[Offload] Remove support for old "BUILD_PLUGIN" options.

[jhuber6]

Summary:
Since the move to the statically linked plugins, we added a new way to
directly control which plugins will be added. Delete these old ones as
they will cause the build to fail and suggest the new format.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

@llvm/pr-subscribers-offload

Author: Joseph Huber (jhuber6)

Changes

Summary:
Since the move to the statically linked plugins, we added a new way to
directly control which plugins will be added. Delete these old ones as
they will cause the build to fail and suggest the new format.

---

Full diff: https://github.com/llvm/llvm-project/pull/91644.diff

3 Files Affected:

• (modified) offload/CMakeLists.txt (+6)
• (modified) offload/plugins-nextgen/amdgpu/CMakeLists.txt (-7)
• (modified) offload/plugins-nextgen/cuda/CMakeLists.txt (-7)

diff --git a/offload/CMakeLists.txt b/offload/CMakeLists.txt
index 3f77583ffa3b8..626df81250638 100644
--- a/offload/CMakeLists.txt
+++ b/offload/CMakeLists.txt
@@ -151,6 +151,11 @@ if (NOT LIBOMPTARGET_LLVM_INCLUDE_DIRS)
   message(FATAL_ERROR "Missing definition for LIBOMPTARGET_LLVM_INCLUDE_DIRS")
 endif()
 
+if(DEFINED LIBOMPTARGET_BUILD_CUDA_PLUGIN OR 
+   DEFINED LIBOMPTARGET_BUILD_AMDGPU_PLUGIN)
+  message(WARNING "Option removed, use 'LIBOMPTARGET_PLUGINS_TO_BUILD' instead")
+endif()
+
 set(LIBOMPTARGET_ALL_PLUGIN_TARGETS amdgpu cuda host)
 set(LIBOMPTARGET_PLUGINS_TO_BUILD "all" CACHE STRING
     "Semicolon-separated list of plugins to use: cuda, amdgpu, host or \"all\".")
@@ -158,6 +163,7 @@ set(LIBOMPTARGET_PLUGINS_TO_BUILD "all" CACHE STRING
 if(LIBOMPTARGET_PLUGINS_TO_BUILD STREQUAL "all")
   set(LIBOMPTARGET_PLUGINS_TO_BUILD ${LIBOMPTARGET_ALL_PLUGIN_TARGETS})
 endif()
+message("Building with support for ${LIBOMPTARGET_PLUGINS_TO_BUILD} plugins")
 
 set(LIBOMPTARGET_ENUM_PLUGIN_TARGETS "")
 foreach(plugin IN LISTS LIBOMPTARGET_PLUGINS_TO_BUILD)
diff --git a/offload/plugins-nextgen/amdgpu/CMakeLists.txt b/offload/plugins-nextgen/amdgpu/CMakeLists.txt
index 738183f8945ed..280cb57e22e90 100644
--- a/offload/plugins-nextgen/amdgpu/CMakeLists.txt
+++ b/offload/plugins-nextgen/amdgpu/CMakeLists.txt
@@ -12,13 +12,6 @@
 ##===----------------------------------------------------------------------===##
 
 ################################################################################
-set(LIBOMPTARGET_BUILD_AMDGPU_PLUGIN TRUE CACHE BOOL
-  "Whether to build AMDGPU plugin")
-if (NOT LIBOMPTARGET_BUILD_AMDGPU_PLUGIN)
-  libomptarget_say("Not building AMDGPU NextGen offloading plugin: LIBOMPTARGET_BUILD_AMDGPU_PLUGIN is false")
-  return()
-endif()
-
 # as of rocm-3.7, hsa is installed with cmake packages and kmt is found via hsa
 find_package(hsa-runtime64 QUIET 1.2.0 HINTS ${CMAKE_INSTALL_PREFIX} PATHS /opt/rocm)
 
diff --git a/offload/plugins-nextgen/cuda/CMakeLists.txt b/offload/plugins-nextgen/cuda/CMakeLists.txt
index dd684bb223431..3f3388e56c5fe 100644
--- a/offload/plugins-nextgen/cuda/CMakeLists.txt
+++ b/offload/plugins-nextgen/cuda/CMakeLists.txt
@@ -9,13 +9,6 @@
 # Build a plugin for a CUDA machine if available.
 #
 ##===----------------------------------------------------------------------===##
-set(LIBOMPTARGET_BUILD_CUDA_PLUGIN TRUE CACHE BOOL
-  "Whether to build CUDA plugin")
-if (NOT LIBOMPTARGET_BUILD_CUDA_PLUGIN)
-  libomptarget_say("Not building CUDA NextGen offloading plugin: LIBOMPTARGET_BUILD_CUDA_PLUGIN is false")
-  return()
-endif()
-
 if (NOT (CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(ppc64le)|(aarch64)$" AND CMAKE_SYSTEM_NAME MATCHES "Linux"))
   libomptarget_say("Not building CUDA NextGen offloading plugin: only support CUDA in Linux x86_64, ppc64le, or aarch64 hosts.")
   return()

[jplehr]

I don't know what this will do to downstream, but I like the change.
LGTM