From 7ff877a43d0fa58f87cabdfacafddbc0b3f48ff2 Mon Sep 17 00:00:00 2001
From: Ryan Krattiger <ryan.krattiger@kitware.com>
Date: Fri, 20 Aug 2021 15:51:52 -0500
Subject: [PATCH] Updates to which and how CXX flags are set

Use `add_compiler_options` instead of modifying the CMAKE_CXX_FLAGS directly
Use CMAKE_<OPTION> to better support HPC compilers
Remove micro architecture flags that are not supported by target system compilers (Fujitsu, Spock/Frontier, etc.)
---
 CMake/build.cmake | 45 ++++++++++++++++++++-------------------------
 CMake/cuda.cmake  |  2 +-
 CMake/mpi.cmake   |  4 ++--
 3 files changed, 23 insertions(+), 28 deletions(-)

diff --git a/CMake/build.cmake b/CMake/build.cmake
index ba5771e3d..2496903d5 100644
--- a/CMake/build.cmake
+++ b/CMake/build.cmake
@@ -1,7 +1,8 @@
-option(BUILD_SHARED_LIBS OFF "Build shared libraries by default")
-option(BUILD_STATIC_EXECS  OFF "Link executables statically")
+option(BUILD_SHARED_LIBS ON "Build shared libraries (default: ON)")
+option(BUILD_STATIC_EXECS  OFF "Link executables statically.")
+
 if (BUILD_STATIC_EXECS)
-  set(BUILD_SHARED_LIBS OFF FORCE)
+  set(BUILD_SHARED_LIBS OFF)
   set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_STATIC_LIBRARY_SUFFIX})
   set(LINK_SEARCH_START_STATIC TRUE)
   set(LINK_SEARCH_END_STATIC TRUE)
@@ -13,32 +14,26 @@ if(NOT CMAKE_BUILD_TYPE)
   set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
 endif()
 
-if (NOT MSVC)
-  if (NOT CMAKE_CXX_FLAGS)
-  set(tmp "-fPIC -std=c++11 -Wall -Wextra")
-  if (BUILD_STATIC_EXECS)
-    set(tmp "${tmp} -static -static-libgcc -static-libstdc++ -pthread -Wl,-Bstatic")
-  endif()
-  if ((APPLE) AND ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang"))
-    set(tmp "${tmp} -stdlib=libc++")
-  endif()
-  if ("${CMAKE_BUILD_TYPE}" MATCHES "Release")
-    set(tmp "${tmp} -O3 -march=native -mtune=native")
-  endif()
-  set(CMAKE_CXX_FLAGS "${tmp}"
-    CACHE STRING "SENSEI build defaults"
-    FORCE)
-  endif()
-endif()
+if (BUILD_STATIC_EXECS)
+  string(APPEND CMAKE_CXX_FLAGS "-static -static-libgcc -static-libstdc++ -pthread -Wl,-Bstatic")
+endif ()
 
 include_directories(${CMAKE_SOURCE_DIR})
 include_directories(${CMAKE_BINARY_DIR})
 
-set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
-set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
-
 message(STATUS "CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}")
-message(STATUS "CMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}")
 message(STATUS "BUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}")
 message(STATUS "BUILD_STATIC_EXECS=${BUILD_STATIC_EXECS}")
+
+add_compile_options(
+   "$<$<NOT:$<COMPILE_LANGUAGE:CUDA>>:-Wall;-Wextra>"
+   # Need to explicitly set optimization level to -O3 because some systems default to -O2
+   "$<$<CONFIG:Release>:-O3>"
+   "$<$<CXX_COMPILER_ID:AppleClang>:-stdlib=libc++>")
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
diff --git a/CMake/cuda.cmake b/CMake/cuda.cmake
index 80b877abe..18e20b0d4 100644
--- a/CMake/cuda.cmake
+++ b/CMake/cuda.cmake
@@ -30,7 +30,7 @@ if(ENABLE_CUDA)
 
     message(STATUS "Created CUDA target ${CUDA_TGT_TARGET}")
 
-    target_compile_features(${CUDA_TGT_TARGET} PUBLIC cxx_std_17)
+    target_compile_features(${CUDA_TGT_TARGET} PUBLIC cxx_std_11)
 
     set_target_properties(${CUDA_TGT_TARGET} PROPERTIES POSITION_INDEPENDENT_CODE ON)
     set_target_properties(${CUDA_TGT_TARGET} PROPERTIES CUDA_SEPARABLE_COMPILATION ON)
diff --git a/CMake/mpi.cmake b/CMake/mpi.cmake
index db9079043..3a89c57e4 100644
--- a/CMake/mpi.cmake
+++ b/CMake/mpi.cmake
@@ -6,7 +6,7 @@ if (ENABLE_CRAY_MPICH OR (NOT DEFINED ENABLE_CRAY_MPICH AND NOT ("$ENV{CRAY_MPIC
     set(MPI_C_INCLUDE_PATH ${CRAY_MPICH_INCLUDE_DIRS} CACHE STRING "MPI include directories")
     set(MPI_C_LIBRARIES ${CRAY_MPICH_LDFLAGS} CACHE STRING "MPI link dependencies")
     set(MPIEXEC srun CACHE STRING "Platform MPI run equivalent")
-    set(MPI_C_FOUND CACHE BOOL TRUE "status of MPI config")
+    set(MPI_C_FOUND TRUE)
 elseif (ENABLE_CORI_GPU OR (NOT DEFINED ENABLE_CORI_GPU AND NOT ("$ENV{OPENMPI_DIR}" STREQUAL "")))
     set(ENV{PKG_CONFIG_PATH} "$ENV{OPENMPI_DIR}/lib/pkgconfig:$ENV{PKG_CONFIG_PATH}")
     find_package(PkgConfig QUIET)
@@ -14,7 +14,7 @@ elseif (ENABLE_CORI_GPU OR (NOT DEFINED ENABLE_CORI_GPU AND NOT ("$ENV{OPENMPI_D
     set(MPI_C_INCLUDE_PATH ${CORI_GPU_INCLUDE_DIRS} CACHE STRING "MPI include directories")
     set(MPI_C_LIBRARIES ${CORI_GPU_LDFLAGS} CACHE STRING "MPI link dependencies")
     set(MPIEXEC srun CACHE STRING "Platform MPI run equivalent")
-    set(MPI_C_FOUND CACHE BOOL ON "status of MPI config")
+    set(MPI_C_FOUND ON)
 else()
     find_package(MPI COMPONENTS C)
 endif()