1 //===-- GlobalDCE.h - DCE unreachable internal functions ------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This transform is designed to eliminate unreachable internal globals from the 11 // program. It uses an aggressive algorithm, searching out globals that are 12 // known to be alive. After it finds all of the globals which are needed, it 13 // deletes whatever is left over. This allows it to delete recursive chunks of 14 // the program which are unreachable. 15 // 16 //===----------------------------------------------------------------------===// 17 18 #ifndef LLVM_TRANSFORMS_IPO_GLOBALDCE_H 19 #define LLVM_TRANSFORMS_IPO_GLOBALDCE_H 20 21 #include "llvm/IR/Module.h" 22 #include "llvm/IR/PassManager.h" 23 #include <unordered_map> 24 25 namespace llvm { 26 27 /// Pass to remove unused function declarations. 28 class GlobalDCEPass : public PassInfoMixin<GlobalDCEPass> { 29 public: 30 PreservedAnalyses run(Module &M, ModuleAnalysisManager &); 31 32 private: 33 SmallPtrSet<GlobalValue*, 32> AliveGlobals; 34 SmallPtrSet<Constant *, 8> SeenConstants; 35 std::unordered_multimap<Comdat *, GlobalValue *> ComdatMembers; 36 37 /// Mark the specific global value as needed, and 38 /// recursively mark anything that it uses as also needed. 39 void GlobalIsNeeded(GlobalValue *GV); 40 void MarkUsedGlobalsAsNeeded(Constant *C); 41 bool RemoveUnusedGlobalValue(GlobalValue &GV); 42 }; 43 44 } 45 46 #endif // LLVM_TRANSFORMS_IPO_GLOBALDCE_H 47
