Bug 2854 - Support for moving debugger instruction pointer
Summary: Support for moving debugger instruction pointer
Alias: None
Product: Xamarin Studio
Classification: Desktop
Component: Debugger ()
Version: Trunk
Hardware: PC Windows
: Low enhancement
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2012-01-11 19:24 UTC by Mikayla Hutchinson [MSFT]
Modified: 2014-05-01 15:10 UTC (History)
6 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Mikayla Hutchinson [MSFT] 2012-01-11 19:24:52 UTC
The debugger should support moving the instruction pointer within the current method
Comment 1 Marek Safar 2012-02-06 10:47:50 UTC
I spoke to Zoltan about this on last xummit and he said it should be possible to implement without too much work.
Comment 2 Zoltan Varga 2012-02-06 11:49:38 UTC
Its pretty easy to implement it, its just hard to implement it in a way that doesn't make the app crash. I.e. for this code:

object o = new object ();
o.ToString ()

the JIT might not generate code to null initialize 'o', so if the initialization statement is skipped using this functionality, 'o' might contain garbage leading to a hard crash. Same for an exception handler which expects the exception to be in a stack location saved at the beginning of the code generated for the catch clause. Also, finally statements are implemented in a strange way inside the JIT, so if the user moves the ip inside a finally statement, or out of it, things will crash also.

All of this can probably be fixed, but it would be a lot of work, it would be hard to test, and it would bloat the code generated in debug mode.
Comment 3 Marek Safar 2012-02-06 11:52:40 UTC
Is there any easy way for JIT to detect IP move is unsafe ?
Comment 4 Zoltan Varga 2012-02-06 13:25:26 UTC
Comment 5 Lluis Sanchez 2013-03-05 20:36:14 UTC
What about always initializing the references when running in the debugger?
Comment 6 Jeffrey Stedfast 2014-05-01 15:06:27 UTC
this is implemented now