[flang][runtime] Create CUDA PTX OBJECT library target for F18 runtime CUDA build.

[vzakhari]

This is to experiment with distributing F18 runtime CUDA library
in the form of a pure PTX library. The change is under
FLANG_EXPERIMENTAL_CUDA_RUNTIME CMake control.

[llvmbot]

@llvm/pr-subscribers-flang-runtime

Author: Slava Zakharin (vzakhari)

Changes

This is to experiment with distributing F18 runtime CUDA library
in the form of a pure PTX library. The change is under
FLANG_EXPERIMENTAL_CUDA_RUNTIME CMake control.

---

Full diff: https://github.com/llvm/llvm-project/pull/88821.diff

3 Files Affected:

• (modified) flang/cmake/modules/AddFlangOffloadRuntime.cmake (+5-1)
• (modified) flang/lib/Decimal/CMakeLists.txt (+1-1)
• (modified) flang/runtime/CMakeLists.txt (+1-1)

diff --git a/flang/cmake/modules/AddFlangOffloadRuntime.cmake b/flang/cmake/modules/AddFlangOffloadRuntime.cmake
index 6fb6213e90fc49..e34d3851187acf 100644
--- a/flang/cmake/modules/AddFlangOffloadRuntime.cmake
+++ b/flang/cmake/modules/AddFlangOffloadRuntime.cmake
@@ -10,7 +10,7 @@ set(FLANG_EXPERIMENTAL_OMP_OFFLOAD_BUILD "off" CACHE STRING
 set(FLANG_OMP_DEVICE_ARCHITECTURES "all" CACHE STRING
   "List of OpenMP device architectures to be used to compile the Fortran runtime (e.g. 'gfx1103;sm_90')")
 
-macro(enable_cuda_compilation files)
+macro(enable_cuda_compilation name files)
   if (FLANG_EXPERIMENTAL_CUDA_RUNTIME)
     if (BUILD_SHARED_LIBS)
       message(FATAL_ERROR
@@ -52,6 +52,10 @@ macro(enable_cuda_compilation files)
       include_directories(AFTER ${FLANG_LIBCUDACXX_PATH}/include)
       add_compile_definitions(RT_USE_LIBCUDACXX=1)
     endif()
+
+    # Add an OBJECT library consisting of CUDA PTX.
+    llvm_add_library(${name}PTX OBJECT PARTIAL_SOURCES_INTENDED ${files})
+    set_property(TARGET obj.${name}PTX PROPERTY CUDA_PTX_COMPILATION ON)
   endif()
 endmacro()
 
diff --git a/flang/lib/Decimal/CMakeLists.txt b/flang/lib/Decimal/CMakeLists.txt
index 3d562b8e3ce1e5..880b190f1c5815 100644
--- a/flang/lib/Decimal/CMakeLists.txt
+++ b/flang/lib/Decimal/CMakeLists.txt
@@ -55,7 +55,7 @@ set(sources
 )
 
 include(AddFlangOffloadRuntime)
-enable_cuda_compilation("${sources}")
+enable_cuda_compilation(FortranDecimal "${sources}")
 enable_omp_offload_compilation("${sources}")
 
 add_flang_library(FortranDecimal INSTALL_WITH_TOOLCHAIN ${sources})
diff --git a/flang/runtime/CMakeLists.txt b/flang/runtime/CMakeLists.txt
index 2a65a22ab674c4..bdd0e07bbfd4d1 100644
--- a/flang/runtime/CMakeLists.txt
+++ b/flang/runtime/CMakeLists.txt
@@ -224,7 +224,7 @@ set(supported_files
   utf.cpp
   )
 
-enable_cuda_compilation("${supported_files}")
+enable_cuda_compilation(FortranRuntime "${supported_files}")
 enable_omp_offload_compilation("${supported_files}")
 
 if (NOT TARGET FortranFloat128Math)