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