llc.cpp revision 221337 
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/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/Target/SubtargetFeature.h"
35#include "llvm/Target/TargetData.h"
36#include "llvm/Target/TargetMachine.h"
37#include "llvm/Target/TargetRegistry.h"
38#include "llvm/Target/TargetSelect.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<bool>
80RelaxAll("mc-relax-all",
81  cl::desc("When used with filetype=obj, "
82           "relax all fixups in the emitted object file"));
83
84cl::opt<TargetMachine::CodeGenFileType>
85FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
86  cl::desc("Choose a file type (not all types are supported by all targets):"),
87  cl::values(
88       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
89                  "Emit an assembly ('.s') file"),
90       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
91                  "Emit a native object ('.o') file [experimental]"),
92       clEnumValN(TargetMachine::CGFT_Null, "null",
93                  "Emit nothing, for performance testing"),
94       clEnumValEnd));
95
96cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
97                       cl::desc("Do not verify input module"));
98
99cl::opt<bool> DisableDotLoc("disable-dot-loc", cl::Hidden,
100                            cl::desc("Do not use .loc entries"));
101
102cl::opt<bool> DisableCFI("disable-cfi", cl::Hidden,
103                         cl::desc("Do not use .cfi_* directives"));
104
105static cl::opt<bool>
106DisableRedZone("disable-red-zone",
107  cl::desc("Do not emit code that uses the red zone."),
108  cl::init(false));
109
110static cl::opt<bool>
111NoImplicitFloats("no-implicit-float",
112  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
113  cl::init(false));
114
115// GetFileNameRoot - Helper function to get the basename of a filename.
116static inline std::string
117GetFileNameRoot(const std::string &InputFilename) {
118  std::string IFN = InputFilename;
119  std::string outputFilename;
120  int Len = IFN.length();
121  if ((Len > 2) &&
122      IFN[Len-3] == '.' &&
123      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
124       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
125    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
126  } else {
127    outputFilename = IFN;
128  }
129  return outputFilename;
130}
131
132static tool_output_file *GetOutputStream(const char *TargetName,
133                                         Triple::OSType OS,
134                                         const char *ProgName) {
135  // If we don't yet have an output filename, make one.
136  if (OutputFilename.empty()) {
137    if (InputFilename == "-")
138      OutputFilename = "-";
139    else {
140      OutputFilename = GetFileNameRoot(InputFilename);
141
142      switch (FileType) {
143      default: assert(0 && "Unknown file type");
144      case TargetMachine::CGFT_AssemblyFile:
145        if (TargetName[0] == 'c') {
146          if (TargetName[1] == 0)
147            OutputFilename += ".cbe.c";
148          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
149            OutputFilename += ".cpp";
150          else
151            OutputFilename += ".s";
152        } else
153          OutputFilename += ".s";
154        break;
155      case TargetMachine::CGFT_ObjectFile:
156        if (OS == Triple::Win32)
157          OutputFilename += ".obj";
158        else
159          OutputFilename += ".o";
160        break;
161      case TargetMachine::CGFT_Null:
162        OutputFilename += ".null";
163        break;
164      }
165    }
166  }
167
168  // Decide if we need "binary" output.
169  bool Binary = false;
170  switch (FileType) {
171  default: assert(0 && "Unknown file type");
172  case TargetMachine::CGFT_AssemblyFile:
173    break;
174  case TargetMachine::CGFT_ObjectFile:
175  case TargetMachine::CGFT_Null:
176    Binary = true;
177    break;
178  }
179
180  // Open the file.
181  std::string error;
182  unsigned OpenFlags = 0;
183  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
184  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
185                                                 OpenFlags);
186  if (!error.empty()) {
187    errs() << error << '\n';
188    delete FDOut;
189    return 0;
190  }
191
192  return FDOut;
193}
194
195// main - Entry point for the llc compiler.
196//
197int main(int argc, char **argv) {
198  sys::PrintStackTraceOnErrorSignal();
199  PrettyStackTraceProgram X(argc, argv);
200
201  // Enable debug stream buffering.
202  EnableDebugBuffering = true;
203
204  LLVMContext &Context = getGlobalContext();
205  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
206
207  // Initialize targets first, so that --version shows registered targets.
208  InitializeAllTargets();
209  InitializeAllAsmPrinters();
210  InitializeAllAsmParsers();
211
212  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
213
214  // Load the module to be compiled...
215  SMDiagnostic Err;
216  std::auto_ptr<Module> M;
217
218  M.reset(ParseIRFile(InputFilename, Err, Context));
219  if (M.get() == 0) {
220    Err.Print(argv[0], errs());
221    return 1;
222  }
223  Module &mod = *M.get();
224
225  // If we are supposed to override the target triple, do so now.
226  if (!TargetTriple.empty())
227    mod.setTargetTriple(Triple::normalize(TargetTriple));
228
229  Triple TheTriple(mod.getTargetTriple());
230  if (TheTriple.getTriple().empty())
231    TheTriple.setTriple(sys::getHostTriple());
232
233  // Allocate target machine.  First, check whether the user has explicitly
234  // specified an architecture to compile for. If so we have to look it up by
235  // name, because it might be a backend that has no mapping to a target triple.
236  const Target *TheTarget = 0;
237  if (!MArch.empty()) {
238    for (TargetRegistry::iterator it = TargetRegistry::begin(),
239           ie = TargetRegistry::end(); it != ie; ++it) {
240      if (MArch == it->getName()) {
241        TheTarget = &*it;
242        break;
243      }
244    }
245
246    if (!TheTarget) {
247      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
248      return 1;
249    }
250
251    // Adjust the triple to match (if known), otherwise stick with the
252    // module/host triple.
253    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
254    if (Type != Triple::UnknownArch)
255      TheTriple.setArch(Type);
256  } else {
257    std::string Err;
258    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
259    if (TheTarget == 0) {
260      errs() << argv[0] << ": error auto-selecting target for module '"
261             << Err << "'.  Please use the -march option to explicitly "
262             << "pick a target.\n";
263      return 1;
264    }
265  }
266
267  // Package up features to be passed to target/subtarget
268  std::string FeaturesStr;
269  if (MCPU.size() || MAttrs.size()) {
270    SubtargetFeatures Features;
271    Features.setCPU(MCPU);
272    for (unsigned i = 0; i != MAttrs.size(); ++i)
273      Features.AddFeature(MAttrs[i]);
274    FeaturesStr = Features.getString();
275  }
276
277  std::auto_ptr<TargetMachine>
278    target(TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr));
279  assert(target.get() && "Could not allocate target machine!");
280  TargetMachine &Target = *target.get();
281
282  if (DisableDotLoc)
283    Target.setMCUseLoc(false);
284
285  if (DisableCFI)
286    Target.setMCUseCFI(false);
287
288  // Disable .loc support for older OS X versions.
289  if (TheTriple.isMacOSX() &&
290      TheTriple.isMacOSXVersionLT(10, 6))
291    Target.setMCUseLoc(false);
292
293  // Figure out where we are going to send the output...
294  OwningPtr<tool_output_file> Out
295    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
296  if (!Out) return 1;
297
298  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
299  switch (OptLevel) {
300  default:
301    errs() << argv[0] << ": invalid optimization level.\n";
302    return 1;
303  case ' ': break;
304  case '0': OLvl = CodeGenOpt::None; break;
305  case '1': OLvl = CodeGenOpt::Less; break;
306  case '2': OLvl = CodeGenOpt::Default; break;
307  case '3': OLvl = CodeGenOpt::Aggressive; break;
308  }
309
310  // Build up all of the passes that we want to do to the module.
311  PassManager PM;
312
313  // Add the target data from the target machine, if it exists, or the module.
314  if (const TargetData *TD = Target.getTargetData())
315    PM.add(new TargetData(*TD));
316  else
317    PM.add(new TargetData(&mod));
318
319  // Override default to generate verbose assembly.
320  Target.setAsmVerbosityDefault(true);
321
322  if (RelaxAll) {
323    if (FileType != TargetMachine::CGFT_ObjectFile)
324      errs() << argv[0]
325             << ": warning: ignoring -mc-relax-all because filetype != obj";
326    else
327      Target.setMCRelaxAll(true);
328  }
329
330  {
331    formatted_raw_ostream FOS(Out->os());
332
333    // Ask the target to add backend passes as necessary.
334    if (Target.addPassesToEmitFile(PM, FOS, FileType, OLvl, NoVerify)) {
335      errs() << argv[0] << ": target does not support generation of this"
336             << " file type!\n";
337      return 1;
338    }
339
340    // Before executing passes, print the final values of the LLVM options.
341    cl::PrintOptionValues();
342
343    PM.run(mod);
344  }
345
346  // Declare success.
347  Out->keep();
348
349  return 0;
350}
351