From 60003cbc3f5a222d8e20da2db0db41a794fcd957 Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Fri, 10 Jul 2026 12:52:30 -0700
Subject: [PATCH] wasm-reduce: Fix up EH nested pops when adding blocks

---
 src/tools/wasm-reduce/wasm-reduce.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/tools/wasm-reduce/wasm-reduce.cpp b/src/tools/wasm-reduce/wasm-reduce.cpp
index 4fe986d13c4..42eb113bd34 100644
--- a/src/tools/wasm-reduce/wasm-reduce.cpp
+++ b/src/tools/wasm-reduce/wasm-reduce.cpp
@@ -28,6 +28,7 @@
 #include <memory>
 
 #include "ir/branch-utils.h"
+#include "ir/eh-utils.h"
 #include "ir/iteration.h"
 #include "ir/localize.h"
 #include "ir/properties.h"
@@ -1089,9 +1090,13 @@ struct Reducer
       struct FunctionReplacer
         : public WalkerPass<PostWalker<FunctionReplacer>> {
         bool isFunctionParallel() override { return true; }
+
         std::unique_ptr<Pass> create() override {
           return std::make_unique<FunctionReplacer>();
         };
+
+        bool needEHFixups = false;
+
         void visitCall(Call* curr) {
           // Replace calls to functions we have removed.
           if (getModule()->getFunctionOrNull(curr->target)) {
@@ -1112,6 +1117,9 @@ struct Reducer
           block->list.push_back(replacement);
           block->type = originalType;
           replaceCurrent(block);
+          // We added a block around content here, possibly causing us to need
+          // EH fixups later.
+          needEHFixups = true;
         }
         void visitRefFunc(RefFunc* curr) {
           // Replace references to functions we have removed.
@@ -1122,6 +1130,11 @@ struct Reducer
           replaceCurrent(
             builder.makeBlock({builder.makeUnreachable()}, curr->type));
         }
+        void visitFunction(Function* curr) {
+          if (needEHFixups) {
+            EHUtils::handleBlockNestedPops(curr, *getModule());
+          }
+        }
       };
       PassRunner runner(module.get());
       runner.add(std::make_unique<FunctionReplacer>());