Add --no_transposed_cache CLI flag for export pipeline

[kimishpatel]

Stack from ghstack (oldest at bottom):

• temp changes to enable benchmarking on device via adb #18719
• Add xplat cxx_binary target for bench_transposed_cache benchmark #18718
• Add non-flash SDPA path gated by ET_USE_UNFUSED_SDPA #18717
• Add ONNX Runtime GQA-style SDPA benchmark #18716
• Add GEMM-based standard SDPA benchmark and fix custom_sdpa_out signature #18715
• Support separate K/V seq dim in custom_sdpa op #18714
• -> Add --no_transposed_cache CLI flag for export pipeline #18713
• Plumb transposed cache config through export pipeline #18712
• Add benchmarks for transposed vs standard KV cache layout #18711
• temp hack #18710
• Add support for transposed kv cache in all variants of custom kv cache #18709
• Add contig requirement to aot binding for llm custom ops #18708
• Add support for seq at dim=2 #18707
• Make kv cache update op support transposed cache #18706
• Add xplat cxx_binary target for bench_sdpa #18705
• Use unfused SDPA for short sequences (q_len <= 128 or kv_len <= 128) #18651
• Limit softmax to causally-valid elements in cpu_sdpa #18650
• Add quantized input support to cpu_sdpa #18649
• [Executorch] Add non-flash SDPA for decode #18648
• Add ONNX Runtime GQA-style SDPA benchmark #18647
• Add GEMM-based standard SDPA benchmark #18646
• Fix SLEEF preprocessor macro name to match ATen vec headers #18645

Add CLI argument to control transposed KV cache layout during export.
By default transposed cache is used (is_seq_at_dim_2=True). Pass
--no_transposed_cache to disable it for baseline comparison.

Differential Revision: D99677684

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/18713

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 14 New Failures, 2 Cancelled Jobs

As of commit af088ae with merge base fb1618e ():

NEW FAILURES - The following jobs have failed:

• pull / test-llama-runner-linux (fp32, xnnpack+custom+quantize_kv, linux.2xlarge, executorch-ubuntu-22.04... / linux-job (gh)
  AttributeError: 'CustomKVCache' object has no attribute 'is_seq_at_dim_2'
• pull / test-llama-runner-linux (fp32, xnnpack+custom+quantize_kv, linux.arm64.2xlarge, executorch-ubuntu... / linux-job (gh)
  AttributeError: 'CustomKVCache' object has no attribute 'is_seq_at_dim_2'
• pull / test-llama-runner-linux (fp32, xnnpack+quantize_kv, linux.2xlarge, executorch-ubuntu-22.04-clang12) / linux-job (gh)
  AttributeError: 'CustomKVCache' object has no attribute 'is_seq_at_dim_2'
• pull / test-llama-runner-linux (fp32, xnnpack+quantize_kv, linux.arm64.2xlarge, executorch-ubuntu-22.04-... / linux-job (gh)
  AttributeError: 'CustomKVCache' object has no attribute 'is_seq_at_dim_2'
• pull / test-lora-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 2a945dfc208831a5b05c1c98496a256430e901097bd9660b0a08022748d3be93 /exec failed with exit code 1
• pull / test-lora-multimethod-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 4af158d90be16f1d362e6faad0d9ca07d57d23fa83c50a69029f06ea38ece442 /exec failed with exit code 1
• pull / test-mcu-cortex-m-backend / linux-job (gh)
  RuntimeError: Command docker exec -t 65a023e7ea8dcb98c549f8211218cd94407ef8653588f3415bded6c0acb733d8 /exec failed with exit code 92
• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 3eafd95bb97ee1b8962d0bac12843315fae45b2d182f3b6525ff17458f808274 /exec failed with exit code 1
• pull / unittest / linux / linux-job (gh)
  examples/models/llama/tests/test_replace_kv_cache.py::TestReplaceKVCache::test_replace_quantized_kv_cache_with_quantized_ring_kv_cache
• pull / unittest / macos / macos-job (gh)
  examples/models/llama/tests/test_replace_kv_cache.py::TestReplaceKVCache::test_replace_quantized_kv_cache_with_quantized_ring_kv_cache
• pull / unittest-buck / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 1ad07b7eb397d33f4c6ed014eddb19b3c5d51f2ac2c0e406897ae052c1c6736f /exec failed with exit code 3
• pull / unittest-buck / macos / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 3
• pull / unittest-editable / linux / linux-job (gh)
  examples/models/llama/tests/test_replace_kv_cache.py::TestReplaceKVCache::test_replace_quantized_kv_cache_with_quantized_ring_kv_cache
• pull / unittest-editable / macos / macos-job (gh)
  examples/models/llama/tests/test_replace_kv_cache.py::TestReplaceKVCache::test_replace_quantized_kv_cache_with_quantized_ring_kv_cache

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• pull / unittest / windows / windows-job (gh)
• pull / unittest-editable / windows / windows-job (gh)

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.

[kimishpatel]

submitted by accident, not meant to land immedidately