lib/Transforms/IPO/Internalize.cpp

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