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 teardownJITDylib(JITDylib &JD) override;
93   Error notifyAdding(ResourceTracker &RT,
94                      const MaterializationUnit &MU) override;
95   Error notifyRemoving(ResourceTracker &RT) override {
96     // Noop -- Nothing to do (yet).
97     return Error::success();
98   }
99 
100 private:
101   GenericLLVMIRPlatformSupport &S;
102 };
103 
104 /// This transform parses llvm.global_ctors to produce a single initialization
105 /// function for the module, records the function, then deletes
106 /// llvm.global_ctors.
107 class GlobalCtorDtorScraper {
108 public:
109   GlobalCtorDtorScraper(GenericLLVMIRPlatformSupport &PS,
110                         StringRef InitFunctionPrefix,
111                         StringRef DeInitFunctionPrefix)
112       : PS(PS), InitFunctionPrefix(InitFunctionPrefix),
113         DeInitFunctionPrefix(DeInitFunctionPrefix) {}
114   Expected<ThreadSafeModule> operator()(ThreadSafeModule TSM,
115                                         MaterializationResponsibility &R);
116 
117 private:
118   GenericLLVMIRPlatformSupport &PS;
119   StringRef InitFunctionPrefix;
120   StringRef DeInitFunctionPrefix;
121 };
122 
123 /// Generic IR Platform Support
124 ///
125 /// Scrapes llvm.global_ctors and llvm.global_dtors and replaces them with
126 /// specially named 'init' and 'deinit'. Injects definitions / interposes for
127 /// some runtime API, including __cxa_atexit, dlopen, and dlclose.
128 class GenericLLVMIRPlatformSupport : public LLJIT::PlatformSupport {
129 public:
130   GenericLLVMIRPlatformSupport(LLJIT &J)
131       : J(J), InitFunctionPrefix(J.mangle("__orc_init_func.")),
132         DeInitFunctionPrefix(J.mangle("__orc_deinit_func.")) {
133 
134     getExecutionSession().setPlatform(
135         std::make_unique<GenericLLVMIRPlatform>(*this));
136 
137     setInitTransform(J, GlobalCtorDtorScraper(*this, InitFunctionPrefix,
138                                               DeInitFunctionPrefix));
139 
140     SymbolMap StdInterposes;
141 
142     StdInterposes[J.mangleAndIntern("__lljit.platform_support_instance")] =
143         JITEvaluatedSymbol(pointerToJITTargetAddress(this),
144                            JITSymbolFlags::Exported);
145     StdInterposes[J.mangleAndIntern("__lljit.cxa_atexit_helper")] =
146         JITEvaluatedSymbol(pointerToJITTargetAddress(registerAtExitHelper),
147                            JITSymbolFlags());
148 
149     cantFail(
150         J.getMainJITDylib().define(absoluteSymbols(std::move(StdInterposes))));
151     cantFail(setupJITDylib(J.getMainJITDylib()));
152     cantFail(J.addIRModule(J.getMainJITDylib(), createPlatformRuntimeModule()));
153   }
154 
155   ExecutionSession &getExecutionSession() { return J.getExecutionSession(); }
156 
157   /// Adds a module that defines the __dso_handle global.
158   Error setupJITDylib(JITDylib &JD) {
159 
160     // Add per-jitdylib standard interposes.
161     SymbolMap PerJDInterposes;
162     PerJDInterposes[J.mangleAndIntern("__lljit.run_atexits_helper")] =
163         JITEvaluatedSymbol(pointerToJITTargetAddress(runAtExitsHelper),
164                            JITSymbolFlags());
165     cantFail(JD.define(absoluteSymbols(std::move(PerJDInterposes))));
166 
167     auto Ctx = std::make_unique<LLVMContext>();
168     auto M = std::make_unique<Module>("__standard_lib", *Ctx);
169     M->setDataLayout(J.getDataLayout());
170 
171     auto *Int64Ty = Type::getInt64Ty(*Ctx);
172     auto *DSOHandle = new GlobalVariable(
173         *M, Int64Ty, true, GlobalValue::ExternalLinkage,
174         ConstantInt::get(Int64Ty, reinterpret_cast<uintptr_t>(&JD)),
175         "__dso_handle");
176     DSOHandle->setVisibility(GlobalValue::DefaultVisibility);
177     DSOHandle->setInitializer(
178         ConstantInt::get(Int64Ty, pointerToJITTargetAddress(&JD)));
179 
180     auto *GenericIRPlatformSupportTy =
181         StructType::create(*Ctx, "lljit.GenericLLJITIRPlatformSupport");
182 
183     auto *PlatformInstanceDecl = new GlobalVariable(
184         *M, GenericIRPlatformSupportTy, true, GlobalValue::ExternalLinkage,
185         nullptr, "__lljit.platform_support_instance");
186 
187     auto *VoidTy = Type::getVoidTy(*Ctx);
188     addHelperAndWrapper(
189         *M, "__lljit_run_atexits", FunctionType::get(VoidTy, {}, false),
190         GlobalValue::HiddenVisibility, "__lljit.run_atexits_helper",
191         {PlatformInstanceDecl, DSOHandle});
192 
193     return J.addIRModule(JD, ThreadSafeModule(std::move(M), std::move(Ctx)));
194   }
195 
196   Error notifyAdding(ResourceTracker &RT, const MaterializationUnit &MU) {
197     auto &JD = RT.getJITDylib();
198     if (auto &InitSym = MU.getInitializerSymbol())
199       InitSymbols[&JD].add(InitSym, SymbolLookupFlags::WeaklyReferencedSymbol);
200     else {
201       // If there's no identified init symbol attached, but there is a symbol
202       // with the GenericIRPlatform::InitFunctionPrefix, then treat that as
203       // an init function. Add the symbol to both the InitSymbols map (which
204       // will trigger a lookup to materialize the module) and the InitFunctions
205       // map (which holds the names of the symbols to execute).
206       for (auto &KV : MU.getSymbols())
207         if ((*KV.first).startswith(InitFunctionPrefix)) {
208           InitSymbols[&JD].add(KV.first,
209                                SymbolLookupFlags::WeaklyReferencedSymbol);
210           InitFunctions[&JD].add(KV.first);
211         } else if ((*KV.first).startswith(DeInitFunctionPrefix)) {
212           DeInitFunctions[&JD].add(KV.first);
213         }
214     }
215     return Error::success();
216   }
217 
218   Error initialize(JITDylib &JD) override {
219     LLVM_DEBUG({
220       dbgs() << "GenericLLVMIRPlatformSupport getting initializers to run\n";
221     });
222     if (auto Initializers = getInitializers(JD)) {
223       LLVM_DEBUG(
224           { dbgs() << "GenericLLVMIRPlatformSupport running initializers\n"; });
225       for (auto InitFnAddr : *Initializers) {
226         LLVM_DEBUG({
227           dbgs() << "  Running init " << formatv("{0:x16}", InitFnAddr)
228                  << "...\n";
229         });
230         auto *InitFn = jitTargetAddressToFunction<void (*)()>(InitFnAddr);
231         InitFn();
232       }
233     } else
234       return Initializers.takeError();
235     return Error::success();
236   }
237 
238   Error deinitialize(JITDylib &JD) override {
239     LLVM_DEBUG({
240       dbgs() << "GenericLLVMIRPlatformSupport getting deinitializers to run\n";
241     });
242     if (auto Deinitializers = getDeinitializers(JD)) {
243       LLVM_DEBUG({
244         dbgs() << "GenericLLVMIRPlatformSupport running deinitializers\n";
245       });
246       for (auto DeinitFnAddr : *Deinitializers) {
247         LLVM_DEBUG({
248           dbgs() << "  Running deinit " << formatv("{0:x16}", DeinitFnAddr)
249                  << "...\n";
250         });
251         auto *DeinitFn = jitTargetAddressToFunction<void (*)()>(DeinitFnAddr);
252         DeinitFn();
253       }
254     } else
255       return Deinitializers.takeError();
256 
257     return Error::success();
258   }
259 
260   void registerInitFunc(JITDylib &JD, SymbolStringPtr InitName) {
261     getExecutionSession().runSessionLocked([&]() {
262         InitFunctions[&JD].add(InitName);
263       });
264   }
265 
266   void registerDeInitFunc(JITDylib &JD, SymbolStringPtr DeInitName) {
267     getExecutionSession().runSessionLocked(
268         [&]() { DeInitFunctions[&JD].add(DeInitName); });
269   }
270 
271 private:
272 
273   Expected<std::vector<JITTargetAddress>> getInitializers(JITDylib &JD) {
274     if (auto Err = issueInitLookups(JD))
275       return std::move(Err);
276 
277     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
278     std::vector<JITDylibSP> DFSLinkOrder;
279 
280     getExecutionSession().runSessionLocked([&]() {
281       DFSLinkOrder = JD.getDFSLinkOrder();
282 
283       for (auto &NextJD : DFSLinkOrder) {
284         auto IFItr = InitFunctions.find(NextJD.get());
285         if (IFItr != InitFunctions.end()) {
286           LookupSymbols[NextJD.get()] = std::move(IFItr->second);
287           InitFunctions.erase(IFItr);
288         }
289       }
290     });
291 
292     LLVM_DEBUG({
293       dbgs() << "JITDylib init order is [ ";
294       for (auto &JD : llvm::reverse(DFSLinkOrder))
295         dbgs() << "\"" << JD->getName() << "\" ";
296       dbgs() << "]\n";
297       dbgs() << "Looking up init functions:\n";
298       for (auto &KV : LookupSymbols)
299         dbgs() << "  \"" << KV.first->getName() << "\": " << KV.second << "\n";
300     });
301 
302     auto &ES = getExecutionSession();
303     auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
304 
305     if (!LookupResult)
306       return LookupResult.takeError();
307 
308     std::vector<JITTargetAddress> Initializers;
309     while (!DFSLinkOrder.empty()) {
310       auto &NextJD = *DFSLinkOrder.back();
311       DFSLinkOrder.pop_back();
312       auto InitsItr = LookupResult->find(&NextJD);
313       if (InitsItr == LookupResult->end())
314         continue;
315       for (auto &KV : InitsItr->second)
316         Initializers.push_back(KV.second.getAddress());
317     }
318 
319     return Initializers;
320   }
321 
322   Expected<std::vector<JITTargetAddress>> getDeinitializers(JITDylib &JD) {
323     auto &ES = getExecutionSession();
324 
325     auto LLJITRunAtExits = J.mangleAndIntern("__lljit_run_atexits");
326 
327     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
328     std::vector<JITDylibSP> DFSLinkOrder;
329 
330     ES.runSessionLocked([&]() {
331       DFSLinkOrder = JD.getDFSLinkOrder();
332 
333       for (auto &NextJD : DFSLinkOrder) {
334         auto &JDLookupSymbols = LookupSymbols[NextJD.get()];
335         auto DIFItr = DeInitFunctions.find(NextJD.get());
336         if (DIFItr != DeInitFunctions.end()) {
337           LookupSymbols[NextJD.get()] = std::move(DIFItr->second);
338           DeInitFunctions.erase(DIFItr);
339         }
340         JDLookupSymbols.add(LLJITRunAtExits,
341                             SymbolLookupFlags::WeaklyReferencedSymbol);
342       }
343     });
344 
345     LLVM_DEBUG({
346       dbgs() << "JITDylib deinit order is [ ";
347       for (auto &JD : DFSLinkOrder)
348         dbgs() << "\"" << JD->getName() << "\" ";
349       dbgs() << "]\n";
350       dbgs() << "Looking up deinit functions:\n";
351       for (auto &KV : LookupSymbols)
352         dbgs() << "  \"" << KV.first->getName() << "\": " << KV.second << "\n";
353     });
354 
355     auto LookupResult = Platform::lookupInitSymbols(ES, LookupSymbols);
356 
357     if (!LookupResult)
358       return LookupResult.takeError();
359 
360     std::vector<JITTargetAddress> DeInitializers;
361     for (auto &NextJD : DFSLinkOrder) {
362       auto DeInitsItr = LookupResult->find(NextJD.get());
363       assert(DeInitsItr != LookupResult->end() &&
364              "Every JD should have at least __lljit_run_atexits");
365 
366       auto RunAtExitsItr = DeInitsItr->second.find(LLJITRunAtExits);
367       if (RunAtExitsItr != DeInitsItr->second.end())
368         DeInitializers.push_back(RunAtExitsItr->second.getAddress());
369 
370       for (auto &KV : DeInitsItr->second)
371         if (KV.first != LLJITRunAtExits)
372           DeInitializers.push_back(KV.second.getAddress());
373     }
374 
375     return DeInitializers;
376   }
377 
378   /// Issue lookups for all init symbols required to initialize JD (and any
379   /// JITDylibs that it depends on).
380   Error issueInitLookups(JITDylib &JD) {
381     DenseMap<JITDylib *, SymbolLookupSet> RequiredInitSymbols;
382     std::vector<JITDylibSP> DFSLinkOrder;
383 
384     getExecutionSession().runSessionLocked([&]() {
385       DFSLinkOrder = JD.getDFSLinkOrder();
386 
387       for (auto &NextJD : DFSLinkOrder) {
388         auto ISItr = InitSymbols.find(NextJD.get());
389         if (ISItr != InitSymbols.end()) {
390           RequiredInitSymbols[NextJD.get()] = std::move(ISItr->second);
391           InitSymbols.erase(ISItr);
392         }
393       }
394     });
395 
396     return Platform::lookupInitSymbols(getExecutionSession(),
397                                        RequiredInitSymbols)
398         .takeError();
399   }
400 
401   static void registerAtExitHelper(void *Self, void (*F)(void *), void *Ctx,
402                                    void *DSOHandle) {
403     LLVM_DEBUG({
404       dbgs() << "Registering atexit function " << (void *)F << " for JD "
405              << (*static_cast<JITDylib **>(DSOHandle))->getName() << "\n";
406     });
407     static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.registerAtExit(
408         F, Ctx, DSOHandle);
409   }
410 
411   static void runAtExitsHelper(void *Self, void *DSOHandle) {
412     LLVM_DEBUG({
413       dbgs() << "Running atexit functions for JD "
414              << (*static_cast<JITDylib **>(DSOHandle))->getName() << "\n";
415     });
416     static_cast<GenericLLVMIRPlatformSupport *>(Self)->AtExitMgr.runAtExits(
417         DSOHandle);
418   }
419 
420   // Constructs an LLVM IR module containing platform runtime globals,
421   // functions, and interposes.
422   ThreadSafeModule createPlatformRuntimeModule() {
423     auto Ctx = std::make_unique<LLVMContext>();
424     auto M = std::make_unique<Module>("__standard_lib", *Ctx);
425     M->setDataLayout(J.getDataLayout());
426 
427     auto *GenericIRPlatformSupportTy =
428         StructType::create(*Ctx, "lljit.GenericLLJITIRPlatformSupport");
429 
430     auto *PlatformInstanceDecl = new GlobalVariable(
431         *M, GenericIRPlatformSupportTy, true, GlobalValue::ExternalLinkage,
432         nullptr, "__lljit.platform_support_instance");
433 
434     auto *Int8Ty = Type::getInt8Ty(*Ctx);
435     auto *IntTy = Type::getIntNTy(*Ctx, sizeof(int) * CHAR_BIT);
436     auto *VoidTy = Type::getVoidTy(*Ctx);
437     auto *BytePtrTy = PointerType::getUnqual(Int8Ty);
438     auto *AtExitCallbackTy = FunctionType::get(VoidTy, {BytePtrTy}, false);
439     auto *AtExitCallbackPtrTy = PointerType::getUnqual(AtExitCallbackTy);
440 
441     addHelperAndWrapper(
442         *M, "__cxa_atexit",
443         FunctionType::get(IntTy, {AtExitCallbackPtrTy, BytePtrTy, BytePtrTy},
444                           false),
445         GlobalValue::DefaultVisibility, "__lljit.cxa_atexit_helper",
446         {PlatformInstanceDecl});
447 
448     return ThreadSafeModule(std::move(M), std::move(Ctx));
449   }
450 
451   LLJIT &J;
452   std::string InitFunctionPrefix;
453   std::string DeInitFunctionPrefix;
454   DenseMap<JITDylib *, SymbolLookupSet> InitSymbols;
455   DenseMap<JITDylib *, SymbolLookupSet> InitFunctions;
456   DenseMap<JITDylib *, SymbolLookupSet> DeInitFunctions;
457   ItaniumCXAAtExitSupport AtExitMgr;
458 };
459 
460 Error GenericLLVMIRPlatform::setupJITDylib(JITDylib &JD) {
461   return S.setupJITDylib(JD);
462 }
463 
464 Error GenericLLVMIRPlatform::teardownJITDylib(JITDylib &JD) {
465   return Error::success();
466 }
467 
468 Error GenericLLVMIRPlatform::notifyAdding(ResourceTracker &RT,
469                                           const MaterializationUnit &MU) {
470   return S.notifyAdding(RT, MU);
471 }
472 
473 Expected<ThreadSafeModule>
474 GlobalCtorDtorScraper::operator()(ThreadSafeModule TSM,
475                                   MaterializationResponsibility &R) {
476   auto Err = TSM.withModuleDo([&](Module &M) -> Error {
477     auto &Ctx = M.getContext();
478     auto *GlobalCtors = M.getNamedGlobal("llvm.global_ctors");
479     auto *GlobalDtors = M.getNamedGlobal("llvm.global_dtors");
480 
481     auto RegisterCOrDtors = [&](GlobalVariable *GlobalCOrDtors,
482                                 bool isCtor) -> Error {
483       // If there's no llvm.global_c/dtor or it's just a decl then skip.
484       if (!GlobalCOrDtors || GlobalCOrDtors->isDeclaration())
485         return Error::success();
486       std::string InitOrDeInitFunctionName;
487       if (isCtor)
488         raw_string_ostream(InitOrDeInitFunctionName)
489             << InitFunctionPrefix << M.getModuleIdentifier();
490       else
491         raw_string_ostream(InitOrDeInitFunctionName)
492             << DeInitFunctionPrefix << M.getModuleIdentifier();
493 
494       MangleAndInterner Mangle(PS.getExecutionSession(), M.getDataLayout());
495       auto InternedInitOrDeInitName = Mangle(InitOrDeInitFunctionName);
496       if (auto Err = R.defineMaterializing(
497               {{InternedInitOrDeInitName, JITSymbolFlags::Callable}}))
498         return Err;
499 
500       auto *InitOrDeInitFunc = Function::Create(
501           FunctionType::get(Type::getVoidTy(Ctx), {}, false),
502           GlobalValue::ExternalLinkage, InitOrDeInitFunctionName, &M);
503       InitOrDeInitFunc->setVisibility(GlobalValue::HiddenVisibility);
504       std::vector<std::pair<Function *, unsigned>> InitsOrDeInits;
505       auto COrDtors = isCtor ? getConstructors(M) : getDestructors(M);
506 
507       for (auto E : COrDtors)
508         InitsOrDeInits.push_back(std::make_pair(E.Func, E.Priority));
509       llvm::sort(InitsOrDeInits,
510                  [](const std::pair<Function *, unsigned> &LHS,
511                     const std::pair<Function *, unsigned> &RHS) {
512                    return LHS.first < RHS.first;
513                  });
514 
515       auto *InitOrDeInitFuncEntryBlock =
516           BasicBlock::Create(Ctx, "entry", InitOrDeInitFunc);
517       IRBuilder<> IB(InitOrDeInitFuncEntryBlock);
518       for (auto &KV : InitsOrDeInits)
519         IB.CreateCall(KV.first);
520       IB.CreateRetVoid();
521 
522       if (isCtor)
523         PS.registerInitFunc(R.getTargetJITDylib(), InternedInitOrDeInitName);
524       else
525         PS.registerDeInitFunc(R.getTargetJITDylib(), InternedInitOrDeInitName);
526 
527       GlobalCOrDtors->eraseFromParent();
528       return Error::success();
529     };
530 
531     if (auto Err = RegisterCOrDtors(GlobalCtors, true))
532       return Err;
533     if (auto Err = RegisterCOrDtors(GlobalDtors, false))
534       return Err;
535 
536     return Error::success();
537   });
538 
539   if (Err)
540     return std::move(Err);
541 
542   return std::move(TSM);
543 }
544 
545 /// Inactive Platform Support
546 ///
547 /// Explicitly disables platform support. JITDylibs are not scanned for special
548 /// init/deinit symbols. No runtime API interposes are injected.
549 class InactivePlatformSupport : public LLJIT::PlatformSupport {
550 public:
551   InactivePlatformSupport() = default;
552 
553   Error initialize(JITDylib &JD) override {
554     LLVM_DEBUG(dbgs() << "InactivePlatformSupport: no initializers running for "
555                       << JD.getName() << "\n");
556     return Error::success();
557   }
558 
559   Error deinitialize(JITDylib &JD) override {
560     LLVM_DEBUG(
561         dbgs() << "InactivePlatformSupport: no deinitializers running for "
562                << JD.getName() << "\n");
563     return Error::success();
564   }
565 };
566 
567 } // end anonymous namespace
568 
569 namespace llvm {
570 namespace orc {
571 
572 void LLJIT::PlatformSupport::setInitTransform(
573     LLJIT &J, IRTransformLayer::TransformFunction T) {
574   J.InitHelperTransformLayer->setTransform(std::move(T));
575 }
576 
577 LLJIT::PlatformSupport::~PlatformSupport() {}
578 
579 Error LLJITBuilderState::prepareForConstruction() {
580 
581   LLVM_DEBUG(dbgs() << "Preparing to create LLJIT instance...\n");
582 
583   if (!JTMB) {
584     LLVM_DEBUG({
585       dbgs() << "  No explicitly set JITTargetMachineBuilder. "
586                 "Detecting host...\n";
587     });
588     if (auto JTMBOrErr = JITTargetMachineBuilder::detectHost())
589       JTMB = std::move(*JTMBOrErr);
590     else
591       return JTMBOrErr.takeError();
592   }
593 
594   LLVM_DEBUG({
595     dbgs() << "  JITTargetMachineBuilder is "
596            << JITTargetMachineBuilderPrinter(*JTMB, "  ")
597            << "  Pre-constructed ExecutionSession: " << (ES ? "Yes" : "No")
598            << "\n"
599            << "  DataLayout: ";
600     if (DL)
601       dbgs() << DL->getStringRepresentation() << "\n";
602     else
603       dbgs() << "None (will be created by JITTargetMachineBuilder)\n";
604 
605     dbgs() << "  Custom object-linking-layer creator: "
606            << (CreateObjectLinkingLayer ? "Yes" : "No") << "\n"
607            << "  Custom compile-function creator: "
608            << (CreateCompileFunction ? "Yes" : "No") << "\n"
609            << "  Custom platform-setup function: "
610            << (SetUpPlatform ? "Yes" : "No") << "\n"
611            << "  Number of compile threads: " << NumCompileThreads;
612     if (!NumCompileThreads)
613       dbgs() << " (code will be compiled on the execution thread)\n";
614     else
615       dbgs() << "\n";
616   });
617 
618   // If neither ES nor EPC has been set then create an EPC instance.
619   if (!ES && !EPC) {
620     LLVM_DEBUG({
621       dbgs() << "ExecutorProcessControl not specified, "
622                 "Creating SelfExecutorProcessControl instance\n";
623     });
624     if (auto EPCOrErr = SelfExecutorProcessControl::Create())
625       EPC = std::move(*EPCOrErr);
626     else
627       return EPCOrErr.takeError();
628   } else
629     LLVM_DEBUG({
630       dbgs() << "Using explicitly specified ExecutorProcessControl instance "
631              << EPC.get() << "\n";
632     });
633 
634   // If the client didn't configure any linker options then auto-configure the
635   // JIT linker.
636   if (!CreateObjectLinkingLayer) {
637     auto &TT = JTMB->getTargetTriple();
638     if (TT.isOSBinFormatMachO() &&
639         (TT.getArch() == Triple::aarch64 || TT.getArch() == Triple::x86_64)) {
640 
641       JTMB->setRelocationModel(Reloc::PIC_);
642       JTMB->setCodeModel(CodeModel::Small);
643       CreateObjectLinkingLayer =
644           [](ExecutionSession &ES,
645              const Triple &) -> Expected<std::unique_ptr<ObjectLayer>> {
646         auto ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(ES);
647         ObjLinkingLayer->addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
648             ES, std::make_unique<jitlink::InProcessEHFrameRegistrar>()));
649         return std::move(ObjLinkingLayer);
650       };
651     }
652   }
653 
654   return Error::success();
655 }
656 
657 LLJIT::~LLJIT() {
658   if (CompileThreads)
659     CompileThreads->wait();
660   if (auto Err = ES->endSession())
661     ES->reportError(std::move(Err));
662 }
663 
664 Error LLJIT::addIRModule(ResourceTrackerSP RT, ThreadSafeModule TSM) {
665   assert(TSM && "Can not add null module");
666 
667   if (auto Err =
668           TSM.withModuleDo([&](Module &M) { return applyDataLayout(M); }))
669     return Err;
670 
671   return InitHelperTransformLayer->add(std::move(RT), std::move(TSM));
672 }
673 
674 Error LLJIT::addIRModule(JITDylib &JD, ThreadSafeModule TSM) {
675   return addIRModule(JD.getDefaultResourceTracker(), std::move(TSM));
676 }
677 
678 Error LLJIT::addObjectFile(ResourceTrackerSP RT,
679                            std::unique_ptr<MemoryBuffer> Obj) {
680   assert(Obj && "Can not add null object");
681 
682   return ObjTransformLayer->add(std::move(RT), std::move(Obj));
683 }
684 
685 Error LLJIT::addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj) {
686   return addObjectFile(JD.getDefaultResourceTracker(), std::move(Obj));
687 }
688 
689 Expected<JITEvaluatedSymbol> LLJIT::lookupLinkerMangled(JITDylib &JD,
690                                                         SymbolStringPtr Name) {
691   return ES->lookup(
692       makeJITDylibSearchOrder(&JD, JITDylibLookupFlags::MatchAllSymbols), Name);
693 }
694 
695 Expected<std::unique_ptr<ObjectLayer>>
696 LLJIT::createObjectLinkingLayer(LLJITBuilderState &S, ExecutionSession &ES) {
697 
698   // If the config state provided an ObjectLinkingLayer factory then use it.
699   if (S.CreateObjectLinkingLayer)
700     return S.CreateObjectLinkingLayer(ES, S.JTMB->getTargetTriple());
701 
702   // Otherwise default to creating an RTDyldObjectLinkingLayer that constructs
703   // a new SectionMemoryManager for each object.
704   auto GetMemMgr = []() { return std::make_unique<SectionMemoryManager>(); };
705   auto Layer =
706       std::make_unique<RTDyldObjectLinkingLayer>(ES, std::move(GetMemMgr));
707 
708   if (S.JTMB->getTargetTriple().isOSBinFormatCOFF()) {
709     Layer->setOverrideObjectFlagsWithResponsibilityFlags(true);
710     Layer->setAutoClaimResponsibilityForObjectSymbols(true);
711   }
712 
713   // FIXME: Explicit conversion to std::unique_ptr<ObjectLayer> added to silence
714   //        errors from some GCC / libstdc++ bots. Remove this conversion (i.e.
715   //        just return ObjLinkingLayer) once those bots are upgraded.
716   return std::unique_ptr<ObjectLayer>(std::move(Layer));
717 }
718 
719 Expected<std::unique_ptr<IRCompileLayer::IRCompiler>>
720 LLJIT::createCompileFunction(LLJITBuilderState &S,
721                              JITTargetMachineBuilder JTMB) {
722 
723   /// If there is a custom compile function creator set then use it.
724   if (S.CreateCompileFunction)
725     return S.CreateCompileFunction(std::move(JTMB));
726 
727   // Otherwise default to creating a SimpleCompiler, or ConcurrentIRCompiler,
728   // depending on the number of threads requested.
729   if (S.NumCompileThreads > 0)
730     return std::make_unique<ConcurrentIRCompiler>(std::move(JTMB));
731 
732   auto TM = JTMB.createTargetMachine();
733   if (!TM)
734     return TM.takeError();
735 
736   return std::make_unique<TMOwningSimpleCompiler>(std::move(*TM));
737 }
738 
739 LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
740     : DL(""), TT(S.JTMB->getTargetTriple()) {
741 
742   ErrorAsOutParameter _(&Err);
743 
744   assert(!(S.EPC && S.ES) && "EPC and ES should not both be set");
745 
746   if (S.EPC) {
747     ES = std::make_unique<ExecutionSession>(std::move(S.EPC));
748   } else if (S.ES)
749     ES = std::move(S.ES);
750   else {
751     if (auto EPC = SelfExecutorProcessControl::Create()) {
752       ES = std::make_unique<ExecutionSession>(std::move(*EPC));
753     } else {
754       Err = EPC.takeError();
755       return;
756     }
757   }
758 
759   if (auto MainOrErr = this->ES->createJITDylib("main"))
760     Main = &*MainOrErr;
761   else {
762     Err = MainOrErr.takeError();
763     return;
764   }
765 
766   if (S.DL)
767     DL = std::move(*S.DL);
768   else if (auto DLOrErr = S.JTMB->getDefaultDataLayoutForTarget())
769     DL = std::move(*DLOrErr);
770   else {
771     Err = DLOrErr.takeError();
772     return;
773   }
774 
775   auto ObjLayer = createObjectLinkingLayer(S, *ES);
776   if (!ObjLayer) {
777     Err = ObjLayer.takeError();
778     return;
779   }
780   ObjLinkingLayer = std::move(*ObjLayer);
781   ObjTransformLayer =
782       std::make_unique<ObjectTransformLayer>(*ES, *ObjLinkingLayer);
783 
784   {
785     auto CompileFunction = createCompileFunction(S, std::move(*S.JTMB));
786     if (!CompileFunction) {
787       Err = CompileFunction.takeError();
788       return;
789     }
790     CompileLayer = std::make_unique<IRCompileLayer>(
791         *ES, *ObjTransformLayer, std::move(*CompileFunction));
792     TransformLayer = std::make_unique<IRTransformLayer>(*ES, *CompileLayer);
793     InitHelperTransformLayer =
794         std::make_unique<IRTransformLayer>(*ES, *TransformLayer);
795   }
796 
797   if (S.NumCompileThreads > 0) {
798     InitHelperTransformLayer->setCloneToNewContextOnEmit(true);
799     CompileThreads =
800         std::make_unique<ThreadPool>(hardware_concurrency(S.NumCompileThreads));
801     ES->setDispatchTask([this](std::unique_ptr<Task> T) {
802       // FIXME: We should be able to use move-capture here, but ThreadPool's
803       // AsyncTaskTys are std::functions rather than unique_functions
804       // (because MSVC's std::packaged_tasks don't support move-only types).
805       // Fix this when all the above gets sorted out.
806       CompileThreads->async([UnownedT = T.release()]() mutable {
807         std::unique_ptr<Task> T(UnownedT);
808         T->run();
809       });
810     });
811   }
812 
813   if (S.SetUpPlatform)
814     Err = S.SetUpPlatform(*this);
815   else
816     setUpGenericLLVMIRPlatform(*this);
817 }
818 
819 std::string LLJIT::mangle(StringRef UnmangledName) const {
820   std::string MangledName;
821   {
822     raw_string_ostream MangledNameStream(MangledName);
823     Mangler::getNameWithPrefix(MangledNameStream, UnmangledName, DL);
824   }
825   return MangledName;
826 }
827 
828 Error LLJIT::applyDataLayout(Module &M) {
829   if (M.getDataLayout().isDefault())
830     M.setDataLayout(DL);
831 
832   if (M.getDataLayout() != DL)
833     return make_error<StringError>(
834         "Added modules have incompatible data layouts: " +
835             M.getDataLayout().getStringRepresentation() + " (module) vs " +
836             DL.getStringRepresentation() + " (jit)",
837         inconvertibleErrorCode());
838 
839   return Error::success();
840 }
841 
842 void setUpGenericLLVMIRPlatform(LLJIT &J) {
843   LLVM_DEBUG(
844       { dbgs() << "Setting up GenericLLVMIRPlatform support for LLJIT\n"; });
845   J.setPlatformSupport(std::make_unique<GenericLLVMIRPlatformSupport>(J));
846 }
847 
848 Error setUpInactivePlatform(LLJIT &J) {
849   LLVM_DEBUG(
850       { dbgs() << "Explicitly deactivated platform support for LLJIT\n"; });
851   J.setPlatformSupport(std::make_unique<InactivePlatformSupport>());
852   return Error::success();
853 }
854 
855 Error LLLazyJITBuilderState::prepareForConstruction() {
856   if (auto Err = LLJITBuilderState::prepareForConstruction())
857     return Err;
858   TT = JTMB->getTargetTriple();
859   return Error::success();
860 }
861 
862 Error LLLazyJIT::addLazyIRModule(JITDylib &JD, ThreadSafeModule TSM) {
863   assert(TSM && "Can not add null module");
864 
865   if (auto Err = TSM.withModuleDo(
866           [&](Module &M) -> Error { return applyDataLayout(M); }))
867     return Err;
868 
869   return CODLayer->add(JD, std::move(TSM));
870 }
871 
872 LLLazyJIT::LLLazyJIT(LLLazyJITBuilderState &S, Error &Err) : LLJIT(S, Err) {
873 
874   // If LLJIT construction failed then bail out.
875   if (Err)
876     return;
877 
878   ErrorAsOutParameter _(&Err);
879 
880   /// Take/Create the lazy-compile callthrough manager.
881   if (S.LCTMgr)
882     LCTMgr = std::move(S.LCTMgr);
883   else {
884     if (auto LCTMgrOrErr = createLocalLazyCallThroughManager(
885             S.TT, *ES, S.LazyCompileFailureAddr))
886       LCTMgr = std::move(*LCTMgrOrErr);
887     else {
888       Err = LCTMgrOrErr.takeError();
889       return;
890     }
891   }
892 
893   // Take/Create the indirect stubs manager builder.
894   auto ISMBuilder = std::move(S.ISMBuilder);
895 
896   // If none was provided, try to build one.
897   if (!ISMBuilder)
898     ISMBuilder = createLocalIndirectStubsManagerBuilder(S.TT);
899 
900   // No luck. Bail out.
901   if (!ISMBuilder) {
902     Err = make_error<StringError>("Could not construct "
903                                   "IndirectStubsManagerBuilder for target " +
904                                       S.TT.str(),
905                                   inconvertibleErrorCode());
906     return;
907   }
908 
909   // Create the COD layer.
910   CODLayer = std::make_unique<CompileOnDemandLayer>(
911       *ES, *InitHelperTransformLayer, *LCTMgr, std::move(ISMBuilder));
912 
913   if (S.NumCompileThreads > 0)
914     CODLayer->setCloneToNewContextOnEmit(true);
915 }
916 
917 } // End namespace orc.
918 } // End namespace llvm.
919