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4977850092
It's not needed anymore with delayed instruction deletion. It was used for two purposes: 1. For analysis, which cache instructions, to avoid dangling instruction pointers 2. For passes, which maintain worklists of instructions, to remove a deleted instructions from the worklist. This is now done by checking SILInstruction::isDeleted().
113 lines
4.0 KiB
C++
113 lines
4.0 KiB
C++
//===--- RCIdentityAnalysis.h -----------------------------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This is an analysis that determines the ref count identity (i.e. gc root) of
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// a pointer. Any values with the same ref count identity are able to be
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// retained and released interchangeably.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SILOPTIMIZER_ANALYSIS_RCIDENTITYANALYSIS_H
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#define SWIFT_SILOPTIMIZER_ANALYSIS_RCIDENTITYANALYSIS_H
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#include "swift/SIL/SILValue.h"
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#include "swift/SIL/SILArgument.h"
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#include "swift/SILOptimizer/Analysis/Analysis.h"
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#include "swift/SILOptimizer/Analysis/DominanceAnalysis.h"
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#include "swift/SILOptimizer/PassManager/PassManager.h"
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namespace swift {
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/// Limit the size of the rc identity cache. We keep a cache per function.
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constexpr unsigned MaxRCIdentityCacheSize = 64;
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class DominanceAnalysis;
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/// This class is a simple wrapper around an identity cache.
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class RCIdentityFunctionInfo {
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llvm::DenseSet<SILArgument *> VisitedArgs;
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// RC identity cache.
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llvm::DenseMap<SILValue, SILValue> RCCache;
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DominanceAnalysis *DA;
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/// This number is arbitrary and conservative. At some point if compile time
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/// is not an issue, this value should be made more aggressive (i.e. greater).
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enum { MaxRecursionDepth = 16 };
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public:
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RCIdentityFunctionInfo(DominanceAnalysis *D) : VisitedArgs(),
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DA(D) {}
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SILValue getRCIdentityRoot(SILValue V);
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/// Return all recursive users of V, looking through users which propagate
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/// RCIdentity.
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///
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/// *NOTE* This ignores obvious ARC escapes where the a potential
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/// user of the RC is not managed by ARC. For instance
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/// unchecked_trivial_bit_cast.
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void getRCUses(SILValue V, SmallVectorImpl<Operand *> &Uses);
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/// A helper method that calls getRCUses and then maps each operand to the
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/// operands user and then uniques the list.
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///
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/// *NOTE* The routine asserts that the passed in Users array is empty for
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/// simplicity. If needed this can be changed, but it is not necessary given
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/// current uses.
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void getRCUsers(SILValue V, SmallVectorImpl<SILInstruction *> &Users);
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/// Like getRCUses except uses a callback to prevent the need for an
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/// intermediate array.
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void visitRCUses(SILValue V, function_ref<void(Operand *)> Visitor);
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private:
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SILValue getRCIdentityRootInner(SILValue V, unsigned RecursionDepth);
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SILValue stripRCIdentityPreservingOps(SILValue V, unsigned RecursionDepth);
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SILValue stripRCIdentityPreservingArgs(SILValue V, unsigned RecursionDepth);
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SILValue stripOneRCIdentityIncomingValue(SILArgument *Arg, SILValue V);
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bool findDominatingNonPayloadedEdge(SILBasicBlock *IncomingEdgeBB,
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SILValue RCIdentity);
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};
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class RCIdentityAnalysis : public FunctionAnalysisBase<RCIdentityFunctionInfo> {
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DominanceAnalysis *DA;
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public:
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RCIdentityAnalysis(SILModule *)
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: FunctionAnalysisBase<RCIdentityFunctionInfo>(
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SILAnalysisKind::RCIdentity),
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DA(nullptr) {}
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RCIdentityAnalysis(const RCIdentityAnalysis &) = delete;
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RCIdentityAnalysis &operator=(const RCIdentityAnalysis &) = delete;
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static bool classof(const SILAnalysis *S) {
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return S->getKind() == SILAnalysisKind::RCIdentity;
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}
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virtual void initialize(SILPassManager *PM) override;
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virtual std::unique_ptr<RCIdentityFunctionInfo>
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newFunctionAnalysis(SILFunction *F) override {
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return std::make_unique<RCIdentityFunctionInfo>(DA);
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}
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virtual bool shouldInvalidate(SILAnalysis::InvalidationKind K) override {
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return true;
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}
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};
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} // end swift namespace
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#endif
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