VM Maker: Cog-eem.420.mcz

 
Eliot Miranda uploaded a new version of Cog to project VM Maker:
http://source.squeak.org/VMMaker/Cog-eem.420.mcz

==================== Summary ====================

Name: Cog-eem.420
Author: eem
Time: 28 October 2020, 7:15:44.003408 pm
UUID: b03ad887-622e-4bf4-9fe4-7470af59aa6c
Ancestors: Cog-eem.419

Fix the stack stitching code.  Fix MultiProcessor's desNotUnderstand: handler to return the non-virtual processor to the second trap continuation.  ANd no breaks for the wicked...

=============== Diff against Cog-eem.419 ===============

Item was changed:
  ----- Method: MultiProcessor>>doesNotUnderstand: (in category 'message forwarding') -----
  doesNotUnderstand: aMessage
  "Forward a message to the actual processor, managing a thread-switch if necessary.
  Catch ProcessorSimulationTraps and raise them outside of the critical section to
  avoid deadlock when reentering the VM from a trap and switching threads in the run-time."
  | selector result trap contextInCritical |
  selector := aMessage selector.
  (guardedProcessorProtocol includes: selector) ifFalse:
  [^(unguardedProcessorProtocol includes: selector)
  ifTrue: [processor perform: selector withArguments: aMessage arguments]
  ifFalse: [super doesNotUnderstand: aMessage]].
  result := [mutex critical:
  [contextInCritical := thisContext.
  owner ~~ mutex owningProcess ifTrue:
  [owner ifNotNil:
  [registerState at: owner put: processor registerState].
  (registerState at: (owner := mutex owningProcess) ifAbsent: nil)
  ifNil: [coInterpreter initializeProcessorForThreadIndex: (threadIndex := threadIndex + 1)]
  ifNotNil: [:newState| processor setRegisterState: newState]].
  processor perform: selector withArguments: aMessage arguments]]
  on: ProcessorSimulationTrap, Error, AssertionFailure
  do: [:ex|
  ex class == ProcessorSimulationTrap ifFalse:
  [ex pass].
  "Alas things are not so simple with ARMv8 ldp/stp...
  The comments in these two methods explain..."
  (self isAboutToReturn: ex signalerContext) ifFalse:
  [self saveStackFor: ex signalerContext
  above: contextInCritical
  homeContext: thisContext home].
  trap := ex].
+ ^trap
+ ifNil: [result]
+ ifNotNil: [trap signal ifNotNil:
+ [:resultOfSignal|
+ resultOfSignal == self
+ ifTrue: [processor]
+ ifFalse: [resultOfSignal]]]!
- ^trap ifNil: [result] ifNotNil: [trap signal]!

Item was changed:
  ----- Method: MultiProcessor>>saveStackFor:above:homeContext: (in category 'private-deep hackery') -----
  saveStackFor: signalerContext above: contextInCritical homeContext: doesNotUnderstandContext
  "Some processors, notably ARMv8, support load/store pair instructions which may raise two
  ProcessorSimulationTraps. To handle this we must preserve the continuation following the
+ raising of the first simulation trap.  This cuts up, and restitches the stack so that when the
- raising of the first simulaiton trap.  This cuts up, and restitches the stack so that when the
  first ProcessorSimulationTrap is raised outside the critical: block in our doesNotUnderstand:
  method, control continues to the second trap."
+ | contextAboveContextInCritical contextAboveSignalerContext |
+ "This is the bottom context in the saved continuation, which must be stitched in beneath the doesNotUnderstand: handler."
+ contextAboveContextInCritical := signalerContext findContextSuchThat: [:ctxt| ctxt sender == contextInCritical].
- | contextAboveSignalerContext |
  "This is our continuation, which should be changed to continue back into the critical section."
  contextAboveSignalerContext := thisContext findContextSuchThat: [:ctxt| ctxt sender == signalerContext].
  self deny: contextAboveSignalerContext isNil.
 
  "signalerContext through the context above contextInCritical is the stack that is the continuation
  for the trap.  This must be inserted between the doesNotUnderstandContext and its sender.
  N.B. Context>>cut: cuts above the argument!!!!"
  signalerContext cut: contextInCritical.
+ contextAboveContextInCritical privSender: doesNotUnderstandContext sender.
- contextInCritical privSender: doesNotUnderstandContext sender.
  doesNotUnderstandContext privSender: signalerContext.
 
  "Now arrange that the handler returns to contextInCritical; and we're done."
  contextAboveSignalerContext privSender: contextInCritical!

Item was changed:
  ----- Method: ProcessorSimulatorPlugin>>singleStepCPU:In:Size:MinAddressRead:Write: (in category 'simulation') -----
  singleStepCPU: cpu In: memoryCArray Size: memorySize MinAddressRead: minAddress Write: minWriteMaxExecAddress
  <doNotGenerate>
  "*now* we need derived pointers. Ho hum...
  But all we need is one more level of indirection..."
  | result |
- self break.
  result := mySimulatorAlien
  rawPrimitiveSingleStepInMemory: interpreterProxy memory
  offsetBy: memoryCArray ptrAddress
  minimumAddress: minAddress
  readOnlyBelow: minWriteMaxExecAddress.
  ^result == mySimulatorAlien
  ifTrue: [0]
  ifFalse:
  [result isPrimitiveError
  ifTrue: [result errorCode]
  ifFalse: [result]]!