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/ParallelCG.h"
22 #include "llvm/CodeGen/RuntimeLibcalls.h"
23 #include "llvm/Config/config.h"
24 #include "llvm/IR/Constants.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/DiagnosticInfo.h"
28 #include "llvm/IR/DiagnosticPrinter.h"
29 #include "llvm/IR/LLVMContext.h"
30 #include "llvm/IR/LegacyPassManager.h"
31 #include "llvm/IR/Mangler.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/Verifier.h"
34 #include "llvm/InitializePasses.h"
35 #include "llvm/LTO/LTOModule.h"
36 #include "llvm/Linker/Linker.h"
37 #include "llvm/MC/MCAsmInfo.h"
38 #include "llvm/MC/MCContext.h"
39 #include "llvm/MC/SubtargetFeature.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/FileSystem.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(LLVMContext &Context)
68 : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
69 IRLinker(new Linker(*MergedModule, [this](const DiagnosticInfo &DI) {
70 MergedModule->getContext().diagnose(DI);
72 initializeLTOPasses();
75 LTOCodeGenerator::~LTOCodeGenerator() {}
77 // Initialize LTO passes. Please keep this function in sync with
78 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
79 // passes are initialized.
80 void LTOCodeGenerator::initializeLTOPasses() {
81 PassRegistry &R = *PassRegistry::getPassRegistry();
83 initializeInternalizePassPass(R);
84 initializeIPSCCPPass(R);
85 initializeGlobalOptPass(R);
86 initializeConstantMergePass(R);
88 initializeInstructionCombiningPassPass(R);
89 initializeSimpleInlinerPass(R);
90 initializePruneEHPass(R);
91 initializeGlobalDCEPass(R);
92 initializeArgPromotionPass(R);
93 initializeJumpThreadingPass(R);
94 initializeSROALegacyPassPass(R);
95 initializeSROA_DTPass(R);
96 initializeSROA_SSAUpPass(R);
97 initializeFunctionAttrsPass(R);
98 initializeGlobalsAAWrapperPassPass(R);
99 initializeLICMPass(R);
100 initializeMergedLoadStoreMotionPass(R);
101 initializeGVNPass(R);
102 initializeMemCpyOptPass(R);
103 initializeDCEPass(R);
104 initializeCFGSimplifyPassPass(R);
107 bool LTOCodeGenerator::addModule(LTOModule *Mod) {
108 assert(&Mod->getModule().getContext() == &Context &&
109 "Expected module in same context");
111 bool ret = IRLinker->linkInModule(Mod->getModule());
113 const std::vector<const char *> &undefs = Mod->getAsmUndefinedRefs();
114 for (int i = 0, e = undefs.size(); i != e; ++i)
115 AsmUndefinedRefs[undefs[i]] = 1;
120 void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
121 assert(&Mod->getModule().getContext() == &Context &&
122 "Expected module in same context");
124 AsmUndefinedRefs.clear();
126 MergedModule = Mod->takeModule();
127 IRLinker = llvm::make_unique<Linker>(*MergedModule,
128 IRLinker->getDiagnosticHandler());
130 const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
131 for (int I = 0, E = Undefs.size(); I != E; ++I)
132 AsmUndefinedRefs[Undefs[I]] = 1;
135 void LTOCodeGenerator::setTargetOptions(TargetOptions Options) {
136 this->Options = Options;
139 void LTOCodeGenerator::setDebugInfo(lto_debug_model Debug) {
141 case LTO_DEBUG_MODEL_NONE:
142 EmitDwarfDebugInfo = false;
145 case LTO_DEBUG_MODEL_DWARF:
146 EmitDwarfDebugInfo = true;
149 llvm_unreachable("Unknown debug format!");
152 void LTOCodeGenerator::setOptLevel(unsigned Level) {
156 CGOptLevel = CodeGenOpt::None;
159 CGOptLevel = CodeGenOpt::Less;
162 CGOptLevel = CodeGenOpt::Default;
165 CGOptLevel = CodeGenOpt::Aggressive;
170 bool LTOCodeGenerator::writeMergedModules(const char *Path) {
171 if (!determineTarget())
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 std::string ErrMsg = "could not open bitcode file for writing: ";
187 // write bitcode to it
188 WriteBitcodeToFile(MergedModule.get(), Out.os(), ShouldEmbedUselists);
191 if (Out.os().has_error()) {
192 std::string ErrMsg = "could not write bitcode file: ";
195 Out.os().clear_error();
203 bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
204 // make unique temp output file to put generated code
205 SmallString<128> Filename;
208 const char *Extension =
209 (FileType == TargetMachine::CGFT_AssemblyFile ? "s" : "o");
212 sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
214 emitError(EC.message());
218 // generate object file
219 tool_output_file objFile(Filename.c_str(), FD);
221 bool genResult = compileOptimized(&objFile.os());
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 std::unique_ptr<MemoryBuffer>
241 LTOCodeGenerator::compileOptimized() {
243 if (!compileOptimizedToFile(&name))
246 // read .o file into memory buffer
247 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
248 MemoryBuffer::getFile(name, -1, false);
249 if (std::error_code EC = BufferOrErr.getError()) {
250 emitError(EC.message());
251 sys::fs::remove(NativeObjectPath);
256 sys::fs::remove(NativeObjectPath);
258 return std::move(*BufferOrErr);
261 bool LTOCodeGenerator::compile_to_file(const char **Name, bool DisableVerify,
263 bool DisableGVNLoadPRE,
264 bool DisableVectorization) {
265 if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
266 DisableVectorization))
269 return compileOptimizedToFile(Name);
272 std::unique_ptr<MemoryBuffer>
273 LTOCodeGenerator::compile(bool DisableVerify, bool DisableInline,
274 bool DisableGVNLoadPRE, bool DisableVectorization) {
275 if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
276 DisableVectorization))
279 return compileOptimized();
282 bool LTOCodeGenerator::determineTarget() {
286 std::string TripleStr = MergedModule->getTargetTriple();
287 if (TripleStr.empty()) {
288 TripleStr = sys::getDefaultTargetTriple();
289 MergedModule->setTargetTriple(TripleStr);
291 llvm::Triple Triple(TripleStr);
293 // create target machine from info for merged modules
295 const Target *march = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
301 // Construct LTOModule, hand over ownership of module and target. Use MAttr as
302 // the default set of features.
303 SubtargetFeatures Features(MAttr);
304 Features.getDefaultSubtargetFeatures(Triple);
305 FeatureStr = Features.getString();
306 // Set a default CPU for Darwin triples.
307 if (MCpu.empty() && Triple.isOSDarwin()) {
308 if (Triple.getArch() == llvm::Triple::x86_64)
310 else if (Triple.getArch() == llvm::Triple::x86)
312 else if (Triple.getArch() == llvm::Triple::aarch64)
316 TargetMach.reset(march->createTargetMachine(TripleStr, MCpu, FeatureStr,
318 CodeModel::Default, CGOptLevel));
322 void LTOCodeGenerator::
323 applyRestriction(GlobalValue &GV,
324 ArrayRef<StringRef> Libcalls,
325 std::vector<const char*> &MustPreserveList,
326 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
328 // There are no restrictions to apply to declarations.
329 if (GV.isDeclaration())
332 // There is nothing more restrictive than private linkage.
333 if (GV.hasPrivateLinkage())
336 SmallString<64> Buffer;
337 TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
339 if (MustPreserveSymbols.count(Buffer))
340 MustPreserveList.push_back(GV.getName().data());
341 if (AsmUndefinedRefs.count(Buffer))
344 // Conservatively append user-supplied runtime library functions to
345 // llvm.compiler.used. These could be internalized and deleted by
346 // optimizations like -globalopt, causing problems when later optimizations
347 // add new library calls (e.g., llvm.memset => memset and printf => puts).
348 // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
349 if (isa<Function>(GV) &&
350 std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
354 static void findUsedValues(GlobalVariable *LLVMUsed,
355 SmallPtrSetImpl<GlobalValue*> &UsedValues) {
356 if (!LLVMUsed) return;
358 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
359 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
360 if (GlobalValue *GV =
361 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
362 UsedValues.insert(GV);
365 // Collect names of runtime library functions. User-defined functions with the
366 // same names are added to llvm.compiler.used to prevent them from being
367 // deleted by optimizations.
368 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
369 const TargetLibraryInfo& TLI,
371 const TargetMachine &TM) {
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 SmallPtrSet<const TargetLowering *, 1> TLSet;
383 for (const Function &F : Mod) {
384 const TargetLowering *Lowering =
385 TM.getSubtargetImpl(F)->getTargetLowering();
387 if (Lowering && TLSet.insert(Lowering).second)
388 // TargetLowering has info on library calls that CodeGen expects to be
389 // available, both from the C runtime and compiler-rt.
390 for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
392 if (const char *Name =
393 Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
394 Libcalls.push_back(Name);
397 array_pod_sort(Libcalls.begin(), Libcalls.end());
398 Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
402 void LTOCodeGenerator::applyScopeRestrictions() {
403 if (ScopeRestrictionsDone || !ShouldInternalize)
406 // Start off with a verification pass.
407 legacy::PassManager passes;
408 passes.add(createVerifierPass());
410 // mark which symbols can not be internalized
412 std::vector<const char*> MustPreserveList;
413 SmallPtrSet<GlobalValue*, 8> AsmUsed;
414 std::vector<StringRef> Libcalls;
415 TargetLibraryInfoImpl TLII(Triple(TargetMach->getTargetTriple()));
416 TargetLibraryInfo TLI(TLII);
418 accumulateAndSortLibcalls(Libcalls, TLI, *MergedModule, *TargetMach);
420 for (Function &f : *MergedModule)
421 applyRestriction(f, Libcalls, MustPreserveList, AsmUsed, Mangler);
422 for (GlobalVariable &v : MergedModule->globals())
423 applyRestriction(v, Libcalls, MustPreserveList, AsmUsed, Mangler);
424 for (GlobalAlias &a : MergedModule->aliases())
425 applyRestriction(a, Libcalls, MustPreserveList, AsmUsed, Mangler);
427 GlobalVariable *LLVMCompilerUsed =
428 MergedModule->getGlobalVariable("llvm.compiler.used");
429 findUsedValues(LLVMCompilerUsed, AsmUsed);
430 if (LLVMCompilerUsed)
431 LLVMCompilerUsed->eraseFromParent();
433 if (!AsmUsed.empty()) {
434 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
435 std::vector<Constant*> asmUsed2;
436 for (auto *GV : AsmUsed) {
437 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
438 asmUsed2.push_back(c);
441 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
443 new llvm::GlobalVariable(*MergedModule, ATy, false,
444 llvm::GlobalValue::AppendingLinkage,
445 llvm::ConstantArray::get(ATy, asmUsed2),
446 "llvm.compiler.used");
448 LLVMCompilerUsed->setSection("llvm.metadata");
451 passes.add(createInternalizePass(MustPreserveList));
453 // apply scope restrictions
454 passes.run(*MergedModule);
456 ScopeRestrictionsDone = true;
459 /// Optimize merged modules using various IPO passes
460 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
461 bool DisableGVNLoadPRE,
462 bool DisableVectorization) {
463 if (!this->determineTarget())
466 // Mark which symbols can not be internalized
467 this->applyScopeRestrictions();
469 // Instantiate the pass manager to organize the passes.
470 legacy::PassManager passes;
472 // Add an appropriate DataLayout instance for this module...
473 MergedModule->setDataLayout(TargetMach->createDataLayout());
476 createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
478 Triple TargetTriple(TargetMach->getTargetTriple());
479 PassManagerBuilder PMB;
480 PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
481 PMB.LoopVectorize = !DisableVectorization;
482 PMB.SLPVectorize = !DisableVectorization;
484 PMB.Inliner = createFunctionInliningPass();
485 PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
486 PMB.OptLevel = OptLevel;
487 PMB.VerifyInput = !DisableVerify;
488 PMB.VerifyOutput = !DisableVerify;
490 PMB.populateLTOPassManager(passes);
492 // Run our queue of passes all at once now, efficiently.
493 passes.run(*MergedModule);
498 bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
499 if (!this->determineTarget())
502 legacy::PassManager preCodeGenPasses;
504 // If the bitcode files contain ARC code and were compiled with optimization,
505 // the ObjCARCContractPass must be run, so do it unconditionally here.
506 preCodeGenPasses.add(createObjCARCContractPass());
507 preCodeGenPasses.run(*MergedModule);
509 // Do code generation. We need to preserve the module in case the client calls
510 // writeMergedModules() after compilation, but we only need to allow this at
511 // parallelism level 1. This is achieved by having splitCodeGen return the
512 // original module at parallelism level 1 which we then assign back to
515 splitCodeGen(std::move(MergedModule), Out, MCpu, FeatureStr, Options,
516 RelocModel, CodeModel::Default, CGOptLevel, FileType);
521 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
523 void LTOCodeGenerator::setCodeGenDebugOptions(const char *Options) {
524 for (std::pair<StringRef, StringRef> o = getToken(Options); !o.first.empty();
525 o = getToken(o.second))
526 CodegenOptions.push_back(o.first);
529 void LTOCodeGenerator::parseCodeGenDebugOptions() {
530 // if options were requested, set them
531 if (!CodegenOptions.empty()) {
532 // ParseCommandLineOptions() expects argv[0] to be program name.
533 std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
534 for (std::string &Arg : CodegenOptions)
535 CodegenArgv.push_back(Arg.c_str());
536 cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
540 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
542 ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
545 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
546 // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
547 lto_codegen_diagnostic_severity_t Severity;
548 switch (DI.getSeverity()) {
550 Severity = LTO_DS_ERROR;
553 Severity = LTO_DS_WARNING;
556 Severity = LTO_DS_REMARK;
559 Severity = LTO_DS_NOTE;
562 // Create the string that will be reported to the external diagnostic handler.
563 std::string MsgStorage;
564 raw_string_ostream Stream(MsgStorage);
565 DiagnosticPrinterRawOStream DP(Stream);
569 // If this method has been called it means someone has set up an external
570 // diagnostic handler. Assert on that.
571 assert(DiagHandler && "Invalid diagnostic handler");
572 (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
576 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
578 this->DiagHandler = DiagHandler;
579 this->DiagContext = Ctxt;
581 return Context.setDiagnosticHandler(nullptr, nullptr);
582 // Register the LTOCodeGenerator stub in the LLVMContext to forward the
583 // diagnostic to the external DiagHandler.
584 Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
585 /* RespectFilters */ true);
589 class LTODiagnosticInfo : public DiagnosticInfo {
592 LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
593 : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
594 void print(DiagnosticPrinter &DP) const override { DP << Msg; }
598 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
600 (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
602 Context.diagnose(LTODiagnosticInfo(ErrMsg));