Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
 
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Hi All,
just stumbled across a bytecode compiler bug that's in both the Squeak compiler and the Opal compiler. I'm told by Clément that Opal mimics the bug to avoid crashing legacy code. So there may be places that depend on this bug. It would be good to eliminate the dependencies and the bug. For illustration look at the to:do: loop in the ifNil: arm in Context>>privRefresh: Context>>privRefresh "Reinitialize the receiver so that it is in the state it was at its creation." closureOrNil ifNotNil: [pc := closureOrNil startpc. self stackp: closureOrNil numArgs + closureOrNil numCopiedValues. 1 to: closureOrNil numCopiedValues do: [:i | self tempAt: closureOrNil numArgs + i put: (closureOrNil at: i)]] ifNil: [pc := method initialPC. self stackp: method numTemps. method numArgs+1 to: method numTemps do: [:i | self tempAt: i put: nil]] This should evaluate method numArgs + 1 then method numTemps. If it were written as a non-in-lined (method numArgs+1 to: method numTemps) do: [:i| self tempAt: i put: nil] then the [self tempAt: i put: nil] block would be created next. But the bytecode for the inlined version is self stackp: method numTemps. 63 <70> self 64 <84 40 03> pushRcvr: 3 67 <D6> send: numTemps 68 <E1> send: stackp: 69 <87> pop iLimit := method numTemps 70 <84 40 03> pushRcvr: 3 73 <D6> send: numTemps 74 <69> popIntoTemp: 1 i := method numArgs + 1 75 <84 40 03> pushRcvr: 3 78 <D2> send: numArgs 79 <76> pushConstant: 1 80 <B0> send: + 81 <81 40> storeIntoTemp: 0 (squeak) <69> popIntoTemp: 1 (pharo) 83 <10> pushTemp: 0 84 <11> pushTemp: 1 85 <B4> send: <= 86 <AC 0B> jumpFalse: 99 There is a second bug in the Squeak bytecode; storeIntoTemp: is used to load i whereas it should be popIntoTemp:. It was this second bug that alerted me to the order-of-evaluation bug. _,,,^..^,,,_ best, Eliot |
Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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On Thu, Apr 20, 2017 at 4:41 PM, Eliot Miranda <[hidden email]> wrote:
The second bug (Squeak's use of storeIntoTemp:) is actually only a poor implementation of the value/effect distinction through the inlined ifNil:ifNotNil:. Because ifNil:ifNotNil: has a value (albeit one that is discarded) the Squeak compiler generates a storeIntoTemp: to p[reserve the value of the to:do: lop, which is the initial index. So the bug is not within the generation of the to:do: (the only bug there being the order-of-evaluation one). The bug is actually outside; the loop should be being generated for effect but is being evaluated for value. On the order of evaluation bug, does anyone have any memory of which methods depended on this bug?
_,,,^..^,,,_ best, Eliot |
Re: [Vm-dev] Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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John Brant discovered this bug recenlty: (see bottom of his post) http://forum.world.st/collection-flatCollect-something-VS-collection-collect-something-flattened-tp4929422p4929479.html 2017-04-21 1:56 GMT+02:00 Eliot Miranda <[hidden email]>:
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Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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In reply to this post by Eliot Miranda-2
On Fri, Apr 21, 2017 at 1:56 AM, Eliot Miranda <[hidden email]> wrote:
No idea ... - Bert - |
Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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I see more than 1000 senders but most of them are in the style 1 to: ... If any of receiver or 1st arg is a LiteralNode, no need to analyze, so it should be possible to write a small analyzer to select non trivial cases and review manually. Something like:SystemNavigation default browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) select: [:e | | ast found | ast := e actualClass newParser parse: e sourceCode class: e actualClass. found := nil. ast accept: (ParseNodeEnumerator ofBlock: [:node | ((node isKindOf: MessageNode) and: [node selector key = #to:do: and: [node receiver isLiteralNode not and: [node arguments first isLiteralNode not]]]) ifTrue: [found := node]]). found notNil]) name: 'complex senders of to:do:' autoSelect: true. Above script did not find any complex senders though I see some, so I must have screwed something, but you get the idea. 2017-04-21 16:08 GMT+02:00 Bert Freudenberg <[hidden email]>:
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Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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2017-04-21 23:05 GMT+02:00 Nicolas Cellier <[hidden email]>:
Ah, my script failed because to:do: is transformed at this stage (disguised in #to:by:do:)... SystemNavigation default browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) select: [:e | | ast found | ast := e actualClass newParser parse: e sourceCode class: e actualClass. found := nil. ast accept: (ParseNodeEnumerator ofBlock: [:node | ((node isKindOf: MessageNode) and: [(node selector key = #to:do: or: [node selector key = #to:by:do: ]) and: [node receiver isLiteralNode not and: [node arguments first isLiteralNode not]]]) ifTrue: [found := node]]). found notNil]) name: 'complex senders of to:do:' autoSelect: #to:do: But I can't test other trivial cases when node arguments first isVariableNode, because it allways is after transform. It would be necessary to disable transform during analysis...
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Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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This seems to work:
methods := (SystemNavigation default allCallsOn: #to:do:) asSet. methods addAll: (SystemNavigation default allCallsOn: #to:by:do:). methods := CurrentReadOnlySourceFiles cacheDuring: [ methods select: [ :methodReference | | ast found | ast := methodReference actualClass newParser parse: methodReference sourceCode class: methodReference actualClass. found := nil. ast accept: (ParseNodeEnumerator ofBlock: [ :node | (node isMessage and: [ (#(to:do: to:by:do:) includes: node selector key) and: [ node receiver isLiteralNode not and: [ node receiver isVariableNode not and: [ node arguments first isLiteralNode not and: [ node arguments first isVariableNode not ] ] ] ] ]) ifTrue: [ found := node ] ]). found notNil ] ]. SystemNavigation default browseMessageList: methods sorted name: 'complex senders of to:do:' autoSelect: 'to:'. Levente On Sat, 22 Apr 2017, Nicolas Cellier wrote: > > > 2017-04-21 23:05 GMT+02:00 Nicolas Cellier <[hidden email]>: > I see more than 1000 senders but most of them are in the style 1 to: ... > If any of receiver or 1st arg is a LiteralNode, no need to analyze, so it should be possible to write a small analyzer to select non trivial cases and review manually. Something like: > > SystemNavigation default > browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) select: [:e | > | ast found | > ast := e actualClass newParser parse: e sourceCode class: e actualClass. > found := nil. > ast accept: (ParseNodeEnumerator > ofBlock: [:node | ((node isKindOf: MessageNode) > and: [node selector key = #to:do: > and: [node receiver isLiteralNode not > and: [node arguments first isLiteralNode not]]]) > ifTrue: [found := node]]). > found notNil]) > name: 'complex senders of to:do:' > autoSelect: true. > > Above script did not find any complex senders though I see some, so I must have screwed something, but you get the idea. > > Then there is the case of to:by:do: to analyze too. > > > Ah, my script failed because to:do: is transformed at this stage (disguised in #to:by:do:)... > > SystemNavigation default > browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) select: [:e | > | ast found | > ast := e actualClass newParser parse: e sourceCode class: e actualClass. > found := nil. > ast accept: (ParseNodeEnumerator > ofBlock: [:node | ((node isKindOf: MessageNode) > and: [(node selector key = #to:do: or: [node selector key = #to:by:do: ]) > and: [node receiver isLiteralNode not > and: [node arguments first isLiteralNode not]]]) > ifTrue: [found := node]]). > found notNil]) > name: 'complex senders of to:do:' > autoSelect: #to:do: > > But I can't test other trivial cases when node arguments first isVariableNode, because it allways is after transform. > It would be necessary to disable transform during analysis... > > > 2017-04-21 16:08 GMT+02:00 Bert Freudenberg <[hidden email]>: > On Fri, Apr 21, 2017 at 1:56 AM, Eliot Miranda <[hidden email]> wrote: > On the order of evaluation bug, does anyone have any memory of which methods depended on this bug? > > > No idea ... > > - Bert - > > > > > > > |
Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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Actually it's possible to have one variable and one non-literal
non-variable node where the latter changes the value of the former, so the condition should be: (node isMessage and: [ (#(to:do: to:by:do:) includes: node selector key) and: [ node receiver isLiteralNode not and: [ node arguments first isLiteralNode not and: [ node receiver isVariableNode not or: [ node arguments first isVariableNode not ] ] ] ] ]) Levente On Sat, 22 Apr 2017, Levente Uzonyi wrote: > This seems to work: > > methods := (SystemNavigation default allCallsOn: #to:do:) asSet. > methods addAll: (SystemNavigation default allCallsOn: #to:by:do:). > methods := CurrentReadOnlySourceFiles cacheDuring: [ > methods select: [ :methodReference | > | ast found | > ast := methodReference actualClass newParser parse: > methodReference sourceCode class: methodReference actualClass. > found := nil. > ast accept: (ParseNodeEnumerator ofBlock: [ :node | > (node isMessage > and: [ (#(to:do: to:by:do:) includes: node > selector key) > and: [ node receiver isLiteralNode not > and: [ node receiver isVariableNode not > and: [ node arguments first isLiteralNode not > and: [ node arguments first isVariableNode > not ] ] ] ] ]) > ifTrue: [ found := node ] ]). > found notNil ] ]. > SystemNavigation default > browseMessageList: methods sorted > name: 'complex senders of to:do:' > autoSelect: 'to:'. > > Levente > > On Sat, 22 Apr 2017, Nicolas Cellier wrote: > >> >> >> 2017-04-21 23:05 GMT+02:00 Nicolas Cellier >> <[hidden email]>: >> I see more than 1000 senders but most of them are in the style 1 to: >> ... >> If any of receiver or 1st arg is a LiteralNode, no need to analyze, so it >> should be possible to write a small analyzer to select non trivial cases >> and review manually. Something like: >> >> SystemNavigation default >> browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) >> select: [:e | >> | ast found | >> ast := e actualClass newParser parse: e sourceCode class: e >> actualClass. >> found := nil. >> ast accept: (ParseNodeEnumerator >> ofBlock: [:node | ((node isKindOf: MessageNode) >> and: [node selector key = #to:do: >> and: [node receiver isLiteralNode not >> and: [node arguments first isLiteralNode not]]]) >> ifTrue: [found := node]]). >> found notNil]) >> name: 'complex senders of to:do:' >> autoSelect: true. >> >> Above script did not find any complex senders though I see some, so I must >> have screwed something, but you get the idea. >> >> Then there is the case of to:by:do: to analyze too. >> >> >> Ah, my script failed because to:do: is transformed at this stage (disguised >> in #to:by:do:)... >> >> SystemNavigation default >> browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) >> select: [:e | >> | ast found | >> ast := e actualClass newParser parse: e sourceCode class: e >> actualClass. >> found := nil. >> ast accept: (ParseNodeEnumerator >> ofBlock: [:node | ((node isKindOf: MessageNode) >> and: [(node selector key = #to:do: or: [node selector >> key = #to:by:do: ]) >> and: [node receiver isLiteralNode not >> and: [node arguments first isLiteralNode not]]]) >> ifTrue: [found := node]]). >> found notNil]) >> name: 'complex senders of to:do:' >> autoSelect: #to:do: >> >> But I can't test other trivial cases when node arguments first >> isVariableNode, because it allways is after transform. >> It would be necessary to disable transform during analysis... >> >> >> 2017-04-21 16:08 GMT+02:00 Bert Freudenberg <[hidden email]>: >> On Fri, Apr 21, 2017 at 1:56 AM, Eliot Miranda >> <[hidden email]> wrote: >> On the order of evaluation bug, does anyone have any memory of >> which methods depended on this bug? >> >> >> No idea ... >> >> - Bert - >> >> >> >> >> >> > |
Re: Order of evaluation bug with in lined to:do: in both Opal and Squeak compilers.
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I went through all those senders in my Trunk image and found that they
won't be affected by the change of evaluation order. Levente On Sat, 22 Apr 2017, Levente Uzonyi wrote: > Actually it's possible to have one variable and one non-literal non-variable > node where the latter changes the value of the former, so the condition > should be: > > (node isMessage > and: [ (#(to:do: to:by:do:) includes: node > selector key) > and: [ node receiver isLiteralNode not > and: [ node arguments first isLiteralNode not > and: [ node receiver isVariableNode not > or: [ node arguments first > isVariableNode not ] ] ] ] ]) > > Levente > > On Sat, 22 Apr 2017, Levente Uzonyi wrote: > >> This seems to work: >> >> methods := (SystemNavigation default allCallsOn: #to:do:) asSet. >> methods addAll: (SystemNavigation default allCallsOn: #to:by:do:). >> methods := CurrentReadOnlySourceFiles cacheDuring: [ >> methods select: [ :methodReference | >> | ast found | >> ast := methodReference actualClass newParser parse: >> methodReference sourceCode class: methodReference actualClass. >> found := nil. >> ast accept: (ParseNodeEnumerator ofBlock: [ :node | >> (node isMessage >> and: [ (#(to:do: to:by:do:) includes: node >> selector key) >> and: [ node receiver isLiteralNode not >> and: [ node receiver isVariableNode not >> and: [ node arguments first isLiteralNode not >> and: [ node arguments first isVariableNode >> not ] ] ] ] ]) >> ifTrue: [ found := node ] ]). >> found notNil ] ]. >> SystemNavigation default >> browseMessageList: methods sorted >> name: 'complex senders of to:do:' >> autoSelect: 'to:'. >> >> Levente >> >> On Sat, 22 Apr 2017, Nicolas Cellier wrote: >> >>> >>> >>> 2017-04-21 23:05 GMT+02:00 Nicolas Cellier >>> <[hidden email]>: >>> I see more than 1000 senders but most of them are in the style 1 to: >>> ... >>> If any of receiver or 1st arg is a LiteralNode, no need to analyze, so it >>> should be possible to write a small analyzer to select non trivial cases >>> and review manually. Something like: >>> >>> SystemNavigation default >>> browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) >>> select: [:e | >>> | ast found | >>> ast := e actualClass newParser parse: e sourceCode class: e >>> actualClass. >>> found := nil. >>> ast accept: (ParseNodeEnumerator >>> ofBlock: [:node | ((node isKindOf: MessageNode) >>> and: [node selector key = #to:do: >>> and: [node receiver isLiteralNode not >>> and: [node arguments first isLiteralNode not]]]) >>> ifTrue: [found := node]]). >>> found notNil]) >>> name: 'complex senders of to:do:' >>> autoSelect: true. >>> >>> Above script did not find any complex senders though I see some, so I must >>> have screwed something, but you get the idea. >>> >>> Then there is the case of to:by:do: to analyze too. >>> >>> >>> Ah, my script failed because to:do: is transformed at this stage >>> (disguised in #to:by:do:)... >>> >>> SystemNavigation default >>> browseMessageList: ((SystemNavigation default allCallsOn: #to:do:) >>> select: [:e | >>> | ast found | >>> ast := e actualClass newParser parse: e sourceCode class: e >>> actualClass. >>> found := nil. >>> ast accept: (ParseNodeEnumerator >>> ofBlock: [:node | ((node isKindOf: MessageNode) >>> and: [(node selector key = #to:do: or: [node selector >>> key = #to:by:do: ]) >>> and: [node receiver isLiteralNode not >>> and: [node arguments first isLiteralNode not]]]) >>> ifTrue: [found := node]]). >>> found notNil]) >>> name: 'complex senders of to:do:' >>> autoSelect: #to:do: >>> >>> But I can't test other trivial cases when node arguments first >>> isVariableNode, because it allways is after transform. >>> It would be necessary to disable transform during analysis... >>> >>> >>> 2017-04-21 16:08 GMT+02:00 Bert Freudenberg <[hidden email]>: >>> On Fri, Apr 21, 2017 at 1:56 AM, Eliot Miranda >>> <[hidden email]> wrote: >>> On the order of evaluation bug, does anyone have any memory of >>> which methods depended on this bug? >>> >>> >>> No idea ... >>> >>> - Bert - >>> >>> >>> >>> >>> >>> > |
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