1//===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
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#include "clang/CodeGen/BackendUtil.h"
11#include "clang/Basic/Diagnostic.h"
12#include "clang/Basic/TargetOptions.h"
13#include "clang/Basic/LangOptions.h"
14#include "clang/Frontend/CodeGenOptions.h"
15#include "clang/Frontend/FrontendDiagnostic.h"
16#include "llvm/Module.h"
17#include "llvm/PassManager.h"
18#include "llvm/Analysis/Verifier.h"
19#include "llvm/Assembly/PrintModulePass.h"
20#include "llvm/Bitcode/ReaderWriter.h"
21#include "llvm/CodeGen/RegAllocRegistry.h"
22#include "llvm/CodeGen/SchedulerRegistry.h"
23#include "llvm/MC/SubtargetFeature.h"
24#include "llvm/Support/CommandLine.h"
25#include "llvm/Support/FormattedStream.h"
26#include "llvm/Support/PrettyStackTrace.h"
27#include "llvm/Support/TargetRegistry.h"
28#include "llvm/Support/Timer.h"
29#include "llvm/Support/raw_ostream.h"
30#include "llvm/Target/TargetData.h"
31#include "llvm/Target/TargetLibraryInfo.h"
32#include "llvm/Target/TargetMachine.h"
33#include "llvm/Target/TargetOptions.h"
34#include "llvm/Transforms/Instrumentation.h"
35#include "llvm/Transforms/IPO.h"
36#include "llvm/Transforms/IPO/PassManagerBuilder.h"
37#include "llvm/Transforms/Scalar.h"
38using namespace clang;
39using namespace llvm;
40
41namespace {
42
43class EmitAssemblyHelper {
44  DiagnosticsEngine &Diags;
45  const CodeGenOptions &CodeGenOpts;
46  const clang::TargetOptions &TargetOpts;
47  const LangOptions &LangOpts;
48  Module *TheModule;
49
50  Timer CodeGenerationTime;
51
52  mutable PassManager *CodeGenPasses;
53  mutable PassManager *PerModulePasses;
54  mutable FunctionPassManager *PerFunctionPasses;
55
56private:
57  PassManager *getCodeGenPasses() const {
58    if (!CodeGenPasses) {
59      CodeGenPasses = new PassManager();
60      CodeGenPasses->add(new TargetData(TheModule));
61    }
62    return CodeGenPasses;
63  }
64
65  PassManager *getPerModulePasses() const {
66    if (!PerModulePasses) {
67      PerModulePasses = new PassManager();
68      PerModulePasses->add(new TargetData(TheModule));
69    }
70    return PerModulePasses;
71  }
72
73  FunctionPassManager *getPerFunctionPasses() const {
74    if (!PerFunctionPasses) {
75      PerFunctionPasses = new FunctionPassManager(TheModule);
76      PerFunctionPasses->add(new TargetData(TheModule));
77    }
78    return PerFunctionPasses;
79  }
80
81  void CreatePasses();
82
83  /// AddEmitPasses - Add passes necessary to emit assembly or LLVM IR.
84  ///
85  /// \return True on success.
86  bool AddEmitPasses(BackendAction Action, formatted_raw_ostream &OS);
87
88public:
89  EmitAssemblyHelper(DiagnosticsEngine &_Diags,
90                     const CodeGenOptions &CGOpts,
91                     const clang::TargetOptions &TOpts,
92                     const LangOptions &LOpts,
93                     Module *M)
94    : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
95      TheModule(M), CodeGenerationTime("Code Generation Time"),
96      CodeGenPasses(0), PerModulePasses(0), PerFunctionPasses(0) {}
97
98  ~EmitAssemblyHelper() {
99    delete CodeGenPasses;
100    delete PerModulePasses;
101    delete PerFunctionPasses;
102  }
103
104  void EmitAssembly(BackendAction Action, raw_ostream *OS);
105};
106
107}
108
109static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
110  if (Builder.OptLevel > 0)
111    PM.add(createObjCARCAPElimPass());
112}
113
114static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
115  if (Builder.OptLevel > 0)
116    PM.add(createObjCARCExpandPass());
117}
118
119static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
120  if (Builder.OptLevel > 0)
121    PM.add(createObjCARCOptPass());
122}
123
124static void addAddressSanitizerPass(const PassManagerBuilder &Builder,
125                                    PassManagerBase &PM) {
126  PM.add(createAddressSanitizerPass());
127}
128
129static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
130                                   PassManagerBase &PM) {
131  PM.add(createThreadSanitizerPass());
132}
133
134void EmitAssemblyHelper::CreatePasses() {
135  unsigned OptLevel = CodeGenOpts.OptimizationLevel;
136  CodeGenOptions::InliningMethod Inlining = CodeGenOpts.Inlining;
137
138  // Handle disabling of LLVM optimization, where we want to preserve the
139  // internal module before any optimization.
140  if (CodeGenOpts.DisableLLVMOpts) {
141    OptLevel = 0;
142    Inlining = CodeGenOpts.NoInlining;
143  }
144
145  PassManagerBuilder PMBuilder;
146  PMBuilder.OptLevel = OptLevel;
147  PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
148
149  PMBuilder.DisableSimplifyLibCalls = !CodeGenOpts.SimplifyLibCalls;
150  PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
151  PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
152
153  // In ObjC ARC mode, add the main ARC optimization passes.
154  if (LangOpts.ObjCAutoRefCount) {
155    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
156                           addObjCARCExpandPass);
157    PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
158                           addObjCARCAPElimPass);
159    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
160                           addObjCARCOptPass);
161  }
162
163  if (LangOpts.AddressSanitizer) {
164    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
165                           addAddressSanitizerPass);
166    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
167                           addAddressSanitizerPass);
168  }
169
170  if (LangOpts.ThreadSanitizer) {
171    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
172                           addThreadSanitizerPass);
173    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
174                           addThreadSanitizerPass);
175  }
176
177  // Figure out TargetLibraryInfo.
178  Triple TargetTriple(TheModule->getTargetTriple());
179  PMBuilder.LibraryInfo = new TargetLibraryInfo(TargetTriple);
180  if (!CodeGenOpts.SimplifyLibCalls)
181    PMBuilder.LibraryInfo->disableAllFunctions();
182
183  switch (Inlining) {
184  case CodeGenOptions::NoInlining: break;
185  case CodeGenOptions::NormalInlining: {
186    // FIXME: Derive these constants in a principled fashion.
187    unsigned Threshold = 225;
188    if (CodeGenOpts.OptimizeSize == 1)      // -Os
189      Threshold = 75;
190    else if (CodeGenOpts.OptimizeSize == 2) // -Oz
191      Threshold = 25;
192    else if (OptLevel > 2)
193      Threshold = 275;
194    PMBuilder.Inliner = createFunctionInliningPass(Threshold);
195    break;
196  }
197  case CodeGenOptions::OnlyAlwaysInlining:
198    // Respect always_inline.
199    if (OptLevel == 0)
200      // Do not insert lifetime intrinsics at -O0.
201      PMBuilder.Inliner = createAlwaysInlinerPass(false);
202    else
203      PMBuilder.Inliner = createAlwaysInlinerPass();
204    break;
205  }
206
207
208  // Set up the per-function pass manager.
209  FunctionPassManager *FPM = getPerFunctionPasses();
210  if (CodeGenOpts.VerifyModule)
211    FPM->add(createVerifierPass());
212  PMBuilder.populateFunctionPassManager(*FPM);
213
214  // Set up the per-module pass manager.
215  PassManager *MPM = getPerModulePasses();
216
217  if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
218    MPM->add(createGCOVProfilerPass(CodeGenOpts.EmitGcovNotes,
219                                    CodeGenOpts.EmitGcovArcs,
220                                    TargetTriple.isMacOSX()));
221
222    if (!CodeGenOpts.DebugInfo)
223      MPM->add(createStripSymbolsPass(true));
224  }
225
226
227  PMBuilder.populateModulePassManager(*MPM);
228}
229
230bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
231                                       formatted_raw_ostream &OS) {
232  // Create the TargetMachine for generating code.
233  std::string Error;
234  std::string Triple = TheModule->getTargetTriple();
235  const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
236  if (!TheTarget) {
237    Diags.Report(diag::err_fe_unable_to_create_target) << Error;
238    return false;
239  }
240
241  // FIXME: Expose these capabilities via actual APIs!!!! Aside from just
242  // being gross, this is also totally broken if we ever care about
243  // concurrency.
244
245  TargetMachine::setAsmVerbosityDefault(CodeGenOpts.AsmVerbose);
246
247  TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
248  TargetMachine::setDataSections    (CodeGenOpts.DataSections);
249
250  // FIXME: Parse this earlier.
251  llvm::CodeModel::Model CM;
252  if (CodeGenOpts.CodeModel == "small") {
253    CM = llvm::CodeModel::Small;
254  } else if (CodeGenOpts.CodeModel == "kernel") {
255    CM = llvm::CodeModel::Kernel;
256  } else if (CodeGenOpts.CodeModel == "medium") {
257    CM = llvm::CodeModel::Medium;
258  } else if (CodeGenOpts.CodeModel == "large") {
259    CM = llvm::CodeModel::Large;
260  } else {
261    assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
262    CM = llvm::CodeModel::Default;
263  }
264
265  SmallVector<const char *, 16> BackendArgs;
266  BackendArgs.push_back("clang"); // Fake program name.
267  if (!CodeGenOpts.DebugPass.empty()) {
268    BackendArgs.push_back("-debug-pass");
269    BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
270  }
271  if (!CodeGenOpts.LimitFloatPrecision.empty()) {
272    BackendArgs.push_back("-limit-float-precision");
273    BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
274  }
275  if (llvm::TimePassesIsEnabled)
276    BackendArgs.push_back("-time-passes");
277  for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
278    BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
279  if (CodeGenOpts.NoGlobalMerge)
280    BackendArgs.push_back("-global-merge=false");
281  BackendArgs.push_back(0);
282  llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
283                                    BackendArgs.data());
284
285  std::string FeaturesStr;
286  if (TargetOpts.Features.size()) {
287    SubtargetFeatures Features;
288    for (std::vector<std::string>::const_iterator
289           it = TargetOpts.Features.begin(),
290           ie = TargetOpts.Features.end(); it != ie; ++it)
291      Features.AddFeature(*it);
292    FeaturesStr = Features.getString();
293  }
294
295  llvm::Reloc::Model RM = llvm::Reloc::Default;
296  if (CodeGenOpts.RelocationModel == "static") {
297    RM = llvm::Reloc::Static;
298  } else if (CodeGenOpts.RelocationModel == "pic") {
299    RM = llvm::Reloc::PIC_;
300  } else {
301    assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
302           "Invalid PIC model!");
303    RM = llvm::Reloc::DynamicNoPIC;
304  }
305
306  CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
307  switch (CodeGenOpts.OptimizationLevel) {
308  default: break;
309  case 0: OptLevel = CodeGenOpt::None; break;
310  case 3: OptLevel = CodeGenOpt::Aggressive; break;
311  }
312
313  llvm::TargetOptions Options;
314
315  // Set frame pointer elimination mode.
316  if (!CodeGenOpts.DisableFPElim) {
317    Options.NoFramePointerElim = false;
318    Options.NoFramePointerElimNonLeaf = false;
319  } else if (CodeGenOpts.OmitLeafFramePointer) {
320    Options.NoFramePointerElim = false;
321    Options.NoFramePointerElimNonLeaf = true;
322  } else {
323    Options.NoFramePointerElim = true;
324    Options.NoFramePointerElimNonLeaf = true;
325  }
326
327  // Set float ABI type.
328  if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
329    Options.FloatABIType = llvm::FloatABI::Soft;
330  else if (CodeGenOpts.FloatABI == "hard")
331    Options.FloatABIType = llvm::FloatABI::Hard;
332  else {
333    assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
334    Options.FloatABIType = llvm::FloatABI::Default;
335  }
336
337  Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
338  Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
339  Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
340  Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
341  Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
342  Options.UseSoftFloat = CodeGenOpts.SoftFloat;
343  Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
344  Options.RealignStack = CodeGenOpts.StackRealignment;
345  Options.DisableTailCalls = CodeGenOpts.DisableTailCalls;
346  Options.TrapFuncName = CodeGenOpts.TrapFuncName;
347  Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
348
349  TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
350                                                     FeaturesStr, Options,
351                                                     RM, CM, OptLevel);
352
353  if (CodeGenOpts.RelaxAll)
354    TM->setMCRelaxAll(true);
355  if (CodeGenOpts.SaveTempLabels)
356    TM->setMCSaveTempLabels(true);
357  if (CodeGenOpts.NoDwarf2CFIAsm)
358    TM->setMCUseCFI(false);
359  if (!CodeGenOpts.NoDwarfDirectoryAsm)
360    TM->setMCUseDwarfDirectory(true);
361  if (CodeGenOpts.NoExecStack)
362    TM->setMCNoExecStack(true);
363
364  // Create the code generator passes.
365  PassManager *PM = getCodeGenPasses();
366
367  // Add LibraryInfo.
368  TargetLibraryInfo *TLI = new TargetLibraryInfo();
369  if (!CodeGenOpts.SimplifyLibCalls)
370    TLI->disableAllFunctions();
371  PM->add(TLI);
372
373  // Normal mode, emit a .s or .o file by running the code generator. Note,
374  // this also adds codegenerator level optimization passes.
375  TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
376  if (Action == Backend_EmitObj)
377    CGFT = TargetMachine::CGFT_ObjectFile;
378  else if (Action == Backend_EmitMCNull)
379    CGFT = TargetMachine::CGFT_Null;
380  else
381    assert(Action == Backend_EmitAssembly && "Invalid action!");
382
383  // Add ObjC ARC final-cleanup optimizations. This is done as part of the
384  // "codegen" passes so that it isn't run multiple times when there is
385  // inlining happening.
386  if (LangOpts.ObjCAutoRefCount &&
387      CodeGenOpts.OptimizationLevel > 0)
388    PM->add(createObjCARCContractPass());
389
390  if (TM->addPassesToEmitFile(*PM, OS, CGFT,
391                              /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
392    Diags.Report(diag::err_fe_unable_to_interface_with_target);
393    return false;
394  }
395
396  return true;
397}
398
399void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
400  TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : 0);
401  llvm::formatted_raw_ostream FormattedOS;
402
403  CreatePasses();
404  switch (Action) {
405  case Backend_EmitNothing:
406    break;
407
408  case Backend_EmitBC:
409    getPerModulePasses()->add(createBitcodeWriterPass(*OS));
410    break;
411
412  case Backend_EmitLL:
413    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
414    getPerModulePasses()->add(createPrintModulePass(&FormattedOS));
415    break;
416
417  default:
418    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
419    if (!AddEmitPasses(Action, FormattedOS))
420      return;
421  }
422
423  // Before executing passes, print the final values of the LLVM options.
424  cl::PrintOptionValues();
425
426  // Run passes. For now we do all passes at once, but eventually we
427  // would like to have the option of streaming code generation.
428
429  if (PerFunctionPasses) {
430    PrettyStackTraceString CrashInfo("Per-function optimization");
431
432    PerFunctionPasses->doInitialization();
433    for (Module::iterator I = TheModule->begin(),
434           E = TheModule->end(); I != E; ++I)
435      if (!I->isDeclaration())
436        PerFunctionPasses->run(*I);
437    PerFunctionPasses->doFinalization();
438  }
439
440  if (PerModulePasses) {
441    PrettyStackTraceString CrashInfo("Per-module optimization passes");
442    PerModulePasses->run(*TheModule);
443  }
444
445  if (CodeGenPasses) {
446    PrettyStackTraceString CrashInfo("Code generation");
447    CodeGenPasses->run(*TheModule);
448  }
449}
450
451void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
452                              const CodeGenOptions &CGOpts,
453                              const clang::TargetOptions &TOpts,
454                              const LangOptions &LOpts,
455                              Module *M,
456                              BackendAction Action, raw_ostream *OS) {
457  EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
458
459  AsmHelper.EmitAssembly(Action, OS);
460}
461