How to compile with STANDALONE_WASM

[syrusakbary]

I've been trying to play with the new emscripten option STANDALONE_WASM (from emscripten-core/emscripten#9461 ), but all my attempts have been unsuccessful.

How STANDALONE_WASM can be enabled with the emsdk?

I tried so far:

Incoming SDK

./emsdk install sdk-incoming-64bit
./emsdk activate sdk-incoming-64bit

# and then
source ./emsdk_env.sh

But then, when trying to compile I got this error:

➜  tests git:(incoming) emcc hello_world.cpp -s STANDALONE_WASM=1
cache:INFO: generating system asset: is_vanilla.txt... (this will be cached in "/Users/syrusakbary/.emscripten_cache/is_vanilla.txt" for subsequent builds)
cache:INFO:  - ok
shared:INFO: (Emscripten: Running sanity checks)
shared:ERROR: STANDALONE_WASM is only available in the upstream wasm backend path

Mix incoming/upstream

Then, I activated upstream:

./emsdk install latest-upstream
./emsdk activate latest-upstream

Changing the ~/.emscripten file, to have incoming:

import os
LLVM_ROOT = '/Users/syrusakbary/Development/emsdk/upstream/bin'
# EMSCRIPTEN_ROOT = '/Users/syrusakbary/Development/emsdk/upstream/emscripten'
EMSCRIPTEN_ROOT = '/Users/syrusakbary/Development/emsdk/emscripten/incoming'
EMSCRIPTEN_NATIVE_OPTIMIZER = '/Users/syrusakbary/Development/emsdk/emscripten/incoming_64bit_optimizer/optimizer'
BINARYEN_ROOT = '/Users/syrusakbary/Development/emsdk/upstream'
NODE_JS = '/Users/syrusakbary/Development/emsdk/node/12.9.1_64bit/bin/node'
SPIDERMONKEY_ENGINE = ''
V8_ENGINE = ''
TEMP_DIR = '/var/folders/l5/vjn0dbf96fx3rd6d2vx2mcxm0000gn/T'
COMPILER_ENGINE = NODE_JS
JS_ENGINES = [NODE_JS]

But still fails:

➜  tests git:(incoming) emcc hello_world.cpp -o hello.wasm
cache:INFO: generating system library: libc.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libc.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libcompiler_rt.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libcompiler_rt.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libc-wasm.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libc-wasm.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libdlmalloc.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libdlmalloc.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libpthreads_stub.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libpthreads_stub.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libcompiler_rt_wasm.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libcompiler_rt_wasm.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libc_rt_wasm.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libc_rt_wasm.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system library: libstandalonewasm.a... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/libstandalonewasm.a" for subsequent builds)
cache:INFO:  - ok
cache:INFO: generating system asset: generated_struct_info.json... (this will be cached in "/Users/syrusakbary/.emscripten_cache/wasm-obj/generated_struct_info.json" for subsequent builds)
cache:INFO:  - ok
Unknown option '--standalone-wasm'
shared:ERROR: '/Users/syrusakbary/Development/emsdk/upstream/bin/wasm-emscripten-finalize /var/folders/l5/vjn0dbf96fx3rd6d2vx2mcxm0000gn/T/emscripten_temp_SyKPuo/hello.wasm -o /var/folders/l5/vjn0dbf96fx3rd6d2vx2mcxm0000gn/T/emscripten_temp_SyKPuo/hello.wasm.o.wasm --detect-features --no-legalize-javascript-ffi --global-base=1024 --standalone-wasm' failed (1)

Any idea on how can I start using it?

[kripken]

This option hasn't reached a tagged version yet - it landed friday, and we haven't tagged a release since that time.

You can however use a tip-of-tree build to try it, tot-upstream instead of latest-upstream.

[syrusakbary]

Thanks!