use CMake builtin mechanisms for setting target CUDA architecture(s)

.github/workflows/github-actions.yml

@@ -54,8 +54,10 @@ jobs:
         run: |
           mypy ./legateboost --config-file ./setup.cfg --exclude=legateboost/test --exclude=install_info
       - name: Build legateboost
+        env:
+          CUDAARCHS: '70;80'
         run: |
-          CUDA_ARCH=70\;80 ./build.sh
+          ./build.sh
           python -m build -n --wheel
       - uses: actions/upload-artifact@v3
         with:

build.sh

@@ -1,9 +1,14 @@
 #!/usr/bin/env bash
 
-set -e
+set -e -u -o pipefail
+
+# ensure 'native' is used if CUDAARCHS isn't set
+# (instead of the CMake default which is a specific architecture)
+# ref: https://cmake.org/cmake/help/latest/variable/CMAKE_CUDA_ARCHITECTURES.html
+declare -r CMAKE_CUDA_ARCHITECTURES="${CUDAARCHS:-native}"
 
 legate_root=`python -c 'import legate.install_info as i; from pathlib import Path; print(Path(i.libpath).parent.resolve())'`
 echo "Using Legate at $legate_root"
-cmake -S . -B build -D legate_core_ROOT=$legate_root -DCMAKE_BUILD_TYPE=Release -DCMAKE_CUDA_ARCHITECTURES=native
+cmake -S . -B build -D legate_core_ROOT=$legate_root -DCMAKE_BUILD_TYPE=Release -DCMAKE_CUDA_ARCHITECTURES=${CMAKE_CUDA_ARCHITECTURES}
 cmake --build build -j
 python -m pip install -e .

contributing.md

@@ -16,7 +16,21 @@ legate --module pytest legateboost/test
 
 ## Change default CUDA architectures
 
-Set the environment variable `CUDA_ARCH` according to cmake [CUDA_ARCHITECTURES](https://cmake.org/cmake/help/latest/prop_tgt/CUDA_ARCHITECTURES.html) if you are installing with pip. For running cmake directly, the argument `CMAKE_CUDA_ARCHITECTURES` works as well.
+By default, builds here default to `CMAKE_CUDA_ARCHITECTURES=native` (whatever GPU exists on the system where the build is running).
+
+If installing with `pip`, set the `CUDAARCHS` environment variable, as described in the CMake docs ([link](https://cmake.org/cmake/help/latest/variable/CMAKE_CUDA_ARCHITECTURES.html)).
+
+```shell
+CUDAARCHS="70;80" \
+    pip install .
+```
+
+For CMake-based builds, pass `CMAKE_CUDA_ARCHITECTURES`.
+
+```shell
+cmake -B build -S . -DCMAKE_CUDA_ARCHITECTURES="70;80"
+cmake --build build -j
+```
 
 ## Pre-commit hooks
 

setup.py

@@ -24,9 +24,14 @@
 
 legate_dir = Path(lg_install_info.libpath).parent.as_posix()
 
+# ensure 'native' is used if CUDAARCHS isn't set
+# (instead of the CMake default which is a specific architecture)
+# ref: https://cmake.org/cmake/help/latest/variable/CMAKE_CUDA_ARCHITECTURES.html
+cuda_arch = os.getenv("CUDAARCHS", "native")
+
 cmake_flags = [
     f"-Dlegate_core_ROOT:STRING={legate_dir}",
-    "-DCMAKE_CUDA_ARCHITECTURES=native",
+    f"-DCMAKE_CUDA_ARCHITECTURES={cuda_arch}",
 ]
 
 env_cmake_args = os.environ.get("CMAKE_ARGS")

src/CMakeLists.txt

@@ -60,14 +60,7 @@ target_compile_options(legateboost
               "$<$<COMPILE_LANGUAGE:CUDA>:${LB_CUDA_FLAGS}>"
 )
 
-
-
 if (Legion_USE_CUDA)
-  # CUDA_ARCH environment variable can override the CMAKE_CUDA_ARCHITECTURES
-  if(DEFINED ENV{CUDA_ARCH})
-    message(STATUS "legateboost: CUDA_ARCH=$ENV{CUDA_ARCH}")
-    set_property(TARGET legateboost PROPERTY CUDA_ARCHITECTURES $ENV{CUDA_ARCH} )
-  endif()
   target_compile_definitions(legateboost PRIVATE LEGATEBOOST_USE_CUDA)
 endif()