Vm-dev May 2015

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New Cog VMs available
by Eliot Miranda 06 May '15

06 May '15

... at http://www.mirandabanda.org/files/Cog/VM/VM.r3319. CogVM binaries as per VMMaker.oscog-eem.1288/r3319 Spur: Implement remembered table pruning via ref counts. The algorithm selectively tenures objects to reduce the remembered table, instead of merely tenuring everything. Be selective about remembering tenured objects; actually scan their contents before remembering willy-nilly. StackVM: Allow setting preemptionYields in the stack VM. Cogit: Use new register allocation in #== with V3 in order to limit register moves. -- best, Eliot

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VM Maker: VMMaker.oscog-eem.1291.mcz
by commits＠source.squeak.org 06 May '15

06 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-eem.1291.mcz ==================== Summary ==================== Name: VMMaker.oscog-eem.1291 Author: eem Time: 6 May 2015, 10:41:54.305 am UUID: 522d9b4a-a938-488b-ae43-6b4ccdd13d5c Ancestors: VMMaker.oscog-cb.1290 Change computeRefCountToShrinkRT to - compute the ref counts and population in a single pass over the RT - determine the ref count for tenuring based on half the population of remembered objects, /not/ half the size of the RT. =============== Diff against VMMaker.oscog-cb.1290 =============== Item was changed: ----- Method: SpurGenerationScavenger>>computeRefCountToShrinkRT (in category 'remembered set') ----- computeRefCountToShrinkRT "Some time in every scavenger's life there may come a time when someone writes code that stresses the remembered table. One might conclude that if the remembered table is full, then the right thing to do is simply to tenure everything, emptying the remembered table. Bt in some circumstances this can be counter-productive, and result in the same situation arising soon after tenuring everything. Instead, we can try and selectively prune the remembered table, tenuring only those objects that are referenced by many objects in the remembered table. That's what this algorithm does. It reference counts young objects referenced from the remembered set, and then sets a threshold used to tenure objects oft referenced from the remembered set, thereby allowing the remembered set to shrink, while not tenuring everything. Once in a network monitoring application in a galaxy not dissimilar from the one this code inhabits, a tree of nodes referring to large integers was in precisely this situation. The nodes were old, and the integers were in new space. Some of the nodes referred to shared numbers, some their own unique numbers. The numbers were updated frequently. Were new space simply tenured when the remembered table was full, the remembered table would soon fill up as new numbers were computed. Only by selectively pruning the remembered table of nodes that shared data, was a balance achieved whereby the remembered table population was kept small, and tenuring rates were low." <inline: #never> + | population | + <var: 'population' declareC: 'long population[MaxRTRefCount + 1]'> + self cCode: [self me: population ms: 0 et: (self sizeof: #long) * (MaxRTRefCount + 1)] + inSmalltalk: [population := CArrayAccessor on: (Array new: MaxRTRefCount + 1 withAll: 0)]. - | counts | - <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> - self cCode: '' inSmalltalk: [counts := CArrayAccessor on: (Array new: MaxRTRefCount + 1)]. self assert: self allNewSpaceObjectsHaveZeroRTRefCount. + self referenceCountRememberedReferents: population. + self setRefCountToShrinkRT: population + + "For debugging: + (manager allNewSpaceObjectsDo: [:o| manager rtRefCountOf: o put: 0])"! - self referenceCountRememberedReferents. - self totalRememberedReferentCounts: counts. - self setRefCountToShrinkRT: counts! Item was removed: - ----- Method: SpurGenerationScavenger>>referenceCountRememberedReferents (in category 'remembered set') ----- - referenceCountRememberedReferents - "Reference count each referent of the remembered table using the rtRefCount - field comprised of isGrey,isPinned,isRemembered. i.e. produce a reference - count from 1 to 7 in all objects accessible from the RT." - <inline: true> - 0 to: rememberedSetSize - 1 do: - [:i| | elephant | - elephant := rememberedSet at: i. - 0 to: (manager numPointerSlotsOf: elephant) - 1 do: - [:j| | referent refCount | - referent := manager fetchPointer: j ofObject: elephant. - (manager isReallyYoung: referent) ifTrue: - [refCount := manager rtRefCountOf: referent. - (refCount := refCount + 1) <= MaxRTRefCount ifTrue: - [manager rtRefCountOf: referent put: refCount]]]]! Item was added: + ----- Method: SpurGenerationScavenger>>referenceCountRememberedReferents: (in category 'remembered set') ----- + referenceCountRememberedReferents: population + "Both reference count young objects reachable from the RT, + and count the populations of each ref count, in a single pass." + <var: 'population' declareC: 'long population[MaxRTRefCount + 1]'> + <inline: true> + 0 to: rememberedSetSize - 1 do: + [:i| | elephant | + elephant := rememberedSet at: i. + 0 to: (manager numPointerSlotsOf: elephant) - 1 do: + [:j| | referent refCount | + referent := manager fetchPointer: j ofObject: elephant. + (manager isReallyYoung: referent) ifTrue: + [refCount := manager rtRefCountOf: referent. + refCount < MaxRTRefCount ifTrue: + [refCount > 0 ifTrue: + [population at: refCount put: (population at: refCount) - 1]. + refCount := refCount + 1. + manager rtRefCountOf: referent put: refCount. + population at: refCount put: (population at: refCount) + 1]]]].! Item was changed: ----- Method: SpurGenerationScavenger>>setRefCountToShrinkRT: (in category 'remembered set') ----- + setRefCountToShrinkRT: population + "Choose a refCount that should shrink the rt by at least half. + i.e. find the maximum reference count that half the population have at least." + <var: 'population' declareC: 'long population[MaxRTRefCount + 1]'> - setRefCountToShrinkRT: counts - "Choose a refCount that will shrink the rt by at least half." - <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> <inline: true> + | entirePopulation i count | + self assert: (population at: 0) = 0. + entirePopulation := 0. + 1 to: MaxRTRefCount do: + [:j| entirePopulation := entirePopulation + (population at: j)]. - | i count | count := 0. i := MaxRTRefCount + 1. + [count < (entirePopulation // 2) and: [(i := i - 1) >= 0]] whileTrue: + [count := count + (population at: i)]. - [count < (rememberedSetSize // 2) and: [(i := i - 1) >= 0]] whileTrue: - [count := count + (counts at: i)]. refCountToShrinkRT := i max: 0! Item was removed: - ----- Method: SpurGenerationScavenger>>totalRememberedReferentCounts: (in category 'remembered set') ----- - totalRememberedReferentCounts: counts - <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> - <inline: true> - 0 to: MaxRTRefCount do: - [:i| counts at: i put: 0]. - 0 to: rememberedSetSize - 1 do: - [:i| | elephant | - elephant := rememberedSet at: i. - 0 to: (manager numPointerSlotsOf: elephant) - 1 do: - [:j| | referent refCount | - referent := manager fetchPointer: j ofObject: elephant. - (manager isReallyYoung: referent) ifTrue: - [refCount := manager rtRefCountOf: referent. - counts at: refCount put: (counts at: refCount) + 1]]]!

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VM Maker: VMMaker.oscog-cb.1290.mcz
by commits＠source.squeak.org 06 May '15

06 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1290.mcz ==================== Summary ==================== Name: VMMaker.oscog-cb.1290 Author: cb Time: 6 May 2015, 11:05:39.237 am UUID: bfb69f82-a7f2-42e8-b375-32586dc89270 Ancestors: VMMaker.oscog-cb.1289 Removed the storeCheck in inlined pointer at:put: if the value stored is an unannotatable constant. I believe this is important in some cases I found where an array was initialized with 0 or false in all its slots. =============== Diff against VMMaker.oscog-cb.1289 =============== Item was changed: ----- Method: StackToRegisterMappingCogit>>genTrinaryInlinePrimitive: (in category 'inline primitive generators') ----- genTrinaryInlinePrimitive: prim "Unary inline primitives." "SistaV1: 248 11111000 iiiiiiii mjjjjjjj Call Primitive #iiiiiiii + (jjjjjjj * 256) m=1 means inlined primitive, no hard return after execution. See EncoderForSistaV1's class comment and StackInterpreter>>#trinaryInlinePrimitive:" + | ra1 ra2 rr adjust needsStoreCheck | - | ra1 ra2 rr adjust | "The store check requires rr to be ReceiverResultReg" self allocateRegForStackTopThreeEntriesInto: [:rTop :rNext :rThird | ra2 := rTop. ra1 := rNext. rr := rThird ] thirdIsReceiver: prim = 0. self assert: (rr ~= ra1 and: [rr ~= ra2 and: [ra1 ~= ra2]]). + needsStoreCheck := (objectRepresentation isUnannotatableConstant: self ssTop) not. self ssTop popToReg: ra2. self ssPop: 1. self ssTop popToReg: ra1. self ssPop: 1. self ssTop popToReg: rr. self ssPop: 1. objectRepresentation genConvertSmallIntegerToIntegerInReg: ra1. "Now: ra is the variable object, rr is long, TempReg holds the value to store." prim caseOf: { "0 - 1 pointerAt:put: and byteAt:Put:" [0] -> [ adjust := (objectMemory baseHeaderSize >> objectMemory shiftForWord) - 1. "shift by baseHeaderSize and then move from 1 relative to zero relative" adjust ~= 0 ifTrue: [ self AddCq: adjust R: ra1. ]. self MoveR: ra2 Xwr: ra1 R: rr. + "I added needsStoreCheck so if you initialize an array with a Smi such as 0 or a boolean you don't need the store check" + needsStoreCheck ifTrue: + [ self assert: needsFrame. + objectRepresentation genStoreCheckReceiverReg: rr valueReg: ra2 scratchReg: TempReg inFrame: true] ]. - objectRepresentation genStoreCheckReceiverReg: rr valueReg: ra2 scratchReg: TempReg inFrame: true]. [1] -> [ objectRepresentation genConvertSmallIntegerToIntegerInReg: ra2. adjust := objectMemory baseHeaderSize - 1. "shift by baseHeaderSize and then move from 1 relative to zero relative" self AddCq: adjust R: ra1. self MoveR: ra2 Xbr: ra1 R: rr. objectRepresentation genConvertIntegerToSmallIntegerInReg: ra2. ] } otherwise: [^EncounteredUnknownBytecode]. self ssPushRegister: ra2. ^0!

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VM Maker: VMMaker.oscog-cb.1289.mcz
by commits＠source.squeak.org 06 May '15

06 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1289.mcz ==================== Summary ==================== Name: VMMaker.oscog-cb.1289 Author: cb Time: 6 May 2015, 9:26:52.521 am UUID: e7a5f914-5989-4493-8941-936984bdd80a Ancestors: VMMaker.oscog-eem.1288 Increased the opcode size heuristic in the SistaCogit. Maybe I'll figure out something better if I rewrite the #== logic. =============== Diff against VMMaker.oscog-eem.1288 =============== Item was changed: ----- Method: Cogit>>compileCogMethod: (in category 'compile abstract instructions') ----- compileCogMethod: selector <returnTypeC: #'CogMethod *'> | numBytecodes numBlocks numCleanBlocks result extra | hasYoungReferent := (objectMemory isYoungObject: methodObj) or: [objectMemory isYoung: selector]. methodOrBlockNumArgs := coInterpreter argumentCountOf: methodObj. inBlock := false. primInvokeLabel := nil. postCompileHook := nil. maxLitIndex := -1. extra := ((primitiveIndex := coInterpreter primitiveIndexOf: methodObj) > 0 and: [(coInterpreter isQuickPrimitiveIndex: primitiveIndex) not]) ifTrue: [30] ifFalse: [10]. initialPC := coInterpreter startPCOfMethod: methodObj. "initial estimate. Actual endPC is determined in scanMethod." endPC := (coInterpreter isQuickPrimitiveIndex: primitiveIndex) ifTrue: [initialPC - 1] ifFalse: [objectMemory numBytesOf: methodObj]. numBytecodes := endPC - initialPC + 1. + self allocateOpcodes: (numBytecodes + extra) * self estimateOfAbstractOpcodesPerBytecodes - self allocateOpcodes: (numBytecodes + extra) * 10 bytecodes: numBytecodes ifFail: [^coInterpreter cCoerceSimple: MethodTooBig to: #'CogMethod *']. (numBlocks := self scanMethod) < 0 ifTrue: [^coInterpreter cCoerceSimple: numBlocks to: #'CogMethod *']. numCleanBlocks := self scanForCleanBlocks. self allocateBlockStarts: numBlocks + numCleanBlocks. blockCount := 0. numCleanBlocks > 0 ifTrue: [self addCleanBlockStarts]. (self maybeAllocAndInitCounters and: [self maybeAllocAndInitIRCs]) ifFalse: "Inaccurate error code, but it'll do. This will likely never fail." [^coInterpreter cCoerceSimple: InsufficientCodeSpace to: #'CogMethod *']. blockEntryLabel := nil. methodLabel dependent: nil. (result := self compileEntireMethod) < 0 ifTrue: [^coInterpreter cCoerceSimple: result to: #'CogMethod *']. ^self generateCogMethod: selector! Item was added: + ----- Method: Cogit>>estimateOfAbstractOpcodesPerBytecodes (in category 'accessing') ----- + estimateOfAbstractOpcodesPerBytecodes + <inline: true> + ^ 10! Item was added: + ----- Method: SistaStackToRegisterMappingCogit>>estimateOfAbstractOpcodesPerBytecodes (in category 'accessing') ----- + estimateOfAbstractOpcodesPerBytecodes + "Due to the counter logic, the estimation is higher" + <inline: true> + self flag: 'we could fix that when #== generates less instructions'. + ^ 14!

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VM Maker: VMMaker.oscog-eem.1288.mcz
by commits＠source.squeak.org 06 May '15

06 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-eem.1288.mcz ==================== Summary ==================== Name: VMMaker.oscog-eem.1288 Author: eem Time: 5 May 2015, 8:16:46.533 pm UUID: 909625f0-4d63-4a3b-84e1-1f2753923d7e Ancestors: VMMaker.oscog-eem.1287 Implement remembered table pruning via ref counts. The algorithm selectively tenures objects to reduce the remembered table, instead of merely tenuring everything. Be selective about remembering tenurted objects; actually scan their contents before remembering willy-nilly. Nuke obsolete copyToOldSpace: methods. =============== Diff against VMMaker.oscog-eem.1287 =============== Item was added: + ----- Method: Spur32BitMemoryManager>>rtRefCountOf:put: (in category 'header access') ----- + rtRefCountOf: obj put: refCount + "Set the rt reference count of obj; this is the three bit field comprised + of isGrey,isPinned,isRemembered. See computeRefCountToShrinkRT." + | header | + self assert: (refCount between: 0 and: MaxRTRefCount). + header := self longAt: obj. + header := header bitAnd: (7 << self rememberedBitShift) bitInvert32. + header := header + (refCount << self rememberedBitShift). + self longAt: obj put: header! Item was added: + ----- Method: Spur64BitMemoryManager>>rtRefCountOf:put: (in category 'header access') ----- + rtRefCountOf: obj put: refCount + "Set the rt reference count of obj; this is the three bit field comprised + of isGrey,isPinned,isRemembered. See computeRefCountToShrinkRT." + | header | + self assert: (refCount between: 0 and: MaxRTRefCount). + header := self longAt: obj. + header := header bitAnd: (7 << self rememberedBitShift) bitInvert64. + header := header + (refCount << self rememberedBitShift). + self longAt: obj put: header! Item was changed: CogClass subclass: #SpurGenerationScavenger + instanceVariableNames: 'coInterpreter manager eden futureSpace pastSpace futureSurvivorStart rememberedSet rememberedSetSize previousRememberedSetSize rememberedSetRedZone rememberedSetLimit refCountToShrinkRT weakList ephemeronList tenureCriterion tenureThreshold tenuringClassIndex tenuringProportion numRememberedEphemerons statTenures' - instanceVariableNames: 'coInterpreter manager eden futureSpace pastSpace futureSurvivorStart rememberedSet rememberedSetSize previousRememberedSetSize rememberedSetRedZone rememberedSetLimit weakList ephemeronList tenureCriterion tenureThreshold tenuringClassIndex tenuringProportion numRememberedEphemerons statTenures' classVariableNames: '' poolDictionaries: 'SpurMemoryManagementConstants' category: 'VMMaker-SpurMemoryManager'! !SpurGenerationScavenger commentStamp: 'eem 9/30/2013 11:05' prior: 0! SpurGenerationScavenger is an implementation of David Ungar's Generation Scavenging garbage collection algorithm. See Generation Scavenging, A Non-disruptive, High-Performance Storage Reclamation Algorithm David Ungar Proceeding SDE 1 Proceedings of the first ACM SIGSOFT/SIGPLAN software engineering symposium on Practical software development environments Pages 157 - 167 ACM New York, NY, USA ©1984 Also relevant are An adaptive tenuring policy for generation scavengers David Ungar & Frank Jackson ACM Transactions on Programming Languages and Systems (TOPLAS) TOPLAS Homepage archive Volume 14 Issue 1, Jan. 1992 Pages 1 - 27 ACM New York, NY, USA ©1992 and Ephemerons: a new finalization mechanism Barry Hayes Proceedings of the 12th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications Pages 176-183 ACM New York, NY, USA ©1997 See text below the variable definitions and explanation below for a full explanation of weak and ephemeron processing. Instance Variables coInterpreter: <StackInterpreterSimulator|CogVMSimulator> eden: <SpurNewSpaceSpace> ephemeronList: <Integer|nil> futureSpace: <SpurNewSpaceSpace> futureSurvivorStart: <Integer address> manager: <SpurMemoryManager|Spur32BitMMLESimulator et al> numRememberedEphemerons: <Integer> pastSpace: <SpurNewSpaceSpace> previousRememberedSetSize: <Integer> rememberedSet: <CArrayAccessor on: Array> rememberedSetSize: <Integer> tenuringProportion: <Float> tenuringThreshold: <Integer address> weakList: <Integer|nil> coInterpreter - the interpreter/vm, in this context, the mutator manager - the Spur memory manager eden - the space containing newly created objects futureSpace - the space to which surviving objects are copied during a scavenge futureSurvivorStart - the allocation pointer into futureSpace pastSpace - the space surviving objects live in until the next scavenge rememberedSet - the root old space objects that refer to objects in new space; a scavenge starts form these roots and the interpreter's stack rememberedSetSize - the size of the remembered set, also the first unused index in the rememberedSet previousRememberedSetSize: - the size of the remembered set before scavenging objects in future space. numRememberedEphemerons - the number of unscavenged ephemerons at the front of the rememberedSet. ephemeronList - the head of the list of corpses of unscavenged ephemerons reached in the current phase weakList - the head of the list of corpses of weak arrays reached during the scavenge. tenuringProportion - the amount of pastSpace below which the system will not tenure unless futureSpace fills up, and above which it will eagerly tenure tenuringThreshold - the pointer into pastSpace below which objects will be tenured Weakness and Ephemerality in the Scavenger. Weak arrays should not hold onto their referents (except from their strong fileds, their named inst vars). Ephemerons are objects that implement instance-based finalization; attaching an ephemeron to an object keeps that object alive and causes the ephemeron to "fire" when the object is only reachable from the ephemeron (or other ephemerons & weak arrays). They are a special kind of Associations that detect when their keys are about to die, i.e. when an ephemeron's key is not reachable from the roots except from weak arrays and other ephemerons with about-to-die keys. Note that if an ephemeron's key is not about to die then references from the rest of the ephemeron can indeed prevent ephemeron keys from dying. The scavenger is concerned with collecting objects in new space, therefore it ony deals with weak arrays and ephemerons that are either in the remembered set or in new space. By deferring scanning these objects until other reachable objects have been scavenged, the scavenger can detect dead or dying references. Weak Array Processing In the case of weak arrays this is simple. The scavenger refuses to scavenge the referents of weak arrays in scavengeReferentsOf: until the entire scavenge is over. It then scans the weak arrays in the remembered set and in future space and nils all fields in them that are referring to unforwarded objects in eden and past space, because these objects have not survived the scavenge. The root weak arrays remaining to be scavenged are in the remembered table. Surviving weak arrays in future space are collected on a list. The list is threaded through the corpses of weak arrays in eden and/or past space. weakList holds the slot offset of the first weak array found in eden and/or past space. The next offset is stored in the weak array corpse's identityHash and format fields (22 bits & 5 bits of allocationUnits, for a max new space size of 2^28 bytes, 256Mb). The list is threaded throguh corpses, but the surviving arrays are pointed to by the corpses' forwarding pointers. Ephemeron Processing The case of ephemerons is a little more complicated because an ephemeron's key should survive. The scavenger is cyclical. It scavenges the remembered set, which may copy and forward surviving objects in past and/or eden spaces to future space. It then scavenges those promoted objects in future space until no more are promoted, which may in turn remember more objects. The cycles continue until no more objects get promoted to future space and no more objects get remembered. At this point all surviving objecta are in futureSpace. So if the scavenger does not scan ephemerons in the remembered set or in future space until the scavenger finishes cycling, it can detect ephemerons whose keys are about to die because these will be unforwarded objects in eden and/or past space. Ephemerons encountered in the remembered set are either processed like ordinary objects if their keys have been promoted to futureSpace, or are moved to the front of the rememberedSet (because, dear reader, it is a sequence) if their keys have not been promoted. Ephemerons encountered in scavengeReferentsOf: are either scanned like normal objects if their keys have been promoted, or added to the ephemeronList, organized identically to the weakList, if their keys are yet to be promoted. Since references from other ephemerons with surviving keys to ephemeron keys can and should prevent the ephemerons whose keys they are from firing the scavenger does not fire ephemerons unless all unscavenged ephemerons have unscavenged keys. So the unscavenged ephemerons (the will be at the beginning of the remembered set and on the ephemeronList) are scanned and any that have promoted keys are scavenged. But if no unscavenged ephemerons have surviving keys then all the unscavenged ephemerons are fired and then scavenged. This in turn may remember more objects and promote more objects to future space, and encounter more unscavenged ephemerons. So the scavenger continues until no more objects are remembered, no more objects are promoted to future space and no more unscavenged ephemerons exist.! Item was changed: ----- Method: SpurGenerationScavenger class>>initialize (in category 'class initialization') ----- initialize "SpurGenerationScavenger initialize" TenureByAge := 1. TenureByClass := 2. + TenureToShrinkRT := 3. + DontTenure := 4. + MarkOnTenure := 5. + MaxRTRefCount := 7 "The field comprised of {isGrey,isPinned,isRemembered}"! - DontTenure := 3. - DontTenureButDoUnmark := 4. - MarkOnTenure := 5! Item was added: + ----- Method: SpurGenerationScavenger>>allNewSpaceObjectsHaveZeroRTRefCount (in category 'remembered set') ----- + allNewSpaceObjectsHaveZeroRTRefCount + manager allNewSpaceObjectsDo: + [:obj| + (manager rtRefCountOf: obj) > 0 ifTrue: + [^false]]. + ^true! Item was added: + ----- Method: SpurGenerationScavenger>>computeRefCountToShrinkRT (in category 'remembered set') ----- + computeRefCountToShrinkRT + "Some time in every scavenger's life there may come a time when someone writes code that stresses + the remembered table. One might conclude that if the remembered table is full, then the right thing + to do is simply to tenure everything, emptying the remembered table. Bt in some circumstances this + can be counter-productive, and result in the same situation arising soon after tenuring everything. + Instead, we can try and selectively prune the remembered table, tenuring only those objects that + are referenced by many objects in the remembered table. That's what this algorithm does. It + reference counts young objects referenced from the remembered set, and then sets a threshold + used to tenure objects oft referenced from the remembered set, thereby allowing the remembered + set to shrink, while not tenuring everything. + + Once in a network monitoring application in a galaxy not dissimilar from the one this code inhabits, + a tree of nodes referring to large integers was in precisely this situation. The nodes were old, and + the integers were in new space. Some of the nodes referred to shared numbers, some their own + unique numbers. The numbers were updated frequently. Were new space simply tenured when the + remembered table was full, the remembered table would soon fill up as new numbers were computed. + Only by selectively pruning the remembered table of nodes that shared data, was a balance achieved + whereby the remembered table population was kept small, and tenuring rates were low." + <inline: #never> + | counts | + <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> + self cCode: '' inSmalltalk: [counts := CArrayAccessor on: (Array new: MaxRTRefCount + 1)]. + self assert: self allNewSpaceObjectsHaveZeroRTRefCount. + self referenceCountRememberedReferents. + self totalRememberedReferentCounts: counts. + self setRefCountToShrinkRT: counts! Item was changed: ----- Method: SpurGenerationScavenger>>copyAndForward: (in category 'scavenger') ----- copyAndForward: survivor "copyAndForward: survivor copies a survivor object either to futureSurvivorSpace or, if it is to be promoted, to oldSpace. It leaves a forwarding pointer behind. If the object is weak then corpse is threaded onto the weakList for later treatment." <inline: false> | bytesInObj format tenure newLocation | self assert: ((manager isInEden: survivor) "cog methods should be excluded." or: [manager isInPastSpace: survivor]). bytesInObj := manager bytesInObject: survivor. format := manager formatOf: survivor. tenure := self shouldBeTenured: survivor. "Allow Slang to inline." newLocation := (tenure or: [futureSurvivorStart + bytesInObj > futureSpace limit]) ifTrue: [self copyToOldSpace: survivor bytes: bytesInObj format: format] ifFalse: [self copyToFutureSpace: survivor bytes: bytesInObj]. manager forwardSurvivor: survivor to: newLocation. "if weak or ephemeron add to the relevant list for subsequent scanning." (manager isWeakFormat: format) ifTrue: [self addToWeakList: survivor]. ((manager isEphemeronFormat: format) and: [(self isScavengeSurvivor: (manager keyOfEphemeron: newLocation)) not]) ifTrue: [self addToEphemeronList: survivor]. ^newLocation! Item was changed: ----- Method: SpurGenerationScavenger>>copyToFutureSpace:bytes: (in category 'scavenger') ----- copyToFutureSpace: survivor bytes: bytesInObject "Copy survivor to futureSpace. Assume it will fit (checked by sender). Answer the new oop of the object (it may have an overflow size field)." <inline: true> | startOfSurvivor newStart | self assert: futureSurvivorStart + bytesInObject <= futureSpace limit. startOfSurvivor := manager startOfObject: survivor. newStart := futureSurvivorStart. futureSurvivorStart := futureSurvivorStart + bytesInObject. manager mem: newStart asVoidPointer cp: startOfSurvivor asVoidPointer y: bytesInObject. + tenureCriterion = TenureToShrinkRT ifTrue: + [manager rtRefCountOf: newStart + (survivor - startOfSurvivor) put: 0]. ^newStart + (survivor - startOfSurvivor)! Item was removed: - ----- Method: SpurGenerationScavenger>>copyToOldSpace: (in category 'scavenger') ----- - copyToOldSpace: survivor - "Copy survivor to oldSpace. Answer the new oop of the object." - <inline: true> - | nTenures numSlots hash newOop | - nTenures := statTenures. - self flag: 'why not just pass header??'. - numSlots := manager numSlotsOf: survivor. - hash := manager rawHashBitsOf: survivor. - newOop := manager - allocateSlotsInOldSpace: numSlots - format: (manager formatOf: survivor) - classIndex: (manager classIndexOf: survivor). - newOop ifNil: - [manager growOldSpaceByAtLeast: 0. "grow by growHeadroom" - newOop := manager - allocateSlotsInOldSpace: numSlots - format: (manager formatOf: survivor) - classIndex: (manager classIndexOf: survivor). - newOop ifNil: - [self error: 'out of memory']]. - manager - mem: (newOop + manager baseHeaderSize) asVoidPointer - cp: (survivor + manager baseHeaderSize) asVoidPointer - y: numSlots * manager wordSize. - (manager hasPointerFields: survivor) ifTrue: - [self remember: newOop]. - hash ~= 0 ifTrue: - [manager setHashBitsOf: newOop to: hash]. - statTenures := nTenures + 1. - ^newOop! Item was removed: - ----- Method: SpurGenerationScavenger>>copyToOldSpace:bytes: (in category 'scavenger') ----- - copyToOldSpace: survivor bytes: bytesInObject - "Copy survivor to oldSpace. Answer the new oop of the object." - <inline: true> - | nTenures startOfSurvivor newStart newOop | - nTenures := statTenures. - startOfSurvivor := manager startOfObject: survivor. - newStart := manager allocateOldSpaceChunkOfBytes: bytesInObject. - newStart ifNil: - [manager growOldSpaceByAtLeast: 0. "grow by growHeadroom" - newStart := manager allocateOldSpaceChunkOfBytes: bytesInObject. - newStart ifNil: - [self error: 'out of memory']]. - manager checkFreeSpace. - manager mem: newStart asVoidPointer cp: startOfSurvivor asVoidPointer y: bytesInObject. - newOop := newStart + (survivor - startOfSurvivor). - (manager hasPointerFields: survivor) ifTrue: - [self remember: newOop]. - statTenures := nTenures + 1. - ^newOop! Item was changed: ----- Method: SpurGenerationScavenger>>copyToOldSpace:bytes:format: (in category 'scavenger') ----- copyToOldSpace: survivor bytes: bytesInObject format: formatOfSurvivor "Copy survivor to oldSpace. Answer the new oop of the object." <inline: #never> "Should be too infrequent to lower icache density of copyAndForward:" | nTenures startOfSurvivor newStart newOop | self assert: (formatOfSurvivor = (manager formatOf: survivor) and: [((manager isMarked: survivor) not or: [tenureCriterion = MarkOnTenure]) + and: [tenureCriterion = TenureToShrinkRT + or: [(manager isPinned: survivor) not + and: [(manager isRemembered: survivor) not]]]]). - and: [(manager isPinned: survivor) not - and: [(manager isRemembered: survivor) not]]]). nTenures := statTenures. startOfSurvivor := manager startOfObject: survivor. newStart := manager allocateOldSpaceChunkOfBytes: bytesInObject. newStart ifNil: [manager growOldSpaceByAtLeast: 0. "grow by growHeadroom" newStart := manager allocateOldSpaceChunkOfBytes: bytesInObject. newStart ifNil: [self error: 'out of memory']]. "manager checkFreeSpace." manager mem: newStart asVoidPointer cp: startOfSurvivor asVoidPointer y: bytesInObject. newOop := newStart + (survivor - startOfSurvivor). + tenureCriterion >= (TenureToShrinkRT min: MarkOnTenure) ifTrue: + [tenureCriterion = TenureToShrinkRT ifTrue: + [manager rtRefCountOf: newOop put: 0]. + tenureCriterion = MarkOnTenure ifTrue: + [manager setIsMarkedOf: newOop to: true]]. - (manager isAnyPointerFormat: formatOfSurvivor) ifTrue: - [self remember: newOop]. - tenureCriterion = MarkOnTenure ifTrue: - [manager setIsMarkedOf: newOop to: true]. statTenures := nTenures + 1. + (manager isAnyPointerFormat: formatOfSurvivor) ifTrue: + ["A very quick and dirty scan to find young referents. If we misidentify bytes + in a CompiledMethod as young we don't care; it's unlikely, and a subsequent + scan of the rt will filter the object out. But it's good to filter here because + otherwise an attempt to shrink the RT may simply fill it up with new objects, + and here the data is likely in the cache." + manager baseHeaderSize to: bytesInObject - (survivor - startOfSurvivor) - manager wordSize by: manager wordSize do: + [:p| | field | + field := manager longAt: survivor + p. + (manager isReallyYoung: field) ifTrue: + [self remember: newOop. + ^newOop]]]. ^newOop! Item was changed: + ----- Method: SpurGenerationScavenger>>growRememberedSet (in category 'remembered set') ----- - ----- Method: SpurGenerationScavenger>>growRememberedSet (in category 'store check') ----- growRememberedSet | obj numSlots newObj base | <inline: false> "Don't ruin locality in remember:" <var: #base type: #'sqInt *'> obj := manager rememberedSetObj. numSlots := manager numSlotsOf: obj. self assert: numSlots >= 1024. newObj := manager allocatePinnedSlots: numSlots * 2. newObj ifNil: [newObj := manager allocatePinnedSlots: numSlots + 1024. newObj ifNil: [self error: 'could not grow remembered set']]. manager rememberedSetObj: newObj. base := manager firstIndexableField: newObj. 0 to: rememberedSetSize - 1 do: [:i| base at: i put: (rememberedSet at: i)]. "if growing in the middle of a GC, need to preserve marked status." (manager isMarked: obj) ifTrue: [manager setIsMarkedOf: newObj to: true; setIsMarkedOf: obj to: false]. manager freeObject: obj. rememberedSet := base. + rememberedSetLimit := manager numSlotsOf: newObj. + self setRememberedSetRedZone! - rememberedSetLimit := numSlots * 2. - rememberedSetRedZone := rememberedSetLimit * 3 + 3 // 4! Item was changed: ----- Method: SpurGenerationScavenger>>initializeRememberedSet (in category 'initialization') ----- initializeRememberedSet | obj | obj := manager rememberedSetObj. obj = manager nilObject ifTrue: [obj := manager allocatePinnedSlots: 1024. manager rememberedSetObj: obj]. rememberedSet := manager firstIndexableField: obj. rememberedSetSize := 0. rememberedSetLimit := manager numSlotsOf: obj. + self setRememberedSetRedZone! - rememberedSetRedZone := rememberedSetLimit * 3 + 3 // 4! Item was added: + ----- Method: SpurGenerationScavenger>>referenceCountRememberedReferents (in category 'remembered set') ----- + referenceCountRememberedReferents + "Reference count each referent of the remembered table using the rtRefCount + field comprised of isGrey,isPinned,isRemembered. i.e. produce a reference + count from 1 to 7 in all objects accessible from the RT." + <inline: true> + 0 to: rememberedSetSize - 1 do: + [:i| | elephant | + elephant := rememberedSet at: i. + 0 to: (manager numPointerSlotsOf: elephant) - 1 do: + [:j| | referent refCount | + referent := manager fetchPointer: j ofObject: elephant. + (manager isReallyYoung: referent) ifTrue: + [refCount := manager rtRefCountOf: referent. + (refCount := refCount + 1) <= MaxRTRefCount ifTrue: + [manager rtRefCountOf: referent put: refCount]]]]! Item was added: + ----- Method: SpurGenerationScavenger>>rememberedSetLimit (in category 'accessing') ----- + rememberedSetLimit + <cmacro: '() GIV(rememberedSetLimit)'> + ^rememberedSetLimit! Item was changed: ----- Method: SpurGenerationScavenger>>scavenge: (in category 'scavenger') ----- scavenge: tenuringCriterion "The main routine, scavenge, scavenges young objects reachable from the roots (the stack zone and the rememberedTable). It first scavenges the new objects immediately reachable from old ones (all in the remembered table), then the stack zone. Then it scavenges those that are transitively reachable. If this results in a promotion, the promotee gets remembered, and it first scavenges objects adjacent to the promotee, then scavenges the ones reachable from the promoted. This loop continues until no more reachable objects are left. At that point, pastSurvivorSpace is exchanged with futureSurvivorSpace. Then any surviving weakArrays and weakArrays in the remembered set can be processed and their dead elements nilled. By default promotion (tenuring) is based on age and ammount of objects scavenged. But tenuring can be based on e.g. a particular class. The argument selects the tenuring criterion. Answer the limit of pastSpace, to allow the memory manager to bounds check survivors." tenureCriterion := tenuringCriterion. + self strategizeToLimitRememberedTable. self scavengeLoop. self processWeaklings. self computeTenuringThreshold. self exchangeSurvivorSpaces. ^self initFutureSpaceStart! Item was added: + ----- Method: SpurGenerationScavenger>>setRefCountToShrinkRT: (in category 'remembered set') ----- + setRefCountToShrinkRT: counts + "Choose a refCount that will shrink the rt by at least half." + <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> + <inline: true> + | i count | + count := 0. + i := MaxRTRefCount + 1. + [count < (rememberedSetSize // 2) and: [(i := i - 1) >= 0]] whileTrue: + [count := count + (counts at: i)]. + refCountToShrinkRT := i max: 0! Item was added: + ----- Method: SpurGenerationScavenger>>setRememberedSetRedZone (in category 'remembered set') ----- + setRememberedSetRedZone + | fudge | + <inline: true> + "fudge is a minimum below which we don't care about growing the RT. + It is chosen so that with a default 4Mb new space, the RT is not considered + full until it has from 512 to 1024 entries." + fudge := eden limit - eden start / manager wordSize // 1024. + rememberedSetRedZone := rememberedSetLimit * 3 // 4 max: fudge! Item was changed: ----- Method: SpurGenerationScavenger>>shouldBeTenured: (in category 'scavenger') ----- shouldBeTenured: survivor "Answer if an object should be tenured. The default policy tenuring policy is to use the tenuringThreshold to decide. If the survivors (measured in bytes) are above some fraction of the survivor space then objects below the threshold (older objects, since allocation grows upwards and hence new objects are later than old) are scavenged. Otherwise, the threshold is set to 0 and no objects are tenured. e.g. see An adaptive tenuring policy for generation scavengers, David Ungar & Frank Jackson. ACM TOPLAS, Volume 14 Issue 1, Jan. 1992, pp 1 - 27. The other policies are for special purposes." ^tenureCriterion caseOf: { [TenureByAge] -> [survivor < tenureThreshold]. [TenureByClass] -> [(manager classIndexOf: survivor) = tenuringClassIndex]. + [TenureToShrinkRT] -> + [(manager rtRefCountOf: survivor) >= refCountToShrinkRT] } - [DontTenureButDoUnmark] -> - [manager setIsMarkedOf: survivor to: false. - false] } otherwise: [false]! Item was added: + ----- Method: SpurGenerationScavenger>>strategizeToLimitRememberedTable (in category 'remembered set') ----- + strategizeToLimitRememberedTable + <inline: true> + (tenureCriterion = TenureByAge + and: [rememberedSetSize >= rememberedSetRedZone]) ifTrue: + [tenureCriterion := TenureToShrinkRT. + self computeRefCountToShrinkRT]! Item was added: + ----- Method: SpurGenerationScavenger>>totalRememberedReferentCounts: (in category 'remembered set') ----- + totalRememberedReferentCounts: counts + <var: 'counts' declareC: 'long counts[MaxRTRefCount + 1]'> + <inline: true> + 0 to: MaxRTRefCount do: + [:i| counts at: i put: 0]. + 0 to: rememberedSetSize - 1 do: + [:i| | elephant | + elephant := rememberedSet at: i. + 0 to: (manager numPointerSlotsOf: elephant) - 1 do: + [:j| | referent refCount | + referent := manager fetchPointer: j ofObject: elephant. + (manager isReallyYoung: referent) ifTrue: + [refCount := manager rtRefCountOf: referent. + counts at: refCount put: (counts at: refCount) + 1]]]! Item was added: + ----- Method: SpurGenerationScavengerSimulator>>computeRefCountToShrinkRT (in category 'remembered set') ----- + computeRefCountToShrinkRT + self halt. + ^super computeRefCountToShrinkRT! Item was removed: - ----- Method: SpurGenerationScavengerSimulator>>remember: (in category 'store check') ----- - remember: objOop - (rememberedSetSize > 0 - and: [(rememberedSet at: rememberedSetSize - 1) = objOop]) ifTrue: - [self halt]. - ^super remember: objOop! Item was changed: SharedPool subclass: #SpurMemoryManagementConstants instanceVariableNames: '' + classVariableNames: 'DontTenure MarkOnTenure MaxRTRefCount TenureByAge TenureByClass TenureToShrinkRT' - classVariableNames: 'DontTenure DontTenureButDoUnmark MarkOnTenure TenureByAge TenureByClass' poolDictionaries: '' category: 'VMMaker-SpurMemoryManager'! Item was changed: ----- Method: SpurMemoryManager>>initializeObjectMemory: (in category 'initialization') ----- initializeObjectMemory: bytesToShift "Initialize object memory variables at startup time. Assume endOfMemory at al are initialised by the image-reading code via setHeapBase:memoryLimit:endOfMemory:. endOfMemory is assumed to point to the end of the last object in the image. Assume: image reader also initializes the following variables: specialObjectsOop lastHash" <inline: false> | freeListObj | "Catch mis-initializations leading to bad translations to C" self assert: self baseHeaderSize = self baseHeaderSize. self assert: (self maxSlotsForAlloc * self wordSize) asInteger > 0. self bootstrapping ifFalse: [self initSegmentBridgeWithBytes: self bridgeSize at: endOfMemory - self bridgeSize]. segmentManager adjustSegmentSwizzlesBy: bytesToShift. "image may be at a different address; adjust oops for new location" self adjustAllOopsBy: bytesToShift. specialObjectsOop := segmentManager swizzleObj: specialObjectsOop. "heavily used special objects" nilObj := self splObj: NilObject. falseObj := self splObj: FalseObject. trueObj := self splObj: TrueObject. "In Cog we insist that nil, true & false are next to each other (Cogit generates tighter conditional branch code as a result). In addition, Spur places the free lists and class table root page immediately following them." self assert: nilObj = oldSpaceStart. self assert: falseObj = (self objectAfter: nilObj). self assert: trueObj = (self objectAfter: falseObj). freeListObj := self objectAfter: trueObj. self setHiddenRootsObj: (self objectAfter: freeListObj). markStack := self swizzleObjStackAt: MarkStackRootIndex. weaklingStack := self swizzleObjStackAt: WeaklingStackRootIndex. ephemeronQueue := self swizzleObjStackAt: EphemeronQueueRootIndex. self assert: self validObjStacks. self assert: (self isEmptyObjStack: markStack). self assert: (self isEmptyObjStack: weaklingStack). self initializeFreeSpacePostLoad: freeListObj. segmentManager collapseSegmentsPostSwizzle. self computeFreeSpacePostSwizzle. self initializeOldSpaceFirstFree: freeOldSpaceStart. "initializes endOfMemory, freeStart, free space" + self initializeNewSpaceVariables. + scavenger initializeRememberedSet. - "self bootstrapping ifFalse: - ["self initializeNewSpaceVariables. - scavenger initializeRememberedSet"]". segmentManager checkSegments. numCompactionPasses := CompactionPassesForGC. "These defaults should depend on machine size; e.g. too small on a powerful laptop, too big on a Pi." growHeadroom := 16*1024*1024. "headroom when growing" shrinkThreshold := 32*1024*1024. "free space before shrinking" self setHeapSizeAtPreviousGC. heapGrowthToSizeGCRatio := 0.333333. "By default GC after scavenge if heap has grown by a third since the last GC"! Item was changed: ----- Method: SpurMemoryManager>>rootTableCapacity (in category 'scavenger') ----- rootTableCapacity + <cmacro: '() GIV(rememberedSetLimit)'> + ^scavenger rememberedSetLimit! - ^self numSlotsOf: self rememberedSetObj! Item was changed: ----- Method: SpurMemoryManager>>rootTableCount (in category 'accessing') ----- rootTableCount + <cmacro: '() GIV(rememberedSetSize)'> ^scavenger rememberedSetSize! Item was added: + ----- Method: SpurMemoryManager>>rtRefCountOf: (in category 'gc - scavenging') ----- + rtRefCountOf: obj + "Answer the rt reference count of obj; this is the three bit field comprised + of isGrey,isPinned,isRemembered. See computeRefCountToShrinkRT." + ^(self longAt: obj) >> self rememberedBitShift bitAnd: MaxRTRefCount! Item was added: + ----- Method: SpurMemoryManager>>rtRefCountOf:put: (in category 'gc - scavenging') ----- + rtRefCountOf: obj put: refCount + "Set the rt reference count of obj; this is the three bit field comprised + of isGrey,isPinned,isRemembered. See computeRefCountToShrinkRT." + self subclassResponsibility! Item was added: + ----- Method: StackInterpreterSimulator>>primitiveVMParameter (in category 'system control primitives') ----- + primitiveVMParameter + (self stackTop = (objectMemory integerObjectOf: 9) + or: [self stackTop = (objectMemory integerObjectOf: 52)]) ifTrue: + [self halt]. + ^super primitiveVMParameter!

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VM Maker: VMMaker.oscog-eem.1287.mcz
by commits＠source.squeak.org 05 May '15

05 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-eem.1287.mcz ==================== Summary ==================== Name: VMMaker.oscog-eem.1287 Author: eem Time: 5 May 2015, 10:08:54.172 am UUID: 45fc3cf4-0050-4473-af9e-392747bdd689 Ancestors: VMMaker.oscog-cb.1286 Add a nice click step facility for single-steppng through machine code that sets up a suitable breakBlock and proceeds the debugger, prompting for a click at each step. Fix instruction decoration when printing instructions with EagerInstructionDecoration false. Add an assert to insist that the receiver not be forwarded to mnuMethodOrNilFor:. Safer comparison in simulator's createActualMessageTo: =============== Diff against VMMaker.oscog-cb.1286 =============== Item was changed: ----- Method: CoInterpreter>>mnuMethodOrNilFor: (in category 'message sending') ----- mnuMethodOrNilFor: rcvr "Lookup the doesNotUnderstand: selector in the class of the argument rcvr. Answer either the matching method (cogged if appropriate), or nil, if not found." | currentClass mnuSelector dictionary mnuMethod methodHeader | + self deny: (objectMemory isOopForwarded: rcvr). - currentClass := objectMemory fetchClassOf: rcvr. mnuSelector := objectMemory splObj: SelectorDoesNotUnderstand. [currentClass ~= objectMemory nilObject] whileTrue: [dictionary := objectMemory fetchPointer: MethodDictionaryIndex ofObject: currentClass. dictionary = objectMemory nilObject ifTrue: [^nil]. mnuMethod := self lookupMethodFor: mnuSelector InDictionary: dictionary. + mnuMethod ifNotNil: - mnuMethod notNil ifTrue: [methodHeader := self rawHeaderOf: mnuMethod. ((self isCogMethodReference: methodHeader) not and: [self methodWithHeaderShouldBeCogged: methodHeader]) ifTrue: [cogit cog: mnuMethod selector: mnuSelector]. ^mnuMethod]. currentClass := self superclassOf: currentClass]. ^nil! Item was changed: ----- Method: CogVMSimulator>>createActualMessageTo: (in category 'debugging traps') ----- createActualMessageTo: class + class = objectMemory nilObject ifTrue: [self halt]. - class == objectMemory nilObject ifTrue: [self halt]. ^super createActualMessageTo: class! Item was changed: ----- Method: CogVMSimulator>>utilitiesMenu: (in category 'UI') ----- utilitiesMenu: aMenuMorph aMenuMorph add: 'toggle transcript' action: #toggleTranscript; add: 'clone VM' action: #cloneSimulationWindow; addLine; add: 'print ext head frame' action: #printExternalHeadFrame; add: 'print int head frame' action: #printHeadFrame; add: 'print mc/cog frame' action: [self printFrame: cogit processor fp WithSP: cogit processor sp]; add: 'short print ext frame & callers' action: [self shortPrintFrameAndCallers: framePointer]; add: 'short print int frame & callers' action: [self shortPrintFrameAndCallers: localFP]; add: 'short print mc/cog frame & callers' action: [self shortPrintFrameAndCallers: cogit processor fp]; add: 'long print ext frame & callers' action: [self printFrameAndCallers: framePointer SP: stackPointer]; add: 'long print int frame & callers' action: [self printFrameAndCallers: localFP SP: localSP]; add: 'long print mc/cog frame & callers' action: [self printFrameAndCallers: cogit processor fp SP: cogit processor sp]; add: 'print frame...' action: [(self promptHex: 'print frame') ifNotNil: [:fp| self printFrame: fp]]; add: 'print call stack' action: #printCallStack; add: 'print stack call stack' action: #printStackCallStack; add: 'print stack call stack of...' action: [(self promptHex: 'frame') ifNotNil: [:fp| self printStackCallStackOf: fp]]; add: 'print call stack of...' action: [(self promptHex: 'context or process oop') ifNotNil: [:obj| self printCallStackOf: obj]]; add: 'print call stack of frame...' action: [(self promptHex: 'frame') ifNotNil: [:fp| self printCallStackFP: fp]]; add: 'print all stacks' action: #printAllStacks; add: 'write back local ptrs' action: [stackPointer := localSP. framePointer := localFP. instructionPointer := localIP. self writeBackHeadFramePointers]; add: 'write back mc ptrs' action: [stackPointer := cogit processor sp. framePointer := cogit processor fp. instructionPointer := cogit processor eip. self writeBackHeadFramePointers]; addLine; add: 'print rump C stack' action: [objectMemory printMemoryFrom: cogit processor sp to: self CStackPointer]; add: 'print registers' action: [cogit processor printRegistersOn: transcript]; add: 'print register map' action: [cogit printRegisterMapOn: transcript]; add: 'disassemble method/trampoline...' action: [(self promptHex: 'pc') ifNotNil: [:pc| cogit disassembleCodeAt: pc]]; add: 'disassemble method/trampoline at pc' action: [cogit disassembleCodeAt: cogit processor pc]; add: 'disassemble ext head frame method' action: [cogit disassembleMethod: (self frameMethod: framePointer)]; add: 'print oop...' action: [(self promptHex: 'print oop') ifNotNil: [:oop| self printOop: oop]]; add: 'long print oop...' action: [(self promptHex: 'print oop') ifNotNil: [:oop| self longPrintOop: oop]]; add: 'print context...' action: [(self promptHex: 'print context') ifNotNil: [:oop| self printContext: oop]]; addLine; add: 'inspect object memory' target: objectMemory action: #inspect; add: 'inspect cointerpreter' action: #inspect; add: 'inspect cogit' target: cogit action: #inspect; add: 'inspect method zone' target: cogit methodZone action: #inspect. self isThreadedVM ifTrue: [aMenuMorph add: 'inspect thread manager' target: self threadManager action: #inspect]. aMenuMorph addLine; add: 'print cog methods' target: cogMethodZone action: #printCogMethods; add: 'print cog methods with prim...' action: [(self promptNum: 'prim index') ifNotNil: [:pix| cogMethodZone printCogMethodsWithPrimitive: pix]]; add: 'print cog methods with selector...' action: [|s| s := UIManager default request: 'selector'. s notEmpty ifTrue: [s = 'nil' ifTrue: [s := nil]. cogMethodZone methodsDo: [:m| (s ifNil: [m selector = objectMemory nilObject] ifNotNil: [(objectMemory numBytesOf: m selector) = s size and: [(self str: s n: (m selector + objectMemory baseHeaderSize) cmp: (objectMemory numBytesOf: m selector)) = 0]]) ifTrue: [cogit printCogMethod: m]]]]; add: 'print cog method for...' action: [(self promptHex: 'pc') ifNotNil: [:pc| cogit printCogMethodFor: pc]]; add: 'print cog method header for...' action: [(self promptHex: 'pc') ifNotNil: [:pc| cogit printCogMethodHeaderFor: pc]]; add: 'print trampoline table' target: cogit action: #printTrampolineTable; add: 'print prim trace log' action: #dumpPrimTraceLog; add: 'report recent instructions' target: cogit action: #reportLastNInstructions; add: 'set break pc (', (cogit breakPC isInteger ifTrue: [cogit breakPC hex] ifFalse: [cogit breakPC printString]), ')...' action: [(self promptHex: 'break pc') ifNotNil: [:bpc| cogit breakPC: bpc]]; add: (cogit singleStep ifTrue: ['no single step'] ifFalse: ['single step']) action: [cogit singleStep: cogit singleStep not]; add: (cogit printRegisters ifTrue: ['no print registers each instruction'] ifFalse: ['print registers each instruction']) action: [cogit printRegisters: cogit printRegisters not]; add: (cogit printInstructions ifTrue: ['no print instructions each instruction'] ifFalse: ['print instructions each instruction']) action: [cogit printInstructions: cogit printInstructions not]; addLine; + add: 'click step' action: [cogit setClickStepBreakBlock]; add: 'set break count...' action: [|s| s := UIManager default request: 'break count (dec)'. s notEmpty ifTrue: [breakCount := Integer readFrom: s readStream]]; add: 'set break selector...' action: [|s| s := UIManager default request: 'break selector'. s notEmpty ifTrue: [self setBreakSelector: s]]; add: 'set break block...' action: [|s| s := UIManager default request: 'break block' initialAnswer: '[:theCogit| false]'. s notEmpty ifTrue: [self setBreakBlockFromString: s]]; add: 'set cogit break method...' action: [(self promptHex: 'cogit breakMethod') ifNotNil: [:bm| cogit setBreakMethod: bm]]; add: (printBytecodeAtEachStep ifTrue: ['no print bytecode each bytecode'] ifFalse: ['print bytecode each bytecode']) action: [self ensureDebugAtEachStepBlock. printBytecodeAtEachStep := printBytecodeAtEachStep not]; add: (printFrameAtEachStep ifTrue: ['no print frame each bytecode'] ifFalse: ['print frame each bytecode']) action: [self ensureDebugAtEachStepBlock. printFrameAtEachStep := printFrameAtEachStep not]. ^aMenuMorph! Item was changed: ----- Method: Cogit>>recordLastInstruction (in category 'simulation only') ----- recordLastInstruction <doNotGenerate> ^self recordInstruction: (processor disassembleNextInstructionIn: coInterpreter memory + for: ((EagerInstructionDecoration or: [printInstructions]) ifTrue: [self]))! - for: (EagerInstructionDecoration ifTrue: [self]))! Item was added: + ----- Method: Cogit>>setClickStepBreakBlock (in category 'simulation only') ----- + setClickStepBreakBlock + "Set the break block to present a confirmer, breaking if true, and restoring the previous break block. + If an open debugger on the receiver can be found, proceed it." + <doNotGenerate> + | previousBreakBlock | + previousBreakBlock := breakBlock. + breakBlock := [:ign| + (UIManager confirm: 'step?') + ifTrue: [false] + ifFalse: [breakBlock := previousBreakBlock. + true]]. + (World submorphs + detect: + [:m| + m model class == Debugger + and: [(m model interruptedProcess suspendedContext findContextSuchThat: + [:ctxt| + ctxt receiver == self + and: [ctxt selector == #simulateCogCodeAt:]]) notNil]] + ifNone: []) ifNotNil: + [:debuggerWindow| + WorldState addDeferredUIMessage: + [debuggerWindow model proceed]]!

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VM Maker: VMMaker.oscog-cb.1286.mcz
by commits＠source.squeak.org 05 May '15

05 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1286.mcz ==================== Summary ==================== Name: VMMaker.oscog-cb.1286 Author: cb Time: 5 May 2015, 4:26:27.068 pm UUID: 1f96acd1-0fdd-4775-8165-485cba2fdb10 Ancestors: VMMaker.oscog-cb.1285 trap callback have no freaking argument any more. =============== Diff against VMMaker.oscog-cb.1285 =============== Item was changed: ----- Method: CoInterpreter>>ceSistaTrap (in category 'trampolines') ----- ceSistaTrap "When we arrive here, the value that trapped is pushed on stack" <api> <option: #SistaVM> | context | instructionPointer := self popStack. context := self ensureFrameIsMarried: framePointer SP: stackPointer. self push: context. self push: instructionPointer. ^self ceSendAbort: (objectMemory splObj: SelectorSistaTrap) to: context + numArgs: 0! - numArgs: 1! Item was changed: ----- Method: StackInterpreter>>respondToSistaTrap (in category 'sista bytecodes') ----- respondToSistaTrap | ourContext | <sharedCodeInCase: #unconditionnalTrapBytecode> messageSelector := objectMemory splObj: SelectorSistaTrap. ourContext := self ensureFrameIsMarried: localFP SP: localSP. self internalPush: ourContext. + argumentCount := 0. - argumentCount := 1. self normalSend!

1 0

VM Maker: VMMaker.oscog-cb.1285.mcz
by commits＠source.squeak.org 05 May '15

05 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1285.mcz ==================== Summary ==================== Name: VMMaker.oscog-cb.1285 Author: cb Time: 5 May 2015, 3:30:06.47 pm UUID: 7ee85347-ea18-4249-81f1-e0510c99c8ce Ancestors: VMMaker.oscog-cb.1284 Forgot a -1 which was creating a segfault.... =============== Diff against VMMaker.oscog-cb.1284 =============== Item was changed: ----- Method: CogObjectRepresentationForSpur>>noneImmediateBranchIf:notInstanceOfBehaviors:target: (in category 'sista support') ----- noneImmediateBranchIf: reg notInstanceOfBehaviors: arrayObj target: targetFixUp "All classes in arrayObj are not immediate" | label numJumps jumps classObj | <var: #targetFixUp type: #'AbstractInstruction *'> <var: #label type: #'AbstractInstruction *'> <var: #jumps type: #'AbstractInstruction **'> cogit MoveR: reg R: TempReg. jumps := self alloca: (objectMemory numSlotsOf: arrayObj) type: (self cCode: [#'AbstractInstruction *'] inSmalltalk: [cogit backEnd class]). (self genJumpImmediateInScratchReg: TempReg) jmpTarget: targetFixUp. self genGetClassIndexOfNonImm: reg into: TempReg. 0 to: (numJumps := objectMemory numSlotsOf: arrayObj) - 1 do: [:i| classObj := objectMemory fetchPointer: i ofObject: arrayObj. self genCmpClassIndex: (objectMemory classTagForClass: classObj) R: TempReg. jumps at: i put: (cogit JumpZero: 0) ]. cogit Jump: targetFixUp. label := self Label. + 0 to: numJumps - 1 do: [:i | - 0 to: numJumps do: [:i | (jumps at: i) jmpTarget: label ]. ^0!

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VM Maker: VMMaker.oscog-cb.1284.mcz
by commits＠source.squeak.org 05 May '15

05 May '15

Eliot Miranda uploaded a new version of VMMaker to project VM Maker: http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1284.mcz ==================== Summary ==================== Name: VMMaker.oscog-cb.1284 Author: cb Time: 5 May 2015, 1:58:03.991 pm UUID: 37a41c7d-771e-4cee-9b78-94dc22070682 Ancestors: VMMaker.oscog-cb.1283 Reduced by 24 bytes the instructions generated by #== in SistaCogit in most cases. =============== Diff against VMMaker.oscog-cb.1283 =============== Item was changed: StackToRegisterMappingCogit subclass: #SistaStackToRegisterMappingCogit + instanceVariableNames: 'picDataIndex picData numCounters counters counterIndex initialCounterValue ceTrapTrampoline branchReachedOnlyForCounterTrip' - instanceVariableNames: 'picDataIndex picData numCounters counters counterIndex initialCounterValue ceTrapTrampoline' classVariableNames: 'CounterBytes MaxCounterValue' poolDictionaries: 'VMSqueakClassIndices' category: 'VMMaker-JIT'! !SistaStackToRegisterMappingCogit commentStamp: 'eem 4/7/2014 12:23' prior: 0! A SistaStackToRegisterMappingCogit is a refinement of StackToRegisterMappingCogit that generates code suitable for dynamic optimization by Sista, the Speculative Inlining Smalltalk Architecture, a project by Clément Bera and Eliot Miranda. Sista is an optimizer that exists in the Smalltalk image, /not/ in the VM, and optimizes by substituting normal bytecoded methods by optimized bytecoded methods that may use special bytecodes for which the Cogit can generate faster code. These bytecodes eliminate overheads such as bounds checks or polymorphic code (indexing Array, ByteArray, String etc). But the bulk of the optimization performed is in inlining blocks and sends for the common path. The basic scheme is that SistaStackToRegisterMappingCogit generates code containing performance counters. When these counters trip, a callback into the image is performed, at which point Sista analyses some portion of the stack, looking at performance data for the methods on the stack, and optimises based on the stack and performance data. Execution then resumes in the optimized code. SistaStackToRegisterMappingCogit adds counters to conditional branches. Each branch has an executed and a taken count, implemented at the two 16-bit halves of a single 32-bit word. Each counter pair is initialized with initialCounterValue. On entry to the branch the executed count is decremented and if the count goes below zero the ceMustBeBooleanAdd[True|False] trampoline called. The trampoline distinguishes between true mustBeBoolean and counter trips because in the former the register temporarily holding the counter value will contain zero. Then the condition is tested, and if the branch is taken the taken count is decremented. The two counter values allow an optimizer to collect basic block execution paths and to know what are the "hot" paths through execution that are worth agressively optimizing. Since conditional branches are about 1/6 as frequent as sends, and since they can be used to determine the hot path through code, they are a better choice to count than, for example, method or block entry. SistaStackToRegisterMappingCogit implements picDataFor:into: that fills an Array with the state of the counters in a method and the state of each linked send in a method. This is used to implement a primitive used by the optimizer to answer the branch and send data for a method as an Array. Instance Variables counterIndex: <Integer> counterMethodCache: <CogMethod> counters: <Array of AbstractInstruction> initialCounterValue: <Integer> numCounters: <Integer> picData: <Integer Oop> picDataIndex: <Integer> prevMapAbsPCMcpc: <Integer> counterIndex - xxxxx counterMethodCache - xxxxx counters - xxxxx initialCounterValue - xxxxx numCounters - xxxxx picData - xxxxx picDataIndex - xxxxx prevMapAbsPCMcpc - xxxxx ! Item was added: + ----- Method: SistaStackToRegisterMappingCogit>>genCounterTripOnlyJumpIf:to: (in category 'bytecode generator support') ----- + genCounterTripOnlyJumpIf: boolean to: targetBytecodePC + "Specific version if the branch is only reached while falling through if the counter trips after an inlined #== branch. We do not regenerate the counter logic in this case to avoid 24 bytes instructions." + + <var: #ok type: #'AbstractInstruction *'> + <var: #mustBeBooleanTrampoline type: #'AbstractInstruction *'> + + | ok mustBeBooleanTrampoline | + + self ssFlushTo: simStackPtr - 1. + + self ssTop popToReg: TempReg. + + self ssPop: 1. + + counterIndex := counterIndex + 1. "counters are increased / decreased in the inlined branch" + + "We need SendNumArgsReg because of the mustBeBooleanTrampoline" + self ssAllocateRequiredReg: SendNumArgsReg. + self MoveCq: 1 R: SendNumArgsReg. + + "The first time this is reached, it calls necessarily the counter trip for the trampoline because SendNumArgsReg is non zero" + mustBeBooleanTrampoline := self CallRT: (boolean == objectMemory falseObject + ifTrue: [ceSendMustBeBooleanAddFalseTrampoline] + ifFalse: [ceSendMustBeBooleanAddTrueTrampoline]). + + self annotateBytecode: self Label. + + "Cunning trick by LPD. If true and false are contiguous subtract the smaller. + Correct result is either 0 or the distance between them. If result is not 0 or + their distance send mustBeBoolean." + self assert: (objectMemory objectAfter: objectMemory falseObject) = objectMemory trueObject. + self annotate: (self SubCw: boolean R: TempReg) objRef: boolean. + self JumpZero: (self ensureFixupAt: targetBytecodePC - initialPC). + + self CmpCq: (boolean == objectMemory falseObject + ifTrue: [objectMemory trueObject - objectMemory falseObject] + ifFalse: [objectMemory falseObject - objectMemory trueObject]) + R: TempReg. + + ok := self JumpZero: 0. + self MoveCq: 0 R: SendNumArgsReg. "if counterReg is 0 this is a mustBeBoolean, not a counter trip." + + self Jump: mustBeBooleanTrampoline. + + ok jmpTarget: self Label. + ^0! Item was changed: ----- Method: SistaStackToRegisterMappingCogit>>genJumpIf:to: (in category 'bytecode generator support') ----- genJumpIf: boolean to: targetBytecodePC "The heart of performance counting in Sista. Conditional branches are 6 times less frequent than sends and can provide basic block frequencies (send counters can't). Each conditional has a 32-bit counter split into an upper 16 bits counting executions and a lower half counting untaken executions of the branch. Executing the branch decrements the upper half, tripping if the count goes negative. Not taking the branch decrements the lower half. N.B. We *do not* eliminate dead branches (true ifTrue:/true ifFalse:) so that scanning for send and branch data is simplified and that branch data is correct." <inline: false> + | ok counterAddress countTripped retry | - | desc ok counterAddress countTripped retry | <var: #ok type: #'AbstractInstruction *'> - <var: #desc type: #'CogSimStackEntry *'> <var: #retry type: #'AbstractInstruction *'> <var: #countTripped type: #'AbstractInstruction *'> (coInterpreter isOptimizedMethod: methodObj) ifTrue: [ ^ super genJumpIf: boolean to: targetBytecodePC ]. + + branchReachedOnlyForCounterTrip ifTrue: + [ branchReachedOnlyForCounterTrip := false. + ^ self genCounterTripOnlyJumpIf: boolean to: targetBytecodePC ]. self ssFlushTo: simStackPtr - 1. + self ssTop popToReg: TempReg. - desc := self ssTop. self ssPop: 1. - desc popToReg: TempReg. "We need SendNumArgsReg because of the mustBeBooleanTrampoline" self ssAllocateRequiredReg: SendNumArgsReg. retry := self Label. self genExecutionCountLogicInto: [ :cAddress :countTripBranch | counterAddress := cAddress. countTripped := countTripBranch ] counterReg: SendNumArgsReg. counterIndex := counterIndex + 1. "Cunning trick by LPD. If true and false are contiguous subtract the smaller. Correct result is either 0 or the distance between them. If result is not 0 or their distance send mustBeBoolean." self assert: (objectMemory objectAfter: objectMemory falseObject) = objectMemory trueObject. self annotate: (self SubCw: boolean R: TempReg) objRef: boolean. self JumpZero: (self ensureFixupAt: targetBytecodePC - initialPC). self genFallsThroughCountLogicCounterReg: SendNumArgsReg counterAddress: counterAddress. self CmpCq: (boolean == objectMemory falseObject ifTrue: [objectMemory trueObject - objectMemory falseObject] ifFalse: [objectMemory falseObject - objectMemory trueObject]) R: TempReg. ok := self JumpZero: 0. self MoveCq: 0 R: SendNumArgsReg. "if counterReg is 0 this is a mustBeBoolean, not a counter trip." + - countTripped jmpTarget: (self CallRT: (boolean == objectMemory falseObject ifTrue: [ceSendMustBeBooleanAddFalseTrampoline] ifFalse: [ceSendMustBeBooleanAddTrueTrampoline])). "If we're in an image which hasn't got the Sista code loaded then the ceCounterTripped: trampoline will return directly to machine code, returning the boolean. So the code should jump back to the retry point. The trampoline makes sure that TempReg has been reloaded." self annotateBytecode: self Label. self Jump: retry. ok jmpTarget: self Label. ^0! Item was changed: ----- Method: SistaStackToRegisterMappingCogit>>genSpecialSelectorEqualsEqualsWithForwarders (in category 'bytecode generators') ----- genSpecialSelectorEqualsEqualsWithForwarders "Override to count inlined branches if followed by a conditional branch. We borrow the following conditional branch's counter and when about to inline the comparison we decrement the counter (without writing it back) and if it trips simply abort the inlining, falling back to the normal send which will then continue to the conditional branch which will trip and enter the abort." | nextPC postBranchPC targetBytecodePC branchDescriptor label counterReg fixup counterAddress countTripped unforwardArg unforwardRcvr argReg rcvrReg regMask | <var: #fixup type: #'BytecodeFixup *'> <var: #countTripped type: #'AbstractInstruction *'> <var: #label type: #'AbstractInstruction *'> <var: #primDescriptor type: #'BytecodeDescriptor *'> <var: #branchDescriptor type: #'BytecodeDescriptor *'> ((coInterpreter isOptimizedMethod: methodObj) or: [needsFrame not]) ifTrue: [ ^ self genSpecialSelectorEqualsEqualsWithForwardersWithoutCounters ]. regMask := 0. self extractMaybeBranchDescriptorInto: [ :descr :next :postBranch :target | branchDescriptor := descr. nextPC := next. postBranchPC := postBranch. targetBytecodePC := target ]. unforwardRcvr := (objectRepresentation isUnannotatableConstant: (self ssValue: 1)) not. unforwardArg := (objectRepresentation isUnannotatableConstant: self ssTop) not. "If an operand is an annotable constant, it may be forwarded, so we need to store it into a register so the forwarder check can jump back to the comparison after unforwarding the constant. However, if one of the operand is an unnanotable constant, does not allocate a register for it (machine code will use operations on constants)." self allocateEqualsEqualsRegistersArgNeedsReg: unforwardArg rcvrNeedsReg: unforwardRcvr into: [ :rcvr :arg | rcvrReg:= rcvr. argReg := arg ]. argReg ifNotNil: [ regMask := self registerMaskFor: argReg ]. rcvrReg ifNotNil: [ regMask := regMask bitOr: (self registerMaskFor: rcvrReg) ]. "Only interested in inlining if followed by a conditional branch." (branchDescriptor isBranchTrue or: [branchDescriptor isBranchFalse]) ifFalse: [^ self genEqualsEqualsNoBranchArgIsConstant: unforwardArg not rcvrIsConstant: unforwardRcvr not argReg: argReg rcvrReg: rcvrReg]. counterReg := self allocateRegNotConflictingWith: regMask. self genExecutionCountLogicInto: [ :cAddress :countTripBranch | counterAddress := cAddress. countTripped := countTripBranch ] counterReg: counterReg. self assert: (unforwardArg or: [ unforwardRcvr ]). "If branching the stack must be flushed for the merge" self ssFlushTo: simStackPtr - 2. label := self Label. self genEqualsEqualsComparisonArgIsConstant: unforwardArg not rcvrIsConstant: unforwardRcvr not argReg: argReg rcvrReg: rcvrReg. self ssPop: 2. "pop by 2 temporarily for the fixups" branchDescriptor isBranchTrue ifTrue: [ fixup := self ensureNonMergeFixupAt: postBranchPC - initialPC. self JumpZero: (self ensureNonMergeFixupAt: targetBytecodePC - initialPC) asUnsignedInteger. ] ifFalse: [ fixup := self ensureNonMergeFixupAt: targetBytecodePC - initialPC. self JumpZero: (self ensureNonMergeFixupAt: postBranchPC - initialPC) asUnsignedInteger. ]. unforwardArg ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: argReg scratchReg: TempReg jumpBackTo: label ]. unforwardRcvr ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: rcvrReg scratchReg: TempReg jumpBackTo: label ]. self ssPop: -2. self genFallsThroughCountLogicCounterReg: counterReg counterAddress: counterAddress. self Jump: fixup. countTripped jmpTarget: self Label. "inlined version of #== ignoring the branchDescriptor if the counter trips to have normal state for the optimizer" self genEqualsEqualsNoBranchArgIsConstant: unforwardArg not rcvrIsConstant: unforwardRcvr not argReg: argReg rcvrReg: rcvrReg. + + (self fixupAt: nextPC - initialPC) targetInstruction = 0 ifTrue: [ branchReachedOnlyForCounterTrip := true ]. + ^ 0! Item was changed: ----- Method: SistaStackToRegisterMappingCogit>>initialize (in category 'initialization') ----- initialize super initialize. + branchReachedOnlyForCounterTrip := false. cogMethodSurrogateClass := (objectMemory ifNil: [self class objectMemoryClass]) wordSize = 4 ifTrue: [CogSistaMethodSurrogate32] ifFalse: [CogSistaMethodSurrogate64]!

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Re: [Vm-dev] VM Maker: VMMaker.oscog-cb.1283.mcz
by Clément Bera 05 May '15

05 May '15

Ok this fix the bug the SistaCogit now runs fine. It could be better to put some values on stack instead of using registers when calling some trampolines but I am a bit confused by which registers a trampoline can used in its implementation so I postpone that for later. 2015-05-05 11:48 GMT+02:00 <commits(a)source.squeak.org>: > > Eliot Miranda uploaded a new version of VMMaker to project VM Maker: > http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1283.mcz > > ==================== Summary ==================== > > Name: VMMaker.oscog-cb.1283 > Author: cb > Time: 5 May 2015, 11:48:13.804 am > UUID: 3000cd43-f84f-4b75-9fdf-aff579a5105b > Ancestors: VMMaker.oscog-eem.1282 > > Fixed a bug in SistaCogit where a trampoline needed a specific register > instead of an allocated one. > > =============== Diff against VMMaker.oscog-eem.1282 =============== > > Item was removed: > - ----- Method: > SistaStackToRegisterMappingCogit>>allocateRegPreferringCalleeSavedNotConflictingWith: > (in category 'simulation stack') ----- > - allocateRegPreferringCalleeSavedNotConflictingWith: regMask > - "If there are multiple free registers, choose one which is callee > saved, > - else just allocate a register not conflicting with regMask" > - | reg | > - reg := backEnd availableRegisterOrNilFor: ((self liveRegisters > bitOr: regMask) bitOr: callerSavedRegMask). > - ^ reg > - ifNil: [ self allocateRegNotConflictingWith: regMask ] > - ifNotNil: [ reg ]! > > Item was changed: > ----- Method: SistaStackToRegisterMappingCogit>>genJumpIf:to: (in > category 'bytecode generator support') ----- > genJumpIf: boolean to: targetBytecodePC > "The heart of performance counting in Sista. Conditional branches > are 6 times less > frequent than sends and can provide basic block frequencies (send > counters can't). > Each conditional has a 32-bit counter split into an upper 16 bits > counting executions > and a lower half counting untaken executions of the branch. > Executing the branch > decrements the upper half, tripping if the count goes negative. > Not taking the branch > decrements the lower half. N.B. We *do not* eliminate dead > branches (true ifTrue:/true ifFalse:) > so that scanning for send and branch data is simplified and that > branch data is correct." > <inline: false> > + | desc ok counterAddress countTripped retry | > - | desc ok counterAddress countTripped retry counterReg | > <var: #ok type: #'AbstractInstruction *'> > <var: #desc type: #'CogSimStackEntry *'> > <var: #retry type: #'AbstractInstruction *'> > <var: #countTripped type: #'AbstractInstruction *'> > > (coInterpreter isOptimizedMethod: methodObj) ifTrue: [ ^ super > genJumpIf: boolean to: targetBytecodePC ]. > > self ssFlushTo: simStackPtr - 1. > desc := self ssTop. > self ssPop: 1. > desc popToReg: TempReg. > > + "We need SendNumArgsReg because of the mustBeBooleanTrampoline" > + self ssAllocateRequiredReg: SendNumArgsReg. > + > - "We prefer calleeSaved to avoid saving it across the trap trip > trampoline" > - counterReg := self > allocateRegPreferringCalleeSavedNotConflictingWith: 0. > retry := self Label. > self > genExecutionCountLogicInto: [ :cAddress :countTripBranch | > counterAddress := cAddress. > countTripped := countTripBranch ] > + counterReg: SendNumArgsReg. > - counterReg: counterReg. > counterIndex := counterIndex + 1. > > "Cunning trick by LPD. If true and false are contiguous subtract > the smaller. > Correct result is either 0 or the distance between them. If > result is not 0 or > their distance send mustBeBoolean." > self assert: (objectMemory objectAfter: objectMemory falseObject) > = objectMemory trueObject. > self annotate: (self SubCw: boolean R: TempReg) objRef: boolean. > self JumpZero: (self ensureFixupAt: targetBytecodePC - initialPC). > > + self genFallsThroughCountLogicCounterReg: SendNumArgsReg > counterAddress: counterAddress. > - self genFallsThroughCountLogicCounterReg: counterReg > counterAddress: counterAddress. > > self CmpCq: (boolean == objectMemory falseObject > ifTrue: [objectMemory trueObject - > objectMemory falseObject] > ifFalse: [objectMemory falseObject > - objectMemory trueObject]) > R: TempReg. > ok := self JumpZero: 0. > + self MoveCq: 0 R: SendNumArgsReg. "if counterReg is 0 this is a > mustBeBoolean, not a counter trip." > - self MoveCq: 0 R: counterReg. "if counterReg is 0 this is a > mustBeBoolean, not a counter trip." > > countTripped jmpTarget: > (self CallRT: (boolean == objectMemory falseObject > ifTrue: > [ceSendMustBeBooleanAddFalseTrampoline] > ifFalse: > [ceSendMustBeBooleanAddTrueTrampoline])). > > "If we're in an image which hasn't got the Sista code loaded then > the ceCounterTripped: > trampoline will return directly to machine code, returning the > boolean. So the code should > jump back to the retry point. The trampoline makes sure that > TempReg has been reloaded." > self annotateBytecode: self Label. > > self Jump: retry. > > ok jmpTarget: self Label. > ^0! > >

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Vm-dev May 2015