                   "trace creation and collection of wasm instances")
1690 
1691 #ifdef V8_ENABLE_WASM_GDB_REMOTE_DEBUGGING
1692 DEFINE_BOOL(trace_wasm_gdb_remote, false, "trace Webassembly GDB-remote server")
1693 #endif  // V8_ENABLE_WASM_GDB_REMOTE_DEBUGGING
1694 
1695 //
1696 // Logging and profiling flags
1697 //
1698 #undef FLAG
1699 #define FLAG FLAG_FULL
1700 
1701 // log.cc
1702 DEFINE_STRING(logfile, "v8.log",
1703               "Specify the name of the log file, use '-' for console, '+' for "
1704               "a temporary file.")
1705 DEFINE_BOOL(logfile_per_isolate, true, "Separate log files for each isolate.")
1706 
1707 DEFINE_BOOL(log, false,
1708             "Minimal logging (no API, code, GC, suspect, or handles samples).")
1709 DEFINE_BOOL(log_all, false, "Log all events to the log file.")
1710 DEFINE_BOOL(log_api, false, "Log API events to the log file.")
1711 DEFINE_BOOL(log_code, false,
1712             "Log code events to the log file without profiling.")
1713 DEFINE_BOOL(log_handles, false, "Log global handle events.")
1714 DEFINE_BOOL(log_suspect, false, "Log suspect operations.")
1715 DEFINE_BOOL(log_source_code, false, "Log source code.")
1716 DEFINE_BOOL(log_function_events, false,
1717             "Log function events "
1718             "(parse, compile, execute) separately.")
1719 
1720 DEFINE_IMPLICATION(log_all, log_api)
1721 DEFINE_IMPLICATION(log_all, log_code)
1722 DEFINE_IMPLICATION(log_all, log_suspect)
1723 DEFINE_IMPLICATION(log_all, log_handles)
1724 DEFINE_IMPLICATION(log_all, log_internal_timer_events)
1725 DEFINE_IMPLICATION(log_all, log_function_events)
1726 
1727 DEFINE_BOOL(detailed_line_info, false,
1728             "Always generate detailed line information for CPU profiling.")
1729 
1730 #if defined(ANDROID)
1731 // Phones and tablets have processors that are much slower than desktop
1732 // and laptop computers for which current heuristics are tuned.
1733 #define DEFAULT_PROF_SAMPLING_INTERVAL 5000
1734 #else
1735 #define DEFAULT_PROF_SAMPLING_INTERVAL 1000
1736 #endif
1737 DEFINE_INT(prof_sampling_interval, DEFAULT_PROF_SAMPLING_INTERVAL,
1738            "Interval for --prof samples (in microseconds).")
1739 #undef DEFAULT_PROF_SAMPLING_INTERVAL
1740 
1741 DEFINE_BOOL(prof_cpp, false, "Like --prof, but ignore generated code.")
1742 DEFINE_BOOL(prof_browser_mode, true,
1743             "Used with --prof, turns on browser-compatible mode for profiling.")
1744 
1745 DEFINE_BOOL(prof, false,
1746             "Log statistical profiling information (implies --log-code).")
1747 DEFINE_IMPLICATION(prof, prof_cpp)
1748 DEFINE_IMPLICATION(prof, log_code)
1749 
1750 DEFINE_BOOL(ll_prof, false, "Enable low-level linux profiler.")
1751 
1752 #if V8_OS_LINUX
1753 #define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL(nam, false, cmt)
1754 #define DEFINE_PERF_PROF_IMPLICATION DEFINE_IMPLICATION
1755 #else
1756 #define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL_READONLY(nam, false, cmt)
1757 #define DEFINE_PERF_PROF_IMPLICATION(...)
1758 #endif
1759 
1760 DEFINE_PERF_PROF_BOOL(perf_basic_prof,
1761                       "Enable perf linux profiler (basic support).")
1762 DEFINE_NEG_IMPLICATION(perf_basic_prof, compact_code_space)
1763 DEFINE_PERF_PROF_BOOL(
1764     perf_basic_prof_only_functions,
1765     "Only report function code ranges to perf (i.e. no stubs).")
1766 DEFINE_PERF_PROF_IMPLICATION(perf_basic_prof_only_functions, perf_basic_prof)
1767 DEFINE_PERF_PROF_BOOL(
1768     perf_prof, "Enable perf linux profiler (experimental annotate support).")
1769 DEFINE_PERF_PROF_BOOL(
1770     perf_prof_annotate_wasm,
1771     "Used with --perf-prof, load wasm source map and provide annotate "
1772     "support (experimental).")
1773 DEFINE_PERF_PROF_BOOL(
1774     perf_prof_delete_file,
1775     "Remove the perf file right after creating it (for testing only).")
1776 DEFINE_NEG_IMPLICATION(perf_prof, compact_code_space)
1777 // TODO(v8:8462) Remove implication once perf supports remapping.
1778 DEFINE_NEG_IMPLICATION(perf_prof, write_protect_code_memory)
1779 DEFINE_NEG_IMPLICATION(perf_prof, wasm_write_protect_code_memory)
1780 
1781 // --perf-prof-unwinding-info is available only on selected architectures.
1782 #if !V8_TARGET_ARCH_ARM && !V8_TARGET_ARCH_ARM64 && !V8_TARGET_ARCH_X64 && \
1783     !V8_TARGET_ARCH_S390X && !V8_TARGET_ARCH_PPC64
1784 #undef DEFINE_PERF_PROF_BOOL
1785 #define DEFINE_PERF_PROF_BOOL(nam, cmt) DEFINE_BOOL_READONLY(nam, false, cmt)
1786 #undef DEFINE_PERF_PROF_IMPLICATION
1787 #define DEFINE_PERF_PROF_IMPLICATION(...)
1788 #endif
1789 
1790 DEFINE_PERF_PROF_BOOL(
1791     perf_prof_unwinding_info,
1792     "Enable unwinding info for perf linux profiler (experimental).")
1793 DEFINE_PERF_PROF_IMPLICATION(perf_prof, perf_prof_unwinding_info)
1794 
1795 #undef DEFINE_PERF_PROF_BOOL
1796 #undef DEFINE_PERF_PROF_IMPLICATION
1797 
1798 DEFINE_STRING(gc_fake_mmap, "/tmp/__v8_gc__",
1799               "Specify the name of the file for fake gc mmap used in ll_prof")
1800 DEFINE_BOOL(log_internal_timer_events, false, "Time internal events.")
1801 DEFINE_IMPLICATION(log_internal_timer_events, prof)
1802 
1803 DEFINE_BOOL(redirect_code_traces, false,
1804             "output deopt information and disassembly into file "
1805             "code-<pid>-<isolate id>.asm")
1806 DEFINE_STRING(redirect_code_traces_to, nullptr,
1807               "output deopt information and disassembly into the given file")
1808 
1809 DEFINE_BOOL(print_opt_source, false,
1810             "print source code of optimized and inlined functions")
1811 
1812 DEFINE_BOOL(vtune_prof_annotate_wasm, false,
1813             "Used when v8_enable_vtunejit is enabled, load wasm source map and "
1814             "provide annotate support (experimental).")
1815 
1816 DEFINE_BOOL(win64_unwinding_info, true, "Enable unwinding info for Windows/x64")
1817 
1818 #ifdef V8_TARGET_ARCH_ARM
1819 // Unsupported on arm. See https://crbug.com/v8/8713.
1820 DEFINE_BOOL_READONLY(
1821     interpreted_frames_native_stack, false,
1822     "Show interpreted frames on the native stack (useful for external "
1823     "profilers).")
1824 #else
1825 DEFINE_BOOL(interpreted_frames_native_stack, false,
1826             "Show interpreted frames on the native stack (useful for external "
1827             "profilers).")
1828 #endif
1829 
1830 //
1831 // Disassembler only flags
1832 //
1833 #undef FLAG
1834 #ifdef ENABLE_DISASSEMBLER
1835 #define FLAG FLAG_FULL
1836 #else
1837 #define FLAG FLAG_READONLY
1838 #endif
1839 
1840 // elements.cc
1841 DEFINE_BOOL(trace_elements_transitions, false, "trace elements transitions")
1842 
1843 DEFINE_BOOL(trace_creation_allocation_sites, false,
1844             "trace the creation of allocation sites")
1845 
1846 DEFINE_BOOL(print_code, false, "print generated code")
1847 DEFINE_BOOL(print_opt_code, false, "print optimized code")
1848 DEFINE_STRING(print_opt_code_filter, "*", "filter for printing optimized code")
1849 DEFINE_BOOL(print_code_verbose, false, "print more information for code")
1850 DEFINE_BOOL(print_builtin_code, false, "print generated code for builtins")
1851 DEFINE_STRING(print_builtin_code_filter, "*",
1852               "filter for printing builtin code")
1853 DEFINE_BOOL(print_regexp_code, false, "print generated regexp code")
1854 DEFINE_BOOL(print_regexp_bytecode, false, "print generated regexp bytecode")
1855 DEFINE_BOOL(print_builtin_size, false, "print code size for builtins")
1856 
1857 #ifdef ENABLE_DISASSEMBLER
1858 DEFINE_BOOL(sodium, false,
1859             "print generated code output suitable for use with "
1860             "the Sodium code viewer")
1861 
1862 DEFINE_IMPLICATION(sodium, print_code)
1863 DEFINE_IMPLICATION(sodium, print_opt_code)
1864 DEFINE_IMPLICATION(sodium, code_comments)
1865 
1866 DEFINE_BOOL(print_all_code, false, "enable all flags related to printing code")
1867 DEFINE_IMPLICATION(print_all_code, print_code)
1868 DEFINE_IMPLICATION(print_all_code, print_opt_code)
1869 DEFINE_IMPLICATION(print_all_code, print_code_verbose)
1870 DEFINE_IMPLICATION(print_all_code, print_builtin_code)
1871 DEFINE_IMPLICATION(print_all_code, print_regexp_code)
1872 DEFINE_IMPLICATION(print_all_code, code_comments)
1873 #endif
1874 
1875 #undef FLAG
1876 #define FLAG FLAG_FULL
1877 
1878 //
1879 // Predictable mode related flags.
1880 //
1881 
1882 DEFINE_BOOL(predictable, false, "enable predictable mode")
1883 DEFINE_IMPLICATION(predictable, single_threaded)
1884 DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
1885 DEFINE_VALUE_IMPLICATION(single_threaded, wasm_num_compilation_tasks, 0)
1886 DEFINE_NEG_IMPLICATION(single_threaded, wasm_async_compilation)
1887 
1888 DEFINE_BOOL(predictable_gc_schedule, false,
1889             "Predictable garbage collection schedule. Fixes heap growing, "
1890             "idle, and memory reducing behavior.")
1891 DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, min_semi_space_size, 4)
1892 DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, max_semi_space_size, 4)
1893 DEFINE_VALUE_IMPLICATION(predictable_gc_schedule, heap_growing_percent, 30)
1894 DEFINE_NEG_IMPLICATION(predictable_gc_schedule, memory_reducer)
1895 
1896 //
1897 // Threading related flags.
1898 //
1899 
1900 DEFINE_BOOL(single_threaded, false, "disable the use of background tasks")
1901 DEFINE_IMPLICATION(single_threaded, single_threaded_gc)
1902 DEFINE_NEG_IMPLICATION(single_threaded, concurrent_recompilation)
1903 DEFINE_NEG_IMPLICATION(single_threaded, compiler_dispatcher)
1904 
1905 //
1906 // Parallel and concurrent GC (Orinoco) related flags.
1907 //
1908 DEFINE_BOOL(single_threaded_gc, false, "disable the use of background gc tasks")
1909 DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_marking)
1910 DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_sweeping)
1911 DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_compaction)
1912 DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_marking)
1913 DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_pointer_update)
1914 DEFINE_NEG_IMPLICATION(single_threaded_gc, parallel_scavenge)
1915 DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_store_buffer)
1916 #ifdef ENABLE_MINOR_MC
1917 DEFINE_NEG_IMPLICATION(single_threaded_gc, minor_mc_parallel_marking)
1918 #endif  // ENABLE_MINOR_MC
1919 DEFINE_NEG_IMPLICATION(single_threaded_gc, concurrent_array_buffer_sweeping)
1920 
1921 #undef FLAG
1922 
1923 #ifdef VERIFY_PREDICTABLE
1924 #define FLAG FLAG_FULL
1925 #else
1926 #define FLAG FLAG_READONLY
1927 #endif
1928 
1929 DEFINE_BOOL(verify_predictable, false,
1930             "this mode is used for checking that V8 behaves predictably")
1931 DEFINE_INT(dump_allocations_digest_at_alloc, -1,
1932            "dump allocations digest each n-th allocation")
1933 
1934 //
1935 // Read-only flags
1936 //
1937 #undef FLAG
1938 #define FLAG FLAG_READONLY
1939 
1940 // assembler.h
1941 DEFINE_BOOL(enable_embedded_constant_pool, V8_EMBEDDED_CONSTANT_POOL,
1942             "enable use of embedded constant pools (PPC only)")
1943 
1944 DEFINE_BOOL(unbox_double_fields, V8_DOUBLE_FIELDS_UNBOXING,
1945             "enable in-object double fields unboxing (64-bit only)")
1946 DEFINE_IMPLICATION(unbox_double_fields, track_double_fields)
1947 
1948 // Cleanup...
1949 #undef FLAG_FULL
1950 #undef FLAG_READONLY
1951 #undef FLAG
1952 #undef FLAG_ALIAS
1953 
1954 #undef DEFINE_BOOL
1955 #undef DEFINE_MAYBE_BOOL
1956 #undef DEFINE_DEBUG_BOOL
1957 #undef DEFINE_INT
1958 #undef DEFINE_STRING
1959 #undef DEFINE_FLOAT
1960 #undef DEFINE_IMPLICATION
1961 #undef DEFINE_WEAK_IMPLICATION
1962 #undef DEFINE_NEG_IMPLICATION
1963 #undef DEFINE_NEG_VALUE_IMPLICATION
1964 #undef DEFINE_VALUE_IMPLICATION
1965 #undef DEFINE_WEAK_VALUE_IMPLICATION
1966 #undef DEFINE_GENERIC_IMPLICATION
1967 #undef DEFINE_ALIAS_BOOL
1968 #undef DEFINE_ALIAS_INT
1969 #undef DEFINE_ALIAS_STRING
1970 #undef DEFINE_ALIAS_FLOAT
1971 
1972 #undef FLAG_MODE_DECLARE
1973 #undef FLAG_MODE_DEFINE
1974 #undef FLAG_MODE_DEFINE_DEFAULTS
1975 #undef FLAG_MODE_META
1976 #undef FLAG_MODE_DEFINE_IMPLICATIONS
1977 #undef FLAG_MODE_APPLY
1978 
1979 #undef COMMA
1980