1 //===----- LLJITDumpObjects.cpp - How to dump JIT'd objects with LLJIT ----===//
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 /// \file
10 ///
11 /// This example demonstrates how to use LLJIT to:
12 ///   - Add absolute symbol definitions.
13 ///   - Run static constructors for a JITDylib.
14 ///   - Run static destructors for a JITDylib.
15 ///
16 /// This example does not call any functions (e.g. main or equivalent)  between
17 /// running the static constructors and running the static destructors.
18 ///
19 //===----------------------------------------------------------------------===//
20 
21 #include "llvm/ADT/StringMap.h"
22 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
23 #include "llvm/Support/InitLLVM.h"
24 #include "llvm/Support/TargetSelect.h"
25 #include "llvm/Support/raw_ostream.h"
26 
27 #include "../ExampleModules.h"
28 
29 using namespace llvm;
30 using namespace llvm::orc;
31 
32 ExitOnError ExitOnErr;
33 
34 const llvm::StringRef ModuleWithInitializer =
35     R"(
36 
37   @InitializersRunFlag = external global i32
38   @DeinitializersRunFlag = external global i32
39 
40   declare i32 @__cxa_atexit(void (i8*)*, i8*, i8*)
41   @__dso_handle = external hidden global i8
42 
43   @llvm.global_ctors =
44     appending global [1 x { i32, void ()*, i8* }]
45       [{ i32, void ()*, i8* } { i32 65535, void ()* @init_func, i8* null }]
46 
47   define internal void @init_func() {
48   entry:
49     store i32 1, i32* @InitializersRunFlag
50     %0 = call i32 @__cxa_atexit(void (i8*)* @deinit_func, i8* null,
51                                 i8* @__dso_handle)
52     ret void
53   }
54 
55   define internal void @deinit_func(i8* %0) {
56     store i32 1, i32* @DeinitializersRunFlag
57     ret void
58   }
59 
60 )";
61 
62 int main(int argc, char *argv[]) {
63   // Initialize LLVM.
64   InitLLVM X(argc, argv);
65 
66   InitializeNativeTarget();
67   InitializeNativeTargetAsmPrinter();
68 
69   cl::ParseCommandLineOptions(argc, argv, "LLJITWithInitializers");
70   ExitOnErr.setBanner(std::string(argv[0]) + ": ");
71 
72   auto J = ExitOnErr(LLJITBuilder().create());
73   auto M = ExitOnErr(parseExampleModule(ModuleWithInitializer, "M"));
74 
75   // Load the module.
76   ExitOnErr(J->addIRModule(std::move(M)));
77 
78   int32_t InitializersRunFlag = 0;
79   int32_t DeinitializersRunFlag = 0;
80 
81   ExitOnErr(J->getMainJITDylib().define(absoluteSymbols(
82       {{J->mangleAndIntern("InitializersRunFlag"),
83         JITEvaluatedSymbol::fromPointer(&InitializersRunFlag)},
84        {J->mangleAndIntern("DeinitializersRunFlag"),
85         JITEvaluatedSymbol::fromPointer(&DeinitializersRunFlag)}})));
86 
87   // Run static initializers.
88   ExitOnErr(J->initialize(J->getMainJITDylib()));
89 
90   // Run deinitializers.
91   ExitOnErr(J->deinitialize(J->getMainJITDylib()));
92 
93   outs() << "InitializerRanFlag = " << InitializersRunFlag << "\n"
94          << "DeinitializersRunFlag = " << DeinitializersRunFlag << "\n";
95 
96   return 0;
97 }
98