Support optimizing feature checks at compile time (#1733)

* Support optimizing feature checks at compile time

Something I've long wanted for `wasmparser` is the ability to
constant-propagate decisions about feature selection instead of
requiring runtime checks to do so. This should be a performance win for
proposals as they become standardized and more and more of wasm is gated
behind some feature or another. The goal with this is to enable a mode
of `wasmparser` which doesn't require runtime checks of booleans/bits to
see whether a proposal is enabled or not.

In lieu of not redesigning everything too much (e.g. adding `F:
WasmFeatures` everywhere) this commit adds a new compile time Cargo
feature to the crate called `features` which, when disabled, makes
`WasmFeatures` a zero-sized type that represent the default active
features for `wasmparser`. This enables const-propagating decisions
about features throughout the codebase and should help optimize the
validator/decoder in niche situations.

* Add required feature

* Update crates/wasmparser/src/features.rs

Co-authored-by: Nick Fitzgerald <[email protected]>

---------

Co-authored-by: Nick Fitzgerald <[email protected]>

Author: alexcrichton

.github/workflows/main.yml

@@ -233,6 +233,8 @@ jobs:
       - run: cargo check --no-default-features -p wasmparser --target x86_64-unknown-none --features validate,serde,no-hash-maps
       - run: cargo check --no-default-features -p wasmparser --features std
       - run: cargo check --no-default-features -p wasmparser --features validate
+      - run: cargo check --no-default-features -p wasmparser --features features
+      - run: cargo check --no-default-features -p wasmparser --features features,validate
       - run: cargo check --no-default-features -p wasmparser --features no-hash-maps
       - run: cargo check --no-default-features -p wasmparser --features serde
       - run: cargo check --no-default-features -p wasmparser --features serde,no-hash-maps

Cargo.toml

@@ -122,7 +122,7 @@ wat = { workspace = true, features = ['dwarf'] }
 termcolor = { workspace = true }
 
 # Dependencies of `validate`
-wasmparser = { workspace = true, optional = true, features = ['validate'] }
+wasmparser = { workspace = true, optional = true }
 rayon = { workspace = true, optional = true }
 bitflags = { workspace = true, optional = true }
 
@@ -211,7 +211,15 @@ default = [
 ]
 
 # Each subcommand is gated behind a feature and lists the dependencies it needs
-validate = ['dep:wasmparser', 'rayon', 'dep:addr2line', 'dep:gimli', 'dep:bitflags']
+validate = [
+  'dep:wasmparser',
+  'rayon',
+  'dep:addr2line',
+  'dep:gimli',
+  'dep:bitflags',
+  'wasmparser/validate',
+  'wasmparser/features',
+]
 print = []
 parse = []
 smith = ['wasm-smith', 'arbitrary', 'dep:serde', 'dep:serde_derive', 'dep:serde_json']

crates/wasm-compose/src/graph.rs

@@ -17,7 +17,7 @@ use wasmparser::{
         ResourceId, SubtypeCx, Types, TypesRef,
     },
     Chunk, ComponentExternalKind, ComponentTypeRef, Encoding, Parser, Payload, ValidPayload,
-    Validator, WasmFeatures,
+    Validator,
 };
 
 pub(crate) fn type_desc(item: ComponentEntityType) -> &'static str {
@@ -98,8 +98,7 @@ impl<'a> Component<'a> {
     fn parse(name: String, path: Option<PathBuf>, bytes: Cow<'a, [u8]>) -> Result<Self> {
         let mut parser = Parser::new(0);
         let mut parsers = Vec::new();
-        let mut validator =
-            Validator::new_with_features(WasmFeatures::default() | WasmFeatures::COMPONENT_MODEL);
+        let mut validator = Validator::new();
         let mut imports = IndexMap::new();
         let mut exports = IndexMap::new();
 
@@ -990,7 +989,7 @@ impl<'a> CompositionGraph<'a> {
         let bytes = CompositionGraphEncoder::new(options, self).encode()?;
 
         if options.validate {
-            Validator::new_with_features(WasmFeatures::default() | WasmFeatures::COMPONENT_MODEL)
+            Validator::new()
                 .validate_all(&bytes)
                 .context("failed to validate encoded graph bytes")?;
         }

crates/wasm-encoder/src/core/code.rs

@@ -83,12 +83,12 @@ impl CodeSection {
     /// into a new code section encoder:
     ///
     /// ```
-    /// # use wasmparser::{BinaryReader, WasmFeatures, CodeSectionReader};
+    /// # use wasmparser::{BinaryReader, CodeSectionReader};
     /// //                  id, size, # entries, entry
     /// let code_section = [10, 6,    1,         4, 0, 65, 0, 11];
     ///
     /// // Parse the code section.
-    /// let reader = BinaryReader::new(&code_section, 0, WasmFeatures::all());
+    /// let reader = BinaryReader::new(&code_section, 0);
     /// let reader = CodeSectionReader::new(reader).unwrap();
     /// let body = reader.into_iter().next().unwrap().unwrap();
     /// let body_range = body.range();

crates/wasm-metadata/src/lib.rs

@@ -10,7 +10,7 @@ use std::ops::Range;
 use wasm_encoder::{ComponentSection as _, ComponentSectionId, Encode, Section};
 use wasmparser::{
     BinaryReader, ComponentNameSectionReader, KnownCustom, NameSectionReader, Parser, Payload::*,
-    ProducersSectionReader, WasmFeatures,
+    ProducersSectionReader,
 };
 
 /// A representation of a WebAssembly producers section.
@@ -64,7 +64,7 @@ impl Producers {
     }
     /// Read the producers section from a Wasm binary.
     pub fn from_bytes(bytes: &[u8], offset: usize) -> Result<Self> {
-        let reader = BinaryReader::new(bytes, offset, WasmFeatures::all());
+        let reader = BinaryReader::new(bytes, offset);
         let section = ProducersSectionReader::new(reader)?;
         let mut fields = IndexMap::new();
         for field in section.into_iter() {
@@ -604,7 +604,7 @@ impl<'a> ModuleNames<'a> {
     /// Read a name section from a WebAssembly binary. Records the module name, and all other
     /// contents of name section, for later serialization.
     pub fn from_bytes(bytes: &'a [u8], offset: usize) -> Result<ModuleNames<'a>> {
-        let reader = BinaryReader::new(bytes, offset, WasmFeatures::all());
+        let reader = BinaryReader::new(bytes, offset);
         let section = NameSectionReader::new(reader);
         let mut s = Self::empty();
         for name in section.into_iter() {
@@ -690,7 +690,7 @@ impl<'a> ComponentNames<'a> {
     /// Read a component-name section from a WebAssembly binary. Records the component name, as
     /// well as all other component name fields for later serialization.
     pub fn from_bytes(bytes: &'a [u8], offset: usize) -> Result<ComponentNames<'a>> {
-        let reader = BinaryReader::new(bytes, offset, WasmFeatures::all());
+        let reader = BinaryReader::new(bytes, offset);
         let section = ComponentNameSectionReader::new(reader);
         let mut s = Self::empty();
         for name in section.into_iter() {

crates/wasm-mutate/src/info.rs

@@ -5,7 +5,7 @@ use crate::{
 use std::collections::HashSet;
 use std::ops::Range;
 use wasm_encoder::{RawSection, SectionId};
-use wasmparser::{BinaryReader, Chunk, Parser, Payload, WasmFeatures};
+use wasmparser::{BinaryReader, Chunk, Parser, Payload};
 
 /// Provides module information for future usage during mutation
 /// an instance of ModuleInfo could be user to determine which mutation could be applied
@@ -220,7 +220,7 @@ impl<'a> ModuleInfo<'a> {
     pub fn has_nonempty_code(&self) -> bool {
         if let Some(section) = self.code {
             let section_data = self.raw_sections[section].data;
-            let reader = BinaryReader::new(section_data, 0, WasmFeatures::all());
+            let reader = BinaryReader::new(section_data, 0);
             wasmparser::CodeSectionReader::new(reader)
                 .map(|r| r.count() != 0)
                 .unwrap_or(false)
@@ -253,7 +253,7 @@ impl<'a> ModuleInfo<'a> {
     }
 
     pub fn get_binary_reader(&self, i: usize) -> wasmparser::BinaryReader<'a> {
-        BinaryReader::new(self.raw_sections[i].data, 0, WasmFeatures::all())
+        BinaryReader::new(self.raw_sections[i].data, 0)
     }
 
     pub fn has_exports(&self) -> bool {

crates/wasm-mutate/src/mutators/remove_section.rs

@@ -16,7 +16,7 @@ pub enum RemoveSection {
 
 fn is_empty_section(section: &wasm_encoder::RawSection) -> bool {
     use wasmparser::*;
-    let reader = BinaryReader::new(section.data, 0, WasmFeatures::all());
+    let reader = BinaryReader::new(section.data, 0);
     crate::module::match_section_id! {
         match section.id;
         Custom => Ok(section.data.is_empty()),

crates/wasm-shrink/Cargo.toml

@@ -21,7 +21,7 @@ log = { workspace = true }
 rand = { workspace = true }
 clap = { workspace = true, optional = true }
 wasm-mutate = { workspace = true }
-wasmparser = { workspace = true, features = ['validate'] }
+wasmparser = { workspace = true, features = ['validate', 'features'] }
 
 [dev-dependencies]
 env_logger = { workspace = true }

crates/wasm-shrink/src/lib.rs

@@ -3,10 +3,9 @@
 //!
 //! See the [`WasmShrink`] type for details.
 
-use std::collections::HashSet;
-
 use anyhow::{Context, Result};
 use rand::{rngs::SmallRng, Rng, SeedableRng};
+use std::collections::HashSet;
 use wasm_mutate::WasmMutate;
 use wasmparser::WasmFeatures;
 
@@ -217,25 +216,7 @@ impl ShrinkRun {
     }
 
     fn validate_wasm(&self, wasm: &[u8]) -> Result<()> {
-        let mut validator = wasmparser::Validator::new_with_features(
-            WasmFeatures::REFERENCE_TYPES
-                | WasmFeatures::MULTI_VALUE
-                | WasmFeatures::BULK_MEMORY
-                | WasmFeatures::SIMD
-                | WasmFeatures::THREADS
-                | WasmFeatures::TAIL_CALL
-                | WasmFeatures::MULTI_MEMORY
-                | WasmFeatures::EXCEPTIONS
-                | WasmFeatures::MEMORY64
-                | WasmFeatures::RELAXED_SIMD
-                | WasmFeatures::EXTENDED_CONST
-                | WasmFeatures::MUTABLE_GLOBAL
-                | WasmFeatures::SATURATING_FLOAT_TO_INT
-                | WasmFeatures::SIGN_EXTENSION
-                | WasmFeatures::FLOATS
-                | WasmFeatures::MEMORY_CONTROL,
-        );
-
+        let mut validator = wasmparser::Validator::new_with_features(WasmFeatures::all());
         validator.validate_all(wasm)?;
         Ok(())
     }

crates/wasm-smith/Cargo.toml

@@ -35,7 +35,7 @@ wat = { workspace = true, optional = true }
 [dev-dependencies]
 criterion = { workspace = true }
 rand = { workspace = true }
-wasmparser = { workspace = true, features = ["validate"] }
+wasmparser = { workspace = true, features = ["validate", "features"] }
 wasmprinter = { path = "../wasmprinter" }
 wat = { path = "../wat" }