llvm dev - Sep 2010 - [LLVMdev] [PATCH] Why isn't __deregister_frame called anywhere in LLVM?

I have two JIT runs in the same process.
First one runs fine. During the second JIT run the exception is thrown, 
and process catches SEGV after it is thrown and before it is caught.

In debugger I see that crash occurs in the function 
'classify_object_over_fdes' called from 'init_object' called
from
'search_object' called from '_Unwind_Find_registered_FDE'. Crash
occurs
on invalid FDE object after several iterations over the valid FDE 
objects. So it looks like an invalid FDE object is attached to the valid 
ones. Also when I split two JIT runs into the separate processes nothing 
crashes.

As I understand, __deregister_frame has to be called during code 
removal. I can only see __register_frame call, and not 
__deregister_frame. Why?

Yuri

Please check in an attached patch.

Synopsys of the change: fixed the cleanup process of exception 
information in JIT. Now JIT deregisters registered by it FDE structures 
allowing consecutive JIT runs to succeed.

Note: tools like lli should delete ExecutionEngine object and not the 
module. Module is deleted by ExecutionEngine. Also I am not sure if this 
is proper for the module to be owned by ExecutionEngine. I think they 
should be independently owned.

Yuri


23.09.2010 01:11, Yuri wrote:
> I have two JIT runs in the same process.
> First one runs fine. During the second JIT run the exception is 
> thrown, and process catches SEGV after it is thrown and before it is 
> caught.
>
> In debugger I see that crash occurs in the function 
> 'classify_object_over_fdes' called from 'init_object'
called from
> 'search_object' called from '_Unwind_Find_registered_FDE'.
Crash
> occurs on invalid FDE object after several iterations over the valid 
> FDE objects. So it looks like an invalid FDE object is attached to the 
> valid ones. Also when I split two JIT runs into the separate processes 
> nothing crashes.
>
> As I understand, __deregister_frame has to be called during code 
> removal. I can only see __register_frame call, and not 
> __deregister_frame. Why?
>
> Yuri
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On 09/24/2010 02:34, Yuri wrote:
> Please check in an attached patch.
>
> Synopsys of the change: fixed the cleanup process of exception 
> information in JIT. Now JIT deregisters registered by it FDE 
> structures allowing consecutive JIT runs to succeed.
>
> Note: tools like lli should delete ExecutionEngine object and not the 
> module. Module is deleted by ExecutionEngine. Also I am not sure if 
> this is proper for the module to be owned by ExecutionEngine. I think 
> they should be independently owned.
>
> Yuri
For some reason I failed to attract any attention or acknowledgement of 
the issue.
So I filed this PR:
http://llvm.org/bugs/show_bug.cgi?id=8285

Yuri