1 /*
   2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_RUNTIME_GLOBALS_HPP
  26 #define SHARE_RUNTIME_GLOBALS_HPP
  27 
  28 #include "compiler/compiler_globals_pd.hpp"
  29 #include "runtime/globals_shared.hpp"
  30 #include "utilities/align.hpp"
  31 #include "utilities/globalDefinitions.hpp"
  32 #include "utilities/macros.hpp"
  33 #include CPU_HEADER(globals)
  34 #include OS_HEADER(globals)
  35 #include OS_CPU_HEADER(globals)
  36 
  37 // develop flags are settable / visible only during development and are constant in the PRODUCT version
  38 // product flags are always settable / visible
  39 // notproduct flags are settable / visible only during development and are not declared in the PRODUCT version
  40 // develop_pd/product_pd flags are the same as develop/product, except that their default values
  41 // are specified in platform-dependent header files.
  42 
  43 // Flags must be declared with the following number of parameters:
  44 // non-pd flags:
  45 //    (type, name, default_value, doc), or
  46 //    (type, name, default_value, extra_attrs, doc)
  47 // pd flags:
  48 //    (type, name, doc), or
  49 //    (type, name, extra_attrs, doc)
  50 
  51 // A flag must be declared with one of the following types:
  52 // bool, int, uint, intx, uintx, size_t, ccstr, ccstrlist, double, or uint64_t.
  53 // The type "ccstr" and "ccstrlist" are an alias for "const char*" and is used
  54 // only in this file, because the macrology requires single-token type names.
  55 
  56 // The optional extra_attrs parameter may have one of the following values:
  57 // DIAGNOSTIC, EXPERIMENTAL, or MANAGEABLE. Currently extra_attrs can be used
  58 // only with product/product_pd flags.
  59 //
  60 // DIAGNOSTIC options are not meant for VM tuning or for product modes.
  61 //    They are to be used for VM quality assurance or field diagnosis
  62 //    of VM bugs.  They are hidden so that users will not be encouraged to
  63 //    try them as if they were VM ordinary execution options.  However, they
  64 //    are available in the product version of the VM.  Under instruction
  65 //    from support engineers, VM customers can turn them on to collect
  66 //    diagnostic information about VM problems.  To use a VM diagnostic
  67 //    option, you must first specify +UnlockDiagnosticVMOptions.
  68 //    (This master switch also affects the behavior of -Xprintflags.)
  69 //
  70 // EXPERIMENTAL flags are in support of features that may not be
  71 //    an officially supported part of a product, but may be available
  72 //    for experimenting with. They could, for example, be performance
  73 //    features that may not have undergone full or rigorous QA, but which may
  74 //    help performance in some cases and released for experimentation
  75 //    by the community of users and developers. This flag also allows one to
  76 //    be able to build a fully supported product that nonetheless also
  77 //    ships with some unsupported, lightly tested, experimental features.
  78 //    Refer to the documentation of any products using this code for details
  79 //    on support and fitness for production.
  80 //    Like the UnlockDiagnosticVMOptions flag above, there is a corresponding
  81 //    UnlockExperimentalVMOptions flag, which allows the control and
  82 //    modification of the experimental flags.
  83 //
  84 // Nota bene: neither diagnostic nor experimental options should be used casually,
  85 //    Refer to the documentation of any products using this code for details.
  86 //
  87 // MANAGEABLE flags are writeable external product flags.
  88 //    They are dynamically writeable through the JDK management interface
  89 //    (com.sun.management.HotSpotDiagnosticMXBean API) and also through JConsole.
  90 //    These flags are external exported interface (see CSR).  The list of
  91 //    manageable flags can be queried programmatically through the management
  92 //    interface.
  93 //
  94 //    A flag can be made as "manageable" only if
  95 //    - the flag is defined in a CSR request as an external exported interface.
  96 //    - the VM implementation supports dynamic setting of the flag.
  97 //      This implies that the VM must *always* query the flag variable
  98 //      and not reuse state related to the flag state at any given time.
  99 //    - you want the flag to be queried programmatically by the customers.
 100 //
 101 
 102 //
 103 // range is a macro that will expand to min and max arguments for range
 104 //    checking code if provided - see jvmFlagLimit.hpp
 105 //
 106 // constraint is a macro that will expand to custom function call
 107 //    for constraint checking if provided - see jvmFlagLimit.hpp
 108 
 109 // Default and minimum StringTable and SymbolTable size values
 110 // Must be powers of 2
 111 const size_t defaultStringTableSize = NOT_LP64(1024) LP64_ONLY(65536);
 112 const size_t minimumStringTableSize = 128;
 113 const size_t defaultSymbolTableSize = 32768; // 2^15
 114 const size_t minimumSymbolTableSize = 1024;
 115 
 116 #ifdef _LP64
 117 #define LP64_RUNTIME_FLAGS(develop,                                         \
 118                            develop_pd,                                      \
 119                            product,                                         \
 120                            product_pd,                                      \
 121                            notproduct,                                      \
 122                            range,                                           \
 123                            constraint)                                      \
 124                                                                             \
 125   product(bool, UseCompressedOops, false,                                   \
 126           "Use 32-bit object references in 64-bit VM. "                     \
 127           "lp64_product means flag is always constant in 32 bit VM")        \
 128                                                                             \
 129   product(bool, UseCompressedClassPointers, true,                           \
 130           "Use 32-bit class pointers in 64-bit VM. "                        \
 131           "lp64_product means flag is always constant in 32 bit VM")        \
 132                                                                             \
 133   product(int, ObjectAlignmentInBytes, 8,                                   \
 134           "Default object alignment in bytes, 8 is minimum")                \
 135           range(8, 256)                                                     \
 136           constraint(ObjectAlignmentInBytesConstraintFunc, AtParse)
 137 
 138 #else
 139 // !_LP64
 140 
 141 #define LP64_RUNTIME_FLAGS(develop,                                         \
 142                            develop_pd,                                      \
 143                            product,                                         \
 144                            product_pd,                                      \
 145                            notproduct,                                      \
 146                            range,                                           \
 147                            constraint)
 148 const bool UseCompressedOops = false;
 149 const bool UseCompressedClassPointers = false;
 150 const int ObjectAlignmentInBytes = 8;
 151 
 152 #endif // _LP64
 153 
 154 #define RUNTIME_FLAGS(develop,                                              \
 155                       develop_pd,                                           \
 156                       product,                                              \
 157                       product_pd,                                           \
 158                       notproduct,                                           \
 159                       range,                                                \
 160                       constraint)                                           \
 161                                                                             \
 162   notproduct(bool, CheckCompressedOops, true,                               \
 163           "Generate checks in encoding/decoding code in debug VM")          \
 164                                                                             \
 165   product(uintx, HeapSearchSteps, 3 PPC64_ONLY(+17),                        \
 166           "Heap allocation steps through preferred address regions to find" \
 167           " where it can allocate the heap. Number of steps to take per "   \
 168           "region.")                                                        \
 169           range(1, max_uintx)                                               \
 170                                                                             \
 171   product(uint, HandshakeTimeout, 0, DIAGNOSTIC,                            \
 172           "If nonzero set a timeout in milliseconds for handshakes")        \
 173                                                                             \
 174   product(bool, AlwaysSafeConstructors, false, EXPERIMENTAL,                \
 175           "Force safe construction, as if all fields are final.")           \
 176                                                                             \
 177   product(bool, UnlockDiagnosticVMOptions, trueInDebug, DIAGNOSTIC,         \
 178           "Enable normal processing of flags relating to field diagnostics")\
 179                                                                             \
 180   product(bool, UnlockExperimentalVMOptions, false, EXPERIMENTAL,           \
 181           "Enable normal processing of flags relating to experimental "     \
 182           "features")                                                       \
 183                                                                             \
 184   product(bool, JavaMonitorsInStackTrace, true,                             \
 185           "Print information about Java monitor locks when the stacks are " \
 186           "dumped")                                                         \
 187                                                                             \
 188   product_pd(bool, UseLargePages,                                           \
 189           "Use large page memory")                                          \
 190                                                                             \
 191   product_pd(bool, UseLargePagesIndividualAllocation,                       \
 192           "Allocate large pages individually for better affinity")          \
 193                                                                             \
 194   develop(bool, LargePagesIndividualAllocationInjectError, false,           \
 195           "Fail large pages individual allocation")                         \
 196                                                                             \
 197   product(bool, UseNUMA, false,                                             \
 198           "Use NUMA if available")                                          \
 199                                                                             \
 200   product(bool, UseNUMAInterleaving, false,                                 \
 201           "Interleave memory across NUMA nodes if available")               \
 202                                                                             \
 203   product(size_t, NUMAInterleaveGranularity, 2*M,                           \
 204           "Granularity to use for NUMA interleaving on Windows OS")         \
 205           constraint(NUMAInterleaveGranularityConstraintFunc, AtParse)      \
 206                                                                             \
 207   product(uintx, NUMAChunkResizeWeight, 20,                                 \
 208           "Percentage (0-100) used to weight the current sample when "      \
 209           "computing exponentially decaying average for "                   \
 210           "AdaptiveNUMAChunkSizing")                                        \
 211           range(0, 100)                                                     \
 212                                                                             \
 213   product(size_t, NUMASpaceResizeRate, 1*G,                                 \
 214           "Do not reallocate more than this amount per collection")         \
 215           range(0, max_uintx)                                               \
 216                                                                             \
 217   product(bool, UseAdaptiveNUMAChunkSizing, true,                           \
 218           "Enable adaptive chunk sizing for NUMA")                          \
 219                                                                             \
 220   product(bool, NUMAStats, false,                                           \
 221           "Print NUMA stats in detailed heap information")                  \
 222                                                                             \
 223   product(uintx, NUMAPageScanRate, 256,                                     \
 224           "Maximum number of pages to include in the page scan procedure")  \
 225           range(0, max_uintx)                                               \
 226                                                                             \
 227   product(bool, UseAES, false,                                              \
 228           "Control whether AES instructions are used when available")       \
 229                                                                             \
 230   product(bool, UseFMA, false,                                              \
 231           "Control whether FMA instructions are used when available")       \
 232                                                                             \
 233   product(bool, UseSHA, false,                                              \
 234           "Control whether SHA instructions are used when available")       \
 235                                                                             \
 236   product(bool, UseGHASHIntrinsics, false, DIAGNOSTIC,                      \
 237           "Use intrinsics for GHASH versions of crypto")                    \
 238                                                                             \
 239   product(bool, UseBASE64Intrinsics, false,                                 \
 240           "Use intrinsics for java.util.Base64")                            \
 241                                                                             \
 242   product(bool, UsePoly1305Intrinsics, false, DIAGNOSTIC,                   \
 243           "Use intrinsics for sun.security.util.math.intpoly")              \
 244                                                                             \
 245   product(size_t, LargePageSizeInBytes, 0,                                  \
 246           "Maximum large page size used (0 will use the default large "     \
 247           "page size for the environment as the maximum)")                  \
 248           range(0, max_uintx)                                               \
 249                                                                             \
 250   product(size_t, LargePageHeapSizeThreshold, 128*M,                        \
 251           "Use large pages if maximum heap is at least this big")           \
 252           range(0, max_uintx)                                               \
 253                                                                             \
 254   product(bool, ForceTimeHighResolution, false,                             \
 255           "Using high time resolution (for Win32 only)")                    \
 256                                                                             \
 257   develop(bool, TracePcPatching, false,                                     \
 258           "Trace usage of frame::patch_pc")                                 \
 259                                                                             \
 260   develop(bool, TraceRelocator, false,                                      \
 261           "Trace the bytecode relocator")                                   \
 262                                                                             \
 263                                                                             \
 264   product(bool, SafepointALot, false, DIAGNOSTIC,                           \
 265           "Generate a lot of safepoints. This works with "                  \
 266           "GuaranteedSafepointInterval")                                    \
 267                                                                             \
 268   product(bool, HandshakeALot, false, DIAGNOSTIC,                           \
 269           "Generate a lot of handshakes. This works with "                  \
 270           "GuaranteedSafepointInterval")                                    \
 271                                                                             \
 272   product_pd(bool, BackgroundCompilation,                                   \
 273           "A thread requesting compilation is not blocked during "          \
 274           "compilation")                                                    \
 275                                                                             \
 276   product(bool, MethodFlushing, true,                                       \
 277           "Reclamation of compiled methods")                                \
 278                                                                             \
 279   develop(bool, VerifyStack, false,                                         \
 280           "Verify stack of each thread when it is entering a runtime call") \
 281                                                                             \
 282   product(bool, ForceUnreachable, false, DIAGNOSTIC,                        \
 283           "Make all non code cache addresses to be unreachable by "         \
 284           "forcing use of 64bit literal fixups")                            \
 285                                                                             \
 286   develop(bool, TraceDerivedPointers, false,                                \
 287           "Trace traversal of derived pointers on stack")                   \
 288                                                                             \
 289   notproduct(bool, TraceCodeBlobStacks, false,                              \
 290           "Trace stack-walk of codeblobs")                                  \
 291                                                                             \
 292   notproduct(bool, PrintRewrites, false,                                    \
 293           "Print methods that are being rewritten")                         \
 294                                                                             \
 295   product(bool, UseInlineCaches, true,                                      \
 296           "Use Inline Caches for virtual calls ")                           \
 297                                                                             \
 298   product(size_t, InlineCacheBufferSize, 10*K, EXPERIMENTAL,                \
 299           "InlineCacheBuffer size")                                         \
 300                                                                             \
 301   product(bool, InlineArrayCopy, true, DIAGNOSTIC,                          \
 302           "Inline arraycopy native that is known to be part of "            \
 303           "base library DLL")                                               \
 304                                                                             \
 305   product(bool, InlineObjectHash, true, DIAGNOSTIC,                         \
 306           "Inline Object::hashCode() native that is known to be part "      \
 307           "of base library DLL")                                            \
 308                                                                             \
 309   product(bool, InlineNatives, true, DIAGNOSTIC,                            \
 310           "Inline natives that are known to be part of base library DLL")   \
 311                                                                             \
 312   product(bool, InlineMathNatives, true, DIAGNOSTIC,                        \
 313           "Inline SinD, CosD, etc.")                                        \
 314                                                                             \
 315   product(bool, InlineClassNatives, true, DIAGNOSTIC,                       \
 316           "Inline Class.isInstance, etc")                                   \
 317                                                                             \
 318   product(bool, InlineThreadNatives, true, DIAGNOSTIC,                      \
 319           "Inline Thread.currentThread, etc")                               \
 320                                                                             \
 321   product(bool, InlineUnsafeOps, true, DIAGNOSTIC,                          \
 322           "Inline memory ops (native methods) from Unsafe")                 \
 323                                                                             \
 324   product(bool, UseAESIntrinsics, false, DIAGNOSTIC,                        \
 325           "Use intrinsics for AES versions of crypto")                      \
 326                                                                             \
 327   product(bool, UseAESCTRIntrinsics, false, DIAGNOSTIC,                     \
 328           "Use intrinsics for the paralleled version of AES/CTR crypto")    \
 329                                                                             \
 330   product(bool, UseChaCha20Intrinsics, false, DIAGNOSTIC,                   \
 331           "Use intrinsics for the vectorized version of ChaCha20")          \
 332                                                                             \
 333   product(bool, UseMD5Intrinsics, false, DIAGNOSTIC,                        \
 334           "Use intrinsics for MD5 crypto hash function")                    \
 335                                                                             \
 336   product(bool, UseSHA1Intrinsics, false, DIAGNOSTIC,                       \
 337           "Use intrinsics for SHA-1 crypto hash function. "                 \
 338           "Requires that UseSHA is enabled.")                               \
 339                                                                             \
 340   product(bool, UseSHA256Intrinsics, false, DIAGNOSTIC,                     \
 341           "Use intrinsics for SHA-224 and SHA-256 crypto hash functions. "  \
 342           "Requires that UseSHA is enabled.")                               \
 343                                                                             \
 344   product(bool, UseSHA512Intrinsics, false, DIAGNOSTIC,                     \
 345           "Use intrinsics for SHA-384 and SHA-512 crypto hash functions. "  \
 346           "Requires that UseSHA is enabled.")                               \
 347                                                                             \
 348   product(bool, UseSHA3Intrinsics, false, DIAGNOSTIC,                       \
 349           "Use intrinsics for SHA3 crypto hash function. "                  \
 350           "Requires that UseSHA is enabled.")                               \
 351                                                                             \
 352   product(bool, UseCRC32Intrinsics, false, DIAGNOSTIC,                      \
 353           "use intrinsics for java.util.zip.CRC32")                         \
 354                                                                             \
 355   product(bool, UseCRC32CIntrinsics, false, DIAGNOSTIC,                     \
 356           "use intrinsics for java.util.zip.CRC32C")                        \
 357                                                                             \
 358   product(bool, UseAdler32Intrinsics, false, DIAGNOSTIC,                    \
 359           "use intrinsics for java.util.zip.Adler32")                       \
 360                                                                             \
 361   product(bool, UseVectorizedMismatchIntrinsic, false, DIAGNOSTIC,          \
 362           "Enables intrinsification of ArraysSupport.vectorizedMismatch()") \
 363                                                                             \
 364   product(bool, UseVectorizedHashCodeIntrinsic, false, DIAGNOSTIC,          \
 365           "Enables intrinsification of ArraysSupport.vectorizedHashCode()") \
 366                                                                             \
 367   product(bool, UseCopySignIntrinsic, false, DIAGNOSTIC,                    \
 368           "Enables intrinsification of Math.copySign")                      \
 369                                                                             \
 370   product(bool, UseSignumIntrinsic, false, DIAGNOSTIC,                      \
 371           "Enables intrinsification of Math.signum")                        \
 372                                                                             \
 373   product_pd(bool, DelayCompilerStubsGeneration, DIAGNOSTIC,                \
 374           "Use Compiler thread for compiler's stubs generation")            \
 375                                                                             \
 376   product(ccstrlist, DisableIntrinsic, "", DIAGNOSTIC,                      \
 377          "do not expand intrinsics whose (internal) names appear here")     \
 378          constraint(DisableIntrinsicConstraintFunc,AfterErgo)               \
 379                                                                             \
 380   product(ccstrlist, ControlIntrinsic, "", DIAGNOSTIC,                      \
 381          "Control intrinsics using a list of +/- (internal) names, "        \
 382          "separated by commas")                                             \
 383          constraint(ControlIntrinsicConstraintFunc,AfterErgo)               \
 384                                                                             \
 385   develop(bool, TraceCallFixup, false,                                      \
 386           "Trace all call fixups")                                          \
 387                                                                             \
 388   develop(bool, DeoptimizeALot, false,                                      \
 389           "Deoptimize at every exit from the runtime system")               \
 390                                                                             \
 391   notproduct(ccstrlist, DeoptimizeOnlyAt, "",                               \
 392           "A comma separated list of bcis to deoptimize at")                \
 393                                                                             \
 394   develop(bool, DeoptimizeRandom, false,                                    \
 395           "Deoptimize random frames on random exit from the runtime system")\
 396                                                                             \
 397   notproduct(bool, ZombieALot, false,                                       \
 398           "Create non-entrant nmethods at exit from the runtime system")    \
 399                                                                             \
 400   notproduct(bool, WalkStackALot, false,                                    \
 401           "Trace stack (no print) at every exit from the runtime system")   \
 402                                                                             \
 403   develop(bool, DeoptimizeObjectsALot, false,                               \
 404           "For testing purposes concurrent threads revert optimizations "   \
 405           "based on escape analysis at intervals given with "               \
 406           "DeoptimizeObjectsALotInterval=n. The thread count is given "     \
 407           "with DeoptimizeObjectsALotThreadCountSingle and "                \
 408           "DeoptimizeObjectsALotThreadCountAll.")                           \
 409                                                                             \
 410   develop(uint64_t, DeoptimizeObjectsALotInterval, 5,                       \
 411           "Interval for DeoptimizeObjectsALot.")                            \
 412           range(0, max_jlong)                                               \
 413                                                                             \
 414   develop(int, DeoptimizeObjectsALotThreadCountSingle, 1,                   \
 415           "The number of threads that revert optimizations based on "       \
 416           "escape analysis for a single thread if DeoptimizeObjectsALot "   \
 417           "is enabled. The target thread is selected round robin." )        \
 418           range(0, max_jint)                                                \
 419                                                                             \
 420   develop(int, DeoptimizeObjectsALotThreadCountAll, 1,                      \
 421           "The number of threads that revert optimizations based on "       \
 422           "escape analysis for all threads if DeoptimizeObjectsALot "       \
 423           "is enabled." )                                                   \
 424           range(0, max_jint)                                                \
 425                                                                             \
 426   notproduct(bool, VerifyLastFrame, false,                                  \
 427           "Verify oops on last frame on entry to VM")                       \
 428                                                                             \
 429   product(bool, SafepointTimeout, false,                                    \
 430           "Time out and warn or fail after SafepointTimeoutDelay "          \
 431           "milliseconds if failed to reach safepoint")                      \
 432                                                                             \
 433   product(bool, AbortVMOnSafepointTimeout, false, DIAGNOSTIC,               \
 434           "Abort upon failure to reach safepoint (see SafepointTimeout)")   \
 435                                                                             \
 436   product(uint64_t, AbortVMOnSafepointTimeoutDelay, 0, DIAGNOSTIC,          \
 437           "Delay in milliseconds for option AbortVMOnSafepointTimeout")     \
 438           range(0, max_jlong)                                               \
 439                                                                             \
 440   product(bool, AbortVMOnVMOperationTimeout, false, DIAGNOSTIC,             \
 441           "Abort upon failure to complete VM operation promptly")           \
 442                                                                             \
 443   product(intx, AbortVMOnVMOperationTimeoutDelay, 1000, DIAGNOSTIC,         \
 444           "Delay in milliseconds for option AbortVMOnVMOperationTimeout")   \
 445           range(0, max_intx)                                                \
 446                                                                             \
 447   product(bool, MaxFDLimit, true,                                           \
 448           "Bump the number of file descriptors to maximum (Unix only)")     \
 449                                                                             \
 450   product(bool, LogEvents, true, DIAGNOSTIC,                                \
 451           "Enable the various ring buffer event logs")                      \
 452                                                                             \
 453   product(int, LogEventsBufferEntries, 20, DIAGNOSTIC,                      \
 454           "Number of ring buffer event logs")                               \
 455           range(1, NOT_LP64(1*K) LP64_ONLY(1*M))                            \
 456                                                                             \
 457   product(bool, BytecodeVerificationRemote, true, DIAGNOSTIC,               \
 458           "Enable the Java bytecode verifier for remote classes")           \
 459                                                                             \
 460   product(bool, BytecodeVerificationLocal, false, DIAGNOSTIC,               \
 461           "Enable the Java bytecode verifier for local classes")            \
 462                                                                             \
 463   develop(bool, VerifyStackAtCalls, false,                                  \
 464           "Verify that the stack pointer is unchanged after calls")         \
 465                                                                             \
 466   develop(bool, TraceJavaAssertions, false,                                 \
 467           "Trace java language assertions")                                 \
 468                                                                             \
 469   notproduct(bool, VerifyCodeCache, false,                                  \
 470           "Verify code cache on memory allocation/deallocation")            \
 471                                                                             \
 472   develop(bool, ZapResourceArea, trueInDebug,                               \
 473           "Zap freed resource/arena space")                                 \
 474                                                                             \
 475   notproduct(bool, ZapVMHandleArea, trueInDebug,                            \
 476           "Zap freed VM handle space")                                      \
 477                                                                             \
 478   notproduct(bool, ZapStackSegments, trueInDebug,                           \
 479           "Zap allocated/freed stack segments")                             \
 480                                                                             \
 481   develop(bool, ZapUnusedHeapArea, trueInDebug,                             \
 482           "Zap unused heap space")                                          \
 483                                                                             \
 484   develop(bool, CheckZapUnusedHeapArea, false,                              \
 485           "Check zapping of unused heap space")                             \
 486                                                                             \
 487   develop(bool, ZapFillerObjects, trueInDebug,                              \
 488           "Zap filler objects")                                             \
 489                                                                             \
 490   product(bool, ExecutingUnitTests, false,                                  \
 491           "Whether the JVM is running unit tests or not")                   \
 492                                                                             \
 493   develop(uint, ErrorHandlerTest, 0,                                        \
 494           "If > 0, provokes an error after VM initialization; the value "   \
 495           "determines which error to provoke. See controlled_crash() "      \
 496           "in vmError.cpp.")                                                \
 497           range(0, 17)                                                      \
 498                                                                             \
 499   develop(uint, TestCrashInErrorHandler, 0,                                 \
 500           "If > 0, provokes an error inside VM error handler (a secondary " \
 501           "crash). see controlled_crash() in vmError.cpp")                  \
 502           range(0, 17)                                                      \
 503                                                                             \
 504   develop(bool, TestSafeFetchInErrorHandler, false   ,                      \
 505           "If true, tests SafeFetch inside error handler.")                 \
 506                                                                             \
 507   develop(bool, TestUnresponsiveErrorHandler, false,                        \
 508           "If true, simulates an unresponsive error handler.")              \
 509                                                                             \
 510   develop(bool, Verbose, false,                                             \
 511           "Print additional debugging information from other modes")        \
 512                                                                             \
 513   develop(bool, PrintMiscellaneous, false,                                  \
 514           "Print uncategorized debugging information (requires +Verbose)")  \
 515                                                                             \
 516   develop(bool, WizardMode, false,                                          \
 517           "Print much more debugging information")                          \
 518                                                                             \
 519   product(bool, ShowMessageBoxOnError, false,                               \
 520           "Keep process alive on VM fatal error")                           \
 521                                                                             \
 522   product(bool, CreateCoredumpOnCrash, true,                                \
 523           "Create core/mini dump on VM fatal error")                        \
 524                                                                             \
 525   product(uint64_t, ErrorLogTimeout, 2 * 60,                                \
 526           "Timeout, in seconds, to limit the time spent on writing an "     \
 527           "error log in case of a crash.")                                  \
 528           range(0, (uint64_t)max_jlong/1000)                                \
 529                                                                             \
 530   product(bool, ErrorLogSecondaryErrorDetails, false, DIAGNOSTIC,           \
 531           "If enabled, show details on secondary crashes in the error log") \
 532                                                                             \
 533   develop(intx, TraceDwarfLevel, 0,                                         \
 534           "Debug levels for the dwarf parser")                              \
 535           range(0, 4)                                                       \
 536                                                                             \
 537   product(bool, SuppressFatalErrorMessage, false,                           \
 538           "Report NO fatal error message (avoid deadlock)")                 \
 539                                                                             \
 540   product(ccstrlist, OnError, "",                                           \
 541           "Run user-defined commands on fatal error; see VMError.cpp "      \
 542           "for examples")                                                   \
 543                                                                             \
 544   product(ccstrlist, OnOutOfMemoryError, "",                                \
 545           "Run user-defined commands on first java.lang.OutOfMemoryError "  \
 546           "thrown from JVM")                                                \
 547                                                                             \
 548   product(bool, HeapDumpBeforeFullGC, false, MANAGEABLE,                    \
 549           "Dump heap to file before any major stop-the-world GC "           \
 550           "(also see FullGCHeapDumpLimit)")                                 \
 551                                                                             \
 552   product(bool, HeapDumpAfterFullGC, false, MANAGEABLE,                     \
 553           "Dump heap to file after any major stop-the-world GC "            \
 554           "(also see FullGCHeapDumpLimit)")                                 \
 555                                                                             \
 556   product(uint, FullGCHeapDumpLimit, 0, MANAGEABLE,                         \
 557           "Limit the number of heap dumps triggered by "                    \
 558           "HeapDumpBeforeFullGC or HeapDumpAfterFullGC "                    \
 559           "(0 means no limit)")                                             \
 560                                                                             \
 561   product(bool, HeapDumpOnOutOfMemoryError, false, MANAGEABLE,              \
 562           "Dump heap to file when java.lang.OutOfMemoryError is thrown "    \
 563           "from JVM")                                                       \
 564                                                                             \
 565   product(ccstr, HeapDumpPath, nullptr, MANAGEABLE,                         \
 566           "When HeapDumpOnOutOfMemoryError is on, the path (filename or "   \
 567           "directory) of the dump file (defaults to java_pid<pid>.hprof "   \
 568           "in the working directory)")                                      \
 569                                                                             \
 570   product(int, HeapDumpGzipLevel, 0, MANAGEABLE,                            \
 571           "When HeapDumpOnOutOfMemoryError is on, the gzip compression "    \
 572           "level of the dump file. 0 (the default) disables gzip "          \
 573           "compression. Otherwise the level must be between 1 and 9.")      \
 574           range(0, 9)                                                       \
 575                                                                             \
 576   product(ccstr, NativeMemoryTracking, DEBUG_ONLY("summary") NOT_DEBUG("off"), \
 577           "Native memory tracking options")                                 \
 578                                                                             \
 579   product(bool, PrintNMTStatistics, false, DIAGNOSTIC,                      \
 580           "Print native memory tracking summary data if it is on")          \
 581                                                                             \
 582   product(bool, LogCompilation, false, DIAGNOSTIC,                          \
 583           "Log compilation activity in detail to LogFile")                  \
 584                                                                             \
 585   product(bool, PrintCompilation, false,                                    \
 586           "Print compilations")                                             \
 587                                                                             \
 588   product(intx, RepeatCompilation, 0, DIAGNOSTIC,                           \
 589           "Repeat compilation without installing code (number of times)")   \
 590           range(0, max_jint)                                                \
 591                                                                             \
 592   product(bool, PrintExtendedThreadInfo, false,                             \
 593           "Print more information in thread dump")                          \
 594                                                                             \
 595   product(intx, ScavengeRootsInCode, 2, DIAGNOSTIC,                         \
 596           "0: do not allow scavengable oops in the code cache; "            \
 597           "1: allow scavenging from the code cache; "                       \
 598           "2: emit as many constants as the compiler can see")              \
 599           range(0, 2)                                                       \
 600                                                                             \
 601   product(bool, AlwaysRestoreFPU, false,                                    \
 602           "Restore the FPU control word after every JNI call (expensive)")  \
 603                                                                             \
 604   product(bool, PrintCompilation2, false, DIAGNOSTIC,                       \
 605           "Print additional statistics per compilation")                    \
 606                                                                             \
 607   product(bool, PrintAdapterHandlers, false, DIAGNOSTIC,                    \
 608           "Print code generated for i2c/c2i adapters")                      \
 609                                                                             \
 610   product(bool, VerifyAdapterCalls, trueInDebug, DIAGNOSTIC,                \
 611           "Verify that i2c/c2i adapters are called properly")               \
 612                                                                             \
 613   develop(bool, VerifyAdapterSharing, false,                                \
 614           "Verify that the code for shared adapters is the equivalent")     \
 615                                                                             \
 616   product(bool, PrintAssembly, false, DIAGNOSTIC,                           \
 617           "Print assembly code (using external disassembler.so)")           \
 618                                                                             \
 619   product(ccstr, PrintAssemblyOptions, nullptr, DIAGNOSTIC,                 \
 620           "Print options string passed to disassembler.so")                 \
 621                                                                             \
 622   notproduct(bool, PrintNMethodStatistics, false,                           \
 623           "Print a summary statistic for the generated nmethods")           \
 624                                                                             \
 625   product(bool, PrintNMethods, false, DIAGNOSTIC,                           \
 626           "Print assembly code for nmethods when generated")                \
 627                                                                             \
 628   product(bool, PrintNativeNMethods, false, DIAGNOSTIC,                     \
 629           "Print assembly code for native nmethods when generated")         \
 630                                                                             \
 631   develop(bool, PrintDebugInfo, false,                                      \
 632           "Print debug information for all nmethods when generated")        \
 633                                                                             \
 634   develop(bool, PrintRelocations, false,                                    \
 635           "Print relocation information for all nmethods when generated")   \
 636                                                                             \
 637   develop(bool, PrintDependencies, false,                                   \
 638           "Print dependency information for all nmethods when generated")   \
 639                                                                             \
 640   develop(bool, PrintExceptionHandlers, false,                              \
 641           "Print exception handler tables for all nmethods when generated") \
 642                                                                             \
 643   develop(bool, StressCompiledExceptionHandlers, false,                     \
 644           "Exercise compiled exception handlers")                           \
 645                                                                             \
 646   develop(bool, InterceptOSException, false,                                \
 647           "Start debugger when an implicit OS (e.g. null pointer) "         \
 648           "exception happens")                                              \
 649                                                                             \
 650   product(bool, PrintCodeCache, false,                                      \
 651           "Print the code cache memory usage when exiting")                 \
 652                                                                             \
 653   develop(bool, PrintCodeCache2, false,                                     \
 654           "Print detailed usage information on the code cache when exiting")\
 655                                                                             \
 656   product(bool, PrintCodeCacheOnCompilation, false,                         \
 657           "Print the code cache memory usage each time a method is "        \
 658           "compiled")                                                       \
 659                                                                             \
 660   product(bool, PrintCodeHeapAnalytics, false, DIAGNOSTIC,                  \
 661           "Print code heap usage statistics on exit and on full condition") \
 662                                                                             \
 663   product(bool, PrintStubCode, false, DIAGNOSTIC,                           \
 664           "Print generated stub code")                                      \
 665                                                                             \
 666   product(bool, StackTraceInThrowable, true,                                \
 667           "Collect backtrace in throwable when exception happens")          \
 668                                                                             \
 669   product(bool, OmitStackTraceInFastThrow, true,                            \
 670           "Omit backtraces for some 'hot' exceptions in optimized code")    \
 671                                                                             \
 672   product(bool, ShowCodeDetailsInExceptionMessages, true, MANAGEABLE,       \
 673           "Show exception messages from RuntimeExceptions that contain "    \
 674           "snippets of the failing code. Disable this to improve privacy.") \
 675                                                                             \
 676   product(bool, PrintWarnings, true,                                        \
 677           "Print JVM warnings to output stream")                            \
 678                                                                             \
 679   product(bool, RegisterFinalizersAtInit, true,                             \
 680           "(Deprecated) Register finalizable objects at end of "            \
 681           "Object.<init> or after allocation")                              \
 682                                                                             \
 683   develop(bool, RegisterReferences, true,                                   \
 684           "Tell whether the VM should register soft/weak/final/phantom "    \
 685           "references")                                                     \
 686                                                                             \
 687   develop(bool, PrintCodeCacheExtension, false,                             \
 688           "Print extension of code cache")                                  \
 689                                                                             \
 690   develop(bool, UsePrivilegedStack, true,                                   \
 691           "Enable the security JVM functions")                              \
 692                                                                             \
 693   product(bool, ClassUnloading, true,                                       \
 694           "Do unloading of classes")                                        \
 695                                                                             \
 696   product(bool, ClassUnloadingWithConcurrentMark, true,                     \
 697           "Do unloading of classes with a concurrent marking cycle")        \
 698                                                                             \
 699   notproduct(bool, PrintSystemDictionaryAtExit, false,                      \
 700           "Print the system dictionary at exit")                            \
 701                                                                             \
 702   notproduct(bool, PrintClassLoaderDataGraphAtExit, false,                  \
 703           "Print the class loader data graph at exit")                      \
 704                                                                             \
 705   product(bool, AllowParallelDefineClass, false,                            \
 706           "Allow parallel defineClass requests for class loaders "          \
 707           "registering as parallel capable")                                \
 708                                                                             \
 709   product_pd(bool, DontYieldALot,                                           \
 710           "Throw away obvious excess yield calls")                          \
 711                                                                             \
 712   product(bool, DisablePrimordialThreadGuardPages, false, EXPERIMENTAL,     \
 713                "Disable the use of stack guard pages if the JVM is loaded " \
 714                "on the primordial process thread")                          \
 715                                                                             \
 716   product(bool, DoJVMTIVirtualThreadTransitions, true, EXPERIMENTAL,        \
 717                "Do JVMTI virtual thread mount/unmount transitions "         \
 718                "(disabling this flag implies no JVMTI events are posted)")  \
 719                                                                             \
 720   /* notice: the max range value here is max_jint, not max_intx  */         \
 721   /* because of overflow issue                                   */         \
 722   product(intx, AsyncDeflationInterval, 250, DIAGNOSTIC,                    \
 723           "Async deflate idle monitors every so many milliseconds when "    \
 724           "MonitorUsedDeflationThreshold is exceeded (0 is off).")          \
 725           range(0, max_jint)                                                \
 726                                                                             \
 727   /* notice: the max range value here is max_jint, not max_intx  */         \
 728   /* because of overflow issue                                   */         \
 729   product(intx, GuaranteedAsyncDeflationInterval, 60000, DIAGNOSTIC,        \
 730           "Async deflate idle monitors every so many milliseconds even "    \
 731           "when MonitorUsedDeflationThreshold is NOT exceeded (0 is off).") \
 732           range(0, max_jint)                                                \
 733                                                                             \
 734   product(size_t, AvgMonitorsPerThreadEstimate, 1024, DIAGNOSTIC,           \
 735           "Used to estimate a variable ceiling based on number of threads " \
 736           "for use with MonitorUsedDeflationThreshold (0 is off).")         \
 737           range(0, max_uintx)                                               \
 738                                                                             \
 739   /* notice: the max range value here is max_jint, not max_intx  */         \
 740   /* because of overflow issue                                   */         \
 741   product(intx, MonitorDeflationMax, 1000000, DIAGNOSTIC,                   \
 742           "The maximum number of monitors to deflate, unlink and delete "   \
 743           "at one time (minimum is 1024).")                                 \
 744           range(1024, max_jint)                                             \
 745                                                                             \
 746   product(intx, MonitorUnlinkBatch, 500, DIAGNOSTIC,                        \
 747           "The maximum number of monitors to unlink in one batch. ")        \
 748           range(1, max_jint)                                                \
 749                                                                             \
 750   product(int, MonitorUsedDeflationThreshold, 90, DIAGNOSTIC,               \
 751           "Percentage of used monitors before triggering deflation (0 is "  \
 752           "off). The check is performed on GuaranteedSafepointInterval, "   \
 753           "AsyncDeflationInterval or GuaranteedAsyncDeflationInterval, "    \
 754           "whichever is lower.")                                            \
 755           range(0, 100)                                                     \
 756                                                                             \
 757   product(uintx, NoAsyncDeflationProgressMax, 3, DIAGNOSTIC,                \
 758           "Max number of no progress async deflation attempts to tolerate " \
 759           "before adjusting the in_use_list_ceiling up (0 is off).")        \
 760           range(0, max_uintx)                                               \
 761                                                                             \
 762   product(intx, hashCode, 5, EXPERIMENTAL,                                  \
 763                "(Unstable) select hashCode generation algorithm")           \
 764                                                                             \
 765   product(bool, ReduceSignalUsage, false,                                   \
 766           "Reduce the use of OS signals in Java and/or the VM")             \
 767                                                                             \
 768   develop(bool, LoadLineNumberTables, true,                                 \
 769           "Tell whether the class file parser loads line number tables")    \
 770                                                                             \
 771   develop(bool, LoadLocalVariableTables, true,                              \
 772           "Tell whether the class file parser loads local variable tables") \
 773                                                                             \
 774   develop(bool, LoadLocalVariableTypeTables, true,                          \
 775           "Tell whether the class file parser loads local variable type"    \
 776           "tables")                                                         \
 777                                                                             \
 778   product(bool, AllowUserSignalHandlers, false,                             \
 779           "Application will install primary signal handlers for the JVM "   \
 780           "(Unix only)")                                                    \
 781                                                                             \
 782   product(bool, UseSignalChaining, true,                                    \
 783           "Use signal-chaining to invoke signal handlers installed "        \
 784           "by the application (Unix only)")                                 \
 785                                                                             \
 786   product(bool, RestoreMXCSROnJNICalls, false,                              \
 787           "Restore MXCSR when returning from JNI calls")                    \
 788                                                                             \
 789   product(bool, CheckJNICalls, false,                                       \
 790           "Verify all arguments to JNI calls")                              \
 791                                                                             \
 792   product(bool, UseFastJNIAccessors, true,                                  \
 793           "Use optimized versions of Get<Primitive>Field")                  \
 794                                                                             \
 795   product(intx, MaxJNILocalCapacity, 65536,                                 \
 796           "Maximum allowable local JNI handle capacity to "                 \
 797           "EnsureLocalCapacity() and PushLocalFrame(), "                    \
 798           "where <= 0 is unlimited, default: 65536")                        \
 799           range(min_intx, max_intx)                                         \
 800                                                                             \
 801   product(bool, EagerXrunInit, false,                                       \
 802           "Eagerly initialize -Xrun libraries; allows startup profiling, "  \
 803           "but not all -Xrun libraries may support the state of the VM "    \
 804           "at this time")                                                   \
 805                                                                             \
 806   product(bool, PreserveAllAnnotations, false,                              \
 807           "Preserve RuntimeInvisibleAnnotations as well "                   \
 808           "as RuntimeVisibleAnnotations")                                   \
 809                                                                             \
 810   develop(uintx, PreallocatedOutOfMemoryErrorCount, 4,                      \
 811           "Number of OutOfMemoryErrors preallocated with backtrace")        \
 812                                                                             \
 813   product(bool, UseXMMForArrayCopy, false,                                  \
 814           "Use SSE2 MOVQ instruction for Arraycopy")                        \
 815                                                                             \
 816   notproduct(bool, PrintFieldLayout, false,                                 \
 817           "Print field layout for each class")                              \
 818                                                                             \
 819   /* Need to limit the extent of the padding to reasonable size.          */\
 820   /* 8K is well beyond the reasonable HW cache line size, even with       */\
 821   /* aggressive prefetching, while still leaving the room for segregating */\
 822   /* among the distinct pages.                                            */\
 823   product(int, ContendedPaddingWidth, 128,                                  \
 824           "How many bytes to pad the fields/classes marked @Contended with")\
 825           range(0, 8192)                                                    \
 826           constraint(ContendedPaddingWidthConstraintFunc,AfterErgo)         \
 827                                                                             \
 828   product(bool, EnableContended, true,                                      \
 829           "Enable @Contended annotation support")                           \
 830                                                                             \
 831   product(bool, RestrictContended, true,                                    \
 832           "Restrict @Contended to trusted classes")                         \
 833                                                                             \
 834   product(int, DiagnoseSyncOnValueBasedClasses, 0, DIAGNOSTIC,              \
 835              "Detect and take action upon identifying synchronization on "  \
 836              "value based classes. Modes: "                                 \
 837              "0: off; "                                                     \
 838              "1: exit with fatal error; "                                   \
 839              "2: log message to stdout. Output file can be specified with " \
 840              "   -Xlog:valuebasedclasses. If JFR is running it will "       \
 841              "   also generate JFR events.")                                \
 842              range(0, 2)                                                    \
 843                                                                             \
 844   product(bool, ExitOnOutOfMemoryError, false,                              \
 845           "JVM exits on the first occurrence of an out-of-memory error "    \
 846           "thrown from JVM")                                                \
 847                                                                             \
 848   product(bool, CrashOnOutOfMemoryError, false,                             \
 849           "JVM aborts, producing an error log and core/mini dump, on the "  \
 850           "first occurrence of an out-of-memory error thrown from JVM")     \
 851                                                                             \
 852   product(intx, UserThreadWaitAttemptsAtExit, 30,                           \
 853           "The number of times to wait for user threads to stop executing " \
 854           "native code during JVM exit. Each wait lasts 10 milliseconds. "  \
 855           "The maximum number of waits is 1000, to wait at most 10 "        \
 856           "seconds.")                                                       \
 857           range(0, 1000)                                                    \
 858                                                                             \
 859   /* tracing */                                                             \
 860                                                                             \
 861   develop(bool, StressRewriter, false,                                      \
 862           "Stress linktime bytecode rewriting")                             \
 863                                                                             \
 864   product(ccstr, TraceJVMTI, nullptr,                                       \
 865           "Trace flags for JVMTI functions and events")                     \
 866                                                                             \
 867   product(bool, StressLdcRewrite, false, DIAGNOSTIC,                        \
 868           "Force ldc -> ldc_w rewrite during RedefineClasses. "             \
 869           "This option can change an EMCP method into an obsolete method "  \
 870           "and can affect tests that expect specific methods to be EMCP. "  \
 871           "This option should be used with caution.")                       \
 872                                                                             \
 873   product(bool, AllowRedefinitionToAddDeleteMethods, false,                 \
 874           "(Deprecated) Allow redefinition to add and delete private "      \
 875           "static or final methods for compatibility with old releases")    \
 876                                                                             \
 877   develop(bool, TraceBytecodes, false,                                      \
 878           "Trace bytecode execution")                                       \
 879                                                                             \
 880   notproduct(bool, TraceInvocationCounterOverflow, false,                   \
 881           "Trace method invocation counter overflow")                       \
 882                                                                             \
 883   develop(bool, TraceInlineCacheClearing, false,                            \
 884           "Trace clearing of inline caches in nmethods")                    \
 885                                                                             \
 886   develop(bool, VerifyDependencies, trueInDebug,                            \
 887           "Exercise and verify the compilation dependency mechanism")       \
 888                                                                             \
 889   develop(bool, TraceNewOopMapGeneration, false,                            \
 890           "Trace OopMapGeneration")                                         \
 891                                                                             \
 892   develop(bool, TraceNewOopMapGenerationDetailed, false,                    \
 893           "Trace OopMapGeneration: print detailed cell states")             \
 894                                                                             \
 895   develop(bool, TimeOopMap, false,                                          \
 896           "Time calls to GenerateOopMap::compute_map() in sum")             \
 897                                                                             \
 898   develop(bool, TimeOopMap2, false,                                         \
 899           "Time calls to GenerateOopMap::compute_map() individually")       \
 900                                                                             \
 901   develop(bool, TraceOopMapRewrites, false,                                 \
 902           "Trace rewriting of methods during oop map generation")           \
 903                                                                             \
 904   develop(bool, TraceICBuffer, false,                                       \
 905           "Trace usage of IC buffer")                                       \
 906                                                                             \
 907   develop(bool, TraceCompiledIC, false,                                     \
 908           "Trace changes of compiled IC")                                   \
 909                                                                             \
 910   develop(bool, FLSVerifyDictionary, false,                                 \
 911           "Do lots of (expensive) FLS dictionary verification")             \
 912                                                                             \
 913   product(uintx, ProcessDistributionStride, 4,                              \
 914           "Stride through processors when distributing processes")          \
 915           range(0, max_juint)                                               \
 916                                                                             \
 917   develop(bool, TraceFinalizerRegistration, false,                          \
 918           "Trace registration of final references")                         \
 919                                                                             \
 920   product(bool, IgnoreEmptyClassPaths, false,                               \
 921           "Ignore empty path elements in -classpath")                       \
 922                                                                             \
 923   product(bool, PrintHeapAtSIGBREAK, true,                                  \
 924           "Print heap layout in response to SIGBREAK")                      \
 925                                                                             \
 926   product(bool, PrintClassHistogram, false, MANAGEABLE,                     \
 927           "Print a histogram of class instances")                           \
 928                                                                             \
 929   product(double, ObjectCountCutOffPercent, 0.5, EXPERIMENTAL,              \
 930           "The percentage of the used heap that the instances of a class "  \
 931           "must occupy for the class to generate a trace event")            \
 932           range(0.0, 100.0)                                                 \
 933                                                                             \
 934   /* JVMTI heap profiling */                                                \
 935                                                                             \
 936   product(bool, VerifyBeforeIteration, false, DIAGNOSTIC,                   \
 937           "Verify memory system before JVMTI iteration")                    \
 938                                                                             \
 939   /* compiler */                                                            \
 940                                                                             \
 941   /* notice: the max range value here is max_jint, not max_intx  */         \
 942   /* because of overflow issue                                   */         \
 943   product(intx, CICompilerCount, CI_COMPILER_COUNT,                         \
 944           "Number of compiler threads to run")                              \
 945           range(0, max_jint)                                                \
 946           constraint(CICompilerCountConstraintFunc, AfterErgo)              \
 947                                                                             \
 948   product(bool, UseDynamicNumberOfCompilerThreads, true,                    \
 949           "Dynamically choose the number of parallel compiler threads")     \
 950                                                                             \
 951   product(bool, ReduceNumberOfCompilerThreads, true, DIAGNOSTIC,            \
 952              "Reduce the number of parallel compiler threads when they "    \
 953              "are not used")                                                \
 954                                                                             \
 955   product(bool, TraceCompilerThreads, false, DIAGNOSTIC,                    \
 956              "Trace creation and removal of compiler threads")              \
 957                                                                             \
 958   product(ccstr, LogClassLoadingCauseFor, nullptr,                          \
 959           "Apply -Xlog:class+load+cause* to classes whose fully "           \
 960           "qualified name contains this string (\"*\" matches "             \
 961           "any class).")                                                    \
 962                                                                             \
 963   develop(bool, InjectCompilerCreationFailure, false,                       \
 964           "Inject thread creation failures for "                            \
 965           "UseDynamicNumberOfCompilerThreads")                              \
 966                                                                             \
 967   develop(bool, GenerateSynchronizationCode, true,                          \
 968           "generate locking/unlocking code for synchronized methods and "   \
 969           "monitors")                                                       \
 970                                                                             \
 971   product_pd(bool, ImplicitNullChecks, DIAGNOSTIC,                          \
 972           "Generate code for implicit null checks")                         \
 973                                                                             \
 974   product_pd(bool, TrapBasedNullChecks,                                     \
 975           "Generate code for null checks that uses a cmp and trap "         \
 976           "instruction raising SIGTRAP.  This is only used if an access to" \
 977           "null (+offset) will not raise a SIGSEGV, i.e.,"                  \
 978           "ImplicitNullChecks don't work (PPC64).")                         \
 979                                                                             \
 980   product(bool, EnableThreadSMRStatistics, trueInDebug, DIAGNOSTIC,         \
 981              "Enable Thread SMR Statistics")                                \
 982                                                                             \
 983   product(bool, UseNotificationThread, true,                                \
 984           "Use Notification Thread")                                        \
 985                                                                             \
 986   product(bool, Inline, true,                                               \
 987           "Enable inlining")                                                \
 988                                                                             \
 989   product(bool, ClipInlining, true,                                         \
 990           "Clip inlining if aggregate method exceeds DesiredMethodLimit")   \
 991                                                                             \
 992   develop(bool, UseCHA, true,                                               \
 993           "Enable CHA")                                                     \
 994                                                                             \
 995   product(bool, UseVtableBasedCHA, true,  DIAGNOSTIC,                       \
 996           "Use vtable information during CHA")                              \
 997                                                                             \
 998   product(bool, UseTypeProfile, true,                                       \
 999           "Check interpreter profile for historically monomorphic calls")   \
1000                                                                             \
1001   product(bool, PrintInlining, false, DIAGNOSTIC,                           \
1002           "Print inlining optimizations")                                   \
1003                                                                             \
1004   product(bool, UsePopCountInstruction, false,                              \
1005           "Use population count instruction")                               \
1006                                                                             \
1007   develop(bool, TraceMethodReplacement, false,                              \
1008           "Print when methods are replaced do to recompilation")            \
1009                                                                             \
1010   product(bool, PrintMethodFlushingStatistics, false, DIAGNOSTIC,           \
1011           "print statistics about method flushing")                         \
1012                                                                             \
1013   product(intx, MinPassesBeforeFlush, 10, DIAGNOSTIC,                       \
1014           "Minimum number of sweeper passes before an nmethod "             \
1015           "can be flushed")                                                 \
1016           range(0, max_intx)                                                \
1017                                                                             \
1018   develop(bool, StressCodeBuffers, false,                                   \
1019           "Exercise code buffer expansion and other rare state changes")    \
1020                                                                             \
1021   product(bool, DebugNonSafepoints, trueInDebug, DIAGNOSTIC,                \
1022           "Generate extra debugging information for non-safepoints in "     \
1023           "nmethods")                                                       \
1024                                                                             \
1025   product(bool, PrintVMOptions, false,                                      \
1026           "Print flags that appeared on the command line")                  \
1027                                                                             \
1028   product(bool, IgnoreUnrecognizedVMOptions, false,                         \
1029           "Ignore unrecognized VM options")                                 \
1030                                                                             \
1031   product(bool, PrintCommandLineFlags, false,                               \
1032           "Print flags specified on command line or set by ergonomics")     \
1033                                                                             \
1034   product(bool, PrintFlagsInitial, false,                                   \
1035           "Print all VM flags before argument processing and exit VM")      \
1036                                                                             \
1037   product(bool, PrintFlagsFinal, false,                                     \
1038           "Print all VM flags after argument and ergonomic processing")     \
1039                                                                             \
1040   notproduct(bool, PrintFlagsWithComments, false,                           \
1041           "Print all VM flags with default values and descriptions and "    \
1042           "exit")                                                           \
1043                                                                             \
1044   product(bool, PrintFlagsRanges, false,                                    \
1045           "Print VM flags and their ranges")                                \
1046                                                                             \
1047   product(bool, SerializeVMOutput, true, DIAGNOSTIC,                        \
1048           "Use a mutex to serialize output to tty and LogFile")             \
1049                                                                             \
1050   product(bool, DisplayVMOutput, true, DIAGNOSTIC,                          \
1051           "Display all VM output on the tty, independently of LogVMOutput") \
1052                                                                             \
1053   product(bool, LogVMOutput, false, DIAGNOSTIC,                             \
1054           "Save VM output to LogFile")                                      \
1055                                                                             \
1056   product(ccstr, LogFile, nullptr, DIAGNOSTIC,                              \
1057           "If LogVMOutput or LogCompilation is on, save VM output to "      \
1058           "this file [default: ./hotspot_%p.log] (%p replaced with pidNNN)")\
1059                                                                             \
1060   product(ccstr, ErrorFile, nullptr,                                        \
1061           "If an error occurs, save the error data to this file "           \
1062           "[default: ./hs_err_%p.log] (%p replaced with pidNNN)")           \
1063                                                                             \
1064   product(bool, ExtensiveErrorReports,                                      \
1065           PRODUCT_ONLY(false) NOT_PRODUCT(true),                            \
1066           "Error reports are more extensive.")                              \
1067                                                                             \
1068   product(bool, DisplayVMOutputToStderr, false,                             \
1069           "If DisplayVMOutput is true, display all VM output to stderr")    \
1070                                                                             \
1071   product(bool, DisplayVMOutputToStdout, false,                             \
1072           "If DisplayVMOutput is true, display all VM output to stdout")    \
1073                                                                             \
1074   product(bool, ErrorFileToStderr, false,                                   \
1075           "If true, error data is printed to stderr instead of a file")     \
1076                                                                             \
1077   product(bool, ErrorFileToStdout, false,                                   \
1078           "If true, error data is printed to stdout instead of a file")     \
1079                                                                             \
1080   develop(bool, VerifyHeavyMonitors, false,                                 \
1081           "Checks that no stack locking happens when using "                \
1082           "-XX:LockingMode=0 (LM_MONITOR)")                                 \
1083                                                                             \
1084   product(bool, PrintStringTableStatistics, false,                          \
1085           "print statistics about the StringTable and SymbolTable")         \
1086                                                                             \
1087   product(bool, VerifyStringTableAtExit, false, DIAGNOSTIC,                 \
1088           "verify StringTable contents at exit")                            \
1089                                                                             \
1090   notproduct(bool, PrintSymbolTableSizeHistogram, false,                    \
1091           "print histogram of the symbol table")                            \
1092                                                                             \
1093   product(ccstr, AbortVMOnException, nullptr, DIAGNOSTIC,                   \
1094           "Call fatal if this exception is thrown.  Example: "              \
1095           "java -XX:AbortVMOnException=java.lang.NullPointerException Foo") \
1096                                                                             \
1097   product(ccstr, AbortVMOnExceptionMessage, nullptr, DIAGNOSTIC,            \
1098           "Call fatal if the exception pointed by AbortVMOnException "      \
1099           "has this message")                                               \
1100                                                                             \
1101   develop(bool, DebugVtables, false,                                        \
1102           "add debugging code to vtable dispatch")                          \
1103                                                                             \
1104   product(bool, RangeCheckElimination, true,                                \
1105           "Eliminate range checks")                                         \
1106                                                                             \
1107   develop_pd(bool, UncommonNullCast,                                        \
1108           "track occurrences of null in casts; adjust compiler tactics")    \
1109                                                                             \
1110   develop(bool, TypeProfileCasts,  true,                                    \
1111           "treat casts like calls for purposes of type profiling")          \
1112                                                                             \
1113   develop(bool, TraceLivenessGen, false,                                    \
1114           "Trace the generation of liveness analysis information")          \
1115                                                                             \
1116   notproduct(bool, TraceLivenessQuery, false,                               \
1117           "Trace queries of liveness analysis information")                 \
1118                                                                             \
1119   notproduct(bool, CollectIndexSetStatistics, false,                        \
1120           "Collect information about IndexSets")                            \
1121                                                                             \
1122   develop(int, FastAllocateSizeLimit, 128*K,                                \
1123           /* Note:  This value is zero mod 1<<13 for a cheap sparc set. */  \
1124           "Inline allocations larger than this in doublewords must go slow")\
1125                                                                             \
1126   product_pd(bool, CompactStrings,                                          \
1127           "Enable Strings to use single byte chars in backing store")       \
1128                                                                             \
1129   product_pd(uint, TypeProfileLevel,                                        \
1130           "=XYZ, with Z: Type profiling of arguments at call; "             \
1131                      "Y: Type profiling of return value at call; "          \
1132                      "X: Type profiling of parameters to methods; "         \
1133           "X, Y and Z in 0=off ; 1=jsr292 only; 2=all methods")             \
1134           constraint(TypeProfileLevelConstraintFunc, AfterErgo)             \
1135                                                                             \
1136   product(int, TypeProfileArgsLimit,     2,                                 \
1137           "max number of call arguments to consider for type profiling")    \
1138           range(0, 16)                                                      \
1139                                                                             \
1140   product(int, TypeProfileParmsLimit,    2,                                 \
1141           "max number of incoming parameters to consider for type profiling"\
1142           ", -1 for all")                                                   \
1143           range(-1, 64)                                                     \
1144                                                                             \
1145   /* statistics */                                                          \
1146   develop(bool, CountCompiledCalls, false,                                  \
1147           "Count method invocations")                                       \
1148                                                                             \
1149   notproduct(bool, ICMissHistogram, false,                                  \
1150           "Produce histogram of IC misses")                                 \
1151                                                                             \
1152   /* interpreter */                                                         \
1153   product_pd(bool, RewriteBytecodes,                                        \
1154           "Allow rewriting of bytecodes (bytecodes are not immutable)")     \
1155                                                                             \
1156   product_pd(bool, RewriteFrequentPairs,                                    \
1157           "Rewrite frequently used bytecode pairs into a single bytecode")  \
1158                                                                             \
1159   product(bool, PrintInterpreter, false, DIAGNOSTIC,                        \
1160           "Print the generated interpreter code")                           \
1161                                                                             \
1162   product(bool, UseInterpreter, true,                                       \
1163           "Use interpreter for non-compiled methods")                       \
1164                                                                             \
1165   develop(bool, UseFastSignatureHandlers, true,                             \
1166           "Use fast signature handlers for native calls")                   \
1167                                                                             \
1168   product(bool, UseLoopCounter, true,                                       \
1169           "Increment invocation counter on backward branch")                \
1170                                                                             \
1171   product_pd(bool, UseOnStackReplacement,                                   \
1172           "Use on stack replacement, calls runtime if invoc. counter "      \
1173           "overflows in loop")                                              \
1174                                                                             \
1175   notproduct(bool, TraceOnStackReplacement, false,                          \
1176           "Trace on stack replacement")                                     \
1177                                                                             \
1178   product_pd(bool, PreferInterpreterNativeStubs,                            \
1179           "Use always interpreter stubs for native methods invoked via "    \
1180           "interpreter")                                                    \
1181                                                                             \
1182   product(bool, CountBytecodes, false, DIAGNOSTIC,                          \
1183           "Count number of bytecodes executed")                             \
1184                                                                             \
1185   product(bool, CountBytecodesPerThread, false, DIAGNOSTIC,                 \
1186           "Count number of bytecodes executed per thread")                  \
1187                                                                             \
1188   product(bool, PrintBytecodeHistogram, false, DIAGNOSTIC,                  \
1189           "Print histogram of the executed bytecodes")                      \
1190                                                                             \
1191   product(double, PrintBytecodeHistogramCutoff, 0.01,                       \
1192           "Print cutoff for histogram of the executed bytecodes")           \
1193           range(0.0, 100.0)                                                 \
1194                                                                             \
1195   develop(bool, PrintBytecodePairHistogram, false,                          \
1196           "Print histogram of the executed bytecode pairs")                 \
1197                                                                             \
1198   product(bool, PrintSignatureHandlers, false, DIAGNOSTIC,                  \
1199           "Print code generated for native method signature handlers")      \
1200                                                                             \
1201   develop(bool, VerifyOops, false,                                          \
1202           "Do plausibility checks for oops")                                \
1203                                                                             \
1204   develop(bool, CheckUnhandledOops, false,                                  \
1205           "Check for unhandled oops in VM code")                            \
1206                                                                             \
1207   develop(bool, VerifyJNIFields, trueInDebug,                               \
1208           "Verify jfieldIDs for instance fields")                           \
1209                                                                             \
1210   develop(bool, VerifyFPU, false,                                           \
1211           "Verify FPU state (check for NaN's, etc.)")                       \
1212                                                                             \
1213   develop(bool, VerifyActivationFrameSize, false,                           \
1214           "Verify that activation frame didn't become smaller than its "    \
1215           "minimal size")                                                   \
1216                                                                             \
1217   develop(bool, TraceFrequencyInlining, false,                              \
1218           "Trace frequency based inlining")                                 \
1219                                                                             \
1220   develop_pd(bool, InlineIntrinsics,                                        \
1221           "Use intrinsics in Interpreter that can be statically resolved")  \
1222                                                                             \
1223   product_pd(bool, ProfileInterpreter,                                      \
1224           "Profile at the bytecode level during interpretation")            \
1225                                                                             \
1226   develop_pd(bool, ProfileTraps,                                            \
1227           "Profile deoptimization traps at the bytecode level")             \
1228                                                                             \
1229   product(intx, ProfileMaturityPercentage, 20,                              \
1230           "number of method invocations/branches (expressed as % of "       \
1231           "CompileThreshold) before using the method's profile")            \
1232           range(0, 100)                                                     \
1233                                                                             \
1234   product(bool, ForceProfiling, false, DIAGNOSTIC,                          \
1235           "Eagerly allocate MDOs")                                          \
1236                                                                             \
1237   product(bool, PrintMethodData, false, DIAGNOSTIC,                         \
1238           "Print the results of +ProfileInterpreter at end of run")         \
1239                                                                             \
1240   develop(bool, VerifyDataPointer, trueInDebug,                             \
1241           "Verify the method data pointer during interpreter profiling")    \
1242                                                                             \
1243   notproduct(bool, CrashGCForDumpingJavaThread, false,                      \
1244           "Manually make GC thread crash then dump java stack trace;  "     \
1245           "Test only")                                                      \
1246                                                                             \
1247   /* compilation */                                                         \
1248   product(bool, UseCompiler, true,                                          \
1249           "Use Just-In-Time compilation")                                   \
1250                                                                             \
1251   develop(intx, CounterHalfLifeTime,    30,                                 \
1252           "Half-life time of invocation counters (in seconds)")             \
1253                                                                             \
1254   product(bool, AlwaysCompileLoopMethods, false,                            \
1255           "When using recompilation, never interpret methods "              \
1256           "containing loops")                                               \
1257                                                                             \
1258   product(int,  AllocatePrefetchStyle, 1,                                   \
1259           "0 = no prefetch, "                                               \
1260           "1 = generate prefetch instructions for each allocation, "        \
1261           "2 = use TLAB watermark to gate allocation prefetch, "            \
1262           "3 = generate one prefetch instruction per cache line")           \
1263           range(0, 3)                                                       \
1264                                                                             \
1265   product(int,  AllocatePrefetchDistance, -1,                               \
1266           "Distance to prefetch ahead of allocation pointer. "              \
1267           "-1: use system-specific value (automatically determined")        \
1268           range(-1, 512)                                                    \
1269                                                                             \
1270   product(int,  AllocatePrefetchLines, 3,                                   \
1271           "Number of lines to prefetch ahead of array allocation pointer")  \
1272           range(1, 64)                                                      \
1273                                                                             \
1274   product(int,  AllocateInstancePrefetchLines, 1,                           \
1275           "Number of lines to prefetch ahead of instance allocation "       \
1276           "pointer")                                                        \
1277           range(1, 64)                                                      \
1278                                                                             \
1279   product(int,  AllocatePrefetchStepSize, 16,                               \
1280           "Step size in bytes of sequential prefetch instructions")         \
1281           range(1, 512)                                                     \
1282           constraint(AllocatePrefetchStepSizeConstraintFunc,AfterMemoryInit)\
1283                                                                             \
1284   product(intx,  AllocatePrefetchInstr, 0,                                  \
1285           "Select instruction to prefetch ahead of allocation pointer")     \
1286           constraint(AllocatePrefetchInstrConstraintFunc, AfterMemoryInit)  \
1287                                                                             \
1288   /* deoptimization */                                                      \
1289   product(bool, TraceDeoptimization, false, DIAGNOSTIC,                     \
1290           "Trace deoptimization")                                           \
1291                                                                             \
1292   develop(bool, PrintDeoptimizationDetails, false,                          \
1293           "Print more information about deoptimization")                    \
1294                                                                             \
1295   develop(bool, DebugDeoptimization, false,                                 \
1296           "Tracing various information while debugging deoptimization")     \
1297                                                                             \
1298   product(double, SelfDestructTimer, 0.0,                                   \
1299           "Will cause VM to terminate after a given time "                  \
1300           "(in fractional minutes) "                                        \
1301           "(0.0 means off)")                                                \
1302           range(0.0, (double)max_intx)                                      \
1303                                                                             \
1304   product(int, MaxJavaStackTraceDepth, 1024,                                \
1305           "The maximum number of lines in the stack trace for Java "        \
1306           "exceptions (0 means all)")                                       \
1307           range(0, max_jint/2)                                              \
1308                                                                             \
1309   /* notice: the max range value here is max_jint, not max_intx  */         \
1310   /* because of overflow issue                                   */         \
1311   product(intx, GuaranteedSafepointInterval, 1000, DIAGNOSTIC,              \
1312           "Guarantee a safepoint (at least) every so many milliseconds "    \
1313           "(0 means none)")                                                 \
1314           range(0, max_jint)                                                \
1315                                                                             \
1316   product(double, SafepointTimeoutDelay, 10000,                             \
1317           "Delay in milliseconds for option SafepointTimeout; "             \
1318           "supports sub-millisecond resolution with fractional values.")    \
1319           range(0, max_jlongDouble LP64_ONLY(/MICROUNITS))                  \
1320                                                                             \
1321   product(bool, UseSystemMemoryBarrier, false,                              \
1322           "Try to enable system memory barrier if supported by OS")         \
1323                                                                             \
1324   product(intx, NmethodSweepActivity, 4,                                    \
1325           "Removes cold nmethods from code cache if > 0. Higher values "    \
1326           "result in more aggressive sweeping")                             \
1327           range(0, 2000)                                                    \
1328                                                                             \
1329   develop(intx, MallocCatchPtr, -1,                                         \
1330           "Hit breakpoint when mallocing/freeing this pointer")             \
1331                                                                             \
1332   develop(int, StackPrintLimit, 100,                                        \
1333           "number of stack frames to print in VM-level stack dump")         \
1334                                                                             \
1335   product(int, ErrorLogPrintCodeLimit, 3, DIAGNOSTIC,                       \
1336           "max number of compiled code units to print in error log")        \
1337           range(0, VMError::max_error_log_print_code)                       \
1338                                                                             \
1339   notproduct(int, MaxElementPrintSize, 256,                                 \
1340           "maximum number of elements to print")                            \
1341                                                                             \
1342   notproduct(intx, MaxSubklassPrintSize, 4,                                 \
1343           "maximum number of subklasses to print when printing klass")      \
1344                                                                             \
1345   develop(intx, MaxForceInlineLevel, 100,                                   \
1346           "maximum number of nested calls that are forced for inlining "    \
1347           "(using CompileCommand or marked w/ @ForceInline)")               \
1348           range(0, max_jint)                                                \
1349                                                                             \
1350   develop(intx, MethodHistogramCutoff, 100,                                 \
1351           "The cutoff value for method invocation histogram (+CountCalls)") \
1352                                                                             \
1353   develop(intx, DontYieldALotInterval,    10,                               \
1354           "Interval between which yields will be dropped (milliseconds)")   \
1355                                                                             \
1356   notproduct(intx, DeoptimizeALotInterval,     5,                           \
1357           "Number of exits until DeoptimizeALot kicks in")                  \
1358                                                                             \
1359   notproduct(intx, ZombieALotInterval,     5,                               \
1360           "Number of exits until ZombieALot kicks in")                      \
1361                                                                             \
1362   product(ccstr, MallocLimit, nullptr, DIAGNOSTIC,                          \
1363           "Limit malloc allocation size from VM. Reaching a limit will "    \
1364           "trigger an action (see flag). This feature requires "            \
1365           "NativeMemoryTracking=summary or NativeMemoryTracking=detail."    \
1366           "Usage:"                                                          \
1367           "\"-XX:MallocLimit=<size>[:<flag>]\" sets a total limit."         \
1368           "\"-XX:MallocLimit=<category>:<size>[:<flag>][,<category>:<size>[:<flag>] ...]\"" \
1369           "sets one or more category-specific limits."                      \
1370           "<flag> defines the action upon reaching the limit:"              \
1371           "\"fatal\": end VM with a fatal error at the allocation site"     \
1372           "\"oom\"  : will mimic a native OOM"                              \
1373           "If <flag> is omitted, \"fatal\" is the default."                 \
1374           "Examples:\n"                                                     \
1375           "-XX:MallocLimit=2g"                                              \
1376           "-XX:MallocLimit=2g:oom"                                          \
1377           "-XX:MallocLimit=compiler:200m:oom,code:100m")                    \
1378                                                                             \
1379   product(intx, TypeProfileWidth, 2,                                        \
1380           "Number of receiver types to record in call/cast profile")        \
1381           range(0, 8)                                                       \
1382                                                                             \
1383   develop(intx, BciProfileWidth,      2,                                    \
1384           "Number of return bci's to record in ret profile")                \
1385                                                                             \
1386   product(intx, PerMethodRecompilationCutoff, 400,                          \
1387           "After recompiling N times, stay in the interpreter (-1=>'Inf')") \
1388           range(-1, max_intx)                                               \
1389                                                                             \
1390   product(intx, PerBytecodeRecompilationCutoff, 200,                        \
1391           "Per-BCI limit on repeated recompilation (-1=>'Inf')")            \
1392           range(-1, max_intx)                                               \
1393                                                                             \
1394   product(intx, PerMethodTrapLimit,  100,                                   \
1395           "Limit on traps (of one kind) in a method (includes inlines)")    \
1396           range(0, max_jint)                                                \
1397                                                                             \
1398   product(intx, PerMethodSpecTrapLimit,  5000, EXPERIMENTAL,                \
1399           "Limit on speculative traps (of one kind) in a method "           \
1400           "(includes inlines)")                                             \
1401           range(0, max_jint)                                                \
1402                                                                             \
1403   product(intx, PerBytecodeTrapLimit,  4,                                   \
1404           "Limit on traps (of one kind) at a particular BCI")               \
1405           range(0, max_jint)                                                \
1406                                                                             \
1407   product(int, SpecTrapLimitExtraEntries,  3, EXPERIMENTAL,                 \
1408           "Extra method data trap entries for speculation")                 \
1409                                                                             \
1410   product(double, InlineFrequencyRatio, 0.25, DIAGNOSTIC,                   \
1411           "Ratio of call site execution to caller method invocation")       \
1412                                                                             \
1413   product(double, MinInlineFrequencyRatio, 0.0085, DIAGNOSTIC,              \
1414           "Minimum ratio of call site execution to caller method"           \
1415           "invocation to be considered for inlining")                       \
1416                                                                             \
1417   develop(intx, InlineThrowCount,    50,                                    \
1418           "Force inlining of interpreted methods that throw this often")    \
1419           range(0, max_jint)                                                \
1420                                                                             \
1421   develop(intx, InlineThrowMaxSize,   200,                                  \
1422           "Force inlining of throwing methods smaller than this")           \
1423           range(0, max_jint)                                                \
1424                                                                             \
1425   product(size_t, MetaspaceSize, NOT_LP64(16 * M) LP64_ONLY(21 * M),        \
1426           "Initial threshold (in bytes) at which a garbage collection "     \
1427           "is done to reduce Metaspace usage")                              \
1428           constraint(MetaspaceSizeConstraintFunc,AfterErgo)                 \
1429                                                                             \
1430   product(size_t, MaxMetaspaceSize, max_uintx,                              \
1431           "Maximum size of Metaspaces (in bytes)")                          \
1432           constraint(MaxMetaspaceSizeConstraintFunc,AfterErgo)              \
1433                                                                             \
1434   product(size_t, CompressedClassSpaceSize, 1*G,                            \
1435           "Maximum size of class area in Metaspace when compressed "        \
1436           "class pointers are used")                                        \
1437           range(1*M, 3*G)                                                   \
1438                                                                             \
1439   develop(size_t, CompressedClassSpaceBaseAddress, 0,                       \
1440           "Force the class space to be allocated at this address or "       \
1441           "fails VM initialization (requires -Xshare=off.")                 \
1442                                                                             \
1443   develop(bool, RandomizeClassSpaceLocation, true,                          \
1444           "Randomize location of class space.")                             \
1445                                                                             \
1446   product(bool, PrintMetaspaceStatisticsAtExit, false, DIAGNOSTIC,          \
1447           "Print metaspace statistics upon VM exit.")                       \
1448                                                                             \
1449   develop(bool, MetaspaceGuardAllocations, false,                           \
1450           "Metapace allocations are guarded.")                              \
1451                                                                             \
1452   product(uintx, MinHeapFreeRatio, 40, MANAGEABLE,                          \
1453           "The minimum percentage of heap free after GC to avoid expansion."\
1454           " For most GCs this applies to the old generation. In G1 and"     \
1455           " ParallelGC it applies to the whole heap.")                      \
1456           range(0, 100)                                                     \
1457           constraint(MinHeapFreeRatioConstraintFunc,AfterErgo)              \
1458                                                                             \
1459   product(uintx, MaxHeapFreeRatio, 70, MANAGEABLE,                          \
1460           "The maximum percentage of heap free after GC to avoid shrinking."\
1461           " For most GCs this applies to the old generation. In G1 and"     \
1462           " ParallelGC it applies to the whole heap.")                      \
1463           range(0, 100)                                                     \
1464           constraint(MaxHeapFreeRatioConstraintFunc,AfterErgo)              \
1465                                                                             \
1466   product(bool, ShrinkHeapInSteps, true,                                    \
1467           "When disabled, informs the GC to shrink the java heap directly"  \
1468           " to the target size at the next full GC rather than requiring"   \
1469           " smaller steps during multiple full GCs.")                       \
1470                                                                             \
1471   product(intx, SoftRefLRUPolicyMSPerMB, 1000,                              \
1472           "Number of milliseconds per MB of free space in the heap")        \
1473           range(0, max_intx)                                                \
1474           constraint(SoftRefLRUPolicyMSPerMBConstraintFunc,AfterMemoryInit) \
1475                                                                             \
1476   product(size_t, MinHeapDeltaBytes, ScaleForWordSize(128*K),               \
1477           "The minimum change in heap space due to GC (in bytes)")          \
1478           range(0, max_uintx)                                               \
1479                                                                             \
1480   product(size_t, MinMetaspaceExpansion, ScaleForWordSize(256*K),           \
1481           "The minimum expansion of Metaspace (in bytes)")                  \
1482           range(0, max_uintx)                                               \
1483                                                                             \
1484   product(uint, MaxMetaspaceFreeRatio,    70,                               \
1485           "The maximum percentage of Metaspace free after GC to avoid "     \
1486           "shrinking")                                                      \
1487           range(0, 100)                                                     \
1488           constraint(MaxMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1489                                                                             \
1490   product(uint, MinMetaspaceFreeRatio,    40,                               \
1491           "The minimum percentage of Metaspace free after GC to avoid "     \
1492           "expansion")                                                      \
1493           range(0, 99)                                                      \
1494           constraint(MinMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1495                                                                             \
1496   product(size_t, MaxMetaspaceExpansion, ScaleForWordSize(4*M),             \
1497           "The maximum expansion of Metaspace without full GC (in bytes)")  \
1498           range(0, max_uintx)                                               \
1499                                                                             \
1500   /* stack parameters */                                                    \
1501   product_pd(intx, StackYellowPages,                                        \
1502           "Number of yellow zone (recoverable overflows) pages of size "    \
1503           "4KB. If pages are bigger yellow zone is aligned up.")            \
1504           range(MIN_STACK_YELLOW_PAGES, (DEFAULT_STACK_YELLOW_PAGES+5))     \
1505                                                                             \
1506   product_pd(intx, StackRedPages,                                           \
1507           "Number of red zone (unrecoverable overflows) pages of size "     \
1508           "4KB. If pages are bigger red zone is aligned up.")               \
1509           range(MIN_STACK_RED_PAGES, (DEFAULT_STACK_RED_PAGES+2))           \
1510                                                                             \
1511   product_pd(intx, StackReservedPages,                                      \
1512           "Number of reserved zone (reserved to annotated methods) pages"   \
1513           " of size 4KB. If pages are bigger reserved zone is aligned up.") \
1514           range(MIN_STACK_RESERVED_PAGES, (DEFAULT_STACK_RESERVED_PAGES+10))\
1515                                                                             \
1516   product(bool, RestrictReservedStack, true,                                \
1517           "Restrict @ReservedStackAccess to trusted classes")               \
1518                                                                             \
1519   /* greater stack shadow pages can't generate instruction to bang stack */ \
1520   product_pd(intx, StackShadowPages,                                        \
1521           "Number of shadow zone (for overflow checking) pages of size "    \
1522           "4KB. If pages are bigger shadow zone is aligned up. "            \
1523           "This should exceed the depth of the VM and native call stack.")  \
1524           range(MIN_STACK_SHADOW_PAGES, (DEFAULT_STACK_SHADOW_PAGES+30))    \
1525                                                                             \
1526   product_pd(intx, ThreadStackSize,                                         \
1527           "Thread Stack Size (in Kbytes)")                                  \
1528           range(0, 1 * M)                                                   \
1529                                                                             \
1530   product_pd(intx, VMThreadStackSize,                                       \
1531           "Non-Java Thread Stack Size (in Kbytes)")                         \
1532           range(0, max_intx/(1 * K))                                        \
1533                                                                             \
1534   product_pd(intx, CompilerThreadStackSize,                                 \
1535           "Compiler Thread Stack Size (in Kbytes)")                         \
1536           range(0, max_intx/(1 * K))                                        \
1537                                                                             \
1538   develop_pd(size_t, JVMInvokeMethodSlack,                                  \
1539           "Stack space (bytes) required for JVM_InvokeMethod to complete")  \
1540                                                                             \
1541   /* code cache parameters                                    */            \
1542   product_pd(uintx, CodeCacheSegmentSize, EXPERIMENTAL,                     \
1543           "Code cache segment size (in bytes) - smallest unit of "          \
1544           "allocation")                                                     \
1545           range(1, 1024)                                                    \
1546           constraint(CodeCacheSegmentSizeConstraintFunc, AfterErgo)         \
1547                                                                             \
1548   product_pd(intx, CodeEntryAlignment, EXPERIMENTAL,                        \
1549           "Code entry alignment for generated code (in bytes)")             \
1550           constraint(CodeEntryAlignmentConstraintFunc, AfterErgo)           \
1551                                                                             \
1552   product_pd(intx, OptoLoopAlignment,                                       \
1553           "Align inner loops to zero relative to this modulus")             \
1554           range(1, 128)                                                     \
1555           constraint(OptoLoopAlignmentConstraintFunc, AfterErgo)            \
1556                                                                             \
1557   product_pd(uintx, InitialCodeCacheSize,                                   \
1558           "Initial code cache size (in bytes)")                             \
1559           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1560                                                                             \
1561   develop_pd(uintx, CodeCacheMinimumUseSpace,                               \
1562           "Minimum code cache size (in bytes) required to start VM.")       \
1563           range(0, max_uintx)                                               \
1564                                                                             \
1565   product(bool, SegmentedCodeCache, false,                                  \
1566           "Use a segmented code cache")                                     \
1567                                                                             \
1568   product_pd(uintx, ReservedCodeCacheSize,                                  \
1569           "Reserved code cache size (in bytes) - maximum code cache size")  \
1570           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1571                                                                             \
1572   product_pd(uintx, NonProfiledCodeHeapSize,                                \
1573           "Size of code heap with non-profiled methods (in bytes)")         \
1574           range(0, max_uintx)                                               \
1575                                                                             \
1576   product_pd(uintx, ProfiledCodeHeapSize,                                   \
1577           "Size of code heap with profiled methods (in bytes)")             \
1578           range(0, max_uintx)                                               \
1579                                                                             \
1580   product_pd(uintx, NonNMethodCodeHeapSize,                                 \
1581           "Size of code heap with non-nmethods (in bytes)")                 \
1582           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1583                                                                             \
1584   product_pd(uintx, CodeCacheExpansionSize,                                 \
1585           "Code cache expansion size (in bytes)")                           \
1586           range(32*K, max_uintx)                                            \
1587                                                                             \
1588   product_pd(uintx, CodeCacheMinBlockLength, DIAGNOSTIC,                    \
1589           "Minimum number of segments in a code cache block")               \
1590           range(1, 100)                                                     \
1591                                                                             \
1592   notproduct(bool, ExitOnFullCodeCache, false,                              \
1593           "Exit the VM if we fill the code cache")                          \
1594                                                                             \
1595   product(bool, UseCodeCacheFlushing, true,                                 \
1596           "Remove cold/old nmethods from the code cache")                   \
1597                                                                             \
1598   product(double, SweeperThreshold, 15.0,                                   \
1599           "Threshold when a code cache unloading GC is invoked."            \
1600           "Value is percentage of ReservedCodeCacheSize.")                  \
1601           range(0.0, 100.0)                                                 \
1602                                                                             \
1603   product(uintx, StartAggressiveSweepingAt, 10,                             \
1604           "Start aggressive sweeping if X[%] of the code cache is free."    \
1605           "Segmented code cache: X[%] of the non-profiled heap."            \
1606           "Non-segmented code cache: X[%] of the total code cache")         \
1607           range(0, 100)                                                     \
1608                                                                             \
1609   /* interpreter debugging */                                               \
1610   develop(intx, BinarySwitchThreshold, 5,                                   \
1611           "Minimal number of lookupswitch entries for rewriting to binary " \
1612           "switch")                                                         \
1613                                                                             \
1614   develop(intx, StopInterpreterAt, 0,                                       \
1615           "Stop interpreter execution at specified bytecode number")        \
1616                                                                             \
1617   develop(intx, TraceBytecodesAt, 0,                                        \
1618           "Trace bytecodes starting with specified bytecode number")        \
1619                                                                             \
1620   develop(intx, TraceBytecodesStopAt, 0,                                    \
1621           "Stop bytecode tracing at the specified bytecode number")         \
1622                                                                             \
1623   /* Priorities */                                                          \
1624   product_pd(bool, UseThreadPriorities,  "Use native thread priorities")    \
1625                                                                             \
1626   product(int, ThreadPriorityPolicy, 0,                                     \
1627           "0 : Normal.                                                     "\
1628           "    VM chooses priorities that are appropriate for normal       "\
1629           "    applications.                                               "\
1630           "    On Windows applications are allowed to use higher native    "\
1631           "    priorities. However, with ThreadPriorityPolicy=0, VM will   "\
1632           "    not use the highest possible native priority,               "\
1633           "    THREAD_PRIORITY_TIME_CRITICAL, as it may interfere with     "\
1634           "    system threads. On Linux thread priorities are ignored      "\
1635           "    because the OS does not support static priority in          "\
1636           "    SCHED_OTHER scheduling class which is the only choice for   "\
1637           "    non-root, non-realtime applications.                        "\
1638           "1 : Aggressive.                                                 "\
1639           "    Java thread priorities map over to the entire range of      "\
1640           "    native thread priorities. Higher Java thread priorities map "\
1641           "    to higher native thread priorities. This policy should be   "\
1642           "    used with care, as sometimes it can cause performance       "\
1643           "    degradation in the application and/or the entire system. On "\
1644           "    Linux/BSD/macOS this policy requires root privilege or an   "\
1645           "    extended capability.")                                       \
1646           range(0, 1)                                                       \
1647                                                                             \
1648   product(bool, ThreadPriorityVerbose, false,                               \
1649           "Print priority changes")                                         \
1650                                                                             \
1651   product(int, CompilerThreadPriority, -1,                                  \
1652           "The native priority at which compiler threads should run "       \
1653           "(-1 means no change)")                                           \
1654           range(min_jint, max_jint)                                         \
1655                                                                             \
1656   product(int, VMThreadPriority, -1,                                        \
1657           "The native priority at which the VM thread should run "          \
1658           "(-1 means no change)")                                           \
1659           range(-1, 127)                                                    \
1660                                                                             \
1661   product(int, JavaPriority1_To_OSPriority, -1,                             \
1662           "Map Java priorities to OS priorities")                           \
1663           range(-1, 127)                                                    \
1664                                                                             \
1665   product(int, JavaPriority2_To_OSPriority, -1,                             \
1666           "Map Java priorities to OS priorities")                           \
1667           range(-1, 127)                                                    \
1668                                                                             \
1669   product(int, JavaPriority3_To_OSPriority, -1,                             \
1670           "Map Java priorities to OS priorities")                           \
1671           range(-1, 127)                                                    \
1672                                                                             \
1673   product(int, JavaPriority4_To_OSPriority, -1,                             \
1674           "Map Java priorities to OS priorities")                           \
1675           range(-1, 127)                                                    \
1676                                                                             \
1677   product(int, JavaPriority5_To_OSPriority, -1,                             \
1678           "Map Java priorities to OS priorities")                           \
1679           range(-1, 127)                                                    \
1680                                                                             \
1681   product(int, JavaPriority6_To_OSPriority, -1,                             \
1682           "Map Java priorities to OS priorities")                           \
1683           range(-1, 127)                                                    \
1684                                                                             \
1685   product(int, JavaPriority7_To_OSPriority, -1,                             \
1686           "Map Java priorities to OS priorities")                           \
1687           range(-1, 127)                                                    \
1688                                                                             \
1689   product(int, JavaPriority8_To_OSPriority, -1,                             \
1690           "Map Java priorities to OS priorities")                           \
1691           range(-1, 127)                                                    \
1692                                                                             \
1693   product(int, JavaPriority9_To_OSPriority, -1,                             \
1694           "Map Java priorities to OS priorities")                           \
1695           range(-1, 127)                                                    \
1696                                                                             \
1697   product(int, JavaPriority10_To_OSPriority,-1,                             \
1698           "Map Java priorities to OS priorities")                           \
1699           range(-1, 127)                                                    \
1700                                                                             \
1701   product(bool, UseCriticalJavaThreadPriority, false, EXPERIMENTAL,         \
1702           "Java thread priority 10 maps to critical scheduling priority")   \
1703                                                                             \
1704   product(bool, UseCriticalCompilerThreadPriority, false, EXPERIMENTAL,     \
1705           "Compiler thread(s) run at critical scheduling priority")         \
1706                                                                             \
1707   develop(intx, NewCodeParameter,      0,                                   \
1708           "Testing Only: Create a dedicated integer parameter before "      \
1709           "putback")                                                        \
1710                                                                             \
1711   /* new oopmap storage allocation */                                       \
1712   develop(intx, MinOopMapAllocation,     8,                                 \
1713           "Minimum number of OopMap entries in an OopMapSet")               \
1714                                                                             \
1715   /* recompilation */                                                       \
1716   product_pd(intx, CompileThreshold,                                        \
1717           "number of interpreted method invocations before (re-)compiling") \
1718           constraint(CompileThresholdConstraintFunc, AfterErgo)             \
1719                                                                             \
1720   product_pd(bool, TieredCompilation,                                       \
1721           "Enable tiered compilation")                                      \
1722                                                                             \
1723   /* Properties for Java libraries  */                                      \
1724                                                                             \
1725   product(uint64_t, MaxDirectMemorySize, 0,                                 \
1726           "Maximum total size of NIO direct-buffer allocations. "           \
1727           "Ignored if not explicitly set.")                                 \
1728           range(0, max_jlong)                                               \
1729                                                                             \
1730   /* Flags used for temporary code during development  */                   \
1731                                                                             \
1732   product(bool, UseNewCode, false, DIAGNOSTIC,                              \
1733           "Testing Only: Use the new version while testing")                \
1734                                                                             \
1735   product(bool, UseNewCode2, false, DIAGNOSTIC,                             \
1736           "Testing Only: Use the new version while testing")                \
1737                                                                             \
1738   product(bool, UseNewCode3, false, DIAGNOSTIC,                             \
1739           "Testing Only: Use the new version while testing")                \
1740                                                                             \
1741   notproduct(bool, UseDebuggerErgo, false,                                  \
1742           "Debugging Only: Adjust the VM to be more debugger-friendly. "    \
1743           "Turns on the other UseDebuggerErgo* flags")                      \
1744                                                                             \
1745   notproduct(bool, UseDebuggerErgo1, false,                                 \
1746           "Debugging Only: Enable workarounds for debugger induced "        \
1747           "os::processor_id() >= os::processor_count() problems")           \
1748                                                                             \
1749   notproduct(bool, UseDebuggerErgo2, false,                                 \
1750           "Debugging Only: Limit the number of spawned JVM threads")        \
1751                                                                             \
1752   notproduct(bool, EnableJVMTIStackDepthAsserts, true,                      \
1753           "Enable JVMTI asserts related to stack depth checks")             \
1754                                                                             \
1755   /* flags for performance data collection */                               \
1756                                                                             \
1757   product(bool, UsePerfData, true,                                          \
1758           "Flag to disable jvmstat instrumentation for performance testing "\
1759           "and problem isolation purposes")                                 \
1760                                                                             \
1761   product(bool, PerfDataSaveToFile, false,                                  \
1762           "Save PerfData memory to hsperfdata_<pid> file on exit")          \
1763                                                                             \
1764   product(ccstr, PerfDataSaveFile, nullptr,                                 \
1765           "Save PerfData memory to the specified absolute pathname. "       \
1766           "The string %p in the file name (if present) "                    \
1767           "will be replaced by pid")                                        \
1768                                                                             \
1769   product(int, PerfDataSamplingInterval, 50,                                \
1770           "Data sampling interval (in milliseconds)")                       \
1771           range(PeriodicTask::min_interval, max_jint)                       \
1772           constraint(PerfDataSamplingIntervalFunc, AfterErgo)               \
1773                                                                             \
1774   product(bool, PerfDisableSharedMem, false,                                \
1775           "Store performance data in standard memory")                      \
1776                                                                             \
1777   product(int, PerfDataMemorySize, 64*K,                                    \
1778           "Size of performance data memory region. Will be rounded "        \
1779           "up to a multiple of the native os page size.")                   \
1780           range(128, 32*64*K)                                               \
1781                                                                             \
1782   product(int, PerfMaxStringConstLength, 1024,                              \
1783           "Maximum PerfStringConstant string length before truncation")     \
1784           range(32, 32*K)                                                   \
1785                                                                             \
1786   product(bool, PerfAllowAtExitRegistration, false,                         \
1787           "Allow registration of atexit() methods")                         \
1788                                                                             \
1789   product(bool, PerfBypassFileSystemCheck, false,                           \
1790           "Bypass Win32 file system criteria checks (Windows Only)")        \
1791                                                                             \
1792   product(int, UnguardOnExecutionViolation, 0,                              \
1793           "Unguard page and retry on no-execute fault (Win32 only) "        \
1794           "0=off, 1=conservative, 2=aggressive")                            \
1795           range(0, 2)                                                       \
1796                                                                             \
1797   /* Serviceability Support */                                              \
1798                                                                             \
1799   product(bool, ManagementServer, false,                                    \
1800           "Create JMX Management Server")                                   \
1801                                                                             \
1802   product(bool, DisableAttachMechanism, false,                              \
1803           "Disable mechanism that allows tools to attach to this VM")       \
1804                                                                             \
1805   product(bool, StartAttachListener, false,                                 \
1806           "Always start Attach Listener at VM startup")                     \
1807                                                                             \
1808   product(bool, EnableDynamicAgentLoading, true,                            \
1809           "Allow tools to load agents with the attach mechanism")           \
1810                                                                             \
1811   product(bool, PrintConcurrentLocks, false, MANAGEABLE,                    \
1812           "Print java.util.concurrent locks in thread dump")                \
1813                                                                             \
1814   product(bool, PrintMethodHandleStubs, false, DIAGNOSTIC,                  \
1815           "Print generated stub code for method handles")                   \
1816                                                                             \
1817   product(bool, VerifyMethodHandles, trueInDebug, DIAGNOSTIC,               \
1818           "perform extra checks when constructing method handles")          \
1819                                                                             \
1820   product(bool, ShowHiddenFrames, false, DIAGNOSTIC,                        \
1821           "show method handle implementation frames (usually hidden)")      \
1822                                                                             \
1823   product(bool, ShowCarrierFrames, false, DIAGNOSTIC,                       \
1824           "show virtual threads' carrier frames in exceptions")             \
1825                                                                             \
1826   product(bool, TrustFinalNonStaticFields, false, EXPERIMENTAL,             \
1827           "trust final non-static declarations for constant folding")       \
1828                                                                             \
1829   product(bool, FoldStableValues, true, DIAGNOSTIC,                         \
1830           "Optimize loads from stable fields (marked w/ @Stable)")          \
1831                                                                             \
1832   product(int, UseBootstrapCallInfo, 1, DIAGNOSTIC,                         \
1833           "0: when resolving InDy or ConDy, force all BSM arguments to be " \
1834           "resolved before the bootstrap method is called; 1: when a BSM "  \
1835           "that may accept a BootstrapCallInfo is detected, use that API "  \
1836           "to pass BSM arguments, which allows the BSM to delay their "     \
1837           "resolution; 2+: stress test the BCI API by calling more BSMs "   \
1838           "via that API, instead of with the eagerly-resolved array.")      \
1839                                                                             \
1840   product(bool, PauseAtStartup,      false, DIAGNOSTIC,                     \
1841           "Causes the VM to pause at startup time and wait for the pause "  \
1842           "file to be removed (default: ./vm.paused.<pid>)")                \
1843                                                                             \
1844   product(ccstr, PauseAtStartupFile, nullptr, DIAGNOSTIC,                      \
1845           "The file to create and for whose removal to await when pausing " \
1846           "at startup. (default: ./vm.paused.<pid>)")                       \
1847                                                                             \
1848   product(bool, PauseAtExit, false, DIAGNOSTIC,                             \
1849           "Pause and wait for keypress on exit if a debugger is attached")  \
1850                                                                             \
1851   product(bool, DTraceMethodProbes, false,                                  \
1852           "Enable dtrace tool probes for method-entry and method-exit")     \
1853                                                                             \
1854   product(bool, DTraceAllocProbes, false,                                   \
1855           "Enable dtrace tool probes for object allocation")                \
1856                                                                             \
1857   product(bool, DTraceMonitorProbes, false,                                 \
1858           "Enable dtrace tool probes for monitor events")                   \
1859                                                                             \
1860   product(bool, RelaxAccessControlCheck, false,                             \
1861           "Relax the access control checks in the verifier")                \
1862                                                                             \
1863   product(uintx, StringTableSize, defaultStringTableSize,                   \
1864           "Number of buckets in the interned String table "                 \
1865           "(will be rounded to nearest higher power of 2)")                 \
1866           range(minimumStringTableSize, 16777216ul /* 2^24 */)              \
1867                                                                             \
1868   product(uintx, SymbolTableSize, defaultSymbolTableSize, EXPERIMENTAL,     \
1869           "Number of buckets in the JVM internal Symbol table")             \
1870           range(minimumSymbolTableSize, 16777216ul /* 2^24 */)              \
1871                                                                             \
1872   product(bool, UseStringDeduplication, false,                              \
1873           "Use string deduplication")                                       \
1874                                                                             \
1875   product(uint, StringDeduplicationAgeThreshold, 3,                         \
1876           "A string must reach this age (or be promoted to an old region) " \
1877           "to be considered for deduplication")                             \
1878           range(1, markWord::max_age)                                       \
1879                                                                             \
1880   product(size_t, StringDeduplicationInitialTableSize, 500, EXPERIMENTAL,   \
1881           "Approximate initial number of buckets in the table")             \
1882           range(1, 1 * G)                                                   \
1883                                                                             \
1884   product(double, StringDeduplicationGrowTableLoad, 14.0, EXPERIMENTAL,     \
1885           "Entries per bucket above which the table should be expanded")    \
1886           range(0.1, 1000.0)                                                \
1887                                                                             \
1888   product(double, StringDeduplicationShrinkTableLoad, 1.0, EXPERIMENTAL,    \
1889           "Entries per bucket below which the table should be shrunk")      \
1890           range(0.01, 100.0)                                                \
1891                                                                             \
1892   product(double, StringDeduplicationTargetTableLoad, 7.0, EXPERIMENTAL,    \
1893           "Desired entries per bucket when resizing the table")             \
1894           range(0.01, 1000.0)                                               \
1895                                                                             \
1896   product(size_t, StringDeduplicationCleanupDeadMinimum, 100, EXPERIMENTAL, \
1897           "Minimum number of dead table entries for cleaning the table")    \
1898                                                                             \
1899   product(int, StringDeduplicationCleanupDeadPercent, 5, EXPERIMENTAL,      \
1900           "Minimum percentage of dead table entries for cleaning the table") \
1901           range(1, 100)                                                     \
1902                                                                             \
1903   product(bool, StringDeduplicationResizeALot, false, DIAGNOSTIC,           \
1904           "Force more frequent table resizing")                             \
1905                                                                             \
1906   product(uint64_t, StringDeduplicationHashSeed, 0, DIAGNOSTIC,             \
1907           "Seed for the table hashing function; 0 requests computed seed")  \
1908                                                                             \
1909   product(bool, WhiteBoxAPI, false, DIAGNOSTIC,                             \
1910           "Enable internal testing APIs")                                   \
1911                                                                             \
1912   product(bool, AlwaysAtomicAccesses, false, EXPERIMENTAL,                  \
1913           "Accesses to all variables should always be atomic")              \
1914                                                                             \
1915   product(bool, UseUnalignedAccesses, false, DIAGNOSTIC,                    \
1916           "Use unaligned memory accesses in Unsafe")                        \
1917                                                                             \
1918   product_pd(bool, PreserveFramePointer,                                    \
1919              "Use the FP register for holding the frame pointer "           \
1920              "and not as a general purpose register.")                      \
1921                                                                             \
1922   product(size_t, AsyncLogBufferSize, 2*M,                                  \
1923           "Memory budget (in bytes) for the buffer of Asynchronous "        \
1924           "Logging (-Xlog:async).")                                         \
1925           range(100*K, 50*M)                                                \
1926                                                                             \
1927   product(bool, CheckIntrinsics, true, DIAGNOSTIC,                          \
1928              "When a class C is loaded, check that "                        \
1929              "(1) all intrinsics defined by the VM for class C are present "\
1930              "in the loaded class file and are marked with the "            \
1931              "@IntrinsicCandidate annotation, that "                        \
1932              "(2) there is an intrinsic registered for all loaded methods " \
1933              "that are annotated with the @IntrinsicCandidate annotation, " \
1934              "and that "                                                    \
1935              "(3) no orphan methods exist for class C (i.e., methods for "  \
1936              "which the VM declares an intrinsic but that are not declared "\
1937              "in the loaded class C. "                                      \
1938              "Check (3) is available only in debug builds.")                \
1939                                                                             \
1940   product_pd(intx, InitArrayShortSize, DIAGNOSTIC,                          \
1941           "Threshold small size (in bytes) for clearing arrays. "           \
1942           "Anything this size or smaller may get converted to discrete "    \
1943           "scalar stores.")                                                 \
1944           range(0, max_intx)                                                \
1945           constraint(InitArrayShortSizeConstraintFunc, AfterErgo)           \
1946                                                                             \
1947   product(ccstr, AllocateHeapAt, nullptr,                                   \
1948           "Path to the directory where a temporary file will be created "   \
1949           "to use as the backing store for Java Heap.")                     \
1950                                                                             \
1951   product_pd(bool, VMContinuations, EXPERIMENTAL,                           \
1952           "Enable VM continuations support")                                \
1953                                                                             \
1954   develop(bool, LoomDeoptAfterThaw, false,                                  \
1955           "Deopt stack after thaw")                                         \
1956                                                                             \
1957   develop(bool, LoomVerifyAfterThaw, false,                                 \
1958           "Verify stack after thaw")                                        \
1959                                                                             \
1960   develop(bool, VerifyContinuations, false,                                 \
1961           "Verify continuation consistency")                                \
1962                                                                             \
1963   develop(bool, UseContinuationFastPath, true,                              \
1964           "Use fast-path frame walking in continuations")                   \
1965                                                                             \
1966   develop(int, VerifyMetaspaceInterval, DEBUG_ONLY(500) NOT_DEBUG(0),       \
1967                "Run periodic metaspace verifications (0 - none, "           \
1968                "1 - always, >1 every nth interval)")                        \
1969                                                                             \
1970   product(bool, ShowRegistersOnAssert, true, DIAGNOSTIC,                    \
1971           "On internal errors, include registers in error report.")         \
1972                                                                             \
1973   product(bool, UseSwitchProfiling, true, DIAGNOSTIC,                       \
1974           "leverage profiling for table/lookup switch")                     \
1975                                                                             \
1976   develop(bool, TraceMemoryWriteback, false,                                \
1977           "Trace memory writeback operations")                              \
1978                                                                             \
1979   JFR_ONLY(product(bool, FlightRecorder, false,                             \
1980           "(Deprecated) Enable Flight Recorder"))                           \
1981                                                                             \
1982   JFR_ONLY(product(ccstr, FlightRecorderOptions, nullptr,                   \
1983           "Flight Recorder options"))                                       \
1984                                                                             \
1985   JFR_ONLY(product(ccstr, StartFlightRecording, nullptr,                    \
1986           "Start flight recording with options"))                           \
1987                                                                             \
1988   product(bool, UseFastUnorderedTimeStamps, false, EXPERIMENTAL,            \
1989           "Use platform unstable time where supported for timestamps only") \
1990                                                                             \
1991   product(bool, UseEmptySlotsInSupers, true,                                \
1992                 "Allow allocating fields in empty slots of super-classes")  \
1993                                                                             \
1994   product(bool, DeoptimizeNMethodBarriersALot, false, DIAGNOSTIC,           \
1995                 "Make nmethod barriers deoptimise a lot.")                  \
1996                                                                             \
1997   develop(bool, VerifyCrossModifyFence,                                     \
1998           false AARCH64_ONLY(DEBUG_ONLY(||true)),                           \
1999              "Mark all threads after a safepoint, and clear on a modify "   \
2000              "fence. Add cleanliness checks.")                              \
2001                                                                             \
2002   product(int, LockingMode, LM_LEGACY,                                      \
2003           "Select locking mode: "                                           \
2004           "0: monitors only (LM_MONITOR), "                                 \
2005           "1: monitors & legacy stack-locking (LM_LEGACY, default), "       \
2006           "2: monitors & new lightweight locking (LM_LIGHTWEIGHT)")         \
2007           range(0, 2)                                                       \
2008                                                                             \
2009   product(uint, TrimNativeHeapInterval, 0, EXPERIMENTAL,                    \
2010           "Interval, in ms, at which the JVM will trim the native heap if " \
2011           "the platform supports that. Lower values will reclaim memory "   \
2012           "more eagerly at the cost of higher overhead. A value of 0 "      \
2013           "(default) disables native heap trimming.")                       \
2014           range(0, UINT_MAX)                                                \
2015                                                                             \
2016   product(bool, ProfileVMLocks, false, DIAGNOSTIC,                          \
2017           "Profile VM locks usage on main thread")                          \
2018                                                                             \
2019   product(bool, ProfileVMCalls, false, DIAGNOSTIC,                          \
2020           "Profile VM calls on main thread")                                \
2021                                                                             \
2022   product(bool, ProfileVMOps, true, DIAGNOSTIC,                             \
2023           "Profile VM operations on main thread")                           \
2024                                                                             \
2025   product(bool, ProfileRuntimeCalls, false, DIAGNOSTIC,                     \
2026           "Profile calls into VM runtime on main thread")                   \
2027                                                                             \
2028   develop(bool, SimulateFullAddressSpace, false,                            \
2029           "Simulates a very populated, fragmented address space; no "       \
2030           "targeted reservations will succeed.")                            \
2031                                                                             \
2032   product(bool, ProfileExceptionHandlers, true,                             \
2033           "Profile exception handlers")                                     \
2034                                                                             \
2035   product(bool, AlwaysRecordEvolDependencies, true, EXPERIMENTAL,           \
2036                 "Unconditionally record nmethod dependencies on class "     \
2037                 "rewriting/transformation independently of the JVMTI "      \
2038                 "can_{retransform/redefine}_classes capabilities.")         \
2039 
2040 // end of RUNTIME_FLAGS
2041 
2042 DECLARE_FLAGS(LP64_RUNTIME_FLAGS)
2043 DECLARE_ARCH_FLAGS(ARCH_FLAGS)
2044 DECLARE_FLAGS(RUNTIME_FLAGS)
2045 DECLARE_FLAGS(RUNTIME_OS_FLAGS)
2046 
2047 #endif // SHARE_RUNTIME_GLOBALS_HPP