Add weight layout transformation cache for Conv operator

Implement lazy weight layout transformation for WebGPU Conv kernel to
avoid redundant GPU transposes on every inference.

Key changes:
- Add WeightLayoutTransformCache to cache transformed weights by name
and format
- Implement TransformWeightLayout() helper using existing
TransposeKernel for OIHW->HWIO transformation
- Cache stored in WebGpuExecutionProvider, shared across all kernels

Author: jchen10

onnxruntime/core/providers/webgpu/compute_context.h

@@ -139,6 +139,13 @@ class ComputeContext final {
     return webgpu_context_.Run(*this, program);
   }
 
+  //
+  // Get the execution provider.
+  //
+  inline const WebGpuExecutionProvider& GetExecutionProvider() const {
+    return ep_;
+  }
+
  private:
   WebGpuContext& webgpu_context_;
   OpKernelContext& kernel_context_;

onnxruntime/core/providers/webgpu/nn/conv.cc

@@ -8,6 +8,8 @@
 #include "core/providers/webgpu/nn/grouped_conv.h"
 #include "core/providers/webgpu/webgpu_utils.h"
 #include "core/providers/webgpu/math/matmul.h"
+#include "core/providers/webgpu/weight_layout_transform.h"
+#include "core/providers/webgpu/webgpu_execution_provider.h"
 
 namespace onnxruntime {
 namespace webgpu {
@@ -25,6 +27,37 @@ Status TransposeKernel(ComputeContext& context, const Tensor* kernel, const Tens
   return Transpose::DoTranspose(context, perm, reshaped_kernel, *transposed_kernel);
 }
 
+template <bool is_channels_last, bool is_fused>
+Status Conv<is_channels_last, is_fused>::GetTransformedWeight(ComputeContext& context,
+                                                              const Tensor* original_weight,
+                                                              const Tensor*& transformed_weight) const {
+  // Return cached weight if already transformed
+  if (transformed_weight_) {
+    transformed_weight = transformed_weight_;
+    return Status::OK();
+  }
+
+  // If transformation was attempted but failed, return error
+  if (weight_transform_attempted_) {
+    return ORT_MAKE_STATUS(ONNXRUNTIME, FAIL, "Weight transformation previously failed");
+  }
+
+  weight_transform_attempted_ = true;
+
+  // Use the weight input name extracted during construction
+  ORT_ENFORCE(!weight_name_.empty(), "Weight input name must be available for transformation caching");
+
+  // Get cache from execution provider
+  auto& cache = context.GetExecutionProvider().GetWeightLayoutTransformCache();
+
+  // Transform weight to HWIO layout
+  ORT_RETURN_IF_ERROR(TransformWeightLayout(context, original_weight, weight_name_,
+                                            "hwio", cache, transformed_weight_));
+
+  transformed_weight = transformed_weight_;
+  return Status::OK();
+}
+
 template <bool is_channels_last, bool is_fused>
 Status Conv<is_channels_last, is_fused>::ComputeInternal(ComputeContext& context) const {
   bool has_bias = context.InputCount() > 2;
@@ -104,11 +137,11 @@ Status Conv<is_channels_last, is_fused>::ComputeInternal(ComputeContext& context
   auto pad1 = conv_attrs_.auto_pad == AutoPadType::NOTSET ? pads[1] : (pads[1] + pads[3] + auto_pad_adjust) / 2;
   std::vector<uint32_t> updated_pads{pad0, pad1};
   if (conv_attrs_.group > 1) {
-    Tensor transposed_kernel;
     if (is_channels_last) {
-      ORT_RETURN_IF_ERROR(TransposeKernel(context, kernel, kernel_shape, &transposed_kernel, perm));
-      inputs[1] = &transposed_kernel;
-      modified_input_output_shapes[1] = transposed_kernel.Shape();
+      const Tensor* kernel_to_use = nullptr;
+      ORT_RETURN_IF_ERROR(GetTransformedWeight(context, kernel, kernel_to_use));
+      inputs[1] = kernel_to_use;
+      modified_input_output_shapes[1] = kernel_to_use->Shape();
     }
     auto output_channels_per_group = output_channels / conv_attrs_.group;
     auto components = static_cast<int>(is_channels_last && output_channels_per_group >= 4 ? GetMaxComponents(output_channels) : 1);
@@ -138,17 +171,16 @@ Status Conv<is_channels_last, is_fused>::ComputeInternal(ComputeContext& context
 
   const auto same_size = is_channels_last && input_height == kernel_height && input_width == kernel_width && pads[0] == 0 && pads[1] == 0;
   if (same_size || (kernel_height == 1 && kernel_width == 1 && pads[0] == 0 && pads[1] == 0 && strides[0] == 1 && strides[1] == 1)) {
-    Tensor transposed_kernel;
     TensorShape input_reshape;
     TensorShape kernel_reshape;
     TensorShape matmul_output_shape;
     std::vector<const Tensor*> matmul_inputs;
     std::vector<TensorShape> matmul_input_reshapes;
     if (is_channels_last) {
-      // Transpose weights
-
-      ORT_RETURN_IF_ERROR(TransposeKernel(context, kernel, kernel_shape, &transposed_kernel, perm));
-      inputs[1] = &transposed_kernel;
+      // Transform weights to HWIO layout (cached on first inference)
+      const Tensor* kernel_to_use = nullptr;
+      ORT_RETURN_IF_ERROR(GetTransformedWeight(context, kernel, kernel_to_use));
+      inputs[1] = kernel_to_use;
       if (same_size) {
         const auto shared_dim = input_height * input_width * input_channels;
         input_reshape = TensorShape({1, batch, shared_dim});
@@ -160,7 +192,7 @@ Status Conv<is_channels_last, is_fused>::ComputeInternal(ComputeContext& context
         matmul_output_shape = TensorShape({batch, output_height * output_width, output_channels});
       }
       matmul_inputs.push_back(input);
-      matmul_inputs.push_back(&transposed_kernel);
+      matmul_inputs.push_back(kernel_to_use);
       matmul_input_reshapes.push_back(input_reshape);
       matmul_input_reshapes.push_back(kernel_reshape);
     } else {

onnxruntime/core/providers/webgpu/nn/conv.h

@@ -20,12 +20,26 @@ class Conv : public WebGpuKernel {
     if (is_fused) {
       ORT_ENFORCE(GetFusedActivationAttr(info, activation_).IsOK());
     }
+    // Extract weight input name (input index 1) for caching
+    const auto& input_defs = info.node().InputDefs();
+    if (input_defs.size() > 1 && input_defs[1]->Exists()) {
+      weight_name_ = input_defs[1]->Name();
+    }
   }
   Status ComputeInternal(ComputeContext& context) const override;
 
  protected:
   ConvAttributes conv_attrs_;
   Activation activation_;
+  std::string weight_name_;  // Name of weight input for cache key
+
+  // Cached transformed weight pointer (set on first inference)
+  mutable const Tensor* transformed_weight_ = nullptr;
+  mutable bool weight_transform_attempted_ = false;
+
+  // Get or create transformed weight (lazy transformation on first inference)
+  Status GetTransformedWeight(ComputeContext& context, const Tensor* original_weight,
+                              const Tensor*& transformed_weight) const;
 };
 
 Status TransposeKernel(ComputeContext& context, const Tensor* kernel, const TensorShape& kernel_shape, Tensor* transposed_kernel, const InlinedVector<size_t>& perm);

onnxruntime/core/providers/webgpu/webgpu_execution_provider.cc

@@ -800,7 +800,8 @@ WebGpuExecutionProvider::WebGpuExecutionProvider(int context_id,
       context_{context},
       preferred_data_layout_{config.data_layout},
       force_cpu_node_names_{std::move(config.force_cpu_node_names)},
-      enable_graph_capture_{config.enable_graph_capture} {
+      enable_graph_capture_{config.enable_graph_capture},
+      weight_layout_transform_cache_{std::make_unique<WeightLayoutTransformCache>()} {
   // If graph capture is enabled, create a dedicated buffer manager for graph mode
   if (enable_graph_capture_) {
     // Create buffer manager for graph capture mode with appropriate cache modes
@@ -948,6 +949,12 @@ std::optional<bool> WebGpuExecutionProvider::ShouldConvertDataLayoutForOp(std::s
 }
 
 WebGpuExecutionProvider::~WebGpuExecutionProvider() {
+  // Clear weight transform cache before releasing WebGPU resources
+  // This ensures cached GPU tensors are freed while BufferManager is still valid
+  if (weight_layout_transform_cache_) {
+    weight_layout_transform_cache_->Clear();
+  }
+
   // Release all resources associated with the captured graph
   if (!captured_commands_.empty()) {
     context_.ReleaseGraphResources(captured_commands_);

onnxruntime/core/providers/webgpu/webgpu_execution_provider.h

@@ -9,6 +9,7 @@
 #include "core/graph/constants.h"
 #include "core/providers/providers.h"
 #include "core/providers/webgpu/buffer_manager.h"
+#include "core/providers/webgpu/weight_layout_transform_cache.h"
 
 struct pthreadpool;
 namespace onnxruntime {
@@ -85,6 +86,11 @@ class WebGpuExecutionProvider : public IExecutionProvider {
   Status ReplayGraph(int graph_annotation_id) override;
   webgpu::BufferManager& BufferManager() const;
 
+  // Get weight layout transform cache
+  webgpu::WeightLayoutTransformCache& GetWeightLayoutTransformCache() const {
+    return *weight_layout_transform_cache_;
+  }
+
  private:
   bool IsGraphCaptureAllowed() const;
   void IncrementRegularRunCountBeforeGraphCapture();
@@ -105,6 +111,9 @@ class WebGpuExecutionProvider : public IExecutionProvider {
 
   // Store captured commands directly in the EP instead of in WebGpuContext
   std::vector<webgpu::CapturedCommandInfo> captured_commands_;
+
+  // Cache for transformed weights (e.g., OIHW -> HWIO)
+  std::unique_ptr<webgpu::WeightLayoutTransformCache> weight_layout_transform_cache_;
 };
 
 }  // namespace onnxruntime

onnxruntime/core/providers/webgpu/weight_layout_transform.cc

@@ -0,0 +1,67 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include "core/providers/webgpu/weight_layout_transform.h"
+#include "core/providers/webgpu/compute_context.h"
+#include "core/providers/webgpu/weight_layout_transform_cache.h"
+#include "core/providers/webgpu/nn/conv.h"  // For TransposeKernel
+
+namespace onnxruntime {
+namespace webgpu {
+
+Status TransformWeightLayout(
+    ComputeContext& context,
+    const Tensor* weight,
+    const std::string& weight_name,
+    const std::string& format_descriptor,
+    WeightLayoutTransformCache& cache,
+    /*out*/ const Tensor*& transformed_weight) {
+  // Check cache first
+  const auto* cached = cache.GetTransformedWeight(weight_name, format_descriptor);
+  if (cached != nullptr) {
+    transformed_weight = cached;
+    return Status::OK();
+  }
+
+  // Not in cache, need to transform
+
+  const auto& original_shape = weight->Shape();
+  auto num_dims = original_shape.NumDimensions();
+
+  // Dispatch transformation based on format
+  Tensor output_tensor;
+  if (format_descriptor == "hwio") {
+    // For 3D tensors, extend to 4D before transposing
+    TensorShape input_shape_for_transpose = original_shape;
+    if (num_dims == 3) {
+      // Extend OIW [O, I, W] to OIHW [O, I, 1, W]
+      TensorShapeVector extended_shape = original_shape.AsShapeVector();
+      extended_shape.insert(extended_shape.begin() + 2, 1);  // Insert H=1 at position 2
+      input_shape_for_transpose = TensorShape(extended_shape);
+    }
+
+    // Use existing TransposeKernel: OIHW [O,I,H,W] -> HWIO [H,W,I,O]
+    // Permutation: [2, 3, 1, 0] means output[i] = input[perm[i]]
+    // TransposeKernel creates the output tensor internally
+    const InlinedVector<size_t> perm = {2, 3, 1, 0};
+    ORT_RETURN_IF_ERROR(TransposeKernel(context, weight, input_shape_for_transpose,
+                                        &output_tensor, perm));
+  } else {
+    // Add more format implementations here
+    return ORT_MAKE_STATUS(ONNXRUNTIME, NOT_IMPLEMENTED,
+                           "Format not yet implemented: ", format_descriptor);
+  }
+
+  // Add to cache
+  cache.AddTransformedWeight(weight_name, format_descriptor, std::move(output_tensor));
+
+  // Return cached tensor
+  const auto* cached_result = cache.GetTransformedWeight(weight_name, format_descriptor);
+  ORT_ENFORCE(cached_result != nullptr, "Failed to cache transformed weight");
+  transformed_weight = cached_result;
+
+  return Status::OK();
+}
+
+}  // namespace webgpu
+}  // namespace onnxruntime

onnxruntime/core/providers/webgpu/weight_layout_transform.h

@@ -0,0 +1,27 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#pragma once
+
+#include "core/common/common.h"
+#include "core/framework/tensor.h"
+#include <string>
+
+namespace onnxruntime {
+namespace webgpu {
+
+class ComputeContext;
+class WeightLayoutTransformCache;
+
+// Transform weight tensor to specified format
+// Returns the transformed tensor (either from cache or newly created)
+Status TransformWeightLayout(
+    ComputeContext& context,
+    const Tensor* weight,
+    const std::string& weight_name,
+    const std::string& format_descriptor,
+    WeightLayoutTransformCache& cache,
+    /*out*/ const Tensor*& transformed_weight);
+
+}  // namespace webgpu
+}  // namespace onnxruntime

onnxruntime/core/providers/webgpu/weight_layout_transform_cache.cc

@@ -0,0 +1,36 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include "core/providers/webgpu/weight_layout_transform_cache.h"
+
+namespace onnxruntime {
+namespace webgpu {
+
+const Tensor* WeightLayoutTransformCache::GetTransformedWeight(
+    const std::string& weight_name,
+    const std::string& format_descriptor) const {
+  std::lock_guard<std::mutex> lock(mutex_);
+  std::string cache_key = MakeCacheKey(weight_name, format_descriptor);
+  auto it = cache_.find(cache_key);
+  if (it != cache_.end()) {
+    return &it->second;
+  }
+  return nullptr;
+}
+
+void WeightLayoutTransformCache::AddTransformedWeight(
+    const std::string& weight_name,
+    const std::string& format_descriptor,
+    Tensor&& tensor) {
+  std::lock_guard<std::mutex> lock(mutex_);
+  std::string cache_key = MakeCacheKey(weight_name, format_descriptor);
+  cache_[cache_key] = std::move(tensor);
+}
+
+void WeightLayoutTransformCache::Clear() {
+  std::lock_guard<std::mutex> lock(mutex_);
+  cache_.clear();
+}
+
+}  // namespace webgpu
+}  // namespace onnxruntime

onnxruntime/core/providers/webgpu/weight_layout_transform_cache.h

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#pragma once
+
+#include <unordered_map>
+#include <mutex>
+#include <string>
+#include "core/framework/tensor.h"
+#include "core/common/common.h"
+
+namespace onnxruntime {
+namespace webgpu {
+
+// Cache manager for transformed weights
+// Owned by WebGpuExecutionProvider
+class WeightLayoutTransformCache {
+ public:
+  WeightLayoutTransformCache() = default;
+  ~WeightLayoutTransformCache() = default;
+
+  // Get transformed weight from cache (nullptr if not found)
+  const Tensor* GetTransformedWeight(const std::string& weight_name,
+                                     const std::string& format_descriptor) const;
+
+  // Add transformed weight to cache
+  void AddTransformedWeight(const std::string& weight_name,
+                            const std::string& format_descriptor,
+                            Tensor&& tensor);
+
+  // Clear cache (must be called before BufferManager is destroyed)
+  void Clear();
+
+ private:
+  std::string MakeCacheKey(const std::string& weight_name,
+                           const std::string& format) const {
+    return weight_name + ":" + format;
+  }
+
+  mutable std::mutex mutex_;
+  std::unordered_map<std::string, Tensor> cache_;
+};
+
+}  // namespace webgpu
+}  // namespace onnxruntime