[squeak-dev] The Trunk: Tools-eem.633.mcz
commits at source.squeak.org
commits at source.squeak.org
Thu Sep 17 20:18:29 UTC 2015
Eliot Miranda uploaded a new version of Tools to project The Trunk:
http://source.squeak.org/trunk/Tools-eem.633.mcz
==================== Summary ====================
Name: Tools-eem.633
Author: eem
Time: 17 September 2015, 1:18:07.129 pm
UUID: 2a5a8395-fa44-4d48-b6ed-a920c18dbc02
Ancestors: Tools-mt.632
Fix hard VM crash when defining quick methods from MNUs in the debugger. The bug is that the sender context (Message>>sentTo:) is doing a perform:withArguments:[inSuperclass:] but the receiver and arguments have already been removed from the context, so simply backing up to the point of send and proceeding will have disastrous consequences; there must be a receiver and arguments on the stack. So if the arguments are unavailable we simply restart the context inmstead of backing up to the point of send.
To reproduce:
0. make sure e.g. Object>>#zork is unimplemented
1. evaluate "nil zork"
2. in the debugger examine the doesNotUnderstand: context and then hit proceed.
3. click the Create button and define
Object>>#zork
^nil
4. (the debugger sets the active context to Message>>sentTo:) hit proceed
Before the VM woudl crash. Now the debugger sets the pc to the start of the Message>>sentTo: method.
=============== Diff against Tools-mt.632 ===============
Item was changed:
----- Method: Debugger>>contents:notifying: (in category 'accessing') -----
contents: aText notifying: aController
"The retrieved information has changed and its source must now be updated.
In this case, the retrieved information is the method of the selected context."
| result selector classOfMethod category h ctxt newMethod |
contextStackIndex = 0 ifTrue:
[^false].
self selectedContext isExecutingBlock ifTrue:
[h := self selectedContext activeHome.
h ifNil:
[self inform: 'Method for block not found on stack, can''t edit and continue'.
^false].
(self confirm: 'I will have to revert to the method from\which this block originated. Is that OK?' withCRs) ifFalse:
[^false].
self resetContext: h changeContents: false.
"N.B. Only reset the contents if the compilation succeeds. If contents are reset
when compilation fails both compiler error message and modifications are lost."
(result := self contents: aText notifying: aController) ifTrue:
[self contentsChanged].
^result].
classOfMethod := self selectedClass.
category := self selectedMessageCategoryName.
selector := self selectedClass newParser parseSelector: aText.
(selector == self selectedMessageName
or: [(self selectedMessageName beginsWith: 'DoIt')
and: [selector numArgs = self selectedMessageName numArgs]]) ifFalse:
[self inform: 'can''t change selector'.
^false].
selector := classOfMethod
compile: aText
classified: category
notifying: aController.
selector ifNil: [^false]. "compile cancelled"
contents := aText.
newMethod := classOfMethod compiledMethodAt: selector.
newMethod isQuick ifTrue:
+ [self cutBackExecutionToSenderContext].
- [self down.
- self selectedContext jump: (self selectedContext previousPc - self selectedContext pc)].
ctxt := interruptedProcess popTo: self selectedContext.
ctxt == self selectedContext
ifFalse:
[self inform: 'Method saved, but current context unchanged\because of unwind error. Click OK to see error' withCRs]
ifTrue:
[newMethod isQuick ifFalse:
[interruptedProcess
restartTopWith: newMethod;
stepToSendOrReturn].
contextVariablesInspector object: nil].
self resetContext: ctxt.
Smalltalk isMorphic ifTrue:
[World
addAlarm: #changed:
withArguments: #(contentsSelection)
for: self
at: (Time millisecondClockValue + 200)].
^true!
Item was added:
+ ----- Method: Debugger>>cutBackExecutionToSenderContext (in category 'private') -----
+ cutBackExecutionToSenderContext
+ "When accepting a new version of a method which can't be simulated (i.e. a quick method) we
+ must cut back to the sender. But this is non-trivial. If the quick method has been reached via
+ a perform: (as it is when one uses Create toi implement a method from an MNU) then the relevant
+ arguments won't be on the stack and we can't simply proceed without crashing the VM."
+ | oldContext context sel |
+ oldContext := self selectedContext.
+ self down.
+ context := self selectedContext.
+ context jump: (context previousPc - context pc).
+ sel := context selectorToSendOrSelf.
+ sel numArgs = oldContext method numArgs
+ ifTrue:
+ [context push: oldContext receiver.
+ oldContext arguments do:
+ [:arg| context push: arg]]
+ ifFalse:
+ [context privRefresh; stepToSendOrReturn]!
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