1//===-- examples/clang-interpreter/main.cpp - Clang C Interpreter Example -===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "clang/CodeGen/CodeGenAction.h"
11#include "clang/Basic/DiagnosticOptions.h"
12#include "clang/Driver/Compilation.h"
13#include "clang/Driver/Driver.h"
14#include "clang/Driver/Tool.h"
15#include "clang/Frontend/CompilerInstance.h"
16#include "clang/Frontend/CompilerInvocation.h"
17#include "clang/Frontend/FrontendDiagnostic.h"
18#include "clang/Frontend/TextDiagnosticPrinter.h"
19#include "llvm/ADT/SmallString.h"
20#include "llvm/ExecutionEngine/ExecutionEngine.h"
21#include "llvm/ExecutionEngine/MCJIT.h"
22#include "llvm/IR/Module.h"
23#include "llvm/Support/FileSystem.h"
24#include "llvm/Support/Host.h"
25#include "llvm/Support/ManagedStatic.h"
26#include "llvm/Support/Path.h"
27#include "llvm/Support/TargetSelect.h"
28#include "llvm/Support/raw_ostream.h"
29#include <memory>
30using namespace clang;
31using namespace clang::driver;
32
33// This function isn't referenced outside its translation unit, but it
34// can't use the "static" keyword because its address is used for
35// GetMainExecutable (since some platforms don't support taking the
36// address of main, and some platforms can't implement GetMainExecutable
37// without being given the address of a function in the main executable).
38std::string GetExecutablePath(const char *Argv0) {
39  // This just needs to be some symbol in the binary; C++ doesn't
40  // allow taking the address of ::main however.
41  void *MainAddr = (void*) (intptr_t) GetExecutablePath;
42  return llvm::sys::fs::getMainExecutable(Argv0, MainAddr);
43}
44
45static llvm::ExecutionEngine *
46createExecutionEngine(std::unique_ptr<llvm::Module> M, std::string *ErrorStr) {
47  return llvm::EngineBuilder(std::move(M))
48      .setEngineKind(llvm::EngineKind::Either)
49      .setErrorStr(ErrorStr)
50      .create();
51}
52
53static int Execute(std::unique_ptr<llvm::Module> Mod, char *const *envp) {
54  llvm::InitializeNativeTarget();
55  llvm::InitializeNativeTargetAsmPrinter();
56
57  llvm::Module &M = *Mod;
58  std::string Error;
59  std::unique_ptr<llvm::ExecutionEngine> EE(
60      createExecutionEngine(std::move(Mod), &Error));
61  if (!EE) {
62    llvm::errs() << "unable to make execution engine: " << Error << "\n";
63    return 255;
64  }
65
66  llvm::Function *EntryFn = M.getFunction("main");
67  if (!EntryFn) {
68    llvm::errs() << "'main' function not found in module.\n";
69    return 255;
70  }
71
72  // FIXME: Support passing arguments.
73  std::vector<std::string> Args;
74  Args.push_back(M.getModuleIdentifier());
75
76  EE->finalizeObject();
77  return EE->runFunctionAsMain(EntryFn, Args, envp);
78}
79
80int main(int argc, const char **argv, char * const *envp) {
81  void *MainAddr = (void*) (intptr_t) GetExecutablePath;
82  std::string Path = GetExecutablePath(argv[0]);
83  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
84  TextDiagnosticPrinter *DiagClient =
85    new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
86
87  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
88  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
89
90  // Use ELF on windows for now.
91  std::string TripleStr = llvm::sys::getProcessTriple();
92  llvm::Triple T(TripleStr);
93  if (T.isOSBinFormatCOFF())
94    T.setObjectFormat(llvm::Triple::ELF);
95
96  Driver TheDriver(Path, T.str(), Diags);
97  TheDriver.setTitle("clang interpreter");
98  TheDriver.setCheckInputsExist(false);
99
100  // FIXME: This is a hack to try to force the driver to do something we can
101  // recognize. We need to extend the driver library to support this use model
102  // (basically, exactly one input, and the operation mode is hard wired).
103  SmallVector<const char *, 16> Args(argv, argv + argc);
104  Args.push_back("-fsyntax-only");
105  std::unique_ptr<Compilation> C(TheDriver.BuildCompilation(Args));
106  if (!C)
107    return 0;
108
109  // FIXME: This is copied from ASTUnit.cpp; simplify and eliminate.
110
111  // We expect to get back exactly one command job, if we didn't something
112  // failed. Extract that job from the compilation.
113  const driver::JobList &Jobs = C->getJobs();
114  if (Jobs.size() != 1 || !isa<driver::Command>(*Jobs.begin())) {
115    SmallString<256> Msg;
116    llvm::raw_svector_ostream OS(Msg);
117    Jobs.Print(OS, "; ", true);
118    Diags.Report(diag::err_fe_expected_compiler_job) << OS.str();
119    return 1;
120  }
121
122  const driver::Command &Cmd = cast<driver::Command>(*Jobs.begin());
123  if (llvm::StringRef(Cmd.getCreator().getName()) != "clang") {
124    Diags.Report(diag::err_fe_expected_clang_command);
125    return 1;
126  }
127
128  // Initialize a compiler invocation object from the clang (-cc1) arguments.
129  const driver::ArgStringList &CCArgs = Cmd.getArguments();
130  std::unique_ptr<CompilerInvocation> CI(new CompilerInvocation);
131  CompilerInvocation::CreateFromArgs(*CI,
132                                     const_cast<const char **>(CCArgs.data()),
133                                     const_cast<const char **>(CCArgs.data()) +
134                                       CCArgs.size(),
135                                     Diags);
136
137  // Show the invocation, with -v.
138  if (CI->getHeaderSearchOpts().Verbose) {
139    llvm::errs() << "clang invocation:\n";
140    Jobs.Print(llvm::errs(), "\n", true);
141    llvm::errs() << "\n";
142  }
143
144  // FIXME: This is copied from cc1_main.cpp; simplify and eliminate.
145
146  // Create a compiler instance to handle the actual work.
147  CompilerInstance Clang;
148  Clang.setInvocation(CI.release());
149
150  // Create the compilers actual diagnostics engine.
151  Clang.createDiagnostics();
152  if (!Clang.hasDiagnostics())
153    return 1;
154
155  // Infer the builtin include path if unspecified.
156  if (Clang.getHeaderSearchOpts().UseBuiltinIncludes &&
157      Clang.getHeaderSearchOpts().ResourceDir.empty())
158    Clang.getHeaderSearchOpts().ResourceDir =
159      CompilerInvocation::GetResourcesPath(argv[0], MainAddr);
160
161  // Create and execute the frontend to generate an LLVM bitcode module.
162  std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction());
163  if (!Clang.ExecuteAction(*Act))
164    return 1;
165
166  int Res = 255;
167  if (std::unique_ptr<llvm::Module> Module = Act->takeModule())
168    Res = Execute(std::move(Module), envp);
169
170  // Shutdown.
171
172  llvm::llvm_shutdown();
173
174  return Res;
175}
176