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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
67 lines
2.5 KiB
C++
67 lines
2.5 KiB
C++
//===- llvm/Analysis/OrderedBasicBlock.h --------------------- -*- 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 the OrderedBasicBlock class. OrderedBasicBlock maintains
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// an interface where clients can query if one instruction comes before another
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// in a BasicBlock. Since BasicBlock currently lacks a reliable way to query
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// relative position between instructions one can use OrderedBasicBlock to do
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// such queries. OrderedBasicBlock is lazily built on a source BasicBlock and
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// maintains an internal Instruction -> Position map. A OrderedBasicBlock
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// instance should be discarded whenever the source BasicBlock changes.
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//
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// It's currently used by the CaptureTracker in order to find relative
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// positions of a pair of instructions inside a BasicBlock.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_ORDEREDBASICBLOCK_H
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#define LLVM_ANALYSIS_ORDEREDBASICBLOCK_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/IR/BasicBlock.h"
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namespace llvm {
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class Instruction;
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class BasicBlock;
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class OrderedBasicBlock {
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private:
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/// Map a instruction to its position in a BasicBlock.
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SmallDenseMap<const Instruction *, unsigned, 32> NumberedInsts;
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/// Keep track of last instruction inserted into \p NumberedInsts.
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/// It speeds up queries for uncached instructions by providing a start point
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/// for new queries in OrderedBasicBlock::comesBefore.
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BasicBlock::const_iterator LastInstFound;
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/// The position/number to tag the next instruction to be found.
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unsigned NextInstPos;
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/// The source BasicBlock to map.
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const BasicBlock *BB;
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/// Given no cached results, find if \p A comes before \p B in \p BB.
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/// Cache and number out instruction while walking \p BB.
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bool comesBefore(const Instruction *A, const Instruction *B);
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public:
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OrderedBasicBlock(const BasicBlock *BasicB);
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/// Find out whether \p A dominates \p B, meaning whether \p A
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/// comes before \p B in \p BB. This is a simplification that considers
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/// cached instruction positions and ignores other basic blocks, being
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/// only relevant to compare relative instructions positions inside \p BB.
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/// Returns false for A == B.
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bool dominates(const Instruction *A, const Instruction *B);
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};
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} // End llvm namespace
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#endif
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