[clang] [llvm] [NVPTX] Add NVVMUpgradeAnnotations pass to cleanup legacy annotations (PR #119261)

[Alex MacLean via llvm-commits]

================
@@ -324,14 +326,15 @@ MaybeAlign getAlign(const Function &F, unsigned Index) {
           F.getAttributes().getAttributes(Index).getStackAlignment())
     return StackAlign;
 
-  // If that is missing, check the legacy nvvm metadata
-  std::vector<unsigned> Vs;
-  bool retval = findAllNVVMAnnotation(&F, "align", Vs);
-  if (!retval)
-    return std::nullopt;
-  for (unsigned V : Vs)
-    if ((V >> 16) == Index)
-      return Align(V & 0xFFFF);
+  // check the legacy nvvm metadata only for the return value since llvm does
+  // not support stackalign attribute for this.
+  if (Index == 0) {
+    std::vector<unsigned> Vs;
+    if (findAllNVVMAnnotation(&F, "align", Vs))
----------------
AlexMaclean wrote:

Yea, I agree the NVVM annotation APIs could be cleaned up significantly, hopefully this work will remove the need for them altogether though.

https://github.com/llvm/llvm-project/pull/119261