Initialize new variable to prevent c++17 compiler error (#3156)

* initialize new variable to prevent c++17 compiler error

* build for gfx90a using -std=c++17 flag

Author: illsilin

Jenkinsfile

@@ -1836,10 +1836,11 @@ pipeline {
                     }
                     agent{ label rocmnode("gfx90a") }
                     environment{
-                        setup_args = """ -DCMAKE_INSTALL_PREFIX=../install -DGPU_TARGETS="gfx90a" -DCMAKE_CXX_FLAGS=" -O3 " """
+                        setup_args = """ -DCMAKE_INSTALL_PREFIX=../install -DGPU_TARGETS="gfx90a" -DCK_CXX_STANDARD="17" -DCMAKE_CXX_FLAGS=" -O3 " """
                         execute_args = """ cd ../client_example && rm -rf build && mkdir build && cd build && \
                                            cmake -DCMAKE_PREFIX_PATH="${env.WORKSPACE}/install;/opt/rocm" \
                                            -DGPU_TARGETS="gfx90a" \
+                                           -DCK_CXX_STANDARD="17" \
                                            -DCMAKE_CXX_COMPILER="${build_compiler()}" \
                                            -DCMAKE_C_COMPILER=/opt/rocm/llvm/bin/clang \
                                            -DCMAKE_CXX_FLAGS=" -O3 " .. && make -j """

include/ck/tensor_operation/gpu/element/element_wise_operation.hpp

@@ -73,7 +73,7 @@ struct AddReluAdd
     __host__ __device__ constexpr void operator()<half_t, float, half_t, half_t>(
         half_t& y, const float& x0, const half_t& x1, const half_t& x2) const
     {
-        float y_float;
+        float y_float = 0.0;
         (*this)(y_float, x0, x1, x2);
         y = y_float;
     }