1 //===-- StripDeadPrototypes.cpp - Remove unused function declarations ----===// 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 pass loops over all of the functions in the input module, looking for 11 // dead declarations and removes them. Dead declarations are declarations of 12 // functions for which no implementation is available (i.e., declarations for 13 // unused library functions). 14 // 15 //===----------------------------------------------------------------------===// 16 17 #define DEBUG_TYPE "strip-dead-prototypes" 18 #include "llvm/Transforms/IPO.h" 19 #include "llvm/Pass.h" 20 #include "llvm/Module.h" 21 #include "llvm/ADT/Statistic.h" 22 using namespace llvm; 23 24 STATISTIC(NumDeadPrototypes, "Number of dead prototypes removed"); 25 26 namespace { 27 28 /// @brief Pass to remove unused function declarations. 29 class StripDeadPrototypesPass : public ModulePass { 30 public: 31 static char ID; // Pass identification, replacement for typeid 32 StripDeadPrototypesPass() : ModulePass(ID) { 33 initializeStripDeadPrototypesPassPass(*PassRegistry::getPassRegistry()); 34 } 35 virtual bool runOnModule(Module &M); 36 }; 37 38 } // end anonymous namespace 39 40 char StripDeadPrototypesPass::ID = 0; 41 INITIALIZE_PASS(StripDeadPrototypesPass, "strip-dead-prototypes", 42 "Strip Unused Function Prototypes", false, false) 43 44 bool StripDeadPrototypesPass::runOnModule(Module &M) { 45 bool MadeChange = false; 46 47 // Erase dead function prototypes. 48 for (Module::iterator I = M.begin(), E = M.end(); I != E; ) { 49 Function *F = I++; 50 // Function must be a prototype and unused. 51 if (F->isDeclaration() && F->use_empty()) { 52 F->eraseFromParent(); 53 ++NumDeadPrototypes; 54 MadeChange = true; 55 } 56 } 57 58 // Erase dead global var prototypes. 59 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 60 I != E; ) { 61 GlobalVariable *GV = I++; 62 // Global must be a prototype and unused. 63 if (GV->isDeclaration() && GV->use_empty()) 64 GV->eraseFromParent(); 65 } 66 67 // Return an indication of whether we changed anything or not. 68 return MadeChange; 69 } 70 71 ModulePass *llvm::createStripDeadPrototypesPass() { 72 return new StripDeadPrototypesPass(); 73 } 74
