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 #define DEFINE_IMPLICATION(whenflag, thenflag)              \
14   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, true)
15 
16 #define DEFINE_NEG_IMPLICATION(whenflag, thenflag)          \
17   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, false)
18 
19 #define DEFINE_NEG_NEG_IMPLICATION(whenflag, thenflag) \
20   DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, false)
21 
22 // We want to declare the names of the variables for the header file.  Normally
23 // this will just be an extern declaration, but for a readonly flag we let the
24 // compiler make better optimizations by giving it the value.
25 #if defined(FLAG_MODE_DECLARE)
26 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
27   V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
28 #define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
29   static ctype const FLAG_##nam = def;
30 
31 // We want to supply the actual storage and value for the flag variable in the
32 // .cc file.  We only do this for writable flags.
33 #elif defined(FLAG_MODE_DEFINE)
34 #ifdef USING_V8_SHARED
35 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
36   V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
37 #else
38 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
39   V8_EXPORT_PRIVATE ctype FLAG_##nam = def;
40 #endif
41 
42 // We need to define all of our default values so that the Flag structure can
43 // access them by pointer.  These are just used internally inside of one .cc,
44 // for MODE_META, so there is no impact on the flags interface.
45 #elif defined(FLAG_MODE_DEFINE_DEFAULTS)
46 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
47   static ctype const FLAGDEFAULT_##nam = def;
48 
49 // We want to write entries into our meta data table, for internal parsing and
50 // printing / etc in the flag parser code.  We only do this for writable flags.
51 #elif defined(FLAG_MODE_META)
52 #define FLAG_FULL(ftype, ctype, nam, def, cmt)                              \
53   { Flag::TYPE_##ftype, #nam, &FLAG_##nam, &FLAGDEFAULT_##nam, cmt, false } \
54   ,
55 #define FLAG_ALIAS(ftype, ctype, alias, nam)                     \
56   {                                                              \
57     Flag::TYPE_##ftype, #alias, &FLAG_##nam, &FLAGDEFAULT_##nam, \
58         "alias for --" #nam, false                               \
59   }                                                              \
60   ,
61 
62 // We produce the code to set flags when it is implied by another flag.
63 #elif defined(FLAG_MODE_DEFINE_IMPLICATIONS)
64 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value) \
65   if (FLAG_##whenflag) FLAG_##thenflag = value;
66 
67 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value) \
68   if (!FLAG_##whenflag) FLAG_##thenflag = value;
69 
70 #else
71 #error No mode supplied when including flags.defs
72 #endif
73 
74 // Dummy defines for modes where it is not relevant.
75 #ifndef FLAG_FULL
76 #define FLAG_FULL(ftype, ctype, nam, def, cmt)
77 #endif
78 
79 #ifndef FLAG_READONLY
80 #define FLAG_READONLY(ftype, ctype, nam, def, cmt)
81 #endif
82 
83 #ifndef FLAG_ALIAS
84 #define FLAG_ALIAS(ftype, ctype, alias, nam)
85 #endif
86 
87 #ifndef DEFINE_VALUE_IMPLICATION
88 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)
89 #endif
90 
91 #ifndef DEFINE_NEG_VALUE_IMPLICATION
92 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)
93 #endif
94 
95 #define COMMA ,
96 
97 #ifdef FLAG_MODE_DECLARE
98 // Structure used to hold a collection of arguments to the JavaScript code.
99 struct JSArguments {
100  public:
101   inline const char*& operator[](int idx) const { return argv[idx]; }
CreateJSArguments102   static JSArguments Create(int argc, const char** argv) {
103     JSArguments args;
104     args.argc = argc;
105     args.argv = argv;
106     return args;
107   }
108   int argc;
109   const char** argv;
110 };
111 
112 struct MaybeBoolFlag {
CreateMaybeBoolFlag113   static MaybeBoolFlag Create(bool has_value, bool value) {
114     MaybeBoolFlag flag;
115     flag.has_value = has_value;
116     flag.value = value;
117     return flag;
118   }
119   bool has_value;
120   bool value;
121 };
122 #endif
123 
124 #ifdef DEBUG
125 #define DEBUG_BOOL true
126 #else
127 #define DEBUG_BOOL false
128 #endif
129 
130 // Supported ARM configurations are:
131 //  "armv6":       ARMv6 + VFPv2
132 //  "armv7":       ARMv7 + VFPv3-D32 + NEON
133 //  "armv7+sudiv": ARMv7 + VFPv4-D32 + NEON + SUDIV
134 //  "armv8":       ARMv8 (including all of the above)
135 #if !defined(ARM_TEST_NO_FEATURE_PROBE) ||                            \
136     (defined(CAN_USE_ARMV8_INSTRUCTIONS) &&                           \
137      defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
138      defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS))
139 #define ARM_ARCH_DEFAULT "armv8"
140 #elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_SUDIV) && \
141     defined(CAN_USE_NEON) && defined(CAN_USE_VFP3_INSTRUCTIONS)
142 #define ARM_ARCH_DEFAULT "armv7+sudiv"
143 #elif defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(CAN_USE_NEON) && \
144     defined(CAN_USE_VFP3_INSTRUCTIONS)
145 #define ARM_ARCH_DEFAULT "armv7"
146 #else
147 #define ARM_ARCH_DEFAULT "armv6"
148 #endif
149 
150 #ifdef V8_OS_WIN
151 # define ENABLE_LOG_COLOUR false
152 #else
153 # define ENABLE_LOG_COLOUR true
154 #endif
155 
156 #define DEFINE_BOOL(nam, def, cmt) FLAG(BOOL, bool, nam, def, cmt)
157 #define DEFINE_BOOL_READONLY(nam, def, cmt) \
158   FLAG_READONLY(BOOL, bool, nam, def, cmt)
159 #define DEFINE_MAYBE_BOOL(nam, cmt) \
160   FLAG(MAYBE_BOOL, MaybeBoolFlag, nam, {false COMMA false}, cmt)
161 #define DEFINE_INT(nam, def, cmt) FLAG(INT, int, nam, def, cmt)
162 #define DEFINE_FLOAT(nam, def, cmt) FLAG(FLOAT, double, nam, def, cmt)
163 #define DEFINE_STRING(nam, def, cmt) FLAG(STRING, const char*, nam, def, cmt)
164 #define DEFINE_ARGS(nam, cmt) FLAG(ARGS, JSArguments, nam, {0 COMMA NULL}, cmt)
165 
166 #define DEFINE_ALIAS_BOOL(alias, nam) FLAG_ALIAS(BOOL, bool, alias, nam)
167 #define DEFINE_ALIAS_INT(alias, nam) FLAG_ALIAS(INT, int, alias, nam)
168 #define DEFINE_ALIAS_FLOAT(alias, nam) FLAG_ALIAS(FLOAT, double, alias, nam)
169 #define DEFINE_ALIAS_STRING(alias, nam) \
170   FLAG_ALIAS(STRING, const char*, alias, nam)
171 #define DEFINE_ALIAS_ARGS(alias, nam) FLAG_ALIAS(ARGS, JSArguments, alias, nam)
172 
173 //
174 // Flags in all modes.
175 //
176 #define FLAG FLAG_FULL
177 
178 DEFINE_BOOL(experimental_extras, false,
179             "enable code compiled in via v8_experimental_extra_library_files")
180 
181 // Flags for language modes and experimental language features.
182 DEFINE_BOOL(use_strict, false, "enforce strict mode")
183 
184 DEFINE_BOOL(es_staging, false,
185             "enable test-worthy harmony features (for internal use only)")
186 DEFINE_BOOL(harmony, false, "enable all completed harmony features")
187 DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
188 DEFINE_IMPLICATION(es_staging, harmony)
189 
190 
191 // Activate on ClusterFuzz.
192 DEFINE_IMPLICATION(es_staging, harmony_regexp_lookbehind)
193 DEFINE_IMPLICATION(es_staging, move_object_start)
194 
195 // Features that are still work in progress (behind individual flags).
196 #define HARMONY_INPROGRESS(V)                                           \
197   V(harmony_array_prototype_values, "harmony Array.prototype.values")   \
198   V(harmony_function_sent, "harmony function.sent")                     \
199   V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")             \
200   V(harmony_simd, "harmony simd")                                       \
201   V(harmony_do_expressions, "harmony do-expressions")                   \
202   V(harmony_regexp_named_captures, "harmony regexp named captures")     \
203   V(harmony_regexp_property, "harmony unicode regexp property classes") \
204   V(harmony_class_fields, "harmony public fields in class literals")
205 
206 // Features that are complete (but still behind --harmony/es-staging flag).
207 #define HARMONY_STAGED_BASE(V)                              \
208   V(harmony_regexp_lookbehind, "harmony regexp lookbehind") \
209   V(harmony_restrictive_generators,                         \
210     "harmony restrictions on generator declarations")       \
211   V(harmony_tailcalls, "harmony tail calls")                \
212   V(harmony_trailing_commas,                                \
213     "harmony trailing commas in function parameter lists")  \
214   V(harmony_string_padding, "harmony String-padding methods")
215 
216 #ifdef V8_I18N_SUPPORT
217 #define HARMONY_STAGED(V)                                          \
218   HARMONY_STAGED_BASE(V)                                           \
219   V(datetime_format_to_parts, "Intl.DateTimeFormat.formatToParts") \
220   V(icu_case_mapping, "case mapping with ICU rather than Unibrow")
221 #else
222 #define HARMONY_STAGED(V) HARMONY_STAGED_BASE(V)
223 #endif
224 
225 // Features that are shipping (turned on by default, but internal flag remains).
226 #define HARMONY_SHIPPING(V) V(harmony_async_await, "harmony async-await")
227 
228 // Once a shipping feature has proved stable in the wild, it will be dropped
229 // from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,
230 // and associated tests are moved from the harmony directory to the appropriate
231 // esN directory.
232 
233 
234 #define FLAG_INPROGRESS_FEATURES(id, description) \
235   DEFINE_BOOL(id, false, "enable " #description " (in progress)")
236 HARMONY_INPROGRESS(FLAG_INPROGRESS_FEATURES)
237 #undef FLAG_INPROGRESS_FEATURES
238 
239 #define FLAG_STAGED_FEATURES(id, description) \
240   DEFINE_BOOL(id, false, "enable " #description) \
241   DEFINE_IMPLICATION(harmony, id)
242 HARMONY_STAGED(FLAG_STAGED_FEATURES)
243 #undef FLAG_STAGED_FEATURES
244 
245 #define FLAG_SHIPPING_FEATURES(id, description) \
246   DEFINE_BOOL(id, true, "enable " #description) \
247   DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
248 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
249 #undef FLAG_SHIPPING_FEATURES
250 
251 DEFINE_BOOL(future, false,
252             "Implies all staged features that we want to ship in the "
253             "not-too-far future")
254 DEFINE_IMPLICATION(future, ignition_staging)
255 
256 // Flags for experimental implementation features.
257 DEFINE_BOOL(allocation_site_pretenuring, true,
258             "pretenure with allocation sites")
259 DEFINE_BOOL(page_promotion, true, "promote pages based on utilization")
260 DEFINE_INT(page_promotion_threshold, 70,
261            "min percentage of live bytes on a page to enable fast evacuation")
262 DEFINE_BOOL(trace_pretenuring, false,
263             "trace pretenuring decisions of HAllocate instructions")
264 DEFINE_BOOL(trace_pretenuring_statistics, false,
265             "trace allocation site pretenuring statistics")
266 DEFINE_BOOL(track_fields, true, "track fields with only smi values")
267 DEFINE_BOOL(track_double_fields, true, "track fields with double values")
268 DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
269 DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
270 DEFINE_IMPLICATION(track_double_fields, track_fields)
271 DEFINE_IMPLICATION(track_heap_object_fields, track_fields)
272 DEFINE_IMPLICATION(track_computed_fields, track_fields)
273 DEFINE_BOOL(track_field_types, true, "track field types")
274 DEFINE_IMPLICATION(track_field_types, track_fields)
275 DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
276 DEFINE_BOOL(smi_binop, true, "support smi representation in binary operations")
277 DEFINE_BOOL(mark_shared_functions_for_tier_up, true,
278             "mark shared functions for tier up")
279 
280 // Flags for optimization types.
281 DEFINE_BOOL(optimize_for_size, false,
282             "Enables optimizations which favor memory size over execution "
283             "speed")
284 
285 DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
286 
287 // Flags for data representation optimizations
288 DEFINE_BOOL(unbox_double_arrays, true, "automatically unbox arrays of doubles")
289 DEFINE_BOOL(string_slices, true, "use string slices")
290 
291 // Flags for Ignition.
292 DEFINE_BOOL(ignition, false, "use ignition interpreter")
293 DEFINE_BOOL(ignition_staging, false, "use ignition with all staged features")
294 DEFINE_IMPLICATION(ignition_staging, ignition)
295 DEFINE_STRING(ignition_filter, "*", "filter for ignition interpreter")
296 DEFINE_BOOL(ignition_deadcode, true,
297             "use ignition dead code elimination optimizer")
298 DEFINE_BOOL(ignition_osr, true, "enable support for OSR from ignition code")
299 DEFINE_BOOL(ignition_peephole, true, "use ignition peephole optimizer")
300 DEFINE_BOOL(ignition_reo, true, "use ignition register equivalence optimizer")
301 DEFINE_BOOL(ignition_filter_expression_positions, true,
302             "filter expression positions before the bytecode pipeline")
303 DEFINE_BOOL(print_bytecode, false,
304             "print bytecode generated by ignition interpreter")
305 DEFINE_BOOL(trace_ignition, false,
306             "trace the bytecodes executed by the ignition interpreter")
307 DEFINE_BOOL(trace_ignition_codegen, false,
308             "trace the codegen of ignition interpreter bytecode handlers")
309 DEFINE_BOOL(trace_ignition_dispatches, false,
310             "traces the dispatches to bytecode handlers by the ignition "
311             "interpreter")
312 DEFINE_STRING(trace_ignition_dispatches_output_file, nullptr,
313               "the file to which the bytecode handler dispatch table is "
314               "written (by default, the table is not written to a file)")
315 
316 // Flags for Crankshaft.
317 DEFINE_BOOL(crankshaft, true, "use crankshaft")
318 DEFINE_STRING(hydrogen_filter, "*", "optimization filter")
319 DEFINE_BOOL(use_gvn, true, "use hydrogen global value numbering")
320 DEFINE_INT(gvn_iterations, 3, "maximum number of GVN fix-point iterations")
321 DEFINE_BOOL(use_canonicalizing, true, "use hydrogen instruction canonicalizing")
322 DEFINE_BOOL(use_inlining, true, "use function inlining")
323 DEFINE_BOOL(use_escape_analysis, true, "use hydrogen escape analysis")
324 DEFINE_BOOL(use_allocation_folding, true, "use allocation folding")
325 DEFINE_BOOL(use_local_allocation_folding, false, "only fold in basic blocks")
326 DEFINE_BOOL(use_write_barrier_elimination, true,
327             "eliminate write barriers targeting allocations in optimized code")
328 DEFINE_INT(max_inlining_levels, 5, "maximum number of inlining levels")
329 DEFINE_INT(max_inlined_source_size, 600,
330            "maximum source size in bytes considered for a single inlining")
331 DEFINE_INT(max_inlined_nodes, 200,
332            "maximum number of AST nodes considered for a single inlining")
333 DEFINE_INT(max_inlined_nodes_cumulative, 400,
334            "maximum cumulative number of AST nodes considered for inlining")
335 DEFINE_BOOL(loop_invariant_code_motion, true, "loop invariant code motion")
336 DEFINE_BOOL(fast_math, true, "faster (but maybe less accurate) math functions")
337 DEFINE_BOOL(collect_megamorphic_maps_from_stub_cache, false,
338             "crankshaft harvests type feedback from stub cache")
339 DEFINE_BOOL(hydrogen_stats, false, "print statistics for hydrogen")
340 DEFINE_BOOL(trace_check_elimination, false, "trace check elimination phase")
341 DEFINE_BOOL(trace_environment_liveness, false,
342             "trace liveness of local variable slots")
343 DEFINE_BOOL(trace_hydrogen, false, "trace generated hydrogen to file")
344 DEFINE_STRING(trace_hydrogen_filter, "*", "hydrogen tracing filter")
345 DEFINE_BOOL(trace_hydrogen_stubs, false, "trace generated hydrogen for stubs")
346 DEFINE_STRING(trace_hydrogen_file, NULL, "trace hydrogen to given file name")
347 DEFINE_STRING(trace_phase, "HLZ", "trace generated IR for specified phases")
348 DEFINE_BOOL(trace_inlining, false, "trace inlining decisions")
349 DEFINE_BOOL(trace_load_elimination, false, "trace load elimination")
350 DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
351 DEFINE_BOOL(turbo_verify_store_elimination, false,
352             "verify store elimination more rigorously")
353 DEFINE_BOOL(trace_alloc, false, "trace register allocator")
354 DEFINE_BOOL(trace_all_uses, false, "trace all use positions")
355 DEFINE_BOOL(trace_range, false, "trace range analysis")
356 DEFINE_BOOL(trace_gvn, false, "trace global value numbering")
357 DEFINE_BOOL(trace_representation, false, "trace representation types")
358 DEFINE_BOOL(trace_removable_simulates, false, "trace removable simulates")
359 DEFINE_BOOL(trace_escape_analysis, false, "trace hydrogen escape analysis")
360 DEFINE_BOOL(trace_allocation_folding, false, "trace allocation folding")
361 DEFINE_BOOL(trace_track_allocation_sites, false,
362             "trace the tracking of allocation sites")
363 DEFINE_BOOL(trace_migration, false, "trace object migration")
364 DEFINE_BOOL(trace_generalization, false, "trace map generalization")
365 DEFINE_BOOL(stress_pointer_maps, false, "pointer map for every instruction")
366 DEFINE_BOOL(stress_environments, false, "environment for every instruction")
367 DEFINE_INT(deopt_every_n_times, 0,
368            "deoptimize every n times a deopt point is passed")
369 DEFINE_INT(deopt_every_n_garbage_collections, 0,
370            "deoptimize every n garbage collections")
371 DEFINE_BOOL(print_deopt_stress, false, "print number of possible deopt points")
372 DEFINE_BOOL(trap_on_deopt, false, "put a break point before deoptimizing")
373 DEFINE_BOOL(trap_on_stub_deopt, false,
374             "put a break point before deoptimizing a stub")
375 DEFINE_BOOL(deoptimize_uncommon_cases, true, "deoptimize uncommon cases")
376 DEFINE_BOOL(polymorphic_inlining, true, "polymorphic inlining")
377 DEFINE_BOOL(use_osr, true, "use on-stack replacement")
378 DEFINE_BOOL(array_bounds_checks_elimination, true,
379             "perform array bounds checks elimination")
380 DEFINE_BOOL(trace_bce, false, "trace array bounds check elimination")
381 DEFINE_BOOL(array_index_dehoisting, true, "perform array index dehoisting")
382 DEFINE_BOOL(analyze_environment_liveness, true,
383             "analyze liveness of environment slots and zap dead values")
384 DEFINE_BOOL(load_elimination, true, "use load elimination")
385 DEFINE_BOOL(check_elimination, true, "use check elimination")
386 DEFINE_BOOL(store_elimination, false, "use store elimination")
387 DEFINE_BOOL(dead_code_elimination, true, "use dead code elimination")
388 DEFINE_BOOL(fold_constants, true, "use constant folding")
389 DEFINE_BOOL(trace_dead_code_elimination, false, "trace dead code elimination")
390 DEFINE_BOOL(unreachable_code_elimination, true, "eliminate unreachable code")
391 DEFINE_BOOL(trace_osr, false, "trace on-stack replacement")
392 DEFINE_INT(stress_runs, 0, "number of stress runs")
393 DEFINE_BOOL(lookup_sample_by_shared, true,
394             "when picking a function to optimize, watch for shared function "
395             "info, not JSFunction itself")
396 DEFINE_BOOL(flush_optimized_code_cache, false,
397             "flushes the cache of optimized code for closures on every GC")
398 DEFINE_BOOL(inline_construct, true, "inline constructor calls")
399 DEFINE_BOOL(inline_arguments, true, "inline functions with arguments object")
400 DEFINE_BOOL(inline_accessors, true, "inline JavaScript accessors")
401 DEFINE_BOOL(inline_into_try, true, "inline into try blocks")
402 DEFINE_INT(escape_analysis_iterations, 2,
403            "maximum number of escape analysis fix-point iterations")
404 
405 DEFINE_BOOL(concurrent_recompilation, true,
406             "optimizing hot functions asynchronously on a separate thread")
407 DEFINE_BOOL(trace_concurrent_recompilation, false,
408             "track concurrent recompilation")
409 DEFINE_INT(concurrent_recompilation_queue_length, 8,
410            "the length of the concurrent compilation queue")
411 DEFINE_INT(concurrent_recompilation_delay, 0,
412            "artificial compilation delay in ms")
413 DEFINE_BOOL(block_concurrent_recompilation, false,
414             "block queued jobs until released")
415 
416 DEFINE_BOOL(omit_map_checks_for_leaf_maps, true,
417             "do not emit check maps for constant values that have a leaf map, "
418             "deoptimize the optimized code if the layout of the maps changes.")
419 
420 // Flags for TurboFan.
421 DEFINE_BOOL(turbo, false, "enable TurboFan compiler")
422 DEFINE_IMPLICATION(turbo, turbo_asm_deoptimization)
423 DEFINE_IMPLICATION(turbo, turbo_loop_peeling)
424 DEFINE_IMPLICATION(turbo, turbo_escape)
425 DEFINE_BOOL(turbo_sp_frame_access, false,
426             "use stack pointer-relative access to frame wherever possible")
427 DEFINE_BOOL(turbo_preprocess_ranges, true,
428             "run pre-register allocation heuristics")
429 DEFINE_BOOL(turbo_loop_stackcheck, true, "enable stack checks in loops")
430 DEFINE_STRING(turbo_filter, "~~", "optimization filter for TurboFan compiler")
431 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
432 DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
433 DEFINE_IMPLICATION(trace_turbo_graph, trace_turbo)
434 DEFINE_STRING(trace_turbo_cfg_file, NULL,
435               "trace turbo cfg graph (for C1 visualizer) to a given file name")
436 DEFINE_BOOL(trace_turbo_types, true, "trace TurboFan's types")
437 DEFINE_BOOL(trace_turbo_scheduler, false, "trace TurboFan's scheduler")
438 DEFINE_BOOL(trace_turbo_reduction, false, "trace TurboFan's various reducers")
439 DEFINE_BOOL(trace_turbo_trimming, false, "trace TurboFan's graph trimmer")
440 DEFINE_BOOL(trace_turbo_jt, false, "trace TurboFan's jump threading")
441 DEFINE_BOOL(trace_turbo_ceq, false, "trace TurboFan's control equivalence")
442 DEFINE_BOOL(trace_turbo_loop, false, "trace TurboFan's loop optimizations")
443 DEFINE_BOOL(turbo_asm, true, "enable TurboFan for asm.js code")
444 DEFINE_BOOL(turbo_asm_deoptimization, false,
445             "enable deoptimization in TurboFan for asm.js code")
446 DEFINE_BOOL(turbo_verify, DEBUG_BOOL, "verify TurboFan graphs at each phase")
447 DEFINE_STRING(turbo_verify_machine_graph, nullptr,
448               "verify TurboFan machine graph before instruction selection")
449 DEFINE_BOOL(turbo_stats, false, "print TurboFan statistics")
450 DEFINE_BOOL(turbo_stats_nvp, false,
451             "print TurboFan statistics in machine-readable format")
452 DEFINE_BOOL(turbo_splitting, true, "split nodes during scheduling in TurboFan")
453 DEFINE_BOOL(turbo_type_feedback, true,
454             "use typed feedback for representation inference in Turbofan")
455 DEFINE_BOOL(function_context_specialization, false,
456             "enable function context specialization in TurboFan")
457 DEFINE_BOOL(turbo_inlining, true, "enable inlining in TurboFan")
458 DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
459 DEFINE_BOOL(turbo_load_elimination, true, "enable load elimination in TurboFan")
460 DEFINE_BOOL(trace_turbo_load_elimination, false,
461             "trace TurboFan load elimination")
462 DEFINE_BOOL(loop_assignment_analysis, true, "perform loop assignment analysis")
463 DEFINE_BOOL(turbo_profiling, false, "enable profiling in TurboFan")
464 DEFINE_BOOL(turbo_verify_allocation, DEBUG_BOOL,
465             "verify register allocation in TurboFan")
466 DEFINE_BOOL(turbo_move_optimization, true, "optimize gap moves in TurboFan")
467 DEFINE_BOOL(turbo_jt, true, "enable jump threading in TurboFan")
468 DEFINE_BOOL(turbo_stress_loop_peeling, false,
469             "stress loop peeling optimization")
470 DEFINE_BOOL(turbo_loop_peeling, false, "Turbofan loop peeling")
471 DEFINE_BOOL(turbo_loop_variable, true, "Turbofan loop variable optimization")
472 DEFINE_BOOL(turbo_cf_optimization, true, "optimize control flow in TurboFan")
473 DEFINE_BOOL(turbo_frame_elision, true, "elide frames in TurboFan")
474 DEFINE_BOOL(turbo_escape, false, "enable escape analysis")
475 DEFINE_BOOL(turbo_instruction_scheduling, false,
476             "enable instruction scheduling in TurboFan")
477 DEFINE_BOOL(turbo_stress_instruction_scheduling, false,
478             "randomly schedule instructions to stress dependency tracking")
479 DEFINE_BOOL(turbo_store_elimination, true,
480             "enable store-store elimination in TurboFan")
481 
482 // Flags to help platform porters
483 DEFINE_BOOL(minimal, false,
484             "simplifies execution model to make porting "
485             "easier (e.g. always use Ignition, never use Crankshaft")
486 DEFINE_IMPLICATION(minimal, ignition)
487 DEFINE_NEG_IMPLICATION(minimal, crankshaft)
488 DEFINE_NEG_IMPLICATION(minimal, use_ic)
489 
490 // Flags for native WebAssembly.
491 DEFINE_BOOL(expose_wasm, false, "expose WASM interface to JavaScript")
492 DEFINE_INT(wasm_num_compilation_tasks, 10,
493            "number of parallel compilation tasks for wasm")
494 DEFINE_BOOL(trace_wasm_encoder, false, "trace encoding of wasm code")
495 DEFINE_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
496 DEFINE_BOOL(trace_wasm_decode_time, false, "trace decoding time of wasm code")
497 DEFINE_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
498 DEFINE_BOOL(trace_wasm_interpreter, false, "trace interpretation of wasm code")
499 DEFINE_INT(trace_wasm_ast_start, 0,
500            "start function for WASM AST trace (inclusive)")
501 DEFINE_INT(trace_wasm_ast_end, 0, "end function for WASM AST trace (exclusive)")
502 DEFINE_INT(skip_compiling_wasm_funcs, 0, "start compiling at function N")
503 DEFINE_BOOL(wasm_break_on_decoder_error, false,
504             "debug break when wasm decoder encounters an error")
505 DEFINE_BOOL(wasm_loop_assignment_analysis, true,
506             "perform loop assignment analysis for WASM")
507 
508 DEFINE_BOOL(validate_asm, false, "validate asm.js modules before compiling")
509 
510 DEFINE_BOOL(dump_wasm_module, false, "dump WASM module bytes")
511 DEFINE_STRING(dump_wasm_module_path, NULL, "directory to dump wasm modules to")
512 
513 DEFINE_INT(typed_array_max_size_in_heap, 64,
514            "threshold for in-heap typed array")
515 
516 DEFINE_BOOL(wasm_simd_prototype, false,
517             "enable prototype simd opcodes for wasm")
518 DEFINE_BOOL(wasm_eh_prototype, false,
519             "enable prototype exception handling opcodes for wasm")
520 DEFINE_BOOL(wasm_mv_prototype, false,
521             "enable prototype multi-value support for wasm")
522 DEFINE_BOOL(wasm_atomics_prototype, false,
523             "enable prototype atomic opcodes for wasm")
524 
525 DEFINE_BOOL(wasm_trap_handler, false,
526             "use signal handlers to catch out of bounds memory access in wasm"
527             " (currently Linux x86_64 only)")
528 
529 // Profiler flags.
530 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
531 // 0x1800 fits in the immediate field of an ARM instruction.
532 DEFINE_INT(interrupt_budget, 0x1800,
533            "execution budget before interrupt is triggered")
534 DEFINE_INT(type_info_threshold, 25,
535            "percentage of ICs that must have type info to allow optimization")
536 DEFINE_INT(generic_ic_threshold, 30,
537            "max percentage of megamorphic/generic ICs to allow optimization")
538 DEFINE_INT(self_opt_count, 130, "call count before self-optimization")
539 
540 DEFINE_BOOL(trace_opt_verbose, false, "extra verbose compilation tracing")
541 DEFINE_IMPLICATION(trace_opt_verbose, trace_opt)
542 
543 // assembler-ia32.cc / assembler-arm.cc / assembler-x64.cc
544 DEFINE_BOOL(debug_code, false, "generate extra code (assertions) for debugging")
545 DEFINE_BOOL(code_comments, false, "emit comments in code disassembly")
546 DEFINE_BOOL(enable_sse3, true, "enable use of SSE3 instructions if available")
547 DEFINE_BOOL(enable_ssse3, true, "enable use of SSSE3 instructions if available")
548 DEFINE_BOOL(enable_sse4_1, true,
549             "enable use of SSE4.1 instructions if available")
550 DEFINE_BOOL(enable_sahf, true,
551             "enable use of SAHF instruction if available (X64 only)")
552 DEFINE_BOOL(enable_avx, true, "enable use of AVX instructions if available")
553 DEFINE_BOOL(enable_fma3, true, "enable use of FMA3 instructions if available")
554 DEFINE_BOOL(enable_bmi1, true, "enable use of BMI1 instructions if available")
555 DEFINE_BOOL(enable_bmi2, true, "enable use of BMI2 instructions if available")
556 DEFINE_BOOL(enable_lzcnt, true, "enable use of LZCNT instruction if available")
557 DEFINE_BOOL(enable_popcnt, true,
558             "enable use of POPCNT instruction if available")
559 DEFINE_STRING(arm_arch, ARM_ARCH_DEFAULT,
560               "generate instructions for the selected ARM architecture if "
561               "available: armv6, armv7, armv7+sudiv or armv8")
562 DEFINE_BOOL(enable_vldr_imm, false,
563             "enable use of constant pools for double immediate (ARM only)")
564 DEFINE_BOOL(force_long_branches, false,
565             "force all emitted branches to be in long mode (MIPS/PPC only)")
566 DEFINE_STRING(mcpu, "auto", "enable optimization for specific cpu")
567 
568 // Deprecated ARM flags (replaced by arm_arch).
569 DEFINE_MAYBE_BOOL(enable_armv7, "deprecated (use --arm_arch instead)")
570 DEFINE_MAYBE_BOOL(enable_vfp3, "deprecated (use --arm_arch instead)")
571 DEFINE_MAYBE_BOOL(enable_32dregs, "deprecated (use --arm_arch instead)")
572 DEFINE_MAYBE_BOOL(enable_neon, "deprecated (use --arm_arch instead)")
573 DEFINE_MAYBE_BOOL(enable_sudiv, "deprecated (use --arm_arch instead)")
574 DEFINE_MAYBE_BOOL(enable_armv8, "deprecated (use --arm_arch instead)")
575 
576 // regexp-macro-assembler-*.cc
577 DEFINE_BOOL(enable_regexp_unaligned_accesses, true,
578             "enable unaligned accesses for the regexp engine")
579 
580 // api.cc
581 DEFINE_BOOL(script_streaming, true, "enable parsing on background")
582 
583 // bootstrapper.cc
584 DEFINE_STRING(expose_natives_as, NULL, "expose natives in global object")
585 DEFINE_STRING(expose_debug_as, NULL, "expose debug in global object")
586 DEFINE_BOOL(expose_free_buffer, false, "expose freeBuffer extension")
587 DEFINE_BOOL(expose_gc, false, "expose gc extension")
588 DEFINE_STRING(expose_gc_as, NULL,
589               "expose gc extension under the specified name")
590 DEFINE_IMPLICATION(expose_gc_as, expose_gc)
591 DEFINE_BOOL(expose_externalize_string, false,
592             "expose externalize string extension")
593 DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
594 DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
595 DEFINE_BOOL(builtins_in_stack_traces, false,
596             "show built-in functions in stack traces")
597 
598 // builtins.cc
599 DEFINE_BOOL(allow_unsafe_function_constructor, false,
600             "allow invoking the function constructor without security checks")
601 
602 // builtins-ia32.cc
603 DEFINE_BOOL(inline_new, true, "use fast inline allocation")
604 
605 // codegen-ia32.cc / codegen-arm.cc
606 DEFINE_BOOL(trace_codegen, false,
607             "print name of functions for which code is generated")
608 DEFINE_BOOL(trace, false, "trace function calls")
609 DEFINE_BOOL(mask_constants_with_cookie, true,
610             "use random jit cookie to mask large constants")
611 
612 // codegen.cc
613 DEFINE_BOOL(lazy, true, "use lazy compilation")
614 DEFINE_BOOL(trace_opt, false, "trace lazy optimization")
615 DEFINE_BOOL(trace_opt_stats, false, "trace lazy optimization statistics")
616 DEFINE_BOOL(trace_file_names, false,
617             "include file names in trace-opt/trace-deopt output")
618 DEFINE_BOOL(opt, true, "use adaptive optimizations")
619 DEFINE_BOOL(always_opt, false, "always try to optimize functions")
620 DEFINE_BOOL(always_osr, false, "always try to OSR functions")
621 DEFINE_BOOL(prepare_always_opt, false, "prepare for turning on always opt")
622 DEFINE_BOOL(trace_deopt, false, "trace optimize function deoptimization")
623 DEFINE_BOOL(trace_stub_failures, false,
624             "trace deoptimization of generated code stubs")
625 
626 DEFINE_BOOL(serialize_toplevel, true, "enable caching of toplevel scripts")
627 DEFINE_BOOL(serialize_eager, false, "compile eagerly when caching scripts")
628 DEFINE_BOOL(serialize_age_code, false, "pre age code in the code cache")
629 DEFINE_BOOL(trace_serializer, false, "print code serializer trace")
630 #ifdef DEBUG
631 DEFINE_BOOL(external_reference_stats, false,
632             "print statistics on external references used during serialization")
633 #endif  // DEBUG
634 
635 // compiler.cc
636 DEFINE_INT(min_preparse_length, 1024,
637            "minimum length for automatic enable preparsing")
638 DEFINE_INT(max_opt_count, 10,
639            "maximum number of optimization attempts before giving up.")
640 
641 // compilation-cache.cc
642 DEFINE_BOOL(compilation_cache, true, "enable compilation cache")
643 
644 DEFINE_BOOL(cache_prototype_transitions, true, "cache prototype transitions")
645 
646 // cpu-profiler.cc
647 DEFINE_INT(cpu_profiler_sampling_interval, 1000,
648            "CPU profiler sampling interval in microseconds")
649 
650 // Array abuse tracing
651 DEFINE_BOOL(trace_js_array_abuse, false,
652             "trace out-of-bounds accesses to JS arrays")
653 DEFINE_BOOL(trace_external_array_abuse, false,
654             "trace out-of-bounds-accesses to external arrays")
655 DEFINE_BOOL(trace_array_abuse, false,
656             "trace out-of-bounds accesses to all arrays")
657 DEFINE_IMPLICATION(trace_array_abuse, trace_js_array_abuse)
658 DEFINE_IMPLICATION(trace_array_abuse, trace_external_array_abuse)
659 
660 // debugger
661 DEFINE_BOOL(trace_debug_json, false, "trace debugging JSON request/response")
662 DEFINE_BOOL(enable_liveedit, true, "enable liveedit experimental feature")
663 DEFINE_BOOL(hard_abort, true, "abort by crashing")
664 
665 // execution.cc
666 DEFINE_INT(stack_size, V8_DEFAULT_STACK_SIZE_KB,
667            "default size of stack region v8 is allowed to use (in kBytes)")
668 
669 // frames.cc
670 DEFINE_INT(max_stack_trace_source_length, 300,
671            "maximum length of function source code printed in a stack trace.")
672 
673 // full-codegen.cc
674 DEFINE_BOOL(always_inline_smi_code, false,
675             "always inline smi code in non-opt code")
676 DEFINE_BOOL(verify_operand_stack_depth, false,
677             "emit debug code that verifies the static tracking of the operand "
678             "stack depth")
679 
680 // heap.cc
681 DEFINE_INT(min_semi_space_size, 0,
682            "min size of a semi-space (in MBytes), the new space consists of two"
683            "semi-spaces")
684 DEFINE_INT(max_semi_space_size, 0,
685            "max size of a semi-space (in MBytes), the new space consists of two"
686            "semi-spaces")
687 DEFINE_INT(semi_space_growth_factor, 2, "factor by which to grow the new space")
688 DEFINE_BOOL(experimental_new_space_growth_heuristic, false,
689             "Grow the new space based on the percentage of survivors instead "
690             "of their absolute value.")
691 DEFINE_INT(max_old_space_size, 0, "max size of the old space (in Mbytes)")
692 DEFINE_INT(initial_old_space_size, 0, "initial old space size (in Mbytes)")
693 DEFINE_INT(max_executable_size, 0, "max size of executable memory (in Mbytes)")
694 DEFINE_BOOL(gc_global, false, "always perform global GCs")
695 DEFINE_INT(gc_interval, -1, "garbage collect after <n> allocations")
696 DEFINE_INT(retain_maps_for_n_gc, 2,
697            "keeps maps alive for <n> old space garbage collections")
698 DEFINE_BOOL(trace_gc, false,
699             "print one trace line following each garbage collection")
700 DEFINE_BOOL(trace_gc_nvp, false,
701             "print one detailed trace line in name=value format "
702             "after each garbage collection")
703 DEFINE_BOOL(trace_gc_ignore_scavenger, false,
704             "do not print trace line after scavenger collection")
705 DEFINE_BOOL(trace_idle_notification, false,
706             "print one trace line following each idle notification")
707 DEFINE_BOOL(trace_idle_notification_verbose, false,
708             "prints the heap state used by the idle notification")
709 DEFINE_BOOL(print_max_heap_committed, false,
710             "print statistics of the maximum memory committed for the heap "
711             "in name=value format on exit")
712 DEFINE_BOOL(trace_gc_verbose, false,
713             "print more details following each garbage collection")
714 DEFINE_INT(trace_allocation_stack_interval, -1,
715            "print stack trace after <n> free-list allocations")
716 DEFINE_BOOL(trace_fragmentation, false, "report fragmentation for old space")
717 DEFINE_BOOL(trace_fragmentation_verbose, false,
718             "report fragmentation for old space (detailed)")
719 DEFINE_BOOL(trace_evacuation, false, "report evacuation statistics")
720 DEFINE_BOOL(trace_mutator_utilization, false,
721             "print mutator utilization, allocation speed, gc speed")
722 DEFINE_BOOL(weak_embedded_maps_in_optimized_code, true,
723             "make maps embedded in optimized code weak")
724 DEFINE_BOOL(weak_embedded_objects_in_optimized_code, true,
725             "make objects embedded in optimized code weak")
726 DEFINE_BOOL(flush_code, true, "flush code that we expect not to use again")
727 DEFINE_BOOL(trace_code_flushing, false, "trace code flushing progress")
728 DEFINE_BOOL(age_code, true,
729             "track un-executed functions to age code and flush only "
730             "old code (required for code flushing)")
731 DEFINE_BOOL(incremental_marking, true, "use incremental marking")
732 DEFINE_BOOL(incremental_marking_wrappers, true,
733             "use incremental marking for marking wrappers")
734 DEFINE_INT(min_progress_during_incremental_marking_finalization, 32,
735            "keep finalizing incremental marking as long as we discover at "
736            "least this many unmarked objects")
737 DEFINE_INT(max_incremental_marking_finalization_rounds, 3,
738            "at most try this many times to finalize incremental marking")
739 DEFINE_BOOL(minor_mc, false, "perform young generation mark compact GCs")
740 DEFINE_NEG_IMPLICATION(minor_mc, incremental_marking)
741 DEFINE_BOOL(black_allocation, false, "use black allocation")
742 DEFINE_BOOL(concurrent_sweeping, true, "use concurrent sweeping")
743 DEFINE_BOOL(parallel_compaction, true, "use parallel compaction")
744 DEFINE_BOOL(parallel_pointer_update, true,
745             "use parallel pointer update during compaction")
746 DEFINE_BOOL(trace_incremental_marking, false,
747             "trace progress of the incremental marking")
748 DEFINE_BOOL(track_gc_object_stats, false,
749             "track object counts and memory usage")
750 DEFINE_BOOL(trace_gc_object_stats, false,
751             "trace object counts and memory usage")
752 DEFINE_INT(gc_stats, 0, "Used by tracing internally to enable gc statistics")
753 DEFINE_IMPLICATION(trace_gc_object_stats, track_gc_object_stats)
754 DEFINE_VALUE_IMPLICATION(track_gc_object_stats, gc_stats, 1)
755 DEFINE_VALUE_IMPLICATION(trace_gc_object_stats, gc_stats, 1)
756 DEFINE_NEG_IMPLICATION(trace_gc_object_stats, incremental_marking)
757 DEFINE_BOOL(track_detached_contexts, true,
758             "track native contexts that are expected to be garbage collected")
759 DEFINE_BOOL(trace_detached_contexts, false,
760             "trace native contexts that are expected to be garbage collected")
761 DEFINE_IMPLICATION(trace_detached_contexts, track_detached_contexts)
762 #ifdef VERIFY_HEAP
763 DEFINE_BOOL(verify_heap, false, "verify heap pointers before and after GC")
764 #endif
765 DEFINE_BOOL(move_object_start, true, "enable moving of object starts")
766 DEFINE_BOOL(memory_reducer, true, "use memory reducer")
767 DEFINE_INT(heap_growing_percent, 0,
768            "specifies heap growing factor as (1 + heap_growing_percent/100)")
769 
770 // spaces.cc
771 DEFINE_INT(v8_os_page_size, 0, "override OS page size (in KBytes)")
772 
773 // execution.cc, messages.cc
774 DEFINE_BOOL(clear_exceptions_on_js_entry, false,
775             "clear pending exceptions when entering JavaScript")
776 
777 // counters.cc
778 DEFINE_INT(histogram_interval, 600000,
779            "time interval in ms for aggregating memory histograms")
780 
781 // global-handles.cc
782 DEFINE_BOOL(trace_object_groups, false,
783             "print object groups detected during each garbage collection")
784 
785 // heap-snapshot-generator.cc
786 DEFINE_BOOL(heap_profiler_trace_objects, false,
787             "Dump heap object allocations/movements/size_updates")
788 
789 
790 // sampling-heap-profiler.cc
791 DEFINE_BOOL(sampling_heap_profiler_suppress_randomness, false,
792             "Use constant sample intervals to eliminate test flakiness")
793 
794 
795 // v8.cc
796 DEFINE_BOOL(use_idle_notification, true,
797             "Use idle notification to reduce memory footprint.")
798 // ic.cc
799 DEFINE_BOOL(use_ic, true, "use inline caching")
800 DEFINE_BOOL(trace_ic, false, "trace inline cache state transitions")
801 DEFINE_BOOL_READONLY(tf_load_ic_stub, true, "use TF LoadIC stub")
802 DEFINE_BOOL(tf_store_ic_stub, true, "use TF StoreIC stub")
803 
804 // macro-assembler-ia32.cc
805 DEFINE_BOOL(native_code_counters, false,
806             "generate extra code for manipulating stats counters")
807 
808 // mark-compact.cc
809 DEFINE_BOOL(always_compact, false, "Perform compaction on every full GC")
810 DEFINE_BOOL(never_compact, false,
811             "Never perform compaction on full GC - testing only")
812 DEFINE_BOOL(compact_code_space, true, "Compact code space on full collections")
813 DEFINE_BOOL(cleanup_code_caches_at_gc, true,
814             "Flush inline caches prior to mark compact collection and "
815             "flush code caches in maps during mark compact cycle.")
816 DEFINE_BOOL(use_marking_progress_bar, true,
817             "Use a progress bar to scan large objects in increments when "
818             "incremental marking is active.")
819 DEFINE_BOOL(zap_code_space, DEBUG_BOOL,
820             "Zap free memory in code space with 0xCC while sweeping.")
821 DEFINE_INT(random_seed, 0,
822            "Default seed for initializing random generator "
823            "(0, the default, means to use system random).")
824 
825 // objects.cc
826 DEFINE_BOOL(trace_weak_arrays, false, "Trace WeakFixedArray usage")
827 DEFINE_BOOL(trace_prototype_users, false,
828             "Trace updates to prototype user tracking")
829 DEFINE_BOOL(use_verbose_printer, true, "allows verbose printing")
830 DEFINE_BOOL(trace_for_in_enumerate, false, "Trace for-in enumerate slow-paths")
831 #if TRACE_MAPS
832 DEFINE_BOOL(trace_maps, false, "trace map creation")
833 #endif
834 
835 // parser.cc
836 DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
837 DEFINE_BOOL(trace_parse, false, "trace parsing and preparsing")
838 DEFINE_BOOL(trace_preparse, false, "trace preparsing decisions")
839 DEFINE_BOOL(lazy_inner_functions, false, "enable lazy parsing inner functions")
840 
841 // simulator-arm.cc, simulator-arm64.cc and simulator-mips.cc
842 DEFINE_BOOL(trace_sim, false, "Trace simulator execution")
843 DEFINE_BOOL(debug_sim, false, "Enable debugging the simulator")
844 DEFINE_BOOL(check_icache, false,
845             "Check icache flushes in ARM and MIPS simulator")
846 DEFINE_INT(stop_sim_at, 0, "Simulator stop after x number of instructions")
847 #if defined(V8_TARGET_ARCH_ARM64) || defined(V8_TARGET_ARCH_MIPS64) || \
848     defined(V8_TARGET_ARCH_PPC64)
849 DEFINE_INT(sim_stack_alignment, 16,
850            "Stack alignment in bytes in simulator. This must be a power of two "
851            "and it must be at least 16. 16 is default.")
852 #else
853 DEFINE_INT(sim_stack_alignment, 8,
854            "Stack alingment in bytes in simulator (4 or 8, 8 is default)")
855 #endif
856 DEFINE_INT(sim_stack_size, 2 * MB / KB,
857            "Stack size of the ARM64, MIPS64 and PPC64 simulator "
858            "in kBytes (default is 2 MB)")
859 DEFINE_BOOL(log_regs_modified, true,
860             "When logging register values, only print modified registers.")
861 DEFINE_BOOL(log_colour, ENABLE_LOG_COLOUR,
862             "When logging, try to use coloured output.")
863 DEFINE_BOOL(ignore_asm_unimplemented_break, false,
864             "Don't break for ASM_UNIMPLEMENTED_BREAK macros.")
865 DEFINE_BOOL(trace_sim_messages, false,
866             "Trace simulator debug messages. Implied by --trace-sim.")
867 
868 // isolate.cc
869 DEFINE_BOOL(stack_trace_on_illegal, false,
870             "print stack trace when an illegal exception is thrown")
871 DEFINE_BOOL(abort_on_uncaught_exception, false,
872             "abort program (dump core) when an uncaught exception is thrown")
873 DEFINE_BOOL(abort_on_stack_overflow, false,
874             "Abort program when stack overflow (as opposed to throwing "
875             "RangeError). This is useful for fuzzing where the spec behaviour "
876             "would introduce nondeterminism.")
877 DEFINE_BOOL(randomize_hashes, true,
878             "randomize hashes to avoid predictable hash collisions "
879             "(with snapshots this option cannot override the baked-in seed)")
880 DEFINE_INT(hash_seed, 0,
881            "Fixed seed to use to hash property keys (0 means random)"
882            "(with snapshots this option cannot override the baked-in seed)")
883 DEFINE_BOOL(trace_rail, false, "trace RAIL mode")
884 DEFINE_BOOL(print_all_exceptions, false,
885             "print exception object and stack trace on each thrown exception")
886 
887 // runtime.cc
888 DEFINE_BOOL(runtime_call_stats, false, "report runtime call counts and times")
889 DEFINE_INT(runtime_stats, 0,
890            "internal usage only for controlling runtime statistics")
891 DEFINE_VALUE_IMPLICATION(runtime_call_stats, runtime_stats, 1)
892 
893 // snapshot-common.cc
894 DEFINE_BOOL(profile_deserialization, false,
895             "Print the time it takes to deserialize the snapshot.")
896 DEFINE_BOOL(serialization_statistics, false,
897             "Collect statistics on serialized objects.")
898 
899 // Regexp
900 DEFINE_BOOL(regexp_optimization, true, "generate optimized regexp code")
901 
902 // Testing flags test/cctest/test-{flags,api,serialization}.cc
903 DEFINE_BOOL(testing_bool_flag, true, "testing_bool_flag")
904 DEFINE_MAYBE_BOOL(testing_maybe_bool_flag, "testing_maybe_bool_flag")
905 DEFINE_INT(testing_int_flag, 13, "testing_int_flag")
906 DEFINE_FLOAT(testing_float_flag, 2.5, "float-flag")
907 DEFINE_STRING(testing_string_flag, "Hello, world!", "string-flag")
908 DEFINE_INT(testing_prng_seed, 42, "Seed used for threading test randomness")
909 
910 // mksnapshot.cc
911 DEFINE_STRING(startup_src, NULL,
912               "Write V8 startup as C++ src. (mksnapshot only)")
913 DEFINE_STRING(startup_blob, NULL,
914               "Write V8 startup blob file. (mksnapshot only)")
915 
916 // code-stubs-hydrogen.cc
917 DEFINE_BOOL(profile_hydrogen_code_stub_compilation, false,
918             "Print the time it takes to lazily compile hydrogen code stubs.")
919 
920 // mark-compact.cc
921 DEFINE_BOOL(force_marking_deque_overflows, false,
922             "force overflows of marking deque by reducing it's size "
923             "to 64 words")
924 
925 DEFINE_BOOL(stress_compaction, false,
926             "stress the GC compactor to flush out bugs (implies "
927             "--force_marking_deque_overflows)")
928 
929 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
930             "Test mode only flag. It allows an unit test to select evacuation "
931             "candidates pages (requires --stress_compaction).")
932 
933 DEFINE_BOOL(disable_old_api_accessors, false,
934             "Disable old-style API accessors whose setters trigger through the "
935             "prototype chain")
936 
937 //
938 // Dev shell flags
939 //
940 
941 DEFINE_BOOL(help, false, "Print usage message, including flags, on console")
942 DEFINE_BOOL(dump_counters, false, "Dump counters on exit")
943 
944 DEFINE_STRING(map_counters, "", "Map counters to a file")
945 DEFINE_ARGS(js_arguments,
946             "Pass all remaining arguments to the script. Alias for \"--\".")
947 
948 //
949 // GDB JIT integration flags.
950 //
951 #undef FLAG
952 #ifdef ENABLE_GDB_JIT_INTERFACE
953 #define FLAG FLAG_FULL
954 #else
955 #define FLAG FLAG_READONLY
956 #endif
957 
958 DEFINE_BOOL(gdbjit, false, "enable GDBJIT interface")
959 DEFINE_BOOL(gdbjit_full, false, "enable GDBJIT interface for all code objects")
960 DEFINE_BOOL(gdbjit_dump, false, "dump elf objects with debug info to disk")
961 DEFINE_STRING(gdbjit_dump_filter, "",
962               "dump only objects containing this substring")
963 
964 #ifdef ENABLE_GDB_JIT_INTERFACE
965 DEFINE_IMPLICATION(gdbjit_full, gdbjit)
966 DEFINE_IMPLICATION(gdbjit_dump, gdbjit)
967 #endif
968 DEFINE_NEG_IMPLICATION(gdbjit, compact_code_space)
969 
970 //
971 // Debug only flags
972 //
973 #undef FLAG
974 #ifdef DEBUG
975 #define FLAG FLAG_FULL
976 #else
977 #define FLAG FLAG_READONLY
978 #endif
979 
980 // checks.cc
981 #ifdef ENABLE_SLOW_DCHECKS
982 DEFINE_BOOL(enable_slow_asserts, false,
983             "enable asserts that are slow to execute")
984 #endif
985 
986 // codegen-ia32.cc / codegen-arm.cc / macro-assembler-*.cc
987 DEFINE_BOOL(print_ast, false, "print source AST")
988 DEFINE_BOOL(print_builtin_ast, false, "print source AST for builtins")
989 DEFINE_BOOL(trap_on_abort, false, "replace aborts by breakpoints")
990 
991 // compiler.cc
992 DEFINE_BOOL(print_builtin_scopes, false, "print scopes for builtins")
993 DEFINE_BOOL(print_scopes, false, "print scopes")
994 
995 // contexts.cc
996 DEFINE_BOOL(trace_contexts, false, "trace contexts operations")
997 
998 // heap.cc
999 DEFINE_BOOL(gc_verbose, false, "print stuff during garbage collection")
1000 DEFINE_BOOL(heap_stats, false, "report heap statistics before and after GC")
1001 DEFINE_BOOL(code_stats, false, "report code statistics after GC")
1002 DEFINE_BOOL(print_handles, false, "report handles after GC")
1003 DEFINE_BOOL(check_handle_count, false,
1004             "Check that there are not too many handles at GC")
1005 DEFINE_BOOL(print_global_handles, false, "report global handles after GC")
1006 
1007 // TurboFan debug-only flags.
1008 DEFINE_BOOL(print_turbo_replay, false,
1009             "print C++ code to recreate TurboFan graphs")
1010 DEFINE_BOOL(trace_turbo_escape, false, "enable tracing in escape analysis")
1011 
1012 // objects.cc
1013 DEFINE_BOOL(trace_normalization, false,
1014             "prints when objects are turned into dictionaries.")
1015 
1016 // runtime.cc
1017 DEFINE_BOOL(trace_lazy, false, "trace lazy compilation")
1018 
1019 // spaces.cc
1020 DEFINE_BOOL(collect_heap_spill_statistics, false,
1021             "report heap spill statistics along with heap_stats "
1022             "(requires heap_stats)")
1023 DEFINE_BOOL(trace_live_bytes, false,
1024             "trace incrementing and resetting of live bytes")
1025 DEFINE_BOOL(trace_isolates, false, "trace isolate state changes")
1026 
1027 // Regexp
1028 DEFINE_BOOL(regexp_possessive_quantifier, false,
1029             "enable possessive quantifier syntax for testing")
1030 DEFINE_BOOL(trace_regexp_bytecodes, false, "trace regexp bytecode execution")
1031 DEFINE_BOOL(trace_regexp_assembler, false,
1032             "trace regexp macro assembler calls.")
1033 DEFINE_BOOL(trace_regexp_parser, false, "trace regexp parsing")
1034 
1035 // Debugger
1036 DEFINE_BOOL(print_break_location, false, "print source location on debug break")
1037 
1038 // wasm instance management
1039 DEFINE_BOOL(trace_wasm_instances, false,
1040             "trace creation and collection of wasm instances")
1041 
1042 //
1043 // Logging and profiling flags
1044 //
1045 #undef FLAG
1046 #define FLAG FLAG_FULL
1047 
1048 // log.cc
1049 DEFINE_BOOL(log, false,
1050             "Minimal logging (no API, code, GC, suspect, or handles samples).")
1051 DEFINE_BOOL(log_all, false, "Log all events to the log file.")
1052 DEFINE_BOOL(log_api, false, "Log API events to the log file.")
1053 DEFINE_BOOL(log_code, false,
1054             "Log code events to the log file without profiling.")
1055 DEFINE_BOOL(log_gc, false,
1056             "Log heap samples on garbage collection for the hp2ps tool.")
1057 DEFINE_BOOL(log_handles, false, "Log global handle events.")
1058 DEFINE_BOOL(log_suspect, false, "Log suspect operations.")
1059 DEFINE_BOOL(prof, false,
1060             "Log statistical profiling information (implies --log-code).")
1061 DEFINE_BOOL(prof_cpp, false, "Like --prof, but ignore generated code.")
1062 DEFINE_IMPLICATION(prof, prof_cpp)
1063 DEFINE_BOOL(prof_browser_mode, true,
1064             "Used with --prof, turns on browser-compatible mode for profiling.")
1065 DEFINE_STRING(logfile, "v8.log", "Specify the name of the log file.")
1066 DEFINE_BOOL(logfile_per_isolate, true, "Separate log files for each isolate.")
1067 DEFINE_BOOL(ll_prof, false, "Enable low-level linux profiler.")
1068 DEFINE_BOOL(perf_basic_prof, false,
1069             "Enable perf linux profiler (basic support).")
1070 DEFINE_NEG_IMPLICATION(perf_basic_prof, compact_code_space)
1071 DEFINE_BOOL(perf_basic_prof_only_functions, false,
1072             "Only report function code ranges to perf (i.e. no stubs).")
1073 DEFINE_IMPLICATION(perf_basic_prof_only_functions, perf_basic_prof)
1074 DEFINE_BOOL(perf_prof, false,
1075             "Enable perf linux profiler (experimental annotate support).")
1076 DEFINE_NEG_IMPLICATION(perf_prof, compact_code_space)
1077 DEFINE_BOOL(perf_prof_debug_info, false,
1078             "Enable debug info for perf linux profiler (experimental).")
1079 DEFINE_BOOL(perf_prof_unwinding_info, false,
1080             "Enable unwinding info for perf linux profiler (experimental).")
1081 DEFINE_STRING(gc_fake_mmap, "/tmp/__v8_gc__",
1082               "Specify the name of the file for fake gc mmap used in ll_prof")
1083 DEFINE_BOOL(log_internal_timer_events, false, "Time internal events.")
1084 DEFINE_BOOL(log_timer_events, false,
1085             "Time events including external callbacks.")
1086 DEFINE_IMPLICATION(log_timer_events, log_internal_timer_events)
1087 DEFINE_IMPLICATION(log_internal_timer_events, prof)
1088 DEFINE_BOOL(log_instruction_stats, false, "Log AArch64 instruction statistics.")
1089 DEFINE_STRING(log_instruction_file, "arm64_inst.csv",
1090               "AArch64 instruction statistics log file.")
1091 DEFINE_INT(log_instruction_period, 1 << 22,
1092            "AArch64 instruction statistics logging period.")
1093 
1094 DEFINE_BOOL(redirect_code_traces, false,
1095             "output deopt information and disassembly into file "
1096             "code-<pid>-<isolate id>.asm")
1097 DEFINE_STRING(redirect_code_traces_to, NULL,
1098               "output deopt information and disassembly into the given file")
1099 
1100 DEFINE_BOOL(hydrogen_track_positions, false,
1101             "track source code positions when building IR")
1102 
1103 //
1104 // Disassembler only flags
1105 //
1106 #undef FLAG
1107 #ifdef ENABLE_DISASSEMBLER
1108 #define FLAG FLAG_FULL
1109 #else
1110 #define FLAG FLAG_READONLY
1111 #endif
1112 
1113 // elements.cc
1114 DEFINE_BOOL(trace_elements_transitions, false, "trace elements transitions")
1115 
1116 DEFINE_BOOL(trace_creation_allocation_sites, false,
1117             "trace the creation of allocation sites")
1118 
1119 // code-stubs.cc
1120 DEFINE_BOOL(print_code_stubs, false, "print code stubs")
1121 DEFINE_BOOL(test_secondary_stub_cache, false,
1122             "test secondary stub cache by disabling the primary one")
1123 
1124 DEFINE_BOOL(test_primary_stub_cache, false,
1125             "test primary stub cache by disabling the secondary one")
1126 
1127 
1128 // codegen-ia32.cc / codegen-arm.cc
1129 DEFINE_BOOL(print_code, false, "print generated code")
1130 DEFINE_BOOL(print_opt_code, false, "print optimized code")
1131 DEFINE_STRING(print_opt_code_filter, "*", "filter for printing optimized code")
1132 DEFINE_BOOL(print_unopt_code, false,
1133             "print unoptimized code before "
1134             "printing optimized code based on it")
1135 DEFINE_BOOL(print_code_verbose, false, "print more information for code")
1136 DEFINE_BOOL(print_builtin_code, false, "print generated code for builtins")
1137 
1138 #ifdef ENABLE_DISASSEMBLER
1139 DEFINE_BOOL(sodium, false,
1140             "print generated code output suitable for use with "
1141             "the Sodium code viewer")
1142 
1143 DEFINE_IMPLICATION(sodium, print_code_stubs)
1144 DEFINE_IMPLICATION(sodium, print_code)
1145 DEFINE_IMPLICATION(sodium, print_opt_code)
1146 DEFINE_IMPLICATION(sodium, hydrogen_track_positions)
1147 DEFINE_IMPLICATION(sodium, code_comments)
1148 
1149 DEFINE_BOOL(print_all_code, false, "enable all flags related to printing code")
1150 DEFINE_IMPLICATION(print_all_code, print_code)
1151 DEFINE_IMPLICATION(print_all_code, print_opt_code)
1152 DEFINE_IMPLICATION(print_all_code, print_unopt_code)
1153 DEFINE_IMPLICATION(print_all_code, print_code_verbose)
1154 DEFINE_IMPLICATION(print_all_code, print_builtin_code)
1155 DEFINE_IMPLICATION(print_all_code, print_code_stubs)
1156 DEFINE_IMPLICATION(print_all_code, code_comments)
1157 #ifdef DEBUG
1158 DEFINE_IMPLICATION(print_all_code, trace_codegen)
1159 #endif
1160 #endif
1161 
1162 #undef FLAG
1163 #define FLAG FLAG_FULL
1164 
1165 //
1166 // Predictable mode related flags.
1167 //
1168 
1169 DEFINE_BOOL(predictable, false, "enable predictable mode")
1170 DEFINE_IMPLICATION(predictable, single_threaded)
1171 DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
1172 
1173 //
1174 // Threading related flags.
1175 //
1176 
1177 DEFINE_BOOL(single_threaded, false, "disable the use of background tasks")
1178 DEFINE_NEG_IMPLICATION(single_threaded, concurrent_recompilation)
1179 DEFINE_NEG_IMPLICATION(single_threaded, concurrent_sweeping)
1180 DEFINE_NEG_IMPLICATION(single_threaded, parallel_compaction)
1181 
1182 
1183 #undef FLAG
1184 
1185 #ifdef VERIFY_PREDICTABLE
1186 #define FLAG FLAG_FULL
1187 #else
1188 #define FLAG FLAG_READONLY
1189 #endif
1190 
1191 DEFINE_BOOL(verify_predictable, false,
1192             "this mode is used for checking that V8 behaves predictably")
1193 DEFINE_INT(dump_allocations_digest_at_alloc, -1,
1194            "dump allocations digest each n-th allocation")
1195 
1196 //
1197 // Read-only flags
1198 //
1199 #undef FLAG
1200 #define FLAG FLAG_READONLY
1201 
1202 // assembler.h
1203 DEFINE_BOOL(enable_embedded_constant_pool, V8_EMBEDDED_CONSTANT_POOL,
1204             "enable use of embedded constant pools (ARM/PPC only)")
1205 
1206 DEFINE_BOOL(unbox_double_fields, V8_DOUBLE_FIELDS_UNBOXING,
1207             "enable in-object double fields unboxing (64-bit only)")
1208 DEFINE_IMPLICATION(unbox_double_fields, track_double_fields)
1209 
1210 // Cleanup...
1211 #undef FLAG_FULL
1212 #undef FLAG_READONLY
1213 #undef FLAG
1214 #undef FLAG_ALIAS
1215 
1216 #undef DEFINE_BOOL
1217 #undef DEFINE_MAYBE_BOOL
1218 #undef DEFINE_INT
1219 #undef DEFINE_STRING
1220 #undef DEFINE_FLOAT
1221 #undef DEFINE_ARGS
1222 #undef DEFINE_IMPLICATION
1223 #undef DEFINE_NEG_IMPLICATION
1224 #undef DEFINE_NEG_VALUE_IMPLICATION
1225 #undef DEFINE_VALUE_IMPLICATION
1226 #undef DEFINE_ALIAS_BOOL
1227 #undef DEFINE_ALIAS_INT
1228 #undef DEFINE_ALIAS_STRING
1229 #undef DEFINE_ALIAS_FLOAT
1230 #undef DEFINE_ALIAS_ARGS
1231 
1232 #undef FLAG_MODE_DECLARE
1233 #undef FLAG_MODE_DEFINE
1234 #undef FLAG_MODE_DEFINE_DEFAULTS
1235 #undef FLAG_MODE_META
1236 #undef FLAG_MODE_DEFINE_IMPLICATIONS
1237 
1238 #undef COMMA
1239