[llvm] [NFC] Add comment to describe the intention use of newly added `avail-extern-gv-in-addrspace-to-local` (PR #144911)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Shilei Tian (shiltian)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/144911.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/IPO/ElimAvailExtern.cpp (+4) 


``````````diff
diff --git a/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp b/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
index bc98f994f490c..538755e66f9cf 100644
--- a/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
+++ b/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
@@ -35,6 +35,10 @@ static cl::opt<bool> ConvertToLocal(
     cl::desc("Convert available_externally into locals, renaming them "
              "to avoid link-time clashes."));
 
+// This option was originally introduced to correctly support the lowering of
+// LDS variables for AMDGPU when ThinLTO is enabled. It can be utilized for
+// other purposes, but make sure it is safe to do so, as privatizing global
+// variables is generally not safe.
 static cl::opt<unsigned> ConvertGlobalVariableInAddrSpace(
     "avail-extern-gv-in-addrspace-to-local", cl::Hidden,
     cl::desc(

``````````

</details>


https://github.com/llvm/llvm-project/pull/144911