[PATCH] D141723: [Clang] Remove `CLANG_OPENMP_NVPTX_DEFAULT_ARCH` CMake option.

[Joseph Huber via Phabricator via llvm-commits]

jhuber6 created this revision.
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The `CLANG_OPENMP_NVPTX_DEFAULT_ARCH` is a static build configuration to
set the default OpenMP value. This was replaced in D141708 <https://reviews.llvm.org/D141708> with the use
of the `nvptx-arch` tool which lets us query this at runtime instead.
This makes the behaviour between AMD and NVIDIA be more consisten and
allows users to have a default architecture that does not rely on
whoever configured the LLVM build.

Depends on D141708 <https://reviews.llvm.org/D141708>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D141723

Files:
  clang/CMakeLists.txt
  clang/include/clang/Config/config.h.cmake
  llvm/utils/gn/secondary/clang/include/clang/Config/BUILD.gn
  utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h


Index: utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h
===================================================================
--- utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h
+++ utils/bazel/llvm-project-overlay/clang/include/clang/Config/config.h
@@ -43,9 +43,6 @@
 /* Default OpenMP runtime used by -fopenmp. */
 #define CLANG_DEFAULT_OPENMP_RUNTIME "libomp"
 
-/* Default architecture for OpenMP offloading to Nvidia GPUs. */
-#define CLANG_OPENMP_NVPTX_DEFAULT_ARCH "sm_35"
-
 /* Default architecture for SystemZ. */
 #define CLANG_SYSTEMZ_DEFAULT_ARCH "z10"
 
Index: llvm/utils/gn/secondary/clang/include/clang/Config/BUILD.gn
===================================================================
--- llvm/utils/gn/secondary/clang/include/clang/Config/BUILD.gn
+++ llvm/utils/gn/secondary/clang/include/clang/Config/BUILD.gn
@@ -17,7 +17,6 @@
     "CLANG_DEFAULT_OPENMP_RUNTIME=libomp",
     "CLANG_DEFAULT_UNWINDLIB=",
     "CLANG_INSTALL_LIBDIR_BASENAME=lib",
-    "CLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_35",
     "CLANG_RESOURCE_DIR=",
     "C_INCLUDE_DIRS=",
     "CLANG_CONFIG_FILE_SYSTEM_DIR=",
Index: clang/include/clang/Config/config.h.cmake
===================================================================
--- clang/include/clang/Config/config.h.cmake
+++ clang/include/clang/Config/config.h.cmake
@@ -29,9 +29,6 @@
 /* Default OpenMP runtime used by -fopenmp. */
 #define CLANG_DEFAULT_OPENMP_RUNTIME "${CLANG_DEFAULT_OPENMP_RUNTIME}"
 
-/* Default architecture for OpenMP offloading to Nvidia GPUs. */
-#define CLANG_OPENMP_NVPTX_DEFAULT_ARCH "${CLANG_OPENMP_NVPTX_DEFAULT_ARCH}"
-
 /* Default architecture for SystemZ. */
 #define CLANG_SYSTEMZ_DEFAULT_ARCH "${CLANG_SYSTEMZ_DEFAULT_ARCH}"
 
Index: clang/CMakeLists.txt
===================================================================
--- clang/CMakeLists.txt
+++ clang/CMakeLists.txt
@@ -245,31 +245,6 @@
 set(CLANG_DEFAULT_OPENMP_RUNTIME "libomp" CACHE STRING
   "Default OpenMP runtime used by -fopenmp.")
 
-# OpenMP offloading requires at least sm_35 because we use shuffle instructions
-# to generate efficient code for reductions and the atomicMax instruction on
-# 64-bit integers in the implementation of conditional lastprivate.
-set(CUDA_ARCH_FLAGS "sm_35")
-
-# Try to find the highest Nvidia GPU architecture the system supports
-if (NOT DEFINED CLANG_OPENMP_NVPTX_DEFAULT_ARCH)
-  find_package(CUDA QUIET)
-  if (CUDA_FOUND)
-    cuda_select_nvcc_arch_flags(CUDA_ARCH_FLAGS)
-  endif()
-else()
-  set(CUDA_ARCH_FLAGS ${CLANG_OPENMP_NVPTX_DEFAULT_ARCH})
-endif()
-
-string(REGEX MATCH "sm_([0-9]+)" CUDA_ARCH_MATCH ${CUDA_ARCH_FLAGS})
-if (NOT DEFINED CUDA_ARCH_MATCH OR "${CMAKE_MATCH_1}" LESS 35)
-  set(CLANG_OPENMP_NVPTX_DEFAULT_ARCH "sm_35" CACHE STRING
-    "Default architecture for OpenMP offloading to Nvidia GPUs." FORCE)
-  message(WARNING "Resetting default architecture for OpenMP offloading to Nvidia GPUs to sm_35")
-else()
-  set(CLANG_OPENMP_NVPTX_DEFAULT_ARCH ${CUDA_ARCH_MATCH} CACHE STRING
-    "Default architecture for OpenMP offloading to Nvidia GPUs.")
-endif()
-
 set(CLANG_SYSTEMZ_DEFAULT_ARCH "z10" CACHE STRING "SystemZ Default Arch")
 
 set(CLANG_VENDOR ${PACKAGE_VENDOR} CACHE STRING


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