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 and variables in the input module.
11 // If the function or variable is not in the list of external names given to
12 // the pass it is marked as internal.
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "internalize"
17 #include "llvm/Transforms/IPO.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/CallGraph.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/raw_ostream.h"
26 #include "llvm/Transforms/Utils/ModuleUtils.h"
31 STATISTIC(NumAliases , "Number of aliases internalized");
32 STATISTIC(NumFunctions, "Number of functions internalized");
33 STATISTIC(NumGlobals , "Number of global vars internalized");
35 // APIFile - A file which contains a list of symbols that should not be marked
37 static cl::opt<std::string>
38 APIFile("internalize-public-api-file", cl::value_desc("filename"),
39 cl::desc("A file containing list of symbol names to preserve"));
41 // APIList - A list of symbols that should not be marked internal.
42 static cl::list<std::string>
43 APIList("internalize-public-api-list", cl::value_desc("list"),
44 cl::desc("A list of symbol names to preserve"),
48 class InternalizePass : public ModulePass {
49 std::set<std::string> ExternalNames;
51 static char ID; // Pass identification, replacement for typeid
52 explicit InternalizePass();
53 explicit InternalizePass(ArrayRef<const char *> exportList);
54 void LoadFile(const char *Filename);
55 void ClearExportList();
56 void AddToExportList(const std::string &val);
57 virtual bool runOnModule(Module &M);
59 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
61 AU.addPreserved<CallGraph>();
64 } // end anonymous namespace
66 char InternalizePass::ID = 0;
67 INITIALIZE_PASS(InternalizePass, "internalize",
68 "Internalize Global Symbols", false, false)
70 InternalizePass::InternalizePass()
72 initializeInternalizePassPass(*PassRegistry::getPassRegistry());
73 if (!APIFile.empty()) // If a filename is specified, use it.
74 LoadFile(APIFile.c_str());
75 if (!APIList.empty()) // If a list is specified, use it as well.
76 ExternalNames.insert(APIList.begin(), APIList.end());
79 InternalizePass::InternalizePass(ArrayRef<const char *> exportList)
81 initializeInternalizePassPass(*PassRegistry::getPassRegistry());
82 for(ArrayRef<const char *>::const_iterator itr = exportList.begin();
83 itr != exportList.end(); itr++) {
84 ExternalNames.insert(*itr);
88 void InternalizePass::LoadFile(const char *Filename) {
89 // Load the APIFile...
90 std::ifstream In(Filename);
92 errs() << "WARNING: Internalize couldn't load file '" << Filename
93 << "'! Continuing as if it's empty.\n";
94 return; // Just continue as if the file were empty
100 ExternalNames.insert(Symbol);
104 void InternalizePass::ClearExportList() {
105 ExternalNames.clear();
108 void InternalizePass::AddToExportList(const std::string &val) {
109 ExternalNames.insert(val);
112 bool InternalizePass::runOnModule(Module &M) {
113 CallGraph *CG = getAnalysisIfAvailable<CallGraph>();
114 CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
115 bool Changed = false;
117 SmallPtrSet<GlobalValue *, 8> Used;
118 collectUsedGlobalVariables(M, Used, false);
120 // We must assume that globals in llvm.used have a reference that not even
121 // the linker can see, so we don't internalize them.
122 // For llvm.compiler.used the situation is a bit fuzzy. The assembler and
123 // linker can drop those symbols. If this pass is running as part of LTO,
124 // one might think that it could just drop llvm.compiler.used. The problem
125 // is that even in LTO llvm doesn't see every reference. For example,
126 // we don't see references from function local inline assembly. To be
127 // conservative, we internalize symbols in llvm.compiler.used, but we
128 // keep llvm.compiler.used so that the symbol is not deleted by llvm.
129 for (SmallPtrSet<GlobalValue *, 8>::iterator I = Used.begin(), E = Used.end();
132 ExternalNames.insert(V->getName());
135 // Mark all functions not in the api as internal.
136 // FIXME: maybe use private linkage?
137 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
138 if (!I->isDeclaration() && // Function must be defined here
139 // Available externally is really just a "declaration with a body".
140 !I->hasAvailableExternallyLinkage() &&
141 !I->hasLocalLinkage() && // Can't already have internal linkage
142 !ExternalNames.count(I->getName())) {// Not marked to keep external?
143 I->setLinkage(GlobalValue::InternalLinkage);
144 // Remove a callgraph edge from the external node to this function.
145 if (ExternalNode) ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
148 DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
151 // Never internalize the llvm.used symbol. It is used to implement
152 // attribute((used)).
153 // FIXME: Shouldn't this just filter on llvm.metadata section??
154 ExternalNames.insert("llvm.used");
155 ExternalNames.insert("llvm.compiler.used");
157 // Never internalize anchors used by the machine module info, else the info
158 // won't find them. (see MachineModuleInfo.)
159 ExternalNames.insert("llvm.global_ctors");
160 ExternalNames.insert("llvm.global_dtors");
161 ExternalNames.insert("llvm.global.annotations");
163 // Never internalize symbols code-gen inserts.
164 // FIXME: We should probably add this (and the __stack_chk_guard) via some
165 // type of call-back in CodeGen.
166 ExternalNames.insert("__stack_chk_fail");
167 ExternalNames.insert("__stack_chk_guard");
169 // Mark all global variables with initializers that are not in the api as
171 // FIXME: maybe use private linkage?
172 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
174 if (!I->isDeclaration() && !I->hasLocalLinkage() &&
175 // Available externally is really just a "declaration with a body".
176 !I->hasAvailableExternallyLinkage() &&
177 !ExternalNames.count(I->getName())) {
178 I->setLinkage(GlobalValue::InternalLinkage);
181 DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
184 // Mark all aliases that are not in the api as internal as well.
185 for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
187 if (!I->isDeclaration() && !I->hasInternalLinkage() &&
188 // Available externally is really just a "declaration with a body".
189 !I->hasAvailableExternallyLinkage() &&
190 !ExternalNames.count(I->getName())) {
191 I->setLinkage(GlobalValue::InternalLinkage);
194 DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
200 ModulePass *llvm::createInternalizePass() {
201 return new InternalizePass();
204 ModulePass *llvm::createInternalizePass(ArrayRef<const char *> el) {
205 return new InternalizePass(el);