5 files changed, 77 insertions, 0 deletions
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index ee3c1a6fa..b6a5daf14 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -3574,6 +3574,9 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
       if (maybeVisitArrayNew(curr, opcode)) {
         break;
       }
+      if (maybeVisitArrayInit(curr, opcode)) {
+        break;
+      }
       if (maybeVisitArrayGet(curr, opcode)) {
         break;
       }
@@ -6508,6 +6511,22 @@ bool WasmBinaryBuilder::maybeVisitArrayNew(Expression*& out, uint32_t code) {
   return true;
 }
 
+bool WasmBinaryBuilder::maybeVisitArrayInit(Expression*& out, uint32_t code) {
+  if (code != BinaryConsts::ArrayInit) {
+    return false;
+  }
+  auto heapType = getIndexedHeapType();
+  auto size = getU32LEB();
+  auto* rtt = popNonVoidExpression();
+  validateHeapTypeUsingChild(rtt, heapType);
+  std::vector<Expression*> values(size);
+  for (size_t i = 0; i < size; i++) {
+    values[size - i - 1] = popNonVoidExpression();
+  }
+  out = Builder(wasm).makeArrayInit(rtt, values);
+  return true;
+}
+
 bool WasmBinaryBuilder::maybeVisitArrayGet(Expression*& out, uint32_t code) {
   bool signed_ = false;
   switch (code) {
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index c9ca71a6d..28028c459 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2680,6 +2680,18 @@ Expression* SExpressionWasmBuilder::makeArrayNew(Element& s, bool default_) {
   return Builder(wasm).makeArrayNew(rtt, size, init);
 }
 
+Expression* SExpressionWasmBuilder::makeArrayInit(Element& s) {
+  auto heapType = parseHeapType(*s[1]);
+  size_t i = 2;
+  std::vector<Expression*> values;
+  while (i < s.size() - 1) {
+    values.push_back(parseExpression(*s[i++]));
+  }
+  auto* rtt = parseExpression(*s[i++]);
+  validateHeapTypeUsingChild(rtt, heapType, s);
+  return Builder(wasm).makeArrayInit(rtt, values);
+}
+
 Expression* SExpressionWasmBuilder::makeArrayGet(Element& s, bool signed_) {
   auto heapType = parseHeapType(*s[1]);
   auto ref = parseExpression(*s[2]);
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 7b682a264..e5460cf6f 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2040,6 +2040,12 @@ void BinaryInstWriter::visitArrayNew(ArrayNew* curr) {
   parent.writeIndexedHeapType(curr->rtt->type.getHeapType());
 }
 
+void BinaryInstWriter::visitArrayInit(ArrayInit* curr) {
+  o << int8_t(BinaryConsts::GCPrefix) << U32LEB(BinaryConsts::ArrayInit);
+  parent.writeIndexedHeapType(curr->rtt->type.getHeapType());
+  o << U32LEB(curr->values.size());
+}
+
 void BinaryInstWriter::visitArrayGet(ArrayGet* curr) {
   auto heapType = curr->ref->type.getHeapType();
   const auto& field = heapType.getArray().element;
diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index 450a7b956..eaeea7f1a 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -382,6 +382,7 @@ public:
   void visitStructGet(StructGet* curr);
   void visitStructSet(StructSet* curr);
   void visitArrayNew(ArrayNew* curr);
+  void visitArrayInit(ArrayInit* curr);
   void visitArrayGet(ArrayGet* curr);
   void visitArraySet(ArraySet* curr);
   void visitArrayLen(ArrayLen* curr);
@@ -2416,6 +2417,31 @@ void FunctionValidator::visitArrayNew(ArrayNew* curr) {
   }
 }
 
+void FunctionValidator::visitArrayInit(ArrayInit* curr) {
+  shouldBeTrue(getModule()->features.hasGC(),
+               curr,
+               "array.init requires gc to be enabled");
+  if (curr->type == Type::unreachable) {
+    return;
+  }
+  if (!shouldBeTrue(
+        curr->rtt->type.isRtt(), curr, "array.init rtt must be rtt")) {
+    return;
+  }
+  auto heapType = curr->rtt->type.getHeapType();
+  if (!shouldBeTrue(
+        heapType.isArray(), curr, "array.init heap type must be array")) {
+    return;
+  }
+  const auto& element = heapType.getArray().element;
+  for (auto* value : curr->values) {
+    shouldBeSubType(value->type,
+                    element.type,
+                    curr,
+                    "array.init value must have proper type");
+  }
+}
+
 void FunctionValidator::visitArrayGet(ArrayGet* curr) {
   shouldBeTrue(
     getModule()->features.hasGC(), curr, "array.get requires gc to be enabled");
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 0dfcf5c2e..761c17116 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -1035,6 +1035,20 @@ void ArrayNew::finalize() {
   type = Type(rtt->type.getHeapType(), NonNullable);
 }
 
+void ArrayInit::finalize() {
+  if (rtt->type == Type::unreachable) {
+    type = Type::unreachable;
+    return;
+  }
+  for (auto* value : values) {
+    if (value->type == Type::unreachable) {
+      type = Type::unreachable;
+      return;
+    }
+  }
+  type = Type(rtt->type.getHeapType(), NonNullable);
+}
+
 void ArrayGet::finalize() {
   if (ref->type == Type::unreachable || index->type == Type::unreachable) {
     type = Type::unreachable;