[wasm] reuse the first compiled module

test/mjsunit/wasm/compiled-module-management.js

Index: test/mjsunit/wasm/compiled-module-management.js
diff --git a/test/mjsunit/wasm/compiled-module-management.js b/test/mjsunit/wasm/compiled-module-management.js
new file mode 100644
index 0000000000000000000000000000000000000000..5b64e00f4139e8993ed28ce62a8b4aab62aa3c5a
--- /dev/null
+++ b/test/mjsunit/wasm/compiled-module-management.js
@@ -0,0 +1,50 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// TODO (mtrofin): re-enable ignition (v8:5345)
+// Flags: --no-ignition --no-ignition-staging
+// Flags: --expose-wasm --expose-gc --allow-natives-syntax
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+
+(function CompiledModuleInstancesAreGCed() {
+  var builder = new WasmModuleBuilder();
+
+  builder.addMemory(1,1, true);
+  builder.addImport("getValue", kSig_i);
+  builder.addFunction("f", kSig_i)
+    .addBody([
+      kExprCallImport, kArity0, 0
+    ]).exportFunc();
+
+  var module = new WebAssembly.Module(builder.toBuffer());
+  %ValidateWasmModuleState(module);
+  %ValidateWasmInstancesChain(module, 0);
+  var i1 = new WebAssembly.Instance(module, {getValue: () => 1});
+  %ValidateWasmInstancesChain(module, 1);
+  var i2 = new WebAssembly.Instance(module, {getValue: () => 2});
+  %ValidateWasmInstancesChain(module, 2);
+  var i3 = new WebAssembly.Instance(module, {getValue: () => 3});
+  %ValidateWasmInstancesChain(module, 3);
+
+  assertEquals(1, i1.exports.f());
+  i1 = null;
+  gc();
+  %ValidateWasmInstancesChain(module, 2);
+  assertEquals(3, i3.exports.f());
+  i3 = null;
+  gc();
+  %ValidateWasmInstancesChain(module, 1);
+  assertEquals(2, i2.exports.f());
+  i2 = null;
+  gc();
+  %ValidateWasmModuleState(module);
+  var i4 = new WebAssembly.Instance(module, {getValue: () => 4});
+  assertEquals(4, i4.exports.f());
+  module = null;
+  gc();
+  %ValidateWasmOrphanedInstance(i4);
+})();