You can use bisection to find out exactly where a speedup came from, basically the same as finding a regression,
https://emscripten.org/docs/contributing/developers_guide.html#bisecting That would give you a single (and hopefully short) list of commits in a single tool (LLVM or Binaryen, but not both). On Tue, Jan 11, 2022 at 10:26 PM Soeren Balko <[email protected]> wrote: > So I just installed the emsdk "top of tree" that comes with LLVM 14. Turns > out that gives me some ~5% performance improvement in some workloads (HEVC > decoding with FFmpeg, which was already hand-optimised to use WebAssembly > SIMD intrinsics). Which is great - if only I knew where that's coming > from... > > Specifically, what is not clear to me is the following: > > (1) Is the new load hoisting optimization automatically performed as part > of LLVM/s LICM pass? That's probably more a question to the LLVM peeps and > I assume that that's a "yes". > (2) Does the "licm" pass in Binaryen's wasm-opt use LLVM's "licm" pass? > (3) Does emcc -O3 already include wasm-opt's "licm" pass? I added -s > BINARYEN_EXTRA_PASSES=licm, but that didn't seem to have an effect. > > I tried directly invoking LLVM's LICM optimisation by passing -mllvm -licm > to emcc, but that makes emcc error out. Interestingly, -mllvm > -enable-loop-versioning-licm does work, but seems to be an entirely > different optimization altogether. > > Sadly, the interplay of emcc, clang, wasm-opt, and LLVM's opt utility > isn't all too clear when it comes to non-standard clang/LLVM features... > > Soeren > > On Wednesday, December 8, 2021 at 3:25:48 AM UTC+10 [email protected] > wrote: > >> Looks like that patch landed Dec 2, so it is already in the latest tip of >> tree build of emscripten, which people can try with >> >> emsdk install tot >> >> >> >> On Tue, Dec 7, 2021 at 5:52 AM 'Thomas Lively' via emscripten-discuss < >> [email protected]> wrote: >> >>> Yes, from the description in that article I would expect that >>> optimization to apply to the Wasm target as well. >>> >>> Thomas >>> >>> On Mon, Dec 6, 2021 at 20:04 Soeren Balko <[email protected]> wrote: >>> >>>> Saw this today: LLVM Clang 14 Lands An "Amazing" Performance >>>> Optimization - Phoronix >>>> <https://www.phoronix.com/scan.php?page=news_item&px=LLVM-Clang-14-Hoist-Load> >>>> >>>> Looks like a fairly substantial gain for some workloads. Will this also >>>> apply to the WebAssembly target? >>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "emscripten-discuss" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/emscripten-discuss/243b4dc8-4305-4af5-9e9d-dff8c0e84c4bn%40googlegroups.com >>>> <https://groups.google.com/d/msgid/emscripten-discuss/243b4dc8-4305-4af5-9e9d-dff8c0e84c4bn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "emscripten-discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> >> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/emscripten-discuss/CAJZD_EXyXLJ6-db5tUrgQzmN5QPsV0S0%3DbPub-TZA1BgrjWnjw%40mail.gmail.com >>> <https://groups.google.com/d/msgid/emscripten-discuss/CAJZD_EXyXLJ6-db5tUrgQzmN5QPsV0S0%3DbPub-TZA1BgrjWnjw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/emscripten-discuss/f9b4c9a7-92aa-4b3c-b092-8c794693b626n%40googlegroups.com > <https://groups.google.com/d/msgid/emscripten-discuss/f9b4c9a7-92aa-4b3c-b092-8c794693b626n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/emscripten-discuss/CAEX4NpQ6yZk3bCDNdjgjaA%2BNV0srD-Ai7cvn7FjPFNPJqVE4Wg%40mail.gmail.com.
