1 //===-- Internalize.cpp - Mark functions internal -------------------------===// 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 a 11 // main function. If a main function is found, all other functions and all 12 // global variables with initializers are marked as internal. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #define DEBUG_TYPE "internalize" 17 #include "llvm/Analysis/CallGraph.h" 18 #include "llvm/Transforms/IPO.h" 19 #include "llvm/Pass.h" 20 #include "llvm/Module.h" 21 #include "llvm/Support/CommandLine.h" 22 #include "llvm/Support/Debug.h" 23 #include "llvm/Support/raw_ostream.h" 24 #include "llvm/ADT/Statistic.h" 25 #include <fstream> 26 #include <set> 27 using namespace llvm; 28 29 STATISTIC(NumAliases , "Number of aliases internalized"); 30 STATISTIC(NumFunctions, "Number of functions internalized"); 31 STATISTIC(NumGlobals , "Number of global vars internalized"); 32 33 // APIFile - A file which contains a list of symbols that should not be marked 34 // external. 35 static cl::opt<std::string> 36 APIFile("internalize-public-api-file", cl::value_desc("filename"), 37 cl::desc("A file containing list of symbol names to preserve")); 38 39 // APIList - A list of symbols that should not be marked internal. 40 static cl::list<std::string> 41 APIList("internalize-public-api-list", cl::value_desc("list"), 42 cl::desc("A list of symbol names to preserve"), 43 cl::CommaSeparated); 44 45 namespace { 46 class InternalizePass : public ModulePass { 47 std::set<std::string> ExternalNames; 48 /// If no api symbols were specified and a main function is defined, 49 /// assume the main function is the only API 50 bool AllButMain; 51 public: 52 static char ID; // Pass identification, replacement for typeid 53 explicit InternalizePass(bool AllButMain = true); 54 explicit InternalizePass(const std::vector <const char *>& exportList); 55 void LoadFile(const char *Filename); 56 virtual bool runOnModule(Module &M); 57 58 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 59 AU.setPreservesCFG(); 60 AU.addPreserved<CallGraph>(); 61 } 62 }; 63 } // end anonymous namespace 64 65 char InternalizePass::ID = 0; 66 INITIALIZE_PASS(InternalizePass, "internalize", 67 "Internalize Global Symbols", false, false) 68 69 InternalizePass::InternalizePass(bool AllButMain) 70 : ModulePass(ID), AllButMain(AllButMain){ 71 initializeInternalizePassPass(*PassRegistry::getPassRegistry()); 72 if (!APIFile.empty()) // If a filename is specified, use it. 73 LoadFile(APIFile.c_str()); 74 if (!APIList.empty()) // If a list is specified, use it as well. 75 ExternalNames.insert(APIList.begin(), APIList.end()); 76 } 77 78 InternalizePass::InternalizePass(const std::vector<const char *>&exportList) 79 : ModulePass(ID), AllButMain(false){ 80 initializeInternalizePassPass(*PassRegistry::getPassRegistry()); 81 for(std::vector<const char *>::const_iterator itr = exportList.begin(); 82 itr != exportList.end(); itr++) { 83 ExternalNames.insert(*itr); 84 } 85 } 86 87 void InternalizePass::LoadFile(const char *Filename) { 88 // Load the APIFile... 89 std::ifstream In(Filename); 90 if (!In.good()) { 91 errs() << "WARNING: Internalize couldn't load file '" << Filename 92 << "'! Continuing as if it's empty.\n"; 93 return; // Just continue as if the file were empty 94 } 95 while (In) { 96 std::string Symbol; 97 In >> Symbol; 98 if (!Symbol.empty()) 99 ExternalNames.insert(Symbol); 100 } 101 } 102 103 bool InternalizePass::runOnModule(Module &M) { 104 CallGraph *CG = getAnalysisIfAvailable<CallGraph>(); 105 CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0; 106 107 if (ExternalNames.empty()) { 108 // Return if we're not in 'all but main' mode and have no external api 109 if (!AllButMain) 110 return false; 111 // If no list or file of symbols was specified, check to see if there is a 112 // "main" symbol defined in the module. If so, use it, otherwise do not 113 // internalize the module, it must be a library or something. 114 // 115 Function *MainFunc = M.getFunction("main"); 116 if (MainFunc == 0 || MainFunc->isDeclaration()) 117 return false; // No main found, must be a library... 118 119 // Preserve main, internalize all else. 120 ExternalNames.insert(MainFunc->getName()); 121 } 122 123 bool Changed = false; 124 125 // Never internalize functions which code-gen might insert. 126 // FIXME: We should probably add this (and the __stack_chk_guard) via some 127 // type of call-back in CodeGen. 128 ExternalNames.insert("__stack_chk_fail"); 129 130 // Mark all functions not in the api as internal. 131 // FIXME: maybe use private linkage? 132 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 133 if (!I->isDeclaration() && // Function must be defined here 134 // Available externally is really just a "declaration with a body". 135 !I->hasAvailableExternallyLinkage() && 136 !I->hasLocalLinkage() && // Can't already have internal linkage 137 !ExternalNames.count(I->getName())) {// Not marked to keep external? 138 I->setLinkage(GlobalValue::InternalLinkage); 139 // Remove a callgraph edge from the external node to this function. 140 if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]); 141 Changed = true; 142 ++NumFunctions; 143 DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n"); 144 } 145 146 // Never internalize the llvm.used symbol. It is used to implement 147 // attribute((used)). 148 // FIXME: Shouldn't this just filter on llvm.metadata section?? 149 ExternalNames.insert("llvm.used"); 150 ExternalNames.insert("llvm.compiler.used"); 151 152 // Never internalize anchors used by the machine module info, else the info 153 // won't find them. (see MachineModuleInfo.) 154 ExternalNames.insert("llvm.global_ctors"); 155 ExternalNames.insert("llvm.global_dtors"); 156 ExternalNames.insert("llvm.global.annotations"); 157 158 // Never internalize symbols code-gen inserts. 159 ExternalNames.insert("__stack_chk_guard"); 160 161 // Mark all global variables with initializers that are not in the api as 162 // internal as well. 163 // FIXME: maybe use private linkage? 164 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 165 I != E; ++I) 166 if (!I->isDeclaration() && !I->hasLocalLinkage() && 167 // Available externally is really just a "declaration with a body". 168 !I->hasAvailableExternallyLinkage() && 169 !ExternalNames.count(I->getName())) { 170 I->setLinkage(GlobalValue::InternalLinkage); 171 Changed = true; 172 ++NumGlobals; 173 DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n"); 174 } 175 176 // Mark all aliases that are not in the api as internal as well. 177 for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); 178 I != E; ++I) 179 if (!I->isDeclaration() && !I->hasInternalLinkage() && 180 // Available externally is really just a "declaration with a body". 181 !I->hasAvailableExternallyLinkage() && 182 !ExternalNames.count(I->getName())) { 183 I->setLinkage(GlobalValue::InternalLinkage); 184 Changed = true; 185 ++NumAliases; 186 DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n"); 187 } 188 189 return Changed; 190 } 191 192 ModulePass *llvm::createInternalizePass(bool AllButMain) { 193 return new InternalizePass(AllButMain); 194 } 195 196 ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) { 197 return new InternalizePass(el); 198 } 199
