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 "llvm/TableGen/Error.h"
17#include "llvm/TableGen/Record.h"
18#include "llvm/Support/Format.h"
19
20using namespace llvm;
21
22// Define the standard operators.
23namespace {
24
25typedef SetTheory::RecSet RecSet;
26typedef SetTheory::RecVec RecVec;
27
28// (add a, b, ...) Evaluate and union all arguments.
29struct 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.
36struct 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.
51struct 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.
65struct 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.
83struct 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.
95struct 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.
108struct 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.
131struct 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// (interleave S1, S2, ...) Interleave elements of the arguments.
143struct InterleaveOp : public SetTheory::Operator {
144  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
145    // Evaluate the arguments individually.
146    SmallVector<RecSet, 4> Args(Expr->getNumArgs());
147    unsigned MaxSize = 0;
148    for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i) {
149      ST.evaluate(Expr->getArg(i), Args[i]);
150      MaxSize = std::max(MaxSize, unsigned(Args[i].size()));
151    }
152    // Interleave arguments into Elts.
153    for (unsigned n = 0; n != MaxSize; ++n)
154      for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i)
155        if (n < Args[i].size())
156          Elts.insert(Args[i][n]);
157  }
158};
159
160// (sequence "Format", From, To) Generate a sequence of records by name.
161struct SequenceOp : public SetTheory::Operator {
162  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
163    int Step = 1;
164    if (Expr->arg_size() > 4)
165      throw "Bad args to (sequence \"Format\", From, To): " +
166        Expr->getAsString();
167    else if (Expr->arg_size() == 4) {
168      if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[3])) {
169        Step = II->getValue();
170      } else
171        throw "Stride must be an integer: " + Expr->getAsString();
172    }
173
174    std::string Format;
175    if (StringInit *SI = dynamic_cast<StringInit*>(Expr->arg_begin()[0]))
176      Format = SI->getValue();
177    else
178      throw "Format must be a string: " + Expr->getAsString();
179
180    int64_t From, To;
181    if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[1]))
182      From = II->getValue();
183    else
184      throw "From must be an integer: " + Expr->getAsString();
185    if (From < 0 || From >= (1 << 30))
186      throw "From out of range";
187
188    if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[2]))
189      To = II->getValue();
190    else
191      throw "From must be an integer: " + Expr->getAsString();
192    if (To < 0 || To >= (1 << 30))
193      throw "To out of range";
194
195    RecordKeeper &Records =
196      dynamic_cast<DefInit&>(*Expr->getOperator()).getDef()->getRecords();
197
198    Step *= From <= To ? 1 : -1;
199    while (true) {
200      if (Step > 0 && From > To)
201        break;
202      else if (Step < 0 && From < To)
203        break;
204      std::string Name;
205      raw_string_ostream OS(Name);
206      OS << format(Format.c_str(), unsigned(From));
207      Record *Rec = Records.getDef(OS.str());
208      if (!Rec)
209        throw "No def named '" + Name + "': " + Expr->getAsString();
210      // Try to reevaluate Rec in case it is a set.
211      if (const RecVec *Result = ST.expand(Rec))
212        Elts.insert(Result->begin(), Result->end());
213      else
214        Elts.insert(Rec);
215
216      From += Step;
217    }
218  }
219};
220
221// Expand a Def into a set by evaluating one of its fields.
222struct FieldExpander : public SetTheory::Expander {
223  StringRef FieldName;
224
225  FieldExpander(StringRef fn) : FieldName(fn) {}
226
227  void expand(SetTheory &ST, Record *Def, RecSet &Elts) {
228    ST.evaluate(Def->getValueInit(FieldName), Elts);
229  }
230};
231} // end anonymous namespace
232
233void SetTheory::Operator::anchor() { }
234
235void SetTheory::Expander::anchor() { }
236
237SetTheory::SetTheory() {
238  addOperator("add", new AddOp);
239  addOperator("sub", new SubOp);
240  addOperator("and", new AndOp);
241  addOperator("shl", new ShlOp);
242  addOperator("trunc", new TruncOp);
243  addOperator("rotl", new RotOp(false));
244  addOperator("rotr", new RotOp(true));
245  addOperator("decimate", new DecimateOp);
246  addOperator("interleave", new InterleaveOp);
247  addOperator("sequence", new SequenceOp);
248}
249
250void SetTheory::addOperator(StringRef Name, Operator *Op) {
251  Operators[Name] = Op;
252}
253
254void SetTheory::addExpander(StringRef ClassName, Expander *E) {
255  Expanders[ClassName] = E;
256}
257
258void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
259  addExpander(ClassName, new FieldExpander(FieldName));
260}
261
262void SetTheory::evaluate(Init *Expr, RecSet &Elts) {
263  // A def in a list can be a just an element, or it may expand.
264  if (DefInit *Def = dynamic_cast<DefInit*>(Expr)) {
265    if (const RecVec *Result = expand(Def->getDef()))
266      return Elts.insert(Result->begin(), Result->end());
267    Elts.insert(Def->getDef());
268    return;
269  }
270
271  // Lists simply expand.
272  if (ListInit *LI = dynamic_cast<ListInit*>(Expr))
273    return evaluate(LI->begin(), LI->end(), Elts);
274
275  // Anything else must be a DAG.
276  DagInit *DagExpr = dynamic_cast<DagInit*>(Expr);
277  if (!DagExpr)
278    throw "Invalid set element: " + Expr->getAsString();
279  DefInit *OpInit = dynamic_cast<DefInit*>(DagExpr->getOperator());
280  if (!OpInit)
281    throw "Bad set expression: " + Expr->getAsString();
282  Operator *Op = Operators.lookup(OpInit->getDef()->getName());
283  if (!Op)
284    throw "Unknown set operator: " + Expr->getAsString();
285  Op->apply(*this, DagExpr, Elts);
286}
287
288const RecVec *SetTheory::expand(Record *Set) {
289  // Check existing entries for Set and return early.
290  ExpandMap::iterator I = Expansions.find(Set);
291  if (I != Expansions.end())
292    return &I->second;
293
294  // This is the first time we see Set. Find a suitable expander.
295  try {
296    const std::vector<Record*> &SC = Set->getSuperClasses();
297    for (unsigned i = 0, e = SC.size(); i != e; ++i) {
298      // Skip unnamed superclasses.
299      if (!dynamic_cast<const StringInit *>(SC[i]->getNameInit()))
300        continue;
301      if (Expander *Exp = Expanders.lookup(SC[i]->getName())) {
302        // This breaks recursive definitions.
303        RecVec &EltVec = Expansions[Set];
304        RecSet Elts;
305        Exp->expand(*this, Set, Elts);
306        EltVec.assign(Elts.begin(), Elts.end());
307        return &EltVec;
308      }
309    }
310  } catch (const std::string &Error) {
311    throw TGError(Set->getLoc(), Error);
312  }
313
314  // Set is not expandable.
315  return 0;
316}
317
318