Transform interfaces are implemented, direction or via extensions, in
libraries belonging to multiple other dialects. Those dialects don't
need to depend on the non-interface part of the transform dialect, which
includes the growing number of ops and transitive dependency footprint.
Split out the interfaces into a separate library. This in turn requires
flipping the dependency from the interface on the dialect that has crept
in because both co-existed in one library. The interface shouldn't
depend on the transform dialect either.
As a consequence of splitting, the capability of the interpreter to
automatically walk the payload IR to identify payload ops of a certain
kind based on the type used for the entry point symbol argument is
disabled. This is a good move by itself as it simplifies the interpreter
logic. This functionality can be trivially replaced by a
`transform.structured.match` operation.
This revision significantly simplifies the specification and implementation of mapping loops to GPU ids.
Each type of mapping (block, warpgroup, warp, thread) now comes with 2 mapping modes:
1. a 3-D "grid-like" mode, subject to alignment considerations on threadIdx.x, on which predication
may occur on a per-dimension 3-D sub-rectangle basis.
2. a n-D linearized mode, on which predication may only occur on a linear basis.
In the process, better size and alignment requirement inference are introduced along with improved runtime verification messages.
The `warp_dims` attribute was deemed confusing and is removed from the transform in favor of better size inference.
Differential Revision: https://reviews.llvm.org/D155941
