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
19namespace llvm {
20class AssumptionCache;
21class DominatorTree;
22class DataLayout;
23class 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///
35class 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 = nullptr;
44
45  /// A cache of \@llvm.assume calls used by SimplifyInstruction.
46  AssumptionCache *AC;
47
48  /// InstInputs - The inputs for our symbolic address.
49  SmallVector<Instruction*, 4> InstInputs;
50
51public:
52  PHITransAddr(Value *Addr, const DataLayout &DL, AssumptionCache *AC)
53      : Addr(Addr), DL(DL), AC(AC) {
54    // If the address is an instruction, the whole thing is considered an input.
55    addAsInput(Addr);
56  }
57
58  Value *getAddr() const { return Addr; }
59
60  /// needsPHITranslationFromBlock - Return true if moving from the specified
61  /// BasicBlock to its predecessors requires PHI translation.
62  bool needsPHITranslationFromBlock(BasicBlock *BB) const {
63    // We do need translation if one of our input instructions is defined in
64    // this block.
65    return any_of(InstInputs, [BB](const auto &InstInput) {
66      return InstInput->getParent() == BB;
67    });
68  }
69
70  /// isPotentiallyPHITranslatable - If this needs PHI translation, return true
71  /// if we have some hope of doing it.  This should be used as a filter to
72  /// avoid calling PHITranslateValue in hopeless situations.
73  bool isPotentiallyPHITranslatable() const;
74
75  /// translateValue - PHI translate the current address up the CFG from
76  /// CurBB to Pred, updating our state to reflect any needed changes.  If
77  /// 'MustDominate' is true, the translated value must dominate PredBB.
78  Value *translateValue(BasicBlock *CurBB, BasicBlock *PredBB,
79                        const DominatorTree *DT, bool MustDominate);
80
81  /// translateWithInsertion - PHI translate this value into the specified
82  /// predecessor block, inserting a computation of the value if it is
83  /// unavailable.
84  ///
85  /// All newly created instructions are added to the NewInsts list.  This
86  /// returns null on failure.
87  ///
88  Value *translateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB,
89                                const DominatorTree &DT,
90                                SmallVectorImpl<Instruction *> &NewInsts);
91
92  void dump() const;
93
94  /// verify - Check internal consistency of this data structure.  If the
95  /// structure is valid, it returns true.  If invalid, it prints errors and
96  /// returns false.
97  bool verify() const;
98
99private:
100  Value *translateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB,
101                          const DominatorTree *DT);
102
103  /// insertTranslatedSubExpr - Insert a computation of the PHI translated
104  /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
105  /// block.  All newly created instructions are added to the NewInsts list.
106  /// This returns null on failure.
107  ///
108  Value *insertTranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
109                                 BasicBlock *PredBB, const DominatorTree &DT,
110                                 SmallVectorImpl<Instruction *> &NewInsts);
111
112  /// addAsInput - If the specified value is an instruction, add it as an input.
113  Value *addAsInput(Value *V) {
114    // If V is an instruction, it is now an input.
115    if (Instruction *VI = dyn_cast<Instruction>(V))
116      InstInputs.push_back(VI);
117    return V;
118  }
119};
120
121} // end namespace llvm
122
123#endif
124