I will try it in my image, thanks! I got a little further with Andres. The thing about the loop example is that the block is copying values outside its scope. You get get extra bytecodes at the start of the method (Array new: ...) and extra bytecodes in the loop to do the copying of values. We suspect that the mapping is getting confused by this. This is because the encoder hands out the ranges of the original method correctly, but the mapping has to align the pc to ignore these bytecodes because they are not in the debugger source. Anyway that was our impression. I agree we need Eliot to review. cheers, Mike On Thu, Aug 25, 2011 at 9:43 PM, Stéphane Ducasse <stephane.ducasse@inria.fr
wrote:
thanks a lot nicolas It seems to work on my image too. I adding it to the bug entry. What is great is that tomorrow I will be able to follow your path in the train.
Stef On Aug 25, 2011, at 9:12 PM, Nicolas Cellier wrote:
And by changing last line of this piece of code in #transformToDo: test := MessageNode new receiver: blockVar selector: (increment key > 0 ifTrue: [#<=] ifFalse: [#>=]) arguments: (Array with: limit) precedence: precedence from: encoder sourceRange: (myRange first to: blockRange last). I get a "correct" selection...
Nicolas
2011/8/25 Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com>:
A few more notes:
- Encoder>>rawSourceRanges answer a mapping AST Node -> sourceRange Gnerally, I would expect sourceRange to be an Interval, but this has to be confirmed. Theses ranges are constructed at source code Parse time (see senders of #noteSourceRange:forNode:) - The program counters are assigned to AST nodes at byte code #generate time - for inlined macros, like #to:do: in our case, this pc is after the initialize and test statements.
in CompiledMethod>>#rawSourceRangesAndMethodDo: I just evaluated this:
methNode encoder rawSourceRanges collect: [:ival | sourceText copyFrom: ival first to: ival last]
And what I see is that the original to:do: message (before macros inlining) has the right range {1 to: 5 do: [:index | temp := index. collection add: [temp]]}->a Text for 'to: 5 do: [ :index | temp := index. collection add: [ temp ] ]' This node is the original #to:do: and has pc=42
There is also {a LeafNode}->a Text for '[ :index | temp := index. collection add: [ temp ] ]' which has a nil pc so it won't be taken into account in the source map.
But one of the messages produced by the inlining has this curious range: {index <= 5}->a Text for 'to: 5 do: [ :index | temp := index. c' This node has pc = 40, so it will be selected before the correct one above has a chance to be. {index <= 5} is the test statement produced by inlining, and this seems to be the incorrect highlighting we see. Thus we know we have to concentrate on macro inlining. This happens in MessageNode>>transformToDo: We'll see this.
In the interim, I played with eliminating the nodes having unitilialized pc Let us try to evaluate this snippet in debugger's inspector: (methNode encoder rawSourceRanges keys select: [:e | e pc > 0]) collect: [:node | | ival | ival := methNode encoder rawSourceRanges at: node. node -> (sourceText copyFrom: ival first to: ival last)]
Oh god, a bug in the debugger: DoItIn: homeContext ^ ((homeContext namedTempAt: 2) encoder rawSourceRanges keys select: [:e | e pc > 0]) collect: [:node | | ival | ival := (node namedTempAt: 2) encoder rawSourceRanges at: node. node -> (sourceText copyFrom: ival first to: ival last)] (node namedTempAt: 2) does not mean a thing... A confusion occurred between the homeContext (DoItIn: method argument) and node (the block argument) Nevermind... forget about it.
Now let's just concentrate on MessageNode>>transformToDo: We see this code: test := MessageNode new receiver: blockVar selector: (increment key > 0 ifTrue: [#<=] ifFalse: [#>=]) arguments: (Array with: limit) precedence: precedence from: encoder sourceRange: (myRange first to: blockRange first).
So the intention seems to select 'to: 5 do: '
But we see this: BlockNode>>noteSourceRangeStart:end:encoder: "Note two source ranges for this node. One is for the debugger and is of the last expression, the result of the block. One is for source analysis and is for the entire block." encoder noteSourceRange: (start to: end) forNode: self closureCreationNode. startOfLastStatement ifNil: [encoder noteSourceRange: (start to: end) forNode: self] ifNotNil: [encoder noteSourceRange: (startOfLastStatement to: end - 1) forNode: self]
So it seems intentional to select only the last instruction of the block for the debugger. We'd better not change this without prior asking Eliot. But obviously, this is not what is expected by the #transformToDo:
Nicolas
2011/8/25 Stéphane Ducasse <stephane.ducasse@inria.fr>:
tx nicolas this is a cool way to help :)
Stef
On Aug 24, 2011, at 9:54 PM, Nicolas Cellier wrote:
So the entries of interest for highlighting are
Debugger>>contentsSelection Debugger>>pcRange CompiledMethod>>debuggerMap DebuggerMethodMap class>>forMethod: DebuggerMethodMap>>rangeForPC:contextIsActiveContext:
Then you see the DebuggerMethodMap>>forMethod:methodNode: takes both a CompiledMethod and its #methodNode. CompiledMethod>>methodNode invokes the Parser to get the AbstractSyntaxTree from method source, and if it ever fails ends up by trying to decompile the byteCodes.
This is the easy part. Now we to deal with #abstractPCForConcretePC: and #abstractSourceMap.
By reading CompiledMethod>>abstractPCForConcretePC: you should quickly understand that a concrete PC is a byte offset of current byteCode (the offsets displayed in the byteCode view) while the abstractPC is just the rank of current byteCode in the list of byteCodes instructions composing the CompiledMethod. This is just because "byteCodes" may spread on several bytes beside their name... This will use InstructionStream and InstructionClient which are just an iterator and a sort of visitor on byteCode instructions. So this is not really interesting.
The more interesting part is #abstractSourceMap There is a first step to obtain CompiledMethod>>rawSourceRangesAndMethodDo: This is the most important part. The rest is again a mapping from concretePC (instruction byte offset) to abstractPC (instruction rank). And some build of a dictionary mapping instruction rank (abstractPC) -> selected range.
Note that the last trick seems to use a regenerated CompiledMethod (theMethodToScan) rather than the original CompiledMethod. There is no assertion whether these two are equivalent or not. A priori, they should, unless the Compiler changed since last compilation or if its behaviour is affected by some Preferences... Would we introduce some customizable Compiler optimizations that this could become a problem (We would then add to map decompiled AST to source code AST, probably with guesses, unless the CompiledMethod would contain debugger friendly hints...) We will consider this is not a problem by now.
So let's now concentrate on rawSourceRangesAndMethodDo: The nice thing is that you now can just debug this
(ClosureTests>>#testToDoOutsideTemp) methodNode rawSourceRangesAndMethodDo: [:rs :mth | ]
and see how it goes in Squeak. I did not look in Pharo yet, but I would be amazed to see it much different. It's now late, and my spare time is off, but you have clues to get more insights. I wish you good debugging, and come back to me if it ever goes in deeper complications.
Cheers
Nicolas
2011/8/24 Michael Roberts <mike@mjr104.co.uk>:
Ok I'm curious to know then.
Here is a little trace from this example method:
toDoOutsideTemp | temp collection | collection := OrderedCollection new. 1 to: 5 do: [ :index | temp := index. collection add: [ temp ] ]
Trace is start,stop position of the highlight for each 'step over'.
Whilst the numbers are hard to visualise, below you can see how they slightly diverge. Left Pharo Right Squeak
50, 73 71, 73 diff 71, 73 71, 73 50, 73 50, 73 108, 115 79, 121 diff 79, 121 79, 121 108, 115 108, 115 132, 144 132, 144 147, 146 146, 146 (diff negative size means no highlight) 146, 146 146, 146 79, 121 79, 121 108, 115 108, 115 132, 144 132, 144 147, 146 146, 146 146, 146 146, 146 79, 121 79, 121 108, 115 108, 115 132, 144 132, 144 147, 146 146, 146 146, 146 146, 146 79, 121 79, 121 108, 115 108, 115 etc... For example the first difference is because Pharo shows the whole
assignment
of the first line as the first send, even though it is not. The second difference is that Pharo shows the assignment inside the block as the first highlight of the loop even though the to:do should be highlighted....but both Pharo & Squeak get the to:do: wrong when they choose to show it. hope you get the idea... Mike