Emscripten SIDE_MODULE config and scripts.

Author: rkistner

Cargo.toml

@@ -19,10 +19,9 @@ lto = true
 
 [profile.wasm]
 inherits = "release"
-# Enabling LTO in WASM build gives:
-# warning: Linking globals named '__rust_alloc_error_handler': symbol multiply defined!
-# error: failed to load bitcode of module "sgnxivc9sns8d6t":
-lto = false
+
+[profile.wasm_asyncify]
+inherits = "wasm"
 
 [workspace.package]
 version = "0.3.0"

crates/loadable/src/lib.rs

@@ -31,27 +31,10 @@ fn panic(_info: &core::panic::PanicInfo) -> ! {
 #[lang = "eh_personality"]
 extern "C" fn eh_personality() {}
 
-#[cfg(target_family = "wasm")]
-#[no_mangle]
-pub fn __rust_alloc_error_handler(_: core::alloc::Layout) -> ! {
-    core::intrinsics::abort()
-}
-
-#[cfg(target_family = "wasm")]
-#[no_mangle]
-static __rust_alloc_error_handler_should_panic: u8 = 0;
-
 #[cfg(target_family = "wasm")]
 #[no_mangle]
 static _CLOCK_PROCESS_CPUTIME_ID: i32 = 1;
 
 #[cfg(target_family = "wasm")]
 #[no_mangle]
 static _CLOCK_THREAD_CPUTIME_ID: i32 = 1;
-
-// Not used, but must be defined in some cases. Most notably when using native sqlite3 and loading
-// the extension.
-// #[allow(non_upper_case_globals)]
-// #[no_mangle]
-// pub static mut _Unwind_Resume: *mut core::ffi::c_void = core::ptr::null_mut();
-

tool/build_wasm.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+set -e
+
+# Normal build
+# target/wasm32-unknown-emscripten/wasm/powersync.wasm
+RUSTFLAGS="-C link-arg=-sSIDE_MODULE=2" \
+  cargo build \
+    -p powersync_loadable \
+    --profile wasm \
+    --no-default-features \
+    --features "powersync_core/static powersync_core/omit_load_extension sqlite_nostd/omit_load_extension" \
+    -Z build-std=panic_abort,core,alloc \
+    --target wasm32-unknown-emscripten
+
+
+# Asyncify
+# target/wasm32-unknown-emscripten/wasm_asyncify/powersync.wasm
+RUSTFLAGS="-C link-arg=-sSIDE_MODULE=2 -C link-arg=-sASYNCIFY=1 -C link-arg=-sJSPI_IMPORTS=@wasm/asyncify_imports.json" \
+  cargo build \
+    -p powersync_loadable \
+    --profile wasm_asyncify \
+    --no-default-features \
+    --features "powersync_core/static powersync_core/omit_load_extension sqlite_nostd/omit_load_extension" \
+    -Z build-std=panic_abort,core,alloc \
+    --target wasm32-unknown-emscripten

wasm/asyncify_imports.json

@@ -0,0 +1,14 @@
+[
+  "sqlite3_close",
+  "sqlite3_finalize",
+  "sqlite3_open_v2",
+  "sqlite3_prepare",
+  "sqlite3_prepare16",
+  "sqlite3_prepare_v2",
+  "sqlite3_prepare16_v2",
+  "sqlite3_prepare_v3",
+  "sqlite3_prepare16_v3",
+  "sqlite3_reset",
+  "sqlite3_step",
+  "sqlite3_exec"
+]