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, 26 insertions, 0 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index fb85023f0..9dbf3cc1f 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -1660,6 +1660,9 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
       case ExternalKind::Global:
         o << "global";
         break;
+      case ExternalKind::Event:
+        o << "event";
+        break;
       case ExternalKind::Invalid:
         WASM_UNREACHABLE();
     }
@@ -1805,6 +1808,25 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
     }
     o << maybeNewLine;
   }
+  void visitEvent(Event* curr) {
+    doIndent(o, indent);
+    if (curr->imported()) {
+      o << '(';
+      emitImportHeader(curr);
+    }
+    o << "(event ";
+    printName(curr->name, o);
+    o << maybeSpace << "(attr " << curr->attribute << ')' << maybeSpace << '(';
+    printMinor(o, "param");
+    for (auto& param : curr->params) {
+      o << ' ' << printType(param);
+    }
+    o << "))";
+    if (curr->imported()) {
+      o << ')';
+    }
+    o << maybeNewLine;
+  }
   void printTableHeader(Table* curr) {
     o << '(';
     printMedium(o, "table") << ' ';
@@ -1948,12 +1970,16 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
       *curr, [&](Global* global) { visitGlobal(global); });
     ModuleUtils::iterImportedFunctions(
       *curr, [&](Function* func) { visitFunction(func); });
+    ModuleUtils::iterImportedEvents(*curr,
+                                    [&](Event* event) { visitEvent(event); });
     ModuleUtils::iterDefinedMemories(
       *curr, [&](Memory* memory) { visitMemory(memory); });
     ModuleUtils::iterDefinedTables(*curr,
                                    [&](Table* table) { visitTable(table); });
     ModuleUtils::iterDefinedGlobals(
       *curr, [&](Global* global) { visitGlobal(global); });
+    ModuleUtils::iterDefinedEvents(*curr,
+                                   [&](Event* event) { visitEvent(event); });
     for (auto& child : curr->exports) {
       doIndent(o, indent);
       visitExport(child.get());