llvm dev - Jul 2017 - How to add custom instrumentation?

Hi everyone,

I run some functions using ORC JIT, now I need to add custom instrumentation.
I want to add two callbacks to each function: ‘enterFunction' at the
beginning and ‘leaveFunction' at the end.
Intuition says that I could ‘just' insert CallInst's to the first and
the last basic blocks in the function.

Am I correct? Are there any other/better way to do this? Is there anything
special I need to be aware of?

Thank you.
--
AlexDenisov
Software Engineer, https://lowlevelbits.org

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The '-finstrument-functions' option may already be sufficient for your
needs.

When selected this inserts the following two calls on entry-to and exit-from a
function:

  __cyg_profile_func_enter(void* this_fn, void* call_site)
  __cyg_profile_func_exit(void* this_fn, void* call_site)

You can then provide a custom implementation of these calls to perform the
analysis tasks that you require.

The two parameters are the address of the function into which the
instrumentation is inserted, and the address of the call site to the
instrumentation function.

There is an "Execution Trace" implementation of these instrumentation
hooks on GitHub called 'eTrace' that may guide you, though I can't
recall the link.

All the best,

  MartinO

-----Original Message-----
From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Alex
Denisov via llvm-dev
Sent: Thursday, July 13, 2017 8:57 AM
To: llvm-dev <llvm-dev at lists.llvm.org>
Subject: [llvm-dev] How to add custom instrumentation?

Hi everyone,

I run some functions using ORC JIT, now I need to add custom instrumentation.
I want to add two callbacks to each function: ‘enterFunction' at the
beginning and ‘leaveFunction' at the end.
Intuition says that I could ‘just' insert CallInst's to the first and
the last basic blocks in the function.

Am I correct? Are there any other/better way to do this? Is there anything
special I need to be aware of?

Thank you.
--
AlexDenisov
Software Engineer, https://lowlevelbits.org

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Thanks for the hint, I didn’t know about this option. That’s a great reference!

However, I am trying to be a compiler/language agnostic.
Also (for whatever reasons) I need a numeric ID of a function rather then its
address.
So the question is still opened.

May I assume that the following always holds:
The first basic block in a function is an entry point and the last basic block
in a function is an exit point
?
> On 13. Jul 2017, at 10:57, ORiordan, Martin <martin.oriordan at
intel.com> wrote:
> 
> The '-finstrument-functions' option may already be sufficient for
your needs.
> 
> When selected this inserts the following two calls on entry-to and
exit-from a function:
> 
>  __cyg_profile_func_enter(void* this_fn, void* call_site)
>  __cyg_profile_func_exit(void* this_fn, void* call_site)
> 
> You can then provide a custom implementation of these calls to perform the
analysis tasks that you require.
> 
> The two parameters are the address of the function into which the
instrumentation is inserted, and the address of the call site to the
instrumentation function.
> 
> There is an "Execution Trace" implementation of these
instrumentation hooks on GitHub called 'eTrace' that may guide you,
though I can't recall the link.
> 
> All the best,
> 
>  MartinO
> 
> -----Original Message-----
> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
Alex Denisov via llvm-dev
> Sent: Thursday, July 13, 2017 8:57 AM
> To: llvm-dev <llvm-dev at lists.llvm.org>
> Subject: [llvm-dev] How to add custom instrumentation?
> 
> Hi everyone,
> 
> I run some functions using ORC JIT, now I need to add custom
instrumentation.
> I want to add two callbacks to each function: ‘enterFunction' at the
beginning and ‘leaveFunction' at the end.
> Intuition says that I could ‘just' insert CallInst's to the first
and the last basic blocks in the function.
> 
> Am I correct? Are there any other/better way to do this? Is there anything
special I need to be aware of?
> 
> Thank you.
> --
> AlexDenisov
> Software Engineer, https://lowlevelbits.org
> 
> --------------------------------------------------------------
> Intel Research and Development Ireland Limited
> Registered in Ireland
> Registered Office: Collinstown Industrial Park, Leixlip, County Kildare
> Registered Number: 308263
> 
> 
> This e-mail and any attachments may contain confidential material for the
sole
> use of the intended recipient(s). Any review or distribution by others is
> strictly prohibited. If you are not the intended recipient, please contact
the
> sender and delete all copies.
--
AlexDenisov
Software Engineer, https://lowlevelbits.org

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