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