[clang] [libclc] [clang] Add the ability to link libclc OpenCL libraries (PR #146503)

[Fraser Cormack via cfe-commits]

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@@ -2942,6 +2942,65 @@ void tools::addHIPRuntimeLibArgs(const ToolChain &TC, Compilation &C,
   }
 }
 
+void tools::addOpenCLBuiltinsLib(const Driver &D,
+                                 const llvm::opt::ArgList &DriverArgs,
+                                 llvm::opt::ArgStringList &CC1Args) {
+  // Check whether user specifies a libclc bytecode library
+  if (const Arg *A = DriverArgs.getLastArg(options::OPT_libclc_lib_EQ)) {
+    SmallVector<StringRef, 8> LibraryPaths;
+
+    // Add user defined library paths from LIBRARY_PATH.
+    std::optional<std::string> LibPath =
+        llvm::sys::Process::GetEnv("LIBRARY_PATH");
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frasercrmck wrote:

I can see that point of view, yeah. I did take this from the logic for finding the OpenMP Device RTL just above this so there's arguably precedent? I don't personally have any need for searching on `LIBRARY_PATH` so I'm happy to remove it if you like. Or should we just swap the blocks and prefer the resource directory?

https://github.com/llvm/llvm-project/pull/146503