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@lilac
Created October 17, 2023 01:34
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Wasm with threads
.phony: run
run: thread.wasm
wasmtime run --wasm-features threads --wasi-modules experimental-wasi-threads ./thread.wasm
thread.wasm: thread.wat
wat2wasm --debug-names --enable-threads thread.wat
(module
(func $fd_write (import "wasi_unstable" "fd_write")
(param $fd i32)
(param $iovs i32)
(param $iovs_len i32)
(param $nwritten i32)
(result i32))
(func $spawn_thread (import "wasi" "thread-spawn")
(param $arg i32)
(result i32))
(memory $mem (import "env" "memory") 1 1 shared)
(export "memory" (memory $mem))
(data
(i32.const 1000)
"From main thread\n\00")
(data
(i32.const 1100)
"From thread 1\n\00")
(data
(i32.const 1200)
"From thread 2\n\00")
(func $print
(param $str_ptr i32)
(i32.store
(i32.const 0)
(local.get $str_ptr))
(i32.store
(i32.const 4)
(call $strlen
(local.get $str_ptr)))
(call $fd_write
(i32.const 1)
(i32.const 0)
(i32.const 1)
(i32.const 12))
drop)
(func $strlen
(param $str_ptr i32)
(result i32)
(local $ctr i32)
(local.set $ctr
(i32.const 0))
(block $done
(loop $continue
(br_if $done
(i32.eqz
(i32.load8_u
(i32.add
(local.get $str_ptr)
(local.get $ctr)))))
(local.set $ctr
(i32.add
(local.get $ctr)
(i32.const 1)))
(br $continue)))
(local.get $ctr))
(func (export "_start")
(call $print
(i32.const 1000))
(drop
(call $spawn_thread
(i32.const 1100)))
(drop
(call $spawn_thread
(i32.const 1200)))
;; Wait until other thread has finished
(drop
(memory.atomic.wait32
(i32.const 2000)
(i32.const 0)
(i64.const -1)))
(drop
(memory.atomic.wait32
(i32.const 2000)
(i32.const 1)
(i64.const -1))))
(func (export "wasi_thread_start")
(param $thread_id i32)
(param $arg i32)
(call $print
(local.get $arg))
(drop
(i32.atomic.rmw.add
(i32.const 2000)
(i32.const 1)))
(drop
(memory.atomic.notify
(i32.const 2000)
(i32.const 1)))))
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