| //===-- GlobalDCE.h - DCE unreachable internal functions ------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This transform is designed to eliminate unreachable internal globals from the |
| // program. It uses an aggressive algorithm, searching out globals that are |
| // known to be alive. After it finds all of the globals which are needed, it |
| // deletes whatever is left over. This allows it to delete recursive chunks of |
| // the program which are unreachable. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_TRANSFORMS_IPO_GLOBALDCE_H |
| #define LLVM_TRANSFORMS_IPO_GLOBALDCE_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/PassManager.h" |
| #include <unordered_map> |
| |
| namespace llvm { |
| |
| /// Pass to remove unused function declarations. |
| class GlobalDCEPass : public PassInfoMixin<GlobalDCEPass> { |
| public: |
| PreservedAnalyses run(Module &M, ModuleAnalysisManager &); |
| |
| private: |
| SmallPtrSet<GlobalValue*, 32> AliveGlobals; |
| |
| /// Global -> Global that uses this global. |
| DenseMap<GlobalValue *, SmallPtrSet<GlobalValue *, 4>> GVDependencies; |
| |
| /// Constant -> Globals that use this global cache. |
| std::unordered_map<Constant *, SmallPtrSet<GlobalValue *, 8>> |
| ConstantDependenciesCache; |
| |
| /// Comdat -> Globals in that Comdat section. |
| std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers; |
| |
| void UpdateGVDependencies(GlobalValue &GV); |
| void MarkLive(GlobalValue &GV, |
| SmallVectorImpl<GlobalValue *> *Updates = nullptr); |
| bool RemoveUnusedGlobalValue(GlobalValue &GV); |
| |
| void ComputeDependencies(Value *V, SmallPtrSetImpl<GlobalValue *> &U); |
| }; |
| |
| } |
| |
| #endif // LLVM_TRANSFORMS_IPO_GLOBALDCE_H |