llc.cpp revision f0356fe140af1a30587b9a86bcfb1b2c51b8ce20 
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/Analysis/Verifier.h"
22#include "llvm/Support/IRReader.h"
23#include "llvm/CodeGen/FileWriters.h"
24#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
25#include "llvm/CodeGen/LinkAllCodegenComponents.h"
26#include "llvm/CodeGen/ObjectCodeEmitter.h"
27#include "llvm/Config/config.h"
28#include "llvm/LinkAllVMCore.h"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Support/Debug.h"
31#include "llvm/Support/FileUtilities.h"
32#include "llvm/Support/FormattedStream.h"
33#include "llvm/Support/ManagedStatic.h"
34#include "llvm/Support/MemoryBuffer.h"
35#include "llvm/Support/PluginLoader.h"
36#include "llvm/Support/PrettyStackTrace.h"
37#include "llvm/System/Host.h"
38#include "llvm/System/Signals.h"
39#include "llvm/Target/SubtargetFeature.h"
40#include "llvm/Target/TargetData.h"
41#include "llvm/Target/TargetMachine.h"
42#include "llvm/Target/TargetRegistry.h"
43#include "llvm/Target/TargetSelect.h"
44#include "llvm/Transforms/Scalar.h"
45#include <memory>
46using namespace llvm;
47
48// General options for llc.  Other pass-specific options are specified
49// within the corresponding llc passes, and target-specific options
50// and back-end code generation options are specified with the target machine.
51//
52static cl::opt<std::string>
53InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
54
55static cl::opt<std::string>
56OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
57
58static cl::opt<bool>
59Force("f", cl::desc("Enable binary output on terminals"));
60
61// Determine optimization level.
62static cl::opt<char>
63OptLevel("O",
64         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
65                  "(default = '-O2')"),
66         cl::Prefix,
67         cl::ZeroOrMore,
68         cl::init(' '));
69
70static cl::opt<std::string>
71TargetTriple("mtriple", cl::desc("Override target triple for module"));
72
73static cl::opt<std::string>
74MArch("march", cl::desc("Architecture to generate code for (see --version)"));
75
76static cl::opt<std::string>
77MCPU("mcpu",
78  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
79  cl::value_desc("cpu-name"),
80  cl::init(""));
81
82static cl::list<std::string>
83MAttrs("mattr",
84  cl::CommaSeparated,
85  cl::desc("Target specific attributes (-mattr=help for details)"),
86  cl::value_desc("a1,+a2,-a3,..."));
87
88cl::opt<TargetMachine::CodeGenFileType>
89FileType("filetype", cl::init(TargetMachine::AssemblyFile),
90  cl::desc("Choose a file type (not all types are supported by all targets):"),
91  cl::values(
92       clEnumValN(TargetMachine::AssemblyFile, "asm",
93                  "Emit an assembly ('.s') file"),
94       clEnumValN(TargetMachine::ObjectFile, "obj",
95                  "Emit a native object ('.o') file [experimental]"),
96       clEnumValN(TargetMachine::DynamicLibrary, "dynlib",
97                  "Emit a native dynamic library ('.so') file"
98                  " [experimental]"),
99       clEnumValEnd));
100
101cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
102                       cl::desc("Do not verify input module"));
103
104
105static cl::opt<bool>
106DisableRedZone("disable-red-zone",
107  cl::desc("Do not emit code that uses the red zone."),
108  cl::init(false));
109
110static cl::opt<bool>
111NoImplicitFloats("no-implicit-float",
112  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
113  cl::init(false));
114
115// GetFileNameRoot - Helper function to get the basename of a filename.
116static inline std::string
117GetFileNameRoot(const std::string &InputFilename) {
118  std::string IFN = InputFilename;
119  std::string outputFilename;
120  int Len = IFN.length();
121  if ((Len > 2) &&
122      IFN[Len-3] == '.' &&
123      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
124       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
125    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
126  } else {
127    outputFilename = IFN;
128  }
129  return outputFilename;
130}
131
132static formatted_raw_ostream *GetOutputStream(const char *TargetName,
133                                              const char *ProgName) {
134  if (OutputFilename != "") {
135    if (OutputFilename == "-")
136      return &fouts();
137
138    // Make sure that the Out file gets unlinked from the disk if we get a
139    // SIGINT
140    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
141
142    std::string error;
143    raw_fd_ostream *FDOut =
144      new raw_fd_ostream(OutputFilename.c_str(), error,
145                         raw_fd_ostream::F_Binary);
146    if (!error.empty()) {
147      errs() << error << '\n';
148      delete FDOut;
149      return 0;
150    }
151    formatted_raw_ostream *Out =
152      new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
153
154    return Out;
155  }
156
157  if (InputFilename == "-") {
158    OutputFilename = "-";
159    return &fouts();
160  }
161
162  OutputFilename = GetFileNameRoot(InputFilename);
163
164  bool Binary = false;
165  switch (FileType) {
166  case TargetMachine::AssemblyFile:
167    if (TargetName[0] == 'c') {
168      if (TargetName[1] == 0)
169        OutputFilename += ".cbe.c";
170      else if (TargetName[1] == 'p' && TargetName[2] == 'p')
171        OutputFilename += ".cpp";
172      else
173        OutputFilename += ".s";
174    } else
175      OutputFilename += ".s";
176    break;
177  case TargetMachine::ObjectFile:
178    OutputFilename += ".o";
179    Binary = true;
180    break;
181  case TargetMachine::DynamicLibrary:
182    OutputFilename += LTDL_SHLIB_EXT;
183    Binary = true;
184    break;
185  }
186
187  // Make sure that the Out file gets unlinked from the disk if we get a
188  // SIGINT
189  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
190
191  std::string error;
192  unsigned OpenFlags = 0;
193  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
194  raw_fd_ostream *FDOut = new raw_fd_ostream(OutputFilename.c_str(), error,
195                                             OpenFlags);
196  if (!error.empty()) {
197    errs() << error << '\n';
198    delete FDOut;
199    return 0;
200  }
201
202  formatted_raw_ostream *Out =
203    new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
204
205  return Out;
206}
207
208// main - Entry point for the llc compiler.
209//
210int main(int argc, char **argv) {
211  sys::PrintStackTraceOnErrorSignal();
212  PrettyStackTraceProgram X(argc, argv);
213
214  // Enable debug stream buffering.
215  EnableDebugBuffering = true;
216
217  LLVMContext &Context = getGlobalContext();
218  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
219
220  // Initialize targets first, so that --version shows registered targets.
221  InitializeAllTargets();
222  InitializeAllAsmPrinters();
223
224  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
225
226  // Load the module to be compiled...
227  SMDiagnostic Err;
228  std::auto_ptr<Module> M;
229
230  M.reset(ParseIRFile(InputFilename, Err, Context));
231  if (M.get() == 0) {
232    Err.Print(argv[0], errs());
233    return 1;
234  }
235  Module &mod = *M.get();
236
237  // If we are supposed to override the target triple, do so now.
238  if (!TargetTriple.empty())
239    mod.setTargetTriple(TargetTriple);
240
241  Triple TheTriple(mod.getTargetTriple());
242  if (TheTriple.getTriple().empty())
243    TheTriple.setTriple(sys::getHostTriple());
244
245  // Allocate target machine.  First, check whether the user has explicitly
246  // specified an architecture to compile for. If so we have to look it up by
247  // name, because it might be a backend that has no mapping to a target triple.
248  const Target *TheTarget = 0;
249  if (!MArch.empty()) {
250    for (TargetRegistry::iterator it = TargetRegistry::begin(),
251           ie = TargetRegistry::end(); it != ie; ++it) {
252      if (MArch == it->getName()) {
253        TheTarget = &*it;
254        break;
255      }
256    }
257
258    if (!TheTarget) {
259      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
260      return 1;
261    }
262
263    // Adjust the triple to match (if known), otherwise stick with the
264    // module/host triple.
265    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
266    if (Type != Triple::UnknownArch)
267      TheTriple.setArch(Type);
268  } else {
269    std::string Err;
270    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
271    if (TheTarget == 0) {
272      errs() << argv[0] << ": error auto-selecting target for module '"
273             << Err << "'.  Please use the -march option to explicitly "
274             << "pick a target.\n";
275      return 1;
276    }
277  }
278
279  // Package up features to be passed to target/subtarget
280  std::string FeaturesStr;
281  if (MCPU.size() || MAttrs.size()) {
282    SubtargetFeatures Features;
283    Features.setCPU(MCPU);
284    for (unsigned i = 0; i != MAttrs.size(); ++i)
285      Features.AddFeature(MAttrs[i]);
286    FeaturesStr = Features.getString();
287  }
288
289  std::auto_ptr<TargetMachine>
290    target(TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr));
291  assert(target.get() && "Could not allocate target machine!");
292  TargetMachine &Target = *target.get();
293
294  // Figure out where we are going to send the output...
295  formatted_raw_ostream *Out = GetOutputStream(TheTarget->getName(), argv[0]);
296  if (Out == 0) return 1;
297
298  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
299  switch (OptLevel) {
300  default:
301    errs() << argv[0] << ": invalid optimization level.\n";
302    return 1;
303  case ' ': break;
304  case '0': OLvl = CodeGenOpt::None; break;
305  case '1': OLvl = CodeGenOpt::Less; break;
306  case '2': OLvl = CodeGenOpt::Default; break;
307  case '3': OLvl = CodeGenOpt::Aggressive; break;
308  }
309
310  // If this target requires addPassesToEmitWholeFile, do it now.  This is
311  // used by strange things like the C backend.
312  if (Target.WantsWholeFile()) {
313    PassManager PM;
314
315    // Add the target data from the target machine, if it exists, or the module.
316    if (const TargetData *TD = Target.getTargetData())
317      PM.add(new TargetData(*TD));
318    else
319      PM.add(new TargetData(&mod));
320
321    if (!NoVerify)
322      PM.add(createVerifierPass());
323
324    // Ask the target to add backend passes as necessary.
325    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, OLvl)) {
326      errs() << argv[0] << ": target does not support generation of this"
327             << " file type!\n";
328      if (Out != &fouts()) delete Out;
329      // And the Out file is empty and useless, so remove it now.
330      sys::Path(OutputFilename).eraseFromDisk();
331      return 1;
332    }
333    PM.run(mod);
334  } else {
335    // Build up all of the passes that we want to do to the module.
336    FunctionPassManager Passes(M.get());
337
338    // Add the target data from the target machine, if it exists, or the module.
339    if (const TargetData *TD = Target.getTargetData())
340      Passes.add(new TargetData(*TD));
341    else
342      Passes.add(new TargetData(&mod));
343
344#ifndef NDEBUG
345    if (!NoVerify)
346      Passes.add(createVerifierPass());
347#endif
348
349    // Ask the target to add backend passes as necessary.
350    ObjectCodeEmitter *OCE = 0;
351
352    // Override default to generate verbose assembly.
353    Target.setAsmVerbosityDefault(true);
354
355    switch (Target.addPassesToEmitFile(Passes, *Out, FileType, OLvl)) {
356    default:
357      assert(0 && "Invalid file model!");
358      return 1;
359    case FileModel::Error:
360      errs() << argv[0] << ": target does not support generation of this"
361             << " file type!\n";
362      if (Out != &fouts()) delete Out;
363      // And the Out file is empty and useless, so remove it now.
364      sys::Path(OutputFilename).eraseFromDisk();
365      return 1;
366    case FileModel::AsmFile:
367    case FileModel::MachOFile:
368      break;
369    case FileModel::ElfFile:
370      OCE = AddELFWriter(Passes, *Out, Target);
371      break;
372    }
373
374    if (Target.addPassesToEmitFileFinish(Passes, OCE, OLvl)) {
375      errs() << argv[0] << ": target does not support generation of this"
376             << " file type!\n";
377      if (Out != &fouts()) delete Out;
378      // And the Out file is empty and useless, so remove it now.
379      sys::Path(OutputFilename).eraseFromDisk();
380      return 1;
381    }
382
383    Passes.doInitialization();
384
385    // Run our queue of passes all at once now, efficiently.
386    // TODO: this could lazily stream functions out of the module.
387    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
388      if (!I->isDeclaration()) {
389        if (DisableRedZone)
390          I->addFnAttr(Attribute::NoRedZone);
391        if (NoImplicitFloats)
392          I->addFnAttr(Attribute::NoImplicitFloat);
393        Passes.run(*I);
394      }
395
396    Passes.doFinalization();
397  }
398
399  // Delete the ostream if it's not a stdout stream
400  if (Out != &fouts()) delete Out;
401
402  return 0;
403}
404