examples/LLJITExamples/LLJITWithJITLink/LLJITWithJITLink.cpp

   1 //===-- LLJITWithJITLink.cpp - Configure LLJIT to use ObjectLinkingLayer --===//
   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 ObjectLinkingLayer (which is
  10 // backed by JITLink) rather than RTDyldObjectLinkingLayer (which is backed by
  11 // RuntimeDyld). Using JITLink as the underlying allocator enables use of
  12 // small code model in JIT'd code.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/ADT/StringMap.h"
  17 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.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 int main(int argc, char *argv[]) {
  32   // Initialize LLVM.
  33   InitLLVM X(argc, argv);
  34
  35   InitializeNativeTarget();
  36   InitializeNativeTargetAsmPrinter();
  37
  38   cl::ParseCommandLineOptions(argc, argv, "HowToUseLLJIT");
  39   ExitOnErr.setBanner(std::string(argv[0]) + ": ");
  40
  41   // Define an in-process JITLink memory manager.
  42   jitlink::InProcessMemoryManager MemMgr;
  43
  44   // Detect the host and set code model to small.
  45   auto JTMB = ExitOnErr(JITTargetMachineBuilder::detectHost());
  46   JTMB.setCodeModel(CodeModel::Small);
  47
  48   // Create an LLJIT instance with an ObjectLinkingLayer as the base layer.
  49   auto J =
  50       ExitOnErr(LLJITBuilder()
  51                     .setJITTargetMachineBuilder(std::move(JTMB))
  52                     .setObjectLinkingLayerCreator([&](ExecutionSession &ES,
  53                                                       const Triple &TT) {
  54                       return std::make_unique<ObjectLinkingLayer>(ES, MemMgr);
  55                     })
  56                     .create());
  57
  58   auto M = ExitOnErr(parseExampleModule(Add1Example, "add1"));
  59
  60   ExitOnErr(J->addIRModule(std::move(M)));
  61
  62   // Look up the JIT'd function, cast it to a function pointer, then call it.
  63   auto Add1Sym = ExitOnErr(J->lookup("add1"));
  64   int (*Add1)(int) = (int (*)(int))Add1Sym.getAddress();
  65
  66   int Result = Add1(42);
  67   outs() << "add1(42) = " << Result << "\n";
  68
  69   return 0;
  70 }