llc.cpp revision 231057 
1//===-- llc.cpp - Implement the LLVM Native Code Generator ----------------===//
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// This is the llc code generator driver. It provides a convenient
11// command-line interface for generating native assembly-language code
12// or C code, given LLVM bitcode.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/LLVMContext.h"
17#include "llvm/Module.h"
18#include "llvm/PassManager.h"
19#include "llvm/Pass.h"
20#include "llvm/ADT/Triple.h"
21#include "llvm/Support/IRReader.h"
22#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
23#include "llvm/CodeGen/LinkAllCodegenComponents.h"
24#include "llvm/Config/config.h"
25#include "llvm/MC/SubtargetFeature.h"
26#include "llvm/Support/CommandLine.h"
27#include "llvm/Support/Debug.h"
28#include "llvm/Support/FormattedStream.h"
29#include "llvm/Support/ManagedStatic.h"
30#include "llvm/Support/PluginLoader.h"
31#include "llvm/Support/PrettyStackTrace.h"
32#include "llvm/Support/ToolOutputFile.h"
33#include "llvm/Support/Host.h"
34#include "llvm/Support/Signals.h"
35#include "llvm/Support/TargetRegistry.h"
36#include "llvm/Support/TargetSelect.h"
37#include "llvm/Target/TargetData.h"
38#include "llvm/Target/TargetMachine.h"
39#include <memory>
40using namespace llvm;
41
42// General options for llc.  Other pass-specific options are specified
43// within the corresponding llc passes, and target-specific options
44// and back-end code generation options are specified with the target machine.
45//
46static cl::opt<std::string>
47InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
48
49static cl::opt<std::string>
50OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
51
52// Determine optimization level.
53static cl::opt<char>
54OptLevel("O",
55         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
56                  "(default = '-O2')"),
57         cl::Prefix,
58         cl::ZeroOrMore,
59         cl::init(' '));
60
61static cl::opt<std::string>
62TargetTriple("mtriple", cl::desc("Override target triple for module"));
63
64static cl::opt<std::string>
65MArch("march", cl::desc("Architecture to generate code for (see --version)"));
66
67static cl::opt<std::string>
68MCPU("mcpu",
69  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
70  cl::value_desc("cpu-name"),
71  cl::init(""));
72
73static cl::list<std::string>
74MAttrs("mattr",
75  cl::CommaSeparated,
76  cl::desc("Target specific attributes (-mattr=help for details)"),
77  cl::value_desc("a1,+a2,-a3,..."));
78
79static cl::opt<Reloc::Model>
80RelocModel("relocation-model",
81             cl::desc("Choose relocation model"),
82             cl::init(Reloc::Default),
83             cl::values(
84            clEnumValN(Reloc::Default, "default",
85                       "Target default relocation model"),
86            clEnumValN(Reloc::Static, "static",
87                       "Non-relocatable code"),
88            clEnumValN(Reloc::PIC_, "pic",
89                       "Fully relocatable, position independent code"),
90            clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
91                       "Relocatable external references, non-relocatable code"),
92            clEnumValEnd));
93
94static cl::opt<llvm::CodeModel::Model>
95CMModel("code-model",
96        cl::desc("Choose code model"),
97        cl::init(CodeModel::Default),
98        cl::values(clEnumValN(CodeModel::Default, "default",
99                              "Target default code model"),
100                   clEnumValN(CodeModel::Small, "small",
101                              "Small code model"),
102                   clEnumValN(CodeModel::Kernel, "kernel",
103                              "Kernel code model"),
104                   clEnumValN(CodeModel::Medium, "medium",
105                              "Medium code model"),
106                   clEnumValN(CodeModel::Large, "large",
107                              "Large code model"),
108                   clEnumValEnd));
109
110static cl::opt<bool>
111RelaxAll("mc-relax-all",
112  cl::desc("When used with filetype=obj, "
113           "relax all fixups in the emitted object file"));
114
115cl::opt<TargetMachine::CodeGenFileType>
116FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
117  cl::desc("Choose a file type (not all types are supported by all targets):"),
118  cl::values(
119       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
120                  "Emit an assembly ('.s') file"),
121       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
122                  "Emit a native object ('.o') file [experimental]"),
123       clEnumValN(TargetMachine::CGFT_Null, "null",
124                  "Emit nothing, for performance testing"),
125       clEnumValEnd));
126
127cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
128                       cl::desc("Do not verify input module"));
129
130cl::opt<bool> DisableDotLoc("disable-dot-loc", cl::Hidden,
131                            cl::desc("Do not use .loc entries"));
132
133cl::opt<bool> DisableCFI("disable-cfi", cl::Hidden,
134                         cl::desc("Do not use .cfi_* directives"));
135
136static cl::opt<bool>
137DisableRedZone("disable-red-zone",
138  cl::desc("Do not emit code that uses the red zone."),
139  cl::init(false));
140
141// GetFileNameRoot - Helper function to get the basename of a filename.
142static inline std::string
143GetFileNameRoot(const std::string &InputFilename) {
144  std::string IFN = InputFilename;
145  std::string outputFilename;
146  int Len = IFN.length();
147  if ((Len > 2) &&
148      IFN[Len-3] == '.' &&
149      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
150       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
151    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
152  } else {
153    outputFilename = IFN;
154  }
155  return outputFilename;
156}
157
158static tool_output_file *GetOutputStream(const char *TargetName,
159                                         Triple::OSType OS,
160                                         const char *ProgName) {
161  // If we don't yet have an output filename, make one.
162  if (OutputFilename.empty()) {
163    if (InputFilename == "-")
164      OutputFilename = "-";
165    else {
166      OutputFilename = GetFileNameRoot(InputFilename);
167
168      switch (FileType) {
169      default: assert(0 && "Unknown file type");
170      case TargetMachine::CGFT_AssemblyFile:
171        if (TargetName[0] == 'c') {
172          if (TargetName[1] == 0)
173            OutputFilename += ".cbe.c";
174          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
175            OutputFilename += ".cpp";
176          else
177            OutputFilename += ".s";
178        } else
179          OutputFilename += ".s";
180        break;
181      case TargetMachine::CGFT_ObjectFile:
182        if (OS == Triple::Win32)
183          OutputFilename += ".obj";
184        else
185          OutputFilename += ".o";
186        break;
187      case TargetMachine::CGFT_Null:
188        OutputFilename += ".null";
189        break;
190      }
191    }
192  }
193
194  // Decide if we need "binary" output.
195  bool Binary = false;
196  switch (FileType) {
197  default: assert(0 && "Unknown file type");
198  case TargetMachine::CGFT_AssemblyFile:
199    break;
200  case TargetMachine::CGFT_ObjectFile:
201  case TargetMachine::CGFT_Null:
202    Binary = true;
203    break;
204  }
205
206  // Open the file.
207  std::string error;
208  unsigned OpenFlags = 0;
209  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
210  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
211                                                 OpenFlags);
212  if (!error.empty()) {
213    errs() << error << '\n';
214    delete FDOut;
215    return 0;
216  }
217
218  return FDOut;
219}
220
221// main - Entry point for the llc compiler.
222//
223int main(int argc, char **argv) {
224  sys::PrintStackTraceOnErrorSignal();
225  PrettyStackTraceProgram X(argc, argv);
226
227  // Enable debug stream buffering.
228  EnableDebugBuffering = true;
229
230  LLVMContext &Context = getGlobalContext();
231  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
232
233  // Initialize targets first, so that --version shows registered targets.
234  InitializeAllTargets();
235  InitializeAllTargetMCs();
236  InitializeAllAsmPrinters();
237  InitializeAllAsmParsers();
238
239  // Register the target printer for --version.
240  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
241
242  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
243
244  // Load the module to be compiled...
245  SMDiagnostic Err;
246  std::auto_ptr<Module> M;
247
248  M.reset(ParseIRFile(InputFilename, Err, Context));
249  if (M.get() == 0) {
250    Err.Print(argv[0], errs());
251    return 1;
252  }
253  Module &mod = *M.get();
254
255  // If we are supposed to override the target triple, do so now.
256  if (!TargetTriple.empty())
257    mod.setTargetTriple(Triple::normalize(TargetTriple));
258
259  Triple TheTriple(mod.getTargetTriple());
260  if (TheTriple.getTriple().empty())
261    TheTriple.setTriple(sys::getHostTriple());
262
263  // Allocate target machine.  First, check whether the user has explicitly
264  // specified an architecture to compile for. If so we have to look it up by
265  // name, because it might be a backend that has no mapping to a target triple.
266  const Target *TheTarget = 0;
267  if (!MArch.empty()) {
268    for (TargetRegistry::iterator it = TargetRegistry::begin(),
269           ie = TargetRegistry::end(); it != ie; ++it) {
270      if (MArch == it->getName()) {
271        TheTarget = &*it;
272        break;
273      }
274    }
275
276    if (!TheTarget) {
277      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
278      return 1;
279    }
280
281    // Adjust the triple to match (if known), otherwise stick with the
282    // module/host triple.
283    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
284    if (Type != Triple::UnknownArch)
285      TheTriple.setArch(Type);
286  } else {
287    std::string Err;
288    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
289    if (TheTarget == 0) {
290      errs() << argv[0] << ": error auto-selecting target for module '"
291             << Err << "'.  Please use the -march option to explicitly "
292             << "pick a target.\n";
293      return 1;
294    }
295  }
296
297  // Package up features to be passed to target/subtarget
298  std::string FeaturesStr;
299  if (MAttrs.size()) {
300    SubtargetFeatures Features;
301    for (unsigned i = 0; i != MAttrs.size(); ++i)
302      Features.AddFeature(MAttrs[i]);
303    FeaturesStr = Features.getString();
304  }
305
306  std::auto_ptr<TargetMachine>
307    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
308                                          MCPU, FeaturesStr,
309                                          RelocModel, CMModel));
310  assert(target.get() && "Could not allocate target machine!");
311  TargetMachine &Target = *target.get();
312
313  if (DisableDotLoc)
314    Target.setMCUseLoc(false);
315
316  if (DisableCFI)
317    Target.setMCUseCFI(false);
318
319  // Disable .loc support for older OS X versions.
320  if (TheTriple.isMacOSX() &&
321      TheTriple.isMacOSXVersionLT(10, 6))
322    Target.setMCUseLoc(false);
323
324  // Figure out where we are going to send the output...
325  OwningPtr<tool_output_file> Out
326    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
327  if (!Out) return 1;
328
329  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
330  switch (OptLevel) {
331  default:
332    errs() << argv[0] << ": invalid optimization level.\n";
333    return 1;
334  case ' ': break;
335  case '0': OLvl = CodeGenOpt::None; break;
336  case '1': OLvl = CodeGenOpt::Less; break;
337  case '2': OLvl = CodeGenOpt::Default; break;
338  case '3': OLvl = CodeGenOpt::Aggressive; break;
339  }
340
341  // Build up all of the passes that we want to do to the module.
342  PassManager PM;
343
344  // Add the target data from the target machine, if it exists, or the module.
345  if (const TargetData *TD = Target.getTargetData())
346    PM.add(new TargetData(*TD));
347  else
348    PM.add(new TargetData(&mod));
349
350  // Override default to generate verbose assembly.
351  Target.setAsmVerbosityDefault(true);
352
353  if (RelaxAll) {
354    if (FileType != TargetMachine::CGFT_ObjectFile)
355      errs() << argv[0]
356             << ": warning: ignoring -mc-relax-all because filetype != obj";
357    else
358      Target.setMCRelaxAll(true);
359  }
360
361  {
362    formatted_raw_ostream FOS(Out->os());
363
364    // Ask the target to add backend passes as necessary.
365    if (Target.addPassesToEmitFile(PM, FOS, FileType, OLvl, NoVerify)) {
366      errs() << argv[0] << ": target does not support generation of this"
367             << " file type!\n";
368      return 1;
369    }
370
371    // Before executing passes, print the final values of the LLVM options.
372    cl::PrintOptionValues();
373
374    PM.run(mod);
375  }
376
377  // Declare success.
378  Out->keep();
379
380  return 0;
381}
382