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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 #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) extern ctype FLAG_##nam;
     27 #define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
     28   static ctype const FLAG_##nam = def;
     29 
     30 // We want to supply the actual storage and value for the flag variable in the
     31 // .cc file.  We only do this for writable flags.
     32 #elif defined(FLAG_MODE_DEFINE)
     33 #define FLAG_FULL(ftype, ctype, nam, def, cmt) ctype FLAG_##nam = def;
     34 
     35 // We need to define all of our default values so that the Flag structure can
     36 // access them by pointer.  These are just used internally inside of one .cc,
     37 // for MODE_META, so there is no impact on the flags interface.
     38 #elif defined(FLAG_MODE_DEFINE_DEFAULTS)
     39 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
     40   static ctype const FLAGDEFAULT_##nam = def;
     41 
     42 // We want to write entries into our meta data table, for internal parsing and
     43 // printing / etc in the flag parser code.  We only do this for writable flags.
     44 #elif defined(FLAG_MODE_META)
     45 #define FLAG_FULL(ftype, ctype, nam, def, cmt)                              \
     46   { Flag::TYPE_##ftype, #nam, &FLAG_##nam, &FLAGDEFAULT_##nam, cmt, false } \
     47   ,
     48 #define FLAG_ALIAS(ftype, ctype, alias, nam)                     \
     49   {                                                              \
     50     Flag::TYPE_##ftype, #alias, &FLAG_##nam, &FLAGDEFAULT_##nam, \
     51         "alias for --" #nam, false                               \
     52   }                                                              \
     53   ,
     54 
     55 // We produce the code to set flags when it is implied by another flag.
     56 #elif defined(FLAG_MODE_DEFINE_IMPLICATIONS)
     57 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value) \
     58   if (FLAG_##whenflag) FLAG_##thenflag = value;
     59 
     60 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value) \
     61   if (!FLAG_##whenflag) FLAG_##thenflag = value;
     62 
     63 #else
     64 #error No mode supplied when including flags.defs
     65 #endif
     66 
     67 // Dummy defines for modes where it is not relevant.
     68 #ifndef FLAG_FULL
     69 #define FLAG_FULL(ftype, ctype, nam, def, cmt)
     70 #endif
     71 
     72 #ifndef FLAG_READONLY
     73 #define FLAG_READONLY(ftype, ctype, nam, def, cmt)
     74 #endif
     75 
     76 #ifndef FLAG_ALIAS
     77 #define FLAG_ALIAS(ftype, ctype, alias, nam)
     78 #endif
     79 
     80 #ifndef DEFINE_VALUE_IMPLICATION
     81 #define DEFINE_VALUE_IMPLICATION(whenflag, thenflag, value)
     82 #endif
     83 
     84 #ifndef DEFINE_NEG_VALUE_IMPLICATION
     85 #define DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, value)
     86 #endif
     87 
     88 #define COMMA ,
     89 
     90 #ifdef FLAG_MODE_DECLARE
     91 // Structure used to hold a collection of arguments to the JavaScript code.
     92 struct JSArguments {
     93  public:
     94   inline const char*& operator[](int idx) const { return argv[idx]; }
     95   static JSArguments Create(int argc, const char** argv) {
     96     JSArguments args;
     97     args.argc = argc;
     98     args.argv = argv;
     99     return args;
    100   }
    101   int argc;
    102   const char** argv;
    103 };
    104 
    105 struct MaybeBoolFlag {
    106   static MaybeBoolFlag Create(bool has_value, bool value) {
    107     MaybeBoolFlag flag;
    108     flag.has_value = has_value;
    109     flag.value = value;
    110     return flag;
    111   }
    112   bool has_value;
    113   bool value;
    114 };
    115 #endif
    116 
    117 #ifdef DEBUG
    118 #define DEBUG_BOOL true
    119 #else
    120 #define DEBUG_BOOL false
    121 #endif
    122 #if (defined CAN_USE_VFP3_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
    123 #define ENABLE_VFP3_DEFAULT true
    124 #else
    125 #define ENABLE_VFP3_DEFAULT false
    126 #endif
    127 #if (defined CAN_USE_ARMV7_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
    128 #define ENABLE_ARMV7_DEFAULT true
    129 #else
    130 #define ENABLE_ARMV7_DEFAULT false
    131 #endif
    132 #if (defined CAN_USE_ARMV8_INSTRUCTIONS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
    133 #define ENABLE_ARMV8_DEFAULT true
    134 #else
    135 #define ENABLE_ARMV8_DEFAULT false
    136 #endif
    137 #if (defined CAN_USE_VFP32DREGS) || !(defined ARM_TEST_NO_FEATURE_PROBE)
    138 #define ENABLE_32DREGS_DEFAULT true
    139 #else
    140 #define ENABLE_32DREGS_DEFAULT false
    141 #endif
    142 #if (defined CAN_USE_NEON) || !(defined ARM_TEST_NO_FEATURE_PROBE)
    143 # define ENABLE_NEON_DEFAULT true
    144 #else
    145 # define ENABLE_NEON_DEFAULT false
    146 #endif
    147 
    148 #define DEFINE_BOOL(nam, def, cmt) FLAG(BOOL, bool, nam, def, cmt)
    149 #define DEFINE_BOOL_READONLY(nam, def, cmt) \
    150   FLAG_READONLY(BOOL, bool, nam, def, cmt)
    151 #define DEFINE_MAYBE_BOOL(nam, cmt) \
    152   FLAG(MAYBE_BOOL, MaybeBoolFlag, nam, {false COMMA false}, cmt)
    153 #define DEFINE_INT(nam, def, cmt) FLAG(INT, int, nam, def, cmt)
    154 #define DEFINE_FLOAT(nam, def, cmt) FLAG(FLOAT, double, nam, def, cmt)
    155 #define DEFINE_STRING(nam, def, cmt) FLAG(STRING, const char*, nam, def, cmt)
    156 #define DEFINE_ARGS(nam, cmt) FLAG(ARGS, JSArguments, nam, {0 COMMA NULL}, cmt)
    157 
    158 #define DEFINE_ALIAS_BOOL(alias, nam) FLAG_ALIAS(BOOL, bool, alias, nam)
    159 #define DEFINE_ALIAS_INT(alias, nam) FLAG_ALIAS(INT, int, alias, nam)
    160 #define DEFINE_ALIAS_FLOAT(alias, nam) FLAG_ALIAS(FLOAT, double, alias, nam)
    161 #define DEFINE_ALIAS_STRING(alias, nam) \
    162   FLAG_ALIAS(STRING, const char*, alias, nam)
    163 #define DEFINE_ALIAS_ARGS(alias, nam) FLAG_ALIAS(ARGS, JSArguments, alias, nam)
    164 
    165 //
    166 // Flags in all modes.
    167 //
    168 #define FLAG FLAG_FULL
    169 
    170 DEFINE_BOOL(experimental_extras, false,
    171             "enable code compiled in via v8_experimental_extra_library_files")
    172 
    173 // Flags for language modes and experimental language features.
    174 DEFINE_BOOL(use_strict, false, "enforce strict mode")
    175 DEFINE_BOOL(use_strong, false, "enforce strong mode")
    176 DEFINE_IMPLICATION(use_strong, use_strict)
    177 
    178 DEFINE_BOOL(strong_mode, false, "experimental strong language mode")
    179 DEFINE_IMPLICATION(use_strong, strong_mode)
    180 DEFINE_BOOL(strong_this, true, "don't allow 'this' to escape from constructors")
    181 
    182 DEFINE_BOOL(es_staging, false,
    183             "enable test-worthy harmony features (for internal use only)")
    184 DEFINE_BOOL(harmony, false, "enable all completed harmony features")
    185 DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
    186 DEFINE_IMPLICATION(es_staging, harmony)
    187 
    188 DEFINE_BOOL(legacy_const, false, "legacy semantics for const in sloppy mode")
    189 // ES2015 const semantics are shipped
    190 DEFINE_NEG_VALUE_IMPLICATION(harmony_shipping, legacy_const, true)
    191 
    192 DEFINE_BOOL(promise_extra, true, "additional V8 Promise functions")
    193 // Removing extra Promise functions is staged
    194 DEFINE_NEG_IMPLICATION(harmony, promise_extra)
    195 
    196 // Activate on ClusterFuzz.
    197 DEFINE_IMPLICATION(es_staging, harmony_regexp_lookbehind)
    198 DEFINE_IMPLICATION(es_staging, move_object_start)
    199 
    200 // Features that are still work in progress (behind individual flags).
    201 #define HARMONY_INPROGRESS(V)                                 \
    202   V(harmony_modules, "harmony modules")                       \
    203   V(harmony_unicode_regexps, "harmony unicode regexps")       \
    204   V(harmony_function_name, "harmony Function name inference") \
    205   V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")   \
    206   V(harmony_simd, "harmony simd")                             \
    207   V(harmony_do_expressions, "harmony do-expressions")         \
    208   V(harmony_regexp_subclass, "harmony regexp subclassing")    \
    209   V(harmony_species, "harmony Symbol.species")
    210 
    211 // Features that are complete (but still behind --harmony/es-staging flag).
    212 #define HARMONY_STAGED(V)                                                 \
    213   V(harmony_regexp_lookbehind, "harmony regexp lookbehind")
    214 
    215 // Features that are shipping (turned on by default, but internal flag remains).
    216 #define HARMONY_SHIPPING(V)                                               \
    217   V(harmony_default_parameters, "harmony default parameters")             \
    218   V(harmony_destructuring_assignment, "harmony destructuring assignment") \
    219   V(harmony_destructuring_bind, "harmony destructuring bind")             \
    220   V(harmony_concat_spreadable, "harmony isConcatSpreadable")              \
    221   V(harmony_object_observe, "harmony Object.observe")                     \
    222   V(harmony_tolength, "harmony ToLength")                                 \
    223   V(harmony_tostring, "harmony toString")                                 \
    224   V(harmony_completion, "harmony completion value semantics")             \
    225   V(harmony_regexps, "harmony regular expression extensions")             \
    226   V(harmony_sloppy, "harmony features in sloppy mode")                    \
    227   V(harmony_sloppy_let, "harmony let in sloppy mode")                     \
    228   V(harmony_sloppy_function, "harmony sloppy function block scoping")     \
    229   V(harmony_proxies, "harmony proxies")                                   \
    230   V(harmony_reflect, "harmony Reflect API")
    231 
    232 
    233 // Once a shipping feature has proved stable in the wild, it will be dropped
    234 // from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,
    235 // and associated tests are moved from the harmony directory to the appropriate
    236 // esN directory.
    237 
    238 
    239 #define FLAG_INPROGRESS_FEATURES(id, description) \
    240   DEFINE_BOOL(id, false, "enable " #description " (in progress)")
    241 HARMONY_INPROGRESS(FLAG_INPROGRESS_FEATURES)
    242 #undef FLAG_INPROGRESS_FEATURES
    243 
    244 #define FLAG_STAGED_FEATURES(id, description) \
    245   DEFINE_BOOL(id, false, "enable " #description) \
    246   DEFINE_IMPLICATION(harmony, id)
    247 HARMONY_STAGED(FLAG_STAGED_FEATURES)
    248 #undef FLAG_STAGED_FEATURES
    249 
    250 #define FLAG_SHIPPING_FEATURES(id, description) \
    251   DEFINE_BOOL(id, true, "enable " #description) \
    252   DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
    253 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
    254 #undef FLAG_SHIPPING_FEATURES
    255 
    256 
    257 // Feature dependencies.
    258 DEFINE_IMPLICATION(harmony_sloppy_let, harmony_sloppy)
    259 DEFINE_IMPLICATION(harmony_sloppy_function, harmony_sloppy)
    260 
    261 // Destructuring shares too much parsing architecture with default parameters
    262 // to be enabled on its own.
    263 DEFINE_IMPLICATION(harmony_destructuring_bind, harmony_default_parameters)
    264 
    265 // Flags for experimental implementation features.
    266 DEFINE_BOOL(compiled_keyed_generic_loads, false,
    267             "use optimizing compiler to generate keyed generic load stubs")
    268 DEFINE_BOOL(allocation_site_pretenuring, true,
    269             "pretenure with allocation sites")
    270 DEFINE_BOOL(trace_pretenuring, false,
    271             "trace pretenuring decisions of HAllocate instructions")
    272 DEFINE_BOOL(trace_pretenuring_statistics, false,
    273             "trace allocation site pretenuring statistics")
    274 DEFINE_BOOL(track_fields, true, "track fields with only smi values")
    275 DEFINE_BOOL(track_double_fields, true, "track fields with double values")
    276 DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
    277 DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
    278 DEFINE_IMPLICATION(track_double_fields, track_fields)
    279 DEFINE_IMPLICATION(track_heap_object_fields, track_fields)
    280 DEFINE_IMPLICATION(track_computed_fields, track_fields)
    281 DEFINE_BOOL(track_field_types, true, "track field types")
    282 DEFINE_IMPLICATION(track_field_types, track_fields)
    283 DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
    284 DEFINE_BOOL(smi_binop, true, "support smi representation in binary operations")
    285 
    286 // Flags for optimization types.
    287 DEFINE_BOOL(optimize_for_size, false,
    288             "Enables optimizations which favor memory size over execution "
    289             "speed")
    290 
    291 DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
    292 
    293 // Flags for data representation optimizations
    294 DEFINE_BOOL(unbox_double_arrays, true, "automatically unbox arrays of doubles")
    295 DEFINE_BOOL(string_slices, true, "use string slices")
    296 
    297 // Flags for Ignition.
    298 DEFINE_BOOL(ignition, false, "use ignition interpreter")
    299 DEFINE_STRING(ignition_filter, "*", "filter for ignition interpreter")
    300 DEFINE_BOOL(ignition_fake_try_catch, false,
    301             "enable fake try-catch-finally blocks in ignition for testing")
    302 DEFINE_BOOL(ignition_fallback_on_eval_and_catch, false,
    303             "fallback to full-codegen for functions which contain eval, catch"
    304             "and es6 blocks")
    305 DEFINE_BOOL(print_bytecode, false,
    306             "print bytecode generated by ignition interpreter")
    307 DEFINE_BOOL(trace_ignition_codegen, false,
    308             "trace the codegen of ignition interpreter bytecode handlers")
    309 
    310 // Flags for Crankshaft.
    311 DEFINE_BOOL(crankshaft, true, "use crankshaft")
    312 DEFINE_STRING(hydrogen_filter, "*", "optimization filter")
    313 DEFINE_BOOL(use_gvn, true, "use hydrogen global value numbering")
    314 DEFINE_INT(gvn_iterations, 3, "maximum number of GVN fix-point iterations")
    315 DEFINE_BOOL(use_canonicalizing, true, "use hydrogen instruction canonicalizing")
    316 DEFINE_BOOL(use_inlining, true, "use function inlining")
    317 DEFINE_BOOL(use_escape_analysis, true, "use hydrogen escape analysis")
    318 DEFINE_BOOL(use_allocation_folding, true, "use allocation folding")
    319 DEFINE_BOOL(use_local_allocation_folding, false, "only fold in basic blocks")
    320 DEFINE_BOOL(use_write_barrier_elimination, true,
    321             "eliminate write barriers targeting allocations in optimized code")
    322 DEFINE_INT(max_inlining_levels, 5, "maximum number of inlining levels")
    323 DEFINE_INT(max_inlined_source_size, 600,
    324            "maximum source size in bytes considered for a single inlining")
    325 DEFINE_INT(max_inlined_nodes, 196,
    326            "maximum number of AST nodes considered for a single inlining")
    327 DEFINE_INT(max_inlined_nodes_cumulative, 400,
    328            "maximum cumulative number of AST nodes considered for inlining")
    329 DEFINE_BOOL(loop_invariant_code_motion, true, "loop invariant code motion")
    330 DEFINE_BOOL(fast_math, true, "faster (but maybe less accurate) math functions")
    331 DEFINE_BOOL(collect_megamorphic_maps_from_stub_cache, true,
    332             "crankshaft harvests type feedback from stub cache")
    333 DEFINE_BOOL(hydrogen_stats, false, "print statistics for hydrogen")
    334 DEFINE_BOOL(trace_check_elimination, false, "trace check elimination phase")
    335 DEFINE_BOOL(trace_environment_liveness, false,
    336             "trace liveness of local variable slots")
    337 DEFINE_BOOL(trace_hydrogen, false, "trace generated hydrogen to file")
    338 DEFINE_STRING(trace_hydrogen_filter, "*", "hydrogen tracing filter")
    339 DEFINE_BOOL(trace_hydrogen_stubs, false, "trace generated hydrogen for stubs")
    340 DEFINE_STRING(trace_hydrogen_file, NULL, "trace hydrogen to given file name")
    341 DEFINE_STRING(trace_phase, "HLZ", "trace generated IR for specified phases")
    342 DEFINE_BOOL(trace_inlining, false, "trace inlining decisions")
    343 DEFINE_BOOL(trace_load_elimination, false, "trace load elimination")
    344 DEFINE_BOOL(trace_store_elimination, false, "trace store elimination")
    345 DEFINE_BOOL(trace_alloc, false, "trace register allocator")
    346 DEFINE_BOOL(trace_all_uses, false, "trace all use positions")
    347 DEFINE_BOOL(trace_range, false, "trace range analysis")
    348 DEFINE_BOOL(trace_gvn, false, "trace global value numbering")
    349 DEFINE_BOOL(trace_representation, false, "trace representation types")
    350 DEFINE_BOOL(trace_removable_simulates, false, "trace removable simulates")
    351 DEFINE_BOOL(trace_escape_analysis, false, "trace hydrogen escape analysis")
    352 DEFINE_BOOL(trace_allocation_folding, false, "trace allocation folding")
    353 DEFINE_BOOL(trace_track_allocation_sites, false,
    354             "trace the tracking of allocation sites")
    355 DEFINE_BOOL(trace_migration, false, "trace object migration")
    356 DEFINE_BOOL(trace_generalization, false, "trace map generalization")
    357 DEFINE_BOOL(stress_pointer_maps, false, "pointer map for every instruction")
    358 DEFINE_BOOL(stress_environments, false, "environment for every instruction")
    359 DEFINE_INT(deopt_every_n_times, 0,
    360            "deoptimize every n times a deopt point is passed")
    361 DEFINE_INT(deopt_every_n_garbage_collections, 0,
    362            "deoptimize every n garbage collections")
    363 DEFINE_BOOL(print_deopt_stress, false, "print number of possible deopt points")
    364 DEFINE_BOOL(trap_on_deopt, false, "put a break point before deoptimizing")
    365 DEFINE_BOOL(trap_on_stub_deopt, false,
    366             "put a break point before deoptimizing a stub")
    367 DEFINE_BOOL(deoptimize_uncommon_cases, true, "deoptimize uncommon cases")
    368 DEFINE_BOOL(polymorphic_inlining, true, "polymorphic inlining")
    369 DEFINE_BOOL(use_osr, true, "use on-stack replacement")
    370 DEFINE_BOOL(array_bounds_checks_elimination, true,
    371             "perform array bounds checks elimination")
    372 DEFINE_BOOL(trace_bce, false, "trace array bounds check elimination")
    373 DEFINE_BOOL(array_bounds_checks_hoisting, false,
    374             "perform array bounds checks hoisting")
    375 DEFINE_BOOL(array_index_dehoisting, true, "perform array index dehoisting")
    376 DEFINE_BOOL(analyze_environment_liveness, true,
    377             "analyze liveness of environment slots and zap dead values")
    378 DEFINE_BOOL(load_elimination, true, "use load elimination")
    379 DEFINE_BOOL(check_elimination, true, "use check elimination")
    380 DEFINE_BOOL(store_elimination, false, "use store elimination")
    381 DEFINE_BOOL(dead_code_elimination, true, "use dead code elimination")
    382 DEFINE_BOOL(fold_constants, true, "use constant folding")
    383 DEFINE_BOOL(trace_dead_code_elimination, false, "trace dead code elimination")
    384 DEFINE_BOOL(unreachable_code_elimination, true, "eliminate unreachable code")
    385 DEFINE_BOOL(trace_osr, false, "trace on-stack replacement")
    386 DEFINE_INT(stress_runs, 0, "number of stress runs")
    387 DEFINE_BOOL(lookup_sample_by_shared, true,
    388             "when picking a function to optimize, watch for shared function "
    389             "info, not JSFunction itself")
    390 DEFINE_BOOL(flush_optimized_code_cache, false,
    391             "flushes the cache of optimized code for closures on every GC")
    392 DEFINE_BOOL(inline_construct, true, "inline constructor calls")
    393 DEFINE_BOOL(inline_arguments, true, "inline functions with arguments object")
    394 DEFINE_BOOL(inline_accessors, true, "inline JavaScript accessors")
    395 DEFINE_INT(escape_analysis_iterations, 2,
    396            "maximum number of escape analysis fix-point iterations")
    397 
    398 DEFINE_BOOL(optimize_for_in, true, "optimize functions containing for-in loops")
    399 
    400 DEFINE_BOOL(concurrent_recompilation, true,
    401             "optimizing hot functions asynchronously on a separate thread")
    402 DEFINE_BOOL(trace_concurrent_recompilation, false,
    403             "track concurrent recompilation")
    404 DEFINE_INT(concurrent_recompilation_queue_length, 8,
    405            "the length of the concurrent compilation queue")
    406 DEFINE_INT(concurrent_recompilation_delay, 0,
    407            "artificial compilation delay in ms")
    408 DEFINE_BOOL(block_concurrent_recompilation, false,
    409             "block queued jobs until released")
    410 DEFINE_BOOL(concurrent_osr, false, "concurrent on-stack replacement")
    411 DEFINE_IMPLICATION(concurrent_osr, concurrent_recompilation)
    412 
    413 DEFINE_BOOL(omit_map_checks_for_leaf_maps, true,
    414             "do not emit check maps for constant values that have a leaf map, "
    415             "deoptimize the optimized code if the layout of the maps changes.")
    416 
    417 // Flags for TurboFan.
    418 DEFINE_BOOL(turbo, false, "enable TurboFan compiler")
    419 DEFINE_IMPLICATION(turbo, turbo_asm_deoptimization)
    420 DEFINE_IMPLICATION(turbo, turbo_inlining)
    421 DEFINE_BOOL(turbo_shipping, true, "enable TurboFan compiler on subset")
    422 DEFINE_BOOL(turbo_greedy_regalloc, false, "use the greedy register allocator")
    423 DEFINE_BOOL(turbo_sp_frame_access, false,
    424             "use stack pointer-relative access to frame wherever possible")
    425 DEFINE_BOOL(turbo_preprocess_ranges, true,
    426             "run pre-register allocation heuristics")
    427 DEFINE_BOOL(turbo_loop_stackcheck, true, "enable stack checks in loops")
    428 DEFINE_STRING(turbo_filter, "~~", "optimization filter for TurboFan compiler")
    429 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
    430 DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
    431 DEFINE_IMPLICATION(trace_turbo_graph, trace_turbo)
    432 DEFINE_STRING(trace_turbo_cfg_file, NULL,
    433               "trace turbo cfg graph (for C1 visualizer) to a given file name")
    434 DEFINE_BOOL(trace_turbo_types, true, "trace TurboFan's types")
    435 DEFINE_BOOL(trace_turbo_scheduler, false, "trace TurboFan's scheduler")
    436 DEFINE_BOOL(trace_turbo_reduction, false, "trace TurboFan's various reducers")
    437 DEFINE_BOOL(trace_turbo_jt, false, "trace TurboFan's jump threading")
    438 DEFINE_BOOL(trace_turbo_ceq, false, "trace TurboFan's control equivalence")
    439 DEFINE_BOOL(turbo_asm, true, "enable TurboFan for asm.js code")
    440 DEFINE_BOOL(turbo_asm_deoptimization, false,
    441             "enable deoptimization in TurboFan for asm.js code")
    442 DEFINE_BOOL(turbo_verify, DEBUG_BOOL, "verify TurboFan graphs at each phase")
    443 DEFINE_BOOL(turbo_stats, false, "print TurboFan statistics")
    444 DEFINE_BOOL(turbo_splitting, true, "split nodes during scheduling in TurboFan")
    445 DEFINE_BOOL(turbo_types, true, "use typed lowering in TurboFan")
    446 DEFINE_BOOL(turbo_source_positions, false,
    447             "track source code positions when building TurboFan IR")
    448 DEFINE_IMPLICATION(trace_turbo, turbo_source_positions)
    449 DEFINE_BOOL(function_context_specialization, false,
    450             "enable function context specialization in TurboFan")
    451 DEFINE_BOOL(native_context_specialization, true,
    452             "enable native context specialization in TurboFan")
    453 DEFINE_BOOL(turbo_inlining, false, "enable inlining in TurboFan")
    454 DEFINE_BOOL(trace_turbo_inlining, false, "trace TurboFan inlining")
    455 DEFINE_BOOL(loop_assignment_analysis, true, "perform loop assignment analysis")
    456 DEFINE_BOOL(turbo_profiling, false, "enable profiling in TurboFan")
    457 DEFINE_BOOL(turbo_verify_allocation, DEBUG_BOOL,
    458             "verify register allocation in TurboFan")
    459 DEFINE_BOOL(turbo_move_optimization, true, "optimize gap moves in TurboFan")
    460 DEFINE_BOOL(turbo_jt, true, "enable jump threading in TurboFan")
    461 DEFINE_BOOL(turbo_osr, true, "enable OSR in TurboFan")
    462 DEFINE_BOOL(turbo_try_finally, false, "enable try-finally support in TurboFan")
    463 DEFINE_BOOL(turbo_stress_loop_peeling, false,
    464             "stress loop peeling optimization")
    465 DEFINE_BOOL(turbo_cf_optimization, true, "optimize control flow in TurboFan")
    466 DEFINE_BOOL(turbo_frame_elision, true, "elide frames in TurboFan")
    467 DEFINE_BOOL(turbo_cache_shared_code, true, "cache context-independent code")
    468 DEFINE_BOOL(turbo_preserve_shared_code, false, "keep context-independent code")
    469 DEFINE_BOOL(turbo_escape, false, "enable escape analysis")
    470 DEFINE_BOOL(trace_turbo_escape, false, "enable tracing in escape analysis")
    471 DEFINE_BOOL(turbo_instruction_scheduling, false,
    472             "enable instruction scheduling in TurboFan")
    473 
    474 // Flags for native WebAssembly.
    475 DEFINE_BOOL(expose_wasm, false, "expose WASM interface to JavaScript")
    476 DEFINE_BOOL(trace_wasm_decoder, false, "trace decoding of wasm code")
    477 DEFINE_BOOL(trace_wasm_decode_time, false, "trace decoding time of wasm code")
    478 DEFINE_BOOL(trace_wasm_compiler, false, "trace compiling of wasm code")
    479 DEFINE_BOOL(wasm_break_on_decoder_error, false,
    480             "debug break when wasm decoder encounters an error")
    481 
    482 DEFINE_INT(typed_array_max_size_in_heap, 64,
    483            "threshold for in-heap typed array")
    484 
    485 // Profiler flags.
    486 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")
    487 // 0x1800 fits in the immediate field of an ARM instruction.
    488 DEFINE_INT(interrupt_budget, 0x1800,
    489            "execution budget before interrupt is triggered")
    490 DEFINE_INT(type_info_threshold, 25,
    491            "percentage of ICs that must have type info to allow optimization")
    492 DEFINE_INT(generic_ic_threshold, 30,
    493            "max percentage of megamorphic/generic ICs to allow optimization")
    494 DEFINE_INT(self_opt_count, 130, "call count before self-optimization")
    495 
    496 DEFINE_BOOL(trace_opt_verbose, false, "extra verbose compilation tracing")
    497 DEFINE_IMPLICATION(trace_opt_verbose, trace_opt)
    498 
    499 // assembler-ia32.cc / assembler-arm.cc / assembler-x64.cc
    500 DEFINE_BOOL(debug_code, false, "generate extra code (assertions) for debugging")
    501 DEFINE_BOOL(code_comments, false, "emit comments in code disassembly")
    502 DEFINE_BOOL(enable_sse3, true, "enable use of SSE3 instructions if available")
    503 DEFINE_BOOL(enable_sse4_1, true,
    504             "enable use of SSE4.1 instructions if available")
    505 DEFINE_BOOL(enable_sahf, true,
    506             "enable use of SAHF instruction if available (X64 only)")
    507 DEFINE_BOOL(enable_avx, true, "enable use of AVX instructions if available")
    508 DEFINE_BOOL(enable_fma3, true, "enable use of FMA3 instructions if available")
    509 DEFINE_BOOL(enable_bmi1, true, "enable use of BMI1 instructions if available")
    510 DEFINE_BOOL(enable_bmi2, true, "enable use of BMI2 instructions if available")
    511 DEFINE_BOOL(enable_lzcnt, true, "enable use of LZCNT instruction if available")
    512 DEFINE_BOOL(enable_popcnt, true,
    513             "enable use of POPCNT instruction if available")
    514 DEFINE_BOOL(enable_vfp3, ENABLE_VFP3_DEFAULT,
    515             "enable use of VFP3 instructions if available")
    516 DEFINE_BOOL(enable_armv7, ENABLE_ARMV7_DEFAULT,
    517             "enable use of ARMv7 instructions if available (ARM only)")
    518 DEFINE_BOOL(enable_armv8, ENABLE_ARMV8_DEFAULT,
    519             "enable use of ARMv8 instructions if available (ARM 32-bit only)")
    520 DEFINE_BOOL(enable_neon, ENABLE_NEON_DEFAULT,
    521             "enable use of NEON instructions if available (ARM only)")
    522 DEFINE_BOOL(enable_sudiv, true,
    523             "enable use of SDIV and UDIV instructions if available (ARM only)")
    524 DEFINE_BOOL(enable_mls, true,
    525             "enable use of MLS instructions if available (ARM only)")
    526 DEFINE_BOOL(enable_movw_movt, false,
    527             "enable loading 32-bit constant by means of movw/movt "
    528             "instruction pairs (ARM only)")
    529 DEFINE_BOOL(enable_unaligned_accesses, true,
    530             "enable unaligned accesses for ARMv7 (ARM only)")
    531 DEFINE_BOOL(enable_32dregs, ENABLE_32DREGS_DEFAULT,
    532             "enable use of d16-d31 registers on ARM - this requires VFP3")
    533 DEFINE_BOOL(enable_vldr_imm, false,
    534             "enable use of constant pools for double immediate (ARM only)")
    535 DEFINE_BOOL(force_long_branches, false,
    536             "force all emitted branches to be in long mode (MIPS/PPC only)")
    537 DEFINE_STRING(mcpu, "auto", "enable optimization for specific cpu")
    538 
    539 DEFINE_IMPLICATION(enable_armv8, enable_vfp3)
    540 DEFINE_IMPLICATION(enable_armv8, enable_neon)
    541 DEFINE_IMPLICATION(enable_armv8, enable_32dregs)
    542 DEFINE_IMPLICATION(enable_armv8, enable_sudiv)
    543 DEFINE_IMPLICATION(enable_armv8, enable_mls)
    544 
    545 // bootstrapper.cc
    546 DEFINE_STRING(expose_natives_as, NULL, "expose natives in global object")
    547 DEFINE_STRING(expose_debug_as, NULL, "expose debug in global object")
    548 DEFINE_BOOL(expose_free_buffer, false, "expose freeBuffer extension")
    549 DEFINE_BOOL(expose_gc, false, "expose gc extension")
    550 DEFINE_STRING(expose_gc_as, NULL,
    551               "expose gc extension under the specified name")
    552 DEFINE_IMPLICATION(expose_gc_as, expose_gc)
    553 DEFINE_BOOL(expose_externalize_string, false,
    554             "expose externalize string extension")
    555 DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
    556 DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
    557 DEFINE_BOOL(builtins_in_stack_traces, false,
    558             "show built-in functions in stack traces")
    559 DEFINE_BOOL(disable_native_files, false, "disable builtin natives files")
    560 
    561 // builtins-ia32.cc
    562 DEFINE_BOOL(inline_new, true, "use fast inline allocation")
    563 
    564 // codegen-ia32.cc / codegen-arm.cc
    565 DEFINE_BOOL(trace_codegen, false,
    566             "print name of functions for which code is generated")
    567 DEFINE_BOOL(trace, false, "trace function calls")
    568 DEFINE_BOOL(mask_constants_with_cookie, true,
    569             "use random jit cookie to mask large constants")
    570 
    571 // codegen.cc
    572 DEFINE_BOOL(lazy, true, "use lazy compilation")
    573 DEFINE_BOOL(trace_opt, false, "trace lazy optimization")
    574 DEFINE_BOOL(trace_opt_stats, false, "trace lazy optimization statistics")
    575 DEFINE_BOOL(opt, true, "use adaptive optimizations")
    576 DEFINE_BOOL(always_opt, false, "always try to optimize functions")
    577 DEFINE_BOOL(always_osr, false, "always try to OSR functions")
    578 DEFINE_BOOL(prepare_always_opt, false, "prepare for turning on always opt")
    579 DEFINE_BOOL(trace_deopt, false, "trace optimize function deoptimization")
    580 DEFINE_BOOL(trace_stub_failures, false,
    581             "trace deoptimization of generated code stubs")
    582 
    583 DEFINE_BOOL(serialize_toplevel, true, "enable caching of toplevel scripts")
    584 DEFINE_BOOL(trace_serializer, false, "print code serializer trace")
    585 
    586 // compiler.cc
    587 DEFINE_INT(min_preparse_length, 1024,
    588            "minimum length for automatic enable preparsing")
    589 DEFINE_INT(max_opt_count, 10,
    590            "maximum number of optimization attempts before giving up.")
    591 
    592 // compilation-cache.cc
    593 DEFINE_BOOL(compilation_cache, true, "enable compilation cache")
    594 
    595 DEFINE_BOOL(cache_prototype_transitions, true, "cache prototype transitions")
    596 
    597 // cpu-profiler.cc
    598 DEFINE_INT(cpu_profiler_sampling_interval, 1000,
    599            "CPU profiler sampling interval in microseconds")
    600 
    601 // Array abuse tracing
    602 DEFINE_BOOL(trace_js_array_abuse, false,
    603             "trace out-of-bounds accesses to JS arrays")
    604 DEFINE_BOOL(trace_external_array_abuse, false,
    605             "trace out-of-bounds-accesses to external arrays")
    606 DEFINE_BOOL(trace_array_abuse, false,
    607             "trace out-of-bounds accesses to all arrays")
    608 DEFINE_IMPLICATION(trace_array_abuse, trace_js_array_abuse)
    609 DEFINE_IMPLICATION(trace_array_abuse, trace_external_array_abuse)
    610 
    611 // debugger
    612 DEFINE_BOOL(debug_eval_readonly_locals, true,
    613             "do not update locals after debug-evaluate")
    614 DEFINE_BOOL(trace_debug_json, false, "trace debugging JSON request/response")
    615 DEFINE_BOOL(enable_liveedit, true, "enable liveedit experimental feature")
    616 DEFINE_BOOL(hard_abort, true, "abort by crashing")
    617 
    618 // execution.cc
    619 DEFINE_INT(stack_size, V8_DEFAULT_STACK_SIZE_KB,
    620            "default size of stack region v8 is allowed to use (in kBytes)")
    621 
    622 // frames.cc
    623 DEFINE_INT(max_stack_trace_source_length, 300,
    624            "maximum length of function source code printed in a stack trace.")
    625 
    626 // full-codegen.cc
    627 DEFINE_BOOL(always_inline_smi_code, false,
    628             "always inline smi code in non-opt code")
    629 
    630 // heap.cc
    631 DEFINE_INT(min_semi_space_size, 0,
    632            "min size of a semi-space (in MBytes), the new space consists of two"
    633            "semi-spaces")
    634 DEFINE_INT(target_semi_space_size, 0,
    635            "target size of a semi-space (in MBytes) before triggering a GC")
    636 DEFINE_INT(max_semi_space_size, 0,
    637            "max size of a semi-space (in MBytes), the new space consists of two"
    638            "semi-spaces")
    639 DEFINE_INT(semi_space_growth_factor, 2, "factor by which to grow the new space")
    640 DEFINE_BOOL(experimental_new_space_growth_heuristic, false,
    641             "Grow the new space based on the percentage of survivors instead "
    642             "of their absolute value.")
    643 DEFINE_INT(max_old_space_size, 0, "max size of the old space (in Mbytes)")
    644 DEFINE_INT(initial_old_space_size, 0, "initial old space size (in Mbytes)")
    645 DEFINE_INT(max_executable_size, 0, "max size of executable memory (in Mbytes)")
    646 DEFINE_BOOL(gc_global, false, "always perform global GCs")
    647 DEFINE_INT(gc_interval, -1, "garbage collect after <n> allocations")
    648 DEFINE_INT(retain_maps_for_n_gc, 2,
    649            "keeps maps alive for <n> old space garbage collections")
    650 DEFINE_BOOL(trace_gc, false,
    651             "print one trace line following each garbage collection")
    652 DEFINE_BOOL(trace_gc_nvp, false,
    653             "print one detailed trace line in name=value format "
    654             "after each garbage collection")
    655 DEFINE_BOOL(trace_gc_ignore_scavenger, false,
    656             "do not print trace line after scavenger collection")
    657 DEFINE_BOOL(trace_idle_notification, false,
    658             "print one trace line following each idle notification")
    659 DEFINE_BOOL(trace_idle_notification_verbose, false,
    660             "prints the heap state used by the idle notification")
    661 DEFINE_BOOL(print_cumulative_gc_stat, false,
    662             "print cumulative GC statistics in name=value format on exit")
    663 DEFINE_BOOL(print_max_heap_committed, false,
    664             "print statistics of the maximum memory committed for the heap "
    665             "in name=value format on exit")
    666 DEFINE_BOOL(trace_gc_verbose, false,
    667             "print more details following each garbage collection")
    668 DEFINE_INT(trace_allocation_stack_interval, -1,
    669            "print stack trace after <n> free-list allocations")
    670 DEFINE_BOOL(trace_fragmentation, false, "report fragmentation for old space")
    671 DEFINE_BOOL(trace_fragmentation_verbose, false,
    672             "report fragmentation for old space (detailed)")
    673 DEFINE_BOOL(trace_mutator_utilization, false,
    674             "print mutator utilization, allocation speed, gc speed")
    675 DEFINE_BOOL(weak_embedded_maps_in_optimized_code, true,
    676             "make maps embedded in optimized code weak")
    677 DEFINE_BOOL(weak_embedded_objects_in_optimized_code, true,
    678             "make objects embedded in optimized code weak")
    679 DEFINE_BOOL(flush_code, true, "flush code that we expect not to use again")
    680 DEFINE_BOOL(trace_code_flushing, false, "trace code flushing progress")
    681 DEFINE_BOOL(age_code, true,
    682             "track un-executed functions to age code and flush only "
    683             "old code (required for code flushing)")
    684 DEFINE_BOOL(incremental_marking, true, "use incremental marking")
    685 DEFINE_INT(min_progress_during_incremental_marking_finalization, 32,
    686            "keep finalizing incremental marking as long as we discover at "
    687            "least this many unmarked objects")
    688 DEFINE_INT(max_incremental_marking_finalization_rounds, 3,
    689            "at most try this many times to finalize incremental marking")
    690 DEFINE_BOOL(concurrent_sweeping, true, "use concurrent sweeping")
    691 DEFINE_BOOL(parallel_compaction, true, "use parallel compaction")
    692 DEFINE_BOOL(trace_incremental_marking, false,
    693             "trace progress of the incremental marking")
    694 DEFINE_BOOL(track_gc_object_stats, false,
    695             "track object counts and memory usage")
    696 DEFINE_BOOL(trace_gc_object_stats, false,
    697             "trace object counts and memory usage")
    698 DEFINE_IMPLICATION(trace_gc_object_stats, track_gc_object_stats)
    699 DEFINE_BOOL(track_detached_contexts, true,
    700             "track native contexts that are expected to be garbage collected")
    701 DEFINE_BOOL(trace_detached_contexts, false,
    702             "trace native contexts that are expected to be garbage collected")
    703 DEFINE_IMPLICATION(trace_detached_contexts, track_detached_contexts)
    704 #ifdef VERIFY_HEAP
    705 DEFINE_BOOL(verify_heap, false, "verify heap pointers before and after GC")
    706 #endif
    707 DEFINE_BOOL(move_object_start, true, "enable moving of object starts")
    708 DEFINE_BOOL(memory_reducer, true, "use memory reducer")
    709 DEFINE_BOOL(scavenge_reclaim_unmodified_objects, false,
    710             "remove unmodified and unreferenced objects")
    711 DEFINE_INT(heap_growing_percent, 0,
    712            "specifies heap growing factor as (1 + heap_growing_percent/100)")
    713 
    714 // counters.cc
    715 DEFINE_INT(histogram_interval, 600000,
    716            "time interval in ms for aggregating memory histograms")
    717 
    718 
    719 // heap-snapshot-generator.cc
    720 DEFINE_BOOL(heap_profiler_trace_objects, false,
    721             "Dump heap object allocations/movements/size_updates")
    722 
    723 
    724 // v8.cc
    725 DEFINE_BOOL(use_idle_notification, true,
    726             "Use idle notification to reduce memory footprint.")
    727 // ic.cc
    728 DEFINE_BOOL(use_ic, true, "use inline caching")
    729 DEFINE_BOOL(trace_ic, false, "trace inline cache state transitions")
    730 
    731 // macro-assembler-ia32.cc
    732 DEFINE_BOOL(native_code_counters, false,
    733             "generate extra code for manipulating stats counters")
    734 
    735 // mark-compact.cc
    736 DEFINE_BOOL(always_compact, false, "Perform compaction on every full GC")
    737 DEFINE_BOOL(never_compact, false,
    738             "Never perform compaction on full GC - testing only")
    739 DEFINE_BOOL(compact_code_space, true, "Compact code space on full collections")
    740 DEFINE_BOOL(cleanup_code_caches_at_gc, true,
    741             "Flush inline caches prior to mark compact collection and "
    742             "flush code caches in maps during mark compact cycle.")
    743 DEFINE_BOOL(use_marking_progress_bar, true,
    744             "Use a progress bar to scan large objects in increments when "
    745             "incremental marking is active.")
    746 DEFINE_BOOL(zap_code_space, DEBUG_BOOL,
    747             "Zap free memory in code space with 0xCC while sweeping.")
    748 DEFINE_INT(random_seed, 0,
    749            "Default seed for initializing random generator "
    750            "(0, the default, means to use system random).")
    751 
    752 // objects.cc
    753 DEFINE_BOOL(trace_weak_arrays, false, "Trace WeakFixedArray usage")
    754 DEFINE_BOOL(track_prototype_users, false,
    755             "Keep track of which maps refer to a given prototype object")
    756 DEFINE_BOOL(trace_prototype_users, false,
    757             "Trace updates to prototype user tracking")
    758 DEFINE_BOOL(eliminate_prototype_chain_checks, true,
    759             "Collapse prototype chain checks into single-cell checks")
    760 DEFINE_IMPLICATION(eliminate_prototype_chain_checks, track_prototype_users)
    761 DEFINE_BOOL(use_verbose_printer, true, "allows verbose printing")
    762 #if TRACE_MAPS
    763 DEFINE_BOOL(trace_maps, false, "trace map creation")
    764 #endif
    765 
    766 // parser.cc
    767 DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
    768 DEFINE_BOOL(trace_parse, false, "trace parsing and preparsing")
    769 
    770 // simulator-arm.cc, simulator-arm64.cc and simulator-mips.cc
    771 DEFINE_BOOL(trace_sim, false, "Trace simulator execution")
    772 DEFINE_BOOL(debug_sim, false, "Enable debugging the simulator")
    773 DEFINE_BOOL(check_icache, false,
    774             "Check icache flushes in ARM and MIPS simulator")
    775 DEFINE_INT(stop_sim_at, 0, "Simulator stop after x number of instructions")
    776 #if defined(V8_TARGET_ARCH_ARM64) || defined(V8_TARGET_ARCH_MIPS64) || \
    777     defined(V8_TARGET_ARCH_PPC64)
    778 DEFINE_INT(sim_stack_alignment, 16,
    779            "Stack alignment in bytes in simulator. This must be a power of two "
    780            "and it must be at least 16. 16 is default.")
    781 #else
    782 DEFINE_INT(sim_stack_alignment, 8,
    783            "Stack alingment in bytes in simulator (4 or 8, 8 is default)")
    784 #endif
    785 DEFINE_INT(sim_stack_size, 2 * MB / KB,
    786            "Stack size of the ARM64, MIPS64 and PPC64 simulator "
    787            "in kBytes (default is 2 MB)")
    788 DEFINE_BOOL(log_regs_modified, true,
    789             "When logging register values, only print modified registers.")
    790 DEFINE_BOOL(log_colour, true, "When logging, try to use coloured output.")
    791 DEFINE_BOOL(ignore_asm_unimplemented_break, false,
    792             "Don't break for ASM_UNIMPLEMENTED_BREAK macros.")
    793 DEFINE_BOOL(trace_sim_messages, false,
    794             "Trace simulator debug messages. Implied by --trace-sim.")
    795 
    796 // isolate.cc
    797 DEFINE_BOOL(stack_trace_on_illegal, false,
    798             "print stack trace when an illegal exception is thrown")
    799 DEFINE_BOOL(abort_on_uncaught_exception, false,
    800             "abort program (dump core) when an uncaught exception is thrown")
    801 DEFINE_BOOL(randomize_hashes, true,
    802             "randomize hashes to avoid predictable hash collisions "
    803             "(with snapshots this option cannot override the baked-in seed)")
    804 DEFINE_INT(hash_seed, 0,
    805            "Fixed seed to use to hash property keys (0 means random)"
    806            "(with snapshots this option cannot override the baked-in seed)")
    807 
    808 // snapshot-common.cc
    809 DEFINE_BOOL(profile_deserialization, false,
    810             "Print the time it takes to deserialize the snapshot.")
    811 DEFINE_BOOL(serialization_statistics, false,
    812             "Collect statistics on serialized objects.")
    813 
    814 // Regexp
    815 DEFINE_BOOL(regexp_optimization, true, "generate optimized regexp code")
    816 
    817 // Testing flags test/cctest/test-{flags,api,serialization}.cc
    818 DEFINE_BOOL(testing_bool_flag, true, "testing_bool_flag")
    819 DEFINE_MAYBE_BOOL(testing_maybe_bool_flag, "testing_maybe_bool_flag")
    820 DEFINE_INT(testing_int_flag, 13, "testing_int_flag")
    821 DEFINE_FLOAT(testing_float_flag, 2.5, "float-flag")
    822 DEFINE_STRING(testing_string_flag, "Hello, world!", "string-flag")
    823 DEFINE_INT(testing_prng_seed, 42, "Seed used for threading test randomness")
    824 #ifdef _WIN32
    825 DEFINE_STRING(testing_serialization_file, "C:\\Windows\\Temp\\serdes",
    826               "file in which to testing_serialize heap")
    827 #else
    828 DEFINE_STRING(testing_serialization_file, "/tmp/serdes",
    829               "file in which to serialize heap")
    830 #endif
    831 
    832 // mksnapshot.cc
    833 DEFINE_STRING(startup_src, NULL,
    834               "Write V8 startup as C++ src. (mksnapshot only)")
    835 DEFINE_STRING(startup_blob, NULL,
    836               "Write V8 startup blob file. (mksnapshot only)")
    837 
    838 // code-stubs-hydrogen.cc
    839 DEFINE_BOOL(profile_hydrogen_code_stub_compilation, false,
    840             "Print the time it takes to lazily compile hydrogen code stubs.")
    841 
    842 DEFINE_BOOL(predictable, false, "enable predictable mode")
    843 DEFINE_NEG_IMPLICATION(predictable, concurrent_recompilation)
    844 DEFINE_NEG_IMPLICATION(predictable, concurrent_osr)
    845 DEFINE_NEG_IMPLICATION(predictable, concurrent_sweeping)
    846 DEFINE_NEG_IMPLICATION(predictable, parallel_compaction)
    847 DEFINE_NEG_IMPLICATION(predictable, memory_reducer)
    848 
    849 // mark-compact.cc
    850 DEFINE_BOOL(force_marking_deque_overflows, false,
    851             "force overflows of marking deque by reducing it's size "
    852             "to 64 words")
    853 
    854 DEFINE_BOOL(stress_compaction, false,
    855             "stress the GC compactor to flush out bugs (implies "
    856             "--force_marking_deque_overflows)")
    857 
    858 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
    859             "Test mode only flag. It allows an unit test to select evacuation "
    860             "candidates pages (requires --stress_compaction).")
    861 
    862 // api.cc
    863 DEFINE_INT(external_allocation_limit_incremental_time, 1,
    864            "Time spent in incremental marking steps (in ms) once the external "
    865            "allocation limit is reached")
    866 
    867 //
    868 // Dev shell flags
    869 //
    870 
    871 DEFINE_BOOL(help, false, "Print usage message, including flags, on console")
    872 DEFINE_BOOL(dump_counters, false, "Dump counters on exit")
    873 
    874 DEFINE_STRING(map_counters, "", "Map counters to a file")
    875 DEFINE_ARGS(js_arguments,
    876             "Pass all remaining arguments to the script. Alias for \"--\".")
    877 
    878 //
    879 // GDB JIT integration flags.
    880 //
    881 #undef FLAG
    882 #ifdef ENABLE_GDB_JIT_INTERFACE
    883 #define FLAG FLAG_FULL
    884 #else
    885 #define FLAG FLAG_READONLY
    886 #endif
    887 
    888 DEFINE_BOOL(gdbjit, false, "enable GDBJIT interface")
    889 DEFINE_BOOL(gdbjit_full, false, "enable GDBJIT interface for all code objects")
    890 DEFINE_BOOL(gdbjit_dump, false, "dump elf objects with debug info to disk")
    891 DEFINE_STRING(gdbjit_dump_filter, "",
    892               "dump only objects containing this substring")
    893 
    894 #ifdef ENABLE_GDB_JIT_INTERFACE
    895 DEFINE_IMPLICATION(gdbjit_full, gdbjit)
    896 DEFINE_IMPLICATION(gdbjit_dump, gdbjit)
    897 #endif
    898 DEFINE_NEG_IMPLICATION(gdbjit, compact_code_space)
    899 
    900 //
    901 // Debug only flags
    902 //
    903 #undef FLAG
    904 #ifdef DEBUG
    905 #define FLAG FLAG_FULL
    906 #else
    907 #define FLAG FLAG_READONLY
    908 #endif
    909 
    910 // checks.cc
    911 #ifdef ENABLE_SLOW_DCHECKS
    912 DEFINE_BOOL(enable_slow_asserts, false,
    913             "enable asserts that are slow to execute")
    914 #endif
    915 
    916 // codegen-ia32.cc / codegen-arm.cc / macro-assembler-*.cc
    917 DEFINE_BOOL(print_source, false, "pretty print source code")
    918 DEFINE_BOOL(print_builtin_source, false,
    919             "pretty print source code for builtins")
    920 DEFINE_BOOL(print_ast, false, "print source AST")
    921 DEFINE_BOOL(print_builtin_ast, false, "print source AST for builtins")
    922 DEFINE_STRING(stop_at, "", "function name where to insert a breakpoint")
    923 DEFINE_BOOL(trap_on_abort, false, "replace aborts by breakpoints")
    924 
    925 // compiler.cc
    926 DEFINE_BOOL(print_builtin_scopes, false, "print scopes for builtins")
    927 DEFINE_BOOL(print_scopes, false, "print scopes")
    928 
    929 // contexts.cc
    930 DEFINE_BOOL(trace_contexts, false, "trace contexts operations")
    931 
    932 // heap.cc
    933 DEFINE_BOOL(gc_verbose, false, "print stuff during garbage collection")
    934 DEFINE_BOOL(heap_stats, false, "report heap statistics before and after GC")
    935 DEFINE_BOOL(code_stats, false, "report code statistics after GC")
    936 DEFINE_BOOL(print_handles, false, "report handles after GC")
    937 DEFINE_BOOL(check_handle_count, false,
    938             "Check that there are not too many handles at GC")
    939 DEFINE_BOOL(print_global_handles, false, "report global handles after GC")
    940 
    941 // TurboFan debug-only flags.
    942 DEFINE_BOOL(print_turbo_replay, false,
    943             "print C++ code to recreate TurboFan graphs")
    944 
    945 // objects.cc
    946 DEFINE_BOOL(trace_normalization, false,
    947             "prints when objects are turned into dictionaries.")
    948 
    949 // runtime.cc
    950 DEFINE_BOOL(trace_lazy, false, "trace lazy compilation")
    951 
    952 // spaces.cc
    953 DEFINE_BOOL(collect_heap_spill_statistics, false,
    954             "report heap spill statistics along with heap_stats "
    955             "(requires heap_stats)")
    956 
    957 DEFINE_BOOL(trace_isolates, false, "trace isolate state changes")
    958 
    959 // Regexp
    960 DEFINE_BOOL(regexp_possessive_quantifier, false,
    961             "enable possessive quantifier syntax for testing")
    962 DEFINE_BOOL(trace_regexp_bytecodes, false, "trace regexp bytecode execution")
    963 DEFINE_BOOL(trace_regexp_assembler, false,
    964             "trace regexp macro assembler calls.")
    965 DEFINE_BOOL(trace_regexp_parser, false, "trace regexp parsing")
    966 
    967 //
    968 // Logging and profiling flags
    969 //
    970 #undef FLAG
    971 #define FLAG FLAG_FULL
    972 
    973 // log.cc
    974 DEFINE_BOOL(log, false,
    975             "Minimal logging (no API, code, GC, suspect, or handles samples).")
    976 DEFINE_BOOL(log_all, false, "Log all events to the log file.")
    977 DEFINE_BOOL(log_api, false, "Log API events to the log file.")
    978 DEFINE_BOOL(log_code, false,
    979             "Log code events to the log file without profiling.")
    980 DEFINE_BOOL(log_gc, false,
    981             "Log heap samples on garbage collection for the hp2ps tool.")
    982 DEFINE_BOOL(log_handles, false, "Log global handle events.")
    983 DEFINE_BOOL(log_snapshot_positions, false,
    984             "log positions of (de)serialized objects in the snapshot.")
    985 DEFINE_BOOL(log_suspect, false, "Log suspect operations.")
    986 DEFINE_BOOL(prof, false,
    987             "Log statistical profiling information (implies --log-code).")
    988 DEFINE_BOOL(prof_cpp, false, "Like --prof, but ignore generated code.")
    989 DEFINE_IMPLICATION(prof, prof_cpp)
    990 DEFINE_BOOL(prof_browser_mode, true,
    991             "Used with --prof, turns on browser-compatible mode for profiling.")
    992 DEFINE_BOOL(log_regexp, false, "Log regular expression execution.")
    993 DEFINE_STRING(logfile, "v8.log", "Specify the name of the log file.")
    994 DEFINE_BOOL(logfile_per_isolate, true, "Separate log files for each isolate.")
    995 DEFINE_BOOL(ll_prof, false, "Enable low-level linux profiler.")
    996 DEFINE_BOOL(perf_basic_prof, false,
    997             "Enable perf linux profiler (basic support).")
    998 DEFINE_NEG_IMPLICATION(perf_basic_prof, compact_code_space)
    999 DEFINE_BOOL(perf_basic_prof_only_functions, false,
   1000             "Only report function code ranges to perf (i.e. no stubs).")
   1001 DEFINE_IMPLICATION(perf_basic_prof_only_functions, perf_basic_prof)
   1002 DEFINE_STRING(gc_fake_mmap, "/tmp/__v8_gc__",
   1003               "Specify the name of the file for fake gc mmap used in ll_prof")
   1004 DEFINE_BOOL(log_internal_timer_events, false, "Time internal events.")
   1005 DEFINE_BOOL(log_timer_events, false,
   1006             "Time events including external callbacks.")
   1007 DEFINE_IMPLICATION(log_timer_events, log_internal_timer_events)
   1008 DEFINE_IMPLICATION(log_internal_timer_events, prof)
   1009 DEFINE_BOOL(log_instruction_stats, false, "Log AArch64 instruction statistics.")
   1010 DEFINE_STRING(log_instruction_file, "arm64_inst.csv",
   1011               "AArch64 instruction statistics log file.")
   1012 DEFINE_INT(log_instruction_period, 1 << 22,
   1013            "AArch64 instruction statistics logging period.")
   1014 
   1015 DEFINE_BOOL(redirect_code_traces, false,
   1016             "output deopt information and disassembly into file "
   1017             "code-<pid>-<isolate id>.asm")
   1018 DEFINE_STRING(redirect_code_traces_to, NULL,
   1019               "output deopt information and disassembly into the given file")
   1020 
   1021 DEFINE_BOOL(hydrogen_track_positions, false,
   1022             "track source code positions when building IR")
   1023 
   1024 //
   1025 // Disassembler only flags
   1026 //
   1027 #undef FLAG
   1028 #ifdef ENABLE_DISASSEMBLER
   1029 #define FLAG FLAG_FULL
   1030 #else
   1031 #define FLAG FLAG_READONLY
   1032 #endif
   1033 
   1034 // elements.cc
   1035 DEFINE_BOOL(trace_elements_transitions, false, "trace elements transitions")
   1036 
   1037 DEFINE_BOOL(trace_creation_allocation_sites, false,
   1038             "trace the creation of allocation sites")
   1039 
   1040 // code-stubs.cc
   1041 DEFINE_BOOL(print_code_stubs, false, "print code stubs")
   1042 DEFINE_BOOL(test_secondary_stub_cache, false,
   1043             "test secondary stub cache by disabling the primary one")
   1044 
   1045 DEFINE_BOOL(test_primary_stub_cache, false,
   1046             "test primary stub cache by disabling the secondary one")
   1047 
   1048 
   1049 // codegen-ia32.cc / codegen-arm.cc
   1050 DEFINE_BOOL(print_code, false, "print generated code")
   1051 DEFINE_BOOL(print_opt_code, false, "print optimized code")
   1052 DEFINE_BOOL(print_unopt_code, false,
   1053             "print unoptimized code before "
   1054             "printing optimized code based on it")
   1055 DEFINE_BOOL(print_code_verbose, false, "print more information for code")
   1056 DEFINE_BOOL(print_builtin_code, false, "print generated code for builtins")
   1057 
   1058 #ifdef ENABLE_DISASSEMBLER
   1059 DEFINE_BOOL(sodium, false,
   1060             "print generated code output suitable for use with "
   1061             "the Sodium code viewer")
   1062 
   1063 DEFINE_IMPLICATION(sodium, print_code_stubs)
   1064 DEFINE_IMPLICATION(sodium, print_code)
   1065 DEFINE_IMPLICATION(sodium, print_opt_code)
   1066 DEFINE_IMPLICATION(sodium, hydrogen_track_positions)
   1067 DEFINE_IMPLICATION(sodium, code_comments)
   1068 
   1069 DEFINE_BOOL(print_all_code, false, "enable all flags related to printing code")
   1070 DEFINE_IMPLICATION(print_all_code, print_code)
   1071 DEFINE_IMPLICATION(print_all_code, print_opt_code)
   1072 DEFINE_IMPLICATION(print_all_code, print_unopt_code)
   1073 DEFINE_IMPLICATION(print_all_code, print_code_verbose)
   1074 DEFINE_IMPLICATION(print_all_code, print_builtin_code)
   1075 DEFINE_IMPLICATION(print_all_code, print_code_stubs)
   1076 DEFINE_IMPLICATION(print_all_code, code_comments)
   1077 #ifdef DEBUG
   1078 DEFINE_IMPLICATION(print_all_code, trace_codegen)
   1079 #endif
   1080 #endif
   1081 
   1082 
   1083 //
   1084 // VERIFY_PREDICTABLE related flags
   1085 //
   1086 #undef FLAG
   1087 
   1088 #ifdef VERIFY_PREDICTABLE
   1089 #define FLAG FLAG_FULL
   1090 #else
   1091 #define FLAG FLAG_READONLY
   1092 #endif
   1093 
   1094 DEFINE_BOOL(verify_predictable, false,
   1095             "this mode is used for checking that V8 behaves predictably")
   1096 DEFINE_INT(dump_allocations_digest_at_alloc, -1,
   1097            "dump allocations digest each n-th allocation")
   1098 
   1099 
   1100 //
   1101 // Read-only flags
   1102 //
   1103 #undef FLAG
   1104 #define FLAG FLAG_READONLY
   1105 
   1106 // assembler.h
   1107 DEFINE_BOOL(enable_embedded_constant_pool, V8_EMBEDDED_CONSTANT_POOL,
   1108             "enable use of embedded constant pools (ARM/PPC only)")
   1109 
   1110 DEFINE_BOOL(unbox_double_fields, V8_DOUBLE_FIELDS_UNBOXING,
   1111             "enable in-object double fields unboxing (64-bit only)")
   1112 DEFINE_IMPLICATION(unbox_double_fields, track_double_fields)
   1113 
   1114 DEFINE_BOOL(global_var_shortcuts, false, "use ic-less global loads and stores")
   1115 
   1116 
   1117 // Cleanup...
   1118 #undef FLAG_FULL
   1119 #undef FLAG_READONLY
   1120 #undef FLAG
   1121 #undef FLAG_ALIAS
   1122 
   1123 #undef DEFINE_BOOL
   1124 #undef DEFINE_MAYBE_BOOL
   1125 #undef DEFINE_INT
   1126 #undef DEFINE_STRING
   1127 #undef DEFINE_FLOAT
   1128 #undef DEFINE_ARGS
   1129 #undef DEFINE_IMPLICATION
   1130 #undef DEFINE_NEG_IMPLICATION
   1131 #undef DEFINE_NEG_VALUE_IMPLICATION
   1132 #undef DEFINE_VALUE_IMPLICATION
   1133 #undef DEFINE_ALIAS_BOOL
   1134 #undef DEFINE_ALIAS_INT
   1135 #undef DEFINE_ALIAS_STRING
   1136 #undef DEFINE_ALIAS_FLOAT
   1137 #undef DEFINE_ALIAS_ARGS
   1138 
   1139 #undef FLAG_MODE_DECLARE
   1140 #undef FLAG_MODE_DEFINE
   1141 #undef FLAG_MODE_DEFINE_DEFAULTS
   1142 #undef FLAG_MODE_META
   1143 #undef FLAG_MODE_DEFINE_IMPLICATIONS
   1144 
   1145 #undef COMMA
   1146