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//===-- examples/clang-interpreter/main.cpp - Clang C Interpreter Example -===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "clang/Basic/DiagnosticOptions.h"
#include "clang/CodeGen/CodeGenAction.h"
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/Tool.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/CompilerInvocation.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/Frontend/TextDiagnosticPrinter.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
#include "llvm/ExecutionEngine/SectionMemoryManager.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
using namespace clang;
using namespace clang::driver;
// This function isn't referenced outside its translation unit, but it
// can't use the "static" keyword because its address is used for
// GetMainExecutable (since some platforms don't support taking the
// address of main, and some platforms can't implement GetMainExecutable
// without being given the address of a function in the main executable).
std::string GetExecutablePath(const char *Argv0, void *MainAddr) {
return llvm::sys::fs::getMainExecutable(Argv0, MainAddr);
namespace llvm {
namespace orc {
class SimpleJIT {
ExecutionSession ES;
std::shared_ptr<SymbolResolver> Resolver;
std::unique_ptr<TargetMachine> TM;
const DataLayout DL;
LegacyRTDyldObjectLinkingLayer ObjectLayer;
LegacyIRCompileLayer<decltype(ObjectLayer), SimpleCompiler> CompileLayer;
: Resolver(createLegacyLookupResolver(
[this](const std::string &Name) -> JITSymbol {
if (auto Sym = CompileLayer.findSymbol(Name, false))
return Sym;
else if (auto Err = Sym.takeError())
return std::move(Err);
if (auto SymAddr =
return JITSymbol(SymAddr, JITSymbolFlags::Exported);
return nullptr;
[](Error Err) { cantFail(std::move(Err), "lookupFlags failed"); })),
TM(EngineBuilder().selectTarget()), DL(TM->createDataLayout()),
[this](VModuleKey) {
return LegacyRTDyldObjectLinkingLayer::Resources{
std::make_shared<SectionMemoryManager>(), Resolver};
CompileLayer(ObjectLayer, SimpleCompiler(*TM)) {
const TargetMachine &getTargetMachine() const { return *TM; }
VModuleKey addModule(std::unique_ptr<Module> M) {
// Add the module to the JIT with a new VModuleKey.
auto K = ES.allocateVModule();
cantFail(CompileLayer.addModule(K, std::move(M)));
return K;
JITSymbol findSymbol(const StringRef &Name) {
std::string MangledName;
raw_string_ostream MangledNameStream(MangledName);
Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
return CompileLayer.findSymbol(MangledNameStream.str(), true);
JITTargetAddress getSymbolAddress(const StringRef &Name) {
return cantFail(findSymbol(Name).getAddress());
void removeModule(VModuleKey K) {
} // end namespace orc
} // end namespace llvm
int main(int argc, const char **argv) {
// This just needs to be some symbol in the binary; C++ doesn't
// allow taking the address of ::main however.
void *MainAddr = (void*) (intptr_t) GetExecutablePath;
std::string Path = GetExecutablePath(argv[0], MainAddr);
IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
TextDiagnosticPrinter *DiagClient =
new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
const std::string TripleStr = llvm::sys::getProcessTriple();
llvm::Triple T(TripleStr);
// Use ELF on Windows-32 and MingW for now.
if (T.isOSBinFormatCOFF())
Driver TheDriver(Path, T.str(), Diags);
TheDriver.setTitle("clang interpreter");
// FIXME: This is a hack to try to force the driver to do something we can
// recognize. We need to extend the driver library to support this use model
// (basically, exactly one input, and the operation mode is hard wired).
SmallVector<const char *, 16> Args(argv, argv + argc);
std::unique_ptr<Compilation> C(TheDriver.BuildCompilation(Args));
if (!C)
return 0;
// FIXME: This is copied from ASTUnit.cpp; simplify and eliminate.
// We expect to get back exactly one command job, if we didn't something
// failed. Extract that job from the compilation.
const driver::JobList &Jobs = C->getJobs();
if (Jobs.size() != 1 || !isa<driver::Command>(*Jobs.begin())) {
SmallString<256> Msg;
llvm::raw_svector_ostream OS(Msg);
Jobs.Print(OS, "; ", true);
Diags.Report(diag::err_fe_expected_compiler_job) << OS.str();
return 1;
const driver::Command &Cmd = cast<driver::Command>(*Jobs.begin());
if (llvm::StringRef(Cmd.getCreator().getName()) != "clang") {
return 1;
// Initialize a compiler invocation object from the clang (-cc1) arguments.
const llvm::opt::ArgStringList &CCArgs = Cmd.getArguments();
std::unique_ptr<CompilerInvocation> CI(new CompilerInvocation);
const_cast<const char **>(,
const_cast<const char **>( +
// Show the invocation, with -v.
if (CI->getHeaderSearchOpts().Verbose) {
llvm::errs() << "clang invocation:\n";
Jobs.Print(llvm::errs(), "\n", true);
llvm::errs() << "\n";
// FIXME: This is copied from cc1_main.cpp; simplify and eliminate.
// Create a compiler instance to handle the actual work.
CompilerInstance Clang;
// Create the compilers actual diagnostics engine.
if (!Clang.hasDiagnostics())
return 1;
// Infer the builtin include path if unspecified.
if (Clang.getHeaderSearchOpts().UseBuiltinIncludes &&
Clang.getHeaderSearchOpts().ResourceDir =
CompilerInvocation::GetResourcesPath(argv[0], MainAddr);
// Create and execute the frontend to generate an LLVM bitcode module.
std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction());
if (!Clang.ExecuteAction(*Act))
return 1;
int Res = 255;
std::unique_ptr<llvm::Module> Module = Act->takeModule();
if (Module) {
llvm::orc::SimpleJIT J;
auto H = J.addModule(std::move(Module));
auto Main = (int(*)(...))J.getSymbolAddress("main");
Res = Main();
// Shutdown.
return Res;