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09b5b54897
Summary: Since the value stored in the cache might be deleted or replaced with something else, we need to use tracking ValueHandlers instead of plain Value pointers. It was discovered in one of internal builds, and unfortunately there is no small reproducer for the issue. The cache was introduced in rL327328. Reviewers: ahatanak, pete Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D48407 llvm-svn: 335201
88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
//===- ProvenanceAnalysis.h - ObjC ARC Optimization -------------*- 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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/// \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/Analysis/AliasAnalysis.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 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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AliasAnalysis *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, const DataLayout &DL);
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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(AliasAnalysis *aa) { AA = aa; }
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AliasAnalysis *getAA() const { return AA; }
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bool related(const Value *A, const Value *B, const DataLayout &DL);
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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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