BackendUtil.cpp revision 9875962295022661213153127eae961250fefd55 
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
129void EmitAssemblyHelper::CreatePasses() {
130  unsigned OptLevel = CodeGenOpts.OptimizationLevel;
131  CodeGenOptions::InliningMethod Inlining = CodeGenOpts.Inlining;
132
133  // Handle disabling of LLVM optimization, where we want to preserve the
134  // internal module before any optimization.
135  if (CodeGenOpts.DisableLLVMOpts) {
136    OptLevel = 0;
137    Inlining = CodeGenOpts.NoInlining;
138  }
139
140  PassManagerBuilder PMBuilder;
141  PMBuilder.OptLevel = OptLevel;
142  PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
143
144  PMBuilder.DisableSimplifyLibCalls = !CodeGenOpts.SimplifyLibCalls;
145  PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
146  PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
147
148  // In ObjC ARC mode, add the main ARC optimization passes.
149  if (LangOpts.ObjCAutoRefCount) {
150    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
151                           addObjCARCExpandPass);
152    PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
153                           addObjCARCAPElimPass);
154    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
155                           addObjCARCOptPass);
156  }
157
158  if (LangOpts.AddressSanitizer) {
159    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
160                           addAddressSanitizerPass);
161    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
162                           addAddressSanitizerPass);
163  }
164
165  // Figure out TargetLibraryInfo.
166  Triple TargetTriple(TheModule->getTargetTriple());
167  PMBuilder.LibraryInfo = new TargetLibraryInfo(TargetTriple);
168  if (!CodeGenOpts.SimplifyLibCalls)
169    PMBuilder.LibraryInfo->disableAllFunctions();
170
171  switch (Inlining) {
172  case CodeGenOptions::NoInlining: break;
173  case CodeGenOptions::NormalInlining: {
174    // FIXME: Derive these constants in a principled fashion.
175    unsigned Threshold = 225;
176    if (CodeGenOpts.OptimizeSize == 1)      // -Os
177      Threshold = 75;
178    else if (CodeGenOpts.OptimizeSize == 2) // -Oz
179      Threshold = 25;
180    else if (OptLevel > 2)
181      Threshold = 275;
182    PMBuilder.Inliner = createFunctionInliningPass(Threshold);
183    break;
184  }
185  case CodeGenOptions::OnlyAlwaysInlining:
186    // Respect always_inline.
187    if (OptLevel == 0)
188      // Do not insert lifetime intrinsics at -O0.
189      PMBuilder.Inliner = createAlwaysInlinerPass(false);
190    else
191      PMBuilder.Inliner = createAlwaysInlinerPass();
192    break;
193  }
194
195
196  // Set up the per-function pass manager.
197  FunctionPassManager *FPM = getPerFunctionPasses();
198  if (CodeGenOpts.VerifyModule)
199    FPM->add(createVerifierPass());
200  PMBuilder.populateFunctionPassManager(*FPM);
201
202  // Set up the per-module pass manager.
203  PassManager *MPM = getPerModulePasses();
204
205  if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
206    MPM->add(createGCOVProfilerPass(CodeGenOpts.EmitGcovNotes,
207                                    CodeGenOpts.EmitGcovArcs,
208                                    TargetTriple.isMacOSX()));
209
210    if (!CodeGenOpts.DebugInfo)
211      MPM->add(createStripSymbolsPass(true));
212  }
213
214
215  PMBuilder.populateModulePassManager(*MPM);
216}
217
218bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
219                                       formatted_raw_ostream &OS) {
220  // Create the TargetMachine for generating code.
221  std::string Error;
222  std::string Triple = TheModule->getTargetTriple();
223  const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
224  if (!TheTarget) {
225    Diags.Report(diag::err_fe_unable_to_create_target) << Error;
226    return false;
227  }
228
229  // FIXME: Expose these capabilities via actual APIs!!!! Aside from just
230  // being gross, this is also totally broken if we ever care about
231  // concurrency.
232
233  TargetMachine::setAsmVerbosityDefault(CodeGenOpts.AsmVerbose);
234
235  TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
236  TargetMachine::setDataSections    (CodeGenOpts.DataSections);
237
238  // FIXME: Parse this earlier.
239  llvm::CodeModel::Model CM;
240  if (CodeGenOpts.CodeModel == "small") {
241    CM = llvm::CodeModel::Small;
242  } else if (CodeGenOpts.CodeModel == "kernel") {
243    CM = llvm::CodeModel::Kernel;
244  } else if (CodeGenOpts.CodeModel == "medium") {
245    CM = llvm::CodeModel::Medium;
246  } else if (CodeGenOpts.CodeModel == "large") {
247    CM = llvm::CodeModel::Large;
248  } else {
249    assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
250    CM = llvm::CodeModel::Default;
251  }
252
253  SmallVector<const char *, 16> BackendArgs;
254  BackendArgs.push_back("clang"); // Fake program name.
255  if (!CodeGenOpts.DebugPass.empty()) {
256    BackendArgs.push_back("-debug-pass");
257    BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
258  }
259  if (!CodeGenOpts.LimitFloatPrecision.empty()) {
260    BackendArgs.push_back("-limit-float-precision");
261    BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
262  }
263  if (llvm::TimePassesIsEnabled)
264    BackendArgs.push_back("-time-passes");
265  for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
266    BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
267  if (CodeGenOpts.NoGlobalMerge)
268    BackendArgs.push_back("-global-merge=false");
269  BackendArgs.push_back(0);
270  llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
271                                    BackendArgs.data());
272
273  std::string FeaturesStr;
274  if (TargetOpts.Features.size()) {
275    SubtargetFeatures Features;
276    for (std::vector<std::string>::const_iterator
277           it = TargetOpts.Features.begin(),
278           ie = TargetOpts.Features.end(); it != ie; ++it)
279      Features.AddFeature(*it);
280    FeaturesStr = Features.getString();
281  }
282
283  llvm::Reloc::Model RM = llvm::Reloc::Default;
284  if (CodeGenOpts.RelocationModel == "static") {
285    RM = llvm::Reloc::Static;
286  } else if (CodeGenOpts.RelocationModel == "pic") {
287    RM = llvm::Reloc::PIC_;
288  } else {
289    assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
290           "Invalid PIC model!");
291    RM = llvm::Reloc::DynamicNoPIC;
292  }
293
294  CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
295  switch (CodeGenOpts.OptimizationLevel) {
296  default: break;
297  case 0: OptLevel = CodeGenOpt::None; break;
298  case 3: OptLevel = CodeGenOpt::Aggressive; break;
299  }
300
301  llvm::TargetOptions Options;
302
303  // Set frame pointer elimination mode.
304  if (!CodeGenOpts.DisableFPElim) {
305    Options.NoFramePointerElim = false;
306    Options.NoFramePointerElimNonLeaf = false;
307  } else if (CodeGenOpts.OmitLeafFramePointer) {
308    Options.NoFramePointerElim = false;
309    Options.NoFramePointerElimNonLeaf = true;
310  } else {
311    Options.NoFramePointerElim = true;
312    Options.NoFramePointerElimNonLeaf = true;
313  }
314
315  // Set float ABI type.
316  if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
317    Options.FloatABIType = llvm::FloatABI::Soft;
318  else if (CodeGenOpts.FloatABI == "hard")
319    Options.FloatABIType = llvm::FloatABI::Hard;
320  else {
321    assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
322    Options.FloatABIType = llvm::FloatABI::Default;
323  }
324
325  Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
326  Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
327  Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
328  Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
329  Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
330  Options.UseSoftFloat = CodeGenOpts.SoftFloat;
331  Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
332  Options.RealignStack = CodeGenOpts.StackRealignment;
333  Options.DisableTailCalls = CodeGenOpts.DisableTailCalls;
334  Options.TrapFuncName = CodeGenOpts.TrapFuncName;
335
336  TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
337                                                     FeaturesStr, Options,
338                                                     RM, CM, OptLevel);
339
340  if (CodeGenOpts.RelaxAll)
341    TM->setMCRelaxAll(true);
342  if (CodeGenOpts.SaveTempLabels)
343    TM->setMCSaveTempLabels(true);
344  if (CodeGenOpts.NoDwarf2CFIAsm)
345    TM->setMCUseCFI(false);
346  if (!CodeGenOpts.NoDwarfDirectoryAsm)
347    TM->setMCUseDwarfDirectory(true);
348  if (CodeGenOpts.NoExecStack)
349    TM->setMCNoExecStack(true);
350
351  // Create the code generator passes.
352  PassManager *PM = getCodeGenPasses();
353
354  // Normal mode, emit a .s or .o file by running the code generator. Note,
355  // this also adds codegenerator level optimization passes.
356  TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
357  if (Action == Backend_EmitObj)
358    CGFT = TargetMachine::CGFT_ObjectFile;
359  else if (Action == Backend_EmitMCNull)
360    CGFT = TargetMachine::CGFT_Null;
361  else
362    assert(Action == Backend_EmitAssembly && "Invalid action!");
363
364  // Add ObjC ARC final-cleanup optimizations. This is done as part of the
365  // "codegen" passes so that it isn't run multiple times when there is
366  // inlining happening.
367  if (LangOpts.ObjCAutoRefCount)
368    PM->add(createObjCARCContractPass());
369
370  if (TM->addPassesToEmitFile(*PM, OS, CGFT,
371                              /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
372    Diags.Report(diag::err_fe_unable_to_interface_with_target);
373    return false;
374  }
375
376  return true;
377}
378
379void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
380  TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : 0);
381  llvm::formatted_raw_ostream FormattedOS;
382
383  CreatePasses();
384  switch (Action) {
385  case Backend_EmitNothing:
386    break;
387
388  case Backend_EmitBC:
389    getPerModulePasses()->add(createBitcodeWriterPass(*OS));
390    break;
391
392  case Backend_EmitLL:
393    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
394    getPerModulePasses()->add(createPrintModulePass(&FormattedOS));
395    break;
396
397  default:
398    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
399    if (!AddEmitPasses(Action, FormattedOS))
400      return;
401  }
402
403  // Before executing passes, print the final values of the LLVM options.
404  cl::PrintOptionValues();
405
406  // Run passes. For now we do all passes at once, but eventually we
407  // would like to have the option of streaming code generation.
408
409  if (PerFunctionPasses) {
410    PrettyStackTraceString CrashInfo("Per-function optimization");
411
412    PerFunctionPasses->doInitialization();
413    for (Module::iterator I = TheModule->begin(),
414           E = TheModule->end(); I != E; ++I)
415      if (!I->isDeclaration())
416        PerFunctionPasses->run(*I);
417    PerFunctionPasses->doFinalization();
418  }
419
420  if (PerModulePasses) {
421    PrettyStackTraceString CrashInfo("Per-module optimization passes");
422    PerModulePasses->run(*TheModule);
423  }
424
425  if (CodeGenPasses) {
426    PrettyStackTraceString CrashInfo("Code generation");
427    CodeGenPasses->run(*TheModule);
428  }
429}
430
431void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
432                              const CodeGenOptions &CGOpts,
433                              const clang::TargetOptions &TOpts,
434                              const LangOptions &LOpts,
435                              Module *M,
436                              BackendAction Action, raw_ostream *OS) {
437  EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
438
439  AsmHelper.EmitAssembly(Action, OS);
440}
441