summaryrefslogtreecommitdiff
path: root/lib/Transforms/IPO/Internalize.cpp
blob: 17de131590f1538223f752650bec395766b23905 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
//===-- Internalize.cpp - Mark functions internal -------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass loops over all of the functions in the input module, looking for a
// main function.  If a main function is found, all other functions and all
// global variables with initializers are marked as internal.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "internalize"
#include "llvm/Transforms/IPO.h"
#include "llvm/Pass.h"
#include "llvm/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
#include <fstream>
#include <set>
using namespace llvm;

STATISTIC(NumFunctions, "Number of functions internalized");
STATISTIC(NumGlobals  , "Number of global vars internalized");

namespace {

  // APIFile - A file which contains a list of symbols that should not be marked
  // external.
  cl::opt<std::string>
  APIFile("internalize-public-api-file", cl::value_desc("filename"),
          cl::desc("A file containing list of symbol names to preserve"));

  // APIList - A list of symbols that should not be marked internal.
  cl::list<std::string>
  APIList("internalize-public-api-list", cl::value_desc("list"),
          cl::desc("A list of symbol names to preserve"),
          cl::CommaSeparated);

  class VISIBILITY_HIDDEN InternalizePass : public ModulePass {
    std::set<std::string> ExternalNames;
    bool DontInternalize;
  public:
    static const int ID; // Pass identifcation, replacement for typeid
    InternalizePass(bool InternalizeEverything = true);
    InternalizePass(const std::vector <const char *>& exportList);
    void LoadFile(const char *Filename);
    virtual bool runOnModule(Module &M);
  };
  const int InternalizePass::ID = 0;
  RegisterPass<InternalizePass> X("internalize", "Internalize Global Symbols");
} // end anonymous namespace

InternalizePass::InternalizePass(bool InternalizeEverything) 
  : ModulePass((intptr_t)&ID), DontInternalize(false){
  if (!APIFile.empty())           // If a filename is specified, use it
    LoadFile(APIFile.c_str());
  else if (!APIList.empty())      // Else, if a list is specified, use it.
    ExternalNames.insert(APIList.begin(), APIList.end());
  else if (!InternalizeEverything)
    // Finally, if we're allowed to, internalize all but main.
    DontInternalize = true;
}

InternalizePass::InternalizePass(const std::vector<const char *>&exportList) 
  : ModulePass((intptr_t)&ID), DontInternalize(false){
  for(std::vector<const char *>::const_iterator itr = exportList.begin();
        itr != exportList.end(); itr++) {
    ExternalNames.insert(*itr);
  }
}

void InternalizePass::LoadFile(const char *Filename) {
  // Load the APIFile...
  std::ifstream In(Filename);
  if (!In.good()) {
    cerr << "WARNING: Internalize couldn't load file '" << Filename << "'!\n";
    return;   // Do not internalize anything...
  }
  while (In) {
    std::string Symbol;
    In >> Symbol;
    if (!Symbol.empty())
      ExternalNames.insert(Symbol);
  }
}

bool InternalizePass::runOnModule(Module &M) {
  if (DontInternalize) return false;
  
  // If no list or file of symbols was specified, check to see if there is a
  // "main" symbol defined in the module.  If so, use it, otherwise do not
  // internalize the module, it must be a library or something.
  //
  if (ExternalNames.empty()) {
    Function *MainFunc = M.getFunction("main");
    if (MainFunc == 0 || MainFunc->isDeclaration())
      return false;  // No main found, must be a library...
    
    // Preserve main, internalize all else.
    ExternalNames.insert(MainFunc->getName());
  }
  
  bool Changed = false;
  
  // Found a main function, mark all functions not named main as internal.
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (!I->isDeclaration() &&         // Function must be defined here
        !I->hasInternalLinkage() &&  // Can't already have internal linkage
        !ExternalNames.count(I->getName())) {// Not marked to keep external?
      I->setLinkage(GlobalValue::InternalLinkage);
      Changed = true;
      ++NumFunctions;
      DOUT << "Internalizing func " << I->getName() << "\n";
    }
  
  // Never internalize the llvm.used symbol.  It is used to implement
  // attribute((used)).
  ExternalNames.insert("llvm.used");
  
  // Never internalize anchors used by the machine module info, else the info
  // won't find them.  (see MachineModuleInfo.)
  ExternalNames.insert("llvm.dbg.compile_units");
  ExternalNames.insert("llvm.dbg.global_variables");
  ExternalNames.insert("llvm.dbg.subprograms");
      
  // Mark all global variables with initializers as internal as well.
  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I)
    if (!I->isDeclaration() && !I->hasInternalLinkage() &&
        !ExternalNames.count(I->getName())) {
      // Special case handling of the global ctor and dtor list.  When we
      // internalize it, we mark it constant, which allows elimination of
      // the list if it's empty.
      //
      if (I->hasAppendingLinkage() && (I->getName() == "llvm.global_ctors" ||
                                       I->getName() == "llvm.global_dtors")) {
        // If the global ctors/dtors list has no uses, do not internalize it, as
        // there is no __main in this program, so the asmprinter should handle
        // it.
        if (I->use_empty()) continue;
 
        // Otherwise, also mark the list constant, as we know that it will not
        // be mutated any longer, and the makes simple IPO xforms automatically
        // better.
        I->setConstant(true);
      }
      
      I->setLinkage(GlobalValue::InternalLinkage);
      Changed = true;
      ++NumGlobals;
      DOUT << "Internalized gvar " << I->getName() << "\n";
    }
      
  return Changed;
}

ModulePass *llvm::createInternalizePass(bool InternalizeEverything) {
  return new InternalizePass(InternalizeEverything);
}

ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
  return new InternalizePass(el);
}