Update RefCast representation to drop extra HeapType (#5350)

The latest upstream version of ref.cast is parameterized with a target reference
type, not just a heap type, because the nullability of the result is
parameterizable. As a first step toward implementing these new, more flexible
ref.cast instructions, change the internal representation of ref.cast to use the
expression type as the cast target rather than storing a separate heap type
field. For now require that the encoded semantics match the previously allowed
semantics, though, so that none of the optimization passes need to be updated.

1 files changed, 7 insertions, 1 deletions

diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index 726c70c7c..b102ecb1c 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -2530,10 +2530,16 @@ void FunctionValidator::visitRefCast(RefCast* curr) {
     return;
   }
   shouldBeEqual(
-    curr->intendedType.getBottom(),
+    curr->type.getHeapType().getBottom(),
     curr->ref->type.getHeapType().getBottom(),
     curr,
     "ref.cast target type and ref type must have a common supertype");
+
+  // TODO: Remove this restriction
+  shouldBeEqual(curr->type.getNullability(),
+                curr->ref->type.getNullability(),
+                curr,
+                "ref.cast to a different nullability not yet implemented");
 }
 
 void FunctionValidator::visitBrOn(BrOn* curr) {