--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Transforms/IPO/Internalize.cpp	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,222 @@
+//===-- Internalize.cpp - Mark functions internal -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass loops over all of the functions and variables in the input module.
+// If the function or variable is not in the list of external names given to
+// the pass it is marked as internal.
+//
+// This transformation would not be legal in a regular compilation, but it gets
+// extra information from the linker about what is safe.
+//
+// For example: Internalizing a function with external linkage. Only if we are
+// told it is only used from within this module, it is safe to do it.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "internalize"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/GlobalStatus.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+#include <fstream>
+#include <set>
+using namespace llvm;
+
+STATISTIC(NumAliases  , "Number of aliases internalized");
+STATISTIC(NumFunctions, "Number of functions internalized");
+STATISTIC(NumGlobals  , "Number of global vars internalized");
+
+// APIFile - A file which contains a list of symbols that should not be marked
+// external.
+static cl::opt<std::string>
+APIFile("internalize-public-api-file", cl::value_desc("filename"),
+        cl::desc("A file containing list of symbol names to preserve"));
+
+// APIList - A list of symbols that should not be marked internal.
+static cl::list<std::string>
+APIList("internalize-public-api-list", cl::value_desc("list"),
+        cl::desc("A list of symbol names to preserve"),
+        cl::CommaSeparated);
+
+namespace {
+  class InternalizePass : public ModulePass {
+    std::set<std::string> ExternalNames;
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    explicit InternalizePass();
+    explicit InternalizePass(ArrayRef<const char *> ExportList);
+    void LoadFile(const char *Filename);
+    virtual bool runOnModule(Module &M);
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addPreserved<CallGraph>();
+    }
+  };
+} // end anonymous namespace
+
+char InternalizePass::ID = 0;
+INITIALIZE_PASS(InternalizePass, "internalize",
+                "Internalize Global Symbols", false, false)
+
+InternalizePass::InternalizePass()
+  : ModulePass(ID) {
+  initializeInternalizePassPass(*PassRegistry::getPassRegistry());
+  if (!APIFile.empty())           // If a filename is specified, use it.
+    LoadFile(APIFile.c_str());
+  ExternalNames.insert(APIList.begin(), APIList.end());
+}
+
+InternalizePass::InternalizePass(ArrayRef<const char *> ExportList)
+  : ModulePass(ID){
+  initializeInternalizePassPass(*PassRegistry::getPassRegistry());
+  for(ArrayRef<const char *>::const_iterator itr = ExportList.begin();
+        itr != ExportList.end(); itr++) {
+    ExternalNames.insert(*itr);
+  }
+}
+
+void InternalizePass::LoadFile(const char *Filename) {
+  // Load the APIFile...
+  std::ifstream In(Filename);
+  if (!In.good()) {
+    errs() << "WARNING: Internalize couldn't load file '" << Filename
+         << "'! Continuing as if it's empty.\n";
+    return; // Just continue as if the file were empty
+  }
+  while (In) {
+    std::string Symbol;
+    In >> Symbol;
+    if (!Symbol.empty())
+      ExternalNames.insert(Symbol);
+  }
+}
+
+static bool shouldInternalize(const GlobalValue &GV,
+                              const std::set<std::string> &ExternalNames) {
+  // Function must be defined here
+  if (GV.isDeclaration())
+    return false;
+
+  // Available externally is really just a "declaration with a body".
+  if (GV.hasAvailableExternallyLinkage())
+    return false;
+
+  // Already has internal linkage
+  if (GV.hasLocalLinkage())
+    return false;
+
+  // Marked to keep external?
+  if (ExternalNames.count(GV.getName()))
+    return false;
+
+  return true;
+}
+
+bool InternalizePass::runOnModule(Module &M) {
+  CallGraph *CG = getAnalysisIfAvailable<CallGraph>();
+  CallGraphNode *ExternalNode = CG ? CG->getExternalCallingNode() : 0;
+  bool Changed = false;
+
+  SmallPtrSet<GlobalValue *, 8> Used;
+  collectUsedGlobalVariables(M, Used, false);
+
+  // We must assume that globals in llvm.used have a reference that not even
+  // the linker can see, so we don't internalize them.
+  // For llvm.compiler.used the situation is a bit fuzzy. The assembler and
+  // linker can drop those symbols. If this pass is running as part of LTO,
+  // one might think that it could just drop llvm.compiler.used. The problem
+  // is that even in LTO llvm doesn't see every reference. For example,
+  // we don't see references from function local inline assembly. To be
+  // conservative, we internalize symbols in llvm.compiler.used, but we
+  // keep llvm.compiler.used so that the symbol is not deleted by llvm.
+  for (SmallPtrSet<GlobalValue *, 8>::iterator I = Used.begin(), E = Used.end();
+       I != E; ++I) {
+    GlobalValue *V = *I;
+    ExternalNames.insert(V->getName());
+  }
+
+  // Mark all functions not in the api as internal.
+  // FIXME: maybe use private linkage?
+  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
+    if (!shouldInternalize(*I, ExternalNames))
+      continue;
+
+    I->setLinkage(GlobalValue::InternalLinkage);
+
+    if (ExternalNode)
+      // Remove a callgraph edge from the external node to this function.
+      ExternalNode->removeOneAbstractEdgeTo((*CG)[I]);
+
+    Changed = true;
+    ++NumFunctions;
+    DEBUG(dbgs() << "Internalizing func " << I->getName() << "\n");
+  }
+
+  // Never internalize the llvm.used symbol.  It is used to implement
+  // attribute((used)).
+  // FIXME: Shouldn't this just filter on llvm.metadata section??
+  ExternalNames.insert("llvm.used");
+  ExternalNames.insert("llvm.compiler.used");
+
+  // Never internalize anchors used by the machine module info, else the info
+  // won't find them.  (see MachineModuleInfo.)
+  ExternalNames.insert("llvm.global_ctors");
+  ExternalNames.insert("llvm.global_dtors");
+  ExternalNames.insert("llvm.global.annotations");
+
+  // Never internalize symbols code-gen inserts.
+  // FIXME: We should probably add this (and the __stack_chk_guard) via some
+  // type of call-back in CodeGen.
+  ExternalNames.insert("__stack_chk_fail");
+  ExternalNames.insert("__stack_chk_guard");
+
+  // Mark all global variables with initializers that are not in the api as
+  // internal as well.
+  // FIXME: maybe use private linkage?
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+       I != E; ++I) {
+    if (!shouldInternalize(*I, ExternalNames))
+      continue;
+
+    I->setLinkage(GlobalValue::InternalLinkage);
+    Changed = true;
+    ++NumGlobals;
+    DEBUG(dbgs() << "Internalized gvar " << I->getName() << "\n");
+  }
+
+  // Mark all aliases that are not in the api as internal as well.
+  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
+       I != E; ++I) {
+    if (!shouldInternalize(*I, ExternalNames))
+      continue;
+
+    I->setLinkage(GlobalValue::InternalLinkage);
+    Changed = true;
+    ++NumAliases;
+    DEBUG(dbgs() << "Internalized alias " << I->getName() << "\n");
+  }
+
+  return Changed;
+}
+
+ModulePass *llvm::createInternalizePass() {
+  return new InternalizePass();
+}
+
+ModulePass *llvm::createInternalizePass(ArrayRef<const char *> ExportList) {
+  return new InternalizePass(ExportList);
+}