SetTheory.cpp revision 2559011a0176f7829effdad0a26395f14d723930 
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 "Record.h"
17#include "llvm/Support/Format.h"
18
19using namespace llvm;
20
21// Define the standard operators.
22namespace {
23
24typedef SetTheory::RecSet RecSet;
25typedef SetTheory::RecVec RecVec;
26
27// (add a, b, ...) Evaluate and union all arguments.
28struct AddOp : public SetTheory::Operator {
29  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
30    ST.evaluate(Expr->arg_begin(), Expr->arg_end(), Elts);
31  }
32};
33
34// (sub Add, Sub, ...) Set difference.
35struct SubOp : public SetTheory::Operator {
36  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
37    if (Expr->arg_size() < 2)
38      throw "Set difference needs at least two arguments: " +
39        Expr->getAsString();
40    RecSet Add, Sub;
41    ST.evaluate(*Expr->arg_begin(), Add);
42    ST.evaluate(Expr->arg_begin() + 1, Expr->arg_end(), Sub);
43    for (RecSet::iterator I = Add.begin(), E = Add.end(); I != E; ++I)
44      if (!Sub.count(*I))
45        Elts.insert(*I);
46  }
47};
48
49// (and S1, S2) Set intersection.
50struct AndOp : public SetTheory::Operator {
51  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
52    if (Expr->arg_size() != 2)
53      throw "Set intersection requires two arguments: " + Expr->getAsString();
54    RecSet S1, S2;
55    ST.evaluate(Expr->arg_begin()[0], S1);
56    ST.evaluate(Expr->arg_begin()[1], S2);
57    for (RecSet::iterator I = S1.begin(), E = S1.end(); I != E; ++I)
58      if (S2.count(*I))
59        Elts.insert(*I);
60  }
61};
62
63// SetIntBinOp - Abstract base class for (Op S, N) operators.
64struct SetIntBinOp : public SetTheory::Operator {
65  virtual void apply2(SetTheory &ST, DagInit *Expr,
66                     RecSet &Set, int64_t N,
67                     RecSet &Elts) =0;
68
69  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
70    if (Expr->arg_size() != 2)
71      throw "Operator requires (Op Set, Int) arguments: " + Expr->getAsString();
72    RecSet Set;
73    ST.evaluate(Expr->arg_begin()[0], Set);
74    IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[1]);
75    if (!II)
76      throw "Second argument must be an integer: " + Expr->getAsString();
77    apply2(ST, Expr, Set, II->getValue(), Elts);
78  }
79};
80
81// (shl S, N) Shift left, remove the first N elements.
82struct ShlOp : public SetIntBinOp {
83  void apply2(SetTheory &ST, DagInit *Expr,
84             RecSet &Set, int64_t N,
85             RecSet &Elts) {
86    if (N < 0)
87      throw "Positive shift required: " + Expr->getAsString();
88    if (unsigned(N) < Set.size())
89      Elts.insert(Set.begin() + N, Set.end());
90  }
91};
92
93// (trunc S, N) Truncate after the first N elements.
94struct TruncOp : public SetIntBinOp {
95  void apply2(SetTheory &ST, DagInit *Expr,
96             RecSet &Set, int64_t N,
97             RecSet &Elts) {
98    if (N < 0)
99      throw "Positive length required: " + Expr->getAsString();
100    if (unsigned(N) > Set.size())
101      N = Set.size();
102    Elts.insert(Set.begin(), Set.begin() + N);
103  }
104};
105
106// Left/right rotation.
107struct RotOp : public SetIntBinOp {
108  const bool Reverse;
109
110  RotOp(bool Rev) : Reverse(Rev) {}
111
112  void apply2(SetTheory &ST, DagInit *Expr,
113             RecSet &Set, int64_t N,
114             RecSet &Elts) {
115    if (Reverse)
116      N = -N;
117    // N > 0 -> rotate left, N < 0 -> rotate right.
118    if (Set.empty())
119      return;
120    if (N < 0)
121      N = Set.size() - (-N % Set.size());
122    else
123      N %= Set.size();
124    Elts.insert(Set.begin() + N, Set.end());
125    Elts.insert(Set.begin(), Set.begin() + N);
126  }
127};
128
129// (decimate S, N) Pick every N'th element of S.
130struct DecimateOp : public SetIntBinOp {
131  void apply2(SetTheory &ST, DagInit *Expr,
132             RecSet &Set, int64_t N,
133             RecSet &Elts) {
134    if (N <= 0)
135      throw "Positive stride required: " + Expr->getAsString();
136    for (unsigned I = 0; I < Set.size(); I += N)
137      Elts.insert(Set[I]);
138  }
139};
140
141// (sequence "Format", From, To) Generate a sequence of records by name.
142struct SequenceOp : public SetTheory::Operator {
143  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
144    if (Expr->arg_size() != 3)
145      throw "Bad args to (sequence \"Format\", From, To): " +
146        Expr->getAsString();
147    std::string Format;
148    if (StringInit *SI = dynamic_cast<StringInit*>(Expr->arg_begin()[0]))
149      Format = SI->getValue();
150    else
151      throw "Format must be a string: " + Expr->getAsString();
152
153    int64_t From, To;
154    if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[1]))
155      From = II->getValue();
156    else
157      throw "From must be an integer: " + Expr->getAsString();
158    if (From < 0 || From >= (1 << 30))
159      throw "From out of range";
160
161    if (IntInit *II = dynamic_cast<IntInit*>(Expr->arg_begin()[2]))
162      To = II->getValue();
163    else
164      throw "From must be an integer: " + Expr->getAsString();
165    if (To < 0 || To >= (1 << 30))
166      throw "To out of range";
167
168    RecordKeeper &Records =
169      dynamic_cast<DefInit&>(*Expr->getOperator()).getDef()->getRecords();
170
171    int Step = From <= To ? 1 : -1;
172    for (To += Step; From != To; From += Step) {
173      std::string Name;
174      raw_string_ostream OS(Name);
175      OS << format(Format.c_str(), unsigned(From));
176      Record *Rec = Records.getDef(OS.str());
177      if (!Rec)
178        throw "No def named '" + Name + "': " + Expr->getAsString();
179      // Try to reevaluate Rec in case it is a set.
180      if (const RecVec *Result = ST.expand(Rec))
181        Elts.insert(Result->begin(), Result->end());
182      else
183        Elts.insert(Rec);
184    }
185  }
186};
187
188// Expand a Def into a set by evaluating one of its fields.
189struct FieldExpander : public SetTheory::Expander {
190  StringRef FieldName;
191
192  FieldExpander(StringRef fn) : FieldName(fn) {}
193
194  void expand(SetTheory &ST, Record *Def, RecSet &Elts) {
195    ST.evaluate(Def->getValueInit(FieldName), Elts);
196  }
197};
198} // end anonymous namespace
199
200SetTheory::SetTheory() {
201  addOperator("add", new AddOp);
202  addOperator("sub", new SubOp);
203  addOperator("and", new AndOp);
204  addOperator("shl", new ShlOp);
205  addOperator("trunc", new TruncOp);
206  addOperator("rotl", new RotOp(false));
207  addOperator("rotr", new RotOp(true));
208  addOperator("decimate", new DecimateOp);
209  addOperator("sequence", new SequenceOp);
210}
211
212void SetTheory::addOperator(StringRef Name, Operator *Op) {
213  Operators[Name] = Op;
214}
215
216void SetTheory::addExpander(StringRef ClassName, Expander *E) {
217  Expanders[ClassName] = E;
218}
219
220void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
221  addExpander(ClassName, new FieldExpander(FieldName));
222}
223
224void SetTheory::evaluate(Init *Expr, RecSet &Elts) {
225  // A def in a list can be a just an element, or it may expand.
226  if (DefInit *Def = dynamic_cast<DefInit*>(Expr)) {
227    if (const RecVec *Result = expand(Def->getDef()))
228      return Elts.insert(Result->begin(), Result->end());
229    Elts.insert(Def->getDef());
230    return;
231  }
232
233  // Lists simply expand.
234  if (ListInit *LI = dynamic_cast<ListInit*>(Expr))
235    return evaluate(LI->begin(), LI->end(), Elts);
236
237  // Anything else must be a DAG.
238  DagInit *DagExpr = dynamic_cast<DagInit*>(Expr);
239  if (!DagExpr)
240    throw "Invalid set element: " + Expr->getAsString();
241  DefInit *OpInit = dynamic_cast<DefInit*>(DagExpr->getOperator());
242  if (!OpInit)
243    throw "Bad set expression: " + Expr->getAsString();
244  Operator *Op = Operators.lookup(OpInit->getDef()->getName());
245  if (!Op)
246    throw "Unknown set operator: " + Expr->getAsString();
247  Op->apply(*this, DagExpr, Elts);
248}
249
250const RecVec *SetTheory::expand(Record *Set) {
251  // Check existing entries for Set and return early.
252  ExpandMap::iterator I = Expansions.find(Set);
253  if (I != Expansions.end())
254    return &I->second;
255
256  // This is the first time we see Set. Find a suitable expander.
257  try {
258    const std::vector<Record*> &SC = Set->getSuperClasses();
259    for (unsigned i = 0, e = SC.size(); i != e; ++i)
260      if (Expander *Exp = Expanders.lookup(SC[i]->getName())) {
261        // This breaks recursive definitions.
262        RecVec &EltVec = Expansions[Set];
263        RecSet Elts;
264        Exp->expand(*this, Set, Elts);
265        EltVec.assign(Elts.begin(), Elts.end());
266        return &EltVec;
267      }
268  } catch (const std::string &Error) {
269    throw TGError(Set->getLoc(), Error);
270  }
271
272  // Set is not expandable.
273  return 0;
274}
275
276