Fix compat issues with LLVM15 in numba 0.61.x (#39)

- Add patch for openmp 15.0.7 to build DeviceRTL bitcodes without opaque pointers
- Cleanup code and improve diagnostic output

Author: ggeorgakoudis

setup.py

@@ -121,14 +121,9 @@ def _build_cmake(self, ext: CMakeExtension):
 
     def _env_toolchain_args(self, ext):
         args = []
-        # Forward LLVM_DIR and CLANG_TOOL if provided.
+        # Forward LLVM_DIR if provided.
         if os.environ.get("LLVM_DIR"):
             args.append(f"-DLLVM_DIR={os.environ['LLVM_DIR']}")
-        if ext.name == "libomp":
-            # CLANG_TOOL is used by libomp to find clang for generating the OpenMP
-            # device runtime bitcodes.
-            if os.environ.get("CLANG_TOOL"):
-                args.append(f"-DCLANG_TOOL={os.environ['CLANG_TOOL']}")
         return args
 
 

src/numba/openmp/libs/libomp/patches/15.0.7/0003-Disable-opaque-pointers-DeviceRTL-bitcode.patch

@@ -0,0 +1,12 @@
+diff --git a/libomptarget/DeviceRTL/CMakeLists.txt b/libomptarget/DeviceRTL/CMakeLists.txt
+index ce66214..04c9dd5 100644
+--- a/libomptarget/DeviceRTL/CMakeLists.txt
++++ b/libomptarget/DeviceRTL/CMakeLists.txt
+@@ -127,6 +127,7 @@ set(bc_flags -c -emit-llvm -std=c++17 -fvisibility=hidden
+              -fopenmp -fopenmp-cuda-mode
+              -I${include_directory}
+              -I${devicertl_base_directory}/../include
++             -Xclang -no-opaque-pointers
+              ${LIBOMPTARGET_LLVM_INCLUDE_DIRS_DEVICERTL}
+ )
+ 

src/numba/openmp/libs/pass/CMakeLists.txt

@@ -13,7 +13,7 @@ find_package(LLVM REQUIRED CONFIG NO_DEFAULT_PATH PATHS
   ${LLVM_DIR}
 )
 
-message(STATUS "LLVM_VERSION ${LLVM_VERSION}")
+message(STATUS "Found LLVM version ${LLVM_VERSION}")
 
 include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})
 

src/numba/openmp/omp_ir.py

@@ -122,8 +122,15 @@ def __init__(self):
         self.libomptarget_arch = (
             libpath / "libomp" / "lib" / f"libomptarget-nvptx-{self.sm}.bc"
         )
-        with open(self.libomptarget_arch, "rb") as f:
-            libomptarget_mod = ll.parse_bitcode(f.read())
+
+        try:
+            with open(self.libomptarget_arch, "rb") as f:
+                libomptarget_mod = ll.parse_bitcode(f.read())
+        except FileNotFoundError:
+            raise RuntimeError(
+                f"Device RTL for architecture {self.sm} not found. Check compute capability with LLVM version {'.'.join(map(str, ll.llvm_version_info))}."
+            )
+
         ## Link in device, openmp libraries.
         self.libs_mod.link_in(libomptarget_mod)
         # Initialize asm printers to codegen ptx.
@@ -1493,7 +1500,9 @@ def add_mapped_to_ins(ins, tags):
             # include a branch converging variable $cp. Remove it to avoid the
             # assert since the openmp region must be single-entry, single-exit.
             if sys.version_info >= (3, 10) and sys.version_info < (3, 11):
-                assert len(target_args) == len([x for x in target_args_unordered if x != "$cp"])
+                assert len(target_args) == len(
+                    [x for x in target_args_unordered if x != "$cp"]
+                )
             else:
                 assert len(target_args) == len(target_args_unordered)
             assert len(target_args) == len(outline_arg_typs)