rev 1905 : 8162955: Activate anonymous class loading for small sources
Reviewed-by: sundar

   1 This document describes system properties that are used for internal
   2 debugging and instrumentation purposes, along with the system loggers,
   3 which are used for the same thing.
   4 
   5 This document is intended as a developer resource, and it is not
   6 needed as Nashorn documentation for normal usage. Flags and system
   7 properties described herein are subject to change without notice.
   8 
   9 =====================================
  10 1. System properties used internally
  11 =====================================
  12 
  13 This documentation of the system property flags assume that the
  14 default value of the flag is false, unless otherwise specified.
  15 
  16 SYSTEM PROPERTY: -Dnashorn.args=<string>
  17 
  18 This property takes as its value a space separated list of Nashorn
  19 command line options that should be passed to Nashorn. This might be
  20 useful in environments where it is hard to tell how a nashorn.jar is
  21 launched.
  22 
  23 Example:
  24 
  25 > java -Dnashorn.args="--lazy-complation --log=compiler" large-java-app-with-nashorn.jar 
  26 > ant -Dnashorn.args="--log=codegen" antjob
  27 
  28 SYSTEM PROPERTY: -Dnashorn.args.prepend=<string>
  29 
  30 This property behaves like nashorn.args, but adds the given arguments
  31 before the existing ones instead of after them. Later arguments will
  32 overwrite earlier ones, so this is useful for setting default arguments
  33 that can be overwritten.
  34 
  35 
  36 SYSTEM PROPERTY: -Dnashorn.unstable.relink.threshold=x
  37 
  38 This property controls how many call site misses are allowed before a 
  39 callsite is relinked with "apply" semantics to never change again. 
  40 In the case of megamorphic callsites, this is necessary, or the 
  41 program would spend all its time swapping out callsite targets. Dynalink 
  42 has a default value (currently 8 relinks) for this property if it 
  43 is not explicitly set.
  44 
  45 
  46 SYSTEM PROPERTY: -Dnashorn.compiler.splitter.threshold=x
  47 
  48 This will change the node weight that requires a subgraph of the IR to
  49 be split into several classes in order not to run out of bytecode space.
  50 The default value is 0x8000 (32768).
  51 
  52 
  53 SYSTEM PROPERTY: -Dnashorn.serialize.compression=<x>
  54 
  55 This property sets the compression level used when deflating serialized
  56 AST structures of anonymous split functions. Valid values range from 0 to 9,
  57 the default value is 4. Higher values will reduce memory size of serialized
  58 AST but increase CPU usage required for compression.
  59 
  60 
  61 SYSTEM PROPERTY: -Dnashorn.codegen.debug.trace=<x>
  62 
  63 See the description of the codegen logger below.
  64 
  65 
  66 SYSTEM PROPERTY: -Dnashorn.fields.objects, -Dnashorn.fields.dual
  67 
  68 When the nashorn.fields.objects property is true, Nashorn will always
  69 use object fields for AccessorProperties, requiring boxing for all
  70 primitive property values. When nashorn.fields.dual is set, Nashorn
  71 will always use dual long/object fields, which allows primitives to be
  72 stored without boxing. When neither system property is set, Nashorn
  73 chooses a setting depending on the optimistic types setting (dual
  74 fields when optimistic types are enabled, object-only fields otherwise).
  75 
  76 With dual fields, Nashorn uses long fields to store primitive values.
  77 Ints are represented as the 32 low bits of the long fields. Doubles
  78 are represented as the doubleToLongBits of their value. This way a
  79 single field can be used for all primitive types. Packing and
  80 unpacking doubles to their bit representation is intrinsified by
  81 the JVM and extremely fast.
  82 
  83 In the future, this might complement or be replaced by experimental
  84 feature sun.misc.TaggedArray, which has been discussed on the mlvm
  85 mailing list. TaggedArrays are basically a way to share data space
  86 between primitives and references, and have the GC understand this.
  87 
  88 
  89 SYSTEM PROPERTY: -Dnashorn.compiler.symbol.trace=[<x>[,*]], 
  90   -Dnashorn.compiler.symbol.stacktrace=[<x>[,*]]
  91 
  92 When this property is set, creation and manipulation of any symbol
  93 named "x" will show information about when the compiler changes its
  94 type assumption, bytecode local variable slot assignment and other
  95 data. This is useful if, for example, a symbol shows up as an Object,
  96 when you believe it should be a primitive. Usually there is an
  97 explanation for this, for example that it exists in the global scope
  98 and type analysis has to be more conservative. 
  99 
 100 Several symbols names to watch can be specified by comma separation.
 101 
 102 If no variable name is specified (and no equals sign), all symbols
 103 will be watched
 104 
 105 By using "stacktrace" instead of or together with "trace", stack
 106 traces will be displayed upon symbol changes according to the same
 107 semantics.
 108 
 109 
 110 SYSTEM PROPERTY: -Dnashorn.lexer.xmlliterals
 111 
 112 If this property it set, it means that the Lexer should attempt to
 113 parse XML literals, which would otherwise generate syntax
 114 errors. Warning: there are currently no unit tests for this
 115 functionality.
 116 
 117 XML literals, when this is enabled, end up as standard LiteralNodes in
 118 the IR.
 119 
 120 
 121 SYSTEM_PROPERTY: -Dnashorn.debug
 122 
 123 If this property is set to true, Nashorn runs in Debug mode. Debug
 124 mode is slightly slower, as for example statistics counters are enabled
 125 during the run. Debug mode makes available a NativeDebug instance
 126 called "Debug" in the global space that can be used to print property
 127 maps and layout for script objects, as well as a "dumpCounters" method
 128 that will print the current values of the previously mentioned stats
 129 counters.
 130 
 131 These functions currently exists for Debug:
 132 
 133 "map" - print(Debug.map(x)) will dump the PropertyMap for object x to
 134 stdout (currently there also exist functions called "embedX", where X
 135 is a value from 0 to 3, that will dump the contents of the embed pool
 136 for the first spill properties in any script object and "spill", that
 137 will dump the contents of the growing spill pool of spill properties
 138 in any script object. This is of course subject to change without
 139 notice, should we change the script object layout.
 140 
 141 "methodHandle" - this method returns the method handle that is used
 142 for invoking a particular script function.
 143 
 144 "identical" - this method compares two script objects for reference
 145 equality. It is a == Java comparison
 146 
 147 "equals" - Returns true if two objects are either referentially
 148 identical or equal as defined by java.lang.Object.equals.
 149 
 150 "dumpCounters" - will dump the debug counters' current values to
 151 stdout.
 152 
 153 Currently we count number of ScriptObjects in the system, number of
 154 Scope objects in the system, number of ScriptObject listeners added,
 155 removed and dead (without references).
 156 
 157 We also count number of ScriptFunctions, ScriptFunction invocations
 158 and ScriptFunction allocations.
 159 
 160 Furthermore we count PropertyMap statistics: how many property maps
 161 exist, how many times were property maps cloned, how many times did
 162 the property map history cache hit, prevent new allocations, how many
 163 prototype invalidations were done, how many time the property map
 164 proto cache hit.
 165 
 166 Finally we count callsite misses on a per callsite bases, which occur
 167 when a callsite has to be relinked, due to a previous assumption of
 168 object layout being invalidated.
 169 
 170 "getContext" - return the current Nashorn context.
 171 
 172 "equalWithoutType" - Returns true if if the two objects are both
 173 property maps, and they have identical properties in the same order,
 174 but allows the properties to differ in their types.
 175 
 176 "diffPropertyMaps" Returns a diagnostic string representing the difference
 177 of two property maps.
 178 
 179 "getClass" - Returns the Java class of an object, or undefined if null.
 180 
 181 "toJavaString" - Returns the Java toString representation of an object.
 182 
 183 "toIdentString" - Returns a string representation of an object consisting
 184 of its java class name and hash code.
 185 
 186 "getListenerCount" - Return the number of property listeners for a
 187 script object.
 188 
 189 "getEventQueueCapacity" - Get the capacity of the event queue.
 190 
 191 "setEventQueueCapacity" - Set the event queue capacity.
 192 
 193 "addRuntimeEvent" - Add a runtime event to the runtime event queue.
 194 The queue has a fixed size (see -Dnashorn.runtime.event.queue.size)
 195 and the oldest entry will be thrown out of the queue is about to overflow.
 196 
 197 "expandEventQueueCapacity" - Expands the event queue capacity,
 198 or truncates if capacity is lower than current capacity. Then only
 199 the newest entries are kept.
 200 
 201 "clearRuntimeEvents" - Clear the runtime event queue.
 202 
 203 "removeRuntimeEvent" - Remove a specific runtime event from the event queue.
 204 
 205 "getRuntimeEvents" - Return all runtime events in the queue as an array.
 206 
 207 "getLastRuntimeEvent" - Return the last runtime event in the queue.
 208 
 209 
 210 SYSTEM PROPERTY: -Dnashorn.methodhandles.debug.stacktrace
 211 
 212 This enhances methodhandles logging (see below) to also dump the
 213 stack trace for every instrumented method handle operation.
 214 Warning: This is enormously verbose, but provides a pretty
 215 decent "grep:able" picture of where the calls are coming from.
 216 
 217 
 218 SYSTEM PROPERTY: -Dnashorn.cce
 219 
 220 Setting this system property causes the Nashorn linker to rely on
 221 ClassCastExceptions for triggering a callsite relink. If not set, the linker
 222 will add an explicit instanceof guard.
 223 
 224 
 225 SYSTEM PROPERTY: -Dnashorn.spill.threshold=<x>
 226 
 227 This property sets the number of fields in an object from which to use
 228 generic array based spill storage instead of Java fields. The default value
 229 is 256.
 230 
 231 
 232 SYSTEM PROPERTY: -Dnashorn.tcs.miss.samplePercent=<x>
 233 
 234 When running with the trace callsite option (-tcs), Nashorn will count
 235 and instrument any callsite misses that require relinking. As the
 236 number of relinks is large and usually produces a lot of output, this
 237 system property can be used to constrain the percentage of misses that
 238 should be logged. Typically this is set to 1 or 5 (percent). 1% is the
 239 default value.
 240 
 241 SYSTEM PROPERTY: -Dnashorn.persistent.code.cache
 242 
 243 This property can be used to set the directory where Nashorn stores
 244 serialized script classes generated with the -pcc/--persistent-code-cache
 245 option. The default directory name is "nashorn_code_cache".
 246 
 247 
 248 SYSTEM PROPERTY: -Dnashorn.typeInfo.maxFiles
 249 
 250 Maximum number of files to store in the type info cache. The type info cache
 251 is used to cache type data of JavaScript functions when running with
 252 optimistic types (-ot/--optimistic-types). There is one file per JavaScript
 253 function in the cache.
 254 
 255 The default value is 0 which means the feature is disabled. Setting this
 256 to something like 20000 is probably good enough for most applications and
 257 will usually cap the cache directory to about 80MB presuming a 4kB
 258 filesystem allocation unit. Set this to "unlimited" to run without limit.
 259 
 260 If the value is not 0 or "unlimited", Nashorn will spawn a cleanup thread
 261 that makes sure the number of files in the cache does not exceed the given
 262 value by deleting the least recently modified files.
 263 
 264 
 265 SYSTEM PROPERTY: -Dnashorn.typeInfo.cacheDir
 266 
 267 This property can be used to set the directory where Nashorn stores the
 268 type info cache when -Dnashorn.typeInfo.maxFiles is set to a nonzero
 269 value. The default location is platform specific. On Windows, it is
 270 "${java.io.tmpdir}\com.oracle.java.NashornTypeInfo". On Linux and
 271 Solaris it is "~/.cache/com.oracle.java.NashornTypeInfo". On Mac OS X,
 272 it is "~/Library/Caches/com.oracle.java.NashornTypeInfo".
 273 
 274 
 275 SYSTEM PROPERTY: -Dnashorn.typeInfo.cleanupDelaySeconds=<value>
 276 
 277 This sets the delay between cleanups of the typeInfo cache, in seconds.
 278 The default delay is 20 seconds.
 279 
 280 
 281 SYSTEM PROPERTY: -Dnashorn.profilefile=<filename>
 282 
 283 When running with the profile callsite options (-pcs), Nashorn will
 284 dump profiling data for all callsites to stderr as a shutdown hook. To
 285 instead redirect this to a file, specify the path to the file using
 286 this system property.
 287 
 288 
 289 SYSTEM_PROPERTY: -Dnashorn.regexp.impl=[jdk|joni]
 290 
 291 This property defines the regular expression engine to be used by
 292 Nashorn. Set this flag to "jdk" to get an implementation based on the
 293 JDK's java.util.regex package. Set this property to "joni" to install
 294 an implementation based on Joni, the regular expression engine used by
 295 the JRuby project. The default value for this flag is "joni"
 296 
 297 SYSTEM PROPERTY: -Dnashorn.runtime.event.queue.size=<value>
 298 
 299 Nashorn provides a fixed sized runtime event queue for debugging purposes.
 300 See -Dnashorn.debug for methods to access the event queue.
 301 The default value is 1024.
 302 










 303 ===============
 304 2. The loggers.
 305 ===============
 306 
 307 It is very simple to create your own logger. Use the DebugLogger class
 308 and give the subsystem name as a constructor argument.
 309 
 310 The Nashorn loggers can be used to print per-module or per-subsystem
 311 debug information with different levels of verbosity. The loggers for
 312 a given subsystem are available are enabled by using
 313 
 314 --log=<systemname>[:<level>]
 315 
 316 on the command line.
 317 
 318 Here <systemname> identifies the name of the subsystem to be logged
 319 and the optional colon and level argument is a standard
 320 java.util.logging.Level name (severe, warning, info, config, fine,
 321 finer, finest). If the level is left out for a particular subsystem,
 322 it defaults to "info". Any log message logged as the level or a level
 323 that is more important will be output to stderr by the logger.
 324 
 325 Several loggers can be enabled by a single command line option, by
 326 putting a comma after each subsystem/level tuple (or each subsystem if
 327 level is unspecified). The --log option can also be given multiple
 328 times on the same command line, with the same effect.
 329 
 330 For example: --log=codegen,fields:finest is equivalent to
 331 --log=codegen:info --log=fields:finest
 332 
 333 The following is an incomplete list of subsystems that currently
 334 support logging. Look for classes implementing
 335 jdk.nashorn.internal.runtime.logging.Loggable for more loggers.
 336 
 337 
 338 * compiler
 339 
 340 The compiler is in charge of turning source code and function nodes
 341 into byte code, and installs the classes into a class loader
 342 controlled from the Context. Log messages are, for example, about
 343 things like new compile units being allocated. The compiler has global
 344 settings that all the tiers of codegen (e.g. Lower and CodeGenerator)
 345 use.s
 346 
 347 
 348 * recompile
 349 
 350 This logger shows information about recompilation of scripts and
 351 functions at runtime. Recompilation may happen because a function
 352 was called with different parameter types, or because an optimistic
 353 assumption failed while executing a function with -ot/--optimistic-types.
 354 
 355 
 356 * codegen
 357 
 358 The code generator is the emitter stage of the code pipeline, and
 359 turns the lowest tier of a FunctionNode into bytecode. Codegen logging
 360 shows byte codes as they are being emitted, line number information
 361 and jumps. It also shows the contents of the bytecode stack prior to
 362 each instruction being emitted. This is a good debugging aid. For
 363 example:
 364 
 365 [codegen] #41                       line:2 (f)_afc824e 
 366 [codegen] #42                           load symbol x slot=2 
 367 [codegen] #43  {1:O}                    load int 0 
 368 [codegen] #44  {2:I O}                  dynamic_runtime_call GT:ZOI_I args=2 returnType=boolean 
 369 [codegen] #45                              signature (Ljava/lang/Object;I)Z 
 370 [codegen] #46  {1:Z}                    ifeq  ternary_false_5402fe28 
 371 [codegen] #47                           load symbol x slot=2 
 372 [codegen] #48  {1:O}                    goto ternary_exit_107c1f2f 
 373 [codegen] #49                       ternary_false_5402fe28 
 374 [codegen] #50                           load symbol x slot=2 
 375 [codegen] #51  {1:O}                    convert object -> double 
 376 [codegen] #52  {1:D}                    neg 
 377 [codegen] #53  {1:D}                    convert double -> object 
 378 [codegen] #54  {1:O}                ternary_exit_107c1f2f 
 379 [codegen] #55  {1:O}                    return object 
 380 
 381 shows a ternary node being generated for the sequence "return x > 0 ?
 382 x : -x"
 383 
 384 The first number on the log line is a unique monotonically increasing
 385 emission id per bytecode. There is no guarantee this is the same id
 386 between runs.  depending on non deterministic code
 387 execution/compilation, but for small applications it usually is. If
 388 the system variable -Dnashorn.codegen.debug.trace=<x> is set, where x
 389 is a bytecode emission id, a stack trace will be shown as the
 390 particular bytecode is about to be emitted. This can be a quick way to
 391 determine where it comes from without attaching the debugger. "Who
 392 generated that neg?"
 393 
 394 The --log=codegen option is equivalent to setting the system variable
 395 "nashorn.codegen.debug" to true.
 396 
 397 * fold
 398 
 399 Shows constant folding taking place before lowering
 400 
 401 * lower
 402 
 403 This is the first lowering pass.
 404 
 405 Lower is a code generation pass that turns high level IR nodes into
 406 lower level one, for example substituting comparisons to RuntimeNodes
 407 and inlining finally blocks.
 408 
 409 Lower is also responsible for determining control flow information
 410 like end points.
 411 
 412 * symbols
 413 
 414 The symbols logger tracks the assignment os symbols to identifiers.
 415 
 416 * scopedepths
 417 
 418 This logs the calculation of scope depths for non-local symbols.
 419 
 420 * fields
 421 
 422 The --log=fields option (at info level) is equivalent to setting the
 423 system variable "nashorn.fields.debug" to true. At the info level it
 424 will only show info about type assumptions that were invalidated. If
 425 the level is set to finest, it will also trace every AccessorProperty
 426 getter and setter in the program, show arguments, return values
 427 etc. It will also show the internal representation of respective field
 428 (Object in the normal case, unless running with the dual field
 429 representation)
 430 
 431 * time
 432 
 433 This enables timers for various phases of script compilation. The timers
 434 will be dumped when the Nashorn process exits. We see a percentage value
 435 of how much time was spent not executing bytecode (i.e. compilation and
 436 internal tasks) at the end of the report. 
 437 
 438 A finer level than "info" will show individual compilation timings as they
 439 happen.
 440 
 441 Here is an example:
 442 
 443 [time] Accumulated complation phase Timings:
 444 [time] 
 445 [time] 'JavaScript Parsing'              1076 ms
 446 [time] 'Constant Folding'                 159 ms
 447 [time] 'Control Flow Lowering'            303 ms
 448 [time] 'Program Point Calculation'        282 ms
 449 [time] 'Builtin Replacement'               71 ms
 450 [time] 'Code Splitting'                   670 ms
 451 [time] 'Symbol Assignment'                474 ms
 452 [time] 'Scope Depth Computation'          249 ms
 453 [time] 'Optimistic Type Assignment'       186 ms
 454 [time] 'Local Variable Type Calculation'  526 ms
 455 [time] 'Bytecode Generation'             5177 ms
 456 [time] 'Class Installation'              1854 ms
 457 [time] 
 458 [time] Total runtime: 11994 ms (Non-runtime: 11027 ms [91%])
 459 
 460 * methodhandles
 461 
 462 If this logger is enabled, each MethodHandle related call that uses
 463 the java.lang.invoke package gets its MethodHandle intercepted and an
 464 instrumentation printout of arguments and return value appended to
 465 it. This shows exactly which method handles are executed and from
 466 where. (Also MethodTypes and SwitchPoints).
 467 
 468 * classcache
 469 
 470 This logger shows information about reusing code classes using the
 471 in-memory class cache. Nashorn will try to avoid compilation of
 472 scripts by using existing classes. This can significantly improve
 473 performance when repeatedly evaluating the same script.
 474 
 475 =======================
 476 3. Undocumented options
 477 =======================
 478 
 479 Here follows a short description of undocumented options for Nashorn.
 480 To see a list of all undocumented options, use the (undocumented) flag
 481 "-xhelp".
 482 
 483 i.e. jjs -xhelp or java -jar nashorn.jar -xhelp
 484 
 485 Undocumented options are not guaranteed to work, run correctly or be
 486 bug free. They are experimental and for internal or debugging use.
 487 They are also subject to change without notice.
 488 
 489 In practice, though, all options below not explicitly documented as
 490 EXPERIMENTAL can be relied upon, for example --dump-on-error is useful
 491 for any JavaScript/Nashorn developer, but there is no guarantee.
 492 
 493 A short summary follows:
 494 
 495         -D (-Dname=value. Set a system property. This option can be repeated.)
 496 
 497         -ccs, --class-cache-size (Size of the Class cache size per global scope.)
 498 
 499         -cp, -classpath (-cp path. Specify where to find user class files.)
 500 
 501         -co, --compile-only (Compile without running.)
 502                 param: [true|false]   default: false
 503 
 504         -d, --dump-debug-dir (specify a destination directory to dump class files.)
 505                 param: <path>   
 506 
 507         --debug-lines (Generate line number table in .class files.)
 508                 param: [true|false]   default: true
 509 
 510         --debug-locals (Generate local variable table in .class files.)
 511                 param: [true|false]   default: false
 512 
 513         -doe, -dump-on-error (Dump a stack trace on errors.)
 514                 param: [true|false]   default: false
 515 
 516         --early-lvalue-error (invalid lvalue expressions should be reported as early errors.)
 517                 param: [true|false]   default: true
 518 
 519         --empty-statements (Preserve empty statements in AST.)
 520                 param: [true|false]   default: false
 521 
 522         -fv, -fullversion (Print full version info of Nashorn.)
 523                 param: [true|false]   default: false
 524 
 525         --function-statement-error (Report an error when function declaration is used as a statement.)
 526                 param: [true|false]   default: false
 527 
 528         --function-statement-warning (Warn when function declaration is used as a statement.)
 529                 param: [true|false]   default: false
 530 
 531         -fx (Launch script as an fx application.)
 532                 param: [true|false]   default: false
 533 
 534         --global-per-engine (Use single Global instance per script engine instance.)
 535                 param: [true|false]   default: false
 536 
 537         -h, -help (Print help for command line flags.)
 538                 param: [true|false]   default: false
 539 
 540         --loader-per-compile (Create a new class loader per compile.)
 541                 param: [true|false]   default: true
 542 
 543         -l, --locale (Set Locale for script execution.)
 544                 param: <locale>   default: en-US
 545 
 546         --log (Enable logging of a given level for a given number of sub systems. 
 547               [for example: --log=fields:finest,codegen:info].)
 548                 param: <module:level>,*   
 549 
 550         -nj, --no-java (Disable Java support.)
 551                 param: [true|false]   default: false
 552 
 553         -nse, --no-syntax-extensions (Disallow non-standard syntax extensions.)
 554                 param: [true|false]   default: false
 555 
 556         -nta, --no-typed-arrays (Disable typed arrays support.)
 557                 param: [true|false]   default: false
 558 
 559         --parse-only (Parse without compiling.)
 560                 param: [true|false]   default: false
 561 
 562         --print-ast (Print abstract syntax tree.)
 563                 param: [true|false]   default: false
 564 
 565         -pc, --print-code (Print generated bytecode. If a directory is specified, nothing will 
 566                           be dumped to stderr. Also, in that case, .dot files will be generated 
 567                           for all functions or for the function with the specified name only.)
 568                 param: [dir:<output-dir>,function:<name>]   
 569 
 570         --print-lower-ast (Print lowered abstract syntax tree.)
 571                 param: [true|false]   default: false
 572 
 573         -plp, --print-lower-parse (Print the parse tree after lowering.)
 574                 param: [true|false]   default: false
 575 
 576         --print-mem-usage (Print memory usage of IR after each compile stage.)
 577                 param: [true|false]   default: false
 578 
 579         --print-no-newline (Print function will not print new line char.)
 580                 param: [true|false]   default: false
 581 
 582         -pp, --print-parse (Print the parse tree.)
 583                 param: [true|false]   default: false
 584 
 585         --print-symbols (Print the symbol table.)
 586                 param: [true|false]   default: false
 587 
 588         -pcs, --profile-callsites (Dump callsite profile data.)
 589                 param: [true|false]   default: false
 590 
 591         -scripting (Enable scripting features.)
 592                 param: [true|false]   default: false
 593 
 594         --stderr (Redirect stderr to a filename or to another tty, e.g. stdout.)
 595                 param: <output console>   
 596 
 597         --stdout (Redirect stdout to a filename or to another tty, e.g. stderr.)
 598                 param: <output console>   
 599 
 600         -strict (Run scripts in strict mode.)
 601                 param: [true|false]   default: false
 602 
 603         -t, -timezone (Set timezone for script execution.)
 604                 param: <timezone>   default: Europe/Stockholm
 605 
 606         -tcs, --trace-callsites (Enable callsite trace mode. Options are: miss [trace callsite misses] 
 607                                  enterexit [trace callsite enter/exit], objects [print object properties].)
 608                 param: [=[option,]*]   
 609 
 610         --verify-code (Verify byte code before running.)
 611                 param: [true|false]   default: false
 612 
 613         -v, -version (Print version info of Nashorn.)
 614                 param: [true|false]   default: false
 615 
 616         -xhelp (Print extended help for command line flags.)
 617                 param: [true|false]   default: false
 618 
--- EOF ---