SetTheory.cpp revision 360784 
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/ADT/ArrayRef.h"
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/ADT/STLExtras.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 "llvm/TableGen/SetTheory.h"
25#include <algorithm>
26#include <cstdint>
27#include <string>
28#include <utility>
29
30using namespace llvm;
31
32// Define the standard operators.
33namespace {
34
35using RecSet = SetTheory::RecSet;
36using RecVec = SetTheory::RecVec;
37
38// (add a, b, ...) Evaluate and union all arguments.
39struct AddOp : public SetTheory::Operator {
40  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
41             ArrayRef<SMLoc> Loc) override {
42    ST.evaluate(Expr->arg_begin(), Expr->arg_end(), Elts, Loc);
43  }
44};
45
46// (sub Add, Sub, ...) Set difference.
47struct SubOp : public SetTheory::Operator {
48  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
49             ArrayRef<SMLoc> Loc) override {
50    if (Expr->arg_size() < 2)
51      PrintFatalError(Loc, "Set difference needs at least two arguments: " +
52        Expr->getAsString());
53    RecSet Add, Sub;
54    ST.evaluate(*Expr->arg_begin(), Add, Loc);
55    ST.evaluate(Expr->arg_begin() + 1, Expr->arg_end(), Sub, Loc);
56    for (RecSet::iterator I = Add.begin(), E = Add.end(); I != E; ++I)
57      if (!Sub.count(*I))
58        Elts.insert(*I);
59  }
60};
61
62// (and S1, S2) Set intersection.
63struct AndOp : public SetTheory::Operator {
64  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
65             ArrayRef<SMLoc> Loc) override {
66    if (Expr->arg_size() != 2)
67      PrintFatalError(Loc, "Set intersection requires two arguments: " +
68        Expr->getAsString());
69    RecSet S1, S2;
70    ST.evaluate(Expr->arg_begin()[0], S1, Loc);
71    ST.evaluate(Expr->arg_begin()[1], S2, Loc);
72    for (RecSet::iterator I = S1.begin(), E = S1.end(); I != E; ++I)
73      if (S2.count(*I))
74        Elts.insert(*I);
75  }
76};
77
78// SetIntBinOp - Abstract base class for (Op S, N) operators.
79struct SetIntBinOp : public SetTheory::Operator {
80  virtual void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
81                      RecSet &Elts, ArrayRef<SMLoc> Loc) = 0;
82
83  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
84             ArrayRef<SMLoc> Loc) override {
85    if (Expr->arg_size() != 2)
86      PrintFatalError(Loc, "Operator requires (Op Set, Int) arguments: " +
87        Expr->getAsString());
88    RecSet Set;
89    ST.evaluate(Expr->arg_begin()[0], Set, Loc);
90    IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[1]);
91    if (!II)
92      PrintFatalError(Loc, "Second argument must be an integer: " +
93        Expr->getAsString());
94    apply2(ST, Expr, Set, II->getValue(), Elts, Loc);
95  }
96};
97
98// (shl S, N) Shift left, remove the first N elements.
99struct ShlOp : public SetIntBinOp {
100  void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
101              RecSet &Elts, ArrayRef<SMLoc> Loc) override {
102    if (N < 0)
103      PrintFatalError(Loc, "Positive shift required: " +
104        Expr->getAsString());
105    if (unsigned(N) < Set.size())
106      Elts.insert(Set.begin() + N, Set.end());
107  }
108};
109
110// (trunc S, N) Truncate after the first N elements.
111struct TruncOp : public SetIntBinOp {
112  void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
113              RecSet &Elts, ArrayRef<SMLoc> Loc) override {
114    if (N < 0)
115      PrintFatalError(Loc, "Positive length required: " +
116        Expr->getAsString());
117    if (unsigned(N) > Set.size())
118      N = Set.size();
119    Elts.insert(Set.begin(), Set.begin() + N);
120  }
121};
122
123// Left/right rotation.
124struct RotOp : public SetIntBinOp {
125  const bool Reverse;
126
127  RotOp(bool Rev) : Reverse(Rev) {}
128
129  void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
130              RecSet &Elts, ArrayRef<SMLoc> Loc) override {
131    if (Reverse)
132      N = -N;
133    // N > 0 -> rotate left, N < 0 -> rotate right.
134    if (Set.empty())
135      return;
136    if (N < 0)
137      N = Set.size() - (-N % Set.size());
138    else
139      N %= Set.size();
140    Elts.insert(Set.begin() + N, Set.end());
141    Elts.insert(Set.begin(), Set.begin() + N);
142  }
143};
144
145// (decimate S, N) Pick every N'th element of S.
146struct DecimateOp : public SetIntBinOp {
147  void apply2(SetTheory &ST, DagInit *Expr, RecSet &Set, int64_t N,
148              RecSet &Elts, ArrayRef<SMLoc> Loc) override {
149    if (N <= 0)
150      PrintFatalError(Loc, "Positive stride required: " +
151        Expr->getAsString());
152    for (unsigned I = 0; I < Set.size(); I += N)
153      Elts.insert(Set[I]);
154  }
155};
156
157// (interleave S1, S2, ...) Interleave elements of the arguments.
158struct InterleaveOp : public SetTheory::Operator {
159  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
160             ArrayRef<SMLoc> Loc) override {
161    // Evaluate the arguments individually.
162    SmallVector<RecSet, 4> Args(Expr->getNumArgs());
163    unsigned MaxSize = 0;
164    for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i) {
165      ST.evaluate(Expr->getArg(i), Args[i], Loc);
166      MaxSize = std::max(MaxSize, unsigned(Args[i].size()));
167    }
168    // Interleave arguments into Elts.
169    for (unsigned n = 0; n != MaxSize; ++n)
170      for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i)
171        if (n < Args[i].size())
172          Elts.insert(Args[i][n]);
173  }
174};
175
176// (sequence "Format", From, To) Generate a sequence of records by name.
177struct SequenceOp : public SetTheory::Operator {
178  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts,
179             ArrayRef<SMLoc> Loc) override {
180    int Step = 1;
181    if (Expr->arg_size() > 4)
182      PrintFatalError(Loc, "Bad args to (sequence \"Format\", From, To): " +
183        Expr->getAsString());
184    else if (Expr->arg_size() == 4) {
185      if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[3])) {
186        Step = II->getValue();
187      } else
188        PrintFatalError(Loc, "Stride must be an integer: " +
189          Expr->getAsString());
190    }
191
192    std::string Format;
193    if (StringInit *SI = dyn_cast<StringInit>(Expr->arg_begin()[0]))
194      Format = SI->getValue();
195    else
196      PrintFatalError(Loc,  "Format must be a string: " + Expr->getAsString());
197
198    int64_t From, To;
199    if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[1]))
200      From = II->getValue();
201    else
202      PrintFatalError(Loc, "From must be an integer: " + Expr->getAsString());
203    if (From < 0 || From >= (1 << 30))
204      PrintFatalError(Loc, "From out of range");
205
206    if (IntInit *II = dyn_cast<IntInit>(Expr->arg_begin()[2]))
207      To = II->getValue();
208    else
209      PrintFatalError(Loc, "To must be an integer: " + Expr->getAsString());
210    if (To < 0 || To >= (1 << 30))
211      PrintFatalError(Loc, "To out of range");
212
213    RecordKeeper &Records =
214      cast<DefInit>(Expr->getOperator())->getDef()->getRecords();
215
216    Step *= From <= To ? 1 : -1;
217    while (true) {
218      if (Step > 0 && From > To)
219        break;
220      else if (Step < 0 && From < To)
221        break;
222      std::string Name;
223      raw_string_ostream OS(Name);
224      OS << format(Format.c_str(), unsigned(From));
225      Record *Rec = Records.getDef(OS.str());
226      if (!Rec)
227        PrintFatalError(Loc, "No def named '" + Name + "': " +
228          Expr->getAsString());
229      // Try to reevaluate Rec in case it is a set.
230      if (const RecVec *Result = ST.expand(Rec))
231        Elts.insert(Result->begin(), Result->end());
232      else
233        Elts.insert(Rec);
234
235      From += Step;
236    }
237  }
238};
239
240// Expand a Def into a set by evaluating one of its fields.
241struct FieldExpander : public SetTheory::Expander {
242  StringRef FieldName;
243
244  FieldExpander(StringRef fn) : FieldName(fn) {}
245
246  void expand(SetTheory &ST, Record *Def, RecSet &Elts) override {
247    ST.evaluate(Def->getValueInit(FieldName), Elts, Def->getLoc());
248  }
249};
250
251} // end anonymous namespace
252
253// Pin the vtables to this file.
254void SetTheory::Operator::anchor() {}
255void SetTheory::Expander::anchor() {}
256
257SetTheory::SetTheory() {
258  addOperator("add", std::make_unique<AddOp>());
259  addOperator("sub", std::make_unique<SubOp>());
260  addOperator("and", std::make_unique<AndOp>());
261  addOperator("shl", std::make_unique<ShlOp>());
262  addOperator("trunc", std::make_unique<TruncOp>());
263  addOperator("rotl", std::make_unique<RotOp>(false));
264  addOperator("rotr", std::make_unique<RotOp>(true));
265  addOperator("decimate", std::make_unique<DecimateOp>());
266  addOperator("interleave", std::make_unique<InterleaveOp>());
267  addOperator("sequence", std::make_unique<SequenceOp>());
268}
269
270void SetTheory::addOperator(StringRef Name, std::unique_ptr<Operator> Op) {
271  Operators[Name] = std::move(Op);
272}
273
274void SetTheory::addExpander(StringRef ClassName, std::unique_ptr<Expander> E) {
275  Expanders[ClassName] = std::move(E);
276}
277
278void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
279  addExpander(ClassName, std::make_unique<FieldExpander>(FieldName));
280}
281
282void SetTheory::evaluate(Init *Expr, RecSet &Elts, ArrayRef<SMLoc> Loc) {
283  // A def in a list can be a just an element, or it may expand.
284  if (DefInit *Def = dyn_cast<DefInit>(Expr)) {
285    if (const RecVec *Result = expand(Def->getDef()))
286      return Elts.insert(Result->begin(), Result->end());
287    Elts.insert(Def->getDef());
288    return;
289  }
290
291  // Lists simply expand.
292  if (ListInit *LI = dyn_cast<ListInit>(Expr))
293    return evaluate(LI->begin(), LI->end(), Elts, Loc);
294
295  // Anything else must be a DAG.
296  DagInit *DagExpr = dyn_cast<DagInit>(Expr);
297  if (!DagExpr)
298    PrintFatalError(Loc, "Invalid set element: " + Expr->getAsString());
299  DefInit *OpInit = dyn_cast<DefInit>(DagExpr->getOperator());
300  if (!OpInit)
301    PrintFatalError(Loc, "Bad set expression: " + Expr->getAsString());
302  auto I = Operators.find(OpInit->getDef()->getName());
303  if (I == Operators.end())
304    PrintFatalError(Loc, "Unknown set operator: " + Expr->getAsString());
305  I->second->apply(*this, DagExpr, Elts, Loc);
306}
307
308const RecVec *SetTheory::expand(Record *Set) {
309  // Check existing entries for Set and return early.
310  ExpandMap::iterator I = Expansions.find(Set);
311  if (I != Expansions.end())
312    return &I->second;
313
314  // This is the first time we see Set. Find a suitable expander.
315  ArrayRef<std::pair<Record *, SMRange>> SC = Set->getSuperClasses();
316  for (const auto &SCPair : SC) {
317    // Skip unnamed superclasses.
318    if (!isa<StringInit>(SCPair.first->getNameInit()))
319      continue;
320    auto I = Expanders.find(SCPair.first->getName());
321    if (I != Expanders.end()) {
322      // This breaks recursive definitions.
323      RecVec &EltVec = Expansions[Set];
324      RecSet Elts;
325      I->second->expand(*this, Set, Elts);
326      EltVec.assign(Elts.begin(), Elts.end());
327      return &EltVec;
328    }
329  }
330
331  // Set is not expandable.
332  return nullptr;
333}
334