llvm/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/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 }