[examples] Rename LLJITWithJITLink to LLJITWithCustomObjectLinkingLayer.

LLJIT now uses JITLink/ObjectLinkingLayer by default where available, so
these steps aren't required to use it. The tutorial is still useful though:
Clients can use it to test altervative linking layer implementations (e.g.
handing off to the system linker) or to test implementations of JITLink that
are still under development.

1 files changed, 66 insertions, 0 deletions

diff --git a/llvm/examples/LLJITExamples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp b/llvm/examples/LLJITExamples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp
new file mode 100644
index 00000000000..04607d743ad
--- /dev/null
+++ b/llvm/examples/LLJITExamples/LLJITWithCustomObjectLinkingLayer/LLJITWithCustomObjectLinkingLayer.cpp
@@ -0,0 +1,66 @@
+//===--------------- LLJITWithCustomObjectLinkingLayer.cpp ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file shows how to switch LLJIT to use a custom object linking layer (we
+// use ObjectLinkingLayer, which is backed by JITLink, as an example).
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
+#include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "../ExampleModules.h"
+
+using namespace llvm;
+using namespace llvm::orc;
+
+ExitOnError ExitOnErr;
+
+int main(int argc, char *argv[]) {
+  // Initialize LLVM.
+  InitLLVM X(argc, argv);
+
+  InitializeNativeTarget();
+  InitializeNativeTargetAsmPrinter();
+
+  cl::ParseCommandLineOptions(argc, argv, "HowToUseLLJIT");
+  ExitOnErr.setBanner(std::string(argv[0]) + ": ");
+
+  // Detect the host and set code model to small.
+  auto JTMB = ExitOnErr(JITTargetMachineBuilder::detectHost());
+  JTMB.setCodeModel(CodeModel::Small);
+
+  // Create an LLJIT instance with an ObjectLinkingLayer as the base layer.
+  auto J = ExitOnErr(
+      LLJITBuilder()
+          .setJITTargetMachineBuilder(std::move(JTMB))
+          .setObjectLinkingLayerCreator(
+              [&](ExecutionSession &ES, const Triple &TT) {
+                return std::make_unique<ObjectLinkingLayer>(
+                    ES, std::make_unique<jitlink::InProcessMemoryManager>());
+              })
+          .create());
+
+  auto M = ExitOnErr(parseExampleModule(Add1Example, "add1"));
+
+  ExitOnErr(J->addIRModule(std::move(M)));
+
+  // Look up the JIT'd function, cast it to a function pointer, then call it.
+  auto Add1Sym = ExitOnErr(J->lookup("add1"));
+  int (*Add1)(int) = (int (*)(int))Add1Sym.getAddress();
+
+  int Result = Add1(42);
+  outs() << "add1(42) = " << Result << "\n";
+
+  return 0;
+}