llc.cpp revision 206274 
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/LinkAllAsmWriterComponents.h"
24#include "llvm/CodeGen/LinkAllCodegenComponents.h"
25#include "llvm/Config/config.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/System/Host.h"
33#include "llvm/System/Signals.h"
34#include "llvm/Target/SubtargetFeature.h"
35#include "llvm/Target/TargetData.h"
36#include "llvm/Target/TargetMachine.h"
37#include "llvm/Target/TargetRegistry.h"
38#include "llvm/Target/TargetSelect.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
52static cl::opt<bool>
53Force("f", cl::desc("Enable binary output on terminals"));
54
55// Determine optimization level.
56static cl::opt<char>
57OptLevel("O",
58         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
59                  "(default = '-O2')"),
60         cl::Prefix,
61         cl::ZeroOrMore,
62         cl::init(' '));
63
64static cl::opt<std::string>
65TargetTriple("mtriple", cl::desc("Override target triple for module"));
66
67static cl::opt<std::string>
68MArch("march", cl::desc("Architecture to generate code for (see --version)"));
69
70static cl::opt<std::string>
71MCPU("mcpu",
72  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
73  cl::value_desc("cpu-name"),
74  cl::init(""));
75
76static cl::list<std::string>
77MAttrs("mattr",
78  cl::CommaSeparated,
79  cl::desc("Target specific attributes (-mattr=help for details)"),
80  cl::value_desc("a1,+a2,-a3,..."));
81
82cl::opt<TargetMachine::CodeGenFileType>
83FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
84  cl::desc("Choose a file type (not all types are supported by all targets):"),
85  cl::values(
86       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
87                  "Emit an assembly ('.s') file"),
88       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
89                  "Emit a native object ('.o') file [experimental]"),
90       clEnumValN(TargetMachine::CGFT_Null, "null",
91                  "Emit nothing, for performance testing"),
92       clEnumValEnd));
93
94cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
95                       cl::desc("Do not verify input module"));
96
97
98static cl::opt<bool>
99DisableRedZone("disable-red-zone",
100  cl::desc("Do not emit code that uses the red zone."),
101  cl::init(false));
102
103static cl::opt<bool>
104NoImplicitFloats("no-implicit-float",
105  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
106  cl::init(false));
107
108// GetFileNameRoot - Helper function to get the basename of a filename.
109static inline std::string
110GetFileNameRoot(const std::string &InputFilename) {
111  std::string IFN = InputFilename;
112  std::string outputFilename;
113  int Len = IFN.length();
114  if ((Len > 2) &&
115      IFN[Len-3] == '.' &&
116      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
117       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
118    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
119  } else {
120    outputFilename = IFN;
121  }
122  return outputFilename;
123}
124
125static formatted_raw_ostream *GetOutputStream(const char *TargetName,
126                                              const char *ProgName) {
127  if (OutputFilename != "") {
128    if (OutputFilename == "-")
129      return &fouts();
130
131    // Make sure that the Out file gets unlinked from the disk if we get a
132    // SIGINT
133    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
134
135    std::string error;
136    raw_fd_ostream *FDOut =
137      new raw_fd_ostream(OutputFilename.c_str(), error,
138                         raw_fd_ostream::F_Binary);
139    if (!error.empty()) {
140      errs() << error << '\n';
141      delete FDOut;
142      return 0;
143    }
144    formatted_raw_ostream *Out =
145      new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
146
147    return Out;
148  }
149
150  if (InputFilename == "-") {
151    OutputFilename = "-";
152    return &fouts();
153  }
154
155  OutputFilename = GetFileNameRoot(InputFilename);
156
157  bool Binary = false;
158  switch (FileType) {
159  default: assert(0 && "Unknown file type");
160  case TargetMachine::CGFT_AssemblyFile:
161    if (TargetName[0] == 'c') {
162      if (TargetName[1] == 0)
163        OutputFilename += ".cbe.c";
164      else if (TargetName[1] == 'p' && TargetName[2] == 'p')
165        OutputFilename += ".cpp";
166      else
167        OutputFilename += ".s";
168    } else
169      OutputFilename += ".s";
170    break;
171  case TargetMachine::CGFT_ObjectFile:
172    OutputFilename += ".o";
173    Binary = true;
174    break;
175  case TargetMachine::CGFT_Null:
176    OutputFilename += ".null";
177    Binary = true;
178    break;
179  }
180
181  // Make sure that the Out file gets unlinked from the disk if we get a
182  // SIGINT
183  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
184
185  std::string error;
186  unsigned OpenFlags = 0;
187  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
188  raw_fd_ostream *FDOut = new raw_fd_ostream(OutputFilename.c_str(), error,
189                                             OpenFlags);
190  if (!error.empty()) {
191    errs() << error << '\n';
192    delete FDOut;
193    return 0;
194  }
195
196  formatted_raw_ostream *Out =
197    new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
198
199  return Out;
200}
201
202// main - Entry point for the llc compiler.
203//
204int main(int argc, char **argv) {
205  sys::PrintStackTraceOnErrorSignal();
206  PrettyStackTraceProgram X(argc, argv);
207
208  // Enable debug stream buffering.
209  EnableDebugBuffering = true;
210
211  LLVMContext &Context = getGlobalContext();
212  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
213
214  // Initialize targets first, so that --version shows registered targets.
215  InitializeAllTargets();
216  InitializeAllAsmPrinters();
217  InitializeAllAsmParsers();
218
219  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
220
221  // Load the module to be compiled...
222  SMDiagnostic Err;
223  std::auto_ptr<Module> M;
224
225  M.reset(ParseIRFile(InputFilename, Err, Context));
226  if (M.get() == 0) {
227    Err.Print(argv[0], errs());
228    return 1;
229  }
230  Module &mod = *M.get();
231
232  // If we are supposed to override the target triple, do so now.
233  if (!TargetTriple.empty())
234    mod.setTargetTriple(TargetTriple);
235
236  Triple TheTriple(mod.getTargetTriple());
237  if (TheTriple.getTriple().empty())
238    TheTriple.setTriple(sys::getHostTriple());
239
240  // Allocate target machine.  First, check whether the user has explicitly
241  // specified an architecture to compile for. If so we have to look it up by
242  // name, because it might be a backend that has no mapping to a target triple.
243  const Target *TheTarget = 0;
244  if (!MArch.empty()) {
245    for (TargetRegistry::iterator it = TargetRegistry::begin(),
246           ie = TargetRegistry::end(); it != ie; ++it) {
247      if (MArch == it->getName()) {
248        TheTarget = &*it;
249        break;
250      }
251    }
252
253    if (!TheTarget) {
254      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
255      return 1;
256    }
257
258    // Adjust the triple to match (if known), otherwise stick with the
259    // module/host triple.
260    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
261    if (Type != Triple::UnknownArch)
262      TheTriple.setArch(Type);
263  } else {
264    std::string Err;
265    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
266    if (TheTarget == 0) {
267      errs() << argv[0] << ": error auto-selecting target for module '"
268             << Err << "'.  Please use the -march option to explicitly "
269             << "pick a target.\n";
270      return 1;
271    }
272  }
273
274  // Package up features to be passed to target/subtarget
275  std::string FeaturesStr;
276  if (MCPU.size() || MAttrs.size()) {
277    SubtargetFeatures Features;
278    Features.setCPU(MCPU);
279    for (unsigned i = 0; i != MAttrs.size(); ++i)
280      Features.AddFeature(MAttrs[i]);
281    FeaturesStr = Features.getString();
282  }
283
284  std::auto_ptr<TargetMachine>
285    target(TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr));
286  assert(target.get() && "Could not allocate target machine!");
287  TargetMachine &Target = *target.get();
288
289  // Figure out where we are going to send the output...
290  formatted_raw_ostream *Out = GetOutputStream(TheTarget->getName(), argv[0]);
291  if (Out == 0) return 1;
292
293  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
294  switch (OptLevel) {
295  default:
296    errs() << argv[0] << ": invalid optimization level.\n";
297    return 1;
298  case ' ': break;
299  case '0': OLvl = CodeGenOpt::None; break;
300  case '1': OLvl = CodeGenOpt::Less; break;
301  case '2': OLvl = CodeGenOpt::Default; break;
302  case '3': OLvl = CodeGenOpt::Aggressive; break;
303  }
304
305  // Request that addPassesToEmitFile run the Verifier after running
306  // passes which modify the IR.
307#ifndef NDEBUG
308  bool DisableVerify = false;
309#else
310  bool DisableVerify = true;
311#endif
312
313  // If this target requires addPassesToEmitWholeFile, do it now.  This is
314  // used by strange things like the C backend.
315  if (Target.WantsWholeFile()) {
316    PassManager PM;
317
318    // Add the target data from the target machine, if it exists, or the module.
319    if (const TargetData *TD = Target.getTargetData())
320      PM.add(new TargetData(*TD));
321    else
322      PM.add(new TargetData(&mod));
323
324    if (!NoVerify)
325      PM.add(createVerifierPass());
326
327    // Ask the target to add backend passes as necessary.
328    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, OLvl,
329                                        DisableVerify)) {
330      errs() << argv[0] << ": target does not support generation of this"
331             << " file type!\n";
332      if (Out != &fouts()) delete Out;
333      // And the Out file is empty and useless, so remove it now.
334      sys::Path(OutputFilename).eraseFromDisk();
335      return 1;
336    }
337    PM.run(mod);
338  } else {
339    // Build up all of the passes that we want to do to the module.
340    FunctionPassManager Passes(M.get());
341
342    // Add the target data from the target machine, if it exists, or the module.
343    if (const TargetData *TD = Target.getTargetData())
344      Passes.add(new TargetData(*TD));
345    else
346      Passes.add(new TargetData(&mod));
347
348#ifndef NDEBUG
349    if (!NoVerify)
350      Passes.add(createVerifierPass());
351#endif
352
353    // Override default to generate verbose assembly.
354    Target.setAsmVerbosityDefault(true);
355
356    if (Target.addPassesToEmitFile(Passes, *Out, FileType, OLvl,
357                                   DisableVerify)) {
358      errs() << argv[0] << ": target does not support generation of this"
359             << " file type!\n";
360      if (Out != &fouts()) delete Out;
361      // And the Out file is empty and useless, so remove it now.
362      sys::Path(OutputFilename).eraseFromDisk();
363      return 1;
364    }
365
366    Passes.doInitialization();
367
368    // Run our queue of passes all at once now, efficiently.
369    // TODO: this could lazily stream functions out of the module.
370    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
371      if (!I->isDeclaration()) {
372        if (DisableRedZone)
373          I->addFnAttr(Attribute::NoRedZone);
374        if (NoImplicitFloats)
375          I->addFnAttr(Attribute::NoImplicitFloat);
376        Passes.run(*I);
377      }
378
379    Passes.doFinalization();
380  }
381
382  // Delete the ostream if it's not a stdout stream
383  if (Out != &fouts()) delete Out;
384
385  return 0;
386}
387