utils/TableGen/SetTheory.cpp

   1 //===- SetTheory.cpp - Generate ordered sets from DAG expressions ---------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the SetTheory class that computes ordered sets of
  11 // Records from DAG expressions.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "SetTheory.h"
  16 #include "Error.h"
  17 #include "Record.h"
  18 #include "llvm/Support/Format.h"
  19
  20 using namespace llvm;
  21
  22 // Define the standard operators.
  23 namespace {
  24
  25 typedef SetTheory::RecSet RecSet;
  26 typedef SetTheory::RecVec RecVec;
  27
  28 // (add a, b, ...) Evaluate and union all arguments.
  29 struct AddOp : public SetTheory::Operator {
  30   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
  31     ST.evaluate(Expr->arg_begin(), Expr->arg_end(), Elts);
  32   }
  33 };
  34
  35 // (sub Add, Sub, ...) Set difference.
  36 struct SubOp : public SetTheory::Operator {
  37   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
  38     if (Expr->arg_size() < 2)
  39       throw "Set difference needs at least two arguments: " +
  40         Expr->getAsString();
  41     RecSet Add, Sub;
  42     ST.evaluate(*Expr->arg_begin(), Add);
  43     ST.evaluate(Expr->arg_begin() + 1, Expr->arg_end(), Sub);
  44     for (RecSet::iterator I = Add.begin(), E = Add.end(); I != E; ++I)
  45       if (!Sub.count(*I))
  46         Elts.insert(*I);
  47   }
  48 };
  49
  50 // (and S1, S2) Set intersection.
  51 struct AndOp : public SetTheory::Operator {
  52   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
  53     if (Expr->arg_size() != 2)
  54       throw "Set intersection requires two arguments: " + Expr->getAsString();
  55     RecSet S1, S2;
  56     ST.evaluate(Expr->arg_begin()[0], S1);
  57     ST.evaluate(Expr->arg_begin()[1], S2);
  58     for (RecSet::iterator I = S1.begin(), E = S1.end(); I != E; ++I)
  59       if (S2.count(*I))
  60         Elts.insert(*I);
  61   }
  62 };
  63
  64 // SetIntBinOp - Abstract base class for (Op S, N) operators.
  65 struct SetIntBinOp : public SetTheory::Operator {
  66   virtual void apply2(SetTheory &ST, DagInit *Expr,
  67                      RecSet &Set, int64_t N,
  68                      RecSet &Elts) =0;
  69
  70   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
  71     if (Expr->arg_size() != 2)
  72       throw "Operator requires (Op Set, Int) arguments: " + Expr->getAsString();
  73     RecSet Set;
  74     ST.evaluate(Expr->arg_begin()[0], Set);
  75     IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[1]);
  76     if (!II)
  77       throw "Second argument must be an integer: " + Expr->getAsString();
  78     apply2(ST, Expr, Set, II->getValue(), Elts);
  79   }
  80 };
  81
  82 // (shl S, N) Shift left, remove the first N elements.
  83 struct ShlOp : public SetIntBinOp {
  84   void apply2(SetTheory &ST, DagInit *Expr,
  85              RecSet &Set, int64_t N,
  86              RecSet &Elts) {
  87     if (N < 0)
  88       throw "Positive shift required: " + Expr->getAsString();
  89     if (unsigned(N) < Set.size())
  90       Elts.insert(Set.begin() + N, Set.end());
  91   }
  92 };
  93
  94 // (trunc S, N) Truncate after the first N elements.
  95 struct TruncOp : public SetIntBinOp {
  96   void apply2(SetTheory &ST, DagInit *Expr,
  97              RecSet &Set, int64_t N,
  98              RecSet &Elts) {
  99     if (N < 0)
 100       throw "Positive length required: " + Expr->getAsString();
 101     if (unsigned(N) > Set.size())
 102       N = Set.size();
 103     Elts.insert(Set.begin(), Set.begin() + N);
 104   }
 105 };
 106
 107 // Left/right rotation.
 108 struct RotOp : public SetIntBinOp {
 109   const bool Reverse;
 110
 111   RotOp(bool Rev) : Reverse(Rev) {}
 112
 113   void apply2(SetTheory &ST, DagInit *Expr,
 114              RecSet &Set, int64_t N,
 115              RecSet &Elts) {
 116     if (Reverse)
 117       N = -N;
 118     // N > 0 -> rotate left, N < 0 -> rotate right.
 119     if (Set.empty())
 120       return;
 121     if (N < 0)
 122       N = Set.size() - (-N % Set.size());
 123     else
 124       N %= Set.size();
 125     Elts.insert(Set.begin() + N, Set.end());
 126     Elts.insert(Set.begin(), Set.begin() + N);
 127   }
 128 };
 129
 130 // (decimate S, N) Pick every N'th element of S.
 131 struct DecimateOp : public SetIntBinOp {
 132   void apply2(SetTheory &ST, DagInit *Expr,
 133              RecSet &Set, int64_t N,
 134              RecSet &Elts) {
 135     if (N <= 0)
 136       throw "Positive stride required: " + Expr->getAsString();
 137     for (unsigned I = 0; I < Set.size(); I += N)
 138       Elts.insert(Set[I]);
 139   }
 140 };
 141
 142 // (sequence "Format", From, To) Generate a sequence of records by name.
 143 struct SequenceOp : public SetTheory::Operator {
 144   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
 145     if (Expr->arg_size() != 3)
 146       throw "Bad args to (sequence \"Format\", From, To): " +
 147         Expr->getAsString();
 148     std::string Format;
 149     if (StringInit *SI = dynamic_cast<StringInit*>(Expr->arg_begin()[0]))
 150       Format = SI->getValue();
 151     else
 152       throw "Format must be a string: " + Expr->getAsString();
 153
 154     int64_t From, To;
 155     if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[1]))
 156       From = II->getValue();
 157     else
 158       throw "From must be an integer: " + Expr->getAsString();
 159     if (From < 0 || From >= (1 << 30))
 160       throw "From out of range";
 161
 162     if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[2]))
 163       To = II->getValue();
 164     else
 165       throw "From must be an integer: " + Expr->getAsString();
 166     if (To < 0 || To >= (1 << 30))
 167       throw "To out of range";
 168
 169     RecordKeeper &Records =
 170       dynamic_cast<DefInit&>(*Expr->getOperator()).getDef()->getRecords();
 171
 172     int Step = From <= To ? 1 : -1;
 173     for (To += Step; From != To; From += Step) {
 174       std::string Name;
 175       raw_string_ostream OS(Name);
 176       OS << format(Format.c_str(), unsigned(From));
 177       Record *Rec = Records.getDef(OS.str());
 178       if (!Rec)
 179         throw "No def named '" + Name + "': " + Expr->getAsString();
 180       // Try to reevaluate Rec in case it is a set.
 181       if (const RecVec *Result = ST.expand(Rec))
 182         Elts.insert(Result->begin(), Result->end());
 183       else
 184         Elts.insert(Rec);
 185     }
 186   }
 187 };
 188
 189 // Expand a Def into a set by evaluating one of its fields.
 190 struct FieldExpander : public SetTheory::Expander {
 191   StringRef FieldName;
 192
 193   FieldExpander(StringRef fn) : FieldName(fn) {}
 194
 195   void expand(SetTheory &ST, Record *Def, RecSet &Elts) {
 196     ST.evaluate(Def->getValueInit(FieldName), Elts);
 197   }
 198 };
 199 } // end anonymous namespace
 200
 201 SetTheory::SetTheory() {
 202   addOperator("add", new AddOp);
 203   addOperator("sub", new SubOp);
 204   addOperator("and", new AndOp);
 205   addOperator("shl", new ShlOp);
 206   addOperator("trunc", new TruncOp);
 207   addOperator("rotl", new RotOp(false));
 208   addOperator("rotr", new RotOp(true));
 209   addOperator("decimate", new DecimateOp);
 210   addOperator("sequence", new SequenceOp);
 211 }
 212
 213 void SetTheory::addOperator(StringRef Name, Operator *Op) {
 214   Operators[Name] = Op;
 215 }
 216
 217 void SetTheory::addExpander(StringRef ClassName, Expander *E) {
 218   Expanders[ClassName] = E;
 219 }
 220
 221 void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
 222   addExpander(ClassName, new FieldExpander(FieldName));
 223 }
 224
 225 void SetTheory::evaluate(Init *Expr, RecSet &Elts) {
 226   // A def in a list can be a just an element, or it may expand.
 227   if (DefInit *Def = dynamic_cast<DefInit*>(Expr)) {
 228     if (const RecVec *Result = expand(Def->getDef()))
 229       return Elts.insert(Result->begin(), Result->end());
 230     Elts.insert(Def->getDef());
 231     return;
 232   }
 233
 234   // Lists simply expand.
 235   if (ListInit *LI = dynamic_cast<ListInit*>(Expr))
 236     return evaluate(LI->begin(), LI->end(), Elts);
 237
 238   // Anything else must be a DAG.
 239   DagInit *DagExpr = dynamic_cast<DagInit*>(Expr);
 240   if (!DagExpr)
 241     throw "Invalid set element: " + Expr->getAsString();
 242   DefInit *OpInit = dynamic_cast<DefInit*>(DagExpr->getOperator());
 243   if (!OpInit)
 244     throw "Bad set expression: " + Expr->getAsString();
 245   Operator *Op = Operators.lookup(OpInit->getDef()->getName());
 246   if (!Op)
 247     throw "Unknown set operator: " + Expr->getAsString();
 248   Op->apply(*this, DagExpr, Elts);
 249 }
 250
 251 const RecVec *SetTheory::expand(Record *Set) {
 252   // Check existing entries for Set and return early.
 253   ExpandMap::iterator I = Expansions.find(Set);
 254   if (I != Expansions.end())
 255     return &I->second;
 256
 257   // This is the first time we see Set. Find a suitable expander.
 258   try {
 259     const std::vector<Record*> &SC = Set->getSuperClasses();
 260     for (unsigned i = 0, e = SC.size(); i != e; ++i)
 261       if (Expander *Exp = Expanders.lookup(SC[i]->getName())) {
 262         // This breaks recursive definitions.
 263         RecVec &EltVec = Expansions[Set];
 264         RecSet Elts;
 265         Exp->expand(*this, Set, Elts);
 266         EltVec.assign(Elts.begin(), Elts.end());
 267         return &EltVec;
 268       }
 269   } catch (const std::string &Error) {
 270     throw TGError(Set->getLoc(), Error);
 271   }
 272
 273   // Set is not expandable.
 274   return 0;
 275 }
 276