This adds a '--no-implicit-module' option, which disables the insertion
of a top-level 'builtin.module' during parsing.
The translation APIs are also updated to take/return 'Operation*'
instead of 'ModuleOp', to allow other operation types to be used. To
simplify translations which are restricted to specific operation types,
'TranslateFromMLIRRegistration' has an overload which performs the
necessary cast and error checking.
Reviewed By: rriddle
Differential Revision: https://reviews.llvm.org/D134237
This patch takes the first step towards a more principled modeling of undefined behavior in MLIR as discussed in the following discourse threads:
1. https://discourse.llvm.org/t/semantics-modeling-undefined-behavior-and-side-effects/4812
2. https://discourse.llvm.org/t/rfc-mark-tensor-dim-and-memref-dim-as-side-effecting/65729
This patch in particular does the following:
1. Introduces a ConditionallySpeculatable OpInterface that dynamically determines whether an Operation can be speculated.
2. Re-defines `NoSideEffect` to allow undefined behavior, making it necessary but not sufficient for speculation. Also renames it to `NoMemoryEffect`.
3. Makes LICM respect the above semantics.
4. Changes all ops tagged with `NoSideEffect` today to additionally implement ConditionallySpeculatable and mark themselves as always speculatable. This combined trait is named `Pure`. This makes this change NFC.
For out of tree dialects:
1. Replace `NoSideEffect` with `Pure` if the operation does not have any memory effects, undefined behavior or infinite loops.
2. Replace `NoSideEffect` with `NoSideEffect` otherwise.
The next steps in this process are (I'm proposing to do these in upcoming patches):
1. Update operations like `tensor.dim`, `memref.dim`, `scf.for`, `affine.for` to implement a correct hook for `ConditionallySpeculatable`. I'm also happy to update ops in other dialects if the respective dialect owners would like to and can give me some pointers.
2. Update other passes that speculate operations to consult `ConditionallySpeculatable` in addition to `NoMemoryEffect`. I could not find any other than LICM on a quick skim, but I could have missed some.
3. Add some documentation / FAQs detailing the differences between side effects, undefined behavior, speculatabilty.
Reviewed By: rriddle, mehdi_amini
Differential Revision: https://reviews.llvm.org/D135505
Most dialects have already flipped to prefixed, and the intention to switch
has been telegraphed for a while.
Differential Revision: https://reviews.llvm.org/D133179
This reverts commit 0816b629c9da5aa8885c4cb3fbbf5c905d37f0ee.
Reason: Broke the sanitizer buildbots. More information available in the
original phabricator review: https://reviews.llvm.org/D132726
Now that C++17 is enabled in LLVM, a lot of the TODOs and patterns to emulate C++17 features can be eliminated.
The steps I have taken were essentially:
```
git grep C++17
git grep c++17
git grep "initializer_list<int>"
```
and address given comments and patterns.
Most of the changes boiled down to just using fold expressions rather than initializer_list.
While doing this I also discovered that Clang by default restricts the depth of fold expressions to 256 elements. I specifically hit this with `TestDialect` in `addOperations`. I opted to not replace it with fold expressions because of that but instead adding a comment documenting the issue.
If any other functions may be called with more than 256 elements in the future we might have to revert other parts as well.
I don't think this is a common occurence besides the `TestDialect` however. If need be, this could potentially be fixed via `mlir-tblgen` in the future.
Differential Revision: https://reviews.llvm.org/D131323
Since the very first commits, the Python and C MLIR APIs have had mis-placed registration/load functionality for dialects, extensions, etc. This was done pragmatically in order to get bootstrapped and then just grew in. Downstreams largely bypass and do their own thing by providing various APIs to register things they need. Meanwhile, the C++ APIs have stabilized around this and it would make sense to follow suit.
The thing we have observed in canonical usage by downstreams is that each downstream tends to have native entry points that configure its installation to its preferences with one-stop APIs. This patch leans in to this approach with `RegisterEverything.h` and `mlir._mlir_libs._mlirRegisterEverything` being the one-stop entry points for the "upstream packages". The `_mlir_libs.__init__.py` now allows customization of the environment and Context by adding "initialization modules" to the `_mlir_libs` package. If present, `_mlirRegisterEverything` is treated as such a module. Others can be added by downstreams by adding a `_site_initialize_{i}.py` module, where '{i}' is a number starting with zero. The number will be incremented and corresponding module loaded until one is not found. Initialization modules can:
* Perform load time customization to the global environment (i.e. registering passes, hooks, etc).
* Define a `register_dialects(registry: DialectRegistry)` function that can extend the `DialectRegistry` that will be used to bootstrap the `Context`.
* Define a `context_init_hook(context: Context)` function that will be added to a list of callbacks which will be invoked after dialect registration during `Context` initialization.
Note that the `MLIRPythonExtension.RegisterEverything` is not included by default when building a downstream (its corresponding behavior was prior). For downstreams which need the default MLIR initialization to take place, they must add this back in to their Python CMake build just like they add their own components (i.e. to `add_mlir_python_common_capi_library` and `add_mlir_python_modules`). It is perfectly valid to not do this, in which case, only the things explicitly depended on and initialized by downstreams will be built/packaged. If the downstream has not been set up for this, it is recommended to simply add this back for the time being and pay the build time/package size cost.
CMake changes:
* `MLIRCAPIRegistration` -> `MLIRCAPIRegisterEverything` (renamed to signify what it does and force an evaluation: a number of places were incidentally linking this very expensive target)
* `MLIRPythonSoure.Passes` removed (without replacement: just drop)
* `MLIRPythonExtension.AllPassesRegistration` removed (without replacement: just drop)
* `MLIRPythonExtension.Conversions` removed (without replacement: just drop)
* `MLIRPythonExtension.Transforms` removed (without replacement: just drop)
Header changes:
* `mlir-c/Registration.h` is deleted. Dialect registration functionality is now in `IR.h`. Registration of upstream features are in `mlir-c/RegisterEverything.h`. When updating MLIR and a couple of downstreams, I found that proper usage was commingled so required making a choice vs just blind S&R.
Python APIs removed:
* mlir.transforms and mlir.conversions (previously only had an __init__.py which indirectly triggered `mlirRegisterTransformsPasses()` and `mlirRegisterConversionPasses()` respectively). Downstream impact: Remove these imports if present (they now happen as part of default initialization).
* mlir._mlir_libs._all_passes_registration, mlir._mlir_libs._mlirTransforms, mlir._mlir_libs._mlirConversions. Downstream impact: None expected (these were internally used).
C-APIs changed:
* mlirRegisterAllDialects(MlirContext) now takes an MlirDialectRegistry instead. It also used to trigger loading of all dialects, which was already marked with a TODO to remove -- it no longer does, and for direct use, dialects must be explicitly loaded. Downstream impact: Direct C-API users must ensure that needed dialects are loaded or call `mlirContextLoadAllAvailableDialects(MlirContext)` to emulate the prior behavior. Also see the `ir.c` test case (e.g. ` mlirContextGetOrLoadDialect(ctx, mlirStringRefCreateFromCString("func"));`).
* mlirDialectHandle* APIs were moved from Registration.h (which now is restricted to just global/upstream registration) to IR.h, arguably where it should have been. Downstream impact: include correct header (likely already doing so).
C-APIs added:
* mlirContextLoadAllAvailableDialects(MlirContext): Corresponds to C++ API with the same purpose.
Python APIs added:
* mlir.ir.DialectRegistry: Mapping for an MlirDialectRegistry.
* mlir.ir.Context.append_dialect_registry(MlirDialectRegistry)
* mlir.ir.Context.load_all_available_dialects()
* mlir._mlir_libs._mlirAllRegistration: New native extension that exposes a `register_dialects(MlirDialectRegistry)` entry point and performs all upstream pass/conversion/transforms registration on init. In this first step, we eagerly load this as part of the __init__.py and use it to monkey patch the Context to emulate prior behavior.
* Type caster and capsule support for MlirDialectRegistry
This should make it possible to build downstream Python dialects that only depend on a subset of MLIR. See: https://github.com/llvm/llvm-project/issues/56037
Here is an example PR, minimally adapting IREE to these changes: https://github.com/iree-org/iree/pull/9638/files In this situation, IREE is opting to not link everything, since it is already configuring the Context to its liking. For projects that would just like to not think about it and pull in everything, add `MLIRPythonExtension.RegisterEverything` to the list of Python sources getting built, and the old behavior will continue.
Reviewed By: mehdi_amini, ftynse
Differential Revision: https://reviews.llvm.org/D128593
Marked all dialects that could be (reasonably) easily flipped to _Both
prefix. Updating the accessors to prefixed form will happen in follow
up, this was to flush out conflicts and to mark all dialects explicitly
as I plan to flip OpBase default to _Prefixed to avoid needing to
migrate new dialects.
Except for Standalone example which got flipped to _Prefixed.
Differential Revision: https://reviews.llvm.org/D128027
Since these are unused, I've removed them from the configuration, so that it can be easier to read and follow.
Reviewed By: stellaraccident
Differential Revision: https://reviews.llvm.org/D125132
This allows for inferring the result types of operations in certain situations by using the type of
an operand. This commit allowed for automatically supporting type inference for many more
operations with no additional effort, e.g. nearly all Arithmetic operations now support
result type inferrence with no additional changes.
Differential Revision: https://reviews.llvm.org/D124581
This clarifies that this is an LLVM specific variable and avoids
potential conflicts with other projects.
Differential Revision: https://reviews.llvm.org/D119918
Translation.h is currently awkwardly shoved into the top-level mlir, even though it is
specific to the mlir-translate tool. This commit moves it to a new Tools/mlir-translate
directory, which is intended for libraries used to implement tools. It also splits the
translate registry from the main entry point, to more closely mirror what mlir-opt
does.
Differential Revision: https://reviews.llvm.org/D121026
MlirOptMain is currently awkwardly shoved into mlir/Support. This commit
moves it to the Tools/ directory, which is intended for libraries used to
implement tools.
Differential Revision: https://reviews.llvm.org/D121025
The last remaining operations in the standard dialect all revolve around
FuncOp/function related constructs. This patch simply handles the initial
renaming (which by itself is already huge), but there are a large number
of cleanups unlocked/necessary afterwards:
* Removing a bunch of unnecessary dependencies on Func
* Cleaning up the From/ToStandard conversion passes
* Preparing for the move of FuncOp to the Func dialect
See the discussion at https://discourse.llvm.org/t/standard-dialect-the-final-chapter/6061
Differential Revision: https://reviews.llvm.org/D120624
- Remove the `{Op,Attr,Type}Trait` TableGen classes and replace with `Trait`
- Rename `OpTraitList` to `TraitList` and use it in a few places
The bulk of this change is a mechanical s/OpTrait/Trait/ throughout the codebase.
Reviewed By: rriddle, jpienaar, herhut
Differential Revision: https://reviews.llvm.org/D118543
Step towards removing the hard coded behavior for this trait and to instead use common interface.
Differential Revision: https://reviews.llvm.org/D114208
Re-applies D111513:
* Adds a full-fledged Python example dialect and tests to the Standalone example (need to do a bit of tweaking in the top level CMake and lit tests to adapt better to if not building with Python enabled).
* Rips out remnants of custom extension building in favor of pybind11_add_module which does the right thing.
* Makes python and extension sources installable (outputs to src/python/${name} in the install tree): Both Python and C++ extension sources get installed as downstreams need all of this in order to build a derived version of the API.
* Exports sources targets (with our properties that make everything work) by converting them to INTERFACE libraries (which have export support), as recommended for the forseeable future by CMake devs. Renames custom properties to start with lower-case letter, as also recommended/required (groan).
* Adds a ROOT_DIR argument to declare_mlir_python_extension since now all C++ sources for an extension must be under the same directory (to line up at install time).
* Downstreams will need to adapt by:
* Remove absolute paths from any SOURCES for declare_mlir_python_extension (I believe all downstreams are just using ${CMAKE_CURRENT_SOURCE_DIR} here, which can just be ommitted). May need to set ROOT_DIR if not relative to the current source directory.
* To allow further downstreams to install/build, will need to make sure that all C++ extension headers are also listed under SOURCES for declare_mlir_python_extension.
This reverts commit 1a6c26d1f52999edbfbf6a978ae3f0e6759ea755.
Reviewed By: stephenneuendorffer
Differential Revision: https://reviews.llvm.org/D113732
* Depends on D111504, which provides the boilerplate for building aggregate shared libraries from installed MLIR.
* Adds a full-fledged Python example dialect and tests to the Standalone example (need to do a bit of tweaking in the top level CMake and lit tests to adapt better to if not building with Python enabled).
* Rips out remnants of custom extension building in favor of `pybind11_add_module` which does the right thing.
* Makes python and extension sources installable (outputs to src/python/${name} in the install tree): Both Python and C++ extension sources get installed as downstreams need all of this in order to build a derived version of the API.
* Exports sources targets (with our properties that make everything work) by converting them to INTERFACE libraries (which have export support), as recommended for the forseeable future by CMake devs. Renames custom properties to start with lower-case letter, as also recommended/required (groan).
* Adds a ROOT_DIR argument to `declare_mlir_python_extension` since now all C++ sources for an extension must be under the same directory (to line up at install time).
* Need to validate against a downstream or two and adjust, prior to submitting.
Downstreams will need to adapt by:
* Remove absolute paths from any SOURCES for `declare_mlir_python_extension` (I believe all downstreams are just using `${CMAKE_CURRENT_SOURCE_DIR}` here, which can just be ommitted). May need to set `ROOT_DIR` if not relative to the current source directory.
* To allow further downstreams to install/build, will need to make sure that all C++ extension headers are also listed under SOURCES for `declare_mlir_python_extension`.
Reviewed By: stephenneuendorffer, mikeurbach
Differential Revision: https://reviews.llvm.org/D111513
* Incorporates a reworked version of D106419 (which I have closed but has comments on it).
* Extends the standalone example to include a minimal CAPI (for registering its dialect) and a test which, from out of tree, creates an aggregate dylib and links a little sample program against it. This will likely only work today in *static* MLIR builds (until the TypeID fiasco is finally put to bed). It should work on all platforms, though (including Windows - albeit I haven't tried this exact incarnation there).
* This is the biggest pre-requisite to being able to build out of tree MLIR Python-based projects from an installed MLIR/LLVM.
* I am rather nauseated by the CMake shenanigans I had to endure to get this working. The primary complexity, above and beyond the previous patch is because (with no reason given), it is impossible to export target properties that contain generator expressions... because, of course it isn't. In this case, the primary reason we use generator expressions on the individual embedded libraries is to support arbitrary ordering. Since that need doesn't apply to out of tree (which import everything via FindPackage at the outset), we fall back to a more imperative way of doing the same thing if we detect that the target was imported. Gross, but I don't expect it to need a lot of maintenance.
* There should be a relatively straight-forward path from here to rebase libMLIR.so on top of this facility and also make it include the CAPI.
Differential Revision: https://reviews.llvm.org/D111504
Precursor: https://reviews.llvm.org/D110200
Removed redundant ops from the standard dialect that were moved to the
`arith` or `math` dialects.
Renamed all instances of operations in the codebase and in tests.
Reviewed By: rriddle, jpienaar
Differential Revision: https://reviews.llvm.org/D110797
* Previously, we were only generating .h.inc files. We foresee the need to also generate implementations and this is a step towards that.
* Discussed in https://llvm.discourse.group/t/generating-cpp-inc-files-for-dialects/3732/2
* Deviates from the discussion above by generating a default constructor in the .cpp.inc file (and adding a tablegen bit that disables this in case if this is user provided).
* Generating the destructor started as a way to flush out the missing includes (produces a link error), but it is a strict improvement on its own that is worth doing (i.e. by emitting key methods in the .cpp file, we root vtables in one translation unit, which is a non-controversial improvement).
Differential Revision: https://reviews.llvm.org/D105070
At present, a lot of code contains main function bodies like "return failed(mlir::MlirOptMain(...);". This is unfortunate for two reasons: a) it uses ADL, which is maybe not what the free "failed" function was designed for; and b) it is a bit awkward to read, requring the reader to both understand the boolean nature of the value and the semantics of main's return value. (And it's also not portable, since 1 is not a portable success value.)
The replacement code, `return mlir::AsMainReturnCode(mlir::MlirOptMain(...))` is a bit more self-explanatory.
The change applies the new function to a few internal uses of MlirOptMain, too.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D102641
This is useful for expressing specific table-gen options, like selecting
a particular dialect to print.
Use it to fix the documentation for the `pdl_interp` dialect which is now
generating the first dialect it finds in its input which is `pdl`.
Differential Revision: https://reviews.llvm.org/D100517
Port the translation of five dialects that define LLVM IR intrinsics
(LLVMAVX512, LLVMArmNeon, LLVMArmSVE, NVVM, ROCDL) to the new dialect
interface-based mechanism. This allows us to remove individual translations
that were created for each of these dialects and just use one common
MLIR-to-LLVM-IR translation that potentially supports all dialects instead,
based on what is registered and including any combination of translatable
dialects. This removal was one of the main goals of the refactoring.
To support the addition of GPU-related metadata, the translation interface is
extended with the `amendOperation` function that allows the interface
implementation to post-process any translated operation with dialect attributes
from the dialect for which the interface is implemented regardless of the
operation's dialect. This is currently applied to "kernel" functions, but can
be used to construct other metadata in dialect-specific ways without
necessarily affecting operations.
Depends On D96591, D96504
Reviewed By: nicolasvasilache
Differential Revision: https://reviews.llvm.org/D96592
Multi-configuration generators (such as Visual Studio and Xcode) allow the specification of a build flavor at build time instead of config time, so the lit configuration files need to support that - and they do for the most part. There are several places that had one of two issues (or both!):
1) Paths had %(build_mode)s set up, but then not configured, resulting in values that would not work correctly e.g. D:/llvm-build/%(build_mode)s/bin/dsymutil.exe
2) Paths did not have %(build_mode)s set up, but instead contained $(Configuration) (which is the value for Visual Studio at configuration time, for Xcode they would have had the equivalent) e.g. "D:/llvm-build/$(Configuration)/lib".
This seems to indicate that we still have a lot of fragility in the configurations, but also that a number of these paths are never used (at least on Windows) since the errors appear to have been there a while.
This patch fixes the configurations and it has been tested with Ninja and Visual Studio to generate the correct paths. We should consider removing some of these settings altogether.
Reviewed By: JDevlieghere, mehdi_amini
Differential Revision: https://reviews.llvm.org/D96427
cmake_minimum_required(VERSION) calls cmake_policy(VERSION),
which sets all policies up to VERSION to NEW.
LLVM started requiring CMake 3.13 last year, so we can remove
a bunch of code setting policies prior to 3.13 to NEW as it
no longer has any effect.
Reviewed By: phosek, #libunwind, #libc, #libc_abi, ldionne
Differential Revision: https://reviews.llvm.org/D94374
Implement Bug 46698, making ODS synthesize a getType() method that returns a
specific C++ class for OneResult methods where we know that class. This eliminates
a common source of casts in things like:
myOp.getType().cast<FIRRTLType>().getPassive()
because we know that myOp always returns a FIRRTLType. This also encourages
op authors to type their results more tightly (which is also good for
verification).
I chose to implement this by splitting the OneResult trait into itself plus a
OneTypedResult trait, given that many things are using `hasTrait<OneResult>`
to conditionalize various logic.
While this changes makes many many ops get more specific getType() results, it
is generally drop-in compatible with the previous behavior because 'x.cast<T>()'
is allowed when x is already known to be a T. The one exception to this is that
we need declarations of the types used by ops, which is why a couple headers
needed additional #includes.
I updated a few things in tree to remove the now-redundant `.cast<>`'s, but there
are probably many more than can be removed.
Differential Revision: https://reviews.llvm.org/D93790
This reverts commit e9b87f43bde8b5f0d8a79c5884fdce639b12e0ca.
There are issues with macros generating macros without an obvious simple fix
so I'm going to revert this and try something different.
New projects (particularly out of tree) have a tendency to hijack the existing
llvm configuration options and build targets (add_llvm_library,
add_llvm_tool). This can lead to some confusion.
1) When querying a configuration variable, do we care about how LLVM was
configured, or how these options were configured for the out of tree project?
2) LLVM has lots of defaults, which are easy to miss
(e.g. LLVM_BUILD_TOOLS=ON). These options all need to be duplicated in the
CMakeLists.txt for the project.
In addition, with LLVM Incubators coming online, we need better ways for these
incubators to do things the "LLVM way" without alot of futzing. Ideally, this
would happen in a way that eases importing into the LLVM monorepo when
projects mature.
This patch creates some generic infrastructure in llvm/cmake/modules and
refactors MLIR to use this infrastructure. This should expand to include
add_xxx_library, which is by far the most complicated bit of building a
project correctly, since it has to deal with lots of shared library
configuration bits. (MLIR currently hijacks the LLVM infrastructure for
building libMLIR.so, so this needs to get refactored anyway.)
Differential Revision: https://reviews.llvm.org/D85140
This refactors the standalone-translate executable to use mlirTranslateMain() declared in Translation.h and further applies D87129.
Reviewed By: jpienaar
Differential Revision: https://reviews.llvm.org/D87131
This changes the behavior of constructing MLIRContext to no longer load globally
registered dialects on construction. Instead Dialects are only loaded explicitly
on demand:
- the Parser is lazily loading Dialects in the context as it encounters them
during parsing. This is the only purpose for registering dialects and not load
them in the context.
- Passes are expected to declare the dialects they will create entity from
(Operations, Attributes, or Types), and the PassManager is loading Dialects into
the Context when starting a pipeline.
This changes simplifies the configuration of the registration: a compiler only
need to load the dialect for the IR it will emit, and the optimizer is
self-contained and load the required Dialects. For example in the Toy tutorial,
the compiler only needs to load the Toy dialect in the Context, all the others
(linalg, affine, std, LLVM, ...) are automatically loaded depending on the
optimization pipeline enabled.
To adjust to this change, stop using the existing dialect registration: the
global registry will be removed soon.
1) For passes, you need to override the method:
virtual void getDependentDialects(DialectRegistry ®istry) const {}
and registery on the provided registry any dialect that this pass can produce.
Passes defined in TableGen can provide this list in the dependentDialects list
field.
2) For dialects, on construction you can register dependent dialects using the
provided MLIRContext: `context.getOrLoadDialect<DialectName>()`
This is useful if a dialect may canonicalize or have interfaces involving
another dialect.
3) For loading IR, dialect that can be in the input file must be explicitly
registered with the context. `MlirOptMain()` is taking an explicit registry for
this purpose. See how the standalone-opt.cpp example is setup:
mlir::DialectRegistry registry;
registry.insert<mlir::standalone::StandaloneDialect>();
registry.insert<mlir::StandardOpsDialect>();
Only operations from these two dialects can be in the input file. To include all
of the dialects in MLIR Core, you can populate the registry this way:
mlir::registerAllDialects(registry);
4) For `mlir-translate` callback, as well as frontend, Dialects can be loaded in
the context before emitting the IR: context.getOrLoadDialect<ToyDialect>()
Differential Revision: https://reviews.llvm.org/D85622
This changes the behavior of constructing MLIRContext to no longer load globally
registered dialects on construction. Instead Dialects are only loaded explicitly
on demand:
- the Parser is lazily loading Dialects in the context as it encounters them
during parsing. This is the only purpose for registering dialects and not load
them in the context.
- Passes are expected to declare the dialects they will create entity from
(Operations, Attributes, or Types), and the PassManager is loading Dialects into
the Context when starting a pipeline.
This changes simplifies the configuration of the registration: a compiler only
need to load the dialect for the IR it will emit, and the optimizer is
self-contained and load the required Dialects. For example in the Toy tutorial,
the compiler only needs to load the Toy dialect in the Context, all the others
(linalg, affine, std, LLVM, ...) are automatically loaded depending on the
optimization pipeline enabled.
To adjust to this change, stop using the existing dialect registration: the
global registry will be removed soon.
1) For passes, you need to override the method:
virtual void getDependentDialects(DialectRegistry ®istry) const {}
and registery on the provided registry any dialect that this pass can produce.
Passes defined in TableGen can provide this list in the dependentDialects list
field.
2) For dialects, on construction you can register dependent dialects using the
provided MLIRContext: `context.getOrLoadDialect<DialectName>()`
This is useful if a dialect may canonicalize or have interfaces involving
another dialect.
3) For loading IR, dialect that can be in the input file must be explicitly
registered with the context. `MlirOptMain()` is taking an explicit registry for
this purpose. See how the standalone-opt.cpp example is setup:
mlir::DialectRegistry registry;
registry.insert<mlir::standalone::StandaloneDialect>();
registry.insert<mlir::StandardOpsDialect>();
Only operations from these two dialects can be in the input file. To include all
of the dialects in MLIR Core, you can populate the registry this way:
mlir::registerAllDialects(registry);
4) For `mlir-translate` callback, as well as frontend, Dialects can be loaded in
the context before emitting the IR: context.getOrLoadDialect<ToyDialect>()
Differential Revision: https://reviews.llvm.org/D85622
