LLVM  10.0.0svn
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1 //===- PtrUseVisitor.cpp - InstVisitors over a pointers uses --------------===//
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 /// \file
10 /// Implementation of the pointer use visitors.
11 //
12 //===----------------------------------------------------------------------===//
15 #include "llvm/IR/Instruction.h"
16 #include "llvm/IR/Instructions.h"
17 #include <algorithm>
19 using namespace llvm;
22  for (Use &U : I.uses()) {
23  if (VisitedUses.insert(&U).second) {
24  UseToVisit NewU = {
26  Offset
27  };
28  Worklist.push_back(std::move(NewU));
29  }
30  }
31 }
34  if (!IsOffsetKnown)
35  return false;
37  APInt TmpOffset(DL.getIndexTypeSizeInBits(GEPI.getType()), 0);
38  if (GEPI.accumulateConstantOffset(DL, TmpOffset)) {
39  Offset += TmpOffset.sextOrTrunc(Offset.getBitWidth());
40  return true;
41  }
43  return false;
44 }
iterator_range< use_iterator > uses()
Definition: Value.h:375
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Use * U
The use currently being visited.
SmallPtrSet< Use *, 8 > VisitedUses
A set of visited uses to break cycles in unreachable code.
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1517
bool IsOffsetKnown
True if we have a known constant offset for the use currently being visited.
A Use represents the edge between a Value definition and its users.
Definition: Use.h:55
This file provides a collection of visitors which walk the (instruction) uses of a pointer...
A struct of the data needed to visit a particular use.
SmallVector< UseToVisit, 8 > Worklist
The worklist of to-visit uses.
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:246
APInt sextOrTrunc(unsigned width) const
Sign extend or truncate to width.
Definition: APInt.cpp:938
PointerIntPair< Use *, 1, bool > UseAndIsOffsetKnownPair
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:881
void enqueueUsers(Instruction &I)
Enqueue the users of this instruction in the visit worklist.
unsigned getIndexTypeSizeInBits(Type *Ty) const
Layout size of the index used in GEP calculation.
Definition: DataLayout.cpp:687
bool adjustOffsetForGEP(GetElementPtrInst &GEPI)
Walk the operands of a GEP and adjust the offset as appropriate.
Class for arbitrary precision integers.
Definition: APInt.h:69
bool accumulateConstantOffset(const DataLayout &DL, APInt &Offset) const
Accumulate the constant address offset of this GEP if possible.
#define I(x, y, z)
Definition: MD5.cpp:58
APInt Offset
The constant offset of the use if that is known.