1 //===--------- LLJIT.cpp - An ORC-based JIT for compiling LLVM IR ---------===//
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/LLJIT.h"
10 #include "llvm/ExecutionEngine/JITLink/EHFrameSupport.h"
11 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
12 #include "llvm/ExecutionEngine/Orc/ExecutorProcessControl.h"
13 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
14 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
15 #include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
16 #include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
17 #include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
18 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
19 #include "llvm/IR/GlobalVariable.h"
20 #include "llvm/IR/IRBuilder.h"
21 #include "llvm/IR/Mangler.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/Support/DynamicLibrary.h"
24 
25 #include <map>
26 
27 #define DEBUG_TYPE "orc"
28 
29 using namespace llvm;
30 using namespace llvm::orc;
31 
32 namespace {
33 
34 /// Adds helper function decls and wrapper functions that call the helper with
35 /// some additional prefix arguments.
36 ///
37 /// E.g. For wrapper "foo" with type i8(i8, i64), helper "bar", and prefix
38 /// args i32 4 and i16 12345, this function will add:
39 ///
40 /// declare i8 @bar(i32, i16, i8, i64)
41 ///
42 /// define i8 @foo(i8, i64) {
43 /// entry:
44 ///   %2 = call i8 @bar(i32 4, i16 12345, i8 %0, i64 %1)
45 ///   ret i8 %2
46 /// }
47 ///
48 Function *addHelperAndWrapper(Module &M, StringRef WrapperName,
49                               FunctionType *WrapperFnType,
50                               GlobalValue::VisibilityTypes WrapperVisibility,
51                               StringRef HelperName,
52                               ArrayRef<Value *> HelperPrefixArgs) {
53   std::vector<Type *> HelperArgTypes;
54   for (auto *Arg : HelperPrefixArgs)
55     HelperArgTypes.push_back(Arg->getType());
56   for (auto *T : WrapperFnType->params())
57     HelperArgTypes.push_back(T);
58   auto *HelperFnType =
59       FunctionType::get(WrapperFnType->getReturnType(), HelperArgTypes, false);
60   auto *HelperFn = Function::Create(HelperFnType, GlobalValue::ExternalLinkage,
61                                     HelperName, M);
62 
63   auto *WrapperFn = Function::Create(
64       WrapperFnType, GlobalValue::ExternalLinkage, WrapperName, M);
65   WrapperFn->setVisibility(WrapperVisibility);
66 
67   auto *EntryBlock = BasicBlock::Create(M.getContext(), "entry", WrapperFn);
68   IRBuilder<> IB(EntryBlock);
69 
70   std::vector<Value *> HelperArgs;
71   for (auto *Arg : HelperPrefixArgs)
72     HelperArgs.push_back(Arg);
73   for (auto &Arg : WrapperFn->args())
74     HelperArgs.push_back(&Arg);
75   auto *HelperResult = IB.CreateCall(HelperFn, HelperArgs);
76   if (HelperFn->getReturnType()->isVoidTy())
77     IB.CreateRetVoid();
78   else
79     IB.CreateRet(HelperResult);
80 
81   return WrapperFn;
82 }
83 
84 class GenericLLVMIRPlatformSupport;
85 
86 /// orc::Platform component of Generic LLVM IR Platform support.
87 /// Just forwards calls to the GenericLLVMIRPlatformSupport class below.
88 class GenericLLVMIRPlatform : public Platform {
89 public:
90   GenericLLVMIRPlatform(GenericLLVMIRPlatformSupport &S) : S(S) {}
91   Error setupJITDylib(JITDylib &JD) override;
92   Error notifyAdding(ResourceTracker &RT,
93                      const MaterializationUnit &MU) override;
94   Error notifyRemoving(ResourceTracker &RT) override {
95     // Noop -- Nothing to do (yet).
96     return Error::success();
97   }
98 
99 private:
100   GenericLLVMIRPlatformSupport &S;
101 };
102 
103 /// This transform parses llvm.global_ctors to produce a single initialization
104 /// function for the module, records the function, then deletes
105 /// llvm.global_ctors.
106 class GlobalCtorDtorScraper {
107 public:
108 
109   GlobalCtorDtorScraper(GenericLLVMIRPlatformSupport &PS,
110                         StringRef InitFunctionPrefix)
111     : PS(PS), InitFunctionPrefix(InitFunctionPrefix) {}
112   Expected<ThreadSafeModule> operator()(ThreadSafeModule TSM,
113                                         MaterializationResponsibility &R);
114 
115 private:
116   GenericLLVMIRPlatformSupport &PS;
117   StringRef InitFunctionPrefix;
118 };
119 
120 /// Generic IR Platform Support
121 ///
122 /// Scrapes llvm.global_ctors and llvm.global_dtors and replaces them with
123 /// specially named 'init' and 'deinit'. Injects definitions / interposes for
124 /// some runtime API, including __cxa_atexit, dlopen, and dlclose.
125 class GenericLLVMIRPlatformSupport : public LLJIT::PlatformSupport {
126 public:
127   GenericLLVMIRPlatformSupport(LLJIT &J)
128       : J(J), InitFunctionPrefix(J.mangle("__orc_init_func.")) {
129 
130     getExecutionSession().setPlatform(
131         std::make_unique<GenericLLVMIRPlatform>(*this));
132 
133     setInitTransform(J, GlobalCtorDtorScraper(*this, InitFunctionPrefix));
134 
135     SymbolMap StdInterposes;
136 
137     StdInterposes[J.mangleAndIntern("__lljit.platform_support_instance")] =
138         JITEvaluatedSymbol(pointerToJITTargetAddress(this),
139                            JITSymbolFlags::Exported);
140     StdInterposes[J.mangleAndIntern("__lljit.cxa_atexit_helper")] =
141         JITEvaluatedSymbol(pointerToJITTargetAddress(registerAtExitHelper),
142                            JITSymbolFlags());
143 
144     cantFail(
145         J.getMainJITDylib().define(absoluteSymbols(std::move(StdInterposes))));
146     cantFail(setupJITDylib(J.getMainJITDylib()));
147     cantFail(J.addIRModule(J.getMainJITDylib(), createPlatformRuntimeModule()));
148   }
149 
150   ExecutionSession &getExecutionSession() { return J.getExecutionSession(); }
151 
152   /// Adds a module that defines the __dso_handle global.
153   Error setupJITDylib(JITDylib &JD) {
154 
155     // Add per-jitdylib standard interposes.
156     SymbolMap PerJDInterposes;
157     PerJDInterposes[J.mangleAndIntern("__lljit.run_atexits_helper")] =
158         JITEvaluatedSymbol(pointerToJITTargetAddress(runAtExitsHelper),
159                            JITSymbolFlags());
160     cantFail(JD.define(absoluteSymbols(std::move(PerJDInterposes))));
161 
162     auto Ctx = std::make_unique<LLVMContext>();
163     auto M = std::make_unique<Module>("__standard_lib", *Ctx);
164     M->setDataLayout(J.getDataLayout());
165 
166     auto *Int64Ty = Type::getInt64Ty(*Ctx);
167     auto *DSOHandle = new GlobalVariable(
168         *M, Int64Ty, true, GlobalValue::ExternalLinkage,
169         ConstantInt::get(Int64Ty, reinterpret_cast<uintptr_t>(&JD)),
170         "__dso_handle");
171     DSOHandle->setVisibility(GlobalValue::DefaultVisibility);
172     DSOHandle->setInitializer(
173         ConstantInt::get(Int64Ty, pointerToJITTargetAddress(&JD)));
174 
175     auto *GenericIRPlatformSupportTy =
176         StructType::create(*Ctx, "lljit.GenericLLJITIRPlatformSupport");
177 
178     auto *PlatformInstanceDecl = new GlobalVariable(
179         *M, GenericIRPlatformSupportTy, true, GlobalValue::ExternalLinkage,
180         nullptr, "__lljit.platform_support_instance");
181 
182     auto *VoidTy = Type::getVoidTy(*Ctx);
183     addHelperAndWrapper(
184         *M, "__lljit_run_atexits", FunctionType::get(VoidTy, {}, false),
185         GlobalValue::HiddenVisibility, "__lljit.run_atexits_helper",
186         {PlatformInstanceDecl, DSOHandle});
187 
188     return J.addIRModule(JD, ThreadSafeModule(std::move(M), std::move(Ctx)));
189   }
190 
191   Error notifyAdding(ResourceTracker &RT, const MaterializationUnit &MU) {
192     auto &JD = RT.getJITDylib();
193     if (auto &InitSym = MU.getInitializerSymbol())
194       InitSymbols[&JD].add(InitSym, SymbolLookupFlags::WeaklyReferencedSymbol);
195     else {
196       // If there's no identified init symbol attached, but there is a symbol
197       // with the GenericIRPlatform::InitFunctionPrefix, then treat that as
198       // an init function. Add the symbol to both the InitSymbols map (which
199       // will trigger a lookup to materialize the module) and the InitFunctions
200       // map (which holds the names of the symbols to execute).
201       for (auto &KV : MU.getSymbols())
202         if ((*KV.first).startswith(InitFunctionPrefix)) {
203           InitSymbols[&JD].add(KV.first,
204                                SymbolLookupFlags::WeaklyReferencedSymbol);
205           InitFunctions[&JD].add(KV.first);
206         }
207     }
208     return Error::success();
209   }
210 
211   Error initialize(JITDylib &JD) override {
212     LLVM_DEBUG({
213       dbgs() << "GenericLLVMIRPlatformSupport getting initializers to run\n";
214     });
215     if (auto Initializers = getInitializers(JD)) {
216       LLVM_DEBUG(
217           { dbgs() << "GenericLLVMIRPlatformSupport running initializers\n"; });
218       for (auto InitFnAddr : *Initializers) {
219         LLVM_DEBUG({
220           dbgs() << "  Running init " << formatv("{0:x16}", InitFnAddr)
221                  << "...\n";
222         });
223         auto *InitFn = jitTargetAddressToFunction<void (*)()>(InitFnAddr);
224         InitFn();
225       }
226     } else
227       return Initializers.takeError();
228     return Error::success();
229   }
230 
231   Error deinitialize(JITDylib &JD) override {
232     LLVM_DEBUG({
233       dbgs() << "GenericLLVMIRPlatformSupport getting deinitializers to run\n";
234     });
235     if (auto Deinitializers = getDeinitializers(JD)) {
236       LLVM_DEBUG({
237         dbgs() << "GenericLLVMIRPlatformSupport running deinitializers\n";
238       });
239       for (auto DeinitFnAddr : *Deinitializers) {
240         LLVM_DEBUG({
241           dbgs() << "  Running deinit " << formatv("{0:x16}", DeinitFnAddr)
242                  << "...\n";
243         });
244         auto *DeinitFn = jitTargetAddressToFunction<void (*)()>(DeinitFnAddr);
245         DeinitFn();
246       }
247     } else
248       return Deinitializers.takeError();
249 
250     return Error::success();
251   }
252 
253   void registerInitFunc(JITDylib &JD, SymbolStringPtr InitName) {
254     getExecutionSession().runSessionLocked([&]() {
255         InitFunctions[&JD].add(InitName);
256       });
257   }
258 
259 private:
260 
261   Expected<std::vector<JITTargetAddress>> getInitializers(JITDylib &JD) {
262     if (auto Err = issueInitLookups(JD))
263       return std::move(Err);
264 
265     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
266     std::vector<JITDylibSP> DFSLinkOrder;
267 
268     getExecutionSession().runSessionLocked([&]() {
269       DFSLinkOrder = JD.getDFSLinkOrder();
270 
271       for (auto &NextJD : DFSLinkOrder) {
272         auto IFItr = InitFunctions.find(NextJD.get());
273         if (IFItr != InitFunctions.end()) {
274           LookupSymbols[NextJD.get()] = std::move(IFItr->second);
275           InitFunctions.erase(IFItr);
276         }
277       }
278     });
279 
280     LLVM_DEBUG({
281       dbgs() << "JITDylib init order is [ ";
282       for (auto &JD : llvm::reverse(DFSLinkOrder))
283         dbgs() << "\"" << JD->getName() << "\" ";
284       dbgs() << "]\n";
285       dbgs() << "Looking up init functions:\n";
286       for (auto &KV : LookupSymbols)
287         dbgs() << "  \"" << KV.first->getName() << "\": " << KV.second << "\n";
288     });
289 
290     auto &ES = getExecutionSession();
291     auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
292 
293     if (!LookupResult)
294       return LookupResult.takeError();
295 
296     std::vector<JITTargetAddress> Initializers;
297     while (!DFSLinkOrder.empty()) {
298       auto &NextJD = *DFSLinkOrder.back();
299       DFSLinkOrder.pop_back();
300       auto InitsItr = LookupResult->find(&NextJD);
301       if (InitsItr == LookupResult->end())
302         continue;
303       for (auto &KV : InitsItr->second)
304         Initializers.push_back(KV.second.getAddress());
305     }
306 
307     return Initializers;
308   }
309 
310   Expected<std::vector<JITTargetAddress>> getDeinitializers(JITDylib &JD) {
311     auto &ES = getExecutionSession();
312 
313     auto LLJITRunAtExits = J.mangleAndIntern("__lljit_run_atexits");
314 
315     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
316     std::vector<JITDylibSP> DFSLinkOrder;
317 
318     ES.runSessionLocked([&]() {
319       DFSLinkOrder = JD.getDFSLinkOrder();
320 
321       for (auto &NextJD : DFSLinkOrder) {
322         auto &JDLookupSymbols = LookupSymbols[NextJD.get()];
323         auto DIFItr = DeInitFunctions.find(NextJD.get());
324         if (DIFItr != DeInitFunctions.end()) {
325           LookupSymbols[NextJD.get()] = std::move(DIFItr->second);
326           DeInitFunctions.erase(DIFItr);
327         }
328         JDLookupSymbols.add(LLJITRunAtExits,
329                             SymbolLookupFlags::WeaklyReferencedSymbol);
330       }
331     });
332 
333     LLVM_DEBUG({
334       dbgs() << "JITDylib deinit order is [ ";
335       for (auto &JD : DFSLinkOrder)
336         dbgs() << "\"" << JD->getName() << "\" ";
337       dbgs() << "]\n";
338       dbgs() << "Looking up deinit functions:\n";
339       for (auto &KV : LookupSymbols)
340         dbgs() << "  \"" << KV.first->getName() << "\": " << KV.second << "\n";
341     });
342 
343     auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
344 
345     if (!LookupResult)
346       return LookupResult.takeError();
347 
348     std::vector<JITTargetAddress> DeInitializers;
349     for (auto &NextJD : DFSLinkOrder) {
350       auto DeInitsItr = LookupResult->find(NextJD.get());
351       assert(DeInitsItr != LookupResult->end() &&
352              "Every JD should have at least __lljit_run_atexits");
353 
354       auto RunAtExitsItr = DeInitsItr->second.find(LLJITRunAtExits);
355       if (RunAtExitsItr != DeInitsItr->second.end())
356         DeInitializers.push_back(RunAtExitsItr->second.getAddress());
357 
358       for (auto &KV : DeInitsItr->second)
359         if (KV.first != LLJITRunAtExits)
360           DeInitializers.push_back(KV.second.getAddress());
361     }
362 
363     return DeInitializers;
364   }
365 
366   /// Issue lookups for all init symbols required to initialize JD (and any
367   /// JITDylibs that it depends on).
368   Error issueInitLookups(JITDylib &JD) {
369     DenseMap<JITDylib *, SymbolLookupSet> RequiredInitSymbols;
370     std::vector<JITDylibSP> DFSLinkOrder;
371 
372     getExecutionSession().runSessionLocked([&]() {
373       DFSLinkOrder = JD.getDFSLinkOrder();
374 
375       for (auto &NextJD : DFSLinkOrder) {
376         auto ISItr = InitSymbols.find(NextJD.get());
377         if (ISItr != InitSymbols.end()) {
378           RequiredInitSymbols[NextJD.get()] = std::move(ISItr->second);
379           InitSymbols.erase(ISItr);
380         }
381       }
382     });
383 
384     return Platform::lookupInitSymbols(getExecutionSession(),
385                                        RequiredInitSymbols)
386         .takeError();
387   }
388 
389   static void registerAtExitHelper(void *Self, void (*F)(void *), void *Ctx,
390                                    void *DSOHandle) {
391     LLVM_DEBUG({
392       dbgs() << "Registering atexit function " << (void *)F << " for JD "
393              << (*static_cast<JITDylib **>(DSOHandle))->getName() << "\n";
394     });
395     static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.registerAtExit(
396         F, Ctx, DSOHandle);
397   }
398 
399   static void runAtExitsHelper(void *Self, void *DSOHandle) {
400     LLVM_DEBUG({
401       dbgs() << "Running atexit functions for JD "
402              << (*static_cast<JITDylib **>(DSOHandle))->getName() << "\n";
403     });
404     static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.runAtExits(
405         DSOHandle);
406   }
407 
408   // Constructs an LLVM IR module containing platform runtime globals,
409   // functions, and interposes.
410   ThreadSafeModule createPlatformRuntimeModule() {
411     auto Ctx = std::make_unique<LLVMContext>();
412     auto M = std::make_unique<Module>("__standard_lib", *Ctx);
413     M->setDataLayout(J.getDataLayout());
414 
415     auto *GenericIRPlatformSupportTy =
416         StructType::create(*Ctx, "lljit.GenericLLJITIRPlatformSupport");
417 
418     auto *PlatformInstanceDecl = new GlobalVariable(
419         *M, GenericIRPlatformSupportTy, true, GlobalValue::ExternalLinkage,
420         nullptr, "__lljit.platform_support_instance");
421 
422     auto *Int8Ty = Type::getInt8Ty(*Ctx);
423     auto *IntTy = Type::getIntNTy(*Ctx, sizeof(int) * CHAR_BIT);
424     auto *VoidTy = Type::getVoidTy(*Ctx);
425     auto *BytePtrTy = PointerType::getUnqual(Int8Ty);
426     auto *AtExitCallbackTy = FunctionType::get(VoidTy, {BytePtrTy}, false);
427     auto *AtExitCallbackPtrTy = PointerType::getUnqual(AtExitCallbackTy);
428 
429     addHelperAndWrapper(
430         *M, "__cxa_atexit",
431         FunctionType::get(IntTy, {AtExitCallbackPtrTy, BytePtrTy, BytePtrTy},
432                           false),
433         GlobalValue::DefaultVisibility, "__lljit.cxa_atexit_helper",
434         {PlatformInstanceDecl});
435 
436     return ThreadSafeModule(std::move(M), std::move(Ctx));
437   }
438 
439   LLJIT &J;
440   std::string InitFunctionPrefix;
441   DenseMap<JITDylib *, SymbolLookupSet> InitSymbols;
442   DenseMap<JITDylib *, SymbolLookupSet> InitFunctions;
443   DenseMap<JITDylib *, SymbolLookupSet> DeInitFunctions;
444   ItaniumCXAAtExitSupport AtExitMgr;
445 };
446 
447 Error GenericLLVMIRPlatform::setupJITDylib(JITDylib &JD) {
448   return S.setupJITDylib(JD);
449 }
450 
451 Error GenericLLVMIRPlatform::notifyAdding(ResourceTracker &RT,
452                                           const MaterializationUnit &MU) {
453   return S.notifyAdding(RT, MU);
454 }
455 
456 Expected<ThreadSafeModule>
457 GlobalCtorDtorScraper::operator()(ThreadSafeModule TSM,
458                                   MaterializationResponsibility &R) {
459   auto Err = TSM.withModuleDo([&](Module &M) -> Error {
460     auto &Ctx = M.getContext();
461     auto *GlobalCtors = M.getNamedGlobal("llvm.global_ctors");
462 
463     // If there's no llvm.global_ctors or it's just a decl then skip.
464     if (!GlobalCtors || GlobalCtors->isDeclaration())
465       return Error::success();
466 
467     std::string InitFunctionName;
468     raw_string_ostream(InitFunctionName)
469         << InitFunctionPrefix << M.getModuleIdentifier();
470 
471     MangleAndInterner Mangle(PS.getExecutionSession(), M.getDataLayout());
472     auto InternedName = Mangle(InitFunctionName);
473     if (auto Err =
474             R.defineMaterializing({{InternedName, JITSymbolFlags::Callable}}))
475       return Err;
476 
477     auto *InitFunc =
478         Function::Create(FunctionType::get(Type::getVoidTy(Ctx), {}, false),
479                          GlobalValue::ExternalLinkage, InitFunctionName, &M);
480     InitFunc->setVisibility(GlobalValue::HiddenVisibility);
481     std::vector<std::pair<Function *, unsigned>> Inits;
482     for (auto E : getConstructors(M))
483       Inits.push_back(std::make_pair(E.Func, E.Priority));
484     llvm::sort(Inits, [](const std::pair<Function *, unsigned> &LHS,
485                          const std::pair<Function *, unsigned> &RHS) {
486       return LHS.first < RHS.first;
487     });
488     auto *EntryBlock = BasicBlock::Create(Ctx, "entry", InitFunc);
489     IRBuilder<> IB(EntryBlock);
490     for (auto &KV : Inits)
491       IB.CreateCall(KV.first);
492     IB.CreateRetVoid();
493 
494     PS.registerInitFunc(R.getTargetJITDylib(), InternedName);
495     GlobalCtors->eraseFromParent();
496     return Error::success();
497   });
498 
499   if (Err)
500     return std::move(Err);
501 
502   return std::move(TSM);
503 }
504 
505 /// Inactive Platform Support
506 ///
507 /// Explicitly disables platform support. JITDylibs are not scanned for special
508 /// init/deinit symbols. No runtime API interposes are injected.
509 class InactivePlatformSupport : public LLJIT::PlatformSupport {
510 public:
511   InactivePlatformSupport() = default;
512 
513   Error initialize(JITDylib &JD) override {
514     LLVM_DEBUG(dbgs() << "InactivePlatformSupport: no initializers running for "
515                       << JD.getName() << "\n");
516     return Error::success();
517   }
518 
519   Error deinitialize(JITDylib &JD) override {
520     LLVM_DEBUG(
521         dbgs() << "InactivePlatformSupport: no deinitializers running for "
522                << JD.getName() << "\n");
523     return Error::success();
524   }
525 };
526 
527 } // end anonymous namespace
528 
529 namespace llvm {
530 namespace orc {
531 
532 void LLJIT::PlatformSupport::setInitTransform(
533     LLJIT &J, IRTransformLayer::TransformFunction T) {
534   J.InitHelperTransformLayer->setTransform(std::move(T));
535 }
536 
537 LLJIT::PlatformSupport::~PlatformSupport() {}
538 
539 Error LLJITBuilderState::prepareForConstruction() {
540 
541   LLVM_DEBUG(dbgs() << "Preparing to create LLJIT instance...\n");
542 
543   if (!JTMB) {
544     LLVM_DEBUG({
545       dbgs() << "  No explicitly set JITTargetMachineBuilder. "
546                 "Detecting host...\n";
547     });
548     if (auto JTMBOrErr = JITTargetMachineBuilder::detectHost())
549       JTMB = std::move(*JTMBOrErr);
550     else
551       return JTMBOrErr.takeError();
552   }
553 
554   LLVM_DEBUG({
555     dbgs() << "  JITTargetMachineBuilder is "
556            << JITTargetMachineBuilderPrinter(*JTMB, "  ")
557            << "  Pre-constructed ExecutionSession: " << (ES ? "Yes" : "No")
558            << "\n"
559            << "  DataLayout: ";
560     if (DL)
561       dbgs() << DL->getStringRepresentation() << "\n";
562     else
563       dbgs() << "None (will be created by JITTargetMachineBuilder)\n";
564 
565     dbgs() << "  Custom object-linking-layer creator: "
566            << (CreateObjectLinkingLayer ? "Yes" : "No") << "\n"
567            << "  Custom compile-function creator: "
568            << (CreateCompileFunction ? "Yes" : "No") << "\n"
569            << "  Custom platform-setup function: "
570            << (SetUpPlatform ? "Yes" : "No") << "\n"
571            << "  Number of compile threads: " << NumCompileThreads;
572     if (!NumCompileThreads)
573       dbgs() << " (code will be compiled on the execution thread)\n";
574     else
575       dbgs() << "\n";
576   });
577 
578   // If the client didn't configure any linker options then auto-configure the
579   // JIT linker.
580   if (!CreateObjectLinkingLayer) {
581     auto &TT = JTMB->getTargetTriple();
582     if (TT.isOSBinFormatMachO() &&
583         (TT.getArch() == Triple::aarch64 || TT.getArch() == Triple::x86_64)) {
584 
585       JTMB->setRelocationModel(Reloc::PIC_);
586       JTMB->setCodeModel(CodeModel::Small);
587       CreateObjectLinkingLayer =
588           [EPC = this->EPC](
589               ExecutionSession &ES,
590               const Triple &) -> Expected<std::unique_ptr<ObjectLayer>> {
591         std::unique_ptr<ObjectLinkingLayer> ObjLinkingLayer;
592         if (EPC)
593           ObjLinkingLayer =
594               std::make_unique<ObjectLinkingLayer>(ES, EPC->getMemMgr());
595         else
596           ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
597               ES, std::make_unique<jitlink::InProcessMemoryManager>());
598         ObjLinkingLayer->addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
599             ES, std::make_unique<jitlink::InProcessEHFrameRegistrar>()));
600         return std::move(ObjLinkingLayer);
601       };
602     }
603   }
604 
605   return Error::success();
606 }
607 
608 LLJIT::~LLJIT() {
609   if (CompileThreads)
610     CompileThreads->wait();
611   if (auto Err = ES->endSession())
612     ES->reportError(std::move(Err));
613 }
614 
615 Error LLJIT::addIRModule(ResourceTrackerSP RT, ThreadSafeModule TSM) {
616   assert(TSM && "Can not add null module");
617 
618   if (auto Err =
619           TSM.withModuleDo([&](Module &M) { return applyDataLayout(M); }))
620     return Err;
621 
622   return InitHelperTransformLayer->add(std::move(RT), std::move(TSM));
623 }
624 
625 Error LLJIT::addIRModule(JITDylib &JD, ThreadSafeModule TSM) {
626   return addIRModule(JD.getDefaultResourceTracker(), std::move(TSM));
627 }
628 
629 Error LLJIT::addObjectFile(ResourceTrackerSP RT,
630                            std::unique_ptr<MemoryBuffer> Obj) {
631   assert(Obj && "Can not add null object");
632 
633   return ObjTransformLayer->add(std::move(RT), std::move(Obj));
634 }
635 
636 Error LLJIT::addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj) {
637   return addObjectFile(JD.getDefaultResourceTracker(), std::move(Obj));
638 }
639 
640 Expected<JITEvaluatedSymbol> LLJIT::lookupLinkerMangled(JITDylib &JD,
641                                                         SymbolStringPtr Name) {
642   return ES->lookup(
643       makeJITDylibSearchOrder(&JD, JITDylibLookupFlags::MatchAllSymbols), Name);
644 }
645 
646 Expected<std::unique_ptr<ObjectLayer>>
647 LLJIT::createObjectLinkingLayer(LLJITBuilderState &S, ExecutionSession &ES) {
648 
649   // If the config state provided an ObjectLinkingLayer factory then use it.
650   if (S.CreateObjectLinkingLayer)
651     return S.CreateObjectLinkingLayer(ES, S.JTMB->getTargetTriple());
652 
653   // Otherwise default to creating an RTDyldObjectLinkingLayer that constructs
654   // a new SectionMemoryManager for each object.
655   auto GetMemMgr = []() { return std::make_unique<SectionMemoryManager>(); };
656   auto Layer =
657       std::make_unique<RTDyldObjectLinkingLayer>(ES, std::move(GetMemMgr));
658 
659   if (S.JTMB->getTargetTriple().isOSBinFormatCOFF()) {
660     Layer->setOverrideObjectFlagsWithResponsibilityFlags(true);
661     Layer->setAutoClaimResponsibilityForObjectSymbols(true);
662   }
663 
664   // FIXME: Explicit conversion to std::unique_ptr<ObjectLayer> added to silence
665   //        errors from some GCC / libstdc++ bots. Remove this conversion (i.e.
666   //        just return ObjLinkingLayer) once those bots are upgraded.
667   return std::unique_ptr<ObjectLayer>(std::move(Layer));
668 }
669 
670 Expected<std::unique_ptr<IRCompileLayer::IRCompiler>>
671 LLJIT::createCompileFunction(LLJITBuilderState &S,
672                              JITTargetMachineBuilder JTMB) {
673 
674   /// If there is a custom compile function creator set then use it.
675   if (S.CreateCompileFunction)
676     return S.CreateCompileFunction(std::move(JTMB));
677 
678   // Otherwise default to creating a SimpleCompiler, or ConcurrentIRCompiler,
679   // depending on the number of threads requested.
680   if (S.NumCompileThreads > 0)
681     return std::make_unique<ConcurrentIRCompiler>(std::move(JTMB));
682 
683   auto TM = JTMB.createTargetMachine();
684   if (!TM)
685     return TM.takeError();
686 
687   return std::make_unique<TMOwningSimpleCompiler>(std::move(*TM));
688 }
689 
690 LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
691     : ES(S.ES ? std::move(S.ES) : std::make_unique<ExecutionSession>()), Main(),
692       DL(""), TT(S.JTMB->getTargetTriple()) {
693 
694   ErrorAsOutParameter _(&Err);
695 
696   if (auto MainOrErr = this->ES->createJITDylib("main"))
697     Main = &*MainOrErr;
698   else {
699     Err = MainOrErr.takeError();
700     return;
701   }
702 
703   if (S.DL)
704     DL = std::move(*S.DL);
705   else if (auto DLOrErr = S.JTMB->getDefaultDataLayoutForTarget())
706     DL = std::move(*DLOrErr);
707   else {
708     Err = DLOrErr.takeError();
709     return;
710   }
711 
712   auto ObjLayer = createObjectLinkingLayer(S, *ES);
713   if (!ObjLayer) {
714     Err = ObjLayer.takeError();
715     return;
716   }
717   ObjLinkingLayer = std::move(*ObjLayer);
718   ObjTransformLayer =
719       std::make_unique<ObjectTransformLayer>(*ES, *ObjLinkingLayer);
720 
721   {
722     auto CompileFunction = createCompileFunction(S, std::move(*S.JTMB));
723     if (!CompileFunction) {
724       Err = CompileFunction.takeError();
725       return;
726     }
727     CompileLayer = std::make_unique<IRCompileLayer>(
728         *ES, *ObjTransformLayer, std::move(*CompileFunction));
729     TransformLayer = std::make_unique<IRTransformLayer>(*ES, *CompileLayer);
730     InitHelperTransformLayer =
731         std::make_unique<IRTransformLayer>(*ES, *TransformLayer);
732   }
733 
734   if (S.NumCompileThreads > 0) {
735     InitHelperTransformLayer->setCloneToNewContextOnEmit(true);
736     CompileThreads =
737         std::make_unique<ThreadPool>(hardware_concurrency(S.NumCompileThreads));
738     ES->setDispatchTask([this](std::unique_ptr<Task> T) {
739       // FIXME: We should be able to use move-capture here, but ThreadPool's
740       // AsyncTaskTys are std::functions rather than unique_functions
741       // (because MSVC's std::packaged_tasks don't support move-only types).
742       // Fix this when all the above gets sorted out.
743       CompileThreads->async([UnownedT = T.release()]() mutable {
744         std::unique_ptr<Task> T(UnownedT);
745         T->run();
746       });
747     });
748   }
749 
750   if (S.SetUpPlatform)
751     Err = S.SetUpPlatform(*this);
752   else
753     setUpGenericLLVMIRPlatform(*this);
754 }
755 
756 std::string LLJIT::mangle(StringRef UnmangledName) const {
757   std::string MangledName;
758   {
759     raw_string_ostream MangledNameStream(MangledName);
760     Mangler::getNameWithPrefix(MangledNameStream, UnmangledName, DL);
761   }
762   return MangledName;
763 }
764 
765 Error LLJIT::applyDataLayout(Module &M) {
766   if (M.getDataLayout().isDefault())
767     M.setDataLayout(DL);
768 
769   if (M.getDataLayout() != DL)
770     return make_error<StringError>(
771         "Added modules have incompatible data layouts: " +
772             M.getDataLayout().getStringRepresentation() + " (module) vs " +
773             DL.getStringRepresentation() + " (jit)",
774         inconvertibleErrorCode());
775 
776   return Error::success();
777 }
778 
779 void setUpGenericLLVMIRPlatform(LLJIT &J) {
780   LLVM_DEBUG(
781       { dbgs() << "Setting up GenericLLVMIRPlatform support for LLJIT\n"; });
782   J.setPlatformSupport(std::make_unique<GenericLLVMIRPlatformSupport>(J));
783 }
784 
785 Error setUpInactivePlatform(LLJIT &J) {
786   LLVM_DEBUG(
787       { dbgs() << "Explicitly deactivated platform support for LLJIT\n"; });
788   J.setPlatformSupport(std::make_unique<InactivePlatformSupport>());
789   return Error::success();
790 }
791 
792 Error LLLazyJITBuilderState::prepareForConstruction() {
793   if (auto Err = LLJITBuilderState::prepareForConstruction())
794     return Err;
795   TT = JTMB->getTargetTriple();
796   return Error::success();
797 }
798 
799 Error LLLazyJIT::addLazyIRModule(JITDylib &JD, ThreadSafeModule TSM) {
800   assert(TSM && "Can not add null module");
801 
802   if (auto Err = TSM.withModuleDo(
803           [&](Module &M) -> Error { return applyDataLayout(M); }))
804     return Err;
805 
806   return CODLayer->add(JD, std::move(TSM));
807 }
808 
809 LLLazyJIT::LLLazyJIT(LLLazyJITBuilderState &S, Error &Err) : LLJIT(S, Err) {
810 
811   // If LLJIT construction failed then bail out.
812   if (Err)
813     return;
814 
815   ErrorAsOutParameter _(&Err);
816 
817   /// Take/Create the lazy-compile callthrough manager.
818   if (S.LCTMgr)
819     LCTMgr = std::move(S.LCTMgr);
820   else {
821     if (auto LCTMgrOrErr = createLocalLazyCallThroughManager(
822             S.TT, *ES, S.LazyCompileFailureAddr))
823       LCTMgr = std::move(*LCTMgrOrErr);
824     else {
825       Err = LCTMgrOrErr.takeError();
826       return;
827     }
828   }
829 
830   // Take/Create the indirect stubs manager builder.
831   auto ISMBuilder = std::move(S.ISMBuilder);
832 
833   // If none was provided, try to build one.
834   if (!ISMBuilder)
835     ISMBuilder = createLocalIndirectStubsManagerBuilder(S.TT);
836 
837   // No luck. Bail out.
838   if (!ISMBuilder) {
839     Err = make_error<StringError>("Could not construct "
840                                   "IndirectStubsManagerBuilder for target " +
841                                       S.TT.str(),
842                                   inconvertibleErrorCode());
843     return;
844   }
845 
846   // Create the COD layer.
847   CODLayer = std::make_unique<CompileOnDemandLayer>(
848       *ES, *InitHelperTransformLayer, *LCTMgr, std::move(ISMBuilder));
849 
850   if (S.NumCompileThreads > 0)
851     CODLayer->setCloneToNewContextOnEmit(true);
852 }
853 
854 } // End namespace orc.
855 } // End namespace llvm.
856