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//===- llvm/Analysis/IVUsers.h - Induction Variable Users -------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file implements bookkeeping for "interesting" users of expressions
// computed from induction variables.
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionNormalization.h"
#include "llvm/IR/ValueHandle.h"
namespace llvm {
class DominatorTree;
class Instruction;
class Value;
class ScalarEvolution;
class SCEV;
class IVUsers;
class DataLayout;
/// IVStrideUse - Keep track of one use of a strided induction variable.
/// The Expr member keeps track of the expression, User is the actual user
/// instruction of the operand, and 'OperandValToReplace' is the operand of
/// the User that is the use.
class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
friend class IVUsers;
IVStrideUse(IVUsers *P, Instruction* U, Value *O)
: CallbackVH(U), Parent(P), OperandValToReplace(O) {
/// getUser - Return the user instruction for this use.
Instruction *getUser() const {
return cast<Instruction>(getValPtr());
/// setUser - Assign a new user instruction for this use.
void setUser(Instruction *NewUser) {
/// getOperandValToReplace - Return the Value of the operand in the user
/// instruction that this IVStrideUse is representing.
Value *getOperandValToReplace() const {
return OperandValToReplace;
/// setOperandValToReplace - Assign a new Value as the operand value
/// to replace.
void setOperandValToReplace(Value *Op) {
OperandValToReplace = Op;
/// getPostIncLoops - Return the set of loops for which the expression has
/// been adjusted to use post-inc mode.
const PostIncLoopSet &getPostIncLoops() const {
return PostIncLoops;
/// transformToPostInc - Transform the expression to post-inc form for the
/// given loop.
void transformToPostInc(const Loop *L);
/// Parent - a pointer to the IVUsers that owns this IVStrideUse.
IVUsers *Parent;
/// OperandValToReplace - The Value of the operand in the user instruction
/// that this IVStrideUse is representing.
WeakVH OperandValToReplace;
/// PostIncLoops - The set of loops for which Expr has been adjusted to
/// use post-inc mode. This corresponds with SCEVExpander's post-inc concept.
PostIncLoopSet PostIncLoops;
/// Deleted - Implementation of CallbackVH virtual function to
/// receive notification when the User is deleted.
void deleted() override;
template<> struct ilist_traits<IVStrideUse>
: public ilist_default_traits<IVStrideUse> {
// createSentinel is used to get hold of a node that marks the end of
// the list...
// The sentinel is relative to this instance, so we use a non-static
// method.
IVStrideUse *createSentinel() const {
// since i(p)lists always publicly derive from the corresponding
// traits, placing a data member in this class will augment i(p)list.
// But since the NodeTy is expected to publicly derive from
// ilist_node<NodeTy>, there is a legal viable downcast from it
// to NodeTy. We use this trick to superpose i(p)list with a "ghostly"
// NodeTy, which becomes the sentinel. Dereferencing the sentinel is
// forbidden (save the ilist_node<NodeTy>) so no one will ever notice
// the superposition.
return static_cast<IVStrideUse*>(&Sentinel);
static void destroySentinel(IVStrideUse*) {}
IVStrideUse *provideInitialHead() const { return createSentinel(); }
IVStrideUse *ensureHead(IVStrideUse*) const { return createSentinel(); }
static void noteHead(IVStrideUse*, IVStrideUse*) {}
mutable ilist_node<IVStrideUse> Sentinel;
class IVUsers : public LoopPass {
friend class IVStrideUse;
Loop *L;
LoopInfo *LI;
DominatorTree *DT;
ScalarEvolution *SE;
const DataLayout *DL;
SmallPtrSet<Instruction*,16> Processed;
/// IVUses - A list of all tracked IV uses of induction variable expressions
/// we are interested in.
ilist<IVStrideUse> IVUses;
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnLoop(Loop *L, LPPassManager &LPM) override;
void releaseMemory() override;
static char ID; // Pass ID, replacement for typeid
Loop *getLoop() const { return L; }
/// AddUsersIfInteresting - Inspect the specified Instruction. If it is a
/// reducible SCEV, recursively add its users to the IVUsesByStride set and
/// return true. Otherwise, return false.
bool AddUsersIfInteresting(Instruction *I);
IVStrideUse &AddUser(Instruction *User, Value *Operand);
/// getReplacementExpr - Return a SCEV expression which computes the
/// value of the OperandValToReplace of the given IVStrideUse.
const SCEV *getReplacementExpr(const IVStrideUse &IU) const;
/// getExpr - Return the expression for the use.
const SCEV *getExpr(const IVStrideUse &IU) const;
const SCEV *getStride(const IVStrideUse &IU, const Loop *L) const;
typedef ilist<IVStrideUse>::iterator iterator;
typedef ilist<IVStrideUse>::const_iterator const_iterator;
iterator begin() { return IVUses.begin(); }
iterator end() { return IVUses.end(); }
const_iterator begin() const { return IVUses.begin(); }
const_iterator end() const { return IVUses.end(); }
bool empty() const { return IVUses.empty(); }
bool isIVUserOrOperand(Instruction *Inst) const {
return Processed.count(Inst);
void print(raw_ostream &OS, const Module* = nullptr) const override;
/// dump - This method is used for debugging.
void dump() const;
bool AddUsersImpl(Instruction *I, SmallPtrSet<Loop*,16> &SimpleLoopNests);
Pass *createIVUsersPass();