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, 12 insertions, 11 deletions

diff --git a/src/wasm/literal.cpp b/src/wasm/literal.cpp
index a7c14fdb6..d309be308 100644
--- a/src/wasm/literal.cpp
+++ b/src/wasm/literal.cpp
@@ -139,7 +139,11 @@ Literals Literal::makeZero(Type type) {
 Literal Literal::makeSingleZero(Type type) {
   assert(type.isSingle());
   if (type.isRef()) {
-    return makeNull(type);
+    if (type == Type::i31ref) {
+      return makeI31(0);
+    } else {
+      return makeNull(type);
+    }
   } else {
     return makeFromInt32(0, type);
   }
@@ -438,7 +442,7 @@ std::ostream& operator<<(std::ostream& o, Literal literal) {
       o << "eqref(null)";
       break;
     case Type::i31ref:
-      o << "i31ref(" << literal.geti31(false) << ")";
+      o << "i31ref(" << literal.geti31() << ")";
       break;
     case Type::unreachable:
       WASM_UNREACHABLE("invalid type");
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index c03a9b281..c857b202c 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -217,18 +217,15 @@ const char* getExpressionName(Expression* curr) {
 }
 
 Literal getSingleLiteralFromConstExpression(Expression* curr) {
-  if (auto* c = curr->dynCast<Const>()) {
-    return c->value;
-  } else if (auto* n = curr->dynCast<RefNull>()) {
-    return Literal::makeNull(n->type);
-  } else if (auto* r = curr->dynCast<RefFunc>()) {
-    return Literal::makeFunc(r->func);
-  } else {
-    WASM_UNREACHABLE("Not a constant expression");
-  }
+  // TODO: Do we need this function given that Properties::getSingleLiteral
+  // (currently) does the same?
+  assert(Properties::isConstantExpression(curr));
+  return Properties::getSingleLiteral(curr);
 }
 
 Literals getLiteralsFromConstExpression(Expression* curr) {
+  // TODO: Do we need this function given that Properties::getLiterals
+  // (currently) does the same?
   if (auto* t = curr->dynCast<TupleMake>()) {
     Literals values;
     for (auto* operand : t->operands) {