4 files changed, 31 insertions, 0 deletions
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 429ff7bae..5aa5948fe 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -3930,6 +3930,9 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
       if (maybeVisitStringEncode(curr, opcode)) {
         break;
       }
+      if (maybeVisitStringConcat(curr, opcode)) {
+        break;
+      }
       if (opcode == BinaryConsts::RefIsFunc ||
           opcode == BinaryConsts::RefIsData ||
           opcode == BinaryConsts::RefIsI31) {
@@ -7220,6 +7223,17 @@ bool WasmBinaryBuilder::maybeVisitStringEncode(Expression*& out,
   return true;
 }
 
+bool WasmBinaryBuilder::maybeVisitStringConcat(Expression*& out,
+                                               uint32_t code) {
+  if (code != BinaryConsts::StringConcat) {
+    return false;
+  }
+  auto* right = popNonVoidExpression();
+  auto* left = popNonVoidExpression();
+  out = Builder(wasm).makeStringConcat(left, right);
+  return true;
+}
+
 void WasmBinaryBuilder::visitRefAs(RefAs* curr, uint8_t code) {
   BYN_TRACE("zz node: RefAs\n");
   switch (code) {
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 68bd69104..fe52864d8 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2990,6 +2990,11 @@ Expression* SExpressionWasmBuilder::makeStringEncode(Element& s,
     op, parseExpression(s[i]), parseExpression(s[i + 1]));
 }
 
+Expression* SExpressionWasmBuilder::makeStringConcat(Element& s) {
+  return Builder(wasm).makeStringConcat(parseExpression(s[1]),
+                                        parseExpression(s[2]));
+}
+
 // converts an s-expression string representing binary data into an output
 // sequence of raw bytes this appends to data, which may already contain
 // content.
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 38c8f1661..6596cccc7 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2300,6 +2300,10 @@ void BinaryInstWriter::visitStringEncode(StringEncode* curr) {
   }
 }
 
+void BinaryInstWriter::visitStringConcat(StringConcat* curr) {
+  o << int8_t(BinaryConsts::GCPrefix) << U32LEB(BinaryConsts::StringConcat);
+}
+
 void BinaryInstWriter::emitScopeEnd(Expression* curr) {
   assert(!breakStack.empty());
   breakStack.pop_back();
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index d4337a87d..d3b1c2151 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -1200,6 +1200,14 @@ void StringEncode::finalize() {
   }
 }
 
+void StringConcat::finalize() {
+  if (left->type == Type::unreachable || right->type == Type::unreachable) {
+    type = Type::unreachable;
+  } else {
+    type = Type(HeapType::string, NonNullable);
+  }
+}
+
 size_t Function::getNumParams() { return getParams().size(); }
 
 size_t Function::getNumVars() { return vars.size(); }