[VitisAI] fix dangling pointer

[amd-genmingz]

Description

set the pointer to nullptr immediately after UnloadDynamicLibrary.

Motivation and Context

After unload library, set the function pointer to nullptr to avoid a dangling pointer. Otherwise, the following scenario may cause errors:

RegisterExecutionProviderLibrary()
SessionOptions::AppendExecutionProvider_VitisAI()

In this scenario, the OrtVitisAIEpAPI will call initialize_vitisai_ep once but call deinitialize_vitisai_ep twice. During deinitialization, functions deinitialize_onnxruntime_vitisai_ep are invoked, which leads to errors.

[adrianlizarraga]

Hi @amd-genmingz Could you please sync this branch with main to make the DML CI check pass?

[Copilot]

Pull request overview

This PR addresses a use-after-unload risk in the VitisAI EP loader by clearing cached function pointers immediately after unloading the onnxruntime_vitisai_ep dynamic library, preventing later accidental invocations of stale pointers.

Changes:

• Update OrtVitisAIEpAPI::Clear() to set all resolved function pointers to nullptr after UnloadDynamicLibrary.
• Ensure the deinitialization function pointer is cleared as part of shutdown to avoid double-deinit calling into unloaded code.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[amd-genmingz]

Hi @adrianlizarraga This request has been synchronized to main; please re-trigger CI checks.

[amd-genmingz]

Hi @adrianlizarraga @a-akoval Can we trigger CI and then proceed with the merge process?

[adrianlizarraga]

/azp run Linux QNN CI Pipeline,Win_TRT_Minimal_CUDA_Test_CI,Windows ARM64 QNN CI Pipeline,Windows GPU Doc Gen CI Pipeline

[azure-pipelines]

Azure Pipelines successfully started running 4 pipeline(s).

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.