[llvm-branch-commits] [DSE] Make DSE eliminate stores to objects with a sized dead_on_return (PR #173694)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/173694

dead_on_return is made optionally sized in #171712. This patch adds
handling in DSE so that we can actually eliminate stores to pointer
parameters marked with a sized dead_on_return attribute. We do not
eliminate stores where the store may overlap with bytes that are not
known to be dead after return.