From 014ab107e37ee2cd4db164d78d650bc66fc5ab30 Mon Sep 17 00:00:00 2001
From: Harsh Chauhan <harsh2005.hc@gmail.com>
Date: Mon, 15 Jun 2026 18:47:16 +0530
Subject: [PATCH] fixing cpu elu formula and added support for Elu GPU alpaka
 kernel with gtest

---
 core/inc/SOFIE/ROperator_Elu.hxx              | 40 ++++++++++++++++++-
 .../TestCustomModelsFromONNXForAlpakaCuda.cxx | 37 +++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/core/inc/SOFIE/ROperator_Elu.hxx b/core/inc/SOFIE/ROperator_Elu.hxx
index 6588b61..31582ee 100644
--- a/core/inc/SOFIE/ROperator_Elu.hxx
+++ b/core/inc/SOFIE/ROperator_Elu.hxx
@@ -69,11 +69,49 @@ public:
 
       out << "\n//------ ELU \n";
       out << SP << "for (int id = 0; id < " << length << " ; id++){\n";
-      out << SP << SP << "tensor_" << fNY << "[id] = ((tensor_" << fNX << "[id] >= 0 )? tensor_" << fNX << "[id] : "<< OpName << "_alpha * std::exp(tensor_"<< fNX<<"[id]) - 1);\n";
+      out << SP << SP << "tensor_" << fNY << "[id] = ((tensor_" << fNX << "[id] >= 0 )? tensor_" << fNX << "[id] : "<< OpName << "_alpha * (std::exp(tensor_"<< fNX<<"[id]) - 1));\n";
       out << SP << "}\n";
       return out.str();
    }
+   
+   std::vector<std::string> GetStdLibs() override { return { std::string("cmath") }; }
+
+   // elu gpu kernel
+   std::string Generate_GPU_Kernel_ALPAKA(std::string /*opName*/) override {
+      std::string op;
+      op = "\n//------ ELU_KERNEL_ALPAKA\n";
+      op += "struct EluKernel {\n";
+      op += SP + "template<typename TAcc, typename T>\n";
+      op += SP + "ALPAKA_FN_ACC void operator()(TAcc const& acc, T const* __restrict__ data, T* __restrict__ out, std::size_t numElements, T alpha) const {\n";
+      op += SP + SP + "const auto idx = alpaka::getIdx<alpaka::Grid, alpaka::Threads>(acc)[0];\n";
+      op += SP + SP + "if (idx < numElements) { out[idx] = data[idx] >= T(0) ? data[idx]:alpha * (exp(data[idx]) - T(1)); }\n";
+      op += SP + "}\n";
+      op += "};\n";
+      return op;
+   }
+
+   std::string Generate_GPU_Kernel_Definitions_ALPAKA(std::string /*opName*/) override {
+      return SP + "EluKernel eluKernel;\n";
+   }
 
+   std::string Generate_GPU_ALPAKA(std::string OpName) override {
+      OpName = "op_" + OpName;
+      if (fShape.empty()) {
+         throw std::runtime_error("SOFIE Elu called to Generate_GPU_ALPAKA without being initialized");
+      }
+      std::stringstream out;
+      std::string length = ConvertDimShapeToLength(fShape);
+      out << "\n//------ ELU_GPU_ALPAKA\n";
+      out << SP << "auto const elementsPerThread_"<<fNX<<" = Vec::all(static_cast<Idx>(1));\n";
+      out << SP << "auto const elementsPerGrid_"<<fNX<<" = Vec::all(Idx{"<< length << "});\n";
+      out << SP << "auto const workDiv_" << fNX << " = sofie_workdiv(elementsPerGrid_" << fNX << ");\n";
+      out << SP << "auto task_" << OpName << " = alpaka::createTaskKernel<Acc>(workDiv_" << fNX
+         << ", eluKernel, alpaka::getPtrNative(deviceBuf_" << fNX
+         << "), alpaka::getPtrNative(deviceBuf_" << fNY << "), static_cast<Idx>(" << length << "), static_cast<float>("
+         << std::setprecision(std::numeric_limits<float>::max_digits10) << falpha << "));\n";
+      out << SP << "alpaka::enqueue(queue, task_" << OpName << ");\n";
+      return out.str();
+   }
 };
 
 }//SOFIE
diff --git a/core/test/TestCustomModelsFromONNXForAlpakaCuda.cxx b/core/test/TestCustomModelsFromONNXForAlpakaCuda.cxx
index 5ad9383..ecfb7b6 100644
--- a/core/test/TestCustomModelsFromONNXForAlpakaCuda.cxx
+++ b/core/test/TestCustomModelsFromONNXForAlpakaCuda.cxx
@@ -176,6 +176,9 @@
 #include "Clip_FromONNX_GPU_ALPAKA.hxx"
 #include "Not_FromONNX_GPU_ALPAKA.hxx"
 
+#include "Elu_FromONNX_GPU_ALPAKA.hxx"
+#include "input_models/references/Elu.ref.hxx"
+
 #include "GNN_model_FromONNX_GPU_ALPAKA.hxx"
 
 #include <alpaka/alpaka.hpp>
@@ -3161,3 +3164,37 @@ TEST_F(SofieAlpakaTest, Logic_BitwiseNot)
    for (std::size_t i = 0; i < N; ++i)
       EXPECT_EQ(res[i], ref[i]) << "  index=" << i;
 }
+
+TEST_F(SofieAlpakaTest, Elu)
+{
+   constexpr float TOLERANCE = DEFAULT_TOLERANCE;
+
+   // same input as the CPU Elu test: spans negative + positive
+   std::vector<float> input({1.0f, -2.0f, 3.0f, 0.5f, -1.0f, 2.0f});
+
+   auto input_h = alpaka::allocBuf<float, Idx>(host, Ext1D::all(Idx{input.size()}));
+   float* input_ptr = reinterpret_cast<float*>(alpaka::getPtrNative(input_h));
+   for (Idx i = 0; i < input.size(); ++i) input_ptr[i] = input[i];
+
+   auto input_d = alpaka::allocBuf<float, Idx>(device, Ext1D::all(Idx{input.size()}));
+   alpaka::memcpy(queue, input_d, input_h);
+   alpaka::wait(queue);
+
+   constexpr size_t nOut = sizeof(Elu_ExpectedOutput::outputs) / sizeof(float);
+   auto result_h = alpaka::allocBuf<float, Idx>(host, Ext1D::all(Idx{nOut}));
+
+   {
+      SOFIE_Elu::Session<alpaka::TagGpuCudaRt> session;
+      auto result = session.infer(input_d);
+      alpaka::wait(queue);
+      cudaDeviceSynchronize();
+      alpaka::memcpy(queue, result_h, result);
+      alpaka::wait(queue);
+   }
+
+   float* res_ptr = reinterpret_cast<float*>(alpaka::getPtrNative(result_h));
+   float* correct = Elu_ExpectedOutput::outputs;
+   for (size_t i = 0; i < nOut; ++i) {
+      EXPECT_LE(std::abs(res_ptr[i] - correct[i]), TOLERANCE) << "i=" << i;
+   }
+}