[Wasm GC] ReFinalize when needed in SimplifyGlobals (#5682)

2 files changed, 56 insertions, 4 deletions

diff --git a/src/passes/SimplifyGlobals.cpp b/src/passes/SimplifyGlobals.cpp
index f9bccab23..97e91bbab 100644
--- a/src/passes/SimplifyGlobals.cpp
+++ b/src/passes/SimplifyGlobals.cpp
@@ -328,6 +328,10 @@ struct ConstantGlobalApplier
   : public WalkerPass<
       LinearExecutionWalker<ConstantGlobalApplier,
                             UnifiedExpressionVisitor<ConstantGlobalApplier>>> {
+  using super = WalkerPass<
+    LinearExecutionWalker<ConstantGlobalApplier,
+                          UnifiedExpressionVisitor<ConstantGlobalApplier>>>;
+
   bool isFunctionParallel() override { return true; }
 
   ConstantGlobalApplier(NameSet* constantGlobals, bool optimize)
@@ -337,6 +341,16 @@ struct ConstantGlobalApplier
     return std::make_unique<ConstantGlobalApplier>(constantGlobals, optimize);
   }
 
+  bool refinalize = false;
+
+  void replaceCurrent(Expression* rep) {
+    if (rep->type != getCurrent()->type) {
+      // This operation will change the type, so refinalize.
+      refinalize = true;
+    }
+    super::replaceCurrent(rep);
+  }
+
   void visitExpression(Expression* curr) {
     if (auto* set = curr->dynCast<GlobalSet>()) {
       if (Properties::isConstantExpression(set->value)) {
@@ -386,10 +400,15 @@ struct ConstantGlobalApplier
   }
 
   void visitFunction(Function* curr) {
-    if (replaced && optimize) {
-      PassRunner runner(getPassRunner());
-      runner.addDefaultFunctionOptimizationPasses();
-      runner.runOnFunction(curr);
+    if (replaced) {
+      if (refinalize) {
+        ReFinalize().walkFunctionInModule(curr, this->getModule());
+      }
+      if (optimize) {
+        PassRunner runner(getPassRunner());
+        runner.addDefaultFunctionOptimizationPasses();
+        runner.runOnFunction(curr);
+      }
     }
   }
 
diff --git a/test/lit/passes/simplify-globals-gc.wast b/test/lit/passes/simplify-globals-gc.wast
new file mode 100644
index 000000000..da49cdf61
--- /dev/null
+++ b/test/lit/passes/simplify-globals-gc.wast
@@ -0,0 +1,33 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+;; NOTE: This test was ported using port_passes_tests_to_lit.py and could be cleaned up.
+
+;; RUN: foreach %s %t wasm-opt --simplify-globals -all -S -o - | filecheck %s
+
+(module
+ ;; CHECK:      (type $A (func))
+ (type $A (func))
+
+ ;; CHECK:      (global $global$0 funcref (ref.func $func))
+ (global $global$0 (mut funcref) (ref.func $func))
+
+ ;; CHECK:      (elem declare func $func)
+
+ ;; CHECK:      (func $func (type $A)
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (ref.cast $A
+ ;; CHECK-NEXT:    (ref.func $func)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $func
+  (drop
+   (ref.cast null $A
+    ;; This global can be replaced with a ref.func of $func. That has a more
+    ;; refined type, so we should refinalize (if we do not, then the ref.cast
+    ;; will fail to validate as it must become a non-nullable cast).
+    (global.get $global$0)
+   )
+  )
+ )
+)
+