ggml-webgpu: add support for im2col (#22259)

* shader(im2col): implement the im2col shader

* shader(im2col): clean the formatting issues

* shader(im2col): clean the editorconfig checker warning

* fix(shader): address the workgroup issues of im2col and conv2d

ggml/src/ggml-webgpu/ggml-webgpu-shader-lib.hpp

@@ -281,6 +281,25 @@ struct ggml_webgpu_conv2d_pipeline_key_hash {
     }
 };
 
+/** Im2Col **/
+struct ggml_webgpu_im2col_pipeline_key {
+    ggml_type input_type;
+    ggml_type output_type;
+
+    bool operator==(const ggml_webgpu_im2col_pipeline_key & other) const {
+        return input_type == other.input_type && output_type == other.output_type;
+    }
+};
+
+struct ggml_webgpu_im2col_pipeline_key_hash {
+    size_t operator()(const ggml_webgpu_im2col_pipeline_key & key) const {
+        size_t seed = 0;
+        ggml_webgpu_hash_combine(seed, key.input_type);
+        ggml_webgpu_hash_combine(seed, key.output_type);
+        return seed;
+    }
+};
+
 /** Gated Delta Net **/
 struct ggml_webgpu_gated_delta_net_pipeline_key {
     int type;
@@ -833,6 +852,8 @@ class ggml_webgpu_shader_lib {
         soft_max_pipelines;
     std::unordered_map<ggml_webgpu_conv2d_pipeline_key, webgpu_pipeline, ggml_webgpu_conv2d_pipeline_key_hash>
         conv2d_pipelines;
+    std::unordered_map<ggml_webgpu_im2col_pipeline_key, webgpu_pipeline, ggml_webgpu_im2col_pipeline_key_hash>
+        im2col_pipelines;
 
     std::unordered_map<ggml_webgpu_rms_norm_mul_pipeline_key,
                        webgpu_pipeline,
@@ -2504,6 +2525,44 @@ class ggml_webgpu_shader_lib {
         return conv2d_pipelines[key];
     }
 
+    webgpu_pipeline get_im2col_pipeline(const ggml_webgpu_shader_lib_context & context) {
+        ggml_webgpu_im2col_pipeline_key key = {};
+        key.input_type                      = context.src1->type;
+        key.output_type                     = context.dst->type;
+
+        auto it = im2col_pipelines.find(key);
+        if (it != im2col_pipelines.end()) {
+            return it->second;
+        }
+
+        std::vector<std::string> defines;
+        std::string              variant = "im2col";
+
+        auto push_type_defines = [&](const char * prefix, ggml_type type) {
+            std::string s_prefix = prefix;
+            if (type == GGML_TYPE_F32) {
+                defines.push_back(s_prefix + "_F32");
+            } else if (type == GGML_TYPE_F16) {
+                defines.push_back(s_prefix + "_F16");
+            } else {
+                GGML_ABORT("Unsupported type for IM2COL shader");
+            }
+        };
+
+        push_type_defines("INPUT", key.input_type);
+        push_type_defines("OUTPUT", key.output_type);
+
+        defines.push_back(std::string("WG_SIZE=") + std::to_string(context.max_wg_size));
+
+        auto processed           = preprocessor.preprocess(wgsl_im2col, defines);
+        auto decisions           = std::make_shared<ggml_webgpu_generic_shader_decisions>();
+        decisions->wg_size       = context.max_wg_size;
+        webgpu_pipeline pipeline = ggml_webgpu_create_pipeline(device, processed, variant);
+        pipeline.context         = decisions;
+        im2col_pipelines[key]    = pipeline;
+        return im2col_pipelines[key];
+    }
+
   private:
     static webgpu_pipeline ggml_webgpu_create_pipeline(wgpu::Device & device,
                                                        std::string    shader_code,

ggml/src/ggml-webgpu/ggml-webgpu.cpp

@@ -979,25 +979,108 @@ static webgpu_encoded_op ggml_webgpu_conv_2d(webgpu_context & ctx,
         ggml_webgpu_make_tensor_bind_group_entry(ctx, 2, dst),
     };
 
-    uint32_t max_wg_size =
-        std::min((uint32_t) WEBGPU_MAX_WG_SIZE, ctx->global_ctx->capabilities.limits.maxComputeWorkgroupSizeX);
-    uint32_t wg_size =
-        std::min((uint32_t) ctx->global_ctx->capabilities.limits.maxComputeInvocationsPerWorkgroup, max_wg_size);
-
     ggml_webgpu_shader_lib_context shader_lib_ctx = {};
     shader_lib_ctx.src0                           = src0;
     shader_lib_ctx.src1                           = src1;
     shader_lib_ctx.dst                            = dst;
-    shader_lib_ctx.max_wg_size                    = wg_size;
+    shader_lib_ctx.max_wg_size = ctx->global_ctx->capabilities.limits.maxComputeInvocationsPerWorkgroup;
 
     webgpu_pipeline pipeline = ctx->shader_lib->get_conv2d_pipeline(shader_lib_ctx);
 
     auto * decisions = static_cast<ggml_webgpu_generic_shader_decisions *>(pipeline.context.get());
 
-    uint32_t n_out    = ggml_nelements(dst);
-    uint32_t total_wg = CEIL_DIV(n_out, decisions->wg_size);
-    uint32_t max_wg   = ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension;
-    uint32_t wg_x     = std::min(total_wg, max_wg);
+    uint32_t total_wg = CEIL_DIV((uint32_t) ggml_nelements(dst), decisions->wg_size);
+    uint32_t wg_x     = std::min(ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension, total_wg);
+    uint32_t wg_y     = CEIL_DIV(total_wg, wg_x);
+
+    return ggml_backend_webgpu_build(ctx, pipeline, params, entries, wg_x, wg_y);
+}
+
+static webgpu_encoded_op ggml_webgpu_im2col(webgpu_context & ctx,
+                                            ggml_tensor *    src0,
+                                            ggml_tensor *    src1,
+                                            ggml_tensor *    dst) {
+    const int32_t s0    = ggml_get_op_params_i32(dst, 0);
+    const int32_t s1    = ggml_get_op_params_i32(dst, 1);
+    const int32_t p0    = ggml_get_op_params_i32(dst, 2);
+    const int32_t p1    = ggml_get_op_params_i32(dst, 3);
+    const int32_t d0    = ggml_get_op_params_i32(dst, 4);
+    const int32_t d1    = ggml_get_op_params_i32(dst, 5);
+    const bool    is_2D = ggml_get_op_params_i32(dst, 6) == 1;
+
+    const uint32_t KW = src0->ne[0];
+    const uint32_t KH = is_2D ? src0->ne[1] : 1;
+    const uint32_t IC = is_2D ? src0->ne[2] : src0->ne[1];
+
+    const uint32_t IW = src1->ne[0];
+    const uint32_t IH = is_2D ? src1->ne[1] : 1;
+    const uint32_t N  = is_2D ? src1->ne[3] : src1->ne[2];
+
+    const uint32_t OW = dst->ne[1];
+    const uint32_t OH = is_2D ? dst->ne[2] : 1;
+
+    const uint32_t si0 = (uint32_t) (src1->nb[0] / ggml_type_size(src1->type));
+    const uint32_t si1 = is_2D ? (uint32_t) (src1->nb[1] / ggml_type_size(src1->type)) : 0;
+    const uint32_t si2 = is_2D ? (uint32_t) (src1->nb[2] / ggml_type_size(src1->type)) :
+                                 (uint32_t) (src1->nb[1] / ggml_type_size(src1->type));
+    const uint32_t si3 = is_2D ? (uint32_t) (src1->nb[3] / ggml_type_size(src1->type)) :
+                                 (uint32_t) (src1->nb[2] / ggml_type_size(src1->type));
+
+    const uint32_t so0 = (uint32_t) (dst->nb[0] / ggml_type_size(dst->type));
+    const uint32_t so1 = (uint32_t) (dst->nb[1] / ggml_type_size(dst->type));
+    const uint32_t so2 = is_2D ? (uint32_t) (dst->nb[2] / ggml_type_size(dst->type)) : 0;
+    const uint32_t so3 = is_2D ? (uint32_t) (dst->nb[3] / ggml_type_size(dst->type)) :
+                                 (uint32_t) (dst->nb[2] / ggml_type_size(dst->type));
+
+    std::vector<uint32_t> params = {
+        (uint32_t) (ggml_webgpu_tensor_misalignment(ctx, src1) / ggml_type_size(src1->type)),
+        (uint32_t) (ggml_webgpu_tensor_misalignment(ctx, dst) / ggml_type_size(dst->type)),
+
+        si0,
+        si1,
+        si2,
+        si3,
+        so0,
+        so1,
+        so2,
+        so3,
+
+        KW,
+        KH,
+        IC,
+
+        IW,
+        IH,
+        N,
+
+        OW,
+        OH,
+
+        (uint32_t) s0,
+        (uint32_t) s1,
+        (uint32_t) p0,
+        (uint32_t) p1,
+        (uint32_t) d0,
+        (uint32_t) d1,
+    };
+
+    std::vector<wgpu::BindGroupEntry> entries = {
+        ggml_webgpu_make_tensor_bind_group_entry(ctx, 0, src1),
+        ggml_webgpu_make_tensor_bind_group_entry(ctx, 1, dst),
+    };
+
+    ggml_webgpu_shader_lib_context shader_lib_ctx = {};
+    shader_lib_ctx.src0                           = src0;
+    shader_lib_ctx.src1                           = src1;
+    shader_lib_ctx.dst                            = dst;
+    shader_lib_ctx.max_wg_size = ctx->global_ctx->capabilities.limits.maxComputeInvocationsPerWorkgroup;
+
+    webgpu_pipeline pipeline = ctx->shader_lib->get_im2col_pipeline(shader_lib_ctx);
+
+    auto * decisions = static_cast<ggml_webgpu_generic_shader_decisions *>(pipeline.context.get());
+
+    uint32_t total_wg = CEIL_DIV((uint32_t) ggml_nelements(dst), decisions->wg_size);
+    uint32_t wg_x     = std::min(ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension, total_wg);
     uint32_t wg_y     = CEIL_DIV(total_wg, wg_x);
 
     return ggml_backend_webgpu_build(ctx, pipeline, params, entries, wg_x, wg_y);
@@ -2689,6 +2772,8 @@ static std::optional<webgpu_encoded_op> ggml_webgpu_encode(webgpu_context ctx,
             return ggml_webgpu_sum_rows(ctx, src0, node);
         case GGML_OP_CONV_2D:
             return ggml_webgpu_conv_2d(ctx, src0, src1, node);
+        case GGML_OP_IM2COL:
+            return ggml_webgpu_im2col(ctx, src0, src1, node);
         default:
             return std::nullopt;
     }
@@ -3802,6 +3887,10 @@ static bool ggml_backend_webgpu_device_supports_op(ggml_backend_dev_t dev, const
                           (src0->type == GGML_TYPE_F32 || src0->type == GGML_TYPE_F16) &&
                           (src1->type == GGML_TYPE_F32 || src1->type == GGML_TYPE_F16);
             break;
+        case GGML_OP_IM2COL:
+            supports_op = (op->type == GGML_TYPE_F32 || op->type == GGML_TYPE_F16) &&
+                          (src0->type == GGML_TYPE_F32 || src0->type == GGML_TYPE_F16);
+            break;
         case GGML_OP_SSM_CONV:
             supports_op = op->type == GGML_TYPE_F32;
             break;

ggml/src/ggml-webgpu/wgsl-shaders/im2col.wgsl

@@ -0,0 +1,101 @@
+#include "common_decls.tmpl"
+enable f16;
+
+@group(0) @binding(0)
+#if defined(INPUT_F32)
+var<storage, read_write> input: array<f32>;
+#elif defined(INPUT_F16)
+var<storage, read_write> input: array<f16>;
+#endif
+
+@group(0) @binding(1)
+#if defined(OUTPUT_F32)
+var<storage, read_write> output: array<f32>;
+#elif defined(OUTPUT_F16)
+var<storage, read_write> output: array<f16>;
+#endif
+
+struct Params {
+    offset_i: u32,
+    offset_o: u32,
+
+    // element strides
+    si0: u32, si1: u32, si2: u32, si3: u32,
+    so0: u32, so1: u32, so2: u32, so3: u32,
+
+    KW: u32, KH: u32, IC: u32,
+    IW: u32, IH: u32, N: u32,
+    OW: u32, OH: u32,
+
+    // stride
+    s0: u32, s1: u32,
+    // padding
+    p0: u32, p1: u32,
+    // dilation
+    d0: u32, d1: u32,
+}
+
+@group(0) @binding(2)
+var<uniform> params: Params;
+
+fn load_input(idx: u32) -> f32 {
+    #if defined(INPUT_F32)
+        return input[idx];
+    #elif defined(INPUT_F16)
+        return f32(input[idx]);
+    #endif
+}
+
+fn store_output(idx: u32, val: f32) {
+    #if defined(OUTPUT_F32)
+        output[idx] = val;
+    #elif defined(OUTPUT_F16)
+        output[idx] = f16(val);
+    #endif
+}
+
+@compute @workgroup_size(WG_SIZE)
+fn main(
+    @builtin(global_invocation_id) gid: vec3<u32>,
+    @builtin(num_workgroups) num_wg: vec3<u32>
+) {
+
+    let threads_per_group = u32(WG_SIZE);
+    let i_out = gid.x + (num_wg.x * threads_per_group) * gid.y;
+    let K = params.KW * params.KH * params.IC;
+    let M = params.OW * params.OH;
+    let total = K * M * params.N;
+
+    if (i_out >= total) {
+        return;
+    }
+
+    // decode (k, m, n)
+    var i = i_out;
+    let n = i / (K * M);
+    i = i % (K * M);
+    let m = i / K;
+    let k = i % K;
+
+    // decode (oh, ow)
+    let oh = m / params.OW;
+    let ow = m % params.OW;
+
+    // decode (kw, kh, ic)
+    let kw = k % params.KW;
+    let tmp = k / params.KW;
+    let kh = tmp % params.KH;
+    let ic = tmp / params.KH;
+
+    let iw_i32 = i32(ow * params.s0 + kw * params.d0) - i32(params.p0);
+    let ih_i32 = i32(oh * params.s1 + kh * params.d1) - i32(params.p1);
+
+    if (iw_i32 >= 0 && iw_i32 < i32(params.IW) && ih_i32 >= 0 && ih_i32 < i32(params.IH)) {
+        let iw = u32(iw_i32);
+        let ih = u32(ih_i32);
+        let in_idx = params.offset_i + iw * params.si0 + ih * params.si1 + ic * params.si2 + n * params.si3;
+        store_output(params.offset_o + k * params.so0 + ow * params.so1 + oh * params.so2 + n * params.so3, load_input(in_idx));
+    } else {
+        store_output(params.offset_o + k * params.so0 + ow * params.so1 + oh * params.so2 + n * params.so3, 0.0);
+    }
+}