[llvm-dev] Interest in integrating a linux perf JITEventListener?

[Philip Reames via llvm-dev]

Having something like this available in tree would definitely be 
useful.  For simplicity, why don't we start with support for the second 
style?  This is the long term useful one and would be a good starting 
point for getting the code in tree.  Can you give a pointer to the patch 
so that I can assess the rough complexity?  If it's simple enough, I'd 
be happy to help get it reviewed and in.  If it's more complicated, I 
probably won't have the time to assist.

Philip

On 12/10/2016 01:27 PM, Andres Freund via llvm-dev wrote:
> Hi,
>
> Under linux a large portion of the profiling these days happens with
> perf, but there's no support for it from LLVM's JITs.
>
> For a while perf could associate address+size to symbols by writing a
> /tmp/perf-$pid.map file:
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/tools/perf/Documentation/jit-interface.txt
>
> A year or so perf also gained the ability to actually see code & debug
> info. It's even being documented now:
> http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?id=b3151ea500655f232255ddcdf2bbcf691cb39646
>
> I've a very preliminary JITEventListener using both of this. Is there
> interest in integrating that into LLVM?  If so, I'll try to follow LLVM
> coding standards and submit it, otherwise I'll keep it somewhere in
> postgres...
>
> If in LLVM, does anybody have preference about how to integrate the two
> methods above?  Because the second method currently (linux limitation)
> only works if the program is profiled from start, I think it makes to
> allow either or both of the methods to be used, which seems to suggest
> an argument to the listener constructor, rather than different wrappers
> for either.  Comments?
>
> Greetings,
>
> Andres Freund
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