Introduce a new extension for simple print-debugging of the transform
dialect scripts. The initial version of this extension consists of two
ops that are printing the payload objects associated with transform
dialect values. Similar ops were already available in the test extenion
and several downstream projects, and were extensively used for testing.
This is a new attempt at #69320.
The transform dialect stores a "library module" that the preload pass
can populate. Until now, each pass registered an additional module by
simply pushing it to a vector; however, the interpreter only used the
first of them. This commit turns the registration into "loading", i.e.,
each newly added module gets merged into the existing one. This allows
the loading to be split into several passes, and using the library in
the interpreter now takes all of them into account. While this design
avoids repeated merging every time the library is accessed, it requires
that the implementation of merging modules lives in the
TransformDialect target (since it at the dialect depend on each
other).
This resolves https://github.com/llvm/llvm-project/issues/69111.
Update most test passes to use the transform-interpreter pass instead of
the test-transform-dialect-interpreter-pass. The new "main" interpreter
pass has a named entry point instead of looking up the top-level op with
`PossibleTopLevelOpTrait`, which is arguably a more understandable
interface. The change is mechanical, rewriting an unnamed sequence into
a named one and wrapping the transform IR in to a module when necessary.
Add an option to the transform-interpreter pass to target a tagged
payload op instead of the root anchor op, which is also useful for repro
generation.
Only the test in the transform dialect proper and the examples have not
been updated yet. These will be updated separately after a more careful
consideration of testing coverage of the transform interpreter logic.
