1//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
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 inline cost analysis.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Analysis/InlineCost.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/SetVector.h"
17#include "llvm/ADT/SmallPtrSet.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/Statistic.h"
20#include "llvm/Analysis/ConstantFolding.h"
21#include "llvm/Analysis/InstructionSimplify.h"
22#include "llvm/Analysis/TargetTransformInfo.h"
23#include "llvm/IR/CallSite.h"
24#include "llvm/IR/CallingConv.h"
25#include "llvm/IR/DataLayout.h"
26#include "llvm/IR/GetElementPtrTypeIterator.h"
27#include "llvm/IR/GlobalAlias.h"
28#include "llvm/IR/InstVisitor.h"
29#include "llvm/IR/IntrinsicInst.h"
30#include "llvm/IR/Operator.h"
31#include "llvm/Support/Debug.h"
32#include "llvm/Support/raw_ostream.h"
33
34using namespace llvm;
35
36#define DEBUG_TYPE "inline-cost"
37
38STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
39
40namespace {
41
42class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
43  typedef InstVisitor<CallAnalyzer, bool> Base;
44  friend class InstVisitor<CallAnalyzer, bool>;
45
46  // DataLayout if available, or null.
47  const DataLayout *const DL;
48
49  /// The TargetTransformInfo available for this compilation.
50  const TargetTransformInfo &TTI;
51
52  // The called function.
53  Function &F;
54
55  int Threshold;
56  int Cost;
57
58  bool IsCallerRecursive;
59  bool IsRecursiveCall;
60  bool ExposesReturnsTwice;
61  bool HasDynamicAlloca;
62  bool ContainsNoDuplicateCall;
63  bool HasReturn;
64  bool HasIndirectBr;
65
66  /// Number of bytes allocated statically by the callee.
67  uint64_t AllocatedSize;
68  unsigned NumInstructions, NumVectorInstructions;
69  int FiftyPercentVectorBonus, TenPercentVectorBonus;
70  int VectorBonus;
71
72  // While we walk the potentially-inlined instructions, we build up and
73  // maintain a mapping of simplified values specific to this callsite. The
74  // idea is to propagate any special information we have about arguments to
75  // this call through the inlinable section of the function, and account for
76  // likely simplifications post-inlining. The most important aspect we track
77  // is CFG altering simplifications -- when we prove a basic block dead, that
78  // can cause dramatic shifts in the cost of inlining a function.
79  DenseMap<Value *, Constant *> SimplifiedValues;
80
81  // Keep track of the values which map back (through function arguments) to
82  // allocas on the caller stack which could be simplified through SROA.
83  DenseMap<Value *, Value *> SROAArgValues;
84
85  // The mapping of caller Alloca values to their accumulated cost savings. If
86  // we have to disable SROA for one of the allocas, this tells us how much
87  // cost must be added.
88  DenseMap<Value *, int> SROAArgCosts;
89
90  // Keep track of values which map to a pointer base and constant offset.
91  DenseMap<Value *, std::pair<Value *, APInt> > ConstantOffsetPtrs;
92
93  // Custom simplification helper routines.
94  bool isAllocaDerivedArg(Value *V);
95  bool lookupSROAArgAndCost(Value *V, Value *&Arg,
96                            DenseMap<Value *, int>::iterator &CostIt);
97  void disableSROA(DenseMap<Value *, int>::iterator CostIt);
98  void disableSROA(Value *V);
99  void accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
100                          int InstructionCost);
101  bool isGEPOffsetConstant(GetElementPtrInst &GEP);
102  bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
103  bool simplifyCallSite(Function *F, CallSite CS);
104  ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
105
106  // Custom analysis routines.
107  bool analyzeBlock(BasicBlock *BB);
108
109  // Disable several entry points to the visitor so we don't accidentally use
110  // them by declaring but not defining them here.
111  void visit(Module *);     void visit(Module &);
112  void visit(Function *);   void visit(Function &);
113  void visit(BasicBlock *); void visit(BasicBlock &);
114
115  // Provide base case for our instruction visit.
116  bool visitInstruction(Instruction &I);
117
118  // Our visit overrides.
119  bool visitAlloca(AllocaInst &I);
120  bool visitPHI(PHINode &I);
121  bool visitGetElementPtr(GetElementPtrInst &I);
122  bool visitBitCast(BitCastInst &I);
123  bool visitPtrToInt(PtrToIntInst &I);
124  bool visitIntToPtr(IntToPtrInst &I);
125  bool visitCastInst(CastInst &I);
126  bool visitUnaryInstruction(UnaryInstruction &I);
127  bool visitCmpInst(CmpInst &I);
128  bool visitSub(BinaryOperator &I);
129  bool visitBinaryOperator(BinaryOperator &I);
130  bool visitLoad(LoadInst &I);
131  bool visitStore(StoreInst &I);
132  bool visitExtractValue(ExtractValueInst &I);
133  bool visitInsertValue(InsertValueInst &I);
134  bool visitCallSite(CallSite CS);
135  bool visitReturnInst(ReturnInst &RI);
136  bool visitBranchInst(BranchInst &BI);
137  bool visitSwitchInst(SwitchInst &SI);
138  bool visitIndirectBrInst(IndirectBrInst &IBI);
139  bool visitResumeInst(ResumeInst &RI);
140  bool visitUnreachableInst(UnreachableInst &I);
141
142public:
143  CallAnalyzer(const DataLayout *DL, const TargetTransformInfo &TTI,
144               Function &Callee, int Threshold)
145      : DL(DL), TTI(TTI), F(Callee), Threshold(Threshold), Cost(0),
146        IsCallerRecursive(false), IsRecursiveCall(false),
147        ExposesReturnsTwice(false), HasDynamicAlloca(false),
148        ContainsNoDuplicateCall(false), HasReturn(false), HasIndirectBr(false),
149        AllocatedSize(0), NumInstructions(0), NumVectorInstructions(0),
150        FiftyPercentVectorBonus(0), TenPercentVectorBonus(0), VectorBonus(0),
151        NumConstantArgs(0), NumConstantOffsetPtrArgs(0), NumAllocaArgs(0),
152        NumConstantPtrCmps(0), NumConstantPtrDiffs(0),
153        NumInstructionsSimplified(0), SROACostSavings(0),
154        SROACostSavingsLost(0) {}
155
156  bool analyzeCall(CallSite CS);
157
158  int getThreshold() { return Threshold; }
159  int getCost() { return Cost; }
160
161  // Keep a bunch of stats about the cost savings found so we can print them
162  // out when debugging.
163  unsigned NumConstantArgs;
164  unsigned NumConstantOffsetPtrArgs;
165  unsigned NumAllocaArgs;
166  unsigned NumConstantPtrCmps;
167  unsigned NumConstantPtrDiffs;
168  unsigned NumInstructionsSimplified;
169  unsigned SROACostSavings;
170  unsigned SROACostSavingsLost;
171
172  void dump();
173};
174
175} // namespace
176
177/// \brief Test whether the given value is an Alloca-derived function argument.
178bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
179  return SROAArgValues.count(V);
180}
181
182/// \brief Lookup the SROA-candidate argument and cost iterator which V maps to.
183/// Returns false if V does not map to a SROA-candidate.
184bool CallAnalyzer::lookupSROAArgAndCost(
185    Value *V, Value *&Arg, DenseMap<Value *, int>::iterator &CostIt) {
186  if (SROAArgValues.empty() || SROAArgCosts.empty())
187    return false;
188
189  DenseMap<Value *, Value *>::iterator ArgIt = SROAArgValues.find(V);
190  if (ArgIt == SROAArgValues.end())
191    return false;
192
193  Arg = ArgIt->second;
194  CostIt = SROAArgCosts.find(Arg);
195  return CostIt != SROAArgCosts.end();
196}
197
198/// \brief Disable SROA for the candidate marked by this cost iterator.
199///
200/// This marks the candidate as no longer viable for SROA, and adds the cost
201/// savings associated with it back into the inline cost measurement.
202void CallAnalyzer::disableSROA(DenseMap<Value *, int>::iterator CostIt) {
203  // If we're no longer able to perform SROA we need to undo its cost savings
204  // and prevent subsequent analysis.
205  Cost += CostIt->second;
206  SROACostSavings -= CostIt->second;
207  SROACostSavingsLost += CostIt->second;
208  SROAArgCosts.erase(CostIt);
209}
210
211/// \brief If 'V' maps to a SROA candidate, disable SROA for it.
212void CallAnalyzer::disableSROA(Value *V) {
213  Value *SROAArg;
214  DenseMap<Value *, int>::iterator CostIt;
215  if (lookupSROAArgAndCost(V, SROAArg, CostIt))
216    disableSROA(CostIt);
217}
218
219/// \brief Accumulate the given cost for a particular SROA candidate.
220void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
221                                      int InstructionCost) {
222  CostIt->second += InstructionCost;
223  SROACostSavings += InstructionCost;
224}
225
226/// \brief Check whether a GEP's indices are all constant.
227///
228/// Respects any simplified values known during the analysis of this callsite.
229bool CallAnalyzer::isGEPOffsetConstant(GetElementPtrInst &GEP) {
230  for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
231    if (!isa<Constant>(*I) && !SimplifiedValues.lookup(*I))
232      return false;
233
234  return true;
235}
236
237/// \brief Accumulate a constant GEP offset into an APInt if possible.
238///
239/// Returns false if unable to compute the offset for any reason. Respects any
240/// simplified values known during the analysis of this callsite.
241bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
242  if (!DL)
243    return false;
244
245  unsigned IntPtrWidth = DL->getPointerSizeInBits();
246  assert(IntPtrWidth == Offset.getBitWidth());
247
248  for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
249       GTI != GTE; ++GTI) {
250    ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
251    if (!OpC)
252      if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
253        OpC = dyn_cast<ConstantInt>(SimpleOp);
254    if (!OpC)
255      return false;
256    if (OpC->isZero()) continue;
257
258    // Handle a struct index, which adds its field offset to the pointer.
259    if (StructType *STy = dyn_cast<StructType>(*GTI)) {
260      unsigned ElementIdx = OpC->getZExtValue();
261      const StructLayout *SL = DL->getStructLayout(STy);
262      Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
263      continue;
264    }
265
266    APInt TypeSize(IntPtrWidth, DL->getTypeAllocSize(GTI.getIndexedType()));
267    Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
268  }
269  return true;
270}
271
272bool CallAnalyzer::visitAlloca(AllocaInst &I) {
273  // Check whether inlining will turn a dynamic alloca into a static
274  // alloca, and handle that case.
275  if (I.isArrayAllocation()) {
276    if (Constant *Size = SimplifiedValues.lookup(I.getArraySize())) {
277      ConstantInt *AllocSize = dyn_cast<ConstantInt>(Size);
278      assert(AllocSize && "Allocation size not a constant int?");
279      Type *Ty = I.getAllocatedType();
280      AllocatedSize += Ty->getPrimitiveSizeInBits() * AllocSize->getZExtValue();
281      return Base::visitAlloca(I);
282    }
283  }
284
285  // Accumulate the allocated size.
286  if (I.isStaticAlloca()) {
287    Type *Ty = I.getAllocatedType();
288    AllocatedSize += (DL ? DL->getTypeAllocSize(Ty) :
289                      Ty->getPrimitiveSizeInBits());
290  }
291
292  // We will happily inline static alloca instructions.
293  if (I.isStaticAlloca())
294    return Base::visitAlloca(I);
295
296  // FIXME: This is overly conservative. Dynamic allocas are inefficient for
297  // a variety of reasons, and so we would like to not inline them into
298  // functions which don't currently have a dynamic alloca. This simply
299  // disables inlining altogether in the presence of a dynamic alloca.
300  HasDynamicAlloca = true;
301  return false;
302}
303
304bool CallAnalyzer::visitPHI(PHINode &I) {
305  // FIXME: We should potentially be tracking values through phi nodes,
306  // especially when they collapse to a single value due to deleted CFG edges
307  // during inlining.
308
309  // FIXME: We need to propagate SROA *disabling* through phi nodes, even
310  // though we don't want to propagate it's bonuses. The idea is to disable
311  // SROA if it *might* be used in an inappropriate manner.
312
313  // Phi nodes are always zero-cost.
314  return true;
315}
316
317bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
318  Value *SROAArg;
319  DenseMap<Value *, int>::iterator CostIt;
320  bool SROACandidate = lookupSROAArgAndCost(I.getPointerOperand(),
321                                            SROAArg, CostIt);
322
323  // Try to fold GEPs of constant-offset call site argument pointers. This
324  // requires target data and inbounds GEPs.
325  if (DL && I.isInBounds()) {
326    // Check if we have a base + offset for the pointer.
327    Value *Ptr = I.getPointerOperand();
328    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Ptr);
329    if (BaseAndOffset.first) {
330      // Check if the offset of this GEP is constant, and if so accumulate it
331      // into Offset.
332      if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second)) {
333        // Non-constant GEPs aren't folded, and disable SROA.
334        if (SROACandidate)
335          disableSROA(CostIt);
336        return false;
337      }
338
339      // Add the result as a new mapping to Base + Offset.
340      ConstantOffsetPtrs[&I] = BaseAndOffset;
341
342      // Also handle SROA candidates here, we already know that the GEP is
343      // all-constant indexed.
344      if (SROACandidate)
345        SROAArgValues[&I] = SROAArg;
346
347      return true;
348    }
349  }
350
351  if (isGEPOffsetConstant(I)) {
352    if (SROACandidate)
353      SROAArgValues[&I] = SROAArg;
354
355    // Constant GEPs are modeled as free.
356    return true;
357  }
358
359  // Variable GEPs will require math and will disable SROA.
360  if (SROACandidate)
361    disableSROA(CostIt);
362  return false;
363}
364
365bool CallAnalyzer::visitBitCast(BitCastInst &I) {
366  // Propagate constants through bitcasts.
367  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
368  if (!COp)
369    COp = SimplifiedValues.lookup(I.getOperand(0));
370  if (COp)
371    if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) {
372      SimplifiedValues[&I] = C;
373      return true;
374    }
375
376  // Track base/offsets through casts
377  std::pair<Value *, APInt> BaseAndOffset
378    = ConstantOffsetPtrs.lookup(I.getOperand(0));
379  // Casts don't change the offset, just wrap it up.
380  if (BaseAndOffset.first)
381    ConstantOffsetPtrs[&I] = BaseAndOffset;
382
383  // Also look for SROA candidates here.
384  Value *SROAArg;
385  DenseMap<Value *, int>::iterator CostIt;
386  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
387    SROAArgValues[&I] = SROAArg;
388
389  // Bitcasts are always zero cost.
390  return true;
391}
392
393bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
394  const DataLayout *DL = I.getDataLayout();
395  // Propagate constants through ptrtoint.
396  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
397  if (!COp)
398    COp = SimplifiedValues.lookup(I.getOperand(0));
399  if (COp)
400    if (Constant *C = ConstantExpr::getPtrToInt(COp, I.getType())) {
401      SimplifiedValues[&I] = C;
402      return true;
403    }
404
405  // Track base/offset pairs when converted to a plain integer provided the
406  // integer is large enough to represent the pointer.
407  unsigned IntegerSize = I.getType()->getScalarSizeInBits();
408  if (DL && IntegerSize >= DL->getPointerSizeInBits()) {
409    std::pair<Value *, APInt> BaseAndOffset
410      = ConstantOffsetPtrs.lookup(I.getOperand(0));
411    if (BaseAndOffset.first)
412      ConstantOffsetPtrs[&I] = BaseAndOffset;
413  }
414
415  // This is really weird. Technically, ptrtoint will disable SROA. However,
416  // unless that ptrtoint is *used* somewhere in the live basic blocks after
417  // inlining, it will be nuked, and SROA should proceed. All of the uses which
418  // would block SROA would also block SROA if applied directly to a pointer,
419  // and so we can just add the integer in here. The only places where SROA is
420  // preserved either cannot fire on an integer, or won't in-and-of themselves
421  // disable SROA (ext) w/o some later use that we would see and disable.
422  Value *SROAArg;
423  DenseMap<Value *, int>::iterator CostIt;
424  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
425    SROAArgValues[&I] = SROAArg;
426
427  return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
428}
429
430bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
431  const DataLayout *DL = I.getDataLayout();
432  // Propagate constants through ptrtoint.
433  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
434  if (!COp)
435    COp = SimplifiedValues.lookup(I.getOperand(0));
436  if (COp)
437    if (Constant *C = ConstantExpr::getIntToPtr(COp, I.getType())) {
438      SimplifiedValues[&I] = C;
439      return true;
440    }
441
442  // Track base/offset pairs when round-tripped through a pointer without
443  // modifications provided the integer is not too large.
444  Value *Op = I.getOperand(0);
445  unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
446  if (DL && IntegerSize <= DL->getPointerSizeInBits()) {
447    std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
448    if (BaseAndOffset.first)
449      ConstantOffsetPtrs[&I] = BaseAndOffset;
450  }
451
452  // "Propagate" SROA here in the same manner as we do for ptrtoint above.
453  Value *SROAArg;
454  DenseMap<Value *, int>::iterator CostIt;
455  if (lookupSROAArgAndCost(Op, SROAArg, CostIt))
456    SROAArgValues[&I] = SROAArg;
457
458  return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
459}
460
461bool CallAnalyzer::visitCastInst(CastInst &I) {
462  // Propagate constants through ptrtoint.
463  Constant *COp = dyn_cast<Constant>(I.getOperand(0));
464  if (!COp)
465    COp = SimplifiedValues.lookup(I.getOperand(0));
466  if (COp)
467    if (Constant *C = ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) {
468      SimplifiedValues[&I] = C;
469      return true;
470    }
471
472  // Disable SROA in the face of arbitrary casts we don't whitelist elsewhere.
473  disableSROA(I.getOperand(0));
474
475  return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
476}
477
478bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
479  Value *Operand = I.getOperand(0);
480  Constant *COp = dyn_cast<Constant>(Operand);
481  if (!COp)
482    COp = SimplifiedValues.lookup(Operand);
483  if (COp)
484    if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(),
485                                               COp, DL)) {
486      SimplifiedValues[&I] = C;
487      return true;
488    }
489
490  // Disable any SROA on the argument to arbitrary unary operators.
491  disableSROA(Operand);
492
493  return false;
494}
495
496bool CallAnalyzer::visitCmpInst(CmpInst &I) {
497  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
498  // First try to handle simplified comparisons.
499  if (!isa<Constant>(LHS))
500    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
501      LHS = SimpleLHS;
502  if (!isa<Constant>(RHS))
503    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
504      RHS = SimpleRHS;
505  if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
506    if (Constant *CRHS = dyn_cast<Constant>(RHS))
507      if (Constant *C = ConstantExpr::getCompare(I.getPredicate(), CLHS, CRHS)) {
508        SimplifiedValues[&I] = C;
509        return true;
510      }
511  }
512
513  if (I.getOpcode() == Instruction::FCmp)
514    return false;
515
516  // Otherwise look for a comparison between constant offset pointers with
517  // a common base.
518  Value *LHSBase, *RHSBase;
519  APInt LHSOffset, RHSOffset;
520  std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
521  if (LHSBase) {
522    std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
523    if (RHSBase && LHSBase == RHSBase) {
524      // We have common bases, fold the icmp to a constant based on the
525      // offsets.
526      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
527      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
528      if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
529        SimplifiedValues[&I] = C;
530        ++NumConstantPtrCmps;
531        return true;
532      }
533    }
534  }
535
536  // If the comparison is an equality comparison with null, we can simplify it
537  // for any alloca-derived argument.
538  if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)))
539    if (isAllocaDerivedArg(I.getOperand(0))) {
540      // We can actually predict the result of comparisons between an
541      // alloca-derived value and null. Note that this fires regardless of
542      // SROA firing.
543      bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
544      SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
545                                        : ConstantInt::getFalse(I.getType());
546      return true;
547    }
548
549  // Finally check for SROA candidates in comparisons.
550  Value *SROAArg;
551  DenseMap<Value *, int>::iterator CostIt;
552  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
553    if (isa<ConstantPointerNull>(I.getOperand(1))) {
554      accumulateSROACost(CostIt, InlineConstants::InstrCost);
555      return true;
556    }
557
558    disableSROA(CostIt);
559  }
560
561  return false;
562}
563
564bool CallAnalyzer::visitSub(BinaryOperator &I) {
565  // Try to handle a special case: we can fold computing the difference of two
566  // constant-related pointers.
567  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
568  Value *LHSBase, *RHSBase;
569  APInt LHSOffset, RHSOffset;
570  std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
571  if (LHSBase) {
572    std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
573    if (RHSBase && LHSBase == RHSBase) {
574      // We have common bases, fold the subtract to a constant based on the
575      // offsets.
576      Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
577      Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
578      if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
579        SimplifiedValues[&I] = C;
580        ++NumConstantPtrDiffs;
581        return true;
582      }
583    }
584  }
585
586  // Otherwise, fall back to the generic logic for simplifying and handling
587  // instructions.
588  return Base::visitSub(I);
589}
590
591bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
592  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
593  if (!isa<Constant>(LHS))
594    if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
595      LHS = SimpleLHS;
596  if (!isa<Constant>(RHS))
597    if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
598      RHS = SimpleRHS;
599  Value *SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, DL);
600  if (Constant *C = dyn_cast_or_null<Constant>(SimpleV)) {
601    SimplifiedValues[&I] = C;
602    return true;
603  }
604
605  // Disable any SROA on arguments to arbitrary, unsimplified binary operators.
606  disableSROA(LHS);
607  disableSROA(RHS);
608
609  return false;
610}
611
612bool CallAnalyzer::visitLoad(LoadInst &I) {
613  Value *SROAArg;
614  DenseMap<Value *, int>::iterator CostIt;
615  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
616    if (I.isSimple()) {
617      accumulateSROACost(CostIt, InlineConstants::InstrCost);
618      return true;
619    }
620
621    disableSROA(CostIt);
622  }
623
624  return false;
625}
626
627bool CallAnalyzer::visitStore(StoreInst &I) {
628  Value *SROAArg;
629  DenseMap<Value *, int>::iterator CostIt;
630  if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
631    if (I.isSimple()) {
632      accumulateSROACost(CostIt, InlineConstants::InstrCost);
633      return true;
634    }
635
636    disableSROA(CostIt);
637  }
638
639  return false;
640}
641
642bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) {
643  // Constant folding for extract value is trivial.
644  Constant *C = dyn_cast<Constant>(I.getAggregateOperand());
645  if (!C)
646    C = SimplifiedValues.lookup(I.getAggregateOperand());
647  if (C) {
648    SimplifiedValues[&I] = ConstantExpr::getExtractValue(C, I.getIndices());
649    return true;
650  }
651
652  // SROA can look through these but give them a cost.
653  return false;
654}
655
656bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
657  // Constant folding for insert value is trivial.
658  Constant *AggC = dyn_cast<Constant>(I.getAggregateOperand());
659  if (!AggC)
660    AggC = SimplifiedValues.lookup(I.getAggregateOperand());
661  Constant *InsertedC = dyn_cast<Constant>(I.getInsertedValueOperand());
662  if (!InsertedC)
663    InsertedC = SimplifiedValues.lookup(I.getInsertedValueOperand());
664  if (AggC && InsertedC) {
665    SimplifiedValues[&I] = ConstantExpr::getInsertValue(AggC, InsertedC,
666                                                        I.getIndices());
667    return true;
668  }
669
670  // SROA can look through these but give them a cost.
671  return false;
672}
673
674/// \brief Try to simplify a call site.
675///
676/// Takes a concrete function and callsite and tries to actually simplify it by
677/// analyzing the arguments and call itself with instsimplify. Returns true if
678/// it has simplified the callsite to some other entity (a constant), making it
679/// free.
680bool CallAnalyzer::simplifyCallSite(Function *F, CallSite CS) {
681  // FIXME: Using the instsimplify logic directly for this is inefficient
682  // because we have to continually rebuild the argument list even when no
683  // simplifications can be performed. Until that is fixed with remapping
684  // inside of instsimplify, directly constant fold calls here.
685  if (!canConstantFoldCallTo(F))
686    return false;
687
688  // Try to re-map the arguments to constants.
689  SmallVector<Constant *, 4> ConstantArgs;
690  ConstantArgs.reserve(CS.arg_size());
691  for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
692       I != E; ++I) {
693    Constant *C = dyn_cast<Constant>(*I);
694    if (!C)
695      C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(*I));
696    if (!C)
697      return false; // This argument doesn't map to a constant.
698
699    ConstantArgs.push_back(C);
700  }
701  if (Constant *C = ConstantFoldCall(F, ConstantArgs)) {
702    SimplifiedValues[CS.getInstruction()] = C;
703    return true;
704  }
705
706  return false;
707}
708
709bool CallAnalyzer::visitCallSite(CallSite CS) {
710  if (CS.hasFnAttr(Attribute::ReturnsTwice) &&
711      !F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
712                                      Attribute::ReturnsTwice)) {
713    // This aborts the entire analysis.
714    ExposesReturnsTwice = true;
715    return false;
716  }
717  if (CS.isCall() &&
718      cast<CallInst>(CS.getInstruction())->cannotDuplicate())
719    ContainsNoDuplicateCall = true;
720
721  if (Function *F = CS.getCalledFunction()) {
722    // When we have a concrete function, first try to simplify it directly.
723    if (simplifyCallSite(F, CS))
724      return true;
725
726    // Next check if it is an intrinsic we know about.
727    // FIXME: Lift this into part of the InstVisitor.
728    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
729      switch (II->getIntrinsicID()) {
730      default:
731        return Base::visitCallSite(CS);
732
733      case Intrinsic::memset:
734      case Intrinsic::memcpy:
735      case Intrinsic::memmove:
736        // SROA can usually chew through these intrinsics, but they aren't free.
737        return false;
738      }
739    }
740
741    if (F == CS.getInstruction()->getParent()->getParent()) {
742      // This flag will fully abort the analysis, so don't bother with anything
743      // else.
744      IsRecursiveCall = true;
745      return false;
746    }
747
748    if (TTI.isLoweredToCall(F)) {
749      // We account for the average 1 instruction per call argument setup
750      // here.
751      Cost += CS.arg_size() * InlineConstants::InstrCost;
752
753      // Everything other than inline ASM will also have a significant cost
754      // merely from making the call.
755      if (!isa<InlineAsm>(CS.getCalledValue()))
756        Cost += InlineConstants::CallPenalty;
757    }
758
759    return Base::visitCallSite(CS);
760  }
761
762  // Otherwise we're in a very special case -- an indirect function call. See
763  // if we can be particularly clever about this.
764  Value *Callee = CS.getCalledValue();
765
766  // First, pay the price of the argument setup. We account for the average
767  // 1 instruction per call argument setup here.
768  Cost += CS.arg_size() * InlineConstants::InstrCost;
769
770  // Next, check if this happens to be an indirect function call to a known
771  // function in this inline context. If not, we've done all we can.
772  Function *F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
773  if (!F)
774    return Base::visitCallSite(CS);
775
776  // If we have a constant that we are calling as a function, we can peer
777  // through it and see the function target. This happens not infrequently
778  // during devirtualization and so we want to give it a hefty bonus for
779  // inlining, but cap that bonus in the event that inlining wouldn't pan
780  // out. Pretend to inline the function, with a custom threshold.
781  CallAnalyzer CA(DL, TTI, *F, InlineConstants::IndirectCallThreshold);
782  if (CA.analyzeCall(CS)) {
783    // We were able to inline the indirect call! Subtract the cost from the
784    // bonus we want to apply, but don't go below zero.
785    Cost -= std::max(0, InlineConstants::IndirectCallThreshold - CA.getCost());
786  }
787
788  return Base::visitCallSite(CS);
789}
790
791bool CallAnalyzer::visitReturnInst(ReturnInst &RI) {
792  // At least one return instruction will be free after inlining.
793  bool Free = !HasReturn;
794  HasReturn = true;
795  return Free;
796}
797
798bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
799  // We model unconditional branches as essentially free -- they really
800  // shouldn't exist at all, but handling them makes the behavior of the
801  // inliner more regular and predictable. Interestingly, conditional branches
802  // which will fold away are also free.
803  return BI.isUnconditional() || isa<ConstantInt>(BI.getCondition()) ||
804         dyn_cast_or_null<ConstantInt>(
805             SimplifiedValues.lookup(BI.getCondition()));
806}
807
808bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
809  // We model unconditional switches as free, see the comments on handling
810  // branches.
811  if (isa<ConstantInt>(SI.getCondition()))
812    return true;
813  if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
814    if (isa<ConstantInt>(V))
815      return true;
816
817  // Otherwise, we need to accumulate a cost proportional to the number of
818  // distinct successor blocks. This fan-out in the CFG cannot be represented
819  // for free even if we can represent the core switch as a jumptable that
820  // takes a single instruction.
821  //
822  // NB: We convert large switches which are just used to initialize large phi
823  // nodes to lookup tables instead in simplify-cfg, so this shouldn't prevent
824  // inlining those. It will prevent inlining in cases where the optimization
825  // does not (yet) fire.
826  SmallPtrSet<BasicBlock *, 8> SuccessorBlocks;
827  SuccessorBlocks.insert(SI.getDefaultDest());
828  for (auto I = SI.case_begin(), E = SI.case_end(); I != E; ++I)
829    SuccessorBlocks.insert(I.getCaseSuccessor());
830  // Add cost corresponding to the number of distinct destinations. The first
831  // we model as free because of fallthrough.
832  Cost += (SuccessorBlocks.size() - 1) * InlineConstants::InstrCost;
833  return false;
834}
835
836bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
837  // We never want to inline functions that contain an indirectbr.  This is
838  // incorrect because all the blockaddress's (in static global initializers
839  // for example) would be referring to the original function, and this
840  // indirect jump would jump from the inlined copy of the function into the
841  // original function which is extremely undefined behavior.
842  // FIXME: This logic isn't really right; we can safely inline functions with
843  // indirectbr's as long as no other function or global references the
844  // blockaddress of a block within the current function.
845  HasIndirectBr = true;
846  return false;
847}
848
849bool CallAnalyzer::visitResumeInst(ResumeInst &RI) {
850  // FIXME: It's not clear that a single instruction is an accurate model for
851  // the inline cost of a resume instruction.
852  return false;
853}
854
855bool CallAnalyzer::visitUnreachableInst(UnreachableInst &I) {
856  // FIXME: It might be reasonably to discount the cost of instructions leading
857  // to unreachable as they have the lowest possible impact on both runtime and
858  // code size.
859  return true; // No actual code is needed for unreachable.
860}
861
862bool CallAnalyzer::visitInstruction(Instruction &I) {
863  // Some instructions are free. All of the free intrinsics can also be
864  // handled by SROA, etc.
865  if (TargetTransformInfo::TCC_Free == TTI.getUserCost(&I))
866    return true;
867
868  // We found something we don't understand or can't handle. Mark any SROA-able
869  // values in the operand list as no longer viable.
870  for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI)
871    disableSROA(*OI);
872
873  return false;
874}
875
876
877/// \brief Analyze a basic block for its contribution to the inline cost.
878///
879/// This method walks the analyzer over every instruction in the given basic
880/// block and accounts for their cost during inlining at this callsite. It
881/// aborts early if the threshold has been exceeded or an impossible to inline
882/// construct has been detected. It returns false if inlining is no longer
883/// viable, and true if inlining remains viable.
884bool CallAnalyzer::analyzeBlock(BasicBlock *BB) {
885  for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
886    // FIXME: Currently, the number of instructions in a function regardless of
887    // our ability to simplify them during inline to constants or dead code,
888    // are actually used by the vector bonus heuristic. As long as that's true,
889    // we have to special case debug intrinsics here to prevent differences in
890    // inlining due to debug symbols. Eventually, the number of unsimplified
891    // instructions shouldn't factor into the cost computation, but until then,
892    // hack around it here.
893    if (isa<DbgInfoIntrinsic>(I))
894      continue;
895
896    ++NumInstructions;
897    if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
898      ++NumVectorInstructions;
899
900    // If the instruction simplified to a constant, there is no cost to this
901    // instruction. Visit the instructions using our InstVisitor to account for
902    // all of the per-instruction logic. The visit tree returns true if we
903    // consumed the instruction in any way, and false if the instruction's base
904    // cost should count against inlining.
905    if (Base::visit(I))
906      ++NumInstructionsSimplified;
907    else
908      Cost += InlineConstants::InstrCost;
909
910    // If the visit this instruction detected an uninlinable pattern, abort.
911    if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
912        HasIndirectBr)
913      return false;
914
915    // If the caller is a recursive function then we don't want to inline
916    // functions which allocate a lot of stack space because it would increase
917    // the caller stack usage dramatically.
918    if (IsCallerRecursive &&
919        AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
920      return false;
921
922    if (NumVectorInstructions > NumInstructions/2)
923      VectorBonus = FiftyPercentVectorBonus;
924    else if (NumVectorInstructions > NumInstructions/10)
925      VectorBonus = TenPercentVectorBonus;
926    else
927      VectorBonus = 0;
928
929    // Check if we've past the threshold so we don't spin in huge basic
930    // blocks that will never inline.
931    if (Cost > (Threshold + VectorBonus))
932      return false;
933  }
934
935  return true;
936}
937
938/// \brief Compute the base pointer and cumulative constant offsets for V.
939///
940/// This strips all constant offsets off of V, leaving it the base pointer, and
941/// accumulates the total constant offset applied in the returned constant. It
942/// returns 0 if V is not a pointer, and returns the constant '0' if there are
943/// no constant offsets applied.
944ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
945  if (!DL || !V->getType()->isPointerTy())
946    return nullptr;
947
948  unsigned IntPtrWidth = DL->getPointerSizeInBits();
949  APInt Offset = APInt::getNullValue(IntPtrWidth);
950
951  // Even though we don't look through PHI nodes, we could be called on an
952  // instruction in an unreachable block, which may be on a cycle.
953  SmallPtrSet<Value *, 4> Visited;
954  Visited.insert(V);
955  do {
956    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
957      if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
958        return nullptr;
959      V = GEP->getPointerOperand();
960    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
961      V = cast<Operator>(V)->getOperand(0);
962    } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
963      if (GA->mayBeOverridden())
964        break;
965      V = GA->getAliasee();
966    } else {
967      break;
968    }
969    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
970  } while (Visited.insert(V));
971
972  Type *IntPtrTy = DL->getIntPtrType(V->getContext());
973  return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
974}
975
976/// \brief Analyze a call site for potential inlining.
977///
978/// Returns true if inlining this call is viable, and false if it is not
979/// viable. It computes the cost and adjusts the threshold based on numerous
980/// factors and heuristics. If this method returns false but the computed cost
981/// is below the computed threshold, then inlining was forcibly disabled by
982/// some artifact of the routine.
983bool CallAnalyzer::analyzeCall(CallSite CS) {
984  ++NumCallsAnalyzed;
985
986  // Track whether the post-inlining function would have more than one basic
987  // block. A single basic block is often intended for inlining. Balloon the
988  // threshold by 50% until we pass the single-BB phase.
989  bool SingleBB = true;
990  int SingleBBBonus = Threshold / 2;
991  Threshold += SingleBBBonus;
992
993  // Perform some tweaks to the cost and threshold based on the direct
994  // callsite information.
995
996  // We want to more aggressively inline vector-dense kernels, so up the
997  // threshold, and we'll lower it if the % of vector instructions gets too
998  // low.
999  assert(NumInstructions == 0);
1000  assert(NumVectorInstructions == 0);
1001  FiftyPercentVectorBonus = Threshold;
1002  TenPercentVectorBonus = Threshold / 2;
1003
1004  // Give out bonuses per argument, as the instructions setting them up will
1005  // be gone after inlining.
1006  for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) {
1007    if (DL && CS.isByValArgument(I)) {
1008      // We approximate the number of loads and stores needed by dividing the
1009      // size of the byval type by the target's pointer size.
1010      PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
1011      unsigned TypeSize = DL->getTypeSizeInBits(PTy->getElementType());
1012      unsigned PointerSize = DL->getPointerSizeInBits();
1013      // Ceiling division.
1014      unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
1015
1016      // If it generates more than 8 stores it is likely to be expanded as an
1017      // inline memcpy so we take that as an upper bound. Otherwise we assume
1018      // one load and one store per word copied.
1019      // FIXME: The maxStoresPerMemcpy setting from the target should be used
1020      // here instead of a magic number of 8, but it's not available via
1021      // DataLayout.
1022      NumStores = std::min(NumStores, 8U);
1023
1024      Cost -= 2 * NumStores * InlineConstants::InstrCost;
1025    } else {
1026      // For non-byval arguments subtract off one instruction per call
1027      // argument.
1028      Cost -= InlineConstants::InstrCost;
1029    }
1030  }
1031
1032  // If there is only one call of the function, and it has internal linkage,
1033  // the cost of inlining it drops dramatically.
1034  bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
1035    &F == CS.getCalledFunction();
1036  if (OnlyOneCallAndLocalLinkage)
1037    Cost += InlineConstants::LastCallToStaticBonus;
1038
1039  // If the instruction after the call, or if the normal destination of the
1040  // invoke is an unreachable instruction, the function is noreturn. As such,
1041  // there is little point in inlining this unless there is literally zero
1042  // cost.
1043  Instruction *Instr = CS.getInstruction();
1044  if (InvokeInst *II = dyn_cast<InvokeInst>(Instr)) {
1045    if (isa<UnreachableInst>(II->getNormalDest()->begin()))
1046      Threshold = 1;
1047  } else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
1048    Threshold = 1;
1049
1050  // If this function uses the coldcc calling convention, prefer not to inline
1051  // it.
1052  if (F.getCallingConv() == CallingConv::Cold)
1053    Cost += InlineConstants::ColdccPenalty;
1054
1055  // Check if we're done. This can happen due to bonuses and penalties.
1056  if (Cost > Threshold)
1057    return false;
1058
1059  if (F.empty())
1060    return true;
1061
1062  Function *Caller = CS.getInstruction()->getParent()->getParent();
1063  // Check if the caller function is recursive itself.
1064  for (User *U : Caller->users()) {
1065    CallSite Site(U);
1066    if (!Site)
1067      continue;
1068    Instruction *I = Site.getInstruction();
1069    if (I->getParent()->getParent() == Caller) {
1070      IsCallerRecursive = true;
1071      break;
1072    }
1073  }
1074
1075  // Populate our simplified values by mapping from function arguments to call
1076  // arguments with known important simplifications.
1077  CallSite::arg_iterator CAI = CS.arg_begin();
1078  for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
1079       FAI != FAE; ++FAI, ++CAI) {
1080    assert(CAI != CS.arg_end());
1081    if (Constant *C = dyn_cast<Constant>(CAI))
1082      SimplifiedValues[FAI] = C;
1083
1084    Value *PtrArg = *CAI;
1085    if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
1086      ConstantOffsetPtrs[FAI] = std::make_pair(PtrArg, C->getValue());
1087
1088      // We can SROA any pointer arguments derived from alloca instructions.
1089      if (isa<AllocaInst>(PtrArg)) {
1090        SROAArgValues[FAI] = PtrArg;
1091        SROAArgCosts[PtrArg] = 0;
1092      }
1093    }
1094  }
1095  NumConstantArgs = SimplifiedValues.size();
1096  NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
1097  NumAllocaArgs = SROAArgValues.size();
1098
1099  // The worklist of live basic blocks in the callee *after* inlining. We avoid
1100  // adding basic blocks of the callee which can be proven to be dead for this
1101  // particular call site in order to get more accurate cost estimates. This
1102  // requires a somewhat heavyweight iteration pattern: we need to walk the
1103  // basic blocks in a breadth-first order as we insert live successors. To
1104  // accomplish this, prioritizing for small iterations because we exit after
1105  // crossing our threshold, we use a small-size optimized SetVector.
1106  typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
1107                                  SmallPtrSet<BasicBlock *, 16> > BBSetVector;
1108  BBSetVector BBWorklist;
1109  BBWorklist.insert(&F.getEntryBlock());
1110  // Note that we *must not* cache the size, this loop grows the worklist.
1111  for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
1112    // Bail out the moment we cross the threshold. This means we'll under-count
1113    // the cost, but only when undercounting doesn't matter.
1114    if (Cost > (Threshold + VectorBonus))
1115      break;
1116
1117    BasicBlock *BB = BBWorklist[Idx];
1118    if (BB->empty())
1119      continue;
1120
1121    // Disallow inlining a blockaddress. A blockaddress only has defined
1122    // behavior for an indirect branch in the same function, and we do not
1123    // currently support inlining indirect branches. But, the inliner may not
1124    // see an indirect branch that ends up being dead code at a particular call
1125    // site. If the blockaddress escapes the function, e.g., via a global
1126    // variable, inlining may lead to an invalid cross-function reference.
1127    if (BB->hasAddressTaken())
1128      return false;
1129
1130    // Analyze the cost of this block. If we blow through the threshold, this
1131    // returns false, and we can bail on out.
1132    if (!analyzeBlock(BB)) {
1133      if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
1134          HasIndirectBr)
1135        return false;
1136
1137      // If the caller is a recursive function then we don't want to inline
1138      // functions which allocate a lot of stack space because it would increase
1139      // the caller stack usage dramatically.
1140      if (IsCallerRecursive &&
1141          AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
1142        return false;
1143
1144      break;
1145    }
1146
1147    TerminatorInst *TI = BB->getTerminator();
1148
1149    // Add in the live successors by first checking whether we have terminator
1150    // that may be simplified based on the values simplified by this call.
1151    if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
1152      if (BI->isConditional()) {
1153        Value *Cond = BI->getCondition();
1154        if (ConstantInt *SimpleCond
1155              = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
1156          BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
1157          continue;
1158        }
1159      }
1160    } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
1161      Value *Cond = SI->getCondition();
1162      if (ConstantInt *SimpleCond
1163            = dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
1164        BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
1165        continue;
1166      }
1167    }
1168
1169    // If we're unable to select a particular successor, just count all of
1170    // them.
1171    for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
1172         ++TIdx)
1173      BBWorklist.insert(TI->getSuccessor(TIdx));
1174
1175    // If we had any successors at this point, than post-inlining is likely to
1176    // have them as well. Note that we assume any basic blocks which existed
1177    // due to branches or switches which folded above will also fold after
1178    // inlining.
1179    if (SingleBB && TI->getNumSuccessors() > 1) {
1180      // Take off the bonus we applied to the threshold.
1181      Threshold -= SingleBBBonus;
1182      SingleBB = false;
1183    }
1184  }
1185
1186  // If this is a noduplicate call, we can still inline as long as
1187  // inlining this would cause the removal of the caller (so the instruction
1188  // is not actually duplicated, just moved).
1189  if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
1190    return false;
1191
1192  Threshold += VectorBonus;
1193
1194  return Cost < Threshold;
1195}
1196
1197#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1198/// \brief Dump stats about this call's analysis.
1199void CallAnalyzer::dump() {
1200#define DEBUG_PRINT_STAT(x) dbgs() << "      " #x ": " << x << "\n"
1201  DEBUG_PRINT_STAT(NumConstantArgs);
1202  DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
1203  DEBUG_PRINT_STAT(NumAllocaArgs);
1204  DEBUG_PRINT_STAT(NumConstantPtrCmps);
1205  DEBUG_PRINT_STAT(NumConstantPtrDiffs);
1206  DEBUG_PRINT_STAT(NumInstructionsSimplified);
1207  DEBUG_PRINT_STAT(SROACostSavings);
1208  DEBUG_PRINT_STAT(SROACostSavingsLost);
1209  DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
1210  DEBUG_PRINT_STAT(Cost);
1211  DEBUG_PRINT_STAT(Threshold);
1212  DEBUG_PRINT_STAT(VectorBonus);
1213#undef DEBUG_PRINT_STAT
1214}
1215#endif
1216
1217INITIALIZE_PASS_BEGIN(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis",
1218                      true, true)
1219INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
1220INITIALIZE_PASS_END(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis",
1221                    true, true)
1222
1223char InlineCostAnalysis::ID = 0;
1224
1225InlineCostAnalysis::InlineCostAnalysis() : CallGraphSCCPass(ID) {}
1226
1227InlineCostAnalysis::~InlineCostAnalysis() {}
1228
1229void InlineCostAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
1230  AU.setPreservesAll();
1231  AU.addRequired<TargetTransformInfo>();
1232  CallGraphSCCPass::getAnalysisUsage(AU);
1233}
1234
1235bool InlineCostAnalysis::runOnSCC(CallGraphSCC &SCC) {
1236  TTI = &getAnalysis<TargetTransformInfo>();
1237  return false;
1238}
1239
1240InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, int Threshold) {
1241  return getInlineCost(CS, CS.getCalledFunction(), Threshold);
1242}
1243
1244/// \brief Test that two functions either have or have not the given attribute
1245///        at the same time.
1246static bool attributeMatches(Function *F1, Function *F2,
1247                             Attribute::AttrKind Attr) {
1248  return F1->hasFnAttribute(Attr) == F2->hasFnAttribute(Attr);
1249}
1250
1251/// \brief Test that there are no attribute conflicts between Caller and Callee
1252///        that prevent inlining.
1253static bool functionsHaveCompatibleAttributes(Function *Caller,
1254                                              Function *Callee) {
1255  return attributeMatches(Caller, Callee, Attribute::SanitizeAddress) &&
1256         attributeMatches(Caller, Callee, Attribute::SanitizeMemory) &&
1257         attributeMatches(Caller, Callee, Attribute::SanitizeThread);
1258}
1259
1260InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, Function *Callee,
1261                                             int Threshold) {
1262  // Cannot inline indirect calls.
1263  if (!Callee)
1264    return llvm::InlineCost::getNever();
1265
1266  // Calls to functions with always-inline attributes should be inlined
1267  // whenever possible.
1268  if (CS.hasFnAttr(Attribute::AlwaysInline)) {
1269    if (isInlineViable(*Callee))
1270      return llvm::InlineCost::getAlways();
1271    return llvm::InlineCost::getNever();
1272  }
1273
1274  // Never inline functions with conflicting attributes (unless callee has
1275  // always-inline attribute).
1276  if (!functionsHaveCompatibleAttributes(CS.getCaller(), Callee))
1277    return llvm::InlineCost::getNever();
1278
1279  // Don't inline this call if the caller has the optnone attribute.
1280  if (CS.getCaller()->hasFnAttribute(Attribute::OptimizeNone))
1281    return llvm::InlineCost::getNever();
1282
1283  // Don't inline functions which can be redefined at link-time to mean
1284  // something else.  Don't inline functions marked noinline or call sites
1285  // marked noinline.
1286  if (Callee->mayBeOverridden() ||
1287      Callee->hasFnAttribute(Attribute::NoInline) || CS.isNoInline())
1288    return llvm::InlineCost::getNever();
1289
1290  DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
1291        << "...\n");
1292
1293  CallAnalyzer CA(Callee->getDataLayout(), *TTI, *Callee, Threshold);
1294  bool ShouldInline = CA.analyzeCall(CS);
1295
1296  DEBUG(CA.dump());
1297
1298  // Check if there was a reason to force inlining or no inlining.
1299  if (!ShouldInline && CA.getCost() < CA.getThreshold())
1300    return InlineCost::getNever();
1301  if (ShouldInline && CA.getCost() >= CA.getThreshold())
1302    return InlineCost::getAlways();
1303
1304  return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
1305}
1306
1307bool InlineCostAnalysis::isInlineViable(Function &F) {
1308  bool ReturnsTwice =
1309    F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1310                                   Attribute::ReturnsTwice);
1311  for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
1312    // Disallow inlining of functions which contain indirect branches or
1313    // blockaddresses.
1314    if (isa<IndirectBrInst>(BI->getTerminator()) || BI->hasAddressTaken())
1315      return false;
1316
1317    for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;
1318         ++II) {
1319      CallSite CS(II);
1320      if (!CS)
1321        continue;
1322
1323      // Disallow recursive calls.
1324      if (&F == CS.getCalledFunction())
1325        return false;
1326
1327      // Disallow calls which expose returns-twice to a function not previously
1328      // attributed as such.
1329      if (!ReturnsTwice && CS.isCall() &&
1330          cast<CallInst>(CS.getInstruction())->canReturnTwice())
1331        return false;
1332    }
1333  }
1334
1335  return true;
1336}
1337