71 lines
2.5 KiB
C
71 lines
2.5 KiB
C
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//===-- GlobalDCE.h - DCE unreachable internal functions ------------------===//
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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 transform is designed to eliminate unreachable internal globals from the
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// program. It uses an aggressive algorithm, searching out globals that are
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// known to be alive. After it finds all of the globals which are needed, it
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// deletes whatever is left over. This allows it to delete recursive chunks of
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// the program which are unreachable.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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#define LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/PassManager.h"
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#include <unordered_map>
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namespace llvm {
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/// Pass to remove unused function declarations.
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class GlobalDCEPass : public PassInfoMixin<GlobalDCEPass> {
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public:
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PreservedAnalyses run(Module &M, ModuleAnalysisManager &);
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private:
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SmallPtrSet<GlobalValue*, 32> AliveGlobals;
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/// Global -> Global that uses this global.
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DenseMap<GlobalValue *, SmallPtrSet<GlobalValue *, 4>> GVDependencies;
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/// Constant -> Globals that use this global cache.
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std::unordered_map<Constant *, SmallPtrSet<GlobalValue *, 8>>
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ConstantDependenciesCache;
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/// Comdat -> Globals in that Comdat section.
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std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers;
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/// !type metadata -> set of (vtable, offset) pairs
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DenseMap<Metadata *, SmallSet<std::pair<GlobalVariable *, uint64_t>, 4>>
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TypeIdMap;
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// Global variables which are vtables, and which we have enough information
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// about to safely do dead virtual function elimination.
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SmallPtrSet<GlobalValue *, 32> VFESafeVTables;
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void UpdateGVDependencies(GlobalValue &GV);
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void MarkLive(GlobalValue &GV,
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SmallVectorImpl<GlobalValue *> *Updates = nullptr);
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bool RemoveUnusedGlobalValue(GlobalValue &GV);
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// Dead virtual function elimination.
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void AddVirtualFunctionDependencies(Module &M);
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void ScanVTables(Module &M);
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void ScanTypeCheckedLoadIntrinsics(Module &M);
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void ScanVTableLoad(Function *Caller, Metadata *TypeId, uint64_t CallOffset);
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void ComputeDependencies(Value *V, SmallPtrSetImpl<GlobalValue *> &U);
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};
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}
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#endif // LLVM_TRANSFORMS_IPO_GLOBALDCE_H
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