llvm dev - Jul 2010 - [LLVMdev] simple way to print disassembly of final code from jit?

Hi,

With the new llvm-mc code for disassembling, what is the recommended
way to disassemble the final code produced by a JIT compiler backend?
(Eg. in the toy.cpp example from the tutorial).

I can get the void* for the final code, but I don't know its length -
superficially at least it appears I need to know the length to
disassemble it as a buffer?

Thanks
b.

If you're on a recent flavor of Linux, you may be able to just go into
gdb and type "disas <pointer-to-JITed-code>".  More detail here:
http://llvm.org/docs/DebuggingJITedCode.html

If you still want to do it programmatically, I think you might be
stuck.  IIRC the length known by the JIT memory allocator is an
overestimate (it's rounded up for alignment), so the disassembler will
hit garbage at the end.

Reid

On Tue, Jul 6, 2010 at 3:07 PM, Bill O'Hara <billtohara at gmail.com>
wrote:
> Hi,
>
> With the new llvm-mc code for disassembling, what is the recommended
> way to disassemble the final code produced by a JIT compiler backend?
> (Eg. in the toy.cpp example from the tutorial).
>
> I can get the void* for the final code, but I don't know its length -
> superficially at least it appears I need to know the length to
> disassemble it as a buffer?
>
> Thanks
> b.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Thanks Reid - I'm on Windows. I guess I just assumed I was missing
something obvious in how to hook up the JIT and disassembler! Given
the nice looking disassembly code I found, I thought people would be
doing it all the time :-)

b.



On Tue, Jul 6, 2010 at 8:41 PM, Reid Kleckner <reid.kleckner at gmail.com>
wrote:
> If you're on a recent flavor of Linux, you may be able to just go into
> gdb and type "disas <pointer-to-JITed-code>".  More detail
here:
> http://llvm.org/docs/DebuggingJITedCode.html
>
> If you still want to do it programmatically, I think you might be
> stuck.  IIRC the length known by the JIT memory allocator is an
> overestimate (it's rounded up for alignment), so the disassembler will
> hit garbage at the end.
>
> Reid
>
> On Tue, Jul 6, 2010 at 3:07 PM, Bill O'Hara <billtohara at
gmail.com> wrote:
>> Hi,
>>
>> With the new llvm-mc code for disassembling, what is the recommended
>> way to disassemble the final code produced by a JIT compiler backend?
>> (Eg. in the toy.cpp example from the tutorial).
>>
>> I can get the void* for the final code, but I don't know its length
-
>> superficially at least it appears I need to know the length to
>> disassemble it as a buffer?
>>
>> Thanks
>> b.
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>