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f71ae721ed
So far it would return true for the first uncached query, then cached queries return false. llvm-svn: 304545
68 lines
2.5 KiB
C++
68 lines
2.5 KiB
C++
//===- llvm/Analysis/OrderedBasicBlock.h --------------------- -*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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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/// \brief Map a instruction to its position in a BasicBlock.
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SmallDenseMap<const Instruction *, unsigned, 32> NumberedInsts;
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/// \brief 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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/// \brief The position/number to tag the next instruction to be found.
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unsigned NextInstPos;
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/// \brief The source BasicBlock to map.
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const BasicBlock *BB;
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/// \brief 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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/// \brief 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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