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 <[email protected]>:
> 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 <[email protected]>:
>>>
>>>>
>>>> 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
>>
>
>
>
