Merge branch 'unsubtyping-optimize-descs' into unsubtyping-exact-casts

Author: tlively

src/passes/Unsubtyping.cpp

@@ -644,6 +644,7 @@ struct Unsubtyping : Pass {
         info.descriptors.insert({*desc, type});
       }
       void visitRefGetDesc(RefGetDesc* curr) {
+        Super::visitRefGetDesc(curr);
         if (!curr->ref->type.isStruct()) {
           return;
         }
@@ -664,6 +665,7 @@ struct Unsubtyping : Pass {
         noteDescriptor(curr->desc->type.getHeapType());
       }
       void visitStructNew(StructNew* curr) {
+        Super::visitStructNew(curr);
         if (curr->type == Type::unreachable || !curr->desc) {
           return;
         }

test/lit/passes/unsubtyping.wast

@@ -1892,3 +1892,31 @@
   )
  )
 )
+
+;; Even though our analysis has its own visitor for StructNew, it should still
+;; be able to collect subtype constraints from StructNews.
+(module
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $A (sub (struct (field (ref null $A)))))
+  (type $A (sub (struct (field (ref null $A)))))
+  ;; CHECK:       (type $B (sub $A (struct (field (ref null $A)))))
+  (type $B (sub $A (struct (field (ref null $A)))))
+
+  ;; CHECK:       (type $2 (func (param (ref null $B))))
+
+  ;; CHECK:      (func $test (type $2) (param $B (ref null $B))
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (struct.new $A
+  ;; CHECK-NEXT:    (local.get $B)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $test (param $B (ref null $B))
+    (drop
+      ;; This requires B <: A.
+      (struct.new $A
+        (local.get $B)
+      )
+    )
+  )
+)