wasmtime: Implement table.fill

Part of bytecodealliance#929

build.rs

@@ -200,11 +200,6 @@ fn ignore(testsuite: &str, testname: &str, strategy: &str) -> bool {
             ("simd", "simd_load") => return true, // FIXME Unsupported feature: proposed SIMD operator I32x4TruncSatF32x4S
             ("simd", "simd_splat") => return true, // FIXME Unsupported feature: proposed SIMD operator I32x4TruncSatF32x4S
 
-            // Still working on implementing these. See #929.
-            ("reference_types", "table_fill") => {
-                return true;
-            }
-
             // TODO(#1886): Ignore reference types tests if this isn't x64,
             // because Cranelift only supports reference types on x64.
             ("reference_types", _) => {

crates/environ/src/func_environ.rs

@@ -170,6 +170,10 @@ declare_builtin_functions! {
     table_grow_funcref(vmctx, i32, i32, pointer) -> (i32);
     /// Returns an index for Wasm's `table.grow` instruction for `externref`s.
     table_grow_externref(vmctx, i32, i32, reference) -> (i32);
+    /// Returns an index for Wasm's `table.fill` instruction for `externref`s.
+    table_fill_externref(vmctx, i32, i32, reference, i32) -> ();
+    /// Returns an index for Wasm's `table.fill` instruction for `funcref`s.
+    table_fill_funcref(vmctx, i32, i32, pointer, i32) -> ();
     /// Returns an index to drop a `VMExternRef`.
     drop_externref(pointer) -> ();
     /// Returns an index to do a GC and then insert a `VMExternRef` into the
@@ -1009,15 +1013,41 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
 
     fn translate_table_fill(
         &mut self,
-        _: cranelift_codegen::cursor::FuncCursor<'_>,
-        _: TableIndex,
-        _: ir::Value,
-        _: ir::Value,
-        _: ir::Value,
+        mut pos: cranelift_codegen::cursor::FuncCursor<'_>,
+        table_index: TableIndex,
+        dst: ir::Value,
+        val: ir::Value,
+        len: ir::Value,
     ) -> WasmResult<()> {
-        Err(WasmError::Unsupported(
-            "the `table.fill` instruction is not supported yet".into(),
-        ))
+        let (builtin_idx, builtin_sig) =
+            match self.module.table_plans[table_index].table.wasm_ty {
+                WasmType::FuncRef => (
+                    BuiltinFunctionIndex::table_fill_funcref(),
+                    self.builtin_function_signatures
+                        .table_fill_funcref(&mut pos.func),
+                ),
+                WasmType::ExternRef => (
+                    BuiltinFunctionIndex::table_fill_externref(),
+                    self.builtin_function_signatures
+                        .table_fill_externref(&mut pos.func),
+                ),
+                _ => return Err(WasmError::Unsupported(
+                    "`table.fill` with a table element type that is not `funcref` or `externref`"
+                        .into(),
+                )),
+            };
+
+        let (vmctx, builtin_addr) =
+            self.translate_load_builtin_function_address(&mut pos, builtin_idx);
+
+        let table_index_arg = pos.ins().iconst(I32, table_index.as_u32() as i64);
+        pos.ins().call_indirect(
+            builtin_sig,
+            builtin_addr,
+            &[vmctx, table_index_arg, dst, val, len],
+        );
+
+        Ok(())
     }
 
     fn translate_ref_null(

crates/runtime/src/libcalls.rs

@@ -265,6 +265,41 @@ pub unsafe extern "C" fn wasmtime_table_grow(
     }
 }
 
+/// Implementation of `table.fill`.
+pub unsafe extern "C" fn wasmtime_table_fill(
+    vmctx: *mut VMContext,
+    table_index: u32,
+    dst: u32,
+    // NB: we don't know whether this is a `VMExternRef` or a pointer to a
+    // `VMCallerCheckedAnyfunc` until we look at the table's element type.
+    val: *mut u8,
+    len: u32,
+) {
+    let result = {
+        let instance = (&mut *vmctx).instance();
+        let table_index = TableIndex::from_u32(table_index);
+        let table = instance.get_table(table_index);
+        match table.element_type() {
+            TableElementType::Func => {
+                let val = val as *mut VMCallerCheckedAnyfunc;
+                table.fill(dst, val.into(), len)
+            }
+            TableElementType::Val(ty) => {
+                debug_assert_eq!(ty, crate::ref_type());
+                let val = if val.is_null() {
+                    None
+                } else {
+                    Some(VMExternRef::clone_from_raw(val))
+                };
+                table.fill(dst, val.into(), len)
+            }
+        }
+    };
+    if let Err(trap) = result {
+        raise_lib_trap(trap);
+    }
+}
+
 /// Implementation of `table.copy`.
 pub unsafe extern "C" fn wasmtime_table_copy(
     vmctx: *mut VMContext,

crates/runtime/src/table.rs

@@ -67,6 +67,26 @@ impl Table {
         }
     }
 
+    /// Fill `table[dst..dst + len]` with `val`.
+    ///
+    /// Returns a trap error on out-of-bounds accesses.
+    pub fn fill(&self, dst: u32, val: TableElement, len: u32) -> Result<(), Trap> {
+        let start = dst;
+        let end = start
+            .checked_add(len)
+            .ok_or_else(|| Trap::wasm(ir::TrapCode::TableOutOfBounds))?;
+
+        if end > self.size() {
+            return Err(Trap::wasm(ir::TrapCode::TableOutOfBounds));
+        }
+
+        for i in start..end {
+            self.set(i, val.clone()).unwrap();
+        }
+
+        Ok(())
+    }
+
     /// Grow table by the specified amount of elements.
     ///
     /// Returns the previous size of the table if growth is successful.

crates/runtime/src/vmcontext.rs

@@ -594,6 +594,10 @@ impl VMBuiltinFunctionsArray {
             wasmtime_externref_global_get as usize;
         ptrs[BuiltinFunctionIndex::externref_global_set().index() as usize] =
             wasmtime_externref_global_set as usize;
+        ptrs[BuiltinFunctionIndex::table_fill_externref().index() as usize] =
+            wasmtime_table_fill as usize;
+        ptrs[BuiltinFunctionIndex::table_fill_funcref().index() as usize] =
+            wasmtime_table_fill as usize;
 
         if cfg!(debug_assertions) {
             for i in 0..ptrs.len() {