Loosen conditions on MemoryPacking (#2205)

Allow MemoryPacking to run when there are no passive segments, even if
bulk memory is enabled.

Author: tlively

src/passes/MemoryPacking.cpp

@@ -28,12 +28,20 @@ struct MemoryPacking : public Pass {
   bool modifiesBinaryenIR() override { return false; }
 
   void run(PassRunner* runner, Module* module) override {
-    // Conservatively refuse to change segments if bulk memory is enabled to
-    // avoid invalidating segment indices or segment contents referenced from
+    if (!module->memory.exists) {
+      return;
+    }
+
+    // Conservatively refuse to change segments if any are passive to avoid
+    // invalidating segment indices or segment contents referenced from
     // memory.init instructions.
     // TODO: optimize in the presence of memory.init instructions
-    if (!module->memory.exists || module->features.hasBulkMemory()) {
-      return;
+    if (module->features.hasBulkMemory()) {
+      for (auto segment : module->memory.segments) {
+        if (segment.isPassive) {
+          return;
+        }
+      }
     }
 
     std::vector<Memory::Segment> packed;