Cuda implementation of antialias kernel

Author: tdakhran

ggml/src/ggml-cpu/ops.cpp

@@ -7425,10 +7425,10 @@ static void ggml_compute_forward_upscale_f32(
                         const float x = ((float) i0 + pixel_offset) / sf0;
 
                         // the range of source pixels that contribute
-                        const int64_t x_min = std::max(int64_t(0), (int64_t) (x - support0 + pixel_offset));
-                        const int64_t x_max = std::min(ne00, (int64_t) (x + support0 + pixel_offset));
-                        const int64_t y_min = std::max(int64_t(0), (int64_t) (y - support1 + pixel_offset));
-                        const int64_t y_max = std::min(ne01, (int64_t) (y + support1 + pixel_offset));
+                        const int64_t x_min = std::max<int64_t>(x - support0 + pixel_offset, 0);
+                        const int64_t x_max = std::min<int64_t>(x + support0 + pixel_offset, ne00);
+                        const int64_t y_min = std::max<int64_t>(y - support1 + pixel_offset, 0);
+                        const int64_t y_max = std::min<int64_t>(y + support1 + pixel_offset, ne01);
 
                         // bilinear filter with antialiasing
                         float val = 0.0f;

ggml/src/ggml-cuda/upscale.cu

@@ -81,6 +81,76 @@ static __global__ void upscale_f32_bilinear(const float * x, float * dst,
     dst[index] = result;
 }
 
+// Similar to F.interpolate(..., mode="bilinear", align_corners=False, antialias=True)
+// https://github.com/pytorch/pytorch/blob/8871ff29b743948d1225389d5b7068f37b22750b/aten/src/ATen/native/cpu/UpSampleKernel.cpp
+static __global__ void upscale_f32_bilinear_antialias(const float * src0, float * dst,
+        const int nb00, const int nb01, const int nb02, const int nb03,
+        const int ne00_src, const int ne01_src,
+        const int ne10_dst, const int ne11_dst, const int ne12_dst, const int ne13_dst,
+        const float sf0, const float sf1, const float sf2, const float sf3,
+        const float pixel_offset) {
+    const int64_t index              = threadIdx.x + blockIdx.x * blockDim.x;
+    const int64_t dst_total_elements = ne10_dst * ne11_dst * ne12_dst * ne13_dst;
+
+    if (index >= dst_total_elements) {
+        return;
+    }
+
+    const int i10_dst = index % ne10_dst;
+    const int i11_dst = (index / ne10_dst) % ne11_dst;
+    const int i12_dst = (index / (ne10_dst * ne11_dst)) % ne12_dst;
+    const int i13_dst = index / (ne10_dst * ne11_dst * ne12_dst);
+
+    const int i02_src = (int)(i12_dst / sf2);
+    const int i03_src = (int)(i13_dst / sf3);
+
+    const float y = ((float)i11_dst + pixel_offset) / sf1;
+    const float x = ((float)i10_dst + pixel_offset) / sf0;
+
+    // support and invscale, maximum 1 pixel for bilinear
+    const float support1  = max(1.f / sf1, 1.f);
+    const float invscale1 = 1.0 / support1;
+    const float support0  = max(1.f / sf0, 1.f);
+    const float invscale0 = 1.f / support0;
+
+    // the range of source pixels that contribute
+    const int64_t x_min = max(int64_t(0), int64_t(x - support0 + pixel_offset));
+    const int64_t x_max = min(int64_t(ne00_src), int64_t(x + support0 + pixel_offset));
+    const int64_t y_min = max(int64_t(0), int64_t(y - support1 + pixel_offset));
+    const int64_t y_max = min(int64_t(ne01_src), int64_t(y + support1 + pixel_offset));
+
+    // bilinear filter with antialiasing
+    float val = 0.0f;
+    float total_weight = 0.0f;
+
+    auto triangle_filter = [](float x) -> float {
+        return max(1.0f - fabsf(x), 0.f);
+    };
+
+    for (int64_t sy = y_min; sy < y_max; sy++) {
+        const float weight_y = triangle_filter((sy - y + pixel_offset) * invscale1);
+
+        for (int64_t sx = x_min; sx < x_max; sx++) {
+            const float weight_x = triangle_filter((sx - x + pixel_offset) * invscale0);
+            const float weight = weight_x * weight_y;
+
+            if (weight <= 0.0f) {
+                continue;
+            }
+
+            const float pixel = *(const float *)((const char *)src0 + sx*nb00 + sy*nb01 + i02_src*nb02 + i03_src*nb03);
+            val += pixel * weight;
+            total_weight += weight;
+        }
+    }
+
+    if (total_weight > 0.0f) {
+        val /= total_weight;
+    }
+
+    dst[index] = val;
+}
+
 namespace bicubic_interpolation {
 // https://en.wikipedia.org/wiki/Bicubic_interpolation#Bicubic_convolution_algorithm
 __device__ const float a = -0.75f; // use alpha = -0.75 (same as PyTorch)
@@ -161,11 +231,15 @@ static void upscale_f32_bilinear_cuda(const float * x, float * dst,
         const int ne00_src, const int ne01_src,
         const int ne10_dst, const int ne11_dst, const int ne12_dst, const int ne13_dst,
         const float sf0, const float sf1, const float sf2, const float sf3,
-        const float pixel_offset, cudaStream_t stream) {
+        const float pixel_offset, bool antialias, cudaStream_t stream) {
     const int64_t dst_size   = ne10_dst * ne11_dst * ne12_dst * ne13_dst;
     const int64_t num_blocks = (dst_size + CUDA_UPSCALE_BLOCK_SIZE - 1) / CUDA_UPSCALE_BLOCK_SIZE;
 
-    upscale_f32_bilinear<<<num_blocks, CUDA_UPSCALE_BLOCK_SIZE,0,stream>>>(x, dst, nb00, nb01, nb02, nb03, ne00_src, ne01_src, ne10_dst, ne11_dst, ne12_dst, ne13_dst, sf0, sf1, sf2, sf3, pixel_offset);
+    if (antialias) {
+        upscale_f32_bilinear_antialias<<<num_blocks, CUDA_UPSCALE_BLOCK_SIZE,0,stream>>>(x, dst, nb00, nb01, nb02, nb03, ne00_src, ne01_src, ne10_dst, ne11_dst, ne12_dst, ne13_dst, sf0, sf1, sf2, sf3, pixel_offset);
+    } else {
+        upscale_f32_bilinear<<<num_blocks, CUDA_UPSCALE_BLOCK_SIZE,0,stream>>>(x, dst, nb00, nb01, nb02, nb03, ne00_src, ne01_src, ne10_dst, ne11_dst, ne12_dst, ne13_dst, sf0, sf1, sf2, sf3, pixel_offset);
+    }
 }
 
 static void upscale_f32_bicubic_cuda(const float * x, float * dst,
@@ -207,9 +281,10 @@ void ggml_cuda_op_upscale(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
     if (mode == GGML_SCALE_MODE_NEAREST) {
         upscale_f32_cuda(src0_d, dst_d, src0->nb[0], src0->nb[1], src0->nb[2], src0->nb[3], dst->ne[0], dst->ne[1], dst->ne[2], dst->ne[3], sf0, sf1, sf2, sf3, stream);
     } else if (mode == GGML_SCALE_MODE_BILINEAR) {
+        bool antialias = (mode_flags & GGML_SCALE_FLAG_ANTIALIAS);
         upscale_f32_bilinear_cuda(src0_d, dst_d, src0->nb[0], src0->nb[1], src0->nb[2], src0->nb[3],
                                  src0->ne[0], src0->ne[1], dst->ne[0], dst->ne[1], dst->ne[2], dst->ne[3],
-                                 sf0, sf1, sf2, sf3, pixel_offset, stream);
+                                 sf0, sf1, sf2, sf3, pixel_offset, antialias, stream);
     } else if (mode == GGML_SCALE_MODE_BICUBIC) {
         upscale_f32_bicubic_cuda(src0_d, dst_d, src0->nb[0], src0->nb[1], src0->nb[2], src0->nb[3],
                                  src0->ne[0], src0->ne[1], dst->ne[0], dst->ne[1], dst->ne[2], dst->ne[3],

tests/test-backend-ops.cpp

@@ -7660,7 +7660,7 @@ static std::vector<std::unique_ptr<test_case>> make_test_cases_eval() {
     //    test_cases.emplace_back(new test_top_k(GGML_TYPE_F32, {i, 2, 1, 3}, rand() % i + 1));
     //}
 
-    for (ggml_scale_mode mode : {GGML_SCALE_MODE_NEAREST, GGML_SCALE_MODE_BILINEAR, GGML_SCALE_MODE_BICUBIC}) {
+    for (ggml_scale_mode mode : {GGML_SCALE_MODE_NEAREST, GGML_SCALE_MODE_BILINEAR, GGML_SCALE_MODE_BICUBIC, ggml_scale_mode(GGML_SCALE_MODE_BILINEAR | GGML_SCALE_FLAG_ANTIALIAS)}) {
         test_cases.emplace_back(new test_upscale(GGML_TYPE_F32, {512, 512, 3, 2}, 2, mode));
         test_cases.emplace_back(new test_upscale(GGML_TYPE_F32, {512, 512, 3, 2}, 2, mode, true));
         test_cases.emplace_back(new test_interpolate(GGML_TYPE_F32, {2, 5,  7, 11}, {5, 7, 11, 13}, mode));