llc.cpp revision 263508 
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
17#include "llvm/IR/LLVMContext.h"
18#include "llvm/ADT/Triple.h"
19#include "llvm/Assembly/PrintModulePass.h"
20#include "llvm/CodeGen/CommandFlags.h"
21#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
22#include "llvm/CodeGen/LinkAllCodegenComponents.h"
23#include "llvm/IR/DataLayout.h"
24#include "llvm/IR/Module.h"
25#include "llvm/IRReader/IRReader.h"
26#include "llvm/MC/SubtargetFeature.h"
27#include "llvm/Pass.h"
28#include "llvm/PassManager.h"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Support/Debug.h"
31#include "llvm/Support/FormattedStream.h"
32#include "llvm/Support/Host.h"
33#include "llvm/Support/ManagedStatic.h"
34#include "llvm/Support/PluginLoader.h"
35#include "llvm/Support/PrettyStackTrace.h"
36#include "llvm/Support/Signals.h"
37#include "llvm/Support/SourceMgr.h"
38#include "llvm/Support/TargetRegistry.h"
39#include "llvm/Support/TargetSelect.h"
40#include "llvm/Support/ToolOutputFile.h"
41#include "llvm/Target/TargetLibraryInfo.h"
42#include "llvm/Target/TargetMachine.h"
43#include <memory>
44using namespace llvm;
45
46// General options for llc.  Other pass-specific options are specified
47// within the corresponding llc passes, and target-specific options
48// and back-end code generation options are specified with the target machine.
49//
50static cl::opt<std::string>
51InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
52
53static cl::opt<std::string>
54OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
55
56static cl::opt<unsigned>
57TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
58                 cl::value_desc("N"),
59                 cl::desc("Repeat compilation N times for timing"));
60
61// Determine optimization level.
62static cl::opt<char>
63OptLevel("O",
64         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
65                  "(default = '-O2')"),
66         cl::Prefix,
67         cl::ZeroOrMore,
68         cl::init(' '));
69
70static cl::opt<std::string>
71TargetTriple("mtriple", cl::desc("Override target triple for module"));
72
73cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
74                       cl::desc("Do not verify input module"));
75
76cl::opt<bool>
77DisableSimplifyLibCalls("disable-simplify-libcalls",
78                        cl::desc("Disable simplify-libcalls"),
79                        cl::init(false));
80
81static int compileModule(char**, LLVMContext&);
82
83// GetFileNameRoot - Helper function to get the basename of a filename.
84static inline std::string
85GetFileNameRoot(const std::string &InputFilename) {
86  std::string IFN = InputFilename;
87  std::string outputFilename;
88  int Len = IFN.length();
89  if ((Len > 2) &&
90      IFN[Len-3] == '.' &&
91      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
92       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
93    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
94  } else {
95    outputFilename = IFN;
96  }
97  return outputFilename;
98}
99
100static tool_output_file *GetOutputStream(const char *TargetName,
101                                         Triple::OSType OS,
102                                         const char *ProgName) {
103  // If we don't yet have an output filename, make one.
104  if (OutputFilename.empty()) {
105    if (InputFilename == "-")
106      OutputFilename = "-";
107    else {
108      OutputFilename = GetFileNameRoot(InputFilename);
109
110      switch (FileType) {
111      case TargetMachine::CGFT_AssemblyFile:
112        if (TargetName[0] == 'c') {
113          if (TargetName[1] == 0)
114            OutputFilename += ".cbe.c";
115          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
116            OutputFilename += ".cpp";
117          else
118            OutputFilename += ".s";
119        } else
120          OutputFilename += ".s";
121        break;
122      case TargetMachine::CGFT_ObjectFile:
123        if (OS == Triple::Win32)
124          OutputFilename += ".obj";
125        else
126          OutputFilename += ".o";
127        break;
128      case TargetMachine::CGFT_Null:
129        OutputFilename += ".null";
130        break;
131      }
132    }
133  }
134
135  // Decide if we need "binary" output.
136  bool Binary = false;
137  switch (FileType) {
138  case TargetMachine::CGFT_AssemblyFile:
139    break;
140  case TargetMachine::CGFT_ObjectFile:
141  case TargetMachine::CGFT_Null:
142    Binary = true;
143    break;
144  }
145
146  // Open the file.
147  std::string error;
148  sys::fs::OpenFlags OpenFlags = sys::fs::F_None;
149  if (Binary)
150    OpenFlags |= sys::fs::F_Binary;
151  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
152                                                 OpenFlags);
153  if (!error.empty()) {
154    errs() << error << '\n';
155    delete FDOut;
156    return 0;
157  }
158
159  return FDOut;
160}
161
162// main - Entry point for the llc compiler.
163//
164int main(int argc, char **argv) {
165  sys::PrintStackTraceOnErrorSignal();
166  PrettyStackTraceProgram X(argc, argv);
167
168  // Enable debug stream buffering.
169  EnableDebugBuffering = true;
170
171  LLVMContext &Context = getGlobalContext();
172  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
173
174  // Initialize targets first, so that --version shows registered targets.
175  InitializeAllTargets();
176  InitializeAllTargetMCs();
177  InitializeAllAsmPrinters();
178  InitializeAllAsmParsers();
179
180  // Initialize codegen and IR passes used by llc so that the -print-after,
181  // -print-before, and -stop-after options work.
182  PassRegistry *Registry = PassRegistry::getPassRegistry();
183  initializeCore(*Registry);
184  initializeCodeGen(*Registry);
185  initializeLoopStrengthReducePass(*Registry);
186  initializeLowerIntrinsicsPass(*Registry);
187  initializeUnreachableBlockElimPass(*Registry);
188
189  // Register the target printer for --version.
190  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
191
192  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
193
194  // Compile the module TimeCompilations times to give better compile time
195  // metrics.
196  for (unsigned I = TimeCompilations; I; --I)
197    if (int RetVal = compileModule(argv, Context))
198      return RetVal;
199  return 0;
200}
201
202static int compileModule(char **argv, LLVMContext &Context) {
203  // Load the module to be compiled...
204  SMDiagnostic Err;
205  OwningPtr<Module> M;
206  Module *mod = 0;
207  Triple TheTriple;
208
209  bool SkipModule = MCPU == "help" ||
210                    (!MAttrs.empty() && MAttrs.front() == "help");
211
212  // If user just wants to list available options, skip module loading
213  if (!SkipModule) {
214    M.reset(ParseIRFile(InputFilename, Err, Context));
215    mod = M.get();
216    if (mod == 0) {
217      Err.print(argv[0], errs());
218      return 1;
219    }
220
221    // If we are supposed to override the target triple, do so now.
222    if (!TargetTriple.empty())
223      mod->setTargetTriple(Triple::normalize(TargetTriple));
224    TheTriple = Triple(mod->getTargetTriple());
225  } else {
226    TheTriple = Triple(Triple::normalize(TargetTriple));
227  }
228
229  if (TheTriple.getTriple().empty())
230    TheTriple.setTriple(sys::getDefaultTargetTriple());
231
232  // Get the target specific parser.
233  std::string Error;
234  const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
235                                                         Error);
236  if (!TheTarget) {
237    errs() << argv[0] << ": " << Error;
238    return 1;
239  }
240
241  // Package up features to be passed to target/subtarget
242  std::string FeaturesStr;
243  if (MAttrs.size()) {
244    SubtargetFeatures Features;
245    for (unsigned i = 0; i != MAttrs.size(); ++i)
246      Features.AddFeature(MAttrs[i]);
247    FeaturesStr = Features.getString();
248  }
249
250  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
251  switch (OptLevel) {
252  default:
253    errs() << argv[0] << ": invalid optimization level.\n";
254    return 1;
255  case ' ': break;
256  case '0': OLvl = CodeGenOpt::None; break;
257  case '1': OLvl = CodeGenOpt::Less; break;
258  case '2': OLvl = CodeGenOpt::Default; break;
259  case '3': OLvl = CodeGenOpt::Aggressive; break;
260  }
261
262  TargetOptions Options;
263  Options.LessPreciseFPMADOption = EnableFPMAD;
264  Options.NoFramePointerElim = DisableFPElim;
265  Options.AllowFPOpFusion = FuseFPOps;
266  Options.UnsafeFPMath = EnableUnsafeFPMath;
267  Options.NoInfsFPMath = EnableNoInfsFPMath;
268  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
269  Options.HonorSignDependentRoundingFPMathOption =
270      EnableHonorSignDependentRoundingFPMath;
271  Options.UseSoftFloat = GenerateSoftFloatCalls;
272  if (FloatABIForCalls != FloatABI::Default)
273    Options.FloatABIType = FloatABIForCalls;
274  Options.NoZerosInBSS = DontPlaceZerosInBSS;
275  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
276  Options.DisableTailCalls = DisableTailCalls;
277  Options.StackAlignmentOverride = OverrideStackAlignment;
278  Options.TrapFuncName = TrapFuncName;
279  Options.PositionIndependentExecutable = EnablePIE;
280  Options.EnableSegmentedStacks = SegmentedStacks;
281  Options.UseInitArray = UseInitArray;
282
283  OwningPtr<TargetMachine>
284    target(TheTarget->createTargetMachine(TheTriple.getTriple(),
285                                          MCPU, FeaturesStr, Options,
286                                          RelocModel, CMModel, OLvl));
287  assert(target.get() && "Could not allocate target machine!");
288  assert(mod && "Should have exited after outputting help!");
289  TargetMachine &Target = *target.get();
290
291  if (DisableDotLoc)
292    Target.setMCUseLoc(false);
293
294  if (DisableCFI)
295    Target.setMCUseCFI(false);
296
297  if (EnableDwarfDirectory)
298    Target.setMCUseDwarfDirectory(true);
299
300  if (GenerateSoftFloatCalls)
301    FloatABIForCalls = FloatABI::Soft;
302
303  // Disable .loc support for older OS X versions.
304  if (TheTriple.isMacOSX() &&
305      TheTriple.isMacOSXVersionLT(10, 6))
306    Target.setMCUseLoc(false);
307
308  // Figure out where we are going to send the output.
309  OwningPtr<tool_output_file> Out
310    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
311  if (!Out) return 1;
312
313  // Build up all of the passes that we want to do to the module.
314  PassManager PM;
315
316  // Add an appropriate TargetLibraryInfo pass for the module's triple.
317  TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
318  if (DisableSimplifyLibCalls)
319    TLI->disableAllFunctions();
320  PM.add(TLI);
321
322  // Add intenal analysis passes from the target machine.
323  Target.addAnalysisPasses(PM);
324
325  // Add the target data from the target machine, if it exists, or the module.
326  if (const DataLayout *TD = Target.getDataLayout())
327    PM.add(new DataLayout(*TD));
328  else
329    PM.add(new DataLayout(mod));
330
331  // Override default to generate verbose assembly.
332  Target.setAsmVerbosityDefault(true);
333
334  if (RelaxAll) {
335    if (FileType != TargetMachine::CGFT_ObjectFile)
336      errs() << argv[0]
337             << ": warning: ignoring -mc-relax-all because filetype != obj";
338    else
339      Target.setMCRelaxAll(true);
340  }
341
342  {
343    formatted_raw_ostream FOS(Out->os());
344
345    AnalysisID StartAfterID = 0;
346    AnalysisID StopAfterID = 0;
347    const PassRegistry *PR = PassRegistry::getPassRegistry();
348    if (!StartAfter.empty()) {
349      const PassInfo *PI = PR->getPassInfo(StartAfter);
350      if (!PI) {
351        errs() << argv[0] << ": start-after pass is not registered.\n";
352        return 1;
353      }
354      StartAfterID = PI->getTypeInfo();
355    }
356    if (!StopAfter.empty()) {
357      const PassInfo *PI = PR->getPassInfo(StopAfter);
358      if (!PI) {
359        errs() << argv[0] << ": stop-after pass is not registered.\n";
360        return 1;
361      }
362      StopAfterID = PI->getTypeInfo();
363    }
364
365    // Ask the target to add backend passes as necessary.
366    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify,
367                                   StartAfterID, StopAfterID)) {
368      errs() << argv[0] << ": target does not support generation of this"
369             << " file type!\n";
370      return 1;
371    }
372
373    // Before executing passes, print the final values of the LLVM options.
374    cl::PrintOptionValues();
375
376    PM.run(*mod);
377  }
378
379  // Declare success.
380  Out->keep();
381
382  return 0;
383}
384