[LLVMdev] Old JIT Status (i.e., can we delete it?)

[Kaylor, Andrew]

I don't think that GDB support is even present in the latest version of the old JIT in trunk.  It used to have code to register emitted functions with GDB in a way that let GDB find the function name and EH frame information, but that got taken out back in January (r147615).  As it stands now, I don't think GDB would provide any useful information at all about code emitted by the old JIT.

MCJIT, on ELF platforms at least, registers emitted code with GDB for full source level debugging (when debug info is available).

-Andy

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Solomon Boulos
Sent: Thursday, November 29, 2012 1:01 PM
To: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] Old JIT Status (i.e., can we delete it?)

On Nov 24, 2012, at 3:50 PM, Rafael Espíndola wrote:

> On 24 November 2012 17:36, Chris Lattner <clattner at apple.com> wrote:
>> As others have said, unfortunately it is premature to remove the old jit.  I don't know of anyone using the EH code though... It can almost certainly be removed!
> 
> Cool. I will remove the EH bits by the end of the week if no one complains.

Do you mean you're going to remove EH entirely from the old JIT?  If so, I'll complain ;).

As you pointed out earlier the EH bits are useful for stack frames on x86_64.  In particular, to get useful stack traces from gdb with JIT'ed code those EH frames need to be there.  So even if other people don't currently set JITExceptionHandling for this purpose (I do in a few projects), they probably will when they see crashes.

Solomon


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