llvm/examples/OrcV2Examples/LLJITWithInitializers/LLJITWithInitializers.cpp

   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(
  82       absoluteSymbols({{J->mangleAndIntern("InitializersRunFlag"),
  83                         {ExecutorAddr::fromPtr(&InitializersRunFlag),
  84                          JITSymbolFlags::Exported}},
  85                        {J->mangleAndIntern("DeinitializersRunFlag"),
  86                         {ExecutorAddr::fromPtr(&DeinitializersRunFlag),
  87                          JITSymbolFlags::Exported}}})));
  88
  89   // Run static initializers.
  90   ExitOnErr(J->initialize(J->getMainJITDylib()));
  91
  92   // Run deinitializers.
  93   ExitOnErr(J->deinitialize(J->getMainJITDylib()));
  94
  95   outs() << "InitializerRanFlag = " << InitializersRunFlag << "\n"
  96          << "DeinitializersRunFlag = " << DeinitializersRunFlag << "\n";
  97
  98   return 0;
  99 }