Wasmex as static lib OTP nif, lib sizes currently 150-500MB

[adiibanez]

I'm in the process of integrating an OTP-27 runtime for native targets like osx, ios, android, ... based on elixir-desktop

including wasmex would be very interesting to run eg. electricsql's wasi pglite. or other wasm packages related to sensors, ai, ...

I did some poc integration with pglite based on a preview build and could at least read imports / exports. their api is not exposed yet. Resp. only for the browser / node.js wasm targets.

The size of the libwasmex static lib is kind of a problem. Are there any ways to reduce the size? Eg. disable nonessential features of wasmtime?

before stripping:
-rw-r--r-- 1 runner staff 471M Mar 18 22:01 /Users/runner/work/elixir-desktop-runtimes/elixir-desktop-runtimes/_build/nifs/libwasmex.a
-rw-r--r-- 1 runner staff 2.1M Mar 18 21:58 /Users/runner/work/elixir-desktop-runtimes/elixir-desktop-runtimes/_build/nifs/sqlite3_nif.a

after stripping:
-rw-r--r-- 1 runner staff 148M Mar 18 22:01 /Users/runner/work/elixir-desktop-runtimes/elixir-desktop-runtimes/_build/nifs/libwasmex.a
-rw-r--r-- 1 runner staff 2.0M Mar 18 22:01 /Users/runner/work/elixir-desktop-runtimes/elixir-desktop-runtimes/_build/nifs/sqlite3_nif.a

This is how I build the static lib. The rustflags are there to enable OTP to statically link multiple rust nifs ( avoid duplicate symbols related to std lib duplicate symbol '__ZN3std9panicking11EMPTY_PANIC17h38cb21ffaeece953E' / duplicate symbol '_rust_eh_personality' )

CARGO_CMD="cargo rustc --crate-type staticlib --target=${{matrix.platform.rust_target}} --features rustler/staticlib -- -C opt-level=z -C codegen-units=1"

git clone --depth 1 https://github.com/adiibanez/wasmex.git --branch static-no-precompiled
cd wasmex

cd native/wasmex
# N rust lib, exclude std lib
RUSTFLAGS="-C target-feature=-crt-static -C link-arg=-nostdlib -C panic=abort" \
$CARGO_CMD

[adiibanez]

TARGET=aarch64-apple-ios-sim
RUSTFLAGS="-C embed-bitcode=yes -C lto=fat"
cargo +nightly rustc --crate-type staticlib --release \
  --target=$TARGET \
  -- \
  -C opt-level=z \
  -C strip=symbols \
  -C panic=abort \
  -C link-arg=-Wl,-dead_strip \
  -C link-arg=-Wl,--gc-sections

find target/$TARGET/release/ -name "*.a" -exec ls -lah {} ;

takes 7mins to build on shared github runner but the size of the lib looks more reasonable now with 19M

getting duplicate symbol exceptions again in the OTP-build process with these settings but that's another issue.
Couldn't test the lib yet but maybe you could check on your side what can be done to reduce size safely?

rusterlium/rustler#688

[tessi]

wow, ok. this is great work. I have not optimized for lib size yet in any meaningful way. I believe the best strategy (apart from the compilation flags magic you do!) is to go through our Cargo.toml and remove (comment-out) dependencies that are not essential and then comment out all things that stop compiling.

Looks like wit-parser, wat, wasmtime-wasi-http could be removed if you don't plan on using wasm components (though they are awesome!). wasmtime-wasi-http specifically should be optional even if using components.

[adiibanez]

This seems like a good source of information https://docs.wasmtime.dev/examples-minimal.html for wasmtime but rust in general too