a3d41879ec
Add `gen-type-constraint-decls` and `gen-type-constraint-defs`, which generate public C++ functions for type constraints. The name of the C++ function is specified in the `cppFunctionName` field. Type constraints are typically used for op/type/attribute verification. They are also sometimes called from builders and transformations. Until now, this required duplicating the check in C++. Note: This commit just adds the option for type constraints, but attribute constraints could be supported in the same way. Alternatives considered: 1. The C++ functions could also be generated as part of `gen-typedef-decls/defs`, but that can be confusing because type constraints may rely on type definitions from multiple `.td` files. `#include`s could cause duplicate definitions of the same type constraint. 2. The C++ functions could also be generated as static member functions of dialects, but they don't really belong to a dialect. (Because they may rely on type definitions from multiple dialects.)
60 lines
2.2 KiB
Markdown
60 lines
2.2 KiB
Markdown
# Constraints
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[TOC]
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## Attribute / Type Constraints
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When defining the arguments of an operation in TableGen, users can specify
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either plain attributes/types or use attribute/type constraints to levy
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additional requirements on the attribute value or operand type.
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```tablegen
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def My_Type1 : MyDialect_Type<"Type1", "type1"> { ... }
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def My_Type2 : MyDialect_Type<"Type2", "type2"> { ... }
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// Plain type
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let arguments = (ins MyType1:$val);
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// Type constraint
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let arguments = (ins AnyTypeOf<[MyType1, MyType2]>:$val);
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```
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`AnyTypeOf` is an example for a type constraints. Many useful type constraints
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can be found in `mlir/IR/CommonTypeConstraints.td`. Additional verification
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code is generated for type/attribute constraints. Type constraints can not only
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be used when defining operation arguments, but also when defining type
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parameters.
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Optionally, C++ functions can be generated, so that type constraints can be
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checked from C++. The name of the C++ function must be specified in the
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`cppFunctionName` field. If no function name is specified, no C++ function is
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emitted.
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```tablegen
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// Example: Element type constraint for VectorType
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def Builtin_VectorTypeElementType : AnyTypeOf<[AnyInteger, Index, AnyFloat]> {
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let cppFunctionName = "isValidVectorTypeElementType";
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}
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```
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The above example tranlates into the following C++ code:
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```c++
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bool isValidVectorTypeElementType(::mlir::Type type) {
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return (((::llvm::isa<::mlir::IntegerType>(type))) || ((::llvm::isa<::mlir::IndexType>(type))) || ((::llvm::isa<::mlir::FloatType>(type))));
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}
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```
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An extra TableGen rule is needed to emit C++ code for type constraints. This
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will generate only the declarations/definitions of the type constaraints that
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are defined in the specified `.td` file, but not those that are in included
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`.td` files.
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```cmake
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mlir_tablegen(<Your Dialect>TypeConstraints.h.inc -gen-type-constraint-decls)
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mlir_tablegen(<Your Dialect>TypeConstraints.cpp.inc -gen-type-constraint-defs)
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```
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The generated `<Your Dialect>TypeConstraints.h.inc` will need to be included
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whereever you are referencing the type constraint in C++. Note that no C++
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namespace will be emitted by the code generator. The `#include` statements of
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the `.h.inc`/`.cpp.inc` files should be wrapped in C++ namespaces by the user.
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