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/Analysis/TargetLibraryInfo.h"
19 #include "llvm/Analysis/TargetTransformInfo.h"
20 #include "llvm/Bitcode/ReaderWriter.h"
21 #include "llvm/CodeGen/RuntimeLibcalls.h"
22 #include "llvm/Config/config.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/DiagnosticInfo.h"
27 #include "llvm/IR/DiagnosticPrinter.h"
28 #include "llvm/IR/LLVMContext.h"
29 #include "llvm/IR/LegacyPassManager.h"
30 #include "llvm/IR/Mangler.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/IR/Verifier.h"
33 #include "llvm/InitializePasses.h"
34 #include "llvm/LTO/LTOModule.h"
35 #include "llvm/Linker/Linker.h"
36 #include "llvm/MC/MCAsmInfo.h"
37 #include "llvm/MC/MCContext.h"
38 #include "llvm/MC/SubtargetFeature.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/FileSystem.h"
41 #include "llvm/Support/FormattedStream.h"
42 #include "llvm/Support/Host.h"
43 #include "llvm/Support/MemoryBuffer.h"
44 #include "llvm/Support/Signals.h"
45 #include "llvm/Support/TargetRegistry.h"
46 #include "llvm/Support/TargetSelect.h"
47 #include "llvm/Support/ToolOutputFile.h"
48 #include "llvm/Support/raw_ostream.h"
49 #include "llvm/Target/TargetLowering.h"
50 #include "llvm/Target/TargetOptions.h"
51 #include "llvm/Target/TargetRegisterInfo.h"
52 #include "llvm/Target/TargetSubtargetInfo.h"
53 #include "llvm/Transforms/IPO.h"
54 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
55 #include "llvm/Transforms/ObjCARC.h"
56 #include <system_error>
59 const char* LTOCodeGenerator::getVersionString() {
60 #ifdef LLVM_VERSION_INFO
61 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
63 return PACKAGE_NAME " version " PACKAGE_VERSION;
67 LTOCodeGenerator::LTOCodeGenerator()
68 : Context(getGlobalContext()), IRLinker(new Module("ld-temp.o", Context)) {
72 LTOCodeGenerator::LTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
73 : OwnedContext(std::move(Context)), Context(*OwnedContext),
74 IRLinker(new Module("ld-temp.o", *OwnedContext)), OptLevel(2) {
78 void LTOCodeGenerator::initialize() {
80 EmitDwarfDebugInfo = false;
81 ScopeRestrictionsDone = false;
82 CodeModel = LTO_CODEGEN_PIC_MODEL_DEFAULT;
83 DiagHandler = nullptr;
84 DiagContext = nullptr;
85 OwnedModule = nullptr;
87 initializeLTOPasses();
90 void LTOCodeGenerator::destroyMergedModule() {
92 assert(IRLinker.getModule() == &OwnedModule->getModule() &&
93 "The linker's module should be the same as the owned module");
95 OwnedModule = nullptr;
96 } else if (IRLinker.getModule())
97 IRLinker.deleteModule();
100 LTOCodeGenerator::~LTOCodeGenerator() {
101 destroyMergedModule();
104 TargetMach = nullptr;
106 for (std::vector<char *>::iterator I = CodegenOptions.begin(),
107 E = CodegenOptions.end();
112 // Initialize LTO passes. Please keep this funciton in sync with
113 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
114 // passes are initialized.
115 void LTOCodeGenerator::initializeLTOPasses() {
116 PassRegistry &R = *PassRegistry::getPassRegistry();
118 initializeInternalizePassPass(R);
119 initializeIPSCCPPass(R);
120 initializeGlobalOptPass(R);
121 initializeConstantMergePass(R);
122 initializeDAHPass(R);
123 initializeInstructionCombiningPassPass(R);
124 initializeSimpleInlinerPass(R);
125 initializePruneEHPass(R);
126 initializeGlobalDCEPass(R);
127 initializeArgPromotionPass(R);
128 initializeJumpThreadingPass(R);
129 initializeSROAPass(R);
130 initializeSROA_DTPass(R);
131 initializeSROA_SSAUpPass(R);
132 initializeFunctionAttrsPass(R);
133 initializeGlobalsModRefPass(R);
134 initializeLICMPass(R);
135 initializeMergedLoadStoreMotionPass(R);
136 initializeGVNPass(R);
137 initializeMemCpyOptPass(R);
138 initializeDCEPass(R);
139 initializeCFGSimplifyPassPass(R);
142 bool LTOCodeGenerator::addModule(LTOModule *mod) {
143 assert(&mod->getModule().getContext() == &Context &&
144 "Expected module in same context");
146 bool ret = IRLinker.linkInModule(&mod->getModule());
148 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
149 for (int i = 0, e = undefs.size(); i != e; ++i)
150 AsmUndefinedRefs[undefs[i]] = 1;
155 void LTOCodeGenerator::setModule(LTOModule *Mod) {
156 assert(&Mod->getModule().getContext() == &Context &&
157 "Expected module in same context");
159 // Delete the old merged module.
160 destroyMergedModule();
161 AsmUndefinedRefs.clear();
164 IRLinker.setModule(&Mod->getModule());
166 const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
167 for (int I = 0, E = Undefs.size(); I != E; ++I)
168 AsmUndefinedRefs[Undefs[I]] = 1;
171 void LTOCodeGenerator::setTargetOptions(TargetOptions options) {
175 void LTOCodeGenerator::setDebugInfo(lto_debug_model debug) {
177 case LTO_DEBUG_MODEL_NONE:
178 EmitDwarfDebugInfo = false;
181 case LTO_DEBUG_MODEL_DWARF:
182 EmitDwarfDebugInfo = true;
185 llvm_unreachable("Unknown debug format!");
188 void LTOCodeGenerator::setCodePICModel(lto_codegen_model model) {
190 case LTO_CODEGEN_PIC_MODEL_STATIC:
191 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
192 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
193 case LTO_CODEGEN_PIC_MODEL_DEFAULT:
197 llvm_unreachable("Unknown PIC model!");
200 bool LTOCodeGenerator::writeMergedModules(const char *path,
201 std::string &errMsg) {
202 if (!determineTarget(errMsg))
205 // mark which symbols can not be internalized
206 applyScopeRestrictions();
208 // create output file
210 tool_output_file Out(path, EC, sys::fs::F_None);
212 errMsg = "could not open bitcode file for writing: ";
217 // write bitcode to it
218 WriteBitcodeToFile(IRLinker.getModule(), Out.os());
221 if (Out.os().has_error()) {
222 errMsg = "could not write bitcode file: ";
224 Out.os().clear_error();
232 bool LTOCodeGenerator::compileOptimizedToFile(const char **name,
233 std::string &errMsg) {
234 // make unique temp .o file to put generated object file
235 SmallString<128> Filename;
238 sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
240 errMsg = EC.message();
244 // generate object file
245 tool_output_file objFile(Filename.c_str(), FD);
247 bool genResult = compileOptimized(objFile.os(), errMsg);
248 objFile.os().close();
249 if (objFile.os().has_error()) {
250 objFile.os().clear_error();
251 sys::fs::remove(Twine(Filename));
257 sys::fs::remove(Twine(Filename));
261 NativeObjectPath = Filename.c_str();
262 *name = NativeObjectPath.c_str();
266 const void *LTOCodeGenerator::compileOptimized(size_t *length,
267 std::string &errMsg) {
269 if (!compileOptimizedToFile(&name, errMsg))
272 // read .o file into memory buffer
273 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
274 MemoryBuffer::getFile(name, -1, false);
275 if (std::error_code EC = BufferOrErr.getError()) {
276 errMsg = EC.message();
277 sys::fs::remove(NativeObjectPath);
280 NativeObjectFile = std::move(*BufferOrErr);
283 sys::fs::remove(NativeObjectPath);
285 // return buffer, unless error
286 if (!NativeObjectFile)
288 *length = NativeObjectFile->getBufferSize();
289 return NativeObjectFile->getBufferStart();
293 bool LTOCodeGenerator::compile_to_file(const char **name,
295 bool disableGVNLoadPRE,
296 bool disableVectorization,
297 std::string &errMsg) {
298 if (!optimize(disableInline, disableGVNLoadPRE,
299 disableVectorization, errMsg))
302 return compileOptimizedToFile(name, errMsg);
305 const void* LTOCodeGenerator::compile(size_t *length,
307 bool disableGVNLoadPRE,
308 bool disableVectorization,
309 std::string &errMsg) {
310 if (!optimize(disableInline, disableGVNLoadPRE,
311 disableVectorization, errMsg))
314 return compileOptimized(length, errMsg);
317 bool LTOCodeGenerator::determineTarget(std::string &errMsg) {
321 std::string TripleStr = IRLinker.getModule()->getTargetTriple();
322 if (TripleStr.empty())
323 TripleStr = sys::getDefaultTargetTriple();
324 llvm::Triple Triple(TripleStr);
326 // create target machine from info for merged modules
327 const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
331 // The relocation model is actually a static member of TargetMachine and
332 // needs to be set before the TargetMachine is instantiated.
333 Reloc::Model RelocModel = Reloc::Default;
335 case LTO_CODEGEN_PIC_MODEL_STATIC:
336 RelocModel = Reloc::Static;
338 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
339 RelocModel = Reloc::PIC_;
341 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
342 RelocModel = Reloc::DynamicNoPIC;
344 case LTO_CODEGEN_PIC_MODEL_DEFAULT:
345 // RelocModel is already the default, so leave it that way.
349 // Construct LTOModule, hand over ownership of module and target. Use MAttr as
350 // the default set of features.
351 SubtargetFeatures Features(MAttr);
352 Features.getDefaultSubtargetFeatures(Triple);
353 std::string FeatureStr = Features.getString();
354 // Set a default CPU for Darwin triples.
355 if (MCpu.empty() && Triple.isOSDarwin()) {
356 if (Triple.getArch() == llvm::Triple::x86_64)
358 else if (Triple.getArch() == llvm::Triple::x86)
360 else if (Triple.getArch() == llvm::Triple::aarch64)
364 CodeGenOpt::Level CGOptLevel;
367 CGOptLevel = CodeGenOpt::None;
370 CGOptLevel = CodeGenOpt::Less;
373 CGOptLevel = CodeGenOpt::Default;
376 CGOptLevel = CodeGenOpt::Aggressive;
380 TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
381 RelocModel, CodeModel::Default,
386 void LTOCodeGenerator::
387 applyRestriction(GlobalValue &GV,
388 ArrayRef<StringRef> Libcalls,
389 std::vector<const char*> &MustPreserveList,
390 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
392 // There are no restrictions to apply to declarations.
393 if (GV.isDeclaration())
396 // There is nothing more restrictive than private linkage.
397 if (GV.hasPrivateLinkage())
400 SmallString<64> Buffer;
401 TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
403 if (MustPreserveSymbols.count(Buffer))
404 MustPreserveList.push_back(GV.getName().data());
405 if (AsmUndefinedRefs.count(Buffer))
408 // Conservatively append user-supplied runtime library functions to
409 // llvm.compiler.used. These could be internalized and deleted by
410 // optimizations like -globalopt, causing problems when later optimizations
411 // add new library calls (e.g., llvm.memset => memset and printf => puts).
412 // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
413 if (isa<Function>(GV) &&
414 std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
418 static void findUsedValues(GlobalVariable *LLVMUsed,
419 SmallPtrSetImpl<GlobalValue*> &UsedValues) {
420 if (!LLVMUsed) return;
422 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
423 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
424 if (GlobalValue *GV =
425 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
426 UsedValues.insert(GV);
429 // Collect names of runtime library functions. User-defined functions with the
430 // same names are added to llvm.compiler.used to prevent them from being
431 // deleted by optimizations.
432 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
433 const TargetLibraryInfo& TLI,
435 const TargetMachine &TM) {
436 // TargetLibraryInfo has info on C runtime library calls on the current
438 for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
440 LibFunc::Func F = static_cast<LibFunc::Func>(I);
442 Libcalls.push_back(TLI.getName(F));
445 SmallPtrSet<const TargetLowering *, 1> TLSet;
447 for (const Function &F : Mod) {
448 const TargetLowering *Lowering =
449 TM.getSubtargetImpl(F)->getTargetLowering();
451 if (Lowering && TLSet.insert(Lowering).second)
452 // TargetLowering has info on library calls that CodeGen expects to be
453 // available, both from the C runtime and compiler-rt.
454 for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
456 if (const char *Name =
457 Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
458 Libcalls.push_back(Name);
461 array_pod_sort(Libcalls.begin(), Libcalls.end());
462 Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
466 void LTOCodeGenerator::applyScopeRestrictions() {
467 if (ScopeRestrictionsDone)
469 Module *mergedModule = IRLinker.getModule();
471 // Start off with a verification pass.
472 legacy::PassManager passes;
473 passes.add(createVerifierPass());
475 // mark which symbols can not be internalized
476 Mangler Mangler(TargetMach->getDataLayout());
477 std::vector<const char*> MustPreserveList;
478 SmallPtrSet<GlobalValue*, 8> AsmUsed;
479 std::vector<StringRef> Libcalls;
480 TargetLibraryInfoImpl TLII(Triple(TargetMach->getTargetTriple()));
481 TargetLibraryInfo TLI(TLII);
483 accumulateAndSortLibcalls(Libcalls, TLI, *mergedModule, *TargetMach);
485 for (Module::iterator f = mergedModule->begin(),
486 e = mergedModule->end(); f != e; ++f)
487 applyRestriction(*f, Libcalls, MustPreserveList, AsmUsed, Mangler);
488 for (Module::global_iterator v = mergedModule->global_begin(),
489 e = mergedModule->global_end(); v != e; ++v)
490 applyRestriction(*v, Libcalls, MustPreserveList, AsmUsed, Mangler);
491 for (Module::alias_iterator a = mergedModule->alias_begin(),
492 e = mergedModule->alias_end(); a != e; ++a)
493 applyRestriction(*a, Libcalls, MustPreserveList, AsmUsed, Mangler);
495 GlobalVariable *LLVMCompilerUsed =
496 mergedModule->getGlobalVariable("llvm.compiler.used");
497 findUsedValues(LLVMCompilerUsed, AsmUsed);
498 if (LLVMCompilerUsed)
499 LLVMCompilerUsed->eraseFromParent();
501 if (!AsmUsed.empty()) {
502 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
503 std::vector<Constant*> asmUsed2;
504 for (auto *GV : AsmUsed) {
505 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
506 asmUsed2.push_back(c);
509 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
511 new llvm::GlobalVariable(*mergedModule, ATy, false,
512 llvm::GlobalValue::AppendingLinkage,
513 llvm::ConstantArray::get(ATy, asmUsed2),
514 "llvm.compiler.used");
516 LLVMCompilerUsed->setSection("llvm.metadata");
519 passes.add(createInternalizePass(MustPreserveList));
521 // apply scope restrictions
522 passes.run(*mergedModule);
524 ScopeRestrictionsDone = true;
527 /// Optimize merged modules using various IPO passes
528 bool LTOCodeGenerator::optimize(bool DisableInline,
529 bool DisableGVNLoadPRE,
530 bool DisableVectorization,
531 std::string &errMsg) {
532 if (!this->determineTarget(errMsg))
535 Module *mergedModule = IRLinker.getModule();
537 // Mark which symbols can not be internalized
538 this->applyScopeRestrictions();
540 // Instantiate the pass manager to organize the passes.
541 legacy::PassManager passes;
543 // Add an appropriate DataLayout instance for this module...
544 mergedModule->setDataLayout(*TargetMach->getDataLayout());
547 createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
549 Triple TargetTriple(TargetMach->getTargetTriple());
550 PassManagerBuilder PMB;
551 PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
552 PMB.LoopVectorize = !DisableVectorization;
553 PMB.SLPVectorize = !DisableVectorization;
555 PMB.Inliner = createFunctionInliningPass();
556 PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
557 PMB.OptLevel = OptLevel;
558 PMB.VerifyInput = true;
559 PMB.VerifyOutput = true;
561 PMB.populateLTOPassManager(passes);
563 // Run our queue of passes all at once now, efficiently.
564 passes.run(*mergedModule);
569 bool LTOCodeGenerator::compileOptimized(raw_ostream &out, std::string &errMsg) {
570 if (!this->determineTarget(errMsg))
573 Module *mergedModule = IRLinker.getModule();
575 // Mark which symbols can not be internalized
576 this->applyScopeRestrictions();
578 legacy::PassManager codeGenPasses;
580 formatted_raw_ostream Out(out);
582 // If the bitcode files contain ARC code and were compiled with optimization,
583 // the ObjCARCContractPass must be run, so do it unconditionally here.
584 codeGenPasses.add(createObjCARCContractPass());
586 if (TargetMach->addPassesToEmitFile(codeGenPasses, Out,
587 TargetMachine::CGFT_ObjectFile)) {
588 errMsg = "target file type not supported";
592 // Run the code generator, and write assembly file
593 codeGenPasses.run(*mergedModule);
598 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
600 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
601 for (std::pair<StringRef, StringRef> o = getToken(options);
602 !o.first.empty(); o = getToken(o.second)) {
603 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
605 if (CodegenOptions.empty())
606 CodegenOptions.push_back(strdup("libLLVMLTO"));
607 CodegenOptions.push_back(strdup(o.first.str().c_str()));
611 void LTOCodeGenerator::parseCodeGenDebugOptions() {
612 // if options were requested, set them
613 if (!CodegenOptions.empty())
614 cl::ParseCommandLineOptions(CodegenOptions.size(),
615 const_cast<char **>(&CodegenOptions[0]));
618 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
620 ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
623 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
624 // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
625 lto_codegen_diagnostic_severity_t Severity;
626 switch (DI.getSeverity()) {
628 Severity = LTO_DS_ERROR;
631 Severity = LTO_DS_WARNING;
634 Severity = LTO_DS_REMARK;
637 Severity = LTO_DS_NOTE;
640 // Create the string that will be reported to the external diagnostic handler.
641 std::string MsgStorage;
642 raw_string_ostream Stream(MsgStorage);
643 DiagnosticPrinterRawOStream DP(Stream);
647 // If this method has been called it means someone has set up an external
648 // diagnostic handler. Assert on that.
649 assert(DiagHandler && "Invalid diagnostic handler");
650 (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
654 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
656 this->DiagHandler = DiagHandler;
657 this->DiagContext = Ctxt;
659 return Context.setDiagnosticHandler(nullptr, nullptr);
660 // Register the LTOCodeGenerator stub in the LLVMContext to forward the
661 // diagnostic to the external DiagHandler.
662 Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
663 /* RespectFilters */ true);