[Vm-dev] VM Maker: VMMaker.oscog-cb.2104.mcz

[commits at source.squeak.org]

ClementBera uploaded a new version of VMMaker to project VM Maker:
http://source.squeak.org/VMMaker/VMMaker.oscog-cb.2104.mcz

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

Name: VMMaker.oscog-cb.2104
Author: cb
Time: 19 January 2017, 11:58:35.234079 am
UUID: 90bbfa32-c00f-4e99-a486-2febcdc203da
Ancestors: VMMaker.oscog-cb.2103

Fixed a bug in eventualTargetOf: where nExts was misscomputed, leading jumps targeting jumps with extensions to be incorrectly computed.

Fixed a bug where branchIfNotInstanceOf: span function misscomputed the distance when ExtB is negated to inverse the branch.

=============== Diff against VMMaker.oscog-cb.2103 ===============

Item was changed:
  ----- Method: SimpleStackBasedCogit>>v4:Long:BranchIfNotInstanceOf:Distance: (in category 'span functions') -----
  v4: descriptor Long: pc BranchIfNotInstanceOf: nExts Distance: aMethodObj
  	"**	254		11111110	kkkkkkkk	jjjjjjjj		branch If Not Instance Of Behavior/Array Of Behavior kkkkkkkk (+ Extend A * 256, where Extend A >= 0) distance jjjjjjjj (+ Extend B * 256, where Extend B >= 0)"
  	<var: #descriptor type: #'BytecodeDescriptor *'>
  	| extBValue |
  	self assert: nExts >= 0.
  	self parseV4Exts: nExts priorTo: pc in: aMethodObj into: [:ea :eb| extBValue := eb].
+ 	extBValue < 0 ifTrue: [extBValue := extBValue + 128].
  	^(objectMemory fetchByte: pc + 2 ofObject: aMethodObj) + (extBValue << 8)!

Item was changed:
  ----- Method: StackToRegisterMappingCogit>>eventualTargetOf: (in category 'peephole optimizations') -----
  eventualTargetOf: targetBytecodePC
  	"Attempt to follow a branch to a pc.  Handle branches to unconditional jumps
  	 and branches to push: aBoolean; conditional branch pairs.  If the branch cannot
  	 be followed answer targetBytecodePC."
  
  	| currentTarget nextPC nExts descriptor span cond |
  	<var: #descriptor type: #'BytecodeDescriptor *'>
  	nextPC := currentTarget := targetBytecodePC.
+ 	[ nExts := 0.
+ 	 [descriptor := self generatorAt: bytecodeSetOffset
- 	[[nExts := 0.
- 	  descriptor := self generatorAt: bytecodeSetOffset
  								+ (objectMemory fetchByte: nextPC ofObject: methodObj).
  	  descriptor isReturn ifTrue: [^currentTarget]. "avoid stepping off the end of methods"
  	  descriptor isExtension]
  		whileTrue:
  			[nExts := nExts + 1.
  			 nextPC := nextPC + descriptor numBytes].
  	 descriptor isUnconditionalBranch
  		ifTrue:
  			[span := self spanFor: descriptor at: nextPC exts: nExts in: methodObj.
  			 span < 0 ifTrue: "Do *not* follow backward branches; these are interrupt points and should not be elided."
  				[^currentTarget].
  			 nextPC := nextPC + descriptor numBytes + span]
  		ifFalse:
  			[descriptor generator == #genPushConstantTrueBytecode ifTrue: [ cond := true ]
  			 ifFalse: [ descriptor generator == #genPushConstantFalseBytecode ifTrue: [ cond := false ] 							ifFalse: [ ^currentTarget ] ].
  			 "Don't step into loops across a pushTrue; jump:if: boundary, so as not to confuse stack depth fixup."
  			 (fixups at: nextPC - initialPC) isBackwardBranchFixup ifTrue:
  				[^currentTarget].
  			 nextPC := self eventualTargetOf: nextPC + descriptor numBytes.
  			 nExts := 0.
  			 [descriptor := self generatorAt: bytecodeSetOffset
  								+ (objectMemory fetchByte: nextPC ofObject: methodObj).
  			  descriptor isReturn ifTrue: [^currentTarget]. "avoid stepping off the end of methods"
  			  descriptor isExtension]
  				whileTrue:
  					[nExts := nExts + 1.
  					 nextPC := nextPC + descriptor numBytes].
  			 descriptor isBranch ifFalse:
  				[^currentTarget].
  			 descriptor isUnconditionalBranch ifTrue:
  				[^currentTarget].
  			 nextPC := cond == descriptor isBranchTrue
  									ifTrue: [nextPC
  											+ descriptor numBytes
  											+ (self spanFor: descriptor at: nextPC exts: nExts in: methodObj)]
  									ifFalse: [nextPC + descriptor numBytes]].
  	 currentTarget := nextPC]
  		repeat!