1 //===- JSONBackend.cpp - Generate a JSON dump of all records. -*- C++ -*-=====//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This TableGen back end generates a machine-readable representation
10 // of all the classes and records defined by the input, in JSON format.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ADT/BitVector.h"
15 #include "llvm/Support/Debug.h"
16 #include "llvm/TableGen/Error.h"
17 #include "llvm/TableGen/Record.h"
18 #include "llvm/TableGen/TableGenBackend.h"
19 #include "llvm/Support/JSON.h"
20 
21 #define DEBUG_TYPE "json-emitter"
22 
23 using namespace llvm;
24 
25 namespace {
26 
27 class JSONEmitter {
28 private:
29   RecordKeeper &Records;
30 
31   json::Value translateInit(const Init &I);
32   json::Array listSuperclasses(const Record &R);
33 
34 public:
35   JSONEmitter(RecordKeeper &R);
36 
37   void run(raw_ostream &OS);
38 };
39 
40 } // end anonymous namespace
41 
JSONEmitter(RecordKeeper & R)42 JSONEmitter::JSONEmitter(RecordKeeper &R) : Records(R) {}
43 
translateInit(const Init & I)44 json::Value JSONEmitter::translateInit(const Init &I) {
45 
46   // Init subclasses that we return as JSON primitive values of one
47   // kind or another.
48 
49   if (isa<UnsetInit>(&I)) {
50     return nullptr;
51   } else if (auto *Bit = dyn_cast<BitInit>(&I)) {
52     return Bit->getValue() ? 1 : 0;
53   } else if (auto *Bits = dyn_cast<BitsInit>(&I)) {
54     json::Array array;
55     for (unsigned i = 0, limit = Bits->getNumBits(); i < limit; i++)
56       array.push_back(translateInit(*Bits->getBit(i)));
57     return std::move(array);
58   } else if (auto *Int = dyn_cast<IntInit>(&I)) {
59     return Int->getValue();
60   } else if (auto *Str = dyn_cast<StringInit>(&I)) {
61     return Str->getValue();
62   } else if (auto *Code = dyn_cast<CodeInit>(&I)) {
63     return Code->getValue();
64   } else if (auto *List = dyn_cast<ListInit>(&I)) {
65     json::Array array;
66     for (auto val : *List)
67       array.push_back(translateInit(*val));
68     return std::move(array);
69   }
70 
71   // Init subclasses that we return as JSON objects containing a
72   // 'kind' discriminator. For these, we also provide the same
73   // translation back into TableGen input syntax that -print-records
74   // would give.
75 
76   json::Object obj;
77   obj["printable"] = I.getAsString();
78 
79   if (auto *Def = dyn_cast<DefInit>(&I)) {
80     obj["kind"] = "def";
81     obj["def"] = Def->getDef()->getName();
82     return std::move(obj);
83   } else if (auto *Var = dyn_cast<VarInit>(&I)) {
84     obj["kind"] = "var";
85     obj["var"] = Var->getName();
86     return std::move(obj);
87   } else if (auto *VarBit = dyn_cast<VarBitInit>(&I)) {
88     if (auto *Var = dyn_cast<VarInit>(VarBit->getBitVar())) {
89       obj["kind"] = "varbit";
90       obj["var"] = Var->getName();
91       obj["index"] = VarBit->getBitNum();
92       return std::move(obj);
93     }
94   } else if (auto *Dag = dyn_cast<DagInit>(&I)) {
95     obj["kind"] = "dag";
96     obj["operator"] = translateInit(*Dag->getOperator());
97     if (auto name = Dag->getName())
98       obj["name"] = name->getAsUnquotedString();
99     json::Array args;
100     for (unsigned i = 0, limit = Dag->getNumArgs(); i < limit; ++i) {
101       json::Array arg;
102       arg.push_back(translateInit(*Dag->getArg(i)));
103       if (auto argname = Dag->getArgName(i))
104         arg.push_back(argname->getAsUnquotedString());
105       else
106         arg.push_back(nullptr);
107       args.push_back(std::move(arg));
108     }
109     obj["args"] = std::move(args);
110     return std::move(obj);
111   }
112 
113   // Final fallback: anything that gets past here is simply given a
114   // kind field of 'complex', and the only other field is the standard
115   // 'printable' representation.
116 
117   assert(!I.isConcrete());
118   obj["kind"] = "complex";
119   return std::move(obj);
120 }
121 
run(raw_ostream & OS)122 void JSONEmitter::run(raw_ostream &OS) {
123   json::Object root;
124 
125   root["!tablegen_json_version"] = 1;
126 
127   // Prepare the arrays that will list the instances of every class.
128   // We mostly fill those in by iterating over the superclasses of
129   // each def, but we also want to ensure we store an empty list for a
130   // class with no instances at all, so we do a preliminary iteration
131   // over the classes, invoking std::map::operator[] to default-
132   // construct the array for each one.
133   std::map<std::string, json::Array> instance_lists;
134   for (const auto &C : Records.getClasses()) {
135     auto &Name = C.second->getNameInitAsString();
136     (void)instance_lists[Name];
137   }
138 
139   // Main iteration over the defs.
140   for (const auto &D : Records.getDefs()) {
141     auto &Name = D.second->getNameInitAsString();
142     auto &Def = *D.second;
143 
144     json::Object obj;
145     json::Array fields;
146 
147     for (const RecordVal &RV : Def.getValues()) {
148       if (!Def.isTemplateArg(RV.getNameInit())) {
149         auto Name = RV.getNameInitAsString();
150         if (RV.getPrefix())
151           fields.push_back(Name);
152         obj[Name] = translateInit(*RV.getValue());
153       }
154     }
155 
156     obj["!fields"] = std::move(fields);
157 
158     json::Array superclasses;
159     for (const auto &SuperPair : Def.getSuperClasses())
160       superclasses.push_back(SuperPair.first->getNameInitAsString());
161     obj["!superclasses"] = std::move(superclasses);
162 
163     obj["!name"] = Name;
164     obj["!anonymous"] = Def.isAnonymous();
165 
166     root[Name] = std::move(obj);
167 
168     // Add this def to the instance list for each of its superclasses.
169     for (const auto &SuperPair : Def.getSuperClasses()) {
170       auto SuperName = SuperPair.first->getNameInitAsString();
171       instance_lists[SuperName].push_back(Name);
172     }
173   }
174 
175   // Make a JSON object from the std::map of instance lists.
176   json::Object instanceof;
177   for (auto kv: instance_lists)
178     instanceof[kv.first] = std::move(kv.second);
179   root["!instanceof"] = std::move(instanceof);
180 
181   // Done. Write the output.
182   OS << json::Value(std::move(root)) << "\n";
183 }
184 
185 namespace llvm {
186 
EmitJSON(RecordKeeper & RK,raw_ostream & OS)187 void EmitJSON(RecordKeeper &RK, raw_ostream &OS) { JSONEmitter(RK).run(OS); }
188 } // end namespace llvm
189