SetTheory.cpp revision f37dd02f7743ebd2424480361f5a7db510495c4f 
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
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, const 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, const 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, const 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, const DagInit *Expr,
67                     RecSet &Set, int64_t N,
68                     RecSet &Elts) =0;
69
70  void apply(SetTheory &ST, const 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    const IntInit *II = dynamic_cast<const 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, const 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, const 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, const 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, const 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.
143struct SequenceOp : public SetTheory::Operator {
144  void apply(SetTheory &ST, const 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 (const StringInit *SI = dynamic_cast<const 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 (const IntInit *II = dynamic_cast<const 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 (const IntInit *II = dynamic_cast<const 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<const 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.
190struct 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
201SetTheory::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
213void SetTheory::addOperator(StringRef Name, Operator *Op) {
214  Operators[Name] = Op;
215}
216
217void SetTheory::addExpander(StringRef ClassName, Expander *E) {
218  Expanders[ClassName] = E;
219}
220
221void SetTheory::addFieldExpander(StringRef ClassName, StringRef FieldName) {
222  addExpander(ClassName, new FieldExpander(FieldName));
223}
224
225void SetTheory::evaluate(const Init *Expr, RecSet &Elts) {
226  // A def in a list can be a just an element, or it may expand.
227  if (const DefInit *Def = dynamic_cast<const 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 (const ListInit *LI = dynamic_cast<const ListInit*>(Expr))
236    return evaluate(LI->begin(), LI->end(), Elts);
237
238  // Anything else must be a DAG.
239  const DagInit *DagExpr = dynamic_cast<const DagInit*>(Expr);
240  if (!DagExpr)
241    throw "Invalid set element: " + Expr->getAsString();
242  const DefInit *OpInit = dynamic_cast<const 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
251const 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
277