llc.cpp revision 8a8d479214745c82ef00f08d4e4f1c173b5f9ce2 
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
136cl::opt<bool> EnableDwarfDirectory("enable-dwarf-directory", cl::Hidden,
137    cl::desc("Use .file directives with an explicit directory."));
138
139static cl::opt<bool>
140DisableRedZone("disable-red-zone",
141  cl::desc("Do not emit code that uses the red zone."),
142  cl::init(false));
143
144static cl::opt<bool>
145EnableFPMAD("enable-fp-mad",
146  cl::desc("Enable less precise MAD instructions to be generated"),
147  cl::init(false));
148
149static cl::opt<bool>
150PrintCode("print-machineinstrs",
151  cl::desc("Print generated machine code"),
152  cl::init(false));
153
154static cl::opt<bool>
155DisableFPElim("disable-fp-elim",
156  cl::desc("Disable frame pointer elimination optimization"),
157  cl::init(false));
158
159static cl::opt<bool>
160DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
161  cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
162  cl::init(false));
163
164static cl::opt<bool>
165DisableExcessPrecision("disable-excess-fp-precision",
166  cl::desc("Disable optimizations that may increase FP precision"),
167  cl::init(false));
168
169static cl::opt<bool>
170EnableUnsafeFPMath("enable-unsafe-fp-math",
171  cl::desc("Enable optimizations that may decrease FP precision"),
172  cl::init(false));
173
174static cl::opt<bool>
175EnableNoInfsFPMath("enable-no-infs-fp-math",
176  cl::desc("Enable FP math optimizations that assume no +-Infs"),
177  cl::init(false));
178
179static cl::opt<bool>
180EnableNoNaNsFPMath("enable-no-nans-fp-math",
181  cl::desc("Enable FP math optimizations that assume no NaNs"),
182  cl::init(false));
183
184static cl::opt<bool>
185EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
186  cl::Hidden,
187  cl::desc("Force codegen to assume rounding mode can change dynamically"),
188  cl::init(false));
189
190static cl::opt<bool>
191GenerateSoftFloatCalls("soft-float",
192  cl::desc("Generate software floating point library calls"),
193  cl::init(false));
194
195static cl::opt<llvm::FloatABI::ABIType>
196FloatABIForCalls("float-abi",
197  cl::desc("Choose float ABI type"),
198  cl::init(FloatABI::Default),
199  cl::values(
200    clEnumValN(FloatABI::Default, "default",
201               "Target default float ABI type"),
202    clEnumValN(FloatABI::Soft, "soft",
203               "Soft float ABI (implied by -soft-float)"),
204    clEnumValN(FloatABI::Hard, "hard",
205               "Hard float ABI (uses FP registers)"),
206    clEnumValEnd));
207
208static cl::opt<bool>
209DontPlaceZerosInBSS("nozero-initialized-in-bss",
210  cl::desc("Don't place zero-initialized symbols into bss section"),
211  cl::init(false));
212
213static cl::opt<bool>
214EnableJITExceptionHandling("jit-enable-eh",
215  cl::desc("Emit exception handling information"),
216  cl::init(false));
217
218// In debug builds, make this default to true.
219#ifdef NDEBUG
220#define EMIT_DEBUG false
221#else
222#define EMIT_DEBUG true
223#endif
224static cl::opt<bool>
225EmitJitDebugInfo("jit-emit-debug",
226  cl::desc("Emit debug information to debugger"),
227  cl::init(EMIT_DEBUG));
228#undef EMIT_DEBUG
229
230static cl::opt<bool>
231EmitJitDebugInfoToDisk("jit-emit-debug-to-disk",
232  cl::Hidden,
233  cl::desc("Emit debug info objfiles to disk"),
234  cl::init(false));
235
236static cl::opt<bool>
237EnableGuaranteedTailCallOpt("tailcallopt",
238  cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
239  cl::init(false));
240
241static cl::opt<unsigned>
242OverrideStackAlignment("stack-alignment",
243  cl::desc("Override default stack alignment"),
244  cl::init(0));
245
246static cl::opt<bool>
247EnableRealignStack("realign-stack",
248  cl::desc("Realign stack if needed"),
249  cl::init(true));
250
251static cl::opt<bool>
252DisableSwitchTables(cl::Hidden, "disable-jump-tables",
253  cl::desc("Do not generate jump tables."),
254  cl::init(false));
255
256static cl::opt<bool>
257EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
258  cl::desc("Use strong PHI elimination."),
259  cl::init(false));
260
261static cl::opt<std::string>
262TrapFuncName("trap-func", cl::Hidden,
263  cl::desc("Emit a call to trap function rather than a trap instruction"),
264  cl::init(""));
265
266static cl::opt<bool>
267SegmentedStacks("segmented-stacks",
268  cl::desc("Use segmented stacks if possible."),
269  cl::init(false));
270
271
272// GetFileNameRoot - Helper function to get the basename of a filename.
273static inline std::string
274GetFileNameRoot(const std::string &InputFilename) {
275  std::string IFN = InputFilename;
276  std::string outputFilename;
277  int Len = IFN.length();
278  if ((Len > 2) &&
279      IFN[Len-3] == '.' &&
280      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
281       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
282    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
283  } else {
284    outputFilename = IFN;
285  }
286  return outputFilename;
287}
288
289static tool_output_file *GetOutputStream(const char *TargetName,
290                                         Triple::OSType OS,
291                                         const char *ProgName) {
292  // If we don't yet have an output filename, make one.
293  if (OutputFilename.empty()) {
294    if (InputFilename == "-")
295      OutputFilename = "-";
296    else {
297      OutputFilename = GetFileNameRoot(InputFilename);
298
299      switch (FileType) {
300      default: assert(0 && "Unknown file type");
301      case TargetMachine::CGFT_AssemblyFile:
302        if (TargetName[0] == 'c') {
303          if (TargetName[1] == 0)
304            OutputFilename += ".cbe.c";
305          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
306            OutputFilename += ".cpp";
307          else
308            OutputFilename += ".s";
309        } else
310          OutputFilename += ".s";
311        break;
312      case TargetMachine::CGFT_ObjectFile:
313        if (OS == Triple::Win32)
314          OutputFilename += ".obj";
315        else
316          OutputFilename += ".o";
317        break;
318      case TargetMachine::CGFT_Null:
319        OutputFilename += ".null";
320        break;
321      }
322    }
323  }
324
325  // Decide if we need "binary" output.
326  bool Binary = false;
327  switch (FileType) {
328  default: assert(0 && "Unknown file type");
329  case TargetMachine::CGFT_AssemblyFile:
330    break;
331  case TargetMachine::CGFT_ObjectFile:
332  case TargetMachine::CGFT_Null:
333    Binary = true;
334    break;
335  }
336
337  // Open the file.
338  std::string error;
339  unsigned OpenFlags = 0;
340  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
341  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
342                                                 OpenFlags);
343  if (!error.empty()) {
344    errs() << error << '\n';
345    delete FDOut;
346    return 0;
347  }
348
349  return FDOut;
350}
351
352// main - Entry point for the llc compiler.
353//
354int main(int argc, char **argv) {
355  sys::PrintStackTraceOnErrorSignal();
356  PrettyStackTraceProgram X(argc, argv);
357
358  // Enable debug stream buffering.
359  EnableDebugBuffering = true;
360
361  LLVMContext &Context = getGlobalContext();
362  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
363
364  // Initialize targets first, so that --version shows registered targets.
365  InitializeAllTargets();
366  InitializeAllTargetMCs();
367  InitializeAllAsmPrinters();
368  InitializeAllAsmParsers();
369
370  // Register the target printer for --version.
371  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
372
373  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
374
375  // Load the module to be compiled...
376  SMDiagnostic Err;
377  std::auto_ptr<Module> M;
378
379  M.reset(ParseIRFile(InputFilename, Err, Context));
380  if (M.get() == 0) {
381    Err.print(argv[0], errs());
382    return 1;
383  }
384  Module &mod = *M.get();
385
386  // If we are supposed to override the target triple, do so now.
387  if (!TargetTriple.empty())
388    mod.setTargetTriple(Triple::normalize(TargetTriple));
389
390  Triple TheTriple(mod.getTargetTriple());
391  if (TheTriple.getTriple().empty())
392    TheTriple.setTriple(sys::getDefaultTargetTriple());
393
394  // Allocate target machine.  First, check whether the user has explicitly
395  // specified an architecture to compile for. If so we have to look it up by
396  // name, because it might be a backend that has no mapping to a target triple.
397  const Target *TheTarget = 0;
398  if (!MArch.empty()) {
399    for (TargetRegistry::iterator it = TargetRegistry::begin(),
400           ie = TargetRegistry::end(); it != ie; ++it) {
401      if (MArch == it->getName()) {
402        TheTarget = &*it;
403        break;
404      }
405    }
406
407    if (!TheTarget) {
408      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
409      return 1;
410    }
411
412    // Adjust the triple to match (if known), otherwise stick with the
413    // module/host triple.
414    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
415    if (Type != Triple::UnknownArch)
416      TheTriple.setArch(Type);
417  } else {
418    std::string Err;
419    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
420    if (TheTarget == 0) {
421      errs() << argv[0] << ": error auto-selecting target for module '"
422             << Err << "'.  Please use the -march option to explicitly "
423             << "pick a target.\n";
424      return 1;
425    }
426  }
427
428  // Package up features to be passed to target/subtarget
429  std::string FeaturesStr;
430  if (MAttrs.size()) {
431    SubtargetFeatures Features;
432    for (unsigned i = 0; i != MAttrs.size(); ++i)
433      Features.AddFeature(MAttrs[i]);
434    FeaturesStr = Features.getString();
435  }
436
437  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
438  switch (OptLevel) {
439  default:
440    errs() << argv[0] << ": invalid optimization level.\n";
441    return 1;
442  case ' ': break;
443  case '0': OLvl = CodeGenOpt::None; break;
444  case '1': OLvl = CodeGenOpt::Less; break;
445  case '2': OLvl = CodeGenOpt::Default; break;
446  case '3': OLvl = CodeGenOpt::Aggressive; break;
447  }
448
449  TargetOptions Options;
450  Options.LessPreciseFPMADOption = EnableFPMAD;
451  Options.PrintMachineCode = PrintCode;
452  Options.NoFramePointerElim = DisableFPElim;
453  Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
454  Options.NoExcessFPPrecision = DisableExcessPrecision;
455  Options.UnsafeFPMath = EnableUnsafeFPMath;
456  Options.NoInfsFPMath = EnableNoInfsFPMath;
457  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
458  Options.HonorSignDependentRoundingFPMathOption =
459      EnableHonorSignDependentRoundingFPMath;
460  Options.UseSoftFloat = GenerateSoftFloatCalls;
461  if (FloatABIForCalls != FloatABI::Default)
462    Options.FloatABIType = FloatABIForCalls;
463  Options.NoZerosInBSS = DontPlaceZerosInBSS;
464  Options.JITExceptionHandling = EnableJITExceptionHandling;
465  Options.JITEmitDebugInfo = EmitJitDebugInfo;
466  Options.JITEmitDebugInfoToDisk = EmitJitDebugInfoToDisk;
467  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
468  Options.StackAlignmentOverride = OverrideStackAlignment;
469  Options.RealignStack = EnableRealignStack;
470  Options.DisableJumpTables = DisableSwitchTables;
471  Options.TrapFuncName = TrapFuncName;
472  Options.EnableSegmentedStacks = SegmentedStacks;
473
474  std::auto_ptr<TargetMachine>
475    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
476                                          MCPU, FeaturesStr, Options,
477                                          RelocModel, CMModel, OLvl));
478  assert(target.get() && "Could not allocate target machine!");
479  TargetMachine &Target = *target.get();
480
481  if (DisableDotLoc)
482    Target.setMCUseLoc(false);
483
484  if (DisableCFI)
485    Target.setMCUseCFI(false);
486
487  if (EnableDwarfDirectory)
488    Target.setMCUseDwarfDirectory(true);
489
490  if (GenerateSoftFloatCalls)
491    FloatABIForCalls = FloatABI::Soft;
492
493  // Disable .loc support for older OS X versions.
494  if (TheTriple.isMacOSX() &&
495      TheTriple.isMacOSXVersionLT(10, 6))
496    Target.setMCUseLoc(false);
497
498  // Figure out where we are going to send the output...
499  OwningPtr<tool_output_file> Out
500    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
501  if (!Out) return 1;
502
503  // Build up all of the passes that we want to do to the module.
504  PassManager PM;
505
506  // Add the target data from the target machine, if it exists, or the module.
507  if (const TargetData *TD = Target.getTargetData())
508    PM.add(new TargetData(*TD));
509  else
510    PM.add(new TargetData(&mod));
511
512  // Override default to generate verbose assembly.
513  Target.setAsmVerbosityDefault(true);
514
515  if (RelaxAll) {
516    if (FileType != TargetMachine::CGFT_ObjectFile)
517      errs() << argv[0]
518             << ": warning: ignoring -mc-relax-all because filetype != obj";
519    else
520      Target.setMCRelaxAll(true);
521  }
522
523  {
524    formatted_raw_ostream FOS(Out->os());
525
526    // Ask the target to add backend passes as necessary.
527    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify)) {
528      errs() << argv[0] << ": target does not support generation of this"
529             << " file type!\n";
530      return 1;
531    }
532
533    // Before executing passes, print the final values of the LLVM options.
534    cl::PrintOptionValues();
535
536    PM.run(mod);
537  }
538
539  // Declare success.
540  Out->keep();
541
542  return 0;
543}
544