Enable CUDA and HIP optionally to build GPU reconstruction code

Credits @davidrohr, @mconcas, @dberzano

Author: mpuccio

CMakeLists.txt

@@ -6,7 +6,7 @@
 # and the experiment part.
 
 # Check IF cmake has the required version
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.11 FATAL_ERROR)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.11.0 FATAL_ERROR)
 
 ### CMP0025   Compiler id for Apple Clang is now AppleClang.
 ### CMP0042   MACOSX_RPATH is enabled by default.

cmake/O2Dependencies.cmake

@@ -75,6 +75,52 @@ if (DDS_FOUND)
   set(OPTIONAL_DDS_INCLUDE_DIR ${DDS_INCLUDE_DIR})
 endif ()
 
+if (ENABLE_CUDA)
+  include(CheckLanguage)
+  check_language(CUDA)
+  if(NOT CMAKE_CUDA_COMPILER)
+    message(FATAL "No CUDA compiler found")
+  endif()
+  if(CMAKE_BUILD_TYPE STREQUAL "DEBUG")
+    set(CMAKE_CUDA_FLAGS "-Xptxas -O0 -Xcompiler -O0")
+  else()
+    set(CMAKE_CUDA_FLAGS "-Xptxas -O4 -Xcompiler -O4 -use_fast_math")
+  endif()
+  if(CUDA_GCCBIN)
+    message(STATUS "Using as CUDA GCC version: ${CUDA_GCCBIN}")
+    set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} --compiler-bindir ${CUDA_GCCBIN}")
+  endif()
+  enable_language(CUDA)
+  if(CUDA_GCCBIN)
+    #Ugly hack! Otherwise CUDA includes unwanted old GCC libraries leading to version conflicts
+    set(CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES "$ENV{CUDA_PATH}/lib64")
+  endif()
+  add_definitions(-DENABLE_CUDA)
+  set(CMAKE_CUDA_STANDARD 14)
+  set(CMAKE_CUDA_STANDARD_REQUIRED ON)
+  set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} --expt-relaxed-constexpr --compiler-options \"${CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE}} -std=c++14\"")
+  message(STATUS "CUDA FOUND: Version ${CUDA_VERSION}")
+endif()
+
+if (ENABLE_HIP)
+  if(NOT DEFINED HIP_PATH)
+    if(NOT DEFINED ENV{HIP_PATH})
+       set(HIP_PATH "/opt/rocm/hip" CACHE PATH "Path to which HIP has been installed")
+    else()
+      set(HIP_PATH $ENV{HIP_PATH} CACHE PATH "Path to which HIP has been installed")
+    endif()
+  endif()
+  set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${HIP_PATH}/cmake")
+  if(NOT DEFINED HCC_PATH)
+    # Workaround to fix a potential FindHIP bug: find HCC_PATH ourselves
+    set(_HCC_PATH "${HIP_PATH}/../hcc")
+    get_filename_component(HCC_PATH ${_HCC_PATH} ABSOLUTE CACHE)
+    unset(_HCC_PATH)
+  endif()
+  find_package(HIP REQUIRED)
+  add_definitions(-DENABLE_HIP)
+endif()
+
 # todo this should really not be needed. ROOT, Pythia, and FairRoot should comply with CMake best practices
 # todo but they do not properly return DEPENDENCIES with absolute path.
 link_directories(