docs: working selfhosted example

Signed-off-by: Henry Gressmann <mail@henrygressmann.de>

.gitignore

@@ -1,4 +1,4 @@
 /target
 notes.md
-examples/tinywasm.wat
+examples/rust/out/*
 examples/wast/*

Cargo.toml

@@ -1,7 +1,14 @@
 [workspace]
-members=["crates/*"]
+members=["crates/*", "examples/rust"]
 resolver="2"
 
+[profile.wasm]
+opt-level="z"
+lto="thin"
+codegen-units=1
+panic="abort"
+inherits="release"
+
 [workspace.package]
 version="0.3.0-alpha.0"
 edition="2021"

README.md

@@ -12,7 +12,7 @@
 
 # Status
 
-TinyWasm, starting from upcoming version `0.3.0`, passes all the WebAssembly 1.0 tests in the [WebAssembly Test Suite](https://github.com/WebAssembly/testsuite). The 2.0 tests are in progress (notably `simd` and `bulk-memory-operations` are not implemented yet).
+TinyWasm, starting from version `0.3.0`, passes all the WebAssembly 1.0 tests in the [WebAssembly Test Suite](https://github.com/WebAssembly/testsuite). The 2.0 tests are in progress (notably `simd` and `bulk-memory-operations` are not implemented yet). This is enough to run most WebAssembly programs, including TinyWasm itself compiled to WebAssembly (see [examples/wasm-rust.rs](./examples/wasm-rust.rs)).
 
 Some APIs to interact with the runtime are not yet exposed, and the existing ones are subject to change, but the core functionality is mostly complete.
 Results of the tests can be found [here](https://github.com/explodingcamera/tinywasm/tree/main/crates/tinywasm/tests/generated).
@@ -56,16 +56,7 @@ $ cargo add tinywasm
   Enables the `tinywasm-parser` crate. This is enabled by default.
 
 With all these features disabled, TinyWasm only depends on `core`, `alloc` and `libm` and can be used in `no_std` environments.
-
-<!-- # 🎯 Goals
-
-- Self-hosted (can run itself compiled to WebAssembly)
-- No unsafe code
-- Works on `no_std` (with `alloc` the feature and nightly compiler)
-- Fully support WebAssembly MVP (1.0)
-- Low Memory Usage (less than 10kb)
-- Fast Startup Time
-- Preemptive multitasking support -->
+Since `libm` is not as performant as the compiler's built-in math intrinsics, it is recommended to use the `std` feature if possible (at least [for now](https://github.com/rust-lang/rfcs/issues/2505)).
 
 ## Performance
 

crates/tinywasm/src/error.rs

@@ -186,8 +186,8 @@ impl Display for Error {
             #[cfg(feature = "std")]
             Self::Io(err) => write!(f, "I/O error: {}", err),
 
-            Self::Trap(trap) => write!(f, "trap: {}", trap.message()),
-            Self::Linker(err) => write!(f, "linking error: {}", err.message()),
+            Self::Trap(trap) => write!(f, "trap: {}", trap),
+            Self::Linker(err) => write!(f, "linking error: {}", err),
             Self::CallStackEmpty => write!(f, "call stack empty"),
             Self::InvalidLabelType => write!(f, "invalid label type"),
             Self::Other(message) => write!(f, "unknown error: {}", message),
@@ -200,6 +200,42 @@ impl Display for Error {
     }
 }
 
+impl Display for LinkingError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::UnknownImport { module, name } => write!(f, "unknown import: {}.{}", module, name),
+            Self::IncompatibleImportType { module, name } => {
+                write!(f, "incompatible import type: {}.{}", module, name)
+            }
+        }
+    }
+}
+
+impl Display for Trap {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::Unreachable => write!(f, "unreachable"),
+            Self::MemoryOutOfBounds { offset, len, max } => {
+                write!(f, "out of bounds memory access: offset={}, len={}, max={}", offset, len, max)
+            }
+            Self::TableOutOfBounds { offset, len, max } => {
+                write!(f, "out of bounds table access: offset={}, len={}, max={}", offset, len, max)
+            }
+            Self::DivisionByZero => write!(f, "integer divide by zero"),
+            Self::InvalidConversionToInt => write!(f, "invalid conversion to integer"),
+            Self::IntegerOverflow => write!(f, "integer overflow"),
+            Self::CallStackOverflow => write!(f, "call stack exhausted"),
+            Self::UndefinedElement { index } => write!(f, "undefined element: index={}", index),
+            Self::UninitializedElement { index } => {
+                write!(f, "uninitialized element: index={}", index)
+            }
+            Self::IndirectCallTypeMismatch { expected, actual } => {
+                write!(f, "indirect call type mismatch: expected={:?}, actual={:?}", expected, actual)
+            }
+        }
+    }
+}
+
 #[cfg(any(feature = "std", all(not(feature = "std"), nightly)))]
 impl crate::std::error::Error for Error {}
 

examples/README.md

@@ -0,0 +1,22 @@
+# Examples
+
+## WasmRust
+
+These are examples using WebAssembly generated from Rust code.
+To run these, you first need to build the Rust code into WebAssembly, since the wasm files are not included in the repository to keep it small.
+This requires the `wasm32-unknown-unknown` target and `wasm-opt` to be installed (available via Binaryen).
+
+```bash
+$ ./examples/rust/build.sh
+```
+
+Then you can run the examples:
+
+```bash
+$ cargo run --example wasm-rust <example>
+```
+
+Where `<example>` is one of the following:
+
+- `hello`: A simple example that prints a number to the console.
+- `tinywasm`: Runs `hello` using TinyWasm - inside of TinyWasm itself!

examples/rust/Cargo.toml

@@ -7,8 +7,7 @@ forced-target="wasm32-unknown-unknown"
 edition="2021"
 
 [dependencies]
-tinywasm={path="../../crates/tinywasm", default-features=false, features=["parser"]}
-embedded-alloc={version="0.5"}
+tinywasm={path="../../crates/tinywasm", features=["parser", "std"]}
 
 [[bin]]
 name="hello"
@@ -17,7 +16,3 @@ path="src/hello.rs"
 [[bin]]
 name="tinywasm"
 path="src/tinywasm.rs"
-
-[profile.release]
-opt-level="z"
-panic="abort"

examples/rust/build.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+cd "$(dirname "$0")"
+
+bins=("hello" "tinywasm")
+exclude_wat=("tinywasm")
+out_dir="../../target/wasm32-unknown-unknown/wasm"
+dest_dir="out"
+
+for bin in "${bins[@]}"; do
+    cargo build --target wasm32-unknown-unknown --package rust-wasm-examples --profile=wasm --bin "$bin"
+
+    cp "$out_dir/$bin.wasm" "$dest_dir/"
+    wasm-opt "$dest_dir/$bin.wasm" -o "$dest_dir/$bin.wasm" -O --intrinsic-lowering -O
+
+    if [[ ! " ${exclude_wat[@]} " =~ " $bin " ]]; then
+        wasm2wat "$dest_dir/$bin.wasm" -o "$dest_dir/$bin.wat"
+    fi
+done

examples/rust/src/tinywasm.rs

@@ -1,41 +1,32 @@
-#![no_std]
 #![no_main]
+use tinywasm::{Extern, FuncContext};
 
-use embedded_alloc::Heap;
-// use tinywasm::{Extern, FuncContext};
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    core::arch::wasm32::unreachable()
+#[link(wasm_import_module = "env")]
+extern "C" {
+    fn printi32(x: i32);
 }
 
-#[global_allocator]
-static HEAP: Heap = Heap::empty();
-
 #[no_mangle]
-pub unsafe extern "C" fn _start() {
-    // Initialize the allocator BEFORE you use it
-    {
-        use core::mem::MaybeUninit;
-        const HEAP_SIZE: usize = 1024;
-        static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
-        unsafe { HEAP.init(HEAP_MEM.as_ptr() as usize, HEAP_SIZE) }
-    }
-
-    // now the allocator is ready types like Box, Vec can be used.
+pub extern "C" fn hello() {
     let _ = run();
 }
 
 fn run() -> tinywasm::Result<()> {
-    // let module = tinywasm::Module::parse_bytes(include_bytes!("../out/hello.wasm"))?;
-    // let mut store = tinywasm::Store::default();
-
-    // let mut imports = tinywasm::Imports::new();
-    // imports.define("env", "printi32", Extern::typed_func(|_: FuncContext<'_>, _: i32| Ok(())))?;
-
-    // let instance = module.instantiate(&mut store, Some(imports))?;
-    // let add_and_print = instance.typed_func::<(i32, i32), ()>(&mut store, "add_and_print")?;
-    // add_and_print.call(&mut store, (1, 2))?;
+    let module = tinywasm::Module::parse_bytes(include_bytes!("../../wasm/hello.wasm"))?;
+    let mut store = tinywasm::Store::default();
+    let mut imports = tinywasm::Imports::new();
+
+    imports.define(
+        "env",
+        "printi32",
+        Extern::typed_func(|_: FuncContext<'_>, v: i32| {
+            unsafe { printi32(v) }
+            Ok(())
+        }),
+    )?;
+    let instance = module.instantiate(&mut store, Some(imports))?;
+
+    let add_and_print = instance.typed_func::<(i32, i32), ()>(&mut store, "add_and_print")?;
+    add_and_print.call(&mut store, (1, 2))?;
     Ok(())
 }

examples/wasm-rust.rs

@@ -7,35 +7,59 @@ fn main() -> Result<()> {
         println!("Usage: cargo run --example wasm-rust <rust_example>");
         println!("Available examples:");
         println!("  hello");
+        println!("  tinywasm");
         return Ok(());
     }
 
     match args[1].as_str() {
         "hello" => hello()?,
+        "tinywasm" => tinywasm()?,
         _ => {}
     }
 
     Ok(())
 }
 
+fn tinywasm() -> Result<()> {
+    const TINYWASM: &[u8] = include_bytes!("./rust/out/tinywasm.wasm");
+    let module = Module::parse_bytes(&TINYWASM)?;
+    let mut store = Store::default();
+
+    let mut imports = Imports::new();
+    imports.define(
+        "env",
+        "printi32",
+        Extern::typed_func(|_: FuncContext<'_>, x: i32| {
+            println!("{}", x);
+            Ok(())
+        }),
+    )?;
+    let instance = module.instantiate(&mut store, Some(imports))?;
+
+    let hello = instance.typed_func::<(), ()>(&mut store, "hello")?;
+    hello.call(&mut store, ())?;
+
+    Ok(())
+}
+
 fn hello() -> Result<()> {
-    // const HELLO_WASM: &[u8] = include_bytes!("./rust/out/hello.wasm");
-    // let module = Module::parse_bytes(&HELLO_WASM)?;
-    // let mut store = Store::default();
-
-    // let mut imports = Imports::new();
-    // imports.define(
-    //     "env",
-    //     "printi32",
-    //     Extern::typed_func(|_: FuncContext<'_>, x: i32| {
-    //         println!("{}", x);
-    //         Ok(())
-    //     }),
-    // )?;
-
-    // let instance = module.instantiate(&mut store, Some(imports))?;
-    // let add_and_print = instance.typed_func::<(i32, i32), ()>(&mut store, "add_and_print")?;
-    // add_and_print.call(&mut store, (1, 2))?;
+    const HELLO_WASM: &[u8] = include_bytes!("./rust/out/hello.wasm");
+    let module = Module::parse_bytes(&HELLO_WASM)?;
+    let mut store = Store::default();
+
+    let mut imports = Imports::new();
+    imports.define(
+        "env",
+        "printi32",
+        Extern::typed_func(|_: FuncContext<'_>, x: i32| {
+            println!("{}", x);
+            Ok(())
+        }),
+    )?;
+
+    let instance = module.instantiate(&mut store, Some(imports))?;
+    let add_and_print = instance.typed_func::<(i32, i32), ()>(&mut store, "add_and_print")?;
+    add_and_print.call(&mut store, (1, 2))?;
 
     Ok(())
 }