Fix NchwcTransformer null deref on node with unresolved schema

[tairenpiao]

Problem

On x86_64 with ORT_ENABLE_ALL, InferenceSession initialization crashes (SIGSEGV) inside NchwcTransformer for a model containing a Transpose → Cast(fp16→fp32) → MatMul chain on a 3D dynamic shape with a singleton dim. Stack bottoms out in graph_utils::IsSupportedOptypeVersionAndDomain.

Root cause

graph_utils::IsSupportedOptypeVersionAndDomain dereferences node.Op()->Deprecated() unconditionally. node.Op() can be nullptr when a node's schema is not resolved (e.g. a node added by an earlier transformer before the graph is re-resolved), so this is a null dereference.

Fix

Guard with node.Op() != nullptr before the deref — matching the existing pattern at graph.cc:3547. A node whose schema is unresolved cannot match a specific op, so returning false is correct. Adds a regression test that loads the reporter's minimal model at ORT_ENABLE_ALL.

Scope

The crash is x86_64-only (NCHWc enabled, MlasNchwcGetBlockSize() > 1). On other platforms the guard is a no-op and the test is a harmless smoke test.

Fixes #28392

[Copilot]

Pull request overview

Fixes a crash during InferenceSession::Initialize() on x86_64 when NchwcTransformer processes a graph containing nodes whose op schema has not been resolved yet (node.Op() == nullptr). The change hardens a shared graph utility predicate used by transformers to avoid a null dereference, and adds a regression test that loads a minimal repro model.

Changes:

• Add a null-check for node.Op() in graph_utils::IsSupportedOptypeVersionAndDomain before consulting OpSchema::Deprecated().
• Add a regression test that loads and initializes a minimal Transpose -> Cast(fp16->fp32) -> MatMul model at Level3 optimizations.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
onnxruntime/test/optimizer/nchwc_optimizer_test.cc	Adds a regression smoke test that loads the repro model and asserts session initialization succeeds.
onnxruntime/core/graph/graph_utils.cc	Guards node.Op()->Deprecated() with node.Op() != nullptr to prevent a null dereference when schemas are unresolved.

[tairenpiao]

Pulled node.Op() into a local op_schema and reused it. Thanks!