From b14fce113fa45da85c8c3528552ae446ced340ca Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Sat, 5 Nov 2022 23:24:05 +0100
Subject: llvm: small ORCv2 jit example

---
 content/2022-07-07-llvm-orc-jit/jit.h | 100 ++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 content/2022-07-07-llvm-orc-jit/jit.h

(limited to 'content/2022-07-07-llvm-orc-jit/jit.h')

diff --git a/content/2022-07-07-llvm-orc-jit/jit.h b/content/2022-07-07-llvm-orc-jit/jit.h
new file mode 100644
index 0000000..10d6d4a
--- /dev/null
+++ b/content/2022-07-07-llvm-orc-jit/jit.h
@@ -0,0 +1,100 @@
+#ifndef JIT_H
+#define JIT_H
+
+#include <llvm/ExecutionEngine/JITSymbol.h>
+#include <llvm/ExecutionEngine/Orc/CompileUtils.h>
+#include <llvm/ExecutionEngine/Orc/Core.h>
+#include <llvm/ExecutionEngine/Orc/ExecutionUtils.h>
+#include <llvm/ExecutionEngine/Orc/ExecutorProcessControl.h>
+#include <llvm/ExecutionEngine/Orc/IRCompileLayer.h>
+#include <llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h>
+#include <llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h>
+#include <llvm/ExecutionEngine/SectionMemoryManager.h>
+#include <llvm/IR/DataLayout.h>
+#include <llvm/IR/LLVMContext.h>
+
+namespace jit {
+
+using llvm::DataLayout;
+using llvm::Expected;
+using llvm::JITEvaluatedSymbol;
+using llvm::SectionMemoryManager;
+using llvm::StringRef;
+
+using llvm::orc::ConcurrentIRCompiler;
+// using llvm::orc::DynamicLibrarySearchGenerator;
+using llvm::orc::ExecutionSession;
+using llvm::orc::IRCompileLayer;
+using llvm::orc::JITDylib;
+using llvm::orc::JITTargetMachineBuilder;
+using llvm::orc::MangleAndInterner;
+using llvm::orc::ResourceTrackerSP;
+using llvm::orc::RTDyldObjectLinkingLayer;
+using llvm::orc::SelfExecutorProcessControl;
+using llvm::orc::ThreadSafeModule;
+
+// Simple JIT engine based on the KaleidoscopeJIT.
+// https://www.llvm.org/docs/tutorial/BuildingAJIT1.html
+class Jit {
+private:
+  std::unique_ptr<ExecutionSession> ES;
+
+  DataLayout DL;
+  MangleAndInterner Mangle;
+
+  RTDyldObjectLinkingLayer ObjectLayer;
+  IRCompileLayer CompileLayer;
+
+  JITDylib &JD;
+
+public:
+  Jit(std::unique_ptr<ExecutionSession> ES, JITTargetMachineBuilder JTMB,
+      DataLayout DL)
+      : ES(std::move(ES)), DL(std::move(DL)), Mangle(*this->ES, this->DL),
+        ObjectLayer(*this->ES,
+                    []() { return std::make_unique<SectionMemoryManager>(); }),
+        CompileLayer(*this->ES, ObjectLayer,
+                     std::make_unique<ConcurrentIRCompiler>(std::move(JTMB))),
+        JD(this->ES->createBareJITDylib("main")) {
+    // https://www.llvm.org/docs/ORCv2.html#how-to-add-process-and-library-symbols-to-jitdylibs
+    // JD.addGenerator(
+    //     cantFail(DynamicLibrarySearchGenerator::GetForCurrentProcess(
+    //         DL.getGlobalPrefix())));
+    (void)JD.define(llvm::orc::absoluteSymbols(
+        {{Mangle("libc_puts"), llvm::JITEvaluatedSymbol::fromPointer(&puts)}}));
+  }
+
+  ~Jit() {
+    if (auto Err = ES->endSession())
+      ES->reportError(std::move(Err));
+  }
+
+  static std::unique_ptr<Jit> Create() {
+    auto EPC = cantFail(SelfExecutorProcessControl::Create());
+    auto ES = std::make_unique<ExecutionSession>(std::move(EPC));
+
+    JITTargetMachineBuilder JTMB(
+        ES->getExecutorProcessControl().getTargetTriple());
+
+    auto DL = cantFail(JTMB.getDefaultDataLayoutForTarget());
+
+    return std::make_unique<Jit>(std::move(ES), std::move(JTMB), std::move(DL));
+  }
+
+  // Error addModule(ThreadSafeModule TSM) {
+  Expected<ResourceTrackerSP> addModule(ThreadSafeModule TSM) {
+    auto RT = JD.createResourceTracker();
+    if (auto E = CompileLayer.add(RT, std::move(TSM))) {
+      return E;
+    }
+    return RT;
+  }
+
+  Expected<JITEvaluatedSymbol> lookup(StringRef Name) {
+    return ES->lookup({&JD}, Mangle(Name.str()));
+  }
+};
+
+} // namespace jit
+
+#endif
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