VM Maker: VMMaker.oscog-eem.2394.mcz

 
Eliot Miranda uploaded a new version of VMMaker to project VM Maker:
http://source.squeak.org/VMMaker/VMMaker.oscog-eem.2394.mcz

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

Name: VMMaker.oscog-eem.2394
Author: eem
Time: 30 May 2018, 12:31:53.985094 pm
UUID: 61ae96f8-fd2b-4208-87ff-cf1cd6b3f859
Ancestors: VMMaker.oscog-eem.2393

SpurSelectiveCompactor:
Add a guard to followForwardingPointersInStackZone: to avoid scanning teh stack zone when it is empty because the system is snapshotting.

=============== Diff against VMMaker.oscog-eem.2393 ===============

Item was changed:
  ----- Method: StackInterpreter>>externalWriteBackHeadFramePointers (in category 'stack pages') -----
  externalWriteBackHeadFramePointers
  self assert:  (framePointer - stackPointer) < (LargeContextSlots * objectMemory bytesPerOop).
  self assert: stackPage = stackPages mostRecentlyUsedPage.
+ self deny: stackPage isFree.
  self setHeadFP: framePointer andSP: stackPointer inPage: stackPage.
  self assert: stackPages pageListIsWellFormed!

Item was changed:
  ----- Method: StackInterpreter>>followForwardingPointersInStackZone: (in category 'object memory support') -----
  followForwardingPointersInStackZone: theBecomeEffectsFlags
  "Spur's become: is lazy, turning the becommed object into a forwarding object to the other.
  The read-barrier is minimised by arranging that forwarding pointers will fail a method cache
  probe, since notionally objects' internals are accessed only via sending messages to them,
  the exception is primitives that access the internals of the non-receiver argument(s).
 
  To avoid a read barrier on bytecode, literal and inst var fetch and non-local return, we scan
  the receivers (including the stacked receiver for non-local return) and method references
  in the stack zone and follow any forwarded ones.  This is of course way cheaper than
  scanning all of memory as in the old become."
  | theIPPtr |
  <inline: false>
  <var: #theFP type: #'char *'>
  <var: #theIPPtr type: #usqInt>
  <var: #callerFP type: #'char *'>
  <var: #thePage type: #'StackPage *'>
 
+ stackPage = 0 ifTrue: "the system must be snapshotting; nothing to do..."
+ [self assert: stackPages mostRecentlyUsedPage isFree.
+ self cCode: [] inSmalltalk: [stackPages allPagesFree].
+ ^self].
+
  self externalWriteBackHeadFramePointers.
 
  (theBecomeEffectsFlags anyMask: BecameCompiledMethodFlag) ifTrue:
  [(objectMemory isForwarded: method) ifTrue:
  [theIPPtr := instructionPointer - method.
  method := objectMemory followForwarded: method.
  instructionPointer := method + theIPPtr].
  (objectMemory isOopForwarded: newMethod) ifTrue:
  [newMethod := objectMemory followForwarded: newMethod]].
 
  self assert: stackPage ~= 0.
  0 to: numStackPages - 1 do:
  [:i| | thePage theFP callerFP offset oop |
  thePage := stackPages stackPageAt: i.
  thePage isFree ifFalse:
  [self assert: (self ifCurrentStackPageHasValidHeadPointers: thePage).
  theFP := thePage  headFP.
  "Skip the instruction pointer on top of stack of inactive pages."
  theIPPtr := thePage = stackPage ifTrue: [0] ifFalse: [thePage headSP asUnsignedInteger].
  [self assert: (thePage addressIsInPage: theFP).
   self assert: (theIPPtr = 0 or: [thePage addressIsInPage: theIPPtr asVoidPointer]).
   oop := stackPages longAt: theFP + FoxReceiver.
   (objectMemory isOopForwarded: oop) ifTrue:
  [stackPages
  longAt: theFP + FoxReceiver
  put: (objectMemory followForwarded: oop)].
   ((self frameHasContext: theFP)
    and: [(objectMemory isForwarded: (self frameContext: theFP))]) ifTrue:
  [stackPages
  longAt: theFP + FoxThisContext
  put: (objectMemory followForwarded: (self frameContext: theFP))].
   oop := self frameMethod: theFP.
   (objectMemory isForwarded: oop) ifTrue:
  [| newOop delta |
  newOop := objectMemory followForwarded: oop.
  theIPPtr ~= 0 ifTrue:
  [self assert: (stackPages longAt: theIPPtr) > (self frameMethod: theFP).
  delta := newOop - oop.
  stackPages
  longAt: theIPPtr
  put: (stackPages longAt: theIPPtr) + delta].
  stackPages
  longAt: theFP + FoxMethod
  put: (oop := newOop)].
   offset := self frameStackedReceiverOffset: theFP.
   oop := stackPages longAt: theFP + offset.
   (objectMemory isOopForwarded: oop) ifTrue:
  [stackPages
  longAt: theFP + offset
  put: (objectMemory followForwarded: oop)].
   (callerFP := self frameCallerFP: theFP) ~= 0] whileTrue:
  [theIPPtr := (theFP + FoxCallerSavedIP) asUnsignedInteger.
  theFP := callerFP].
  "And finally follow the caller context."
  self assert: theFP = thePage baseFP.
  oop := self frameCallerContext: theFP.
  (objectMemory isForwarded: oop) ifTrue:
  [self frameCallerContext: theFP put: (objectMemory followForwarded: oop)]]]!