9fcd14d9b0
Add `gen-attr-constraint-decls` and `gen-attr-constraint-defs`, which generate public C++ functions for attribute constraints. The name of the C++ function is specified in the `cppFunctionName` field. This generalize `cppFunctionName` from `TypeConstraint` introduced in https://github.com/llvm/llvm-project/pull/104577 to be usable also in `AttrConstraint`.
63 lines
2.5 KiB
Markdown
63 lines
2.5 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/attribute constraints
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can be 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/attribute
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constraints. This will generate only the declarations/definitions of the
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type/attribute constaraints that are defined in the specified `.td` file, but
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not those that are in included `.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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mlir_tablegen(<Your Dialect>AttrConstraints.h.inc -gen-attr-constraint-decls)
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mlir_tablegen(<Your Dialect>AttrConstraints.cpp.inc -gen-attr-constraint-defs)
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```
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The generated `<Your Dialect>TypeConstraints.h.inc` respectivelly
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`<Your Dialect>AttrConstraints.h.inc` will need to be included whereever you are
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referencing the type/attributes constraint in C++. Note that no C++ namespace
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will be emitted by the code generator. The `#include` statements of the
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`.h.inc`/`.cpp.inc` files should be wrapped in C++ namespaces by the user.
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