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//===-- examples/clang-interpreter/main.cpp - Clang C Interpreter Example -===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
#include "clang/CodeGen/CodeGenAction.h"
#include "clang/Basic/DiagnosticOptions.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/MCJIT.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 <memory>
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) {
// 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;
return llvm::sys::fs::getMainExecutable(Argv0, MainAddr);
static llvm::ExecutionEngine *
createExecutionEngine(std::unique_ptr<llvm::Module> M, std::string *ErrorStr) {
return llvm::EngineBuilder(std::move(M))
static int Execute(std::unique_ptr<llvm::Module> Mod, char *const *envp) {
llvm::Module &M = *Mod;
std::string Error;
std::unique_ptr<llvm::ExecutionEngine> EE(
createExecutionEngine(std::move(Mod), &Error));
if (!EE) {
llvm::errs() << "unable to make execution engine: " << Error << "\n";
return 255;
llvm::Function *EntryFn = M.getFunction("main");
if (!EntryFn) {
llvm::errs() << "'main' function not found in module.\n";
return 255;
// FIXME: Support passing arguments.
std::vector<std::string> Args;
return EE->runFunctionAsMain(EntryFn, Args, envp);
int main(int argc, const char **argv, char * const *envp) {
void *MainAddr = (void*) (intptr_t) GetExecutablePath;
std::string Path = GetExecutablePath(argv[0]);
IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
TextDiagnosticPrinter *DiagClient =
new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
// Use ELF on windows for now.
std::string TripleStr = llvm::sys::getProcessTriple();
llvm::Triple T(TripleStr);
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 driver::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;
if (std::unique_ptr<llvm::Module> Module = Act->takeModule())
Res = Execute(std::move(Module), envp);
// Shutdown.
return Res;