summaryrefslogtreecommitdiff
path: root/lib/Analysis/InlineCost.cpp
blob: 6e5c03582256e8468ca573bde9f763ab62ee3d92 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements inline cost analysis.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "inline-cost"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Operator.h"
#include "llvm/InstVisitor.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");

namespace {

class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
  typedef InstVisitor<CallAnalyzer, bool> Base;
  friend class InstVisitor<CallAnalyzer, bool>;

  // DataLayout if available, or null.
  const DataLayout *const TD;

  // The called function.
  Function &F;

  int Threshold;
  int Cost;

  bool IsCallerRecursive;
  bool IsRecursiveCall;
  bool ExposesReturnsTwice;
  bool HasDynamicAlloca;
  bool ContainsNoDuplicateCall;

  /// Number of bytes allocated statically by the callee.
  uint64_t AllocatedSize;
  unsigned NumInstructions, NumVectorInstructions;
  int FiftyPercentVectorBonus, TenPercentVectorBonus;
  int VectorBonus;

  // While we walk the potentially-inlined instructions, we build up and
  // maintain a mapping of simplified values specific to this callsite. The
  // idea is to propagate any special information we have about arguments to
  // this call through the inlinable section of the function, and account for
  // likely simplifications post-inlining. The most important aspect we track
  // is CFG altering simplifications -- when we prove a basic block dead, that
  // can cause dramatic shifts in the cost of inlining a function.
  DenseMap<Value *, Constant *> SimplifiedValues;

  // Keep track of the values which map back (through function arguments) to
  // allocas on the caller stack which could be simplified through SROA.
  DenseMap<Value *, Value *> SROAArgValues;

  // The mapping of caller Alloca values to their accumulated cost savings. If
  // we have to disable SROA for one of the allocas, this tells us how much
  // cost must be added.
  DenseMap<Value *, int> SROAArgCosts;

  // Keep track of values which map to a pointer base and constant offset.
  DenseMap<Value *, std::pair<Value *, APInt> > ConstantOffsetPtrs;

  // Custom simplification helper routines.
  bool isAllocaDerivedArg(Value *V);
  bool lookupSROAArgAndCost(Value *V, Value *&Arg,
                            DenseMap<Value *, int>::iterator &CostIt);
  void disableSROA(DenseMap<Value *, int>::iterator CostIt);
  void disableSROA(Value *V);
  void accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
                          int InstructionCost);
  bool handleSROACandidate(bool IsSROAValid,
                           DenseMap<Value *, int>::iterator CostIt,
                           int InstructionCost);
  bool isGEPOffsetConstant(GetElementPtrInst &GEP);
  bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
  bool simplifyCallSite(Function *F, CallSite CS);
  ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);

  // Custom analysis routines.
  bool analyzeBlock(BasicBlock *BB);

  // Disable several entry points to the visitor so we don't accidentally use
  // them by declaring but not defining them here.
  void visit(Module *);     void visit(Module &);
  void visit(Function *);   void visit(Function &);
  void visit(BasicBlock *); void visit(BasicBlock &);

  // Provide base case for our instruction visit.
  bool visitInstruction(Instruction &I);

  // Our visit overrides.
  bool visitAlloca(AllocaInst &I);
  bool visitPHI(PHINode &I);
  bool visitGetElementPtr(GetElementPtrInst &I);
  bool visitBitCast(BitCastInst &I);
  bool visitPtrToInt(PtrToIntInst &I);
  bool visitIntToPtr(IntToPtrInst &I);
  bool visitCastInst(CastInst &I);
  bool visitUnaryInstruction(UnaryInstruction &I);
  bool visitICmp(ICmpInst &I);
  bool visitSub(BinaryOperator &I);
  bool visitBinaryOperator(BinaryOperator &I);
  bool visitLoad(LoadInst &I);
  bool visitStore(StoreInst &I);
  bool visitExtractValue(ExtractValueInst &I);
  bool visitInsertValue(InsertValueInst &I);
  bool visitCallSite(CallSite CS);

public:
  CallAnalyzer(const DataLayout *TD, Function &Callee, int Threshold)
    : TD(TD), F(Callee), Threshold(Threshold), Cost(0),
      IsCallerRecursive(false), IsRecursiveCall(false),
      ExposesReturnsTwice(false), HasDynamicAlloca(false), ContainsNoDuplicateCall(false),
      AllocatedSize(0), NumInstructions(0), NumVectorInstructions(0),
      FiftyPercentVectorBonus(0), TenPercentVectorBonus(0), VectorBonus(0),
      NumConstantArgs(0), NumConstantOffsetPtrArgs(0), NumAllocaArgs(0),
      NumConstantPtrCmps(0), NumConstantPtrDiffs(0),
      NumInstructionsSimplified(0), SROACostSavings(0), SROACostSavingsLost(0) {
  }

  bool analyzeCall(CallSite CS);

  int getThreshold() { return Threshold; }
  int getCost() { return Cost; }

  // Keep a bunch of stats about the cost savings found so we can print them
  // out when debugging.
  unsigned NumConstantArgs;
  unsigned NumConstantOffsetPtrArgs;
  unsigned NumAllocaArgs;
  unsigned NumConstantPtrCmps;
  unsigned NumConstantPtrDiffs;
  unsigned NumInstructionsSimplified;
  unsigned SROACostSavings;
  unsigned SROACostSavingsLost;

  void dump();
};

} // namespace

/// \brief Test whether the given value is an Alloca-derived function argument.
bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
  return SROAArgValues.count(V);
}

/// \brief Lookup the SROA-candidate argument and cost iterator which V maps to.
/// Returns false if V does not map to a SROA-candidate.
bool CallAnalyzer::lookupSROAArgAndCost(
    Value *V, Value *&Arg, DenseMap<Value *, int>::iterator &CostIt) {
  if (SROAArgValues.empty() || SROAArgCosts.empty())
    return false;

  DenseMap<Value *, Value *>::iterator ArgIt = SROAArgValues.find(V);
  if (ArgIt == SROAArgValues.end())
    return false;

  Arg = ArgIt->second;
  CostIt = SROAArgCosts.find(Arg);
  return CostIt != SROAArgCosts.end();
}

/// \brief Disable SROA for the candidate marked by this cost iterator.
///
/// This marks the candidate as no longer viable for SROA, and adds the cost
/// savings associated with it back into the inline cost measurement.
void CallAnalyzer::disableSROA(DenseMap<Value *, int>::iterator CostIt) {
  // If we're no longer able to perform SROA we need to undo its cost savings
  // and prevent subsequent analysis.
  Cost += CostIt->second;
  SROACostSavings -= CostIt->second;
  SROACostSavingsLost += CostIt->second;
  SROAArgCosts.erase(CostIt);
}

/// \brief If 'V' maps to a SROA candidate, disable SROA for it.
void CallAnalyzer::disableSROA(Value *V) {
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(V, SROAArg, CostIt))
    disableSROA(CostIt);
}

/// \brief Accumulate the given cost for a particular SROA candidate.
void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
                                      int InstructionCost) {
  CostIt->second += InstructionCost;
  SROACostSavings += InstructionCost;
}

/// \brief Helper for the common pattern of handling a SROA candidate.
/// Either accumulates the cost savings if the SROA remains valid, or disables
/// SROA for the candidate.
bool CallAnalyzer::handleSROACandidate(bool IsSROAValid,
                                       DenseMap<Value *, int>::iterator CostIt,
                                       int InstructionCost) {
  if (IsSROAValid) {
    accumulateSROACost(CostIt, InstructionCost);
    return true;
  }

  disableSROA(CostIt);
  return false;
}

/// \brief Check whether a GEP's indices are all constant.
///
/// Respects any simplified values known during the analysis of this callsite.
bool CallAnalyzer::isGEPOffsetConstant(GetElementPtrInst &GEP) {
  for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
    if (!isa<Constant>(*I) && !SimplifiedValues.lookup(*I))
      return false;

  return true;
}

/// \brief Accumulate a constant GEP offset into an APInt if possible.
///
/// Returns false if unable to compute the offset for any reason. Respects any
/// simplified values known during the analysis of this callsite.
bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
  if (!TD)
    return false;

  unsigned IntPtrWidth = TD->getPointerSizeInBits();
  assert(IntPtrWidth == Offset.getBitWidth());

  for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
       GTI != GTE; ++GTI) {
    ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
    if (!OpC)
      if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
        OpC = dyn_cast<ConstantInt>(SimpleOp);
    if (!OpC)
      return false;
    if (OpC->isZero()) continue;

    // Handle a struct index, which adds its field offset to the pointer.
    if (StructType *STy = dyn_cast<StructType>(*GTI)) {
      unsigned ElementIdx = OpC->getZExtValue();
      const StructLayout *SL = TD->getStructLayout(STy);
      Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
      continue;
    }

    APInt TypeSize(IntPtrWidth, TD->getTypeAllocSize(GTI.getIndexedType()));
    Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
  }
  return true;
}

bool CallAnalyzer::visitAlloca(AllocaInst &I) {
  // FIXME: Check whether inlining will turn a dynamic alloca into a static
  // alloca, and handle that case.

  // Accumulate the allocated size.
  if (I.isStaticAlloca()) {
    Type *Ty = I.getAllocatedType();
    AllocatedSize += (TD ? TD->getTypeAllocSize(Ty) :
                      Ty->getPrimitiveSizeInBits());
  }

  // We will happily inline static alloca instructions.
  if (I.isStaticAlloca())
    return Base::visitAlloca(I);

  // FIXME: This is overly conservative. Dynamic allocas are inefficient for
  // a variety of reasons, and so we would like to not inline them into
  // functions which don't currently have a dynamic alloca. This simply
  // disables inlining altogether in the presence of a dynamic alloca.
  HasDynamicAlloca = true;
  return false;
}

bool CallAnalyzer::visitPHI(PHINode &I) {
  // FIXME: We should potentially be tracking values through phi nodes,
  // especially when they collapse to a single value due to deleted CFG edges
  // during inlining.

  // FIXME: We need to propagate SROA *disabling* through phi nodes, even
  // though we don't want to propagate it's bonuses. The idea is to disable
  // SROA if it *might* be used in an inappropriate manner.

  // Phi nodes are always zero-cost.
  return true;
}

bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  bool SROACandidate = lookupSROAArgAndCost(I.getPointerOperand(),
                                            SROAArg, CostIt);

  // Try to fold GEPs of constant-offset call site argument pointers. This
  // requires target data and inbounds GEPs.
  if (TD && I.isInBounds()) {
    // Check if we have a base + offset for the pointer.
    Value *Ptr = I.getPointerOperand();
    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Ptr);
    if (BaseAndOffset.first) {
      // Check if the offset of this GEP is constant, and if so accumulate it
      // into Offset.
      if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second)) {
        // Non-constant GEPs aren't folded, and disable SROA.
        if (SROACandidate)
          disableSROA(CostIt);
        return false;
      }

      // Add the result as a new mapping to Base + Offset.
      ConstantOffsetPtrs[&I] = BaseAndOffset;

      // Also handle SROA candidates here, we already know that the GEP is
      // all-constant indexed.
      if (SROACandidate)
        SROAArgValues[&I] = SROAArg;

      return true;
    }
  }

  if (isGEPOffsetConstant(I)) {
    if (SROACandidate)
      SROAArgValues[&I] = SROAArg;

    // Constant GEPs are modeled as free.
    return true;
  }

  // Variable GEPs will require math and will disable SROA.
  if (SROACandidate)
    disableSROA(CostIt);
  return false;
}

bool CallAnalyzer::visitBitCast(BitCastInst &I) {
  // Propagate constants through bitcasts.
  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
  if (!COp)
    COp = SimplifiedValues.lookup(I.getOperand(0));
  if (COp)
    if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) {
      SimplifiedValues[&I] = C;
      return true;
    }

  // Track base/offsets through casts
  std::pair<Value *, APInt> BaseAndOffset
    = ConstantOffsetPtrs.lookup(I.getOperand(0));
  // Casts don't change the offset, just wrap it up.
  if (BaseAndOffset.first)
    ConstantOffsetPtrs[&I] = BaseAndOffset;

  // Also look for SROA candidates here.
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
    SROAArgValues[&I] = SROAArg;

  // Bitcasts are always zero cost.
  return true;
}

bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
  // Propagate constants through ptrtoint.
  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
  if (!COp)
    COp = SimplifiedValues.lookup(I.getOperand(0));
  if (COp)
    if (Constant *C = ConstantExpr::getPtrToInt(COp, I.getType())) {
      SimplifiedValues[&I] = C;
      return true;
    }

  // Track base/offset pairs when converted to a plain integer provided the
  // integer is large enough to represent the pointer.
  unsigned IntegerSize = I.getType()->getScalarSizeInBits();
  if (TD && IntegerSize >= TD->getPointerSizeInBits()) {
    std::pair<Value *, APInt> BaseAndOffset
      = ConstantOffsetPtrs.lookup(I.getOperand(0));
    if (BaseAndOffset.first)
      ConstantOffsetPtrs[&I] = BaseAndOffset;
  }

  // This is really weird. Technically, ptrtoint will disable SROA. However,
  // unless that ptrtoint is *used* somewhere in the live basic blocks after
  // inlining, it will be nuked, and SROA should proceed. All of the uses which
  // would block SROA would also block SROA if applied directly to a pointer,
  // and so we can just add the integer in here. The only places where SROA is
  // preserved either cannot fire on an integer, or won't in-and-of themselves
  // disable SROA (ext) w/o some later use that we would see and disable.
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
    SROAArgValues[&I] = SROAArg;

  return isInstructionFree(&I, TD);
}

bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
  // Propagate constants through ptrtoint.
  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
  if (!COp)
    COp = SimplifiedValues.lookup(I.getOperand(0));
  if (COp)
    if (Constant *C = ConstantExpr::getIntToPtr(COp, I.getType())) {
      SimplifiedValues[&I] = C;
      return true;
    }

  // Track base/offset pairs when round-tripped through a pointer without
  // modifications provided the integer is not too large.
  Value *Op = I.getOperand(0);
  unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
  if (TD && IntegerSize <= TD->getPointerSizeInBits()) {
    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
    if (BaseAndOffset.first)
      ConstantOffsetPtrs[&I] = BaseAndOffset;
  }

  // "Propagate" SROA here in the same manner as we do for ptrtoint above.
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(Op, SROAArg, CostIt))
    SROAArgValues[&I] = SROAArg;

  return isInstructionFree(&I, TD);
}

bool CallAnalyzer::visitCastInst(CastInst &I) {
  // Propagate constants through ptrtoint.
  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
  if (!COp)
    COp = SimplifiedValues.lookup(I.getOperand(0));
  if (COp)
    if (Constant *C = ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) {
      SimplifiedValues[&I] = C;
      return true;
    }

  // Disable SROA in the face of arbitrary casts we don't whitelist elsewhere.
  disableSROA(I.getOperand(0));

  return isInstructionFree(&I, TD);
}

bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
  Value *Operand = I.getOperand(0);
  Constant *Ops[1] = { dyn_cast<Constant>(Operand) };
  if (Ops[0] || (Ops[0] = SimplifiedValues.lookup(Operand)))
    if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(),
                                               Ops, TD)) {
      SimplifiedValues[&I] = C;
      return true;
    }

  // Disable any SROA on the argument to arbitrary unary operators.
  disableSROA(Operand);

  return false;
}

bool CallAnalyzer::visitICmp(ICmpInst &I) {
  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
  // First try to handle simplified comparisons.
  if (!isa<Constant>(LHS))
    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
      LHS = SimpleLHS;
  if (!isa<Constant>(RHS))
    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
      RHS = SimpleRHS;
  if (Constant *CLHS = dyn_cast<Constant>(LHS))
    if (Constant *CRHS = dyn_cast<Constant>(RHS))
      if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
        SimplifiedValues[&I] = C;
        return true;
      }

  // Otherwise look for a comparison between constant offset pointers with
  // a common base.
  Value *LHSBase, *RHSBase;
  APInt LHSOffset, RHSOffset;
  llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
  if (LHSBase) {
    llvm::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
    if (RHSBase && LHSBase == RHSBase) {
      // We have common bases, fold the icmp to a constant based on the
      // offsets.
      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
      if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
        SimplifiedValues[&I] = C;
        ++NumConstantPtrCmps;
        return true;
      }
    }
  }

  // If the comparison is an equality comparison with null, we can simplify it
  // for any alloca-derived argument.
  if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)))
    if (isAllocaDerivedArg(I.getOperand(0))) {
      // We can actually predict the result of comparisons between an
      // alloca-derived value and null. Note that this fires regardless of
      // SROA firing.
      bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
      SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
                                        : ConstantInt::getFalse(I.getType());
      return true;
    }

  // Finally check for SROA candidates in comparisons.
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
    if (isa<ConstantPointerNull>(I.getOperand(1))) {
      accumulateSROACost(CostIt, InlineConstants::InstrCost);
      return true;
    }

    disableSROA(CostIt);
  }

  return false;
}

bool CallAnalyzer::visitSub(BinaryOperator &I) {
  // Try to handle a special case: we can fold computing the difference of two
  // constant-related pointers.
  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
  Value *LHSBase, *RHSBase;
  APInt LHSOffset, RHSOffset;
  llvm::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
  if (LHSBase) {
    llvm::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
    if (RHSBase && LHSBase == RHSBase) {
      // We have common bases, fold the subtract to a constant based on the
      // offsets.
      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
      if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
        SimplifiedValues[&I] = C;
        ++NumConstantPtrDiffs;
        return true;
      }
    }
  }

  // Otherwise, fall back to the generic logic for simplifying and handling
  // instructions.
  return Base::visitSub(I);
}

bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
  if (!isa<Constant>(LHS))
    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
      LHS = SimpleLHS;
  if (!isa<Constant>(RHS))
    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
      RHS = SimpleRHS;
  Value *SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, TD);
  if (Constant *C = dyn_cast_or_null<Constant>(SimpleV)) {
    SimplifiedValues[&I] = C;
    return true;
  }

  // Disable any SROA on arguments to arbitrary, unsimplified binary operators.
  disableSROA(LHS);
  disableSROA(RHS);

  return false;
}

bool CallAnalyzer::visitLoad(LoadInst &I) {
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
    if (I.isSimple()) {
      accumulateSROACost(CostIt, InlineConstants::InstrCost);
      return true;
    }

    disableSROA(CostIt);
  }

  return false;
}

bool CallAnalyzer::visitStore(StoreInst &I) {
  Value *SROAArg;
  DenseMap<Value *, int>::iterator CostIt;
  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
    if (I.isSimple()) {
      accumulateSROACost(CostIt, InlineConstants::InstrCost);
      return true;
    }

    disableSROA(CostIt);
  }

  return false;
}

bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) {
  // Constant folding for extract value is trivial.
  Constant *C = dyn_cast<Constant>(I.getAggregateOperand());
  if (!C)
    C = SimplifiedValues.lookup(I.getAggregateOperand());
  if (C) {
    SimplifiedValues[&I] = ConstantExpr::getExtractValue(C, I.getIndices());
    return true;
  }

  // SROA can look through these but give them a cost.
  return false;
}

bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
  // Constant folding for insert value is trivial.
  Constant *AggC = dyn_cast<Constant>(I.getAggregateOperand());
  if (!AggC)
    AggC = SimplifiedValues.lookup(I.getAggregateOperand());
  Constant *InsertedC = dyn_cast<Constant>(I.getInsertedValueOperand());
  if (!InsertedC)
    InsertedC = SimplifiedValues.lookup(I.getInsertedValueOperand());
  if (AggC && InsertedC) {
    SimplifiedValues[&I] = ConstantExpr::getInsertValue(AggC, InsertedC,
                                                        I.getIndices());
    return true;
  }

  // SROA can look through these but give them a cost.
  return false;
}

/// \brief Try to simplify a call site.
///
/// Takes a concrete function and callsite and tries to actually simplify it by
/// analyzing the arguments and call itself with instsimplify. Returns true if
/// it has simplified the callsite to some other entity (a constant), making it
/// free.
bool CallAnalyzer::simplifyCallSite(Function *F, CallSite CS) {
  // FIXME: Using the instsimplify logic directly for this is inefficient
  // because we have to continually rebuild the argument list even when no
  // simplifications can be performed. Until that is fixed with remapping
  // inside of instsimplify, directly constant fold calls here.
  if (!canConstantFoldCallTo(F))
    return false;

  // Try to re-map the arguments to constants.
  SmallVector<Constant *, 4> ConstantArgs;
  ConstantArgs.reserve(CS.arg_size());
  for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
       I != E; ++I) {
    Constant *C = dyn_cast<Constant>(*I);
    if (!C)
      C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(*I));
    if (!C)
      return false; // This argument doesn't map to a constant.

    ConstantArgs.push_back(C);
  }
  if (Constant *C = ConstantFoldCall(F, ConstantArgs)) {
    SimplifiedValues[CS.getInstruction()] = C;
    return true;
  }

  return false;
}

bool CallAnalyzer::visitCallSite(CallSite CS) {
  if (CS.isCall() && cast<CallInst>(CS.getInstruction())->canReturnTwice() &&
      !F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                      Attribute::ReturnsTwice)) {
    // This aborts the entire analysis.
    ExposesReturnsTwice = true;
    return false;
  }
  if (CS.isCall() &&
      cast<CallInst>(CS.getInstruction())->hasFnAttr(Attribute::NoDuplicate))
    ContainsNoDuplicateCall = true;

  if (Function *F = CS.getCalledFunction()) {
    // When we have a concrete function, first try to simplify it directly.
    if (simplifyCallSite(F, CS))
      return true;

    // Next check if it is an intrinsic we know about.
    // FIXME: Lift this into part of the InstVisitor.
    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
      switch (II->getIntrinsicID()) {
      default:
        return Base::visitCallSite(CS);

      case Intrinsic::memset:
      case Intrinsic::memcpy:
      case Intrinsic::memmove:
        // SROA can usually chew through these intrinsics, but they aren't free.
        return false;
      }
    }

    if (F == CS.getInstruction()->getParent()->getParent()) {
      // This flag will fully abort the analysis, so don't bother with anything
      // else.
      IsRecursiveCall = true;
      return false;
    }

    if (!callIsSmall(CS)) {
      // We account for the average 1 instruction per call argument setup
      // here.
      Cost += CS.arg_size() * InlineConstants::InstrCost;

      // Everything other than inline ASM will also have a significant cost
      // merely from making the call.
      if (!isa<InlineAsm>(CS.getCalledValue()))
        Cost += InlineConstants::CallPenalty;
    }

    return Base::visitCallSite(CS);
  }

  // Otherwise we're in a very special case -- an indirect function call. See
  // if we can be particularly clever about this.
  Value *Callee = CS.getCalledValue();

  // First, pay the price of the argument setup. We account for the average
  // 1 instruction per call argument setup here.
  Cost += CS.arg_size() * InlineConstants::InstrCost;

  // Next, check if this happens to be an indirect function call to a known
  // function in this inline context. If not, we've done all we can.
  Function *F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
  if (!F)
    return Base::visitCallSite(CS);

  // If we have a constant that we are calling as a function, we can peer
  // through it and see the function target. This happens not infrequently
  // during devirtualization and so we want to give it a hefty bonus for
  // inlining, but cap that bonus in the event that inlining wouldn't pan
  // out. Pretend to inline the function, with a custom threshold.
  CallAnalyzer CA(TD, *F, InlineConstants::IndirectCallThreshold);
  if (CA.analyzeCall(CS)) {
    // We were able to inline the indirect call! Subtract the cost from the
    // bonus we want to apply, but don't go below zero.
    Cost -= std::max(0, InlineConstants::IndirectCallThreshold - CA.getCost());
  }

  return Base::visitCallSite(CS);
}

bool CallAnalyzer::visitInstruction(Instruction &I) {
  // Some instructions are free. All of the free intrinsics can also be
  // handled by SROA, etc.
  if (isInstructionFree(&I, TD))
    return true;

  // We found something we don't understand or can't handle. Mark any SROA-able
  // values in the operand list as no longer viable.
  for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI)
    disableSROA(*OI);

  return false;
}


/// \brief Analyze a basic block for its contribution to the inline cost.
///
/// This method walks the analyzer over every instruction in the given basic
/// block and accounts for their cost during inlining at this callsite. It
/// aborts early if the threshold has been exceeded or an impossible to inline
/// construct has been detected. It returns false if inlining is no longer
/// viable, and true if inlining remains viable.
bool CallAnalyzer::analyzeBlock(BasicBlock *BB) {
  for (BasicBlock::iterator I = BB->begin(), E = llvm::prior(BB->end());
       I != E; ++I) {
    ++NumInstructions;
    if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
      ++NumVectorInstructions;

    // If the instruction simplified to a constant, there is no cost to this
    // instruction. Visit the instructions using our InstVisitor to account for
    // all of the per-instruction logic. The visit tree returns true if we
    // consumed the instruction in any way, and false if the instruction's base
    // cost should count against inlining.
    if (Base::visit(I))
      ++NumInstructionsSimplified;
    else
      Cost += InlineConstants::InstrCost;

    // If the visit this instruction detected an uninlinable pattern, abort.
    if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca)
      return false;

    // If the caller is a recursive function then we don't want to inline
    // functions which allocate a lot of stack space because it would increase
    // the caller stack usage dramatically.
    if (IsCallerRecursive &&
        AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
      return false;

    if (NumVectorInstructions > NumInstructions/2)
      VectorBonus = FiftyPercentVectorBonus;
    else if (NumVectorInstructions > NumInstructions/10)
      VectorBonus = TenPercentVectorBonus;
    else
      VectorBonus = 0;

    // Check if we've past the threshold so we don't spin in huge basic
    // blocks that will never inline.
    if (Cost > (Threshold + VectorBonus))
      return false;
  }

  return true;
}

/// \brief Compute the base pointer and cumulative constant offsets for V.
///
/// This strips all constant offsets off of V, leaving it the base pointer, and
/// accumulates the total constant offset applied in the returned constant. It
/// returns 0 if V is not a pointer, and returns the constant '0' if there are
/// no constant offsets applied.
ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
  if (!TD || !V->getType()->isPointerTy())
    return 0;

  unsigned IntPtrWidth = TD->getPointerSizeInBits();
  APInt Offset = APInt::getNullValue(IntPtrWidth);

  // Even though we don't look through PHI nodes, we could be called on an
  // instruction in an unreachable block, which may be on a cycle.
  SmallPtrSet<Value *, 4> Visited;
  Visited.insert(V);
  do {
    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
      if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
        return 0;
      V = GEP->getPointerOperand();
    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
      V = cast<Operator>(V)->getOperand(0);
    } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
      if (GA->mayBeOverridden())
        break;
      V = GA->getAliasee();
    } else {
      break;
    }
    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
  } while (Visited.insert(V));

  Type *IntPtrTy = TD->getIntPtrType(V->getContext());
  return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
}

/// \brief Analyze a call site for potential inlining.
///
/// Returns true if inlining this call is viable, and false if it is not
/// viable. It computes the cost and adjusts the threshold based on numerous
/// factors and heuristics. If this method returns false but the computed cost
/// is below the computed threshold, then inlining was forcibly disabled by
/// some artifact of the routine.
bool CallAnalyzer::analyzeCall(CallSite CS) {
  ++NumCallsAnalyzed;

  // Track whether the post-inlining function would have more than one basic
  // block. A single basic block is often intended for inlining. Balloon the
  // threshold by 50% until we pass the single-BB phase.
  bool SingleBB = true;
  int SingleBBBonus = Threshold / 2;
  Threshold += SingleBBBonus;

  // Perform some tweaks to the cost and threshold based on the direct
  // callsite information.

  // We want to more aggressively inline vector-dense kernels, so up the
  // threshold, and we'll lower it if the % of vector instructions gets too
  // low.
  assert(NumInstructions == 0);
  assert(NumVectorInstructions == 0);
  FiftyPercentVectorBonus = Threshold;
  TenPercentVectorBonus = Threshold / 2;

  // Give out bonuses per argument, as the instructions setting them up will
  // be gone after inlining.
  for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) {
    if (TD && CS.isByValArgument(I)) {
      // We approximate the number of loads and stores needed by dividing the
      // size of the byval type by the target's pointer size.
      PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
      unsigned TypeSize = TD->getTypeSizeInBits(PTy->getElementType());
      unsigned PointerSize = TD->getPointerSizeInBits();
      // Ceiling division.
      unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;

      // If it generates more than 8 stores it is likely to be expanded as an
      // inline memcpy so we take that as an upper bound. Otherwise we assume
      // one load and one store per word copied.
      // FIXME: The maxStoresPerMemcpy setting from the target should be used
      // here instead of a magic number of 8, but it's not available via
      // DataLayout.
      NumStores = std::min(NumStores, 8U);

      Cost -= 2 * NumStores * InlineConstants::InstrCost;
    } else {
      // For non-byval arguments subtract off one instruction per call
      // argument.
      Cost -= InlineConstants::InstrCost;
    }
  }

  // If there is only one call of the function, and it has internal linkage,
  // the cost of inlining it drops dramatically.
  bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
    &F == CS.getCalledFunction();
  if (OnlyOneCallAndLocalLinkage)
    Cost += InlineConstants::LastCallToStaticBonus;

  // If the instruction after the call, or if the normal destination of the
  // invoke is an unreachable instruction, the function is noreturn. As such,
  // there is little point in inlining this unless there is literally zero
  // cost.
  Instruction *Instr = CS.getInstruction();
  if (InvokeInst *II = dyn_cast<InvokeInst>(Instr)) {
    if (isa<UnreachableInst>(II->getNormalDest()->begin()))
      Threshold = 1;
  } else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
    Threshold = 1;

  // If this function uses the coldcc calling convention, prefer not to inline
  // it.
  if (F.getCallingConv() == CallingConv::Cold)
    Cost += InlineConstants::ColdccPenalty;

  // Check if we're done. This can happen due to bonuses and penalties.
  if (Cost > Threshold)
    return false;

  if (F.empty())
    return true;

  Function *Caller = CS.getInstruction()->getParent()->getParent();
  // Check if the caller function is recursive itself.
  for (Value::use_iterator U = Caller->use_begin(), E = Caller->use_end();
       U != E; ++U) {
    CallSite Site(cast<Value>(*U));
    if (!Site)
      continue;
    Instruction *I = Site.getInstruction();
    if (I->getParent()->getParent() == Caller) {
      IsCallerRecursive = true;
      break;
    }
  }

  // Track whether we've seen a return instruction. The first return
  // instruction is free, as at least one will usually disappear in inlining.
  bool HasReturn = false;

  // Populate our simplified values by mapping from function arguments to call
  // arguments with known important simplifications.
  CallSite::arg_iterator CAI = CS.arg_begin();
  for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
       FAI != FAE; ++FAI, ++CAI) {
    assert(CAI != CS.arg_end());
    if (Constant *C = dyn_cast<Constant>(CAI))
      SimplifiedValues[FAI] = C;

    Value *PtrArg = *CAI;
    if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
      ConstantOffsetPtrs[FAI] = std::make_pair(PtrArg, C->getValue());

      // We can SROA any pointer arguments derived from alloca instructions.
      if (isa<AllocaInst>(PtrArg)) {
        SROAArgValues[FAI] = PtrArg;
        SROAArgCosts[PtrArg] = 0;
      }
    }
  }
  NumConstantArgs = SimplifiedValues.size();
  NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
  NumAllocaArgs = SROAArgValues.size();

  // The worklist of live basic blocks in the callee *after* inlining. We avoid
  // adding basic blocks of the callee which can be proven to be dead for this
  // particular call site in order to get more accurate cost estimates. This
  // requires a somewhat heavyweight iteration pattern: we need to walk the
  // basic blocks in a breadth-first order as we insert live successors. To
  // accomplish this, prioritizing for small iterations because we exit after
  // crossing our threshold, we use a small-size optimized SetVector.
  typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
                                  SmallPtrSet<BasicBlock *, 16> > BBSetVector;
  BBSetVector BBWorklist;
  BBWorklist.insert(&F.getEntryBlock());
  // Note that we *must not* cache the size, this loop grows the worklist.
  for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
    // Bail out the moment we cross the threshold. This means we'll under-count
    // the cost, but only when undercounting doesn't matter.
    if (Cost > (Threshold + VectorBonus))
      break;

    BasicBlock *BB = BBWorklist[Idx];
    if (BB->empty())
      continue;

    // Handle the terminator cost here where we can track returns and other
    // function-wide constructs.
    TerminatorInst *TI = BB->getTerminator();

    // We never want to inline functions that contain an indirectbr.  This is
    // incorrect because all the blockaddress's (in static global initializers
    // for example) would be referring to the original function, and this
    // indirect jump would jump from the inlined copy of the function into the 
    // original function which is extremely undefined behavior.
    // FIXME: This logic isn't really right; we can safely inline functions
    // with indirectbr's as long as no other function or global references the
    // blockaddress of a block within the current function.  And as a QOI issue,
    // if someone is using a blockaddress without an indirectbr, and that
    // reference somehow ends up in another function or global, we probably
    // don't want to inline this function.
    if (isa<IndirectBrInst>(TI))
      return false;

    if (!HasReturn && isa<ReturnInst>(TI))
      HasReturn = true;
    else
      Cost += InlineConstants::InstrCost;

    // Analyze the cost of this block. If we blow through the threshold, this
    // returns false, and we can bail on out.
    if (!analyzeBlock(BB)) {
      if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca)
        return false;

      // If the caller is a recursive function then we don't want to inline
      // functions which allocate a lot of stack space because it would increase
      // the caller stack usage dramatically.
      if (IsCallerRecursive &&
          AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
        return false;

      break;
    }

    // Add in the live successors by first checking whether we have terminator
    // that may be simplified based on the values simplified by this call.
    if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
      if (BI->isConditional()) {
        Value *Cond = BI->getCondition();
        if (ConstantInt *SimpleCond
              = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
          BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
          continue;
        }
      }
    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
      Value *Cond = SI->getCondition();
      if (ConstantInt *SimpleCond
            = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
        BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
        continue;
      }
    }

    // If we're unable to select a particular successor, just count all of
    // them.
    for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
         ++TIdx)
      BBWorklist.insert(TI->getSuccessor(TIdx));

    // If we had any successors at this point, than post-inlining is likely to
    // have them as well. Note that we assume any basic blocks which existed
    // due to branches or switches which folded above will also fold after
    // inlining.
    if (SingleBB && TI->getNumSuccessors() > 1) {
      // Take off the bonus we applied to the threshold.
      Threshold -= SingleBBBonus;
      SingleBB = false;
    }
  }

  // If this is a noduplicate call, we can still inline as long as 
  // inlining this would cause the removal of the caller (so the instruction
  // is not actually duplicated, just moved).
  if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
    return false;

  Threshold += VectorBonus;

  return Cost < Threshold;
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// \brief Dump stats about this call's analysis.
void CallAnalyzer::dump() {
#define DEBUG_PRINT_STAT(x) llvm::dbgs() << "      " #x ": " << x << "\n"
  DEBUG_PRINT_STAT(NumConstantArgs);
  DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
  DEBUG_PRINT_STAT(NumAllocaArgs);
  DEBUG_PRINT_STAT(NumConstantPtrCmps);
  DEBUG_PRINT_STAT(NumConstantPtrDiffs);
  DEBUG_PRINT_STAT(NumInstructionsSimplified);
  DEBUG_PRINT_STAT(SROACostSavings);
  DEBUG_PRINT_STAT(SROACostSavingsLost);
  DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
#undef DEBUG_PRINT_STAT
}
#endif

InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, int Threshold) {
  return getInlineCost(CS, CS.getCalledFunction(), Threshold);
}

InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, Function *Callee,
                                             int Threshold) {
  // Cannot inline indirect calls.
  if (!Callee)
    return llvm::InlineCost::getNever();

  // Calls to functions with always-inline attributes should be inlined
  // whenever possible.
  if (Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                           Attribute::AlwaysInline)) {
    if (isInlineViable(*Callee))
      return llvm::InlineCost::getAlways();
    return llvm::InlineCost::getNever();
  }

  // Don't inline functions which can be redefined at link-time to mean
  // something else.  Don't inline functions marked noinline or call sites
  // marked noinline.
  if (Callee->mayBeOverridden() ||
      Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                           Attribute::NoInline) ||
      CS.isNoInline())
    return llvm::InlineCost::getNever();

  DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
        << "...\n");

  CallAnalyzer CA(TD, *Callee, Threshold);
  bool ShouldInline = CA.analyzeCall(CS);

  DEBUG(CA.dump());

  // Check if there was a reason to force inlining or no inlining.
  if (!ShouldInline && CA.getCost() < CA.getThreshold())
    return InlineCost::getNever();
  if (ShouldInline && CA.getCost() >= CA.getThreshold())
    return InlineCost::getAlways();

  return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
}

bool InlineCostAnalyzer::isInlineViable(Function &F) {
  bool ReturnsTwice =F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                                    Attribute::ReturnsTwice);
  for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
    // Disallow inlining of functions which contain an indirect branch.
    if (isa<IndirectBrInst>(BI->getTerminator()))
      return false;

    for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;
         ++II) {
      CallSite CS(II);
      if (!CS)
        continue;

      // Disallow recursive calls.
      if (&F == CS.getCalledFunction())
        return false;

      // Disallow calls which expose returns-twice to a function not previously
      // attributed as such.
      if (!ReturnsTwice && CS.isCall() &&
          cast<CallInst>(CS.getInstruction())->canReturnTwice())
        return false;
    }
  }

  return true;
}