Update README.md file to add instructions for Polaris

Author: rayhe88

README.md

@@ -3,11 +3,35 @@
 
 ## Compilation
 
+### Laptop DELL with oneapi
 ```
 mkdir build
 cmake ../src/ -DCMAKE_CXX_COMPILER=icpx
 cmake --build .
 ```
+
+### Polaris - ALCF machine
+```
+module use /soft/modulefiles
+module load oneapi/upstream
+module load nvhpc-mixed
+module load craype-accel-nvidia80
+module unload nvhpc-mixed
+module load spack-pe-base cmake
+
+EXTRA_FLAGS="-sycl-std=2020 -O3 -fsycl -fsycl-targets=nvptx64-nvidia-cuda -Xsycl-target-backend --cuda-gpu-arch=sm_80"
+export CFLAGS="-ffp-model=precise"
+export CXXFLAGS="-ffp-model=precise -fsycl $EXTRA_FLAGS"
+export CC=clang
+export CXX=clang++
+
+
+mkdir build
+cmake ../src/ -DCMAKE_CXX_COMPILER=clang++
+cmake --build .
+```
+
+
 ## Acknowledgements
 This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357. Argonne National Laboratory’s work was supported by the U.S. Department of Energy, Office of Science, under contract DE-AC02-06CH11357.