1 //===------ MachOPlatform.cpp - Utilities for executing MachO in Orc ------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
10 
11 #include "llvm/BinaryFormat/MachO.h"
12 #include "llvm/ExecutionEngine/JITLink/x86_64.h"
13 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
14 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
15 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
16 #include "llvm/Support/BinaryByteStream.h"
17 #include "llvm/Support/Debug.h"
18 
19 #define DEBUG_TYPE "orc"
20 
21 using namespace llvm;
22 using namespace llvm::orc;
23 using namespace llvm::orc::shared;
24 
25 namespace {
26 
27 class MachOHeaderMaterializationUnit : public MaterializationUnit {
28 public:
29   MachOHeaderMaterializationUnit(MachOPlatform &MOP,
30                                  const SymbolStringPtr &HeaderStartSymbol)
31       : MaterializationUnit(createHeaderSymbols(MOP, HeaderStartSymbol),
32                             HeaderStartSymbol),
33         MOP(MOP) {}
34 
35   StringRef getName() const override { return "MachOHeaderMU"; }
36 
37   void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
38     unsigned PointerSize;
39     support::endianness Endianness;
40     const auto &TT =
41         MOP.getExecutionSession().getExecutorProcessControl().getTargetTriple();
42 
43     switch (TT.getArch()) {
44     case Triple::aarch64:
45     case Triple::x86_64:
46       PointerSize = 8;
47       Endianness = support::endianness::little;
48       break;
49     default:
50       llvm_unreachable("Unrecognized architecture");
51     }
52 
53     auto G = std::make_unique<jitlink::LinkGraph>(
54         "<MachOHeaderMU>", TT, PointerSize, Endianness,
55         jitlink::getGenericEdgeKindName);
56     auto &HeaderSection = G->createSection("__header", sys::Memory::MF_READ);
57     auto &HeaderBlock = createHeaderBlock(*G, HeaderSection);
58 
59     // Init symbol is header-start symbol.
60     G->addDefinedSymbol(HeaderBlock, 0, *R->getInitializerSymbol(),
61                         HeaderBlock.getSize(), jitlink::Linkage::Strong,
62                         jitlink::Scope::Default, false, true);
63     for (auto &HS : AdditionalHeaderSymbols)
64       G->addDefinedSymbol(HeaderBlock, HS.Offset, HS.Name,
65                           HeaderBlock.getSize(), jitlink::Linkage::Strong,
66                           jitlink::Scope::Default, false, true);
67 
68     MOP.getObjectLinkingLayer().emit(std::move(R), std::move(G));
69   }
70 
71   void discard(const JITDylib &JD, const SymbolStringPtr &Sym) override {}
72 
73 private:
74   struct HeaderSymbol {
75     const char *Name;
76     uint64_t Offset;
77   };
78 
79   static constexpr HeaderSymbol AdditionalHeaderSymbols[] = {
80       {"___mh_executable_header", 0}};
81 
82   static jitlink::Block &createHeaderBlock(jitlink::LinkGraph &G,
83                                            jitlink::Section &HeaderSection) {
84     MachO::mach_header_64 Hdr;
85     Hdr.magic = MachO::MH_MAGIC_64;
86     switch (G.getTargetTriple().getArch()) {
87     case Triple::aarch64:
88       Hdr.cputype = MachO::CPU_TYPE_ARM64;
89       Hdr.cpusubtype = MachO::CPU_SUBTYPE_ARM64_ALL;
90       break;
91     case Triple::x86_64:
92       Hdr.cputype = MachO::CPU_TYPE_X86_64;
93       Hdr.cpusubtype = MachO::CPU_SUBTYPE_X86_64_ALL;
94       break;
95     default:
96       llvm_unreachable("Unrecognized architecture");
97     }
98     Hdr.filetype = MachO::MH_DYLIB; // Custom file type?
99     Hdr.ncmds = 0;
100     Hdr.sizeofcmds = 0;
101     Hdr.flags = 0;
102     Hdr.reserved = 0;
103 
104     if (G.getEndianness() != support::endian::system_endianness())
105       MachO::swapStruct(Hdr);
106 
107     auto HeaderContent = G.allocateString(
108         StringRef(reinterpret_cast<const char *>(&Hdr), sizeof(Hdr)));
109 
110     return G.createContentBlock(HeaderSection, HeaderContent, 0, 8, 0);
111   }
112 
113   static SymbolFlagsMap
114   createHeaderSymbols(MachOPlatform &MOP,
115                       const SymbolStringPtr &HeaderStartSymbol) {
116     SymbolFlagsMap HeaderSymbolFlags;
117 
118     HeaderSymbolFlags[HeaderStartSymbol] = JITSymbolFlags::Exported;
119     for (auto &HS : AdditionalHeaderSymbols)
120       HeaderSymbolFlags[MOP.getExecutionSession().intern(HS.Name)] =
121           JITSymbolFlags::Exported;
122 
123     return HeaderSymbolFlags;
124   }
125 
126   MachOPlatform &MOP;
127 };
128 
129 constexpr MachOHeaderMaterializationUnit::HeaderSymbol
130     MachOHeaderMaterializationUnit::AdditionalHeaderSymbols[];
131 
132 StringRef EHFrameSectionName = "__TEXT,__eh_frame";
133 StringRef ModInitFuncSectionName = "__DATA,__mod_init_func";
134 StringRef ObjCClassListSectionName = "__DATA,__objc_classlist";
135 StringRef ObjCImageInfoSectionName = "__DATA,__objc_image_info";
136 StringRef ObjCSelRefsSectionName = "__DATA,__objc_selrefs";
137 StringRef Swift5ProtoSectionName = "__TEXT,__swift5_proto";
138 StringRef Swift5ProtosSectionName = "__TEXT,__swift5_protos";
139 StringRef ThreadBSSSectionName = "__DATA,__thread_bss";
140 StringRef ThreadDataSectionName = "__DATA,__thread_data";
141 StringRef ThreadVarsSectionName = "__DATA,__thread_vars";
142 
143 StringRef InitSectionNames[] = {
144     ModInitFuncSectionName, ObjCSelRefsSectionName, ObjCClassListSectionName,
145     Swift5ProtosSectionName, Swift5ProtoSectionName};
146 
147 } // end anonymous namespace
148 
149 namespace llvm {
150 namespace orc {
151 
152 Expected<std::unique_ptr<MachOPlatform>>
153 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
154                       JITDylib &PlatformJD, const char *OrcRuntimePath,
155                       Optional<SymbolAliasMap> RuntimeAliases) {
156 
157   auto &EPC = ES.getExecutorProcessControl();
158 
159   // If the target is not supported then bail out immediately.
160   if (!supportedTarget(EPC.getTargetTriple()))
161     return make_error<StringError>("Unsupported MachOPlatform triple: " +
162                                        EPC.getTargetTriple().str(),
163                                    inconvertibleErrorCode());
164 
165   // Create default aliases if the caller didn't supply any.
166   if (!RuntimeAliases)
167     RuntimeAliases = standardPlatformAliases(ES);
168 
169   // Define the aliases.
170   if (auto Err = PlatformJD.define(symbolAliases(std::move(*RuntimeAliases))))
171     return std::move(Err);
172 
173   // Add JIT-dispatch function support symbols.
174   if (auto Err = PlatformJD.define(absoluteSymbols(
175           {{ES.intern("___orc_rt_jit_dispatch"),
176             {EPC.getJITDispatchInfo().JITDispatchFunction.getValue(),
177              JITSymbolFlags::Exported}},
178            {ES.intern("___orc_rt_jit_dispatch_ctx"),
179             {EPC.getJITDispatchInfo().JITDispatchContext.getValue(),
180              JITSymbolFlags::Exported}}})))
181     return std::move(Err);
182 
183   // Create a generator for the ORC runtime archive.
184   auto OrcRuntimeArchiveGenerator = StaticLibraryDefinitionGenerator::Load(
185       ObjLinkingLayer, OrcRuntimePath, EPC.getTargetTriple());
186   if (!OrcRuntimeArchiveGenerator)
187     return OrcRuntimeArchiveGenerator.takeError();
188 
189   // Create the instance.
190   Error Err = Error::success();
191   auto P = std::unique_ptr<MachOPlatform>(
192       new MachOPlatform(ES, ObjLinkingLayer, PlatformJD,
193                         std::move(*OrcRuntimeArchiveGenerator), Err));
194   if (Err)
195     return std::move(Err);
196   return std::move(P);
197 }
198 
199 Error MachOPlatform::setupJITDylib(JITDylib &JD) {
200   return JD.define(std::make_unique<MachOHeaderMaterializationUnit>(
201       *this, MachOHeaderStartSymbol));
202 }
203 
204 Error MachOPlatform::notifyAdding(ResourceTracker &RT,
205                                   const MaterializationUnit &MU) {
206   auto &JD = RT.getJITDylib();
207   const auto &InitSym = MU.getInitializerSymbol();
208   if (!InitSym)
209     return Error::success();
210 
211   RegisteredInitSymbols[&JD].add(InitSym,
212                                  SymbolLookupFlags::WeaklyReferencedSymbol);
213   LLVM_DEBUG({
214     dbgs() << "MachOPlatform: Registered init symbol " << *InitSym << " for MU "
215            << MU.getName() << "\n";
216   });
217   return Error::success();
218 }
219 
220 Error MachOPlatform::notifyRemoving(ResourceTracker &RT) {
221   llvm_unreachable("Not supported yet");
222 }
223 
224 static void addAliases(ExecutionSession &ES, SymbolAliasMap &Aliases,
225                        ArrayRef<std::pair<const char *, const char *>> AL) {
226   for (auto &KV : AL) {
227     auto AliasName = ES.intern(KV.first);
228     assert(!Aliases.count(AliasName) && "Duplicate symbol name in alias map");
229     Aliases[std::move(AliasName)] = {ES.intern(KV.second),
230                                      JITSymbolFlags::Exported};
231   }
232 }
233 
234 SymbolAliasMap MachOPlatform::standardPlatformAliases(ExecutionSession &ES) {
235   SymbolAliasMap Aliases;
236   addAliases(ES, Aliases, requiredCXXAliases());
237   addAliases(ES, Aliases, standardRuntimeUtilityAliases());
238   return Aliases;
239 }
240 
241 ArrayRef<std::pair<const char *, const char *>>
242 MachOPlatform::requiredCXXAliases() {
243   static const std::pair<const char *, const char *> RequiredCXXAliases[] = {
244       {"___cxa_atexit", "___orc_rt_macho_cxa_atexit"}};
245 
246   return ArrayRef<std::pair<const char *, const char *>>(RequiredCXXAliases);
247 }
248 
249 ArrayRef<std::pair<const char *, const char *>>
250 MachOPlatform::standardRuntimeUtilityAliases() {
251   static const std::pair<const char *, const char *>
252       StandardRuntimeUtilityAliases[] = {
253           {"___orc_rt_run_program", "___orc_rt_macho_run_program"},
254           {"___orc_rt_log_error", "___orc_rt_log_error_to_stderr"}};
255 
256   return ArrayRef<std::pair<const char *, const char *>>(
257       StandardRuntimeUtilityAliases);
258 }
259 
260 bool MachOPlatform::isInitializerSection(StringRef SegName,
261                                          StringRef SectName) {
262   for (auto &Name : InitSectionNames) {
263     if (Name.startswith(SegName) && Name.substr(7) == SectName)
264       return true;
265   }
266   return false;
267 }
268 
269 bool MachOPlatform::supportedTarget(const Triple &TT) {
270   switch (TT.getArch()) {
271   case Triple::x86_64:
272     return true;
273   default:
274     return false;
275   }
276 }
277 
278 MachOPlatform::MachOPlatform(
279     ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
280     JITDylib &PlatformJD,
281     std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator, Error &Err)
282     : ES(ES), ObjLinkingLayer(ObjLinkingLayer),
283       MachOHeaderStartSymbol(ES.intern("___dso_handle")) {
284   ErrorAsOutParameter _(&Err);
285 
286   ObjLinkingLayer.addPlugin(std::make_unique<MachOPlatformPlugin>(*this));
287 
288   PlatformJD.addGenerator(std::move(OrcRuntimeGenerator));
289 
290   // PlatformJD hasn't been 'set-up' by the platform yet (since we're creating
291   // the platform now), so set it up.
292   if (auto E2 = setupJITDylib(PlatformJD)) {
293     Err = std::move(E2);
294     return;
295   }
296 
297   RegisteredInitSymbols[&PlatformJD].add(
298       MachOHeaderStartSymbol, SymbolLookupFlags::WeaklyReferencedSymbol);
299 
300   // Associate wrapper function tags with JIT-side function implementations.
301   if (auto E2 = associateRuntimeSupportFunctions(PlatformJD)) {
302     Err = std::move(E2);
303     return;
304   }
305 
306   // Lookup addresses of runtime functions callable by the platform,
307   // call the platform bootstrap function to initialize the platform-state
308   // object in the executor.
309   if (auto E2 = bootstrapMachORuntime(PlatformJD)) {
310     Err = std::move(E2);
311     return;
312   }
313 }
314 
315 Error MachOPlatform::associateRuntimeSupportFunctions(JITDylib &PlatformJD) {
316   ExecutionSession::JITDispatchHandlerAssociationMap WFs;
317 
318   using GetInitializersSPSSig =
319       SPSExpected<SPSMachOJITDylibInitializerSequence>(SPSString);
320   WFs[ES.intern("___orc_rt_macho_get_initializers_tag")] =
321       ES.wrapAsyncWithSPS<GetInitializersSPSSig>(
322           this, &MachOPlatform::rt_getInitializers);
323 
324   using GetDeinitializersSPSSig =
325       SPSExpected<SPSMachOJITDylibDeinitializerSequence>(SPSExecutorAddr);
326   WFs[ES.intern("___orc_rt_macho_get_deinitializers_tag")] =
327       ES.wrapAsyncWithSPS<GetDeinitializersSPSSig>(
328           this, &MachOPlatform::rt_getDeinitializers);
329 
330   using LookupSymbolSPSSig =
331       SPSExpected<SPSExecutorAddr>(SPSExecutorAddr, SPSString);
332   WFs[ES.intern("___orc_rt_macho_symbol_lookup_tag")] =
333       ES.wrapAsyncWithSPS<LookupSymbolSPSSig>(this,
334                                               &MachOPlatform::rt_lookupSymbol);
335 
336   return ES.registerJITDispatchHandlers(PlatformJD, std::move(WFs));
337 }
338 
339 void MachOPlatform::getInitializersBuildSequencePhase(
340     SendInitializerSequenceFn SendResult, JITDylib &JD,
341     std::vector<JITDylibSP> DFSLinkOrder) {
342   MachOJITDylibInitializerSequence FullInitSeq;
343   {
344     std::lock_guard<std::mutex> Lock(PlatformMutex);
345     for (auto &InitJD : reverse(DFSLinkOrder)) {
346       LLVM_DEBUG({
347         dbgs() << "MachOPlatform: Appending inits for \"" << InitJD->getName()
348                << "\" to sequence\n";
349       });
350       auto ISItr = InitSeqs.find(InitJD.get());
351       if (ISItr != InitSeqs.end()) {
352         FullInitSeq.emplace_back(std::move(ISItr->second));
353         InitSeqs.erase(ISItr);
354       }
355     }
356   }
357 
358   SendResult(std::move(FullInitSeq));
359 }
360 
361 void MachOPlatform::getInitializersLookupPhase(
362     SendInitializerSequenceFn SendResult, JITDylib &JD) {
363 
364   auto DFSLinkOrder = JD.getDFSLinkOrder();
365   DenseMap<JITDylib *, SymbolLookupSet> NewInitSymbols;
366   ES.runSessionLocked([&]() {
367     for (auto &InitJD : DFSLinkOrder) {
368       auto RISItr = RegisteredInitSymbols.find(InitJD.get());
369       if (RISItr != RegisteredInitSymbols.end()) {
370         NewInitSymbols[InitJD.get()] = std::move(RISItr->second);
371         RegisteredInitSymbols.erase(RISItr);
372       }
373     }
374   });
375 
376   // If there are no further init symbols to look up then move on to the next
377   // phase.
378   if (NewInitSymbols.empty()) {
379     getInitializersBuildSequencePhase(std::move(SendResult), JD,
380                                       std::move(DFSLinkOrder));
381     return;
382   }
383 
384   // Otherwise issue a lookup and re-run this phase when it completes.
385   lookupInitSymbolsAsync(
386       [this, SendResult = std::move(SendResult), &JD](Error Err) mutable {
387         if (Err)
388           SendResult(std::move(Err));
389         else
390           getInitializersLookupPhase(std::move(SendResult), JD);
391       },
392       ES, std::move(NewInitSymbols));
393 }
394 
395 void MachOPlatform::rt_getInitializers(SendInitializerSequenceFn SendResult,
396                                        StringRef JDName) {
397   LLVM_DEBUG({
398     dbgs() << "MachOPlatform::rt_getInitializers(\"" << JDName << "\")\n";
399   });
400 
401   JITDylib *JD = ES.getJITDylibByName(JDName);
402   if (!JD) {
403     LLVM_DEBUG({
404       dbgs() << "  No such JITDylib \"" << JDName << "\". Sending error.\n";
405     });
406     SendResult(make_error<StringError>("No JITDylib named " + JDName,
407                                        inconvertibleErrorCode()));
408     return;
409   }
410 
411   getInitializersLookupPhase(std::move(SendResult), *JD);
412 }
413 
414 void MachOPlatform::rt_getDeinitializers(SendDeinitializerSequenceFn SendResult,
415                                          ExecutorAddr Handle) {
416   LLVM_DEBUG({
417     dbgs() << "MachOPlatform::rt_getDeinitializers(\""
418            << formatv("{0:x}", Handle.getValue()) << "\")\n";
419   });
420 
421   JITDylib *JD = nullptr;
422 
423   {
424     std::lock_guard<std::mutex> Lock(PlatformMutex);
425     auto I = HeaderAddrToJITDylib.find(Handle.getValue());
426     if (I != HeaderAddrToJITDylib.end())
427       JD = I->second;
428   }
429 
430   if (!JD) {
431     LLVM_DEBUG({
432       dbgs() << "  No JITDylib for handle "
433              << formatv("{0:x}", Handle.getValue()) << "\n";
434     });
435     SendResult(make_error<StringError>("No JITDylib associated with handle " +
436                                            formatv("{0:x}", Handle.getValue()),
437                                        inconvertibleErrorCode()));
438     return;
439   }
440 
441   SendResult(MachOJITDylibDeinitializerSequence());
442 }
443 
444 void MachOPlatform::rt_lookupSymbol(SendSymbolAddressFn SendResult,
445                                     ExecutorAddr Handle, StringRef SymbolName) {
446   LLVM_DEBUG({
447     dbgs() << "MachOPlatform::rt_lookupSymbol(\""
448            << formatv("{0:x}", Handle.getValue()) << "\")\n";
449   });
450 
451   JITDylib *JD = nullptr;
452 
453   {
454     std::lock_guard<std::mutex> Lock(PlatformMutex);
455     auto I = HeaderAddrToJITDylib.find(Handle.getValue());
456     if (I != HeaderAddrToJITDylib.end())
457       JD = I->second;
458   }
459 
460   if (!JD) {
461     LLVM_DEBUG({
462       dbgs() << "  No JITDylib for handle "
463              << formatv("{0:x}", Handle.getValue()) << "\n";
464     });
465     SendResult(make_error<StringError>("No JITDylib associated with handle " +
466                                            formatv("{0:x}", Handle.getValue()),
467                                        inconvertibleErrorCode()));
468     return;
469   }
470 
471   // Use functor class to work around XL build compiler issue on AIX.
472   class RtLookupNotifyComplete {
473   public:
474     RtLookupNotifyComplete(SendSymbolAddressFn &&SendResult)
475         : SendResult(std::move(SendResult)) {}
476     void operator()(Expected<SymbolMap> Result) {
477       if (Result) {
478         assert(Result->size() == 1 && "Unexpected result map count");
479         SendResult(ExecutorAddr(Result->begin()->second.getAddress()));
480       } else {
481         SendResult(Result.takeError());
482       }
483     }
484 
485   private:
486     SendSymbolAddressFn SendResult;
487   };
488 
489   // FIXME: Proper mangling.
490   auto MangledName = ("_" + SymbolName).str();
491   ES.lookup(
492       LookupKind::DLSym, {{JD, JITDylibLookupFlags::MatchExportedSymbolsOnly}},
493       SymbolLookupSet(ES.intern(MangledName)), SymbolState::Ready,
494       RtLookupNotifyComplete(std::move(SendResult)), NoDependenciesToRegister);
495 }
496 
497 Error MachOPlatform::bootstrapMachORuntime(JITDylib &PlatformJD) {
498 
499   if (auto Err = lookupAndRecordAddrs(
500           ES, LookupKind::Static, makeJITDylibSearchOrder(&PlatformJD),
501           {{ES.intern("___orc_rt_macho_platform_bootstrap"),
502             &orc_rt_macho_platform_bootstrap},
503            {ES.intern("___orc_rt_macho_platform_shutdown"),
504             &orc_rt_macho_platform_shutdown},
505            {ES.intern("___orc_rt_macho_register_object_sections"),
506             &orc_rt_macho_register_object_sections},
507            {ES.intern("___orc_rt_macho_create_pthread_key"),
508             &orc_rt_macho_create_pthread_key}}))
509     return Err;
510 
511   if (auto Err =
512           ES.callSPSWrapper<void()>(orc_rt_macho_platform_bootstrap.getValue()))
513     return Err;
514 
515   // FIXME: Ordering is fuzzy here. We're probably best off saying
516   // "behavior is undefined if code that uses the runtime is added before
517   // the platform constructor returns", then move all this to the constructor.
518   RuntimeBootstrapped = true;
519   std::vector<MachOPerObjectSectionsToRegister> DeferredPOSRs;
520   {
521     std::lock_guard<std::mutex> Lock(PlatformMutex);
522     DeferredPOSRs = std::move(BootstrapPOSRs);
523   }
524 
525   for (auto &D : DeferredPOSRs)
526     if (auto Err = registerPerObjectSections(D))
527       return Err;
528 
529   return Error::success();
530 }
531 
532 Error MachOPlatform::registerInitInfo(
533     JITDylib &JD, ExecutorAddr ObjCImageInfoAddr,
534     ArrayRef<jitlink::Section *> InitSections) {
535 
536   std::unique_lock<std::mutex> Lock(PlatformMutex);
537 
538   MachOJITDylibInitializers *InitSeq = nullptr;
539   {
540     auto I = InitSeqs.find(&JD);
541     if (I == InitSeqs.end()) {
542       // If there's no init sequence entry yet then we need to look up the
543       // header symbol to force creation of one.
544       Lock.unlock();
545 
546       auto SearchOrder =
547           JD.withLinkOrderDo([](const JITDylibSearchOrder &SO) { return SO; });
548       if (auto Err = ES.lookup(SearchOrder, MachOHeaderStartSymbol).takeError())
549         return Err;
550 
551       Lock.lock();
552       I = InitSeqs.find(&JD);
553       assert(I != InitSeqs.end() &&
554              "Entry missing after header symbol lookup?");
555     }
556     InitSeq = &I->second;
557   }
558 
559   InitSeq->ObjCImageInfoAddress = ObjCImageInfoAddr;
560 
561   for (auto *Sec : InitSections) {
562     // FIXME: Avoid copy here.
563     jitlink::SectionRange R(*Sec);
564     InitSeq->InitSections[Sec->getName()].push_back(
565         {ExecutorAddr(R.getStart()), ExecutorAddr(R.getEnd())});
566   }
567 
568   return Error::success();
569 }
570 
571 Error MachOPlatform::registerPerObjectSections(
572     const MachOPerObjectSectionsToRegister &POSR) {
573 
574   if (!orc_rt_macho_register_object_sections)
575     return make_error<StringError>("Attempting to register per-object "
576                                    "sections, but runtime support has not "
577                                    "been loaded yet",
578                                    inconvertibleErrorCode());
579 
580   Error ErrResult = Error::success();
581   if (auto Err = ES.callSPSWrapper<shared::SPSError(
582                      SPSMachOPerObjectSectionsToRegister)>(
583           orc_rt_macho_register_object_sections.getValue(), ErrResult, POSR))
584     return Err;
585   return ErrResult;
586 }
587 
588 Expected<uint64_t> MachOPlatform::createPThreadKey() {
589   if (!orc_rt_macho_create_pthread_key)
590     return make_error<StringError>(
591         "Attempting to create pthread key in target, but runtime support has "
592         "not been loaded yet",
593         inconvertibleErrorCode());
594 
595   Expected<uint64_t> Result(0);
596   if (auto Err = ES.callSPSWrapper<SPSExpected<uint64_t>(void)>(
597           orc_rt_macho_create_pthread_key.getValue(), Result))
598     return std::move(Err);
599   return Result;
600 }
601 
602 void MachOPlatform::MachOPlatformPlugin::modifyPassConfig(
603     MaterializationResponsibility &MR, jitlink::LinkGraph &LG,
604     jitlink::PassConfiguration &Config) {
605 
606   // If the initializer symbol is the MachOHeader start symbol then just add
607   // the macho header support passes.
608   if (MR.getInitializerSymbol() == MP.MachOHeaderStartSymbol) {
609     addMachOHeaderSupportPasses(MR, Config);
610     // The header materialization unit doesn't require any other support, so we
611     // can bail out early.
612     return;
613   }
614 
615   // If the object contains initializers then add passes to record them.
616   if (MR.getInitializerSymbol())
617     addInitializerSupportPasses(MR, Config);
618 
619   // Add passes for eh-frame and TLV support.
620   addEHAndTLVSupportPasses(MR, Config);
621 }
622 
623 ObjectLinkingLayer::Plugin::SyntheticSymbolDependenciesMap
624 MachOPlatform::MachOPlatformPlugin::getSyntheticSymbolDependencies(
625     MaterializationResponsibility &MR) {
626   std::lock_guard<std::mutex> Lock(PluginMutex);
627   auto I = InitSymbolDeps.find(&MR);
628   if (I != InitSymbolDeps.end()) {
629     SyntheticSymbolDependenciesMap Result;
630     Result[MR.getInitializerSymbol()] = std::move(I->second);
631     InitSymbolDeps.erase(&MR);
632     return Result;
633   }
634   return SyntheticSymbolDependenciesMap();
635 }
636 
637 void MachOPlatform::MachOPlatformPlugin::addInitializerSupportPasses(
638     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
639 
640   /// Preserve init sections.
641   Config.PrePrunePasses.push_back([this, &MR](jitlink::LinkGraph &G) {
642     if (auto Err = preserveInitSections(G, MR))
643       return Err;
644     return processObjCImageInfo(G, MR);
645   });
646 
647   Config.PostFixupPasses.push_back(
648       [this, &JD = MR.getTargetJITDylib()](jitlink::LinkGraph &G) {
649         return registerInitSections(G, JD);
650       });
651 }
652 
653 void MachOPlatform::MachOPlatformPlugin::addMachOHeaderSupportPasses(
654     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
655 
656   Config.PostAllocationPasses.push_back([this, &JD = MR.getTargetJITDylib()](
657                                             jitlink::LinkGraph &G) -> Error {
658     auto I = llvm::find_if(G.defined_symbols(), [this](jitlink::Symbol *Sym) {
659       return Sym->getName() == *MP.MachOHeaderStartSymbol;
660     });
661     assert(I != G.defined_symbols().end() &&
662            "Missing MachO header start symbol");
663     {
664       std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
665       JITTargetAddress HeaderAddr = (*I)->getAddress();
666       MP.HeaderAddrToJITDylib[HeaderAddr] = &JD;
667       assert(!MP.InitSeqs.count(&JD) && "InitSeq entry for JD already exists");
668       MP.InitSeqs.insert(std::make_pair(
669           &JD,
670           MachOJITDylibInitializers(JD.getName(), ExecutorAddr(HeaderAddr))));
671     }
672     return Error::success();
673   });
674 }
675 
676 void MachOPlatform::MachOPlatformPlugin::addEHAndTLVSupportPasses(
677     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
678 
679   // Insert TLV lowering at the start of the PostPrunePasses, since we want
680   // it to run before GOT/PLT lowering.
681   Config.PostPrunePasses.insert(
682       Config.PostPrunePasses.begin(),
683       [this, &JD = MR.getTargetJITDylib()](jitlink::LinkGraph &G) {
684         return fixTLVSectionsAndEdges(G, JD);
685       });
686 
687   // Add a pass to register the final addresses of the eh-frame and TLV sections
688   // with the runtime.
689   Config.PostFixupPasses.push_back([this](jitlink::LinkGraph &G) -> Error {
690     MachOPerObjectSectionsToRegister POSR;
691 
692     if (auto *EHFrameSection = G.findSectionByName(EHFrameSectionName)) {
693       jitlink::SectionRange R(*EHFrameSection);
694       if (!R.empty())
695         POSR.EHFrameSection = {ExecutorAddr(R.getStart()),
696                                ExecutorAddr(R.getEnd())};
697     }
698 
699     // Get a pointer to the thread data section if there is one. It will be used
700     // below.
701     jitlink::Section *ThreadDataSection =
702         G.findSectionByName(ThreadDataSectionName);
703 
704     // Handle thread BSS section if there is one.
705     if (auto *ThreadBSSSection = G.findSectionByName(ThreadBSSSectionName)) {
706       // If there's already a thread data section in this graph then merge the
707       // thread BSS section content into it, otherwise just treat the thread
708       // BSS section as the thread data section.
709       if (ThreadDataSection)
710         G.mergeSections(*ThreadDataSection, *ThreadBSSSection);
711       else
712         ThreadDataSection = ThreadBSSSection;
713     }
714 
715     // Having merged thread BSS (if present) and thread data (if present),
716     // record the resulting section range.
717     if (ThreadDataSection) {
718       jitlink::SectionRange R(*ThreadDataSection);
719       if (!R.empty())
720         POSR.ThreadDataSection = {ExecutorAddr(R.getStart()),
721                                   ExecutorAddr(R.getEnd())};
722     }
723 
724     if (POSR.EHFrameSection.Start || POSR.ThreadDataSection.Start) {
725 
726       // If we're still bootstrapping the runtime then just record this
727       // frame for now.
728       if (!MP.RuntimeBootstrapped) {
729         std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
730         MP.BootstrapPOSRs.push_back(POSR);
731         return Error::success();
732       }
733 
734       // Otherwise register it immediately.
735       if (auto Err = MP.registerPerObjectSections(POSR))
736         return Err;
737     }
738 
739     return Error::success();
740   });
741 }
742 
743 Error MachOPlatform::MachOPlatformPlugin::preserveInitSections(
744     jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
745 
746   JITLinkSymbolSet InitSectionSymbols;
747   for (auto &InitSectionName : InitSectionNames) {
748     // Skip non-init sections.
749     auto *InitSection = G.findSectionByName(InitSectionName);
750     if (!InitSection)
751       continue;
752 
753     // Make a pass over live symbols in the section: those blocks are already
754     // preserved.
755     DenseSet<jitlink::Block *> AlreadyLiveBlocks;
756     for (auto &Sym : InitSection->symbols()) {
757       auto &B = Sym->getBlock();
758       if (Sym->isLive() && Sym->getOffset() == 0 &&
759           Sym->getSize() == B.getSize() && !AlreadyLiveBlocks.count(&B)) {
760         InitSectionSymbols.insert(Sym);
761         AlreadyLiveBlocks.insert(&B);
762       }
763     }
764 
765     // Add anonymous symbols to preserve any not-already-preserved blocks.
766     for (auto *B : InitSection->blocks())
767       if (!AlreadyLiveBlocks.count(B))
768         InitSectionSymbols.insert(
769             &G.addAnonymousSymbol(*B, 0, B->getSize(), false, true));
770   }
771 
772   if (!InitSectionSymbols.empty()) {
773     std::lock_guard<std::mutex> Lock(PluginMutex);
774     InitSymbolDeps[&MR] = std::move(InitSectionSymbols);
775   }
776 
777   return Error::success();
778 }
779 
780 Error MachOPlatform::MachOPlatformPlugin::processObjCImageInfo(
781     jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
782 
783   // If there's an ObjC imagine info then either
784   //   (1) It's the first __objc_imageinfo we've seen in this JITDylib. In
785   //       this case we name and record it.
786   // OR
787   //   (2) We already have a recorded __objc_imageinfo for this JITDylib,
788   //       in which case we just verify it.
789   auto *ObjCImageInfo = G.findSectionByName(ObjCImageInfoSectionName);
790   if (!ObjCImageInfo)
791     return Error::success();
792 
793   auto ObjCImageInfoBlocks = ObjCImageInfo->blocks();
794 
795   // Check that the section is not empty if present.
796   if (llvm::empty(ObjCImageInfoBlocks))
797     return make_error<StringError>("Empty " + ObjCImageInfoSectionName +
798                                        " section in " + G.getName(),
799                                    inconvertibleErrorCode());
800 
801   // Check that there's only one block in the section.
802   if (std::next(ObjCImageInfoBlocks.begin()) != ObjCImageInfoBlocks.end())
803     return make_error<StringError>("Multiple blocks in " +
804                                        ObjCImageInfoSectionName +
805                                        " section in " + G.getName(),
806                                    inconvertibleErrorCode());
807 
808   // Check that the __objc_imageinfo section is unreferenced.
809   // FIXME: We could optimize this check if Symbols had a ref-count.
810   for (auto &Sec : G.sections()) {
811     if (&Sec != ObjCImageInfo)
812       for (auto *B : Sec.blocks())
813         for (auto &E : B->edges())
814           if (E.getTarget().isDefined() &&
815               &E.getTarget().getBlock().getSection() == ObjCImageInfo)
816             return make_error<StringError>(ObjCImageInfoSectionName +
817                                                " is referenced within file " +
818                                                G.getName(),
819                                            inconvertibleErrorCode());
820   }
821 
822   auto &ObjCImageInfoBlock = **ObjCImageInfoBlocks.begin();
823   auto *ObjCImageInfoData = ObjCImageInfoBlock.getContent().data();
824   auto Version = support::endian::read32(ObjCImageInfoData, G.getEndianness());
825   auto Flags =
826       support::endian::read32(ObjCImageInfoData + 4, G.getEndianness());
827 
828   // Lock the mutex while we verify / update the ObjCImageInfos map.
829   std::lock_guard<std::mutex> Lock(PluginMutex);
830 
831   auto ObjCImageInfoItr = ObjCImageInfos.find(&MR.getTargetJITDylib());
832   if (ObjCImageInfoItr != ObjCImageInfos.end()) {
833     // We've already registered an __objc_imageinfo section. Verify the
834     // content of this new section matches, then delete it.
835     if (ObjCImageInfoItr->second.first != Version)
836       return make_error<StringError>(
837           "ObjC version in " + G.getName() +
838               " does not match first registered version",
839           inconvertibleErrorCode());
840     if (ObjCImageInfoItr->second.second != Flags)
841       return make_error<StringError>("ObjC flags in " + G.getName() +
842                                          " do not match first registered flags",
843                                      inconvertibleErrorCode());
844 
845     // __objc_imageinfo is valid. Delete the block.
846     for (auto *S : ObjCImageInfo->symbols())
847       G.removeDefinedSymbol(*S);
848     G.removeBlock(ObjCImageInfoBlock);
849   } else {
850     // We haven't registered an __objc_imageinfo section yet. Register and
851     // move on. The section should already be marked no-dead-strip.
852     ObjCImageInfos[&MR.getTargetJITDylib()] = std::make_pair(Version, Flags);
853   }
854 
855   return Error::success();
856 }
857 
858 Error MachOPlatform::MachOPlatformPlugin::registerInitSections(
859     jitlink::LinkGraph &G, JITDylib &JD) {
860 
861   ExecutorAddr ObjCImageInfoAddr;
862   SmallVector<jitlink::Section *> InitSections;
863 
864   if (auto *ObjCImageInfoSec = G.findSectionByName(ObjCImageInfoSectionName)) {
865     if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart())
866       ObjCImageInfoAddr.setValue(Addr);
867   }
868 
869   for (auto InitSectionName : InitSectionNames)
870     if (auto *Sec = G.findSectionByName(InitSectionName))
871       InitSections.push_back(Sec);
872 
873   // Dump the scraped inits.
874   LLVM_DEBUG({
875     dbgs() << "MachOPlatform: Scraped " << G.getName() << " init sections:\n";
876     if (ObjCImageInfoAddr)
877       dbgs() << "  " << ObjCImageInfoSectionName << ": "
878              << formatv("{0:x}", ObjCImageInfoAddr.getValue()) << "\n";
879     for (auto *Sec : InitSections) {
880       jitlink::SectionRange R(*Sec);
881       dbgs() << "  " << Sec->getName() << ": "
882              << formatv("[ {0:x} -- {1:x} ]", R.getStart(), R.getEnd()) << "\n";
883     }
884   });
885 
886   return MP.registerInitInfo(JD, ObjCImageInfoAddr, InitSections);
887 }
888 
889 Error MachOPlatform::MachOPlatformPlugin::fixTLVSectionsAndEdges(
890     jitlink::LinkGraph &G, JITDylib &JD) {
891 
892   // Rename external references to __tlv_bootstrap to ___orc_rt_tlv_get_addr.
893   for (auto *Sym : G.external_symbols())
894     if (Sym->getName() == "__tlv_bootstrap") {
895       Sym->setName("___orc_rt_macho_tlv_get_addr");
896       break;
897     }
898 
899   // Store key in __thread_vars struct fields.
900   if (auto *ThreadDataSec = G.findSectionByName(ThreadVarsSectionName)) {
901     Optional<uint64_t> Key;
902     {
903       std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
904       auto I = MP.JITDylibToPThreadKey.find(&JD);
905       if (I != MP.JITDylibToPThreadKey.end())
906         Key = I->second;
907     }
908 
909     if (!Key) {
910       if (auto KeyOrErr = MP.createPThreadKey())
911         Key = *KeyOrErr;
912       else
913         return KeyOrErr.takeError();
914     }
915 
916     uint64_t PlatformKeyBits =
917         support::endian::byte_swap(*Key, G.getEndianness());
918 
919     for (auto *B : ThreadDataSec->blocks()) {
920       if (B->getSize() != 3 * G.getPointerSize())
921         return make_error<StringError>("__thread_vars block at " +
922                                            formatv("{0:x}", B->getAddress()) +
923                                            " has unexpected size",
924                                        inconvertibleErrorCode());
925 
926       auto NewBlockContent = G.allocateBuffer(B->getSize());
927       llvm::copy(B->getContent(), NewBlockContent.data());
928       memcpy(NewBlockContent.data() + G.getPointerSize(), &PlatformKeyBits,
929              G.getPointerSize());
930       B->setContent(NewBlockContent);
931     }
932   }
933 
934   // Transform any TLV edges into GOT edges.
935   for (auto *B : G.blocks())
936     for (auto &E : B->edges())
937       if (E.getKind() ==
938           jitlink::x86_64::RequestTLVPAndTransformToPCRel32TLVPLoadREXRelaxable)
939         E.setKind(jitlink::x86_64::
940                       RequestGOTAndTransformToPCRel32GOTLoadREXRelaxable);
941 
942   return Error::success();
943 }
944 
945 } // End namespace orc.
946 } // End namespace llvm.
947