[ExecuTorch][WebGPU] Port repeat by JCNTH · Pull Request #21168 · pytorch/executorch

JCNTH · 2026-07-22T22:30:40Z

Stack from ghstack (oldest at bottom):

Ports aten.repeat.default as a per-element tiling gather, mirroring the landed permute/flip index-transform (dual-TensorMeta, 2D-fold dispatch). repeat is pure data movement, so it maps each output element to its source via a per-dim modulo and copies — no fp compute.

Key changes:

runtime/ops/repeat/{Repeat.cpp, repeat.wgsl} (+ generated repeat_wgsl.h) — per out flat idx: unravel via out_meta.strides, in_coord = out_coord % in_meta.sizes[in_d], ravel via in_meta.strides, output[out] = input[in]; registered aten.repeat.default.
CMakeLists.txt — runtime/ops/repeat/Repeat.cpp in WEBGPU_SRCS.

Mirrors Vulkan glsl/repeat_buffer.glsl (in_tidx[d] = out_tidx[d] % size_at(in_meta, d)). Vulkan's innermost-first BufferMetadata auto-aligns a shorter input; WebGPU's NCHW TensorMeta makes the right-alignment explicit via offset = out_ndim - in_ndim (leading d < offset dims are pure prepends, contributing 0). No repeats-arg read needed: the repeated out dims are baked in by export, so the tiling is recoverable from shapes alone. No int dtype-guard (bit-preserving movement, like flip); the nbytes != numel*4 guard rejects int64/fp16.
@exported-using-ghexport

Differential Revision: D112257679

[ghstack-poisoned]

pytorch-bot · 2026-07-22T22:30:43Z

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/21168

📄 Preview Python docs built from this PR

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❌ 14 New Failures, 17 Pending, 11 Unrelated Failures

As of commit 21dc925 with merge base 4a26c64 ():

NEW FAILURES - The following jobs have failed:

Build Presets / windows (pybind) / build (gh)
Build Presets / windows (windows) / build (gh)
pull / test-models-linux (emformer_join, xnnpack-quantization-delegation, linux.4xlarge.memory) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-models-linux (ic4, portable, linux.4xlarge.memory) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-models-linux (llama3_2_vision_encoder, portable, linux.4xlarge.memory) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-models-linux (w2l, portable, linux.4xlarge.memory) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-models-linux-basic (mv3, xnnpack-quantization-delegation, cmake, linux.arm64.2xlarge, execut... / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-parakeet-xnnpack-linux / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
pull / test-voxtral-realtime-xnnpack-linux / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
Test ARM Backend / test-arm / test-backend-linux (arm_vgf_fp, models) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
Test ARM Backend / test-arm / test-backend-linux (arm_vgf_fp, operators) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
Test QNN Windows MSVC build / build-qnn-windows-msvc / windows-job (gh)
Can't find 'action.yml', 'action.yaml' or 'Dockerfile' under 'C:\actions-runner\_work\executorch\executorch\test-infra\.github\actions\teardown-windows'. Did you forget to run actions/checkout before running your local action?
Test WebGPU Backend / test-webgpu / test-backend-linux (webgpu, models) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory
Test XNNPACK Backend / test-xnnpack / test-backend-linux (xnnpack, operators) / linux-job (gh)
An error occurred trying to start process '/usr/bin/bash' with working directory '/home/ec2-user/actions-runner/_work/executorch/executorch/pytorch/executorch'. No such file or directory

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

pull / test-models-linux (emformer_join, portable, linux.4xlarge.memory) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
pull / test-models-linux (ic4, xnnpack-quantization-delegation, linux.4xlarge.memory) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
pull / test-models-linux (phi_4_mini, portable, linux.4xlarge.memory) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
pull / unittest / windows / windows-job (gh) (matched win rule in flaky-rules.json)
Can't find 'action.yml', 'action.yaml' or 'Dockerfile' under 'C:\actions-runner\_work\executorch\executorch\test-infra\.github\actions\teardown-windows'. Did you forget to run actions/checkout before running your local action?
pull / unittest-editable / windows / windows-job (gh) (detected as infra flaky with no log or failing log classifier)
Test ARM Backend / test-arm / test-backend-linux (arm_tosa_fp, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
Test ARM Backend / test-arm / test-backend-linux (arm_tosa_fp, operators) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
Test Vulkan Backend / test-vulkan / test-backend-linux (vulkan, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
Test Vulkan Backend / test-vulkan / test-backend-linux (vulkan, operators) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
Test WebGPU Backend / test-webgpu / test-backend-linux (webgpu, operators) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
Test XNNPACK Backend / test-xnnpack / test-backend-linux (xnnpack, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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github-actions · 2026-07-22T22:31:31Z

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psiddh

Approving full WebGPU stack

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[ExecuTorch][WebGPU] Port repeat#21168

[ExecuTorch][WebGPU] Port repeat#21168
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🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/21168

❌ 14 New Failures, 17 Pending, 11 Unrelated Failures

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