1 //===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
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 file implements the Link Time Optimization library. This library is
11 // intended to be used by linker to optimize code at link time.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/LTO/LTOCodeGenerator.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/Analysis/Passes.h"
18 #include "llvm/Bitcode/ReaderWriter.h"
19 #include "llvm/CodeGen/RuntimeLibcalls.h"
20 #include "llvm/Config/config.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/DerivedTypes.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/DiagnosticPrinter.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Mangler.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/IR/Verifier.h"
30 #include "llvm/InitializePasses.h"
31 #include "llvm/LTO/LTOModule.h"
32 #include "llvm/Linker/Linker.h"
33 #include "llvm/MC/MCAsmInfo.h"
34 #include "llvm/MC/MCContext.h"
35 #include "llvm/MC/SubtargetFeature.h"
36 #include "llvm/PassManager.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/FileSystem.h"
39 #include "llvm/Support/FormattedStream.h"
40 #include "llvm/Support/Host.h"
41 #include "llvm/Support/MemoryBuffer.h"
42 #include "llvm/Support/Signals.h"
43 #include "llvm/Support/TargetRegistry.h"
44 #include "llvm/Support/TargetSelect.h"
45 #include "llvm/Support/ToolOutputFile.h"
46 #include "llvm/Support/raw_ostream.h"
47 #include "llvm/Target/TargetLibraryInfo.h"
48 #include "llvm/Target/TargetLowering.h"
49 #include "llvm/Target/TargetOptions.h"
50 #include "llvm/Target/TargetRegisterInfo.h"
51 #include "llvm/Target/TargetSubtargetInfo.h"
52 #include "llvm/Transforms/IPO.h"
53 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
54 #include "llvm/Transforms/ObjCARC.h"
55 #include <system_error>
58 const char* LTOCodeGenerator::getVersionString() {
59 #ifdef LLVM_VERSION_INFO
60 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
62 return PACKAGE_NAME " version " PACKAGE_VERSION;
66 LTOCodeGenerator::LTOCodeGenerator()
67 : Context(getGlobalContext()), IRLinker(new Module("ld-temp.o", Context)) {
71 LTOCodeGenerator::LTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
72 : OwnedContext(std::move(Context)), Context(*OwnedContext),
73 IRLinker(new Module("ld-temp.o", *OwnedContext)) {
77 void LTOCodeGenerator::initialize() {
79 EmitDwarfDebugInfo = false;
80 ScopeRestrictionsDone = false;
81 CodeModel = LTO_CODEGEN_PIC_MODEL_DEFAULT;
82 DiagHandler = nullptr;
83 DiagContext = nullptr;
85 initializeLTOPasses();
88 LTOCodeGenerator::~LTOCodeGenerator() {
92 IRLinker.deleteModule();
94 for (std::vector<char *>::iterator I = CodegenOptions.begin(),
95 E = CodegenOptions.end();
100 // Initialize LTO passes. Please keep this funciton in sync with
101 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
102 // passes are initialized.
103 void LTOCodeGenerator::initializeLTOPasses() {
104 PassRegistry &R = *PassRegistry::getPassRegistry();
106 initializeInternalizePassPass(R);
107 initializeIPSCCPPass(R);
108 initializeGlobalOptPass(R);
109 initializeConstantMergePass(R);
110 initializeDAHPass(R);
111 initializeInstCombinerPass(R);
112 initializeSimpleInlinerPass(R);
113 initializePruneEHPass(R);
114 initializeGlobalDCEPass(R);
115 initializeArgPromotionPass(R);
116 initializeJumpThreadingPass(R);
117 initializeSROAPass(R);
118 initializeSROA_DTPass(R);
119 initializeSROA_SSAUpPass(R);
120 initializeFunctionAttrsPass(R);
121 initializeGlobalsModRefPass(R);
122 initializeLICMPass(R);
123 initializeMergedLoadStoreMotionPass(R);
124 initializeGVNPass(R);
125 initializeMemCpyOptPass(R);
126 initializeDCEPass(R);
127 initializeCFGSimplifyPassPass(R);
130 bool LTOCodeGenerator::addModule(LTOModule *mod) {
131 bool ret = IRLinker.linkInModule(&mod->getModule());
133 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
134 for (int i = 0, e = undefs.size(); i != e; ++i)
135 AsmUndefinedRefs[undefs[i]] = 1;
140 void LTOCodeGenerator::setTargetOptions(TargetOptions options) {
144 void LTOCodeGenerator::setDebugInfo(lto_debug_model debug) {
146 case LTO_DEBUG_MODEL_NONE:
147 EmitDwarfDebugInfo = false;
150 case LTO_DEBUG_MODEL_DWARF:
151 EmitDwarfDebugInfo = true;
154 llvm_unreachable("Unknown debug format!");
157 void LTOCodeGenerator::setCodePICModel(lto_codegen_model model) {
159 case LTO_CODEGEN_PIC_MODEL_STATIC:
160 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
161 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
162 case LTO_CODEGEN_PIC_MODEL_DEFAULT:
166 llvm_unreachable("Unknown PIC model!");
169 bool LTOCodeGenerator::writeMergedModules(const char *path,
170 std::string &errMsg) {
171 if (!determineTarget(errMsg))
174 // mark which symbols can not be internalized
175 applyScopeRestrictions();
177 // create output file
179 tool_output_file Out(path, EC, sys::fs::F_None);
181 errMsg = "could not open bitcode file for writing: ";
186 // write bitcode to it
187 WriteBitcodeToFile(IRLinker.getModule(), Out.os());
190 if (Out.os().has_error()) {
191 errMsg = "could not write bitcode file: ";
193 Out.os().clear_error();
201 bool LTOCodeGenerator::compile_to_file(const char** name,
204 bool disableGVNLoadPRE,
205 bool disableVectorization,
206 std::string& errMsg) {
207 // make unique temp .o file to put generated object file
208 SmallString<128> Filename;
211 sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
213 errMsg = EC.message();
217 // generate object file
218 tool_output_file objFile(Filename.c_str(), FD);
221 generateObjectFile(objFile.os(), disableOpt, disableInline,
222 disableGVNLoadPRE, disableVectorization, errMsg);
223 objFile.os().close();
224 if (objFile.os().has_error()) {
225 objFile.os().clear_error();
226 sys::fs::remove(Twine(Filename));
232 sys::fs::remove(Twine(Filename));
236 NativeObjectPath = Filename.c_str();
237 *name = NativeObjectPath.c_str();
241 const void* LTOCodeGenerator::compile(size_t* length,
244 bool disableGVNLoadPRE,
245 bool disableVectorization,
246 std::string& errMsg) {
248 if (!compile_to_file(&name, disableOpt, disableInline, disableGVNLoadPRE,
249 disableVectorization, errMsg))
252 // read .o file into memory buffer
253 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
254 MemoryBuffer::getFile(name, -1, false);
255 if (std::error_code EC = BufferOrErr.getError()) {
256 errMsg = EC.message();
257 sys::fs::remove(NativeObjectPath);
260 NativeObjectFile = std::move(*BufferOrErr);
263 sys::fs::remove(NativeObjectPath);
265 // return buffer, unless error
266 if (!NativeObjectFile)
268 *length = NativeObjectFile->getBufferSize();
269 return NativeObjectFile->getBufferStart();
272 bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
276 std::string TripleStr = IRLinker.getModule()->getTargetTriple();
277 if (TripleStr.empty())
278 TripleStr = sys::getDefaultTargetTriple();
279 llvm::Triple Triple(TripleStr);
281 // create target machine from info for merged modules
282 const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
286 // The relocation model is actually a static member of TargetMachine and
287 // needs to be set before the TargetMachine is instantiated.
288 Reloc::Model RelocModel = Reloc::Default;
290 case LTO_CODEGEN_PIC_MODEL_STATIC:
291 RelocModel = Reloc::Static;
293 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
294 RelocModel = Reloc::PIC_;
296 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
297 RelocModel = Reloc::DynamicNoPIC;
299 case LTO_CODEGEN_PIC_MODEL_DEFAULT:
300 // RelocModel is already the default, so leave it that way.
304 // Construct LTOModule, hand over ownership of module and target. Use MAttr as
305 // the default set of features.
306 SubtargetFeatures Features(MAttr);
307 Features.getDefaultSubtargetFeatures(Triple);
308 std::string FeatureStr = Features.getString();
309 // Set a default CPU for Darwin triples.
310 if (MCpu.empty() && Triple.isOSDarwin()) {
311 if (Triple.getArch() == llvm::Triple::x86_64)
313 else if (Triple.getArch() == llvm::Triple::x86)
315 else if (Triple.getArch() == llvm::Triple::aarch64)
319 TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
320 RelocModel, CodeModel::Default,
321 CodeGenOpt::Aggressive);
325 void LTOCodeGenerator::
326 applyRestriction(GlobalValue &GV,
327 ArrayRef<StringRef> Libcalls,
328 std::vector<const char*> &MustPreserveList,
329 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
331 // There are no restrictions to apply to declarations.
332 if (GV.isDeclaration())
335 // There is nothing more restrictive than private linkage.
336 if (GV.hasPrivateLinkage())
339 SmallString<64> Buffer;
340 TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
342 if (MustPreserveSymbols.count(Buffer))
343 MustPreserveList.push_back(GV.getName().data());
344 if (AsmUndefinedRefs.count(Buffer))
347 // Conservatively append user-supplied runtime library functions to
348 // llvm.compiler.used. These could be internalized and deleted by
349 // optimizations like -globalopt, causing problems when later optimizations
350 // add new library calls (e.g., llvm.memset => memset and printf => puts).
351 // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
352 if (isa<Function>(GV) &&
353 std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
357 static void findUsedValues(GlobalVariable *LLVMUsed,
358 SmallPtrSetImpl<GlobalValue*> &UsedValues) {
359 if (!LLVMUsed) return;
361 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
362 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
363 if (GlobalValue *GV =
364 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
365 UsedValues.insert(GV);
368 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
369 const TargetLibraryInfo& TLI,
370 const TargetLowering *Lowering)
372 // TargetLibraryInfo has info on C runtime library calls on the current
374 for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
376 LibFunc::Func F = static_cast<LibFunc::Func>(I);
378 Libcalls.push_back(TLI.getName(F));
381 // TargetLowering has info on library calls that CodeGen expects to be
382 // available, both from the C runtime and compiler-rt.
384 for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
387 = Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
388 Libcalls.push_back(Name);
390 array_pod_sort(Libcalls.begin(), Libcalls.end());
391 Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
395 void LTOCodeGenerator::applyScopeRestrictions() {
396 if (ScopeRestrictionsDone)
398 Module *mergedModule = IRLinker.getModule();
400 // Start off with a verification pass.
402 passes.add(createVerifierPass());
403 passes.add(createDebugInfoVerifierPass());
405 // mark which symbols can not be internalized
406 Mangler Mangler(TargetMach->getSubtargetImpl()->getDataLayout());
407 std::vector<const char*> MustPreserveList;
408 SmallPtrSet<GlobalValue*, 8> AsmUsed;
409 std::vector<StringRef> Libcalls;
410 TargetLibraryInfo TLI(Triple(TargetMach->getTargetTriple()));
411 accumulateAndSortLibcalls(
412 Libcalls, TLI, TargetMach->getSubtargetImpl()->getTargetLowering());
414 for (Module::iterator f = mergedModule->begin(),
415 e = mergedModule->end(); f != e; ++f)
416 applyRestriction(*f, Libcalls, MustPreserveList, AsmUsed, Mangler);
417 for (Module::global_iterator v = mergedModule->global_begin(),
418 e = mergedModule->global_end(); v != e; ++v)
419 applyRestriction(*v, Libcalls, MustPreserveList, AsmUsed, Mangler);
420 for (Module::alias_iterator a = mergedModule->alias_begin(),
421 e = mergedModule->alias_end(); a != e; ++a)
422 applyRestriction(*a, Libcalls, MustPreserveList, AsmUsed, Mangler);
424 GlobalVariable *LLVMCompilerUsed =
425 mergedModule->getGlobalVariable("llvm.compiler.used");
426 findUsedValues(LLVMCompilerUsed, AsmUsed);
427 if (LLVMCompilerUsed)
428 LLVMCompilerUsed->eraseFromParent();
430 if (!AsmUsed.empty()) {
431 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
432 std::vector<Constant*> asmUsed2;
433 for (auto *GV : AsmUsed) {
434 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
435 asmUsed2.push_back(c);
438 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
440 new llvm::GlobalVariable(*mergedModule, ATy, false,
441 llvm::GlobalValue::AppendingLinkage,
442 llvm::ConstantArray::get(ATy, asmUsed2),
443 "llvm.compiler.used");
445 LLVMCompilerUsed->setSection("llvm.metadata");
448 passes.add(createInternalizePass(MustPreserveList));
450 // apply scope restrictions
451 passes.run(*mergedModule);
453 ScopeRestrictionsDone = true;
456 /// Optimize merged modules using various IPO passes
457 bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
460 bool DisableGVNLoadPRE,
461 bool DisableVectorization,
462 std::string &errMsg) {
463 if (!this->determineTarget(errMsg))
466 Module *mergedModule = IRLinker.getModule();
468 // Mark which symbols can not be internalized
469 this->applyScopeRestrictions();
471 // Instantiate the pass manager to organize the passes.
474 // Add an appropriate DataLayout instance for this module...
475 mergedModule->setDataLayout(TargetMach->getSubtargetImpl()->getDataLayout());
477 Triple TargetTriple(TargetMach->getTargetTriple());
478 PassManagerBuilder PMB;
479 PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
480 PMB.LoopVectorize = !DisableVectorization;
481 PMB.SLPVectorize = !DisableVectorization;
483 PMB.Inliner = createFunctionInliningPass();
484 PMB.LibraryInfo = new TargetLibraryInfo(TargetTriple);
487 PMB.VerifyInput = true;
488 PMB.VerifyOutput = true;
490 PMB.populateLTOPassManager(passes, TargetMach);
492 PassManager codeGenPasses;
494 codeGenPasses.add(new DataLayoutPass());
496 formatted_raw_ostream Out(out);
498 // If the bitcode files contain ARC code and were compiled with optimization,
499 // the ObjCARCContractPass must be run, so do it unconditionally here.
500 codeGenPasses.add(createObjCARCContractPass());
502 if (TargetMach->addPassesToEmitFile(codeGenPasses, Out,
503 TargetMachine::CGFT_ObjectFile)) {
504 errMsg = "target file type not supported";
508 // Run our queue of passes all at once now, efficiently.
509 passes.run(*mergedModule);
511 // Run the code generator, and write assembly file
512 codeGenPasses.run(*mergedModule);
517 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
519 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
520 for (std::pair<StringRef, StringRef> o = getToken(options);
521 !o.first.empty(); o = getToken(o.second)) {
522 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
524 if (CodegenOptions.empty())
525 CodegenOptions.push_back(strdup("libLLVMLTO"));
526 CodegenOptions.push_back(strdup(o.first.str().c_str()));
530 void LTOCodeGenerator::parseCodeGenDebugOptions() {
531 // if options were requested, set them
532 if (!CodegenOptions.empty())
533 cl::ParseCommandLineOptions(CodegenOptions.size(),
534 const_cast<char **>(&CodegenOptions[0]));
537 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
539 ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
542 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
543 // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
544 lto_codegen_diagnostic_severity_t Severity;
545 switch (DI.getSeverity()) {
547 Severity = LTO_DS_ERROR;
550 Severity = LTO_DS_WARNING;
553 Severity = LTO_DS_REMARK;
556 Severity = LTO_DS_NOTE;
559 // Create the string that will be reported to the external diagnostic handler.
560 std::string MsgStorage;
561 raw_string_ostream Stream(MsgStorage);
562 DiagnosticPrinterRawOStream DP(Stream);
566 // If this method has been called it means someone has set up an external
567 // diagnostic handler. Assert on that.
568 assert(DiagHandler && "Invalid diagnostic handler");
569 (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
573 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
575 this->DiagHandler = DiagHandler;
576 this->DiagContext = Ctxt;
578 return Context.setDiagnosticHandler(nullptr, nullptr);
579 // Register the LTOCodeGenerator stub in the LLVMContext to forward the
580 // diagnostic to the external DiagHandler.
581 Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
582 /* RespectFilters */ true);