Reshape: guard the 9.22 reshape-mode attribute at runtime, not just at compile time

[YangXu1990uiuc]

CUDNN_ATTR_OPERATION_RESHAPE_MODE is set under #if (CUDNN_VERSION >= 92200) alone
(node/reshape.h:109). The compile-time guard is necessary but not sufficient: a frontend built
against >= 9.22 headers and run against an older runtime sets an attribute that runtime does not
know, and the failure takes down every graph containing a Reshape node — in practice all of
sdpa_backward, on 9.18 / 9.19 / 9.20 / 9.21.

Fix: nest a runtime check inside the existing compile-time guard, the idiom already used at
node/reduction.h:96-97.

Two decisions that aren't obvious from the diff:

• LOGICAL is rejected rather than silently skipped. Not setting the attribute reproduces an old
  runtime's behaviour exactly, because pre-9.22 reshape has one semantics and it is the view-only one
  (CUDNN_RESHAPE_VIEW_ONLY == 0, "no data movement") — also this frontend's default. But an
  explicit LOGICAL request cannot be honoured there, and downgrading it to view-only would change
  results, so it returns GRAPH_NOT_SUPPORTED.

• The check is spelled out instead of using NV_CUDNN_FE_DYNAMIC_CHECK_CUDNN_BACKEND_VERSION.
  That macro expands to nothing unless NV_CUDNN_FRONTEND_USE_DYNAMIC_LOADING is defined
  (cudnn_frontend_shim.h:213-215), so it would be a no-op in an ordinary C++ build — the exact
  configuration this needs to protect. Same caveat applies to sites that do use the macro
  (e.g. node/transpose.h:99); not addressed here.

g++ -fsyntax-only -std=c++17 clean; clang-format clean (pre-commit passed).

Summary by CodeRabbit

• Bug Fixes
  • Improved reshape operation compatibility across supported runtime versions.
  • View-only reshape operations now work correctly with older runtimes.
  • Logical reshape operations on runtimes that do not support them now report a clear “graph not supported” result instead of failing unexpectedly.

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📥 Commits

Reviewing files that changed from the base of the PR and between 504e34e and 3ff9747.

📒 Files selected for processing (1)

• include/cudnn_frontend/node/reshape.h

🚧 Files skipped from review as they are similar to previous changes (1)

• include/cudnn_frontend/node/reshape.h

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📝 Walkthrough

Walkthrough

Reshape operation creation gates mode attribute configuration on the cuDNN runtime version. Older runtimes support view-only reshapes without the attribute and reject logical reshapes. Runtimes 9.22 and newer retain explicit mode configuration.

Changes

Reshape runtime compatibility

Layer / File(s)	Summary
Version-gated reshape mode handling include/cudnn_frontend/node/reshape.h	Reshape creation checks the runtime version before setting CUDNN_ATTR_OPERATION_RESHAPE_MODE. Older runtimes omit the attribute for view-only reshapes and return GRAPH_NOT_SUPPORTED for logical reshapes.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: adding a runtime guard for the reshape-mode attribute.
Description check	✅ Passed	The description clearly explains the problem, solution, compatibility behavior, rationale, and testing results.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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