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| 14 | pmbaty | 1 | //===- llvm/Analysis/ScalarEvolutionNormalization.h - See below -*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // This file defines utilities for working with "normalized" ScalarEvolution |
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| 10 | // expressions. |
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| 11 | // |
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| 12 | // The following example illustrates post-increment uses and how normalized |
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| 13 | // expressions help. |
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| 14 | // |
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| 15 | // for (i=0; i!=n; ++i) { |
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| 16 | // ... |
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| 17 | // } |
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| 18 | // use(i); |
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| 19 | // |
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| 20 | // While the expression for most uses of i inside the loop is {0,+,1}<%L>, the |
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| 21 | // expression for the use of i outside the loop is {1,+,1}<%L>, since i is |
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| 22 | // incremented at the end of the loop body. This is inconveient, since it |
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| 23 | // suggests that we need two different induction variables, one that starts |
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| 24 | // at 0 and one that starts at 1. We'd prefer to be able to think of these as |
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| 25 | // the same induction variable, with uses inside the loop using the |
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| 26 | // "pre-incremented" value, and uses after the loop using the |
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| 27 | // "post-incremented" value. |
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| 28 | // |
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| 29 | // Expressions for post-incremented uses are represented as an expression |
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| 30 | // paired with a set of loops for which the expression is in "post-increment" |
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| 31 | // mode (there may be multiple loops). |
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| 32 | // |
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| 33 | //===----------------------------------------------------------------------===// |
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| 34 | |||
| 35 | #ifndef LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H |
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| 36 | #define LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H |
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| 37 | |||
| 38 | #include "llvm/ADT/STLFunctionalExtras.h" |
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| 39 | #include "llvm/ADT/SmallPtrSet.h" |
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| 40 | |||
| 41 | namespace llvm { |
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| 42 | |||
| 43 | class Loop; |
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| 44 | class ScalarEvolution; |
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| 45 | class SCEV; |
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| 46 | class SCEVAddRecExpr; |
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| 47 | |||
| 48 | typedef SmallPtrSet<const Loop *, 2> PostIncLoopSet; |
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| 49 | |||
| 50 | typedef function_ref<bool(const SCEVAddRecExpr *)> NormalizePredTy; |
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| 51 | |||
| 52 | /// Normalize \p S to be post-increment for all loops present in \p |
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| 53 | /// Loops. |
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| 54 | const SCEV *normalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops, |
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| 55 | ScalarEvolution &SE); |
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| 56 | |||
| 57 | /// Normalize \p S for all add recurrence sub-expressions for which \p |
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| 58 | /// Pred returns true. |
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| 59 | const SCEV *normalizeForPostIncUseIf(const SCEV *S, NormalizePredTy Pred, |
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| 60 | ScalarEvolution &SE); |
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| 61 | |||
| 62 | /// Denormalize \p S to be post-increment for all loops present in \p |
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| 63 | /// Loops. |
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| 64 | const SCEV *denormalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops, |
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| 65 | ScalarEvolution &SE); |
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| 66 | } // namespace llvm |
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| 67 | |||
| 68 | #endif |