lib/TableGen/SetTheory.cpp

   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
  30 using namespace llvm;
  31
  32 // Define the standard operators.
  33 namespace {
  34
  35 using RecSet = SetTheory::RecSet;
  36 using RecVec = SetTheory::RecVec;
  37
  38 // (add a, b, ...) Evaluate and union all arguments.
  39 struct 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.
  47 struct 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.
  63 struct 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.
  79 struct 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.
  99 struct 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.
 111 struct 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.
 124 struct 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.
 146 struct 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.
 158 struct 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.
 177 struct 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.
 241 struct 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.
 254 void SetTheory::Operator::anchor() {}
 255 void SetTheory::Expander::anchor() {}
 256
 257 SetTheory::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
 270 void SetTheory::addOperator(StringRef Name, std::unique_ptr<Operator> Op) {
 271   Operators[Name] = std::move(Op);
 272 }
 273
 274 void SetTheory::addExpander(StringRef ClassName, std::unique_ptr<Expander> E) {
 275   Expanders[ClassName] = std::move(E);
 276 }
 277
 278 void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
 279   addExpander(ClassName, std::make_unique<FieldExpander>(FieldName));
 280 }
 281
 282 void 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
 308 const 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 }