llc.cpp revision 239462 
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/Assembly/PrintModulePass.h"
22#include "llvm/Support/IRReader.h"
23#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
24#include "llvm/CodeGen/LinkAllCodegenComponents.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/TargetLibraryInfo.h"
39#include "llvm/Target/TargetMachine.h"
40#include <memory>
41using namespace llvm;
42
43// General options for llc.  Other pass-specific options are specified
44// within the corresponding llc passes, and target-specific options
45// and back-end code generation options are specified with the target machine.
46//
47static cl::opt<std::string>
48InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
49
50static cl::opt<std::string>
51OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
52
53// Determine optimization level.
54static cl::opt<char>
55OptLevel("O",
56         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
57                  "(default = '-O2')"),
58         cl::Prefix,
59         cl::ZeroOrMore,
60         cl::init(' '));
61
62static cl::opt<std::string>
63TargetTriple("mtriple", cl::desc("Override target triple for module"));
64
65static cl::opt<std::string>
66MArch("march", cl::desc("Architecture to generate code for (see --version)"));
67
68static cl::opt<std::string>
69MCPU("mcpu",
70  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
71  cl::value_desc("cpu-name"),
72  cl::init(""));
73
74static cl::list<std::string>
75MAttrs("mattr",
76  cl::CommaSeparated,
77  cl::desc("Target specific attributes (-mattr=help for details)"),
78  cl::value_desc("a1,+a2,-a3,..."));
79
80static cl::opt<Reloc::Model>
81RelocModel("relocation-model",
82             cl::desc("Choose relocation model"),
83             cl::init(Reloc::Default),
84             cl::values(
85            clEnumValN(Reloc::Default, "default",
86                       "Target default relocation model"),
87            clEnumValN(Reloc::Static, "static",
88                       "Non-relocatable code"),
89            clEnumValN(Reloc::PIC_, "pic",
90                       "Fully relocatable, position independent code"),
91            clEnumValN(Reloc::DynamicNoPIC, "dynamic-no-pic",
92                       "Relocatable external references, non-relocatable code"),
93            clEnumValEnd));
94
95static cl::opt<llvm::CodeModel::Model>
96CMModel("code-model",
97        cl::desc("Choose code model"),
98        cl::init(CodeModel::Default),
99        cl::values(clEnumValN(CodeModel::Default, "default",
100                              "Target default code model"),
101                   clEnumValN(CodeModel::Small, "small",
102                              "Small code model"),
103                   clEnumValN(CodeModel::Kernel, "kernel",
104                              "Kernel code model"),
105                   clEnumValN(CodeModel::Medium, "medium",
106                              "Medium code model"),
107                   clEnumValN(CodeModel::Large, "large",
108                              "Large code model"),
109                   clEnumValEnd));
110
111static cl::opt<bool>
112RelaxAll("mc-relax-all",
113  cl::desc("When used with filetype=obj, "
114           "relax all fixups in the emitted object file"));
115
116cl::opt<TargetMachine::CodeGenFileType>
117FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
118  cl::desc("Choose a file type (not all types are supported by all targets):"),
119  cl::values(
120       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
121                  "Emit an assembly ('.s') file"),
122       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
123                  "Emit a native object ('.o') file"),
124       clEnumValN(TargetMachine::CGFT_Null, "null",
125                  "Emit nothing, for performance testing"),
126       clEnumValEnd));
127
128cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
129                       cl::desc("Do not verify input module"));
130
131cl::opt<bool> DisableDotLoc("disable-dot-loc", cl::Hidden,
132                            cl::desc("Do not use .loc entries"));
133
134cl::opt<bool> DisableCFI("disable-cfi", cl::Hidden,
135                         cl::desc("Do not use .cfi_* directives"));
136
137cl::opt<bool> EnableDwarfDirectory("enable-dwarf-directory", cl::Hidden,
138    cl::desc("Use .file directives with an explicit directory."));
139
140static cl::opt<bool>
141DisableRedZone("disable-red-zone",
142  cl::desc("Do not emit code that uses the red zone."),
143  cl::init(false));
144
145static cl::opt<bool>
146EnableFPMAD("enable-fp-mad",
147  cl::desc("Enable less precise MAD instructions to be generated"),
148  cl::init(false));
149
150static cl::opt<bool>
151DisableFPElim("disable-fp-elim",
152  cl::desc("Disable frame pointer elimination optimization"),
153  cl::init(false));
154
155static cl::opt<bool>
156DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
157  cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
158  cl::init(false));
159
160static cl::opt<bool>
161EnableUnsafeFPMath("enable-unsafe-fp-math",
162  cl::desc("Enable optimizations that may decrease FP precision"),
163  cl::init(false));
164
165static cl::opt<bool>
166EnableNoInfsFPMath("enable-no-infs-fp-math",
167  cl::desc("Enable FP math optimizations that assume no +-Infs"),
168  cl::init(false));
169
170static cl::opt<bool>
171EnableNoNaNsFPMath("enable-no-nans-fp-math",
172  cl::desc("Enable FP math optimizations that assume no NaNs"),
173  cl::init(false));
174
175static cl::opt<bool>
176EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
177  cl::Hidden,
178  cl::desc("Force codegen to assume rounding mode can change dynamically"),
179  cl::init(false));
180
181static cl::opt<bool>
182GenerateSoftFloatCalls("soft-float",
183  cl::desc("Generate software floating point library calls"),
184  cl::init(false));
185
186static cl::opt<llvm::FloatABI::ABIType>
187FloatABIForCalls("float-abi",
188  cl::desc("Choose float ABI type"),
189  cl::init(FloatABI::Default),
190  cl::values(
191    clEnumValN(FloatABI::Default, "default",
192               "Target default float ABI type"),
193    clEnumValN(FloatABI::Soft, "soft",
194               "Soft float ABI (implied by -soft-float)"),
195    clEnumValN(FloatABI::Hard, "hard",
196               "Hard float ABI (uses FP registers)"),
197    clEnumValEnd));
198
199static cl::opt<llvm::FPOpFusion::FPOpFusionMode>
200FuseFPOps("fp-contract",
201  cl::desc("Enable aggresive formation of fused FP ops"),
202  cl::init(FPOpFusion::Standard),
203  cl::values(
204    clEnumValN(FPOpFusion::Fast, "fast",
205               "Fuse FP ops whenever profitable"),
206    clEnumValN(FPOpFusion::Standard, "on",
207               "Only fuse 'blessed' FP ops."),
208    clEnumValN(FPOpFusion::Strict, "off",
209               "Only fuse FP ops when the result won't be effected."),
210    clEnumValEnd));
211
212static cl::opt<bool>
213DontPlaceZerosInBSS("nozero-initialized-in-bss",
214  cl::desc("Don't place zero-initialized symbols into bss section"),
215  cl::init(false));
216
217static cl::opt<bool>
218DisableSimplifyLibCalls("disable-simplify-libcalls",
219  cl::desc("Disable simplify-libcalls"),
220  cl::init(false));
221
222static cl::opt<bool>
223EnableGuaranteedTailCallOpt("tailcallopt",
224  cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
225  cl::init(false));
226
227static cl::opt<bool>
228DisableTailCalls("disable-tail-calls",
229  cl::desc("Never emit tail calls"),
230  cl::init(false));
231
232static cl::opt<unsigned>
233OverrideStackAlignment("stack-alignment",
234  cl::desc("Override default stack alignment"),
235  cl::init(0));
236
237static cl::opt<bool>
238EnableRealignStack("realign-stack",
239  cl::desc("Realign stack if needed"),
240  cl::init(true));
241
242static cl::opt<std::string>
243TrapFuncName("trap-func", cl::Hidden,
244  cl::desc("Emit a call to trap function rather than a trap instruction"),
245  cl::init(""));
246
247static cl::opt<bool>
248EnablePIE("enable-pie",
249  cl::desc("Assume the creation of a position independent executable."),
250  cl::init(false));
251
252static cl::opt<bool>
253SegmentedStacks("segmented-stacks",
254  cl::desc("Use segmented stacks if possible."),
255  cl::init(false));
256
257static cl::opt<bool>
258UseInitArray("use-init-array",
259  cl::desc("Use .init_array instead of .ctors."),
260  cl::init(false));
261
262static cl::opt<std::string> StopAfter("stop-after",
263  cl::desc("Stop compilation after a specific pass"),
264  cl::value_desc("pass-name"),
265  cl::init(""));
266static cl::opt<std::string> StartAfter("start-after",
267  cl::desc("Resume compilation after a specific pass"),
268  cl::value_desc("pass-name"),
269  cl::init(""));
270
271// GetFileNameRoot - Helper function to get the basename of a filename.
272static inline std::string
273GetFileNameRoot(const std::string &InputFilename) {
274  std::string IFN = InputFilename;
275  std::string outputFilename;
276  int Len = IFN.length();
277  if ((Len > 2) &&
278      IFN[Len-3] == '.' &&
279      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
280       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
281    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
282  } else {
283    outputFilename = IFN;
284  }
285  return outputFilename;
286}
287
288static tool_output_file *GetOutputStream(const char *TargetName,
289                                         Triple::OSType OS,
290                                         const char *ProgName) {
291  // If we don't yet have an output filename, make one.
292  if (OutputFilename.empty()) {
293    if (InputFilename == "-")
294      OutputFilename = "-";
295    else {
296      OutputFilename = GetFileNameRoot(InputFilename);
297
298      switch (FileType) {
299      case TargetMachine::CGFT_AssemblyFile:
300        if (TargetName[0] == 'c') {
301          if (TargetName[1] == 0)
302            OutputFilename += ".cbe.c";
303          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
304            OutputFilename += ".cpp";
305          else
306            OutputFilename += ".s";
307        } else
308          OutputFilename += ".s";
309        break;
310      case TargetMachine::CGFT_ObjectFile:
311        if (OS == Triple::Win32)
312          OutputFilename += ".obj";
313        else
314          OutputFilename += ".o";
315        break;
316      case TargetMachine::CGFT_Null:
317        OutputFilename += ".null";
318        break;
319      }
320    }
321  }
322
323  // Decide if we need "binary" output.
324  bool Binary = false;
325  switch (FileType) {
326  case TargetMachine::CGFT_AssemblyFile:
327    break;
328  case TargetMachine::CGFT_ObjectFile:
329  case TargetMachine::CGFT_Null:
330    Binary = true;
331    break;
332  }
333
334  // Open the file.
335  std::string error;
336  unsigned OpenFlags = 0;
337  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
338  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
339                                                 OpenFlags);
340  if (!error.empty()) {
341    errs() << error << '\n';
342    delete FDOut;
343    return 0;
344  }
345
346  return FDOut;
347}
348
349// main - Entry point for the llc compiler.
350//
351int main(int argc, char **argv) {
352  sys::PrintStackTraceOnErrorSignal();
353  PrettyStackTraceProgram X(argc, argv);
354
355  // Enable debug stream buffering.
356  EnableDebugBuffering = true;
357
358  LLVMContext &Context = getGlobalContext();
359  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
360
361  // Initialize targets first, so that --version shows registered targets.
362  InitializeAllTargets();
363  InitializeAllTargetMCs();
364  InitializeAllAsmPrinters();
365  InitializeAllAsmParsers();
366
367  // Initialize codegen and IR passes used by llc so that the -print-after,
368  // -print-before, and -stop-after options work.
369  PassRegistry *Registry = PassRegistry::getPassRegistry();
370  initializeCore(*Registry);
371  initializeCodeGen(*Registry);
372  initializeLoopStrengthReducePass(*Registry);
373  initializeLowerIntrinsicsPass(*Registry);
374  initializeUnreachableBlockElimPass(*Registry);
375
376  // Register the target printer for --version.
377  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
378
379  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
380
381  // Load the module to be compiled...
382  SMDiagnostic Err;
383  std::auto_ptr<Module> M;
384  Module *mod = 0;
385  Triple TheTriple;
386
387  bool SkipModule = MCPU == "help" ||
388                    (!MAttrs.empty() && MAttrs.front() == "help");
389
390  // If user just wants to list available options, skip module loading
391  if (!SkipModule) {
392    M.reset(ParseIRFile(InputFilename, Err, Context));
393    mod = M.get();
394    if (mod == 0) {
395      Err.print(argv[0], errs());
396      return 1;
397    }
398
399    // If we are supposed to override the target triple, do so now.
400    if (!TargetTriple.empty())
401      mod->setTargetTriple(Triple::normalize(TargetTriple));
402    TheTriple = Triple(mod->getTargetTriple());
403  } else {
404    TheTriple = Triple(Triple::normalize(TargetTriple));
405  }
406
407  if (TheTriple.getTriple().empty())
408    TheTriple.setTriple(sys::getDefaultTargetTriple());
409
410  // Get the target specific parser.
411  std::string Error;
412  const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
413                                                         Error);
414  if (!TheTarget) {
415    errs() << argv[0] << ": " << Error;
416    return 1;
417  }
418
419  // Package up features to be passed to target/subtarget
420  std::string FeaturesStr;
421  if (MAttrs.size()) {
422    SubtargetFeatures Features;
423    for (unsigned i = 0; i != MAttrs.size(); ++i)
424      Features.AddFeature(MAttrs[i]);
425    FeaturesStr = Features.getString();
426  }
427
428  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
429  switch (OptLevel) {
430  default:
431    errs() << argv[0] << ": invalid optimization level.\n";
432    return 1;
433  case ' ': break;
434  case '0': OLvl = CodeGenOpt::None; break;
435  case '1': OLvl = CodeGenOpt::Less; break;
436  case '2': OLvl = CodeGenOpt::Default; break;
437  case '3': OLvl = CodeGenOpt::Aggressive; break;
438  }
439
440  TargetOptions Options;
441  Options.LessPreciseFPMADOption = EnableFPMAD;
442  Options.NoFramePointerElim = DisableFPElim;
443  Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
444  Options.AllowFPOpFusion = FuseFPOps;
445  Options.UnsafeFPMath = EnableUnsafeFPMath;
446  Options.NoInfsFPMath = EnableNoInfsFPMath;
447  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
448  Options.HonorSignDependentRoundingFPMathOption =
449      EnableHonorSignDependentRoundingFPMath;
450  Options.UseSoftFloat = GenerateSoftFloatCalls;
451  if (FloatABIForCalls != FloatABI::Default)
452    Options.FloatABIType = FloatABIForCalls;
453  Options.NoZerosInBSS = DontPlaceZerosInBSS;
454  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
455  Options.DisableTailCalls = DisableTailCalls;
456  Options.StackAlignmentOverride = OverrideStackAlignment;
457  Options.RealignStack = EnableRealignStack;
458  Options.TrapFuncName = TrapFuncName;
459  Options.PositionIndependentExecutable = EnablePIE;
460  Options.EnableSegmentedStacks = SegmentedStacks;
461  Options.UseInitArray = UseInitArray;
462
463  std::auto_ptr<TargetMachine>
464    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
465                                          MCPU, FeaturesStr, Options,
466                                          RelocModel, CMModel, OLvl));
467  assert(target.get() && "Could not allocate target machine!");
468  assert(mod && "Should have exited after outputting help!");
469  TargetMachine &Target = *target.get();
470
471  if (DisableDotLoc)
472    Target.setMCUseLoc(false);
473
474  if (DisableCFI)
475    Target.setMCUseCFI(false);
476
477  if (EnableDwarfDirectory)
478    Target.setMCUseDwarfDirectory(true);
479
480  if (GenerateSoftFloatCalls)
481    FloatABIForCalls = FloatABI::Soft;
482
483  // Disable .loc support for older OS X versions.
484  if (TheTriple.isMacOSX() &&
485      TheTriple.isMacOSXVersionLT(10, 6))
486    Target.setMCUseLoc(false);
487
488  // Figure out where we are going to send the output.
489  OwningPtr<tool_output_file> Out
490    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
491  if (!Out) return 1;
492
493  // Build up all of the passes that we want to do to the module.
494  PassManager PM;
495
496  // Add an appropriate TargetLibraryInfo pass for the module's triple.
497  TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
498  if (DisableSimplifyLibCalls)
499    TLI->disableAllFunctions();
500  PM.add(TLI);
501
502  // Add the target data from the target machine, if it exists, or the module.
503  if (const TargetData *TD = Target.getTargetData())
504    PM.add(new TargetData(*TD));
505  else
506    PM.add(new TargetData(mod));
507
508  // Override default to generate verbose assembly.
509  Target.setAsmVerbosityDefault(true);
510
511  if (RelaxAll) {
512    if (FileType != TargetMachine::CGFT_ObjectFile)
513      errs() << argv[0]
514             << ": warning: ignoring -mc-relax-all because filetype != obj";
515    else
516      Target.setMCRelaxAll(true);
517  }
518
519  {
520    formatted_raw_ostream FOS(Out->os());
521
522    AnalysisID StartAfterID = 0;
523    AnalysisID StopAfterID = 0;
524    const PassRegistry *PR = PassRegistry::getPassRegistry();
525    if (!StartAfter.empty()) {
526      const PassInfo *PI = PR->getPassInfo(StartAfter);
527      if (!PI) {
528        errs() << argv[0] << ": start-after pass is not registered.\n";
529        return 1;
530      }
531      StartAfterID = PI->getTypeInfo();
532    }
533    if (!StopAfter.empty()) {
534      const PassInfo *PI = PR->getPassInfo(StopAfter);
535      if (!PI) {
536        errs() << argv[0] << ": stop-after pass is not registered.\n";
537        return 1;
538      }
539      StopAfterID = PI->getTypeInfo();
540    }
541
542    // Ask the target to add backend passes as necessary.
543    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify,
544                                   StartAfterID, StopAfterID)) {
545      errs() << argv[0] << ": target does not support generation of this"
546             << " file type!\n";
547      return 1;
548    }
549
550    // Before executing passes, print the final values of the LLVM options.
551    cl::PrintOptionValues();
552
553    PM.run(*mod);
554  }
555
556  // Declare success.
557  Out->keep();
558
559  return 0;
560}
561