similar to: Current PGO status

Hello David, thanks for detailed response! Do you have any tests that you use to measure the PGO effectiveness? I have tested clang version 6.0 with the same sample that Jie Chen used in 2016 and actually both frontend-based PGO and IR-based make code run slower, see the average time: clang++ -O3: 3.15 sec  clang++ -O3 and -fprofile-instr-use: 3.160 sec clang++ -O3 and -fprofile-use: 3.180 sec

David, could you please clarify on which code did you gain 10% improvement? I have run numerous tests with and w/o this option and it looks like it has no effect on performance (I am talking of the old 2016 sample to be concrete). Maybe we could investigate it together? Just tell me where to start? On 02/07/2018 02:11 AM, Xinliang David Li wrote: > Victor, thanks for the experiment. > >

On Sun, Feb 4, 2018 at 9:59 PM, Victor Leschuk <vleschuk at accesssoftek.com> wrote: > Hello David! > > I have recently started acquaintance with PGO in LLVM/clang and found > your e-mail thread: > http://lists.llvm.org/pipermail/llvm-dev/2016-May/099395.html . Here you > posted a nice list of optimizations that use profiling and of those > which could be using but

Victor, thanks for the experiment. My suspicion is it is due to the remaining issues with block layout -- especially with loop rotation (with PGO). Another problem is that tail dup is not happening after loop rotation which can limit the effectiveness of loop rotation. I tried the internal option -mllvm -force-precise-rotation-cost and there is about 10% speedup with -fprofile-use. This option

Victor, please file a bug tracking the issue. We can put relevant information there including test cases used in the experiment etc. thanks, David On Wed, Feb 7, 2018 at 2:15 PM, Victor Leschuk <vleschuk at accesssoftek.com> wrote: > David, could you please clarify on which code did you gain 10% > improvement? I have run numerous tests with and w/o this option and it > looks

Hello David and all involved =) On 02/05/2018 09:38 AM, Xinliang David Li wrote: > ThinLTO also works well with PGO. Could you please let me know if there are any problems which prevent using PGO with FullLTO? Thanks in advance! -- Best Regards, Victor Leschuk | Software Engineer | Access Softek

Thanks for testing out LLVM PGO and evaluated the performance. We are currently still more focused on infrastructure improvement which is the foundation for performance improvement. We are making great progress in this direction, but there are still some key missing pieces such as profile data in inliner etc. We are working on that. Once those are done, more focus will be on making more passes

Hello all, clang-related PGO documentation recommends using PGO with -O2 (for example: https://clang.llvm.org/docs/UsersManual.html#profile-guided-optimization). The question is: is there any reason why exactly -O2 is used in examples? Are there any factors which can cause problems when using PGO with -O3? Thanks in advance for your advice! -- Best Regards, Victor Leschuk | Software Engineer

Maybe we should update the documentation to state this directly? Currently its a little bit confusing. On 01/29/2018 05:51 AM, Xinliang David Li wrote: > It means using PGO with -O2 and above (including -O3). > > David > > On Sun, Jan 28, 2018 at 6:48 PM, Victor Leschuk via llvm-dev > <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: > >

It means using PGO with -O2 and above (including -O3). David On Sun, Jan 28, 2018 at 6:48 PM, Victor Leschuk via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hello all, > > clang-related PGO documentation recommends using PGO with -O2 (for > example: > https://clang.llvm.org/docs/UsersManual.html#profile-guided-optimization). > The question is: is there any reason why

Hi Victor, The work Wolfgang is doing should get us to the "minimum syntactically correct DWARF v5" stage, which we really wanted to have for LLVM 7.0. That is, once we have .debug_rnglists and .debug_loclists done, you can ask for DWARF 5 and get something that conforms to the spec. However, it won't conform if you ask for type units (I'm working on that) or split DWARF. If

Hello Wolfgang and team, I see that you are working on support of .debug_rnglists, I am interested in the feature too, could you please point me out what else left to be done so that I could help you? -- Best Regards, Victor Leschuk | Software Engineer | Access Softek

Hello, I hope I will have time to help you with that. I discussed dwarfv5 .debug_names implementation with involved party from RH. Anyway even if can't help much could you keep me in the loop please? On 01/17/2018 07:13 PM, Pavel Labath via llvm-dev wrote: > Hello all, > > In <https://reviews.llvm.org/D41986#977215> it was brought up that > there are at least two parties

Hi, I have a question regarding PGO. I collected profile data with the instrumentation build (-fprofile-instr-generate) and provided for PGO optimization in the second build (with -fprofile-instr-use=xxx.profdata). This works fine. Then I tried to provide the profile data to opt using the option -pgo-instr-use, but this causes an error with the message: "Not an IR level instrumentation

Hi, all Recently I'm trying to use LLVM PGO and autoFDO. However I have some problems in the process. LLVM source code is updated on April 9th. Operating system is SUSE x86_64 1. Problems in instrumentation based PGO: clang -O2 -fprofile-instr-generate test.c -o a.out ./a.out (then default.profraw is generated) clang -O2 -fprofile-instr-use=default.profraw test.c -o a.out

Hello everyone, LLVM buildmasters (both main and staging) will be restarted in 2 hours (~3:00 AM PDT). -- Best Regards, Victor Leschuk | Software Engineer |Access Softek

Hello, When I try to use -fprofile-instr-generate with clang (which is built from source) I am getting following error : ld: file not found: /Users/Mr.Pandya/My_Stuff/Active/llvm/build/bin/../lib/clang/3.9.0/lib/darwin/libclang_rt.profile_osx.a clang-3.9: error: linker command failed with exit code 1 (use -v to see invocation) I am not building compiler RT with LLVM. Am I missing any thing

Hi everyone, As part of my work for Mozilla's Low Level Tools team I've implemented PGO in the Rust compiler. The feature is available since Rust 1.37 [1]. However, so far we have not seen any actual performance gains from enabling PGO for Rust code. Performance even seems to drop 1-3% with PGO enabled. I wonder why that is and I'm hoping that someone here might have experience

Hello - I'm an Engineer in Microsoft Office after looking into possible advantages of using PGO for our Android Applications. We at Microsoft have deep experience with Visual C++'s Profile Guided Optimization<https://msdn.microsoft.com/en-us/library/e7k32f4k.aspx> and often see 10% or more reduction in the size of application code loaded after using PGO for key scenarios (e.g.

Hello, I'm working on Android kernel profile-guided optimization to figure out whether pgo can improve the performance of Android kernel. I have tried to added '-fprofile-generate' option to build Android kernel(msm-4.19). But error occurs during building: "undefined reference to '__llvm_profile_instrument_target'". I have tried to add