search for: kpszeniczni

On Wed, Oct 2, 2019 at 8:41 PM Maksim Panchenko via llvm-dev < llvm-dev at lists.llvm.org> wrote: > *Pessimization/overhead for stack unwinding used by system-wide profilers > and > for exception handling* > > Larger CFI programs put an extra burden on unwinding at runtime as more CFI > (and thus native) instructions have to be executed. This will cause more > overhead

I'm a bit confused by this subthread -- doesn't BOLT have the exact same CFI bloat issue? From my cursory reading of the propellor doc, the CFI duplication is _necessary_ to represent discontiguous functions, not anything particular to the way Propellor happens to generate those discontiguous functions. And emitting discontiguous functions is a fundamental goal of this, right? On Wed,

We would also like to clarify on the misconceptions around CFI Instructions: There are two things that need to be clarified here: 1) Extra CFI FDE entries for basic blocks does not mean more dynamic instructions are executed. In fact, they do not increase at all. Krys talked about this earlier. 2) We do deduplication of common static CFI instructions in the FDE and move it to the CIE . Hence,

Hi folks, please check out our RFC: Supported Optimizations attribute https://docs.google.com/document/d/1s0n-JVaSNML1Z9SCZVg2bgisxswIJAK2Tp9DahucW10/edit?usp=sharing Pasting it here for the record: RFC: supported_optimizations attribute Piotr Padlewski - piotr.padlewski at gmail.com Krzysztof Pszeniczny - kpszeniczny at google.com December 2018 Introduction Sometimes a possible class of

Some more information about the relaxation pass whose effectiveness and convergence guarantees were listed as a concern: TLDR; Our relaxation pass is similar to what LLVM’s MCAssembler does but with a caveat for efficiency. Our experimental results show it is efficient and convergence is guaranteed. Our relaxation pass is very similar to what MCAssembler does as it needs to solve the same

Hello Maksim, On Wed, Oct 16, 2019 at 3:52 PM Maksim Panchenko <maks at fb.com> wrote: > Hi Sri, > > > > I want to clarify one thing before sending a detailed reply: did you > evaluate > > BOLT on Clang built with basic block sections? > In the makefile you reference, > > there are two versions: a “vanilla” and a default built with function > sections.

Is there large value from deferring the block ordering to link time? That is, does the block layout algorithm need to consider global layout issues when deciding which blocks to put together and which to relegate to the far-away part of the code? Or, could the propellor-optimized compile step instead split each function into only 2 pieces -- one containing an "optimally-ordered" set of

Hello, I wanted to consolidate all the discussions and our final thoughts on the concerns raised. I have attached a document consolidating it. BOLT’s performance gains inspired this work and we believe BOLT is a great piece of engineering. However, there are build environments where scalability is critical and memory limits per process are tight : * Debug Fission,

Hello Maksim, On Fri, Oct 18, 2019 at 10:57 AM Maksim Panchenko <maks at fb.com> wrote: > Cool. The new numbers look good. If you run BOLT with jemalloc library > > preloaded, you will likely get a runtime closer to 1 minute. We’ve noticed > that > > compared to the default malloc, it improves the multithreaded > > performance and brings down memory usage

We are going to be at the llvm-dev meeting the next two days. We will get back to you after that. Sri On Mon, Oct 21, 2019 at 10:07 PM Maksim Panchenko <maks at fb.com> wrote: > Hi Sri, > > > > Thank you for replying to our feedback. 7 out 12 high-level concerns have > been > > answered; 2 of them are fully addressed. The rest are being tracked at the > >