1 /*
   2  * Copyright (c) 1997, 2024, 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           "Use 32-bit class pointers in 64-bit VM. "                        \
 129           "lp64_product means flag is always constant in 32 bit VM")        \
 130                                                                             \
 131   product(int, ObjectAlignmentInBytes, 8,                                   \
 132           "Default object alignment in bytes, 8 is minimum")                \
 133           range(8, 256)                                                     \
 134           constraint(ObjectAlignmentInBytesConstraintFunc, AtParse)
 135 
 136 #else
 137 // !_LP64
 138 
 139 #define LP64_RUNTIME_FLAGS(develop,                                         \
 140                            develop_pd,                                      \
 141                            product,                                         \
 142                            product_pd,                                      \
 143                            range,                                           \
 144                            constraint)
 145 const bool UseCompressedOops = false;
 146 const bool UseCompressedClassPointers = false;
 147 const int ObjectAlignmentInBytes = 8;
 148 
 149 #endif // _LP64
 150 
 151 #define RUNTIME_FLAGS(develop,                                              \
 152                       develop_pd,                                           \
 153                       product,                                              \
 154                       product_pd,                                           \
 155                       range,                                                \
 156                       constraint)                                           \
 157                                                                             \
 158   develop(bool, CheckCompressedOops, true,                                  \
 159           "Generate checks in encoding/decoding code in debug VM")          \
 160                                                                             \
 161   product(uintx, HeapSearchSteps, 3 PPC64_ONLY(+17),                        \
 162           "Heap allocation steps through preferred address regions to find" \
 163           " where it can allocate the heap. Number of steps to take per "   \
 164           "region.")                                                        \
 165           range(1, max_uintx)                                               \
 166                                                                             \
 167   product(uint, HandshakeTimeout, 0, DIAGNOSTIC,                            \
 168           "If nonzero set a timeout in milliseconds for handshakes")        \
 169                                                                             \
 170   product(bool, AlwaysSafeConstructors, false, EXPERIMENTAL,                \
 171           "Force safe construction, as if all fields are final.")           \
 172                                                                             \
 173   product(bool, UnlockDiagnosticVMOptions, trueInDebug, DIAGNOSTIC,         \
 174           "Enable normal processing of flags relating to field diagnostics")\
 175                                                                             \
 176   product(bool, UnlockExperimentalVMOptions, false, EXPERIMENTAL,           \
 177           "Enable normal processing of flags relating to experimental "     \
 178           "features")                                                       \
 179                                                                             \
 180   product(bool, JavaMonitorsInStackTrace, true,                             \
 181           "Print information about Java monitor locks when the stacks are " \
 182           "dumped")                                                         \
 183                                                                             \
 184   product_pd(bool, UseLargePages,                                           \
 185           "Use large page memory")                                          \
 186                                                                             \
 187   product_pd(bool, UseLargePagesIndividualAllocation,                       \
 188           "Allocate large pages individually for better affinity")          \
 189                                                                             \
 190   develop(bool, LargePagesIndividualAllocationInjectError, false,           \
 191           "Fail large pages individual allocation")                         \
 192                                                                             \
 193   product(bool, UseNUMA, false,                                             \
 194           "Use NUMA if available")                                          \
 195                                                                             \
 196   product(bool, UseNUMAInterleaving, false,                                 \
 197           "Interleave memory across NUMA nodes if available")               \
 198                                                                             \
 199   product(size_t, NUMAInterleaveGranularity, 2*M,                           \
 200           "Granularity to use for NUMA interleaving on Windows OS")         \
 201           constraint(NUMAInterleaveGranularityConstraintFunc, AtParse)      \
 202                                                                             \
 203   product(uintx, NUMAChunkResizeWeight, 20,                                 \
 204           "Percentage (0-100) used to weight the current sample when "      \
 205           "computing exponentially decaying average for "                   \
 206           "AdaptiveNUMAChunkSizing")                                        \
 207           range(0, 100)                                                     \
 208                                                                             \
 209   product(size_t, NUMASpaceResizeRate, 1*G,                                 \
 210           "Do not reallocate more than this amount per collection")         \
 211           range(0, max_uintx)                                               \
 212                                                                             \
 213   product(bool, UseAdaptiveNUMAChunkSizing, true,                           \
 214           "Enable adaptive chunk sizing for NUMA")                          \
 215                                                                             \
 216   product(bool, NUMAStats, false,                                           \
 217           "Print NUMA stats in detailed heap information")                  \
 218                                                                             \
 219   product(bool, UseAES, false,                                              \
 220           "Control whether AES instructions are used when available")       \
 221                                                                             \
 222   product(bool, UseFMA, false,                                              \
 223           "Control whether FMA instructions are used when available")       \
 224                                                                             \
 225   product(bool, UseSHA, false,                                              \
 226           "Control whether SHA instructions are used when available")       \
 227                                                                             \
 228   product(bool, UseGHASHIntrinsics, false, DIAGNOSTIC,                      \
 229           "Use intrinsics for GHASH versions of crypto")                    \
 230                                                                             \
 231   product(bool, UseBASE64Intrinsics, false,                                 \
 232           "Use intrinsics for java.util.Base64")                            \
 233                                                                             \
 234   product(bool, UsePoly1305Intrinsics, false, DIAGNOSTIC,                   \
 235           "Use intrinsics for sun.security.util.math.intpoly")              \
 236   product(bool, UseIntPolyIntrinsics, false, DIAGNOSTIC,                   \
 237           "Use intrinsics for sun.security.util.math.intpoly.MontgomeryIntegerPolynomialP256") \
 238                                                                             \
 239   product(size_t, LargePageSizeInBytes, 0,                                  \
 240           "Maximum large page size used (0 will use the default large "     \
 241           "page size for the environment as the maximum)")                  \
 242           range(0, max_uintx)                                               \
 243                                                                             \
 244   product(size_t, LargePageHeapSizeThreshold, 128*M,                        \
 245           "Use large pages if maximum heap is at least this big")           \
 246           range(0, max_uintx)                                               \
 247                                                                             \
 248   product(bool, ForceTimeHighResolution, false,                             \
 249           "Using high time resolution (for Win32 only)")                    \
 250                                                                             \
 251   develop(bool, TracePcPatching, false,                                     \
 252           "Trace usage of frame::patch_pc")                                 \
 253                                                                             \
 254   develop(bool, TraceRelocator, false,                                      \
 255           "Trace the bytecode relocator")                                   \
 256                                                                             \
 257                                                                             \
 258   product(bool, SafepointALot, false, DIAGNOSTIC,                           \
 259           "Generate a lot of safepoints. This works with "                  \
 260           "GuaranteedSafepointInterval")                                    \
 261                                                                             \
 262   product(bool, HandshakeALot, false, DIAGNOSTIC,                           \
 263           "Generate a lot of handshakes. This works with "                  \
 264           "GuaranteedSafepointInterval")                                    \
 265                                                                             \
 266   product_pd(bool, BackgroundCompilation,                                   \
 267           "A thread requesting compilation is not blocked during "          \
 268           "compilation")                                                    \
 269                                                                             \
 270   product(bool, MethodFlushing, true,                                       \
 271           "Reclamation of compiled methods")                                \
 272                                                                             \
 273   develop(bool, VerifyStack, false,                                         \
 274           "Verify stack of each thread when it is entering a runtime call") \
 275                                                                             \
 276   product(bool, ForceUnreachable, false, DIAGNOSTIC,                        \
 277           "Make all non code cache addresses to be unreachable by "         \
 278           "forcing use of 64bit literal fixups")                            \
 279                                                                             \
 280   develop(bool, TraceDerivedPointers, false,                                \
 281           "Trace traversal of derived pointers on stack")                   \
 282                                                                             \
 283   develop(bool, TraceCodeBlobStacks, false,                                 \
 284           "Trace stack-walk of codeblobs")                                  \
 285                                                                             \
 286   develop(bool, PrintRewrites, false,                                       \
 287           "Print methods that are being rewritten")                         \
 288                                                                             \
 289   product(bool, UseInlineCaches, true,                                      \
 290           "Use Inline Caches for virtual calls ")                           \
 291                                                                             \
 292   product(bool, InlineArrayCopy, true, DIAGNOSTIC,                          \
 293           "Inline arraycopy native that is known to be part of "            \
 294           "base library DLL")                                               \
 295                                                                             \
 296   product(bool, InlineObjectHash, true, DIAGNOSTIC,                         \
 297           "Inline Object::hashCode() native that is known to be part "      \
 298           "of base library DLL")                                            \
 299                                                                             \
 300   product(bool, InlineNatives, true, DIAGNOSTIC,                            \
 301           "Inline natives that are known to be part of base library DLL")   \
 302                                                                             \
 303   product(bool, InlineMathNatives, true, DIAGNOSTIC,                        \
 304           "Inline SinD, CosD, etc.")                                        \
 305                                                                             \
 306   product(bool, InlineClassNatives, true, DIAGNOSTIC,                       \
 307           "Inline Class.isInstance, etc")                                   \
 308                                                                             \
 309   product(bool, InlineThreadNatives, true, DIAGNOSTIC,                      \
 310           "Inline Thread.currentThread, etc")                               \
 311                                                                             \
 312   product(bool, InlineUnsafeOps, true, DIAGNOSTIC,                          \
 313           "Inline memory ops (native methods) from Unsafe")                 \
 314                                                                             \
 315   product(bool, UseAESIntrinsics, false, DIAGNOSTIC,                        \
 316           "Use intrinsics for AES versions of crypto")                      \
 317                                                                             \
 318   product(bool, UseAESCTRIntrinsics, false, DIAGNOSTIC,                     \
 319           "Use intrinsics for the paralleled version of AES/CTR crypto")    \
 320                                                                             \
 321   product(bool, UseChaCha20Intrinsics, false, DIAGNOSTIC,                   \
 322           "Use intrinsics for the vectorized version of ChaCha20")          \
 323                                                                             \
 324   product(bool, UseMD5Intrinsics, false, DIAGNOSTIC,                        \
 325           "Use intrinsics for MD5 crypto hash function")                    \
 326                                                                             \
 327   product(bool, UseSHA1Intrinsics, false, DIAGNOSTIC,                       \
 328           "Use intrinsics for SHA-1 crypto hash function. "                 \
 329           "Requires that UseSHA is enabled.")                               \
 330                                                                             \
 331   product(bool, UseSHA256Intrinsics, false, DIAGNOSTIC,                     \
 332           "Use intrinsics for SHA-224 and SHA-256 crypto hash functions. "  \
 333           "Requires that UseSHA is enabled.")                               \
 334                                                                             \
 335   product(bool, UseSHA512Intrinsics, false, DIAGNOSTIC,                     \
 336           "Use intrinsics for SHA-384 and SHA-512 crypto hash functions. "  \
 337           "Requires that UseSHA is enabled.")                               \
 338                                                                             \
 339   product(bool, UseSHA3Intrinsics, false, DIAGNOSTIC,                       \
 340           "Use intrinsics for SHA3 crypto hash function. "                  \
 341           "Requires that UseSHA is enabled.")                               \
 342                                                                             \
 343   product(bool, UseCRC32Intrinsics, false, DIAGNOSTIC,                      \
 344           "use intrinsics for java.util.zip.CRC32")                         \
 345                                                                             \
 346   product(bool, UseCRC32CIntrinsics, false, DIAGNOSTIC,                     \
 347           "use intrinsics for java.util.zip.CRC32C")                        \
 348                                                                             \
 349   product(bool, UseAdler32Intrinsics, false, DIAGNOSTIC,                    \
 350           "use intrinsics for java.util.zip.Adler32")                       \
 351                                                                             \
 352   product(bool, UseVectorizedMismatchIntrinsic, false, DIAGNOSTIC,          \
 353           "Enables intrinsification of ArraysSupport.vectorizedMismatch()") \
 354                                                                             \
 355   product(bool, UseVectorizedHashCodeIntrinsic, false, DIAGNOSTIC,          \
 356           "Enables intrinsification of ArraysSupport.vectorizedHashCode()") \
 357                                                                             \
 358   product(bool, UseCopySignIntrinsic, false, DIAGNOSTIC,                    \
 359           "Enables intrinsification of Math.copySign")                      \
 360                                                                             \
 361   product(bool, UseSignumIntrinsic, false, DIAGNOSTIC,                      \
 362           "Enables intrinsification of Math.signum")                        \
 363                                                                             \
 364   product_pd(bool, DelayCompilerStubsGeneration, DIAGNOSTIC,                \
 365           "Use Compiler thread for compiler's stubs generation")            \
 366                                                                             \
 367   product(ccstrlist, DisableIntrinsic, "", DIAGNOSTIC,                      \
 368          "do not expand intrinsics whose (internal) names appear here")     \
 369          constraint(DisableIntrinsicConstraintFunc,AfterErgo)               \
 370                                                                             \
 371   product(ccstrlist, ControlIntrinsic, "", DIAGNOSTIC,                      \
 372          "Control intrinsics using a list of +/- (internal) names, "        \
 373          "separated by commas")                                             \
 374          constraint(ControlIntrinsicConstraintFunc,AfterErgo)               \
 375                                                                             \
 376   develop(bool, TraceCallFixup, false,                                      \
 377           "Trace all call fixups")                                          \
 378                                                                             \
 379   develop(bool, DeoptimizeALot, false,                                      \
 380           "Deoptimize at every exit from the runtime system")               \
 381                                                                             \
 382   develop(ccstrlist, DeoptimizeOnlyAt, "",                                  \
 383           "A comma separated list of bcis to deoptimize at")                \
 384                                                                             \
 385   develop(bool, DeoptimizeRandom, false,                                    \
 386           "Deoptimize random frames on random exit from the runtime system")\
 387                                                                             \
 388   develop(bool, ZombieALot, false,                                          \
 389           "Create non-entrant nmethods at exit from the runtime system")    \
 390                                                                             \
 391   develop(bool, WalkStackALot, false,                                       \
 392           "Trace stack (no print) at every exit from the runtime system")   \
 393                                                                             \
 394   develop(bool, DeoptimizeObjectsALot, false,                               \
 395           "For testing purposes concurrent threads revert optimizations "   \
 396           "based on escape analysis at intervals given with "               \
 397           "DeoptimizeObjectsALotInterval=n. The thread count is given "     \
 398           "with DeoptimizeObjectsALotThreadCountSingle and "                \
 399           "DeoptimizeObjectsALotThreadCountAll.")                           \
 400                                                                             \
 401   develop(uint64_t, DeoptimizeObjectsALotInterval, 5,                       \
 402           "Interval for DeoptimizeObjectsALot.")                            \
 403           range(0, max_jlong)                                               \
 404                                                                             \
 405   develop(int, DeoptimizeObjectsALotThreadCountSingle, 1,                   \
 406           "The number of threads that revert optimizations based on "       \
 407           "escape analysis for a single thread if DeoptimizeObjectsALot "   \
 408           "is enabled. The target thread is selected round robin." )        \
 409           range(0, max_jint)                                                \
 410                                                                             \
 411   develop(int, DeoptimizeObjectsALotThreadCountAll, 1,                      \
 412           "The number of threads that revert optimizations based on "       \
 413           "escape analysis for all threads if DeoptimizeObjectsALot "       \
 414           "is enabled." )                                                   \
 415           range(0, max_jint)                                                \
 416                                                                             \
 417   develop(bool, VerifyLastFrame, false,                                     \
 418           "Verify oops on last frame on entry to VM")                       \
 419                                                                             \
 420   product(bool, SafepointTimeout, false,                                    \
 421           "Time out and warn or fail after SafepointTimeoutDelay "          \
 422           "milliseconds if failed to reach safepoint")                      \
 423                                                                             \
 424   product(bool, AbortVMOnSafepointTimeout, false, DIAGNOSTIC,               \
 425           "Abort upon failure to reach safepoint (see SafepointTimeout)")   \
 426                                                                             \
 427   product(uint64_t, AbortVMOnSafepointTimeoutDelay, 0, DIAGNOSTIC,          \
 428           "Delay in milliseconds for option AbortVMOnSafepointTimeout")     \
 429           range(0, max_jlong)                                               \
 430                                                                             \
 431   product(bool, AbortVMOnVMOperationTimeout, false, DIAGNOSTIC,             \
 432           "Abort upon failure to complete VM operation promptly")           \
 433                                                                             \
 434   product(intx, AbortVMOnVMOperationTimeoutDelay, 1000, DIAGNOSTIC,         \
 435           "Delay in milliseconds for option AbortVMOnVMOperationTimeout")   \
 436           range(0, max_intx)                                                \
 437                                                                             \
 438   product(bool, MaxFDLimit, true,                                           \
 439           "Bump the number of file descriptors to maximum (Unix only)")     \
 440                                                                             \
 441   product(bool, LogEvents, true, DIAGNOSTIC,                                \
 442           "Enable the various ring buffer event logs")                      \
 443                                                                             \
 444   product(int, LogEventsBufferEntries, 20, DIAGNOSTIC,                      \
 445           "Number of ring buffer event logs")                               \
 446           range(1, NOT_LP64(1*K) LP64_ONLY(1*M))                            \
 447                                                                             \
 448   product(bool, BytecodeVerificationRemote, true, DIAGNOSTIC,               \
 449           "Enable the Java bytecode verifier for remote classes")           \
 450                                                                             \
 451   product(bool, BytecodeVerificationLocal, false, DIAGNOSTIC,               \
 452           "Enable the Java bytecode verifier for local classes")            \
 453                                                                             \
 454   develop(bool, VerifyStackAtCalls, false,                                  \
 455           "Verify that the stack pointer is unchanged after calls")         \
 456                                                                             \
 457   develop(bool, TraceJavaAssertions, false,                                 \
 458           "Trace java language assertions")                                 \
 459                                                                             \
 460   develop(bool, VerifyCodeCache, false,                                     \
 461           "Verify code cache on memory allocation/deallocation")            \
 462                                                                             \
 463   develop(bool, ZapResourceArea, trueInDebug,                               \
 464           "Zap freed resource/arena space")                                 \
 465                                                                             \
 466   develop(bool, ZapVMHandleArea, trueInDebug,                               \
 467           "Zap freed VM handle space")                                      \
 468                                                                             \
 469   develop(bool, ZapStackSegments, trueInDebug,                              \
 470           "Zap allocated/freed stack segments")                             \
 471                                                                             \
 472   develop(bool, ZapUnusedHeapArea, trueInDebug,                             \
 473           "Zap unused heap space")                                          \
 474                                                                             \
 475   develop(bool, ZapFillerObjects, trueInDebug,                              \
 476           "Zap filler objects")                                             \
 477                                                                             \
 478   develop(bool, ZapTLAB, trueInDebug,                                       \
 479           "Zap allocated TLABs")                                            \
 480                                                                             \
 481   product(bool, ExecutingUnitTests, false,                                  \
 482           "Whether the JVM is running unit tests or not")                   \
 483                                                                             \
 484   develop(uint, ErrorHandlerTest, 0,                                        \
 485           "If > 0, provokes an error after VM initialization; the value "   \
 486           "determines which error to provoke. See controlled_crash() "      \
 487           "in vmError.cpp.")                                                \
 488           range(0, 17)                                                      \
 489                                                                             \
 490   develop(uint, TestCrashInErrorHandler, 0,                                 \
 491           "If > 0, provokes an error inside VM error handler (a secondary " \
 492           "crash). see controlled_crash() in vmError.cpp")                  \
 493           range(0, 17)                                                      \
 494                                                                             \
 495   develop(bool, TestSafeFetchInErrorHandler, false   ,                      \
 496           "If true, tests SafeFetch inside error handler.")                 \
 497                                                                             \
 498   develop(bool, TestUnresponsiveErrorHandler, false,                        \
 499           "If true, simulates an unresponsive error handler.")              \
 500                                                                             \
 501   develop(bool, Verbose, false,                                             \
 502           "Print additional debugging information from other modes")        \
 503                                                                             \
 504   develop(bool, PrintMiscellaneous, false,                                  \
 505           "Print uncategorized debugging information (requires +Verbose)")  \
 506                                                                             \
 507   develop(bool, WizardMode, false,                                          \
 508           "Print much more debugging information")                          \
 509                                                                             \
 510   product(bool, ShowMessageBoxOnError, false,                               \
 511           "Keep process alive on VM fatal error")                           \
 512                                                                             \
 513   product(bool, CreateCoredumpOnCrash, true,                                \
 514           "Create core/mini dump on VM fatal error")                        \
 515                                                                             \
 516   product(uint64_t, ErrorLogTimeout, 2 * 60,                                \
 517           "Timeout, in seconds, to limit the time spent on writing an "     \
 518           "error log in case of a crash.")                                  \
 519           range(0, (uint64_t)max_jlong/1000)                                \
 520                                                                             \
 521   product(bool, ErrorLogSecondaryErrorDetails, false, DIAGNOSTIC,           \
 522           "If enabled, show details on secondary crashes in the error log") \
 523                                                                             \
 524   develop(intx, TraceDwarfLevel, 0,                                         \
 525           "Debug levels for the dwarf parser")                              \
 526           range(0, 4)                                                       \
 527                                                                             \
 528   product(bool, SuppressFatalErrorMessage, false,                           \
 529           "Report NO fatal error message (avoid deadlock)")                 \
 530                                                                             \
 531   product(ccstrlist, OnError, "",                                           \
 532           "Run user-defined commands on fatal error; see VMError.cpp "      \
 533           "for examples")                                                   \
 534                                                                             \
 535   product(ccstrlist, OnOutOfMemoryError, "",                                \
 536           "Run user-defined commands on first java.lang.OutOfMemoryError "  \
 537           "thrown from JVM")                                                \
 538                                                                             \
 539   product(bool, HeapDumpBeforeFullGC, false, MANAGEABLE,                    \
 540           "Dump heap to file before any major stop-the-world GC "           \
 541           "(also see FullGCHeapDumpLimit, HeapDumpPath, HeapDumpGzipLevel)")\
 542                                                                             \
 543   product(bool, HeapDumpAfterFullGC, false, MANAGEABLE,                     \
 544           "Dump heap to file after any major stop-the-world GC "            \
 545           "(also see FullGCHeapDumpLimit, HeapDumpPath, HeapDumpGzipLevel)")\
 546                                                                             \
 547   product(uint, FullGCHeapDumpLimit, 0, MANAGEABLE,                         \
 548           "Limit the number of heap dumps triggered by "                    \
 549           "HeapDumpBeforeFullGC or HeapDumpAfterFullGC "                    \
 550           "(0 means no limit)")                                             \
 551                                                                             \
 552   product(bool, HeapDumpOnOutOfMemoryError, false, MANAGEABLE,              \
 553           "Dump heap to file when java.lang.OutOfMemoryError is thrown "    \
 554           "from JVM "                                                       \
 555           "(also see HeapDumpPath, HeapDumpGzipLevel)")                     \
 556                                                                             \
 557   product(ccstr, HeapDumpPath, nullptr, MANAGEABLE,                         \
 558           "When HeapDumpOnOutOfMemoryError, HeapDumpBeforeFullGC "          \
 559           "or HeapDumpAfterFullGC is on, the path (filename or "            \
 560           "directory) of the dump file (defaults to java_pid<pid>.hprof "   \
 561           "in the working directory)")                                      \
 562                                                                             \
 563   product(int, HeapDumpGzipLevel, 0, MANAGEABLE,                            \
 564           "When HeapDumpOnOutOfMemoryError, HeapDumpBeforeFullGC "          \
 565           "or HeapDumpAfterFullGC is on, the gzip compression "             \
 566           "level of the dump file. 0 (the default) disables gzip "          \
 567           "compression. Otherwise the level must be between 1 and 9.")      \
 568           range(0, 9)                                                       \
 569                                                                             \
 570   product(ccstr, NativeMemoryTracking, DEBUG_ONLY("summary") NOT_DEBUG("off"), \
 571           "Native memory tracking options")                                 \
 572                                                                             \
 573   product(bool, PrintNMTStatistics, false, DIAGNOSTIC,                      \
 574           "Print native memory tracking summary data if it is on")          \
 575                                                                             \
 576   product(bool, LogCompilation, false, DIAGNOSTIC,                          \
 577           "Log compilation activity in detail to LogFile")                  \
 578                                                                             \
 579   product(bool, PrintCompilation, false,                                    \
 580           "Print compilations")                                             \
 581                                                                             \
 582   product(intx, RepeatCompilation, 0, DIAGNOSTIC,                           \
 583           "Repeat compilation without installing code (number of times)")   \
 584           range(0, max_jint)                                                \
 585                                                                             \
 586   product(bool, PrintExtendedThreadInfo, false,                             \
 587           "Print more information in thread dump")                          \
 588                                                                             \
 589   product(intx, ScavengeRootsInCode, 2, DIAGNOSTIC,                         \
 590           "0: do not allow scavengable oops in the code cache; "            \
 591           "1: allow scavenging from the code cache; "                       \
 592           "2: emit as many constants as the compiler can see")              \
 593           range(0, 2)                                                       \
 594                                                                             \
 595   product(bool, AlwaysRestoreFPU, false,                                    \
 596           "Restore the FPU control word after every JNI call (expensive)")  \
 597                                                                             \
 598   product(bool, PrintCompilation2, false, DIAGNOSTIC,                       \
 599           "Print additional statistics per compilation")                    \
 600                                                                             \
 601   product(bool, PrintAdapterHandlers, false, DIAGNOSTIC,                    \
 602           "Print code generated for i2c/c2i adapters")                      \
 603                                                                             \
 604   product(bool, VerifyAdapterCalls, trueInDebug, DIAGNOSTIC,                \
 605           "Verify that i2c/c2i adapters are called properly")               \
 606                                                                             \
 607   develop(bool, VerifyAdapterSharing, false,                                \
 608           "Verify that the code for shared adapters is the equivalent")     \
 609                                                                             \
 610   product(bool, PrintAssembly, false, DIAGNOSTIC,                           \
 611           "Print assembly code (using external disassembler.so)")           \
 612                                                                             \
 613   product(ccstr, PrintAssemblyOptions, nullptr, DIAGNOSTIC,                 \
 614           "Print options string passed to disassembler.so")                 \
 615                                                                             \
 616   develop(bool, PrintNMethodStatistics, false,                              \
 617           "Print a summary statistic for the generated nmethods")           \
 618                                                                             \
 619   product(bool, PrintNMethods, false, DIAGNOSTIC,                           \
 620           "Print assembly code for nmethods when generated")                \
 621                                                                             \
 622   product(bool, PrintNativeNMethods, false, DIAGNOSTIC,                     \
 623           "Print assembly code for native nmethods when generated")         \
 624                                                                             \
 625   develop(bool, PrintDebugInfo, false,                                      \
 626           "Print debug information for all nmethods when generated")        \
 627                                                                             \
 628   develop(bool, PrintRelocations, false,                                    \
 629           "Print relocation information for all nmethods when generated")   \
 630                                                                             \
 631   develop(bool, PrintDependencies, false,                                   \
 632           "Print dependency information for all nmethods when generated")   \
 633                                                                             \
 634   develop(bool, PrintExceptionHandlers, false,                              \
 635           "Print exception handler tables for all nmethods when generated") \
 636                                                                             \
 637   develop(bool, StressCompiledExceptionHandlers, false,                     \
 638           "Exercise compiled exception handlers")                           \
 639                                                                             \
 640   develop(bool, InterceptOSException, false,                                \
 641           "Start debugger when an implicit OS (e.g. null pointer) "         \
 642           "exception happens")                                              \
 643                                                                             \
 644   product(bool, PrintCodeCache, false,                                      \
 645           "Print the code cache memory usage when exiting")                 \
 646                                                                             \
 647   develop(bool, PrintCodeCache2, false,                                     \
 648           "Print detailed usage information on the code cache when exiting")\
 649                                                                             \
 650   product(bool, PrintCodeCacheOnCompilation, false,                         \
 651           "Print the code cache memory usage each time a method is "        \
 652           "compiled")                                                       \
 653                                                                             \
 654   product(bool, PrintCodeHeapAnalytics, false, DIAGNOSTIC,                  \
 655           "Print code heap usage statistics on exit and on full condition") \
 656                                                                             \
 657   product(bool, PrintStubCode, false, DIAGNOSTIC,                           \
 658           "Print generated stub code")                                      \
 659                                                                             \
 660   product(bool, StackTraceInThrowable, true,                                \
 661           "Collect backtrace in throwable when exception happens")          \
 662                                                                             \
 663   product(bool, OmitStackTraceInFastThrow, true,                            \
 664           "Omit backtraces for some 'hot' exceptions in optimized code")    \
 665                                                                             \
 666   product(bool, ShowCodeDetailsInExceptionMessages, true, MANAGEABLE,       \
 667           "Show exception messages from RuntimeExceptions that contain "    \
 668           "snippets of the failing code. Disable this to improve privacy.") \
 669                                                                             \
 670   product(bool, PrintWarnings, true,                                        \
 671           "Print JVM warnings to output stream")                            \
 672                                                                             \
 673   develop(bool, RegisterReferences, true,                                   \
 674           "Tell whether the VM should register soft/weak/final/phantom "    \
 675           "references")                                                     \
 676                                                                             \
 677   develop(bool, PrintCodeCacheExtension, false,                             \
 678           "Print extension of code cache")                                  \
 679                                                                             \
 680   develop(bool, UsePrivilegedStack, true,                                   \
 681           "Enable the security JVM functions")                              \
 682                                                                             \
 683   product(bool, ClassUnloading, true,                                       \
 684           "Do unloading of classes")                                        \
 685                                                                             \
 686   product(bool, ClassUnloadingWithConcurrentMark, true,                     \
 687           "Do unloading of classes with a concurrent marking cycle")        \
 688                                                                             \
 689   develop(bool, PrintSystemDictionaryAtExit, false,                         \
 690           "Print the system dictionary at exit")                            \
 691                                                                             \
 692   develop(bool, PrintClassLoaderDataGraphAtExit, false,                     \
 693           "Print the class loader data graph at exit")                      \
 694                                                                             \
 695   product(bool, AllowParallelDefineClass, false,                            \
 696           "Allow parallel defineClass requests for class loaders "          \
 697           "registering as parallel capable")                                \
 698                                                                             \
 699   product_pd(bool, DontYieldALot,                                           \
 700              "(Deprecated) Throw away obvious excess yield calls")          \
 701                                                                             \
 702   product(bool, DisablePrimordialThreadGuardPages, false, EXPERIMENTAL,     \
 703                "Disable the use of stack guard pages if the JVM is loaded " \
 704                "on the primordial process thread")                          \
 705                                                                             \
 706   product(bool, DoJVMTIVirtualThreadTransitions, true, EXPERIMENTAL,        \
 707                "Do JVMTI virtual thread mount/unmount transitions "         \
 708                "(disabling this flag implies no JVMTI events are posted)")  \
 709                                                                             \
 710   /* notice: the max range value here is max_jint, not max_intx  */         \
 711   /* because of overflow issue                                   */         \
 712   product(intx, AsyncDeflationInterval, 250, DIAGNOSTIC,                    \
 713           "Async deflate idle monitors every so many milliseconds when "    \
 714           "MonitorUsedDeflationThreshold is exceeded (0 is off).")          \
 715           range(0, max_jint)                                                \
 716                                                                             \
 717   /* notice: the max range value here is max_jint, not max_intx  */         \
 718   /* because of overflow issue                                   */         \
 719   product(intx, GuaranteedAsyncDeflationInterval, 60000, DIAGNOSTIC,        \
 720           "Async deflate idle monitors every so many milliseconds even "    \
 721           "when MonitorUsedDeflationThreshold is NOT exceeded (0 is off).") \
 722           range(0, max_jint)                                                \
 723                                                                             \
 724   product(size_t, AvgMonitorsPerThreadEstimate, 1024, DIAGNOSTIC,           \
 725           "Used to estimate a variable ceiling based on number of threads " \
 726           "for use with MonitorUsedDeflationThreshold (0 is off).")         \
 727           range(0, max_uintx)                                               \
 728                                                                             \
 729   /* notice: the max range value here is max_jint, not max_intx  */         \
 730   /* because of overflow issue                                   */         \
 731   product(intx, MonitorDeflationMax, 1000000, DIAGNOSTIC,                   \
 732           "The maximum number of monitors to deflate, unlink and delete "   \
 733           "at one time (minimum is 1024).")                                 \
 734           range(1024, max_jint)                                             \
 735                                                                             \
 736   product(intx, MonitorUnlinkBatch, 500, DIAGNOSTIC,                        \
 737           "The maximum number of monitors to unlink in one batch. ")        \
 738           range(1, max_jint)                                                \
 739                                                                             \
 740   product(int, MonitorUsedDeflationThreshold, 90, DIAGNOSTIC,               \
 741           "Percentage of used monitors before triggering deflation (0 is "  \
 742           "off). The check is performed on AsyncDeflationInterval or "      \
 743           "GuaranteedAsyncDeflationInterval, whichever is lower.")          \
 744           range(0, 100)                                                     \
 745                                                                             \
 746   product(uintx, NoAsyncDeflationProgressMax, 3, DIAGNOSTIC,                \
 747           "Max number of no progress async deflation attempts to tolerate " \
 748           "before adjusting the in_use_list_ceiling up (0 is off).")        \
 749           range(0, max_uintx)                                               \
 750                                                                             \
 751   product(intx, hashCode, 5, EXPERIMENTAL,                                  \
 752                "(Unstable) select hashCode generation algorithm")           \
 753                                                                             \
 754   product(bool, ReduceSignalUsage, false,                                   \
 755           "Reduce the use of OS signals in Java and/or the VM")             \
 756                                                                             \
 757   develop(bool, LoadLineNumberTables, true,                                 \
 758           "Tell whether the class file parser loads line number tables")    \
 759                                                                             \
 760   develop(bool, LoadLocalVariableTables, true,                              \
 761           "Tell whether the class file parser loads local variable tables") \
 762                                                                             \
 763   develop(bool, LoadLocalVariableTypeTables, true,                          \
 764           "Tell whether the class file parser loads local variable type"    \
 765           "tables")                                                         \
 766                                                                             \
 767   product(bool, AllowUserSignalHandlers, false,                             \
 768           "Application will install primary signal handlers for the JVM "   \
 769           "(Unix only)")                                                    \
 770                                                                             \
 771   product(bool, UseSignalChaining, true,                                    \
 772           "Use signal-chaining to invoke signal handlers installed "        \
 773           "by the application (Unix only)")                                 \
 774                                                                             \
 775   product(bool, RestoreMXCSROnJNICalls, false,                              \
 776           "Restore MXCSR when returning from JNI calls")                    \
 777                                                                             \
 778   product(bool, CheckJNICalls, false,                                       \
 779           "Verify all arguments to JNI calls")                              \
 780                                                                             \
 781   product(bool, UseFastJNIAccessors, true,                                  \
 782           "Use optimized versions of Get<Primitive>Field")                  \
 783                                                                             \
 784   product(intx, MaxJNILocalCapacity, 65536,                                 \
 785           "Maximum allowable local JNI handle capacity to "                 \
 786           "EnsureLocalCapacity() and PushLocalFrame(), "                    \
 787           "where <= 0 is unlimited, default: 65536")                        \
 788           range(min_intx, max_intx)                                         \
 789                                                                             \
 790   product(bool, EagerXrunInit, false,                                       \
 791           "Eagerly initialize -Xrun libraries; allows startup profiling, "  \
 792           "but not all -Xrun libraries may support the state of the VM "    \
 793           "at this time")                                                   \
 794                                                                             \
 795   develop(uintx, PreallocatedOutOfMemoryErrorCount, 4,                      \
 796           "Number of OutOfMemoryErrors preallocated with backtrace")        \
 797                                                                             \
 798   product(bool, UseXMMForArrayCopy, false,                                  \
 799           "Use SSE2 MOVQ instruction for Arraycopy")                        \
 800                                                                             \
 801   develop(bool, PrintFieldLayout, false,                                    \
 802           "Print field layout for each class")                              \
 803                                                                             \
 804   /* Need to limit the extent of the padding to reasonable size.          */\
 805   /* 8K is well beyond the reasonable HW cache line size, even with       */\
 806   /* aggressive prefetching, while still leaving the room for segregating */\
 807   /* among the distinct pages.                                            */\
 808   product(int, ContendedPaddingWidth, 128,                                  \
 809           "How many bytes to pad the fields/classes marked @Contended with")\
 810           range(0, 8192)                                                    \
 811           constraint(ContendedPaddingWidthConstraintFunc,AfterErgo)         \
 812                                                                             \
 813   product(bool, EnableContended, true,                                      \
 814           "Enable @Contended annotation support")                           \
 815                                                                             \
 816   product(bool, RestrictContended, true,                                    \
 817           "Restrict @Contended to trusted classes")                         \
 818                                                                             \
 819   product(int, DiagnoseSyncOnValueBasedClasses, 0, DIAGNOSTIC,              \
 820              "Detect and take action upon identifying synchronization on "  \
 821              "value based classes. Modes: "                                 \
 822              "0: off; "                                                     \
 823              "1: exit with fatal error; "                                   \
 824              "2: log message to stdout. Output file can be specified with " \
 825              "   -Xlog:valuebasedclasses. If JFR is running it will "       \
 826              "   also generate JFR events.")                                \
 827              range(0, 2)                                                    \
 828                                                                             \
 829   product(bool, ExitOnOutOfMemoryError, false,                              \
 830           "JVM exits on the first occurrence of an out-of-memory error "    \
 831           "thrown from JVM")                                                \
 832                                                                             \
 833   product(bool, CrashOnOutOfMemoryError, false,                             \
 834           "JVM aborts, producing an error log and core/mini dump, on the "  \
 835           "first occurrence of an out-of-memory error thrown from JVM")     \
 836                                                                             \
 837   product(intx, UserThreadWaitAttemptsAtExit, 30,                           \
 838           "The number of times to wait for user threads to stop executing " \
 839           "native code during JVM exit. Each wait lasts 10 milliseconds. "  \
 840           "The maximum number of waits is 1000, to wait at most 10 "        \
 841           "seconds.")                                                       \
 842           range(0, 1000)                                                    \
 843                                                                             \
 844   /* tracing */                                                             \
 845                                                                             \
 846   develop(bool, StressRewriter, false,                                      \
 847           "Stress linktime bytecode rewriting")                             \
 848                                                                             \
 849   product(ccstr, TraceJVMTI, nullptr,                                       \
 850           "Trace flags for JVMTI functions and events")                     \
 851                                                                             \
 852   product(bool, StressLdcRewrite, false, DIAGNOSTIC,                        \
 853           "Force ldc -> ldc_w rewrite during RedefineClasses. "             \
 854           "This option can change an EMCP method into an obsolete method "  \
 855           "and can affect tests that expect specific methods to be EMCP. "  \
 856           "This option should be used with caution.")                       \
 857                                                                             \
 858   product(bool, AllowRedefinitionToAddDeleteMethods, false,                 \
 859           "(Deprecated) Allow redefinition to add and delete private "      \
 860           "static or final methods for compatibility with old releases")    \
 861                                                                             \
 862   develop(bool, TraceBytecodes, false,                                      \
 863           "Trace bytecode execution")                                       \
 864                                                                             \
 865   develop(bool, TraceBytecodesTruncated, false,                             \
 866           "Truncate non control-flow bytecode when tracing bytecode")       \
 867                                                                             \
 868   develop(bool, VerifyDependencies, trueInDebug,                            \
 869           "Exercise and verify the compilation dependency mechanism")       \
 870                                                                             \
 871   develop(bool, TraceNewOopMapGeneration, false,                            \
 872           "Trace OopMapGeneration")                                         \
 873                                                                             \
 874   develop(bool, TraceNewOopMapGenerationDetailed, false,                    \
 875           "Trace OopMapGeneration: print detailed cell states")             \
 876                                                                             \
 877   develop(bool, TimeOopMap, false,                                          \
 878           "Time calls to GenerateOopMap::compute_map() in sum")             \
 879                                                                             \
 880   develop(bool, TimeOopMap2, false,                                         \
 881           "Time calls to GenerateOopMap::compute_map() individually")       \
 882                                                                             \
 883   develop(bool, TraceOopMapRewrites, false,                                 \
 884           "Trace rewriting of methods during oop map generation")           \
 885                                                                             \
 886   develop(bool, TraceFinalizerRegistration, false,                          \
 887           "Trace registration of final references")                         \
 888                                                                             \
 889   product(bool, IgnoreEmptyClassPaths, false,                               \
 890           "Ignore empty path elements in -classpath")                       \
 891                                                                             \
 892   product(bool, PrintHeapAtSIGBREAK, true,                                  \
 893           "Print heap layout in response to SIGBREAK")                      \
 894                                                                             \
 895   product(bool, PrintClassHistogram, false, MANAGEABLE,                     \
 896           "Print a histogram of class instances")                           \
 897                                                                             \
 898   product(double, ObjectCountCutOffPercent, 0.5, EXPERIMENTAL,              \
 899           "The percentage of the used heap that the instances of a class "  \
 900           "must occupy for the class to generate a trace event")            \
 901           range(0.0, 100.0)                                                 \
 902                                                                             \
 903   /* JVMTI heap profiling */                                                \
 904                                                                             \
 905   product(bool, VerifyBeforeIteration, false, DIAGNOSTIC,                   \
 906           "Verify memory system before JVMTI iteration")                    \
 907                                                                             \
 908   /* compiler */                                                            \
 909                                                                             \
 910   /* notice: the max range value here is max_jint, not max_intx  */         \
 911   /* because of overflow issue                                   */         \
 912   product(intx, CICompilerCount, CI_COMPILER_COUNT,                         \
 913           "Number of compiler threads to run")                              \
 914           range(0, max_jint)                                                \
 915           constraint(CICompilerCountConstraintFunc, AfterErgo)              \
 916                                                                             \
 917   product(bool, UseDynamicNumberOfCompilerThreads, true,                    \
 918           "Dynamically choose the number of parallel compiler threads")     \
 919                                                                             \
 920   product(bool, ReduceNumberOfCompilerThreads, true, DIAGNOSTIC,            \
 921              "Reduce the number of parallel compiler threads when they "    \
 922              "are not used")                                                \
 923                                                                             \
 924   product(bool, TraceCompilerThreads, false, DIAGNOSTIC,                    \
 925              "Trace creation and removal of compiler threads")              \
 926                                                                             \
 927   product(ccstr, LogClassLoadingCauseFor, nullptr,                          \
 928           "Apply -Xlog:class+load+cause* to classes whose fully "           \
 929           "qualified name contains this string (\"*\" matches "             \
 930           "any class).")                                                    \
 931                                                                             \
 932   develop(bool, InjectCompilerCreationFailure, false,                       \
 933           "Inject thread creation failures for "                            \
 934           "UseDynamicNumberOfCompilerThreads")                              \
 935                                                                             \
 936   develop(bool, GenerateSynchronizationCode, true,                          \
 937           "generate locking/unlocking code for synchronized methods and "   \
 938           "monitors")                                                       \
 939                                                                             \
 940   product_pd(bool, ImplicitNullChecks, DIAGNOSTIC,                          \
 941           "Generate code for implicit null checks")                         \
 942                                                                             \
 943   product_pd(bool, TrapBasedNullChecks,                                     \
 944           "Generate code for null checks that uses a cmp and trap "         \
 945           "instruction raising SIGTRAP.  This is only used if an access to" \
 946           "null (+offset) will not raise a SIGSEGV, i.e.,"                  \
 947           "ImplicitNullChecks don't work (PPC64).")                         \
 948                                                                             \
 949   product(bool, EnableThreadSMRStatistics, trueInDebug, DIAGNOSTIC,         \
 950              "Enable Thread SMR Statistics")                                \
 951                                                                             \
 952   product(bool, Inline, true,                                               \
 953           "Enable inlining")                                                \
 954                                                                             \
 955   product(bool, ClipInlining, true,                                         \
 956           "Clip inlining if aggregate method exceeds DesiredMethodLimit")   \
 957                                                                             \
 958   develop(bool, UseCHA, true,                                               \
 959           "Enable CHA")                                                     \
 960                                                                             \
 961   product(bool, UseTypeProfile, true,                                       \
 962           "Check interpreter profile for historically monomorphic calls")   \
 963                                                                             \
 964   product(bool, PrintInlining, false, DIAGNOSTIC,                           \
 965           "Print inlining optimizations")                                   \
 966                                                                             \
 967   product(bool, UsePopCountInstruction, false,                              \
 968           "Use population count instruction")                               \
 969                                                                             \
 970   develop(bool, TraceMethodReplacement, false,                              \
 971           "Print when methods are replaced do to recompilation")            \
 972                                                                             \
 973   product(intx, MinPassesBeforeFlush, 10, DIAGNOSTIC,                       \
 974           "Minimum number of sweeper passes before an nmethod "             \
 975           "can be flushed")                                                 \
 976           range(0, max_intx)                                                \
 977                                                                             \
 978   develop(bool, StressCodeBuffers, false,                                   \
 979           "Exercise code buffer expansion and other rare state changes")    \
 980                                                                             \
 981   product(bool, DebugNonSafepoints, trueInDebug, DIAGNOSTIC,                \
 982           "Generate extra debugging information for non-safepoints in "     \
 983           "nmethods")                                                       \
 984                                                                             \
 985   product(bool, PrintVMOptions, false,                                      \
 986           "Print flags that appeared on the command line")                  \
 987                                                                             \
 988   product(bool, IgnoreUnrecognizedVMOptions, false,                         \
 989           "Ignore unrecognized VM options")                                 \
 990                                                                             \
 991   product(bool, PrintCommandLineFlags, false,                               \
 992           "Print flags specified on command line or set by ergonomics")     \
 993                                                                             \
 994   product(bool, PrintFlagsInitial, false,                                   \
 995           "Print all VM flags before argument processing and exit VM")      \
 996                                                                             \
 997   product(bool, PrintFlagsFinal, false,                                     \
 998           "Print all VM flags after argument and ergonomic processing")     \
 999                                                                             \
1000   develop(bool, PrintFlagsWithComments, false,                              \
1001           "Print all VM flags with default values and descriptions and "    \
1002           "exit")                                                           \
1003                                                                             \
1004   product(bool, PrintFlagsRanges, false,                                    \
1005           "Print VM flags and their ranges")                                \
1006                                                                             \
1007   product(bool, SerializeVMOutput, true, DIAGNOSTIC,                        \
1008           "Use a mutex to serialize output to tty and LogFile")             \
1009                                                                             \
1010   product(bool, DisplayVMOutput, true, DIAGNOSTIC,                          \
1011           "Display all VM output on the tty, independently of LogVMOutput") \
1012                                                                             \
1013   product(bool, LogVMOutput, false, DIAGNOSTIC,                             \
1014           "Save VM output to LogFile")                                      \
1015                                                                             \
1016   product(ccstr, LogFile, nullptr, DIAGNOSTIC,                              \
1017           "If LogVMOutput or LogCompilation is on, save VM output to "      \
1018           "this file [default: ./hotspot_pid%p.log] (%p replaced with pid)")\
1019                                                                             \
1020   product(ccstr, ErrorFile, nullptr,                                        \
1021           "If an error occurs, save the error data to this file "           \
1022           "[default: ./hs_err_pid%p.log] (%p replaced with pid)")           \
1023                                                                             \
1024   product(bool, ExtensiveErrorReports,                                      \
1025           PRODUCT_ONLY(false) NOT_PRODUCT(true),                            \
1026           "Error reports are more extensive.")                              \
1027                                                                             \
1028   product(bool, DisplayVMOutputToStderr, false,                             \
1029           "If DisplayVMOutput is true, display all VM output to stderr")    \
1030                                                                             \
1031   product(bool, DisplayVMOutputToStdout, false,                             \
1032           "If DisplayVMOutput is true, display all VM output to stdout")    \
1033                                                                             \
1034   product(bool, ErrorFileToStderr, false,                                   \
1035           "If true, error data is printed to stderr instead of a file")     \
1036                                                                             \
1037   product(bool, ErrorFileToStdout, false,                                   \
1038           "If true, error data is printed to stdout instead of a file")     \
1039                                                                             \
1040   develop(bool, VerifyHeavyMonitors, false,                                 \
1041           "Checks that no stack locking happens when using "                \
1042           "-XX:LockingMode=0 (LM_MONITOR)")                                 \
1043                                                                             \
1044   product(bool, PrintStringTableStatistics, false,                          \
1045           "print statistics about the StringTable and SymbolTable")         \
1046                                                                             \
1047   product(bool, VerifyStringTableAtExit, false, DIAGNOSTIC,                 \
1048           "verify StringTable contents at exit")                            \
1049                                                                             \
1050   develop(bool, PrintSymbolTableSizeHistogram, false,                       \
1051           "print histogram of the symbol table")                            \
1052                                                                             \
1053   product(ccstr, AbortVMOnException, nullptr, DIAGNOSTIC,                   \
1054           "Call fatal if this exception is thrown.  Example: "              \
1055           "java -XX:AbortVMOnException=java.lang.NullPointerException Foo") \
1056                                                                             \
1057   product(ccstr, AbortVMOnExceptionMessage, nullptr, DIAGNOSTIC,            \
1058           "Call fatal if the exception pointed by AbortVMOnException "      \
1059           "has this message")                                               \
1060                                                                             \
1061   develop(bool, DebugVtables, false,                                        \
1062           "add debugging code to vtable dispatch")                          \
1063                                                                             \
1064   product(bool, RangeCheckElimination, true,                                \
1065           "Eliminate range checks")                                         \
1066                                                                             \
1067   develop_pd(bool, UncommonNullCast,                                        \
1068           "track occurrences of null in casts; adjust compiler tactics")    \
1069                                                                             \
1070   develop(bool, TypeProfileCasts,  true,                                    \
1071           "treat casts like calls for purposes of type profiling")          \
1072                                                                             \
1073   develop(bool, TraceLivenessGen, false,                                    \
1074           "Trace the generation of liveness analysis information")          \
1075                                                                             \
1076   develop(bool, TraceLivenessQuery, false,                                  \
1077           "Trace queries of liveness analysis information")                 \
1078                                                                             \
1079   develop(bool, CollectIndexSetStatistics, false,                           \
1080           "Collect information about IndexSets")                            \
1081                                                                             \
1082   develop(int, FastAllocateSizeLimit, 128*K,                                \
1083           /* Note:  This value is zero mod 1<<13 for a cheap sparc set. */  \
1084           "Inline allocations larger than this in doublewords must go slow")\
1085                                                                             \
1086   product_pd(bool, CompactStrings,                                          \
1087           "Enable Strings to use single byte chars in backing store")       \
1088                                                                             \
1089   product_pd(uint, TypeProfileLevel,                                        \
1090           "=XYZ, with Z: Type profiling of arguments at call; "             \
1091                      "Y: Type profiling of return value at call; "          \
1092                      "X: Type profiling of parameters to methods; "         \
1093           "X, Y and Z in 0=off ; 1=jsr292 only; 2=all methods")             \
1094           constraint(TypeProfileLevelConstraintFunc, AfterErgo)             \
1095                                                                             \
1096   product(int, TypeProfileArgsLimit,     2,                                 \
1097           "max number of call arguments to consider for type profiling")    \
1098           range(0, 16)                                                      \
1099                                                                             \
1100   product(int, TypeProfileParmsLimit,    2,                                 \
1101           "max number of incoming parameters to consider for type profiling"\
1102           ", -1 for all")                                                   \
1103           range(-1, 64)                                                     \
1104                                                                             \
1105   /* statistics */                                                          \
1106   develop(bool, CountCompiledCalls, false,                                  \
1107           "Count method invocations")                                       \
1108                                                                             \
1109   develop(bool, ICMissHistogram, false,                                     \
1110           "Produce histogram of IC misses")                                 \
1111                                                                             \
1112   /* interpreter */                                                         \
1113   product_pd(bool, RewriteBytecodes,                                        \
1114           "Allow rewriting of bytecodes (bytecodes are not immutable)")     \
1115                                                                             \
1116   product_pd(bool, RewriteFrequentPairs,                                    \
1117           "Rewrite frequently used bytecode pairs into a single bytecode")  \
1118                                                                             \
1119   product(bool, PrintInterpreter, false, DIAGNOSTIC,                        \
1120           "Print the generated interpreter code")                           \
1121                                                                             \
1122   product(bool, UseInterpreter, true,                                       \
1123           "Use interpreter for non-compiled methods")                       \
1124                                                                             \
1125   develop(bool, UseFastSignatureHandlers, true,                             \
1126           "Use fast signature handlers for native calls")                   \
1127                                                                             \
1128   product(bool, UseLoopCounter, true,                                       \
1129           "Increment invocation counter on backward branch")                \
1130                                                                             \
1131   product_pd(bool, UseOnStackReplacement,                                   \
1132           "Use on stack replacement, calls runtime if invoc. counter "      \
1133           "overflows in loop")                                              \
1134                                                                             \
1135   develop(bool, TraceOnStackReplacement, false,                             \
1136           "Trace on stack replacement")                                     \
1137                                                                             \
1138   product_pd(bool, PreferInterpreterNativeStubs,                            \
1139           "Use always interpreter stubs for native methods invoked via "    \
1140           "interpreter")                                                    \
1141                                                                             \
1142   develop(bool, CountBytecodes, false,                                      \
1143           "Count number of bytecodes executed")                             \
1144                                                                             \
1145   develop(bool, PrintBytecodeHistogram, false,                              \
1146           "Print histogram of the executed bytecodes")                      \
1147                                                                             \
1148   develop(bool, PrintBytecodePairHistogram, false,                          \
1149           "Print histogram of the executed bytecode pairs")                 \
1150                                                                             \
1151   product(bool, PrintSignatureHandlers, false, DIAGNOSTIC,                  \
1152           "Print code generated for native method signature handlers")      \
1153                                                                             \
1154   develop(bool, VerifyOops, false,                                          \
1155           "Do plausibility checks for oops")                                \
1156                                                                             \
1157   develop(bool, CheckUnhandledOops, false,                                  \
1158           "Check for unhandled oops in VM code")                            \
1159                                                                             \
1160   develop(bool, VerifyJNIFields, trueInDebug,                               \
1161           "Verify jfieldIDs for instance fields")                           \
1162                                                                             \
1163   develop(bool, VerifyFPU, false,                                           \
1164           "Verify FPU state (check for NaN's, etc.)")                       \
1165                                                                             \
1166   develop(bool, VerifyActivationFrameSize, false,                           \
1167           "Verify that activation frame didn't become smaller than its "    \
1168           "minimal size")                                                   \
1169                                                                             \
1170   develop(bool, TraceFrequencyInlining, false,                              \
1171           "Trace frequency based inlining")                                 \
1172                                                                             \
1173   develop_pd(bool, InlineIntrinsics,                                        \
1174           "Use intrinsics in Interpreter that can be statically resolved")  \
1175                                                                             \
1176   product_pd(bool, ProfileInterpreter,                                      \
1177           "Profile at the bytecode level during interpretation")            \
1178                                                                             \
1179   develop_pd(bool, ProfileTraps,                                            \
1180           "Profile deoptimization traps at the bytecode level")             \
1181                                                                             \
1182   product(intx, ProfileMaturityPercentage, 20,                              \
1183           "number of method invocations/branches (expressed as % of "       \
1184           "CompileThreshold) before using the method's profile")            \
1185           range(0, 100)                                                     \
1186                                                                             \
1187   product(bool, PrintMethodData, false, DIAGNOSTIC,                         \
1188           "Print the results of +ProfileInterpreter at end of run")         \
1189                                                                             \
1190   develop(bool, VerifyDataPointer, trueInDebug,                             \
1191           "Verify the method data pointer during interpreter profiling")    \
1192                                                                             \
1193   develop(bool, CrashGCForDumpingJavaThread, false,                         \
1194           "Manually make GC thread crash then dump java stack trace;  "     \
1195           "Test only")                                                      \
1196                                                                             \
1197   /* compilation */                                                         \
1198   product(bool, UseCompiler, true,                                          \
1199           "Use Just-In-Time compilation")                                   \
1200                                                                             \
1201   product(bool, AlwaysCompileLoopMethods, false,                            \
1202           "When using recompilation, never interpret methods "              \
1203           "containing loops")                                               \
1204                                                                             \
1205   product(int,  AllocatePrefetchStyle, 1,                                   \
1206           "0 = no prefetch, "                                               \
1207           "1 = generate prefetch instructions for each allocation, "        \
1208           "2 = use TLAB watermark to gate allocation prefetch, "            \
1209           "3 = generate one prefetch instruction per cache line")           \
1210           range(0, 3)                                                       \
1211                                                                             \
1212   product(int,  AllocatePrefetchDistance, -1,                               \
1213           "Distance to prefetch ahead of allocation pointer. "              \
1214           "-1: use system-specific value (automatically determined")        \
1215           range(-1, 512)                                                    \
1216                                                                             \
1217   product(int,  AllocatePrefetchLines, 3,                                   \
1218           "Number of lines to prefetch ahead of array allocation pointer")  \
1219           range(1, 64)                                                      \
1220                                                                             \
1221   product(int,  AllocateInstancePrefetchLines, 1,                           \
1222           "Number of lines to prefetch ahead of instance allocation "       \
1223           "pointer")                                                        \
1224           range(1, 64)                                                      \
1225                                                                             \
1226   product(int,  AllocatePrefetchStepSize, 16,                               \
1227           "Step size in bytes of sequential prefetch instructions")         \
1228           range(1, 512)                                                     \
1229           constraint(AllocatePrefetchStepSizeConstraintFunc,AfterMemoryInit)\
1230                                                                             \
1231   product(intx,  AllocatePrefetchInstr, 0,                                  \
1232           "Select instruction to prefetch ahead of allocation pointer")     \
1233           constraint(AllocatePrefetchInstrConstraintFunc, AfterMemoryInit)  \
1234                                                                             \
1235   /* deoptimization */                                                      \
1236   product(bool, TraceDeoptimization, false, DIAGNOSTIC,                     \
1237           "Trace deoptimization")                                           \
1238                                                                             \
1239   develop(bool, PrintDeoptimizationDetails, false,                          \
1240           "Print more information about deoptimization")                    \
1241                                                                             \
1242   develop(bool, DebugDeoptimization, false,                                 \
1243           "Tracing various information while debugging deoptimization")     \
1244                                                                             \
1245   product(double, SelfDestructTimer, 0.0,                                   \
1246           "Will cause VM to terminate after a given time "                  \
1247           "(in fractional minutes) "                                        \
1248           "(0.0 means off)")                                                \
1249           range(0.0, (double)max_intx)                                      \
1250                                                                             \
1251   product(int, MaxJavaStackTraceDepth, 1024,                                \
1252           "The maximum number of lines in the stack trace for Java "        \
1253           "exceptions (0 means all)")                                       \
1254           range(0, max_jint/2)                                              \
1255                                                                             \
1256   /* notice: the max range value here is max_jint, not max_intx  */         \
1257   /* because of overflow issue                                   */         \
1258   product(intx, GuaranteedSafepointInterval, 0, DIAGNOSTIC,                 \
1259           "Guarantee a safepoint (at least) every so many milliseconds "    \
1260           "(0 means none)")                                                 \
1261           range(0, max_jint)                                                \
1262                                                                             \
1263   product(intx, ServiceThreadCleanupInterval, 1000, DIAGNOSTIC,             \
1264           "Wake the ServiceThread to do periodic cleanup checks every so "  \
1265           "many milliseconds (0 means none)")                               \
1266           range(0, max_jint)                                                \
1267                                                                             \
1268   product(double, SafepointTimeoutDelay, 10000,                             \
1269           "Delay in milliseconds for option SafepointTimeout; "             \
1270           "supports sub-millisecond resolution with fractional values.")    \
1271           range(0, max_jlongDouble LP64_ONLY(/MICROUNITS))                  \
1272                                                                             \
1273   product(bool, UseSystemMemoryBarrier, false,                              \
1274           "Try to enable system memory barrier if supported by OS")         \
1275                                                                             \
1276   product(intx, NmethodSweepActivity, 4,                                    \
1277           "Removes cold nmethods from code cache if > 0. Higher values "    \
1278           "result in more aggressive sweeping")                             \
1279           range(0, 2000)                                                    \
1280                                                                             \
1281   develop(intx, MallocCatchPtr, -1,                                         \
1282           "Hit breakpoint when mallocing/freeing this pointer")             \
1283                                                                             \
1284   develop(int, StackPrintLimit, 100,                                        \
1285           "number of stack frames to print in VM-level stack dump")         \
1286                                                                             \
1287   product(int, ErrorLogPrintCodeLimit, 3, DIAGNOSTIC,                       \
1288           "max number of compiled code units to print in error log")        \
1289           range(0, VMError::max_error_log_print_code)                       \
1290                                                                             \
1291   develop(int, MaxElementPrintSize, 256,                                    \
1292           "maximum number of elements to print")                            \
1293                                                                             \
1294   develop(int, MaxStringPrintSize, 256,                                     \
1295           "maximum number of characters to print for a java.lang.String "   \
1296           "in the VM. If exceeded, an abridged version of the string is "   \
1297           "printed with the middle of the string elided.")                  \
1298           range(2, O_BUFLEN)                                                \
1299                                                                             \
1300   develop(intx, MaxSubklassPrintSize, 4,                                    \
1301           "maximum number of subklasses to print when printing klass")      \
1302                                                                             \
1303   develop(intx, MaxForceInlineLevel, 100,                                   \
1304           "maximum number of nested calls that are forced for inlining "    \
1305           "(using CompileCommand or marked w/ @ForceInline)")               \
1306           range(0, max_jint)                                                \
1307                                                                             \
1308   develop(intx, MethodHistogramCutoff, 100,                                 \
1309           "The cutoff value for method invocation histogram (+CountCalls)") \
1310                                                                             \
1311   develop(intx, DeoptimizeALotInterval,     5,                              \
1312           "Number of exits until DeoptimizeALot kicks in")                  \
1313                                                                             \
1314   develop(intx, ZombieALotInterval,     5,                                  \
1315           "Number of exits until ZombieALot kicks in")                      \
1316                                                                             \
1317   product(ccstr, MallocLimit, nullptr, DIAGNOSTIC,                          \
1318           "Limit malloc allocation size from VM. Reaching a limit will "    \
1319           "trigger an action (see flag). This feature requires "            \
1320           "NativeMemoryTracking=summary or NativeMemoryTracking=detail."    \
1321           "Usage:"                                                          \
1322           "\"-XX:MallocLimit=<size>[:<flag>]\" sets a total limit."         \
1323           "\"-XX:MallocLimit=<category>:<size>[:<flag>][,<category>:<size>[:<flag>] ...]\"" \
1324           "sets one or more category-specific limits."                      \
1325           "<flag> defines the action upon reaching the limit:"              \
1326           "\"fatal\": end VM with a fatal error at the allocation site"     \
1327           "\"oom\"  : will mimic a native OOM"                              \
1328           "If <flag> is omitted, \"fatal\" is the default."                 \
1329           "Examples:\n"                                                     \
1330           "-XX:MallocLimit=2g"                                              \
1331           "-XX:MallocLimit=2g:oom"                                          \
1332           "-XX:MallocLimit=compiler:200m:oom,code:100m")                    \
1333                                                                             \
1334   product(intx, TypeProfileWidth, 2,                                        \
1335           "Number of receiver types to record in call/cast profile")        \
1336           range(0, 8)                                                       \
1337                                                                             \
1338   develop(intx, BciProfileWidth,      2,                                    \
1339           "Number of return bci's to record in ret profile")                \
1340                                                                             \
1341   product(intx, PerMethodRecompilationCutoff, 400,                          \
1342           "After recompiling N times, stay in the interpreter (-1=>'Inf')") \
1343           range(-1, max_intx)                                               \
1344                                                                             \
1345   product(intx, PerBytecodeRecompilationCutoff, 200,                        \
1346           "Per-BCI limit on repeated recompilation (-1=>'Inf')")            \
1347           range(-1, max_intx)                                               \
1348                                                                             \
1349   product(intx, PerMethodTrapLimit,  100,                                   \
1350           "Limit on traps (of one kind) in a method (includes inlines)")    \
1351           range(0, max_jint)                                                \
1352                                                                             \
1353   product(intx, PerMethodSpecTrapLimit,  5000, EXPERIMENTAL,                \
1354           "Limit on speculative traps (of one kind) in a method "           \
1355           "(includes inlines)")                                             \
1356           range(0, max_jint)                                                \
1357                                                                             \
1358   product(intx, PerBytecodeTrapLimit,  4,                                   \
1359           "Limit on traps (of one kind) at a particular BCI")               \
1360           range(0, max_jint)                                                \
1361                                                                             \
1362   product(int, SpecTrapLimitExtraEntries,  3, EXPERIMENTAL,                 \
1363           "Extra method data trap entries for speculation")                 \
1364                                                                             \
1365   product(double, InlineFrequencyRatio, 0.25, DIAGNOSTIC,                   \
1366           "Ratio of call site execution to caller method invocation")       \
1367                                                                             \
1368   product(double, MinInlineFrequencyRatio, 0.0085, DIAGNOSTIC,              \
1369           "Minimum ratio of call site execution to caller method"           \
1370           "invocation to be considered for inlining")                       \
1371                                                                             \
1372   develop(intx, InlineThrowCount,    50,                                    \
1373           "Force inlining of interpreted methods that throw this often")    \
1374           range(0, max_jint)                                                \
1375                                                                             \
1376   develop(intx, InlineThrowMaxSize,   200,                                  \
1377           "Force inlining of throwing methods smaller than this")           \
1378           range(0, max_jint)                                                \
1379                                                                             \
1380   product(size_t, MetaspaceSize, NOT_LP64(16 * M) LP64_ONLY(21 * M),        \
1381           "Initial threshold (in bytes) at which a garbage collection "     \
1382           "is done to reduce Metaspace usage")                              \
1383           constraint(MetaspaceSizeConstraintFunc,AfterErgo)                 \
1384                                                                             \
1385   product(size_t, MaxMetaspaceSize, max_uintx,                              \
1386           "Maximum size of Metaspaces (in bytes)")                          \
1387           constraint(MaxMetaspaceSizeConstraintFunc,AfterErgo)              \
1388                                                                             \
1389   product(size_t, CompressedClassSpaceSize, 1*G,                            \
1390           "Maximum size of class area in Metaspace when compressed "        \
1391           "class pointers are used")                                        \
1392           range(1*M, LP64_ONLY(4*G) NOT_LP64(max_uintx))                    \
1393                                                                             \
1394   develop(size_t, CompressedClassSpaceBaseAddress, 0,                       \
1395           "Force the class space to be allocated at this address or "       \
1396           "fails VM initialization (requires -Xshare=off.")                 \
1397                                                                             \
1398   develop(bool, RandomizeClassSpaceLocation, true,                          \
1399           "Randomize location of class space.")                             \
1400                                                                             \
1401   product(bool, PrintMetaspaceStatisticsAtExit, false, DIAGNOSTIC,          \
1402           "Print metaspace statistics upon VM exit.")                       \
1403                                                                             \
1404   product(uintx, MinHeapFreeRatio, 40, MANAGEABLE,                          \
1405           "The minimum percentage of heap free after GC to avoid expansion."\
1406           " For most GCs this applies to the old generation. In G1 and"     \
1407           " ParallelGC it applies to the whole heap.")                      \
1408           range(0, 100)                                                     \
1409           constraint(MinHeapFreeRatioConstraintFunc,AfterErgo)              \
1410                                                                             \
1411   product(uintx, MaxHeapFreeRatio, 70, MANAGEABLE,                          \
1412           "The maximum percentage of heap free after GC to avoid shrinking."\
1413           " For most GCs this applies to the old generation. In G1 and"     \
1414           " ParallelGC it applies to the whole heap.")                      \
1415           range(0, 100)                                                     \
1416           constraint(MaxHeapFreeRatioConstraintFunc,AfterErgo)              \
1417                                                                             \
1418   product(intx, SoftRefLRUPolicyMSPerMB, 1000,                              \
1419           "Number of milliseconds per MB of free space in the heap")        \
1420           range(0, max_intx)                                                \
1421           constraint(SoftRefLRUPolicyMSPerMBConstraintFunc,AfterMemoryInit) \
1422                                                                             \
1423   product(size_t, MinHeapDeltaBytes, ScaleForWordSize(128*K),               \
1424           "The minimum change in heap space due to GC (in bytes)")          \
1425           range(0, max_uintx)                                               \
1426                                                                             \
1427   product(size_t, MinMetaspaceExpansion, ScaleForWordSize(256*K),           \
1428           "The minimum expansion of Metaspace (in bytes)")                  \
1429           range(0, max_uintx)                                               \
1430                                                                             \
1431   product(uint, MaxMetaspaceFreeRatio,    70,                               \
1432           "The maximum percentage of Metaspace free after GC to avoid "     \
1433           "shrinking")                                                      \
1434           range(0, 100)                                                     \
1435           constraint(MaxMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1436                                                                             \
1437   product(uint, MinMetaspaceFreeRatio,    40,                               \
1438           "The minimum percentage of Metaspace free after GC to avoid "     \
1439           "expansion")                                                      \
1440           range(0, 99)                                                      \
1441           constraint(MinMetaspaceFreeRatioConstraintFunc,AfterErgo)         \
1442                                                                             \
1443   product(size_t, MaxMetaspaceExpansion, ScaleForWordSize(4*M),             \
1444           "The maximum expansion of Metaspace without full GC (in bytes)")  \
1445           range(0, max_uintx)                                               \
1446                                                                             \
1447   /* stack parameters */                                                    \
1448   product_pd(intx, StackYellowPages,                                        \
1449           "Number of yellow zone (recoverable overflows) pages of size "    \
1450           "4KB. If pages are bigger yellow zone is aligned up.")            \
1451           range(MIN_STACK_YELLOW_PAGES, (DEFAULT_STACK_YELLOW_PAGES+5))     \
1452                                                                             \
1453   product_pd(intx, StackRedPages,                                           \
1454           "Number of red zone (unrecoverable overflows) pages of size "     \
1455           "4KB. If pages are bigger red zone is aligned up.")               \
1456           range(MIN_STACK_RED_PAGES, (DEFAULT_STACK_RED_PAGES+2))           \
1457                                                                             \
1458   product_pd(intx, StackReservedPages,                                      \
1459           "Number of reserved zone (reserved to annotated methods) pages"   \
1460           " of size 4KB. If pages are bigger reserved zone is aligned up.") \
1461           range(MIN_STACK_RESERVED_PAGES, (DEFAULT_STACK_RESERVED_PAGES+10))\
1462                                                                             \
1463   product(bool, RestrictReservedStack, true,                                \
1464           "Restrict @ReservedStackAccess to trusted classes")               \
1465                                                                             \
1466   /* greater stack shadow pages can't generate instruction to bang stack */ \
1467   product_pd(intx, StackShadowPages,                                        \
1468           "Number of shadow zone (for overflow checking) pages of size "    \
1469           "4KB. If pages are bigger shadow zone is aligned up. "            \
1470           "This should exceed the depth of the VM and native call stack.")  \
1471           range(MIN_STACK_SHADOW_PAGES, (DEFAULT_STACK_SHADOW_PAGES+30))    \
1472                                                                             \
1473   product_pd(intx, ThreadStackSize,                                         \
1474           "Thread Stack Size (in Kbytes)")                                  \
1475           range(0, 1 * M)                                                   \
1476                                                                             \
1477   product_pd(intx, VMThreadStackSize,                                       \
1478           "Non-Java Thread Stack Size (in Kbytes)")                         \
1479           range(0, max_intx/(1 * K))                                        \
1480                                                                             \
1481   product_pd(intx, CompilerThreadStackSize,                                 \
1482           "Compiler Thread Stack Size (in Kbytes)")                         \
1483           range(0, max_intx/(1 * K))                                        \
1484                                                                             \
1485   develop_pd(size_t, JVMInvokeMethodSlack,                                  \
1486           "Stack space (bytes) required for JVM_InvokeMethod to complete")  \
1487                                                                             \
1488   /* code cache parameters                                    */            \
1489   product_pd(uintx, CodeCacheSegmentSize, EXPERIMENTAL,                     \
1490           "Code cache segment size (in bytes) - smallest unit of "          \
1491           "allocation")                                                     \
1492           range(1, 1024)                                                    \
1493           constraint(CodeCacheSegmentSizeConstraintFunc, AfterErgo)         \
1494                                                                             \
1495   product_pd(intx, CodeEntryAlignment, EXPERIMENTAL,                        \
1496           "Code entry alignment for generated code (in bytes)")             \
1497           constraint(CodeEntryAlignmentConstraintFunc, AfterErgo)           \
1498                                                                             \
1499   product_pd(intx, OptoLoopAlignment,                                       \
1500           "Align inner loops to zero relative to this modulus")             \
1501           range(1, 128)                                                     \
1502           constraint(OptoLoopAlignmentConstraintFunc, AfterErgo)            \
1503                                                                             \
1504   product_pd(uintx, InitialCodeCacheSize,                                   \
1505           "Initial code cache size (in bytes)")                             \
1506           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1507                                                                             \
1508   develop_pd(uintx, CodeCacheMinimumUseSpace,                               \
1509           "Minimum code cache size (in bytes) required to start VM.")       \
1510           range(0, max_uintx)                                               \
1511                                                                             \
1512   product(bool, SegmentedCodeCache, false,                                  \
1513           "Use a segmented code cache")                                     \
1514                                                                             \
1515   product_pd(uintx, ReservedCodeCacheSize,                                  \
1516           "Reserved code cache size (in bytes) - maximum code cache size")  \
1517           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1518                                                                             \
1519   product_pd(uintx, NonProfiledCodeHeapSize,                                \
1520           "Size of code heap with non-profiled methods (in bytes)")         \
1521           range(0, max_uintx)                                               \
1522                                                                             \
1523   product_pd(uintx, ProfiledCodeHeapSize,                                   \
1524           "Size of code heap with profiled methods (in bytes)")             \
1525           range(0, max_uintx)                                               \
1526                                                                             \
1527   product_pd(uintx, NonNMethodCodeHeapSize,                                 \
1528           "Size of code heap with non-nmethods (in bytes)")                 \
1529           constraint(VMPageSizeConstraintFunc, AtParse)                     \
1530                                                                             \
1531   product_pd(uintx, CodeCacheExpansionSize,                                 \
1532           "Code cache expansion size (in bytes)")                           \
1533           range(32*K, max_uintx)                                            \
1534                                                                             \
1535   product_pd(uintx, CodeCacheMinBlockLength, DIAGNOSTIC,                    \
1536           "Minimum number of segments in a code cache block")               \
1537           range(1, 100)                                                     \
1538                                                                             \
1539   develop(bool, ExitOnFullCodeCache, false,                                 \
1540           "Exit the VM if we fill the code cache")                          \
1541                                                                             \
1542   product(bool, UseCodeCacheFlushing, true,                                 \
1543           "Remove cold/old nmethods from the code cache")                   \
1544                                                                             \
1545   product(double, SweeperThreshold, 15.0,                                   \
1546           "Threshold when a code cache unloading GC is invoked."            \
1547           "Value is percentage of ReservedCodeCacheSize.")                  \
1548           range(0.0, 100.0)                                                 \
1549                                                                             \
1550   product(uintx, StartAggressiveSweepingAt, 10,                             \
1551           "Start aggressive sweeping if X[%] of the code cache is free."    \
1552           "Segmented code cache: X[%] of the non-profiled heap."            \
1553           "Non-segmented code cache: X[%] of the total code cache")         \
1554           range(0, 100)                                                     \
1555                                                                             \
1556   /* interpreter debugging */                                               \
1557   develop(intx, BinarySwitchThreshold, 5,                                   \
1558           "Minimal number of lookupswitch entries for rewriting to binary " \
1559           "switch")                                                         \
1560                                                                             \
1561   develop(intx, StopInterpreterAt, 0,                                       \
1562           "Stop interpreter execution at specified bytecode number")        \
1563                                                                             \
1564   develop(intx, TraceBytecodesAt, 0,                                        \
1565           "Trace bytecodes starting with specified bytecode number")        \
1566                                                                             \
1567   develop(intx, TraceBytecodesStopAt, 0,                                    \
1568           "Stop bytecode tracing at the specified bytecode number")         \
1569                                                                             \
1570   /* Priorities */                                                          \
1571   product_pd(bool, UseThreadPriorities,  "Use native thread priorities")    \
1572                                                                             \
1573   product(int, ThreadPriorityPolicy, 0,                                     \
1574           "0 : Normal.                                                     "\
1575           "    VM chooses priorities that are appropriate for normal       "\
1576           "    applications.                                               "\
1577           "    On Windows applications are allowed to use higher native    "\
1578           "    priorities. However, with ThreadPriorityPolicy=0, VM will   "\
1579           "    not use the highest possible native priority,               "\
1580           "    THREAD_PRIORITY_TIME_CRITICAL, as it may interfere with     "\
1581           "    system threads. On Linux thread priorities are ignored      "\
1582           "    because the OS does not support static priority in          "\
1583           "    SCHED_OTHER scheduling class which is the only choice for   "\
1584           "    non-root, non-realtime applications.                        "\
1585           "1 : Aggressive.                                                 "\
1586           "    Java thread priorities map over to the entire range of      "\
1587           "    native thread priorities. Higher Java thread priorities map "\
1588           "    to higher native thread priorities. This policy should be   "\
1589           "    used with care, as sometimes it can cause performance       "\
1590           "    degradation in the application and/or the entire system. On "\
1591           "    Linux/BSD/macOS this policy requires root privilege or an   "\
1592           "    extended capability.")                                       \
1593           range(0, 1)                                                       \
1594                                                                             \
1595   product(bool, ThreadPriorityVerbose, false,                               \
1596           "Print priority changes")                                         \
1597                                                                             \
1598   product(int, CompilerThreadPriority, -1,                                  \
1599           "The native priority at which compiler threads should run "       \
1600           "(-1 means no change)")                                           \
1601           range(min_jint, max_jint)                                         \
1602                                                                             \
1603   product(int, VMThreadPriority, -1,                                        \
1604           "The native priority at which the VM thread should run "          \
1605           "(-1 means no change)")                                           \
1606           range(-1, 127)                                                    \
1607                                                                             \
1608   product(int, JavaPriority1_To_OSPriority, -1,                             \
1609           "Map Java priorities to OS priorities")                           \
1610           range(-1, 127)                                                    \
1611                                                                             \
1612   product(int, JavaPriority2_To_OSPriority, -1,                             \
1613           "Map Java priorities to OS priorities")                           \
1614           range(-1, 127)                                                    \
1615                                                                             \
1616   product(int, JavaPriority3_To_OSPriority, -1,                             \
1617           "Map Java priorities to OS priorities")                           \
1618           range(-1, 127)                                                    \
1619                                                                             \
1620   product(int, JavaPriority4_To_OSPriority, -1,                             \
1621           "Map Java priorities to OS priorities")                           \
1622           range(-1, 127)                                                    \
1623                                                                             \
1624   product(int, JavaPriority5_To_OSPriority, -1,                             \
1625           "Map Java priorities to OS priorities")                           \
1626           range(-1, 127)                                                    \
1627                                                                             \
1628   product(int, JavaPriority6_To_OSPriority, -1,                             \
1629           "Map Java priorities to OS priorities")                           \
1630           range(-1, 127)                                                    \
1631                                                                             \
1632   product(int, JavaPriority7_To_OSPriority, -1,                             \
1633           "Map Java priorities to OS priorities")                           \
1634           range(-1, 127)                                                    \
1635                                                                             \
1636   product(int, JavaPriority8_To_OSPriority, -1,                             \
1637           "Map Java priorities to OS priorities")                           \
1638           range(-1, 127)                                                    \
1639                                                                             \
1640   product(int, JavaPriority9_To_OSPriority, -1,                             \
1641           "Map Java priorities to OS priorities")                           \
1642           range(-1, 127)                                                    \
1643                                                                             \
1644   product(int, JavaPriority10_To_OSPriority,-1,                             \
1645           "Map Java priorities to OS priorities")                           \
1646           range(-1, 127)                                                    \
1647                                                                             \
1648   product(bool, UseCriticalJavaThreadPriority, false, EXPERIMENTAL,         \
1649           "Java thread priority 10 maps to critical scheduling priority")   \
1650                                                                             \
1651   product(bool, UseCriticalCompilerThreadPriority, false, EXPERIMENTAL,     \
1652           "Compiler thread(s) run at critical scheduling priority")         \
1653                                                                             \
1654   develop(intx, NewCodeParameter,      0,                                   \
1655           "Testing Only: Create a dedicated integer parameter before "      \
1656           "putback")                                                        \
1657                                                                             \
1658   /* new oopmap storage allocation */                                       \
1659   develop(intx, MinOopMapAllocation,     8,                                 \
1660           "Minimum number of OopMap entries in an OopMapSet")               \
1661                                                                             \
1662   /* recompilation */                                                       \
1663   product_pd(intx, CompileThreshold,                                        \
1664           "number of interpreted method invocations before (re-)compiling") \
1665           constraint(CompileThresholdConstraintFunc, AfterErgo)             \
1666                                                                             \
1667   product_pd(bool, TieredCompilation,                                       \
1668           "Enable tiered compilation")                                      \
1669                                                                             \
1670   /* Properties for Java libraries  */                                      \
1671                                                                             \
1672   product(uint64_t, MaxDirectMemorySize, 0,                                 \
1673           "Maximum total size of NIO direct-buffer allocations. "           \
1674           "Ignored if not explicitly set.")                                 \
1675           range(0, max_jlong)                                               \
1676                                                                             \
1677   /* Flags used for temporary code during development  */                   \
1678                                                                             \
1679   product(bool, UseNewCode, false, DIAGNOSTIC,                              \
1680           "Testing Only: Use the new version while testing")                \
1681                                                                             \
1682   product(bool, UseNewCode2, false, DIAGNOSTIC,                             \
1683           "Testing Only: Use the new version while testing")                \
1684                                                                             \
1685   product(bool, UseNewCode3, false, DIAGNOSTIC,                             \
1686           "Testing Only: Use the new version while testing")                \
1687                                                                             \
1688   develop(bool, UseDebuggerErgo, false,                                     \
1689           "Debugging Only: Adjust the VM to be more debugger-friendly. "    \
1690           "Turns on the other UseDebuggerErgo* flags")                      \
1691                                                                             \
1692   develop(bool, UseDebuggerErgo1, false,                                    \
1693           "Debugging Only: Enable workarounds for debugger induced "        \
1694           "os::processor_id() >= os::processor_count() problems")           \
1695                                                                             \
1696   develop(bool, UseDebuggerErgo2, false,                                    \
1697           "Debugging Only: Limit the number of spawned JVM threads")        \
1698                                                                             \
1699   develop(bool, EnableJVMTIStackDepthAsserts, true,                         \
1700           "Enable JVMTI asserts related to stack depth checks")             \
1701                                                                             \
1702   /* flags for performance data collection */                               \
1703                                                                             \
1704   product(bool, UsePerfData, true,                                          \
1705           "Flag to disable jvmstat instrumentation for performance testing "\
1706           "and problem isolation purposes")                                 \
1707                                                                             \
1708   product(bool, PerfDataSaveToFile, false,                                  \
1709           "Save PerfData memory to hsperfdata_<pid> file on exit")          \
1710                                                                             \
1711   product(ccstr, PerfDataSaveFile, nullptr,                                 \
1712           "Save PerfData memory to the specified absolute pathname. "       \
1713           "The string %p in the file name (if present) "                    \
1714           "will be replaced by pid")                                        \
1715                                                                             \
1716   product(int, PerfDataSamplingInterval, 50,                                \
1717           "Data sampling interval (in milliseconds)")                       \
1718           range(PeriodicTask::min_interval, max_jint)                       \
1719           constraint(PerfDataSamplingIntervalFunc, AfterErgo)               \
1720                                                                             \
1721   product(bool, PerfDisableSharedMem, false,                                \
1722           "Store performance data in standard memory")                      \
1723                                                                             \
1724   product(int, PerfDataMemorySize, 32*K,                                    \
1725           "Size of performance data memory region. Will be rounded "        \
1726           "up to a multiple of the native os page size.")                   \
1727           range(128, 32*64*K)                                               \
1728                                                                             \
1729   product(int, PerfMaxStringConstLength, 1024,                              \
1730           "Maximum PerfStringConstant string length before truncation")     \
1731           range(32, 32*K)                                                   \
1732                                                                             \
1733   product(bool, PerfAllowAtExitRegistration, false,                         \
1734           "Allow registration of atexit() methods")                         \
1735                                                                             \
1736   product(bool, PerfBypassFileSystemCheck, false,                           \
1737           "Bypass Win32 file system criteria checks (Windows Only)")        \
1738                                                                             \
1739   product(int, UnguardOnExecutionViolation, 0,                              \
1740           "Unguard page and retry on no-execute fault (Win32 only) "        \
1741           "0=off, 1=conservative, 2=aggressive")                            \
1742           range(0, 2)                                                       \
1743                                                                             \
1744   /* Serviceability Support */                                              \
1745                                                                             \
1746   product(bool, ManagementServer, false,                                    \
1747           "Create JMX Management Server")                                   \
1748                                                                             \
1749   product(bool, DisableAttachMechanism, false,                              \
1750           "Disable mechanism that allows tools to attach to this VM")       \
1751                                                                             \
1752   product(bool, StartAttachListener, false,                                 \
1753           "Always start Attach Listener at VM startup")                     \
1754                                                                             \
1755   product(bool, EnableDynamicAgentLoading, true,                            \
1756           "Allow tools to load agents with the attach mechanism")           \
1757                                                                             \
1758   product(bool, PrintConcurrentLocks, false, MANAGEABLE,                    \
1759           "Print java.util.concurrent locks in thread dump")                \
1760                                                                             \
1761   product(bool, PrintMethodHandleStubs, false, DIAGNOSTIC,                  \
1762           "Print generated stub code for method handles")                   \
1763                                                                             \
1764   product(bool, VerifyMethodHandles, trueInDebug, DIAGNOSTIC,               \
1765           "perform extra checks when constructing method handles")          \
1766                                                                             \
1767   product(bool, ShowHiddenFrames, false, DIAGNOSTIC,                        \
1768           "show method handle implementation frames (usually hidden)")      \
1769                                                                             \
1770   product(bool, ShowCarrierFrames, false, DIAGNOSTIC,                       \
1771           "show virtual threads' carrier frames in exceptions")             \
1772                                                                             \
1773   product(bool, TrustFinalNonStaticFields, false, EXPERIMENTAL,             \
1774           "trust final non-static declarations for constant folding")       \
1775                                                                             \
1776   product(bool, FoldStableValues, true, DIAGNOSTIC,                         \
1777           "Optimize loads from stable fields (marked w/ @Stable)")          \
1778                                                                             \
1779   product(int, UseBootstrapCallInfo, 1, DIAGNOSTIC,                         \
1780           "0: when resolving InDy or ConDy, force all BSM arguments to be " \
1781           "resolved before the bootstrap method is called; 1: when a BSM "  \
1782           "that may accept a BootstrapCallInfo is detected, use that API "  \
1783           "to pass BSM arguments, which allows the BSM to delay their "     \
1784           "resolution; 2+: stress test the BCI API by calling more BSMs "   \
1785           "via that API, instead of with the eagerly-resolved array.")      \
1786                                                                             \
1787   product(bool, PauseAtStartup,      false, DIAGNOSTIC,                     \
1788           "Causes the VM to pause at startup time and wait for the pause "  \
1789           "file to be removed (default: ./vm.paused.<pid>)")                \
1790                                                                             \
1791   product(ccstr, PauseAtStartupFile, nullptr, DIAGNOSTIC,                      \
1792           "The file to create and for whose removal to await when pausing " \
1793           "at startup. (default: ./vm.paused.<pid>)")                       \
1794                                                                             \
1795   product(bool, PauseAtExit, false, DIAGNOSTIC,                             \
1796           "Pause and wait for keypress on exit if a debugger is attached")  \
1797                                                                             \
1798   product(bool, DTraceMethodProbes, false,                                  \
1799           "Enable dtrace tool probes for method-entry and method-exit")     \
1800                                                                             \
1801   product(bool, DTraceAllocProbes, false,                                   \
1802           "Enable dtrace tool probes for object allocation")                \
1803                                                                             \
1804   product(bool, DTraceMonitorProbes, false,                                 \
1805           "Enable dtrace tool probes for monitor events")                   \
1806                                                                             \
1807   product(bool, RelaxAccessControlCheck, false,                             \
1808           "Relax the access control checks in the verifier")                \
1809                                                                             \
1810   product(uintx, StringTableSize, defaultStringTableSize,                   \
1811           "Number of buckets in the interned String table "                 \
1812           "(will be rounded to nearest higher power of 2)")                 \
1813           range(minimumStringTableSize, 16777216ul /* 2^24 */)              \
1814                                                                             \
1815   product(uintx, SymbolTableSize, defaultSymbolTableSize, EXPERIMENTAL,     \
1816           "Number of buckets in the JVM internal Symbol table")             \
1817           range(minimumSymbolTableSize, 16777216ul /* 2^24 */)              \
1818                                                                             \
1819   product(bool, UseStringDeduplication, false,                              \
1820           "Use string deduplication")                                       \
1821                                                                             \
1822   product(uint, StringDeduplicationAgeThreshold, 3,                         \
1823           "A string must reach this age (or be promoted to an old region) " \
1824           "to be considered for deduplication")                             \
1825           range(1, markWord::max_age)                                       \
1826                                                                             \
1827   product(size_t, StringDeduplicationInitialTableSize, 500, EXPERIMENTAL,   \
1828           "Approximate initial number of buckets in the table")             \
1829           range(1, 1 * G)                                                   \
1830                                                                             \
1831   product(double, StringDeduplicationGrowTableLoad, 14.0, EXPERIMENTAL,     \
1832           "Entries per bucket above which the table should be expanded")    \
1833           range(0.1, 1000.0)                                                \
1834                                                                             \
1835   product(double, StringDeduplicationShrinkTableLoad, 1.0, EXPERIMENTAL,    \
1836           "Entries per bucket below which the table should be shrunk")      \
1837           range(0.01, 100.0)                                                \
1838                                                                             \
1839   product(double, StringDeduplicationTargetTableLoad, 7.0, EXPERIMENTAL,    \
1840           "Desired entries per bucket when resizing the table")             \
1841           range(0.01, 1000.0)                                               \
1842                                                                             \
1843   product(size_t, StringDeduplicationCleanupDeadMinimum, 100, EXPERIMENTAL, \
1844           "Minimum number of dead table entries for cleaning the table")    \
1845                                                                             \
1846   product(int, StringDeduplicationCleanupDeadPercent, 5, EXPERIMENTAL,      \
1847           "Minimum percentage of dead table entries for cleaning the table") \
1848           range(1, 100)                                                     \
1849                                                                             \
1850   product(bool, StringDeduplicationResizeALot, false, DIAGNOSTIC,           \
1851           "Force more frequent table resizing")                             \
1852                                                                             \
1853   product(uint64_t, StringDeduplicationHashSeed, 0, DIAGNOSTIC,             \
1854           "Seed for the table hashing function; 0 requests computed seed")  \
1855                                                                             \
1856   product(bool, WhiteBoxAPI, false, DIAGNOSTIC,                             \
1857           "Enable internal testing APIs")                                   \
1858                                                                             \
1859   product(bool, AlwaysAtomicAccesses, false, EXPERIMENTAL,                  \
1860           "Accesses to all variables should always be atomic")              \
1861                                                                             \
1862   product(bool, UseUnalignedAccesses, false, DIAGNOSTIC,                    \
1863           "Use unaligned memory accesses in Unsafe")                        \
1864                                                                             \
1865   product_pd(bool, PreserveFramePointer,                                    \
1866              "Use the FP register for holding the frame pointer "           \
1867              "and not as a general purpose register.")                      \
1868                                                                             \
1869   product(size_t, AsyncLogBufferSize, 2*M,                                  \
1870           "Memory budget (in bytes) for the buffer of Asynchronous "        \
1871           "Logging (-Xlog:async).")                                         \
1872           range(100*K, 50*M)                                                \
1873                                                                             \
1874   product(bool, CheckIntrinsics, true, DIAGNOSTIC,                          \
1875              "When a class C is loaded, check that "                        \
1876              "(1) all intrinsics defined by the VM for class C are present "\
1877              "in the loaded class file and are marked with the "            \
1878              "@IntrinsicCandidate annotation, that "                        \
1879              "(2) there is an intrinsic registered for all loaded methods " \
1880              "that are annotated with the @IntrinsicCandidate annotation, " \
1881              "and that "                                                    \
1882              "(3) no orphan methods exist for class C (i.e., methods for "  \
1883              "which the VM declares an intrinsic but that are not declared "\
1884              "in the loaded class C. "                                      \
1885              "Check (3) is available only in debug builds.")                \
1886                                                                             \
1887   product_pd(intx, InitArrayShortSize, DIAGNOSTIC,                          \
1888           "Threshold small size (in bytes) for clearing arrays. "           \
1889           "Anything this size or smaller may get converted to discrete "    \
1890           "scalar stores.")                                                 \
1891           range(0, max_intx)                                                \
1892           constraint(InitArrayShortSizeConstraintFunc, AfterErgo)           \
1893                                                                             \
1894   product(ccstr, AllocateHeapAt, nullptr,                                   \
1895           "Path to the directory where a temporary file will be created "   \
1896           "to use as the backing store for Java Heap.")                     \
1897                                                                             \
1898   product_pd(bool, VMContinuations, EXPERIMENTAL,                           \
1899           "Enable VM continuations support")                                \
1900                                                                             \
1901   develop(bool, LoomDeoptAfterThaw, false,                                  \
1902           "Deopt stack after thaw")                                         \
1903                                                                             \
1904   develop(bool, LoomVerifyAfterThaw, false,                                 \
1905           "Verify stack after thaw")                                        \
1906                                                                             \
1907   develop(bool, VerifyContinuations, false,                                 \
1908           "Verify continuation consistency")                                \
1909                                                                             \
1910   develop(bool, UseContinuationFastPath, true,                              \
1911           "Use fast-path frame walking in continuations")                   \
1912                                                                             \
1913   develop(int, VerifyMetaspaceInterval, DEBUG_ONLY(500) NOT_DEBUG(0),       \
1914                "Run periodic metaspace verifications (0 - none, "           \
1915                "1 - always, >1 every nth interval)")                        \
1916                                                                             \
1917   product(bool, ShowRegistersOnAssert, true, DIAGNOSTIC,                    \
1918           "On internal errors, include registers in error report.")         \
1919                                                                             \
1920   product(bool, UseSwitchProfiling, true, DIAGNOSTIC,                       \
1921           "leverage profiling for table/lookup switch")                     \
1922                                                                             \
1923   develop(bool, TraceMemoryWriteback, false,                                \
1924           "Trace memory writeback operations")                              \
1925                                                                             \
1926   JFR_ONLY(product(bool, FlightRecorder, false,                             \
1927           "(Deprecated) Enable Flight Recorder"))                           \
1928                                                                             \
1929   JFR_ONLY(product(ccstr, FlightRecorderOptions, nullptr,                   \
1930           "Flight Recorder options"))                                       \
1931                                                                             \
1932   JFR_ONLY(product(ccstr, StartFlightRecording, nullptr,                    \
1933           "Start flight recording with options"))                           \
1934                                                                             \
1935   product(bool, UseFastUnorderedTimeStamps, false, EXPERIMENTAL,            \
1936           "Use platform unstable time where supported for timestamps only") \
1937                                                                             \
1938   product(bool, DeoptimizeNMethodBarriersALot, false, DIAGNOSTIC,           \
1939                 "Make nmethod barriers deoptimise a lot.")                  \
1940                                                                             \
1941   develop(bool, VerifyCrossModifyFence,                                     \
1942           false AARCH64_ONLY(DEBUG_ONLY(||true)),                           \
1943              "Mark all threads after a safepoint, and clear on a modify "   \
1944              "fence. Add cleanliness checks.")                              \
1945                                                                             \
1946   product(int, LockingMode, LM_LIGHTWEIGHT,                                 \
1947           "(Deprecated) Select locking mode: "                              \
1948           "0: (Deprecated) monitors only (LM_MONITOR), "                    \
1949           "1: (Deprecated) monitors & legacy stack-locking (LM_LEGACY), "   \
1950           "2: monitors & new lightweight locking (LM_LIGHTWEIGHT, default)") \
1951           range(0, 2)                                                       \
1952                                                                             \
1953   product(bool, UseObjectMonitorTable, false, DIAGNOSTIC,                   \
1954           "With Lightweight Locking mode, use a table to record inflated "  \
1955           "monitors rather than the first word of the object.")             \
1956                                                                             \
1957   product(int, LightweightFastLockingSpins, 13, DIAGNOSTIC,                 \
1958           "Specifies the number of times lightweight fast locking will "    \
1959           "attempt to CAS the markWord before inflating. Between each "     \
1960           "CAS it will spin for exponentially more time, resulting in "     \
1961           "a total number of spins on the order of O(2^value)")             \
1962           range(1, 30)                                                      \
1963                                                                             \
1964   product(uint, TrimNativeHeapInterval, 0,                                  \
1965           "Interval, in ms, at which the JVM will trim the native heap if " \
1966           "the platform supports that. Lower values will reclaim memory "   \
1967           "more eagerly at the cost of higher overhead. A value of 0 "      \
1968           "(default) disables native heap trimming.")                       \
1969           range(0, UINT_MAX)                                                \
1970                                                                             \
1971   develop(bool, SimulateFullAddressSpace, false,                            \
1972           "Simulates a very populated, fragmented address space; no "       \
1973           "targeted reservations will succeed.")                            \
1974                                                                             \
1975   product(bool, ProfileExceptionHandlers, true,                             \
1976           "Profile exception handlers")                                     \
1977                                                                             \
1978   product(bool, AlwaysRecordEvolDependencies, true, EXPERIMENTAL,           \
1979                 "Unconditionally record nmethod dependencies on class "     \
1980                 "rewriting/transformation independently of the JVMTI "      \
1981                 "can_{retransform/redefine}_classes capabilities.")         \
1982                                                                             \
1983   product(bool, UseSecondarySupersCache, true, DIAGNOSTIC,                  \
1984                 "Use secondary supers cache during subtype checks.")        \
1985                                                                             \
1986   product(bool, UseSecondarySupersTable, false, DIAGNOSTIC,                 \
1987                 "Use hash table to lookup secondary supers.")               \
1988                                                                             \
1989   product(bool, VerifySecondarySupers, false, DIAGNOSTIC,                   \
1990           "Check that linear and hashed secondary lookups return the same result.") \
1991                                                                             \
1992   product(bool, StressSecondarySupers, false, DIAGNOSTIC,                   \
1993           "Use a terrible hash function in order to generate many collisions.") \
1994                                                                             \
1995   product(bool, UseThreadsLockThrottleLock, true, DIAGNOSTIC,               \
1996           "Use an extra lock during Thread start and exit to alleviate"     \
1997           "contention on Threads_lock.")                                    \
1998 
1999 // end of RUNTIME_FLAGS
2000 
2001 DECLARE_FLAGS(LP64_RUNTIME_FLAGS)
2002 DECLARE_ARCH_FLAGS(ARCH_FLAGS)
2003 DECLARE_FLAGS(RUNTIME_FLAGS)
2004 DECLARE_FLAGS(RUNTIME_OS_FLAGS)
2005 
2006 #endif // SHARE_RUNTIME_GLOBALS_HPP