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bench: add more WASI benchmarks (#5309)
* bench: add more WASI benchmarks This follows up on #5274 to add several more scenarios with which to benchmark WASI performance: - `open-file.wat`: opens and closes a file - `read-file.wat`: opens a file, reads 4K bytes from it, then closes it - `read-dir.wat`: reads a directory's entries Each benchmark is hand-crafted WAT to more clearly control what WASI calls are made. As with #5274, these modules' sole entry point takes a parameter indicating the number of iterations to run in order to use `criterion`'s `iter_custom` feature. * fix: reduce expected size of directory entries
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‎benches/wasi.rs‎

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//! Measure some common WASI call scenarios.
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use criterion::{criterion_group, criterion_main, Criterion};
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use std::time::Instant;
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use std::{fs::File, path::Path, time::Instant};
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use wasmtime::{Engine, Linker, Module, Store, TypedFunc};
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use wasmtime_wasi::{sync::WasiCtxBuilder, WasiCtx};
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criterion_group!(benches, bench_wasi);
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criterion_main!(benches);
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fn bench_wasi(c: &mut Criterion) {
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let _ = env_logger::try_init();
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// Build a zero-filled test file if it does not yet exist.
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let test_file = Path::new("benches/wasi/test.bin");
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if !test_file.is_file() {
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let file = File::create(test_file).unwrap();
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file.set_len(4096).unwrap();
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}
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// Benchmark each `*.wat` file in the `wasi` directory.
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for file in std::fs::read_dir("benches/wasi").unwrap() {
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let path = file.unwrap().path();
@@ -67,5 +76,11 @@ fn wasi_context() -> WasiCtx {
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"--flag4".to_string(),
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])
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.unwrap()
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.preopened_dir(
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wasmtime_wasi::Dir::open_ambient_dir("benches/wasi", wasmtime_wasi::ambient_authority())
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.unwrap(),
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"/",
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)
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.unwrap()
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.build()
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}

‎benches/wasi/.gitignore‎

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test.bin

‎benches/wasi/open-file.wat‎

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;; Repeatedly open and close `test.bin`.
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(module
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(import "wasi_snapshot_preview1" "path_open"
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(func $__wasi_path_open (param i32 i32 i32 i32 i32 i64 i64 i32 i32) (result i32)))
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(import "wasi_snapshot_preview1" "fd_read"
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(func $__wasi_fd_read (param i32 i32 i32 i32) (result i32)))
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(import "wasi_snapshot_preview1" "fd_close"
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(func $__wasi_fd_close (param i32) (result i32)))
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(func (export "run") (param $iters i64) (result i64)
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(local $i i64)
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(local.set $i (i64.const 0))
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(loop $cont
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;; Open the file `test.bin` under the same directory as this WAT
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;; file; this assumes some prior set up of the preopens in
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;; `wasi.rs`. See https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witx/wasi_snapshot_preview1.witx#L346.
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(call $__wasi_path_open
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;; The fd of the preopen under which to search for the file;
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;; the first three are the `std*` ones.
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(i32.const 3)
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;; The lookup flags (i.e., whether to follow symlinks).
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(i32.const 0)
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;; The path to the file under the initial fd.
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(i32.const 0)
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(i32.const 8)
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;; The open flags; in this case we will only attempt to read but
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;; this may attempt to create the file if it does not exist, see
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;; https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witxtypenames.witx#L444).
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(i32.const 0)
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;; The base rights and the inheriting rights: here we only set
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;; the bits for the FD_READ and FD_READDIR capabilities.
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(i64.const 0x2002)
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(i64.const 0x2002)
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;; The file descriptor flags (e.g., whether to append, sync,
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;; etc.); see https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witx/typenames.witx#L385
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(i32.const 0)
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;; The address at which to store the opened fd (if the call
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;; succeeds)
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(i32.const 16))
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(if (then unreachable))
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;; Close the open file handle we stored at offset 16.
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(call $__wasi_fd_close (i32.load (i32.const 16)))
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(if (then unreachable))
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;; Continue looping until $i reaches $iters.
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(local.set $i (i64.add (local.get $i) (i64.const 1)))
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(br_if $cont (i64.lt_u (local.get $i) (local.get $iters)))
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)
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(local.get $i)
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)
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(data (i32.const 0) "test.bin")
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(memory (export "memory") 1)
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)

‎benches/wasi/read-dir.wat‎

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;; Read the directory entries of the preopened directory.
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(module
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(import "wasi_snapshot_preview1" "fd_readdir"
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(func $__wasi_fd_readdir (param i32 i32 i32 i64 i32) (result i32)))
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(func (export "run") (param $iters i64) (result i64)
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(local $i i64)
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(local.set $i (i64.const 0))
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(if (i32.ne (i32.load (i32.const 0)) (i32.const 0))
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(then unreachable))
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(loop $cont
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;; Read the file into the sole iovec buffer.
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(call $__wasi_fd_readdir
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;; The fd of the preopened directory; the first three are the
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;; `std*` ones.
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(i32.const 3)
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;; The buffer address at which to store the entries and the
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;; length of the buffer.
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(i32.const 16)
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(i32.const 4096)
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;; The location at which to start reading entries in the
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;; directory; here we start at the first entry.
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(i64.const 0)
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;; The address at which to store the number of bytes read.
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(i32.const 8))
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(drop)
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;; Check that we indeed read at least 380 bytes of directory
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;; entries.
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(if (i32.lt_u (i32.load (i32.const 8)) (i32.const 300))
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(then unreachable))
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;; Continue looping until $i reaches $iters.
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(local.set $i (i64.add (local.get $i) (i64.const 1)))
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(br_if $cont (i64.lt_u (local.get $i) (local.get $iters)))
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)
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(local.get $i)
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)
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(memory (export "memory") 1)
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)

‎benches/wasi/read-file.wat‎

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;; Repeatedly read the contents of `test.bin`.
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(module
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(import "wasi_snapshot_preview1" "path_open"
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(func $__wasi_path_open (param i32 i32 i32 i32 i32 i64 i64 i32 i32) (result i32)))
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(import "wasi_snapshot_preview1" "fd_read"
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(func $__wasi_fd_read (param i32 i32 i32 i32) (result i32)))
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(import "wasi_snapshot_preview1" "fd_close"
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(func $__wasi_fd_close (param i32) (result i32)))
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(func (export "run") (param $iters i64) (result i64)
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(local $i i64)
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(local.set $i (i64.const 0))
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;; Set up the iovec list; the memory usage for this module should be:
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;; - offset 0 => file name
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;; - offset 16 => the opened file descriptor
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;; - offset 24 => the number of read bytes
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;; - offset 32 => the iovec list
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;; - offset 48 => the first (and only) iovec buffer
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(i32.store (i32.const 32) (i32.const 48))
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(i32.store (i32.const 36) (i32.const 4096))
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(loop $cont
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;; Open the file `test.bin` under the same directory as this WAT
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;; file; this assumes some prior set up of the preopens in
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;; `wasi.rs`. See https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witx/wasi_snapshot_preview1.witx#L346.
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(call $__wasi_path_open
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;; The fd of the preopen under which to search for the file;
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;; the first three are the `std*` ones.
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(i32.const 3)
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;; The lookup flags (i.e., whether to follow symlinks).
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(i32.const 0)
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;; The path to the file under the initial fd.
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(i32.const 0)
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(i32.const 8)
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;; The open flags; in this case we will only attempt to read but
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;; this may attempt to create the file if it does not exist, see
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;; https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witxtypenames.witx#L444).
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(i32.const 0)
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;; The base rights and the inheriting rights: here we only set
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;; the bits for the FD_READ and FD_READDIR capabilities.
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(i64.const 0x2002)
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(i64.const 0x2002)
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;; The file descriptor flags (e.g., whether to append, sync,
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;; etc.); see https://github.com/WebAssembly/WASI/blob/d8da230b/phases/snapshot/witx/typenames.witx#L385
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(i32.const 0)
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;; The address at which to store the opened fd (if the call
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;; succeeds)
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(i32.const 16))
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(if (then unreachable))
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;; Read the file into the sole iovec buffer.
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(call $__wasi_fd_read
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;; The now-open fd stored at offset 16.
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(i32.load (i32.const 16))
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;; The address and size of the list of iovecs; here we only use
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;; a list of a single iovec set up outside the loop.
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(i32.const 32)
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(i32.const 1)
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;; The address at which to store the number of bytes read.
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(i32.const 24))
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(if (then unreachable))
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;; Check that we indeed read 4096 bytes.
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(if (i32.ne (i32.load (i32.const 24)) (i32.const 4096))
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(then unreachable))
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;; Close the open file handle we stored at offset 16.
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(call $__wasi_fd_close (i32.load (i32.const 16)))
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(if (then unreachable))
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;; Continue looping until $i reaches $iters.
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(local.set $i (i64.add (local.get $i) (i64.const 1)))
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(br_if $cont (i64.lt_u (local.get $i) (local.get $iters)))
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)
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(local.get $i)
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)
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(data (i32.const 0) "test.bin")
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(memory (export "memory") 1)
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)

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