first commit of new LTO system. It is not hooked up in the llvm/tools/Makefile, so no one will build it be default yet

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47621 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 1477 insertions, 0 deletions

diff --git a/include/llvm-c/lto.h b/include/llvm-c/lto.h
new file mode 100644
index 0000000..8d4590b
--- /dev/null
+++ b/include/llvm-c/lto.h
@@ -0,0 +1,234 @@
+/*===-- llvm-c/lto.h - LTO Public C Interface ---------------------*- C -*-===*\
+|*                                                                            *|
+|*                     The LLVM Compiler Infrastructure                       *|
+|*                                                                            *|
+|* This file is distributed under the University of Illinois Open Source      *|
+|* License. See LICENSE.TXT for details.                                      *|
+|*                                                                            *|
+|*===----------------------------------------------------------------------===*|
+|*                                                                            *|
+|* This header provides public interface to an abstract link time optimization*|
+|* library.  LLVM provides an implementation of this interface for use with   *|
+|* llvm bitcode files.                                                        *|
+|*                                                                            *|
+\*===----------------------------------------------------------------------===*/
+
+#ifndef LTO_H
+#define LTO_H  1
+
+#include <stdbool.h>
+#include <stddef.h>
+
+typedef enum {
+    LTO_SYMBOL_ALIGNMENT_MASK         = 0x0000001F,    /* log2 of alignment */
+    LTO_SYMBOL_PERMISSIONS_MASK       = 0x000000E0,    
+    LTO_SYMBOL_PERMISSIONS_CODE       = 0x000000A0,    
+    LTO_SYMBOL_PERMISSIONS_DATA       = 0x000000C0,    
+    LTO_SYMBOL_PERMISSIONS_RODATA     = 0x00000080,    
+    LTO_SYMBOL_DEFINITION_MASK        = 0x00000700,    
+    LTO_SYMBOL_DEFINITION_REGULAR     = 0x00000100,    
+    LTO_SYMBOL_DEFINITION_TENTATIVE   = 0x00000200,    
+    LTO_SYMBOL_DEFINITION_WEAK        = 0x00000300,    
+    LTO_SYMBOL_DEFINITION_UNDEFINED   = 0x00000400,    
+    LTO_SYMBOL_SCOPE_MASK             = 0x00001800,    
+    LTO_SYMBOL_SCOPE_INTERNAL         = 0x00000800,    
+    LTO_SYMBOL_SCOPE_HIDDEN           = 0x00001000,    
+    LTO_SYMBOL_SCOPE_DEFAULT          = 0x00001800    
+} lto_symbol_attributes;
+
+typedef enum {
+    LTO_DEBUG_MODEL_NONE         = 0,
+    LTO_DEBUG_MODEL_DWARF        = 1
+} lto_debug_model;
+
+typedef enum {
+    LTO_CODEGEN_PIC_MODEL_STATIC         = 0,
+    LTO_CODEGEN_PIC_MODEL_DYNAMIC        = 1,
+    LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC = 2
+} lto_codegen_model;
+
+
+/** opaque reference to a loaded object module */
+typedef struct LTOModule*         lto_module_t;
+
+/** opaque reference to a code generator */
+typedef struct LTOCodeGenerator*  lto_code_gen_t;
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Returns a printable string.
+ */
+extern const char*
+lto_get_version();
+
+
+/**
+ * Returns the last error string or NULL if last operation was sucessful.
+ */
+extern const char*
+lto_get_error_message();
+
+
+/**
+ * Checks if a file is a loadable object file.
+ */
+extern bool
+lto_module_is_object_file(const char* path);
+
+
+/**
+ * Checks if a file is a loadable object compiled for requested target.
+ */
+extern bool
+lto_module_is_object_file_for_target(const char* path, 
+                                            const char* target_triple_prefix);
+
+
+/**
+ * Checks if a buffer is a loadable object file.
+ */
+extern bool
+lto_module_is_object_file_in_memory(const void* mem, size_t length);
+
+
+/**
+ * Checks if a buffer is a loadable object compiled for requested target.
+ */
+extern bool
+lto_module_is_object_file_in_memory_for_target(const void* mem, size_t length, 
+                                               const char* target_triple_prefix);
+
+
+/**
+ * Loads an object file from disk.
+ * Returns NULL on error (check lto_get_error_message() for details).
+ */
+extern lto_module_t
+lto_module_create(const char* path);
+
+
+/**
+ * Loads an object file from memory.
+ * Returns NULL on error (check lto_get_error_message() for details).
+ */
+extern lto_module_t
+lto_module_create_from_memory(const void* mem, size_t length);
+
+
+/**
+ * Frees all memory internally allocated by the module.
+ * Upon return the lto_module_t is no longer valid.
+ */
+extern void
+lto_module_dispose(lto_module_t mod);
+
+
+/**
+ * Returns triple string which the object module was compiled under.
+ */
+extern const char*
+lto_module_get_target_triple(lto_module_t mod);
+
+
+/**
+ * Returns the number of symbols in the object module.
+ */
+extern unsigned int
+lto_module_get_num_symbols(lto_module_t mod);
+
+
+/**
+ * Returns the name of the ith symbol in the object module.
+ */
+extern const char*
+lto_module_get_symbol_name(lto_module_t mod, unsigned int index);
+
+
+/**
+ * Returns the attributes of the ith symbol in the object module.
+ */
+extern lto_symbol_attributes
+lto_module_get_symbol_attribute(lto_module_t mod, unsigned int index);
+
+
+/**
+ * Instantiates a code generator.
+ * Returns NULL on error (check lto_get_error_message() for details).
+ */
+extern lto_code_gen_t
+lto_codegen_create();
+
+
+/**
+ * Frees all code generator and all memory it internally allocated.
+ * Upon return the lto_code_gen_t is no longer valid.
+ */
+extern void
+lto_codegen_dispose(lto_code_gen_t);
+
+
+
+/**
+ * Add an object module to the set of modules for which code will be generated.
+ * Returns true on error (check lto_get_error_message() for details).
+ */
+extern bool
+lto_codegen_add_module(lto_code_gen_t cg, lto_module_t mod);
+
+
+
+/**
+ * Sets if debug info should be generated.
+ * Returns true on error (check lto_get_error_message() for details).
+ */
+extern bool
+lto_codegen_set_debug_model(lto_code_gen_t cg, lto_debug_model);
+
+
+/**
+ * Sets which PIC code model to generated.
+ * Returns true on error (check lto_get_error_message() for details).
+ */
+extern bool
+lto_codegen_set_pic_model(lto_code_gen_t cg, lto_codegen_model);
+
+
+/**
+ * Adds to a list of all global symbols that must exist in the final
+ * generated code.  If a function is not listed, it might be
+ * inlined into every usage and optimized away.
+ */
+extern void
+lto_codegen_add_must_preserve_symbol(lto_code_gen_t cg, const char* symbol);
+
+
+/**
+ * Writes a new object file at the specified path that contains the
+ * merged contents of all modules added so far.
+ * Returns true on error (check lto_get_error_message() for details).
+ */
+extern bool
+lto_codegen_write_merged_modules(lto_code_gen_t cg, const char* path);
+
+
+/**
+ * Generates code for all added modules into one native object file.
+ * On sucess returns a pointer to a generated mach-o/ELF buffer and
+ * length set to the buffer size.  Client owns the buffer and should
+ * free() it when done.
+ * On failure, returns NULL (check lto_get_error_message() for details).
+ */
+extern void*
+lto_codegen_compile(lto_code_gen_t cg, size_t* length);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif
diff --git a/tools/lto2/LTOCodeGenerator.cpp b/tools/lto2/LTOCodeGenerator.cpp
new file mode 100644
index 0000000..795aca0
--- /dev/null
+++ b/tools/lto2/LTOCodeGenerator.cpp
@@ -0,0 +1,465 @@
+//===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Link Time Optimization library. This library is 
+// intended to be used by linker to optimize code at link time.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/PassManager.h"
+#include "llvm/Linker.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/ModuleProvider.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/SystemUtils.h"
+#include "llvm/Support/Mangler.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/System/Program.h"
+#include "llvm/System/Signals.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/CodeGen/FileWriters.h"
+#include "llvm/Target/SubtargetFeature.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetMachineRegistry.h"
+#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Analysis/LoadValueNumbering.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Config/config.h"
+
+#include "LTOModule.h"
+#include "LTOCodeGenerator.h"
+
+#include <fstream>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+
+
+using namespace llvm;
+
+
+
+const char* LTOCodeGenerator::getVersionString()
+{
+#ifdef LLVM_VERSION_INFO
+    return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
+#else
+    return PACKAGE_NAME " version " PACKAGE_VERSION;
+#endif
+}
+
+
+LTOCodeGenerator::LTOCodeGenerator() 
+    : _linker("LinkTimeOptimizer", "ld-temp.o"), _target(NULL),
+      _emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
+      _codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC)
+{
+
+}
+
+LTOCodeGenerator::~LTOCodeGenerator()
+{
+    // FIXME
+}
+
+
+
+bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
+{
+    return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
+}
+    
+
+bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
+{
+    switch (debug) {
+        case LTO_DEBUG_MODEL_NONE:
+            _emitDwarfDebugInfo = false;
+            return false;
+            
+        case LTO_DEBUG_MODEL_DWARF:
+            _emitDwarfDebugInfo = true;
+            return false;
+    }
+    errMsg = "unknown debug format";
+    return true;
+}
+
+
+bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model, 
+                                                        std::string& errMsg)
+{
+    switch (model) {
+        case LTO_CODEGEN_PIC_MODEL_STATIC:
+        case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
+        case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
+            _codeModel = model;
+            return false;
+    }
+    errMsg = "unknown pic model";
+    return true;
+}
+
+
+void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
+{
+    _mustPreserveSymbols[sym] = 1;
+}
+
+
+bool LTOCodeGenerator::writeMergedModules(const char* path, std::string& errMsg)
+{
+    if ( this->determineTarget(errMsg) ) 
+        return true;
+
+    // mark which symbols can not be internalized 
+    this->applyScopeRestrictions();
+
+    // create output file
+    std::ofstream out(path, std::ios_base::out|std::ios::trunc|std::ios::binary);
+    if ( out.fail() ) {
+        errMsg = "could not open bitcode file for writing: ";
+        errMsg += path;
+        return true;
+    }
+    
+    // write bitcode to it
+    WriteBitcodeToFile(_linker.getModule(), out);
+    if ( out.fail() ) {
+        errMsg = "could not write bitcode file: ";
+        errMsg += path;
+        return true;
+    }
+    
+    return false;
+}
+
+
+void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
+{
+    // make unqiue temp .s file to put generated assembly code
+    sys::Path uniqueAsmPath("lto-llvm.s");
+    if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
+        return NULL;
+    sys::RemoveFileOnSignal(uniqueAsmPath);
+       
+    // generate assembly code
+    std::ofstream asmFile(uniqueAsmPath.c_str());
+    bool genResult = this->generateAssemblyCode(asmFile, errMsg);
+    asmFile.close();
+    if ( genResult ) {
+        if ( uniqueAsmPath.exists() )
+            uniqueAsmPath.eraseFromDisk();
+        return NULL;
+    }
+    
+    // make unqiue temp .o file to put generated object file
+    sys::PathWithStatus uniqueObjPath("lto-llvm.o");
+    if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
+        if ( uniqueAsmPath.exists() )
+            uniqueAsmPath.eraseFromDisk();
+        return NULL;
+    }
+    sys::RemoveFileOnSignal(uniqueObjPath);
+
+    // assemble the assembly code
+    void* buffer = NULL;
+    bool asmResult = this->assemble(uniqueAsmPath.toString(), 
+                                            uniqueObjPath.toString(), errMsg);
+    if ( !asmResult ) {
+        // read .o file into memory buffer
+        const sys::FileStatus* objStatus;
+        objStatus = uniqueObjPath.getFileStatus(false, &errMsg);
+        if ( objStatus != NULL ) {
+            *length = objStatus->getSize();
+            // use malloc() because caller will own this buffer and free() it 
+            buffer = ::malloc(*length);
+            if ( buffer != NULL ) {
+                int fd = ::open(uniqueObjPath.c_str(), O_RDONLY, 0);
+                if ( fd != -1 ) {
+                    // read object file contents into buffer
+                    if ( ::read(fd, buffer, *length) != (ssize_t)*length ) {
+                        errMsg = "error reading object file";
+                        free(buffer);
+                        buffer = NULL;
+                    }
+                    close(fd);
+                }
+                else {
+                    errMsg = "error opening object file";
+                    free(buffer);
+                    buffer = NULL;
+                }
+            }
+            else {
+                errMsg = "error mallocing space for object file";
+            }
+        }
+        else {
+            errMsg = "error stat'ing object file";
+        }
+    }
+    // clean up temp files
+    uniqueAsmPath.eraseFromDisk();
+    uniqueObjPath.eraseFromDisk();
+    return buffer;
+}
+
+
+bool LTOCodeGenerator::assemble(const std::string& asmPath, 
+                                const std::string& objPath, std::string& errMsg)
+{
+    // find compiler driver
+    const sys::Path gcc = sys::Program::FindProgramByName("gcc");
+    if ( gcc.isEmpty() ) {
+        errMsg = "can't locate gcc";
+        return true;
+    }
+
+    // build argument list
+    std::vector<const char*> args;
+    std::string targetTriple = _linker.getModule()->getTargetTriple();
+    args.push_back(gcc.c_str());
+    if ( targetTriple.find("darwin") != targetTriple.size() ) {
+        if (strncmp(targetTriple.c_str(), "i686-apple-", 11) == 0) {
+            args.push_back("-arch");
+            args.push_back("i386");
+        }
+        else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
+            args.push_back("-arch");
+            args.push_back("x86_64");
+        }
+        else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
+            args.push_back("-arch");
+            args.push_back("ppc");
+        }
+        else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
+            args.push_back("-arch");
+            args.push_back("ppc64");
+        }
+    }
+    args.push_back("-c");
+    args.push_back("-x");
+    args.push_back("assembler");
+    args.push_back("-o");
+    args.push_back(objPath.c_str());
+    args.push_back(asmPath.c_str());
+    args.push_back(0);
+
+    // invoke assembler
+    if ( sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &errMsg) ) {
+        errMsg = "error in assembly";    
+        return true;
+    }
+    return false; // success
+}
+
+
+
+bool LTOCodeGenerator::determineTarget(std::string& errMsg)
+{
+    if ( _target == NULL ) {
+        // create target machine from info for merged modules
+        Module* mergedModule = _linker.getModule();
+        const TargetMachineRegistry::entry* march = 
+          TargetMachineRegistry::getClosestStaticTargetForModule(
+                                                       *mergedModule, errMsg);
+        if ( march == NULL )
+            return true;
+        std::string features;
+        _target = march->CtorFn(*mergedModule, features);
+    }
+    return false;
+}
+
+void LTOCodeGenerator::applyScopeRestrictions()
+{
+    if ( !_scopeRestrictionsDone ) {
+        Module* mergedModule = _linker.getModule();
+
+        // Start off with a verification pass.
+        PassManager passes;
+        passes.add(createVerifierPass());
+
+        // mark which symbols can not be internalized 
+        if ( !_mustPreserveSymbols.empty() ) {
+            Mangler mangler(*mergedModule, 
+                                _target->getTargetAsmInfo()->getGlobalPrefix());
+            std::vector<const char*> mustPreserveList;
+            for (Module::iterator f = mergedModule->begin(), 
+                                        e = mergedModule->end(); f != e; ++f) {
+                if ( !f->isDeclaration() 
+                  && _mustPreserveSymbols.count(mangler.getValueName(f)) )
+                    mustPreserveList.push_back(::strdup(f->getName().c_str()));
+            }
+            for (Module::global_iterator v = mergedModule->global_begin(), 
+                                 e = mergedModule->global_end(); v !=  e; ++v) {
+                if ( !v->isDeclaration()
+                  && _mustPreserveSymbols.count(mangler.getValueName(v)) )
+                    mustPreserveList.push_back(::strdup(v->getName().c_str()));
+            }
+            passes.add(createInternalizePass(mustPreserveList));
+        }
+        // apply scope restrictions
+        passes.run(*mergedModule);
+        
+        _scopeRestrictionsDone = true;
+    }
+}
+
+
+/// Optimize merged modules using various IPO passes
+bool LTOCodeGenerator::generateAssemblyCode(std::ostream& out, std::string& errMsg)
+{
+    if (  this->determineTarget(errMsg) ) 
+        return true;
+
+    // mark which symbols can not be internalized 
+    this->applyScopeRestrictions();
+
+    Module* mergedModule = _linker.getModule();
+
+     // If target supports exception handling then enable it now.
+    if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
+        llvm::ExceptionHandling = true;
+
+    // set codegen model
+    switch( _codeModel ) {
+        case LTO_CODEGEN_PIC_MODEL_STATIC:
+            _target->setRelocationModel(Reloc::Static);
+            break;
+        case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
+            _target->setRelocationModel(Reloc::PIC_);
+            break;
+        case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
+            _target->setRelocationModel(Reloc::DynamicNoPIC);
+            break;
+    }
+
+    // Instantiate the pass manager to organize the passes.
+    PassManager passes;
+
+    // Start off with a verification pass.
+    passes.add(createVerifierPass());
+
+    // Add an appropriate TargetData instance for this module...
+    passes.add(new TargetData(*_target->getTargetData()));
+    
+    // Now that we internalized some globals, see if we can hack on them!
+    passes.add(createGlobalOptimizerPass());
+
+    // Linking modules together can lead to duplicated global constants, only
+    // keep one copy of each constant...
+    passes.add(createConstantMergePass());
+
+    // If the -s command line option was specified, strip the symbols out of the
+    // resulting program to make it smaller.  -s is a GLD option that we are
+    // supporting.
+    if( !llvm::ExceptionHandling ) {
+        // FIXME : This causes multiple nameless _.eh symbols on 
+        // darwin when EH is ON.
+        passes.add(createStripSymbolsPass());
+    }
+    
+    // Propagate constants at call sites into the functions they call.
+    passes.add(createIPConstantPropagationPass());
+
+    // Remove unused arguments from functions...
+    passes.add(createDeadArgEliminationPass());
+
+    passes.add(createFunctionInliningPass()); // Inline small functions
+
+    passes.add(createPruneEHPass());            // Remove dead EH info
+
+    passes.add(createGlobalDCEPass());          // Remove dead functions
+
+    // If we didn't decide to inline a function, check to see if we can
+    // transform it to pass arguments by value instead of by reference.
+    passes.add(createArgumentPromotionPass());
+
+    // The IPO passes may leave cruft around.  Clean up after them.
+    passes.add(createInstructionCombiningPass());
+
+    passes.add(createScalarReplAggregatesPass()); // Break up allocas
+
+    // Run a few AA driven optimizations here and now, to cleanup the code.
+    passes.add(createGlobalsModRefPass());      // IP alias analysis
+
+    passes.add(createLICMPass());               // Hoist loop invariants
+    passes.add(createLoadValueNumberingPass()); // GVN for load instrs
+    passes.add(createGCSEPass());               // Remove common subexprs
+    passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
+
+    // Cleanup and simplify the code after the scalar optimizations.
+    passes.add(createInstructionCombiningPass());
+
+    // Delete basic blocks, which optimization passes may have killed...
+    passes.add(createCFGSimplificationPass());
+
+    // Now that we have optimized the program, discard unreachable functions...
+    passes.add(createGlobalDCEPass());
+
+    // Make sure everything is still good.
+    passes.add(createVerifierPass());
+
+    FunctionPassManager* codeGenPasses =
+            new FunctionPassManager(new ExistingModuleProvider(mergedModule));
+
+    codeGenPasses->add(new TargetData(*_target->getTargetData()));
+
+    MachineCodeEmitter* mce = NULL;
+
+    switch (_target->addPassesToEmitFile(*codeGenPasses, out,
+                                      TargetMachine::AssemblyFile, true)) {
+        case FileModel::MachOFile:
+            mce = AddMachOWriter(*codeGenPasses, out, *_target);
+            break;
+        case FileModel::ElfFile:
+            mce = AddELFWriter(*codeGenPasses, out, *_target);
+            break;
+        case FileModel::AsmFile:
+            break;
+        case FileModel::Error:
+        case FileModel::None:
+            errMsg = "target file type not supported";
+            return true;
+    }
+
+    if (_target->addPassesToEmitFileFinish(*codeGenPasses, mce, true)) {
+        errMsg = "target does not support generation of this file type";
+        return true;
+    }
+
+    // Run our queue of passes all at once now, efficiently.
+    passes.run(*mergedModule);
+
+    // Run the code generator, and write assembly file
+    codeGenPasses->doInitialization();
+    for (Module::iterator it = mergedModule->begin(),
+                e = mergedModule->end(); it != e; ++it) {
+        if (!it->isDeclaration())
+            codeGenPasses->run(*it);
+    }
+    codeGenPasses->doFinalization();
+
+    return false; // success
+}
+
+
+
diff --git a/tools/lto2/LTOCodeGenerator.h b/tools/lto2/LTOCodeGenerator.h
new file mode 100644
index 0000000..e9c1f78
--- /dev/null
+++ b/tools/lto2/LTOCodeGenerator.h
@@ -0,0 +1,59 @@
+//===-LTOCodeGenerator.h - LLVM Link Time Optimizer -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file declares the LTOCodeGenerator class. 
+//
+//===----------------------------------------------------------------------===//
+
+
+#ifndef LTO_CODE_GENERATOR_H
+#define LTO_CODE_GENERATOR_H
+
+#include "llvm/Linker.h"
+#include "llvm/ADT/StringMap.h"
+
+
+
+//
+// C++ class which implements the opaque lto_code_gen_t
+//
+class LTOCodeGenerator {
+public:
+    static const char*        getVersionString();
+    
+                            LTOCodeGenerator();
+                            ~LTOCodeGenerator();
+                            
+    bool                addModule(class LTOModule*, std::string& errMsg);
+    bool                setDebugInfo(lto_debug_model, std::string& errMsg);
+    bool                setCodePICModel(lto_codegen_model, std::string& errMsg);
+    void                addMustPreserveSymbol(const char* sym);
+    bool                writeMergedModules(const char* path, std::string& errMsg);
+    void*               compile(size_t* length, std::string& errMsg);
+    
+private:
+    bool                generateAssemblyCode(std::ostream& out, 
+                                                        std::string& errMsg);
+    bool                assemble(const std::string& asmPath, 
+                            const std::string& objPath, std::string& errMsg);
+    void                applyScopeRestrictions();
+    bool                determineTarget(std::string& errMsg);
+    
+    typedef llvm::StringMap<uint8_t> StringSet;
+
+    llvm::Linker                _linker;
+    llvm::TargetMachine*        _target;
+    bool                        _emitDwarfDebugInfo;
+    bool                        _scopeRestrictionsDone;
+    lto_codegen_model           _codeModel;
+    StringSet                   _mustPreserveSymbols;
+};
+
+#endif // LTO_CODE_GENERATOR_H
+
diff --git a/tools/lto2/LTOModule.cpp b/tools/lto2/LTOModule.cpp
new file mode 100644
index 0000000..e10ea5f
--- /dev/null
+++ b/tools/lto2/LTOModule.cpp
@@ -0,0 +1,329 @@
+//===-LTOModule.cpp - LLVM Link Time Optimizer ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Link Time Optimization library. This library is 
+// intended to be used by linker to optimize code at link time.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/PassManager.h"
+#include "llvm/Linker.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/ModuleProvider.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/SystemUtils.h"
+#include "llvm/Support/Mangler.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/System/Program.h"
+#include "llvm/System/Path.h"
+#include "llvm/System/Signals.h"
+#include "llvm/Target/SubtargetFeature.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetMachineRegistry.h"
+#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Analysis/LoadValueNumbering.h"
+#include "llvm/Support/MathExtras.h"
+
+#include "LTOModule.h"
+
+#include <fstream>
+
+using namespace llvm;
+
+bool LTOModule::isBitcodeFile(const void* mem, size_t length)
+{
+    return ( llvm::sys::IdentifyFileType((char*)mem, length) 
+                                            == llvm::sys::Bitcode_FileType );
+}
+
+bool LTOModule::isBitcodeFile(const char* path)
+{
+    return llvm::sys::Path(path).isBitcodeFile();
+}
+
+bool LTOModule::isBitcodeFileForTarget(const void* mem, 
+                                    size_t length, const char* triplePrefix) 
+{
+    bool result = false;
+    MemoryBuffer* buffer;
+    buffer = MemoryBuffer::getMemBuffer((char*)mem, (char*)mem+length);
+    if ( buffer != NULL ) {
+        ModuleProvider* mp = getBitcodeModuleProvider(buffer);
+        if ( mp != NULL ) {
+            std::string actualTarget = mp->getModule()->getTargetTriple();
+            if  ( strncmp(actualTarget.c_str(), triplePrefix, 
+                                    strlen(triplePrefix)) == 0) {
+                result = true;
+            }
+            //  mp destructor will delete buffer
+            delete mp;
+        }
+        else {
+            // if getBitcodeModuleProvider failed, we need to delete buffer
+            delete buffer;
+        }
+    }
+    return result;
+}
+
+bool LTOModule::isBitcodeFileForTarget(const char* path,
+                                                const char* triplePrefix) 
+{
+    bool result = false;
+    MemoryBuffer* buffer;
+    buffer = MemoryBuffer::getFile(path, strlen(path));
+    if ( buffer != NULL ) {
+        ModuleProvider* mp = getBitcodeModuleProvider(buffer);
+        if ( mp != NULL ) {
+            std::string actualTarget = mp->getModule()->getTargetTriple();
+            if  ( strncmp(actualTarget.c_str(), triplePrefix, 
+                                    strlen(triplePrefix)) == 0) {
+                result = true;
+            }
+            //  mp destructor will delete buffer
+            delete mp;
+        }
+        else {
+            // if getBitcodeModuleProvider failed, we need to delete buffer
+            delete buffer;
+        }
+    }
+    return result;
+}
+
+
+LTOModule::LTOModule(Module* m, TargetMachine* t) 
+ : _module(m), _target(t), _symbolsParsed(false)
+{
+}
+
+LTOModule::~LTOModule()
+{
+    delete _module;
+    if ( _target != NULL )
+        delete _target;
+}
+
+
+LTOModule* LTOModule::makeLTOModule(const char* path, std::string& errMsg)
+{
+    MemoryBuffer* buffer = MemoryBuffer::getFile(path, strlen(path));
+    if ( buffer != NULL ) {
+        Module* m = ParseBitcodeFile(buffer, &errMsg);
+        delete buffer;
+        if ( m != NULL ) {
+            const TargetMachineRegistry::entry* march = 
+              TargetMachineRegistry::getClosestStaticTargetForModule(*m, errMsg);
+            if ( march != NULL ) {
+                std::string features;
+                TargetMachine*    target = march->CtorFn(*m, features);
+                return new LTOModule(m, target);
+            }
+        }
+    }
+    return NULL;
+}
+
+LTOModule* LTOModule::makeLTOModule(const void* mem, size_t length, 
+                                                        std::string& errMsg)
+{
+    MemoryBuffer* buffer;
+    buffer = MemoryBuffer::getMemBuffer((char*)mem, (char*)mem+length);
+    if ( buffer != NULL ) {
+        Module* m = ParseBitcodeFile(buffer, &errMsg);
+        delete buffer;
+        if ( m != NULL ) {
+            const TargetMachineRegistry::entry* march = 
+             TargetMachineRegistry::getClosestStaticTargetForModule(*m, errMsg);
+            if ( march != NULL ) {
+                std::string features;
+                TargetMachine*    target = march->CtorFn(*m, features);
+                return new LTOModule(m, target);
+            }
+        }
+    }
+    return NULL;
+}
+
+
+const char* LTOModule::getTargetTriple()
+{
+    return _module->getTargetTriple().c_str();
+}
+
+void LTOModule::addDefinedSymbol(GlobalValue* def, Mangler &mangler, 
+                                bool isFunction)
+{    
+    const char* symbolName = ::strdup(mangler.getValueName(def).c_str());
+    
+    // set alignment part log2() can have rounding errors
+    uint32_t align = def->getAlignment();
+    uint32_t attr = align ? __builtin_ctz(def->getAlignment()) : 0;
+    
+    // set permissions part
+    if ( isFunction )
+        attr |= LTO_SYMBOL_PERMISSIONS_CODE;
+    else {
+        GlobalVariable* gv = dyn_cast<GlobalVariable>(def);
+        if ( (gv != NULL) && gv->isConstant() )
+            attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
+        else
+            attr |= LTO_SYMBOL_PERMISSIONS_DATA;
+    }
+    
+    // set definition part 
+    if ( def->hasWeakLinkage() || def->hasLinkOnceLinkage() ) {
+        // lvm bitcode does not differenciate between weak def data 
+        // and tentative definitions!
+        // HACK HACK HACK
+        // C++ does not use tentative definitions, but does use weak symbols
+        // so guess that anything that looks like a C++ symbol is weak and others
+        // are tentative definitions
+        if ( (strncmp(symbolName, "__Z", 3) == 0) )
+            attr |= LTO_SYMBOL_DEFINITION_WEAK;
+        else {
+            attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
+        }
+    }
+    else { 
+        attr |= LTO_SYMBOL_DEFINITION_REGULAR;
+    }
+    
+    // set scope part
+    if ( def->hasHiddenVisibility() )
+        attr |= LTO_SYMBOL_SCOPE_HIDDEN;
+    else if ( def->hasExternalLinkage() || def->hasWeakLinkage() )
+        attr |= LTO_SYMBOL_SCOPE_DEFAULT;
+    else
+        attr |= LTO_SYMBOL_SCOPE_INTERNAL;
+
+    // add to table of symbols
+    NameAndAttributes info;
+    info.name = symbolName;
+    info.attributes = (lto_symbol_attributes)attr;
+    _symbols.push_back(info);
+    _defines[info.name] = 1;
+}
+
+
+void LTOModule::addUndefinedSymbol(const char* name)
+{    
+    // ignore all llvm.* symbols
+    if ( strncmp(name, "llvm.", 5) != 0 ) {
+        _undefines[name] = 1;
+    }
+}
+
+
+
+// Find exeternal symbols referenced by VALUE. This is a recursive function.
+void LTOModule::findExternalRefs(Value* value, Mangler &mangler) {
+
+    if (GlobalValue* gv = dyn_cast<GlobalValue>(value)) {
+        if ( !gv->hasExternalLinkage() )
+            addUndefinedSymbol(mangler.getValueName(gv).c_str());
+    }
+
+    // GlobalValue, even with InternalLinkage type, may have operands with 
+    // ExternalLinkage type. Do not ignore these operands.
+    if (Constant* c = dyn_cast<Constant>(value)) {
+        // Handle ConstantExpr, ConstantStruct, ConstantArry etc..
+        for (unsigned i = 0, e = c->getNumOperands(); i != e; ++i)
+            findExternalRefs(c->getOperand(i), mangler);
+    }
+}
+
+
+uint32_t LTOModule::getSymbolCount()
+{
+    if ( !_symbolsParsed ) {
+        _symbolsParsed = true;
+        
+        // Use mangler to add GlobalPrefix to names to match linker names.
+        Mangler mangler(*_module, _target->getTargetAsmInfo()->getGlobalPrefix());
+
+        // add functions
+        for (Module::iterator f = _module->begin(); f != _module->end(); ++f) {
+            if ( f->isDeclaration() ) {
+                addUndefinedSymbol(mangler.getValueName(f).c_str());
+            }
+            else {
+                addDefinedSymbol(f, mangler, true);
+                // add external symbols referenced by this function.
+                for (Function::iterator b = f->begin(); b != f->end(); ++b) {
+                    for (BasicBlock::iterator i = b->begin(); 
+                                                        i != b->end(); ++i) {
+                        for (unsigned count = 0, total = i->getNumOperands(); 
+                                                    count != total; ++count) {
+                            findExternalRefs(i->getOperand(count), mangler);
+                        }
+                    }
+                }
+            }
+        }
+        
+        // add data 
+        for (Module::global_iterator v = _module->global_begin(), 
+                                    e = _module->global_end(); v !=  e; ++v) {
+            if ( v->isDeclaration() ) {
+                addUndefinedSymbol(mangler.getValueName(v).c_str());
+            }
+            else {
+                addDefinedSymbol(v, mangler, false);
+                // add external symbols referenced by this data
+                for (unsigned count = 0, total = v->getNumOperands(); 
+                                                count != total; ++count) {
+                    findExternalRefs(v->getOperand(count), mangler);
+                }
+            }
+        }
+
+        // make symbols for all undefines
+        for (StringSet::iterator it=_undefines.begin(); 
+                                                it != _undefines.end(); ++it) {
+            // if this symbol also has a definition, then don't make an undefine
+            // because it is a tentative definition
+            if ( _defines.find(it->getKeyData(), it->getKeyData()+it->getKeyLength()) == _defines.end() ) {
+                NameAndAttributes info;
+                info.name = it->getKeyData();
+                info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
+                _symbols.push_back(info);
+            }
+        }
+        
+    }
+    
+    return _symbols.size();
+}
+
+
+lto_symbol_attributes LTOModule::getSymbolAttributes(uint32_t index)
+{
+    if ( index < _symbols.size() )
+        return _symbols[index].attributes;
+    else
+        return lto_symbol_attributes(0);
+}
+
+const char* LTOModule::getSymbolName(uint32_t index)
+{
+    if ( index < _symbols.size() )
+        return _symbols[index].name;
+    else
+        return NULL;
+}
+
diff --git a/tools/lto2/LTOModule.h b/tools/lto2/LTOModule.h
new file mode 100644
index 0000000..9770757
--- /dev/null
+++ b/tools/lto2/LTOModule.h
@@ -0,0 +1,83 @@
+//===-LTOModule.h - LLVM Link Time Optimizer ------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file declares the LTOModule class. 
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LTO_MODULE_H
+#define LTO_MODULE_H
+
+#include "llvm/Module.h"
+#include "llvm/GlobalValue.h"
+#include "llvm/Constants.h"
+#include "llvm/Support/Mangler.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/ADT/StringMap.h"
+
+#include "llvm-c/lto.h"
+
+#include <vector>
+
+
+//
+// C++ class which implements the opaque lto_module_t
+//
+class LTOModule {
+public:
+
+    static bool              isBitcodeFile(const void* mem, size_t length);
+    static bool              isBitcodeFile(const char* path);
+
+    static bool              isBitcodeFileForTarget(const void* mem, 
+                                    size_t length, const char* triplePrefix);
+
+    static bool              isBitcodeFileForTarget(const char* path, 
+                                                    const char* triplePrefix);
+
+    static LTOModule*        makeLTOModule(const char* path, std::string& errMsg);
+    static LTOModule*        makeLTOModule(const void* mem, size_t length,
+                                                            std::string& errMsg);
+                            ~LTOModule();
+
+    const char*              getTargetTriple();
+    uint32_t                 getSymbolCount();
+    lto_symbol_attributes    getSymbolAttributes(uint32_t index);
+    const char*              getSymbolName(uint32_t index);
+    
+    llvm::Module *           getLLVVMModule() { return _module; }
+    bool                     targetSupported() { return (_target !=  NULL); }
+
+private:
+                            LTOModule(llvm::Module* m, llvm::TargetMachine* t);
+
+    void                    addDefinedSymbol(llvm::GlobalValue* def, 
+                                                    llvm::Mangler& mangler, 
+                                                    bool isFunction);
+    void                    addUndefinedSymbol(const char* name);
+    void                    findExternalRefs(llvm::Value* value, 
+                                                llvm::Mangler& mangler);
+    
+    typedef llvm::StringMap<uint8_t> StringSet;
+    
+    struct NameAndAttributes { 
+        const char*            name; 
+        lto_symbol_attributes  attributes; 
+    };
+
+    llvm::Module *                   _module;
+    llvm::TargetMachine *            _target;
+    bool                             _symbolsParsed;
+    std::vector<NameAndAttributes>   _symbols;
+    StringSet                        _defines;    // only needed to disambiguate tentative definitions
+    StringSet                        _undefines;  // only needed to disambiguate tentative definitions
+};
+
+#endif // LTO_MODULE_H
+
diff --git a/tools/lto2/Makefile b/tools/lto2/Makefile
new file mode 100644
index 0000000..30f6ed8
--- /dev/null
+++ b/tools/lto2/Makefile
@@ -0,0 +1,45 @@
+##===- tools/lto2/Makefile ---------------------------------*- Makefile -*-===##
+# 
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+# 
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../..
+LIBRARYNAME = LTO
+
+# Include this here so we can get the configuration of the targets
+# that have been configured for construction. We have to do this 
+# early so we can set up LINK_COMPONENTS before includeing Makefile.rules
+include $(LEVEL)/Makefile.config
+
+LINK_LIBS_IN_SHARED = 1
+ifeq ($(OS),Darwin)
+  SHARED_LIBRARY = 1
+  DONT_BUILD_RELINKED = 1
+else
+  BUILD_ARCHIVE = 1
+endif
+
+LINK_COMPONENTS := $(TARGETS_TO_BUILD) ipo scalaropts linker bitreader bitwriter
+
+include $(LEVEL)/Makefile.common
+
+ifeq ($(OS),Darwin)
+    # set dylib internal version number to llvmCore submission number
+    ifdef LLVM_SUBMIT_VERSION
+        LLVMLibsOptions := $(LLVMLibsOptions) -Wl,-current_version \
+						-Wl,$(LLVM_SUBMIT_VERSION).$(LLVM_SUBMIT_SUBVERSION)
+    endif
+    # extra options to override libtool defaults 
+    LLVMLibsOptions    := $(LLVMLibsOptions)  \
+				-no-undefined  -avoid-version \
+                -Wl,-exported_symbols_list -Wl,lto.exports \
+                -Wl,-dead_strip \
+                -Wl,-install_name \
+				-Wl,"@executable_path/../lib/lib$(LIBRARYNAME)$(SHLIBEXT)" \
+                -Wl,-seg1addr -Wl,0xE0000000 
+
+endif
diff --git a/tools/lto2/lto.cpp b/tools/lto2/lto.cpp
new file mode 100644
index 0000000..d6f1d98
--- /dev/null
+++ b/tools/lto2/lto.cpp
@@ -0,0 +1,240 @@
+//===-lto.cpp - LLVM Link Time Optimizer ----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Link Time Optimization library. This library is 
+// intended to be used by linker to optimize code at link time.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm-c/lto.h"
+
+#include "LTOModule.h"
+#include "LTOCodeGenerator.h"
+
+
+// holds most recent error string
+// *** not thread safe ***
+static std::string sLastErrorString;
+
+
+
+//
+// returns a printable string
+//
+extern const char* lto_get_version()
+{
+    return LTOCodeGenerator::getVersionString();
+}
+
+//
+// returns the last error string or NULL if last operation was sucessful
+//
+const char* lto_get_error_message()
+{
+    return sLastErrorString.c_str();
+}
+
+
+
+//
+// validates if a file is a loadable object file
+//
+bool lto_module_is_object_file(const char* path)
+{
+    return LTOModule::isBitcodeFile(path);
+}
+
+
+//
+// validates if a file is a loadable object file compilable for requested target
+//
+bool lto_module_is_object_file_for_target(const char* path, 
+                                            const char* target_triplet_prefix)
+{
+    return LTOModule::isBitcodeFileForTarget(path, target_triplet_prefix);
+}
+
+
+//
+// validates if a buffer is a loadable object file
+//
+bool lto_module_is_object_file_in_memory(const void* mem, size_t length)
+{
+    return LTOModule::isBitcodeFile(mem, length);
+}
+
+
+//
+// validates if a buffer is a loadable object file compilable for the target
+//
+bool lto_module_is_object_file_in_memory_for_target(const void* mem, 
+                            size_t length, const char* target_triplet_prefix)
+{
+    return LTOModule::isBitcodeFileForTarget(mem, length, target_triplet_prefix);
+}
+
+
+
+//
+// loads an object file from disk  
+// returns NULL on error (check lto_get_error_message() for details)
+//
+lto_module_t lto_module_create(const char* path)
+{
+     return LTOModule::makeLTOModule(path, sLastErrorString);
+}
+
+
+//
+// loads an object file from memory 
+// returns NULL on error (check lto_get_error_message() for details)
+//
+lto_module_t lto_module_create_from_memory(const void* mem, size_t length)
+{
+     return LTOModule::makeLTOModule(mem, length, sLastErrorString);
+}
+
+
+//
+// frees all memory for a module
+// upon return the lto_module_t is no longer valid
+//
+void lto_module_dispose(lto_module_t mod)
+{
+    delete mod;
+}
+
+
+//
+// returns triplet string which the object module was compiled under
+//
+const char* lto_module_get_target_triple(lto_module_t mod)
+{
+    return mod->getTargetTriple();
+}
+
+
+//
+// returns the number of symbols in the object module
+//
+uint32_t lto_module_get_num_symbols(lto_module_t mod)
+{
+    return mod->getSymbolCount();
+}
+
+//
+// returns the name of the ith symbol in the object module
+//
+const char* lto_module_get_symbol_name(lto_module_t mod, uint32_t index)
+{
+    return mod->getSymbolName(index);
+}
+
+
+//
+// returns the attributes of the ith symbol in the object module
+//
+lto_symbol_attributes lto_module_get_symbol_attribute(lto_module_t mod, 
+                                                            uint32_t index)
+{
+    return mod->getSymbolAttributes(index);
+}
+
+
+
+
+
+//
+// instantiates a code generator
+// returns NULL if there is an error
+//
+lto_code_gen_t lto_codegen_create()
+{
+     return new LTOCodeGenerator();
+}
+
+
+
+//
+// frees all memory for a code generator
+// upon return the lto_code_gen_t is no longer valid
+//
+void lto_codegen_dispose(lto_code_gen_t cg)
+{
+    delete cg;
+}
+
+
+
+//
+// add an object module to the set of modules for which code will be generated
+// returns true on error (check lto_get_error_message() for details)
+//
+bool lto_codegen_add_module(lto_code_gen_t cg, lto_module_t mod)
+{
+    return cg->addModule(mod, sLastErrorString);
+}
+
+
+//
+// sets what if any format of debug info should be generated
+// returns true on error (check lto_get_error_message() for details)
+//
+bool lto_codegen_set_debug_model(lto_code_gen_t cg, lto_debug_model debug)
+{
+    return cg->setDebugInfo(debug, sLastErrorString);
+}
+
+
+//
+// sets what code model to generated
+// returns true on error (check lto_get_error_message() for details)
+//
+bool lto_codegen_set_pic_model(lto_code_gen_t cg, lto_codegen_model model)
+{
+    return cg->setCodePICModel(model, sLastErrorString);
+}
+
+//
+// adds to a list of all global symbols that must exist in the final
+// generated code.  If a function is not listed there, it might be
+// inlined into every usage and optimized away.
+//
+void lto_codegen_add_must_preserve_symbol(lto_code_gen_t cg, const char* symbol)
+{
+    cg->addMustPreserveSymbol(symbol);
+}
+
+
+//
+// writes a new file at the specified path that contains the
+// merged contents of all modules added so far.
+// returns true on error (check lto_get_error_message() for details)
+//
+bool lto_codegen_write_merged_modules(lto_code_gen_t cg, const char* path)
+{
+   return cg->writeMergedModules(path, sLastErrorString);
+}
+
+
+//
+// generates code for all added modules into one object file
+// On sucess returns a pointer to a generated mach-o buffer and
+// length set to the buffer size.  Client must free() the buffer
+// when done.
+// On failure, returns NULL (check lto_get_error_message() for details)
+//
+extern void*
+lto_codegen_compile(lto_code_gen_t cg, size_t* length)
+{
+    return cg->compile(length, sLastErrorString);
+}
+
+
+
diff --git a/tools/lto2/lto.exports b/tools/lto2/lto.exports
new file mode 100644
index 0000000..415cbbe
--- /dev/null
+++ b/tools/lto2/lto.exports
@@ -0,0 +1,22 @@
+_lto_get_error_message
+_lto_get_version
+_lto_module_create
+_lto_module_create_from_memory
+_lto_module_get_num_symbols
+_lto_module_get_symbol_attribute
+_lto_module_get_symbol_name
+_lto_module_get_target_triple
+_lto_module_is_object_file
+_lto_module_is_object_file_for_target
+_lto_module_is_object_file_in_memory
+_lto_module_is_object_file_in_memory_for_target
+_lto_module_dispose
+_lto_codegen_add_module
+_lto_codegen_add_must_preserve_symbol
+_lto_codegen_compile
+_lto_codegen_create
+_lto_codegen_dispose
+_lto_codegen_set_debug_model
+_lto_codegen_set_pic_model
+_lto_codegen_write_merged_modules
+