Continuation types (#10255)

Author: dhil

crates/cranelift/src/func_environ.rs

@@ -1458,6 +1458,8 @@ impl<'a, 'func, 'module_env> Call<'a, 'func, 'module_env> {
                 return CheckIndirectCallTypeSignature::StaticTrap;
             }
 
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
+
             // Engine-indexed types don't show up until runtime and it's a Wasm
             // validation error to perform a call through a non-function table,
             // so these cases are dynamically not reachable.
@@ -1701,6 +1703,7 @@ impl<'module_environment> TargetEnvironment for FuncEnvironment<'module_environm
         let needs_stack_map = match wasm_ty.top() {
             WasmHeapTopType::Extern | WasmHeapTopType::Any => true,
             WasmHeapTopType::Func => false,
+            WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
         };
         (ty, needs_stack_map)
     }
@@ -1816,6 +1819,9 @@ impl FuncEnvironment<'_> {
             WasmHeapTopType::Func => {
                 Ok(self.get_or_init_func_ref_table_elem(builder, table_index, index, false))
             }
+
+            // Continuation types.
+            WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
         }
     }
 
@@ -1862,6 +1868,9 @@ impl FuncEnvironment<'_> {
                     .store(flags, value_with_init_bit, elem_addr, 0);
                 Ok(())
             }
+
+            // Continuation types.
+            WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
         }
     }
 
@@ -2213,6 +2222,7 @@ impl FuncEnvironment<'_> {
             WasmHeapTopType::Func => pos.ins().iconst(self.pointer_type(), 0),
             // NB: null GC references don't need to be in stack maps.
             WasmHeapTopType::Any | WasmHeapTopType::Extern => pos.ins().iconst(types::I32, 0),
+            WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
         })
     }
 

crates/cranelift/src/gc/enabled.rs

@@ -148,6 +148,7 @@ fn read_field_at_addr(
                         .call(get_interned_func_ref, &[vmctx, func_ref_id, expected_ty]);
                     builder.func.dfg.first_result(call_inst)
                 }
+                WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
             },
         },
     };
@@ -1059,6 +1060,8 @@ pub fn translate_ref_test(
 
             func_env.is_subtype(builder, actual_shared_ty, expected_shared_ty)
         }
+
+        WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
     };
     builder.ins().jump(continue_block, &[result]);
 
@@ -1391,6 +1394,8 @@ impl FuncEnvironment<'_> {
             WasmHeapType::Func | WasmHeapType::ConcreteFunc(_) | WasmHeapType::NoFunc => {
                 unreachable!()
             }
+
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
         };
 
         match (ty.nullable, might_be_i31) {

crates/cranelift/src/lib.rs

@@ -202,6 +202,7 @@ fn reference_type(wasm_ht: WasmHeapType, pointer_type: ir::Type) -> ir::Type {
     match wasm_ht.top() {
         WasmHeapTopType::Func => pointer_type,
         WasmHeapTopType::Any | WasmHeapTopType::Extern => ir::types::I32,
+        WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
     }
 }
 

crates/environ/src/compile/module_environ.rs

@@ -1220,7 +1220,7 @@ impl ModuleTranslation<'_> {
                 // initializer won't trap so we could continue processing
                 // segments, but that's left as a future optimization if
                 // necessary.
-                WasmHeapTopType::Any | WasmHeapTopType::Extern => break,
+                WasmHeapTopType::Any | WasmHeapTopType::Extern | WasmHeapTopType::Cont => break,
             }
 
             // Function indices can be optimized here, but fully general

crates/environ/src/compile/module_types.rs

@@ -438,6 +438,7 @@ where
                         WasmCompositeInnerType::Array(_) => WasmHeapType::ConcreteArray(index),
                         WasmCompositeInnerType::Func(_) => WasmHeapType::ConcreteFunc(index),
                         WasmCompositeInnerType::Struct(_) => WasmHeapType::ConcreteStruct(index),
+                        WasmCompositeInnerType::Cont(_) => WasmHeapType::ConcreteCont(index),
                     }
                 } else if let Some((wasmparser_types, _)) = self.rec_group_context.as_ref() {
                     let wasmparser_ty = &wasmparser_types[id].composite_type;
@@ -453,7 +454,7 @@ where
                             WasmHeapType::ConcreteStruct(index)
                         }
                         wasmparser::CompositeInnerType::Cont(_) => {
-                            panic!("unimplemented continuation types")
+                            WasmHeapType::ConcreteCont(index)
                         }
                     }
                 } else {
@@ -477,6 +478,7 @@ where
                         WasmCompositeInnerType::Array(_) => WasmHeapType::ConcreteArray(index),
                         WasmCompositeInnerType::Func(_) => WasmHeapType::ConcreteFunc(index),
                         WasmCompositeInnerType::Struct(_) => WasmHeapType::ConcreteStruct(index),
+                        WasmCompositeInnerType::Cont(_) => WasmHeapType::ConcreteCont(index),
                     }
                 } else if let Some((parser_types, rec_group)) = self.rec_group_context.as_ref() {
                     let rec_group_index = interned.index() - self.types.types.len_types();
@@ -497,7 +499,7 @@ where
                             WasmHeapType::ConcreteStruct(index)
                         }
                         wasmparser::CompositeInnerType::Cont(_) => {
-                            panic!("unimplemented continuation types")
+                            WasmHeapType::ConcreteCont(index)
                         }
                     }
                 } else {

crates/environ/src/gc.rs

@@ -162,6 +162,7 @@ pub trait GcTypeLayouts {
             WasmCompositeInnerType::Array(ty) => Some(self.array_layout(ty).into()),
             WasmCompositeInnerType::Struct(ty) => Some(self.struct_layout(ty).into()),
             WasmCompositeInnerType::Func(_) => None,
+            WasmCompositeInnerType::Cont(_) => None,
         }
     }
 

crates/environ/src/types.rs

@@ -436,6 +436,11 @@ pub enum WasmHeapType {
     ConcreteFunc(EngineOrModuleTypeIndex),
     NoFunc,
 
+    // Continuation types.
+    Cont,
+    ConcreteCont(EngineOrModuleTypeIndex),
+    NoCont,
+
     // Internal types.
     Any,
     Eq,
@@ -454,6 +459,7 @@ impl From<WasmHeapTopType> for WasmHeapType {
             WasmHeapTopType::Extern => Self::Extern,
             WasmHeapTopType::Any => Self::Any,
             WasmHeapTopType::Func => Self::Func,
+            WasmHeapTopType::Cont => Self::Cont,
         }
     }
 }
@@ -465,6 +471,7 @@ impl From<WasmHeapBottomType> for WasmHeapType {
             WasmHeapBottomType::NoExtern => Self::NoExtern,
             WasmHeapBottomType::None => Self::None,
             WasmHeapBottomType::NoFunc => Self::NoFunc,
+            WasmHeapBottomType::NoCont => Self::NoCont,
         }
     }
 }
@@ -477,6 +484,9 @@ impl fmt::Display for WasmHeapType {
             Self::Func => write!(f, "func"),
             Self::ConcreteFunc(i) => write!(f, "func {i}"),
             Self::NoFunc => write!(f, "nofunc"),
+            Self::Cont => write!(f, "cont"),
+            Self::ConcreteCont(i) => write!(f, "cont {i}"),
+            Self::NoCont => write!(f, "nocont"),
             Self::Any => write!(f, "any"),
             Self::Eq => write!(f, "eq"),
             Self::I31 => write!(f, "i31"),
@@ -498,6 +508,7 @@ impl TypeTrace for WasmHeapType {
             Self::ConcreteArray(i) => func(i),
             Self::ConcreteFunc(i) => func(i),
             Self::ConcreteStruct(i) => func(i),
+            Self::ConcreteCont(i) => func(i),
             _ => Ok(()),
         }
     }
@@ -510,6 +521,7 @@ impl TypeTrace for WasmHeapType {
             Self::ConcreteArray(i) => func(i),
             Self::ConcreteFunc(i) => func(i),
             Self::ConcreteStruct(i) => func(i),
+            Self::ConcreteCont(i) => func(i),
             _ => Ok(()),
         }
     }
@@ -526,6 +538,7 @@ impl WasmHeapType {
 
             // All `t <: (ref null func)` are not.
             WasmHeapTopType::Func => false,
+            WasmHeapTopType::Cont => false,
         }
     }
 
@@ -555,6 +568,10 @@ impl WasmHeapType {
                 WasmHeapTopType::Func
             }
 
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => {
+                WasmHeapTopType::Cont
+            }
+
             WasmHeapType::Any
             | WasmHeapType::Eq
             | WasmHeapType::I31
@@ -582,6 +599,10 @@ impl WasmHeapType {
                 WasmHeapBottomType::NoFunc
             }
 
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => {
+                WasmHeapBottomType::NoCont
+            }
+
             WasmHeapType::Any
             | WasmHeapType::Eq
             | WasmHeapType::I31
@@ -603,6 +624,8 @@ pub enum WasmHeapTopType {
     Any,
     /// The common supertype of all function references.
     Func,
+    /// The common supertype of all continuation references.
+    Cont,
 }
 
 /// A bottom heap type.
@@ -614,6 +637,8 @@ pub enum WasmHeapBottomType {
     None,
     /// The common subtype of all function references.
     NoFunc,
+    /// The common subtype of all continuation references.
+    NoCont,
 }
 
 /// WebAssembly function type -- equivalent of `wasmparser`'s FuncType.
@@ -761,6 +786,39 @@ impl WasmFuncType {
     }
 }
 
+/// WebAssembly continuation type -- equivalent of `wasmparser`'s ContType.
+#[derive(Debug, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
+pub struct WasmContType(EngineOrModuleTypeIndex);
+
+impl fmt::Display for WasmContType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "(cont {})", self.0)
+    }
+}
+
+impl WasmContType {
+    /// Constructs a new continuation type.
+    pub fn new(idx: EngineOrModuleTypeIndex) -> Self {
+        WasmContType(idx)
+    }
+}
+
+impl TypeTrace for WasmContType {
+    fn trace<F, E>(&self, func: &mut F) -> Result<(), E>
+    where
+        F: FnMut(EngineOrModuleTypeIndex) -> Result<(), E>,
+    {
+        func(self.0)
+    }
+
+    fn trace_mut<F, E>(&mut self, func: &mut F) -> Result<(), E>
+    where
+        F: FnMut(&mut EngineOrModuleTypeIndex) -> Result<(), E>,
+    {
+        func(&mut self.0)
+    }
+}
+
 /// Represents storage types introduced in the GC spec for array and struct fields.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
 pub enum WasmStorageType {
@@ -935,6 +993,7 @@ pub enum WasmCompositeInnerType {
     Array(WasmArrayType),
     Func(WasmFuncType),
     Struct(WasmStructType),
+    Cont(WasmContType),
 }
 
 impl fmt::Display for WasmCompositeInnerType {
@@ -943,6 +1002,7 @@ impl fmt::Display for WasmCompositeInnerType {
             Self::Array(ty) => fmt::Display::fmt(ty, f),
             Self::Func(ty) => fmt::Display::fmt(ty, f),
             Self::Struct(ty) => fmt::Display::fmt(ty, f),
+            Self::Cont(ty) => fmt::Display::fmt(ty, f),
         }
     }
 }
@@ -1002,6 +1062,24 @@ impl WasmCompositeInnerType {
     pub fn unwrap_struct(&self) -> &WasmStructType {
         self.as_struct().unwrap()
     }
+
+    #[inline]
+    pub fn is_cont(&self) -> bool {
+        matches!(self, Self::Cont(_))
+    }
+
+    #[inline]
+    pub fn as_cont(&self) -> Option<&WasmContType> {
+        match self {
+            Self::Cont(f) => Some(f),
+            _ => None,
+        }
+    }
+
+    #[inline]
+    pub fn unwrap_cont(&self) -> &WasmContType {
+        self.as_cont().unwrap()
+    }
 }
 
 impl TypeTrace for WasmCompositeType {
@@ -1013,6 +1091,7 @@ impl TypeTrace for WasmCompositeType {
             WasmCompositeInnerType::Array(a) => a.trace(func),
             WasmCompositeInnerType::Func(f) => f.trace(func),
             WasmCompositeInnerType::Struct(a) => a.trace(func),
+            WasmCompositeInnerType::Cont(c) => c.trace(func),
         }
     }
 
@@ -1024,6 +1103,7 @@ impl TypeTrace for WasmCompositeType {
             WasmCompositeInnerType::Array(a) => a.trace_mut(func),
             WasmCompositeInnerType::Func(f) => f.trace_mut(func),
             WasmCompositeInnerType::Struct(a) => a.trace_mut(func),
+            WasmCompositeInnerType::Cont(c) => c.trace_mut(func),
         }
     }
 }
@@ -1123,6 +1203,26 @@ impl WasmSubType {
         assert!(!self.composite_type.shared);
         self.composite_type.inner.unwrap_struct()
     }
+
+    #[inline]
+    pub fn is_cont(&self) -> bool {
+        self.composite_type.inner.is_cont() && !self.composite_type.shared
+    }
+
+    #[inline]
+    pub fn as_cont(&self) -> Option<&WasmContType> {
+        if self.composite_type.shared {
+            None
+        } else {
+            self.composite_type.inner.as_cont()
+        }
+    }
+
+    #[inline]
+    pub fn unwrap_cont(&self) -> &WasmContType {
+        assert!(!self.composite_type.shared);
+        self.composite_type.inner.unwrap_cont()
+    }
 }
 
 impl TypeTrace for WasmSubType {
@@ -2018,8 +2118,8 @@ pub trait TypeConvert {
             wasmparser::CompositeInnerType::Struct(s) => {
                 WasmCompositeInnerType::Struct(self.convert_struct_type(s))
             }
-            wasmparser::CompositeInnerType::Cont(_) => {
-                unimplemented!("continuation types")
+            wasmparser::CompositeInnerType::Cont(c) => {
+                WasmCompositeInnerType::Cont(self.convert_cont_type(c))
             }
         };
         WasmCompositeType {
@@ -2028,6 +2128,15 @@ pub trait TypeConvert {
         }
     }
 
+    /// Converts a wasmparser continuation type to a wasmtime type
+    fn convert_cont_type(&self, ty: &wasmparser::ContType) -> WasmContType {
+        if let WasmHeapType::ConcreteFunc(sigidx) = self.lookup_heap_type(ty.0.unpack()) {
+            WasmContType::new(sigidx)
+        } else {
+            panic!("Failed to extract signature index for continuation type.")
+        }
+    }
+
     fn convert_struct_type(&self, ty: &wasmparser::StructType) -> WasmStructType {
         WasmStructType {
             fields: ty

crates/wasmtime/src/runtime/type_registry.rs

@@ -851,6 +851,7 @@ impl TypeRegistryInner {
                     .struct_layout(s)
                     .into(),
             ),
+            wasmtime_environ::WasmCompositeInnerType::Cont(_) => todo!(), // FIXME: #10248 stack switching support.
         };
 
         // Add the type to our slab.

crates/wasmtime/src/runtime/types.rs

@@ -1096,6 +1096,8 @@ impl HeapType {
             | WasmHeapType::ConcreteStruct(EngineOrModuleTypeIndex::RecGroup(_)) => {
                 panic!("HeapType::from_wasm_type on non-canonicalized-for-runtime-usage heap type")
             }
+
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
         }
     }