Issue with Bulk Memory Operation Error in Web Window Init Example

[petrasvestartas]

Hi,

I’ve been learning from scratch using the website tutorials, and I managed to set up the web window init example via Vue, though it wasn’t easy. You can find the example code here: GitHub Link

Everything works, but I had to add the following flag to Cargo.toml to make it work:

[package.metadata.wasm-pack.profile.release]
wasm-opt = false

I’m wondering why this error happens and what exactly the bulk memory operation means. Could someone provide some insights?

Otherwise I get this error:

...
[wasm-validator error in function 800] unexpected false: Bulk memory operations require bulk memory [--enable-bulk-memory], on 
(memory.copy
 (local.get $0)
 (local.get $1)
 (i32.const 176)
)
[wasm-validator error in function 1075] unexpected false: all used features should be allowed, on 
(i32.trunc_sat_f64_u
 (call $537
  (local.get $0)
 )
)
[wasm-validator error in function 1076] unexpected false: all used features should be allowed, on 
(i32.trunc_sat_f64_s
 (call $537
  (local.get $0)
 )
)
Fatal: error validating input
Error: failed to execute `wasm-opt`: exited with exit status: 1
  full command: "/Users/petras/Library/Caches/.wasm-pack/wasm-opt-50385c9e73ccee70/bin/wasm-opt" "/Users/petras/rust/wink/pkg/wink_bg.wasm" "-o" "/Users/petras/rust/wink/pkg/wink_bg.wasm-opt.wasm" "-O"
To disable `wasm-opt`, add `wasm-opt = false` to your package metadata in your `Cargo.toml`.
Caused by: failed to execute `wasm-opt`: exited with exit status: 1
  full command: "/Users/petras/Library/Caches/.wasm-pack/wasm-opt-50385c9e73ccee70/bin/wasm-opt" "/Users/petras/rust/wink/pkg/wink_bg.wasm" "-o" "/Users/petras/rust/wink/pkg/wink_bg.wasm-opt.wasm" "-O"

[pwbh]

It seems that the following

[profile.release]
strip = true

is causing the issue when compiling for WASM, this can be safely removed as wasm-opt will do the optimization that it needs to do.

Edit: You should keep it if you want to build native executables, you'll need someway to conditionally include it though so it won't interfere for WASM build.

[supercooltest2024]

Bulk memory operations is a wasm extension that adds a few instructions (to improve performance):

Name	Opcode	Immediate	Description
memory.init	0xfc 0x08	segment:varuint32, memory:0x00	copy from a passive data segment to linear memory
data.drop	0xfc 0x09	segment:varuint32	prevent further use of passive data segment
memory.copy	0xfc 0x0a	memory_dst:0x00 memory_src:0x00	copy from one region of linear memory to another region
memory.fill	0xfc 0x0b	memory:0x00	fill a region of linear memory with a given byte value
table.init	0xfc 0x0c	segment:varuint32, table:0x00	copy from a passive element segment to a table
elem.drop	0xfc 0x0d	segment:varuint32	prevent further use of a passive element segment
table.copy	0xfc 0x0e	table_dst:0x00 table_src:0x00	copy from one region of a table to another region

Notably, being an extension it isn't in MVP wasm. All the various tools in the build pipeline need to agree which wasm extensions are in use.

See https://github.com/wngr/wasm-futures-executor#:~:text=And%20build%20your%20project%20with but pretty much you need to enable target features for the wasm features you are using (and consider availability https://webassembly.org/features/). Also make sure to build with atomics if you want multithreading support in browser. Consider recompiling the standard library as these flags aren't enabled by default.

RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \
  cargo +nightly build --target wasm32-unknown-unknown --release -Z build-std=std,panic_abort

wasm-bindgen \
  ./target/wasm32-unknown-unknown/release/sample.wasm \
  --out-dir . \
  --target web \
  --weak-refs