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digitalmars.D - D at FOSDEM this weekend

reply David Nadlinger <code klickverbot.at> writes:
Hi all,

This year's FOSDEM is taking place Saturday–Sunday in Brussels 
(registration-less open source software event).

Any D heads in the area? Kai Nacke is going to give a talk on PGO 
in LDC in the LLVM dev room [1], and I'll also be around.

  — David


[1] https://fosdem.org/2017/schedule/event/ldc_d_optimization/
Feb 02 2017
next sibling parent Johan Engelen <j j.nl> writes:
On Friday, 3 February 2017 at 06:59:32 UTC, David Nadlinger wrote:

 Hi all,

 This year's FOSDEM is taking place Saturday–Sunday in Brussels 
 (registration-less open source software event).

 Any D heads in the area? Kai Nacke is going to give a talk on 
 PGO in LDC in the LLVM dev room [1], and I'll also be around.


I am not there :/

Have fun!
Feb 04 2017
prev sibling next sibling parent Matthias Klumpp <mak debian.org> writes:
On Friday, 3 February 2017 at 06:59:32 UTC, David Nadlinger wrote:

 Hi all,

 This year's FOSDEM is taking place Saturday–Sunday in Brussels 
 (registration-less open source software event).

 Any D heads in the area? Kai Nacke is going to give a talk on 
 PGO in LDC in the LLVM dev room [1], and I'll also be around.


Too bad that I am not there this year :( (first FOSDEM to miss in 
a while).
Would have been nice to meet!

Enjoy the conference and the Belgian beer!
Feb 04 2017
prev sibling parent reply Johan Engelen <j j.nl> writes:
On Friday, 3 February 2017 at 06:59:32 UTC, David Nadlinger wrote:

 
 Kai Nacke is going to give a talk on PGO in LDC in the LLVM dev 
 room [1], and I'll also be around.


How did it go?

- Johan
Feb 07 2017
parent reply Johan Engelen <j j.nl> writes:
On Tuesday, 7 February 2017 at 16:57:26 UTC, Johan Engelen wrote:

 On Friday, 3 February 2017 at 06:59:32 UTC, David Nadlinger 
 wrote:

 
 Kai Nacke is going to give a talk on PGO in LDC in the LLVM 
 dev room [1], and I'll also be around.


 How did it go?


A recording of Kai's talk is online here: 
https://fosdem.org/2017/schedule/event/ldc_d_optimization/
Feb 07 2017
parent Johan Engelen <j j.nl> writes:
On Tuesday, 7 February 2017 at 17:05:48 UTC, Johan Engelen wrote:

 A recording of Kai's talk is online here: 
 https://fosdem.org/2017/schedule/event/ldc_d_optimization/


Thanks for a nice talk Kai :-)

(please excuse the thread steal)
Some additional answers to the questions raised:

- Using LLVM IR PGO, instead of front-end PGO
Yep... I think frontend PGO is doomed... sad :/ calculating 
statement execution counts from a minimal set of counters was 
nice to work on and interesting code. VCP can be done by the 
backend too (and IIRC _is_ already done) if it has access to 
vtables, etc. To enable backend VCP, I believe clang emits a 
little bit extra (e.g. vtables) to IR where it is not needed 
otherwise. With LTO, the backend already has all the info it 
needs.
Performance-wise, the IR PGO should result in a better profile as 
it can profile optimized code which can be hugely different from 
non-optimized code (inlining!!!).
At the very least, we now have the PGO infrastructure ready and 
can easily provide an IR PGO flag (and should soon!).  When 
Clang/LLVM/LDC versions are in-sync, this should give us 
cross-language LTO+PGO. (^_^)

- Memory alloc call profiling
Something related in progress in LLVM: 
https://reviews.llvm.org/D28965

-Johan
Feb 07 2017