87 lines
2.8 KiB
C
87 lines
2.8 KiB
C
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//===- ProvenanceAnalysis.h - ObjC ARC Optimization -------------*- 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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/// \file
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///
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/// This file declares a special form of Alias Analysis called ``Provenance
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/// Analysis''. The word ``provenance'' refers to the history of the ownership
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/// of an object. Thus ``Provenance Analysis'' is an analysis which attempts to
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/// use various techniques to determine if locally
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///
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/// WARNING: This file knows about certain library functions. It recognizes them
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/// by name, and hardwires knowledge of their semantics.
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///
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/// WARNING: This file knows about how certain Objective-C library functions are
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/// used. Naive LLVM IR transformations which would otherwise be
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/// behavior-preserving may break these assumptions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
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#define LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/IR/ValueHandle.h"
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#include <utility>
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namespace llvm {
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class AAResults;
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class DataLayout;
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class PHINode;
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class SelectInst;
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class Value;
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namespace objcarc {
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/// This is similar to BasicAliasAnalysis, and it uses many of the same
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/// techniques, except it uses special ObjC-specific reasoning about pointer
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/// relationships.
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///
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/// In this context ``Provenance'' is defined as the history of an object's
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/// ownership. Thus ``Provenance Analysis'' is defined by using the notion of
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/// an ``independent provenance source'' of a pointer to determine whether or
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/// not two pointers have the same provenance source and thus could
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/// potentially be related.
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class ProvenanceAnalysis {
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AAResults *AA;
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using ValuePairTy = std::pair<const Value *, const Value *>;
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using CachedResultsTy = DenseMap<ValuePairTy, bool>;
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CachedResultsTy CachedResults;
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DenseMap<const Value *, WeakTrackingVH> UnderlyingObjCPtrCache;
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bool relatedCheck(const Value *A, const Value *B);
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bool relatedSelect(const SelectInst *A, const Value *B);
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bool relatedPHI(const PHINode *A, const Value *B);
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public:
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ProvenanceAnalysis() = default;
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ProvenanceAnalysis(const ProvenanceAnalysis &) = delete;
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ProvenanceAnalysis &operator=(const ProvenanceAnalysis &) = delete;
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void setAA(AAResults *aa) { AA = aa; }
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AAResults *getAA() const { return AA; }
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bool related(const Value *A, const Value *B);
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void clear() {
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CachedResults.clear();
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UnderlyingObjCPtrCache.clear();
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}
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};
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} // end namespace objcarc
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} // end namespace llvm
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#endif // LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
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