contrib/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp

   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"
  38 using namespace clang;
  39 using namespace llvm;
  40
  41 namespace {
  42
  43 class 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
  56 private:
  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
  88 public:
  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
 109 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
 110   if (Builder.OptLevel > 0)
 111     PM.add(createObjCARCAPElimPass());
 112 }
 113
 114 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
 115   if (Builder.OptLevel > 0)
 116     PM.add(createObjCARCExpandPass());
 117 }
 118
 119 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
 120   if (Builder.OptLevel > 0)
 121     PM.add(createObjCARCOptPass());
 122 }
 123
 124 static void addAddressSanitizerPass(const PassManagerBuilder &Builder,
 125                                     PassManagerBase &PM) {
 126   PM.add(createAddressSanitizerPass());
 127 }
 128
 129 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
 130                                    PassManagerBase &PM) {
 131   PM.add(createThreadSanitizerPass());
 132 }
 133
 134 void 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
 230 bool 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
 399 void 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
 451 void 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 }