[js/webgpu] Optimize Expand

Use components = 4 if possible.

llama3.2-1B becomes 20 tokens/s from 18 tokens/s on my iGPUs.

Author: qjia7

js/web/lib/wasm/jsep/webgpu/ops/expand.ts

@@ -48,11 +48,18 @@ const createExpandProgramInfo = (inputs: readonly TensorView[]): ProgramInfo =>
   const shape = Array.from(inputs[1].getBigInt64Array(), Number);
   const outputShape: number[] = calculateOutputShape(inputShape, shape);
   const dataType = inputs[0].dataType;
-  const components = dataType === DataType.bool ? 4 : 1;
+  const isBoolOrScalar = dataType === DataType.bool || ShapeUtil.size(inputShape) === 1;
+  const iComponents =
+    dataType === DataType.bool ? 4 : inputShape.length > 0 && inputShape[inputShape.length - 1] % 4 === 0 ? 4 : 1;
+  const components = isBoolOrScalar
+    ? 4
+    : outputShape.length > 0 && outputShape[outputShape.length - 1] % 4 === 0
+      ? 4
+      : 1;
   const outputSize = Math.ceil(ShapeUtil.size(outputShape) / components);
 
   const getShaderSource = (shaderHelper: ShaderHelper) => {
-    const input = inputVariable('input', dataType, inputShape.length, components);
+    const input = inputVariable('input', dataType, inputShape.length, iComponents);
     const output = outputVariable('output', dataType, outputShape.length, components);
     let assignment: string;
     if (dataType === DataType.bool) {
@@ -74,9 +81,10 @@ const createExpandProgramInfo = (inputs: readonly TensorView[]): ProgramInfo =>
       }`;
     } else {
       assignment = `
-        let outputIndices = ${output.offsetToIndices('global_idx')};
+        let outputIndices = ${output.offsetToIndices(`global_idx * ${components}`)};
         let inputOffset = ${input.broadcastedIndicesToOffset('outputIndices', output)};
-        ${output.setByOffset('global_idx', input.getByOffset('inputOffset'))}
+        let data = ${output.type.value}(${input.getByOffset(`inputOffset / ${iComponents}`)});
+        ${output.setByOffset('global_idx', 'data')}
       }`;
     }
     return `
@@ -92,7 +100,7 @@ const createExpandProgramInfo = (inputs: readonly TensorView[]): ProgramInfo =>
   ];
   return {
     name: 'Expand',
-    shaderCache: { hint: `${outputShape.length}`, inputDependencies: ['rank'] },
+    shaderCache: { hint: `${outputShape.length};${iComponents}${components}`, inputDependencies: ['rank'] },
     getShaderSource,
     getRunData: () => ({
       outputs: [{ dims: outputShape, dataType: inputs[0].dataType }],

js/web/test/data/ops/expand.jsonc

@@ -134,6 +134,56 @@
             "type": "float32"
           }
         ]
+      },
+      {
+        "name": "Expand in components = 1, out components = 4",
+        "inputs": [
+          {
+            "data": [1, 2, 3, 4, 5, 6],
+            "dims": [3, 2, 1],
+            "type": "float32"
+          },
+          {
+            "data": [3, 1, 8],
+            "dims": [3],
+            "type": "int64"
+          }
+        ],
+        "outputs": [
+          {
+            "data": [
+              1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5,
+              5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6
+            ],
+            "dims": [3, 2, 8],
+            "type": "float32"
+          }
+        ]
+      },
+      {
+        "name": "Expand in components = 4, out components = 4",
+        "inputs": [
+          {
+            "data": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16],
+            "dims": [1, 1, 2, 8],
+            "type": "float32"
+          },
+          {
+            "data": [2, 1, 8],
+            "dims": [3],
+            "type": "int64"
+          }
+        ],
+        "outputs": [
+          {
+            "data": [
+              1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+              16
+            ],
+            "dims": [1, 2, 2, 8],
+            "type": "float32"
+          }
+        ]
       }
     ]
   },