Classify public tag types as public (#7232)

Tags previously preserved only their signatures and not their heap types
in the IR, so there was no need or opportunity to classify their types
as public, even for tags that were imported or exported. When we updated
tags to preserve their heap types, we did not update the visibility
classification code to handle them. Update that code now.

Author: tlively

src/ir/module-utils.cpp

@@ -605,8 +605,7 @@ void classifyTypeVisibility(Module& wasm,
     }
   };
 
-  // TODO: Consider Tags as well, but they should store HeapTypes instead of
-  // Signatures first.
+  ModuleUtils::iterImportedTags(wasm, [&](Tag* tag) { notePublic(tag->type); });
   ModuleUtils::iterImportedTables(wasm, [&](Table* table) {
     assert(table->type.isRef());
     notePublic(table->type.getHeapType());
@@ -647,7 +646,7 @@ void classifyTypeVisibility(Module& wasm,
         continue;
       }
       case ExternalKind::Tag:
-        // TODO
+        notePublic(wasm.getTag(ex->value)->type);
         continue;
       case ExternalKind::Invalid:
         break;

test/lit/passes/remove-unused-types-public-tags.wast

@@ -0,0 +1,84 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+
+;; Check that public tag types are correctly considered public and do not become
+;; part of the single, large rec group.
+
+;; RUN: foreach %s %t wasm-opt --remove-unused-types --closed-world -all -S -o - | filecheck %s
+
+;; Neither imported nor exported tag. The tag type is private.
+(module
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $other-2 (struct (field i8)))
+
+  ;; CHECK:       (type $other-1 (struct))
+
+  ;; CHECK:       (type $tag-type (func))
+  (type $tag-type (func))
+  (type $other-1 (struct))
+  (type $other-2 (struct (field i8)))
+
+  ;; CHECK:      (global $tag-type (ref null $tag-type) (ref.null nofunc))
+
+  ;; CHECK:      (global $other-1 (ref null $other-1) (ref.null none))
+
+  ;; CHECK:      (global $other-2 (ref null $other-2) (ref.null none))
+
+  ;; CHECK:      (tag $exported (type $tag-type))
+  (tag $exported (type $tag-type))
+
+  ;; Use all the types.
+  (global $tag-type (ref null $tag-type) (ref.null nofunc))
+  (global $other-1 (ref null $other-1) (ref.null none))
+  (global $other-2 (ref null $other-2) (ref.null none))
+)
+
+;; Imported tag.
+(module
+  ;; CHECK:      (type $tag-type (func))
+  (type $tag-type (func))
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $other-2 (struct (field i8)))
+
+  ;; CHECK:       (type $other-1 (struct))
+  (type $other-1 (struct))
+  (type $other-2 (struct (field i8)))
+
+  (tag $imported (import "" "") (type $tag-type))
+
+  ;; Use all the types.
+  ;; CHECK:      (import "" "" (tag $imported (type $tag-type)))
+
+  ;; CHECK:      (global $tag-type (ref null $tag-type) (ref.null nofunc))
+  (global $tag-type (ref null $tag-type) (ref.null nofunc))
+  ;; CHECK:      (global $other-1 (ref null $other-1) (ref.null none))
+  (global $other-1 (ref null $other-1) (ref.null none))
+  ;; CHECK:      (global $other-2 (ref null $other-2) (ref.null none))
+  (global $other-2 (ref null $other-2) (ref.null none))
+)
+
+;; Exported tag.
+(module
+  ;; CHECK:      (type $tag-type (func))
+  (type $tag-type (func))
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $other-2 (struct (field i8)))
+
+  ;; CHECK:       (type $other-1 (struct))
+  (type $other-1 (struct))
+  (type $other-2 (struct (field i8)))
+
+  ;; CHECK:      (global $tag-type (ref null $tag-type) (ref.null nofunc))
+
+  ;; CHECK:      (global $other-1 (ref null $other-1) (ref.null none))
+
+  ;; CHECK:      (global $other-2 (ref null $other-2) (ref.null none))
+
+  ;; CHECK:      (tag $exported (type $tag-type))
+  (tag $exported (export "") (type $tag-type))
+
+  ;; Use all the types.
+  (global $tag-type (ref null $tag-type) (ref.null nofunc))
+  (global $other-1 (ref null $other-1) (ref.null none))
+  (global $other-2 (ref null $other-2) (ref.null none))
+)
+;; CHECK:      (export "" (tag $exported))