Implement the memory.fill instruction from the bulk memory proposal

build.rs

@@ -184,7 +184,9 @@ fn ignore(testsuite: &str, testname: &str, strategy: &str) -> bool {
 
             ("bulk_memory_operations", "table_copy")
             | ("bulk_memory_operations", "table_init")
-            | ("bulk_memory_operations", "elem") => return false,
+            | ("bulk_memory_operations", "elem")
+            | ("bulk_memory_operations", "memory_copy")
+            | ("bulk_memory_operations", "memory_fill") => return false,
             ("bulk_memory_operations", _) => return true,
 
             _ => {}

crates/environ/src/func_environ.rs

@@ -78,9 +78,17 @@ impl BuiltinFunctionIndex {
     pub const fn get_imported_memory_copy_index() -> Self {
         Self(11)
     }
+    /// Returns an index for wasm's `memory.fill` for locally defined memories.
+    pub const fn get_memory_fill_index() -> Self {
+        Self(12)
+    }
+    /// Returns an index for wasm's `memory.fill` for imported memories.
+    pub const fn get_imported_memory_fill_index() -> Self {
+        Self(13)
+    }
     /// Returns the total number of builtin functions.
     pub const fn builtin_functions_total_number() -> u32 {
-        12
+        14
     }
 
     /// Return the index as an u32 number.
@@ -122,6 +130,10 @@ pub struct FuncEnvironment<'module_environment> {
     /// (it's the same for both local and imported memories).
     memory_copy_sig: Option<ir::SigRef>,
 
+    /// The external function signature for implementing wasm's `memory.fill`
+    /// (it's the same for both local and imported memories).
+    memory_fill_sig: Option<ir::SigRef>,
+
     /// Offsets to struct fields accessed by JIT code.
     offsets: VMOffsets,
 }
@@ -141,6 +153,7 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
             table_init_sig: None,
             elem_drop_sig: None,
             memory_copy_sig: None,
+            memory_fill_sig: None,
             offsets: VMOffsets::new(target_config.pointer_bytes(), module),
         }
     }
@@ -429,6 +442,51 @@ impl<'module_environment> FuncEnvironment<'module_environment> {
         }
     }
 
+    fn get_memory_fill_sig(&mut self, func: &mut Function) -> ir::SigRef {
+        let sig = self.memory_fill_sig.unwrap_or_else(|| {
+            func.import_signature(Signature {
+                params: vec![
+                    AbiParam::special(self.pointer_type(), ArgumentPurpose::VMContext),
+                    // Memory index.
+                    AbiParam::new(I32),
+                    // Destination address.
+                    AbiParam::new(I32),
+                    // Value.
+                    AbiParam::new(I32),
+                    // Length.
+                    AbiParam::new(I32),
+                    // Source location.
+                    AbiParam::new(I32),
+                ],
+                returns: vec![],
+                call_conv: self.target_config.default_call_conv,
+            })
+        });
+        self.memory_fill_sig = Some(sig);
+        sig
+    }
+
+    fn get_memory_fill_func(
+        &mut self,
+        func: &mut Function,
+        memory_index: MemoryIndex,
+    ) -> (ir::SigRef, usize, BuiltinFunctionIndex) {
+        let sig = self.get_memory_fill_sig(func);
+        if let Some(defined_memory_index) = self.module.defined_memory_index(memory_index) {
+            (
+                sig,
+                defined_memory_index.index(),
+                BuiltinFunctionIndex::get_memory_fill_index(),
+            )
+        } else {
+            (
+                sig,
+                memory_index.index(),
+                BuiltinFunctionIndex::get_imported_memory_fill_index(),
+            )
+        }
+    }
+
     /// Translates load of builtin function and returns a pair of values `vmctx`
     /// and address of the loaded function.
     fn translate_load_builtin_function_address(
@@ -1054,16 +1112,30 @@ impl<'module_environment> cranelift_wasm::FuncEnvironment for FuncEnvironment<'m
 
     fn translate_memory_fill(
         &mut self,
-        _pos: FuncCursor,
+        mut pos: FuncCursor,
-        _index: MemoryIndex,
+        memory_index: MemoryIndex,
         _heap: ir::Heap,
-        _dst: ir::Value,
+        dst: ir::Value,
-        _val: ir::Value,
+        val: ir::Value,
-        _len: ir::Value,
+        len: ir::Value,
     ) -> WasmResult<()> {
-        Err(WasmError::Unsupported(
+        let (func_sig, memory_index, func_idx) =
-            "bulk memory: `memory.fill`".to_string(),
+            self.get_memory_fill_func(&mut pos.func, memory_index);
-        ))
+
+        let memory_index_arg = pos.ins().iconst(I32, memory_index as i64);
+
+        let (vmctx, func_addr) = self.translate_load_builtin_function_address(&mut pos, func_idx);
+
+        let src_loc = pos.srcloc();
+        let src_loc_arg = pos.ins().iconst(I32, src_loc.bits() as i64);
+
+        pos.ins().call_indirect(
+            func_sig,
+            func_addr,
+            &[vmctx, memory_index_arg, dst, val, len, src_loc_arg],
+        );
+
+        Ok(())
     }
 
     fn translate_memory_init(

crates/runtime/src/instance.rs

@@ -643,6 +643,7 @@ impl Instance {
         // https://webassembly.github.io/reference-types/core/exec/instructions.html#exec-memory-copy
 
         let memory = self.memory(memory_index);
+
         if src
             .checked_add(len)
             .map_or(true, |n| n as usize > memory.current_length)
@@ -691,6 +692,69 @@ impl Instance {
         }
     }
 
+    /// Perform the `memory.fill` operation on a locally defined memory.
+    ///
+    /// # Errors
+    ///
+    /// Returns a `Trap` error if the memory range is out of bounds.
+    pub(crate) fn defined_memory_fill(
+        &self,
+        memory_index: DefinedMemoryIndex,
+        dst: u32,
+        val: u32,
+        len: u32,
+        source_loc: ir::SourceLoc,
+    ) -> Result<(), Trap> {
+        let memory = self.memory(memory_index);
+
+        if dst
+            .checked_add(len)
+            .map_or(true, |m| m as usize > memory.current_length)
+        {
+            return Err(Trap::Wasm {
+                desc: TrapDescription {
+                    source_loc,
+                    trap_code: ir::TrapCode::HeapOutOfBounds,
+                },
+                backtrace: Backtrace::new(),
+            });
+        }
+
+        let dst = isize::try_from(dst).unwrap();
+        let val = val as u8;
+
+        // Bounds and casts are checked above, by this point we know that
+        // everything is safe.
+        unsafe {
+            let dst = memory.base.offset(dst);
+            ptr::write_bytes(dst, val, len as usize);
+        }
+
+        Ok(())
+    }
+
+    /// Perform the `memory.fill` operation on an imported memory.
+    ///
+    /// # Errors
+    ///
+    /// Returns a `Trap` error if the memory range is out of bounds.
+    pub(crate) fn imported_memory_fill(
+        &self,
+        memory_index: MemoryIndex,
+        dst: u32,
+        val: u32,
+        len: u32,
+        source_loc: ir::SourceLoc,
+    ) -> Result<(), Trap> {
+        let import = self.imported_memory(memory_index);
+        unsafe {
+            let foreign_instance = (&*import.vmctx).instance();
+            let foreign_memory = &*import.from;
+            let foreign_index = foreign_instance.memory_index(foreign_memory);
+            foreign_instance.defined_memory_fill(foreign_index, dst, val, len, source_loc)
+        }
+    }
+
     /// Get a table by index regardless of whether it is locally-defined or an
     /// imported, foreign table.
     pub(crate) fn get_table(&self, table_index: TableIndex) -> &Table {

crates/runtime/src/libcalls.rs

@@ -298,3 +298,39 @@ pub unsafe extern "C" fn wasmtime_imported_memory_copy(
         raise_lib_trap(trap);
     }
 }
+
+/// Implementation of `memory.fill` for locally defined memories.
+#[no_mangle]
+pub unsafe extern "C" fn wasmtime_memory_fill(
+    vmctx: *mut VMContext,
+    memory_index: u32,
+    dst: u32,
+    val: u32,
+    len: u32,
+    source_loc: u32,
+) {
+    let memory_index = DefinedMemoryIndex::from_u32(memory_index);
+    let source_loc = ir::SourceLoc::new(source_loc);
+    let instance = (&mut *vmctx).instance();
+    if let Err(trap) = instance.defined_memory_fill(memory_index, dst, val, len, source_loc) {
+        raise_lib_trap(trap);
+    }
+}
+
+/// Implementation of `memory.fill` for imported memories.
+#[no_mangle]
+pub unsafe extern "C" fn wasmtime_imported_memory_fill(
+    vmctx: *mut VMContext,
+    memory_index: u32,
+    dst: u32,
+    val: u32,
+    len: u32,
+    source_loc: u32,
+) {
+    let memory_index = MemoryIndex::from_u32(memory_index);
+    let source_loc = ir::SourceLoc::new(source_loc);
+    let instance = (&mut *vmctx).instance();
+    if let Err(trap) = instance.imported_memory_fill(memory_index, dst, val, len, source_loc) {
+        raise_lib_trap(trap);
+    }
+}

crates/runtime/src/vmcontext.rs

@@ -567,6 +567,10 @@ impl VMBuiltinFunctionsArray {
             wasmtime_memory_copy as usize;
         ptrs[BuiltinFunctionIndex::get_imported_memory_copy_index().index() as usize] =
             wasmtime_imported_memory_copy as usize;
+        ptrs[BuiltinFunctionIndex::get_memory_fill_index().index() as usize] =
+            wasmtime_memory_fill as usize;
+        ptrs[BuiltinFunctionIndex::get_imported_memory_fill_index().index() as usize] =
+            wasmtime_imported_memory_fill as usize;
 
         debug_assert!(ptrs.iter().cloned().all(|p| p != 0));