1 /*
   2  * Copyright (c) 1997, 2025, 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 // develop_pd/product_pd flags are the same as develop/product, except that their default values
  40 // are specified in platform-dependent header files.
  41 
  42 // Flags must be declared with the following number of parameters:
  43 // non-pd flags:
  44 //    (type, name, default_value, doc), or
  45 //    (type, name, default_value, extra_attrs, doc)
  46 // pd flags:
  47 //    (type, name, doc), or
  48 //    (type, name, extra_attrs, doc)
  49 
  50 // A flag must be declared with one of the following types:
  51 // bool, int, uint, intx, uintx, size_t, ccstr, ccstrlist, double, or uint64_t.
  52 // The type "ccstr" and "ccstrlist" are an alias for "const char*" and is used
  53 // only in this file, because the macrology requires single-token type names.
  54 
  55 // The optional extra_attrs parameter may have one of the following values:
  56 // DIAGNOSTIC, EXPERIMENTAL, or MANAGEABLE. Currently extra_attrs can be used
  57 // only with product/product_pd flags.
  58 //
  59 // DIAGNOSTIC options are not meant for VM tuning or for product modes.
  60 //    They are to be used for VM quality assurance or field diagnosis
  61 //    of VM bugs.  They are hidden so that users will not be encouraged to
  62 //    try them as if they were VM ordinary execution options.  However, they
  63 //    are available in the product version of the VM.  Under instruction
  64 //    from support engineers, VM customers can turn them on to collect
  65 //    diagnostic information about VM problems.  To use a VM diagnostic
  66 //    option, you must first specify +UnlockDiagnosticVMOptions.
  67 //    (This master switch also affects the behavior of -Xprintflags.)
  68 //
  69 // EXPERIMENTAL flags are in support of features that may not be
  70 //    an officially supported part of a product, but may be available
  71 //    for experimenting with. They could, for example, be performance
  72 //    features that may not have undergone full or rigorous QA, but which may
  73 //    help performance in some cases and released for experimentation
  74 //    by the community of users and developers. This flag also allows one to
  75 //    be able to build a fully supported product that nonetheless also
  76 //    ships with some unsupported, lightly tested, experimental features.
  77 //    Refer to the documentation of any products using this code for details
  78 //    on support and fitness for production.
  79 //    Like the UnlockDiagnosticVMOptions flag above, there is a corresponding
  80 //    UnlockExperimentalVMOptions flag, which allows the control and
  81 //    modification of the experimental flags.
  82 //
  83 // Nota bene: neither diagnostic nor experimental options should be used casually,
  84 //    Refer to the documentation of any products using this code for details.
  85 //
  86 // MANAGEABLE flags are writeable external product flags.
  87 //    They are dynamically writeable through the JDK management interface
  88 //    (com.sun.management.HotSpotDiagnosticMXBean API) and also through JConsole.
  89 //    These flags are external exported interface (see CSR).  The list of
  90 //    manageable flags can be queried programmatically through the management
  91 //    interface.
  92 //
  93 //    A flag can be made as "manageable" only if
  94 //    - the flag is defined in a CSR request as an external exported interface.
  95 //    - the VM implementation supports dynamic setting of the flag.
  96 //      This implies that the VM must *always* query the flag variable
  97 //      and not reuse state related to the flag state at any given time.
  98 //    - you want the flag to be queried programmatically by the customers.
  99 //
 100 
 101 //
 102 // range is a macro that will expand to min and max arguments for range
 103 //    checking code if provided - see jvmFlagLimit.hpp
 104 //
 105 // constraint is a macro that will expand to custom function call
 106 //    for constraint checking if provided - see jvmFlagLimit.hpp
 107 
 108 // Default and minimum StringTable and SymbolTable size values
 109 // Must be powers of 2
 110 const size_t defaultStringTableSize = NOT_LP64(1024) LP64_ONLY(65536);
 111 const size_t minimumStringTableSize = 128;
 112 const size_t defaultSymbolTableSize = 32768; // 2^15
 113 const size_t minimumSymbolTableSize = 1024;
 114 
 115 #ifdef _LP64
 116 #define LP64_RUNTIME_FLAGS(develop,                                         \
 117                            develop_pd,                                      \
 118                            product,                                         \
 119                            product_pd,                                      \
 120                            range,                                           \
 121                            constraint)                                      \
 122                                                                             \
 123   product(bool, UseCompressedOops, false,                                   \
 124           "Use 32-bit object references in 64-bit VM. "                     \
 125           "lp64_product means flag is always constant in 32 bit VM")        \
 126                                                                             \
 127   product(bool, UseCompressedClassPointers, true,                           \
 128           "(Deprecated) Use 32-bit class pointers in 64-bit VM. "           \
 129           "lp64_product means flag is always constant in 32 bit VM")        \
 130                                                                             \
 131   product(bool, UseCompactObjectHeaders, false, EXPERIMENTAL,               \
 132           "Use compact 64-bit object headers in 64-bit VM")                 \
 133                                                                             \
 134   product(int, ObjectAlignmentInBytes, 8,                                   \
 135           "Default object alignment in bytes, 8 is minimum")                \
 136           range(8, 256)                                                     \
 137           constraint(ObjectAlignmentInBytesConstraintFunc, AtParse)
 138 
 139 #else
 140 // !_LP64
 141 
 142 #define LP64_RUNTIME_FLAGS(develop,                                         \
 143                            develop_pd,                                      \
 144                            product,                                         \
 145                            product_pd,                                      \
 146                            range,                                           \
 147                            constraint)
 148 const bool UseCompressedOops = false;
 149 const bool UseCompressedClassPointers = false;
 150 const bool UseCompactObjectHeaders = false;
 151 const int ObjectAlignmentInBytes = 8;
 152 
 153 #endif // _LP64
 154 
 155 #define RUNTIME_FLAGS(develop,                                              \
 156                       develop_pd,                                           \
 157                       product,                                              \
 158                       product_pd,                                           \
 159                       range,                                                \
 160                       constraint)                                           \
 161                                                                             \
 162   develop(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(bool, UseAES, false,                                              \
 224           "Control whether AES instructions are used when available")       \
 225                                                                             \
 226   product(bool, UseFMA, false,                                              \
 227           "Control whether FMA instructions are used when available")       \
 228                                                                             \
 229   product(bool, UseSHA, false,                                              \
 230           "Control whether SHA instructions are used when available")       \
 231                                                                             \
 232   product(bool, UseGHASHIntrinsics, false, DIAGNOSTIC,                      \
 233           "Use intrinsics for GHASH versions of crypto")                    \
 234                                                                             \
 235   product(bool, UseBASE64Intrinsics, false,                                 \
 236           "Use intrinsics for java.util.Base64")                            \
 237                                                                             \
 238   product(bool, UsePoly1305Intrinsics, false, DIAGNOSTIC,                   \
 239           "Use intrinsics for sun.security.util.math.intpoly")              \
 240   product(bool, UseIntPolyIntrinsics, false, DIAGNOSTIC,                   \
 241           "Use intrinsics for sun.security.util.math.intpoly.MontgomeryIntegerPolynomialP256") \
 242                                                                             \
 243   product(size_t, LargePageSizeInBytes, 0,                                  \
 244           "Maximum large page size used (0 will use the default large "     \
 245           "page size for the environment as the maximum)")                  \
 246           range(0, max_uintx)                                               \
 247                                                                             \
 248   product(size_t, LargePageHeapSizeThreshold, 128*M,                        \
 249           "Use large pages if maximum heap is at least this big")           \
 250           range(0, max_uintx)                                               \
 251                                                                             \
 252   product(bool, ForceTimeHighResolution, false,                             \
 253           "Using high time resolution (for Win32 only)")                    \
 254                                                                             \
 255   develop(bool, TracePcPatching, false,                                     \
 256           "Trace usage of frame::patch_pc")                                 \
 257                                                                             \
 258   develop(bool, TraceRelocator, false,                                      \
 259           "Trace the bytecode relocator")                                   \
 260                                                                             \
 261                                                                             \
 262   product(bool, SafepointALot, false, DIAGNOSTIC,                           \
 263           "Generate a lot of safepoints. This works with "                  \
 264           "GuaranteedSafepointInterval")                                    \
 265                                                                             \
 266   product(bool, HandshakeALot, false, DIAGNOSTIC,                           \
 267           "Generate a lot of handshakes. This works with "                  \
 268           "GuaranteedSafepointInterval")                                    \
 269                                                                             \
 270   product_pd(bool, BackgroundCompilation,                                   \
 271           "A thread requesting compilation is not blocked during "          \
 272           "compilation")                                                    \
 273                                                                             \
 274   product(bool, MethodFlushing, true,                                       \
 275           "Reclamation of compiled methods")                                \
 276                                                                             \
 277   develop(bool, VerifyStack, false,                                         \
 278           "Verify stack of each thread when it is entering a runtime call") \
 279                                                                             \
 280   product(bool, ForceUnreachable, false, DIAGNOSTIC,                        \
 281           "Make all non code cache addresses to be unreachable by "         \
 282           "forcing use of 64bit literal fixups")                            \
 283                                                                             \
 284   develop(bool, TraceDerivedPointers, false,                                \
 285           "Trace traversal of derived pointers on stack")                   \
 286                                                                             \
 287   develop(bool, TraceCodeBlobStacks, false,                                 \
 288           "Trace stack-walk of codeblobs")                                  \
 289                                                                             \
 290   develop(bool, PrintRewrites, false,                                       \
 291           "Print methods that are being rewritten")                         \
 292                                                                             \
 293   product(bool, UseInlineCaches, true,                                      \
 294           "Use Inline Caches for virtual calls ")                           \
 295                                                                             \
 296   product(bool, InlineArrayCopy, true, DIAGNOSTIC,                          \
 297           "Inline arraycopy native that is known to be part of "            \
 298           "base library DLL")                                               \
 299                                                                             \
 300   product(bool, InlineObjectHash, true, DIAGNOSTIC,                         \
 301           "Inline Object::hashCode() native that is known to be part "      \
 302           "of base library DLL")                                            \
 303                                                                             \
 304   product(bool, InlineNatives, true, DIAGNOSTIC,                            \
 305           "Inline natives that are known to be part of base library DLL")   \
 306                                                                             \
 307   product(bool, InlineMathNatives, true, DIAGNOSTIC,                        \
 308           "Inline SinD, CosD, etc.")                                        \
 309                                                                             \
 310   product(bool, InlineClassNatives, true, DIAGNOSTIC,                       \
 311           "Inline Class.isInstance, etc")                                   \
 312                                                                             \
 313   product(bool, InlineThreadNatives, true, DIAGNOSTIC,                      \
 314           "Inline Thread.currentThread, etc")                               \
 315                                                                             \
 316   product(bool, InlineUnsafeOps, true, DIAGNOSTIC,                          \
 317           "Inline memory ops (native methods) from Unsafe")                 \
 318                                                                             \
 319   product(bool, UseAESIntrinsics, false, DIAGNOSTIC,                        \
 320           "Use intrinsics for AES versions of crypto")                      \
 321                                                                             \
 322   product(bool, UseAESCTRIntrinsics, false, DIAGNOSTIC,                     \
 323           "Use intrinsics for the paralleled version of AES/CTR crypto")    \
 324                                                                             \
 325   product(bool, UseChaCha20Intrinsics, false, DIAGNOSTIC,                   \
 326           "Use intrinsics for the vectorized version of ChaCha20")          \
 327                                                                             \
 328   product(bool, UseKyberIntrinsics, false, DIAGNOSTIC,                      \
 329           "Use intrinsics for the vectorized version of Kyber")             \
 330   product(bool, UseDilithiumIntrinsics, false, DIAGNOSTIC,                  \
 331           "Use intrinsics for the vectorized version of Dilithium")         \
 332                                                                             \
 333   product(bool, UseMD5Intrinsics, false, DIAGNOSTIC,                        \
 334           "Use intrinsics for MD5 crypto hash function")                    \
 335                                                                             \
 336   product(bool, UseSHA1Intrinsics, false, DIAGNOSTIC,                       \
 337           "Use intrinsics for SHA-1 crypto hash function. "                 \
 338           "Requires that UseSHA is enabled.")                               \
 339                                                                             \
 340   product(bool, UseSHA256Intrinsics, false, DIAGNOSTIC,                     \
 341           "Use intrinsics for SHA-224 and SHA-256 crypto hash functions. "  \
 342           "Requires that UseSHA is enabled.")                               \
 343                                                                             \
 344   product(bool, UseSHA512Intrinsics, false, DIAGNOSTIC,                     \
 345           "Use intrinsics for SHA-384 and SHA-512 crypto hash functions. "  \
 346           "Requires that UseSHA is enabled.")                               \
 347                                                                             \
 348   product(bool, UseSHA3Intrinsics, false, DIAGNOSTIC,                       \
 349           "Use intrinsics for SHA3 crypto hash function. "                  \
 350           "Requires that UseSHA is enabled.")                               \
 351                                                                             \
 352   product(bool, UseCRC32Intrinsics, false, DIAGNOSTIC,                      \
 353           "use intrinsics for java.util.zip.CRC32")                         \
 354                                                                             \
 355   product(bool, UseCRC32CIntrinsics, false, DIAGNOSTIC,                     \
 356           "use intrinsics for java.util.zip.CRC32C")                        \
 357                                                                             \
 358   product(bool, UseAdler32Intrinsics, false, DIAGNOSTIC,                    \
 359           "use intrinsics for java.util.zip.Adler32")                       \
 360                                                                             \
 361   product(bool, UseVectorizedMismatchIntrinsic, false, DIAGNOSTIC,          \
 362           "Enables intrinsification of ArraysSupport.vectorizedMismatch()") \
 363                                                                             \
 364   product(bool, UseVectorizedHashCodeIntrinsic, false, DIAGNOSTIC,          \
 365           "Enables intrinsification of ArraysSupport.vectorizedHashCode()") \
 366                                                                             \
 367   product(bool, UseCopySignIntrinsic, false, DIAGNOSTIC,                    \
 368           "Enables intrinsification of Math.copySign")                      \
 369                                                                             \
 370   product(bool, UseSignumIntrinsic, false, DIAGNOSTIC,                      \
 371           "Enables intrinsification of Math.signum")                        \
 372                                                                             \
 373   product_pd(bool, DelayCompilerStubsGeneration, DIAGNOSTIC,                \
 374           "Use Compiler thread for compiler's stubs generation")            \
 375                                                                             \
 376   product(ccstrlist, DisableIntrinsic, "", DIAGNOSTIC,                      \
 377          "do not expand intrinsics whose (internal) names appear here")     \
 378          constraint(DisableIntrinsicConstraintFunc,AfterErgo)               \
 379                                                                             \
 380   product(ccstrlist, ControlIntrinsic, "", DIAGNOSTIC,                      \
 381          "Control intrinsics using a list of +/- (internal) names, "        \
 382          "separated by commas")                                             \
 383          constraint(ControlIntrinsicConstraintFunc,AfterErgo)               \
 384                                                                             \
 385   develop(bool, TraceCallFixup, false,                                      \
 386           "Trace all call fixups")                                          \
 387                                                                             \
 388   develop(bool, DeoptimizeALot, false,                                      \
 389           "Deoptimize at every exit from the runtime system")               \
 390                                                                             \
 391   develop(ccstrlist, DeoptimizeOnlyAt, "",                                  \
 392           "A comma separated list of bcis to deoptimize at")                \
 393                                                                             \
 394   develop(bool, DeoptimizeRandom, false,                                    \
 395           "Deoptimize random frames on random exit from the runtime system")\
 396                                                                             \
 397   develop(bool, ZombieALot, false,                                          \
 398           "Create non-entrant nmethods at exit from the runtime system")    \
 399                                                                             \
 400   develop(bool, WalkStackALot, false,                                       \
 401           "Trace stack (no print) at every exit from the runtime system")   \
 402                                                                             \
 403   develop(bool, DeoptimizeObjectsALot, false,                               \
 404           "For testing purposes concurrent threads revert optimizations "   \
 405           "based on escape analysis at intervals given with "               \
 406           "DeoptimizeObjectsALotInterval=n. The thread count is given "     \
 407           "with DeoptimizeObjectsALotThreadCountSingle and "                \
 408           "DeoptimizeObjectsALotThreadCountAll.")                           \
 409                                                                             \
 410   develop(uint64_t, DeoptimizeObjectsALotInterval, 5,                       \
 411           "Interval for DeoptimizeObjectsALot.")                            \
 412           range(0, max_jlong)                                               \
 413                                                                             \
 414   develop(int, DeoptimizeObjectsALotThreadCountSingle, 1,                   \
 415           "The number of threads that revert optimizations based on "       \
 416           "escape analysis for a single thread if DeoptimizeObjectsALot "   \
 417           "is enabled. The target thread is selected round robin." )        \
 418           range(0, max_jint)                                                \
 419                                                                             \
 420   develop(int, DeoptimizeObjectsALotThreadCountAll, 1,                      \
 421           "The number of threads that revert optimizations based on "       \
 422           "escape analysis for all threads if DeoptimizeObjectsALot "       \
 423           "is enabled." )                                                   \
 424           range(0, max_jint)                                                \
 425                                                                             \
 426   develop(bool, VerifyLastFrame, false,                                     \
 427           "Verify oops on last frame on entry to VM")                       \
 428                                                                             \
 429   product(bool, SafepointTimeout, false,                                    \
 430           "Time out and warn or fail after SafepointTimeoutDelay "          \
 431           "milliseconds if failed to reach safepoint")                      \
 432                                                                             \
 433   product(bool, AbortVMOnSafepointTimeout, false, DIAGNOSTIC,               \
 434           "Abort upon failure to reach safepoint (see SafepointTimeout)")   \
 435                                                                             \
 436   product(uint64_t, AbortVMOnSafepointTimeoutDelay, 0, DIAGNOSTIC,          \
 437           "Delay in milliseconds for option AbortVMOnSafepointTimeout")     \
 438           range(0, max_jlong)                                               \
 439                                                                             \
 440   product(bool, AbortVMOnVMOperationTimeout, false, DIAGNOSTIC,             \
 441           "Abort upon failure to complete VM operation promptly")           \
 442                                                                             \
 443   product(intx, AbortVMOnVMOperationTimeoutDelay, 1000, DIAGNOSTIC,         \
 444           "Delay in milliseconds for option AbortVMOnVMOperationTimeout")   \
 445           range(0, max_intx)                                                \
 446                                                                             \
 447   product(bool, MaxFDLimit, true,                                           \
 448           "Bump the number of file descriptors to maximum (Unix only)")     \
 449                                                                             \
 450   product(bool, LogEvents, true, DIAGNOSTIC,                                \
 451           "Enable the various ring buffer event logs")                      \
 452                                                                             \
 453   product(int, LogEventsBufferEntries, 20, DIAGNOSTIC,                      \
 454           "Number of ring buffer event logs")                               \
 455           range(1, NOT_LP64(1*K) LP64_ONLY(1*M))                            \
 456                                                                             \
 457   product(bool, BytecodeVerificationRemote, true, DIAGNOSTIC,               \
 458           "Enable the Java bytecode verifier for remote classes")           \
 459                                                                             \
 460   product(bool, BytecodeVerificationLocal, false, DIAGNOSTIC,               \
 461           "Enable the Java bytecode verifier for local classes")            \
 462                                                                             \
 463   develop(bool, VerifyStackAtCalls, false,                                  \
 464           "Verify that the stack pointer is unchanged after calls")         \
 465                                                                             \
 466   develop(bool, TraceJavaAssertions, false,                                 \
 467           "Trace java language assertions")                                 \
 468                                                                             \
 469   develop(bool, VerifyCodeCache, false,                                     \
 470           "Verify code cache on memory allocation/deallocation")            \
 471                                                                             \
 472   develop(bool, ZapResourceArea, trueInDebug,                               \
 473           "Zap freed resource/arena space")                                 \
 474                                                                             \
 475   develop(bool, ZapVMHandleArea, trueInDebug,                               \
 476           "Zap freed VM handle space")                                      \
 477                                                                             \
 478   develop(bool, ZapStackSegments, trueInDebug,                              \
 479           "Zap allocated/freed stack segments")                             \
 480                                                                             \
 481   develop(bool, ZapUnusedHeapArea, trueInDebug,                             \
 482           "Zap unused heap space")                                          \
 483                                                                             \
 484   develop(bool, ZapFillerObjects, trueInDebug,                              \
 485           "Zap filler objects")                                             \
 486                                                                             \
 487   develop(bool, ZapTLAB, trueInDebug,                                       \
 488           "Zap allocated TLABs")                                            \
 489   develop(bool, TestingAsyncLoggingDeathTest, false,                        \
 490           "Recursive logging death test")                                   \
 491   develop(bool, TestingAsyncLoggingDeathTestNoCrash, false,                 \
 492           "Recursive logging death test (no crash)")                        \
 493                                                                             \
 494   product(bool, ExecutingUnitTests, false,                                  \
 495           "Whether the JVM is running unit tests or not")                   \
 496                                                                             \
 497   develop(uint, ErrorHandlerTest, 0,                                        \
 498           "If > 0, provokes an error after VM initialization; the value "   \
 499           "determines which error to provoke. See controlled_crash() "      \
 500           "in vmError.cpp.")                                                \
 501           range(0, 17)                                                      \
 502                                                                             \
 503   develop(uint, TestCrashInErrorHandler, 0,                                 \
 504           "If > 0, provokes an error inside VM error handler (a secondary " \
 505           "crash). see controlled_crash() in vmError.cpp")                  \
 506           range(0, 17)                                                      \
 507                                                                             \
 508   develop(bool, TestSafeFetchInErrorHandler, false   ,                      \
 509           "If true, tests SafeFetch inside error handler.")                 \
 510                                                                             \
 511   develop(bool, TestUnresponsiveErrorHandler, false,                        \
 512           "If true, simulates an unresponsive error handler.")              \
 513                                                                             \
 514   develop(bool, Verbose, false,                                             \
 515           "Print additional debugging information from other modes")        \
 516                                                                             \
 517   develop(bool, PrintMiscellaneous, false,                                  \
 518           "Print uncategorized debugging information (requires +Verbose)")  \
 519                                                                             \
 520   develop(bool, WizardMode, false,                                          \
 521           "Print much more debugging information")                          \
 522                                                                             \
 523   product(bool, ShowMessageBoxOnError, false,                               \
 524           "Keep process alive on VM fatal error")                           \
 525                                                                             \
 526   product(bool, CreateCoredumpOnCrash, true,                                \
 527           "Create core/mini dump on VM fatal error")                        \
 528                                                                             \
 529   product(uint64_t, ErrorLogTimeout, 2 * 60,                                \
 530           "Timeout, in seconds, to limit the time spent on writing an "     \
 531           "error log in case of a crash.")                                  \
 532           range(0, (uint64_t)max_jlong/1000)                                \
 533                                                                             \
 534   product(bool, ErrorLogSecondaryErrorDetails, false, DIAGNOSTIC,           \
 535           "If enabled, show details on secondary crashes in the error log") \
 536                                                                             \
 537   develop(intx, TraceDwarfLevel, 0,                                         \
 538           "Debug levels for the dwarf parser")                              \
 539           range(0, 4)                                                       \
 540                                                                             \
 541   product(bool, SuppressFatalErrorMessage, false,                           \
 542           "Report NO fatal error message (avoid deadlock)")                 \
 543                                                                             \
 544   product(ccstrlist, OnError, "",                                           \
 545           "Run user-defined commands on fatal error; see VMError.cpp "      \
 546           "for examples")                                                   \
 547                                                                             \
 548   product(ccstrlist, OnOutOfMemoryError, "",                                \
 549           "Run user-defined commands on first java.lang.OutOfMemoryError "  \
 550           "thrown from JVM")                                                \
 551                                                                             \
 552   product(bool, HeapDumpBeforeFullGC, false, MANAGEABLE,                    \
 553           "Dump heap to file before any major stop-the-world GC "           \
 554           "(also see FullGCHeapDumpLimit, HeapDumpPath, HeapDumpGzipLevel)")\
 555                                                                             \
 556   product(bool, HeapDumpAfterFullGC, false, MANAGEABLE,                     \
 557           "Dump heap to file after any major stop-the-world GC "            \
 558           "(also see FullGCHeapDumpLimit, HeapDumpPath, HeapDumpGzipLevel)")\
 559                                                                             \
 560   product(uint, FullGCHeapDumpLimit, 0, MANAGEABLE,                         \
 561           "Limit the number of heap dumps triggered by "                    \
 562           "HeapDumpBeforeFullGC or HeapDumpAfterFullGC "                    \
 563           "(0 means no limit)")                                             \
 564                                                                             \
 565   product(bool, HeapDumpOnOutOfMemoryError, false, MANAGEABLE,              \
 566           "Dump heap to file when java.lang.OutOfMemoryError is thrown "    \
 567           "from JVM "                                                       \
 568           "(also see HeapDumpPath, HeapDumpGzipLevel)")                     \
 569                                                                             \
 570   product(ccstr, HeapDumpPath, nullptr, MANAGEABLE,                         \
 571           "When HeapDumpOnOutOfMemoryError, HeapDumpBeforeFullGC "          \
 572           "or HeapDumpAfterFullGC is on, the path (filename or "            \
 573           "directory) of the dump file (defaults to java_pid<pid>.hprof "   \
 574           "in the working directory)")                                      \
 575                                                                             \
 576   product(int, HeapDumpGzipLevel, 0, MANAGEABLE,                            \
 577           "When HeapDumpOnOutOfMemoryError, HeapDumpBeforeFullGC "          \
 578           "or HeapDumpAfterFullGC is on, the gzip compression "             \
 579           "level of the dump file. 0 (the default) disables gzip "          \
 580           "compression. Otherwise the level must be between 1 and 9.")      \
 581           range(0, 9)                                                       \
 582                                                                             \
 583   product(ccstr, NativeMemoryTracking, DEBUG_ONLY("summary") NOT_DEBUG("off"), \
 584           "Native memory tracking options")                                 \
 585                                                                             \
 586   product(bool, PrintNMTStatistics, false, DIAGNOSTIC,                      \
 587           "Print native memory tracking summary data if it is on")          \
 588                                                                             \
 589   product(bool, LogCompilation, false, DIAGNOSTIC,                          \
 590           "Log compilation activity in detail to LogFile")                  \
 591                                                                             \
 592   product(bool, PrintCompilation, false,                                    \
 593           "Print compilations")                                             \
 594                                                                             \
 595   product(intx, RepeatCompilation, 0, DIAGNOSTIC,                           \
 596           "Repeat compilation without installing code (number of times)")   \
 597           range(0, max_jint)                                                \
 598                                                                             \
 599   product(bool, PrintExtendedThreadInfo, false,                             \
 600           "Print more information in thread dump")                          \
 601                                                                             \
 602   product(intx, ScavengeRootsInCode, 2, DIAGNOSTIC,                         \
 603           "0: do not allow scavengable oops in the code cache; "            \
 604           "1: allow scavenging from the code cache; "                       \
 605           "2: emit as many constants as the compiler can see")              \
 606           range(0, 2)                                                       \
 607                                                                             \
 608   product(bool, AlwaysRestoreFPU, false,                                    \
 609           "Restore the FPU control word after every JNI call (expensive)")  \
 610                                                                             \
 611   product(bool, PrintCompilation2, false, DIAGNOSTIC,                       \
 612           "Print additional statistics per compilation")                    \
 613                                                                             \
 614   product(bool, PrintAdapterHandlers, false, DIAGNOSTIC,                    \
 615           "Print code generated for i2c/c2i adapters")                      \
 616                                                                             \
 617   product(bool, VerifyAdapterCalls, trueInDebug, DIAGNOSTIC,                \
 618           "Verify that i2c/c2i adapters are called properly")               \
 619                                                                             \
 620   develop(bool, VerifyAdapterSharing, false,                                \
 621           "Verify that the code for shared adapters is the equivalent")     \
 622                                                                             \
 623   product(bool, PrintAssembly, false, DIAGNOSTIC,                           \
 624           "Print assembly code (using external disassembler.so)")           \
 625                                                                             \
 626   product(ccstr, PrintAssemblyOptions, nullptr, DIAGNOSTIC,                 \
 627           "Print options string passed to disassembler.so")                 \
 628                                                                             \
 629   develop(bool, PrintNMethodStatistics, false,                              \
 630           "Print a summary statistic for the generated nmethods")           \
 631                                                                             \
 632   product(bool, PrintNMethods, false, DIAGNOSTIC,                           \
 633           "Print assembly code for nmethods when generated")                \
 634                                                                             \
 635   product(bool, PrintNativeNMethods, false, DIAGNOSTIC,                     \
 636           "Print assembly code for native nmethods when generated")         \
 637                                                                             \
 638   develop(bool, PrintDebugInfo, false,                                      \
 639           "Print debug information for all nmethods when generated")        \
 640                                                                             \
 641   develop(bool, PrintRelocations, false,                                    \
 642           "Print relocation information for all nmethods when generated")   \
 643                                                                             \
 644   develop(bool, PrintDependencies, false,                                   \
 645           "Print dependency information for all nmethods when generated")   \
 646                                                                             \
 647   develop(bool, PrintExceptionHandlers, false,                              \
 648           "Print exception handler tables for all nmethods when generated") \
 649                                                                             \
 650   develop(bool, StressCompiledExceptionHandlers, false,                     \
 651           "Exercise compiled exception handlers")                           \
 652                                                                             \
 653   develop(bool, InterceptOSException, false,                                \
 654           "Start debugger when an implicit OS (e.g. null pointer) "         \
 655           "exception happens")                                              \
 656                                                                             \
 657   product(bool, PrintCodeCache, false,                                      \
 658           "Print the code cache memory usage when exiting")                 \
 659                                                                             \
 660   develop(bool, PrintCodeCache2, false,                                     \
 661           "Print detailed usage information on the code cache when exiting")\
 662                                                                             \
 663   product(bool, PrintCodeCacheOnCompilation, false,                         \
 664           "Print the code cache memory usage each time a method is "        \
 665           "compiled")                                                       \
 666                                                                             \
 667   product(bool, PrintCodeHeapAnalytics, false, DIAGNOSTIC,                  \
 668           "Print code heap usage statistics on exit and on full condition") \
 669                                                                             \
 670   product(bool, PrintStubCode, false, DIAGNOSTIC,                           \
 671           "Print generated stub code")                                      \
 672                                                                             \
 673   product(bool, StackTraceInThrowable, true,                                \
 674           "Collect backtrace in throwable when exception happens")          \
 675                                                                             \
 676   product(bool, OmitStackTraceInFastThrow, true,                            \
 677           "Omit backtraces for some 'hot' exceptions in optimized code")    \
 678                                                                             \
 679   product(bool, ShowCodeDetailsInExceptionMessages, true, MANAGEABLE,       \
 680           "Show exception messages from RuntimeExceptions that contain "    \
 681           "snippets of the failing code. Disable this to improve privacy.") \
 682                                                                             \
 683   product(bool, PrintWarnings, true,                                        \
 684           "Print JVM warnings to output stream")                            \
 685                                                                             \
 686   develop(bool, RegisterReferences, true,                                   \
 687           "Tell whether the VM should register soft/weak/final/phantom "    \
 688           "references")                                                     \
 689                                                                             \
 690   develop(bool, PrintCodeCacheExtension, false,                             \
 691           "Print extension of code cache")                                  \
 692                                                                             \
 693   product(bool, ClassUnloading, true,                                       \
 694           "Do unloading of classes")                                        \
 695                                                                             \
 696   product(bool, ClassUnloadingWithConcurrentMark, true,                     \
 697           "Do unloading of classes with a concurrent marking cycle")        \
 698                                                                             \
 699   develop(bool, PrintSystemDictionaryAtExit, false,                         \
 700           "Print the system dictionary at exit")                            \
 701                                                                             \
 702   develop(bool, PrintClassLoaderDataGraphAtExit, false,                     \
 703           "Print the class loader data graph at exit")                      \
 704                                                                             \
 705   product(bool, AllowParallelDefineClass, false,                            \
 706           "Allow parallel defineClass requests for class loaders "          \
 707           "registering as parallel capable")                                \
 708                                                                             \
 709   product(bool, DisablePrimordialThreadGuardPages, false, EXPERIMENTAL,     \
 710                "Disable the use of stack guard pages if the JVM is loaded " \
 711                "on the primordial process thread")                          \
 712                                                                             \
 713   product(bool, DoJVMTIVirtualThreadTransitions, true, EXPERIMENTAL,        \
 714                "Do JVMTI virtual thread mount/unmount transitions "         \
 715                "(disabling this flag implies no JVMTI events are posted)")  \
 716                                                                             \
 717   /* notice: the max range value here is max_jint, not max_intx  */         \
 718   /* because of overflow issue                                   */         \
 719   product(intx, AsyncDeflationInterval, 250, DIAGNOSTIC,                    \
 720           "Async deflate idle monitors every so many milliseconds when "    \
 721           "MonitorUsedDeflationThreshold is exceeded (0 is off).")          \
 722           range(0, max_jint)                                                \
 723                                                                             \
 724   /* notice: the max range value here is max_jint, not max_intx  */         \
 725   /* because of overflow issue                                   */         \
 726   product(intx, GuaranteedAsyncDeflationInterval, 60000, DIAGNOSTIC,        \
 727           "Async deflate idle monitors every so many milliseconds even "    \
 728           "when MonitorUsedDeflationThreshold is NOT exceeded (0 is off).") \
 729           range(0, max_jint)                                                \
 730                                                                             \
 731   product(size_t, AvgMonitorsPerThreadEstimate, 1024, DIAGNOSTIC,           \
 732           "Used to estimate a variable ceiling based on number of threads " \
 733           "for use with MonitorUsedDeflationThreshold (0 is off).")         \
 734           range(0, max_uintx)                                               \
 735                                                                             \
 736   /* notice: the max range value here is max_jint, not max_intx  */         \
 737   /* because of overflow issue                                   */         \
 738   product(intx, MonitorDeflationMax, 1000000, DIAGNOSTIC,                   \
 739           "The maximum number of monitors to deflate, unlink and delete "   \
 740           "at one time (minimum is 1024).")                                 \
 741           range(1024, max_jint)                                             \
 742                                                                             \
 743   product(intx, MonitorUnlinkBatch, 500, DIAGNOSTIC,                        \
 744           "The maximum number of monitors to unlink in one batch. ")        \
 745           range(1, max_jint)                                                \
 746                                                                             \
 747   product(int, MonitorUsedDeflationThreshold, 90, DIAGNOSTIC,               \
 748           "Percentage of used monitors before triggering deflation (0 is "  \
 749           "off). The check is performed on AsyncDeflationInterval or "      \
 750           "GuaranteedAsyncDeflationInterval, whichever is lower.")          \
 751           range(0, 100)                                                     \
 752                                                                             \
 753   product(uintx, NoAsyncDeflationProgressMax, 3, DIAGNOSTIC,                \
 754           "Max number of no progress async deflation attempts to tolerate " \
 755           "before adjusting the in_use_list_ceiling up (0 is off).")        \
 756           range(0, max_uintx)                                               \
 757                                                                             \
 758   product(intx, hashCode, 5, EXPERIMENTAL,                                  \
 759                "(Unstable) select hashCode generation algorithm")           \
 760                                                                             \
 761   product(bool, ReduceSignalUsage, false,                                   \
 762           "Reduce the use of OS signals in Java and/or the VM")             \
 763                                                                             \
 764   develop(bool, LoadLineNumberTables, true,                                 \
 765           "Tell whether the class file parser loads line number tables")    \
 766                                                                             \
 767   develop(bool, LoadLocalVariableTables, true,                              \
 768           "Tell whether the class file parser loads local variable tables") \
 769                                                                             \
 770   develop(bool, LoadLocalVariableTypeTables, true,                          \
 771           "Tell whether the class file parser loads local variable type"    \
 772           "tables")                                                         \
 773                                                                             \
 774   product(bool, AllowUserSignalHandlers, false,                             \
 775           "Application will install primary signal handlers for the JVM "   \
 776           "(Unix only)")                                                    \
 777                                                                             \
 778   product(bool, UseSignalChaining, true,                                    \
 779           "Use signal-chaining to invoke signal handlers installed "        \
 780           "by the application (Unix only)")                                 \
 781                                                                             \
 782   product(bool, RestoreMXCSROnJNICalls, false,                              \
 783           "Restore MXCSR when returning from JNI calls")                    \
 784                                                                             \
 785   product(bool, CheckJNICalls, false,                                       \
 786           "Verify all arguments to JNI calls")                              \
 787                                                                             \
 788   product(bool, UseFastJNIAccessors, true,                                  \
 789           "Use optimized versions of Get<Primitive>Field")                  \
 790                                                                             \
 791   product(intx, MaxJNILocalCapacity, 65536,                                 \
 792           "Maximum allowable local JNI handle capacity to "                 \
 793           "EnsureLocalCapacity() and PushLocalFrame(), "                    \
 794           "where <= 0 is unlimited, default: 65536")                        \
 795           range(min_intx, max_intx)                                         \
 796                                                                             \
 797   product(bool, EagerXrunInit, false,                                       \
 798           "Eagerly initialize -Xrun libraries; allows startup profiling, "  \
 799           "but not all -Xrun libraries may support the state of the VM "    \
 800           "at this time")                                                   \
 801                                                                             \
 802   develop(uintx, PreallocatedOutOfMemoryErrorCount, 4,                      \
 803           "Number of OutOfMemoryErrors preallocated with backtrace")        \
 804                                                                             \
 805   product(bool, UseXMMForArrayCopy, false,                                  \
 806           "Use SSE2 MOVQ instruction for Arraycopy")                        \
 807                                                                             \
 808   product(bool, PrintFieldLayout, false, DIAGNOSTIC,                        \
 809           "Print field layout for each class")                              \
 810                                                                             \
 811   product(bool, PrintInlineLayout, false, DIAGNOSTIC,                       \
 812           "Print field layout for each inline type or class with inline fields") \
 813                                                                             \
 814   product(bool, PrintFlatArrayLayout, false, DIAGNOSTIC,                    \
 815           "Print array layout for each inline type array")                  \
 816                                                                             \
 817   product(bool, UseArrayFlattening, true,                                   \
 818           "Allow the VM to flatten arrays")                                 \
 819                                                                             \
 820   product(bool, UseFieldFlattening, true,                                   \
 821           "Allow the VM to flatten value fields")                           \
 822                                                                             \
 823   product(bool, UseNonAtomicValueFlattening, true,                          \
 824           "Allow the JVM to flatten some non-atomic null-free values")      \
 825                                                                             \
 826   product(bool, UseNullableValueFlattening, false,                          \
 827           "Allow the JVM to flatten some nullable values")                  \
 828                                                                             \
 829   product(bool, UseAtomicValueFlattening, false,                            \
 830           "Allow the JVM to flatten some atomic values")                    \
 831                                                                             \
 832   product(intx, FlatArrayElementMaxOops, 4,                                 \
 833           "Max nof embedded object references in an inline type to flatten, <0 no limit")  \
 834                                                                             \
 835   /* Need to limit the extent of the padding to reasonable size.          */\
 836   /* 8K is well beyond the reasonable HW cache line size, even with       */\
 837   /* aggressive prefetching, while still leaving the room for segregating */\
 838   /* among the distinct pages.                                            */\
 839   product(int, ContendedPaddingWidth, 128,                                  \
 840           "How many bytes to pad the fields/classes marked @Contended with")\
 841           range(0, 8192)                                                    \
 842           constraint(ContendedPaddingWidthConstraintFunc,AfterErgo)         \
 843                                                                             \
 844   product(bool, EnableContended, true,                                      \
 845           "Enable @Contended annotation support")                           \
 846                                                                             \
 847   product(bool, RestrictContended, true,                                    \
 848           "Restrict @Contended to trusted classes")                         \
 849                                                                             \
 850   product(int, DiagnoseSyncOnValueBasedClasses, 0, DIAGNOSTIC,              \
 851              "Detect and take action upon identifying synchronization on "  \
 852              "value based classes. Modes: "                                 \
 853              "0: off; "                                                     \
 854              "1: exit with fatal error; "                                   \
 855              "2: log message to stdout. Output file can be specified with " \
 856              "   -Xlog:valuebasedclasses. If JFR is running it will "       \
 857              "   also generate JFR events.")                                \
 858              range(0, 2)                                                    \
 859                                                                             \
 860   product(bool, ExitOnOutOfMemoryError, false,                              \
 861           "JVM exits on the first occurrence of an out-of-memory error "    \
 862           "thrown from JVM")                                                \
 863                                                                             \
 864   product(bool, CrashOnOutOfMemoryError, false,                             \
 865           "JVM aborts, producing an error log and core/mini dump, on the "  \
 866           "first occurrence of an out-of-memory error thrown from JVM")     \
 867                                                                             \
 868   product(intx, UserThreadWaitAttemptsAtExit, 30,                           \
 869           "The number of times to wait for user threads to stop executing " \
 870           "native code during JVM exit. Each wait lasts 10 milliseconds. "  \
 871           "The maximum number of waits is 1000, to wait at most 10 "        \
 872           "seconds.")                                                       \
 873           range(0, 1000)                                                    \
 874                                                                             \
 875   /* tracing */                                                             \
 876                                                                             \
 877   develop(bool, StressRewriter, false,                                      \
 878           "Stress linktime bytecode rewriting")                             \
 879                                                                             \
 880   product(ccstr, TraceJVMTI, nullptr,                                       \
 881           "Trace flags for JVMTI functions and events")                     \
 882                                                                             \
 883   product(bool, StressLdcRewrite, false, DIAGNOSTIC,                        \
 884           "Force ldc -> ldc_w rewrite during RedefineClasses. "             \
 885           "This option can change an EMCP method into an obsolete method "  \
 886           "and can affect tests that expect specific methods to be EMCP. "  \
 887           "This option should be used with caution.")                       \
 888                                                                             \
 889   product(bool, AllowRedefinitionToAddDeleteMethods, false,                 \
 890           "(Deprecated) Allow redefinition to add and delete private "      \
 891           "static or final methods for compatibility with old releases")    \
 892                                                                             \
 893   develop(bool, TraceBytecodes, false,                                      \
 894           "Trace bytecode execution")                                       \
 895                                                                             \
 896   develop(bool, TraceBytecodesTruncated, false,                             \
 897           "Truncate non control-flow bytecode when tracing bytecode")       \
 898                                                                             \
 899   develop(bool, VerifyDependencies, trueInDebug,                            \
 900           "Exercise and verify the compilation dependency mechanism")       \
 901                                                                             \
 902   develop(bool, TraceNewOopMapGeneration, false,                            \
 903           "Trace OopMapGeneration")                                         \
 904                                                                             \
 905   develop(bool, TraceNewOopMapGenerationDetailed, false,                    \
 906           "Trace OopMapGeneration: print detailed cell states")             \
 907                                                                             \
 908   develop(bool, TimeOopMap, false,                                          \
 909           "Time calls to GenerateOopMap::compute_map() in sum")             \
 910                                                                             \
 911   develop(bool, TimeOopMap2, false,                                         \
 912           "Time calls to GenerateOopMap::compute_map() individually")       \
 913                                                                             \
 914   develop(bool, TraceOopMapRewrites, false,                                 \
 915           "Trace rewriting of methods during oop map generation")           \
 916                                                                             \
 917   develop(bool, TraceFinalizerRegistration, false,                          \
 918           "Trace registration of final references")                         \
 919                                                                             \
 920   product(bool, IgnoreEmptyClassPaths, false,                               \
 921           "Ignore empty path elements in -classpath")                       \
 922                                                                             \
 923   product(bool, PrintHeapAtSIGBREAK, true,                                  \
 924           "Print heap layout in response to SIGBREAK")                      \
 925                                                                             \
 926   product(bool, PrintClassHistogram, false, MANAGEABLE,                     \
 927           "Print a histogram of class instances")                           \
 928                                                                             \
 929   product(double, ObjectCountCutOffPercent, 0.5, EXPERIMENTAL,              \
 930           "The percentage of the used heap that the instances of a class "  \
 931           "must occupy for the class to generate a trace event")            \
 932           range(0.0, 100.0)                                                 \
 933                                                                             \
 934   /* JVMTI heap profiling */                                                \
 935                                                                             \
 936   product(bool, VerifyBeforeIteration, false, DIAGNOSTIC,                   \
 937           "Verify memory system before JVMTI iteration")                    \
 938                                                                             \
 939   /* compiler */                                                            \
 940                                                                             \
 941   /* notice: the max range value here is max_jint, not max_intx  */         \
 942   /* because of overflow issue                                   */         \
 943   product(intx, CICompilerCount, CI_COMPILER_COUNT,                         \
 944           "Number of compiler threads to run")                              \
 945           range(0, max_jint)                                                \
 946           constraint(CICompilerCountConstraintFunc, AfterErgo)              \
 947                                                                             \
 948   product(bool, UseDynamicNumberOfCompilerThreads, true,                    \
 949           "Dynamically choose the number of parallel compiler threads")     \
 950                                                                             \
 951   product(bool, ReduceNumberOfCompilerThreads, true, DIAGNOSTIC,            \
 952              "Reduce the number of parallel compiler threads when they "    \
 953              "are not used")                                                \
 954                                                                             \
 955   product(bool, TraceCompilerThreads, false, DIAGNOSTIC,                    \
 956              "Trace creation and removal of compiler threads")              \
 957                                                                             \
 958   product(ccstr, LogClassLoadingCauseFor, nullptr,                          \
 959           "Apply -Xlog:class+load+cause* to classes whose fully "           \
 960           "qualified name contains this string (\"*\" matches "             \
 961           "any class).")                                                    \
 962                                                                             \
 963   develop(bool, InjectCompilerCreationFailure, false,                       \
 964           "Inject thread creation failures for "                            \
 965           "UseDynamicNumberOfCompilerThreads")                              \
 966                                                                             \
 967   develop(bool, GenerateSynchronizationCode, true,                          \
 968           "generate locking/unlocking code for synchronized methods and "   \
 969           "monitors")                                                       \
 970                                                                             \
 971   product_pd(bool, ImplicitNullChecks, DIAGNOSTIC,                          \
 972           "Generate code for implicit null checks")                         \
 973                                                                             \
 974   product_pd(bool, TrapBasedNullChecks,                                     \
 975           "Generate code for null checks that uses a cmp and trap "         \
 976           "instruction raising SIGTRAP.  This is only used if an access to" \
 977           "null (+offset) will not raise a SIGSEGV, i.e.,"                  \
 978           "ImplicitNullChecks don't work (PPC64).")                         \
 979                                                                             \
 980   product(bool, EnableThreadSMRStatistics, trueInDebug, DIAGNOSTIC,         \
 981              "Enable Thread SMR Statistics")                                \
 982                                                                             \
 983   product(bool, Inline, true,                                               \
 984           "Enable inlining")                                                \
 985                                                                             \
 986   product(bool, ClipInlining, true,                                         \
 987           "Clip inlining if aggregate method exceeds DesiredMethodLimit")   \
 988                                                                             \
 989   develop(bool, UseCHA, true,                                               \
 990           "Enable CHA")                                                     \
 991                                                                             \
 992   product(bool, UseTypeProfile, true,                                       \
 993           "Check interpreter profile for historically monomorphic calls")   \
 994                                                                             \
 995   product(bool, PrintInlining, false, DIAGNOSTIC,                           \
 996           "Print inlining optimizations")                                   \
 997                                                                             \
 998   product(bool, UsePopCountInstruction, false,                              \
 999           "Use population count instruction")                               \
1000                                                                             \
1001   develop(bool, TraceMethodReplacement, false,                              \
1002           "Print when methods are replaced do to recompilation")            \
1003                                                                             \
1004   product(intx, MinPassesBeforeFlush, 10, DIAGNOSTIC,                       \
1005           "Minimum number of sweeper passes before an nmethod "             \
1006           "can be flushed")                                                 \
1007           range(0, max_intx)                                                \
1008                                                                             \
1009   develop(bool, StressCodeBuffers, false,                                   \
1010           "Exercise code buffer expansion and other rare state changes")    \
1011                                                                             \
1012   product(bool, DebugNonSafepoints, trueInDebug, DIAGNOSTIC,                \
1013           "Generate extra debugging information for non-safepoints in "     \
1014           "nmethods")                                                       \
1015                                                                             \
1016   product(bool, PrintVMOptions, false,                                      \
1017           "Print flags that appeared on the command line")                  \
1018                                                                             \
1019   product(bool, IgnoreUnrecognizedVMOptions, false,                         \
1020           "Ignore unrecognized VM options")                                 \
1021                                                                             \
1022   product(bool, PrintCommandLineFlags, false,                               \
1023           "Print flags specified on command line or set by ergonomics")     \
1024                                                                             \
1025   product(bool, PrintFlagsInitial, false,                                   \
1026           "Print all VM flags before argument processing and exit VM")      \
1027                                                                             \
1028   product(bool, PrintFlagsFinal, false,                                     \
1029           "Print all VM flags after argument and ergonomic processing")     \
1030                                                                             \
1031   develop(bool, PrintFlagsWithComments, false,                              \
1032           "Print all VM flags with default values and descriptions and "    \
1033           "exit")                                                           \
1034                                                                             \
1035   product(bool, PrintFlagsRanges, false,                                    \
1036           "Print VM flags and their ranges")                                \
1037                                                                             \
1038   product(bool, SerializeVMOutput, true, DIAGNOSTIC,                        \
1039           "Use a mutex to serialize output to tty and LogFile")             \
1040                                                                             \
1041   product(bool, DisplayVMOutput, true, DIAGNOSTIC,                          \
1042           "Display all VM output on the tty, independently of LogVMOutput") \
1043                                                                             \
1044   product(bool, LogVMOutput, false, DIAGNOSTIC,                             \
1045           "Save VM output to LogFile")                                      \
1046                                                                             \
1047   product(ccstr, LogFile, nullptr, DIAGNOSTIC,                              \
1048           "If LogVMOutput or LogCompilation is on, save VM output to "      \
1049           "this file [default: ./hotspot_pid%p.log] (%p replaced with pid)")\
1050                                                                             \
1051   product(ccstr, ErrorFile, nullptr,                                        \
1052           "If an error occurs, save the error data to this file "           \
1053           "[default: ./hs_err_pid%p.log] (%p replaced with pid)")           \
1054                                                                             \
1055   product(bool, ExtensiveErrorReports,                                      \
1056           PRODUCT_ONLY(false) NOT_PRODUCT(true),                            \
1057           "Error reports are more extensive.")                              \
1058                                                                             \
1059   product(bool, DisplayVMOutputToStderr, false,                             \
1060           "If DisplayVMOutput is true, display all VM output to stderr")    \
1061                                                                             \
1062   product(bool, DisplayVMOutputToStdout, false,                             \
1063           "If DisplayVMOutput is true, display all VM output to stdout")    \
1064                                                                             \
1065   product(bool, ErrorFileToStderr, false,                                   \
1066           "If true, error data is printed to stderr instead of a file")     \
1067                                                                             \
1068   product(bool, ErrorFileToStdout, false,                                   \
1069           "If true, error data is printed to stdout instead of a file")     \
1070                                                                             \
1071   develop(bool, VerifyHeavyMonitors, false,                                 \
1072           "Checks that no stack locking happens when using "                \
1073           "-XX:LockingMode=0 (LM_MONITOR)")                                 \
1074                                                                             \
1075   product(bool, PrintStringTableStatistics, false,                          \
1076           "print statistics about the StringTable and SymbolTable")         \
1077                                                                             \
1078   product(bool, VerifyStringTableAtExit, false, DIAGNOSTIC,                 \
1079           "verify StringTable contents at exit")                            \
1080                                                                             \
1081   develop(bool, PrintSymbolTableSizeHistogram, false,                       \
1082           "print histogram of the symbol table")                            \
1083                                                                             \
1084   product(ccstr, AbortVMOnException, nullptr, DIAGNOSTIC,                   \
1085           "Call fatal if this exception is thrown.  Example: "              \
1086           "java -XX:AbortVMOnException=java.lang.NullPointerException Foo") \
1087                                                                             \
1088   product(ccstr, AbortVMOnExceptionMessage, nullptr, DIAGNOSTIC,            \
1089           "Call fatal if the exception pointed by AbortVMOnException "      \
1090           "has this message")                                               \
1091                                                                             \
1092   develop(bool, DebugVtables, false,                                        \
1093           "add debugging code to vtable dispatch")                          \
1094                                                                             \
1095   product(bool, RangeCheckElimination, true,                                \
1096           "Eliminate range checks")                                         \
1097                                                                             \
1098   develop_pd(bool, UncommonNullCast,                                        \
1099           "track occurrences of null in casts; adjust compiler tactics")    \
1100                                                                             \
1101   develop(bool, TypeProfileCasts,  true,                                    \
1102           "treat casts like calls for purposes of type profiling")          \
1103                                                                             \
1104   develop(bool, TraceLivenessGen, false,                                    \
1105           "Trace the generation of liveness analysis information")          \
1106                                                                             \
1107   develop(bool, TraceLivenessQuery, false,                                  \
1108           "Trace queries of liveness analysis information")                 \
1109                                                                             \
1110   develop(bool, CollectIndexSetStatistics, false,                           \
1111           "Collect information about IndexSets")                            \
1112                                                                             \
1113   develop(int, FastAllocateSizeLimit, 128*K,                                \
1114           /* Note:  This value is zero mod 1<<13 for a cheap sparc set. */  \
1115           "Inline allocations larger than this in doublewords must go slow")\
1116                                                                             \
1117   product_pd(bool, CompactStrings,                                          \
1118           "Enable Strings to use single byte chars in backing store")       \
1119                                                                             \
1120   product_pd(uint, TypeProfileLevel,                                        \
1121           "=XYZ, with Z: Type profiling of arguments at call; "             \
1122                      "Y: Type profiling of return value at call; "          \
1123                      "X: Type profiling of parameters to methods; "         \
1124           "X, Y and Z in 0=off ; 1=jsr292 only; 2=all methods")             \
1125           constraint(TypeProfileLevelConstraintFunc, AfterErgo)             \
1126                                                                             \
1127   product(int, TypeProfileArgsLimit,     2,                                 \
1128           "max number of call arguments to consider for type profiling")    \
1129           range(0, 16)                                                      \
1130                                                                             \
1131   product(int, TypeProfileParmsLimit,    2,                                 \
1132           "max number of incoming parameters to consider for type profiling"\
1133           ", -1 for all")                                                   \
1134           range(-1, 64)                                                     \
1135                                                                             \
1136   /* statistics */                                                          \
1137   develop(bool, CountCompiledCalls, false,                                  \
1138           "Count method invocations")                                       \
1139                                                                             \
1140   develop(bool, ICMissHistogram, false,                                     \
1141           "Produce histogram of IC misses")                                 \
1142                                                                             \
1143   /* interpreter */                                                         \
1144   product_pd(bool, RewriteBytecodes,                                        \
1145           "Allow rewriting of bytecodes (bytecodes are not immutable)")     \
1146                                                                             \
1147   product_pd(bool, RewriteFrequentPairs,                                    \
1148           "Rewrite frequently used bytecode pairs into a single bytecode")  \
1149                                                                             \
1150   product(bool, PrintInterpreter, false, DIAGNOSTIC,                        \
1151           "Print the generated interpreter code")                           \
1152                                                                             \
1153   product(bool, UseInterpreter, true,                                       \
1154           "Use interpreter for non-compiled methods")                       \
1155                                                                             \
1156   develop(bool, UseFastSignatureHandlers, true,                             \
1157           "Use fast signature handlers for native calls")                   \
1158                                                                             \
1159   product(bool, UseLoopCounter, true,                                       \
1160           "Increment invocation counter on backward branch")                \
1161                                                                             \
1162   product_pd(bool, UseOnStackReplacement,                                   \
1163           "Use on stack replacement, calls runtime if invoc. counter "      \
1164           "overflows in loop")                                              \
1165                                                                             \
1166   develop(bool, TraceOnStackReplacement, false,                             \
1167           "Trace on stack replacement")                                     \
1168                                                                             \
1169   product_pd(bool, PreferInterpreterNativeStubs,                            \
1170           "Use always interpreter stubs for native methods invoked via "    \
1171           "interpreter")                                                    \
1172                                                                             \
1173   develop(bool, CountBytecodes, false,                                      \
1174           "Count number of bytecodes executed")                             \
1175                                                                             \
1176   develop(bool, PrintBytecodeHistogram, false,                              \
1177           "Print histogram of the executed bytecodes")                      \
1178                                                                             \
1179   develop(bool, PrintBytecodePairHistogram, false,                          \
1180           "Print histogram of the executed bytecode pairs")                 \
1181                                                                             \
1182   product(bool, PrintSignatureHandlers, false, DIAGNOSTIC,                  \
1183           "Print code generated for native method signature handlers")      \
1184                                                                             \
1185   develop(bool, VerifyOops, false,                                          \
1186           "Do plausibility checks for oops")                                \
1187                                                                             \
1188   develop(bool, CheckUnhandledOops, false,                                  \
1189           "Check for unhandled oops in VM code")                            \
1190                                                                             \
1191   develop(bool, VerifyJNIFields, trueInDebug,                               \
1192           "Verify jfieldIDs for instance fields")                           \
1193                                                                             \
1194   develop(bool, VerifyActivationFrameSize, false,                           \
1195           "Verify that activation frame didn't become smaller than its "    \
1196           "minimal size")                                                   \
1197                                                                             \
1198   develop(bool, TraceFrequencyInlining, false,                              \
1199           "Trace frequency based inlining")                                 \
1200                                                                             \
1201   develop_pd(bool, InlineIntrinsics,                                        \
1202           "Use intrinsics in Interpreter that can be statically resolved")  \
1203                                                                             \
1204   product_pd(bool, ProfileInterpreter,                                      \
1205           "Profile at the bytecode level during interpretation")            \
1206                                                                             \
1207   develop_pd(bool, ProfileTraps,                                            \
1208           "Profile deoptimization traps at the bytecode level")             \
1209                                                                             \
1210   product(intx, ProfileMaturityPercentage, 20,                              \
1211           "number of method invocations/branches (expressed as % of "       \
1212           "CompileThreshold) before using the method's profile")            \
1213           range(0, 100)                                                     \
1214                                                                             \
1215   product(bool, PrintMethodData, false, DIAGNOSTIC,                         \
1216           "Print the results of +ProfileInterpreter at end of run")         \
1217                                                                             \
1218   develop(bool, VerifyDataPointer, trueInDebug,                             \
1219           "Verify the method data pointer during interpreter profiling")    \
1220                                                                             \
1221   develop(bool, CrashGCForDumpingJavaThread, false,                         \
1222           "Manually make GC thread crash then dump java stack trace;  "     \
1223           "Test only")                                                      \
1224                                                                             \
1225   /* compilation */                                                         \
1226   product(bool, UseCompiler, true,                                          \
1227           "Use Just-In-Time compilation")                                   \
1228                                                                             \
1229   product(bool, AlwaysCompileLoopMethods, false,                            \
1230           "When using recompilation, never interpret methods "              \
1231           "containing loops")                                               \
1232                                                                             \
1233   product(int,  AllocatePrefetchStyle, 1,                                   \
1234           "0 = no prefetch, "                                               \
1235           "1 = generate prefetch instructions for each allocation, "        \
1236           "2 = use TLAB watermark to gate allocation prefetch, "            \
1237           "3 = generate one prefetch instruction per cache line")           \
1238           range(0, 3)                                                       \
1239                                                                             \
1240   product(int,  AllocatePrefetchDistance, -1,                               \
1241           "Distance to prefetch ahead of allocation pointer. "              \
1242           "-1: use system-specific value (automatically determined")        \
1243           range(-1, 512)                                                    \
1244                                                                             \
1245   product(int,  AllocatePrefetchLines, 3,                                   \
1246           "Number of lines to prefetch ahead of array allocation pointer")  \
1247           range(1, 64)                                                      \
1248                                                                             \
1249   product(int,  AllocateInstancePrefetchLines, 1,                           \
1250           "Number of lines to prefetch ahead of instance allocation "       \
1251           "pointer")                                                        \
1252           range(1, 64)                                                      \
1253                                                                             \
1254   product(int,  AllocatePrefetchStepSize, 16,                               \
1255           "Step size in bytes of sequential prefetch instructions")         \
1256           range(1, 512)                                                     \
1257           constraint(AllocatePrefetchStepSizeConstraintFunc,AfterMemoryInit)\
1258                                                                             \
1259   product(intx,  AllocatePrefetchInstr, 0,                                  \
1260           "Select instruction to prefetch ahead of allocation pointer")     \
1261           constraint(AllocatePrefetchInstrConstraintFunc, AfterMemoryInit)  \
1262                                                                             \
1263   /* deoptimization */                                                      \
1264   product(bool, TraceDeoptimization, false, DIAGNOSTIC,                     \
1265           "Trace deoptimization")                                           \
1266                                                                             \
1267   develop(bool, PrintDeoptimizationDetails, false,                          \
1268           "Print more information about deoptimization")                    \
1269                                                                             \
1270   develop(bool, DebugDeoptimization, false,                                 \
1271           "Tracing various information while debugging deoptimization")     \
1272                                                                             \
1273   product(double, SelfDestructTimer, 0.0,                                   \
1274           "Will cause VM to terminate after a given time "                  \
1275           "(in fractional minutes) "                                        \
1276           "(0.0 means off)")                                                \
1277           range(0.0, (double)max_intx)                                      \
1278                                                                             \
1279   product(int, MaxJavaStackTraceDepth, 1024,                                \
1280           "The maximum number of lines in the stack trace for Java "        \
1281           "exceptions (0 means all)")                                       \
1282           range(0, max_jint/2)                                              \
1283                                                                             \
1284   /* notice: the max range value here is max_jint, not max_intx  */         \
1285   /* because of overflow issue                                   */         \
1286   product(intx, GuaranteedSafepointInterval, 0, DIAGNOSTIC,                 \
1287           "Guarantee a safepoint (at least) every so many milliseconds "    \
1288           "(0 means none)")                                                 \
1289           range(0, max_jint)                                                \
1290                                                                             \
1291   product(intx, ServiceThreadCleanupInterval, 1000, DIAGNOSTIC,             \
1292           "Wake the ServiceThread to do periodic cleanup checks every so "  \
1293           "many milliseconds (0 means none)")                               \
1294           range(0, max_jint)                                                \
1295                                                                             \
1296   product(double, SafepointTimeoutDelay, 10000,                             \
1297           "Delay in milliseconds for option SafepointTimeout; "             \
1298           "supports sub-millisecond resolution with fractional values.")    \
1299           range(0, max_jlongDouble LP64_ONLY(/MICROUNITS))                  \
1300                                                                             \
1301   product(bool, UseSystemMemoryBarrier, false,                              \
1302           "Try to enable system memory barrier if supported by OS")         \
1303                                                                             \
1304   product(intx, NmethodSweepActivity, 4,                                    \
1305           "Removes cold nmethods from code cache if > 0. Higher values "    \
1306           "result in more aggressive sweeping")                             \
1307           range(0, 2000)                                                    \
1308                                                                             \
1309   develop(intx, MallocCatchPtr, -1,                                         \
1310           "Hit breakpoint when mallocing/freeing this pointer")             \
1311                                                                             \
1312   develop(int, StackPrintLimit, 100,                                        \
1313           "number of stack frames to print in VM-level stack dump")         \
1314                                                                             \
1315   product(int, ErrorLogPrintCodeLimit, 3, DIAGNOSTIC,                       \
1316           "max number of compiled code units to print in error log")        \
1317           range(0, VMError::max_error_log_print_code)                       \
1318                                                                             \
1319   develop(int, MaxElementPrintSize, 256,                                    \
1320           "maximum number of elements to print")                            \
1321                                                                             \
1322   develop(int, MaxStringPrintSize, 256,                                     \
1323           "maximum number of characters to print for a java.lang.String "   \
1324           "in the VM. If exceeded, an abridged version of the string is "   \
1325           "printed with the middle of the string elided.")                  \
1326           range(2, O_BUFLEN)                                                \
1327                                                                             \
1328   develop(intx, MaxSubklassPrintSize, 4,                                    \
1329           "maximum number of subklasses to print when printing klass")      \
1330                                                                             \
1331   develop(intx, MaxForceInlineLevel, 100,                                   \
1332           "maximum number of nested calls that are forced for inlining "    \
1333           "(using CompileCommand or marked w/ @ForceInline)")               \
1334           range(0, max_jint)                                                \
1335                                                                             \
1336   develop(intx, MethodHistogramCutoff, 100,                                 \
1337           "The cutoff value for method invocation histogram (+CountCalls)") \
1338                                                                             \
1339   develop(intx, DeoptimizeALotInterval,     5,                              \
1340           "Number of exits until DeoptimizeALot kicks in")                  \
1341                                                                             \
1342   develop(intx, ZombieALotInterval,     5,                                  \
1343           "Number of exits until ZombieALot kicks in")                      \
1344                                                                             \
1345   product(ccstr, MallocLimit, nullptr, DIAGNOSTIC,                          \
1346           "Limit malloc allocation size from VM. Reaching a limit will "    \
1347           "trigger an action (see flag). This feature requires "            \
1348           "NativeMemoryTracking=summary or NativeMemoryTracking=detail."    \
1349           "Usage:"                                                          \
1350           "\"-XX:MallocLimit=<size>[:<flag>]\" sets a total limit."         \
1351           "\"-XX:MallocLimit=<category>:<size>[:<flag>][,<category>:<size>[:<flag>] ...]\"" \
1352           "sets one or more category-specific limits."                      \
1353           "<flag> defines the action upon reaching the limit:"              \
1354           "\"fatal\": end VM with a fatal error at the allocation site"     \
1355           "\"oom\"  : will mimic a native OOM"                              \
1356           "If <flag> is omitted, \"fatal\" is the default."                 \
1357           "Examples:\n"                                                     \
1358           "-XX:MallocLimit=2g"                                              \
1359           "-XX:MallocLimit=2g:oom"                                          \
1360           "-XX:MallocLimit=compiler:200m:oom,code:100m")                    \
1361                                                                             \
1362   product(intx, TypeProfileWidth, 2,                                        \
1363           "Number of receiver types to record in call/cast profile")        \
1364           range(0, 8)                                                       \
1365                                                                             \
1366   develop(intx, BciProfileWidth,      2,                                    \
1367           "Number of return bci's to record in ret profile")                \
1368                                                                             \
1369   product(intx, PerMethodRecompilationCutoff, 400,                          \
1370           "After recompiling N times, stay in the interpreter (-1=>'Inf')") \
1371           range(-1, max_intx)                                               \
1372                                                                             \
1373   product(intx, PerBytecodeRecompilationCutoff, 200,                        \
1374           "Per-BCI limit on repeated recompilation (-1=>'Inf')")            \
1375           range(-1, max_intx)                                               \
1376                                                                             \
1377   product(intx, PerMethodTrapLimit,  100,                                   \
1378           "Limit on traps (of one kind) in a method (includes inlines)")    \
1379           range(0, max_jint)                                                \
1380                                                                             \
1381   product(intx, PerMethodSpecTrapLimit,  5000, EXPERIMENTAL,                \
1382           "Limit on speculative traps (of one kind) in a method "           \
1383           "(includes inlines)")                                             \
1384           range(0, max_jint)                                                \
1385                                                                             \
1386   product(intx, PerBytecodeTrapLimit,  4,                                   \
1387           "Limit on traps (of one kind) at a particular BCI")               \
1388           range(0, max_jint)                                                \
1389                                                                             \
1390   product(int, SpecTrapLimitExtraEntries,  3, EXPERIMENTAL,                 \
1391           "Extra method data trap entries for speculation")                 \
1392                                                                             \
1393   product(double, InlineFrequencyRatio, 0.25, DIAGNOSTIC,                   \
1394           "Ratio of call site execution to caller method invocation")       \
1395                                                                             \
1396   product(double, MinInlineFrequencyRatio, 0.0085, DIAGNOSTIC,              \
1397           "Minimum ratio of call site execution to caller method"           \
1398           "invocation to be considered for inlining")                       \
1399                                                                             \
1400   develop(intx, InlineThrowCount,    50,                                    \
1401           "Force inlining of interpreted methods that throw this often")    \
1402           range(0, max_jint)                                                \
1403                                                                             \
1404   develop(intx, InlineThrowMaxSize,   200,                                  \
1405           "Force inlining of throwing methods smaller than this")           \
1406           range(0, max_jint)                                                \
1407                                                                             \
1408   product(size_t, MetaspaceSize, NOT_LP64(16 * M) LP64_ONLY(21 * M),        \
1409           "Initial threshold (in bytes) at which a garbage collection "     \
1410           "is done to reduce Metaspace usage")                              \
1411           constraint(MetaspaceSizeConstraintFunc,AfterErgo)                 \
1412                                                                             \
1413   product(size_t, MaxMetaspaceSize, max_uintx,                              \
1414           "Maximum size of Metaspaces (in bytes)")                          \
1415           constraint(MaxMetaspaceSizeConstraintFunc,AfterErgo)              \
1416                                                                             \
1417   product(size_t, CompressedClassSpaceSize, 1*G,                            \
1418           "Maximum size of class area in Metaspace when compressed "        \
1419           "class pointers are used")                                        \
1420           range(1*M, LP64_ONLY(4*G) NOT_LP64(max_uintx))                    \
1421                                                                             \
1422   develop(size_t, CompressedClassSpaceBaseAddress, 0,                       \
1423           "Force the class space to be allocated at this address or "       \
1424           "fails VM initialization (requires -Xshare=off.")                 \
1425                                                                             \
1426   develop(bool, RandomizeClassSpaceLocation, true,                          \
1427           "Randomize location of class space.")                             \
1428                                                                             \
1429   product(bool, PrintMetaspaceStatisticsAtExit, false, DIAGNOSTIC,          \
1430           "Print metaspace statistics upon VM exit.")                       \
1431                                                                             \
1432   product(bool, PrintCompilerMemoryStatisticsAtExit, false, DIAGNOSTIC,     \
1433           "Print compiler memory statistics upon VM exit.")                 \
1434                                                                             \
1435   product(uintx, MinHeapFreeRatio, 40, MANAGEABLE,                          \
1436           "The minimum percentage of heap free after GC to avoid expansion."\
1437           " For most GCs this applies to the old generation. In G1 and"     \
1438           " ParallelGC it applies to the whole heap.")                      \
1439           range(0, 100)                                                     \
1440           constraint(MinHeapFreeRatioConstraintFunc,AfterErgo)              \
1441                                                                             \
1442   product(uintx, MaxHeapFreeRatio, 70, MANAGEABLE,                          \
1443           "The maximum percentage of heap free after GC to avoid shrinking."\
1444           " For most GCs this applies to the old generation. In G1 and"     \
1445           " ParallelGC it applies to the whole heap.")                      \
1446           range(0, 100)                                                     \
1447           constraint(MaxHeapFreeRatioConstraintFunc,AfterErgo)              \
1448                                                                             \
1449   product(intx, SoftRefLRUPolicyMSPerMB, 1000,                              \
1450           "Number of milliseconds per MB of free space in the heap")        \
1451           range(0, max_intx)                                                \
1452           constraint(SoftRefLRUPolicyMSPerMBConstraintFunc,AfterMemoryInit) \
1453                                                                             \
1454   product(size_t, MinHeapDeltaBytes, ScaleForWordSize(128*K),               \
1455           "The minimum change in heap space due to GC (in bytes)")          \
1456           range(0, max_uintx / 2 + 1)                                       \
1457                                                                             \
1458   product(size_t, MinMetaspaceExpansion, ScaleForWordSize(256*K),           \
1459           "The minimum expansion of Metaspace (in bytes)")                  \
1460           range(0, max_uintx)                                               \
1461                                                                             \
1462   product(uint, MaxMetaspaceFreeRatio,    70,                               \
1463           "The maximum percentage of Metaspace free after GC to avoid "     \
1464           "shrinking")                                                      \
1465           range(0, 100)                                                     \
1466           constraint(MaxMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1467                                                                             \
1468   product(uint, MinMetaspaceFreeRatio,    40,                               \
1469           "The minimum percentage of Metaspace free after GC to avoid "     \
1470           "expansion")                                                      \
1471           range(0, 99)                                                      \
1472           constraint(MinMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1473                                                                             \
1474   product(size_t, MaxMetaspaceExpansion, ScaleForWordSize(4*M),             \
1475           "The maximum expansion of Metaspace without full GC (in bytes)")  \
1476           range(0, max_uintx)                                               \
1477                                                                             \
1478   /* stack parameters */                                                    \
1479   product_pd(intx, StackYellowPages,                                        \
1480           "Number of yellow zone (recoverable overflows) pages of size "    \
1481           "4KB. If pages are bigger yellow zone is aligned up.")            \
1482           range(MIN_STACK_YELLOW_PAGES, (DEFAULT_STACK_YELLOW_PAGES+5))     \
1483                                                                             \
1484   product_pd(intx, StackRedPages,                                           \
1485           "Number of red zone (unrecoverable overflows) pages of size "     \
1486           "4KB. If pages are bigger red zone is aligned up.")               \
1487           range(MIN_STACK_RED_PAGES, (DEFAULT_STACK_RED_PAGES+2))           \
1488                                                                             \
1489   product_pd(intx, StackReservedPages,                                      \
1490           "Number of reserved zone (reserved to annotated methods) pages"   \
1491           " of size 4KB. If pages are bigger reserved zone is aligned up.") \
1492           range(MIN_STACK_RESERVED_PAGES, (DEFAULT_STACK_RESERVED_PAGES+10))\
1493                                                                             \
1494   product(bool, RestrictReservedStack, true,                                \
1495           "Restrict @ReservedStackAccess to trusted classes")               \
1496                                                                             \
1497   /* greater stack shadow pages can't generate instruction to bang stack */ \
1498   product_pd(intx, StackShadowPages,                                        \
1499           "Number of shadow zone (for overflow checking) pages of size "    \
1500           "4KB. If pages are bigger shadow zone is aligned up. "            \
1501           "This should exceed the depth of the VM and native call stack.")  \
1502           range(MIN_STACK_SHADOW_PAGES, (DEFAULT_STACK_SHADOW_PAGES+30))    \
1503                                                                             \
1504   product_pd(intx, ThreadStackSize,                                         \
1505           "Thread Stack Size (in Kbytes)")                                  \
1506           range(0, 1 * M)                                                   \
1507                                                                             \
1508   product_pd(intx, VMThreadStackSize,                                       \
1509           "Non-Java Thread Stack Size (in Kbytes)")                         \
1510           range(0, max_intx/(1 * K))                                        \
1511                                                                             \
1512   product_pd(intx, CompilerThreadStackSize,                                 \
1513           "Compiler Thread Stack Size (in Kbytes)")                         \
1514           range(0, max_intx/(1 * K))                                        \
1515                                                                             \
1516   develop_pd(size_t, JVMInvokeMethodSlack,                                  \
1517           "Stack space (bytes) required for JVM_InvokeMethod to complete")  \
1518                                                                             \
1519   /* code cache parameters                                    */            \
1520   product_pd(uintx, CodeCacheSegmentSize, EXPERIMENTAL,                     \
1521           "Code cache segment size (in bytes) - smallest unit of "          \
1522           "allocation")                                                     \
1523           range(1, 1024)                                                    \
1524           constraint(CodeCacheSegmentSizeConstraintFunc, AfterErgo)         \
1525                                                                             \
1526   product_pd(intx, CodeEntryAlignment, EXPERIMENTAL,                        \
1527           "Code entry alignment for generated code (in bytes)")             \
1528           constraint(CodeEntryAlignmentConstraintFunc, AfterErgo)           \
1529                                                                             \
1530   product_pd(intx, OptoLoopAlignment,                                       \
1531           "Align inner loops to zero relative to this modulus")             \
1532           range(1, 128)                                                     \
1533           constraint(OptoLoopAlignmentConstraintFunc, AfterErgo)            \
1534                                                                             \
1535   product_pd(uintx, InitialCodeCacheSize,                                   \
1536           "Initial code cache size (in bytes)")                             \
1537           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1538                                                                             \
1539   develop_pd(uintx, CodeCacheMinimumUseSpace,                               \
1540           "Minimum code cache size (in bytes) required to start VM.")       \
1541           range(0, max_uintx)                                               \
1542                                                                             \
1543   product(bool, SegmentedCodeCache, false,                                  \
1544           "Use a segmented code cache")                                     \
1545                                                                             \
1546   product_pd(uintx, ReservedCodeCacheSize,                                  \
1547           "Reserved code cache size (in bytes) - maximum code cache size")  \
1548           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1549                                                                             \
1550   product_pd(uintx, NonProfiledCodeHeapSize,                                \
1551           "Size of code heap with non-profiled methods (in bytes)")         \
1552           range(0, max_uintx)                                               \
1553                                                                             \
1554   product_pd(uintx, ProfiledCodeHeapSize,                                   \
1555           "Size of code heap with profiled methods (in bytes)")             \
1556           range(0, max_uintx)                                               \
1557                                                                             \
1558   product_pd(uintx, NonNMethodCodeHeapSize,                                 \
1559           "Size of code heap with non-nmethods (in bytes)")                 \
1560           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1561                                                                             \
1562   product_pd(uintx, CodeCacheExpansionSize,                                 \
1563           "Code cache expansion size (in bytes)")                           \
1564           range(32*K, max_uintx)                                            \
1565                                                                             \
1566   product_pd(uintx, CodeCacheMinBlockLength, DIAGNOSTIC,                    \
1567           "Minimum number of segments in a code cache block")               \
1568           range(1, 100)                                                     \
1569                                                                             \
1570   develop(bool, ExitOnFullCodeCache, false,                                 \
1571           "Exit the VM if we fill the code cache")                          \
1572                                                                             \
1573   product(bool, UseCodeCacheFlushing, true,                                 \
1574           "Remove cold/old nmethods from the code cache")                   \
1575                                                                             \
1576   product(double, SweeperThreshold, 15.0,                                   \
1577           "Threshold when a code cache unloading GC is invoked."            \
1578           "Value is percentage of ReservedCodeCacheSize.")                  \
1579           range(0.0, 100.0)                                                 \
1580                                                                             \
1581   product(uintx, StartAggressiveSweepingAt, 10,                             \
1582           "Start aggressive sweeping if X[%] of the code cache is free."    \
1583           "Segmented code cache: X[%] of the non-profiled heap."            \
1584           "Non-segmented code cache: X[%] of the total code cache")         \
1585           range(0, 100)                                                     \
1586                                                                             \
1587   /* interpreter debugging */                                               \
1588   develop(intx, BinarySwitchThreshold, 5,                                   \
1589           "Minimal number of lookupswitch entries for rewriting to binary " \
1590           "switch")                                                         \
1591                                                                             \
1592   develop(uintx, StopInterpreterAt, 0,                                      \
1593           "Stop interpreter execution at specified bytecode number")        \
1594                                                                             \
1595   develop(uintx, TraceBytecodesAt, 0,                                       \
1596           "Trace bytecodes starting with specified bytecode number")        \
1597                                                                             \
1598   develop(uintx, TraceBytecodesStopAt, 0,                                   \
1599           "Stop bytecode tracing at the specified bytecode number")         \
1600                                                                             \
1601   /* Priorities */                                                          \
1602   product_pd(bool, UseThreadPriorities,  "Use native thread priorities")    \
1603                                                                             \
1604   product(int, ThreadPriorityPolicy, 0,                                     \
1605           "0 : Normal.                                                     "\
1606           "    VM chooses priorities that are appropriate for normal       "\
1607           "    applications.                                               "\
1608           "    On Windows applications are allowed to use higher native    "\
1609           "    priorities. However, with ThreadPriorityPolicy=0, VM will   "\
1610           "    not use the highest possible native priority,               "\
1611           "    THREAD_PRIORITY_TIME_CRITICAL, as it may interfere with     "\
1612           "    system threads. On Linux thread priorities are ignored      "\
1613           "    because the OS does not support static priority in          "\
1614           "    SCHED_OTHER scheduling class which is the only choice for   "\
1615           "    non-root, non-realtime applications.                        "\
1616           "1 : Aggressive.                                                 "\
1617           "    Java thread priorities map over to the entire range of      "\
1618           "    native thread priorities. Higher Java thread priorities map "\
1619           "    to higher native thread priorities. This policy should be   "\
1620           "    used with care, as sometimes it can cause performance       "\
1621           "    degradation in the application and/or the entire system. On "\
1622           "    Linux/BSD/macOS this policy requires root privilege or an   "\
1623           "    extended capability.")                                       \
1624           range(0, 1)                                                       \
1625                                                                             \
1626   product(bool, ThreadPriorityVerbose, false,                               \
1627           "Print priority changes")                                         \
1628                                                                             \
1629   product(int, CompilerThreadPriority, -1,                                  \
1630           "The native priority at which compiler threads should run "       \
1631           "(-1 means no change)")                                           \
1632           range(min_jint, max_jint)                                         \
1633                                                                             \
1634   product(int, VMThreadPriority, -1,                                        \
1635           "The native priority at which the VM thread should run "          \
1636           "(-1 means no change)")                                           \
1637           range(min_jint, max_jint)                                         \
1638                                                                             \
1639   product(int, JavaPriority1_To_OSPriority, -1,                             \
1640           "Map Java priorities to OS priorities")                           \
1641           range(min_jint, max_jint)                                         \
1642                                                                             \
1643   product(int, JavaPriority2_To_OSPriority, -1,                             \
1644           "Map Java priorities to OS priorities")                           \
1645           range(min_jint, max_jint)                                         \
1646                                                                             \
1647   product(int, JavaPriority3_To_OSPriority, -1,                             \
1648           "Map Java priorities to OS priorities")                           \
1649           range(min_jint, max_jint)                                         \
1650                                                                             \
1651   product(int, JavaPriority4_To_OSPriority, -1,                             \
1652           "Map Java priorities to OS priorities")                           \
1653           range(min_jint, max_jint)                                         \
1654                                                                             \
1655   product(int, JavaPriority5_To_OSPriority, -1,                             \
1656           "Map Java priorities to OS priorities")                           \
1657           range(min_jint, max_jint)                                         \
1658                                                                             \
1659   product(int, JavaPriority6_To_OSPriority, -1,                             \
1660           "Map Java priorities to OS priorities")                           \
1661           range(min_jint, max_jint)                                         \
1662                                                                             \
1663   product(int, JavaPriority7_To_OSPriority, -1,                             \
1664           "Map Java priorities to OS priorities")                           \
1665           range(min_jint, max_jint)                                         \
1666                                                                             \
1667   product(int, JavaPriority8_To_OSPriority, -1,                             \
1668           "Map Java priorities to OS priorities")                           \
1669           range(min_jint, max_jint)                                         \
1670                                                                             \
1671   product(int, JavaPriority9_To_OSPriority, -1,                             \
1672           "Map Java priorities to OS priorities")                           \
1673           range(min_jint, max_jint)                                         \
1674                                                                             \
1675   product(int, JavaPriority10_To_OSPriority,-1,                             \
1676           "Map Java priorities to OS priorities")                           \
1677           range(min_jint, max_jint)                                         \
1678                                                                             \
1679   product(bool, UseCriticalJavaThreadPriority, false, EXPERIMENTAL,         \
1680           "Java thread priority 10 maps to critical scheduling priority")   \
1681                                                                             \
1682   product(bool, UseCriticalCompilerThreadPriority, false, EXPERIMENTAL,     \
1683           "Compiler thread(s) run at critical scheduling priority")         \
1684                                                                             \
1685   develop(intx, NewCodeParameter,      0,                                   \
1686           "Testing Only: Create a dedicated integer parameter before "      \
1687           "putback")                                                        \
1688                                                                             \
1689   /* new oopmap storage allocation */                                       \
1690   develop(intx, MinOopMapAllocation,     8,                                 \
1691           "Minimum number of OopMap entries in an OopMapSet")               \
1692                                                                             \
1693   /* recompilation */                                                       \
1694   product_pd(intx, CompileThreshold,                                        \
1695           "number of interpreted method invocations before (re-)compiling") \
1696           constraint(CompileThresholdConstraintFunc, AfterErgo)             \
1697                                                                             \
1698   product_pd(bool, TieredCompilation,                                       \
1699           "Enable tiered compilation")                                      \
1700                                                                             \
1701   /* Properties for Java libraries  */                                      \
1702                                                                             \
1703   product(uint64_t, MaxDirectMemorySize, 0,                                 \
1704           "Maximum total size of NIO direct-buffer allocations. "           \
1705           "Ignored if not explicitly set.")                                 \
1706           range(0, max_jlong)                                               \
1707                                                                             \
1708   /* Flags used for temporary code during development  */                   \
1709                                                                             \
1710   product(bool, UseNewCode, false, DIAGNOSTIC,                              \
1711           "Testing Only: Use the new version while testing")                \
1712                                                                             \
1713   product(bool, UseNewCode2, false, DIAGNOSTIC,                             \
1714           "Testing Only: Use the new version while testing")                \
1715                                                                             \
1716   product(bool, UseNewCode3, false, DIAGNOSTIC,                             \
1717           "Testing Only: Use the new version while testing")                \
1718                                                                             \
1719   develop(bool, UseDebuggerErgo, false,                                     \
1720           "Debugging Only: Adjust the VM to be more debugger-friendly. "    \
1721           "Turns on the other UseDebuggerErgo* flags")                      \
1722                                                                             \
1723   develop(bool, UseDebuggerErgo1, false,                                    \
1724           "Debugging Only: Enable workarounds for debugger induced "        \
1725           "os::processor_id() >= os::processor_count() problems")           \
1726                                                                             \
1727   develop(bool, UseDebuggerErgo2, false,                                    \
1728           "Debugging Only: Limit the number of spawned JVM threads")        \
1729                                                                             \
1730   develop(bool, EnableJVMTIStackDepthAsserts, true,                         \
1731           "Enable JVMTI asserts related to stack depth checks")             \
1732                                                                             \
1733   /* flags for performance data collection */                               \
1734                                                                             \
1735   product(bool, UsePerfData, true,                                          \
1736           "Flag to disable jvmstat instrumentation for performance testing "\
1737           "and problem isolation purposes")                                 \
1738                                                                             \
1739   product(bool, PerfDataSaveToFile, false,                                  \
1740           "Save PerfData memory to hsperfdata_<pid> file on exit")          \
1741                                                                             \
1742   product(ccstr, PerfDataSaveFile, nullptr,                                 \
1743           "Save PerfData memory to the specified absolute pathname. "       \
1744           "The string %p in the file name (if present) "                    \
1745           "will be replaced by pid")                                        \
1746                                                                             \
1747   product(int, PerfDataSamplingInterval, 50,                                \
1748           "Data sampling interval (in milliseconds)")                       \
1749           range(PeriodicTask::min_interval, max_jint)                       \
1750           constraint(PerfDataSamplingIntervalFunc, AfterErgo)               \
1751                                                                             \
1752   product(bool, PerfDisableSharedMem, false,                                \
1753           "Store performance data in standard memory")                      \
1754                                                                             \
1755   product(int, PerfDataMemorySize, 32*K,                                    \
1756           "Size of performance data memory region. Will be rounded "        \
1757           "up to a multiple of the native os page size.")                   \
1758           range(128, 32*64*K)                                               \
1759                                                                             \
1760   product(int, PerfMaxStringConstLength, 1024,                              \
1761           "Maximum PerfStringConstant string length before truncation")     \
1762           range(32, 32*K)                                                   \
1763                                                                             \
1764   product(bool, PerfAllowAtExitRegistration, false,                         \
1765           "Allow registration of atexit() methods")                         \
1766                                                                             \
1767   product(bool, PerfBypassFileSystemCheck, false,                           \
1768           "Bypass Win32 file system criteria checks (Windows Only)")        \
1769                                                                             \
1770   product(int, UnguardOnExecutionViolation, 0,                              \
1771           "Unguard page and retry on no-execute fault (Win32 only) "        \
1772           "0=off, 1=conservative, 2=aggressive")                            \
1773           range(0, 2)                                                       \
1774                                                                             \
1775   /* Serviceability Support */                                              \
1776                                                                             \
1777   product(bool, ManagementServer, false,                                    \
1778           "Create JMX Management Server")                                   \
1779                                                                             \
1780   product(bool, DisableAttachMechanism, false,                              \
1781           "Disable mechanism that allows tools to attach to this VM")       \
1782                                                                             \
1783   product(bool, StartAttachListener, false,                                 \
1784           "Always start Attach Listener at VM startup")                     \
1785                                                                             \
1786   product(bool, EnableDynamicAgentLoading, true,                            \
1787           "Allow tools to load agents with the attach mechanism")           \
1788                                                                             \
1789   product(bool, PrintConcurrentLocks, false, MANAGEABLE,                    \
1790           "Print java.util.concurrent locks in thread dump")                \
1791                                                                             \
1792   product(bool, PrintMethodHandleStubs, false, DIAGNOSTIC,                  \
1793           "Print generated stub code for method handles")                   \
1794                                                                             \
1795   product(bool, VerifyMethodHandles, trueInDebug, DIAGNOSTIC,               \
1796           "perform extra checks when constructing method handles")          \
1797                                                                             \
1798   product(bool, IgnoreAssertUnsetFields, false, DIAGNOSTIC,                           \
1799           "Ignore assert_unset_fields")                                     \
1800                                                                             \
1801   product(bool, ShowHiddenFrames, false, DIAGNOSTIC,                        \
1802           "show method handle implementation frames (usually hidden)")      \
1803                                                                             \
1804   product(bool, ShowCarrierFrames, false, DIAGNOSTIC,                       \
1805           "show virtual threads' carrier frames in exceptions")             \
1806                                                                             \
1807   product(bool, TrustFinalNonStaticFields, false, EXPERIMENTAL,             \
1808           "trust final non-static declarations for constant folding")       \
1809                                                                             \
1810   product(bool, FoldStableValues, true, DIAGNOSTIC,                         \
1811           "Optimize loads from stable fields (marked w/ @Stable)")          \
1812                                                                             \
1813   product(int, UseBootstrapCallInfo, 1, DIAGNOSTIC,                         \
1814           "0: when resolving InDy or ConDy, force all BSM arguments to be " \
1815           "resolved before the bootstrap method is called; 1: when a BSM "  \
1816           "that may accept a BootstrapCallInfo is detected, use that API "  \
1817           "to pass BSM arguments, which allows the BSM to delay their "     \
1818           "resolution; 2+: stress test the BCI API by calling more BSMs "   \
1819           "via that API, instead of with the eagerly-resolved array.")      \
1820                                                                             \
1821   product(bool, PauseAtStartup,      false, DIAGNOSTIC,                     \
1822           "Causes the VM to pause at startup time and wait for the pause "  \
1823           "file to be removed (default: ./vm.paused.<pid>)")                \
1824                                                                             \
1825   product(ccstr, PauseAtStartupFile, nullptr, DIAGNOSTIC,                      \
1826           "The file to create and for whose removal to await when pausing " \
1827           "at startup. (default: ./vm.paused.<pid>)")                       \
1828                                                                             \
1829   product(bool, PauseAtExit, false, DIAGNOSTIC,                             \
1830           "Pause and wait for keypress on exit if a debugger is attached")  \
1831                                                                             \
1832   product(bool, DTraceMethodProbes, false,                                  \
1833           "Enable dtrace tool probes for method-entry and method-exit")     \
1834                                                                             \
1835   product(bool, DTraceAllocProbes, false,                                   \
1836           "Enable dtrace tool probes for object allocation")                \
1837                                                                             \
1838   product(bool, DTraceMonitorProbes, false,                                 \
1839           "Enable dtrace tool probes for monitor events")                   \
1840                                                                             \
1841   product(bool, RelaxAccessControlCheck, false,                             \
1842           "Relax the access control checks in the verifier")                \
1843                                                                             \
1844   product(uintx, StringTableSize, defaultStringTableSize,                   \
1845           "Number of buckets in the interned String table "                 \
1846           "(will be rounded to nearest higher power of 2)")                 \
1847           range(minimumStringTableSize, 16777216ul /* 2^24 */)              \
1848                                                                             \
1849   product(uintx, SymbolTableSize, defaultSymbolTableSize, EXPERIMENTAL,     \
1850           "Number of buckets in the JVM internal Symbol table")             \
1851           range(minimumSymbolTableSize, 16777216ul /* 2^24 */)              \
1852                                                                             \
1853   product(bool, UseStringDeduplication, false,                              \
1854           "Use string deduplication")                                       \
1855                                                                             \
1856   product(uint, StringDeduplicationAgeThreshold, 3,                         \
1857           "A string must reach this age (or be promoted to an old region) " \
1858           "to be considered for deduplication")                             \
1859           range(1, markWord::max_age)                                       \
1860                                                                             \
1861   product(size_t, StringDeduplicationInitialTableSize, 500, EXPERIMENTAL,   \
1862           "Approximate initial number of buckets in the table")             \
1863           range(1, 1 * G)                                                   \
1864                                                                             \
1865   product(double, StringDeduplicationGrowTableLoad, 14.0, EXPERIMENTAL,     \
1866           "Entries per bucket above which the table should be expanded")    \
1867           range(0.1, 1000.0)                                                \
1868                                                                             \
1869   product(double, StringDeduplicationShrinkTableLoad, 1.0, EXPERIMENTAL,    \
1870           "Entries per bucket below which the table should be shrunk")      \
1871           range(0.01, 100.0)                                                \
1872                                                                             \
1873   product(double, StringDeduplicationTargetTableLoad, 7.0, EXPERIMENTAL,    \
1874           "Desired entries per bucket when resizing the table")             \
1875           range(0.01, 1000.0)                                               \
1876                                                                             \
1877   product(size_t, StringDeduplicationCleanupDeadMinimum, 100, EXPERIMENTAL, \
1878           "Minimum number of dead table entries for cleaning the table")    \
1879                                                                             \
1880   product(int, StringDeduplicationCleanupDeadPercent, 5, EXPERIMENTAL,      \
1881           "Minimum percentage of dead table entries for cleaning the table") \
1882           range(1, 100)                                                     \
1883                                                                             \
1884   product(bool, StringDeduplicationResizeALot, false, DIAGNOSTIC,           \
1885           "Force more frequent table resizing")                             \
1886                                                                             \
1887   product(uint64_t, StringDeduplicationHashSeed, 0, DIAGNOSTIC,             \
1888           "Seed for the table hashing function; 0 requests computed seed")  \
1889                                                                             \
1890   product(bool, WhiteBoxAPI, false, DIAGNOSTIC,                             \
1891           "Enable internal testing APIs")                                   \
1892                                                                             \
1893   product(bool, AlwaysAtomicAccesses, false, EXPERIMENTAL,                  \
1894           "Accesses to all variables should always be atomic")              \
1895                                                                             \
1896   product(bool, UseUnalignedAccesses, false, DIAGNOSTIC,                    \
1897           "Use unaligned memory accesses in Unsafe")                        \
1898                                                                             \
1899   product_pd(bool, PreserveFramePointer,                                    \
1900              "Use the FP register for holding the frame pointer "           \
1901              "and not as a general purpose register.")                      \
1902                                                                             \
1903   product(size_t, AsyncLogBufferSize, 2*M,                                  \
1904           "Memory budget (in bytes) for the buffer of Asynchronous "        \
1905           "Logging (-Xlog:async).")                                         \
1906           range(DEBUG_ONLY(192) NOT_DEBUG(100*K), 50*M)                     \
1907                                                                             \
1908   product(bool, CheckIntrinsics, true, DIAGNOSTIC,                          \
1909              "When a class C is loaded, check that "                        \
1910              "(1) all intrinsics defined by the VM for class C are present "\
1911              "in the loaded class file and are marked with the "            \
1912              "@IntrinsicCandidate annotation, that "                        \
1913              "(2) there is an intrinsic registered for all loaded methods " \
1914              "that are annotated with the @IntrinsicCandidate annotation, " \
1915              "and that "                                                    \
1916              "(3) no orphan methods exist for class C (i.e., methods for "  \
1917              "which the VM declares an intrinsic but that are not declared "\
1918              "in the loaded class C. "                                      \
1919              "Check (3) is available only in debug builds.")                \
1920                                                                             \
1921   product_pd(intx, InitArrayShortSize, DIAGNOSTIC,                          \
1922           "Threshold small size (in bytes) for clearing arrays. "           \
1923           "Anything this size or smaller may get converted to discrete "    \
1924           "scalar stores.")                                                 \
1925           range(0, max_intx)                                                \
1926           constraint(InitArrayShortSizeConstraintFunc, AfterErgo)           \
1927                                                                             \
1928   product(ccstr, AllocateHeapAt, nullptr,                                   \
1929           "Path to the directory where a temporary file will be created "   \
1930           "to use as the backing store for Java Heap.")                     \
1931                                                                             \
1932   product_pd(bool, VMContinuations, EXPERIMENTAL,                           \
1933           "Enable VM continuations support")                                \
1934                                                                             \
1935   develop(bool, LoomDeoptAfterThaw, false,                                  \
1936           "Deopt stack after thaw")                                         \
1937                                                                             \
1938   develop(bool, LoomVerifyAfterThaw, false,                                 \
1939           "Verify stack after thaw")                                        \
1940                                                                             \
1941   develop(bool, VerifyContinuations, false,                                 \
1942           "Verify continuation consistency")                                \
1943                                                                             \
1944   develop(bool, UseContinuationFastPath, true,                              \
1945           "Use fast-path frame walking in continuations")                   \
1946                                                                             \
1947   develop(int, VerifyMetaspaceInterval, DEBUG_ONLY(500) NOT_DEBUG(0),       \
1948                "Run periodic metaspace verifications (0 - none, "           \
1949                "1 - always, >1 every nth interval)")                        \
1950                                                                             \
1951   product(bool, ShowRegistersOnAssert, true, DIAGNOSTIC,                    \
1952           "On internal errors, include registers in error report.")         \
1953                                                                             \
1954   product(bool, UseSwitchProfiling, true, DIAGNOSTIC,                       \
1955           "leverage profiling for table/lookup switch")                     \
1956                                                                             \
1957   develop(bool, TraceMemoryWriteback, false,                                \
1958           "Trace memory writeback operations")                              \
1959                                                                             \
1960   JFR_ONLY(product(bool, FlightRecorder, false,                             \
1961           "(Deprecated) Enable Flight Recorder"))                           \
1962                                                                             \
1963   JFR_ONLY(product(ccstr, FlightRecorderOptions, nullptr,                   \
1964           "Flight Recorder options"))                                       \
1965                                                                             \
1966   JFR_ONLY(product(ccstr, StartFlightRecording, nullptr,                    \
1967           "Start flight recording with options"))                           \
1968                                                                             \
1969   product(bool, UseFastUnorderedTimeStamps, false, EXPERIMENTAL,            \
1970           "Use platform unstable time where supported for timestamps only") \
1971                                                                             \
1972   product(bool, EnableValhalla, true,                                       \
1973           "Enable experimental Valhalla features")                          \
1974                                                                             \
1975   product_pd(bool, InlineTypePassFieldsAsArgs,                              \
1976           "Pass each inline type field as an argument at calls")            \
1977                                                                             \
1978   product_pd(bool, InlineTypeReturnedAsFields,                              \
1979           "Return fields instead of an inline type reference")              \
1980                                                                             \
1981   develop(bool, StressCallingConvention, false,                             \
1982           "Stress the scalarized calling convention.")                      \
1983                                                                             \
1984   product(ccstrlist, ForceNonTearable, "", DIAGNOSTIC,                      \
1985           "List of inline classes which are forced to be atomic "           \
1986           "(whitespace and commas separate names, "                         \
1987           "and leading and trailing stars '*' are wildcards)")              \
1988                                                                             \
1989   product(bool, DeoptimizeNMethodBarriersALot, false, DIAGNOSTIC,           \
1990                 "Make nmethod barriers deoptimise a lot.")                  \
1991                                                                             \
1992   develop(bool, VerifyCrossModifyFence,                                     \
1993           false AARCH64_ONLY(DEBUG_ONLY(||true)),                           \
1994              "Mark all threads after a safepoint, and clear on a modify "   \
1995              "fence. Add cleanliness checks.")                              \
1996                                                                             \
1997   product(int, LockingMode, LM_LIGHTWEIGHT,                                 \
1998           "(Deprecated) Select locking mode: "                              \
1999           "0: (Deprecated) monitors only (LM_MONITOR), "                    \
2000           "1: (Deprecated) monitors & legacy stack-locking (LM_LEGACY), "   \
2001           "2: monitors & new lightweight locking (LM_LIGHTWEIGHT, default)") \
2002           range(0, 2)                                                       \
2003                                                                             \
2004   product(bool, UseObjectMonitorTable, false, DIAGNOSTIC,                   \
2005           "With Lightweight Locking mode, use a table to record inflated "  \
2006           "monitors rather than the first word of the object.")             \
2007                                                                             \
2008   product(int, LightweightFastLockingSpins, 13, DIAGNOSTIC,                 \
2009           "Specifies the number of times lightweight fast locking will "    \
2010           "attempt to CAS the markWord before inflating. Between each "     \
2011           "CAS it will spin for exponentially more time, resulting in "     \
2012           "a total number of spins on the order of O(2^value)")             \
2013           range(1, 30)                                                      \
2014                                                                             \
2015   product(uint, TrimNativeHeapInterval, 0,                                  \
2016           "Interval, in ms, at which the JVM will trim the native heap if " \
2017           "the platform supports that. Lower values will reclaim memory "   \
2018           "more eagerly at the cost of higher overhead. A value of 0 "      \
2019           "(default) disables native heap trimming.")                       \
2020           range(0, UINT_MAX)                                                \
2021                                                                             \
2022   develop(bool, SimulateFullAddressSpace, false,                            \
2023           "Simulates a very populated, fragmented address space; no "       \
2024           "targeted reservations will succeed.")                            \
2025                                                                             \
2026   product(bool, ProfileExceptionHandlers, true,                             \
2027           "Profile exception handlers")                                     \
2028                                                                             \
2029   product(bool, AlwaysRecordEvolDependencies, true, EXPERIMENTAL,           \
2030                 "Unconditionally record nmethod dependencies on class "     \
2031                 "rewriting/transformation independently of the JVMTI "      \
2032                 "can_{retransform/redefine}_classes capabilities.")         \
2033                                                                             \
2034   product(bool, UseSecondarySupersCache, true, DIAGNOSTIC,                  \
2035                 "Use secondary supers cache during subtype checks.")        \
2036                                                                             \
2037   product(bool, UseSecondarySupersTable, false, DIAGNOSTIC,                 \
2038                 "Use hash table to lookup secondary supers.")               \
2039                                                                             \
2040   product(bool, VerifySecondarySupers, false, DIAGNOSTIC,                   \
2041           "Check that linear and hashed secondary lookups return the same result.") \
2042                                                                             \
2043   product(bool, StressSecondarySupers, false, DIAGNOSTIC,                   \
2044           "Use a terrible hash function in order to generate many collisions.") \
2045                                                                             \
2046   product(bool, UseThreadsLockThrottleLock, true, DIAGNOSTIC,               \
2047           "Use an extra lock during Thread start and exit to alleviate"     \
2048           "contention on Threads_lock.")                                    \
2049 
2050 // end of RUNTIME_FLAGS
2051 
2052 DECLARE_FLAGS(LP64_RUNTIME_FLAGS)
2053 DECLARE_ARCH_FLAGS(ARCH_FLAGS)
2054 DECLARE_FLAGS(RUNTIME_FLAGS)
2055 DECLARE_FLAGS(RUNTIME_OS_FLAGS)
2056 
2057 #endif // SHARE_RUNTIME_GLOBALS_HPP