b4bb2f8aef
Since `llvm.experimental.noalias.scope.decl` is marked as
`memory(inaccessiblemem: readwrite)`, we cannot treat this annotation
intrinsic as having no side effects. It will block loop deletion when
this intrinsic exists inside a dead loop:
3dad29b677/llvm/lib/Transforms/Scalar/LoopDeletion.cpp (L103-L110)
This patch marks `llvm.experimental.noalias.scope.decl` as droppable to
address the issue.
Fixes https://github.com/llvm/llvm-project/issues/108052.