1 //===- llvm/Analysis/ScalarEvolutionNormalization.h - See below -*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines utilities for working with "normalized" ScalarEvolution 11 // expressions. 12 // 13 // The following example illustrates post-increment uses and how normalized 14 // expressions help. 15 // 16 // for (i=0; i!=n; ++i) { 17 // ... 18 // } 19 // use(i); 20 // 21 // While the expression for most uses of i inside the loop is {0,+,1}<%L>, the 22 // expression for the use of i outside the loop is {1,+,1}<%L>, since i is 23 // incremented at the end of the loop body. This is inconveient, since it 24 // suggests that we need two different induction variables, one that starts 25 // at 0 and one that starts at 1. We'd prefer to be able to think of these as 26 // the same induction variable, with uses inside the loop using the 27 // "pre-incremented" value, and uses after the loop using the 28 // "post-incremented" value. 29 // 30 // Expressions for post-incremented uses are represented as an expression 31 // paired with a set of loops for which the expression is in "post-increment" 32 // mode (there may be multiple loops). 33 // 34 //===----------------------------------------------------------------------===// 35 36 #ifndef LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H 37 #define LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H 38 39 #include "llvm/ADT/STLExtras.h" 40 #include "llvm/ADT/SmallPtrSet.h" 41 #include "llvm/Analysis/ScalarEvolutionExpressions.h" 42 43 namespace llvm { 44 45 class Loop; 46 class ScalarEvolution; 47 class SCEV; 48 49 typedef SmallPtrSet<const Loop *, 2> PostIncLoopSet; 50 51 typedef function_ref<bool(const SCEVAddRecExpr *)> NormalizePredTy; 52 53 /// Normalize \p S to be post-increment for all loops present in \p 54 /// Loops. 55 const SCEV *normalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops, 56 ScalarEvolution &SE); 57 58 /// Normalize \p S for all add recurrence sub-expressions for which \p 59 /// Pred returns true. 60 const SCEV *normalizeForPostIncUseIf(const SCEV *S, NormalizePredTy Pred, 61 ScalarEvolution &SE); 62 63 /// Denormalize \p S to be post-increment for all loops present in \p 64 /// Loops. 65 const SCEV *denormalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops, 66 ScalarEvolution &SE); 67 } // namespace llvm 68 69 #endif 70