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/Support/system_error.h"
48 #include "llvm/Target/TargetLibraryInfo.h"
49 #include "llvm/Target/TargetLowering.h"
50 #include "llvm/Target/TargetOptions.h"
51 #include "llvm/Target/TargetRegisterInfo.h"
52 #include "llvm/Transforms/IPO.h"
53 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
54 #include "llvm/Transforms/ObjCARC.h"
57 const char* LTOCodeGenerator::getVersionString() {
58 #ifdef LLVM_VERSION_INFO
59 return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
61 return PACKAGE_NAME " version " PACKAGE_VERSION;
65 LTOCodeGenerator::LTOCodeGenerator()
66 : Context(getGlobalContext()), IRLinker(new Module("ld-temp.o", Context)),
67 TargetMach(nullptr), EmitDwarfDebugInfo(false),
68 ScopeRestrictionsDone(false), CodeModel(LTO_CODEGEN_PIC_MODEL_DEFAULT),
69 NativeObjectFile(nullptr), DiagHandler(nullptr), DiagContext(nullptr) {
70 initializeLTOPasses();
73 LTOCodeGenerator::~LTOCodeGenerator() {
75 delete NativeObjectFile;
77 NativeObjectFile = nullptr;
79 IRLinker.deleteModule();
81 for (std::vector<char *>::iterator I = CodegenOptions.begin(),
82 E = CodegenOptions.end();
87 // Initialize LTO passes. Please keep this funciton in sync with
88 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
89 // passes are initialized.
90 void LTOCodeGenerator::initializeLTOPasses() {
91 PassRegistry &R = *PassRegistry::getPassRegistry();
93 initializeInternalizePassPass(R);
94 initializeIPSCCPPass(R);
95 initializeGlobalOptPass(R);
96 initializeConstantMergePass(R);
98 initializeInstCombinerPass(R);
99 initializeSimpleInlinerPass(R);
100 initializePruneEHPass(R);
101 initializeGlobalDCEPass(R);
102 initializeArgPromotionPass(R);
103 initializeJumpThreadingPass(R);
104 initializeSROAPass(R);
105 initializeSROA_DTPass(R);
106 initializeSROA_SSAUpPass(R);
107 initializeFunctionAttrsPass(R);
108 initializeGlobalsModRefPass(R);
109 initializeLICMPass(R);
110 initializeGVNPass(R);
111 initializeMemCpyOptPass(R);
112 initializeDCEPass(R);
113 initializeCFGSimplifyPassPass(R);
116 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
117 bool ret = IRLinker.linkInModule(mod->getLLVVMModule(), &errMsg);
119 const std::vector<const char*> &undefs = mod->getAsmUndefinedRefs();
120 for (int i = 0, e = undefs.size(); i != e; ++i)
121 AsmUndefinedRefs[undefs[i]] = 1;
126 void LTOCodeGenerator::setTargetOptions(TargetOptions options) {
127 Options.LessPreciseFPMADOption = options.LessPreciseFPMADOption;
128 Options.NoFramePointerElim = options.NoFramePointerElim;
129 Options.AllowFPOpFusion = options.AllowFPOpFusion;
130 Options.UnsafeFPMath = options.UnsafeFPMath;
131 Options.NoInfsFPMath = options.NoInfsFPMath;
132 Options.NoNaNsFPMath = options.NoNaNsFPMath;
133 Options.HonorSignDependentRoundingFPMathOption =
134 options.HonorSignDependentRoundingFPMathOption;
135 Options.UseSoftFloat = options.UseSoftFloat;
136 Options.FloatABIType = options.FloatABIType;
137 Options.NoZerosInBSS = options.NoZerosInBSS;
138 Options.GuaranteedTailCallOpt = options.GuaranteedTailCallOpt;
139 Options.DisableTailCalls = options.DisableTailCalls;
140 Options.StackAlignmentOverride = options.StackAlignmentOverride;
141 Options.TrapFuncName = options.TrapFuncName;
142 Options.PositionIndependentExecutable = options.PositionIndependentExecutable;
143 Options.UseInitArray = options.UseInitArray;
146 void LTOCodeGenerator::setDebugInfo(lto_debug_model debug) {
148 case LTO_DEBUG_MODEL_NONE:
149 EmitDwarfDebugInfo = false;
152 case LTO_DEBUG_MODEL_DWARF:
153 EmitDwarfDebugInfo = true;
156 llvm_unreachable("Unknown debug format!");
159 void LTOCodeGenerator::setCodePICModel(lto_codegen_model model) {
161 case LTO_CODEGEN_PIC_MODEL_STATIC:
162 case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
163 case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
164 case LTO_CODEGEN_PIC_MODEL_DEFAULT:
168 llvm_unreachable("Unknown PIC model!");
171 bool LTOCodeGenerator::writeMergedModules(const char *path,
172 std::string &errMsg) {
173 if (!determineTarget(errMsg))
176 // mark which symbols can not be internalized
177 applyScopeRestrictions();
179 // create output file
181 tool_output_file Out(path, ErrInfo, sys::fs::F_None);
182 if (!ErrInfo.empty()) {
183 errMsg = "could not open bitcode file for writing: ";
188 // write bitcode to it
189 WriteBitcodeToFile(IRLinker.getModule(), Out.os());
192 if (Out.os().has_error()) {
193 errMsg = "could not write bitcode file: ";
195 Out.os().clear_error();
203 bool LTOCodeGenerator::compile_to_file(const char** name,
206 bool disableGVNLoadPRE,
207 std::string& errMsg) {
208 // make unique temp .o file to put generated object file
209 SmallString<128> Filename;
211 error_code EC = 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);
220 bool genResult = generateObjectFile(objFile.os(), disableOpt, disableInline,
221 disableGVNLoadPRE, errMsg);
222 objFile.os().close();
223 if (objFile.os().has_error()) {
224 objFile.os().clear_error();
225 sys::fs::remove(Twine(Filename));
231 sys::fs::remove(Twine(Filename));
235 NativeObjectPath = Filename.c_str();
236 *name = NativeObjectPath.c_str();
240 const void* LTOCodeGenerator::compile(size_t* length,
243 bool disableGVNLoadPRE,
244 std::string& errMsg) {
246 if (!compile_to_file(&name, disableOpt, disableInline, disableGVNLoadPRE,
250 // remove old buffer if compile() called twice
251 delete NativeObjectFile;
253 // read .o file into memory buffer
254 std::unique_ptr<MemoryBuffer> BuffPtr;
255 if (error_code ec = MemoryBuffer::getFile(name, BuffPtr, -1, false)) {
256 errMsg = ec.message();
257 sys::fs::remove(NativeObjectPath);
260 NativeObjectFile = BuffPtr.release();
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::arm64 ||
316 Triple.getArch() == llvm::Triple::aarch64)
320 TargetMach = march->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
321 RelocModel, CodeModel::Default,
322 CodeGenOpt::Aggressive);
326 void LTOCodeGenerator::
327 applyRestriction(GlobalValue &GV,
328 const ArrayRef<StringRef> &Libcalls,
329 std::vector<const char*> &MustPreserveList,
330 SmallPtrSet<GlobalValue*, 8> &AsmUsed,
332 // There are no restrictions to apply to declarations.
333 if (GV.isDeclaration())
336 // There is nothing more restrictive than private linkage.
337 if (GV.hasPrivateLinkage())
340 SmallString<64> Buffer;
341 TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
343 if (MustPreserveSymbols.count(Buffer))
344 MustPreserveList.push_back(GV.getName().data());
345 if (AsmUndefinedRefs.count(Buffer))
348 // Conservatively append user-supplied runtime library functions to
349 // llvm.compiler.used. These could be internalized and deleted by
350 // optimizations like -globalopt, causing problems when later optimizations
351 // add new library calls (e.g., llvm.memset => memset and printf => puts).
352 // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
353 if (isa<Function>(GV) &&
354 std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
358 static void findUsedValues(GlobalVariable *LLVMUsed,
359 SmallPtrSet<GlobalValue*, 8> &UsedValues) {
360 if (!LLVMUsed) return;
362 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
363 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
364 if (GlobalValue *GV =
365 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
366 UsedValues.insert(GV);
369 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
370 const TargetLibraryInfo& TLI,
371 const TargetLowering *Lowering)
373 // TargetLibraryInfo has info on C runtime library calls on the current
375 for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
377 LibFunc::Func F = static_cast<LibFunc::Func>(I);
379 Libcalls.push_back(TLI.getName(F));
382 // TargetLowering has info on library calls that CodeGen expects to be
383 // available, both from the C runtime and compiler-rt.
385 for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
388 = Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
389 Libcalls.push_back(Name);
391 array_pod_sort(Libcalls.begin(), Libcalls.end());
392 Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
396 void LTOCodeGenerator::applyScopeRestrictions() {
397 if (ScopeRestrictionsDone)
399 Module *mergedModule = IRLinker.getModule();
401 // Start off with a verification pass.
403 passes.add(createVerifierPass());
404 passes.add(createDebugInfoVerifierPass());
406 // mark which symbols can not be internalized
407 Mangler Mangler(TargetMach->getDataLayout());
408 std::vector<const char*> MustPreserveList;
409 SmallPtrSet<GlobalValue*, 8> AsmUsed;
410 std::vector<StringRef> Libcalls;
411 TargetLibraryInfo TLI(Triple(TargetMach->getTargetTriple()));
412 accumulateAndSortLibcalls(Libcalls, TLI, TargetMach->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 std::string &errMsg) {
462 if (!this->determineTarget(errMsg))
465 Module *mergedModule = IRLinker.getModule();
467 // Mark which symbols can not be internalized
468 this->applyScopeRestrictions();
470 // Instantiate the pass manager to organize the passes.
473 // Start off with a verification pass.
474 passes.add(createVerifierPass());
475 passes.add(createDebugInfoVerifierPass());
477 // Add an appropriate DataLayout instance for this module...
478 mergedModule->setDataLayout(TargetMach->getDataLayout());
479 passes.add(new DataLayoutPass(mergedModule));
481 // Add appropriate TargetLibraryInfo for this module.
482 passes.add(new TargetLibraryInfo(Triple(TargetMach->getTargetTriple())));
484 TargetMach->addAnalysisPasses(passes);
486 // Enabling internalize here would use its AllButMain variant. It
487 // keeps only main if it exists and does nothing for libraries. Instead
488 // we create the pass ourselves with the symbol list provided by the linker.
490 PassManagerBuilder().populateLTOPassManager(passes,
491 /*Internalize=*/false,
495 // Make sure everything is still good.
496 passes.add(createVerifierPass());
497 passes.add(createDebugInfoVerifierPass());
499 PassManager codeGenPasses;
501 codeGenPasses.add(new DataLayoutPass(mergedModule));
503 formatted_raw_ostream Out(out);
505 // If the bitcode files contain ARC code and were compiled with optimization,
506 // the ObjCARCContractPass must be run, so do it unconditionally here.
507 codeGenPasses.add(createObjCARCContractPass());
509 if (TargetMach->addPassesToEmitFile(codeGenPasses, Out,
510 TargetMachine::CGFT_ObjectFile)) {
511 errMsg = "target file type not supported";
515 // Run our queue of passes all at once now, efficiently.
516 passes.run(*mergedModule);
518 // Run the code generator, and write assembly file
519 codeGenPasses.run(*mergedModule);
524 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
526 void LTOCodeGenerator::setCodeGenDebugOptions(const char *options) {
527 for (std::pair<StringRef, StringRef> o = getToken(options);
528 !o.first.empty(); o = getToken(o.second)) {
529 // ParseCommandLineOptions() expects argv[0] to be program name. Lazily add
531 if (CodegenOptions.empty())
532 CodegenOptions.push_back(strdup("libLLVMLTO"));
533 CodegenOptions.push_back(strdup(o.first.str().c_str()));
537 void LTOCodeGenerator::parseCodeGenDebugOptions() {
538 // if options were requested, set them
539 if (!CodegenOptions.empty())
540 cl::ParseCommandLineOptions(CodegenOptions.size(),
541 const_cast<char **>(&CodegenOptions[0]));
544 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
546 ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
549 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
550 // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
551 lto_codegen_diagnostic_severity_t Severity;
552 switch (DI.getSeverity()) {
554 Severity = LTO_DS_ERROR;
557 Severity = LTO_DS_WARNING;
560 Severity = LTO_DS_REMARK;
563 Severity = LTO_DS_NOTE;
566 // Create the string that will be reported to the external diagnostic handler.
567 std::string MsgStorage;
568 raw_string_ostream Stream(MsgStorage);
569 DiagnosticPrinterRawOStream DP(Stream);
573 // If this method has been called it means someone has set up an external
574 // diagnostic handler. Assert on that.
575 assert(DiagHandler && "Invalid diagnostic handler");
576 (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
580 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
582 this->DiagHandler = DiagHandler;
583 this->DiagContext = Ctxt;
585 return Context.setDiagnosticHandler(nullptr, nullptr);
586 // Register the LTOCodeGenerator stub in the LLVMContext to forward the
587 // diagnostic to the external DiagHandler.
588 Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this);