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/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 VISIBILITY_HIDDEN 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 static RegisterPass<InternalizePass>
  67 X("internalize", "Internalize Global Symbols");
  68
  69 InternalizePass::InternalizePass(bool AllButMain)
  70   : ModulePass(&ID), AllButMain(AllButMain){
  71   if (!APIFile.empty())           // If a filename is specified, use it.
  72     LoadFile(APIFile.c_str());
  73   if (!APIList.empty())           // If a list is specified, use it as well.
  74     ExternalNames.insert(APIList.begin(), APIList.end());
  75 }
  76
  77 InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
  78   : ModulePass(&ID), AllButMain(false){
  79   for(std::vector<const char *>::const_iterator itr = exportList.begin();
  80         itr != exportList.end(); itr++) {
  81     ExternalNames.insert(*itr);
  82   }
  83 }
  84
  85 void InternalizePass::LoadFile(const char *Filename) {
  86   // Load the APIFile...
  87   std::ifstream In(Filename);
  88   if (!In.good()) {
  89     cerr << "WARNING: Internalize couldn't load file '" << Filename
  90          << "'! Continuing as if it's empty.\n";
  91     return; // Just continue as if the file were empty
  92   }
  93   while (In) {
  94     std::string Symbol;
  95     In >> Symbol;
  96     if (!Symbol.empty())
  97       ExternalNames.insert(Symbol);
  98   }
  99 }
 100
 101 bool InternalizePass::runOnModule(Module &M) {
 102   CallGraph *CG = getAnalysisIfAvailable<CallGraph>();
 103   CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
 104
 105   if (ExternalNames.empty()) {
 106     // Return if we're not in 'all but main' mode and have no external api
 107     if (!AllButMain)
 108       return false;
 109     // If no list or file of symbols was specified, check to see if there is a
 110     // "main" symbol defined in the module.  If so, use it, otherwise do not
 111     // internalize the module, it must be a library or something.
 112     //
 113     Function *MainFunc = M.getFunction("main");
 114     if (MainFunc == 0 || MainFunc->isDeclaration())
 115       return false;  // No main found, must be a library...
 116
 117     // Preserve main, internalize all else.
 118     ExternalNames.insert(MainFunc->getName());
 119   }
 120
 121   bool Changed = false;
 122
 123   // Mark all functions not in the api as internal.
 124   // FIXME: maybe use private linkage?
 125   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
 126     if (!I->isDeclaration() &&         // Function must be defined here
 127         !I->hasLocalLinkage() &&  // Can't already have internal linkage
 128         !ExternalNames.count(I->getName())) {// Not marked to keep external?
 129       I->setLinkage(GlobalValue::InternalLinkage);
 130       // Remove a callgraph edge from the external node to this function.
 131       if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
 132       Changed = true;
 133       ++NumFunctions;
 134       DOUT << "Internalizing func " << I->getName() << "\n";
 135     }
 136
 137   // Never internalize the llvm.used symbol.  It is used to implement
 138   // attribute((used)).
 139   ExternalNames.insert("llvm.used");
 140
 141   // Never internalize anchors used by the machine module info, else the info
 142   // won't find them.  (see MachineModuleInfo.)
 143   ExternalNames.insert("llvm.dbg.compile_units");
 144   ExternalNames.insert("llvm.dbg.global_variables");
 145   ExternalNames.insert("llvm.dbg.subprograms");
 146   ExternalNames.insert("llvm.global_ctors");
 147   ExternalNames.insert("llvm.global_dtors");
 148   ExternalNames.insert("llvm.noinline");
 149   ExternalNames.insert("llvm.global.annotations");
 150
 151   // Mark all global variables with initializers that are not in the api as
 152   // internal as well.
 153   // FIXME: maybe use private linkage?
 154   for (Module::global_iterator I = M.global_begin(), E = M.global_end();
 155        I != E; ++I)
 156     if (!I->isDeclaration() && !I->hasLocalLinkage() &&
 157         !ExternalNames.count(I->getName())) {
 158       I->setLinkage(GlobalValue::InternalLinkage);
 159       Changed = true;
 160       ++NumGlobals;
 161       DOUT << "Internalized gvar " << I->getName() << "\n";
 162     }
 163
 164   // Mark all aliases that are not in the api as internal as well.
 165   for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
 166        I != E; ++I)
 167     if (!I->isDeclaration() && !I->hasInternalLinkage() &&
 168         !ExternalNames.count(I->getName())) {
 169       I->setLinkage(GlobalValue::InternalLinkage);
 170       Changed = true;
 171       ++NumAliases;
 172       DOUT << "Internalized alias " << I->getName() << "\n";
 173     }
 174
 175   return Changed;
 176 }
 177
 178 ModulePass *llvm::createInternalizePass(bool AllButMain) {
 179   return new InternalizePass(AllButMain);
 180 }
 181
 182 ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
 183   return new InternalizePass(el);
 184 }