[llvm] [VPlan] Add new VPInstruction ocpode for header mask. (PR #89603)

[via llvm-commits]

================
@@ -1180,6 +1180,9 @@ class VPInstruction : public VPRecipeWithIRFlags {
     // operand). Only generates scalar values (either for the first lane only or
     // for all lanes, depending on its uses).
     PtrAdd,
+    // An abstract representation of the vector loops header mask, to be lowered
+    // later depending on target preference.
+    HeaderMask,
----------------
ayalz wrote:

nit: would be good to list in lex order, so better placed before PtrAdd.

https://github.com/llvm/llvm-project/pull/89603