Add support for table.copy

This adds support for the `table.copy` instruction from the bulk memory
proposal. It also supports multiple tables, which were introduced by the
reference types proposal.

Part of #928

crates/environ/src/module.rs

@@ -6,7 +6,7 @@ use cranelift_codegen::ir;
 use cranelift_entity::{EntityRef, PrimaryMap};
 use cranelift_wasm::{
     DefinedFuncIndex, DefinedGlobalIndex, DefinedMemoryIndex, DefinedTableIndex, FuncIndex, Global,
-    GlobalIndex, Memory, MemoryIndex, SignatureIndex, Table, TableIndex,
+    GlobalIndex, Memory, MemoryIndex, PassiveElemIndex, SignatureIndex, Table, TableIndex,
 };
 use indexmap::IndexMap;
 use more_asserts::assert_ge;
@@ -165,6 +165,9 @@ pub struct Module {
     /// WebAssembly table initializers.
     pub table_elements: Vec<TableElements>,
 
+    /// WebAssembly passive elements.
+    pub passive_elements: HashMap<PassiveElemIndex, Box<[FuncIndex]>>,
+
     /// WebAssembly table initializers.
     pub func_names: HashMap<FuncIndex, String>,
 }
@@ -219,6 +222,7 @@ impl Module {
             exports: IndexMap::new(),
             start_func: None,
             table_elements: Vec::new(),
+            passive_elements: HashMap::new(),
             func_names: HashMap::new(),
             local: ModuleLocal {
                 num_imported_funcs: 0,