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PHITransAddr.h
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1 //===- PHITransAddr.h - PHI Translation for Addresses -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file declares the PHITransAddr class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_ANALYSIS_PHITRANSADDR_H
14 #define LLVM_ANALYSIS_PHITRANSADDR_H
15 
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/IR/Instruction.h"
18 
19 namespace llvm {
20  class AssumptionCache;
21  class DominatorTree;
22  class DataLayout;
23  class TargetLibraryInfo;
24 
25 /// PHITransAddr - An address value which tracks and handles phi translation.
26 /// As we walk "up" the CFG through predecessors, we need to ensure that the
27 /// address we're tracking is kept up to date. For example, if we're analyzing
28 /// an address of "&A[i]" and walk through the definition of 'i' which is a PHI
29 /// node, we *must* phi translate i to get "&A[j]" or else we will analyze an
30 /// incorrect pointer in the predecessor block.
31 ///
32 /// This is designed to be a relatively small object that lives on the stack and
33 /// is copyable.
34 ///
35 class PHITransAddr {
36  /// Addr - The actual address we're analyzing.
37  Value *Addr;
38 
39  /// The DataLayout we are playing with.
40  const DataLayout &DL;
41 
42  /// TLI - The target library info if known, otherwise null.
43  const TargetLibraryInfo *TLI;
44 
45  /// A cache of \@llvm.assume calls used by SimplifyInstruction.
46  AssumptionCache *AC;
47 
48  /// InstInputs - The inputs for our symbolic address.
50 
51 public:
53  : Addr(addr), DL(DL), TLI(nullptr), AC(AC) {
54  // If the address is an instruction, the whole thing is considered an input.
55  if (Instruction *I = dyn_cast<Instruction>(Addr))
56  InstInputs.push_back(I);
57  }
58 
59  Value *getAddr() const { return Addr; }
60 
61  /// NeedsPHITranslationFromBlock - Return true if moving from the specified
62  /// BasicBlock to its predecessors requires PHI translation.
64  // We do need translation if one of our input instructions is defined in
65  // this block.
66  for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
67  if (InstInputs[i]->getParent() == BB)
68  return true;
69  return false;
70  }
71 
72  /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true
73  /// if we have some hope of doing it. This should be used as a filter to
74  /// avoid calling PHITranslateValue in hopeless situations.
75  bool IsPotentiallyPHITranslatable() const;
76 
77  /// PHITranslateValue - PHI translate the current address up the CFG from
78  /// CurBB to Pred, updating our state to reflect any needed changes. If
79  /// 'MustDominate' is true, the translated value must dominate
80  /// PredBB. This returns true on failure and sets Addr to null.
81  bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB,
82  const DominatorTree *DT, bool MustDominate);
83 
84  /// PHITranslateWithInsertion - PHI translate this value into the specified
85  /// predecessor block, inserting a computation of the value if it is
86  /// unavailable.
87  ///
88  /// All newly created instructions are added to the NewInsts list. This
89  /// returns null on failure.
90  ///
92  const DominatorTree &DT,
94 
95  void dump() const;
96 
97  /// Verify - Check internal consistency of this data structure. If the
98  /// structure is valid, it returns true. If invalid, it prints errors and
99  /// returns false.
100  bool Verify() const;
101 
102 private:
103  Value *PHITranslateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB,
104  const DominatorTree *DT);
105 
106  /// InsertPHITranslatedSubExpr - Insert a computation of the PHI translated
107  /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
108  /// block. All newly created instructions are added to the NewInsts list.
109  /// This returns null on failure.
110  ///
111  Value *InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
112  BasicBlock *PredBB, const DominatorTree &DT,
114 
115  /// AddAsInput - If the specified value is an instruction, add it as an input.
116  Value *AddAsInput(Value *V) {
117  // If V is an instruction, it is now an input.
118  if (Instruction *VI = dyn_cast<Instruction>(V))
119  InstInputs.push_back(VI);
120  return V;
121  }
122 };
123 
124 } // end namespace llvm
125 
126 #endif
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:110
This class represents lattice values for constants.
Definition: AllocatorList.h:23
A cache of @llvm.assume calls within a function.
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
PHITransAddr - An address value which tracks and handles phi translation.
Definition: PHITransAddr.h:35
void dump() const
PHITransAddr(Value *addr, const DataLayout &DL, AssumptionCache *AC)
Definition: PHITransAddr.h:52
size_t size() const
Definition: SmallVector.h:52
Value * PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB, const DominatorTree &DT, SmallVectorImpl< Instruction *> &NewInsts)
PHITranslateWithInsertion - PHI translate this value into the specified predecessor block...
bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB, const DominatorTree *DT, bool MustDominate)
PHITranslateValue - PHI translate the current address up the CFG from CurBB to Pred, updating our state to reflect any needed changes.
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Provides information about what library functions are available for the current target.
bool NeedsPHITranslationFromBlock(BasicBlock *BB) const
NeedsPHITranslationFromBlock - Return true if moving from the specified BasicBlock to its predecessor...
Definition: PHITransAddr.h:63
bool Verify() const
Verify - Check internal consistency of this data structure.
#define I(x, y, z)
Definition: MD5.cpp:58
bool IsPotentiallyPHITranslatable() const
IsPotentiallyPHITranslatable - If this needs PHI translation, return true if we have some hope of doi...
Value * getAddr() const
Definition: PHITransAddr.h:59
LLVM Value Representation.
Definition: Value.h:72
static const Function * getParent(const Value *V)