[Vm-dev] VM Maker: VMMaker.oscog-cb.1216.mcz

[commits at source.squeak.org]

Eliot Miranda uploaded a new version of VMMaker to project VM Maker:
http://source.squeak.org/VMMaker/VMMaker.oscog-cb.1216.mcz

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

Name: VMMaker.oscog-cb.1216
Author: cb
Time: 17 April 2015, 7:13:59.32 pm
UUID: f8d9c5c3-14f2-42ae-a382-6d7623ed69b1
Ancestors: VMMaker.oscog-cb.1215

fix a bug where some #== followed by a branch would not generate the compare instruction before the jumpZero.

=============== Diff against VMMaker.oscog-cb.1215 ===============

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 primDescriptor branchDescriptor nExts label counterReg fixup
  	  counterAddress countTripped unforwardArg unforwardRcvr argReg rcvrReg regMask |
  	<var: #fixup type: #'BytecodeFixup *'>
  	<var: #countTripped type: #'AbstractInstruction *'>
  	<var: #primDescriptor type: #'BytecodeDescriptor *'>
  	<var: #branchDescriptor type: #'BytecodeDescriptor *'>
  
  	((coInterpreter isOptimizedMethod: methodObj) or: [needsFrame not]) ifTrue: [ ^ super genSpecialSelectorEqualsEquals ].
  
  	primDescriptor := self generatorAt: byte0.
  	regMask := 0.
  
  	nextPC := bytecodePC + primDescriptor numBytes.
  	nExts := 0.
  	[branchDescriptor := self generatorAt: (objectMemory fetchByte: nextPC ofObject: methodObj) + (byte0 bitAnd: 256).
  	 branchDescriptor isExtension] whileTrue:
  		[nExts := nExts + 1.
  		 nextPC := nextPC + branchDescriptor numBytes].
  	
  	(branchDescriptor isBranchTrue or: [branchDescriptor isBranchFalse]) ifTrue:
  		[self ssFlushTo: simStackPtr - 2].
  	
  	unforwardRcvr := (objectRepresentation isUnannotatableConstant: (self ssValue: 1)) not.
  	unforwardArg := (objectRepresentation isUnannotatableConstant: self ssTop) not.
  	
  	"if the rcvr or the arg is an annotable constant, we need to push it to a register 
  	else the forwarder check can't jump back to the comparison after unforwarding the constant"
  	unforwardArg
  		ifTrue: 
  			[unforwardRcvr
  				ifTrue:
  					[self allocateTwoRegistersInto: [:rTop :rNext| argReg := rTop. rcvrReg := rNext].
  					 self ssTop popToReg: argReg.
  					 (self ssValue:1) popToReg: rcvrReg]
  				ifFalse:
  					[argReg := self allocateOneRegister.
  					 self ssTop popToReg: argReg]]
  		ifFalse:
  			[self assert: unforwardRcvr.
  			 rcvrReg := self allocateOneRegister.
  			 (self ssValue:1) popToReg: rcvrReg].
  		
  	argReg ifNotNil: [ regMask := self registerMaskFor: regMask ].
  	rcvrReg ifNotNil: [ regMask := regMask bitOr: (self registerMaskFor: rcvrReg) ].
  	
  	"Here we can use Cq because the constant does not need to be annotated"
  	self assert: (unforwardArg not or: [argReg notNil]).
  	self assert: (unforwardRcvr not or: [rcvrReg notNil]).
  	
  	"Only interested in inlining if followed by a conditional branch."
  	(branchDescriptor isBranchTrue or: [branchDescriptor isBranchFalse]) ifFalse:
  		[^ self genDirectEqualsEqualsArg: unforwardArg rcvr: unforwardRcvr argReg: argReg rcvrReg: rcvrReg].
  
  	targetBytecodePC := nextPC
  							+ branchDescriptor numBytes
  							+ (self spanFor: branchDescriptor at: nextPC exts: nExts in: methodObj).
  	postBranchPC := nextPC + branchDescriptor numBytes.
  
  	counterReg := self allocateRegisterNotConflictingWith: regMask. "Use this as the count reg, can't conflict with the registers for the arg and the receiver of #==."
  	counterAddress := counters + ((self sizeof: #sqInt) * counterIndex).
  	self flag: 'will need to use MoveAw32:R: if 64 bits'.
  	self assert: objectMemory wordSize = CounterBytes.
  	self MoveAw: counterAddress R: counterReg.
  	self SubCq: 16r10000 R: counterReg. "Count executed"
  	"If counter trips simply abort the inlined comparison and send continuing to the following
  	 branch *without* writing back.  A double decrement will not trip the second time."
  	countTripped := self JumpCarry: 0.
  	self MoveR: counterReg Aw: counterAddress. "write back"
  	
  	self assert: (unforwardArg or: [ unforwardRcvr ]).
  	
  	label := self Label.
  	
+ 	unforwardArg 
+ 		ifFalse: [ self CmpCq: self ssTop constant R: rcvrReg ]
+ 		ifTrue: [ unforwardRcvr
+ 			ifFalse: [ self CmpCq: (self ssValue: 1) constant R: argReg ]
+ 			ifTrue: [ self CmpR: argReg R: rcvrReg ] ].	
+ 	
+ 	self ssPop: 2.
  	branchDescriptor isBranchTrue ifTrue: 
+ 		[ fixup := self ensureNonMergeFixupAt: postBranchPC - initialPC.
- 		[ self ssPop: 2.
- 		fixup := self ensureNonMergeFixupAt: postBranchPC - initialPC.
  		self JumpZero: (self ensureNonMergeFixupAt: targetBytecodePC - initialPC) asUnsignedInteger.
  		unforwardArg ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: argReg scratchReg: TempReg jumpBackTo: label  ].
+ 		unforwardRcvr ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: rcvrReg scratchReg: TempReg jumpBackTo: label ] ].
- 		unforwardRcvr ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: rcvrReg scratchReg: TempReg jumpBackTo: label ].
- 		self ssPop: -2. ].
  	branchDescriptor isBranchFalse ifTrue: 
+ 		[ fixup := self ensureNonMergeFixupAt: targetBytecodePC - initialPC.
- 		[ self ssPop: 2.
- 		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. 
- 		unforwardRcvr ifTrue: [ objectRepresentation genEnsureOopInRegNotForwarded: rcvrReg scratchReg: TempReg jumpBackTo: label ].
- 		self ssPop: -2. ].
  	
  	"the jump has not been taken and forwarders have been followed."
  	self SubCq: 1 R: counterReg. "Count untaken"
  	self MoveR: counterReg Aw: counterAddress. "write back"
  	self Jump: (self ensureNonMergeFixupAt: postBranchPC - initialPC).
  	
  	countTripped jmpTarget: self Label.
  	
  	"inlined version of #== ignoring the branchDescriptor if the counter trips to have normal state for the optimizer"
  	^ self genDirectEqualsEqualsArg: unforwardArg rcvr: unforwardRcvr argReg: argReg rcvrReg: rcvrReg!