[mlir] Use unique_function in AbstractOperation fields

[math-fehr]

Summary

Currently, AbstractOperation fields are function pointers.
Modifying them to unique_function allow them to contain
runtime information.

For instance, this allows operations to be defined at runtime.

[math-fehr]

Remove unneeded lambdas, and attempt to fix compilation on windows

[math-fehr]

Try to fix windows compilation

[math-fehr]

Try to fix windows compilation

[math-fehr]

Comment compilation problem on Windows

[math-fehr]

There seems to be a compilation problem on windows, and my last two patches fix it.

Basically, if A is a class and foo a templated static method of A, then constructing a unique_function with unique_function(&A::foo<Args>) triggers a compilation error C2298 on windows. I believe that this is a bug in the windows compiler, since this is a pointer to a static method.

I found a workaround using lambdas to make my code work on windows, but I believe that this can have a runtime cost.
I would be interested if anyone has a better solution!

[rriddle]

mlir/include/mlir/IR/OpDefinition.h

1684

Accidental change?

1703

Just remove these comments, there won't really be any runtime cost difference to using a lambda in a majority of cases because the function will just get inlined.

1763–1766

Just use a lambda here.

mlir/lib/Parser/Parser.cpp

1806–1807

Drop the llvm:: here.

[math-fehr]

Address comments

[math-fehr]

Thanks, I addressed the comments.

Also, I do not have commit access, so could one of you land it?

mlir/include/mlir/IR/OpDefinition.h

private:
   /// The internal implementation of `getFoldHookFn` above that is invoked if
   /// the operation is single result and defines a `fold` method.
   template <typename ConcreteOpT>
   static std::enable_if_t<llvm::is_one_of<OpTrait::OneResult<ConcreteOpT>,
                                           Traits<ConcreteOpT>...>::value &&
                               detect_has_single_result_fold<ConcreteOpT>::value,
                           AbstractOperation::FoldHookFn>
   getFoldHookFnImpl() {
-    return &foldSingleResultHook<ConcreteOpT>;
+    return [](Operation *op, ArrayRef<Attribute> operands,
+              SmallVectorImpl<OpFoldResult> &results) {
+      return foldSingleResultHook<ConcreteOpT>(op, operands, results);
+    };
   }
-  /// The internal implementation of `getFoldHookFn` above that is invoked if
-  /// the operation is not single result and defines a `fold` method.
+  /// The internal implementation of `getFoldHookFn` above that
+  /// is invoked if the operation is not single result and
+  /// defines a `fold` method.
   template <typename ConcreteOpT>
   static std::enable_if_t<!llvm::is_one_of<OpTrait::OneResult<ConcreteOpT>,
                                            Traits<ConcreteOpT>...>::value &&
                               detect_has_fold<ConcreteOpT>::value,
                           AbstractOperation::FoldHookFn>
   getFoldHookFnImpl() {
-    return &foldHook<ConcreteOpT>;
+    // Windows fails to compile when giving only a pointer to the function.
+    // This is why we create a unique_function with a lambda instead.
+    return [](Operation *op, ArrayRef<Attribute> operands,
+              SmallVectorImpl<OpFoldResult> &results) {
+      return foldHook<ConcreteOpT>(op, operands, results);
+    };
   }
   /// The internal implementation of `getFoldHookFn` above that is invoked if
   /// the operation does not define a `fold` method.
   template <typename ConcreteOpT>
   static std::enable_if_t<!detect_has_single_result_fold<ConcreteOpT>::value &&
                               !detect_has_fold<ConcreteOpT>::value,
                           AbstractOperation::FoldHookFn>
   getFoldHookFnImpl() {
     // In this case, we only need to fold the traits of the operation.
     return &op_definition_impl::foldTraits<FoldableTraitsTupleT>;
   }
   /// Return the result of folding a single result operation that defines a
   /// `fold` method.
   template <typename ConcreteOpT>
   static LogicalResult
   foldSingleResultHook(Operation *op, ArrayRef<Attribute> operands,
                        SmallVectorImpl<OpFoldResult> &results) {
     OpFoldResult result = cast<ConcreteOpT>(op).fold(operands);
static AbstractOperation::PrintAssemblyFn getPrintAssemblyFn() {
     return getPrintAssemblyFnImpl<ConcreteType>();
   }
   /// The internal implementation of `getPrintAssemblyFn` that is invoked when
   /// the concrete operation does not define a `print` method.
   template <typename ConcreteOpT>
   static std::enable_if_t<!detect_has_print<ConcreteOpT>::value,
                           AbstractOperation::PrintAssemblyFn>
   getPrintAssemblyFnImpl() {
-    return &OpState::print;
+    // We need to get the right overload before passing the function
+    // to the unique_function constructor.
+    void (*fun)(Operation *, OpAsmPrinter &) = &OpState::print;
+    return fun;
   }
   /// The internal implementation of `getPrintAssemblyFn` that is invoked when
   /// the concrete operation defines a `print` method.
   template <typename ConcreteOpT>
   static std::enable_if_t<detect_has_print<ConcreteOpT>::value,
                           AbstractOperation::PrintAssemblyFn>
   getPrintAssemblyFnImpl() {
     return &printAssembly;

mlir/include/mlir/IR/OperationSupport.h

 //===----------------------------------------------------------------------===//
 
 /// This is a "type erased" representation of a registered operation.  This
 /// should only be used by things like the AsmPrinter and other things that need
 /// to be parameterized by generic operation hooks.  Most user code should use
 /// the concrete operation types.
 class AbstractOperation {
 public:
-  using GetCanonicalizationPatternsFn = void (*)(RewritePatternSet &,
-                                                 MLIRContext *);
-  using FoldHookFn = LogicalResult (*)(Operation *, ArrayRef<Attribute>,
-                                       SmallVectorImpl<OpFoldResult> &);
-  using HasTraitFn = bool (*)(TypeID);
-  using ParseAssemblyFn = ParseResult (*)(OpAsmParser &, OperationState &);
-  using PrintAssemblyFn = void (*)(Operation *, OpAsmPrinter &);
-  using VerifyInvariantsFn = LogicalResult (*)(Operation *);
+  using GetCanonicalizationPatternsFn =
+      llvm::unique_function<void(RewritePatternSet &, MLIRContext *) const>;
+  using FoldHookFn = llvm::unique_function<LogicalResult(
+      Operation *, ArrayRef<Attribute>, SmallVectorImpl<OpFoldResult> &) const>;
+  using HasTraitFn = llvm::unique_function<bool(TypeID) const>;
+  using ParseAssemblyFn =
+      llvm::unique_function<ParseResult(OpAsmParser &, OperationState &) const>;
+  using PrintAssemblyFn =
+      llvm::unique_function<void(Operation *, OpAsmPrinter &) const>;
+  using VerifyInvariantsFn =
+      llvm::unique_function<LogicalResult(Operation *) const>;
 
   /// This is the name of the operation.
   const Identifier name;
 
   /// This is the dialect that this operation belongs to.
   Dialect &dialect;
 
   /// The unique identifier of the derived Op class.
   TypeID typeID;
 
   /// Use the specified object to parse this ops custom assembly format.
   ParseResult parseAssembly(OpAsmParser &parser, OperationState &result) const;
 
   /// Return the static hook for parsing this operation assembly.
-  ParseAssemblyFn getParseAssemblyFn() const { return parseAssemblyFn; }
+  const ParseAssemblyFn &getParseAssemblyFn() const { return parseAssemblyFn; }
 
   /// This hook implements the AsmPrinter for this operation.
   void printAssembly(Operation *op, OpAsmPrinter &p) const {
     return printAssemblyFn(op, p);
   }
 
   /// This hook implements the verifier for this operation.  It should emits an
   /// error message and returns failure if a problem is detected, or returns
insert(T::getOperationName(), dialect, TypeID::get<T>(),
            T::getVerifyInvariantsFn(), T::getFoldHookFn(),
            T::getGetCanonicalizationPatternsFn(), T::getInterfaceMap(),
            T::getHasTraitFn());
   }
 
   /// Register a new operation in a Dialect object.
   /// The use of this method is in general discouraged in favor of
   /// 'insert<CustomOp>(dialect)'.
-  static void insert(StringRef name, Dialect &dialect, TypeID typeID,
-                     ParseAssemblyFn parseAssembly,
-                     PrintAssemblyFn printAssembly,
-                     VerifyInvariantsFn verifyInvariants, FoldHookFn foldHook,
-                     GetCanonicalizationPatternsFn getCanonicalizationPatterns,
-                     detail::InterfaceMap &&interfaceMap, HasTraitFn hasTrait);
+  static void
+  insert(StringRef name, Dialect &dialect, TypeID typeID,
+         ParseAssemblyFn &&parseAssembly, PrintAssemblyFn &&printAssembly,
+         VerifyInvariantsFn &&verifyInvariants, FoldHookFn &&foldHook,
+         GetCanonicalizationPatternsFn &&getCanonicalizationPatterns,
+         detail::InterfaceMap &&interfaceMap, HasTraitFn &&hasTrait);
 
 private:
   AbstractOperation(StringRef name, Dialect &dialect, TypeID typeID,
-                    ParseAssemblyFn parseAssembly,
-                    PrintAssemblyFn printAssembly,
-                    VerifyInvariantsFn verifyInvariants, FoldHookFn foldHook,
-                    GetCanonicalizationPatternsFn getCanonicalizationPatterns,
-                    detail::InterfaceMap &&interfaceMap, HasTraitFn hasTrait);
+                    ParseAssemblyFn &&parseAssembly,
+                    PrintAssemblyFn &&printAssembly,
+                    VerifyInvariantsFn &&verifyInvariants,
+                    FoldHookFn &&foldHook,
+                    GetCanonicalizationPatternsFn &&getCanonicalizationPatterns,
+                    detail::InterfaceMap &&interfaceMap, HasTraitFn &&hasTrait);
 
   /// A map of interfaces that were registered to this operation.
   detail::InterfaceMap interfaceMap;
 
   /// Internal callback hooks provided by the op implementation.
   FoldHookFn foldHookFn;
   GetCanonicalizationPatternsFn getCanonicalizationPatternsFn;
   HasTraitFn hasTraitFn;

mlir/lib/IR/MLIRContext.cpp

const AbstractOperation *AbstractOperation::lookup(StringRef opName,
   auto it = impl.registeredOperations.find(opName);
   if (it != impl.registeredOperations.end())
     return &it->second;
   return nullptr;
 }
 
 void AbstractOperation::insert(
     StringRef name, Dialect &dialect, TypeID typeID,
-    ParseAssemblyFn parseAssembly, PrintAssemblyFn printAssembly,
-    VerifyInvariantsFn verifyInvariants, FoldHookFn foldHook,
-    GetCanonicalizationPatternsFn getCanonicalizationPatterns,
-    detail::InterfaceMap &&interfaceMap, HasTraitFn hasTrait) {
-  AbstractOperation opInfo(
-      name, dialect, typeID, parseAssembly, printAssembly, verifyInvariants,
-      foldHook, getCanonicalizationPatterns, std::move(interfaceMap), hasTrait);
+    ParseAssemblyFn &&parseAssembly, PrintAssemblyFn &&printAssembly,
+    VerifyInvariantsFn &&verifyInvariants, FoldHookFn &&foldHook,
+    GetCanonicalizationPatternsFn &&getCanonicalizationPatterns,
+    detail::InterfaceMap &&interfaceMap, HasTraitFn &&hasTrait) {
+  AbstractOperation opInfo(name, dialect, typeID, std::move(parseAssembly),
+                           std::move(printAssembly),
+                           std::move(verifyInvariants), std::move(foldHook),
+                           std::move(getCanonicalizationPatterns),
+                           std::move(interfaceMap), std::move(hasTrait));
 
   auto &impl = dialect.getContext()->getImpl();
   assert(impl.multiThreadedExecutionContext == 0 &&
          "Registering a new operation kind while in a multi-threaded execution "
          "context");
   if (!impl.registeredOperations.insert({name, std::move(opInfo)}).second) {
     llvm::errs() << "error: operation named '" << name
                  << "' is already registered.\n";
     abort();
   }
 }
 
 AbstractOperation::AbstractOperation(
     StringRef name, Dialect &dialect, TypeID typeID,
-    ParseAssemblyFn parseAssembly, PrintAssemblyFn printAssembly,
-    VerifyInvariantsFn verifyInvariants, FoldHookFn foldHook,
-    GetCanonicalizationPatternsFn getCanonicalizationPatterns,
-    detail::InterfaceMap &&interfaceMap, HasTraitFn hasTrait)
+    ParseAssemblyFn &&parseAssembly, PrintAssemblyFn &&printAssembly,
+    VerifyInvariantsFn &&verifyInvariants, FoldHookFn &&foldHook,
+    GetCanonicalizationPatternsFn &&getCanonicalizationPatterns,
+    detail::InterfaceMap &&interfaceMap, HasTraitFn &&hasTrait)
     : name(Identifier::get(name, dialect.getContext())), dialect(dialect),
       typeID(typeID), interfaceMap(std::move(interfaceMap)),
-      foldHookFn(foldHook),
-      getCanonicalizationPatternsFn(getCanonicalizationPatterns),
-      hasTraitFn(hasTrait), parseAssemblyFn(parseAssembly),
-      printAssemblyFn(printAssembly), verifyInvariantsFn(verifyInvariants) {}
+      foldHookFn(std::move(foldHook)),
+      getCanonicalizationPatternsFn(std::move(getCanonicalizationPatterns)),
+      hasTraitFn(std::move(hasTrait)),
+      parseAssemblyFn(std::move(parseAssembly)),
+      printAssemblyFn(std::move(printAssembly)),
+      verifyInvariantsFn(std::move(verifyInvariants)) {}
 
 //===----------------------------------------------------------------------===//
 // AbstractType
 //===----------------------------------------------------------------------===//
 
 const AbstractType &AbstractType::lookup(TypeID typeID, MLIRContext *context) {
   auto &impl = context->getImpl();
   auto it = impl.registeredTypes.find(typeID);

mlir/lib/Parser/Parser.cpp

if (opName.contains('.')) {
           opName = opDefinition->name.strref();
       }
     }
   }
 
   // This is the actual hook for the custom op parsing, usually implemented by
   // the op itself (`Op::parse()`). We retrieve it either from the
   // AbstractOperation or from the Dialect.
-  std::function<ParseResult(OpAsmParser &, OperationState &)> parseAssemblyFn;
+  llvm::function_ref<ParseResult(OpAsmParser &, OperationState &)>
+      parseAssemblyFn;
   bool isIsolatedFromAbove = false;
 
   if (opDefinition) {
     parseAssemblyFn = opDefinition->getParseAssemblyFn();
     isIsolatedFromAbove =
         opDefinition->hasTrait<OpTrait::IsIsolatedFromAbove>();
   } else {
     Optional<Dialect::ParseOpHook> dialectHook;