llc.cpp revision 0d7c695c74ae6d5f68cc07378c17491915e607d3 
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/Bitcode/ReaderWriter.h"
17#include "llvm/CodeGen/FileWriters.h"
18#include "llvm/CodeGen/LinkAllCodegenComponents.h"
19#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
20#include "llvm/CodeGen/ObjectCodeEmitter.h"
21#include "llvm/Target/SubtargetFeature.h"
22#include "llvm/Target/TargetData.h"
23#include "llvm/Target/TargetMachine.h"
24#include "llvm/Target/TargetMachineRegistry.h"
25#include "llvm/Transforms/Scalar.h"
26#include "llvm/LLVMContext.h"
27#include "llvm/Module.h"
28#include "llvm/ModuleProvider.h"
29#include "llvm/PassManager.h"
30#include "llvm/Pass.h"
31#include "llvm/Support/CommandLine.h"
32#include "llvm/Support/FileUtilities.h"
33#include "llvm/Support/FormattedStream.h"
34#include "llvm/Support/ManagedStatic.h"
35#include "llvm/Support/MemoryBuffer.h"
36#include "llvm/Support/PluginLoader.h"
37#include "llvm/Support/PrettyStackTrace.h"
38#include "llvm/Support/RegistryParser.h"
39#include "llvm/Analysis/Verifier.h"
40#include "llvm/System/Signals.h"
41#include "llvm/Config/config.h"
42#include "llvm/LinkAllVMCore.h"
43#include "llvm/Target/TargetSelect.h"
44#include <memory>
45using namespace llvm;
46
47// General options for llc.  Other pass-specific options are specified
48// within the corresponding llc passes, and target-specific options
49// and back-end code generation options are specified with the target machine.
50//
51static cl::opt<std::string>
52InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
53
54static cl::opt<std::string>
55OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
56
57static cl::opt<bool> Force("f", cl::desc("Overwrite output files"));
58
59// Determine optimization level.
60static cl::opt<char>
61OptLevel("O",
62         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
63                  "(default = '-O2')"),
64         cl::Prefix,
65         cl::ZeroOrMore,
66         cl::init(' '));
67
68static cl::opt<std::string>
69TargetTriple("mtriple", cl::desc("Override target triple for module"));
70
71static cl::opt<const TargetMachineRegistry::entry*, false,
72               RegistryParser<TargetMachine> >
73MArch("march", cl::desc("Architecture to generate code for:"));
74
75static cl::opt<std::string>
76MCPU("mcpu",
77  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
78  cl::value_desc("cpu-name"),
79  cl::init(""));
80
81static cl::list<std::string>
82MAttrs("mattr",
83  cl::CommaSeparated,
84  cl::desc("Target specific attributes (-mattr=help for details)"),
85  cl::value_desc("a1,+a2,-a3,..."));
86
87cl::opt<TargetMachine::CodeGenFileType>
88FileType("filetype", cl::init(TargetMachine::AssemblyFile),
89  cl::desc("Choose a file type (not all types are supported by all targets):"),
90  cl::values(
91       clEnumValN(TargetMachine::AssemblyFile, "asm",
92                  "Emit an assembly ('.s') file"),
93       clEnumValN(TargetMachine::ObjectFile, "obj",
94                  "Emit a native object ('.o') file [experimental]"),
95       clEnumValN(TargetMachine::DynamicLibrary, "dynlib",
96                  "Emit a native dynamic library ('.so') file"
97                  " [experimental]"),
98       clEnumValEnd));
99
100cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
101                       cl::desc("Do not verify input module"));
102
103
104static cl::opt<bool>
105DisableRedZone("disable-red-zone",
106  cl::desc("Do not emit code that uses the red zone."),
107  cl::init(false));
108
109static cl::opt<bool>
110NoImplicitFloats("no-implicit-float",
111  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
112  cl::init(false));
113
114// GetFileNameRoot - Helper function to get the basename of a filename.
115static inline std::string
116GetFileNameRoot(const std::string &InputFilename) {
117  std::string IFN = InputFilename;
118  std::string outputFilename;
119  int Len = IFN.length();
120  if ((Len > 2) &&
121      IFN[Len-3] == '.' && IFN[Len-2] == 'b' && IFN[Len-1] == 'c') {
122    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
123  } else {
124    outputFilename = IFN;
125  }
126  return outputFilename;
127}
128
129static formatted_raw_ostream *GetOutputStream(const char *TargetName,
130                                              const char *ProgName) {
131  if (OutputFilename != "") {
132    if (OutputFilename == "-")
133      return &fouts();
134
135    // Make sure that the Out file gets unlinked from the disk if we get a
136    // SIGINT
137    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
138
139    std::string error;
140    raw_fd_ostream *FDOut = new raw_fd_ostream(OutputFilename.c_str(),
141                                               /*Binary=*/true, Force, error);
142    if (!error.empty()) {
143      errs() << error << '\n';
144      if (!Force)
145        errs() << "Use -f command line argument to force output\n";
146      delete FDOut;
147      return 0;
148    }
149    formatted_raw_ostream *Out =
150      new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
151
152    return Out;
153  }
154
155  if (InputFilename == "-") {
156    OutputFilename = "-";
157    return &fouts();
158  }
159
160  OutputFilename = GetFileNameRoot(InputFilename);
161
162  bool Binary = false;
163  switch (FileType) {
164  case TargetMachine::AssemblyFile:
165    if (TargetName[0] == 'c') {
166      if (TargetName[1] == 0)
167        OutputFilename += ".cbe.c";
168      else if (TargetName[1] == 'p' && TargetName[2] == 'p')
169        OutputFilename += ".cpp";
170      else
171        OutputFilename += ".s";
172    } else
173      OutputFilename += ".s";
174    break;
175  case TargetMachine::ObjectFile:
176    OutputFilename += ".o";
177    Binary = true;
178    break;
179  case TargetMachine::DynamicLibrary:
180    OutputFilename += LTDL_SHLIB_EXT;
181    Binary = true;
182    break;
183  }
184
185  // Make sure that the Out file gets unlinked from the disk if we get a
186  // SIGINT
187  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
188
189  std::string error;
190  raw_fd_ostream *FDOut = new raw_fd_ostream(OutputFilename.c_str(),
191                                             Binary, Force, error);
192  if (!error.empty()) {
193    errs() << error << '\n';
194    if (!Force)
195      errs() << "Use -f command line argument to force output\n";
196    delete FDOut;
197    return 0;
198  }
199
200  formatted_raw_ostream *Out =
201    new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
202
203  return Out;
204}
205
206// main - Entry point for the llc compiler.
207//
208int main(int argc, char **argv) {
209  sys::PrintStackTraceOnErrorSignal();
210  PrettyStackTraceProgram X(argc, argv);
211  LLVMContext &Context = getGlobalContext();
212  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
213  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
214
215  InitializeAllTargets();
216  InitializeAllAsmPrinters();
217
218  // Load the module to be compiled...
219  std::string ErrorMessage;
220  std::auto_ptr<Module> M;
221
222  std::auto_ptr<MemoryBuffer> Buffer(
223                   MemoryBuffer::getFileOrSTDIN(InputFilename, &ErrorMessage));
224  if (Buffer.get())
225    M.reset(ParseBitcodeFile(Buffer.get(), Context, &ErrorMessage));
226  if (M.get() == 0) {
227    errs() << argv[0] << ": bitcode didn't read correctly.\n";
228    errs() << "Reason: " << ErrorMessage << "\n";
229    return 1;
230  }
231  Module &mod = *M.get();
232
233  // If we are supposed to override the target triple, do so now.
234  if (!TargetTriple.empty())
235    mod.setTargetTriple(TargetTriple);
236
237  // Allocate target machine.  First, check whether the user has
238  // explicitly specified an architecture to compile for.
239  const Target *TheTarget;
240  if (MArch) {
241    TheTarget = &MArch->TheTarget;
242  } else {
243    std::string Err;
244    TheTarget = TargetRegistry::getClosestStaticTargetForModule(mod, Err);
245    if (TheTarget == 0) {
246      errs() << argv[0] << ": error auto-selecting target for module '"
247             << Err << "'.  Please use the -march option to explicitly "
248             << "pick a target.\n";
249      return 1;
250    }
251  }
252
253  // Package up features to be passed to target/subtarget
254  std::string FeaturesStr;
255  if (MCPU.size() || MAttrs.size()) {
256    SubtargetFeatures Features;
257    Features.setCPU(MCPU);
258    for (unsigned i = 0; i != MAttrs.size(); ++i)
259      Features.AddFeature(MAttrs[i]);
260    FeaturesStr = Features.getString();
261  }
262
263  std::auto_ptr<TargetMachine>
264    target(TheTarget->createTargetMachine(mod, FeaturesStr));
265  assert(target.get() && "Could not allocate target machine!");
266  TargetMachine &Target = *target.get();
267
268  // Figure out where we are going to send the output...
269  formatted_raw_ostream *Out = GetOutputStream(TheTarget->getName(), argv[0]);
270  if (Out == 0) return 1;
271
272  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
273  switch (OptLevel) {
274  default:
275    errs() << argv[0] << ": invalid optimization level.\n";
276    return 1;
277  case ' ': break;
278  case '0': OLvl = CodeGenOpt::None; break;
279  case '1':
280  case '2': OLvl = CodeGenOpt::Default; break;
281  case '3': OLvl = CodeGenOpt::Aggressive; break;
282  }
283
284  // If this target requires addPassesToEmitWholeFile, do it now.  This is
285  // used by strange things like the C backend.
286  if (Target.WantsWholeFile()) {
287    PassManager PM;
288    PM.add(new TargetData(*Target.getTargetData()));
289    if (!NoVerify)
290      PM.add(createVerifierPass());
291
292    // Ask the target to add backend passes as necessary.
293    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, OLvl)) {
294      errs() << argv[0] << ": target does not support generation of this"
295             << " file type!\n";
296      if (Out != &fouts()) delete Out;
297      // And the Out file is empty and useless, so remove it now.
298      sys::Path(OutputFilename).eraseFromDisk();
299      return 1;
300    }
301    PM.run(mod);
302  } else {
303    // Build up all of the passes that we want to do to the module.
304    ExistingModuleProvider Provider(M.release());
305    FunctionPassManager Passes(&Provider);
306    Passes.add(new TargetData(*Target.getTargetData()));
307
308#ifndef NDEBUG
309    if (!NoVerify)
310      Passes.add(createVerifierPass());
311#endif
312
313    // Ask the target to add backend passes as necessary.
314    ObjectCodeEmitter *OCE = 0;
315
316    // Override default to generate verbose assembly.
317    Target.setAsmVerbosityDefault(true);
318
319    switch (Target.addPassesToEmitFile(Passes, *Out, FileType, OLvl)) {
320    default:
321      assert(0 && "Invalid file model!");
322      return 1;
323    case FileModel::Error:
324      errs() << argv[0] << ": target does not support generation of this"
325             << " file type!\n";
326      if (Out != &fouts()) delete Out;
327      // And the Out file is empty and useless, so remove it now.
328      sys::Path(OutputFilename).eraseFromDisk();
329      return 1;
330    case FileModel::AsmFile:
331      break;
332    case FileModel::MachOFile:
333      OCE = AddMachOWriter(Passes, *Out, Target);
334      break;
335    case FileModel::ElfFile:
336      OCE = AddELFWriter(Passes, *Out, Target);
337      break;
338    }
339
340    if (Target.addPassesToEmitFileFinish(Passes, OCE, OLvl)) {
341      errs() << argv[0] << ": target does not support generation of this"
342             << " file type!\n";
343      if (Out != &fouts()) delete Out;
344      // And the Out file is empty and useless, so remove it now.
345      sys::Path(OutputFilename).eraseFromDisk();
346      return 1;
347    }
348
349    Passes.doInitialization();
350
351    // Run our queue of passes all at once now, efficiently.
352    // TODO: this could lazily stream functions out of the module.
353    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
354      if (!I->isDeclaration()) {
355        if (DisableRedZone)
356          I->addFnAttr(Attribute::NoRedZone);
357        if (NoImplicitFloats)
358          I->addFnAttr(Attribute::NoImplicitFloat);
359        Passes.run(*I);
360      }
361
362    Passes.doFinalization();
363  }
364
365  Out->flush();
366
367  // Delete the ostream if it's not a stdout stream
368  if (Out != &fouts()) delete Out;
369
370  return 0;
371}
372