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 and variables in the input module. 11 // If the function or variable is not in the list of external names given to 12 // the pass it is marked as internal. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #define DEBUG_TYPE "internalize" 17 #include "llvm/Transforms/IPO.h" 18 #include "llvm/ADT/SmallPtrSet.h" 19 #include "llvm/ADT/Statistic.h" 20 #include "llvm/Analysis/CallGraph.h" 21 #include "llvm/IR/Module.h" 22 #include "llvm/Pass.h" 23 #include "llvm/Support/CommandLine.h" 24 #include "llvm/Support/Debug.h" 25 #include "llvm/Support/raw_ostream.h" 26 #include "llvm/Transforms/Utils/ModuleUtils.h" 27 #include <fstream> 28 #include <set> 29 using namespace llvm; 30 31 STATISTIC(NumAliases , "Number of aliases internalized"); 32 STATISTIC(NumFunctions, "Number of functions internalized"); 33 STATISTIC(NumGlobals , "Number of global vars internalized"); 34 35 // APIFile - A file which contains a list of symbols that should not be marked 36 // external. 37 static cl::opt<std::string> 38 APIFile("internalize-public-api-file", cl::value_desc("filename"), 39 cl::desc("A file containing list of symbol names to preserve")); 40 41 // APIList - A list of symbols that should not be marked internal. 42 static cl::list<std::string> 43 APIList("internalize-public-api-list", cl::value_desc("list"), 44 cl::desc("A list of symbol names to preserve"), 45 cl::CommaSeparated); 46 47 namespace { 48 class InternalizePass : public ModulePass { 49 std::set<std::string> ExternalNames; 50 public: 51 static char ID; // Pass identification, replacement for typeid 52 explicit InternalizePass(); 53 explicit InternalizePass(ArrayRef<const char *> exportList); 54 void LoadFile(const char *Filename); 55 void ClearExportList(); 56 void AddToExportList(const std::string &val); 57 virtual bool runOnModule(Module &M); 58 59 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 60 AU.setPreservesCFG(); 61 AU.addPreserved<CallGraph>(); 62 } 63 }; 64 } // end anonymous namespace 65 66 char InternalizePass::ID = 0; 67 INITIALIZE_PASS(InternalizePass, "internalize", 68 "Internalize Global Symbols", false, false) 69 70 InternalizePass::InternalizePass() 71 : ModulePass(ID) { 72 initializeInternalizePassPass(*PassRegistry::getPassRegistry()); 73 if (!APIFile.empty()) // If a filename is specified, use it. 74 LoadFile(APIFile.c_str()); 75 if (!APIList.empty()) // If a list is specified, use it as well. 76 ExternalNames.insert(APIList.begin(), APIList.end()); 77 } 78 79 InternalizePass::InternalizePass(ArrayRef<const char *> exportList) 80 : ModulePass(ID){ 81 initializeInternalizePassPass(*PassRegistry::getPassRegistry()); 82 for(ArrayRef<const char *>::const_iterator itr = exportList.begin(); 83 itr != exportList.end(); itr++) { 84 ExternalNames.insert(*itr); 85 } 86 } 87 88 void InternalizePass::LoadFile(const char *Filename) { 89 // Load the APIFile... 90 std::ifstream In(Filename); 91 if (!In.good()) { 92 errs() << "WARNING: Internalize couldn't load file '" << Filename 93 << "'! Continuing as if it's empty.\n"; 94 return; // Just continue as if the file were empty 95 } 96 while (In) { 97 std::string Symbol; 98 In >> Symbol; 99 if (!Symbol.empty()) 100 ExternalNames.insert(Symbol); 101 } 102 } 103 104 void InternalizePass::ClearExportList() { 105 ExternalNames.clear(); 106 } 107 108 void InternalizePass::AddToExportList(const std::string &val) { 109 ExternalNames.insert(val); 110 } 111 112 bool InternalizePass::runOnModule(Module &M) { 113 CallGraph *CG = getAnalysisIfAvailable<CallGraph>(); 114 CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0; 115 bool Changed = false; 116 117 // Never internalize functions which code-gen might insert. 118 // FIXME: We should probably add this (and the __stack_chk_guard) via some 119 // type of call-back in CodeGen. 120 ExternalNames.insert("__stack_chk_fail"); 121 122 SmallPtrSet<GlobalValue *, 8> Used; 123 collectUsedGlobalVariables(M, Used, false); 124 125 // We must assume that globals in llvm.used have a reference that not even 126 // the linker can see, so we don't internalize them. 127 // For llvm.compiler.used the situation is a bit fuzzy. The assembler and 128 // linker can drop those symbols. If this pass is running as part of LTO, 129 // one might think that it could just drop llvm.compiler.used. The problem 130 // is that even in LTO llvm doesn't see every reference. For example, 131 // we don't see references from function local inline assembly. To be 132 // conservative, we internalize symbols in llvm.compiler.used, but we 133 // keep llvm.compiler.used so that the symbol is not deleted by llvm. 134 for (SmallPtrSet<GlobalValue *, 8>::iterator I = Used.begin(), E = Used.end(); 135 I != E; ++I) { 136 GlobalValue *V = *I; 137 ExternalNames.insert(V->getName()); 138 } 139 140 // Mark all functions not in the api as internal. 141 // FIXME: maybe use private linkage? 142 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 143 if (!I->isDeclaration() && // Function must be defined here 144 // Available externally is really just a "declaration with a body". 145 !I->hasAvailableExternallyLinkage() && 146 !I->hasLocalLinkage() && // Can't already have internal linkage 147 !ExternalNames.count(I->getName())) {// Not marked to keep external? 148 I->setLinkage(GlobalValue::InternalLinkage); 149 // Remove a callgraph edge from the external node to this function. 150 if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]); 151 Changed = true; 152 ++NumFunctions; 153 DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n"); 154 } 155 156 // Never internalize the llvm.used symbol. It is used to implement 157 // attribute((used)). 158 // FIXME: Shouldn't this just filter on llvm.metadata section?? 159 ExternalNames.insert("llvm.used"); 160 ExternalNames.insert("llvm.compiler.used"); 161 162 // Never internalize anchors used by the machine module info, else the info 163 // won't find them. (see MachineModuleInfo.) 164 ExternalNames.insert("llvm.global_ctors"); 165 ExternalNames.insert("llvm.global_dtors"); 166 ExternalNames.insert("llvm.global.annotations"); 167 168 // Never internalize symbols code-gen inserts. 169 ExternalNames.insert("__stack_chk_guard"); 170 171 // Mark all global variables with initializers that are not in the api as 172 // internal as well. 173 // FIXME: maybe use private linkage? 174 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 175 I != E; ++I) 176 if (!I->isDeclaration() && !I->hasLocalLinkage() && 177 // Available externally is really just a "declaration with a body". 178 !I->hasAvailableExternallyLinkage() && 179 !ExternalNames.count(I->getName())) { 180 I->setLinkage(GlobalValue::InternalLinkage); 181 Changed = true; 182 ++NumGlobals; 183 DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n"); 184 } 185 186 // Mark all aliases that are not in the api as internal as well. 187 for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); 188 I != E; ++I) 189 if (!I->isDeclaration() && !I->hasInternalLinkage() && 190 // Available externally is really just a "declaration with a body". 191 !I->hasAvailableExternallyLinkage() && 192 !ExternalNames.count(I->getName())) { 193 I->setLinkage(GlobalValue::InternalLinkage); 194 Changed = true; 195 ++NumAliases; 196 DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n"); 197 } 198 199 return Changed; 200 } 201 202 ModulePass *llvm::createInternalizePass() { 203 return new InternalizePass(); 204 } 205 206 ModulePass *llvm::createInternalizePass(ArrayRef<const char *> el) { 207 return new InternalizePass(el); 208 } 209
