| //===- TableGenBackends.h - Declarations for LLVM TableGen Backends -------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the declarations for all of the LLVM TableGen |
| // backends. A "TableGen backend" is just a function. See below for a |
| // precise description. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_UTILS_TABLEGEN_TABLEGENBACKENDS_H |
| #define LLVM_UTILS_TABLEGEN_TABLEGENBACKENDS_H |
| |
| #include <string> |
| |
| // A TableGen backend is a function that looks like |
| // |
| // EmitFoo(RecordKeeper &RK, raw_ostream &OS /*, anything else you need */ ) |
| // |
| // What you do inside of that function is up to you, but it will usually |
| // involve generating C++ code to the provided raw_ostream. |
| // |
| // The RecordKeeper is just a top-level container for an in-memory |
| // representation of the data encoded in the TableGen file. What a TableGen |
| // backend does is walk around that in-memory representation and generate |
| // stuff based on the information it contains. |
| // |
| // The in-memory representation is a node-graph (think of it like JSON but |
| // with a richer ontology of types), where the nodes are subclasses of |
| // Record. The methods `getClass`, `getDef` are the basic interface to |
| // access the node-graph. RecordKeeper also provides a handy method |
| // `getAllDerivedDefinitions`. Consult "include/llvm/TableGen/Record.h" for |
| // the exact interfaces provided by Record's and RecordKeeper. |
| // |
| // A common pattern for TableGen backends is for the EmitFoo function to |
| // instantiate a class which holds some context for the generation process, |
| // and then have most of the work happen in that class's methods. This |
| // pattern partly has historical roots in the previous TableGen backend API |
| // that involved a class and an invocation like `FooEmitter(RK).run(OS)`. |
| // |
| // Remember to wrap private things in an anonymous namespace. For most |
| // backends, this means that the EmitFoo function is the only thing not in |
| // the anonymous namespace. |
| |
| // FIXME: Reorganize TableGen so that build dependencies can be more |
| // accurately expressed. Currently, touching any of the emitters (or |
| // anything that they transitively depend on) causes everything dependent |
| // on TableGen to be rebuilt (this includes all the targets!). Perhaps have |
| // a standalone TableGen binary and have the backends be loadable modules |
| // of some sort; then the dependency could be expressed as being on the |
| // module, and all the modules would have a common dependency on the |
| // TableGen binary with as few dependencies as possible on the rest of |
| // LLVM. |
| |
| namespace llvm { |
| |
| class raw_ostream; |
| class RecordKeeper; |
| |
| void EmitMapTable(const RecordKeeper &RK, raw_ostream &OS); |
| |
| // Defined in DecoderEmitter.cpp |
| void EmitDecoder(const RecordKeeper &RK, raw_ostream &OS, |
| StringRef PredicateNamespace); |
| |
| } // namespace llvm |
| |
| #endif |