Internalize.cpp revision 4e78908b9453edf7d0907d4811c469a630aff560 
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} // end anonymous namespace
57
58char InternalizePass::ID = 0;
59static RegisterPass<InternalizePass>
60X("internalize", "Internalize Global Symbols");
61
62InternalizePass::InternalizePass(bool AllButMain)
63  : ModulePass((intptr_t)&ID), AllButMain(AllButMain){
64  if (!APIFile.empty())           // If a filename is specified, use it.
65    LoadFile(APIFile.c_str());
66  if (!APIList.empty())           // If a list is specified, use it as well.
67    ExternalNames.insert(APIList.begin(), APIList.end());
68}
69
70InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
71  : ModulePass((intptr_t)&ID), AllButMain(false){
72  for(std::vector<const char *>::const_iterator itr = exportList.begin();
73        itr != exportList.end(); itr++) {
74    ExternalNames.insert(*itr);
75  }
76}
77
78void InternalizePass::LoadFile(const char *Filename) {
79  // Load the APIFile...
80  std::ifstream In(Filename);
81  if (!In.good()) {
82    cerr << "WARNING: Internalize couldn't load file '" << Filename
83         << "'! Continuing as if it's empty.\n";
84    return; // Just continue as if the file were empty
85  }
86  while (In) {
87    std::string Symbol;
88    In >> Symbol;
89    if (!Symbol.empty())
90      ExternalNames.insert(Symbol);
91  }
92}
93
94bool InternalizePass::runOnModule(Module &M) {
95  if (ExternalNames.empty()) {
96    // Return if we're not in 'all but main' mode and have no external api
97    if (!AllButMain)
98      return false;
99    // If no list or file of symbols was specified, check to see if there is a
100    // "main" symbol defined in the module.  If so, use it, otherwise do not
101    // internalize the module, it must be a library or something.
102    //
103    Function *MainFunc = M.getFunction("main");
104    if (MainFunc == 0 || MainFunc->isDeclaration())
105      return false;  // No main found, must be a library...
106
107    // Preserve main, internalize all else.
108    ExternalNames.insert(MainFunc->getName());
109  }
110
111  bool Changed = false;
112
113  // Mark all functions not in the api as internal.
114  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
115    if (!I->isDeclaration() &&         // Function must be defined here
116        !I->hasInternalLinkage() &&  // Can't already have internal linkage
117        !ExternalNames.count(I->getName())) {// Not marked to keep external?
118      I->setLinkage(GlobalValue::InternalLinkage);
119      Changed = true;
120      ++NumFunctions;
121      DOUT << "Internalizing func " << I->getName() << "\n";
122    }
123
124  // Never internalize the llvm.used symbol.  It is used to implement
125  // attribute((used)).
126  ExternalNames.insert("llvm.used");
127
128  // Never internalize anchors used by the machine module info, else the info
129  // won't find them.  (see MachineModuleInfo.)
130  ExternalNames.insert("llvm.dbg.compile_units");
131  ExternalNames.insert("llvm.dbg.global_variables");
132  ExternalNames.insert("llvm.dbg.subprograms");
133  ExternalNames.insert("llvm.global_ctors");
134  ExternalNames.insert("llvm.global_dtors");
135  ExternalNames.insert("llvm.noinline");
136  ExternalNames.insert("llvm.global.annotations");
137
138  // Mark all global variables with initializers that are not in the api as
139  // internal as well.
140  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
141       I != E; ++I)
142    if (!I->isDeclaration() && !I->hasInternalLinkage() &&
143        !ExternalNames.count(I->getName())) {
144      I->setLinkage(GlobalValue::InternalLinkage);
145      Changed = true;
146      ++NumGlobals;
147      DOUT << "Internalized gvar " << I->getName() << "\n";
148    }
149
150  return Changed;
151}
152
153ModulePass *llvm::createInternalizePass(bool AllButMain) {
154  return new InternalizePass(AllButMain);
155}
156
157ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
158  return new InternalizePass(el);
159}
160