Vm-dev January 2011

vm-dev@lists.squeakfoundation.org

38 participants
103 discussions

Official VM missing MPEGPlugin
by Matthew Fulmer 17 Jan '11

17 Jan '11

Cog VM includes the MPEGPlugin, but the interpreter VM from http://ftp.squeak.org/4.1/ does not. It's needed by Cobalt. To test: - Load up Movies-Kernel and Movies-Player from http://www.squeaksource.com/MultiMedia.html (aside: anyone know of a more official location for multimedia stuff?) - Get out an MPEGPlayerMorph (World > objects > Multimedia > MPEGPlayer) - press the load button and find your favorite mpeg file. I threw up the one we ship with cobalt in case you don't have one on hand (3.1 MB): http://cobalt.cs.duke.edu/pub/alien.mpeg - official VM will get a primitive failure at this point - Cog will show the first frame of the video and you can watch it by pressing play -- Matthew Fulmer (a.k.a. Tapple)

5 9

more Info in aboutSqueak
by Alexander Lazarević 17 Jan '11

17 Jan '11

2011/1/13 Eliot Miranda <eliot.miranda(a)gmail.com> > Which platform? I infer linux. [Please can we be more informative in > these discussions. It's hard trying to follow all the VM bugs when people > don't specify the platform. please :)] > I always thought it would be nice to have something that offers more info about the system and it's environment than what aboutSqueak shows. Morphic-laza.514 and System-laza.414 in the Inbox are a shot at this. Instead of a dialog this opens a workspace with some more info that can be easily edited/copied/pasted into an email, eg. Image Squeak4.2alpha latest update: #10896 Current Change Set: Unnamed1 H:\Squeak\Squeak4.2-10892-beta.image Operating System/Hardware Win32 6.1 IX86 Virtual Machine Croquet Closure Cog VM [CoInterpreter VMMaker-oscog.35] C:\Program Files\cogwin\Croquet.exe C:\Program Files\cogwin\Croquet.exe Loaded Modules ZipPlugin VMMaker-oscog.35 (i) SocketPlugin VMMaker-oscog.8 (i) LocalePlugin VMMaker-oscog.8 (i) BitBltPlugin VMMaker-oscog.35 (i) B2DPlugin VMMaker-oscog.35 (i) SecurityPlugin VMMaker-oscog.8 (i) FilePlugin VMMaker-oscog.35 (i) LargeIntegers v1.5 VMMaker-oscog.36 (i) MiscPrimitivePlugin VMMaker-oscog.8 (i) Alex

2 2

Problem understanding #cannotInterpret
by Mariano Martinez Peck 17 Jan '11

17 Jan '11

Hi. There is something I don't understand about #cannotInterpret and maybe you can help me. Since I am not sure if this is more image side or vm, I did a cross post, sorry for that. Context: I am implementing proxies for classes. Since I want that a proxy loads back the original object when receiving the message #class, I have removed from the compiler the shortcut bytecode for class, with this: (ParseNode classVarNamed: 'StdSelectors') removeKey: #class ifAbsent: []. Now, my testcase is something like this: | inst proxy | "This is the simplest test that does the less assert as possible." inst := ClassWith1Var new. self assert: inst foo = 'foo'. proxy := ClassProxyInstVar new. proxy become: ClassWith1Var. "here I can send any message, it is just to load back the original class" inst basicIdentityHash. self assert: (inst class == ClassWith1Var). self assert: inst foo = 'foo'. ProtoObject subclass: #ClassProxyInstVar instanceVariableNames: 'superclass methodDict format actualClass' classVariableNames: '' poolDictionaries: '' category: 'Proxies' ClassProxyInstVar >> initialize super initialize. superclass := ProxySuperclass. methodDict := nil. actualClass := self So...with this i can use an instance of ClassProxyInstVar like a class. When an instance of the class receives a message, the methodDict will be in nil, and then the VM will send the #cannotInterpret. and there I want to put back the original class. Then I do: ProxySuperclass >> cannotInterpret: aMessage Transcript cr; show: 'cannotInterpret:'; space; show: aMessage selector.. self class restore. ^aMessage sendTo: self Now, this is working, but there is something I DO NOT UNSERSTAND. When I try to do the "inst basicIdentityHash" the VM will send the #cannotInterpret to ProxySuperclass because the methodDict was nil in ClassProxyInstVar. Ok, perfect. What I don't understand is how the method #cannotInterptet can be run perfeclty in this case, since I am doing a "self class restore" there. Remember I removed the shortcut bytecode, so #class is sent like any normal message. So, my question is, when sending "self class", why the VM doesn't call #cannotInterpter again like it did it when I did " inst basicIdentityHash." ? in other words...why the VM isn't entering in a loop ? There is something I am not seeing. Thanks for any help in advance, Mariano

2 2

new Cog VMs
by Eliot Miranda 15 Jan '11

15 Jan '11

Hi All, I've released a new version of Cog that has a substantially improved code generator along the lines of Peter Deutsch's HPS (VisualWorks) and various of Ian Piumarta's VMs. These all use a simple tecnique to identify constant references in bytecode and to support a register-based calling convention. While this does produce faster code it tends to accelerate low-level code much more than high-level code as you can see by the following benchmarks: SimpleStackBasedCogit: [1 to: 100000000 do: [:i|]] timeToRun 691 StackToRegisterMappingCogit: [1 to: 100000000 do: [:i|]] timeToRun 192 192 - 691 / 6.91 -72% SimpleStackBasedCogit: 0 tinyBenchmarks '753495217 bytecodes/sec; 64769127 sends/sec' StackToRegisterMappingCogit: 0 tinyBenchmarks '931756141 bytecodes/sec; 128157989 sends/sec' 931756141 - 753495217 / 7534952.17 -24% 128157989 - 64769127 / 647691.27 -98% SimpleStackBasedCogit: [Compiler recompileAll] timeToRun 47013 (no transcript StackToRegisterMappingCogit: [Compiler recompileAll] timeToRun 43406 (no transcript) 43406 - 47013 / 470.13 -7.67234594686576 The status of this code is essentially beta. The test suite runs the same on the new code generator as on the old, but I think there are still bugs because I get the occasional transient error. I am therefore very interested in any reproducible errors you can find. The VMs (http://www.mirandabanda.org/files/Cog/VM/VM.r2334/) contain a few other important changes: - a bug fix to bytecode<->native pc mappng that produced incorrect results for methods containing blocks with ^-returns in them. One symptom is incorrect highlighting of the pc in the debugger, althoguh symptoms could be much serious. - jitting interpreted methods on backward branches. Currently any interpreted method that performs more than 20 backward branches will be considered for JIT compilation and if it is suitable (default, <= 60 literals) will be compiled to native code. - new callback support. I need to commit some changes to the Alien package to provide access to this but essentially the VM's callback support is now able to be ported to architectures with register-based calling conventions (ARM, PowerPC, SPARC etc). I'll try and get the Alien code released soon, and to back-port the changes to the standard VM before the end of the holiday. One thing that is still /not/ fixed is the lack of a SoundPlugin on win32. Apologies. I'll try and get a fix for this before the end of the holidays too, but time might be too tight. There are other priorities such as harmonising the standard and Cog VMs for the 4.2 release. best Eliot

4 7

Fwd: [Pharo-users] squeak vm without MMU
by stephane ducasse 13 Jan '11

13 Jan '11

Begin forwarded message: > From: Annick Fron <info(a)afceurope.com> > Date: January 12, 2011 10:26:41 AM GMT+01:00 > To: A friendly place where any question about pharo is welcome <pharo-users(a)lists.gforge.inria.fr> > Subject: [Pharo-users] squeak vm without MMU > Reply-To: A friendly place where any question about pharo is welcome <pharo-users(a)lists.gforge.inria.fr> > > Hi, > > Is it possible to use pharo on a processor with MMU (Memory Unit Management ) ? > Namely my target OS is a Linux with the following differences : > ============ > > The kernel is a collection of patches to make the standard Linux kernel run on CPUs that do not have an MMU. As a consequence you will encounter some differences between the kernel and the standard Linux behavior: > u no fork() – consider using vfork() instead but beware of the difference of their semantics > u no daemon() – it is usually implemented on top of fork and cannot be easily replaced without changing the semantics. > u fixed stack size -- the stack of an application is set at execution time and cannot grow during runtime. The default stack size is 4k! It can be increased with the "-s" option of m68k-uClinux-elf2flat. > u limited libc compared to glibc -- either add more to libc, or remove some functionality. > u no support for ELF binary file format > u very limited support for shared libraries due to missing MMU -- all applications get linked statically > u mmap() is very inefficient > u no paging -- applications have to be loaded completely into RAM, the heap is very susceptible to fragmentation. > ======== > Annick Fron

2 1

Where are precompiled stack VMs or interpreter VMs?
by Matthew Fulmer 13 Jan '11

13 Jan '11

Hi. I'm trying to find a suitable official VM for Cobalt as it draws nearer to being officially a squeak 4.2 application. I've found 3 VM-dependent bugs, and have yet to find a recent VM that exhibits none of them: - FFI support. The latest cog VM's (2339 and later) fail. - Writing sockets incorrectly timeout after 5-30 minutes. Older cog VMs (2316 and earlier) fail; I'm not able to easily test the latest ones due to the first bug - Keyboard Up events are incorrect when multiple keys are pressed at once. The latest vm's on squeakvm.org fail, however, they are nearing a year old, and the cog VMs (all newer) don't have this bug. So, where can I get some newer stack or interpreter VMs than what is on squeakvm.org? I have a feeling they would satisfy all three criteria, but I can't find any. -- Matthew Fulmer (a.k.a. Tapple)

6 17

Re: [Pharo-project] [BUG]LargePositiveInteger(Object)>>error:
by Eliot Miranda 13 Jan '11

13 Jan '11

Hi All, I think I've found the reproducible case for the MessageNotUnderstood: LargePositiveInteger>>pixelValueForDepth: bug in the StackToRegisterMappingCogit. The symptom may be that the register arguments get shuffled incorrectly through an inline send miss. Here's an example that produces an MNU every time: | s a ca | s := #(1 -1). a := Array new: 2. ca := ColorArray new: 2. a replaceFrom: 1 to: 2 with: s. ca replaceFrom: 1 to: 2 with: s. I'll try and look at this this evening. best Eliot On Tue, Jan 11, 2011 at 5:36 PM, Stuart Herring <st-lists(a)stuartherring.com>wrote: > It seems to be related to the VM. > To reproduce, just open a browser and save and quit. > Then opening the image with Cog r2344 or r2345 will result in this > error - it seems to be happening in the startup process. > If you debug it, the code that apparently causes the problem actually > works fine when manually invoked. > > Earlier versions of Cog don't have this problem - r2316 works fine. > I'm using the standard 1.1.1 image on Linux (Omnibrowser is > OB-Standard-lr.479) > > Regards, > Stuart > > On Wed, Jan 12, 2011 at 3:06 AM, Pat Maddox <patmaddox(a)me.com> wrote: > > I used the public 1.1.1 oneclick > > > > > > On Jan 6, 2011, at 1:30 PM, Stéphane Ducasse wrote: > > > >> Thanks pat for the report. > >> > >> Now could you let us know if you loaded OB or if you used the public > 1.1.1 oneclick? > >> > >> Stef > >> > >> On Jan 6, 2011, at 9:18 PM, Pat Maddox wrote: > >> > >>> I opened up an OmniBrowser and scrolled to the very bottom. Then I > clicked on my package name, and then a class name. > >>> > >>> 6 January 2011 12:12:44 pm > >>> > >>> VM: Mac OS - intel - 1065 - Croquet Closure Cog VM [CoInterpreter > VMMaker-oscog.43] Croquet Cog 3.0.0 > >>> Image: Pharo-1.1.1-- [Latest update: #11414] > >>> > >>> SecurityManager state: > >>> Restricted: false > >>> FileAccess: true > >>> SocketAccess: true > >>> Working Dir /Users/padillac/code/pharo_image > >>> Trusted Dir /foobar/tooBar/forSqueak/bogus/ > >>> Untrusted Dir > /Users/padillac/Library/Preferences/Croquet/Internet/Untrusted > >>> > >>> LargePositiveInteger(Object)>>error: > >>> Receiver: 4287876447 > >>> Arguments and temporary variables: > >>> aString: 'MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth:' > >>> Receiver's instance variables: > >>> 4287876447 > >>> > >>> [] in WorldState>>displayWorldSafely: > >>> Receiver: a WorldState > >>> Arguments and temporary variables: > >>> err: 'MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth:' > >>> rcvr: 4287876447 > >>> errCtx: OBLazyListMorph>>display:atRow:on: > >>> errMorph: an OBLazyListMorph(969408512) > >>> Receiver's instance variables: > >>> hands: an Array(a HandMorph(843055104)) > >>> viewBox: 0@0 corner: 2552@1374 > >>> canvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> damageRecorder: a DamageRecorder > >>> stepList: a Heap(StepMessage(#stepAt: -> a > SystemWindow(154664960))(a SystemWin...etc... > >>> lastStepTime: 805471 > >>> lastStepMessage: nil > >>> lastCycleTime: 805463 > >>> commandHistory: a CommandHistory > >>> alarms: a Heap() > >>> lastAlarmTime: 805471 > >>> menuBuilder: a PragmaMenuBuilder > >>> > >>> BlockClosure>>valueWithPossibleArgs: > >>> Receiver: [:err :rcvr | > >>> | errCtx errMorph | > >>> errCtx := thisContext. > >>> [errCtx := errCtx sender. > >>> [err...etc... > >>> Arguments and temporary variables: > >>> anArray: #('MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth:' 42...etc... > >>> Receiver's instance variables: > >>> outerContext: WorldState>>displayWorldSafely: > >>> startpc: 73 > >>> numArgs: 2 > >>> > >>> [] in BlockClosure>>ifError: > >>> Receiver: [aWorld displayWorld] > >>> Arguments and temporary variables: > >>> errorHandlerBlock: MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDep...etc... > >>> ex: [:err :rcvr | > >>> | errCtx errMorph | > >>> errCtx := thisContext. > >>> [errCtx := errCt...etc... > >>> Receiver's instance variables: > >>> outerContext: WorldState>>displayWorldSafely: > >>> startpc: 66 > >>> numArgs: 0 > >>> > >>> BlockClosure>>valueWithPossibleArgs: > >>> Receiver: [:ex | errorHandlerBlock valueWithPossibleArgs: {ex > description. ex receiver}] > >>> Arguments and temporary variables: > >>> anArray: an Array(MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDept...etc... > >>> Receiver's instance variables: > >>> outerContext: BlockClosure>>ifError: > >>> startpc: 40 > >>> numArgs: 1 > >>> > >>> [] in MethodContext(ContextPart)>>handleSignal: > >>> Receiver: BlockClosure>>on:do: > >>> Arguments and temporary variables: > >>> exception: MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth: > >>> Receiver's instance variables: > >>> sender: BlockClosure>>ifError: > >>> pc: 17 > >>> stackp: 3 > >>> method: (BlockClosure>>#on:do: "a > CompiledMethod(280231936)") > >>> closureOrNil: nil > >>> receiver: [aWorld displayWorld] > >>> > >>> BlockClosure>>ensure: > >>> Receiver: [(self tempAt: 2) > >>> valueWithPossibleArgs: {exception}] > >>> Arguments and temporary variables: > >>> aBlock: [self tempAt: 3 put: true] > >>> complete: nil > >>> returnValue: nil > >>> Receiver's instance variables: > >>> outerContext: MethodContext(ContextPart)>>handleSignal: > >>> startpc: 90 > >>> numArgs: 0 > >>> > >>> MethodContext(ContextPart)>>handleSignal: > >>> Receiver: BlockClosure>>on:do: > >>> Arguments and temporary variables: > >>> exception: MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth: > >>> val: nil > >>> Receiver's instance variables: > >>> sender: BlockClosure>>ifError: > >>> pc: 17 > >>> stackp: 3 > >>> method: (BlockClosure>>#on:do: "a > CompiledMethod(280231936)") > >>> closureOrNil: nil > >>> receiver: [aWorld displayWorld] > >>> > >>> MessageNotUnderstood(Exception)>>signal > >>> Receiver: MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth: > >>> Arguments and temporary variables: > >>> > >>> Receiver's instance variables: > >>> messageText: nil > >>> tag: nil > >>> signalContext: MessageNotUnderstood(Exception)>>signal > >>> handlerContext: BlockClosure>>on:do: > >>> outerContext: nil > >>> message: pixelValueForDepth: 32 > >>> receiver: 4287876447 > >>> reachedDefaultHandler: false > >>> > >>> LargePositiveInteger(Object)>>doesNotUnderstand: #pixelValueForDepth: > >>> Receiver: 4287876447 > >>> Arguments and temporary variables: > >>> aMessage: pixelValueForDepth: 32 > >>> exception: MessageNotUnderstood: > LargePositiveInteger>>pixelValueForDepth: > >>> resumeValue: nil > >>> Receiver's instance variables: > >>> 4287876447 > >>> > >>> ColorForm>>colormapIfNeededForDepth: > >>> Receiver: ColorForm(12x12x8) > >>> Arguments and temporary variables: > >>> destDepth: 32 > >>> newMap: a Bitmap of length 256 > >>> i: 3 > >>> iLimiT: 256 > >>> Receiver's instance variables: > >>> bits: #[36 29 11 7 11 10 10 11 9 11 95 10 9 9 10 11 11 > 11 11 11 11 11 10 9 0 8 ...etc... > >>> width: 12 > >>> height: 12 > >>> depth: 8 > >>> offset: 0@0 > >>> colors: a ColorArray((Color r: 0.572 g: 0.804 b: > 0.369) (Color r: 0.564 g: 0.76...etc... > >>> cachedDepth: nil > >>> cachedColormap: nil > >>> > >>> ColorForm>>colormapIfNeededFor: > >>> Receiver: ColorForm(12x12x8) > >>> Arguments and temporary variables: > >>> destForm: DisplayScreen(2552x1374x32) > >>> newMap: nil > >>> color: nil > >>> pv: nil > >>> i: nil > >>> iLimiT: nil > >>> Receiver's instance variables: > >>> bits: #[36 29 11 7 11 10 10 11 9 11 95 10 9 9 10 11 11 > 11 11 11 11 11 10 9 0 8 ...etc... > >>> width: 12 > >>> height: 12 > >>> depth: 8 > >>> offset: 0@0 > >>> colors: a ColorArray((Color r: 0.572 g: 0.804 b: > 0.369) (Color r: 0.564 g: 0.76...etc... > >>> cachedDepth: nil > >>> cachedColormap: nil > >>> > >>> FormCanvas>>image:at:sourceRect:rule: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aForm: ColorForm(12x12x8) > >>> aPoint: 0@15 > >>> sourceRect: 0@0 corner: 12@12 > >>> rule: 24 > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>translucentImage:at:sourceRect: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aForm: ColorForm(12x12x8) > >>> aPoint: 0@15 > >>> sourceRect: 0@0 corner: 12@12 > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>translucentImage:at: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aForm: ColorForm(12x12x8) > >>> aPoint: 0@15 > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> OBLazyListMorph>>display:atRow:on: > >>> Receiver: an OBLazyListMorph(969408512) > >>> Arguments and temporary variables: > >>> item: #renderContentOn: > >>> row: 2 > >>> canvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> drawBounds: 0@14 corner: 190@28 > >>> top: 15 > >>> icon: ColorForm(12x12x8) > >>> name: #arrowUp > >>> Receiver's instance variables: > >>> bounds: 0@0 corner: 190@42 > >>> owner: a TransformMorph(743702528) > >>> submorphs: #() > >>> fullBounds: 0@0 corner: 190@42 > >>> color: Color black > >>> extension: a MorphExtension (970981376) [other: > (errorOnDraw -> true)] > >>> listItems: #(#callbackUrlOn:callback: > #renderContentOn: nil) > >>> font: a StrikeFont(Bitmap DejaVu Sans 9 14) > >>> selectedRow: 0 > >>> selectedRows: a PluggableSet() > >>> listSource: an OBPluggableListMorph(155189248) > >>> maxWidth: 136 > >>> > >>> OBLazyListMorph(LazyListMorph)>>drawOn: > >>> Receiver: an OBLazyListMorph(969408512) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> row: 2 > >>> rowLimiT: 3 > >>> Receiver's instance variables: > >>> bounds: 0@0 corner: 190@42 > >>> owner: a TransformMorph(743702528) > >>> submorphs: #() > >>> fullBounds: 0@0 corner: 190@42 > >>> color: Color black > >>> extension: a MorphExtension (970981376) [other: > (errorOnDraw -> true)] > >>> listItems: #(#callbackUrlOn:callback: > #renderContentOn: nil) > >>> font: a StrikeFont(Bitmap DejaVu Sans 9 14) > >>> selectedRow: 0 > >>> selectedRows: a PluggableSet() > >>> listSource: an OBPluggableListMorph(155189248) > >>> maxWidth: 136 > >>> > >>> FormCanvas(Canvas)>>draw: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> anObject: an OBLazyListMorph(969408512) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>drawMorph: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: an OBLazyListMorph(969408512) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> [] in OBLazyListMorph(Morph)>>fullDrawOn: > >>> Receiver: an OBLazyListMorph(969408512) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 0@0 corner: 190@42 > >>> owner: a TransformMorph(743702528) > >>> submorphs: #() > >>> fullBounds: 0@0 corner: 190@42 > >>> color: Color black > >>> extension: a MorphExtension (970981376) [other: > (errorOnDraw -> true)] > >>> listItems: #(#callbackUrlOn:callback: > #renderContentOn: nil) > >>> font: a StrikeFont(Bitmap DejaVu Sans 9 14) > >>> selectedRow: 0 > >>> selectedRows: a PluggableSet() > >>> listSource: an OBPluggableListMorph(155189248) > >>> maxWidth: 136 > >>> > >>> FormCanvas>>roundCornersOf:in:during: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: an OBLazyListMorph(969408512) > >>> bounds: 0@0 corner: 190@42 > >>> aBlock: [(aCanvas isVisible: self bounds) > >>> ifTrue: [aCanvas drawMorph: self]. > >>> ...etc... > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: an OBLazyListMorph(969408512) > >>> aBlock: [(aCanvas isVisible: self bounds) > >>> ifTrue: [aCanvas drawMorph: self]. > >>> ...etc... > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> OBLazyListMorph(Morph)>>fullDrawOn: > >>> Receiver: an OBLazyListMorph(969408512) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 0@0 corner: 190@42 > >>> owner: a TransformMorph(743702528) > >>> submorphs: #() > >>> fullBounds: 0@0 corner: 190@42 > >>> color: Color black > >>> extension: a MorphExtension (970981376) [other: > (errorOnDraw -> true)] > >>> listItems: #(#callbackUrlOn:callback: > #renderContentOn: nil) > >>> font: a StrikeFont(Bitmap DejaVu Sans 9 14) > >>> selectedRow: 0 > >>> selectedRows: a PluggableSet() > >>> listSource: an OBPluggableListMorph(155189248) > >>> maxWidth: 136 > >>> > >>> FormCanvas(Canvas)>>fullDraw: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> anObject: an OBLazyListMorph(969408512) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: an OBLazyListMorph(969408512) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 2367@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> [] in [] in TransformMorph>>drawSubmorphsOn: > >>> Receiver: a TransformMorph(743702528) > >>> Arguments and temporary variables: > >>> myCanvas: an OBLazyListMorph(969408512) > >>> m: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPluggableListMorph(155189248) > >>> submorphs: an Array(an OBLazyListMorph(969408512)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color transparent > >>> extension: a MorphExtension (745537536) > >>> transform: a MorphicTransform(angle = 0.0; scale = > 1.0; offset = -523@0) > >>> smoothing: 1 > >>> localBounds: nil > >>> > >>> Array(SequenceableCollection)>>reverseDo: > >>> Receiver: an Array(an OBLazyListMorph(969408512)) > >>> Arguments and temporary variables: > >>> aBlock: [:m | myCanvas fullDrawMorph: m] > >>> index: 1 > >>> Receiver's instance variables: > >>> an Array(an OBLazyListMorph(969408512)) > >>> > >>> [] in TransformMorph>>drawSubmorphsOn: > >>> Receiver: a TransformMorph(743702528) > >>> Arguments and temporary variables: > >>> myCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPluggableListMorph(155189248) > >>> submorphs: an Array(an OBLazyListMorph(969408512)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color transparent > >>> extension: a MorphExtension (745537536) > >>> transform: a MorphicTransform(angle = 0.0; scale = > 1.0; offset = -523@0) > >>> smoothing: 1 > >>> localBounds: nil > >>> > >>> FormCanvas>>transformBy:clippingTo:during:smoothing: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aDisplayTransform: a MorphicTransform(angle = 0.0; > scale = 1.0; offset = -523@0...etc... > >>> aClipRect: 520@0 corner: 690@213 > >>> aBlock: [:myCanvas | (self angle ~= 0.0 > >>> or: [self scale ~= 1.0]) > >>> ifTrue: [...etc... > >>> cellSize: 1 > >>> innerRect: nil > >>> patchRect: nil > >>> sourceQuad: nil > >>> warp: nil > >>> start: nil > >>> subCanvas: nil > >>> rule: nil > >>> i: nil > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 1844@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> TransformMorph>>drawSubmorphsOn: > >>> Receiver: a TransformMorph(743702528) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPluggableListMorph(155189248) > >>> submorphs: an Array(an OBLazyListMorph(969408512)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color transparent > >>> extension: a MorphExtension (745537536) > >>> transform: a MorphicTransform(angle = 0.0; scale = > 1.0; offset = -523@0) > >>> smoothing: 1 > >>> localBounds: nil > >>> > >>> [] in TransformMorph(Morph)>>fullDrawOn: > >>> Receiver: a TransformMorph(743702528) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPluggableListMorph(155189248) > >>> submorphs: an Array(an OBLazyListMorph(969408512)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color transparent > >>> extension: a MorphExtension (745537536) > >>> transform: a MorphicTransform(angle = 0.0; scale = > 1.0; offset = -523@0) > >>> smoothing: 1 > >>> localBounds: nil > >>> > >>> FormCanvas>>roundCornersOf:in:during: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: a TransformMorph(743702528) > >>> bounds: 520@0 corner: 690@213 > >>> aBlock: [(aCanvas isVisible: self bounds) > >>> ifTrue: [aCanvas drawMorph: self]. > >>> ...etc... > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 1844@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: a TransformMorph(743702528) > >>> aBlock: [(aCanvas isVisible: self bounds) > >>> ifTrue: [aCanvas drawMorph: self]. > >>> ...etc... > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 1844@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> TransformMorph(Morph)>>fullDrawOn: > >>> Receiver: a TransformMorph(743702528) > >>> Arguments and temporary variables: > >>> aCanvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPluggableListMorph(155189248) > >>> submorphs: an Array(an OBLazyListMorph(969408512)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color transparent > >>> extension: a MorphExtension (745537536) > >>> transform: a MorphicTransform(angle = 0.0; scale = > 1.0; offset = -523@0) > >>> smoothing: 1 > >>> localBounds: nil > >>> > >>> FormCanvas(Canvas)>>fullDraw: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> anObject: a TransformMorph(743702528) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 1844@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> Receiver: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Arguments and temporary variables: > >>> aMorph: a TransformMorph(743702528) > >>> Receiver's instance variables: > >>> target: nil > >>> filterSelector: nil > >>> origin: 1844@187 > >>> clipRect: 2364@187 corner: 2534@400 > >>> form: DisplayScreen(2552x1374x32) > >>> port: a GrafPort > >>> shadowColor: nil > >>> > >>> [] in [] in OBPluggableListMorph(Morph)>>drawSubmorphsOn: > >>> Receiver: an OBPluggableListMorph(155189248) > >>> Arguments and temporary variables: > >>> canvas: a TransformMorph(743702528) > >>> m: a FormCanvas on: DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPane(127401984) > >>> submorphs: an Array(a TransformMorph(743702528)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color white > >>> extension: a MorphExtension (132644864) [other: > (dragEnabled -> true) (dropEna...etc... > >>> borderWidth: 0 > >>> borderColor: Color black > >>> model: an OBColumn() > >>> slotName: nil > >>> open: false > >>> scrollBar: a ScrollBar(161742848) > >>> scroller: a TransformMorph(743702528) > >>> retractableScrollBar: false > >>> scrollBarOnLeft: false > >>> getMenuSelector: #menu: > >>> getMenuTitleSelector: nil > >>> hasFocus: false > >>> hScrollBar: a ScrollBar(990642176) > >>> list: nil > >>> getListSelector: #list > >>> getListSizeSelector: #listSize > >>> getListElementSelector: #listAt: > >>> getIndexSelector: #selection > >>> setIndexSelector: #selection: > >>> keystrokeActionSelector: #keystroke:from: > >>> autoDeselect: false > >>> lastKeystrokeTime: 0 > >>> lastKeystrokes: '' > >>> doubleClickSelector: #doubleClick > >>> handlesBasicKeys: nil > >>> potentialDropRow: nil > >>> listMorph: an OBLazyListMorph(969408512) > >>> hScrollRangeCache: nil > >>> > >>> Array(SequenceableCollection)>>reverseDo: > >>> Receiver: an Array(a TransformMorph(743702528)) > >>> Arguments and temporary variables: > >>> aBlock: [:m | canvas fullDrawMorph: m] > >>> index: 1 > >>> Receiver's instance variables: > >>> an Array(a TransformMorph(743702528)) > >>> > >>> [] in OBPluggableListMorph(Morph)>>drawSubmorphsOn: > >>> Receiver: an OBPluggableListMorph(155189248) > >>> Arguments and temporary variables: > >>> canvas: a FormCanvas on: > DisplayScreen(2552x1374x32) > >>> Receiver's instance variables: > >>> bounds: 520@0 corner: 690@213 > >>> owner: an OBPane(127401984) > >>> submorphs: an Array(a TransformMorph(743702528)) > >>> fullBounds: 520@0 corner: 690@213 > >>> color: Color white > >>> extension: a MorphExtension (132644864) [other: > (dragEnabled -> true) (dropEna...etc... > >>> borderWidth: 0 > >>> borderColor: Color black > >>> model: an OBColumn() > >>> slotName: nil > >>> open: false > >>> scrollBar: a ScrollBar(161742848) > >>> scroller: a TransformMorph(743702528) > >>> retractableScrollBar: false > >>> scrollBarOnLeft: false > >>> getMenuSelector: #menu: > >>> getMenuTitleSelector: nil > >>> hasFocus: false > >>> hScrollBar: a ScrollBar(990642176) > >>> list: nil > >>> getListSelector: #list > >>> getListSizeSelector: #listSize > >>> getListElementSelector: #listAt: > >>> getIndexSelector: #selection > >>> setIndexSelector: #selection: > >>> keystrokeActionSelector: #keystroke:from: > >>> autoDeselect: false > >>> lastKeystrokeTime: 0 > >>> lastKeystrokes: '' > >>> doubleClickSelector: #doubleClick > >>> handlesBasicKeys: nil > >>> potentialDropRow: nil > >>> listMorph: an OBLazyListMorph(969408512) > >>> hScrollRangeCache: nil > >>> > >>> > >>> --- The full stack --- > >>> LargePositiveInteger(Object)>>error: > >>> [] in WorldState>>displayWorldSafely: > >>> BlockClosure>>valueWithPossibleArgs: > >>> [] in BlockClosure>>ifError: > >>> BlockClosure>>valueWithPossibleArgs: > >>> [] in MethodContext(ContextPart)>>handleSignal: > >>> BlockClosure>>ensure: > >>> MethodContext(ContextPart)>>handleSignal: > >>> MessageNotUnderstood(Exception)>>signal > >>> LargePositiveInteger(Object)>>doesNotUnderstand: #pixelValueForDepth: > >>> ColorForm>>colormapIfNeededForDepth: > >>> ColorForm>>colormapIfNeededFor: > >>> FormCanvas>>image:at:sourceRect:rule: > >>> FormCanvas(Canvas)>>translucentImage:at:sourceRect: > >>> FormCanvas(Canvas)>>translucentImage:at: > >>> OBLazyListMorph>>display:atRow:on: > >>> OBLazyListMorph(LazyListMorph)>>drawOn: > >>> FormCanvas(Canvas)>>draw: > >>> FormCanvas(Canvas)>>drawMorph: > >>> [] in OBLazyListMorph(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> OBLazyListMorph(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in TransformMorph>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in TransformMorph>>drawSubmorphsOn: > >>> FormCanvas>>transformBy:clippingTo:during:smoothing: > >>> TransformMorph>>drawSubmorphsOn: > >>> [] in TransformMorph(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> TransformMorph(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in OBPluggableListMorph(Morph)>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in OBPluggableListMorph(Morph)>>drawSubmorphsOn: > >>> - - - - - - - - - - - - - - - > >>> - - - - - - - - - - - - - - - - - - > >>> OBPluggableListMorph(Morph)>>drawSubmorphsOn: > >>> OBPluggableListMorph(PluggableListMorph)>>drawSubmorphsOn: > >>> [] in OBPluggableListMorph(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> OBPluggableListMorph(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in OBPane(Morph)>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in OBPane(Morph)>>drawSubmorphsOn: > >>> FormCanvas>>clipBy:during: > >>> OBPane(Morph)>>drawSubmorphsOn: > >>> [] in OBPane(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> OBPane(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in TransformMorph>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in TransformMorph>>drawSubmorphsOn: > >>> FormCanvas>>transformBy:clippingTo:during:smoothing: > >>> TransformMorph>>drawSubmorphsOn: > >>> [] in TransformMorph(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> TransformMorph(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in OBPaneScroller(Morph)>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in OBPaneScroller(Morph)>>drawSubmorphsOn: > >>> OBPaneScroller(Morph)>>drawSubmorphsOn: > >>> [] in OBPaneScroller(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> OBPaneScroller(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in OBGroupingMorph(Morph)>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in OBGroupingMorph(Morph)>>drawSubmorphsOn: > >>> OBGroupingMorph(Morph)>>drawSubmorphsOn: > >>> [] in OBGroupingMorph(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> OBGroupingMorph(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in SystemWindow(Morph)>>drawSubmorphsOn: > >>> Array(SequenceableCollection)>>reverseDo: > >>> [] in SystemWindow(Morph)>>drawSubmorphsOn: > >>> FormCanvas>>clipBy:during: > >>> SystemWindow(Morph)>>drawSubmorphsOn: > >>> [] in SystemWindow(Morph)>>fullDrawOn: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> SystemWindow(Morph)>>fullDrawOn: > >>> FormCanvas(Canvas)>>fullDraw: > >>> FormCanvas(Canvas)>>fullDrawMorph: > >>> [] in [] in WorldState>>drawWorld:submorphs:invalidAreasOn: > >>> Rectangle>>allAreasOutsideList:startingAt:do: > >>> Rectangle>>allAreasOutsideList:do: > >>> [] in WorldState>>drawWorld:submorphs:invalidAreasOn: > >>> Array(SequenceableCollection)>>do: > >>> WorldState>>drawWorld:submorphs:invalidAreasOn: > >>> [] in WorldState>>displayWorld:submorphs: > >>> FormCanvas>>roundCornersOf:in:during: > >>> FormCanvas(Canvas)>>roundCornersOf:during: > >>> WorldState>>displayWorld:submorphs: > >>> PasteUpMorph>>privateOuterDisplayWorld > >>> PasteUpMorph>>displayWorld > >>> [] in WorldState>>displayWorldSafely: > >>> BlockClosure>>on:do: > >>> BlockClosure>>ifError: > >>> WorldState>>displayWorldSafely: > >>> WorldState>>doOneCycleNowFor: > >>> WorldState>>doOneCycleFor: > >>> PasteUpMorph>>doOneCycle > >>> [] in Project class>>spawnNewProcess > >>> [] in BlockClosure>>newProcess > >>> > >> > >> > > > > > > > >

1 1

[Cog] Funny thing about time
by Igor Stasenko 12 Jan '11

12 Jan '11

Yesterday on my comp two separate running images are hung simultaneously, while i were doing something completely outside of them. And now during reading the sqUnixHeartBeat.c: /* The native clock may go backwards, e.g. due to NTP adjustments, although * why it can't avoid small backward steps itself, I don't know. Simply * ignore backward steps and wait until the clock catches up again. Of * course this will cause problems if the clock is manually adjusted. To * which the doctor says, "don't do that". */ i start recalling that yesterday i adjusted clock back by 1 hour, because after installing a windoze in dual boot it was set it wrongly. But of course it could be anything else :) -- Best regards, Igor Stasenko AKA sig.

7 7

pinning GC
by Eliot Miranda 12 Jan '11

12 Jan '11

Hi All, as I've mentioned I've been thinking of implementing a pinning GC for the threaded Cog VM. Pinning is really important for a threaded FFI since the GC can run in parallel with FFI calls and so move objects while FFI calls are in progress. The idea then is to arrange that every object passed out through the FFI is pinned. This is easy to do in a Smalltalk VM that has an object table; an object header bit is used as the "is pinned" flag. The marshalling code in FFI calls checks the "is pinned" bit and if not set, allocates a clone of the object in a region of the heap that the GC does not compact, with the "is pinned" bit set, and does a become. In a Smalltalk VM without an object table (Squeak, VisualAge etc) this is more challenging. But a recent comment on Gilad Bracha's Newspeak blog by "TruePath" (who's he? ed.) points out a technique that applies: "Remember smalltalk is a dynamic language so every method call (and that is all there is) requires we check the type pointer and (if the PIC or other caches don't include an appropriate entry) use the type to resolve the method call. One could easily have a special type that escapes into the runtime on any message at which point the runtime replaces the reference the message call was dispatch on with the new location and retries the call. Indeed, any modern GC has to have some way of doing indirection like this so the heap can be compacted." So the FFI marshalling code checks the "is pinned" bit, and if unset allocates a clone of the object in a region of the heap that the GC does not compact, changes the class/type field of the object to the special "i'm a forwarding corpse" value, and sets a forwarding pointer to the pinned copy. There are two problems with this. One, it doesn't work for objects with named inst vars; in Smalltalk an object's named inst vars are accessed directly. But that's easy; one likely doesn't have any business handing out such objects through the FFI, so we can fail calls that do this, and provide special wrappers to hand-out indirect references to objects with named inst vars. (There was a discussion on this approach last year; Andreas proposed a generic object handle scheme). Two, there needs to be room in the corpse for a forwarding pointer to the pinned copy. There isn't enough space in a zero-sized byte data. But one has no business handing pout pointers to empty byte data anyway; attempts to write data into them must overwrite the heap, potentially disastrously. So the FFI can either pass zero-sized objects as null pointers or fail the call. So there will always be enough room in byte data to corpse it to a pinned copy because we'll only attempt the operation on non-empty objects (and the underlying heap representation will round up the size of any object to at least a pointers width). So all one needs is a special class marker, say 0, for corpses. The GC must be modified to follow the forwarding pointer through corpses, as must the message lookup machinery. The heap must have a region that is not compacted (such as old space, which could have a free list and be compacted only on snapshot - i.e. writing a file that has the free space squeezed out, but that /does not/ move objects in the heap, such as VW's image file format, and hence the compaction actually happens on image load when the objects in the snapshot file are relocated and pointers swizzled). This should have been obvious to me, but became so only on reading TruePath's comment (thanks again). best Eliot

4 6

Another way to crash the VM (was:Re: [Vm-dev] pinning GC)
by Igor Stasenko 12 Jan '11

12 Jan '11

> > myMethod > > x := 1. > self becomeForward: y. > x := 5. > > in the above, x is an instance variable of receiver. > If become primitive turns receiver oop into forwarding corpse, now we > have a problem that > after returning back to given method, a bytecode will attempt to write > new ivar value at old location, > instead of a new one, since receiver reference are not updated and > still points to old object memory location. > The code above crashing Squeak VM (and i guess Cog as well). I wonder, what security measures can be added to VM in order to prevent it from crashing or corrupting the object memory. The problem is that at any moment, a receiver's identity could change (it could be due to use of become either in some nested message sends, or even in higher priority process, which interrupted a current one), and after activating the context back, we have a real problem, because there is no range/format checking for receiver, to make sure that it is safe to continue run given compiled method. -- Best regards, Igor Stasenko AKA sig.

1 0

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Vm-dev January 2011