Add event section (#2151)

This adds support for the event and the event section, as specified in
https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md#changes-to-the-binary-model.

Wasm events are features that suspend the current execution and transfer
the control flow to a corresponding handler. Currently the only
supported event kind is exceptions.

For events, this includes support for
- Binary file reading/writing
- Wast file reading/writing
- Binaryen.js API
- Fuzzer
- Validation
- Metadce
- Passes: metrics, minify-imports-and-exports,
  remove-unused-module-elements

1 files changed, 45 insertions, 0 deletions

diff --git a/src/ir/module-utils.h b/src/ir/module-utils.h
index 5569843fd..067f59416 100644
--- a/src/ir/module-utils.h
+++ b/src/ir/module-utils.h
@@ -34,6 +34,7 @@ namespace ModuleUtils {
 struct BinaryIndexes {
   std::unordered_map<Name, Index> functionIndexes;
   std::unordered_map<Name, Index> globalIndexes;
+  std::unordered_map<Name, Index> eventIndexes;
 
   BinaryIndexes(Module& wasm) {
     auto addGlobal = [&](Global* curr) {
@@ -66,6 +67,21 @@ struct BinaryIndexes {
       }
     }
     assert(functionIndexes.size() == wasm.functions.size());
+    auto addEvent = [&](Event* curr) {
+      auto index = eventIndexes.size();
+      eventIndexes[curr->name] = index;
+    };
+    for (auto& curr : wasm.events) {
+      if (curr->imported()) {
+        addEvent(curr.get());
+      }
+    }
+    for (auto& curr : wasm.events) {
+      if (!curr->imported()) {
+        addEvent(curr.get());
+      }
+    }
+    assert(eventIndexes.size() == wasm.events.size());
   }
 };
 
@@ -105,6 +121,16 @@ inline Global* copyGlobal(Global* global, Module& out) {
   return ret;
 }
 
+inline Event* copyEvent(Event* event, Module& out) {
+  auto* ret = new Event();
+  ret->name = event->name;
+  ret->attribute = event->attribute;
+  ret->type = event->type;
+  ret->params = event->params;
+  out.addEvent(ret);
+  return ret;
+}
+
 inline void copyModule(Module& in, Module& out) {
   // we use names throughout, not raw points, so simple copying is fine
   // for everything *but* expressions
@@ -120,6 +146,9 @@ inline void copyModule(Module& in, Module& out) {
   for (auto& curr : in.globals) {
     copyGlobal(curr.get(), out);
   }
+  for (auto& curr : in.events) {
+    copyEvent(curr.get(), out);
+  }
   out.table = in.table;
   for (auto& segment : out.table.segments) {
     segment.offset = ExpressionManipulator::copy(segment.offset, out);
@@ -243,6 +272,22 @@ template<typename T> inline void iterDefinedFunctions(Module& wasm, T visitor) {
   }
 }
 
+template<typename T> inline void iterImportedEvents(Module& wasm, T visitor) {
+  for (auto& import : wasm.events) {
+    if (import->imported()) {
+      visitor(import.get());
+    }
+  }
+}
+
+template<typename T> inline void iterDefinedEvents(Module& wasm, T visitor) {
+  for (auto& import : wasm.events) {
+    if (!import->imported()) {
+      visitor(import.get());
+    }
+  }
+}
+
 } // namespace ModuleUtils
 
 } // namespace wasm