[Webkit-unassigned] [Bug 90420] New: JSC: Add ability to symbolically set and dump JSC VM options

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=90420

           Summary: JSC: Add ability to symbolically set and dump JSC VM
                    options
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: mark.lam at apple.com


It would be nice to be able to set VM options (and verify them) from the jsc command line.  This will make it easier to adjust VM heuristics for testing and tuning purposes without having to recompile JSC.

For example, to do a test run with the DFG disabled, one should be run jsc from the command line as follows:
$ jsc --useDFGJIT=false

Another example, to shows the default values for the VM settings:
$ jsc --options
JSC runtime options:
   useJIT: true
   useDFGJIT: true
   showDisassembly: false
   showDFGDisassembly: false
   maximumOptimizationCandidateInstructionCount: 10000
   maximumFunctionForCallInlineCandidateInstructionCount: 180
   maximumFunctionForConstructInlineCandidateInstructionCount: 100
   maximumInliningDepth: 5
   thresholdForJITAfterWarmUp: 100
   thresholdForJITSoon: 100
   thresholdForOptimizeAfterWarmUp: 1000
   thresholdForOptimizeAfterLongWarmUp: 5000
   thresholdForOptimizeSoon: 1000
   executionCounterIncrementForLoop: 1
   executionCounterIncrementForReturn: 15
   randomizeExecutionCountsBetweenCheckpoints: false
   maximumExecutionCountsBetweenCheckpoints: 1000
   likelyToTakeSlowCaseThreshold: 0.150000
   couldTakeSlowCaseThreshold: 0.050000
   likelyToTakeSlowCaseMinimumCount: 100
   couldTakeSlowCaseMinimumCount: 10
   osrExitProminenceForFrequentExitSite: 0.300000
   osrExitCountForReoptimization: 100
   osrExitCountForReoptimizationFromLoop: 5
   reoptimizationRetryCounterMax: 18
   reoptimizationRetryCounterStep: 1
   minimumOptimizationDelay: 1
   maximumOptimizationDelay: 5
   desiredProfileLivenessRate: 0.750000
   desiredProfileFullnessRate: 0.350000
   doubleVoteRatioForDoubleFormat: 2.000000
   minimumNumberOfScansBetweenRebalance: 100
   gcMarkStackSegmentSize: 4096
   numberOfGCMarkers: 7
   opaqueRootMergeThreshold: 1000
   forceWeakRandomSeed: false
   forcedWeakRandomSeed: 0

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