6 files changed, 57 insertions, 5 deletions
diff --git a/src/parser/contexts.h b/src/parser/contexts.h
index 4147f7bda..aa207fcd5 100644
--- a/src/parser/contexts.h
+++ b/src/parser/contexts.h
@@ -446,6 +446,7 @@ struct NullInstrParserCtx {
   template<typename HeapTypeT> Result<> makeArrayFill(Index, HeapTypeT) {
     return Ok{};
   }
+  Result<> makeRefAs(Index, RefAsOp) { return Ok{}; }
 };
 
 // Phase 1: Parse definition spans for top-level module elements and determine
@@ -1352,6 +1353,10 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx> {
   Result<> makeArrayFill(Index pos, HeapType type) {
     return withLoc(pos, irBuilder.makeArrayFill(type));
   }
+
+  Result<> makeRefAs(Index pos, RefAsOp op) {
+    return withLoc(pos, irBuilder.makeRefAs(op));
+  }
 };
 
 } // namespace wasm::WATParser
diff --git a/src/parser/parsers.h b/src/parser/parsers.h
index e2fb3732a..610e2953a 100644
--- a/src/parser/parsers.h
+++ b/src/parser/parsers.h
@@ -1425,7 +1425,7 @@ template<typename Ctx> Result<> makeArrayInitElem(Ctx& ctx, Index pos) {
 }
 
 template<typename Ctx> Result<> makeRefAs(Ctx& ctx, Index pos, RefAsOp op) {
-  return ctx.in.err("unimplemented instruction");
+  return ctx.makeRefAs(pos, op);
 }
 
 template<typename Ctx>
diff --git a/src/wasm-ir-builder.h b/src/wasm-ir-builder.h
index 64ee0d62e..24b430e25 100644
--- a/src/wasm-ir-builder.h
+++ b/src/wasm-ir-builder.h
@@ -170,7 +170,7 @@ public:
   [[nodiscard]] Result<> makeArrayFill(HeapType type);
   // [[nodiscard]] Result<> makeArrayInitData();
   // [[nodiscard]] Result<> makeArrayInitElem();
-  // [[nodiscard]] Result<> makeRefAs();
+  [[nodiscard]] Result<> makeRefAs(RefAsOp op);
   // [[nodiscard]] Result<> makeStringNew();
   // [[nodiscard]] Result<> makeStringConst();
   // [[nodiscard]] Result<> makeStringMeasure();
diff --git a/src/wasm.h b/src/wasm.h
index dbedc05f4..47cc047bb 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -1760,6 +1760,7 @@ public:
 
 class RefAs : public SpecificExpression<Expression::RefAsId> {
 public:
+  RefAs() = default;
   RefAs(MixedArena& allocator) {}
 
   RefAsOp op;
diff --git a/src/wasm/wasm-ir-builder.cpp b/src/wasm/wasm-ir-builder.cpp
index cc2bfb433..843e0ed78 100644
--- a/src/wasm/wasm-ir-builder.cpp
+++ b/src/wasm/wasm-ir-builder.cpp
@@ -1048,7 +1048,12 @@ Result<> IRBuilder::makeArrayFill(HeapType type) {
 
 // Result<> IRBuilder::makeArrayInitElem() {}
 
-// Result<> IRBuilder::makeRefAs() {}
+Result<> IRBuilder::makeRefAs(RefAsOp op) {
+  RefAs curr;
+  CHECK_ERR(visitRefAs(&curr));
+  push(builder.makeRefAs(op, curr.value));
+  return Ok{};
+}
 
 // Result<> IRBuilder::makeStringNew() {}
 
diff --git a/test/lit/wat-kitchen-sink.wast b/test/lit/wat-kitchen-sink.wast
index a99cd4c24..6b70a7822 100644
--- a/test/lit/wat-kitchen-sink.wast
+++ b/test/lit/wat-kitchen-sink.wast
@@ -112,6 +112,8 @@
 
  ;; CHECK:      (type $49 (func (param (ref $a2) i32 f32 i32)))
 
+ ;; CHECK:      (type $50 (func (param externref)))
+
  ;; CHECK:      (type $s2 (struct (field i32)))
  (type $s2 (struct i32))
  ;; CHECK:      (type $s3 (struct (field i64)))
@@ -160,7 +162,7 @@
  (global (import "mod" "") (ref null $many))
 
  (global (mut i32) i32.const 0)
- ;; CHECK:      (type $61 (func (param (ref $s0) (ref $s1) (ref $s2) (ref $s3) (ref $s4) (ref $s5) (ref $s6) (ref $s7) (ref $s8) (ref $a0) (ref $a1) (ref $a2) (ref $a3) (ref $subvoid) (ref $submany))))
+ ;; CHECK:      (type $62 (func (param (ref $s0) (ref $s1) (ref $s2) (ref $s3) (ref $s4) (ref $s5) (ref $s6) (ref $s7) (ref $s8) (ref $a0) (ref $a1) (ref $a2) (ref $a3) (ref $subvoid) (ref $submany))))
 
  ;; CHECK:      (import "" "mem" (memory $mimport$1 0))
 
@@ -2693,6 +2695,45 @@
   array.fill $a2
  )
 
+ ;; CHECK:      (func $ref-as-non-null (type $8) (param $0 anyref)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (ref.as_non_null
+ ;; CHECK-NEXT:    (local.get $0)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $ref-as-non-null (param anyref)
+  local.get 0
+  ref.as_non_null
+  drop
+ )
+
+ ;; CHECK:      (func $any-convert-extern (type $50) (param $0 externref)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (extern.internalize
+ ;; CHECK-NEXT:    (local.get $0)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $any-convert-extern (param externref)
+  local.get 0
+  extern.internalize
+  drop
+ )
+
+ ;; CHECK:      (func $extern-convert-any (type $8) (param $0 anyref)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (extern.externalize
+ ;; CHECK-NEXT:    (local.get $0)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $extern-convert-any (param anyref)
+  local.get 0
+  extern.externalize
+  drop
+ )
+
  ;; CHECK:      (func $call (type $16) (param $0 i32) (param $1 i64) (result f32)
  ;; CHECK-NEXT:  (call $call
  ;; CHECK-NEXT:   (local.get $0)
@@ -2717,7 +2758,7 @@
   return_call $return_call
  )
 
- ;; CHECK:      (func $use-types (type $61) (param $0 (ref $s0)) (param $1 (ref $s1)) (param $2 (ref $s2)) (param $3 (ref $s3)) (param $4 (ref $s4)) (param $5 (ref $s5)) (param $6 (ref $s6)) (param $7 (ref $s7)) (param $8 (ref $s8)) (param $9 (ref $a0)) (param $10 (ref $a1)) (param $11 (ref $a2)) (param $12 (ref $a3)) (param $13 (ref $subvoid)) (param $14 (ref $submany))
+ ;; CHECK:      (func $use-types (type $62) (param $0 (ref $s0)) (param $1 (ref $s1)) (param $2 (ref $s2)) (param $3 (ref $s3)) (param $4 (ref $s4)) (param $5 (ref $s5)) (param $6 (ref $s6)) (param $7 (ref $s7)) (param $8 (ref $s8)) (param $9 (ref $a0)) (param $10 (ref $a1)) (param $11 (ref $a2)) (param $12 (ref $a3)) (param $13 (ref $subvoid)) (param $14 (ref $submany))
  ;; CHECK-NEXT:  (nop)
  ;; CHECK-NEXT: )
  (func $use-types