Coverage Report

Created: 2018-07-19 03:59

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/CodeGen/RegAllocPBQP.h
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//===- RegAllocPBQP.h -------------------------------------------*- C++ -*-===//
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 defines the PBQPBuilder interface, for classes which build PBQP
11
// instances to represent register allocation problems, and the RegAllocPBQP
12
// interface.
13
//
14
//===----------------------------------------------------------------------===//
15
16
#ifndef LLVM_CODEGEN_REGALLOCPBQP_H
17
#define LLVM_CODEGEN_REGALLOCPBQP_H
18
19
#include "llvm/ADT/DenseMap.h"
20
#include "llvm/ADT/Hashing.h"
21
#include "llvm/CodeGen/PBQP/CostAllocator.h"
22
#include "llvm/CodeGen/PBQP/Graph.h"
23
#include "llvm/CodeGen/PBQP/Math.h"
24
#include "llvm/CodeGen/PBQP/ReductionRules.h"
25
#include "llvm/CodeGen/PBQP/Solution.h"
26
#include "llvm/Support/ErrorHandling.h"
27
#include <algorithm>
28
#include <cassert>
29
#include <cstddef>
30
#include <limits>
31
#include <memory>
32
#include <set>
33
#include <vector>
34
35
namespace llvm {
36
37
class FunctionPass;
38
class LiveIntervals;
39
class MachineBlockFrequencyInfo;
40
class MachineFunction;
41
class raw_ostream;
42
43
namespace PBQP {
44
namespace RegAlloc {
45
46
/// Spill option index.
47
306
inline unsigned getSpillOptionIdx() { return 0; }
48
49
/// Metadata to speed allocatability test.
50
///
51
/// Keeps track of the number of infinities in each row and column.
52
class MatrixMetadata {
53
public:
54
  MatrixMetadata(const Matrix& M)
55
    : UnsafeRows(new bool[M.getRows() - 1]()),
56
70
      UnsafeCols(new bool[M.getCols() - 1]()) {
57
70
    unsigned* ColCounts = new unsigned[M.getCols() - 1]();
58
70
59
2.09k
    for (unsigned i = 1; i < M.getRows(); 
++i2.02k
) {
60
2.02k
      unsigned RowCount = 0;
61
61.9k
      for (unsigned j = 1; j < M.getCols(); 
++j59.9k
) {
62
59.9k
        if (M[i][j] == std::numeric_limits<PBQPNum>::infinity()) {
63
1.83k
          ++RowCount;
64
1.83k
          ++ColCounts[j - 1];
65
1.83k
          UnsafeRows[i - 1] = true;
66
1.83k
          UnsafeCols[j - 1] = true;
67
1.83k
        }
68
59.9k
      }
69
2.02k
      WorstRow = std::max(WorstRow, RowCount);
70
2.02k
    }
71
70
    unsigned WorstColCountForCurRow =
72
70
      *std::max_element(ColCounts, ColCounts + M.getCols() - 1);
73
70
    WorstCol = std::max(WorstCol, WorstColCountForCurRow);
74
70
    delete[] ColCounts;
75
70
  }
76
77
  MatrixMetadata(const MatrixMetadata &) = delete;
78
  MatrixMetadata &operator=(const MatrixMetadata &) = delete;
79
80
798
  unsigned getWorstRow() const { return WorstRow; }
81
1.02k
  unsigned getWorstCol() const { return WorstCol; }
82
1.02k
  const bool* getUnsafeRows() const { return UnsafeRows.get(); }
83
798
  const bool* getUnsafeCols() const { return UnsafeCols.get(); }
84
85
private:
86
  unsigned WorstRow = 0;
87
  unsigned WorstCol = 0;
88
  std::unique_ptr<bool[]> UnsafeRows;
89
  std::unique_ptr<bool[]> UnsafeCols;
90
};
91
92
/// Holds a vector of the allowed physical regs for a vreg.
93
class AllowedRegVector {
94
  friend hash_code hash_value(const AllowedRegVector &);
95
96
public:
97
  AllowedRegVector() = default;
98
201
  AllowedRegVector(AllowedRegVector &&) = default;
99
100
  AllowedRegVector(const std::vector<unsigned> &OptVec)
101
153
    : NumOpts(OptVec.size()), Opts(new unsigned[NumOpts]) {
102
153
    std::copy(OptVec.begin(), OptVec.end(), Opts.get());
103
153
  }
104
105
48.2k
  unsigned size() const { return NumOpts; }
106
127k
  unsigned operator[](size_t I) const { return Opts[I]; }
107
108
153
  bool operator==(const AllowedRegVector &Other) const {
109
153
    if (NumOpts != Other.NumOpts)
110
0
      return false;
111
153
    return std::equal(Opts.get(), Opts.get() + NumOpts, Other.Opts.get());
112
153
  }
113
114
  bool operator!=(const AllowedRegVector &Other) const {
115
    return !(*this == Other);
116
  }
117
118
private:
119
  unsigned NumOpts = 0;
120
  std::unique_ptr<unsigned[]> Opts;
121
};
122
123
193
inline hash_code hash_value(const AllowedRegVector &OptRegs) {
124
193
  unsigned *OStart = OptRegs.Opts.get();
125
193
  unsigned *OEnd = OptRegs.Opts.get() + OptRegs.NumOpts;
126
193
  return hash_combine(OptRegs.NumOpts,
127
193
                      hash_combine_range(OStart, OEnd));
128
193
}
129
130
/// Holds graph-level metadata relevant to PBQP RA problems.
131
class GraphMetadata {
132
private:
133
  using AllowedRegVecPool = ValuePool<AllowedRegVector>;
134
135
public:
136
  using AllowedRegVecRef = AllowedRegVecPool::PoolRef;
137
138
  GraphMetadata(MachineFunction &MF,
139
                LiveIntervals &LIS,
140
                MachineBlockFrequencyInfo &MBFI)
141
8
    : MF(MF), LIS(LIS), MBFI(MBFI) {}
142
143
  MachineFunction &MF;
144
  LiveIntervals &LIS;
145
  MachineBlockFrequencyInfo &MBFI;
146
147
153
  void setNodeIdForVReg(unsigned VReg, GraphBase::NodeId NId) {
148
153
    VRegToNodeId[VReg] = NId;
149
153
  }
150
151
138
  GraphBase::NodeId getNodeIdForVReg(unsigned VReg) const {
152
138
    auto VRegItr = VRegToNodeId.find(VReg);
153
138
    if (VRegItr == VRegToNodeId.end())
154
0
      return GraphBase::invalidNodeId();
155
138
    return VRegItr->second;
156
138
  }
157
158
153
  AllowedRegVecRef getAllowedRegs(AllowedRegVector Allowed) {
159
153
    return AllowedRegVecs.getValue(std::move(Allowed));
160
153
  }
161
162
private:
163
  DenseMap<unsigned, GraphBase::NodeId> VRegToNodeId;
164
  AllowedRegVecPool AllowedRegVecs;
165
};
166
167
/// Holds solver state and other metadata relevant to each PBQP RA node.
168
class NodeMetadata {
169
public:
170
  using AllowedRegVector = RegAlloc::AllowedRegVector;
171
172
  // The node's reduction state. The order in this enum is important,
173
  // as it is assumed nodes can only progress up (i.e. towards being
174
  // optimally reducible) when reducing the graph.
175
  using ReductionState = enum {
176
    Unprocessed,
177
    NotProvablyAllocatable,
178
    ConservativelyAllocatable,
179
    OptimallyReducible
180
  };
181
182
153
  NodeMetadata() = default;
183
184
  NodeMetadata(const NodeMetadata &Other)
185
    : RS(Other.RS), NumOpts(Other.NumOpts), DeniedOpts(Other.DeniedOpts),
186
      OptUnsafeEdges(new unsigned[NumOpts]), VReg(Other.VReg),
187
      AllowedRegs(Other.AllowedRegs)
188
#ifndef NDEBUG
189
      , everConservativelyAllocatable(Other.everConservativelyAllocatable)
190
#endif
191
  {
192
    if (NumOpts > 0) {
193
      std::copy(&Other.OptUnsafeEdges[0], &Other.OptUnsafeEdges[NumOpts],
194
                &OptUnsafeEdges[0]);
195
    }
196
  }
197
198
373
  NodeMetadata(NodeMetadata &&) = default;
199
0
  NodeMetadata& operator=(NodeMetadata &&) = default;
200
201
153
  void setVReg(unsigned VReg) { this->VReg = VReg; }
202
459
  unsigned getVReg() const { return VReg; }
203
204
153
  void setAllowedRegs(GraphMetadata::AllowedRegVecRef AllowedRegs) {
205
153
    this->AllowedRegs = std::move(AllowedRegs);
206
153
  }
207
3.53k
  const AllowedRegVector& getAllowedRegs() const { return *AllowedRegs; }
208
209
153
  void setup(const Vector& Costs) {
210
153
    NumOpts = Costs.getLength() - 1;
211
153
    OptUnsafeEdges = std::unique_ptr<unsigned[]>(new unsigned[NumOpts]());
212
153
  }
213
214
796
  ReductionState getReductionState() const { return RS; }
215
240
  void setReductionState(ReductionState RS) {
216
240
    assert(RS >= this->RS && "A node's reduction state can not be downgraded");
217
240
    this->RS = RS;
218
240
219
240
#ifndef NDEBUG
220
240
    // Remember this state to assert later that a non-infinite register
221
240
    // option was available.
222
240
    if (RS == ConservativelyAllocatable)
223
240
      everConservativelyAllocatable = true;
224
240
#endif
225
240
  }
226
227
1.19k
  void handleAddEdge(const MatrixMetadata& MD, bool Transpose) {
228
1.19k
    DeniedOpts += Transpose ? 
MD.getWorstRow()596
:
MD.getWorstCol()596
;
229
1.19k
    const bool* UnsafeOpts =
230
1.19k
      Transpose ? 
MD.getUnsafeCols()596
:
MD.getUnsafeRows()596
;
231
31.0k
    for (unsigned i = 0; i < NumOpts; 
++i29.8k
)
232
29.8k
      OptUnsafeEdges[i] += UnsafeOpts[i];
233
1.19k
  }
234
235
631
  void handleRemoveEdge(const MatrixMetadata& MD, bool Transpose) {
236
631
    DeniedOpts -= Transpose ? 
MD.getWorstRow()202
:
MD.getWorstCol()429
;
237
631
    const bool* UnsafeOpts =
238
631
      Transpose ? 
MD.getUnsafeCols()202
:
MD.getUnsafeRows()429
;
239
16.5k
    for (unsigned i = 0; i < NumOpts; 
++i15.8k
)
240
15.8k
      OptUnsafeEdges[i] -= UnsafeOpts[i];
241
631
  }
242
243
261
  bool isConservativelyAllocatable() const {
244
261
    return (DeniedOpts < NumOpts) ||
245
261
      (std::find(&OptUnsafeEdges[0], &OptUnsafeEdges[NumOpts], 0) !=
246
138
       &OptUnsafeEdges[NumOpts]);
247
261
  }
248
249
#ifndef NDEBUG
250
  bool wasConservativelyAllocatable() const {
251
    return everConservativelyAllocatable;
252
  }
253
#endif
254
255
private:
256
  ReductionState RS = Unprocessed;
257
  unsigned NumOpts = 0;
258
  unsigned DeniedOpts = 0;
259
  std::unique_ptr<unsigned[]> OptUnsafeEdges;
260
  unsigned VReg = 0;
261
  GraphMetadata::AllowedRegVecRef AllowedRegs;
262
263
#ifndef NDEBUG
264
  bool everConservativelyAllocatable = false;
265
#endif
266
};
267
268
class RegAllocSolverImpl {
269
private:
270
  using RAMatrix = MDMatrix<MatrixMetadata>;
271
272
public:
273
  using RawVector = PBQP::Vector;
274
  using RawMatrix = PBQP::Matrix;
275
  using Vector = PBQP::Vector;
276
  using Matrix = RAMatrix;
277
  using CostAllocator = PBQP::PoolCostAllocator<Vector, Matrix>;
278
279
  using NodeId = GraphBase::NodeId;
280
  using EdgeId = GraphBase::EdgeId;
281
282
  using NodeMetadata = RegAlloc::NodeMetadata;
283
0
  struct EdgeMetadata {};
284
  using GraphMetadata = RegAlloc::GraphMetadata;
285
286
  using Graph = PBQP::Graph<RegAllocSolverImpl>;
287
288
8
  RegAllocSolverImpl(Graph &G) : G(G) {}
289
290
8
  Solution solve() {
291
8
    G.setSolver(*this);
292
8
    Solution S;
293
8
    setup();
294
8
    S = backpropagate(G, reduce());
295
8
    G.unsetSolver();
296
8
    return S;
297
8
  }
298
299
153
  void handleAddNode(NodeId NId) {
300
153
    assert(G.getNodeCosts(NId).getLength() > 1 &&
301
153
           "PBQP Graph should not contain single or zero-option nodes");
302
153
    G.getNodeMetadata(NId).setup(G.getNodeCosts(NId));
303
153
  }
304
305
  void handleRemoveNode(NodeId NId) {}
306
17
  void handleSetNodeCosts(NodeId NId, const Vector& newCosts) {}
307
308
561
  void handleAddEdge(EdgeId EId) {
309
561
    handleReconnectEdge(EId, G.getEdgeNode1Id(EId));
310
561
    handleReconnectEdge(EId, G.getEdgeNode2Id(EId));
311
561
  }
312
313
561
  void handleDisconnectEdge(EdgeId EId, NodeId NId) {
314
561
    NodeMetadata& NMd = G.getNodeMetadata(NId);
315
561
    const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
316
561
    NMd.handleRemoveEdge(MMd, NId == G.getEdgeNode2Id(EId));
317
561
    promote(NId, NMd);
318
561
  }
319
320
1.12k
  void handleReconnectEdge(EdgeId EId, NodeId NId) {
321
1.12k
    NodeMetadata& NMd = G.getNodeMetadata(NId);
322
1.12k
    const MatrixMetadata& MMd = G.getEdgeCosts(EId).getMetadata();
323
1.12k
    NMd.handleAddEdge(MMd, NId == G.getEdgeNode2Id(EId));
324
1.12k
  }
325
326
35
  void handleUpdateCosts(EdgeId EId, const Matrix& NewCosts) {
327
35
    NodeId N1Id = G.getEdgeNode1Id(EId);
328
35
    NodeId N2Id = G.getEdgeNode2Id(EId);
329
35
    NodeMetadata& N1Md = G.getNodeMetadata(N1Id);
330
35
    NodeMetadata& N2Md = G.getNodeMetadata(N2Id);
331
35
    bool Transpose = N1Id != G.getEdgeNode1Id(EId);
332
35
333
35
    // Metadata are computed incrementally. First, update them
334
35
    // by removing the old cost.
335
35
    const MatrixMetadata& OldMMd = G.getEdgeCosts(EId).getMetadata();
336
35
    N1Md.handleRemoveEdge(OldMMd, Transpose);
337
35
    N2Md.handleRemoveEdge(OldMMd, !Transpose);
338
35
339
35
    // And update now the metadata with the new cost.
340
35
    const MatrixMetadata& MMd = NewCosts.getMetadata();
341
35
    N1Md.handleAddEdge(MMd, Transpose);
342
35
    N2Md.handleAddEdge(MMd, !Transpose);
343
35
344
35
    // As the metadata may have changed with the update, the nodes may have
345
35
    // become ConservativelyAllocatable or OptimallyReducible.
346
35
    promote(N1Id, N1Md);
347
35
    promote(N2Id, N2Md);
348
35
  }
349
350
private:
351
631
  void promote(NodeId NId, NodeMetadata& NMd) {
352
631
    if (G.getNodeDegree(NId) == 3) {
353
75
      // This node is becoming optimally reducible.
354
75
      moveToOptimallyReducibleNodes(NId);
355
556
    } else if (NMd.getReductionState() ==
356
556
               NodeMetadata::NotProvablyAllocatable &&
357
556
               
NMd.isConservativelyAllocatable()127
) {
358
12
      // This node just became conservatively allocatable.
359
12
      moveToConservativelyAllocatableNodes(NId);
360
12
    }
361
631
  }
362
363
240
  void removeFromCurrentSet(NodeId NId) {
364
240
    switch (G.getNodeMetadata(NId).getReductionState()) {
365
240
    
case NodeMetadata::Unprocessed: break153
;
366
240
    case NodeMetadata::OptimallyReducible:
367
19
      assert(OptimallyReducibleNodes.find(NId) !=
368
19
             OptimallyReducibleNodes.end() &&
369
19
             "Node not in optimally reducible set.");
370
19
      OptimallyReducibleNodes.erase(NId);
371
19
      break;
372
240
    case NodeMetadata::ConservativelyAllocatable:
373
56
      assert(ConservativelyAllocatableNodes.find(NId) !=
374
56
             ConservativelyAllocatableNodes.end() &&
375
56
             "Node not in conservatively allocatable set.");
376
56
      ConservativelyAllocatableNodes.erase(NId);
377
56
      break;
378
240
    case NodeMetadata::NotProvablyAllocatable:
379
12
      assert(NotProvablyAllocatableNodes.find(NId) !=
380
12
             NotProvablyAllocatableNodes.end() &&
381
12
             "Node not in not-provably-allocatable set.");
382
12
      NotProvablyAllocatableNodes.erase(NId);
383
12
      break;
384
240
    }
385
240
  }
386
387
94
  void moveToOptimallyReducibleNodes(NodeId NId) {
388
94
    removeFromCurrentSet(NId);
389
94
    OptimallyReducibleNodes.insert(NId);
390
94
    G.getNodeMetadata(NId).setReductionState(
391
94
      NodeMetadata::OptimallyReducible);
392
94
  }
393
394
124
  void moveToConservativelyAllocatableNodes(NodeId NId) {
395
124
    removeFromCurrentSet(NId);
396
124
    ConservativelyAllocatableNodes.insert(NId);
397
124
    G.getNodeMetadata(NId).setReductionState(
398
124
      NodeMetadata::ConservativelyAllocatable);
399
124
  }
400
401
22
  void moveToNotProvablyAllocatableNodes(NodeId NId) {
402
22
    removeFromCurrentSet(NId);
403
22
    NotProvablyAllocatableNodes.insert(NId);
404
22
    G.getNodeMetadata(NId).setReductionState(
405
22
      NodeMetadata::NotProvablyAllocatable);
406
22
  }
407
408
8
  void setup() {
409
8
    // Set up worklists.
410
153
    for (auto NId : G.nodeIds()) {
411
153
      if (G.getNodeDegree(NId) < 3)
412
19
        moveToOptimallyReducibleNodes(NId);
413
134
      else if (G.getNodeMetadata(NId).isConservativelyAllocatable())
414
112
        moveToConservativelyAllocatableNodes(NId);
415
22
      else
416
22
        moveToNotProvablyAllocatableNodes(NId);
417
153
    }
418
8
  }
419
420
  // Compute a reduction order for the graph by iteratively applying PBQP
421
  // reduction rules. Locally optimal rules are applied whenever possible (R0,
422
  // R1, R2). If no locally-optimal rules apply then any conservatively
423
  // allocatable node is reduced. Finally, if no conservatively allocatable
424
  // node exists then the node with the lowest spill-cost:degree ratio is
425
  // selected.
426
8
  std::vector<GraphBase::NodeId> reduce() {
427
8
    assert(!G.empty() && "Cannot reduce empty graph.");
428
8
429
8
    using NodeId = GraphBase::NodeId;
430
8
    std::vector<NodeId> NodeStack;
431
8
432
8
    // Consume worklists.
433
161
    while (true) {
434
161
      if (!OptimallyReducibleNodes.empty()) {
435
75
        NodeSet::iterator NItr = OptimallyReducibleNodes.begin();
436
75
        NodeId NId = *NItr;
437
75
        OptimallyReducibleNodes.erase(NItr);
438
75
        NodeStack.push_back(NId);
439
75
        switch (G.getNodeDegree(NId)) {
440
75
        case 0:
441
23
          break;
442
75
        case 1:
443
17
          applyR1(G, NId);
444
17
          break;
445
75
        case 2:
446
35
          applyR2(G, NId);
447
35
          break;
448
75
        
default: 0
llvm_unreachable0
("Not an optimally reducible node.");
449
86
        }
450
86
      } else if (!ConservativelyAllocatableNodes.empty()) {
451
68
        // Conservatively allocatable nodes will never spill. For now just
452
68
        // take the first node in the set and push it on the stack. When we
453
68
        // start optimizing more heavily for register preferencing, it may
454
68
        // would be better to push nodes with lower 'expected' or worst-case
455
68
        // register costs first (since early nodes are the most
456
68
        // constrained).
457
68
        NodeSet::iterator NItr = ConservativelyAllocatableNodes.begin();
458
68
        NodeId NId = *NItr;
459
68
        ConservativelyAllocatableNodes.erase(NItr);
460
68
        NodeStack.push_back(NId);
461
68
        G.disconnectAllNeighborsFromNode(NId);
462
68
      } else 
if (18
!NotProvablyAllocatableNodes.empty()18
) {
463
10
        NodeSet::iterator NItr =
464
10
          std::min_element(NotProvablyAllocatableNodes.begin(),
465
10
                           NotProvablyAllocatableNodes.end(),
466
10
                           SpillCostComparator(G));
467
10
        NodeId NId = *NItr;
468
10
        NotProvablyAllocatableNodes.erase(NItr);
469
10
        NodeStack.push_back(NId);
470
10
        G.disconnectAllNeighborsFromNode(NId);
471
10
      } else
472
8
        break;
473
161
    }
474
8
475
8
    return NodeStack;
476
8
  }
477
478
  class SpillCostComparator {
479
  public:
480
10
    SpillCostComparator(const Graph& G) : G(G) {}
481
482
105
    bool operator()(NodeId N1Id, NodeId N2Id) {
483
105
      PBQPNum N1SC = G.getNodeCosts(N1Id)[0];
484
105
      PBQPNum N2SC = G.getNodeCosts(N2Id)[0];
485
105
      if (N1SC == N2SC)
486
0
        return G.getNodeDegree(N1Id) < G.getNodeDegree(N2Id);
487
105
      return N1SC < N2SC;
488
105
    }
489
490
  private:
491
    const Graph& G;
492
  };
493
494
  Graph& G;
495
  using NodeSet = std::set<NodeId>;
496
  NodeSet OptimallyReducibleNodes;
497
  NodeSet ConservativelyAllocatableNodes;
498
  NodeSet NotProvablyAllocatableNodes;
499
};
500
501
class PBQPRAGraph : public PBQP::Graph<RegAllocSolverImpl> {
502
private:
503
  using BaseT = PBQP::Graph<RegAllocSolverImpl>;
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public:
506
8
  PBQPRAGraph(GraphMetadata Metadata) : BaseT(std::move(Metadata)) {}
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  /// Dump this graph to dbgs().
509
  void dump() const;
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  /// Dump this graph to an output stream.
512
  /// @param OS Output stream to print on.
513
  void dump(raw_ostream &OS) const;
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515
  /// Print a representation of this graph in DOT format.
516
  /// @param OS Output stream to print on.
517
  void printDot(raw_ostream &OS) const;
518
};
519
520
8
inline Solution solve(PBQPRAGraph& G) {
521
8
  if (G.empty())
522
0
    return Solution();
523
8
  RegAllocSolverImpl RegAllocSolver(G);
524
8
  return RegAllocSolver.solve();
525
8
}
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} // end namespace RegAlloc
528
} // end namespace PBQP
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/// Create a PBQP register allocator instance.
531
FunctionPass *
532
createPBQPRegisterAllocator(char *customPassID = nullptr);
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534
} // end namespace llvm
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536
#endif // LLVM_CODEGEN_REGALLOCPBQP_H