[Parser] Parse throw_ref (WebAssembly#6238)

Author: tlively

src/parser/contexts.h

@@ -453,6 +453,7 @@ struct NullInstrParserCtx {
   Result<> makeTableCopy(Index, TableIdxT*, TableIdxT*) { return Ok{}; }
   Result<> makeThrow(Index, TagIdxT) { return Ok{}; }
   Result<> makeRethrow(Index, LabelIdxT) { return Ok{}; }
+  Result<> makeThrowRef(Index) { return Ok{}; }
   Result<> makeTupleMake(Index, uint32_t) { return Ok{}; }
   Result<> makeTupleExtract(Index, uint32_t, uint32_t) { return Ok{}; }
   Result<> makeTupleDrop(Index, uint32_t) { return Ok{}; }
@@ -1721,6 +1722,10 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx> {
     return withLoc(pos, irBuilder.makeRethrow(label));
   }
 
+  Result<> makeThrowRef(Index pos) {
+    return withLoc(pos, irBuilder.makeThrowRef());
+  }
+
   Result<> makeTupleMake(Index pos, uint32_t arity) {
     return withLoc(pos, irBuilder.makeTupleMake(arity));
   }

src/parser/parsers.h

@@ -1646,7 +1646,7 @@ template<typename Ctx> Result<> makeRethrow(Ctx& ctx, Index pos) {
 }
 
 template<typename Ctx> Result<> makeThrowRef(Ctx& ctx, Index pos) {
-  return ctx.in.err("unimplemented instruction");
+  return ctx.makeThrowRef(pos);
 }
 
 template<typename Ctx> Result<> makeTupleMake(Ctx& ctx, Index pos) {

src/wasm-ir-builder.h

@@ -164,7 +164,7 @@ class IRBuilder : public UnifiedExpressionVisitor<IRBuilder, Result<>> {
                                       const std::vector<bool>& isRefs);
   [[nodiscard]] Result<> makeThrow(Name tag);
   [[nodiscard]] Result<> makeRethrow(Index label);
-  // [[nodiscard]] Result<> makeThrowRef();
+  [[nodiscard]] Result<> makeThrowRef();
   [[nodiscard]] Result<> makeTupleMake(uint32_t arity);
   [[nodiscard]] Result<> makeTupleExtract(uint32_t arity, uint32_t index);
   [[nodiscard]] Result<> makeTupleDrop(uint32_t arity);

src/wasm.h

@@ -1522,6 +1522,7 @@ class Rethrow : public SpecificExpression<Expression::RethrowId> {
 // 'throw_ref' from the new EH proposal
 class ThrowRef : public SpecificExpression<Expression::ThrowRefId> {
 public:
+  ThrowRef() = default;
   ThrowRef(MixedArena& allocator) {}
 
   Expression* exnref;

src/wasm/wasm-ir-builder.cpp

@@ -1390,7 +1390,12 @@ Result<> IRBuilder::makeRethrow(Index label) {
   return Ok{};
 }
 
-// Result<> IRBuilder::makeThrowRef() {}
+Result<> IRBuilder::makeThrowRef() {
+  ThrowRef curr;
+  CHECK_ERR(visitThrowRef(&curr));
+  push(builder.makeThrowRef(curr.exnref));
+  return Ok{};
+}
 
 Result<> IRBuilder::makeTupleMake(uint32_t arity) {
   TupleMake curr(wasm.allocator);