4 files changed, 81 insertions, 0 deletions
diff --git a/src/passes/CMakeLists.txt b/src/passes/CMakeLists.txt
index 9d16f9782..4cf28fa65 100644
--- a/src/passes/CMakeLists.txt
+++ b/src/passes/CMakeLists.txt
@@ -110,6 +110,7 @@ set(passes_SOURCES
   Souperify.cpp
   SpillPointers.cpp
   StackCheck.cpp
+  StripEH.cpp
   SSAify.cpp
   Untee.cpp
   Vacuum.cpp
diff --git a/src/passes/StripEH.cpp b/src/passes/StripEH.cpp
new file mode 100644
index 000000000..d2a68d630
--- /dev/null
+++ b/src/passes/StripEH.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2023 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.
+ */
+
+//
+// Removes all EH instructions and tags. Removes catch blocks and converts
+// 'throw's into 'unreachable's. Any exception thrown will crash the program as
+// they are now traps.
+//
+
+#include <ir/drop.h>
+#include <ir/utils.h>
+
+namespace wasm {
+
+namespace {
+
+struct StripEHImpl : public WalkerPass<PostWalker<StripEHImpl>> {
+  bool isFunctionParallel() override { return true; }
+
+  bool refinalize = false;
+
+  std::unique_ptr<Pass> create() override {
+    return std::make_unique<StripEHImpl>();
+  }
+
+  void visitThrow(Throw* curr) {
+    auto& wasm = *getModule();
+    Builder builder(wasm);
+    replaceCurrent(getDroppedChildrenAndAppend(curr,
+                                               wasm,
+                                               getPassOptions(),
+                                               builder.makeUnreachable(),
+                                               DropMode::IgnoreParentEffects));
+  }
+
+  void visitTry(Try* curr) {
+    replaceCurrent(curr->body);
+    refinalize = true;
+  }
+
+  void visitFunction(Function* curr) {
+    if (refinalize) {
+      ReFinalize().walkFunctionInModule(curr, getModule());
+    }
+  }
+};
+
+struct StripEH : public Pass {
+  void run(Module* wasm) override {
+    PassRunner runner(wasm);
+    // We run this as an inner pass to make it parallel. This StripEH pass
+    // itself cannot be parallel because we need to disable the EH feature.
+    runner.add(std::make_unique<StripEHImpl>());
+    runner.setIsNested(true);
+    runner.run();
+    wasm->removeTags([](Tag*) { return true; });
+    wasm->features.disable(FeatureSet::ExceptionHandling);
+  }
+};
+
+} // anonymous namespace
+
+Pass* createStripEHPass() { return new StripEH(); }
+
+} // namespace wasm
diff --git a/src/passes/pass.cpp b/src/passes/pass.cpp
index ff2c7d45f..0411dcc75 100644
--- a/src/passes/pass.cpp
+++ b/src/passes/pass.cpp
@@ -464,6 +464,7 @@ void PassRegistry::registerPasses() {
   registerPass("strip-producers",
                "strip the wasm producers section",
                createStripProducersPass);
+  registerPass("strip-eh", "strip EH instructions", createStripEHPass);
   registerPass("strip-target-features",
                "strip the wasm target features section",
                createStripTargetFeaturesPass);
diff --git a/src/passes/passes.h b/src/passes/passes.h
index 346741b1a..d8855d4a8 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -145,6 +145,7 @@ Pass* createStripTargetFeaturesPass();
 Pass* createSouperifyPass();
 Pass* createSouperifySingleUsePass();
 Pass* createSpillPointersPass();
+Pass* createStripEHPass();
 Pass* createStubUnsupportedJSOpsPass();
 Pass* createSSAifyPass();
 Pass* createSSAifyNoMergePass();