BackendUtil.cpp revision 3c66d30d513106bb794990c5e4ba36a31ac19f15 
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/Frontend/CodeGenOptions.h"
14#include "clang/Frontend/FrontendDiagnostic.h"
15#include "llvm/Module.h"
16#include "llvm/PassManager.h"
17#include "llvm/Assembly/PrintModulePass.h"
18#include "llvm/Bitcode/ReaderWriter.h"
19#include "llvm/CodeGen/RegAllocRegistry.h"
20#include "llvm/CodeGen/SchedulerRegistry.h"
21#include "llvm/Support/CommandLine.h"
22#include "llvm/Support/FormattedStream.h"
23#include "llvm/Support/PrettyStackTrace.h"
24#include "llvm/Support/StandardPasses.h"
25#include "llvm/Support/Timer.h"
26#include "llvm/Support/raw_ostream.h"
27#include "llvm/Target/SubtargetFeature.h"
28#include "llvm/Target/TargetData.h"
29#include "llvm/Target/TargetLibraryInfo.h"
30#include "llvm/Target/TargetMachine.h"
31#include "llvm/Target/TargetOptions.h"
32#include "llvm/Target/TargetRegistry.h"
33using namespace clang;
34using namespace llvm;
35
36namespace {
37
38class EmitAssemblyHelper {
39  Diagnostic &Diags;
40  const CodeGenOptions &CodeGenOpts;
41  const TargetOptions &TargetOpts;
42  Module *TheModule;
43
44  Timer CodeGenerationTime;
45
46  mutable PassManager *CodeGenPasses;
47  mutable PassManager *PerModulePasses;
48  mutable FunctionPassManager *PerFunctionPasses;
49
50private:
51  PassManager *getCodeGenPasses() const {
52    if (!CodeGenPasses) {
53      CodeGenPasses = new PassManager();
54      CodeGenPasses->add(new TargetData(TheModule));
55    }
56    return CodeGenPasses;
57  }
58
59  PassManager *getPerModulePasses() const {
60    if (!PerModulePasses) {
61      PerModulePasses = new PassManager();
62      PerModulePasses->add(new TargetData(TheModule));
63    }
64    return PerModulePasses;
65  }
66
67  FunctionPassManager *getPerFunctionPasses() const {
68    if (!PerFunctionPasses) {
69      PerFunctionPasses = new FunctionPassManager(TheModule);
70      PerFunctionPasses->add(new TargetData(TheModule));
71    }
72    return PerFunctionPasses;
73  }
74
75  void CreatePasses();
76
77  /// AddEmitPasses - Add passes necessary to emit assembly or LLVM IR.
78  ///
79  /// \return True on success.
80  bool AddEmitPasses(BackendAction Action, formatted_raw_ostream &OS);
81
82public:
83  EmitAssemblyHelper(Diagnostic &_Diags,
84                     const CodeGenOptions &CGOpts, const TargetOptions &TOpts,
85                     Module *M)
86    : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts),
87      TheModule(M), CodeGenerationTime("Code Generation Time"),
88      CodeGenPasses(0), PerModulePasses(0), PerFunctionPasses(0) {}
89
90  ~EmitAssemblyHelper() {
91    delete CodeGenPasses;
92    delete PerModulePasses;
93    delete PerFunctionPasses;
94  }
95
96  void EmitAssembly(BackendAction Action, raw_ostream *OS);
97};
98
99}
100
101void EmitAssemblyHelper::CreatePasses() {
102  unsigned OptLevel = CodeGenOpts.OptimizationLevel;
103  CodeGenOptions::InliningMethod Inlining = CodeGenOpts.Inlining;
104
105  // Handle disabling of LLVM optimization, where we want to preserve the
106  // internal module before any optimization.
107  if (CodeGenOpts.DisableLLVMOpts) {
108    OptLevel = 0;
109    Inlining = CodeGenOpts.NoInlining;
110  }
111
112  FunctionPassManager *FPM = getPerFunctionPasses();
113
114  TargetLibraryInfo *TLI =
115    new TargetLibraryInfo(Triple(TheModule->getTargetTriple()));
116  if (!CodeGenOpts.SimplifyLibCalls)
117    TLI->disableAllFunctions();
118  FPM->add(TLI);
119
120  // In -O0 if checking is disabled, we don't even have per-function passes.
121  if (CodeGenOpts.VerifyModule)
122    FPM->add(createVerifierPass());
123
124  // Assume that standard function passes aren't run for -O0.
125  if (OptLevel > 0)
126    llvm::createStandardFunctionPasses(FPM, OptLevel);
127
128  llvm::Pass *InliningPass = 0;
129  switch (Inlining) {
130  case CodeGenOptions::NoInlining: break;
131  case CodeGenOptions::NormalInlining: {
132    // Set the inline threshold following llvm-gcc.
133    //
134    // FIXME: Derive these constants in a principled fashion.
135    unsigned Threshold = 225;
136    if (CodeGenOpts.OptimizeSize)
137      Threshold = 75;
138    else if (OptLevel > 2)
139      Threshold = 275;
140    InliningPass = createFunctionInliningPass(Threshold);
141    break;
142  }
143  case CodeGenOptions::OnlyAlwaysInlining:
144    InliningPass = createAlwaysInlinerPass();         // Respect always_inline
145    break;
146  }
147
148  PassManager *MPM = getPerModulePasses();
149
150  TLI = new TargetLibraryInfo(Triple(TheModule->getTargetTriple()));
151  if (!CodeGenOpts.SimplifyLibCalls)
152    TLI->disableAllFunctions();
153  MPM->add(TLI);
154
155  // For now we always create per module passes.
156  llvm::createStandardModulePasses(MPM, OptLevel,
157                                   CodeGenOpts.OptimizeSize,
158                                   CodeGenOpts.UnitAtATime,
159                                   CodeGenOpts.UnrollLoops,
160                                   CodeGenOpts.SimplifyLibCalls,
161                                   /*HaveExceptions=*/true,
162                                   InliningPass);
163}
164
165bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
166                                       formatted_raw_ostream &OS) {
167  // Create the TargetMachine for generating code.
168  std::string Error;
169  std::string Triple = TheModule->getTargetTriple();
170  const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
171  if (!TheTarget) {
172    Diags.Report(diag::err_fe_unable_to_create_target) << Error;
173    return false;
174  }
175
176  // FIXME: Expose these capabilities via actual APIs!!!! Aside from just
177  // being gross, this is also totally broken if we ever care about
178  // concurrency.
179
180  // Set frame pointer elimination mode.
181  if (!CodeGenOpts.DisableFPElim) {
182    llvm::NoFramePointerElim = false;
183    llvm::NoFramePointerElimNonLeaf = false;
184  } else if (CodeGenOpts.OmitLeafFramePointer) {
185    llvm::NoFramePointerElim = false;
186    llvm::NoFramePointerElimNonLeaf = true;
187  } else {
188    llvm::NoFramePointerElim = true;
189    llvm::NoFramePointerElimNonLeaf = true;
190  }
191
192  // Set float ABI type.
193  if (CodeGenOpts.FloatABI == "soft")
194    llvm::FloatABIType = llvm::FloatABI::Soft;
195  else if (CodeGenOpts.FloatABI == "hard")
196    llvm::FloatABIType = llvm::FloatABI::Hard;
197  else {
198    assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
199    llvm::FloatABIType = llvm::FloatABI::Default;
200  }
201
202  llvm::LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
203  llvm::NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
204  llvm::NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
205  NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
206  llvm::UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
207  llvm::UseSoftFloat = CodeGenOpts.SoftFloat;
208  UnwindTablesMandatory = CodeGenOpts.UnwindTables;
209
210  TargetMachine::setAsmVerbosityDefault(CodeGenOpts.AsmVerbose);
211
212  TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
213  TargetMachine::setDataSections    (CodeGenOpts.DataSections);
214
215  // FIXME: Parse this earlier.
216  if (CodeGenOpts.RelocationModel == "static") {
217    TargetMachine::setRelocationModel(llvm::Reloc::Static);
218  } else if (CodeGenOpts.RelocationModel == "pic") {
219    TargetMachine::setRelocationModel(llvm::Reloc::PIC_);
220  } else {
221    assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
222           "Invalid PIC model!");
223    TargetMachine::setRelocationModel(llvm::Reloc::DynamicNoPIC);
224  }
225  // FIXME: Parse this earlier.
226  if (CodeGenOpts.CodeModel == "small") {
227    TargetMachine::setCodeModel(llvm::CodeModel::Small);
228  } else if (CodeGenOpts.CodeModel == "kernel") {
229    TargetMachine::setCodeModel(llvm::CodeModel::Kernel);
230  } else if (CodeGenOpts.CodeModel == "medium") {
231    TargetMachine::setCodeModel(llvm::CodeModel::Medium);
232  } else if (CodeGenOpts.CodeModel == "large") {
233    TargetMachine::setCodeModel(llvm::CodeModel::Large);
234  } else {
235    assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
236    TargetMachine::setCodeModel(llvm::CodeModel::Default);
237  }
238
239  std::vector<const char *> BackendArgs;
240  BackendArgs.push_back("clang"); // Fake program name.
241  if (!CodeGenOpts.DebugPass.empty()) {
242    BackendArgs.push_back("-debug-pass");
243    BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
244  }
245  if (!CodeGenOpts.LimitFloatPrecision.empty()) {
246    BackendArgs.push_back("-limit-float-precision");
247    BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
248  }
249  if (llvm::TimePassesIsEnabled)
250    BackendArgs.push_back("-time-passes");
251  for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
252    BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
253  BackendArgs.push_back(0);
254  llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
255                                    const_cast<char **>(&BackendArgs[0]));
256
257  std::string FeaturesStr;
258  if (TargetOpts.CPU.size() || TargetOpts.Features.size()) {
259    SubtargetFeatures Features;
260    Features.setCPU(TargetOpts.CPU);
261    for (std::vector<std::string>::const_iterator
262           it = TargetOpts.Features.begin(),
263           ie = TargetOpts.Features.end(); it != ie; ++it)
264      Features.AddFeature(*it);
265    FeaturesStr = Features.getString();
266  }
267  TargetMachine *TM = TheTarget->createTargetMachine(Triple, FeaturesStr);
268
269  if (CodeGenOpts.RelaxAll)
270    TM->setMCRelaxAll(true);
271
272  // Create the code generator passes.
273  PassManager *PM = getCodeGenPasses();
274  CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
275
276  switch (CodeGenOpts.OptimizationLevel) {
277  default: break;
278  case 0: OptLevel = CodeGenOpt::None; break;
279  case 3: OptLevel = CodeGenOpt::Aggressive; break;
280  }
281
282  // Normal mode, emit a .s or .o file by running the code generator. Note,
283  // this also adds codegenerator level optimization passes.
284  TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
285  if (Action == Backend_EmitObj)
286    CGFT = TargetMachine::CGFT_ObjectFile;
287  else if (Action == Backend_EmitMCNull)
288    CGFT = TargetMachine::CGFT_Null;
289  else
290    assert(Action == Backend_EmitAssembly && "Invalid action!");
291  if (TM->addPassesToEmitFile(*PM, OS, CGFT, OptLevel,
292                              /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
293    Diags.Report(diag::err_fe_unable_to_interface_with_target);
294    return false;
295  }
296
297  return true;
298}
299
300void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
301  TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : 0);
302  llvm::formatted_raw_ostream FormattedOS;
303
304  CreatePasses();
305  switch (Action) {
306  case Backend_EmitNothing:
307    break;
308
309  case Backend_EmitBC:
310    getPerModulePasses()->add(createBitcodeWriterPass(*OS));
311    break;
312
313  case Backend_EmitLL:
314    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
315    getPerModulePasses()->add(createPrintModulePass(&FormattedOS));
316    break;
317
318  default:
319    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
320    if (!AddEmitPasses(Action, FormattedOS))
321      return;
322  }
323
324  // Run passes. For now we do all passes at once, but eventually we
325  // would like to have the option of streaming code generation.
326
327  if (PerFunctionPasses) {
328    PrettyStackTraceString CrashInfo("Per-function optimization");
329
330    PerFunctionPasses->doInitialization();
331    for (Module::iterator I = TheModule->begin(),
332           E = TheModule->end(); I != E; ++I)
333      if (!I->isDeclaration())
334        PerFunctionPasses->run(*I);
335    PerFunctionPasses->doFinalization();
336  }
337
338  if (PerModulePasses) {
339    PrettyStackTraceString CrashInfo("Per-module optimization passes");
340    PerModulePasses->run(*TheModule);
341  }
342
343  if (CodeGenPasses) {
344    PrettyStackTraceString CrashInfo("Code generation");
345    CodeGenPasses->run(*TheModule);
346  }
347}
348
349void clang::EmitBackendOutput(Diagnostic &Diags, const CodeGenOptions &CGOpts,
350                              const TargetOptions &TOpts, Module *M,
351                              BackendAction Action, raw_ostream *OS) {
352  EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, M);
353
354  AsmHelper.EmitAssembly(Action, OS);
355}
356