fix: simplify redundant softmax version condition

[andrewwhitecdw]

This PR addresses the following issue in transformer_engine/common/fused_attn/fused_attn.cpp: simplify redundant softmax version condition.

Changes

• transformer_engine/common/fused_attn/fused_attn.cpp: simplify redundant softmax version condition.

Details

--- a/transformer_engine/common/fused_attn/fused_attn.cpp
+++ b/transformer_engine/common/fused_attn/fused_attn.cpp
@@ -1,6 +1,5 @@
-        // softmax type
-        // pre-9.13.1: vanilla
-        // 9.13.1+: vanilla, off-by-one, learnable
-        (cudnn_runtime_version >= 91301 ||
-         (cudnn_runtime_version < 91301 &&
-          softmax_type == NVTE_Softmax_Type::NVTE_VANILLA_SOFTMAX)) &&
+        // softmax type
+        // pre-9.13.1: vanilla
+        // 9.13.1+: vanilla, off-by-one, learnable
+        (cudnn_runtime_version >= 91301 ||
+         softmax_type == NVTE_Softmax_Type::NVTE_VANILLA_SOFTMAX) &&

Tests

Let me know if you want tests added for this fix or not.

[greptile-apps]

Greptile Summary

This PR simplifies a redundant cuDNN-version condition without changing fused-attention backend selection behavior.

• Removes an unnecessary cudnn_runtime_version < 91301 check.
• Preserves vanilla-only softmax support before cuDNN 9.13.1 and all supported softmax types from 9.13.1 onward.

Confidence Score: 5/5

The PR appears safe to merge because the simplified predicate is equivalent to the original for all version and softmax-type combinations.

The change removes a redundant comparison while preserving the exact set of inputs that select the fused-attention backend.

Important Files Changed

Filename	Overview
transformer_engine/common/fused_attn/fused_attn.cpp	Simplifies the softmax compatibility predicate to a Boolean-equivalent expression with no observable behavior change.

_{Reviews (1): Last reviewed commit: "fix: simplify redundant softmax version ..." | Re-trigger Greptile}

[cyanguwa]

Please fix the DCO for this PR. Thanks.