LLVM  4.0.0
TypeBasedAliasAnalysis.cpp
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1 //===- TypeBasedAliasAnalysis.cpp - Type-Based Alias Analysis -------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the TypeBasedAliasAnalysis pass, which implements
11 // metadata-based TBAA.
12 //
13 // In LLVM IR, memory does not have types, so LLVM's own type system is not
14 // suitable for doing TBAA. Instead, metadata is added to the IR to describe
15 // a type system of a higher level language. This can be used to implement
16 // typical C/C++ TBAA, but it can also be used to implement custom alias
17 // analysis behavior for other languages.
18 //
19 // We now support two types of metadata format: scalar TBAA and struct-path
20 // aware TBAA. After all testing cases are upgraded to use struct-path aware
21 // TBAA and we can auto-upgrade existing bc files, the support for scalar TBAA
22 // can be dropped.
23 //
24 // The scalar TBAA metadata format is very simple. TBAA MDNodes have up to
25 // three fields, e.g.:
26 // !0 = metadata !{ metadata !"an example type tree" }
27 // !1 = metadata !{ metadata !"int", metadata !0 }
28 // !2 = metadata !{ metadata !"float", metadata !0 }
29 // !3 = metadata !{ metadata !"const float", metadata !2, i64 1 }
30 //
31 // The first field is an identity field. It can be any value, usually
32 // an MDString, which uniquely identifies the type. The most important
33 // name in the tree is the name of the root node. Two trees with
34 // different root node names are entirely disjoint, even if they
35 // have leaves with common names.
36 //
37 // The second field identifies the type's parent node in the tree, or
38 // is null or omitted for a root node. A type is considered to alias
39 // all of its descendants and all of its ancestors in the tree. Also,
40 // a type is considered to alias all types in other trees, so that
41 // bitcode produced from multiple front-ends is handled conservatively.
42 //
43 // If the third field is present, it's an integer which if equal to 1
44 // indicates that the type is "constant" (meaning pointsToConstantMemory
45 // should return true; see
46 // http://llvm.org/docs/AliasAnalysis.html#OtherItfs).
47 //
48 // With struct-path aware TBAA, the MDNodes attached to an instruction using
49 // "!tbaa" are called path tag nodes.
50 //
51 // The path tag node has 4 fields with the last field being optional.
52 //
53 // The first field is the base type node, it can be a struct type node
54 // or a scalar type node. The second field is the access type node, it
55 // must be a scalar type node. The third field is the offset into the base type.
56 // The last field has the same meaning as the last field of our scalar TBAA:
57 // it's an integer which if equal to 1 indicates that the access is "constant".
58 //
59 // The struct type node has a name and a list of pairs, one pair for each member
60 // of the struct. The first element of each pair is a type node (a struct type
61 // node or a sclar type node), specifying the type of the member, the second
62 // element of each pair is the offset of the member.
63 //
64 // Given an example
65 // typedef struct {
66 // short s;
67 // } A;
68 // typedef struct {
69 // uint16_t s;
70 // A a;
71 // } B;
72 //
73 // For an access to B.a.s, we attach !5 (a path tag node) to the load/store
74 // instruction. The base type is !4 (struct B), the access type is !2 (scalar
75 // type short) and the offset is 4.
76 //
77 // !0 = metadata !{metadata !"Simple C/C++ TBAA"}
78 // !1 = metadata !{metadata !"omnipotent char", metadata !0} // Scalar type node
79 // !2 = metadata !{metadata !"short", metadata !1} // Scalar type node
80 // !3 = metadata !{metadata !"A", metadata !2, i64 0} // Struct type node
81 // !4 = metadata !{metadata !"B", metadata !2, i64 0, metadata !3, i64 4}
82 // // Struct type node
83 // !5 = metadata !{metadata !4, metadata !2, i64 4} // Path tag node
84 //
85 // The struct type nodes and the scalar type nodes form a type DAG.
86 // Root (!0)
87 // char (!1) -- edge to Root
88 // short (!2) -- edge to char
89 // A (!3) -- edge with offset 0 to short
90 // B (!4) -- edge with offset 0 to short and edge with offset 4 to A
91 //
92 // To check if two tags (tagX and tagY) can alias, we start from the base type
93 // of tagX, follow the edge with the correct offset in the type DAG and adjust
94 // the offset until we reach the base type of tagY or until we reach the Root
95 // node.
96 // If we reach the base type of tagY, compare the adjusted offset with
97 // offset of tagY, return Alias if the offsets are the same, return NoAlias
98 // otherwise.
99 // If we reach the Root node, perform the above starting from base type of tagY
100 // to see if we reach base type of tagX.
101 //
102 // If they have different roots, they're part of different potentially
103 // unrelated type systems, so we return Alias to be conservative.
104 // If neither node is an ancestor of the other and they have the same root,
105 // then we say NoAlias.
106 //
107 // TODO: The current metadata format doesn't support struct
108 // fields. For example:
109 // struct X {
110 // double d;
111 // int i;
112 // };
113 // void foo(struct X *x, struct X *y, double *p) {
114 // *x = *y;
115 // *p = 0.0;
116 // }
117 // Struct X has a double member, so the store to *x can alias the store to *p.
118 // Currently it's not possible to precisely describe all the things struct X
119 // aliases, so struct assignments must use conservative TBAA nodes. There's
120 // no scheme for attaching metadata to @llvm.memcpy yet either.
121 //
122 //===----------------------------------------------------------------------===//
123 
125 #include "llvm/ADT/SetVector.h"
126 #include "llvm/IR/Constants.h"
127 #include "llvm/IR/LLVMContext.h"
128 #include "llvm/IR/Module.h"
130 using namespace llvm;
131 
132 // A handy option for disabling TBAA functionality. The same effect can also be
133 // achieved by stripping the !tbaa tags from IR, but this option is sometimes
134 // more convenient.
135 static cl::opt<bool> EnableTBAA("enable-tbaa", cl::init(true));
136 
137 namespace {
138 /// This is a simple wrapper around an MDNode which provides a higher-level
139 /// interface by hiding the details of how alias analysis information is encoded
140 /// in its operands.
141 template<typename MDNodeTy>
142 class TBAANodeImpl {
143  MDNodeTy *Node;
144 
145 public:
146  TBAANodeImpl() : Node(nullptr) {}
147  explicit TBAANodeImpl(MDNodeTy *N) : Node(N) {}
148 
149  /// getNode - Get the MDNode for this TBAANode.
150  MDNodeTy *getNode() const { return Node; }
151 
152  /// getParent - Get this TBAANode's Alias tree parent.
153  TBAANodeImpl<MDNodeTy> getParent() const {
154  if (Node->getNumOperands() < 2)
155  return TBAANodeImpl<MDNodeTy>();
156  MDNodeTy *P = dyn_cast_or_null<MDNodeTy>(Node->getOperand(1));
157  if (!P)
158  return TBAANodeImpl<MDNodeTy>();
159  // Ok, this node has a valid parent. Return it.
160  return TBAANodeImpl<MDNodeTy>(P);
161  }
162 
163  /// Test if this TBAANode represents a type for objects which are
164  /// not modified (by any means) in the context where this
165  /// AliasAnalysis is relevant.
166  bool isTypeImmutable() const {
167  if (Node->getNumOperands() < 3)
168  return false;
169  ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(Node->getOperand(2));
170  if (!CI)
171  return false;
172  return CI->getValue()[0];
173  }
174 };
175 
176 /// \name Specializations of \c TBAANodeImpl for const and non const qualified
177 /// \c MDNode.
178 /// @{
179 typedef TBAANodeImpl<const MDNode> TBAANode;
180 typedef TBAANodeImpl<MDNode> MutableTBAANode;
181 /// @}
182 
183 /// This is a simple wrapper around an MDNode which provides a
184 /// higher-level interface by hiding the details of how alias analysis
185 /// information is encoded in its operands.
186 template<typename MDNodeTy>
187 class TBAAStructTagNodeImpl {
188  /// This node should be created with createTBAAStructTagNode.
189  MDNodeTy *Node;
190 
191 public:
192  explicit TBAAStructTagNodeImpl(MDNodeTy *N) : Node(N) {}
193 
194  /// Get the MDNode for this TBAAStructTagNode.
195  MDNodeTy *getNode() const { return Node; }
196 
197  MDNodeTy *getBaseType() const {
198  return dyn_cast_or_null<MDNode>(Node->getOperand(0));
199  }
200  MDNodeTy *getAccessType() const {
201  return dyn_cast_or_null<MDNode>(Node->getOperand(1));
202  }
203  uint64_t getOffset() const {
204  return mdconst::extract<ConstantInt>(Node->getOperand(2))->getZExtValue();
205  }
206  /// Test if this TBAAStructTagNode represents a type for objects
207  /// which are not modified (by any means) in the context where this
208  /// AliasAnalysis is relevant.
209  bool isTypeImmutable() const {
210  if (Node->getNumOperands() < 4)
211  return false;
212  ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(Node->getOperand(3));
213  if (!CI)
214  return false;
215  return CI->getValue()[0];
216  }
217 };
218 
219 /// \name Specializations of \c TBAAStructTagNodeImpl for const and non const
220 /// qualified \c MDNods.
221 /// @{
222 typedef TBAAStructTagNodeImpl<const MDNode> TBAAStructTagNode;
223 typedef TBAAStructTagNodeImpl<MDNode> MutableTBAAStructTagNode;
224 /// @}
225 
226 /// This is a simple wrapper around an MDNode which provides a
227 /// higher-level interface by hiding the details of how alias analysis
228 /// information is encoded in its operands.
229 class TBAAStructTypeNode {
230  /// This node should be created with createTBAAStructTypeNode.
231  const MDNode *Node;
232 
233 public:
234  TBAAStructTypeNode() : Node(nullptr) {}
235  explicit TBAAStructTypeNode(const MDNode *N) : Node(N) {}
236 
237  /// Get the MDNode for this TBAAStructTypeNode.
238  const MDNode *getNode() const { return Node; }
239 
240  /// Get this TBAAStructTypeNode's field in the type DAG with
241  /// given offset. Update the offset to be relative to the field type.
242  TBAAStructTypeNode getParent(uint64_t &Offset) const {
243  // Parent can be omitted for the root node.
244  if (Node->getNumOperands() < 2)
245  return TBAAStructTypeNode();
246 
247  // Fast path for a scalar type node and a struct type node with a single
248  // field.
249  if (Node->getNumOperands() <= 3) {
250  uint64_t Cur = Node->getNumOperands() == 2
251  ? 0
252  : mdconst::extract<ConstantInt>(Node->getOperand(2))
253  ->getZExtValue();
254  Offset -= Cur;
255  MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(1));
256  if (!P)
257  return TBAAStructTypeNode();
258  return TBAAStructTypeNode(P);
259  }
260 
261  // Assume the offsets are in order. We return the previous field if
262  // the current offset is bigger than the given offset.
263  unsigned TheIdx = 0;
264  for (unsigned Idx = 1; Idx < Node->getNumOperands(); Idx += 2) {
265  uint64_t Cur = mdconst::extract<ConstantInt>(Node->getOperand(Idx + 1))
266  ->getZExtValue();
267  if (Cur > Offset) {
268  assert(Idx >= 3 &&
269  "TBAAStructTypeNode::getParent should have an offset match!");
270  TheIdx = Idx - 2;
271  break;
272  }
273  }
274  // Move along the last field.
275  if (TheIdx == 0)
276  TheIdx = Node->getNumOperands() - 2;
277  uint64_t Cur = mdconst::extract<ConstantInt>(Node->getOperand(TheIdx + 1))
278  ->getZExtValue();
279  Offset -= Cur;
280  MDNode *P = dyn_cast_or_null<MDNode>(Node->getOperand(TheIdx));
281  if (!P)
282  return TBAAStructTypeNode();
283  return TBAAStructTypeNode(P);
284  }
285 };
286 }
287 
288 /// Check the first operand of the tbaa tag node, if it is a MDNode, we treat
289 /// it as struct-path aware TBAA format, otherwise, we treat it as scalar TBAA
290 /// format.
291 static bool isStructPathTBAA(const MDNode *MD) {
292  // Anonymous TBAA root starts with a MDNode and dragonegg uses it as
293  // a TBAA tag.
294  return isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3;
295 }
296 
298  const MemoryLocation &LocB) {
299  if (!EnableTBAA)
300  return AAResultBase::alias(LocA, LocB);
301 
302  // Get the attached MDNodes. If either value lacks a tbaa MDNode, we must
303  // be conservative.
304  const MDNode *AM = LocA.AATags.TBAA;
305  if (!AM)
306  return AAResultBase::alias(LocA, LocB);
307  const MDNode *BM = LocB.AATags.TBAA;
308  if (!BM)
309  return AAResultBase::alias(LocA, LocB);
310 
311  // If they may alias, chain to the next AliasAnalysis.
312  if (Aliases(AM, BM))
313  return AAResultBase::alias(LocA, LocB);
314 
315  // Otherwise return a definitive result.
316  return NoAlias;
317 }
318 
320  bool OrLocal) {
321  if (!EnableTBAA)
322  return AAResultBase::pointsToConstantMemory(Loc, OrLocal);
323 
324  const MDNode *M = Loc.AATags.TBAA;
325  if (!M)
326  return AAResultBase::pointsToConstantMemory(Loc, OrLocal);
327 
328  // If this is an "immutable" type, we can assume the pointer is pointing
329  // to constant memory.
330  if ((!isStructPathTBAA(M) && TBAANode(M).isTypeImmutable()) ||
331  (isStructPathTBAA(M) && TBAAStructTagNode(M).isTypeImmutable()))
332  return true;
333 
334  return AAResultBase::pointsToConstantMemory(Loc, OrLocal);
335 }
336 
339  if (!EnableTBAA)
341 
343 
344  // If this is an "immutable" type, we can assume the call doesn't write
345  // to memory.
347  if ((!isStructPathTBAA(M) && TBAANode(M).isTypeImmutable()) ||
348  (isStructPathTBAA(M) && TBAAStructTagNode(M).isTypeImmutable()))
349  Min = FMRB_OnlyReadsMemory;
350 
352 }
353 
355  // Functions don't have metadata. Just chain to the next implementation.
357 }
358 
360  const MemoryLocation &Loc) {
361  if (!EnableTBAA)
362  return AAResultBase::getModRefInfo(CS, Loc);
363 
364  if (const MDNode *L = Loc.AATags.TBAA)
365  if (const MDNode *M =
367  if (!Aliases(L, M))
368  return MRI_NoModRef;
369 
370  return AAResultBase::getModRefInfo(CS, Loc);
371 }
372 
374  ImmutableCallSite CS2) {
375  if (!EnableTBAA)
376  return AAResultBase::getModRefInfo(CS1, CS2);
377 
378  if (const MDNode *M1 =
380  if (const MDNode *M2 =
382  if (!Aliases(M1, M2))
383  return MRI_NoModRef;
384 
385  return AAResultBase::getModRefInfo(CS1, CS2);
386 }
387 
389  if (!isStructPathTBAA(this)) {
390  if (getNumOperands() < 1)
391  return false;
392  if (MDString *Tag1 = dyn_cast<MDString>(getOperand(0))) {
393  if (Tag1->getString() == "vtable pointer")
394  return true;
395  }
396  return false;
397  }
398 
399  // For struct-path aware TBAA, we use the access type of the tag.
400  if (getNumOperands() < 2)
401  return false;
402  MDNode *Tag = cast_or_null<MDNode>(getOperand(1));
403  if (!Tag)
404  return false;
405  if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
406  if (Tag1->getString() == "vtable pointer")
407  return true;
408  }
409  return false;
410 }
411 
413  if (!A || !B)
414  return nullptr;
415 
416  if (A == B)
417  return A;
418 
419  // For struct-path aware TBAA, we use the access type of the tag.
421  "Auto upgrade should have taken care of this!");
422  A = cast_or_null<MDNode>(MutableTBAAStructTagNode(A).getAccessType());
423  if (!A)
424  return nullptr;
425  B = cast_or_null<MDNode>(MutableTBAAStructTagNode(B).getAccessType());
426  if (!B)
427  return nullptr;
428 
430  MutableTBAANode TA(A);
431  while (TA.getNode()) {
432  if (PathA.count(TA.getNode()))
433  report_fatal_error("Cycle found in TBAA metadata.");
434  PathA.insert(TA.getNode());
435  TA = TA.getParent();
436  }
437 
439  MutableTBAANode TB(B);
440  while (TB.getNode()) {
441  if (PathB.count(TB.getNode()))
442  report_fatal_error("Cycle found in TBAA metadata.");
443  PathB.insert(TB.getNode());
444  TB = TB.getParent();
445  }
446 
447  int IA = PathA.size() - 1;
448  int IB = PathB.size() - 1;
449 
450  MDNode *Ret = nullptr;
451  while (IA >= 0 && IB >= 0) {
452  if (PathA[IA] == PathB[IB])
453  Ret = PathA[IA];
454  else
455  break;
456  --IA;
457  --IB;
458  }
459 
460  // We either did not find a match, or the only common base "type" is
461  // the root node. In either case, we don't have any useful TBAA
462  // metadata to attach.
463  if (!Ret || Ret->getNumOperands() < 2)
464  return nullptr;
465 
466  // We need to convert from a type node to a tag node.
467  Type *Int64 = IntegerType::get(A->getContext(), 64);
468  Metadata *Ops[3] = {Ret, Ret,
470  return MDNode::get(A->getContext(), Ops);
471 }
472 
474  if (Merge)
475  N.TBAA =
477  else
479 
480  if (Merge)
483  else
485 
486  if (Merge)
487  N.NoAlias =
489  else
491 }
492 
493 /// Aliases - Test whether the type represented by A may alias the
494 /// type represented by B.
495 bool TypeBasedAAResult::Aliases(const MDNode *A, const MDNode *B) const {
496  // Verify that both input nodes are struct-path aware. Auto-upgrade should
497  // have taken care of this.
498  assert(isStructPathTBAA(A) && "MDNode A is not struct-path aware.");
499  assert(isStructPathTBAA(B) && "MDNode B is not struct-path aware.");
500 
501  // Keep track of the root node for A and B.
502  TBAAStructTypeNode RootA, RootB;
503  TBAAStructTagNode TagA(A), TagB(B);
504 
505  // TODO: We need to check if AccessType of TagA encloses AccessType of
506  // TagB to support aggregate AccessType. If yes, return true.
507 
508  // Start from the base type of A, follow the edge with the correct offset in
509  // the type DAG and adjust the offset until we reach the base type of B or
510  // until we reach the Root node.
511  // Compare the adjusted offset once we have the same base.
512 
513  // Climb the type DAG from base type of A to see if we reach base type of B.
514  const MDNode *BaseA = TagA.getBaseType();
515  const MDNode *BaseB = TagB.getBaseType();
516  uint64_t OffsetA = TagA.getOffset(), OffsetB = TagB.getOffset();
517  for (TBAAStructTypeNode T(BaseA);;) {
518  if (T.getNode() == BaseB)
519  // Base type of A encloses base type of B, check if the offsets match.
520  return OffsetA == OffsetB;
521 
522  RootA = T;
523  // Follow the edge with the correct offset, OffsetA will be adjusted to
524  // be relative to the field type.
525  T = T.getParent(OffsetA);
526  if (!T.getNode())
527  break;
528  }
529 
530  // Reset OffsetA and climb the type DAG from base type of B to see if we reach
531  // base type of A.
532  OffsetA = TagA.getOffset();
533  for (TBAAStructTypeNode T(BaseB);;) {
534  if (T.getNode() == BaseA)
535  // Base type of B encloses base type of A, check if the offsets match.
536  return OffsetA == OffsetB;
537 
538  RootB = T;
539  // Follow the edge with the correct offset, OffsetB will be adjusted to
540  // be relative to the field type.
541  T = T.getParent(OffsetB);
542  if (!T.getNode())
543  break;
544  }
545 
546  // Neither node is an ancestor of the other.
547 
548  // If they have different roots, they're part of different potentially
549  // unrelated type systems, so we must be conservative.
550  if (RootA.getNode() != RootB.getNode())
551  return true;
552 
553  // If they have the same root, then we've proved there's no alias.
554  return false;
555 }
556 
557 AnalysisKey TypeBasedAA::Key;
558 
560  return TypeBasedAAResult();
561 }
562 
564 INITIALIZE_PASS(TypeBasedAAWrapperPass, "tbaa", "Type-Based Alias Analysis",
565  false, true)
566 
568  return new TypeBasedAAWrapperPass();
569 }
570 
573 }
574 
576  Result.reset(new TypeBasedAAResult());
577  return false;
578 }
579 
581  Result.reset();
582  return false;
583 }
584 
586  AU.setPreservesAll();
587 }
MachineLoop * L
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
MDNode * Scope
The tag for alias scope specification (used with noalias).
Definition: Metadata.h:642
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
MDNode * TBAA
The tag for type-based alias analysis.
Definition: Metadata.h:639
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:52
bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal)
unsigned getNumOperands() const
Definition: User.h:167
unsigned getNumOperands() const
Return number of MDNode operands.
Definition: Metadata.h:1040
static MDNode * getMostGenericAliasScope(MDNode *A, MDNode *B)
Definition: Metadata.cpp:883
INITIALIZE_PASS(TypeBasedAAWrapperPass,"tbaa","Type-Based Alias Analysis", false, true) ImmutablePass *llvm
Metadata node.
Definition: Metadata.h:830
The two locations do not alias at all.
Definition: AliasAnalysis.h:79
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB)
size_type size() const
Determine the number of elements in the SetVector.
Definition: SetVector.h:78
void initializeTypeBasedAAWrapperPassPass(PassRegistry &)
TypeBasedAAResult run(Function &F, FunctionAnalysisManager &AM)
This indicates that the function could not be classified into one of the behaviors above...
Legacy wrapper pass to provide the TypeBasedAAResult object.
ModRefInfo
Flags indicating whether a memory access modifies or references memory.
Definition: AliasAnalysis.h:94
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:143
bool isTBAAVtableAccess() const
Check whether MDNode is a vtable access.
#define F(x, y, z)
Definition: MD5.cpp:51
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:136
#define T
FunctionModRefBehavior
Summary of how a function affects memory in the program.
FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS)
static MDNode * intersect(MDNode *A, MDNode *B)
Definition: Metadata.cpp:870
static GCRegistry::Add< OcamlGC > B("ocaml","ocaml 3.10-compatible GC")
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB)
static Error getOffset(const SymbolRef &Sym, SectionRef Sec, uint64_t &Result)
static ConstantAsMetadata * get(Constant *C)
Definition: Metadata.h:392
bool doFinalization(Module &M) override
doFinalization - Virtual method overriden by subclasses to do any necessary clean up after all passes...
FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS)
The access neither references nor modifies the value stored in memory.
Definition: AliasAnalysis.h:96
#define P(N)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:395
This is the interface for a metadata-based TBAA.
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
This file contains the declarations for the subclasses of Constant, which represent the different fla...
AliasResult
The possible results of an alias query.
Definition: AliasAnalysis.h:73
Represent the analysis usage information of a pass.
uint32_t Offset
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
A simple AA result that uses TBAA metadata to answer queries.
static MDNode * getMostGenericTBAA(MDNode *A, MDNode *B)
ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc)
Representation for a specific memory location.
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:234
const MDOperand & getOperand(unsigned I) const
Definition: Metadata.h:1034
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:292
static void Merge(const std::string &Input, const std::vector< std::string > Result, size_t NumNewFeatures)
This is the shared class of boolean and integer constants.
Definition: Constants.h:88
ImmutablePass class - This class is used to provide information that does not need to be run...
Definition: Pass.h:266
InstrTy * getInstruction() const
Definition: CallSite.h:93
Module.h This file contains the declarations for the Module class.
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:175
A collection of metadata nodes that might be associated with a memory access used by the alias-analys...
Definition: Metadata.h:625
MDNode * NoAlias
The tag specifying the noalias scope.
Definition: Metadata.h:645
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:558
This function does not perform any non-local stores or volatile loads, but may read from any memory l...
void setPreservesAll()
Set by analyses that do not transform their input at all.
static cl::opt< bool > EnableTBAA("enable-tbaa", cl::init(true))
static MDTuple * get(LLVMContext &Context, ArrayRef< Metadata * > MDs)
Definition: Metadata.h:1132
AAMDNodes AATags
The metadata nodes which describes the aliasing of the location (each member is null if that kind of ...
size_type count(const key_type &key) const
Count the number of elements of a given key in the SetVector.
Definition: SetVector.h:205
void getAAMetadata(AAMDNodes &N, bool Merge=false) const
Fills the AAMDNodes structure with AA metadata from this instruction.
ImmutableCallSite - establish a view to a call site for examination.
Definition: CallSite.h:665
#define N
static MemAccessTy getAccessType(const Instruction *Inst)
Return the type of the memory being accessed.
LLVMContext & getContext() const
Definition: Metadata.h:889
ImmutablePass * createTypeBasedAAWrapperPass()
ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static const Function * getParent(const Value *V)
A single uniqued string.
Definition: Metadata.h:586
A container for analyses that lazily runs them and caches their results.
static GCRegistry::Add< ErlangGC > A("erlang","erlang-compatible garbage collector")
Root of the metadata hierarchy.
Definition: Metadata.h:55
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:64
bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal)
bool doInitialization(Module &M) override
doInitialization - Virtual method overridden by subclasses to do any necessary initialization before ...
static bool isStructPathTBAA(const MDNode *MD)
Check the first operand of the tbaa tag node, if it is a MDNode, we treat it as struct-path aware TBA...