Internalize.cpp revision f4d48e15f7af90a5b0b056cea6a21bbfa266779e 
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/Transforms/IPO.h"
18#include "llvm/Pass.h"
19#include "llvm/Module.h"
20#include "llvm/Support/CommandLine.h"
21#include "llvm/Support/Compiler.h"
22#include "llvm/Support/Debug.h"
23#include "llvm/ADT/Statistic.h"
24#include <fstream>
25#include <set>
26using namespace llvm;
27
28STATISTIC(NumFunctions, "Number of functions internalized");
29STATISTIC(NumGlobals  , "Number of global vars internalized");
30
31// APIFile - A file which contains a list of symbols that should not be marked
32// external.
33static cl::opt<std::string>
34APIFile("internalize-public-api-file", cl::value_desc("filename"),
35        cl::desc("A file containing list of symbol names to preserve"));
36
37// APIList - A list of symbols that should not be marked internal.
38static cl::list<std::string>
39APIList("internalize-public-api-list", cl::value_desc("list"),
40        cl::desc("A list of symbol names to preserve"),
41        cl::CommaSeparated);
42
43namespace {
44  class VISIBILITY_HIDDEN InternalizePass : public ModulePass {
45    std::set<std::string> ExternalNames;
46    /// If no api symbols were specified and a main function is defined,
47    /// assume the main function is the only API
48    bool AllButMain;
49  public:
50    static char ID; // Pass identification, replacement for typeid
51    explicit InternalizePass(bool AllButMain = true);
52    explicit InternalizePass(const std::vector <const char *>& exportList);
53    void LoadFile(const char *Filename);
54    virtual bool runOnModule(Module &M);
55
56    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
57      AU.setPreservesCFG();
58    }
59  };
60} // end anonymous namespace
61
62char InternalizePass::ID = 0;
63static RegisterPass<InternalizePass>
64X("internalize", "Internalize Global Symbols");
65
66InternalizePass::InternalizePass(bool AllButMain)
67  : ModulePass(&ID), AllButMain(AllButMain){
68  if (!APIFile.empty())           // If a filename is specified, use it.
69    LoadFile(APIFile.c_str());
70  if (!APIList.empty())           // If a list is specified, use it as well.
71    ExternalNames.insert(APIList.begin(), APIList.end());
72}
73
74InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
75  : ModulePass(&ID), AllButMain(false){
76  for(std::vector<const char *>::const_iterator itr = exportList.begin();
77        itr != exportList.end(); itr++) {
78    ExternalNames.insert(*itr);
79  }
80}
81
82void InternalizePass::LoadFile(const char *Filename) {
83  // Load the APIFile...
84  std::ifstream In(Filename);
85  if (!In.good()) {
86    cerr << "WARNING: Internalize couldn't load file '" << Filename
87         << "'! Continuing as if it's empty.\n";
88    return; // Just continue as if the file were empty
89  }
90  while (In) {
91    std::string Symbol;
92    In >> Symbol;
93    if (!Symbol.empty())
94      ExternalNames.insert(Symbol);
95  }
96}
97
98bool InternalizePass::runOnModule(Module &M) {
99  if (ExternalNames.empty()) {
100    // Return if we're not in 'all but main' mode and have no external api
101    if (!AllButMain)
102      return false;
103    // If no list or file of symbols was specified, check to see if there is a
104    // "main" symbol defined in the module.  If so, use it, otherwise do not
105    // internalize the module, it must be a library or something.
106    //
107    Function *MainFunc = M.getFunction("main");
108    if (MainFunc == 0 || MainFunc->isDeclaration())
109      return false;  // No main found, must be a library...
110
111    // Preserve main, internalize all else.
112    ExternalNames.insert(MainFunc->getName());
113  }
114
115  bool Changed = false;
116
117  // Mark all functions not in the api as internal.
118  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
119    if (!I->isDeclaration() &&         // Function must be defined here
120        !I->hasInternalLinkage() &&  // Can't already have internal linkage
121        !ExternalNames.count(I->getName())) {// Not marked to keep external?
122      I->setLinkage(GlobalValue::InternalLinkage);
123      Changed = true;
124      ++NumFunctions;
125      DOUT << "Internalizing func " << I->getName() << "\n";
126    }
127
128  // Never internalize the llvm.used symbol.  It is used to implement
129  // attribute((used)).
130  ExternalNames.insert("llvm.used");
131
132  // Never internalize anchors used by the machine module info, else the info
133  // won't find them.  (see MachineModuleInfo.)
134  ExternalNames.insert("llvm.dbg.compile_units");
135  ExternalNames.insert("llvm.dbg.global_variables");
136  ExternalNames.insert("llvm.dbg.subprograms");
137  ExternalNames.insert("llvm.global_ctors");
138  ExternalNames.insert("llvm.global_dtors");
139  ExternalNames.insert("llvm.noinline");
140  ExternalNames.insert("llvm.global.annotations");
141
142  // Mark all global variables with initializers that are not in the api as
143  // internal as well.
144  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
145       I != E; ++I)
146    if (!I->isDeclaration() && !I->hasInternalLinkage() &&
147        !ExternalNames.count(I->getName())) {
148      I->setLinkage(GlobalValue::InternalLinkage);
149      Changed = true;
150      ++NumGlobals;
151      DOUT << "Internalized gvar " << I->getName() << "\n";
152    }
153
154  return Changed;
155}
156
157ModulePass *llvm::createInternalizePass(bool AllButMain) {
158  return new InternalizePass(AllButMain);
159}
160
161ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
162  return new InternalizePass(el);
163}
164