Emit "elem declare" for functions that need it (#3653)

This adds support for reading (elem declare func $foo .. in the text and
binary formats. We can simply ignore it: we don't need to represent it in
IR, rather we find what needs to be declared when writing. That part takes
a little more work, for which this adds a shared helper function.

1 files changed, 73 insertions, 0 deletions

diff --git a/src/ir/table-utils.cpp b/src/ir/table-utils.cpp
new file mode 100644
index 000000000..ef89e50f3
--- /dev/null
+++ b/src/ir/table-utils.cpp
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2021 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "table-utils.h"
+#include "find_all.h"
+#include "module-utils.h"
+
+namespace wasm {
+
+namespace TableUtils {
+
+std::set<Name> getFunctionsNeedingElemDeclare(Module& wasm) {
+  // Without reference types there are no ref.funcs or elem declare.
+  if (!wasm.features.hasReferenceTypes()) {
+    return {};
+  }
+
+  // Find all the names in the tables.
+
+  std::unordered_set<Name> tableNames;
+  for (auto& table : wasm.tables) {
+    for (auto& segment : table->segments) {
+      for (auto name : segment.data) {
+        tableNames.insert(name);
+      }
+    }
+  }
+
+  // Find all the names in ref.funcs.
+  using Names = std::unordered_set<Name>;
+
+  ModuleUtils::ParallelFunctionAnalysis<Names> analysis(
+    wasm, [&](Function* func, Names& names) {
+      if (func->imported()) {
+        return;
+      }
+      for (auto* refFunc : FindAll<RefFunc>(func->body).list) {
+        names.insert(refFunc->func);
+      }
+    });
+
+  // Find the names that need to be declared.
+
+  std::set<Name> ret;
+
+  for (auto& kv : analysis.map) {
+    auto& names = kv.second;
+    for (auto name : names) {
+      if (!tableNames.count(name)) {
+        ret.insert(name);
+      }
+    }
+  }
+
+  return ret;
+}
+
+} // namespace TableUtils
+
+} // namespace wasm