1 //===-- Internalize.cpp - Mark functions internal -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/IPO.h"
17 #include "llvm/Pass.h"
18 #include "llvm/Module.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/ADT/Statistic.h"
27 Statistic NumFunctions("internalize", "Number of functions internalized");
28 Statistic NumGlobals ("internalize", "Number of global vars internalized");
30 // APIFile - A file which contains a list of symbols that should not be marked
33 APIFile("internalize-public-api-file", cl::value_desc("filename"),
34 cl::desc("A file containing list of symbol names to preserve"));
36 // APIList - A list of symbols that should not be marked internal.
38 APIList("internalize-public-api-list", cl::value_desc("list"),
39 cl::desc("A list of symbol names to preserve"),
42 class InternalizePass : public ModulePass {
43 std::set<std::string> ExternalNames;
46 InternalizePass(bool InternalizeEverything = true);
47 InternalizePass(const std::vector <const char *>& exportList);
48 void LoadFile(const char *Filename);
49 virtual bool runOnModule(Module &M);
51 RegisterPass<InternalizePass> X("internalize", "Internalize Global Symbols");
52 } // end anonymous namespace
54 InternalizePass::InternalizePass(bool InternalizeEverything)
55 : DontInternalize(false){
56 if (!APIFile.empty()) // If a filename is specified, use it
57 LoadFile(APIFile.c_str());
58 else if (!APIList.empty()) // Else, if a list is specified, use it.
59 ExternalNames.insert(APIList.begin(), APIList.end());
60 else if (!InternalizeEverything)
61 // Finally, if we're allowed to, internalize all but main.
62 DontInternalize = true;
65 InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
66 : DontInternalize(false){
67 for(std::vector<const char *>::const_iterator itr = exportList.begin();
68 itr != exportList.end(); itr++) {
69 ExternalNames.insert(*itr);
73 void InternalizePass::LoadFile(const char *Filename) {
74 // Load the APIFile...
75 std::ifstream In(Filename);
77 cerr << "WARNING: Internalize couldn't load file '" << Filename << "'!\n";
78 return; // Do not internalize anything...
84 ExternalNames.insert(Symbol);
88 bool InternalizePass::runOnModule(Module &M) {
89 if (DontInternalize) return false;
91 // If no list or file of symbols was specified, check to see if there is a
92 // "main" symbol defined in the module. If so, use it, otherwise do not
93 // internalize the module, it must be a library or something.
95 if (ExternalNames.empty()) {
96 Function *MainFunc = M.getMainFunction();
97 if (MainFunc == 0 || MainFunc->isExternal())
98 return false; // No main found, must be a library...
100 // Preserve main, internalize all else.
101 ExternalNames.insert(MainFunc->getName());
104 bool Changed = false;
106 // Found a main function, mark all functions not named main as internal.
107 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
108 if (!I->isExternal() && // Function must be defined here
109 !I->hasInternalLinkage() && // Can't already have internal linkage
110 !ExternalNames.count(I->getName())) {// Not marked to keep external?
111 I->setLinkage(GlobalValue::InternalLinkage);
114 DOUT << "Internalizing func " << I->getName() << "\n";
117 // Never internalize the llvm.used symbol. It is used to implement
118 // attribute((used)).
119 ExternalNames.insert("llvm.used");
121 // Never internalize anchors used by the debugger, else the debugger won't
122 // find them. (see MachineDebugInfo.)
123 ExternalNames.insert("llvm.dbg.compile_units");
124 ExternalNames.insert("llvm.dbg.global_variables");
125 ExternalNames.insert("llvm.dbg.subprograms");
127 // Mark all global variables with initializers as internal as well.
128 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
130 if (!I->isExternal() && !I->hasInternalLinkage() &&
131 !ExternalNames.count(I->getName())) {
132 // Special case handling of the global ctor and dtor list. When we
133 // internalize it, we mark it constant, which allows elimination of
134 // the list if it's empty.
136 if (I->hasAppendingLinkage() && (I->getName() == "llvm.global_ctors" ||
137 I->getName() == "llvm.global_dtors")) {
138 // If the global ctors/dtors list has no uses, do not internalize it, as
139 // there is no __main in this program, so the asmprinter should handle
141 if (I->use_empty()) continue;
143 // Otherwise, also mark the list constant, as we know that it will not
144 // be mutated any longer, and the makes simple IPO xforms automatically
146 I->setConstant(true);
149 I->setLinkage(GlobalValue::InternalLinkage);
152 DOUT << "Internalized gvar " << I->getName() << "\n";
158 ModulePass *llvm::createInternalizePass(bool InternalizeEverything) {
159 return new InternalizePass(InternalizeEverything);
162 ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
163 return new InternalizePass(el);