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
17#include "llvm/ADT/Triple.h"
18#include "llvm/CodeGen/CommandFlags.h"
19#include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
20#include "llvm/CodeGen/LinkAllCodegenComponents.h"
21#include "llvm/IR/DataLayout.h"
22#include "llvm/IR/IRPrintingPasses.h"
23#include "llvm/IR/LLVMContext.h"
24#include "llvm/IR/Module.h"
25#include "llvm/IRReader/IRReader.h"
26#include "llvm/MC/SubtargetFeature.h"
27#include "llvm/Pass.h"
28#include "llvm/PassManager.h"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Support/Debug.h"
31#include "llvm/Support/FileSystem.h"
32#include "llvm/Support/FormattedStream.h"
33#include "llvm/Support/Host.h"
34#include "llvm/Support/ManagedStatic.h"
35#include "llvm/Support/PluginLoader.h"
36#include "llvm/Support/PrettyStackTrace.h"
37#include "llvm/Support/Signals.h"
38#include "llvm/Support/SourceMgr.h"
39#include "llvm/Support/TargetRegistry.h"
40#include "llvm/Support/TargetSelect.h"
41#include "llvm/Support/ToolOutputFile.h"
42#include "llvm/Target/TargetLibraryInfo.h"
43#include "llvm/Target/TargetMachine.h"
44#include <memory>
45using namespace llvm;
46
47// General options for llc.  Other pass-specific options are specified
48// within the corresponding llc passes, and target-specific options
49// and back-end code generation options are specified with the target machine.
50//
51static cl::opt<std::string>
52InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
53
54static cl::opt<std::string>
55OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
56
57static cl::opt<unsigned>
58TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
59                 cl::value_desc("N"),
60                 cl::desc("Repeat compilation N times for timing"));
61
62static cl::opt<bool>
63NoIntegratedAssembler("no-integrated-as", cl::Hidden,
64                      cl::desc("Disable integrated assembler"));
65
66// Determine optimization level.
67static cl::opt<char>
68OptLevel("O",
69         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
70                  "(default = '-O2')"),
71         cl::Prefix,
72         cl::ZeroOrMore,
73         cl::init(' '));
74
75static cl::opt<std::string>
76TargetTriple("mtriple", cl::desc("Override target triple for module"));
77
78static cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
79                              cl::desc("Do not verify input module"));
80
81static cl::opt<bool> DisableSimplifyLibCalls("disable-simplify-libcalls",
82                                             cl::desc("Disable simplify-libcalls"));
83
84static cl::opt<bool> ShowMCEncoding("show-mc-encoding", cl::Hidden,
85                                    cl::desc("Show encoding in .s output"));
86
87static cl::opt<bool> EnableDwarfDirectory(
88    "enable-dwarf-directory", cl::Hidden,
89    cl::desc("Use .file directives with an explicit directory."));
90
91static cl::opt<bool> AsmVerbose("asm-verbose",
92                                cl::desc("Add comments to directives."),
93                                cl::init(true));
94
95static int compileModule(char **, LLVMContext &);
96
97// GetFileNameRoot - Helper function to get the basename of a filename.
98static inline std::string
99GetFileNameRoot(const std::string &InputFilename) {
100  std::string IFN = InputFilename;
101  std::string outputFilename;
102  int Len = IFN.length();
103  if ((Len > 2) &&
104      IFN[Len-3] == '.' &&
105      ((IFN[Len-2] == 'b' && IFN[Len-1] == 'c') ||
106       (IFN[Len-2] == 'l' && IFN[Len-1] == 'l'))) {
107    outputFilename = std::string(IFN.begin(), IFN.end()-3); // s/.bc/.s/
108  } else {
109    outputFilename = IFN;
110  }
111  return outputFilename;
112}
113
114static tool_output_file *GetOutputStream(const char *TargetName,
115                                         Triple::OSType OS,
116                                         const char *ProgName) {
117  // If we don't yet have an output filename, make one.
118  if (OutputFilename.empty()) {
119    if (InputFilename == "-")
120      OutputFilename = "-";
121    else {
122      OutputFilename = GetFileNameRoot(InputFilename);
123
124      switch (FileType) {
125      case TargetMachine::CGFT_AssemblyFile:
126        if (TargetName[0] == 'c') {
127          if (TargetName[1] == 0)
128            OutputFilename += ".cbe.c";
129          else if (TargetName[1] == 'p' && TargetName[2] == 'p')
130            OutputFilename += ".cpp";
131          else
132            OutputFilename += ".s";
133        } else
134          OutputFilename += ".s";
135        break;
136      case TargetMachine::CGFT_ObjectFile:
137        if (OS == Triple::Win32)
138          OutputFilename += ".obj";
139        else
140          OutputFilename += ".o";
141        break;
142      case TargetMachine::CGFT_Null:
143        OutputFilename += ".null";
144        break;
145      }
146    }
147  }
148
149  // Decide if we need "binary" output.
150  bool Binary = false;
151  switch (FileType) {
152  case TargetMachine::CGFT_AssemblyFile:
153    break;
154  case TargetMachine::CGFT_ObjectFile:
155  case TargetMachine::CGFT_Null:
156    Binary = true;
157    break;
158  }
159
160  // Open the file.
161  std::string error;
162  sys::fs::OpenFlags OpenFlags = sys::fs::F_None;
163  if (!Binary)
164    OpenFlags |= sys::fs::F_Text;
165  tool_output_file *FDOut = new tool_output_file(OutputFilename.c_str(), error,
166                                                 OpenFlags);
167  if (!error.empty()) {
168    errs() << error << '\n';
169    delete FDOut;
170    return nullptr;
171  }
172
173  return FDOut;
174}
175
176// main - Entry point for the llc compiler.
177//
178int main(int argc, char **argv) {
179  sys::PrintStackTraceOnErrorSignal();
180  PrettyStackTraceProgram X(argc, argv);
181
182  // Enable debug stream buffering.
183  EnableDebugBuffering = true;
184
185  LLVMContext &Context = getGlobalContext();
186  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
187
188  // Initialize targets first, so that --version shows registered targets.
189  InitializeAllTargets();
190  InitializeAllTargetMCs();
191  InitializeAllAsmPrinters();
192  InitializeAllAsmParsers();
193
194  // Initialize codegen and IR passes used by llc so that the -print-after,
195  // -print-before, and -stop-after options work.
196  PassRegistry *Registry = PassRegistry::getPassRegistry();
197  initializeCore(*Registry);
198  initializeCodeGen(*Registry);
199  initializeLoopStrengthReducePass(*Registry);
200  initializeLowerIntrinsicsPass(*Registry);
201  initializeUnreachableBlockElimPass(*Registry);
202
203  // Register the target printer for --version.
204  cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
205
206  cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
207
208  // Compile the module TimeCompilations times to give better compile time
209  // metrics.
210  for (unsigned I = TimeCompilations; I; --I)
211    if (int RetVal = compileModule(argv, Context))
212      return RetVal;
213  return 0;
214}
215
216static int compileModule(char **argv, LLVMContext &Context) {
217  // Load the module to be compiled...
218  SMDiagnostic Err;
219  std::unique_ptr<Module> M;
220  Module *mod = nullptr;
221  Triple TheTriple;
222
223  bool SkipModule = MCPU == "help" ||
224                    (!MAttrs.empty() && MAttrs.front() == "help");
225
226  // If user asked for the 'native' CPU, autodetect here. If autodection fails,
227  // this will set the CPU to an empty string which tells the target to
228  // pick a basic default.
229  if (MCPU == "native")
230    MCPU = sys::getHostCPUName();
231
232  // If user just wants to list available options, skip module loading
233  if (!SkipModule) {
234    M.reset(ParseIRFile(InputFilename, Err, Context));
235    mod = M.get();
236    if (mod == nullptr) {
237      Err.print(argv[0], errs());
238      return 1;
239    }
240
241    // If we are supposed to override the target triple, do so now.
242    if (!TargetTriple.empty())
243      mod->setTargetTriple(Triple::normalize(TargetTriple));
244    TheTriple = Triple(mod->getTargetTriple());
245  } else {
246    TheTriple = Triple(Triple::normalize(TargetTriple));
247  }
248
249  if (TheTriple.getTriple().empty())
250    TheTriple.setTriple(sys::getDefaultTargetTriple());
251
252  // Get the target specific parser.
253  std::string Error;
254  const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
255                                                         Error);
256  if (!TheTarget) {
257    errs() << argv[0] << ": " << Error;
258    return 1;
259  }
260
261  // Package up features to be passed to target/subtarget
262  std::string FeaturesStr;
263  if (MAttrs.size()) {
264    SubtargetFeatures Features;
265    for (unsigned i = 0; i != MAttrs.size(); ++i)
266      Features.AddFeature(MAttrs[i]);
267    FeaturesStr = Features.getString();
268  }
269
270  CodeGenOpt::Level OLvl = CodeGenOpt::Default;
271  switch (OptLevel) {
272  default:
273    errs() << argv[0] << ": invalid optimization level.\n";
274    return 1;
275  case ' ': break;
276  case '0': OLvl = CodeGenOpt::None; break;
277  case '1': OLvl = CodeGenOpt::Less; break;
278  case '2': OLvl = CodeGenOpt::Default; break;
279  case '3': OLvl = CodeGenOpt::Aggressive; break;
280  }
281
282  TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
283  Options.DisableIntegratedAS = NoIntegratedAssembler;
284  Options.MCOptions.ShowMCEncoding = ShowMCEncoding;
285  Options.MCOptions.MCUseDwarfDirectory = EnableDwarfDirectory;
286  Options.MCOptions.AsmVerbose = AsmVerbose;
287
288  std::unique_ptr<TargetMachine> target(
289      TheTarget->createTargetMachine(TheTriple.getTriple(), MCPU, FeaturesStr,
290                                     Options, RelocModel, CMModel, OLvl));
291  assert(target.get() && "Could not allocate target machine!");
292
293  // If we don't have a module then just exit now. We do this down
294  // here since the CPU/Feature help is underneath the target machine
295  // creation.
296  if (SkipModule)
297    return 0;
298
299  assert(mod && "Should have exited if we didn't have a module!");
300  TargetMachine &Target = *target.get();
301
302  if (GenerateSoftFloatCalls)
303    FloatABIForCalls = FloatABI::Soft;
304
305  // Figure out where we are going to send the output.
306  std::unique_ptr<tool_output_file> Out(
307      GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]));
308  if (!Out) return 1;
309
310  // Build up all of the passes that we want to do to the module.
311  PassManager PM;
312
313  // Add an appropriate TargetLibraryInfo pass for the module's triple.
314  TargetLibraryInfo *TLI = new TargetLibraryInfo(TheTriple);
315  if (DisableSimplifyLibCalls)
316    TLI->disableAllFunctions();
317  PM.add(TLI);
318
319  // Add the target data from the target machine, if it exists, or the module.
320  if (const DataLayout *DL = Target.getDataLayout())
321    mod->setDataLayout(DL);
322  PM.add(new DataLayoutPass(mod));
323
324  if (RelaxAll.getNumOccurrences() > 0 &&
325      FileType != TargetMachine::CGFT_ObjectFile)
326    errs() << argv[0]
327             << ": warning: ignoring -mc-relax-all because filetype != obj";
328
329  {
330    formatted_raw_ostream FOS(Out->os());
331
332    AnalysisID StartAfterID = nullptr;
333    AnalysisID StopAfterID = nullptr;
334    const PassRegistry *PR = PassRegistry::getPassRegistry();
335    if (!StartAfter.empty()) {
336      const PassInfo *PI = PR->getPassInfo(StartAfter);
337      if (!PI) {
338        errs() << argv[0] << ": start-after pass is not registered.\n";
339        return 1;
340      }
341      StartAfterID = PI->getTypeInfo();
342    }
343    if (!StopAfter.empty()) {
344      const PassInfo *PI = PR->getPassInfo(StopAfter);
345      if (!PI) {
346        errs() << argv[0] << ": stop-after pass is not registered.\n";
347        return 1;
348      }
349      StopAfterID = PI->getTypeInfo();
350    }
351
352    // Ask the target to add backend passes as necessary.
353    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify,
354                                   StartAfterID, StopAfterID)) {
355      errs() << argv[0] << ": target does not support generation of this"
356             << " file type!\n";
357      return 1;
358    }
359
360    // Before executing passes, print the final values of the LLVM options.
361    cl::PrintOptionValues();
362
363    PM.run(*mod);
364  }
365
366  // Declare success.
367  Out->keep();
368
369  return 0;
370}
371