Update llvm recipe regarding libomptarget. (#36675)

1 files changed, 28 insertions, 7 deletions

diff --git a/var/spack/repos/builtin/packages/llvm/package.py b/var/spack/repos/builtin/packages/llvm/package.py
index f62822e3ca..01fa8f0f2f 100644
--- a/var/spack/repos/builtin/packages/llvm/package.py
+++ b/var/spack/repos/builtin/packages/llvm/package.py
@@ -88,11 +88,6 @@ class Llvm(CMakePackage, CudaPackage):
         description="Build the LLVM Fortran compiler frontend "
         "(experimental - parser only, needs GCC)",
     )
-    variant(
-        "omp_debug",
-        default=False,
-        description="Include debugging code in OpenMP runtime libraries",
-    )
     variant("lldb", default=True, when="+clang", description="Build the LLVM debugger")
     variant("lld", default=True, description="Build the LLVM linker")
     variant("mlir", default=False, when="@10:", description="Build with MLIR support")
@@ -108,6 +103,18 @@ class Llvm(CMakePackage, CudaPackage):
         "libcxx", default=True, when="+clang", description="Build the LLVM C++ standard library"
     )
     variant(
+        "libomptarget",
+        default=True,
+        when="+clang",
+        description="Build the OpenMP offloading library",
+    )
+    variant(
+        "omp_debug",
+        default=False,
+        when="+libomptarget",
+        description="Include debugging code in OpenMP runtime libraries",
+    )
+    variant(
         "compiler-rt",
         when="+clang",
         default=True,
@@ -132,7 +139,7 @@ class Llvm(CMakePackage, CudaPackage):
     )
     variant(
         "targets",
-        default="none",
+        default="all",
         description=(
             "What targets to build. Spack's target family is always added "
             "(e.g. X86 is automatically enabled when targeting znver2)."
@@ -230,7 +237,7 @@ class Llvm(CMakePackage, CudaPackage):
     depends_on("hwloc")
     depends_on("hwloc@2.0.1:", when="@9:")
     depends_on("elf", when="+cuda")  # libomptarget
-    depends_on("libffi", when="+cuda")  # libomptarget
+    depends_on("libffi", when="+libomptarget")  # libomptarget
 
     # llvm-config --system-libs libraries.
     depends_on("zlib")
@@ -272,6 +279,15 @@ class Llvm(CMakePackage, CudaPackage):
     conflicts("%clang@:10", when="@13:+libcxx")
     conflicts("%apple-clang@:11", when="@13:+libcxx")
 
+    # libomptarget
+    conflicts("+cuda", when="@15:")  # +cuda variant is obselete since LLVM 15
+    conflicts(
+        "targets=none",
+        when="+libomptarget",
+        msg="Non-host backends needed for offloading, set targets=all",
+    )
+    conflicts("~lld", when="+libomptarget")
+
     # cuda_arch value must be specified
     conflicts("cuda_arch=none", when="+cuda", msg="A value for cuda_arch must be specified.")
 
@@ -644,6 +660,11 @@ class Llvm(CMakePackage, CudaPackage):
             else:
                 projects.append("openmp")
 
+            if "+libomptarget" in spec:
+                cmake_args.append(define("OPENMP_ENABLE_LIBOMPTARGET", True))
+            else:
+                cmake_args.append(define("OPENMP_ENABLE_LIBOMPTARGET", False))
+
             if "@8" in spec:
                 cmake_args.append(from_variant("CLANG_ANALYZER_ENABLE_Z3_SOLVER", "z3"))
             elif "@9:" in spec: