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"
28 Statistic<> NumFunctions("internalize", "Number of functions internalized");
29 Statistic<> NumGlobals ("internalize", "Number of global vars internalized");
31 // APIFile - A file which contains a list of symbols that should not be marked
34 APIFile("internalize-public-api-file", cl::value_desc("filename"),
35 cl::desc("A file containing list of symbol names to preserve"));
37 // APIList - A list of symbols that should not be marked internal.
39 APIList("internalize-public-api-list", cl::value_desc("list"),
40 cl::desc("A list of symbol names to preserve"),
43 class InternalizePass : public ModulePass {
44 std::set<std::string> ExternalNames;
47 InternalizePass(bool InternalizeEverything = true);
48 void LoadFile(const char *Filename);
49 virtual bool runOnModule(Module &M);
51 RegisterOpt<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 void InternalizePass::LoadFile(const char *Filename) {
66 // Load the APIFile...
67 std::ifstream In(Filename);
69 std::cerr << "WARNING: Internalize couldn't load file '" << Filename
71 return; // Do not internalize anything...
77 ExternalNames.insert(Symbol);
81 bool InternalizePass::runOnModule(Module &M) {
82 if (DontInternalize) return false;
84 // If no list or file of symbols was specified, check to see if there is a
85 // "main" symbol defined in the module. If so, use it, otherwise do not
86 // internalize the module, it must be a library or something.
88 if (ExternalNames.empty()) {
89 Function *MainFunc = M.getMainFunction();
90 if (MainFunc == 0 || MainFunc->isExternal())
91 return false; // No main found, must be a library...
93 // Preserve main, internalize all else.
94 ExternalNames.insert(MainFunc->getName());
99 // Found a main function, mark all functions not named main as internal.
100 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
101 if (!I->isExternal() && // Function must be defined here
102 !I->hasInternalLinkage() && // Can't already have internal linkage
103 !ExternalNames.count(I->getName())) {// Not marked to keep external?
104 I->setLinkage(GlobalValue::InternalLinkage);
107 DEBUG(std::cerr << "Internalizing func " << I->getName() << "\n");
110 // Never internalize the llvm.used symbol. It is used to implement
111 // attribute((used)).
112 ExternalNames.insert("llvm.used");
114 // Never internalize anchors used by the debugger, else the debugger won't
116 ExternalNames.insert("llvm.dbg.translation_units");
117 ExternalNames.insert("llvm.dbg.globals");
119 // Mark all global variables with initializers as internal as well.
120 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
122 if (!I->isExternal() && !I->hasInternalLinkage() &&
123 !ExternalNames.count(I->getName())) {
124 // Special case handling of the global ctor and dtor list. When we
125 // internalize it, we mark it constant, which allows elimination of
126 // the list if it's empty.
128 if (I->hasAppendingLinkage() && (I->getName() == "llvm.global_ctors" ||
129 I->getName() == "llvm.global_dtors")) {
130 // If the global ctors/dtors list has no uses, do not internalize it, as
131 // there is no __main in this program, so the asmprinter should handle
133 if (I->use_empty()) continue;
135 // Otherwise, also mark the list constant, as we know that it will not
136 // be mutated any longer, and the makes simple IPO xforms automatically
138 I->setConstant(true);
141 I->setLinkage(GlobalValue::InternalLinkage);
144 DEBUG(std::cerr << "Internalized gvar " << I->getName() << "\n");
150 ModulePass *llvm::createInternalizePass(bool InternalizeEverything) {
151 return new InternalizePass(InternalizeEverything);