Exception and control tags (#10251)

* Tags

* Tag tests

* Tests

* Refer to tags issue

* Engine index

* Simplify

* Fix clippy warnings

Author: dhil

crates/c-api/src/extern.rs

@@ -23,6 +23,7 @@ pub extern "C" fn wasm_extern_kind(e: &wasm_extern_t) -> wasm_externkind_t {
         Extern::SharedMemory(_) => panic!(
             "Shared Memory no implemented for wasm_* types. Please use wasmtime_* types instead"
         ),
+        Extern::Tag(_) => todo!(), // FIXME: #10252 C embedder API for exceptions and control tags.
     }
 }
 
@@ -143,6 +144,7 @@ impl From<Extern> for wasmtime_extern_t {
                     sharedmemory: ManuallyDrop::new(Box::new(sharedmemory)),
                 },
             },
+            Extern::Tag(_) => todo!(), // FIXME: #10252 C embedder API for exceptions and control tags.
         }
     }
 }

crates/c-api/src/types/extern.rs

@@ -25,6 +25,7 @@ impl CExternType {
             ExternType::Global(f) => CExternType::Global(CGlobalType::new(f)),
             ExternType::Memory(f) => CExternType::Memory(CMemoryType::new(f)),
             ExternType::Table(f) => CExternType::Table(CTableType::new(f)),
+            ExternType::Tag(_) => todo!(), // FIXME: #10252 C embedder API for exceptions and control tags.
         }
     }
 }

crates/environ/src/compile/module_environ.rs

@@ -7,8 +7,8 @@ use crate::{
     ConstExpr, ConstOp, DataIndex, DefinedFuncIndex, ElemIndex, EngineOrModuleTypeIndex,
     EntityIndex, EntityType, FuncIndex, GlobalIndex, IndexType, InitMemory, MemoryIndex,
     ModuleInternedTypeIndex, ModuleTypesBuilder, PrimaryMap, SizeOverflow, StaticMemoryInitializer,
-    TableIndex, TableInitialValue, Tunables, TypeConvert, TypeIndex, Unsigned, WasmError,
-    WasmHeapTopType, WasmHeapType, WasmResult, WasmValType, WasmparserTypeConverter,
+    TableIndex, TableInitialValue, Tag, TagIndex, Tunables, TypeConvert, TypeIndex, Unsigned,
+    WasmError, WasmHeapTopType, WasmHeapType, WasmResult, WasmValType, WasmparserTypeConverter,
 };
 use anyhow::{bail, Result};
 use cranelift_entity::packed_option::ReservedValue;
@@ -318,9 +318,13 @@ impl<'a, 'data> ModuleEnvironment<'a, 'data> {
                             self.result.module.num_imported_tables += 1;
                             EntityType::Table(self.convert_table_type(&ty)?)
                         }
-
-                        // doesn't get past validation
-                        TypeRef::Tag(_) => unreachable!(),
+                        TypeRef::Tag(ty) => {
+                            let index = TypeIndex::from_u32(ty.func_type_idx);
+                            let signature = self.result.module.types[index];
+                            let tag = Tag { signature };
+                            self.result.module.num_imported_tags += 1;
+                            EntityType::Tag(tag)
+                        }
                     };
                     self.declare_import(import.module, import.name, ty);
                 }
@@ -384,9 +388,12 @@ impl<'a, 'data> ModuleEnvironment<'a, 'data> {
             Payload::TagSection(tags) => {
                 self.validator.tag_section(&tags)?;
 
-                // This feature isn't enabled at this time, so we should
-                // never get here.
-                unreachable!();
+                for entry in tags {
+                    let sigindex = entry?.func_type_idx;
+                    let ty = TypeIndex::from_u32(sigindex);
+                    let interned_index = self.result.module.types[ty];
+                    self.result.module.push_tag(interned_index);
+                }
             }
 
             Payload::GlobalSection(globals) => {
@@ -424,9 +431,7 @@ impl<'a, 'data> ModuleEnvironment<'a, 'data> {
                         ExternalKind::Table => EntityIndex::Table(TableIndex::from_u32(index)),
                         ExternalKind::Memory => EntityIndex::Memory(MemoryIndex::from_u32(index)),
                         ExternalKind::Global => EntityIndex::Global(GlobalIndex::from_u32(index)),
-
-                        // this never gets past validation
-                        ExternalKind::Tag => unreachable!(),
+                        ExternalKind::Tag => EntityIndex::Tag(TagIndex::from_u32(index)),
                     };
                     self.result
                         .module
@@ -770,7 +775,7 @@ and for re-adding support for interface types you can see this issue:
             EntityType::Table(ty) => EntityIndex::Table(self.result.module.tables.push(ty)),
             EntityType::Memory(ty) => EntityIndex::Memory(self.result.module.memories.push(ty)),
             EntityType::Global(ty) => EntityIndex::Global(self.result.module.globals.push(ty)),
-            EntityType::Tag(_) => unimplemented!(),
+            EntityType::Tag(ty) => EntityIndex::Tag(self.result.module.tags.push(ty)),
         }
     }
 

crates/environ/src/component/translate/inline.rs

@@ -1229,6 +1229,7 @@ impl<'a> Inliner<'a> {
                 EntityIndex::Table(i) => frame.tables[i].clone().into(),
                 EntityIndex::Global(i) => frame.globals[i].clone().into(),
                 EntityIndex::Memory(i) => frame.memories[i].clone().into(),
+                EntityIndex::Tag(_) => todo!(), // FIXME: #10252 support for tags in the component model
             },
         }
     }

crates/environ/src/module.rs

@@ -333,6 +333,9 @@ pub struct Module {
     /// Number of imported or aliased globals in the module.
     pub num_imported_globals: usize,
 
+    /// Number of imported or aliased tags in the module.
+    pub num_imported_tags: usize,
+
     /// Number of functions that "escape" from this module may need to have a
     /// `VMFuncRef` constructed for them.
     ///
@@ -354,6 +357,9 @@ pub struct Module {
 
     /// WebAssembly global initializers for locally-defined globals.
     pub global_initializers: PrimaryMap<DefinedGlobalIndex, ConstExpr>,
+
+    /// WebAssembly exception and control tags.
+    pub tags: PrimaryMap<TagIndex, Tag>,
 }
 
 /// Initialization routines for creating an instance, encompassing imports,
@@ -500,6 +506,29 @@ impl Module {
         index.index() < self.num_imported_globals
     }
 
+    /// Test whether the given tag index is for an imported tag.
+    #[inline]
+    pub fn is_imported_tag(&self, index: TagIndex) -> bool {
+        index.index() < self.num_imported_tags
+    }
+
+    /// Convert a `DefinedTagIndex` into a `TagIndex`.
+    #[inline]
+    pub fn tag_index(&self, defined_tag: DefinedTagIndex) -> TagIndex {
+        TagIndex::new(self.num_imported_tags + defined_tag.index())
+    }
+
+    /// Convert a `TagIndex` into a `DefinedTagIndex`. Returns None if the
+    /// index is an imported tag.
+    #[inline]
+    pub fn defined_tag_index(&self, tag: TagIndex) -> Option<DefinedTagIndex> {
+        if tag.index() < self.num_imported_tags {
+            None
+        } else {
+            Some(DefinedTagIndex::new(tag.index() - self.num_imported_tags))
+        }
+    }
+
     /// Returns an iterator of all the imports in this module, along with their
     /// module name, field name, and type that's being imported.
     pub fn imports(&self) -> impl ExactSizeIterator<Item = (&str, &str, EntityType)> {
@@ -517,9 +546,16 @@ impl Module {
             EntityIndex::Table(i) => EntityType::Table(self.tables[i]),
             EntityIndex::Memory(i) => EntityType::Memory(self.memories[i]),
             EntityIndex::Function(i) => EntityType::Function(self.functions[i].signature),
+            EntityIndex::Tag(i) => EntityType::Tag(self.tags[i]),
         }
     }
 
+    /// Appends a new tag to this module with the given type information.
+    pub fn push_tag(&mut self, signature: impl Into<EngineOrModuleTypeIndex>) -> TagIndex {
+        let signature = signature.into();
+        self.tags.push(Tag { signature })
+    }
+
     /// Appends a new function to this module with the given type information,
     /// used for functions that either don't escape or aren't certain whether
     /// they escape yet.
@@ -548,6 +584,12 @@ impl Module {
     pub fn num_defined_memories(&self) -> usize {
         self.memories.len() - self.num_imported_memories
     }
+
+    /// Returns the number of tags defined by this module itself: all tags
+    /// minus imported tags.
+    pub fn num_defined_tags(&self) -> usize {
+        self.tags.len() - self.num_imported_tags
+    }
 }
 
 impl TypeTrace for Module {
@@ -572,12 +614,14 @@ impl TypeTrace for Module {
             num_imported_tables: _,
             num_imported_memories: _,
             num_imported_globals: _,
+            num_imported_tags: _,
             num_escaped_funcs: _,
             functions,
             tables,
             memories: _,
             globals,
             global_initializers: _,
+            tags,
         } = self;
 
         for t in types.values().copied() {
@@ -592,6 +636,9 @@ impl TypeTrace for Module {
         for g in globals.values() {
             g.trace(func)?;
         }
+        for t in tags.values() {
+            t.trace(func)?;
+        }
         Ok(())
     }
 
@@ -616,12 +663,14 @@ impl TypeTrace for Module {
             num_imported_tables: _,
             num_imported_memories: _,
             num_imported_globals: _,
+            num_imported_tags: _,
             num_escaped_funcs: _,
             functions,
             tables,
             memories: _,
             globals,
             global_initializers: _,
+            tags,
         } = self;
 
         for t in types.values_mut() {
@@ -636,6 +685,9 @@ impl TypeTrace for Module {
         for g in globals.values_mut() {
             g.trace_mut(func)?;
         }
+        for t in tags.values_mut() {
+            t.trace_mut(func)?;
+        }
         Ok(())
     }
 }

crates/environ/src/types.rs

@@ -1315,6 +1315,11 @@ entity_impl!(DataIndex);
 pub struct ElemIndex(u32);
 entity_impl!(ElemIndex);
 
+/// Index type of a defined tag inside the WebAssembly module.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug, Serialize, Deserialize)]
+pub struct DefinedTagIndex(u32);
+entity_impl!(DefinedTagIndex);
+
 /// Index type of an event inside the WebAssembly module.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug, Serialize, Deserialize)]
 pub struct TagIndex(u32);
@@ -1339,6 +1344,8 @@ pub enum EntityIndex {
     Memory(MemoryIndex),
     /// Global index.
     Global(GlobalIndex),
+    /// Tag index.
+    Tag(TagIndex),
 }
 
 impl From<FuncIndex> for EntityIndex {
@@ -1365,6 +1372,12 @@ impl From<GlobalIndex> for EntityIndex {
     }
 }
 
+impl From<TagIndex> for EntityIndex {
+    fn from(idx: TagIndex) -> EntityIndex {
+        EntityIndex::Tag(idx)
+    }
+}
+
 /// A type of an item in a wasm module where an item is typically something that
 /// can be exported.
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -1373,7 +1386,7 @@ pub enum EntityType {
     Global(Global),
     /// A linear memory with the specified limits
     Memory(Memory),
-    /// An event definition.
+    /// An exception and control tag definition.
     Tag(Tag),
     /// A table with the specified element type and limits
     Table(Table),
@@ -1391,7 +1404,8 @@ impl TypeTrace for EntityType {
             Self::Global(g) => g.trace(func),
             Self::Table(t) => t.trace(func),
             Self::Function(idx) => func(*idx),
-            Self::Memory(_) | Self::Tag(_) => Ok(()),
+            Self::Memory(_) => Ok(()),
+            Self::Tag(t) => t.trace(func),
         }
     }
 
@@ -1403,7 +1417,8 @@ impl TypeTrace for EntityType {
             Self::Global(g) => g.trace_mut(func),
             Self::Table(t) => t.trace_mut(func),
             Self::Function(idx) => func(idx),
-            Self::Memory(_) | Self::Tag(_) => Ok(()),
+            Self::Memory(_) => Ok(()),
+            Self::Tag(t) => t.trace_mut(func),
         }
     }
 }
@@ -1933,20 +1948,26 @@ impl From<wasmparser::MemoryType> for Memory {
     }
 }
 
-/// WebAssembly event.
+/// WebAssembly exception and control tag.
 #[derive(Debug, Clone, Copy, Hash, Eq, PartialEq, Serialize, Deserialize)]
 pub struct Tag {
-    /// The event signature type.
-    pub ty: TypeIndex,
+    /// The tag signature type.
+    pub signature: EngineOrModuleTypeIndex,
 }
 
-impl From<wasmparser::TagType> for Tag {
-    fn from(ty: wasmparser::TagType) -> Tag {
-        match ty.kind {
-            wasmparser::TagKind::Exception => Tag {
-                ty: TypeIndex::from_u32(ty.func_type_idx),
-            },
-        }
+impl TypeTrace for Tag {
+    fn trace<F, E>(&self, func: &mut F) -> Result<(), E>
+    where
+        F: FnMut(EngineOrModuleTypeIndex) -> Result<(), E>,
+    {
+        func(self.signature)
+    }
+
+    fn trace_mut<F, E>(&mut self, func: &mut F) -> Result<(), E>
+    where
+        F: FnMut(&mut EngineOrModuleTypeIndex) -> Result<(), E>,
+    {
+        func(&mut self.signature)
     }
 }