1 //===- SetTheory.cpp - Generate ordered sets from DAG expressions ---------===//
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 file implements the SetTheory class that computes ordered sets of
10 // Records from DAG expressions.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/TableGen/SetTheory.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Support/Casting.h"
19 #include "llvm/Support/Format.h"
20 #include "llvm/Support/SMLoc.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/TableGen/Error.h"
23 #include "llvm/TableGen/Record.h"
24 #include <algorithm>
25 #include <cstdint>
26 #include <string>
27 #include <utility>
28 
29 using namespace llvm;
30 
31 // Define the standard operators.
32 namespace {
33 
34 using RecSet = SetTheory::RecSet;
35 using RecVec = SetTheory::RecVec;
36 
37 // (add a, b, ...) Evaluate and union all arguments.
38 struct AddOp : public SetTheory::Operator {
39   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
40              ArrayRef<SMLoc> Loc) override {
41     ST.evaluate(Expr->arg_begin(), Expr->arg_end(), Elts, Loc);
42   }
43 };
44 
45 // (sub Add, Sub, ...) Set difference.
46 struct SubOp : public SetTheory::Operator {
47   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
48              ArrayRef<SMLoc> Loc) override {
49     if (Expr->arg_size() < 2)
50       PrintFatalError(Loc, "Set difference needs at least two arguments: " +
51         Expr->getAsString());
52     RecSet Add, Sub;
53     ST.evaluate(*Expr->arg_begin(), Add, Loc);
54     ST.evaluate(Expr->arg_begin() + 1, Expr->arg_end(), Sub, Loc);
55     for (const auto &I : Add)
56       if (!Sub.count(I))
57         Elts.insert(I);
58   }
59 };
60 
61 // (and S1, S2) Set intersection.
62 struct AndOp : public SetTheory::Operator {
63   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
64              ArrayRef<SMLoc> Loc) override {
65     if (Expr->arg_size() != 2)
66       PrintFatalError(Loc, "Set intersection requires two arguments: " +
67         Expr->getAsString());
68     RecSet S1, S2;
69     ST.evaluate(Expr->arg_begin()[0], S1, Loc);
70     ST.evaluate(Expr->arg_begin()[1], S2, Loc);
71     for (const auto &I : S1)
72       if (S2.count(I))
73         Elts.insert(I);
74   }
75 };
76 
77 // SetIntBinOp - Abstract base class for (Op S, N) operators.
78 struct SetIntBinOp : public SetTheory::Operator {
79   virtual void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
80                       RecSet &Elts, ArrayRef<SMLoc> Loc) = 0;
81 
82   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
83              ArrayRef<SMLoc> Loc) override {
84     if (Expr->arg_size() != 2)
85       PrintFatalError(Loc, "Operator requires (Op Set, Int) arguments: " +
86         Expr->getAsString());
87     RecSet Set;
88     ST.evaluate(Expr->arg_begin()[0], Set, Loc);
89     IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[1]);
90     if (!II)
91       PrintFatalError(Loc, "Second argument must be an integer: " +
92         Expr->getAsString());
93     apply2(ST, Expr, Set, II->getValue(), Elts, Loc);
94   }
95 };
96 
97 // (shl S, N) Shift left, remove the first N elements.
98 struct ShlOp : public SetIntBinOp {
99   void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
100               RecSet &Elts, ArrayRef<SMLoc> Loc) override {
101     if (N < 0)
102       PrintFatalError(Loc, "Positive shift required: " +
103         Expr->getAsString());
104     if (unsigned(N) < Set.size())
105       Elts.insert(Set.begin() + N, Set.end());
106   }
107 };
108 
109 // (trunc S, N) Truncate after the first N elements.
110 struct TruncOp : public SetIntBinOp {
111   void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
112               RecSet &Elts, ArrayRef<SMLoc> Loc) override {
113     if (N < 0)
114       PrintFatalError(Loc, "Positive length required: " +
115         Expr->getAsString());
116     if (unsigned(N) > Set.size())
117       N = Set.size();
118     Elts.insert(Set.begin(), Set.begin() + N);
119   }
120 };
121 
122 // Left/right rotation.
123 struct RotOp : public SetIntBinOp {
124   const bool Reverse;
125 
126   RotOp(bool Rev) : Reverse(Rev) {}
127 
128   void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
129               RecSet &Elts, ArrayRef<SMLoc> Loc) override {
130     if (Reverse)
131       N = -N;
132     // N > 0 -> rotate left, N < 0 -> rotate right.
133     if (Set.empty())
134       return;
135     if (N < 0)
136       N = Set.size() - (-N % Set.size());
137     else
138       N %= Set.size();
139     Elts.insert(Set.begin() + N, Set.end());
140     Elts.insert(Set.begin(), Set.begin() + N);
141   }
142 };
143 
144 // (decimate S, N) Pick every N'th element of S.
145 struct DecimateOp : public SetIntBinOp {
146   void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
147               RecSet &Elts, ArrayRef<SMLoc> Loc) override {
148     if (N <= 0)
149       PrintFatalError(Loc, "Positive stride required: " +
150         Expr->getAsString());
151     for (unsigned I = 0; I < Set.size(); I += N)
152       Elts.insert(Set[I]);
153   }
154 };
155 
156 // (interleave S1, S2, ...) Interleave elements of the arguments.
157 struct InterleaveOp : public SetTheory::Operator {
158   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
159              ArrayRef<SMLoc> Loc) override {
160     // Evaluate the arguments individually.
161     SmallVector<RecSet, 4> Args(Expr->getNumArgs());
162     unsigned MaxSize = 0;
163     for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i) {
164       ST.evaluate(Expr->getArg(i), Args[i], Loc);
165       MaxSize = std::max(MaxSize, unsigned(Args[i].size()));
166     }
167     // Interleave arguments into Elts.
168     for (unsigned n = 0; n != MaxSize; ++n)
169       for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i)
170         if (n < Args[i].size())
171           Elts.insert(Args[i][n]);
172   }
173 };
174 
175 // (sequence "Format", From, To) Generate a sequence of records by name.
176 struct SequenceOp : public SetTheory::Operator {
177   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
178              ArrayRef<SMLoc> Loc) override {
179     int Step = 1;
180     if (Expr->arg_size() > 4)
181       PrintFatalError(Loc, "Bad args to (sequence \"Format\", From, To): " +
182         Expr->getAsString());
183     else if (Expr->arg_size() == 4) {
184       if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[3])) {
185         Step = II->getValue();
186       } else
187         PrintFatalError(Loc, "Stride must be an integer: " +
188           Expr->getAsString());
189     }
190 
191     std::string Format;
192     if (StringInit *SI = dyn_cast<StringInit>(Expr->arg_begin()[0]))
193       Format = std::string(SI->getValue());
194     else
195       PrintFatalError(Loc,  "Format must be a string: " + Expr->getAsString());
196 
197     int64_t From, To;
198     if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[1]))
199       From = II->getValue();
200     else
201       PrintFatalError(Loc, "From must be an integer: " + Expr->getAsString());
202     if (From < 0 || From >= (1 << 30))
203       PrintFatalError(Loc, "From out of range");
204 
205     if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[2]))
206       To = II->getValue();
207     else
208       PrintFatalError(Loc, "To must be an integer: " + Expr->getAsString());
209     if (To < 0 || To >= (1 << 30))
210       PrintFatalError(Loc, "To out of range");
211 
212     RecordKeeper &Records =
213       cast<DefInit>(Expr->getOperator())->getDef()->getRecords();
214 
215     Step *= From <= To ? 1 : -1;
216     while (true) {
217       if (Step > 0 && From > To)
218         break;
219       else if (Step < 0 && From < To)
220         break;
221       std::string Name;
222       raw_string_ostream OS(Name);
223       OS << format(Format.c_str(), unsigned(From));
224       Record *Rec = Records.getDef(OS.str());
225       if (!Rec)
226         PrintFatalError(Loc, "No def named '" + Name + "': " +
227           Expr->getAsString());
228       // Try to reevaluate Rec in case it is a set.
229       if (const RecVec *Result = ST.expand(Rec))
230         Elts.insert(Result->begin(), Result->end());
231       else
232         Elts.insert(Rec);
233 
234       From += Step;
235     }
236   }
237 };
238 
239 // Expand a Def into a set by evaluating one of its fields.
240 struct FieldExpander : public SetTheory::Expander {
241   StringRef FieldName;
242 
243   FieldExpander(StringRef fn) : FieldName(fn) {}
244 
245   void expand(SetTheory &ST, Record *Def, RecSet &Elts) override {
246     ST.evaluate(Def->getValueInit(FieldName), Elts, Def->getLoc());
247   }
248 };
249 
250 } // end anonymous namespace
251 
252 // Pin the vtables to this file.
253 void SetTheory::Operator::anchor() {}
254 void SetTheory::Expander::anchor() {}
255 
256 SetTheory::SetTheory() {
257   addOperator("add", std::make_unique<AddOp>());
258   addOperator("sub", std::make_unique<SubOp>());
259   addOperator("and", std::make_unique<AndOp>());
260   addOperator("shl", std::make_unique<ShlOp>());
261   addOperator("trunc", std::make_unique<TruncOp>());
262   addOperator("rotl", std::make_unique<RotOp>(false));
263   addOperator("rotr", std::make_unique<RotOp>(true));
264   addOperator("decimate", std::make_unique<DecimateOp>());
265   addOperator("interleave", std::make_unique<InterleaveOp>());
266   addOperator("sequence", std::make_unique<SequenceOp>());
267 }
268 
269 void SetTheory::addOperator(StringRef Name, std::unique_ptr<Operator> Op) {
270   Operators[Name] = std::move(Op);
271 }
272 
273 void SetTheory::addExpander(StringRef ClassName, std::unique_ptr<Expander> E) {
274   Expanders[ClassName] = std::move(E);
275 }
276 
277 void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
278   addExpander(ClassName, std::make_unique<FieldExpander>(FieldName));
279 }
280 
281 void SetTheory::evaluate(Init *Expr, RecSet &Elts, ArrayRef<SMLoc> Loc) {
282   // A def in a list can be a just an element, or it may expand.
283   if (DefInit *Def = dyn_cast<DefInit>(Expr)) {
284     if (const RecVec *Result = expand(Def->getDef()))
285       return Elts.insert(Result->begin(), Result->end());
286     Elts.insert(Def->getDef());
287     return;
288   }
289 
290   // Lists simply expand.
291   if (ListInit *LI = dyn_cast<ListInit>(Expr))
292     return evaluate(LI->begin(), LI->end(), Elts, Loc);
293 
294   // Anything else must be a DAG.
295   DagInit *DagExpr = dyn_cast<DagInit>(Expr);
296   if (!DagExpr)
297     PrintFatalError(Loc, "Invalid set element: " + Expr->getAsString());
298   DefInit *OpInit = dyn_cast<DefInit>(DagExpr->getOperator());
299   if (!OpInit)
300     PrintFatalError(Loc, "Bad set expression: " + Expr->getAsString());
301   auto I = Operators.find(OpInit->getDef()->getName());
302   if (I == Operators.end())
303     PrintFatalError(Loc, "Unknown set operator: " + Expr->getAsString());
304   I->second->apply(*this, DagExpr, Elts, Loc);
305 }
306 
307 const RecVec *SetTheory::expand(Record *Set) {
308   // Check existing entries for Set and return early.
309   ExpandMap::iterator I = Expansions.find(Set);
310   if (I != Expansions.end())
311     return &I->second;
312 
313   // This is the first time we see Set. Find a suitable expander.
314   ArrayRef<std::pair<Record *, SMRange>> SC = Set->getSuperClasses();
315   for (const auto &SCPair : SC) {
316     // Skip unnamed superclasses.
317     if (!isa<StringInit>(SCPair.first->getNameInit()))
318       continue;
319     auto I = Expanders.find(SCPair.first->getName());
320     if (I != Expanders.end()) {
321       // This breaks recursive definitions.
322       RecVec &EltVec = Expansions[Set];
323       RecSet Elts;
324       I->second->expand(*this, Set, Elts);
325       EltVec.assign(Elts.begin(), Elts.end());
326       return &EltVec;
327     }
328   }
329 
330   // Set is not expandable.
331   return nullptr;
332 }
333