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
271static cl::opt<unsigned>
272SSPBufferSize("stack-protector-buffer-size", cl::init(8),
273              cl::desc("Lower bound for a buffer to be considered for "
274                       "stack protection"));
275
276// GetFileNameRoot - Helper function to get the basename of a filename.
277static inline std::string
278GetFileNameRoot(const std::string &InputFilename) {
279  std::string IFN = InputFilename;
280  std::string outputFilename;
281  int Len = IFN.length();
282  if ((Len > 2) &&
283      IFN[Len-3] == '.' &&
284      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
285       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
286    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
287  } else {
288    outputFilename = IFN;
289  }
290  return outputFilename;
291}
292
293static tool_output_file *GetOutputStream(const char *TargetName,
294                                         Triple::OSType OS,
295                                         const char *ProgName) {
296  // If we don't yet have an output filename, make one.
297  if (OutputFilename.empty()) {
298    if (InputFilename == "-")
299      OutputFilename = "-";
300    else {
301      OutputFilename = GetFileNameRoot(InputFilename);
302
303      switch (FileType) {
304      case TargetMachine::CGFT_AssemblyFile:
305        if (TargetName[0] == 'c') {
306          if (TargetName[1] == 0)
307            OutputFilename += ".cbe.c";
308          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
309            OutputFilename += ".cpp";
310          else
311            OutputFilename += ".s";
312        } else
313          OutputFilename += ".s";
314        break;
315      case TargetMachine::CGFT_ObjectFile:
316        if (OS == Triple::Win32)
317          OutputFilename += ".obj";
318        else
319          OutputFilename += ".o";
320        break;
321      case TargetMachine::CGFT_Null:
322        OutputFilename += ".null";
323        break;
324      }
325    }
326  }
327
328  // Decide if we need "binary" output.
329  bool Binary = false;
330  switch (FileType) {
331  case TargetMachine::CGFT_AssemblyFile:
332    break;
333  case TargetMachine::CGFT_ObjectFile:
334  case TargetMachine::CGFT_Null:
335    Binary = true;
336    break;
337  }
338
339  // Open the file.
340  std::string error;
341  unsigned OpenFlags = 0;
342  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
343  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
344                                                 OpenFlags);
345  if (!error.empty()) {
346    errs() << error << '\n';
347    delete FDOut;
348    return 0;
349  }
350
351  return FDOut;
352}
353
354// main - Entry point for the llc compiler.
355//
356int main(int argc, char **argv) {
357  sys::PrintStackTraceOnErrorSignal();
358  PrettyStackTraceProgram X(argc, argv);
359
360  // Enable debug stream buffering.
361  EnableDebugBuffering = true;
362
363  LLVMContext &Context = getGlobalContext();
364  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
365
366  // Initialize targets first, so that --version shows registered targets.
367  InitializeAllTargets();
368  InitializeAllTargetMCs();
369  InitializeAllAsmPrinters();
370  InitializeAllAsmParsers();
371
372  // Initialize codegen and IR passes used by llc so that the -print-after,
373  // -print-before, and -stop-after options work.
374  PassRegistry *Registry = PassRegistry::getPassRegistry();
375  initializeCore(*Registry);
376  initializeCodeGen(*Registry);
377  initializeLoopStrengthReducePass(*Registry);
378  initializeLowerIntrinsicsPass(*Registry);
379  initializeUnreachableBlockElimPass(*Registry);
380
381  // Register the target printer for --version.
382  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
383
384  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
385
386  // Load the module to be compiled...
387  SMDiagnostic Err;
388  std::auto_ptr<Module> M;
389  Module *mod = 0;
390  Triple TheTriple;
391
392  bool SkipModule = MCPU == "help" ||
393                    (!MAttrs.empty() && MAttrs.front() == "help");
394
395  // If user just wants to list available options, skip module loading
396  if (!SkipModule) {
397    M.reset(ParseIRFile(InputFilename, Err, Context));
398    mod = M.get();
399    if (mod == 0) {
400      Err.print(argv[0], errs());
401      return 1;
402    }
403
404    // If we are supposed to override the target triple, do so now.
405    if (!TargetTriple.empty())
406      mod->setTargetTriple(Triple::normalize(TargetTriple));
407    TheTriple = Triple(mod->getTargetTriple());
408  } else {
409    TheTriple = Triple(Triple::normalize(TargetTriple));
410  }
411
412  if (TheTriple.getTriple().empty())
413    TheTriple.setTriple(sys::getDefaultTargetTriple());
414
415  // Get the target specific parser.
416  std::string Error;
417  const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
418                                                         Error);
419  if (!TheTarget) {
420    errs() << argv[0] << ": " << Error;
421    return 1;
422  }
423
424  // Package up features to be passed to target/subtarget
425  std::string FeaturesStr;
426  if (MAttrs.size()) {
427    SubtargetFeatures Features;
428    for (unsigned i = 0; i != MAttrs.size(); ++i)
429      Features.AddFeature(MAttrs[i]);
430    FeaturesStr = Features.getString();
431  }
432
433  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
434  switch (OptLevel) {
435  default:
436    errs() << argv[0] << ": invalid optimization level.\n";
437    return 1;
438  case ' ': break;
439  case '0': OLvl = CodeGenOpt::None; break;
440  case '1': OLvl = CodeGenOpt::Less; break;
441  case '2': OLvl = CodeGenOpt::Default; break;
442  case '3': OLvl = CodeGenOpt::Aggressive; break;
443  }
444
445  TargetOptions Options;
446  Options.LessPreciseFPMADOption = EnableFPMAD;
447  Options.NoFramePointerElim = DisableFPElim;
448  Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
449  Options.AllowFPOpFusion = FuseFPOps;
450  Options.UnsafeFPMath = EnableUnsafeFPMath;
451  Options.NoInfsFPMath = EnableNoInfsFPMath;
452  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
453  Options.HonorSignDependentRoundingFPMathOption =
454      EnableHonorSignDependentRoundingFPMath;
455  Options.UseSoftFloat = GenerateSoftFloatCalls;
456  if (FloatABIForCalls != FloatABI::Default)
457    Options.FloatABIType = FloatABIForCalls;
458  Options.NoZerosInBSS = DontPlaceZerosInBSS;
459  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
460  Options.DisableTailCalls = DisableTailCalls;
461  Options.StackAlignmentOverride = OverrideStackAlignment;
462  Options.RealignStack = EnableRealignStack;
463  Options.TrapFuncName = TrapFuncName;
464  Options.PositionIndependentExecutable = EnablePIE;
465  Options.EnableSegmentedStacks = SegmentedStacks;
466  Options.UseInitArray = UseInitArray;
467  Options.SSPBufferSize = SSPBufferSize;
468
469  std::auto_ptr<TargetMachine>
470    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
471                                          MCPU, FeaturesStr, Options,
472                                          RelocModel, CMModel, OLvl));
473  assert(target.get() && "Could not allocate target machine!");
474  assert(mod && "Should have exited after outputting help!");
475  TargetMachine &Target = *target.get();
476
477  if (DisableDotLoc)
478    Target.setMCUseLoc(false);
479
480  if (DisableCFI)
481    Target.setMCUseCFI(false);
482
483  if (EnableDwarfDirectory)
484    Target.setMCUseDwarfDirectory(true);
485
486  if (GenerateSoftFloatCalls)
487    FloatABIForCalls = FloatABI::Soft;
488
489  // Disable .loc support for older OS X versions.
490  if (TheTriple.isMacOSX() &&
491      TheTriple.isMacOSXVersionLT(10, 6))
492    Target.setMCUseLoc(false);
493
494  // Figure out where we are going to send the output.
495  OwningPtr<tool_output_file> Out
496    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
497  if (!Out) return 1;
498
499  // Build up all of the passes that we want to do to the module.
500  PassManager PM;
501
502  // Add an appropriate TargetLibraryInfo pass for the module's triple.
503  TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
504  if (DisableSimplifyLibCalls)
505    TLI->disableAllFunctions();
506  PM.add(TLI);
507
508  // Add the target data from the target machine, if it exists, or the module.
509  if (const TargetData *TD = Target.getTargetData())
510    PM.add(new TargetData(*TD));
511  else
512    PM.add(new TargetData(mod));
513
514  // Override default to generate verbose assembly.
515  Target.setAsmVerbosityDefault(true);
516
517  if (RelaxAll) {
518    if (FileType != TargetMachine::CGFT_ObjectFile)
519      errs() << argv[0]
520             << ": warning: ignoring -mc-relax-all because filetype != obj";
521    else
522      Target.setMCRelaxAll(true);
523  }
524
525  {
526    formatted_raw_ostream FOS(Out->os());
527
528    AnalysisID StartAfterID = 0;
529    AnalysisID StopAfterID = 0;
530    const PassRegistry *PR = PassRegistry::getPassRegistry();
531    if (!StartAfter.empty()) {
532      const PassInfo *PI = PR->getPassInfo(StartAfter);
533      if (!PI) {
534        errs() << argv[0] << ": start-after pass is not registered.\n";
535        return 1;
536      }
537      StartAfterID = PI->getTypeInfo();
538    }
539    if (!StopAfter.empty()) {
540      const PassInfo *PI = PR->getPassInfo(StopAfter);
541      if (!PI) {
542        errs() << argv[0] << ": stop-after pass is not registered.\n";
543        return 1;
544      }
545      StopAfterID = PI->getTypeInfo();
546    }
547
548    // Ask the target to add backend passes as necessary.
549    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify,
550                                   StartAfterID, StopAfterID)) {
551      errs() << argv[0] << ": target does not support generation of this"
552             << " file type!\n";
553      return 1;
554    }
555
556    // Before executing passes, print the final values of the LLVM options.
557    cl::PrintOptionValues();
558
559    PM.run(*mod);
560  }
561
562  // Declare success.
563  Out->keep();
564
565  return 0;
566}
567