Merge pull request #2118 from fitzgen/enable-ref-types-by-default

Enable ref types and bulk memory operations by default

cranelift/codegen/src/regalloc/context.rs

@@ -203,17 +203,22 @@ impl Context {
             &mut self.tracker,
         );
 
-        // This function runs after register allocation has taken
+        // If there are any reference types used, encode safepoints and emit
-        // place, meaning values have locations assigned already.
+        // stack maps.
-        if isa.flags().enable_safepoints() {
+        //
-            emit_stack_maps(func, domtree, &self.liveness, &mut self.tracker, isa);
+        // This function runs after register allocation has taken place, meaning
-        } else {
+        // values have locations assigned already, which is necessary for
-            // Make sure no references are used.
+        // creating the stack maps.
-            for val in func.dfg.values() {
+        let safepoints_enabled = isa.flags().enable_safepoints();
-                let ty = func.dfg.value_type(val);
+        for val in func.dfg.values() {
-                if ty.lane_type().is_ref() {
+            let ty = func.dfg.value_type(val);
-                    panic!("reference types were found but safepoints were not enabled.");
+            if ty.lane_type().is_ref() {
-                }
+                assert!(
+                    safepoints_enabled,
+                    "reference types were found but safepoints were not enabled"
+                );
+                emit_stack_maps(func, domtree, &self.liveness, &mut self.tracker, isa);
+                break;
             }
         }
 

crates/wasmtime/src/runtime.rs

@@ -99,8 +99,8 @@ impl Config {
             memory_creator: None,
             max_wasm_stack: 1 << 20,
             wasm_threads: false,
-            wasm_reference_types: false,
+            wasm_reference_types: cfg!(target_arch = "x86_64"),
-            wasm_bulk_memory: false,
+            wasm_bulk_memory: true,
             wasm_simd: false,
             wasm_multi_value: true,
         }
@@ -175,25 +175,17 @@ impl Config {
         self
     }
 
-    /// Configures whether the WebAssembly reference types proposal will be
+    /// Configures whether the [WebAssembly reference types proposal][proposal]
-    /// enabled for compilation.
+    /// will be enabled for compilation.
     ///
-    /// The [WebAssembly reference types proposal][proposal] is not currently
+    /// This feature gates items such as the `externref` and `funcref` types as
-    /// fully standardized and is undergoing development. Additionally the
+    /// well as allowing a module to define multiple tables.
-    /// support in wasmtime itself is still being worked on. Support for this
-    /// feature can be enabled through this method for appropriate wasm
-    /// modules.
     ///
-    /// This feature gates items such as the `externref` type and multiple tables
+    /// Note that enabling the reference types feature will also enable the bulk
-    /// being in a module. Note that enabling the reference types feature will
+    /// memory feature.
-    /// also enable the bulk memory feature.
     ///
-    /// This is `false` by default.
+    /// This is `true` by default on x86-64, and `false` by default on other
-    ///
+    /// architectures.
-    /// > **Note**: Wasmtime does not implement everything for the reference
-    /// > types proposal spec at this time, so bugs, panics, and possibly
-    /// > segfaults should be expected. This should not be enabled in a
-    /// > production setting right now.
     ///
     /// [proposal]: https://github.com/webassembly/reference-types
     pub fn wasm_reference_types(&mut self, enable: bool) -> &mut Self {
@@ -240,19 +232,13 @@ impl Config {
         self
     }
 
-    /// Configures whether the WebAssembly bulk memory operations proposal will
+    /// Configures whether the [WebAssembly bulk memory operations
-    /// be enabled for compilation.
+    /// proposal][proposal] will be enabled for compilation.
-    ///
-    /// The [WebAssembly bulk memory operations proposal][proposal] is not
-    /// currently fully standardized and is undergoing development.
-    /// Additionally the support in wasmtime itself is still being worked on.
-    /// Support for this feature can be enabled through this method for
-    /// appropriate wasm modules.
     ///
     /// This feature gates items such as the `memory.copy` instruction, passive
     /// data/table segments, etc, being in a module.
     ///
-    /// This is `false` by default.
+    /// This is `true` by default.
     ///
     /// [proposal]: https://github.com/webassembly/bulk-memory-operations
     pub fn wasm_bulk_memory(&mut self, enable: bool) -> &mut Self {

docs/SUMMARY.md

@@ -5,26 +5,26 @@
   - [Creating `hello-world.wasm`](./tutorial-create-hello-world.md)
   - [Running `hello-world.wasm`](./tutorial-run-hello-world.md)
 - [Examples](./examples.md)
-  - [Markdown parser](./examples-markdown.md)
+  - [Markdown Parser](./examples-markdown.md)
   - [Profiling WebAssembly](./examples-profiling.md)
     - [Profiling with Perf](./examples-profiling-perf.md)
     - [Profiling with VTune](./examples-profiling-vtune.md)
   - [Embedding in Rust](./examples-rust-embed.md)
     - [Hello, world!](./examples-rust-hello-world.md)
     - [Calculating the GCD](./examples-rust-gcd.md)
-    - [Using linear memory](./examples-rust-memory.md)
+    - [Using Linear Memory](./examples-rust-memory.md)
     - [WASI](./examples-rust-wasi.md)
-    - [Linking modules](./examples-rust-linking.md)
+    - [Linking Modules](./examples-rust-linking.md)
     - [Debugging](./examples-rust-debugging.md)
-    - [Using multi-value](./examples-rust-multi-value.md)
+    - [Using Multi-Value](./examples-rust-multi-value.md)
   - [Embedding in C](./examples-c-embed.md)
-    - [Hello, world!](./examples-c-hello-world.md)
+    - [Hello, World!](./examples-c-hello-world.md)
     - [Calculating the GCD](./examples-c-gcd.md)
-    - [Using linear memory](./examples-c-memory.md)
+    - [Using Linear Memory](./examples-c-memory.md)
     - [WASI](./examples-c-wasi.md)
-    - [Linking modules](./examples-c-linking.md)
+    - [Linking Modules](./examples-c-linking.md)
     - [Debugging](./examples-c-debugging.md)
-    - [Using multi-value](./examples-c-multi-value.md)
+    - [Using Multi-Value](./examples-c-multi-value.md)
 - [Using WebAssembly from your language](./lang.md)
   - [Rust](./lang-rust.md)
   - [C](./lang-c.md)
@@ -45,6 +45,7 @@
 - [Stability](stability.md)
   - [Release Process](./stability-release.md)
   - [Platform Support](./stability-platform-support.md)
+  - [Wasm Proposals Support](./stability-wasm-proposals-support.md)
 - [Security](security.md)
   - [Disclosure Policy](./security-disclosure.md)
   - [Sandboxing](./security-sandboxing.md)
@@ -53,8 +54,9 @@
   - [Testing](./contributing-testing.md)
   - [Fuzzing](./contributing-fuzzing.md)
   - [CI](./contributing-ci.md)
-  - [Coding guidelines](./contributing-coding-guidelines.md)
+  - [Coding Guidelines](./contributing-coding-guidelines.md)
-  - [Development process](./contributing-development-process.md)
+  - [Development Process](./contributing-development-process.md)
   - [Release Process](./contributing-release-process.md)
+  - [Implementing Wasm Proposals](./contributing-implementing-wasm-proposals.md)
   - [Governance](./contributing-governance.md)
   - [Code of Conduct](./contributing-coc.md)

docs/contributing-coding-guidelines.md

@@ -6,7 +6,7 @@ be aware of.
 
 [pull request]: https://help.github.com/articles/about-pull-requests/
 
-### rustfmt
+### `rustfmt`
 
 All PRs must be formatted according to rustfmt, and this is checked in the
 continuous integration tests. You can format code locally with:
@@ -19,7 +19,7 @@ at the root of the repository. You can find [more information about rustfmt
 online](https://github.com/rust-lang/rustfmt) too, such as how to configure
 your editor.
 
-### Rustc version support
+### Minimum Supported `rustc` Version
 
 Wasmtime supports the current stable version of Rust.
 

docs/contributing-implementing-wasm-proposals.md

@@ -0,0 +1,118 @@
+# Implementing WebAssembly Proposals
+
+## Adding New Support for a Wasm Proposal
+
+The following checkboxes enumerate the steps required to add support for a new
+WebAssembly proposal to Wasmtime. They can be completed over the course of
+multiple pull requests.
+
+* <input type="checkbox"/> Add support to the
+  [`wasmparser`](https://github.com/bytecodealliance/wasm-tools/tree/main/crates/wasmparser)
+  crate.
+
+* <input type="checkbox"/> Add support to the
+  [`wat`](https://github.com/bytecodealliance/wasm-tools/tree/main/crates/wat)
+  and
+  [`wast`](https://github.com/bytecodealliance/wasm-tools/tree/main/crates/wast)
+  crates.
+
+* <input type="checkbox"/> Add support to the
+  [`wasmprinter`](https://github.com/bytecodealliance/wasm-tools/tree/main/crates/wasmprinter)
+  crate.
+
+* <input type="checkbox"/> Add a `wasmtime::Config::enable_foo_bar` method to
+  the `wasmtime` crate.
+
+* <input type="checkbox"/> Add a `--enable-foo-bar` command line flag to the
+  `wasmtime` binary.
+
+* <input type="checkbox"/> Enable the spec tests in
+  [`build.rs`](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/build.rs#L41-L52)
+  but [mark them as
+  ignored](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/build.rs#L196)
+  for now.
+
+* <input type="checkbox"/> Stop ignoring individual spec tests and get them
+  passing one by one.
+
+* <input type="checkbox"/> Enable the proposal in [the fuzz
+  targets](./contributing-fuzzing.html).
+
+  * <input type="checkbox"/> Add examples from the spec tests to [the relevant
+    corpora](https://github.com/bytecodealliance/wasmtime-libfuzzer-corpus).
+
+    > The `wast2json` tool from [WABT] is useful for this.
+
+  * <input type="checkbox"/> Write a custom fuzz target, oracle, and/or test
+    case generator for fuzzing this proposal in particular.
+
+    > For example, we wrote a [custom
+    > generator](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/crates/fuzzing/src/generators/table_ops.rs),
+    > [oracle](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/crates/fuzzing/src/oracles.rs#L417-L467),
+    > and [fuzz
+    > target](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/fuzz/fuzz_targets/table_ops.rs)
+    > for exercising `table.{get,set}` instructions and their interaction with
+    > GC while implementing the reference types proposal.
+
+* <input type="checkbox"/> Expose the proposal's new functionality in the
+  `wasmtime` crate's API.
+
+  > For example, the bulk memory operations proposal introduced a `table.copy`
+  > instruction, and we exposed its functionality as the `wasmtime::Table::copy`
+  > method.
+
+* <input type="checkbox"/> Expose the proposal's new functionality in the C API.
+
+  > This may require extensions to the standard C API, and if so, should be
+  > defined in
+  > [`wasmtime.h`](https://github.com/bytecodealliance/wasmtime/blob/c7cd70fcec3eee66c9d7b5aa6fb4580d5a802218/crates/c-api/include/wasmtime.h)
+  > and prefixed with `wasmtime_`.
+
+* <input type="checkbox"/> Use the C API to expose the proposal's new
+  functionality in the other language embedding APIs:
+
+  * <input type="checkbox"/> [Python](https://github.com/bytecodealliance/wasmtime-py/)
+
+  * <input type="checkbox"/> [Go](https://github.com/bytecodealliance/wasmtime-go/)
+
+  * <input type="checkbox"/> [.NET](https://github.com/bytecodealliance/wasmtime-dotnet/)
+
+* <input type="checkbox"/> Document support for the proposal in
+  `wasmtime/docs/stability-wasm-proposals-support.md`.
+
+## Enabling Support for a Proposal by Default
+
+These are the standards that must be met to enable support for a proposal by
+default in Wasmtime, and can be used as a review checklist.
+
+* <input type="checkbox"/> The proposal must be in phase 4, or greater, of [the
+  WebAssembly standardization process][phases].
+
+* <input type="checkbox"/> All spec tests must be passing in Wasmtime.
+
+* <input type="checkbox"/> No open questions, design concerns, or serious known
+  bugs.
+
+* <input type="checkbox"/> Has been fuzzed for at least a week minimum.
+
+* <input type="checkbox"/> We are confident that the fuzzers are fully
+  exercising the proposal's functionality.
+
+  > For example, it would *not* have been enough to simply enable reference
+  > types in the `compile` fuzz target to enable that proposal by
+  > default. Compiling a module that uses reference types but not instantiating
+  > it nor running any of its functions doesn't exercise any of the GC
+  > implementation and does not run the inline fast paths for `table` operations
+  > emitted by the JIT. Exercising these things was the motivation for writing
+  > the custom fuzz target for `table.{get,set}` instructions.
+
+* <input type="checkbox"/> The proposal's functionality is exposed in the
+  `wasmtime` crate's API.
+
+* <input type="checkbox"/> The proposal's functionality is exposed in the C API.
+
+* <input type="checkbox"/> The proposal's functionality is exposed in at least
+  one of the other languages' APIs.
+
+[phases]: https://github.com/WebAssembly/meetings/blob/master/process/phases.md
+[WABT]: https://github.com/WebAssembly/wabt/

docs/stability-wasm-proposals-support.md

@@ -0,0 +1,34 @@
+# WebAssembly Proposals Support
+
+The following table summarizes Wasmtime's support for WebAssembly proposals as
+well as the command line flag and [`wasmtime::Config`][config] method you can
+use to enable or disable support for a proposal.
+
+If a proposal is not listed, then it is not supported by Wasmtime.
+
+Wasmtime will never enable a proposal by default unless it has reached phase 4
+of [the WebAssembly standardizations process][phases] and its implementation in
+Wasmtime has been [thoroughly
+vetted](./contributing-supporting-new-wasm-proposals.html).
+
+| WebAssembly Proposal                        | Supported in Wasmtime?           | Command Line Flag      | [`Config`][config] Method |
+|---------------------------------------------|----------------------------------|------------------------|---------------------------|
+| **[Import and Export Mutable Globals]**     | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Sign-Extension Operations]**             | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Non-Trapping Float-to-Int Conversions]** | **Yes.**<br/>Always enabled.     | (none)                 | (none)                    |
+| **[Multi-Value]**                           | **Yes.**<br/>Enabled by default. | `--enable-multi-value` | [`wasm_multi_value`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_multi_value) |
+| **[Bulk Memory Operations]**                | **Yes.**<br/>Enabled by default. | `--enable-bulk-memory` | [`wasm_bulk_memory`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_bulk_memory) |
+| **[Reference Types]**                       | **Yes.**<br/>Enabled by default on x86_64. Aarch64 support in progress. | `--enable-reference-types` | [`wasm_reference_types`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_reference_types) |
+| **[Fixed-Width SIMD]**                      | **In progress.**                 | `--enable-simd`        | [`wasm_simd`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_simd) |
+| **[Threads and Atomics]**                   | **In progress.**                 | `--enable-threads`     | [`wasm_threads`](https://docs.rs/wasmtime/*/wasmtime/struct.Config.html#method.wasm_threads) |
+
+[config]: https://docs.rs/wasmtime/*/wasmtime/struct.Config.html
+[Multi-Value]: https://github.com/WebAssembly/spec/blob/master/proposals/multi-value/Overview.md
+[Bulk Memory Operations]: https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
+[Import and Export Mutable Globals]: https://github.com/WebAssembly/mutable-global/blob/master/proposals/mutable-global/Overview.md
+[Reference Types]: https://github.com/WebAssembly/reference-types/blob/master/proposals/reference-types/Overview.md
+[Non-Trapping Float-to-Int Conversions]: https://github.com/WebAssembly/spec/blob/master/proposals/nontrapping-float-to-int-conversion/Overview.md
+[Sign-Extension Operations]: https://github.com/WebAssembly/spec/blob/master/proposals/sign-extension-ops/Overview.md
+[Fixed-Width SIMD]: https://github.com/WebAssembly/simd/blob/master/proposals/simd/SIMD.md
+[phases]: https://github.com/WebAssembly/meetings/blob/master/process/phases.md
+[Threads and Atomics]: https://github.com/WebAssembly/threads/blob/master/proposals/threads/Overview.md

src/lib.rs

@@ -110,7 +110,7 @@ struct CommonOptions {
 
     /// Enable support for reference types
     #[structopt(long)]
-    enable_reference_types: bool,
+    enable_reference_types: Option<bool>,
 
     /// Enable support for multi-value functions
     #[structopt(long)]
@@ -122,7 +122,7 @@ struct CommonOptions {
 
     /// Enable support for bulk memory instructions
     #[structopt(long)]
-    enable_bulk_memory: bool,
+    enable_bulk_memory: Option<bool>,
 
     /// Enable all experimental Wasm features
     #[structopt(long)]
@@ -185,9 +185,13 @@ impl CommonOptions {
         config
             .cranelift_debug_verifier(self.enable_cranelift_debug_verifier)
             .debug_info(self.debug_info)
-            .wasm_bulk_memory(self.enable_bulk_memory || self.enable_all)
             .wasm_simd(self.enable_simd || self.enable_all)
-            .wasm_reference_types(self.enable_reference_types || self.enable_all)
+            .wasm_bulk_memory(self.enable_bulk_memory.unwrap_or(true) || self.enable_all)
+            .wasm_reference_types(
+                self.enable_reference_types
+                    .unwrap_or(cfg!(target_arch = "x86_64"))
+                    || self.enable_all,
+            )
             .wasm_multi_value(self.enable_multi_value.unwrap_or(true) || self.enable_all)
             .wasm_threads(self.enable_threads || self.enable_all)
             .cranelift_opt_level(self.opt_level())