llc.cpp revision 234982 
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/MC/SubtargetFeature.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Support/Debug.h"
27#include "llvm/Support/FormattedStream.h"
28#include "llvm/Support/ManagedStatic.h"
29#include "llvm/Support/PluginLoader.h"
30#include "llvm/Support/PrettyStackTrace.h"
31#include "llvm/Support/ToolOutputFile.h"
32#include "llvm/Support/Host.h"
33#include "llvm/Support/Signals.h"
34#include "llvm/Support/TargetRegistry.h"
35#include "llvm/Support/TargetSelect.h"
36#include "llvm/Target/TargetData.h"
37#include "llvm/Target/TargetMachine.h"
38#include <memory>
39using namespace llvm;
40
41// General options for llc.  Other pass-specific options are specified
42// within the corresponding llc passes, and target-specific options
43// and back-end code generation options are specified with the target machine.
44//
45static cl::opt<std::string>
46InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
47
48static cl::opt<std::string>
49OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
50
51// Determine optimization level.
52static cl::opt<char>
53OptLevel("O",
54         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
55                  "(default = '-O2')"),
56         cl::Prefix,
57         cl::ZeroOrMore,
58         cl::init(' '));
59
60static cl::opt<std::string>
61TargetTriple("mtriple", cl::desc("Override target triple for module"));
62
63static cl::opt<std::string>
64MArch("march", cl::desc("Architecture to generate code for (see --version)"));
65
66static cl::opt<std::string>
67MCPU("mcpu",
68  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
69  cl::value_desc("cpu-name"),
70  cl::init(""));
71
72static cl::list<std::string>
73MAttrs("mattr",
74  cl::CommaSeparated,
75  cl::desc("Target specific attributes (-mattr=help for details)"),
76  cl::value_desc("a1,+a2,-a3,..."));
77
78static cl::opt<Reloc::Model>
79RelocModel("relocation-model",
80             cl::desc("Choose relocation model"),
81             cl::init(Reloc::Default),
82             cl::values(
83            clEnumValN(Reloc::Default, "default",
84                       "Target default relocation model"),
85            clEnumValN(Reloc::Static, "static",
86                       "Non-relocatable code"),
87            clEnumValN(Reloc::PIC_, "pic",
88                       "Fully relocatable, position independent code"),
89            clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
90                       "Relocatable external references, non-relocatable code"),
91            clEnumValEnd));
92
93static cl::opt<llvm::CodeModel::Model>
94CMModel("code-model",
95        cl::desc("Choose code model"),
96        cl::init(CodeModel::Default),
97        cl::values(clEnumValN(CodeModel::Default, "default",
98                              "Target default code model"),
99                   clEnumValN(CodeModel::Small, "small",
100                              "Small code model"),
101                   clEnumValN(CodeModel::Kernel, "kernel",
102                              "Kernel code model"),
103                   clEnumValN(CodeModel::Medium, "medium",
104                              "Medium code model"),
105                   clEnumValN(CodeModel::Large, "large",
106                              "Large code model"),
107                   clEnumValEnd));
108
109static cl::opt<bool>
110RelaxAll("mc-relax-all",
111  cl::desc("When used with filetype=obj, "
112           "relax all fixups in the emitted object file"));
113
114cl::opt<TargetMachine::CodeGenFileType>
115FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
116  cl::desc("Choose a file type (not all types are supported by all targets):"),
117  cl::values(
118       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
119                  "Emit an assembly ('.s') file"),
120       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
121                  "Emit a native object ('.o') file [experimental]"),
122       clEnumValN(TargetMachine::CGFT_Null, "null",
123                  "Emit nothing, for performance testing"),
124       clEnumValEnd));
125
126cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
127                       cl::desc("Do not verify input module"));
128
129cl::opt<bool> DisableDotLoc("disable-dot-loc", cl::Hidden,
130                            cl::desc("Do not use .loc entries"));
131
132cl::opt<bool> DisableCFI("disable-cfi", cl::Hidden,
133                         cl::desc("Do not use .cfi_* directives"));
134
135cl::opt<bool> EnableDwarfDirectory("enable-dwarf-directory", cl::Hidden,
136    cl::desc("Use .file directives with an explicit directory."));
137
138static cl::opt<bool>
139DisableRedZone("disable-red-zone",
140  cl::desc("Do not emit code that uses the red zone."),
141  cl::init(false));
142
143static cl::opt<bool>
144EnableFPMAD("enable-fp-mad",
145  cl::desc("Enable less precise MAD instructions to be generated"),
146  cl::init(false));
147
148static cl::opt<bool>
149PrintCode("print-machineinstrs",
150  cl::desc("Print generated machine code"),
151  cl::init(false));
152
153static cl::opt<bool>
154DisableFPElim("disable-fp-elim",
155  cl::desc("Disable frame pointer elimination optimization"),
156  cl::init(false));
157
158static cl::opt<bool>
159DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
160  cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
161  cl::init(false));
162
163static cl::opt<bool>
164DisableExcessPrecision("disable-excess-fp-precision",
165  cl::desc("Disable optimizations that may increase FP precision"),
166  cl::init(false));
167
168static cl::opt<bool>
169EnableUnsafeFPMath("enable-unsafe-fp-math",
170  cl::desc("Enable optimizations that may decrease FP precision"),
171  cl::init(false));
172
173static cl::opt<bool>
174EnableNoInfsFPMath("enable-no-infs-fp-math",
175  cl::desc("Enable FP math optimizations that assume no +-Infs"),
176  cl::init(false));
177
178static cl::opt<bool>
179EnableNoNaNsFPMath("enable-no-nans-fp-math",
180  cl::desc("Enable FP math optimizations that assume no NaNs"),
181  cl::init(false));
182
183static cl::opt<bool>
184EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
185  cl::Hidden,
186  cl::desc("Force codegen to assume rounding mode can change dynamically"),
187  cl::init(false));
188
189static cl::opt<bool>
190GenerateSoftFloatCalls("soft-float",
191  cl::desc("Generate software floating point library calls"),
192  cl::init(false));
193
194static cl::opt<llvm::FloatABI::ABIType>
195FloatABIForCalls("float-abi",
196  cl::desc("Choose float ABI type"),
197  cl::init(FloatABI::Default),
198  cl::values(
199    clEnumValN(FloatABI::Default, "default",
200               "Target default float ABI type"),
201    clEnumValN(FloatABI::Soft, "soft",
202               "Soft float ABI (implied by -soft-float)"),
203    clEnumValN(FloatABI::Hard, "hard",
204               "Hard float ABI (uses FP registers)"),
205    clEnumValEnd));
206
207static cl::opt<bool>
208DontPlaceZerosInBSS("nozero-initialized-in-bss",
209  cl::desc("Don't place zero-initialized symbols into bss section"),
210  cl::init(false));
211
212static cl::opt<bool>
213EnableGuaranteedTailCallOpt("tailcallopt",
214  cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
215  cl::init(false));
216
217static cl::opt<bool>
218DisableTailCalls("disable-tail-calls",
219  cl::desc("Never emit tail calls"),
220  cl::init(false));
221
222static cl::opt<unsigned>
223OverrideStackAlignment("stack-alignment",
224  cl::desc("Override default stack alignment"),
225  cl::init(0));
226
227static cl::opt<bool>
228EnableRealignStack("realign-stack",
229  cl::desc("Realign stack if needed"),
230  cl::init(true));
231
232static cl::opt<bool>
233DisableSwitchTables(cl::Hidden, "disable-jump-tables",
234  cl::desc("Do not generate jump tables."),
235  cl::init(false));
236
237static cl::opt<std::string>
238TrapFuncName("trap-func", cl::Hidden,
239  cl::desc("Emit a call to trap function rather than a trap instruction"),
240  cl::init(""));
241
242static cl::opt<bool>
243EnablePIE("enable-pie",
244  cl::desc("Assume the creation of a position independent executable."),
245  cl::init(false));
246
247static cl::opt<bool>
248SegmentedStacks("segmented-stacks",
249  cl::desc("Use segmented stacks if possible."),
250  cl::init(false));
251
252
253// GetFileNameRoot - Helper function to get the basename of a filename.
254static inline std::string
255GetFileNameRoot(const std::string &InputFilename) {
256  std::string IFN = InputFilename;
257  std::string outputFilename;
258  int Len = IFN.length();
259  if ((Len > 2) &&
260      IFN[Len-3] == '.' &&
261      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
262       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
263    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
264  } else {
265    outputFilename = IFN;
266  }
267  return outputFilename;
268}
269
270static tool_output_file *GetOutputStream(const char *TargetName,
271                                         Triple::OSType OS,
272                                         const char *ProgName) {
273  // If we don't yet have an output filename, make one.
274  if (OutputFilename.empty()) {
275    if (InputFilename == "-")
276      OutputFilename = "-";
277    else {
278      OutputFilename = GetFileNameRoot(InputFilename);
279
280      switch (FileType) {
281      case TargetMachine::CGFT_AssemblyFile:
282        if (TargetName[0] == 'c') {
283          if (TargetName[1] == 0)
284            OutputFilename += ".cbe.c";
285          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
286            OutputFilename += ".cpp";
287          else
288            OutputFilename += ".s";
289        } else
290          OutputFilename += ".s";
291        break;
292      case TargetMachine::CGFT_ObjectFile:
293        if (OS == Triple::Win32)
294          OutputFilename += ".obj";
295        else
296          OutputFilename += ".o";
297        break;
298      case TargetMachine::CGFT_Null:
299        OutputFilename += ".null";
300        break;
301      }
302    }
303  }
304
305  // Decide if we need "binary" output.
306  bool Binary = false;
307  switch (FileType) {
308  case TargetMachine::CGFT_AssemblyFile:
309    break;
310  case TargetMachine::CGFT_ObjectFile:
311  case TargetMachine::CGFT_Null:
312    Binary = true;
313    break;
314  }
315
316  // Open the file.
317  std::string error;
318  unsigned OpenFlags = 0;
319  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
320  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
321                                                 OpenFlags);
322  if (!error.empty()) {
323    errs() << error << '\n';
324    delete FDOut;
325    return 0;
326  }
327
328  return FDOut;
329}
330
331// main - Entry point for the llc compiler.
332//
333int main(int argc, char **argv) {
334  sys::PrintStackTraceOnErrorSignal();
335  PrettyStackTraceProgram X(argc, argv);
336
337  // Enable debug stream buffering.
338  EnableDebugBuffering = true;
339
340  LLVMContext &Context = getGlobalContext();
341  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
342
343  // Initialize targets first, so that --version shows registered targets.
344  InitializeAllTargets();
345  InitializeAllTargetMCs();
346  InitializeAllAsmPrinters();
347  InitializeAllAsmParsers();
348
349  // Register the target printer for --version.
350  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
351
352  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
353
354  // Load the module to be compiled...
355  SMDiagnostic Err;
356  std::auto_ptr<Module> M;
357
358  M.reset(ParseIRFile(InputFilename, Err, Context));
359  if (M.get() == 0) {
360    Err.print(argv[0], errs());
361    return 1;
362  }
363  Module &mod = *M.get();
364
365  // If we are supposed to override the target triple, do so now.
366  if (!TargetTriple.empty())
367    mod.setTargetTriple(Triple::normalize(TargetTriple));
368
369  Triple TheTriple(mod.getTargetTriple());
370  if (TheTriple.getTriple().empty())
371    TheTriple.setTriple(sys::getDefaultTargetTriple());
372
373  // Allocate target machine.  First, check whether the user has explicitly
374  // specified an architecture to compile for. If so we have to look it up by
375  // name, because it might be a backend that has no mapping to a target triple.
376  const Target *TheTarget = 0;
377  if (!MArch.empty()) {
378    for (TargetRegistry::iterator it = TargetRegistry::begin(),
379           ie = TargetRegistry::end(); it != ie; ++it) {
380      if (MArch == it->getName()) {
381        TheTarget = &*it;
382        break;
383      }
384    }
385
386    if (!TheTarget) {
387      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
388      return 1;
389    }
390
391    // Adjust the triple to match (if known), otherwise stick with the
392    // module/host triple.
393    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
394    if (Type != Triple::UnknownArch)
395      TheTriple.setArch(Type);
396  } else {
397    std::string Err;
398    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
399    if (TheTarget == 0) {
400      errs() << argv[0] << ": error auto-selecting target for module '"
401             << Err << "'.  Please use the -march option to explicitly "
402             << "pick a target.\n";
403      return 1;
404    }
405  }
406
407  // Package up features to be passed to target/subtarget
408  std::string FeaturesStr;
409  if (MAttrs.size()) {
410    SubtargetFeatures Features;
411    for (unsigned i = 0; i != MAttrs.size(); ++i)
412      Features.AddFeature(MAttrs[i]);
413    FeaturesStr = Features.getString();
414  }
415
416  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
417  switch (OptLevel) {
418  default:
419    errs() << argv[0] << ": invalid optimization level.\n";
420    return 1;
421  case ' ': break;
422  case '0': OLvl = CodeGenOpt::None; break;
423  case '1': OLvl = CodeGenOpt::Less; break;
424  case '2': OLvl = CodeGenOpt::Default; break;
425  case '3': OLvl = CodeGenOpt::Aggressive; break;
426  }
427
428  TargetOptions Options;
429  Options.LessPreciseFPMADOption = EnableFPMAD;
430  Options.PrintMachineCode = PrintCode;
431  Options.NoFramePointerElim = DisableFPElim;
432  Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
433  Options.NoExcessFPPrecision = DisableExcessPrecision;
434  Options.UnsafeFPMath = EnableUnsafeFPMath;
435  Options.NoInfsFPMath = EnableNoInfsFPMath;
436  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
437  Options.HonorSignDependentRoundingFPMathOption =
438      EnableHonorSignDependentRoundingFPMath;
439  Options.UseSoftFloat = GenerateSoftFloatCalls;
440  if (FloatABIForCalls != FloatABI::Default)
441    Options.FloatABIType = FloatABIForCalls;
442  Options.NoZerosInBSS = DontPlaceZerosInBSS;
443  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
444  Options.DisableTailCalls = DisableTailCalls;
445  Options.StackAlignmentOverride = OverrideStackAlignment;
446  Options.RealignStack = EnableRealignStack;
447  Options.DisableJumpTables = DisableSwitchTables;
448  Options.TrapFuncName = TrapFuncName;
449  Options.PositionIndependentExecutable = EnablePIE;
450  Options.EnableSegmentedStacks = SegmentedStacks;
451
452  std::auto_ptr<TargetMachine>
453    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
454                                          MCPU, FeaturesStr, Options,
455                                          RelocModel, CMModel, OLvl));
456  assert(target.get() && "Could not allocate target machine!");
457  TargetMachine &Target = *target.get();
458
459  if (DisableDotLoc)
460    Target.setMCUseLoc(false);
461
462  if (DisableCFI)
463    Target.setMCUseCFI(false);
464
465  if (EnableDwarfDirectory)
466    Target.setMCUseDwarfDirectory(true);
467
468  if (GenerateSoftFloatCalls)
469    FloatABIForCalls = FloatABI::Soft;
470
471  // Disable .loc support for older OS X versions.
472  if (TheTriple.isMacOSX() &&
473      TheTriple.isMacOSXVersionLT(10, 6))
474    Target.setMCUseLoc(false);
475
476  // Figure out where we are going to send the output...
477  OwningPtr<tool_output_file> Out
478    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
479  if (!Out) return 1;
480
481  // Build up all of the passes that we want to do to the module.
482  PassManager PM;
483
484  // Add the target data from the target machine, if it exists, or the module.
485  if (const TargetData *TD = Target.getTargetData())
486    PM.add(new TargetData(*TD));
487  else
488    PM.add(new TargetData(&mod));
489
490  // Override default to generate verbose assembly.
491  Target.setAsmVerbosityDefault(true);
492
493  if (RelaxAll) {
494    if (FileType != TargetMachine::CGFT_ObjectFile)
495      errs() << argv[0]
496             << ": warning: ignoring -mc-relax-all because filetype != obj";
497    else
498      Target.setMCRelaxAll(true);
499  }
500
501  {
502    formatted_raw_ostream FOS(Out->os());
503
504    // Ask the target to add backend passes as necessary.
505    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify)) {
506      errs() << argv[0] << ": target does not support generation of this"
507             << " file type!\n";
508      return 1;
509    }
510
511    // Before executing passes, print the final values of the LLVM options.
512    cl::PrintOptionValues();
513
514    PM.run(mod);
515  }
516
517  // Declare success.
518  Out->keep();
519
520  return 0;
521}
522