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()
68 : Context(getGlobalContext()),
69 MergedModule(new Module("ld-temp.o", Context)),
70 IRLinker(MergedModule.get()) {
71 initializeLTOPasses();
74 LTOCodeGenerator::LTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
75 : OwnedContext(std::move(Context)), Context(*OwnedContext),
76 MergedModule(new Module("ld-temp.o", *OwnedContext)),
77 IRLinker(MergedModule.get()) {
78 initializeLTOPasses();
81 LTOCodeGenerator::~LTOCodeGenerator() {}
83 // Initialize LTO passes. Please keep this function in sync with
84 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
85 // passes are initialized.
86 void LTOCodeGenerator::initializeLTOPasses() {
87 PassRegistry &R = *PassRegistry::getPassRegistry();
89 initializeInternalizePassPass(R);
90 initializeIPSCCPPass(R);
91 initializeGlobalOptPass(R);
92 initializeConstantMergePass(R);
94 initializeInstructionCombiningPassPass(R);
95 initializeSimpleInlinerPass(R);
96 initializePruneEHPass(R);
97 initializeGlobalDCEPass(R);
98 initializeArgPromotionPass(R);
99 initializeJumpThreadingPass(R);
100 initializeSROALegacyPassPass(R);
101 initializeSROA_DTPass(R);
102 initializeSROA_SSAUpPass(R);
103 initializeFunctionAttrsPass(R);
104 initializeGlobalsAAWrapperPassPass(R);
105 initializeLICMPass(R);
106 initializeMergedLoadStoreMotionPass(R);
107 initializeGVNPass(R);
108 initializeMemCpyOptPass(R);
109 initializeDCEPass(R);
110 initializeCFGSimplifyPassPass(R);
113 bool LTOCodeGenerator::addModule(LTOModule *Mod) {
114 assert(&Mod->getModule().getContext() == &Context &&
115 "Expected module in same context");
117 bool ret = IRLinker.linkInModule(&Mod->getModule());
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::setModule(std::unique_ptr<LTOModule> Mod) {
127 assert(&Mod->getModule().getContext() == &Context &&
128 "Expected module in same context");
130 AsmUndefinedRefs.clear();
132 MergedModule = Mod->takeModule();
133 IRLinker.setModule(MergedModule.get());
135 const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
136 for (int I = 0, E = Undefs.size(); I != E; ++I)
137 AsmUndefinedRefs[Undefs[I]] = 1;
140 void LTOCodeGenerator::setTargetOptions(TargetOptions Options) {
141 this->Options = 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::setOptLevel(unsigned Level) {
161 CGOptLevel = CodeGenOpt::None;
164 CGOptLevel = CodeGenOpt::Less;
167 CGOptLevel = CodeGenOpt::Default;
170 CGOptLevel = CodeGenOpt::Aggressive;
175 bool LTOCodeGenerator::writeMergedModules(const char *Path) {
176 if (!determineTarget())
179 // mark which symbols can not be internalized
180 applyScopeRestrictions();
182 // create output file
184 tool_output_file Out(Path, EC, sys::fs::F_None);
186 std::string ErrMsg = "could not open bitcode file for writing: ";
192 // write bitcode to it
193 WriteBitcodeToFile(MergedModule.get(), Out.os(), ShouldEmbedUselists);
196 if (Out.os().has_error()) {
197 std::string ErrMsg = "could not write bitcode file: ";
200 Out.os().clear_error();
208 bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
209 // make unique temp output file to put generated code
210 SmallString<128> Filename;
213 const char *Extension =
214 (FileType == TargetMachine::CGFT_AssemblyFile ? "s" : "o");
217 sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
219 emitError(EC.message());
223 // generate object file
224 tool_output_file objFile(Filename.c_str(), FD);
226 bool genResult = compileOptimized(&objFile.os());
227 objFile.os().close();
228 if (objFile.os().has_error()) {
229 objFile.os().clear_error();
230 sys::fs::remove(Twine(Filename));
236 sys::fs::remove(Twine(Filename));
240 NativeObjectPath = Filename.c_str();
241 *Name = NativeObjectPath.c_str();
245 std::unique_ptr<MemoryBuffer>
246 LTOCodeGenerator::compileOptimized() {
248 if (!compileOptimizedToFile(&name))
251 // read .o file into memory buffer
252 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
253 MemoryBuffer::getFile(name, -1, false);
254 if (std::error_code EC = BufferOrErr.getError()) {
255 emitError(EC.message());
256 sys::fs::remove(NativeObjectPath);
261 sys::fs::remove(NativeObjectPath);
263 return std::move(*BufferOrErr);
266 bool LTOCodeGenerator::compile_to_file(const char **Name, bool DisableVerify,
268 bool DisableGVNLoadPRE,
269 bool DisableVectorization) {
270 if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
271 DisableVectorization))
274 return compileOptimizedToFile(Name);
277 std::unique_ptr<MemoryBuffer>
278 LTOCodeGenerator::compile(bool DisableVerify, bool DisableInline,
279 bool DisableGVNLoadPRE, bool DisableVectorization) {
280 if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
281 DisableVectorization))
284 return compileOptimized();
287 bool LTOCodeGenerator::determineTarget() {
291 std::string TripleStr = MergedModule->getTargetTriple();
292 if (TripleStr.empty()) {
293 TripleStr = sys::getDefaultTargetTriple();
294 MergedModule->setTargetTriple(TripleStr);
296 llvm::Triple Triple(TripleStr);
298 // create target machine from info for merged modules
300 const Target *march = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
306 // Construct LTOModule, hand over ownership of module and target. Use MAttr as
307 // the default set of features.
308 SubtargetFeatures Features(MAttr);
309 Features.getDefaultSubtargetFeatures(Triple);
310 FeatureStr = Features.getString();
311 // Set a default CPU for Darwin triples.
312 if (MCpu.empty() && Triple.isOSDarwin()) {
313 if (Triple.getArch() == llvm::Triple::x86_64)
315 else if (Triple.getArch() == llvm::Triple::x86)
317 else if (Triple.getArch() == llvm::Triple::aarch64)
321 TargetMach.reset(march->createTargetMachine(TripleStr, MCpu, FeatureStr,
323 CodeModel::Default, CGOptLevel));
327 void LTOCodeGenerator::
328 applyRestriction(GlobalValue &GV,
329 ArrayRef<StringRef> Libcalls,
330 std::vector<const char*> &MustPreserveList,
331 SmallPtrSetImpl<GlobalValue*> &AsmUsed,
333 // There are no restrictions to apply to declarations.
334 if (GV.isDeclaration())
337 // There is nothing more restrictive than private linkage.
338 if (GV.hasPrivateLinkage())
341 SmallString<64> Buffer;
342 TargetMach->getNameWithPrefix(Buffer, &GV, Mangler);
344 if (MustPreserveSymbols.count(Buffer))
345 MustPreserveList.push_back(GV.getName().data());
346 if (AsmUndefinedRefs.count(Buffer))
349 // Conservatively append user-supplied runtime library functions to
350 // llvm.compiler.used. These could be internalized and deleted by
351 // optimizations like -globalopt, causing problems when later optimizations
352 // add new library calls (e.g., llvm.memset => memset and printf => puts).
353 // Leave it to the linker to remove any dead code (e.g. with -dead_strip).
354 if (isa<Function>(GV) &&
355 std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
359 static void findUsedValues(GlobalVariable *LLVMUsed,
360 SmallPtrSetImpl<GlobalValue*> &UsedValues) {
361 if (!LLVMUsed) return;
363 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
364 for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
365 if (GlobalValue *GV =
366 dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
367 UsedValues.insert(GV);
370 // Collect names of runtime library functions. User-defined functions with the
371 // same names are added to llvm.compiler.used to prevent them from being
372 // deleted by optimizations.
373 static void accumulateAndSortLibcalls(std::vector<StringRef> &Libcalls,
374 const TargetLibraryInfo& TLI,
376 const TargetMachine &TM) {
377 // TargetLibraryInfo has info on C runtime library calls on the current
379 for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
381 LibFunc::Func F = static_cast<LibFunc::Func>(I);
383 Libcalls.push_back(TLI.getName(F));
386 SmallPtrSet<const TargetLowering *, 1> TLSet;
388 for (const Function &F : Mod) {
389 const TargetLowering *Lowering =
390 TM.getSubtargetImpl(F)->getTargetLowering();
392 if (Lowering && TLSet.insert(Lowering).second)
393 // TargetLowering has info on library calls that CodeGen expects to be
394 // available, both from the C runtime and compiler-rt.
395 for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
397 if (const char *Name =
398 Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
399 Libcalls.push_back(Name);
402 array_pod_sort(Libcalls.begin(), Libcalls.end());
403 Libcalls.erase(std::unique(Libcalls.begin(), Libcalls.end()),
407 void LTOCodeGenerator::applyScopeRestrictions() {
408 if (ScopeRestrictionsDone || !ShouldInternalize)
411 // Start off with a verification pass.
412 legacy::PassManager passes;
413 passes.add(createVerifierPass());
415 // mark which symbols can not be internalized
417 std::vector<const char*> MustPreserveList;
418 SmallPtrSet<GlobalValue*, 8> AsmUsed;
419 std::vector<StringRef> Libcalls;
420 TargetLibraryInfoImpl TLII(Triple(TargetMach->getTargetTriple()));
421 TargetLibraryInfo TLI(TLII);
423 accumulateAndSortLibcalls(Libcalls, TLI, *MergedModule, *TargetMach);
425 for (Function &f : *MergedModule)
426 applyRestriction(f, Libcalls, MustPreserveList, AsmUsed, Mangler);
427 for (GlobalVariable &v : MergedModule->globals())
428 applyRestriction(v, Libcalls, MustPreserveList, AsmUsed, Mangler);
429 for (GlobalAlias &a : MergedModule->aliases())
430 applyRestriction(a, Libcalls, MustPreserveList, AsmUsed, Mangler);
432 GlobalVariable *LLVMCompilerUsed =
433 MergedModule->getGlobalVariable("llvm.compiler.used");
434 findUsedValues(LLVMCompilerUsed, AsmUsed);
435 if (LLVMCompilerUsed)
436 LLVMCompilerUsed->eraseFromParent();
438 if (!AsmUsed.empty()) {
439 llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(Context);
440 std::vector<Constant*> asmUsed2;
441 for (auto *GV : AsmUsed) {
442 Constant *c = ConstantExpr::getBitCast(GV, i8PTy);
443 asmUsed2.push_back(c);
446 llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, asmUsed2.size());
448 new llvm::GlobalVariable(*MergedModule, ATy, false,
449 llvm::GlobalValue::AppendingLinkage,
450 llvm::ConstantArray::get(ATy, asmUsed2),
451 "llvm.compiler.used");
453 LLVMCompilerUsed->setSection("llvm.metadata");
456 passes.add(createInternalizePass(MustPreserveList));
458 // apply scope restrictions
459 passes.run(*MergedModule);
461 ScopeRestrictionsDone = true;
464 /// Optimize merged modules using various IPO passes
465 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
466 bool DisableGVNLoadPRE,
467 bool DisableVectorization) {
468 if (!this->determineTarget())
471 // Mark which symbols can not be internalized
472 this->applyScopeRestrictions();
474 // Instantiate the pass manager to organize the passes.
475 legacy::PassManager passes;
477 // Add an appropriate DataLayout instance for this module...
478 MergedModule->setDataLayout(TargetMach->createDataLayout());
481 createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
483 Triple TargetTriple(TargetMach->getTargetTriple());
484 PassManagerBuilder PMB;
485 PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
486 PMB.LoopVectorize = !DisableVectorization;
487 PMB.SLPVectorize = !DisableVectorization;
489 PMB.Inliner = createFunctionInliningPass();
490 PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
491 PMB.OptLevel = OptLevel;
492 PMB.VerifyInput = !DisableVerify;
493 PMB.VerifyOutput = !DisableVerify;
495 PMB.populateLTOPassManager(passes);
497 // Run our queue of passes all at once now, efficiently.
498 passes.run(*MergedModule);
503 bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
504 if (!this->determineTarget())
507 legacy::PassManager preCodeGenPasses;
509 // If the bitcode files contain ARC code and were compiled with optimization,
510 // the ObjCARCContractPass must be run, so do it unconditionally here.
511 preCodeGenPasses.add(createObjCARCContractPass());
512 preCodeGenPasses.run(*MergedModule);
514 // Do code generation. We need to preserve the module in case the client calls
515 // writeMergedModules() after compilation, but we only need to allow this at
516 // parallelism level 1. This is achieved by having splitCodeGen return the
517 // original module at parallelism level 1 which we then assign back to
520 splitCodeGen(std::move(MergedModule), Out, MCpu, FeatureStr, Options,
521 RelocModel, CodeModel::Default, CGOptLevel, FileType);
526 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
528 void LTOCodeGenerator::setCodeGenDebugOptions(const char *Options) {
529 for (std::pair<StringRef, StringRef> o = getToken(Options); !o.first.empty();
530 o = getToken(o.second))
531 CodegenOptions.push_back(o.first);
534 void LTOCodeGenerator::parseCodeGenDebugOptions() {
535 // if options were requested, set them
536 if (!CodegenOptions.empty()) {
537 // ParseCommandLineOptions() expects argv[0] to be program name.
538 std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
539 for (std::string &Arg : CodegenOptions)
540 CodegenArgv.push_back(Arg.c_str());
541 cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
545 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
547 ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
550 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
551 // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
552 lto_codegen_diagnostic_severity_t Severity;
553 switch (DI.getSeverity()) {
555 Severity = LTO_DS_ERROR;
558 Severity = LTO_DS_WARNING;
561 Severity = LTO_DS_REMARK;
564 Severity = LTO_DS_NOTE;
567 // Create the string that will be reported to the external diagnostic handler.
568 std::string MsgStorage;
569 raw_string_ostream Stream(MsgStorage);
570 DiagnosticPrinterRawOStream DP(Stream);
574 // If this method has been called it means someone has set up an external
575 // diagnostic handler. Assert on that.
576 assert(DiagHandler && "Invalid diagnostic handler");
577 (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
581 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
583 this->DiagHandler = DiagHandler;
584 this->DiagContext = Ctxt;
586 return Context.setDiagnosticHandler(nullptr, nullptr);
587 // Register the LTOCodeGenerator stub in the LLVMContext to forward the
588 // diagnostic to the external DiagHandler.
589 Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
590 /* RespectFilters */ true);
594 class LTODiagnosticInfo : public DiagnosticInfo {
597 LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
598 : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
599 void print(DiagnosticPrinter &DP) const override { DP << Msg; }
603 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
605 (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
607 Context.diagnose(LTODiagnosticInfo(ErrMsg));