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69 lines
2.5 KiB
C++
69 lines
2.5 KiB
C++
//===- llvm/Analysis/ScalarEvolutionNormalization.h - See below -*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines utilities for working with "normalized" ScalarEvolution
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// expressions.
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//
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// The following example illustrates post-increment uses and how normalized
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// expressions help.
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//
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// for (i=0; i!=n; ++i) {
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// ...
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// }
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// use(i);
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//
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// While the expression for most uses of i inside the loop is {0,+,1}<%L>, the
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// expression for the use of i outside the loop is {1,+,1}<%L>, since i is
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// incremented at the end of the loop body. This is inconveient, since it
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// suggests that we need two different induction variables, one that starts
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// at 0 and one that starts at 1. We'd prefer to be able to think of these as
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// the same induction variable, with uses inside the loop using the
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// "pre-incremented" value, and uses after the loop using the
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// "post-incremented" value.
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//
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// Expressions for post-incremented uses are represented as an expression
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// paired with a set of loops for which the expression is in "post-increment"
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// mode (there may be multiple loops).
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H
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#define LLVM_ANALYSIS_SCALAREVOLUTIONNORMALIZATION_H
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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namespace llvm {
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class Loop;
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class ScalarEvolution;
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class SCEV;
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typedef SmallPtrSet<const Loop *, 2> PostIncLoopSet;
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typedef function_ref<bool(const SCEVAddRecExpr *)> NormalizePredTy;
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/// Normalize \p S to be post-increment for all loops present in \p
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/// Loops.
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const SCEV *normalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops,
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ScalarEvolution &SE);
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/// Normalize \p S for all add recurrence sub-expressions for which \p
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/// Pred returns true.
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const SCEV *normalizeForPostIncUseIf(const SCEV *S, NormalizePredTy Pred,
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ScalarEvolution &SE);
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/// Denormalize \p S to be post-increment for all loops present in \p
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/// Loops.
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const SCEV *denormalizeForPostIncUse(const SCEV *S, const PostIncLoopSet &Loops,
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ScalarEvolution &SE);
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} // namespace llvm
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#endif
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