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

[Alex MacLean via llvm-commits]

================
@@ -311,11 +311,16 @@ std::optional<unsigned> getMaxNReg(const Function &F) {
 }
 
 bool isKernelFunction(const Function &F) {
+  if (F.getCallingConv() == CallingConv::PTX_Kernel)
+    return true;
+
+  if (F.hasFnAttribute("nvvm.kernel"))
+    return true;
+
   if (const auto X = findOneNVVMAnnotation(&F, "kernel"))
     return (*X == 1);
 
-  // There is no NVVM metadata, check the calling convention
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AlexMaclean wrote:

We still have the calling convention check, I just moved it higher up in the function since it is cheaper than traversing the metadata. 

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