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