[Bugfix] Adjust role assignment in warp specialization based on read access (#647)

* [Bugfix] Adjust role assignment in warp specialization based on read access

- Updated the role assignment logic in `warp_specialized_rewriter.cc` to set the role to `kConsumer` when no reads are detected, ensuring correct behavior in memory access scenarios.

* Apply suggestion from @gemini-code-assist[bot]
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

---------
Co-authored-by: Lei Wang <34334180+LeiWang1999@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

src/transform/warp_specialized_rewriter.cc

@@ -129,6 +129,8 @@ public:
     auto access = GetBlockReadWriteRegion(block, buffer_data_to_buffer_);
     auto reads = access[0];
     Role role = Role::kProducer;
+    if (reads.empty())
+      role = Role::kConsumer;
     for (auto read : reads) {
       if (read->buffer.scope() != "global") {
         role = Role::kConsumer;