llc.cpp revision 212793 
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/System/Host.h"
32#include "llvm/System/Signals.h"
33#include "llvm/Target/SubtargetFeature.h"
34#include "llvm/Target/TargetData.h"
35#include "llvm/Target/TargetMachine.h"
36#include "llvm/Target/TargetRegistry.h"
37#include "llvm/Target/TargetSelect.h"
38#include <memory>
39using namespace llvm;
40
41// General options for llc.  Other pass-specific options are specified
42// within the corresponding llc passes, and target-specific options
43// and back-end code generation options are specified with the target machine.
44//
45static cl::opt<std::string>
46InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
47
48static cl::opt<std::string>
49OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
50
51// Determine optimization level.
52static cl::opt<char>
53OptLevel("O",
54         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
55                  "(default = '-O2')"),
56         cl::Prefix,
57         cl::ZeroOrMore,
58         cl::init(' '));
59
60static cl::opt<std::string>
61TargetTriple("mtriple", cl::desc("Override target triple for module"));
62
63static cl::opt<std::string>
64MArch("march", cl::desc("Architecture to generate code for (see --version)"));
65
66static cl::opt<std::string>
67MCPU("mcpu",
68  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
69  cl::value_desc("cpu-name"),
70  cl::init(""));
71
72static cl::list<std::string>
73MAttrs("mattr",
74  cl::CommaSeparated,
75  cl::desc("Target specific attributes (-mattr=help for details)"),
76  cl::value_desc("a1,+a2,-a3,..."));
77
78static cl::opt<bool>
79RelaxAll("mc-relax-all",
80  cl::desc("When used with filetype=obj, "
81           "relax all fixups in the emitted object file"));
82
83cl::opt<TargetMachine::CodeGenFileType>
84FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
85  cl::desc("Choose a file type (not all types are supported by all targets):"),
86  cl::values(
87       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
88                  "Emit an assembly ('.s') file"),
89       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
90                  "Emit a native object ('.o') file [experimental]"),
91       clEnumValN(TargetMachine::CGFT_Null, "null",
92                  "Emit nothing, for performance testing"),
93       clEnumValEnd));
94
95cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
96                       cl::desc("Do not verify input module"));
97
98
99static cl::opt<bool>
100DisableRedZone("disable-red-zone",
101  cl::desc("Do not emit code that uses the red zone."),
102  cl::init(false));
103
104static cl::opt<bool>
105NoImplicitFloats("no-implicit-float",
106  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
107  cl::init(false));
108
109// GetFileNameRoot - Helper function to get the basename of a filename.
110static inline std::string
111GetFileNameRoot(const std::string &InputFilename) {
112  std::string IFN = InputFilename;
113  std::string outputFilename;
114  int Len = IFN.length();
115  if ((Len > 2) &&
116      IFN[Len-3] == '.' &&
117      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
118       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
119    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
120  } else {
121    outputFilename = IFN;
122  }
123  return outputFilename;
124}
125
126static tool_output_file *GetOutputStream(const char *TargetName,
127                                         Triple::OSType OS,
128                                         const char *ProgName) {
129  // If we don't yet have an output filename, make one.
130  if (OutputFilename.empty()) {
131    if (InputFilename == "-")
132      OutputFilename = "-";
133    else {
134      OutputFilename = GetFileNameRoot(InputFilename);
135
136      switch (FileType) {
137      default: assert(0 && "Unknown file type");
138      case TargetMachine::CGFT_AssemblyFile:
139        if (TargetName[0] == 'c') {
140          if (TargetName[1] == 0)
141            OutputFilename += ".cbe.c";
142          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
143            OutputFilename += ".cpp";
144          else
145            OutputFilename += ".s";
146        } else
147          OutputFilename += ".s";
148        break;
149      case TargetMachine::CGFT_ObjectFile:
150        if (OS == Triple::Win32)
151          OutputFilename += ".obj";
152        else
153          OutputFilename += ".o";
154        break;
155      case TargetMachine::CGFT_Null:
156        OutputFilename += ".null";
157        break;
158      }
159    }
160  }
161
162  // Decide if we need "binary" output.
163  bool Binary = false;
164  switch (FileType) {
165  default: assert(0 && "Unknown file type");
166  case TargetMachine::CGFT_AssemblyFile:
167    break;
168  case TargetMachine::CGFT_ObjectFile:
169  case TargetMachine::CGFT_Null:
170    Binary = true;
171    break;
172  }
173
174  // Open the file.
175  std::string error;
176  unsigned OpenFlags = 0;
177  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
178  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
179                                                 OpenFlags);
180  if (!error.empty()) {
181    errs() << error << '\n';
182    delete FDOut;
183    return 0;
184  }
185
186  return FDOut;
187}
188
189// main - Entry point for the llc compiler.
190//
191int main(int argc, char **argv) {
192  sys::PrintStackTraceOnErrorSignal();
193  PrettyStackTraceProgram X(argc, argv);
194
195  // Enable debug stream buffering.
196  EnableDebugBuffering = true;
197
198  LLVMContext &Context = getGlobalContext();
199  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
200
201  // Initialize targets first, so that --version shows registered targets.
202  InitializeAllTargets();
203  InitializeAllAsmPrinters();
204  InitializeAllAsmParsers();
205
206  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
207
208  // Load the module to be compiled...
209  SMDiagnostic Err;
210  std::auto_ptr<Module> M;
211
212  M.reset(ParseIRFile(InputFilename, Err, Context));
213  if (M.get() == 0) {
214    Err.Print(argv[0], errs());
215    return 1;
216  }
217  Module &mod = *M.get();
218
219  // If we are supposed to override the target triple, do so now.
220  if (!TargetTriple.empty())
221    mod.setTargetTriple(Triple::normalize(TargetTriple));
222
223  Triple TheTriple(mod.getTargetTriple());
224  if (TheTriple.getTriple().empty())
225    TheTriple.setTriple(sys::getHostTriple());
226
227  // Allocate target machine.  First, check whether the user has explicitly
228  // specified an architecture to compile for. If so we have to look it up by
229  // name, because it might be a backend that has no mapping to a target triple.
230  const Target *TheTarget = 0;
231  if (!MArch.empty()) {
232    for (TargetRegistry::iterator it = TargetRegistry::begin(),
233           ie = TargetRegistry::end(); it != ie; ++it) {
234      if (MArch == it->getName()) {
235        TheTarget = &*it;
236        break;
237      }
238    }
239
240    if (!TheTarget) {
241      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
242      return 1;
243    }
244
245    // Adjust the triple to match (if known), otherwise stick with the
246    // module/host triple.
247    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
248    if (Type != Triple::UnknownArch)
249      TheTriple.setArch(Type);
250  } else {
251    std::string Err;
252    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
253    if (TheTarget == 0) {
254      errs() << argv[0] << ": error auto-selecting target for module '"
255             << Err << "'.  Please use the -march option to explicitly "
256             << "pick a target.\n";
257      return 1;
258    }
259  }
260
261  // Package up features to be passed to target/subtarget
262  std::string FeaturesStr;
263  if (MCPU.size() || MAttrs.size()) {
264    SubtargetFeatures Features;
265    Features.setCPU(MCPU);
266    for (unsigned i = 0; i != MAttrs.size(); ++i)
267      Features.AddFeature(MAttrs[i]);
268    FeaturesStr = Features.getString();
269  }
270
271  std::auto_ptr<TargetMachine>
272    target(TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr));
273  assert(target.get() && "Could not allocate target machine!");
274  TargetMachine &Target = *target.get();
275
276  // Figure out where we are going to send the output...
277  OwningPtr<tool_output_file> Out
278    (GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
279  if (!Out) return 1;
280
281  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
282  switch (OptLevel) {
283  default:
284    errs() << argv[0] << ": invalid optimization level.\n";
285    return 1;
286  case ' ': break;
287  case '0': OLvl = CodeGenOpt::None; break;
288  case '1': OLvl = CodeGenOpt::Less; break;
289  case '2': OLvl = CodeGenOpt::Default; break;
290  case '3': OLvl = CodeGenOpt::Aggressive; break;
291  }
292
293  // Build up all of the passes that we want to do to the module.
294  PassManager PM;
295
296  // Add the target data from the target machine, if it exists, or the module.
297  if (const TargetData *TD = Target.getTargetData())
298    PM.add(new TargetData(*TD));
299  else
300    PM.add(new TargetData(&mod));
301
302  // Override default to generate verbose assembly.
303  Target.setAsmVerbosityDefault(true);
304
305  if (RelaxAll) {
306    if (FileType != TargetMachine::CGFT_ObjectFile)
307      errs() << argv[0]
308             << ": warning: ignoring -mc-relax-all because filetype != obj";
309    else
310      Target.setMCRelaxAll(true);
311  }
312
313  {
314    formatted_raw_ostream FOS(Out->os());
315
316    // Ask the target to add backend passes as necessary.
317    if (Target.addPassesToEmitFile(PM, FOS, FileType, OLvl, NoVerify)) {
318      errs() << argv[0] << ": target does not support generation of this"
319             << " file type!\n";
320      return 1;
321    }
322
323    PM.run(mod);
324  }
325
326  // Declare success.
327  Out->keep();
328
329  return 0;
330}
331