[flang-commits] [flang] [Flang] Stop building multiple verisons of the OpenMP library (PR #126657)

[Joseph Huber via flang-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/126657

Summary:
We do not need to build for all of these architectures. Since the
infrastructure uses the natively created packager binary we can rely on
the support for generic targets. This is the same thing the OpenMP /
libc projects use now.

Depends on https://github.com/llvm/llvm-project/pull/126655


>From 003a230c30315a04dafbf5f8a3d5521ae8b1856b Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Mon, 10 Feb 2025 20:44:13 -0600
Subject: [PATCH] [Flang] Stop building multiple verisons of the OpenMP library

Summary:
We do not need to build for all of these architectures. Since the
infrastructure uses the natively created packager binary we can rely on
the support for generic targets. This is the same thing the OpenMP /
libc projects use now.

Depends on https://github.com/llvm/llvm-project/pull/126655
---
 .../modules/AddFlangOffloadRuntime.cmake      | 30 +++----------------
 1 file changed, 4 insertions(+), 26 deletions(-)

diff --git a/flang/cmake/modules/AddFlangOffloadRuntime.cmake b/flang/cmake/modules/AddFlangOffloadRuntime.cmake
index 8e4f47d18535dcb..7b598241e168145 100644
--- a/flang/cmake/modules/AddFlangOffloadRuntime.cmake
+++ b/flang/cmake/modules/AddFlangOffloadRuntime.cmake
@@ -96,36 +96,14 @@ macro(enable_omp_offload_compilation files)
     if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" AND
         "${CMAKE_C_COMPILER_ID}" MATCHES "Clang")
 
-      set(all_amdgpu_architectures
-        "gfx700;gfx701;gfx801;gfx803;gfx900;gfx902;gfx906"
-        "gfx908;gfx90a;gfx90c;gfx940;gfx1010;gfx1030"
-        "gfx1031;gfx1032;gfx1033;gfx1034;gfx1035;gfx1036"
-        "gfx1100;gfx1101;gfx1102;gfx1103;gfx1150;gfx1151"
-        "gfx1152;gfx1153"
-        )
-      set(all_nvptx_architectures
-        "sm_35;sm_37;sm_50;sm_52;sm_53;sm_60;sm_61;sm_62"
-        "sm_70;sm_72;sm_75;sm_80;sm_86;sm_89;sm_90"
-        )
-      set(all_gpu_architectures
-        "${all_amdgpu_architectures};${all_nvptx_architectures}"
-        )
-      # TODO: support auto detection on the build system.
-      if (FLANG_OMP_DEVICE_ARCHITECTURES STREQUAL "all")
-        set(FLANG_OMP_DEVICE_ARCHITECTURES ${all_gpu_architectures})
-      endif()
-      list(REMOVE_DUPLICATES FLANG_OMP_DEVICE_ARCHITECTURES)
-
-      string(REPLACE ";" "," compile_for_architectures
-        "${FLANG_OMP_DEVICE_ARCHITECTURES}"
-        )
-
       set(OMP_COMPILE_OPTIONS
         -fopenmp
         -fvisibility=hidden
         -fopenmp-cuda-mode
-        --offload-arch=${compile_for_architectures}
-        # Force LTO for the device part.
+        -fopenmp-targets=amdgcn-amd-amdhsa,nvptx64-nvidia-cuda
+        -Xopenmp-target=amdgcn-amd-amdhsa -march=''
+        -Xopenmp-target=nvptx64-nvidia-cuda -march=''
+        -nogpulib
         -foffload-lto
         )
       set_source_files_properties(${files} PROPERTIES COMPILE_OPTIONS