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      1 //===-- llvm/Transforms/Utils/SimplifyIndVar.h - Indvar Utils ---*- 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 defines in interface for induction variable simplification. It does
     10 // not define any actual pass or policy, but provides a single function to
     11 // simplify a loop's induction variables based on ScalarEvolution.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_TRANSFORMS_UTILS_SIMPLIFYINDVAR_H
     16 #define LLVM_TRANSFORMS_UTILS_SIMPLIFYINDVAR_H
     17 
     18 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
     19 #include "llvm/IR/ConstantRange.h"
     20 #include "llvm/IR/ValueHandle.h"
     21 
     22 namespace llvm {
     23 
     24 class CastInst;
     25 class DominatorTree;
     26 class Loop;
     27 class LoopInfo;
     28 class PHINode;
     29 class ScalarEvolution;
     30 class SCEVExpander;
     31 class TargetTransformInfo;
     32 
     33 /// Interface for visiting interesting IV users that are recognized but not
     34 /// simplified by this utility.
     35 class IVVisitor {
     36 protected:
     37   const DominatorTree *DT = nullptr;
     38 
     39   virtual void anchor();
     40 
     41 public:
     42   IVVisitor() = default;
     43   virtual ~IVVisitor() = default;
     44 
     45   const DominatorTree *getDomTree() const { return DT; }
     46   virtual void visitCast(CastInst *Cast) = 0;
     47 };
     48 
     49 /// simplifyUsersOfIV - Simplify instructions that use this induction variable
     50 /// by using ScalarEvolution to analyze the IV's recurrence.
     51 bool simplifyUsersOfIV(PHINode *CurrIV, ScalarEvolution *SE, DominatorTree *DT,
     52                        LoopInfo *LI, const TargetTransformInfo *TTI,
     53                        SmallVectorImpl<WeakTrackingVH> &Dead,
     54                        SCEVExpander &Rewriter, IVVisitor *V = nullptr);
     55 
     56 /// SimplifyLoopIVs - Simplify users of induction variables within this
     57 /// loop. This does not actually change or add IVs.
     58 bool simplifyLoopIVs(Loop *L, ScalarEvolution *SE, DominatorTree *DT,
     59                      LoopInfo *LI, const TargetTransformInfo *TTI,
     60                      SmallVectorImpl<WeakTrackingVH> &Dead);
     61 
     62 /// Collect information about induction variables that are used by sign/zero
     63 /// extend operations. This information is recorded by CollectExtend and provides
     64 /// the input to WidenIV.
     65 struct WideIVInfo {
     66   PHINode *NarrowIV = nullptr;
     67 
     68   // Widest integer type created [sz]ext
     69   Type *WidestNativeType = nullptr;
     70 
     71   // Was a sext user seen before a zext?
     72   bool IsSigned = false;
     73 };
     74 
     75 /// Widen Induction Variables - Extend the width of an IV to cover its
     76 /// widest uses.
     77 PHINode *createWideIV(const WideIVInfo &WI,
     78     LoopInfo *LI, ScalarEvolution *SE, SCEVExpander &Rewriter,
     79     DominatorTree *DT, SmallVectorImpl<WeakTrackingVH> &DeadInsts,
     80     unsigned &NumElimExt, unsigned &NumWidened,
     81     bool HasGuards, bool UsePostIncrementRanges);
     82 
     83 } // end namespace llvm
     84 
     85 #endif // LLVM_TRANSFORMS_UTILS_SIMPLIFYINDVAR_H
     86