Dai, Feng (Gerrit)

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Apr 16, 2026, 7:36:09 AMApr 16

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File-level comment, Patchset 3 (Latest):

Dai, Feng . resolved

@rei...@chromium.org @ningx...@intel.com PTAL, thanks!

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Apr 16, 2026, 1:27:07 PMApr 16

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File-level comment, Patchset 3 (Latest):

Dwayne Robinson . resolved

Thanks Bruce.

File services/webnn/tflite/graph_builder_tflite.cc

Line 8112, Patchset 3 (Latest): if (input_tensor_info.dimensions.size() == 5 ||

Dwayne Robinson . unresolved

(minor) Consider `> 4` rather than specifically `== 5`, since that semantically reflects the limit of the underlying API (rank 4) allows code to be more generic (not that rank 6 will be hit anyway, since op support limits prevents it).

File third_party/blink/web_tests/external/wpt/webnn/conformance_tests/prelu.https.any.js

Line 513, Patchset 3 (Latest): },

Dwayne Robinson . unresolved

Since [prelu](https://webmachinelearning.github.io/webnn/#api-mlgraphbuilder-prelu) is bidirectionally broadcastable, consider also a 1D input and 5D slope.

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Dai, Feng (Gerrit)

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Apr 16, 2026, 10:40:07 PM (14 days ago) Apr 16

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File services/webnn/tflite/graph_builder_tflite.cc

Line 8112, Patchset 3: if (input_tensor_info.dimensions.size() == 5 ||

Dwayne Robinson . resolved

(minor) Consider `> 4` rather than specifically `== 5`, since that semantically reflects the limit of the underlying API (rank 4) allows code to be more generic (not that rank 6 will be hit anyway, since op support limits prevents it).

Dai, Feng

👍
Updated. Please take another look. Thanks!

File third_party/blink/web_tests/external/wpt/webnn/conformance_tests/prelu.https.any.js

Line 513, Patchset 3: },

Dwayne Robinson . resolved

Since [prelu](https://webmachinelearning.github.io/webnn/#api-mlgraphbuilder-prelu) is bidirectionally broadcastable, consider also a 1D input and 5D slope.

Dai, Feng

Thanks @dwa...@microsoft.com!
I filed a separate issue https://issues.chromium.org/issues/503402055 to track it.

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Dwayne Robinson (Gerrit)

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Apr 16, 2026, 10:58:29 PM (14 days ago) Apr 16

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File-level comment, Patchset 4 (Latest):

Dwayne Robinson . resolved

👍

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Hu, Ningxin (Gerrit)

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Apr 20, 2026, 2:40:41 AM (11 days ago) Apr 20

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File services/webnn/tflite/graph_builder_tflite.cc

Line 917, Patchset 4 (Latest):

      // TFLite's native PReLU path is used for lower-rank tensors, and
      // SerializePrelu emulates rank-5 cases with element-wise ops to preserve
      // WebNN broadcasting semantics for the 5D conformance coverage.
      // https://source.chromium.org/chromium/chromium/src/+/main:third_party/tflite/src/tensorflow/lite/kernels/internal/reference/prelu.h

Hu, Ningxin . unresolved

inconsistent indentation.

Line 8122, Patchset 4 (Latest):

    ASSIGN_OR_RETURN(const TensorIndex zero_value_tensor_index,
                     SerializeTensorWithBuffer<float>(
                         /*buffer=*/std::array<float, 1>{0.0f},
                         /*dimensions=*/{}));

Hu, Ningxin . unresolved

Worth adding a comment explaining why only create float32 zero tensor, e.g. "Prelu input tensors are already dequantized to float32 by SerializeInputTensorInfo."

Line 8142, Patchset 4 (Latest):

    ASSIGN_OR_RETURN(const TensorIndex scaled_negative_tensor_index,
                     SerializeTemporaryTensorWithByteSizeCheck(
                         input_tensor_info.dimensions,
                         input_tensor_info.data_type));

Hu, Ningxin . unresolved

The `scaled_negative_tensor_index` temporary is allocated with `input_tensor_info.dimensions`, but after slope * min(x, 0), the result shape may be the broadcast of `slope_tensor_info.dimensions`. If the slope has a dimension larger than 1 where input has 1, the intermediate tensor shape would be wrong. Consider using `output_tensor_info.dimensions` and adding a test case.

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Dai, Feng (Gerrit)

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Apr 20, 2026, 9:38:10 PM (10 days ago) Apr 20

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File services/webnn/tflite/graph_builder_tflite.cc

Line 917, Patchset 4: // TFLite's native PReLU path is used for lower-rank tensors, and


      // SerializePrelu emulates rank-5 cases with element-wise ops to preserve
      // WebNN broadcasting semantics for the 5D conformance coverage.
      // https://source.chromium.org/chromium/chromium/src/+/main:third_party/tflite/src/tensorflow/lite/kernels/internal/reference/prelu.h

Hu, Ningxin . resolved

inconsistent indentation.

Dai, Feng

Done.
Please take another look at the new commit, thanks!

Line 8122, Patchset 4: ASSIGN_OR_RETURN(const TensorIndex zero_value_tensor_index,


                     SerializeTensorWithBuffer<float>(
                         /*buffer=*/std::array<float, 1>{0.0f},
                         /*dimensions=*/{}));

Hu, Ningxin . unresolved

Worth adding a comment explaining why only create float32 zero tensor, e.g. "Prelu input tensors are already dequantized to float32 by SerializeInputTensorInfo."

Dai, Feng

Thanks @ningx...@intel.com!
I added such explanation comment here.
Please take another look at the new commit, thanks!

Line 8142, Patchset 4:

    ASSIGN_OR_RETURN(const TensorIndex scaled_negative_tensor_index,
                     SerializeTemporaryTensorWithByteSizeCheck(
                         input_tensor_info.dimensions,
                         input_tensor_info.data_type));

Hu, Ningxin . unresolved

The `scaled_negative_tensor_index` temporary is allocated with `input_tensor_info.dimensions`, but after slope * min(x, 0), the result shape may be the broadcast of `slope_tensor_info.dimensions`. If the slope has a dimension larger than 1 where input has 1, the intermediate tensor shape would be wrong. Consider using `output_tensor_info.dimensions` and adding a test case.

Dai, Feng

Good catch! 👍
Updated in new commit, please take another look, thanks!

If the slope has a dimension larger than 1 where input has 1, the intermediate tensor shape would be wrong. Consider using `output_tensor_info.dimensions` and adding a test case.

Added such a test case "prelu float32 broadcast 5D x 5D slope with expanded output shape" using input of `[2, 1, 1, 2, 3]` shape with slope of `[1, 2, 1, 1, 1]` shape, current this test would run `Fail`, since there's this issue https://issues.chromium.org/issues/503402055 -
Support bidirectionally broadcast the shapes of input and slope for prelu operator, I will fix it in another following CL later.

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Hu, Ningxin (Gerrit)

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Apr 21, 2026, 12:25:46 AM (10 days ago) Apr 21

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File-level comment, Patchset 5 (Latest):

Hu, Ningxin . resolved

LGTM with a comment

File services/webnn/tflite/graph_builder_tflite.cc

Line 8122, Patchset 4:

    ASSIGN_OR_RETURN(const TensorIndex zero_value_tensor_index,
                     SerializeTensorWithBuffer<float>(
                         /*buffer=*/std::array<float, 1>{0.0f},
                         /*dimensions=*/{}));

Hu, Ningxin . resolved

Worth adding a comment explaining why only create float32 zero tensor, e.g. "Prelu input tensors are already dequantized to float32 by SerializeInputTensorInfo."

Dai, Feng

Thanks @ningx...@intel.com!
I added such explanation comment here.
Please take another look at the new commit, thanks!

Hu, Ningxin

Acknowledged

Line 8142, Patchset 4:

    ASSIGN_OR_RETURN(const TensorIndex scaled_negative_tensor_index,
                     SerializeTemporaryTensorWithByteSizeCheck(
                         input_tensor_info.dimensions,
                         input_tensor_info.data_type));

Hu, Ningxin . resolved

The `scaled_negative_tensor_index` temporary is allocated with `input_tensor_info.dimensions`, but after slope * min(x, 0), the result shape may be the broadcast of `slope_tensor_info.dimensions`. If the slope has a dimension larger than 1 where input has 1, the intermediate tensor shape would be wrong. Consider using `output_tensor_info.dimensions` and adding a test case.

Dai, Feng

Good catch! 👍
Updated in new commit, please take another look, thanks!
If the slope has a dimension larger than 1 where input has 1, the intermediate tensor shape would be wrong. Consider using `output_tensor_info.dimensions` and adding a test case.
Added such a test case "prelu float32 broadcast 5D x 5D slope with expanded output shape" using input of `[2, 1, 1, 2, 3]` shape with slope of `[1, 2, 1, 1, 1]` shape, current this test would run `Fail`, since there's this issue https://issues.chromium.org/issues/503402055 -
Support bidirectionally broadcast the shapes of input and slope for prelu operator, I will fix it in another following CL later.

Hu, Ningxin

Acknowledged

Line 8148, Patchset 5 (Latest): input_tensor_info.data_type));

Hu, Ningxin . unresolved

Use `output_tensor_info` as well.

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Dai, Feng (Gerrit)

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Apr 21, 2026, 1:09:04 AM (10 days ago) Apr 21

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File services/webnn/tflite/graph_builder_tflite.cc

Line 8148, Patchset 5: input_tensor_info.data_type));

Hu, Ningxin . resolved

Use `output_tensor_info` as well.

Dai, Feng

Updated.Thanks @ningx...@intel.com!

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Apr 21, 2026, 1:23:01 AM (10 days ago) Apr 21

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Hu, Ningxin . resolved

LGTM

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Apr 22, 2026, 9:20:51 AM (8 days ago) Apr 22

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Gentle ping @rei...@chromium.org Please take a review when you're available. Thanks!

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Apr 27, 2026, 9:00:00 PM (3 days ago) Apr 27

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Apr 27, 2026, 9:38:17 PM (3 days ago) Apr 27

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Dai, Feng . resolved

Thanks all for your reviewing!
I'm going to submit this CL.

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Dai, Feng . resolved

Last there're trybot's failures when submitting CL, then I rebasline and rebase code to make all trybots pass. Now the failure results in expected files are due to this issue [#503402055 - Support bidirectionally broadcast the shapes of input and slope for prelu operator](https://issues.chromium.org/issues/503402055) that I'm working on a follow-up CL.
@ningx...@intel.com @rei...@chromium.org Please take another look, thanks!

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LGTM

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webnn: emulate rank-5 prelu's input tensors in TFLite [chromium/src : main]

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