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Re: [Help-smalltalk] ContextPart>>printOn: prints incorrect line
From: |
Ladislav Marek |
Subject: |
Re: [Help-smalltalk] ContextPart>>printOn: prints incorrect line |
Date: |
Fri, 15 Jul 2011 18:03:33 +0200 |
Patch should be applied in DebugTools package too (just saying to be sure).
diff --git a/packages/debug/DebugTools.st b/packages/debug/DebugTools.st
index cb41c3b..f7f8695 100644
--- a/packages/debug/DebugTools.st
+++ b/packages/debug/DebugTools.st
@@ -48,7 +48,7 @@ pointer bytecodes to line numbers.'>
ifTrue: [MethodLineMapCache := WeakKeyIdentityDictionary new].
lineMap := MethodLineMapCache at: method
ifAbsentPut: [method sourceCodeMap].
- ^lineMap at: aContext ip + 1 ifAbsent: [1]
+ ^lineMap at: aContext ip - 1 ifAbsent: [1]
]
Debugger class >> on: aProcess [
On Fri, Jul 15, 2011 at 10:20, Ladislav Marek <address@hidden> wrote:
> Thanks. Nice explanation.
>
> On Fri, Jul 15, 2011 at 09:52, Paolo Bonzini <address@hidden> wrote:
>> On 07/14/2011 08:25 PM, Ladislav Marek wrote:
>>> I have observe strange behavior of MethodContext>>printOn: and
>>> ContextPart>>currentLineInFile
>>>
>>> Eval [
>>> thisContext print.
>>> 1.
>>> ]
>>>
>>> This code outputs: UndefinedObject>>executeStatements (test.st:3),
>>> line is incorrect, I think it should be 2.
>>>
>>> Eval [
>>> thisContext currentLineInFile printNl.
>>> 1.
>>> ]
>>>
>>> This code outputs: 2, as expected. I look at the
>>> MethodContext>>printOn: method and there is
>>> ContextPart>>currentLineInFile called, so why it outputs different
>>> line number?
>>
>> It's an off-by-one error. This is the compiled bytecode for your first
>> example:
>>
>> 0: source line 2
>> push Global Variable[0] = ContextPart
>> 2: send special message #thisContext
>> 4: send selector 1, 0 args = #printNl
>> 6: source line 2
>> pop stack top
>> 8: push 1
>> return stack top
>>
>> The instruction pointer when sending #printNl is already 6. The call to
>> #currentLineInFile prints erroneously takes the "source line" bytecode at
>> address 6 into account, and prints 2+2-1 = 3.
>>
>> This patch fixes it:
>>
>> diff --git a/kernel/ContextPart.st b/kernel/ContextPart.st
>> index bfcf8d5..dc11dd3 100644
>> --- a/kernel/ContextPart.st
>> +++ b/kernel/ContextPart.st
>> @@ -125,7 +125,7 @@ methods that can be used in inspection or debugging.'>
>> thus making the implementation faster."
>>
>> <category: 'debugging'>
>> - ^self method sourceCodeMap at: self ip + 1 ifAbsent: [1]
>> + ^self method sourceCodeMap at: self ip - 1 ifAbsent: [1]
>> ]
>>
>> debugger [
>>
>> Thanks for reporting it!
>>
>> Paolo
>>
>