Hi Dylan, Here's what these errors mean in more detail.
wasm-ld: error: 'atomics' feature is used by d1_lib.o, so --shared-memory must be used This one means that `dl_lib.o` was compiled with -pthread already (-pthread enables the 'atomics' feature), so its atomic operations have been lowered to real atomic WebAssembly instructions. However, because you're not passing -pthread at link time, the linker tries to produce a module with an unshared memory, which would make those atomic instructions invalid. wasm-ld: error: Target feature 'atomics' used in d1_lib.o is disallowed by ConcurrentScheduler.cpp.o. Use --no-check-features to suppress. This line tells us that ConcurrentScheduler.cpp.o was compiled without -pthread, which means its atomic operations were lowered to non-atomic WebAssembly instruction because the atomics feature was not enabled. That means that ConcurrentScheduler.cpp.o is not safe to link with dl_lib.o because the resulting program would not be thread-safe, even if the program was thread-safe at the source level. When using the LLVM backend, the wasm-ld linker helpfully recognizes this error and does not let you link an unsafe program. Fastcomp would just silently link your program into a thread-unsafe binary. As Mehdi said, you can either make sure to use -pthread when building all your objects and libraries and at link time to get a properly thread-safe binary out, or alternatively you can make sure not to pass -pthread for any of the objects and libraries to get a single-threaded version of the binary that will run on any engine. Let me know if I you want more detail on anything :) On Wed, Jul 24, 2019 at 2:41 PM Dylan Staley <[email protected]> wrote: > By adding the pthreads flag, will that change the behavior of the > generated WASM module? I know that browsers like Chrome have experimental > support for webassembly threads, but I'm aiming for a WASM module that > works in older versions of Chrome as well. > > On Wed, Jul 24, 2019, 2:34 PM Mehdi Sabwat <[email protected]> wrote: > >> I think it's there, https://reviews.llvm.org/D59625 . The backend seems >> to disallow linking with objects that use atomics features and are not >> tagged as such. That's how I have understood it. I fixed it in my build >> by adding pthread to my CFLAGS. >> You don't seem to have CFLAGS so prepending cmake with CFLAGS="-pthread" >> should do the trick. >> Let us know if it works :) >> >> On Wednesday, July 24, 2019 at 11:04:29 PM UTC+2, Dylan Staley wrote: >>> >>> Hello! I recently heard about the new WebAssembly backend, and wanted to >>> give it a try to compare against the fastcomp backend. I've successfully >>> compiled this project using `latest`, but when I switch to >>> `latest-upstream` I get the following issue during linking: >>> >>> ``` >>> wasm-ld: error: 'atomics' feature is used by d1_lib.o, so >>> --shared-memory must be used >>> wasm-ld: error: Target feature 'atomics' used in d1_lib.o is disallowed >>> by ConcurrentScheduler.cpp.o. Use --no-check-features to suppress. >>> ``` >>> >>> The actual command that failed was: >>> ``` >>> shared:ERROR: '/home/staley_dylan/emsdk/upstream/bin/wasm-ld -o >>> /tmp/emscripten_temp_DthpaW/td_wasm.wasm --allow-undefined --import-memory >>> --import-table --lto-O0 >>> CMakeFiles/td_wasm.dir/td/telegram/td_emscripten.cpp.o libtdjson_static.a >>> tdactor/libtdactor.a libtdjson_private.a libtdclient.a libtdcore.a >>> tdnet/libtdnet.a ../crypto/lib/libssl.a tddb/libtddb.a tdactor/libtdactor.a >>> tdutils/libtdutils.a sqlite/libtdsqlite.a ../crypto/lib/libcrypto.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libz.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libcompiler_rt.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc-wasm.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc++-noexcept.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc++abi.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc-extras.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libdlmalloc.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libpthreads_stub.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libcompiler_rt_wasm.a >>> /home/staley_dylan/.emscripten_cache/wasm-obj/libc_rt_wasm.a -mllvm >>> -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm >>> -disable-lsr --export __wasm_call_ctors --export __data_end --export main >>> --export malloc --export free --export setThrew --export __errno_location >>> --export htonl --export htons --export ntohs --export >>> emscripten_builtin_memalign --export memalign --export _get_environ >>> --export strlen --export _get_tzname --export _get_daylight --export >>> _get_timezone --export emscripten_builtin_free -z stack-size=5242880 >>> --initial-memory=16777216 --no-entry --global-base=1024' failed (1) >>> ``` >>> >>> I assume this is something to do with shared memory support in WASM, but >>> I haven't changed the configuration between a successful compile on >>> `latest` and this failing one on `latest-upstream`. Does anyone have any >>> idea? For reference, I'm trying to compile TdLib ( >>> https://github.com/tdlib/td >>> <https://www.google.com/url?q=https%3A%2F%2Fgithub.com%2Ftdlib%2Ftd&sa=D&sntz=1&usg=AFQjCNGFEkTIBqppIVw0j_ZPWBcfUNRVsw> >>> ). >>> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "emscripten-discuss" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/emscripten-discuss/tdjKEcKXXC8/unsubscribe >> . >> To unsubscribe from this group and all its topics, send an email to >> [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/emscripten-discuss/977d6ddf-d05b-40c5-a27d-37094d096252%40googlegroups.com >> <https://groups.google.com/d/msgid/emscripten-discuss/977d6ddf-d05b-40c5-a27d-37094d096252%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/CA%2Bu72ZnbstT4XzQs7uMszj5%2BX%2BCoAsZy4ggiBu0ujOt9UwvOuQ%40mail.gmail.com > <https://groups.google.com/d/msgid/emscripten-discuss/CA%2Bu72ZnbstT4XzQs7uMszj5%2BX%2BCoAsZy4ggiBu0ujOt9UwvOuQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. 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