1 //===----- CompileOnDemandLayer.cpp - Lazily emit IR on first call --------===//
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/CompileOnDemandLayer.h"
10 #include "llvm/ADT/Hashing.h"
11 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
12 #include "llvm/IR/Mangler.h"
13 #include "llvm/IR/Module.h"
14 #include "llvm/Support/FormatVariadic.h"
15 #include <string>
16
17 using namespace llvm;
18 using namespace llvm::orc;
19
extractSubModule(ThreadSafeModule & TSM,StringRef Suffix,GVPredicate ShouldExtract)20 static ThreadSafeModule extractSubModule(ThreadSafeModule &TSM,
21 StringRef Suffix,
22 GVPredicate ShouldExtract) {
23
24 auto DeleteExtractedDefs = [](GlobalValue &GV) {
25 // Bump the linkage: this global will be provided by the external module.
26 GV.setLinkage(GlobalValue::ExternalLinkage);
27
28 // Delete the definition in the source module.
29 if (isa<Function>(GV)) {
30 auto &F = cast<Function>(GV);
31 F.deleteBody();
32 F.setPersonalityFn(nullptr);
33 } else if (isa<GlobalVariable>(GV)) {
34 cast<GlobalVariable>(GV).setInitializer(nullptr);
35 } else if (isa<GlobalAlias>(GV)) {
36 // We need to turn deleted aliases into function or variable decls based
37 // on the type of their aliasee.
38 auto &A = cast<GlobalAlias>(GV);
39 Constant *Aliasee = A.getAliasee();
40 assert(A.hasName() && "Anonymous alias?");
41 assert(Aliasee->hasName() && "Anonymous aliasee");
42 std::string AliasName = std::string(A.getName());
43
44 if (isa<Function>(Aliasee)) {
45 auto *F = cloneFunctionDecl(*A.getParent(), *cast<Function>(Aliasee));
46 A.replaceAllUsesWith(F);
47 A.eraseFromParent();
48 F->setName(AliasName);
49 } else if (isa<GlobalVariable>(Aliasee)) {
50 auto *G = cloneGlobalVariableDecl(*A.getParent(),
51 *cast<GlobalVariable>(Aliasee));
52 A.replaceAllUsesWith(G);
53 A.eraseFromParent();
54 G->setName(AliasName);
55 } else
56 llvm_unreachable("Alias to unsupported type");
57 } else
58 llvm_unreachable("Unsupported global type");
59 };
60
61 auto NewTSM = cloneToNewContext(TSM, ShouldExtract, DeleteExtractedDefs);
62 NewTSM.withModuleDo([&](Module &M) {
63 M.setModuleIdentifier((M.getModuleIdentifier() + Suffix).str());
64 });
65
66 return NewTSM;
67 }
68
69 namespace llvm {
70 namespace orc {
71
72 class PartitioningIRMaterializationUnit : public IRMaterializationUnit {
73 public:
PartitioningIRMaterializationUnit(ExecutionSession & ES,const IRSymbolMapper::ManglingOptions & MO,ThreadSafeModule TSM,CompileOnDemandLayer & Parent)74 PartitioningIRMaterializationUnit(ExecutionSession &ES,
75 const IRSymbolMapper::ManglingOptions &MO,
76 ThreadSafeModule TSM,
77 CompileOnDemandLayer &Parent)
78 : IRMaterializationUnit(ES, MO, std::move(TSM)), Parent(Parent) {}
79
PartitioningIRMaterializationUnit(ThreadSafeModule TSM,Interface I,SymbolNameToDefinitionMap SymbolToDefinition,CompileOnDemandLayer & Parent)80 PartitioningIRMaterializationUnit(
81 ThreadSafeModule TSM, Interface I,
82 SymbolNameToDefinitionMap SymbolToDefinition,
83 CompileOnDemandLayer &Parent)
84 : IRMaterializationUnit(std::move(TSM), std::move(I),
85 std::move(SymbolToDefinition)),
86 Parent(Parent) {}
87
88 private:
materialize(std::unique_ptr<MaterializationResponsibility> R)89 void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
90 Parent.emitPartition(std::move(R), std::move(TSM),
91 std::move(SymbolToDefinition));
92 }
93
discard(const JITDylib & V,const SymbolStringPtr & Name)94 void discard(const JITDylib &V, const SymbolStringPtr &Name) override {
95 // All original symbols were materialized by the CODLayer and should be
96 // final. The function bodies provided by M should never be overridden.
97 llvm_unreachable("Discard should never be called on an "
98 "ExtractingIRMaterializationUnit");
99 }
100
101 mutable std::mutex SourceModuleMutex;
102 CompileOnDemandLayer &Parent;
103 };
104
105 std::optional<CompileOnDemandLayer::GlobalValueSet>
compileRequested(GlobalValueSet Requested)106 CompileOnDemandLayer::compileRequested(GlobalValueSet Requested) {
107 return std::move(Requested);
108 }
109
110 std::optional<CompileOnDemandLayer::GlobalValueSet>
compileWholeModule(GlobalValueSet Requested)111 CompileOnDemandLayer::compileWholeModule(GlobalValueSet Requested) {
112 return std::nullopt;
113 }
114
CompileOnDemandLayer(ExecutionSession & ES,IRLayer & BaseLayer,LazyCallThroughManager & LCTMgr,IndirectStubsManagerBuilder BuildIndirectStubsManager)115 CompileOnDemandLayer::CompileOnDemandLayer(
116 ExecutionSession &ES, IRLayer &BaseLayer, LazyCallThroughManager &LCTMgr,
117 IndirectStubsManagerBuilder BuildIndirectStubsManager)
118 : IRLayer(ES, BaseLayer.getManglingOptions()), BaseLayer(BaseLayer),
119 LCTMgr(LCTMgr),
120 BuildIndirectStubsManager(std::move(BuildIndirectStubsManager)) {}
121
setPartitionFunction(PartitionFunction Partition)122 void CompileOnDemandLayer::setPartitionFunction(PartitionFunction Partition) {
123 this->Partition = std::move(Partition);
124 }
125
setImplMap(ImplSymbolMap * Imp)126 void CompileOnDemandLayer::setImplMap(ImplSymbolMap *Imp) {
127 this->AliaseeImpls = Imp;
128 }
emit(std::unique_ptr<MaterializationResponsibility> R,ThreadSafeModule TSM)129 void CompileOnDemandLayer::emit(
130 std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM) {
131 assert(TSM && "Null module");
132
133 auto &ES = getExecutionSession();
134
135 // Sort the callables and non-callables, build re-exports and lodge the
136 // actual module with the implementation dylib.
137 auto &PDR = getPerDylibResources(R->getTargetJITDylib());
138
139 SymbolAliasMap NonCallables;
140 SymbolAliasMap Callables;
141 TSM.withModuleDo([&](Module &M) {
142 // First, do some cleanup on the module:
143 cleanUpModule(M);
144 });
145
146 for (auto &KV : R->getSymbols()) {
147 auto &Name = KV.first;
148 auto &Flags = KV.second;
149 if (Flags.isCallable())
150 Callables[Name] = SymbolAliasMapEntry(Name, Flags);
151 else
152 NonCallables[Name] = SymbolAliasMapEntry(Name, Flags);
153 }
154
155 // Create a partitioning materialization unit and lodge it with the
156 // implementation dylib.
157 if (auto Err = PDR.getImplDylib().define(
158 std::make_unique<PartitioningIRMaterializationUnit>(
159 ES, *getManglingOptions(), std::move(TSM), *this))) {
160 ES.reportError(std::move(Err));
161 R->failMaterialization();
162 return;
163 }
164
165 if (!NonCallables.empty())
166 if (auto Err =
167 R->replace(reexports(PDR.getImplDylib(), std::move(NonCallables),
168 JITDylibLookupFlags::MatchAllSymbols))) {
169 getExecutionSession().reportError(std::move(Err));
170 R->failMaterialization();
171 return;
172 }
173 if (!Callables.empty()) {
174 if (auto Err = R->replace(
175 lazyReexports(LCTMgr, PDR.getISManager(), PDR.getImplDylib(),
176 std::move(Callables), AliaseeImpls))) {
177 getExecutionSession().reportError(std::move(Err));
178 R->failMaterialization();
179 return;
180 }
181 }
182 }
183
184 CompileOnDemandLayer::PerDylibResources &
getPerDylibResources(JITDylib & TargetD)185 CompileOnDemandLayer::getPerDylibResources(JITDylib &TargetD) {
186 std::lock_guard<std::mutex> Lock(CODLayerMutex);
187
188 auto I = DylibResources.find(&TargetD);
189 if (I == DylibResources.end()) {
190 auto &ImplD =
191 getExecutionSession().createBareJITDylib(TargetD.getName() + ".impl");
192 JITDylibSearchOrder NewLinkOrder;
193 TargetD.withLinkOrderDo([&](const JITDylibSearchOrder &TargetLinkOrder) {
194 NewLinkOrder = TargetLinkOrder;
195 });
196
197 assert(!NewLinkOrder.empty() && NewLinkOrder.front().first == &TargetD &&
198 NewLinkOrder.front().second ==
199 JITDylibLookupFlags::MatchAllSymbols &&
200 "TargetD must be at the front of its own search order and match "
201 "non-exported symbol");
202 NewLinkOrder.insert(std::next(NewLinkOrder.begin()),
203 {&ImplD, JITDylibLookupFlags::MatchAllSymbols});
204 ImplD.setLinkOrder(NewLinkOrder, false);
205 TargetD.setLinkOrder(std::move(NewLinkOrder), false);
206
207 PerDylibResources PDR(ImplD, BuildIndirectStubsManager());
208 I = DylibResources.insert(std::make_pair(&TargetD, std::move(PDR))).first;
209 }
210
211 return I->second;
212 }
213
cleanUpModule(Module & M)214 void CompileOnDemandLayer::cleanUpModule(Module &M) {
215 for (auto &F : M.functions()) {
216 if (F.isDeclaration())
217 continue;
218
219 if (F.hasAvailableExternallyLinkage()) {
220 F.deleteBody();
221 F.setPersonalityFn(nullptr);
222 continue;
223 }
224 }
225 }
226
expandPartition(GlobalValueSet & Partition)227 void CompileOnDemandLayer::expandPartition(GlobalValueSet &Partition) {
228 // Expands the partition to ensure the following rules hold:
229 // (1) If any alias is in the partition, its aliasee is also in the partition.
230 // (2) If any aliasee is in the partition, its aliases are also in the
231 // partiton.
232 // (3) If any global variable is in the partition then all global variables
233 // are in the partition.
234 assert(!Partition.empty() && "Unexpected empty partition");
235
236 const Module &M = *(*Partition.begin())->getParent();
237 bool ContainsGlobalVariables = false;
238 std::vector<const GlobalValue *> GVsToAdd;
239
240 for (const auto *GV : Partition)
241 if (isa<GlobalAlias>(GV))
242 GVsToAdd.push_back(
243 cast<GlobalValue>(cast<GlobalAlias>(GV)->getAliasee()));
244 else if (isa<GlobalVariable>(GV))
245 ContainsGlobalVariables = true;
246
247 for (auto &A : M.aliases())
248 if (Partition.count(cast<GlobalValue>(A.getAliasee())))
249 GVsToAdd.push_back(&A);
250
251 if (ContainsGlobalVariables)
252 for (auto &G : M.globals())
253 GVsToAdd.push_back(&G);
254
255 for (const auto *GV : GVsToAdd)
256 Partition.insert(GV);
257 }
258
emitPartition(std::unique_ptr<MaterializationResponsibility> R,ThreadSafeModule TSM,IRMaterializationUnit::SymbolNameToDefinitionMap Defs)259 void CompileOnDemandLayer::emitPartition(
260 std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM,
261 IRMaterializationUnit::SymbolNameToDefinitionMap Defs) {
262
263 // FIXME: Need a 'notify lazy-extracting/emitting' callback to tie the
264 // extracted module key, extracted module, and source module key
265 // together. This could be used, for example, to provide a specific
266 // memory manager instance to the linking layer.
267
268 auto &ES = getExecutionSession();
269 GlobalValueSet RequestedGVs;
270 for (auto &Name : R->getRequestedSymbols()) {
271 if (Name == R->getInitializerSymbol())
272 TSM.withModuleDo([&](Module &M) {
273 for (auto &GV : getStaticInitGVs(M))
274 RequestedGVs.insert(&GV);
275 });
276 else {
277 assert(Defs.count(Name) && "No definition for symbol");
278 RequestedGVs.insert(Defs[Name]);
279 }
280 }
281
282 /// Perform partitioning with the context lock held, since the partition
283 /// function is allowed to access the globals to compute the partition.
284 auto GVsToExtract =
285 TSM.withModuleDo([&](Module &M) { return Partition(RequestedGVs); });
286
287 // Take a 'None' partition to mean the whole module (as opposed to an empty
288 // partition, which means "materialize nothing"). Emit the whole module
289 // unmodified to the base layer.
290 if (GVsToExtract == std::nullopt) {
291 Defs.clear();
292 BaseLayer.emit(std::move(R), std::move(TSM));
293 return;
294 }
295
296 // If the partition is empty, return the whole module to the symbol table.
297 if (GVsToExtract->empty()) {
298 if (auto Err =
299 R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
300 std::move(TSM),
301 MaterializationUnit::Interface(R->getSymbols(),
302 R->getInitializerSymbol()),
303 std::move(Defs), *this))) {
304 getExecutionSession().reportError(std::move(Err));
305 R->failMaterialization();
306 return;
307 }
308 return;
309 }
310
311 // Ok -- we actually need to partition the symbols. Promote the symbol
312 // linkages/names, expand the partition to include any required symbols
313 // (i.e. symbols that can't be separated from our partition), and
314 // then extract the partition.
315 //
316 // FIXME: We apply this promotion once per partitioning. It's safe, but
317 // overkill.
318 auto ExtractedTSM =
319 TSM.withModuleDo([&](Module &M) -> Expected<ThreadSafeModule> {
320 auto PromotedGlobals = PromoteSymbols(M);
321 if (!PromotedGlobals.empty()) {
322
323 MangleAndInterner Mangle(ES, M.getDataLayout());
324 SymbolFlagsMap SymbolFlags;
325 IRSymbolMapper::add(ES, *getManglingOptions(),
326 PromotedGlobals, SymbolFlags);
327
328 if (auto Err = R->defineMaterializing(SymbolFlags))
329 return std::move(Err);
330 }
331
332 expandPartition(*GVsToExtract);
333
334 // Submodule name is given by hashing the names of the globals.
335 std::string SubModuleName;
336 {
337 std::vector<const GlobalValue*> HashGVs;
338 HashGVs.reserve(GVsToExtract->size());
339 for (const auto *GV : *GVsToExtract)
340 HashGVs.push_back(GV);
341 llvm::sort(HashGVs, [](const GlobalValue *LHS, const GlobalValue *RHS) {
342 return LHS->getName() < RHS->getName();
343 });
344 hash_code HC(0);
345 for (const auto *GV : HashGVs) {
346 assert(GV->hasName() && "All GVs to extract should be named by now");
347 auto GVName = GV->getName();
348 HC = hash_combine(HC, hash_combine_range(GVName.begin(), GVName.end()));
349 }
350 raw_string_ostream(SubModuleName)
351 << ".submodule."
352 << formatv(sizeof(size_t) == 8 ? "{0:x16}" : "{0:x8}",
353 static_cast<size_t>(HC))
354 << ".ll";
355 }
356
357 // Extract the requested partiton (plus any necessary aliases) and
358 // put the rest back into the impl dylib.
359 auto ShouldExtract = [&](const GlobalValue &GV) -> bool {
360 return GVsToExtract->count(&GV);
361 };
362
363 return extractSubModule(TSM, SubModuleName , ShouldExtract);
364 });
365
366 if (!ExtractedTSM) {
367 ES.reportError(ExtractedTSM.takeError());
368 R->failMaterialization();
369 return;
370 }
371
372 if (auto Err = R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
373 ES, *getManglingOptions(), std::move(TSM), *this))) {
374 ES.reportError(std::move(Err));
375 R->failMaterialization();
376 return;
377 }
378 BaseLayer.emit(std::move(R), std::move(*ExtractedTSM));
379 }
380
381 } // end namespace orc
382 } // end namespace llvm
383