Update exception handling support to current proposal (#1596)

This PR updates the support of exception handling to the latest proposal (that is compatible with future 2-phase exception handling) described in https://github.com/WebAssembly/exception-handling/pull/137 and https://github.com/WebAssembly/exception-handling/pull/143.

* Adds back tagged `catch $e`, `catch_all`, and `rethrow N` from a previous version of wabt, but with updates to match the current spec (e.g., `catch_all` shares an opcode with `else`, `rethrow`'s depth indexes only catch blocks, etc).
* Adds `unwind` and `delegate` instructions.
* Removes `exnref` and `br_on_exn`.
* Updates relevant tests.

There are some details that could still change (e.g., maybe how `delegate`'s depth is validated), but I'd be happy to submit further PRs if the spec details change.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/binary-reader-objdump.cc b/src/binary-reader-objdump.cc
index 77d207d2..f03283e7 100644
--- a/src/binary-reader-objdump.cc
+++ b/src/binary-reader-objdump.cc
@@ -475,6 +475,7 @@ class BinaryReaderObjdumpDisassemble : public BinaryReaderObjdumpBase {
   Result OnBrTableExpr(Index num_targets,
                        Index* target_depths,
                        Index default_target_depth) override;
+  Result OnDelegateExpr(Index) override;
   Result OnEndExpr() override;
   Result OnEndFunc() override;
 
@@ -595,6 +596,7 @@ void BinaryReaderObjdumpDisassemble::LogOpcode(size_t data_size,
       switch (current_opcode) {
         case Opcode::Else:
         case Opcode::Catch:
+        case Opcode::Unwind:
           indent_level--;
         default:
           break;
@@ -741,6 +743,15 @@ Result BinaryReaderObjdumpDisassemble::OnBrTableExpr(
   return Result::Ok;
 }
 
+Result BinaryReaderObjdumpDisassemble::OnDelegateExpr(Index depth) {
+  // Because `delegate` ends the block we need to dedent here, and
+  // we don't need to dedent it in LogOpcode.
+  if (indent_level > 0) {
+    indent_level--;
+  }
+  return Result::Ok;
+}
+
 Result BinaryReaderObjdumpDisassemble::OnEndFunc() {
   LogOpcode(0, nullptr);
   return Result::Ok;