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 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, const TargetOptions &TOpts,
  91                      const LangOptions &LOpts,
  92                      Module *M)
  93     : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
  94       TheModule(M), CodeGenerationTime("Code Generation Time"),
  95       CodeGenPasses(0), PerModulePasses(0), PerFunctionPasses(0) {}
  96
  97   ~EmitAssemblyHelper() {
  98     delete CodeGenPasses;
  99     delete PerModulePasses;
 100     delete PerFunctionPasses;
 101   }
 102
 103   void EmitAssembly(BackendAction Action, raw_ostream *OS);
 104 };
 105
 106 }
 107
 108 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
 109   if (Builder.OptLevel > 0)
 110     PM.add(createObjCARCExpandPass());
 111 }
 112
 113 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
 114   if (Builder.OptLevel > 0)
 115     PM.add(createObjCARCOptPass());
 116 }
 117
 118 void EmitAssemblyHelper::CreatePasses() {
 119   unsigned OptLevel = CodeGenOpts.OptimizationLevel;
 120   CodeGenOptions::InliningMethod Inlining = CodeGenOpts.Inlining;
 121
 122   // Handle disabling of LLVM optimization, where we want to preserve the
 123   // internal module before any optimization.
 124   if (CodeGenOpts.DisableLLVMOpts) {
 125     OptLevel = 0;
 126     Inlining = CodeGenOpts.NoInlining;
 127   }
 128
 129   PassManagerBuilder PMBuilder;
 130   PMBuilder.OptLevel = OptLevel;
 131   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
 132
 133   PMBuilder.DisableSimplifyLibCalls = !CodeGenOpts.SimplifyLibCalls;
 134   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
 135   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
 136
 137   // In ObjC ARC mode, add the main ARC optimization passes.
 138   if (LangOpts.ObjCAutoRefCount) {
 139     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
 140                            addObjCARCExpandPass);
 141     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
 142                            addObjCARCOptPass);
 143   }
 144
 145   // Figure out TargetLibraryInfo.
 146   Triple TargetTriple(TheModule->getTargetTriple());
 147   PMBuilder.LibraryInfo = new TargetLibraryInfo(TargetTriple);
 148   if (!CodeGenOpts.SimplifyLibCalls)
 149     PMBuilder.LibraryInfo->disableAllFunctions();
 150
 151   switch (Inlining) {
 152   case CodeGenOptions::NoInlining: break;
 153   case CodeGenOptions::NormalInlining: {
 154     // FIXME: Derive these constants in a principled fashion.
 155     unsigned Threshold = 225;
 156     if (CodeGenOpts.OptimizeSize == 1)      // -Os
 157       Threshold = 75;
 158     else if (CodeGenOpts.OptimizeSize == 2) // -Oz
 159       Threshold = 25;
 160     else if (OptLevel > 2)
 161       Threshold = 275;
 162     PMBuilder.Inliner = createFunctionInliningPass(Threshold);
 163     break;
 164   }
 165   case CodeGenOptions::OnlyAlwaysInlining:
 166     // Respect always_inline.
 167     PMBuilder.Inliner = createAlwaysInlinerPass();
 168     break;
 169   }
 170
 171
 172   // Set up the per-function pass manager.
 173   FunctionPassManager *FPM = getPerFunctionPasses();
 174   if (CodeGenOpts.VerifyModule)
 175     FPM->add(createVerifierPass());
 176   PMBuilder.populateFunctionPassManager(*FPM);
 177
 178   // Set up the per-module pass manager.
 179   PassManager *MPM = getPerModulePasses();
 180
 181   if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
 182     MPM->add(createGCOVProfilerPass(CodeGenOpts.EmitGcovNotes,
 183                                     CodeGenOpts.EmitGcovArcs,
 184                                     TargetTriple.isMacOSX()));
 185
 186     if (!CodeGenOpts.DebugInfo)
 187       MPM->add(createStripSymbolsPass(true));
 188   }
 189
 190
 191   PMBuilder.populateModulePassManager(*MPM);
 192 }
 193
 194 bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
 195                                        formatted_raw_ostream &OS) {
 196   // Create the TargetMachine for generating code.
 197   std::string Error;
 198   std::string Triple = TheModule->getTargetTriple();
 199   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
 200   if (!TheTarget) {
 201     Diags.Report(diag::err_fe_unable_to_create_target) << Error;
 202     return false;
 203   }
 204
 205   // FIXME: Expose these capabilities via actual APIs!!!! Aside from just
 206   // being gross, this is also totally broken if we ever care about
 207   // concurrency.
 208
 209   // Set frame pointer elimination mode.
 210   if (!CodeGenOpts.DisableFPElim) {
 211     llvm::NoFramePointerElim = false;
 212     llvm::NoFramePointerElimNonLeaf = false;
 213   } else if (CodeGenOpts.OmitLeafFramePointer) {
 214     llvm::NoFramePointerElim = false;
 215     llvm::NoFramePointerElimNonLeaf = true;
 216   } else {
 217     llvm::NoFramePointerElim = true;
 218     llvm::NoFramePointerElimNonLeaf = true;
 219   }
 220
 221   // Set float ABI type.
 222   if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
 223     llvm::FloatABIType = llvm::FloatABI::Soft;
 224   else if (CodeGenOpts.FloatABI == "hard")
 225     llvm::FloatABIType = llvm::FloatABI::Hard;
 226   else {
 227     assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
 228     llvm::FloatABIType = llvm::FloatABI::Default;
 229   }
 230
 231   llvm::LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
 232   llvm::NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
 233   llvm::NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
 234   NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
 235   llvm::UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
 236   llvm::UseSoftFloat = CodeGenOpts.SoftFloat;
 237
 238   TargetMachine::setAsmVerbosityDefault(CodeGenOpts.AsmVerbose);
 239
 240   TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
 241   TargetMachine::setDataSections    (CodeGenOpts.DataSections);
 242
 243   // FIXME: Parse this earlier.
 244   llvm::CodeModel::Model CM;
 245   if (CodeGenOpts.CodeModel == "small") {
 246     CM = llvm::CodeModel::Small;
 247   } else if (CodeGenOpts.CodeModel == "kernel") {
 248     CM = llvm::CodeModel::Kernel;
 249   } else if (CodeGenOpts.CodeModel == "medium") {
 250     CM = llvm::CodeModel::Medium;
 251   } else if (CodeGenOpts.CodeModel == "large") {
 252     CM = llvm::CodeModel::Large;
 253   } else {
 254     assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
 255     CM = llvm::CodeModel::Default;
 256   }
 257
 258   std::vector<const char *> BackendArgs;
 259   BackendArgs.push_back("clang"); // Fake program name.
 260   if (!CodeGenOpts.DebugPass.empty()) {
 261     BackendArgs.push_back("-debug-pass");
 262     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
 263   }
 264   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
 265     BackendArgs.push_back("-limit-float-precision");
 266     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
 267   }
 268   if (llvm::TimePassesIsEnabled)
 269     BackendArgs.push_back("-time-passes");
 270   for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
 271     BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
 272   if (CodeGenOpts.NoGlobalMerge)
 273     BackendArgs.push_back("-global-merge=false");
 274   BackendArgs.push_back(0);
 275   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
 276                                     const_cast<char **>(&BackendArgs[0]));
 277
 278   std::string FeaturesStr;
 279   if (TargetOpts.Features.size()) {
 280     SubtargetFeatures Features;
 281     for (std::vector<std::string>::const_iterator
 282            it = TargetOpts.Features.begin(),
 283            ie = TargetOpts.Features.end(); it != ie; ++it)
 284       Features.AddFeature(*it);
 285     FeaturesStr = Features.getString();
 286   }
 287
 288   llvm::Reloc::Model RM = llvm::Reloc::Default;
 289   if (CodeGenOpts.RelocationModel == "static") {
 290     RM = llvm::Reloc::Static;
 291   } else if (CodeGenOpts.RelocationModel == "pic") {
 292     RM = llvm::Reloc::PIC_;
 293   } else {
 294     assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
 295            "Invalid PIC model!");
 296     RM = llvm::Reloc::DynamicNoPIC;
 297   }
 298
 299   TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
 300                                                      FeaturesStr, RM, CM);
 301
 302   if (CodeGenOpts.RelaxAll)
 303     TM->setMCRelaxAll(true);
 304   if (CodeGenOpts.SaveTempLabels)
 305     TM->setMCSaveTempLabels(true);
 306   if (CodeGenOpts.NoDwarf2CFIAsm)
 307     TM->setMCUseCFI(false);
 308   if (CodeGenOpts.NoExecStack)
 309     TM->setMCNoExecStack(true);
 310
 311   // Create the code generator passes.
 312   PassManager *PM = getCodeGenPasses();
 313   CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
 314
 315   switch (CodeGenOpts.OptimizationLevel) {
 316   default: break;
 317   case 0: OptLevel = CodeGenOpt::None; break;
 318   case 3: OptLevel = CodeGenOpt::Aggressive; break;
 319   }
 320
 321   // Normal mode, emit a .s or .o file by running the code generator. Note,
 322   // this also adds codegenerator level optimization passes.
 323   TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
 324   if (Action == Backend_EmitObj)
 325     CGFT = TargetMachine::CGFT_ObjectFile;
 326   else if (Action == Backend_EmitMCNull)
 327     CGFT = TargetMachine::CGFT_Null;
 328   else
 329     assert(Action == Backend_EmitAssembly && "Invalid action!");
 330
 331   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
 332   // "codegen" passes so that it isn't run multiple times when there is
 333   // inlining happening.
 334   if (LangOpts.ObjCAutoRefCount)
 335     PM->add(createObjCARCContractPass());
 336
 337   if (TM->addPassesToEmitFile(*PM, OS, CGFT, OptLevel,
 338                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
 339     Diags.Report(diag::err_fe_unable_to_interface_with_target);
 340     return false;
 341   }
 342
 343   return true;
 344 }
 345
 346 void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
 347   TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : 0);
 348   llvm::formatted_raw_ostream FormattedOS;
 349
 350   CreatePasses();
 351   switch (Action) {
 352   case Backend_EmitNothing:
 353     break;
 354
 355   case Backend_EmitBC:
 356     getPerModulePasses()->add(createBitcodeWriterPass(*OS));
 357     break;
 358
 359   case Backend_EmitLL:
 360     FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
 361     getPerModulePasses()->add(createPrintModulePass(&FormattedOS));
 362     break;
 363
 364   default:
 365     FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
 366     if (!AddEmitPasses(Action, FormattedOS))
 367       return;
 368   }
 369
 370   // Before executing passes, print the final values of the LLVM options.
 371   cl::PrintOptionValues();
 372
 373   // Run passes. For now we do all passes at once, but eventually we
 374   // would like to have the option of streaming code generation.
 375
 376   if (PerFunctionPasses) {
 377     PrettyStackTraceString CrashInfo("Per-function optimization");
 378
 379     PerFunctionPasses->doInitialization();
 380     for (Module::iterator I = TheModule->begin(),
 381            E = TheModule->end(); I != E; ++I)
 382       if (!I->isDeclaration())
 383         PerFunctionPasses->run(*I);
 384     PerFunctionPasses->doFinalization();
 385   }
 386
 387   if (PerModulePasses) {
 388     PrettyStackTraceString CrashInfo("Per-module optimization passes");
 389     PerModulePasses->run(*TheModule);
 390   }
 391
 392   if (CodeGenPasses) {
 393     PrettyStackTraceString CrashInfo("Code generation");
 394     CodeGenPasses->run(*TheModule);
 395   }
 396 }
 397
 398 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
 399                               const CodeGenOptions &CGOpts,
 400                               const TargetOptions &TOpts,
 401                               const LangOptions &LOpts,
 402                               Module *M,
 403                               BackendAction Action, raw_ostream *OS) {
 404   EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
 405
 406   AsmHelper.EmitAssembly(Action, OS);
 407 }