1 //===-- Internalize.cpp - Mark functions internal -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 #define DEBUG_TYPE "internalize"
17 #include "llvm/Analysis/CallGraph.h"
18 #include "llvm/Transforms/IPO.h"
19 #include "llvm/Pass.h"
20 #include "llvm/Module.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include "llvm/ADT/Statistic.h"
29 STATISTIC(NumAliases , "Number of aliases internalized");
30 STATISTIC(NumFunctions, "Number of functions internalized");
31 STATISTIC(NumGlobals , "Number of global vars internalized");
33 // APIFile - A file which contains a list of symbols that should not be marked
35 static cl::opt<std::string>
36 APIFile("internalize-public-api-file", cl::value_desc("filename"),
37 cl::desc("A file containing list of symbol names to preserve"));
39 // APIList - A list of symbols that should not be marked internal.
40 static cl::list<std::string>
41 APIList("internalize-public-api-list", cl::value_desc("list"),
42 cl::desc("A list of symbol names to preserve"),
46 class InternalizePass : public ModulePass {
47 std::set<std::string> ExternalNames;
48 /// If no api symbols were specified and a main function is defined,
49 /// assume the main function is the only API
52 static char ID; // Pass identification, replacement for typeid
53 explicit InternalizePass(bool AllButMain = true);
54 explicit InternalizePass(const std::vector <const char *>& exportList);
55 void LoadFile(const char *Filename);
56 virtual bool runOnModule(Module &M);
58 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
60 AU.addPreserved<CallGraph>();
63 } // end anonymous namespace
65 char InternalizePass::ID = 0;
66 INITIALIZE_PASS(InternalizePass, "internalize",
67 "Internalize Global Symbols", false, false)
69 InternalizePass::InternalizePass(bool AllButMain)
70 : ModulePass(ID), AllButMain(AllButMain){
71 initializeInternalizePassPass(*PassRegistry::getPassRegistry());
72 if (!APIFile.empty()) // If a filename is specified, use it.
73 LoadFile(APIFile.c_str());
74 if (!APIList.empty()) // If a list is specified, use it as well.
75 ExternalNames.insert(APIList.begin(), APIList.end());
78 InternalizePass::InternalizePass(const std::vector<const char *>&exportList)
79 : ModulePass(ID), AllButMain(false){
80 initializeInternalizePassPass(*PassRegistry::getPassRegistry());
81 for(std::vector<const char *>::const_iterator itr = exportList.begin();
82 itr != exportList.end(); itr++) {
83 ExternalNames.insert(*itr);
87 void InternalizePass::LoadFile(const char *Filename) {
88 // Load the APIFile...
89 std::ifstream In(Filename);
91 errs() << "WARNING: Internalize couldn't load file '" << Filename
92 << "'! Continuing as if it's empty.\n";
93 return; // Just continue as if the file were empty
99 ExternalNames.insert(Symbol);
103 bool InternalizePass::runOnModule(Module &M) {
104 CallGraph *CG = getAnalysisIfAvailable<CallGraph>();
105 CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
107 if (ExternalNames.empty()) {
108 // Return if we're not in 'all but main' mode and have no external api
111 // If no list or file of symbols was specified, check to see if there is a
112 // "main" symbol defined in the module. If so, use it, otherwise do not
113 // internalize the module, it must be a library or something.
115 Function *MainFunc = M.getFunction("main");
116 if (MainFunc == 0 || MainFunc->isDeclaration())
117 return false; // No main found, must be a library...
119 // Preserve main, internalize all else.
120 ExternalNames.insert(MainFunc->getName());
123 bool Changed = false;
125 // Never internalize functions which code-gen might insert.
126 ExternalNames.insert("__stack_chk_fail");
128 // Mark all functions not in the api as internal.
129 // FIXME: maybe use private linkage?
130 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
131 if (!I->isDeclaration() && // Function must be defined here
132 // Available externally is really just a "declaration with a body".
133 !I->hasAvailableExternallyLinkage() &&
134 !I->hasLocalLinkage() && // Can't already have internal linkage
135 !ExternalNames.count(I->getName())) {// Not marked to keep external?
136 I->setLinkage(GlobalValue::InternalLinkage);
137 // Remove a callgraph edge from the external node to this function.
138 if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
141 DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
144 // Never internalize the llvm.used symbol. It is used to implement
145 // attribute((used)).
146 // FIXME: Shouldn't this just filter on llvm.metadata section??
147 ExternalNames.insert("llvm.used");
148 ExternalNames.insert("llvm.compiler.used");
150 // Never internalize anchors used by the machine module info, else the info
151 // won't find them. (see MachineModuleInfo.)
152 ExternalNames.insert("llvm.global_ctors");
153 ExternalNames.insert("llvm.global_dtors");
154 ExternalNames.insert("llvm.global.annotations");
156 // Never internalize symbols code-gen inserts.
157 ExternalNames.insert("__stack_chk_guard");
159 // Mark all global variables with initializers that are not in the api as
161 // FIXME: maybe use private linkage?
162 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
164 if (!I->isDeclaration() && !I->hasLocalLinkage() &&
165 // Available externally is really just a "declaration with a body".
166 !I->hasAvailableExternallyLinkage() &&
167 !ExternalNames.count(I->getName())) {
168 I->setLinkage(GlobalValue::InternalLinkage);
171 DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
174 // Mark all aliases that are not in the api as internal as well.
175 for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
177 if (!I->isDeclaration() && !I->hasInternalLinkage() &&
178 // Available externally is really just a "declaration with a body".
179 !I->hasAvailableExternallyLinkage() &&
180 !ExternalNames.count(I->getName())) {
181 I->setLinkage(GlobalValue::InternalLinkage);
184 DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
190 ModulePass *llvm::createInternalizePass(bool AllButMain) {
191 return new InternalizePass(AllButMain);
194 ModulePass *llvm::createInternalizePass(const std::vector <const char *> &el) {
195 return new InternalizePass(el);