`IntrConvergent` was originally added to `dx.resource.getpointer` to
prevent optimization passes (`SimplifyCFG`, `GVN`) from sinking the
intrinsic out of control flow branches, which would create phi nodes on
the returned pointer.
Using `IntrInaccessibleMemOnly` and `IntrReadMem` semantics still
prevent passes from merging or sinking identical calls across branches.
However, this allows the call to be moved within a single control flow
path.
Updates relevant tests and adds a new test to demonstrate a now legal
potential optimization.
This was discovered when
https://github.com/llvm/llvm-project/pull/188792 caused the following
failure:
https://github.com/llvm/llvm-project/actions/runs/24577221310/job/71865579618.
When emitting convergence control tokens, each resource access is then a
user of the convergence control tokens, which makes it's use more
unnecessarily restrictive for optimizations and in this case would
prevent a loop unroll from taking place.
Assisted by: Claude Opus 4.6
63e36755de