llc.cpp revision 195340 
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/Bitcode/ReaderWriter.h"
17#include "llvm/CodeGen/FileWriters.h"
18#include "llvm/CodeGen/LinkAllCodegenComponents.h"
19#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
20#include "llvm/Target/SubtargetFeature.h"
21#include "llvm/Target/TargetData.h"
22#include "llvm/Target/TargetMachine.h"
23#include "llvm/Target/TargetMachineRegistry.h"
24#include "llvm/Transforms/Scalar.h"
25#include "llvm/LLVMContext.h"
26#include "llvm/Module.h"
27#include "llvm/ModuleProvider.h"
28#include "llvm/PassManager.h"
29#include "llvm/Pass.h"
30#include "llvm/Support/CommandLine.h"
31#include "llvm/Support/FileUtilities.h"
32#include "llvm/Support/ManagedStatic.h"
33#include "llvm/Support/MemoryBuffer.h"
34#include "llvm/Support/PluginLoader.h"
35#include "llvm/Support/PrettyStackTrace.h"
36#include "llvm/Support/RegistryParser.h"
37#include "llvm/Support/raw_ostream.h"
38#include "llvm/Analysis/Verifier.h"
39#include "llvm/System/Signals.h"
40#include "llvm/Config/config.h"
41#include "llvm/LinkAllVMCore.h"
42#include "llvm/Target/TargetSelect.h"
43#include <fstream>
44#include <iostream>
45#include <memory>
46using namespace llvm;
47
48// General options for llc.  Other pass-specific options are specified
49// within the corresponding llc passes, and target-specific options
50// and back-end code generation options are specified with the target machine.
51//
52static cl::opt<std::string>
53InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
54
55static cl::opt<std::string>
56OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
57
58static cl::opt<bool> Force("f", cl::desc("Overwrite output files"));
59
60// Determine optimization level.
61static cl::opt<char>
62OptLevel("O",
63         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
64                  "(default = '-O2')"),
65         cl::Prefix,
66         cl::ZeroOrMore,
67         cl::init(' '));
68
69static cl::opt<std::string>
70TargetTriple("mtriple", cl::desc("Override target triple for module"));
71
72static cl::opt<const TargetMachineRegistry::entry*, false,
73               RegistryParser<TargetMachine> >
74MArch("march", cl::desc("Architecture to generate code for:"));
75
76static cl::opt<std::string>
77MCPU("mcpu",
78  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
79  cl::value_desc("cpu-name"),
80  cl::init(""));
81
82static cl::list<std::string>
83MAttrs("mattr",
84  cl::CommaSeparated,
85  cl::desc("Target specific attributes (-mattr=help for details)"),
86  cl::value_desc("a1,+a2,-a3,..."));
87
88cl::opt<TargetMachine::CodeGenFileType>
89FileType("filetype", cl::init(TargetMachine::AssemblyFile),
90  cl::desc("Choose a file type (not all types are supported by all targets):"),
91  cl::values(
92       clEnumValN(TargetMachine::AssemblyFile, "asm",
93                  "Emit an assembly ('.s') file"),
94       clEnumValN(TargetMachine::ObjectFile, "obj",
95                  "Emit a native object ('.o') file [experimental]"),
96       clEnumValN(TargetMachine::DynamicLibrary, "dynlib",
97                  "Emit a native dynamic library ('.so') file"
98                  " [experimental]"),
99       clEnumValEnd));
100
101cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
102                       cl::desc("Do not verify input module"));
103
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] == '.' && IFN[Len-2] == 'b' && IFN[Len-1] == 'c') {
123    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
124  } else {
125    outputFilename = IFN;
126  }
127  return outputFilename;
128}
129
130static raw_ostream *GetOutputStream(const char *ProgName) {
131  if (OutputFilename != "") {
132    if (OutputFilename == "-")
133      return &outs();
134
135    // Specified an output filename?
136    if (!Force && std::ifstream(OutputFilename.c_str())) {
137      // If force is not specified, make sure not to overwrite a file!
138      std::cerr << ProgName << ": error opening '" << OutputFilename
139                << "': file exists!\n"
140                << "Use -f command line argument to force output\n";
141      return 0;
142    }
143    // Make sure that the Out file gets unlinked from the disk if we get a
144    // SIGINT
145    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
146
147    std::string error;
148    raw_ostream *Out = new raw_fd_ostream(OutputFilename.c_str(), true, error);
149    if (!error.empty()) {
150      std::cerr << error << '\n';
151      delete Out;
152      return 0;
153    }
154
155    return Out;
156  }
157
158  if (InputFilename == "-") {
159    OutputFilename = "-";
160    return &outs();
161  }
162
163  OutputFilename = GetFileNameRoot(InputFilename);
164
165  bool Binary = false;
166  switch (FileType) {
167  case TargetMachine::AssemblyFile:
168    if (MArch->Name[0] == 'c') {
169      if (MArch->Name[1] == 0)
170        OutputFilename += ".cbe.c";
171      else if (MArch->Name[1] == 'p' && MArch->Name[2] == 'p')
172        OutputFilename += ".cpp";
173      else
174        OutputFilename += ".s";
175    } else
176      OutputFilename += ".s";
177    break;
178  case TargetMachine::ObjectFile:
179    OutputFilename += ".o";
180    Binary = true;
181    break;
182  case TargetMachine::DynamicLibrary:
183    OutputFilename += LTDL_SHLIB_EXT;
184    Binary = true;
185    break;
186  }
187
188  if (!Force && std::ifstream(OutputFilename.c_str())) {
189    // If force is not specified, make sure not to overwrite a file!
190    std::cerr << ProgName << ": error opening '" << OutputFilename
191                          << "': file exists!\n"
192                          << "Use -f command line argument to force output\n";
193    return 0;
194  }
195
196  // Make sure that the Out file gets unlinked from the disk if we get a
197  // SIGINT
198  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
199
200  std::string error;
201  raw_ostream *Out = new raw_fd_ostream(OutputFilename.c_str(), Binary, error);
202  if (!error.empty()) {
203    std::cerr << error << '\n';
204    delete Out;
205    return 0;
206  }
207
208  return Out;
209}
210
211// main - Entry point for the llc compiler.
212//
213int main(int argc, char **argv) {
214  sys::PrintStackTraceOnErrorSignal();
215  PrettyStackTraceProgram X(argc, argv);
216  LLVMContext Context;
217  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
218  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
219
220  InitializeAllTargets();
221  InitializeAllAsmPrinters();
222
223  // Load the module to be compiled...
224  std::string ErrorMessage;
225  std::auto_ptr<Module> M;
226
227  std::auto_ptr<MemoryBuffer> Buffer(
228                   MemoryBuffer::getFileOrSTDIN(InputFilename, &ErrorMessage));
229  if (Buffer.get())
230    M.reset(ParseBitcodeFile(Buffer.get(), Context, &ErrorMessage));
231  if (M.get() == 0) {
232    std::cerr << argv[0] << ": bitcode didn't read correctly.\n";
233    std::cerr << "Reason: " << ErrorMessage << "\n";
234    return 1;
235  }
236  Module &mod = *M.get();
237
238  // If we are supposed to override the target triple, do so now.
239  if (!TargetTriple.empty())
240    mod.setTargetTriple(TargetTriple);
241
242  // Allocate target machine.  First, check whether the user has
243  // explicitly specified an architecture to compile for.
244  if (MArch == 0) {
245    std::string Err;
246    MArch = TargetMachineRegistry::getClosestStaticTargetForModule(mod, Err);
247    if (MArch == 0) {
248      std::cerr << argv[0] << ": error auto-selecting target for module '"
249                << Err << "'.  Please use the -march option to explicitly "
250                << "pick a target.\n";
251      return 1;
252    }
253  }
254
255  // Package up features to be passed to target/subtarget
256  std::string FeaturesStr;
257  if (MCPU.size() || MAttrs.size()) {
258    SubtargetFeatures Features;
259    Features.setCPU(MCPU);
260    for (unsigned i = 0; i != MAttrs.size(); ++i)
261      Features.AddFeature(MAttrs[i]);
262    FeaturesStr = Features.getString();
263  }
264
265  std::auto_ptr<TargetMachine> target(MArch->CtorFn(mod, FeaturesStr));
266  assert(target.get() && "Could not allocate target machine!");
267  TargetMachine &Target = *target.get();
268
269  // Figure out where we are going to send the output...
270  raw_ostream *Out = GetOutputStream(argv[0]);
271  if (Out == 0) return 1;
272
273  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
274  switch (OptLevel) {
275  default:
276    std::cerr << argv[0] << ": invalid optimization level.\n";
277    return 1;
278  case ' ': break;
279  case '0': OLvl = CodeGenOpt::None; break;
280  case '1':
281  case '2': OLvl = CodeGenOpt::Default; break;
282  case '3': OLvl = CodeGenOpt::Aggressive; break;
283  }
284
285  // If this target requires addPassesToEmitWholeFile, do it now.  This is
286  // used by strange things like the C backend.
287  if (Target.WantsWholeFile()) {
288    PassManager PM;
289    PM.add(new TargetData(*Target.getTargetData()));
290    if (!NoVerify)
291      PM.add(createVerifierPass());
292
293    // Ask the target to add backend passes as necessary.
294    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, OLvl)) {
295      std::cerr << argv[0] << ": target does not support generation of this"
296                << " file type!\n";
297      if (Out != &outs()) delete Out;
298      // And the Out file is empty and useless, so remove it now.
299      sys::Path(OutputFilename).eraseFromDisk();
300      return 1;
301    }
302    PM.run(mod);
303  } else {
304    // Build up all of the passes that we want to do to the module.
305    ExistingModuleProvider Provider(M.release());
306    FunctionPassManager Passes(&Provider);
307    Passes.add(new TargetData(*Target.getTargetData()));
308
309#ifndef NDEBUG
310    if (!NoVerify)
311      Passes.add(createVerifierPass());
312#endif
313
314    // Ask the target to add backend passes as necessary.
315    MachineCodeEmitter *MCE = 0;
316
317    // Override default to generate verbose assembly.
318    Target.setAsmVerbosityDefault(true);
319
320    switch (Target.addPassesToEmitFile(Passes, *Out, FileType, OLvl)) {
321    default:
322      assert(0 && "Invalid file model!");
323      return 1;
324    case FileModel::Error:
325      std::cerr << argv[0] << ": target does not support generation of this"
326                << " file type!\n";
327      if (Out != &outs()) delete Out;
328      // And the Out file is empty and useless, so remove it now.
329      sys::Path(OutputFilename).eraseFromDisk();
330      return 1;
331    case FileModel::AsmFile:
332      break;
333    case FileModel::MachOFile:
334      MCE = AddMachOWriter(Passes, *Out, Target);
335      break;
336    case FileModel::ElfFile:
337      MCE = AddELFWriter(Passes, *Out, Target);
338      break;
339    }
340
341    if (Target.addPassesToEmitFileFinish(Passes, MCE, OLvl)) {
342      std::cerr << argv[0] << ": target does not support generation of this"
343                << " file type!\n";
344      if (Out != &outs()) delete Out;
345      // And the Out file is empty and useless, so remove it now.
346      sys::Path(OutputFilename).eraseFromDisk();
347      return 1;
348    }
349
350    Passes.doInitialization();
351
352    // Run our queue of passes all at once now, efficiently.
353    // TODO: this could lazily stream functions out of the module.
354    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
355      if (!I->isDeclaration()) {
356        if (DisableRedZone)
357          I->addFnAttr(Attribute::NoRedZone);
358        if (NoImplicitFloats)
359          I->addFnAttr(Attribute::NoImplicitFloat);
360        Passes.run(*I);
361      }
362
363    Passes.doFinalization();
364  }
365
366  // Delete the ostream if it's not a stdout stream
367  if (Out != &outs()) delete Out;
368
369  return 0;
370}
371