llc.cpp revision 207618 
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/Analysis/Verifier.h"
22#include "llvm/Support/IRReader.h"
23#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
24#include "llvm/CodeGen/LinkAllCodegenComponents.h"
25#include "llvm/Config/config.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/System/Host.h"
33#include "llvm/System/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
79cl::opt<TargetMachine::CodeGenFileType>
80FileType("filetype", cl::init(TargetMachine::CGFT_AssemblyFile),
81  cl::desc("Choose a file type (not all types are supported by all targets):"),
82  cl::values(
83       clEnumValN(TargetMachine::CGFT_AssemblyFile, "asm",
84                  "Emit an assembly ('.s') file"),
85       clEnumValN(TargetMachine::CGFT_ObjectFile, "obj",
86                  "Emit a native object ('.o') file [experimental]"),
87       clEnumValN(TargetMachine::CGFT_Null, "null",
88                  "Emit nothing, for performance testing"),
89       clEnumValEnd));
90
91cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
92                       cl::desc("Do not verify input module"));
93
94
95static cl::opt<bool>
96DisableRedZone("disable-red-zone",
97  cl::desc("Do not emit code that uses the red zone."),
98  cl::init(false));
99
100static cl::opt<bool>
101NoImplicitFloats("no-implicit-float",
102  cl::desc("Don't generate implicit floating point instructions (x86-only)"),
103  cl::init(false));
104
105// GetFileNameRoot - Helper function to get the basename of a filename.
106static inline std::string
107GetFileNameRoot(const std::string &InputFilename) {
108  std::string IFN = InputFilename;
109  std::string outputFilename;
110  int Len = IFN.length();
111  if ((Len > 2) &&
112      IFN[Len-3] == '.' &&
113      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
114       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
115    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
116  } else {
117    outputFilename = IFN;
118  }
119  return outputFilename;
120}
121
122static formatted_raw_ostream *GetOutputStream(const char *TargetName,
123                                              const char *ProgName) {
124  if (OutputFilename != "") {
125    if (OutputFilename == "-")
126      return &fouts();
127
128    // Make sure that the Out file gets unlinked from the disk if we get a
129    // SIGINT
130    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
131
132    std::string error;
133    raw_fd_ostream *FDOut =
134      new raw_fd_ostream(OutputFilename.c_str(), error,
135                         raw_fd_ostream::F_Binary);
136    if (!error.empty()) {
137      errs() << error << '\n';
138      delete FDOut;
139      return 0;
140    }
141    formatted_raw_ostream *Out =
142      new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
143
144    return Out;
145  }
146
147  if (InputFilename == "-") {
148    OutputFilename = "-";
149    return &fouts();
150  }
151
152  OutputFilename = GetFileNameRoot(InputFilename);
153
154  bool Binary = false;
155  switch (FileType) {
156  default: assert(0 && "Unknown file type");
157  case TargetMachine::CGFT_AssemblyFile:
158    if (TargetName[0] == 'c') {
159      if (TargetName[1] == 0)
160        OutputFilename += ".cbe.c";
161      else if (TargetName[1] == 'p' && TargetName[2] == 'p')
162        OutputFilename += ".cpp";
163      else
164        OutputFilename += ".s";
165    } else
166      OutputFilename += ".s";
167    break;
168  case TargetMachine::CGFT_ObjectFile:
169    OutputFilename += ".o";
170    Binary = true;
171    break;
172  case TargetMachine::CGFT_Null:
173    OutputFilename += ".null";
174    Binary = true;
175    break;
176  }
177
178  // Make sure that the Out file gets unlinked from the disk if we get a
179  // SIGINT
180  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
181
182  std::string error;
183  unsigned OpenFlags = 0;
184  if (Binary) OpenFlags |= raw_fd_ostream::F_Binary;
185  raw_fd_ostream *FDOut = new raw_fd_ostream(OutputFilename.c_str(), error,
186                                             OpenFlags);
187  if (!error.empty()) {
188    errs() << error << '\n';
189    delete FDOut;
190    return 0;
191  }
192
193  formatted_raw_ostream *Out =
194    new formatted_raw_ostream(*FDOut, formatted_raw_ostream::DELETE_STREAM);
195
196  return Out;
197}
198
199// main - Entry point for the llc compiler.
200//
201int main(int argc, char **argv) {
202  sys::PrintStackTraceOnErrorSignal();
203  PrettyStackTraceProgram X(argc, argv);
204
205  // Enable debug stream buffering.
206  EnableDebugBuffering = true;
207
208  LLVMContext &Context = getGlobalContext();
209  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
210
211  // Initialize targets first, so that --version shows registered targets.
212  InitializeAllTargets();
213  InitializeAllAsmPrinters();
214  InitializeAllAsmParsers();
215
216  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
217
218  // Load the module to be compiled...
219  SMDiagnostic Err;
220  std::auto_ptr<Module> M;
221
222  M.reset(ParseIRFile(InputFilename, Err, Context));
223  if (M.get() == 0) {
224    Err.Print(argv[0], errs());
225    return 1;
226  }
227  Module &mod = *M.get();
228
229  // If we are supposed to override the target triple, do so now.
230  if (!TargetTriple.empty())
231    mod.setTargetTriple(TargetTriple);
232
233  Triple TheTriple(mod.getTargetTriple());
234  if (TheTriple.getTriple().empty())
235    TheTriple.setTriple(sys::getHostTriple());
236
237  // Allocate target machine.  First, check whether the user has explicitly
238  // specified an architecture to compile for. If so we have to look it up by
239  // name, because it might be a backend that has no mapping to a target triple.
240  const Target *TheTarget = 0;
241  if (!MArch.empty()) {
242    for (TargetRegistry::iterator it = TargetRegistry::begin(),
243           ie = TargetRegistry::end(); it != ie; ++it) {
244      if (MArch == it->getName()) {
245        TheTarget = &*it;
246        break;
247      }
248    }
249
250    if (!TheTarget) {
251      errs() << argv[0] << ": error: invalid target '" << MArch << "'.\n";
252      return 1;
253    }
254
255    // Adjust the triple to match (if known), otherwise stick with the
256    // module/host triple.
257    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
258    if (Type != Triple::UnknownArch)
259      TheTriple.setArch(Type);
260  } else {
261    std::string Err;
262    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Err);
263    if (TheTarget == 0) {
264      errs() << argv[0] << ": error auto-selecting target for module '"
265             << Err << "'.  Please use the -march option to explicitly "
266             << "pick a target.\n";
267      return 1;
268    }
269  }
270
271  // Package up features to be passed to target/subtarget
272  std::string FeaturesStr;
273  if (MCPU.size() || MAttrs.size()) {
274    SubtargetFeatures Features;
275    Features.setCPU(MCPU);
276    for (unsigned i = 0; i != MAttrs.size(); ++i)
277      Features.AddFeature(MAttrs[i]);
278    FeaturesStr = Features.getString();
279  }
280
281  std::auto_ptr<TargetMachine>
282    target(TheTarget->createTargetMachine(TheTriple.getTriple(), FeaturesStr));
283  assert(target.get() && "Could not allocate target machine!");
284  TargetMachine &Target = *target.get();
285
286  // Figure out where we are going to send the output...
287  formatted_raw_ostream *Out = GetOutputStream(TheTarget->getName(), argv[0]);
288  if (Out == 0) return 1;
289
290  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
291  switch (OptLevel) {
292  default:
293    errs() << argv[0] << ": invalid optimization level.\n";
294    return 1;
295  case ' ': break;
296  case '0': OLvl = CodeGenOpt::None; break;
297  case '1': OLvl = CodeGenOpt::Less; break;
298  case '2': OLvl = CodeGenOpt::Default; break;
299  case '3': OLvl = CodeGenOpt::Aggressive; break;
300  }
301
302  // Request that addPassesToEmitFile run the Verifier after running
303  // passes which modify the IR.
304#ifndef NDEBUG
305  bool DisableVerify = false;
306#else
307  bool DisableVerify = true;
308#endif
309
310  // If this target requires addPassesToEmitWholeFile, do it now.  This is
311  // used by strange things like the C backend.
312  if (Target.WantsWholeFile()) {
313    PassManager PM;
314
315    // Add the target data from the target machine, if it exists, or the module.
316    if (const TargetData *TD = Target.getTargetData())
317      PM.add(new TargetData(*TD));
318    else
319      PM.add(new TargetData(&mod));
320
321    if (!NoVerify)
322      PM.add(createVerifierPass());
323
324    // Ask the target to add backend passes as necessary.
325    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, OLvl,
326                                        DisableVerify)) {
327      errs() << argv[0] << ": target does not support generation of this"
328             << " file type!\n";
329      if (Out != &fouts()) delete Out;
330      // And the Out file is empty and useless, so remove it now.
331      sys::Path(OutputFilename).eraseFromDisk();
332      return 1;
333    }
334    PM.run(mod);
335  } else {
336    // Build up all of the passes that we want to do to the module.
337    FunctionPassManager Passes(M.get());
338
339    // Add the target data from the target machine, if it exists, or the module.
340    if (const TargetData *TD = Target.getTargetData())
341      Passes.add(new TargetData(*TD));
342    else
343      Passes.add(new TargetData(&mod));
344
345#ifndef NDEBUG
346    if (!NoVerify)
347      Passes.add(createVerifierPass());
348#endif
349
350    // Override default to generate verbose assembly.
351    Target.setAsmVerbosityDefault(true);
352
353    if (Target.addPassesToEmitFile(Passes, *Out, FileType, OLvl,
354                                   DisableVerify)) {
355      errs() << argv[0] << ": target does not support generation of this"
356             << " file type!\n";
357      if (Out != &fouts()) delete Out;
358      // And the Out file is empty and useless, so remove it now.
359      sys::Path(OutputFilename).eraseFromDisk();
360      return 1;
361    }
362
363    Passes.doInitialization();
364
365    // Run our queue of passes all at once now, efficiently.
366    // TODO: this could lazily stream functions out of the module.
367    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
368      if (!I->isDeclaration()) {
369        if (DisableRedZone)
370          I->addFnAttr(Attribute::NoRedZone);
371        if (NoImplicitFloats)
372          I->addFnAttr(Attribute::NoImplicitFloat);
373        Passes.run(*I);
374      }
375
376    Passes.doFinalization();
377  }
378
379  // Delete the ostream if it's not a stdout stream
380  if (Out != &fouts()) delete Out;
381
382  return 0;
383}
384