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 void LoadFile(const char *Filename);
48 virtual bool runOnModule(Module &M);
50 RegisterOpt<InternalizePass> X("internalize", "Internalize Global Symbols");
51 } // end anonymous namespace
53 InternalizePass::InternalizePass(bool InternalizeEverything)
54 : DontInternalize(false){
55 if (!APIFile.empty()) // If a filename is specified, use it
56 LoadFile(APIFile.c_str());
57 else if (!APIList.empty()) // Else, if a list is specified, use it.
58 ExternalNames.insert(APIList.begin(), APIList.end());
59 else if (!InternalizeEverything)
60 // Finally, if we're allowed to, internalize all but main.
61 DontInternalize = true;
64 void InternalizePass::LoadFile(const char *Filename) {
65 // Load the APIFile...
66 std::ifstream In(Filename);
68 std::cerr << "WARNING: Internalize couldn't load file '" << Filename
70 return; // Do not internalize anything...
76 ExternalNames.insert(Symbol);
80 bool InternalizePass::runOnModule(Module &M) {
81 if (DontInternalize) return false;
83 // If no list or file of symbols was specified, check to see if there is a
84 // "main" symbol defined in the module. If so, use it, otherwise do not
85 // internalize the module, it must be a library or something.
87 if (ExternalNames.empty()) {
88 Function *MainFunc = M.getMainFunction();
89 if (MainFunc == 0 || MainFunc->isExternal())
90 return false; // No main found, must be a library...
92 // Preserve main, internalize all else.
93 ExternalNames.insert(MainFunc->getName());
98 // Found a main function, mark all functions not named main as internal.
99 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
100 if (!I->isExternal() && // Function must be defined here
101 !I->hasInternalLinkage() && // Can't already have internal linkage
102 !ExternalNames.count(I->getName())) {// Not marked to keep external?
103 I->setLinkage(GlobalValue::InternalLinkage);
106 DEBUG(std::cerr << "Internalizing func " << I->getName() << "\n");
109 // Never internalize the llvm.used symbol. It is used to implement
110 // attribute((used)).
111 ExternalNames.insert("llvm.used");
113 // Never internalize anchors used by the debugger, else the debugger won't
115 ExternalNames.insert("llvm.dbg.translation_units");
116 ExternalNames.insert("llvm.dbg.globals");
118 // Mark all global variables with initializers as internal as well.
119 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
121 if (!I->isExternal() && !I->hasInternalLinkage() &&
122 !ExternalNames.count(I->getName())) {
123 // Special case handling of the global ctor and dtor list. When we
124 // internalize it, we mark it constant, which allows elimination of
125 // the list if it's empty.
127 if (I->hasAppendingLinkage() && (I->getName() == "llvm.global_ctors" ||
128 I->getName() == "llvm.global_dtors")) {
129 // If the global ctors/dtors list has no uses, do not internalize it, as
130 // there is no __main in this program, so the asmprinter should handle
132 if (I->use_empty()) continue;
134 // Otherwise, also mark the list constant, as we know that it will not
135 // be mutated any longer, and the makes simple IPO xforms automatically
137 I->setConstant(true);
140 I->setLinkage(GlobalValue::InternalLinkage);
143 DEBUG(std::cerr << "Internalized gvar " << I->getName() << "\n");
149 ModulePass *llvm::createInternalizePass(bool InternalizeEverything) {
150 return new InternalizePass(InternalizeEverything);