llc.cpp revision 33ef2bb2680de321cd6d2056a1ecce635e6d1c75 
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/Target/SubtargetFeature.h"
20#include "llvm/Target/TargetData.h"
21#include "llvm/Target/TargetMachine.h"
22#include "llvm/Target/TargetMachineRegistry.h"
23#include "llvm/Transforms/Scalar.h"
24#include "llvm/Module.h"
25#include "llvm/ModuleProvider.h"
26#include "llvm/PassManager.h"
27#include "llvm/Pass.h"
28#include "llvm/Support/CommandLine.h"
29#include "llvm/Support/ManagedStatic.h"
30#include "llvm/Support/MemoryBuffer.h"
31#include "llvm/Support/PluginLoader.h"
32#include "llvm/Support/FileUtilities.h"
33#include "llvm/Analysis/Verifier.h"
34#include "llvm/System/Signals.h"
35#include "llvm/Config/config.h"
36#include "llvm/LinkAllVMCore.h"
37#include <fstream>
38#include <iostream>
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
52static cl::opt<bool> Force("f", cl::desc("Overwrite output files"));
53
54static cl::opt<bool> Fast("fast",
55      cl::desc("Generate code quickly, potentially sacrificing code quality"));
56
57static cl::opt<std::string>
58TargetTriple("mtriple", cl::desc("Override target triple for module"));
59
60static cl::opt<const TargetMachineRegistry::entry*, false,
61               TargetMachineRegistry::Parser>
62MArch("march", cl::desc("Architecture to generate code for:"));
63
64static cl::opt<std::string>
65MCPU("mcpu",
66  cl::desc("Target a specific cpu type (-mcpu=help for details)"),
67  cl::value_desc("cpu-name"),
68  cl::init(""));
69
70static cl::list<std::string>
71MAttrs("mattr",
72  cl::CommaSeparated,
73  cl::desc("Target specific attributes (-mattr=help for details)"),
74  cl::value_desc("a1,+a2,-a3,..."));
75
76cl::opt<TargetMachine::CodeGenFileType>
77FileType("filetype", cl::init(TargetMachine::AssemblyFile),
78  cl::desc("Choose a file type (not all types are supported by all targets):"),
79  cl::values(
80       clEnumValN(TargetMachine::AssemblyFile,    "asm",
81                  "  Emit an assembly ('.s') file"),
82       clEnumValN(TargetMachine::ObjectFile,    "obj",
83                  "  Emit a native object ('.o') file [experimental]"),
84       clEnumValN(TargetMachine::DynamicLibrary, "dynlib",
85                  "  Emit a native dynamic library ('.so') file"
86                  " [experimental]"),
87       clEnumValEnd));
88
89cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
90                       cl::desc("Do not verify input module"));
91
92
93// GetFileNameRoot - Helper function to get the basename of a filename.
94static inline std::string
95GetFileNameRoot(const std::string &InputFilename) {
96  std::string IFN = InputFilename;
97  std::string outputFilename;
98  int Len = IFN.length();
99  if ((Len > 2) &&
100      IFN[Len-3] == '.' && IFN[Len-2] == 'b' && IFN[Len-1] == 'c') {
101    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
102  } else {
103    outputFilename = IFN;
104  }
105  return outputFilename;
106}
107
108static std::ostream *GetOutputStream(const char *ProgName) {
109  if (OutputFilename != "") {
110    if (OutputFilename == "-")
111      return &std::cout;
112
113    // Specified an output filename?
114    if (!Force && std::ifstream(OutputFilename.c_str())) {
115      // If force is not specified, make sure not to overwrite a file!
116      std::cerr << ProgName << ": error opening '" << OutputFilename
117                << "': file exists!\n"
118                << "Use -f command line argument to force output\n";
119      return 0;
120    }
121    // Make sure that the Out file gets unlinked from the disk if we get a
122    // SIGINT
123    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
124
125    return new std::ofstream(OutputFilename.c_str());
126  }
127
128  if (InputFilename == "-") {
129    OutputFilename = "-";
130    return &std::cout;
131  }
132
133  OutputFilename = GetFileNameRoot(InputFilename);
134
135  switch (FileType) {
136  case TargetMachine::AssemblyFile:
137    if (MArch->Name[0] != 'c' || MArch->Name[1] != 0)  // not CBE
138      OutputFilename += ".s";
139    else
140      OutputFilename += ".cbe.c";
141    break;
142  case TargetMachine::ObjectFile:
143    OutputFilename += ".o";
144    break;
145  case TargetMachine::DynamicLibrary:
146    OutputFilename += LTDL_SHLIB_EXT;
147    break;
148  }
149
150  if (!Force && std::ifstream(OutputFilename.c_str())) {
151    // If force is not specified, make sure not to overwrite a file!
152    std::cerr << ProgName << ": error opening '" << OutputFilename
153                          << "': file exists!\n"
154                          << "Use -f command line argument to force output\n";
155    return 0;
156  }
157
158  // Make sure that the Out file gets unlinked from the disk if we get a
159  // SIGINT
160  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
161
162  std::ostream *Out = new std::ofstream(OutputFilename.c_str());
163  if (!Out->good()) {
164    std::cerr << ProgName << ": error opening " << OutputFilename << "!\n";
165    delete Out;
166    return 0;
167  }
168
169  return Out;
170}
171
172// main - Entry point for the llc compiler.
173//
174int main(int argc, char **argv) {
175  llvm_shutdown_obj X;  // Call llvm_shutdown() on exit.
176  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
177  sys::PrintStackTraceOnErrorSignal();
178
179  // Load the module to be compiled...
180  std::string ErrorMessage;
181  std::auto_ptr<Module> M;
182
183  std::auto_ptr<MemoryBuffer> Buffer(
184                   MemoryBuffer::getFileOrSTDIN(InputFilename, &ErrorMessage));
185  if (Buffer.get())
186    M.reset(ParseBitcodeFile(Buffer.get(), &ErrorMessage));
187  if (M.get() == 0) {
188    std::cerr << argv[0] << ": bitcode didn't read correctly.\n";
189    std::cerr << "Reason: " << ErrorMessage << "\n";
190    return 1;
191  }
192  Module &mod = *M.get();
193
194  // If we are supposed to override the target triple, do so now.
195  if (!TargetTriple.empty())
196    mod.setTargetTriple(TargetTriple);
197
198  // Allocate target machine.  First, check whether the user has
199  // explicitly specified an architecture to compile for.
200  if (MArch == 0) {
201    std::string Err;
202    MArch = TargetMachineRegistry::getClosestStaticTargetForModule(mod, Err);
203    if (MArch == 0) {
204      std::cerr << argv[0] << ": error auto-selecting target for module '"
205                << Err << "'.  Please use the -march option to explicitly "
206                << "pick a target.\n";
207      return 1;
208    }
209  }
210
211  // Package up features to be passed to target/subtarget
212  std::string FeaturesStr;
213  if (MCPU.size() || MAttrs.size()) {
214    SubtargetFeatures Features;
215    Features.setCPU(MCPU);
216    for (unsigned i = 0; i != MAttrs.size(); ++i)
217      Features.AddFeature(MAttrs[i]);
218    FeaturesStr = Features.getString();
219  }
220
221  std::auto_ptr<TargetMachine> target(MArch->CtorFn(mod, FeaturesStr));
222  assert(target.get() && "Could not allocate target machine!");
223  TargetMachine &Target = *target.get();
224
225  // Figure out where we are going to send the output...
226  std::ostream *Out = GetOutputStream(argv[0]);
227  if (Out == 0) return 1;
228
229  // If this target requires addPassesToEmitWholeFile, do it now.  This is
230  // used by strange things like the C backend.
231  if (Target.WantsWholeFile()) {
232    PassManager PM;
233    PM.add(new TargetData(*Target.getTargetData()));
234    if (!NoVerify)
235      PM.add(createVerifierPass());
236
237    // Ask the target to add backend passes as necessary.
238    if (Target.addPassesToEmitWholeFile(PM, *Out, FileType, Fast)) {
239      std::cerr << argv[0] << ": target does not support generation of this"
240                << " file type!\n";
241      if (Out != &std::cout) delete Out;
242      // And the Out file is empty and useless, so remove it now.
243      sys::Path(OutputFilename).eraseFromDisk();
244      return 1;
245    }
246    PM.run(mod);
247  } else {
248    // Build up all of the passes that we want to do to the module.
249    ExistingModuleProvider Provider(M.release());
250    FunctionPassManager Passes(&Provider);
251    Passes.add(new TargetData(*Target.getTargetData()));
252
253#ifndef NDEBUG
254    if (!NoVerify)
255      Passes.add(createVerifierPass());
256#endif
257
258    // Ask the target to add backend passes as necessary.
259    MachineCodeEmitter *MCE = 0;
260
261    switch (Target.addPassesToEmitFile(Passes, *Out, FileType, Fast)) {
262    default:
263      assert(0 && "Invalid file model!");
264      return 1;
265    case FileModel::Error:
266      std::cerr << argv[0] << ": target does not support generation of this"
267                << " file type!\n";
268      if (Out != &std::cout) delete Out;
269      // And the Out file is empty and useless, so remove it now.
270      sys::Path(OutputFilename).eraseFromDisk();
271      return 1;
272    case FileModel::AsmFile:
273      break;
274    case FileModel::MachOFile:
275      MCE = AddMachOWriter(Passes, *Out, Target);
276      break;
277    case FileModel::ElfFile:
278      MCE = AddELFWriter(Passes, *Out, Target);
279      break;
280    }
281
282    if (Target.addPassesToEmitFileFinish(Passes, MCE, Fast)) {
283      std::cerr << argv[0] << ": target does not support generation of this"
284                << " file type!\n";
285      if (Out != &std::cout) delete Out;
286      // And the Out file is empty and useless, so remove it now.
287      sys::Path(OutputFilename).eraseFromDisk();
288      return 1;
289    }
290
291    Passes.doInitialization();
292
293    // Run our queue of passes all at once now, efficiently.
294    // TODO: this could lazily stream functions out of the module.
295    for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I)
296      if (!I->isDeclaration())
297        Passes.run(*I);
298
299    Passes.doFinalization();
300  }
301
302  // Delete the ostream if it's not a stdout stream
303  if (Out != &std::cout) delete Out;
304
305  return 0;
306}
307