GC: Fuzzing support for i31 (#3169)

Integrates `i31ref` types and instructions into the fuzzer, by assuming that `(i31.new (i32.const N))` is constant and hence suitable to be used in global initializers.

2 files changed, 15 insertions, 9 deletions

diff --git a/src/ir/global-utils.h b/src/ir/global-utils.h
index b575d6952..7dc4c6af3 100644
--- a/src/ir/global-utils.h
+++ b/src/ir/global-utils.h
@@ -56,15 +56,13 @@ getGlobalInitializedToImport(Module& wasm, Name module, Name base) {
 inline bool canInitializeGlobal(const Expression* curr) {
   if (auto* tuple = curr->dynCast<TupleMake>()) {
     for (auto* op : tuple->operands) {
-      if (!op->is<Const>() && !op->is<RefNull>() &&
-          !op->is<RefFunc>() & !op->is<GlobalGet>()) {
+      if (!Properties::isSingleConstantExpression(op) && !op->is<GlobalGet>()) {
         return false;
       }
     }
     return true;
   }
-  return curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>() ||
-         curr->is<GlobalGet>();
+  return Properties::isSingleConstantExpression(curr) || curr->is<GlobalGet>();
 }
 
 } // namespace GlobalUtils
diff --git a/src/ir/properties.h b/src/ir/properties.h
index 56723631a..d0495f4a9 100644
--- a/src/ir/properties.h
+++ b/src/ir/properties.h
@@ -79,13 +79,18 @@ inline bool isNamedControlFlow(Expression* curr) {
   return false;
 }
 
+inline bool isSingleConstantExpression(const Expression* curr) {
+  return curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>() ||
+         (curr->is<I31New>() && curr->cast<I31New>()->value->is<Const>());
+}
+
 inline bool isConstantExpression(const Expression* curr) {
-  if (curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>()) {
+  if (isSingleConstantExpression(curr)) {
     return true;
   }
   if (auto* tuple = curr->dynCast<TupleMake>()) {
     for (auto* op : tuple->operands) {
-      if (!op->is<Const>() && !op->is<RefNull>() && !op->is<RefFunc>()) {
+      if (!isSingleConstantExpression(op)) {
         return false;
       }
     }
@@ -101,13 +106,16 @@ inline Literal getSingleLiteral(const Expression* curr) {
     return Literal(n->type);
   } else if (auto* r = curr->dynCast<RefFunc>()) {
     return Literal(r->func);
-  } else {
-    WASM_UNREACHABLE("non-constant expression");
+  } else if (auto* i = curr->dynCast<I31New>()) {
+    if (auto* c = i->value->dynCast<Const>()) {
+      return Literal::makeI31(c->value.geti32());
+    }
   }
+  WASM_UNREACHABLE("non-constant expression");
 }
 
 inline Literals getLiterals(const Expression* curr) {
-  if (curr->is<Const>() || curr->is<RefNull>() || curr->is<RefFunc>()) {
+  if (isSingleConstantExpression(curr)) {
     return {getSingleLiteral(curr)};
   } else if (auto* tuple = curr->dynCast<TupleMake>()) {
     Literals literals;