LLVM  3.7.0
CFLAliasAnalysis.cpp
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1 //===- CFLAliasAnalysis.cpp - CFL-Based Alias Analysis Implementation ------==//
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 a CFL-based context-insensitive alias analysis
11 // algorithm. It does not depend on types. The algorithm is a mixture of the one
12 // described in "Demand-driven alias analysis for C" by Xin Zheng and Radu
13 // Rugina, and "Fast algorithms for Dyck-CFL-reachability with applications to
14 // Alias Analysis" by Zhang Q, Lyu M R, Yuan H, and Su Z. -- to summarize the
15 // papers, we build a graph of the uses of a variable, where each node is a
16 // memory location, and each edge is an action that happened on that memory
17 // location. The "actions" can be one of Dereference, Reference, or Assign.
18 //
19 // Two variables are considered as aliasing iff you can reach one value's node
20 // from the other value's node and the language formed by concatenating all of
21 // the edge labels (actions) conforms to a context-free grammar.
22 //
23 // Because this algorithm requires a graph search on each query, we execute the
24 // algorithm outlined in "Fast algorithms..." (mentioned above)
25 // in order to transform the graph into sets of variables that may alias in
26 // ~nlogn time (n = number of variables.), which makes queries take constant
27 // time.
28 //===----------------------------------------------------------------------===//
29 
30 #include "StratifiedSets.h"
31 #include "llvm/ADT/BitVector.h"
32 #include "llvm/ADT/DenseMap.h"
33 #include "llvm/ADT/None.h"
34 #include "llvm/ADT/Optional.h"
36 #include "llvm/Analysis/Passes.h"
37 #include "llvm/IR/Constants.h"
38 #include "llvm/IR/Function.h"
39 #include "llvm/IR/InstVisitor.h"
40 #include "llvm/IR/Instructions.h"
41 #include "llvm/IR/ValueHandle.h"
42 #include "llvm/Pass.h"
43 #include "llvm/Support/Allocator.h"
44 #include "llvm/Support/Compiler.h"
45 #include "llvm/Support/Debug.h"
48 #include <algorithm>
49 #include <cassert>
50 #include <forward_list>
51 #include <memory>
52 #include <tuple>
53 
54 using namespace llvm;
55 
56 #define DEBUG_TYPE "cfl-aa"
57 
58 // Try to go from a Value* to a Function*. Never returns nullptr.
60 
61 // Returns possible functions called by the Inst* into the given
62 // SmallVectorImpl. Returns true if targets found, false otherwise.
63 // This is templated because InvokeInst/CallInst give us the same
64 // set of functions that we care about, and I don't like repeating
65 // myself.
66 template <typename Inst>
67 static bool getPossibleTargets(Inst *, SmallVectorImpl<Function *> &);
68 
69 // Some instructions need to have their users tracked. Instructions like
70 // `add` require you to get the users of the Instruction* itself, other
71 // instructions like `store` require you to get the users of the first
72 // operand. This function gets the "proper" value to track for each
73 // type of instruction we support.
75 
76 // There are certain instructions (i.e. FenceInst, etc.) that we ignore.
77 // This notes that we should ignore those.
78 static bool hasUsefulEdges(Instruction *);
79 
81  std::numeric_limits<StratifiedIndex>::max();
82 
83 namespace {
84 // StratifiedInfo Attribute things.
85 typedef unsigned StratifiedAttr;
86 LLVM_CONSTEXPR unsigned MaxStratifiedAttrIndex = NumStratifiedAttrs;
87 LLVM_CONSTEXPR unsigned AttrAllIndex = 0;
88 LLVM_CONSTEXPR unsigned AttrGlobalIndex = 1;
89 LLVM_CONSTEXPR unsigned AttrUnknownIndex = 2;
90 LLVM_CONSTEXPR unsigned AttrFirstArgIndex = 3;
91 LLVM_CONSTEXPR unsigned AttrLastArgIndex = MaxStratifiedAttrIndex;
92 LLVM_CONSTEXPR unsigned AttrMaxNumArgs = AttrLastArgIndex - AttrFirstArgIndex;
93 
94 LLVM_CONSTEXPR StratifiedAttr AttrNone = 0;
95 LLVM_CONSTEXPR StratifiedAttr AttrUnknown = 1 << AttrUnknownIndex;
96 LLVM_CONSTEXPR StratifiedAttr AttrAll = ~AttrNone;
97 
98 // \brief StratifiedSets call for knowledge of "direction", so this is how we
99 // represent that locally.
100 enum class Level { Same, Above, Below };
101 
102 // \brief Edges can be one of four "weights" -- each weight must have an inverse
103 // weight (Assign has Assign; Reference has Dereference).
104 enum class EdgeType {
105  // The weight assigned when assigning from or to a value. For example, in:
106  // %b = getelementptr %a, 0
107  // ...The relationships are %b assign %a, and %a assign %b. This used to be
108  // two edges, but having a distinction bought us nothing.
109  Assign,
110 
111  // The edge used when we have an edge going from some handle to a Value.
112  // Examples of this include:
113  // %b = load %a (%b Dereference %a)
114  // %b = extractelement %a, 0 (%a Dereference %b)
115  Dereference,
116 
117  // The edge used when our edge goes from a value to a handle that may have
118  // contained it at some point. Examples:
119  // %b = load %a (%a Reference %b)
120  // %b = extractelement %a, 0 (%b Reference %a)
121  Reference
122 };
123 
124 // \brief Encodes the notion of a "use"
125 struct Edge {
126  // \brief Which value the edge is coming from
127  Value *From;
128 
129  // \brief Which value the edge is pointing to
130  Value *To;
131 
132  // \brief Edge weight
133  EdgeType Weight;
134 
135  // \brief Whether we aliased any external values along the way that may be
136  // invisible to the analysis (i.e. landingpad for exceptions, calls for
137  // interprocedural analysis, etc.)
138  StratifiedAttrs AdditionalAttrs;
139 
140  Edge(Value *From, Value *To, EdgeType W, StratifiedAttrs A)
141  : From(From), To(To), Weight(W), AdditionalAttrs(A) {}
142 };
143 
144 // \brief Information we have about a function and would like to keep around
145 struct FunctionInfo {
147  // Lots of functions have < 4 returns. Adjust as necessary.
148  SmallVector<Value *, 4> ReturnedValues;
149 
150  FunctionInfo(StratifiedSets<Value *> &&S, SmallVector<Value *, 4> &&RV)
151  : Sets(std::move(S)), ReturnedValues(std::move(RV)) {}
152 };
153 
154 struct CFLAliasAnalysis;
155 
156 struct FunctionHandle : public CallbackVH {
157  FunctionHandle(Function *Fn, CFLAliasAnalysis *CFLAA)
158  : CallbackVH(Fn), CFLAA(CFLAA) {
159  assert(Fn != nullptr);
160  assert(CFLAA != nullptr);
161  }
162 
163  ~FunctionHandle() override {}
164 
165  void deleted() override { removeSelfFromCache(); }
166  void allUsesReplacedWith(Value *) override { removeSelfFromCache(); }
167 
168 private:
169  CFLAliasAnalysis *CFLAA;
170 
171  void removeSelfFromCache();
172 };
173 
174 struct CFLAliasAnalysis : public ImmutablePass, public AliasAnalysis {
175 private:
176  /// \brief Cached mapping of Functions to their StratifiedSets.
177  /// If a function's sets are currently being built, it is marked
178  /// in the cache as an Optional without a value. This way, if we
179  /// have any kind of recursion, it is discernable from a function
180  /// that simply has empty sets.
182  std::forward_list<FunctionHandle> Handles;
183 
184 public:
185  static char ID;
186 
187  CFLAliasAnalysis() : ImmutablePass(ID) {
189  }
190 
191  ~CFLAliasAnalysis() override {}
192 
193  void getAnalysisUsage(AnalysisUsage &AU) const override {
195  }
196 
197  void *getAdjustedAnalysisPointer(const void *ID) override {
198  if (ID == &AliasAnalysis::ID)
199  return (AliasAnalysis *)this;
200  return this;
201  }
202 
203  /// \brief Inserts the given Function into the cache.
204  void scan(Function *Fn);
205 
206  void evict(Function *Fn) { Cache.erase(Fn); }
207 
208  /// \brief Ensures that the given function is available in the cache.
209  /// Returns the appropriate entry from the cache.
210  const Optional<FunctionInfo> &ensureCached(Function *Fn) {
211  auto Iter = Cache.find(Fn);
212  if (Iter == Cache.end()) {
213  scan(Fn);
214  Iter = Cache.find(Fn);
215  assert(Iter != Cache.end());
216  assert(Iter->second.hasValue());
217  }
218  return Iter->second;
219  }
220 
221  AliasResult query(const MemoryLocation &LocA, const MemoryLocation &LocB);
222 
223  AliasResult alias(const MemoryLocation &LocA,
224  const MemoryLocation &LocB) override {
225  if (LocA.Ptr == LocB.Ptr) {
226  if (LocA.Size == LocB.Size) {
227  return MustAlias;
228  } else {
229  return PartialAlias;
230  }
231  }
232 
233  // Comparisons between global variables and other constants should be
234  // handled by BasicAA.
235  // TODO: ConstantExpr handling -- CFLAA may report NoAlias when comparing
236  // a GlobalValue and ConstantExpr, but every query needs to have at least
237  // one Value tied to a Function, and neither GlobalValues nor ConstantExprs
238  // are.
239  if (isa<Constant>(LocA.Ptr) && isa<Constant>(LocB.Ptr)) {
240  return AliasAnalysis::alias(LocA, LocB);
241  }
242 
243  AliasResult QueryResult = query(LocA, LocB);
244  if (QueryResult == MayAlias)
245  return AliasAnalysis::alias(LocA, LocB);
246 
247  return QueryResult;
248  }
249 
250  bool doInitialization(Module &M) override;
251 };
252 
253 void FunctionHandle::removeSelfFromCache() {
254  assert(CFLAA != nullptr);
255  auto *Val = getValPtr();
256  CFLAA->evict(cast<Function>(Val));
257  setValPtr(nullptr);
258 }
259 
260 // \brief Gets the edges our graph should have, based on an Instruction*
261 class GetEdgesVisitor : public InstVisitor<GetEdgesVisitor, void> {
262  CFLAliasAnalysis &AA;
263  SmallVectorImpl<Edge> &Output;
264 
265 public:
266  GetEdgesVisitor(CFLAliasAnalysis &AA, SmallVectorImpl<Edge> &Output)
267  : AA(AA), Output(Output) {}
268 
269  void visitInstruction(Instruction &) {
270  llvm_unreachable("Unsupported instruction encountered");
271  }
272 
273  void visitPtrToIntInst(PtrToIntInst &Inst) {
274  auto *Ptr = Inst.getOperand(0);
275  Output.push_back(Edge(Ptr, Ptr, EdgeType::Assign, AttrUnknown));
276  }
277 
278  void visitIntToPtrInst(IntToPtrInst &Inst) {
279  auto *Ptr = &Inst;
280  Output.push_back(Edge(Ptr, Ptr, EdgeType::Assign, AttrUnknown));
281  }
282 
283  void visitCastInst(CastInst &Inst) {
284  Output.push_back(
285  Edge(&Inst, Inst.getOperand(0), EdgeType::Assign, AttrNone));
286  }
287 
288  void visitBinaryOperator(BinaryOperator &Inst) {
289  auto *Op1 = Inst.getOperand(0);
290  auto *Op2 = Inst.getOperand(1);
291  Output.push_back(Edge(&Inst, Op1, EdgeType::Assign, AttrNone));
292  Output.push_back(Edge(&Inst, Op2, EdgeType::Assign, AttrNone));
293  }
294 
295  void visitAtomicCmpXchgInst(AtomicCmpXchgInst &Inst) {
296  auto *Ptr = Inst.getPointerOperand();
297  auto *Val = Inst.getNewValOperand();
298  Output.push_back(Edge(Ptr, Val, EdgeType::Dereference, AttrNone));
299  }
300 
301  void visitAtomicRMWInst(AtomicRMWInst &Inst) {
302  auto *Ptr = Inst.getPointerOperand();
303  auto *Val = Inst.getValOperand();
304  Output.push_back(Edge(Ptr, Val, EdgeType::Dereference, AttrNone));
305  }
306 
307  void visitPHINode(PHINode &Inst) {
308  for (Value *Val : Inst.incoming_values()) {
309  Output.push_back(Edge(&Inst, Val, EdgeType::Assign, AttrNone));
310  }
311  }
312 
313  void visitGetElementPtrInst(GetElementPtrInst &Inst) {
314  auto *Op = Inst.getPointerOperand();
315  Output.push_back(Edge(&Inst, Op, EdgeType::Assign, AttrNone));
316  for (auto I = Inst.idx_begin(), E = Inst.idx_end(); I != E; ++I)
317  Output.push_back(Edge(&Inst, *I, EdgeType::Assign, AttrNone));
318  }
319 
320  void visitSelectInst(SelectInst &Inst) {
321  // Condition is not processed here (The actual statement producing
322  // the condition result is processed elsewhere). For select, the
323  // condition is evaluated, but not loaded, stored, or assigned
324  // simply as a result of being the condition of a select.
325 
326  auto *TrueVal = Inst.getTrueValue();
327  Output.push_back(Edge(&Inst, TrueVal, EdgeType::Assign, AttrNone));
328  auto *FalseVal = Inst.getFalseValue();
329  Output.push_back(Edge(&Inst, FalseVal, EdgeType::Assign, AttrNone));
330  }
331 
332  void visitAllocaInst(AllocaInst &) {}
333 
334  void visitLoadInst(LoadInst &Inst) {
335  auto *Ptr = Inst.getPointerOperand();
336  auto *Val = &Inst;
337  Output.push_back(Edge(Val, Ptr, EdgeType::Reference, AttrNone));
338  }
339 
340  void visitStoreInst(StoreInst &Inst) {
341  auto *Ptr = Inst.getPointerOperand();
342  auto *Val = Inst.getValueOperand();
343  Output.push_back(Edge(Ptr, Val, EdgeType::Dereference, AttrNone));
344  }
345 
346  void visitVAArgInst(VAArgInst &Inst) {
347  // We can't fully model va_arg here. For *Ptr = Inst.getOperand(0), it does
348  // two things:
349  // 1. Loads a value from *((T*)*Ptr).
350  // 2. Increments (stores to) *Ptr by some target-specific amount.
351  // For now, we'll handle this like a landingpad instruction (by placing the
352  // result in its own group, and having that group alias externals).
353  auto *Val = &Inst;
354  Output.push_back(Edge(Val, Val, EdgeType::Assign, AttrAll));
355  }
356 
357  static bool isFunctionExternal(Function *Fn) {
358  return Fn->isDeclaration() || !Fn->hasLocalLinkage();
359  }
360 
361  // Gets whether the sets at Index1 above, below, or equal to the sets at
362  // Index2. Returns None if they are not in the same set chain.
363  static Optional<Level> getIndexRelation(const StratifiedSets<Value *> &Sets,
364  StratifiedIndex Index1,
365  StratifiedIndex Index2) {
366  if (Index1 == Index2)
367  return Level::Same;
368 
369  const auto *Current = &Sets.getLink(Index1);
370  while (Current->hasBelow()) {
371  if (Current->Below == Index2)
372  return Level::Below;
373  Current = &Sets.getLink(Current->Below);
374  }
375 
376  Current = &Sets.getLink(Index1);
377  while (Current->hasAbove()) {
378  if (Current->Above == Index2)
379  return Level::Above;
380  Current = &Sets.getLink(Current->Above);
381  }
382 
383  return NoneType();
384  }
385 
386  bool
387  tryInterproceduralAnalysis(const SmallVectorImpl<Function *> &Fns,
388  Value *FuncValue,
389  const iterator_range<User::op_iterator> &Args) {
390  const unsigned ExpectedMaxArgs = 8;
391  const unsigned MaxSupportedArgs = 50;
392  assert(Fns.size() > 0);
393 
394  // I put this here to give us an upper bound on time taken by IPA. Is it
395  // really (realistically) needed? Keep in mind that we do have an n^2 algo.
396  if (std::distance(Args.begin(), Args.end()) > (int)MaxSupportedArgs)
397  return false;
398 
399  // Exit early if we'll fail anyway
400  for (auto *Fn : Fns) {
401  if (isFunctionExternal(Fn) || Fn->isVarArg())
402  return false;
403  auto &MaybeInfo = AA.ensureCached(Fn);
404  if (!MaybeInfo.hasValue())
405  return false;
406  }
407 
408  SmallVector<Value *, ExpectedMaxArgs> Arguments(Args.begin(), Args.end());
410  for (auto *Fn : Fns) {
411  auto &Info = *AA.ensureCached(Fn);
412  auto &Sets = Info.Sets;
413  auto &RetVals = Info.ReturnedValues;
414 
415  Parameters.clear();
416  for (auto &Param : Fn->args()) {
417  auto MaybeInfo = Sets.find(&Param);
418  // Did a new parameter somehow get added to the function/slip by?
419  if (!MaybeInfo.hasValue())
420  return false;
421  Parameters.push_back(*MaybeInfo);
422  }
423 
424  // Adding an edge from argument -> return value for each parameter that
425  // may alias the return value
426  for (unsigned I = 0, E = Parameters.size(); I != E; ++I) {
427  auto &ParamInfo = Parameters[I];
428  auto &ArgVal = Arguments[I];
429  bool AddEdge = false;
430  StratifiedAttrs Externals;
431  for (unsigned X = 0, XE = RetVals.size(); X != XE; ++X) {
432  auto MaybeInfo = Sets.find(RetVals[X]);
433  if (!MaybeInfo.hasValue())
434  return false;
435 
436  auto &RetInfo = *MaybeInfo;
437  auto RetAttrs = Sets.getLink(RetInfo.Index).Attrs;
438  auto ParamAttrs = Sets.getLink(ParamInfo.Index).Attrs;
439  auto MaybeRelation =
440  getIndexRelation(Sets, ParamInfo.Index, RetInfo.Index);
441  if (MaybeRelation.hasValue()) {
442  AddEdge = true;
443  Externals |= RetAttrs | ParamAttrs;
444  }
445  }
446  if (AddEdge)
447  Output.push_back(Edge(FuncValue, ArgVal, EdgeType::Assign,
448  StratifiedAttrs().flip()));
449  }
450 
451  if (Parameters.size() != Arguments.size())
452  return false;
453 
454  // Adding edges between arguments for arguments that may end up aliasing
455  // each other. This is necessary for functions such as
456  // void foo(int** a, int** b) { *a = *b; }
457  // (Technically, the proper sets for this would be those below
458  // Arguments[I] and Arguments[X], but our algorithm will produce
459  // extremely similar, and equally correct, results either way)
460  for (unsigned I = 0, E = Arguments.size(); I != E; ++I) {
461  auto &MainVal = Arguments[I];
462  auto &MainInfo = Parameters[I];
463  auto &MainAttrs = Sets.getLink(MainInfo.Index).Attrs;
464  for (unsigned X = I + 1; X != E; ++X) {
465  auto &SubInfo = Parameters[X];
466  auto &SubVal = Arguments[X];
467  auto &SubAttrs = Sets.getLink(SubInfo.Index).Attrs;
468  auto MaybeRelation =
469  getIndexRelation(Sets, MainInfo.Index, SubInfo.Index);
470 
471  if (!MaybeRelation.hasValue())
472  continue;
473 
474  auto NewAttrs = SubAttrs | MainAttrs;
475  Output.push_back(Edge(MainVal, SubVal, EdgeType::Assign, NewAttrs));
476  }
477  }
478  }
479  return true;
480  }
481 
482  template <typename InstT> void visitCallLikeInst(InstT &Inst) {
484  if (getPossibleTargets(&Inst, Targets)) {
485  if (tryInterproceduralAnalysis(Targets, &Inst, Inst.arg_operands()))
486  return;
487  // Cleanup from interprocedural analysis
488  Output.clear();
489  }
490 
491  for (Value *V : Inst.arg_operands())
492  Output.push_back(Edge(&Inst, V, EdgeType::Assign, AttrAll));
493  }
494 
495  void visitCallInst(CallInst &Inst) { visitCallLikeInst(Inst); }
496 
497  void visitInvokeInst(InvokeInst &Inst) { visitCallLikeInst(Inst); }
498 
499  // Because vectors/aggregates are immutable and unaddressable,
500  // there's nothing we can do to coax a value out of them, other
501  // than calling Extract{Element,Value}. We can effectively treat
502  // them as pointers to arbitrary memory locations we can store in
503  // and load from.
504  void visitExtractElementInst(ExtractElementInst &Inst) {
505  auto *Ptr = Inst.getVectorOperand();
506  auto *Val = &Inst;
507  Output.push_back(Edge(Val, Ptr, EdgeType::Reference, AttrNone));
508  }
509 
510  void visitInsertElementInst(InsertElementInst &Inst) {
511  auto *Vec = Inst.getOperand(0);
512  auto *Val = Inst.getOperand(1);
513  Output.push_back(Edge(&Inst, Vec, EdgeType::Assign, AttrNone));
514  Output.push_back(Edge(&Inst, Val, EdgeType::Dereference, AttrNone));
515  }
516 
517  void visitLandingPadInst(LandingPadInst &Inst) {
518  // Exceptions come from "nowhere", from our analysis' perspective.
519  // So we place the instruction its own group, noting that said group may
520  // alias externals
521  Output.push_back(Edge(&Inst, &Inst, EdgeType::Assign, AttrAll));
522  }
523 
524  void visitInsertValueInst(InsertValueInst &Inst) {
525  auto *Agg = Inst.getOperand(0);
526  auto *Val = Inst.getOperand(1);
527  Output.push_back(Edge(&Inst, Agg, EdgeType::Assign, AttrNone));
528  Output.push_back(Edge(&Inst, Val, EdgeType::Dereference, AttrNone));
529  }
530 
531  void visitExtractValueInst(ExtractValueInst &Inst) {
532  auto *Ptr = Inst.getAggregateOperand();
533  Output.push_back(Edge(&Inst, Ptr, EdgeType::Reference, AttrNone));
534  }
535 
536  void visitShuffleVectorInst(ShuffleVectorInst &Inst) {
537  auto *From1 = Inst.getOperand(0);
538  auto *From2 = Inst.getOperand(1);
539  Output.push_back(Edge(&Inst, From1, EdgeType::Assign, AttrNone));
540  Output.push_back(Edge(&Inst, From2, EdgeType::Assign, AttrNone));
541  }
542 
543  void visitConstantExpr(ConstantExpr *CE) {
544  switch (CE->getOpcode()) {
545  default:
546  llvm_unreachable("Unknown instruction type encountered!");
547 // Build the switch statement using the Instruction.def file.
548 #define HANDLE_INST(NUM, OPCODE, CLASS) \
549  case Instruction::OPCODE: \
550  visit##OPCODE(*(CLASS *)CE); \
551  break;
552 #include "llvm/IR/Instruction.def"
553  }
554  }
555 };
556 
557 // For a given instruction, we need to know which Value* to get the
558 // users of in order to build our graph. In some cases (i.e. add),
559 // we simply need the Instruction*. In other cases (i.e. store),
560 // finding the users of the Instruction* is useless; we need to find
561 // the users of the first operand. This handles determining which
562 // value to follow for us.
563 //
564 // Note: we *need* to keep this in sync with GetEdgesVisitor. Add
565 // something to GetEdgesVisitor, add it here -- remove something from
566 // GetEdgesVisitor, remove it here.
567 class GetTargetValueVisitor
568  : public InstVisitor<GetTargetValueVisitor, Value *> {
569 public:
570  Value *visitInstruction(Instruction &Inst) { return &Inst; }
571 
572  Value *visitStoreInst(StoreInst &Inst) { return Inst.getPointerOperand(); }
573 
574  Value *visitAtomicCmpXchgInst(AtomicCmpXchgInst &Inst) {
575  return Inst.getPointerOperand();
576  }
577 
578  Value *visitAtomicRMWInst(AtomicRMWInst &Inst) {
579  return Inst.getPointerOperand();
580  }
581 
582  Value *visitInsertElementInst(InsertElementInst &Inst) {
583  return Inst.getOperand(0);
584  }
585 
586  Value *visitInsertValueInst(InsertValueInst &Inst) {
587  return Inst.getAggregateOperand();
588  }
589 };
590 
591 // Set building requires a weighted bidirectional graph.
592 template <typename EdgeTypeT> class WeightedBidirectionalGraph {
593 public:
594  typedef std::size_t Node;
595 
596 private:
597  const static Node StartNode = Node(0);
598 
599  struct Edge {
600  EdgeTypeT Weight;
601  Node Other;
602 
603  Edge(const EdgeTypeT &W, const Node &N) : Weight(W), Other(N) {}
604 
605  bool operator==(const Edge &E) const {
606  return Weight == E.Weight && Other == E.Other;
607  }
608 
609  bool operator!=(const Edge &E) const { return !operator==(E); }
610  };
611 
612  struct NodeImpl {
613  std::vector<Edge> Edges;
614  };
615 
616  std::vector<NodeImpl> NodeImpls;
617 
618  bool inbounds(Node NodeIndex) const { return NodeIndex < NodeImpls.size(); }
619 
620  const NodeImpl &getNode(Node N) const { return NodeImpls[N]; }
621  NodeImpl &getNode(Node N) { return NodeImpls[N]; }
622 
623 public:
624  // ----- Various Edge iterators for the graph ----- //
625 
626  // \brief Iterator for edges. Because this graph is bidirected, we don't
627  // allow modificaiton of the edges using this iterator. Additionally, the
628  // iterator becomes invalid if you add edges to or from the node you're
629  // getting the edges of.
630  struct EdgeIterator : public std::iterator<std::forward_iterator_tag,
631  std::tuple<EdgeTypeT, Node *>> {
632  EdgeIterator(const typename std::vector<Edge>::const_iterator &Iter)
633  : Current(Iter) {}
634 
635  EdgeIterator(NodeImpl &Impl) : Current(Impl.begin()) {}
636 
637  EdgeIterator &operator++() {
638  ++Current;
639  return *this;
640  }
641 
642  EdgeIterator operator++(int) {
643  EdgeIterator Copy(Current);
644  operator++();
645  return Copy;
646  }
647 
648  std::tuple<EdgeTypeT, Node> &operator*() {
649  Store = std::make_tuple(Current->Weight, Current->Other);
650  return Store;
651  }
652 
653  bool operator==(const EdgeIterator &Other) const {
654  return Current == Other.Current;
655  }
656 
657  bool operator!=(const EdgeIterator &Other) const {
658  return !operator==(Other);
659  }
660 
661  private:
662  typename std::vector<Edge>::const_iterator Current;
663  std::tuple<EdgeTypeT, Node> Store;
664  };
665 
666  // Wrapper for EdgeIterator with begin()/end() calls.
667  struct EdgeIterable {
668  EdgeIterable(const std::vector<Edge> &Edges)
669  : BeginIter(Edges.begin()), EndIter(Edges.end()) {}
670 
671  EdgeIterator begin() { return EdgeIterator(BeginIter); }
672 
673  EdgeIterator end() { return EdgeIterator(EndIter); }
674 
675  private:
676  typename std::vector<Edge>::const_iterator BeginIter;
677  typename std::vector<Edge>::const_iterator EndIter;
678  };
679 
680  // ----- Actual graph-related things ----- //
681 
682  WeightedBidirectionalGraph() {}
683 
684  WeightedBidirectionalGraph(WeightedBidirectionalGraph<EdgeTypeT> &&Other)
685  : NodeImpls(std::move(Other.NodeImpls)) {}
686 
687  WeightedBidirectionalGraph<EdgeTypeT> &
688  operator=(WeightedBidirectionalGraph<EdgeTypeT> &&Other) {
689  NodeImpls = std::move(Other.NodeImpls);
690  return *this;
691  }
692 
693  Node addNode() {
694  auto Index = NodeImpls.size();
695  auto NewNode = Node(Index);
696  NodeImpls.push_back(NodeImpl());
697  return NewNode;
698  }
699 
700  void addEdge(Node From, Node To, const EdgeTypeT &Weight,
701  const EdgeTypeT &ReverseWeight) {
702  assert(inbounds(From));
703  assert(inbounds(To));
704  auto &FromNode = getNode(From);
705  auto &ToNode = getNode(To);
706  FromNode.Edges.push_back(Edge(Weight, To));
707  ToNode.Edges.push_back(Edge(ReverseWeight, From));
708  }
709 
710  EdgeIterable edgesFor(const Node &N) const {
711  const auto &Node = getNode(N);
712  return EdgeIterable(Node.Edges);
713  }
714 
715  bool empty() const { return NodeImpls.empty(); }
716  std::size_t size() const { return NodeImpls.size(); }
717 
718  // \brief Gets an arbitrary node in the graph as a starting point for
719  // traversal.
720  Node getEntryNode() {
721  assert(inbounds(StartNode));
722  return StartNode;
723  }
724 };
725 
726 typedef WeightedBidirectionalGraph<std::pair<EdgeType, StratifiedAttrs>> GraphT;
727 typedef DenseMap<Value *, GraphT::Node> NodeMapT;
728 }
729 
730 // -- Setting up/registering CFLAA pass -- //
731 char CFLAliasAnalysis::ID = 0;
732 
733 INITIALIZE_AG_PASS(CFLAliasAnalysis, AliasAnalysis, "cfl-aa",
734  "CFL-Based AA implementation", false, true, false)
735 
737  return new CFLAliasAnalysis();
738 }
739 
740 //===----------------------------------------------------------------------===//
741 // Function declarations that require types defined in the namespace above
742 //===----------------------------------------------------------------------===//
743 
744 // Given an argument number, returns the appropriate Attr index to set.
745 static StratifiedAttr argNumberToAttrIndex(StratifiedAttr);
746 
747 // Given a Value, potentially return which AttrIndex it maps to.
749 
750 // Gets the inverse of a given EdgeType.
752 
753 // Gets edges of the given Instruction*, writing them to the SmallVector*.
754 static void argsToEdges(CFLAliasAnalysis &, Instruction *,
756 
757 // Gets edges of the given ConstantExpr*, writing them to the SmallVector*.
758 static void argsToEdges(CFLAliasAnalysis &, ConstantExpr *,
760 
761 // Gets the "Level" that one should travel in StratifiedSets
762 // given an EdgeType.
764 
765 // Builds the graph needed for constructing the StratifiedSets for the
766 // given function
767 static void buildGraphFrom(CFLAliasAnalysis &, Function *,
768  SmallVectorImpl<Value *> &, NodeMapT &, GraphT &);
769 
770 // Gets the edges of a ConstantExpr as if it was an Instruction. This
771 // function also acts on any nested ConstantExprs, adding the edges
772 // of those to the given SmallVector as well.
773 static void constexprToEdges(CFLAliasAnalysis &, ConstantExpr &,
775 
776 // Given an Instruction, this will add it to the graph, along with any
777 // Instructions that are potentially only available from said Instruction
778 // For example, given the following line:
779 // %0 = load i16* getelementptr ([1 x i16]* @a, 0, 0), align 2
780 // addInstructionToGraph would add both the `load` and `getelementptr`
781 // instructions to the graph appropriately.
782 static void addInstructionToGraph(CFLAliasAnalysis &, Instruction &,
783  SmallVectorImpl<Value *> &, NodeMapT &,
784  GraphT &);
785 
786 // Notes whether it would be pointless to add the given Value to our sets.
787 static bool canSkipAddingToSets(Value *Val);
788 
789 // Builds the graph + StratifiedSets for a function.
790 static FunctionInfo buildSetsFrom(CFLAliasAnalysis &, Function *);
791 
793  if (auto *Inst = dyn_cast<Instruction>(Val)) {
794  auto *Bb = Inst->getParent();
795  return Bb->getParent();
796  }
797 
798  if (auto *Arg = dyn_cast<Argument>(Val))
799  return Arg->getParent();
800  return NoneType();
801 }
802 
803 template <typename Inst>
804 static bool getPossibleTargets(Inst *Call,
805  SmallVectorImpl<Function *> &Output) {
806  if (auto *Fn = Call->getCalledFunction()) {
807  Output.push_back(Fn);
808  return true;
809  }
810 
811  // TODO: If the call is indirect, we might be able to enumerate all potential
812  // targets of the call and return them, rather than just failing.
813  return false;
814 }
815 
817  GetTargetValueVisitor V;
818  return V.visit(Inst);
819 }
820 
821 static bool hasUsefulEdges(Instruction *Inst) {
822  bool IsNonInvokeTerminator =
823  isa<TerminatorInst>(Inst) && !isa<InvokeInst>(Inst);
824  return !isa<CmpInst>(Inst) && !isa<FenceInst>(Inst) && !IsNonInvokeTerminator;
825 }
826 
827 static bool hasUsefulEdges(ConstantExpr *CE) {
828  // ConstantExpr doens't have terminators, invokes, or fences, so only needs
829  // to check for compares.
830  return CE->getOpcode() != Instruction::ICmp &&
831  CE->getOpcode() != Instruction::FCmp;
832 }
833 
835  if (isa<GlobalValue>(Val))
836  return AttrGlobalIndex;
837 
838  if (auto *Arg = dyn_cast<Argument>(Val))
839  // Only pointer arguments should have the argument attribute,
840  // because things can't escape through scalars without us seeing a
841  // cast, and thus, interaction with them doesn't matter.
842  if (!Arg->hasNoAliasAttr() && Arg->getType()->isPointerTy())
843  return argNumberToAttrIndex(Arg->getArgNo());
844  return NoneType();
845 }
846 
847 static StratifiedAttr argNumberToAttrIndex(unsigned ArgNum) {
848  if (ArgNum >= AttrMaxNumArgs)
849  return AttrAllIndex;
850  return ArgNum + AttrFirstArgIndex;
851 }
852 
853 static EdgeType flipWeight(EdgeType Initial) {
854  switch (Initial) {
855  case EdgeType::Assign:
856  return EdgeType::Assign;
857  case EdgeType::Dereference:
858  return EdgeType::Reference;
859  case EdgeType::Reference:
860  return EdgeType::Dereference;
861  }
862  llvm_unreachable("Incomplete coverage of EdgeType enum");
863 }
864 
865 static void argsToEdges(CFLAliasAnalysis &Analysis, Instruction *Inst,
866  SmallVectorImpl<Edge> &Output) {
867  assert(hasUsefulEdges(Inst) &&
868  "Expected instructions to have 'useful' edges");
869  GetEdgesVisitor v(Analysis, Output);
870  v.visit(Inst);
871 }
872 
873 static void argsToEdges(CFLAliasAnalysis &Analysis, ConstantExpr *CE,
874  SmallVectorImpl<Edge> &Output) {
875  assert(hasUsefulEdges(CE) && "Expected constant expr to have 'useful' edges");
876  GetEdgesVisitor v(Analysis, Output);
877  v.visitConstantExpr(CE);
878 }
879 
881  switch (Weight) {
882  case EdgeType::Reference:
883  return Level::Above;
884  case EdgeType::Dereference:
885  return Level::Below;
886  case EdgeType::Assign:
887  return Level::Same;
888  }
889  llvm_unreachable("Incomplete switch coverage");
890 }
891 
892 static void constexprToEdges(CFLAliasAnalysis &Analysis,
893  ConstantExpr &CExprToCollapse,
894  SmallVectorImpl<Edge> &Results) {
896  Worklist.push_back(&CExprToCollapse);
897 
898  SmallVector<Edge, 8> ConstexprEdges;
900  while (!Worklist.empty()) {
901  auto *CExpr = Worklist.pop_back_val();
902 
903  if (!hasUsefulEdges(CExpr))
904  continue;
905 
906  ConstexprEdges.clear();
907  argsToEdges(Analysis, CExpr, ConstexprEdges);
908  for (auto &Edge : ConstexprEdges) {
909  if (auto *Nested = dyn_cast<ConstantExpr>(Edge.From))
910  if (Visited.insert(Nested).second)
911  Worklist.push_back(Nested);
912 
913  if (auto *Nested = dyn_cast<ConstantExpr>(Edge.To))
914  if (Visited.insert(Nested).second)
915  Worklist.push_back(Nested);
916  }
917 
918  Results.append(ConstexprEdges.begin(), ConstexprEdges.end());
919  }
920 }
921 
922 static void addInstructionToGraph(CFLAliasAnalysis &Analysis, Instruction &Inst,
923  SmallVectorImpl<Value *> &ReturnedValues,
924  NodeMapT &Map, GraphT &Graph) {
925  const auto findOrInsertNode = [&Map, &Graph](Value *Val) {
926  auto Pair = Map.insert(std::make_pair(Val, GraphT::Node()));
927  auto &Iter = Pair.first;
928  if (Pair.second) {
929  auto NewNode = Graph.addNode();
930  Iter->second = NewNode;
931  }
932  return Iter->second;
933  };
934 
935  // We don't want the edges of most "return" instructions, but we *do* want
936  // to know what can be returned.
937  if (isa<ReturnInst>(&Inst))
938  ReturnedValues.push_back(&Inst);
939 
940  if (!hasUsefulEdges(&Inst))
941  return;
942 
943  SmallVector<Edge, 8> Edges;
944  argsToEdges(Analysis, &Inst, Edges);
945 
946  // In the case of an unused alloca (or similar), edges may be empty. Note
947  // that it exists so we can potentially answer NoAlias.
948  if (Edges.empty()) {
949  auto MaybeVal = getTargetValue(&Inst);
950  assert(MaybeVal.hasValue());
951  auto *Target = *MaybeVal;
952  findOrInsertNode(Target);
953  return;
954  }
955 
956  const auto addEdgeToGraph = [&Graph, &findOrInsertNode](const Edge &E) {
957  auto To = findOrInsertNode(E.To);
958  auto From = findOrInsertNode(E.From);
959  auto FlippedWeight = flipWeight(E.Weight);
960  auto Attrs = E.AdditionalAttrs;
961  Graph.addEdge(From, To, std::make_pair(E.Weight, Attrs),
962  std::make_pair(FlippedWeight, Attrs));
963  };
964 
965  SmallVector<ConstantExpr *, 4> ConstantExprs;
966  for (const Edge &E : Edges) {
967  addEdgeToGraph(E);
968  if (auto *Constexpr = dyn_cast<ConstantExpr>(E.To))
969  ConstantExprs.push_back(Constexpr);
970  if (auto *Constexpr = dyn_cast<ConstantExpr>(E.From))
971  ConstantExprs.push_back(Constexpr);
972  }
973 
974  for (ConstantExpr *CE : ConstantExprs) {
975  Edges.clear();
976  constexprToEdges(Analysis, *CE, Edges);
977  std::for_each(Edges.begin(), Edges.end(), addEdgeToGraph);
978  }
979 }
980 
981 // Aside: We may remove graph construction entirely, because it doesn't really
982 // buy us much that we don't already have. I'd like to add interprocedural
983 // analysis prior to this however, in case that somehow requires the graph
984 // produced by this for efficient execution
985 static void buildGraphFrom(CFLAliasAnalysis &Analysis, Function *Fn,
986  SmallVectorImpl<Value *> &ReturnedValues,
987  NodeMapT &Map, GraphT &Graph) {
988  for (auto &Bb : Fn->getBasicBlockList())
989  for (auto &Inst : Bb.getInstList())
990  addInstructionToGraph(Analysis, Inst, ReturnedValues, Map, Graph);
991 }
992 
993 static bool canSkipAddingToSets(Value *Val) {
994  // Constants can share instances, which may falsely unify multiple
995  // sets, e.g. in
996  // store i32* null, i32** %ptr1
997  // store i32* null, i32** %ptr2
998  // clearly ptr1 and ptr2 should not be unified into the same set, so
999  // we should filter out the (potentially shared) instance to
1000  // i32* null.
1001  if (isa<Constant>(Val)) {
1002  bool Container = isa<ConstantVector>(Val) || isa<ConstantArray>(Val) ||
1003  isa<ConstantStruct>(Val);
1004  // TODO: Because all of these things are constant, we can determine whether
1005  // the data is *actually* mutable at graph building time. This will probably
1006  // come for free/cheap with offset awareness.
1007  bool CanStoreMutableData =
1008  isa<GlobalValue>(Val) || isa<ConstantExpr>(Val) || Container;
1009  return !CanStoreMutableData;
1010  }
1011 
1012  return false;
1013 }
1014 
1015 static FunctionInfo buildSetsFrom(CFLAliasAnalysis &Analysis, Function *Fn) {
1016  NodeMapT Map;
1017  GraphT Graph;
1018  SmallVector<Value *, 4> ReturnedValues;
1019 
1020  buildGraphFrom(Analysis, Fn, ReturnedValues, Map, Graph);
1021 
1022  DenseMap<GraphT::Node, Value *> NodeValueMap;
1023  NodeValueMap.resize(Map.size());
1024  for (const auto &Pair : Map)
1025  NodeValueMap.insert(std::make_pair(Pair.second, Pair.first));
1026 
1027  const auto findValueOrDie = [&NodeValueMap](GraphT::Node Node) {
1028  auto ValIter = NodeValueMap.find(Node);
1029  assert(ValIter != NodeValueMap.end());
1030  return ValIter->second;
1031  };
1032 
1034 
1036  for (auto &Pair : Map) {
1037  Worklist.clear();
1038 
1039  auto *Value = Pair.first;
1040  Builder.add(Value);
1041  auto InitialNode = Pair.second;
1042  Worklist.push_back(InitialNode);
1043  while (!Worklist.empty()) {
1044  auto Node = Worklist.pop_back_val();
1045  auto *CurValue = findValueOrDie(Node);
1046  if (canSkipAddingToSets(CurValue))
1047  continue;
1048 
1049  for (const auto &EdgeTuple : Graph.edgesFor(Node)) {
1050  auto Weight = std::get<0>(EdgeTuple);
1051  auto Label = Weight.first;
1052  auto &OtherNode = std::get<1>(EdgeTuple);
1053  auto *OtherValue = findValueOrDie(OtherNode);
1054 
1055  if (canSkipAddingToSets(OtherValue))
1056  continue;
1057 
1058  bool Added;
1059  switch (directionOfEdgeType(Label)) {
1060  case Level::Above:
1061  Added = Builder.addAbove(CurValue, OtherValue);
1062  break;
1063  case Level::Below:
1064  Added = Builder.addBelow(CurValue, OtherValue);
1065  break;
1066  case Level::Same:
1067  Added = Builder.addWith(CurValue, OtherValue);
1068  break;
1069  }
1070 
1071  auto Aliasing = Weight.second;
1072  if (auto MaybeCurIndex = valueToAttrIndex(CurValue))
1073  Aliasing.set(*MaybeCurIndex);
1074  if (auto MaybeOtherIndex = valueToAttrIndex(OtherValue))
1075  Aliasing.set(*MaybeOtherIndex);
1076  Builder.noteAttributes(CurValue, Aliasing);
1077  Builder.noteAttributes(OtherValue, Aliasing);
1078 
1079  if (Added)
1080  Worklist.push_back(OtherNode);
1081  }
1082  }
1083  }
1084 
1085  // There are times when we end up with parameters not in our graph (i.e. if
1086  // it's only used as the condition of a branch). Other bits of code depend on
1087  // things that were present during construction being present in the graph.
1088  // So, we add all present arguments here.
1089  for (auto &Arg : Fn->args()) {
1090  if (!Builder.add(&Arg))
1091  continue;
1092 
1093  auto Attrs = valueToAttrIndex(&Arg);
1094  if (Attrs.hasValue())
1095  Builder.noteAttributes(&Arg, *Attrs);
1096  }
1097 
1098  return FunctionInfo(Builder.build(), std::move(ReturnedValues));
1099 }
1100 
1101 void CFLAliasAnalysis::scan(Function *Fn) {
1102  auto InsertPair = Cache.insert(std::make_pair(Fn, Optional<FunctionInfo>()));
1103  (void)InsertPair;
1104  assert(InsertPair.second &&
1105  "Trying to scan a function that has already been cached");
1106 
1107  FunctionInfo Info(buildSetsFrom(*this, Fn));
1108  Cache[Fn] = std::move(Info);
1109  Handles.push_front(FunctionHandle(Fn, this));
1110 }
1111 
1112 AliasResult CFLAliasAnalysis::query(const MemoryLocation &LocA,
1113  const MemoryLocation &LocB) {
1114  auto *ValA = const_cast<Value *>(LocA.Ptr);
1115  auto *ValB = const_cast<Value *>(LocB.Ptr);
1116 
1117  Function *Fn = nullptr;
1118  auto MaybeFnA = parentFunctionOfValue(ValA);
1119  auto MaybeFnB = parentFunctionOfValue(ValB);
1120  if (!MaybeFnA.hasValue() && !MaybeFnB.hasValue()) {
1121  // The only times this is known to happen are when globals + InlineAsm
1122  // are involved
1123  DEBUG(dbgs() << "CFLAA: could not extract parent function information.\n");
1124  return MayAlias;
1125  }
1126 
1127  if (MaybeFnA.hasValue()) {
1128  Fn = *MaybeFnA;
1129  assert((!MaybeFnB.hasValue() || *MaybeFnB == *MaybeFnA) &&
1130  "Interprocedural queries not supported");
1131  } else {
1132  Fn = *MaybeFnB;
1133  }
1134 
1135  assert(Fn != nullptr);
1136  auto &MaybeInfo = ensureCached(Fn);
1137  assert(MaybeInfo.hasValue());
1138 
1139  auto &Sets = MaybeInfo->Sets;
1140  auto MaybeA = Sets.find(ValA);
1141  if (!MaybeA.hasValue())
1142  return MayAlias;
1143 
1144  auto MaybeB = Sets.find(ValB);
1145  if (!MaybeB.hasValue())
1146  return MayAlias;
1147 
1148  auto SetA = *MaybeA;
1149  auto SetB = *MaybeB;
1150  auto AttrsA = Sets.getLink(SetA.Index).Attrs;
1151  auto AttrsB = Sets.getLink(SetB.Index).Attrs;
1152 
1153  // Stratified set attributes are used as markets to signify whether a member
1154  // of a StratifiedSet (or a member of a set above the current set) has
1155  // interacted with either arguments or globals. "Interacted with" meaning
1156  // its value may be different depending on the value of an argument or
1157  // global. The thought behind this is that, because arguments and globals
1158  // may alias each other, if AttrsA and AttrsB have touched args/globals,
1159  // we must conservatively say that they alias. However, if at least one of
1160  // the sets has no values that could legally be altered by changing the value
1161  // of an argument or global, then we don't have to be as conservative.
1162  if (AttrsA.any() && AttrsB.any())
1163  return MayAlias;
1164 
1165  // We currently unify things even if the accesses to them may not be in
1166  // bounds, so we can't return partial alias here because we don't
1167  // know whether the pointer is really within the object or not.
1168  // IE Given an out of bounds GEP and an alloca'd pointer, we may
1169  // unify the two. We can't return partial alias for this case.
1170  // Since we do not currently track enough information to
1171  // differentiate
1172 
1173  if (SetA.Index == SetB.Index)
1174  return MayAlias;
1175 
1176  return NoAlias;
1177 }
1178 
1179 bool CFLAliasAnalysis::doInitialization(Module &M) {
1180  InitializeAliasAnalysis(this, &M.getDataLayout());
1181  return true;
1182 }
The two locations precisely alias each other.
Definition: AliasAnalysis.h:84
StratifiedSets< T > build()
Value * getValueOperand()
Definition: Instructions.h:406
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:240
static Level directionOfEdgeType(EdgeType)
ExtractValueInst - This instruction extracts a struct member or array element value from an aggregate...
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
static bool getPossibleTargets(Inst *, SmallVectorImpl< Function * > &)
Base class for instruction visitors.
Definition: InstVisitor.h:81
Value * getAggregateOperand()
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:114
AtomicCmpXchgInst - an instruction that atomically checks whether a specified value is in a memory lo...
Definition: Instructions.h:515
NoneType
A simple null object to allow implicit construction of Optional<T> and similar types without having to ...
Definition: None.h:22
static StratifiedAttr argNumberToAttrIndex(StratifiedAttr)
The two locations alias, but only due to a partial overlap.
Definition: AliasAnalysis.h:82
static const unsigned NumStratifiedAttrs
virtual void getAnalysisUsage(AnalysisUsage &) const
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: Pass.cpp:78
CallInst - This class represents a function call, abstracting a target machine's calling convention...
ShuffleVectorInst - This instruction constructs a fixed permutation of two input vectors.
const_iterator begin(StringRef path)
Get begin iterator over path.
Definition: Path.cpp:232
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:111
The two locations do not alias at all.
Definition: AliasAnalysis.h:78
LoadInst - an instruction for reading from memory.
Definition: Instructions.h:177
AtomicRMWInst - an instruction that atomically reads a memory location, combines it with another valu...
Definition: Instructions.h:674
unsigned getOpcode() const
getOpcode - Return the opcode at the root of this constant expression
Definition: Constants.h:1144
The two locations may or may not alias. This is the least precise result.
Definition: AliasAnalysis.h:80
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static void argsToEdges(CFLAliasAnalysis &, Instruction *, SmallVectorImpl< Edge > &)
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:169
#define LLVM_CONSTEXPR
Definition: Compiler.h:98
SelectInst - This class represents the LLVM 'select' instruction.
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:389
T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val()
Definition: SmallVector.h:406
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
bool addAbove(const T &Main, const T &ToAdd)
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APInt.h:33
const StratifiedLink & getLink(StratifiedIndex Index) const
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:591
This class represents a cast from a pointer to an integer.
ConstantExpr - a constant value that is initialized with an expression using other constant values...
Definition: Constants.h:852
bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const
Definition: SmallVector.h:57
op_iterator idx_begin()
Definition: Instructions.h:954
StoreInst - an instruction for storing to memory.
Definition: Instructions.h:316
ImmutablePass * createCFLAliasAnalysisPass()
static void constexprToEdges(CFLAliasAnalysis &, ConstantExpr &, SmallVectorImpl< Edge > &)
static void addInstructionToGraph(CFLAliasAnalysis &, Instruction &, SmallVectorImpl< Value * > &, NodeMapT &, GraphT &)
static void buildGraphFrom(CFLAliasAnalysis &, Function *, SmallVectorImpl< Value * > &, NodeMapT &, GraphT &)
virtual bool doInitialization(Module &)
doInitialization - Virtual method overridden by subclasses to do any necessary initialization before ...
Definition: Pass.h:111
GetElementPtrInst - an instruction for type-safe pointer arithmetic to access elements of arrays and ...
Definition: Instructions.h:830
InsertElementInst - This instruction inserts a single (scalar) element into a VectorType value...
LandingPadInst - The landingpad instruction holds all of the information necessary to generate correc...
static bool hasUsefulEdges(Instruction *)
This file contains the declarations for the subclasses of Constant, which represent the different fla...
static Optional< StratifiedAttr > valueToAttrIndex(Value *Val)
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:264
AliasResult
The possible results of an alias query.
Definition: AliasAnalysis.h:72
Represent the analysis usage information of a pass.
static bool canSkipAddingToSets(Value *Val)
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
Optional< StratifiedInfo > find(const T &Elem) const
Value * getOperand(unsigned i) const
Definition: User.h:118
Value * getPointerOperand()
Definition: Instructions.h:284
static Optional< Value * > getTargetValue(Instruction *)
void noteAttributes(const T &Main, const StratifiedAttrs &NewAttrs)
This class represents a cast from an integer to a pointer.
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:416
VAArgInst - This class represents the va_arg llvm instruction, which returns an argument of the speci...
const Value * getTrueValue() const
void resize(size_type Size)
Grow the densemap so that it has at least Size buckets. Does not shrink.
Definition: DenseMap.h:85
bool addWith(const T &Main, const T &ToAdd)
INITIALIZE_AG_PASS(CFLAliasAnalysis, AliasAnalysis,"cfl-aa","CFL-Based AA implementation", false, true, false) ImmutablePass *llvm
const Value * Ptr
The address of the start of the location.
Representation for a specific memory location.
static Optional< Function * > parentFunctionOfValue(Value *)
Value * getValOperand()
Definition: Instructions.h:783
const BasicBlockListType & getBasicBlockList() const
Definition: Function.h:436
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:299
ImmutablePass class - This class is used to provide information that does not need to be run...
Definition: Pass.h:262
bool addBelow(const T &Main, const T &ToAdd)
BlockMass operator*(const BlockMass &L, const BranchProbability &R)
virtual AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB)
Alias Queries...
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
static EdgeType flipWeight(EdgeType)
bool add(const T &Main)
IteratorT end() const
IteratorT begin() const
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
A range adaptor for a pair of iterators.
Target - Wrapper for Target specific information.
bool operator!=(uint64_t V1, const APInt &V2)
Definition: APInt.h:1736
std::bitset< NumStratifiedAttrs > StratifiedAttrs
const DataLayout & getDataLayout() const
Get the data layout for the module's target platform.
Definition: Module.cpp:372
block Block Frequency Analysis
bool isDeclaration() const
Return true if the primary definition of this global value is outside of the current translation unit...
Definition: Globals.cpp:128
Value * getPointerOperand()
Definition: Instructions.h:779
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
void size_t size
ExtractElementInst - This instruction extracts a single (scalar) element from a VectorType value...
static FunctionInfo buildSetsFrom(CFLAliasAnalysis &, Function *)
bool hasLocalLinkage() const
Definition: GlobalValue.h:280
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:365
LLVM Value Representation.
Definition: Value.h:69
void initializeCFLAliasAnalysisPass(PassRegistry &)
virtual void getAnalysisUsage(AnalysisUsage &AU) const
getAnalysisUsage - All alias analysis implementations should invoke this directly (using AliasAnalysi...
virtual void * getAdjustedAnalysisPointer(AnalysisID ID)
getAdjustedAnalysisPointer - This method is used when a pass implements an analysis interface through...
Definition: Pass.cpp:90
InvokeInst - Invoke instruction.
#define DEBUG(X)
Definition: Debug.h:92
const Value * getFalseValue() const
Value handle with callbacks on RAUW and destruction.
Definition: ValueHandle.h:344
bool operator==(uint64_t V1, const APInt &V2)
Definition: APInt.h:1734
op_range incoming_values()
bool isVarArg() const
isVarArg - Return true if this function takes a variable number of arguments.
Definition: Function.cpp:229
Value * getPointerOperand()
Definition: Instructions.h:409
const BasicBlock * getParent() const
Definition: Instruction.h:72
iterator_range< arg_iterator > args()
Definition: Function.h:489
AllocaInst - an instruction to allocate memory on the stack.
Definition: Instructions.h:76
InsertValueInst - This instruction inserts a struct field of array element value into an aggregate va...
uint64_t Size
The maximum size of the location, in address-units, or UnknownSize if the size is not known...