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