pytorch

3efd5d8f - Introduce tools.codegen.api.translate (#49122)

Introduce tools.codegen.api.translate (#49122) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/49122 cpparguments_exprs has induced a lot of head scratching in many recent PRs for how to structure the code in a good way. This PR eliminates the old algorithm for an entirely new algorithm inspired by logic programming. The net result is shorter, cleaner and should be more robust to future changes. This PR is a bit of a whopper. Here is the order to review it. - tools/codegen/api/types.py - Deleted CppArgument, CppArgumentPackIface (and subclasses), CppExpr, DispatcherExpr, DispatcherArgument, NativeExpr, NativeArgument, MetaArgument. All things previously called XArgument are now Binding. All things previously called XExpr are now Expr. I deleted the `__str__` implementation on Binding and fixed all call sites not to use it. On Binding, I renamed `str_no_default` and `str_default` to `defn` and `decl` for better symmetry with the corresponding signature concepts, although I'm open to naming them back to their original versions. - Obviously, things are less type safe without the class distinctions. So I introduce a new ADT called CType. CType represents the *semantic C++ type* of a binding: it is both the C++ type (e.g., `const Tensor&`) as well as the argument name that specifies what the binding denotes (e.g., `other`). Every binding now records its CType. The key observation here is that you don't actually care if a given expression is from the cpp or dispatcher or native API; what you care is having enough information to know what the expression means, so you can use it appropriately. CType has this information. For the most part, ArgNames are just the string names of the arguments as you see them in JIT schema, but there is one case (`possibly_redundant_memory_format`) where we encode a little extra information. Unlike the plain strings we previously used to represent C++ types, CType have a little bit of structure around optional and references, because the translation code needs to work around these concepts. - I took the opportunity to kill all of the private fields like `_arguments` and `_returns_type` (since the argument types don't make sense anymore). Everything is computed for you on the fly. If this is a perf problem in codegen we can start using `cached_property` decorator. - All of the heavy lifting in CppSignature.argument_packs has been moved to the cpp module. We'll head over there next. Similarly, all of the exprs methods are now calling translate, the new functionality which we haven't gotten to yet - tools/codegen/api/cpp.py - We refactor all of the type computation functions to return CType instead of str. Because CTypes need to know the denotation, there is a new `binds: ArgName` argument to most functions that provides the denotation, so we can slot it in. (An alternative would have been to construct CTypes without denotations and then fill them in post-facto, but I didn't do it this way. One downside is there are some places where I need a CType without denotation, so I fill these in with `__placeholder__` whenever this happens). - `argument` and `arguments` are now extremely simple. There is no more Pack business, just produce one or more Bindings. The one thing of note is that when both a `memory_format` and `options` are in scope, we label the memory format as `possibly_redundant_memory_format`. This will be used in translation - tools/codegen/api/dispatcher.py and tools/codegen/api/native.py - same deal as cpp.py. One thing is that `cpparguments_exprs` is deleted; that is in the translator - tools/codegen/api/translate.py - the translator! It uses a very simple backwards deduction engine to work out how to fill in the arguments of functions. There are comments in the file that explain how it works. - Everything else: just some small call site tweaks for places when I changed API. Signed-off-by: Edward Z. Yang <ezyang@fb.com> Test Plan: Imported from OSS Reviewed By: ljk53 Differential Revision: D25455887 Pulled By: ezyang fbshipit-source-id: 90dc58d420d4cc49281aa8647987c69f3ed42fa6