1 //===--------------- LLJITWithCustomObjectLinkingLayer.cpp ----------------===//
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 // This file shows how to switch LLJIT to use a custom object linking layer (we
10 // use ObjectLinkingLayer, which is backed by JITLink, as an example).
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/ADT/StringMap.h"
15 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
16 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
17 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
18 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
19 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
20 #include "llvm/Support/InitLLVM.h"
21 #include "llvm/Support/TargetSelect.h"
22 #include "llvm/Support/raw_ostream.h"
23
24 #include "../ExampleModules.h"
25
26 using namespace llvm;
27 using namespace llvm::orc;
28
29 ExitOnError ExitOnErr;
30
31 const llvm::StringRef TestMod =
32 R"(
33 define i32 @callee() {
34 entry:
35 ret i32 7
36 }
37
38 define i32 @entry() {
39 entry:
40 %0 = call i32 @callee()
41 ret i32 %0
42 }
43 )";
44
45 class MyPlugin : public ObjectLinkingLayer::Plugin {
46 public:
47 // The modifyPassConfig callback gives us a chance to inspect the
48 // MaterializationResponsibility and target triple for the object being
49 // linked, then add any JITLink passes that we would like to run on the
50 // link graph. A pass is just a function object that is callable as
51 // Error(jitlink::LinkGraph&). In this case we will add two passes
52 // defined as lambdas that call the printLinkerGraph method on our
53 // plugin: One to run before the linker applies fixups and another to
54 // run afterwards.
modifyPassConfig(MaterializationResponsibility & MR,jitlink::LinkGraph & LG,jitlink::PassConfiguration & Config)55 void modifyPassConfig(MaterializationResponsibility &MR,
56 jitlink::LinkGraph &LG,
57 jitlink::PassConfiguration &Config) override {
58
59 outs() << "MyPlugin -- Modifying pass config for " << LG.getName() << " ("
60 << LG.getTargetTriple().str() << "):\n";
61
62 // Print sections, symbol names and addresses, and any edges for the
63 // associated blocks at the 'PostPrune' phase of JITLink (after
64 // dead-stripping, but before addresses are allocated in the target
65 // address space. See llvm/docs/JITLink.rst).
66 //
67 // Experiment with adding the 'printGraph' pass at other points in the
68 // pipeline. E.g. PrePrunePasses, PostAllocationPasses, and
69 // PostFixupPasses.
70 Config.PostPrunePasses.push_back(printGraph);
71 }
72
notifyLoaded(MaterializationResponsibility & MR)73 void notifyLoaded(MaterializationResponsibility &MR) override {
74 outs() << "Loading object defining " << MR.getSymbols() << "\n";
75 }
76
notifyEmitted(MaterializationResponsibility & MR)77 Error notifyEmitted(MaterializationResponsibility &MR) override {
78 outs() << "Emitted object defining " << MR.getSymbols() << "\n";
79 return Error::success();
80 }
81
notifyFailed(MaterializationResponsibility & MR)82 Error notifyFailed(MaterializationResponsibility &MR) override {
83 return Error::success();
84 }
85
notifyRemovingResources(JITDylib & JD,ResourceKey K)86 Error notifyRemovingResources(JITDylib &JD, ResourceKey K) override {
87 return Error::success();
88 }
89
notifyTransferringResources(JITDylib & JD,ResourceKey DstKey,ResourceKey SrcKey)90 void notifyTransferringResources(JITDylib &JD, ResourceKey DstKey,
91 ResourceKey SrcKey) override {}
92
93 private:
printBlockContent(jitlink::Block & B)94 static void printBlockContent(jitlink::Block &B) {
95 constexpr JITTargetAddress LineWidth = 16;
96
97 if (B.isZeroFill()) {
98 outs() << " " << formatv("{0:x16}", B.getAddress()) << ": "
99 << B.getSize() << " bytes of zero-fill.\n";
100 return;
101 }
102
103 ExecutorAddr InitAddr(B.getAddress().getValue() & ~(LineWidth - 1));
104 ExecutorAddr StartAddr = B.getAddress();
105 ExecutorAddr EndAddr = B.getAddress() + B.getSize();
106 auto *Data = reinterpret_cast<const uint8_t *>(B.getContent().data());
107
108 for (ExecutorAddr CurAddr = InitAddr; CurAddr != EndAddr; ++CurAddr) {
109 if (CurAddr % LineWidth == 0)
110 outs() << " " << formatv("{0:x16}", CurAddr.getValue())
111 << ": ";
112 if (CurAddr < StartAddr)
113 outs() << " ";
114 else
115 outs() << formatv("{0:x-2}", Data[CurAddr - StartAddr]) << " ";
116 if (CurAddr % LineWidth == LineWidth - 1)
117 outs() << "\n";
118 }
119 if (EndAddr % LineWidth != 0)
120 outs() << "\n";
121 }
122
printGraph(jitlink::LinkGraph & G)123 static Error printGraph(jitlink::LinkGraph &G) {
124
125 DenseSet<jitlink::Block *> BlocksAlreadyVisited;
126
127 outs() << "Graph \"" << G.getName() << "\"\n";
128 // Loop over all sections...
129 for (auto &S : G.sections()) {
130 outs() << " Section " << S.getName() << ":\n";
131
132 // Loop over all symbols in the current section...
133 for (auto *Sym : S.symbols()) {
134
135 // Print the symbol's address.
136 outs() << " " << formatv("{0:x16}", Sym->getAddress()) << ": ";
137
138 // Print the symbol's name, or "<anonymous symbol>" if it doesn't have
139 // one.
140 if (Sym->hasName())
141 outs() << Sym->getName() << "\n";
142 else
143 outs() << "<anonymous symbol>\n";
144
145 // Get the content block for this symbol.
146 auto &B = Sym->getBlock();
147
148 if (BlocksAlreadyVisited.count(&B)) {
149 outs() << " Block " << formatv("{0:x16}", B.getAddress())
150 << " already printed.\n";
151 continue;
152 } else
153 outs() << " Block " << formatv("{0:x16}", B.getAddress())
154 << ":\n";
155
156 outs() << " Content:\n";
157 printBlockContent(B);
158 BlocksAlreadyVisited.insert(&B);
159
160 if (!B.edges().empty()) {
161 outs() << " Edges:\n";
162 for (auto &E : B.edges()) {
163 outs() << " "
164 << formatv("{0:x16}", B.getAddress() + E.getOffset())
165 << ": kind = " << formatv("{0:d}", E.getKind())
166 << ", addend = " << formatv("{0:x}", E.getAddend())
167 << ", target = ";
168 jitlink::Symbol &TargetSym = E.getTarget();
169 if (TargetSym.hasName())
170 outs() << TargetSym.getName() << "\n";
171 else
172 outs() << "<anonymous target>\n";
173 }
174 }
175 outs() << "\n";
176 }
177 }
178 return Error::success();
179 }
180 };
181
182 static cl::opt<std::string>
183 EntryPointName("entry", cl::desc("Symbol to call as main entry point"),
184 cl::init("entry"));
185
186 static cl::list<std::string> InputObjects(cl::Positional,
187 cl::desc("input objects"));
188
main(int argc,char * argv[])189 int main(int argc, char *argv[]) {
190 // Initialize LLVM.
191 InitLLVM X(argc, argv);
192
193 InitializeNativeTarget();
194 InitializeNativeTargetAsmPrinter();
195
196 cl::ParseCommandLineOptions(argc, argv, "LLJITWithObjectLinkingLayerPlugin");
197 ExitOnErr.setBanner(std::string(argv[0]) + ": ");
198
199 // Detect the host and set code model to small.
200 auto JTMB = ExitOnErr(JITTargetMachineBuilder::detectHost());
201 JTMB.setCodeModel(CodeModel::Small);
202
203 // Create an LLJIT instance with an ObjectLinkingLayer as the base layer.
204 // We attach our plugin in to the newly created ObjectLinkingLayer before
205 // returning it.
206 auto J = ExitOnErr(
207 LLJITBuilder()
208 .setJITTargetMachineBuilder(std::move(JTMB))
209 .setObjectLinkingLayerCreator(
210 [&](ExecutionSession &ES, const Triple &TT) {
211 // Create ObjectLinkingLayer.
212 auto ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
213 ES, ExitOnErr(jitlink::InProcessMemoryManager::Create()));
214 // Add an instance of our plugin.
215 ObjLinkingLayer->addPlugin(std::make_unique<MyPlugin>());
216 return ObjLinkingLayer;
217 })
218 .create());
219
220 if (!InputObjects.empty()) {
221 // Load the input objects.
222 for (auto InputObject : InputObjects) {
223 auto ObjBuffer =
224 ExitOnErr(errorOrToExpected(MemoryBuffer::getFile(InputObject)));
225 ExitOnErr(J->addObjectFile(std::move(ObjBuffer)));
226 }
227 } else {
228 auto M = ExitOnErr(parseExampleModule(TestMod, "test-module"));
229 M.withModuleDo([](Module &MP) {
230 outs() << "No input objects specified. Using demo module:\n"
231 << MP << "\n";
232 });
233 ExitOnErr(J->addIRModule(std::move(M)));
234 }
235
236 // Look up the JIT'd function, cast it to a function pointer, then call it.
237 auto EntryAddr = ExitOnErr(J->lookup(EntryPointName));
238 auto *Entry = EntryAddr.toPtr<int()>();
239
240 int Result = Entry();
241 outs() << "---Result---\n"
242 << EntryPointName << "() = " << Result << "\n";
243
244 return 0;
245 }
246