| 1 | //===- TableGenBackends.h - Declarations for LLVM TableGen Backends -------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // This file contains the declarations for all of the LLVM TableGen |
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| 10 | // backends. A "TableGen backend" is just a function. See below for a |
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| 11 | // precise description. |
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| 12 | // |
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| 13 | //===----------------------------------------------------------------------===// |
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| 14 | |
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| 15 | #ifndef LLVM_UTILS_TABLEGEN_TABLEGENBACKENDS_H |
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| 16 | #define LLVM_UTILS_TABLEGEN_TABLEGENBACKENDS_H |
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| 17 | |
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| 18 | #include <string> |
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| 19 | |
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| 20 | // A TableGen backend is a function that looks like |
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| 21 | // |
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| 22 | // EmitFoo(RecordKeeper &RK, raw_ostream &OS /*, anything else you need */ ) |
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| 23 | // |
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| 24 | // What you do inside of that function is up to you, but it will usually |
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| 25 | // involve generating C++ code to the provided raw_ostream. |
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| 26 | // |
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| 27 | // The RecordKeeper is just a top-level container for an in-memory |
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| 28 | // representation of the data encoded in the TableGen file. What a TableGen |
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| 29 | // backend does is walk around that in-memory representation and generate |
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| 30 | // stuff based on the information it contains. |
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| 31 | // |
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| 32 | // The in-memory representation is a node-graph (think of it like JSON but |
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| 33 | // with a richer ontology of types), where the nodes are subclasses of |
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| 34 | // Record. The methods `getClass`, `getDef` are the basic interface to |
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| 35 | // access the node-graph. RecordKeeper also provides a handy method |
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| 36 | // `getAllDerivedDefinitions`. Consult "include/llvm/TableGen/Record.h" for |
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| 37 | // the exact interfaces provided by Record's and RecordKeeper. |
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| 38 | // |
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| 39 | // A common pattern for TableGen backends is for the EmitFoo function to |
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| 40 | // instantiate a class which holds some context for the generation process, |
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| 41 | // and then have most of the work happen in that class's methods. This |
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| 42 | // pattern partly has historical roots in the previous TableGen backend API |
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| 43 | // that involved a class and an invocation like `FooEmitter(RK).run(OS)`. |
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| 44 | // |
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| 45 | // Remember to wrap private things in an anonymous namespace. For most |
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| 46 | // backends, this means that the EmitFoo function is the only thing not in |
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| 47 | // the anonymous namespace. |
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| 48 | |
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| 49 | // FIXME: Reorganize TableGen so that build dependencies can be more |
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| 50 | // accurately expressed. Currently, touching any of the emitters (or |
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| 51 | // anything that they transitively depend on) causes everything dependent |
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| 52 | // on TableGen to be rebuilt (this includes all the targets!). Perhaps have |
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| 53 | // a standalone TableGen binary and have the backends be loadable modules |
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| 54 | // of some sort; then the dependency could be expressed as being on the |
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| 55 | // module, and all the modules would have a common dependency on the |
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| 56 | // TableGen binary with as few dependencies as possible on the rest of |
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| 57 | // LLVM. |
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| 58 | |
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| 59 | namespace llvm { |
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| 60 | |
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| 61 | class raw_ostream; |
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| 62 | class RecordKeeper; |
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| 63 | |
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| 64 | void EmitMapTable(RecordKeeper &RK, raw_ostream &OS); |
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| 65 | |
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| 66 | // Defined in DecoderEmitter.cpp |
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| 67 | void EmitDecoder(RecordKeeper &RK, raw_ostream &OS, |
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| 68 | const std::string &PredicateNamespace); |
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| 69 | |
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| 70 | } // namespace llvm |
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| 71 | |
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| 72 | #endif |
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| 73 | |
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