Support discovery of nvrtc and nvjitlink libraries at run time

CTK installations distribute their libraries using personal packages:
- nvidia-nvjitlink-cuXX
- nvidia-cuda-nvrtc-cuXX

The relative path of their libraries to cuda-bindings is consistent,
and allows us to use relative paths to discover them when loading
at run time.

Author: vzhurba01

cuda_bindings/setup.py

@@ -20,15 +20,14 @@
 from Cython.Build import cythonize
 from pyclibrary import CParser
 from setuptools import find_packages, setup
+from setuptools.command.bdist_wheel import bdist_wheel
 from setuptools.command.build_ext import build_ext
 from setuptools.extension import Extension
 
 # ----------------------------------------------------------------------
 # Fetch configuration options
 
-CUDA_HOME = os.environ.get("CUDA_HOME")
-if not CUDA_HOME:
-    CUDA_HOME = os.environ.get("CUDA_PATH")
+CUDA_HOME = os.environ.get("CUDA_HOME", os.environ.get("CUDA_PATH", None))
 if not CUDA_HOME:
     raise RuntimeError("Environment variable CUDA_HOME or CUDA_PATH is not set")
 
@@ -283,24 +282,49 @@ def do_cythonize(extensions):
     extensions += prep_extensions(sources)
 
 # ---------------------------------------------------------------------
-# Custom build_ext command
-# Files are build in two steps:
-# 1) Cythonized (in the do_cythonize() command)
-# 2) Compiled to .o files as part of build_ext
-# This class is solely for passing the value of nthreads to build_ext
+# Custom cmdclass extensions
+
+building_wheel = False
+
+
+class WheelsBuildExtensions(bdist_wheel):
+    def run(self):
+        global building_wheel
+        building_wheel = True
+        super().run()
 
 
 class ParallelBuildExtensions(build_ext):
     def initialize_options(self):
-        build_ext.initialize_options(self)
+        super().initialize_options()
         if nthreads > 0:
             self.parallel = nthreads
 
-    def finalize_options(self):
-        build_ext.finalize_options(self)
+    def build_extension(self, ext):
+        if building_wheel:
+            # Strip binaries to remove debug symbols
+            extra_linker_flags = ["-Wl,--strip-all"]
+
+            # Allow extensions to discover libraries at runtime
+            # relative their wheels installation.
+            ldflag = "-Wl,--disable-new-dtags"
+            if ext.name == "cuda.bindings._bindings.cynvrtc":
+                ldflag += f",-rpath,$ORIGIN/../../../nvidia/cuda_nvrtc/lib"
+            elif ext.name == "cuda.bindings._internal.nvjitlink":
+                ldflag += f",-rpath,$ORIGIN/../../../nvidia/nvjitlink/lib"
+
+            extra_linker_flags.append(ldflag)
+        else:
+            extra_linker_flags = []
+
+        ext.extra_link_args += extra_linker_flags
+        super().build_extension(ext)
 
 
-cmdclass = {"build_ext": ParallelBuildExtensions}
+cmdclass = {
+    "bdist_wheel": WheelsBuildExtensions,
+    "build_ext": ParallelBuildExtensions,
+    }
 
 # ----------------------------------------------------------------------
 # Setup