InitPreprocessor.cpp revision 207619 
1//===--- InitPreprocessor.cpp - PP initialization code. ---------*- C++ -*-===//
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// This file implements the clang::InitializePreprocessor function.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Basic/Version.h"
15#include "clang/Frontend/Utils.h"
16#include "clang/Basic/MacroBuilder.h"
17#include "clang/Basic/TargetInfo.h"
18#include "clang/Frontend/FrontendDiagnostic.h"
19#include "clang/Frontend/FrontendOptions.h"
20#include "clang/Frontend/PreprocessorOptions.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/Basic/FileManager.h"
23#include "clang/Basic/SourceManager.h"
24#include "llvm/ADT/APFloat.h"
25#include "llvm/Support/MemoryBuffer.h"
26#include "llvm/System/Path.h"
27using namespace clang;
28
29// Append a #define line to Buf for Macro.  Macro should be of the form XXX,
30// in which case we emit "#define XXX 1" or "XXX=Y z W" in which case we emit
31// "#define XXX Y z W".  To get a #define with no value, use "XXX=".
32static void DefineBuiltinMacro(MacroBuilder &Builder, llvm::StringRef Macro,
33                               Diagnostic &Diags) {
34  std::pair<llvm::StringRef, llvm::StringRef> MacroPair = Macro.split('=');
35  llvm::StringRef MacroName = MacroPair.first;
36  llvm::StringRef MacroBody = MacroPair.second;
37  if (MacroName.size() != Macro.size()) {
38    // Per GCC -D semantics, the macro ends at \n if it exists.
39    llvm::StringRef::size_type End = MacroBody.find_first_of("\n\r");
40    if (End != llvm::StringRef::npos)
41      Diags.Report(diag::warn_fe_macro_contains_embedded_newline)
42        << MacroName;
43    Builder.defineMacro(MacroName, MacroBody.substr(0, End));
44  } else {
45    // Push "macroname 1".
46    Builder.defineMacro(Macro);
47  }
48}
49
50std::string clang::NormalizeDashIncludePath(llvm::StringRef File) {
51  // Implicit include paths should be resolved relative to the current
52  // working directory first, and then use the regular header search
53  // mechanism. The proper way to handle this is to have the
54  // predefines buffer located at the current working directory, but
55  // it has not file entry. For now, workaround this by using an
56  // absolute path if we find the file here, and otherwise letting
57  // header search handle it.
58  llvm::sys::Path Path(File);
59  Path.makeAbsolute();
60  if (!Path.exists())
61    Path = File;
62
63  return Lexer::Stringify(Path.str());
64}
65
66/// AddImplicitInclude - Add an implicit #include of the specified file to the
67/// predefines buffer.
68static void AddImplicitInclude(MacroBuilder &Builder, llvm::StringRef File) {
69  Builder.append("#include \"" +
70                 llvm::Twine(NormalizeDashIncludePath(File)) + "\"");
71}
72
73static void AddImplicitIncludeMacros(MacroBuilder &Builder,
74                                     llvm::StringRef File) {
75  Builder.append("#__include_macros \"" +
76                 llvm::Twine(NormalizeDashIncludePath(File)) + "\"");
77  // Marker token to stop the __include_macros fetch loop.
78  Builder.append("##"); // ##?
79}
80
81/// AddImplicitIncludePTH - Add an implicit #include using the original file
82///  used to generate a PTH cache.
83static void AddImplicitIncludePTH(MacroBuilder &Builder, Preprocessor &PP,
84                                  llvm::StringRef ImplicitIncludePTH) {
85  PTHManager *P = PP.getPTHManager();
86  assert(P && "No PTHManager.");
87  const char *OriginalFile = P->getOriginalSourceFile();
88
89  if (!OriginalFile) {
90    PP.getDiagnostics().Report(diag::err_fe_pth_file_has_no_source_header)
91      << ImplicitIncludePTH;
92    return;
93  }
94
95  AddImplicitInclude(Builder, OriginalFile);
96}
97
98/// PickFP - This is used to pick a value based on the FP semantics of the
99/// specified FP model.
100template <typename T>
101static T PickFP(const llvm::fltSemantics *Sem, T IEEESingleVal,
102                T IEEEDoubleVal, T X87DoubleExtendedVal, T PPCDoubleDoubleVal,
103                T IEEEQuadVal) {
104  if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEsingle)
105    return IEEESingleVal;
106  if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEdouble)
107    return IEEEDoubleVal;
108  if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::x87DoubleExtended)
109    return X87DoubleExtendedVal;
110  if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::PPCDoubleDouble)
111    return PPCDoubleDoubleVal;
112  assert(Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEquad);
113  return IEEEQuadVal;
114}
115
116static void DefineFloatMacros(MacroBuilder &Builder, llvm::StringRef Prefix,
117                              const llvm::fltSemantics *Sem) {
118  const char *DenormMin, *Epsilon, *Max, *Min;
119  DenormMin = PickFP(Sem, "1.40129846e-45F", "4.9406564584124654e-324",
120                     "3.64519953188247460253e-4951L",
121                     "4.94065645841246544176568792868221e-324L",
122                     "6.47517511943802511092443895822764655e-4966L");
123  int Digits = PickFP(Sem, 6, 15, 18, 31, 33);
124  Epsilon = PickFP(Sem, "1.19209290e-7F", "2.2204460492503131e-16",
125                   "1.08420217248550443401e-19L",
126                   "4.94065645841246544176568792868221e-324L",
127                   "1.92592994438723585305597794258492732e-34L");
128  int MantissaDigits = PickFP(Sem, 24, 53, 64, 106, 113);
129  int Min10Exp = PickFP(Sem, -37, -307, -4931, -291, -4931);
130  int Max10Exp = PickFP(Sem, 38, 308, 4932, 308, 4932);
131  int MinExp = PickFP(Sem, -125, -1021, -16381, -968, -16381);
132  int MaxExp = PickFP(Sem, 128, 1024, 16384, 1024, 16384);
133  Min = PickFP(Sem, "1.17549435e-38F", "2.2250738585072014e-308",
134               "3.36210314311209350626e-4932L",
135               "2.00416836000897277799610805135016e-292L",
136               "3.36210314311209350626267781732175260e-4932L");
137  Max = PickFP(Sem, "3.40282347e+38F", "1.7976931348623157e+308",
138               "1.18973149535723176502e+4932L",
139               "1.79769313486231580793728971405301e+308L",
140               "1.18973149535723176508575932662800702e+4932L");
141
142  llvm::SmallString<32> DefPrefix;
143  DefPrefix = "__";
144  DefPrefix += Prefix;
145  DefPrefix += "_";
146
147  Builder.defineMacro(DefPrefix + "DENORM_MIN__", DenormMin);
148  Builder.defineMacro(DefPrefix + "HAS_DENORM__");
149  Builder.defineMacro(DefPrefix + "DIG__", llvm::Twine(Digits));
150  Builder.defineMacro(DefPrefix + "EPSILON__", llvm::Twine(Epsilon));
151  Builder.defineMacro(DefPrefix + "HAS_INFINITY__");
152  Builder.defineMacro(DefPrefix + "HAS_QUIET_NAN__");
153  Builder.defineMacro(DefPrefix + "MANT_DIG__", llvm::Twine(MantissaDigits));
154
155  Builder.defineMacro(DefPrefix + "MAX_10_EXP__", llvm::Twine(Max10Exp));
156  Builder.defineMacro(DefPrefix + "MAX_EXP__", llvm::Twine(MaxExp));
157  Builder.defineMacro(DefPrefix + "MAX__", llvm::Twine(Max));
158
159  Builder.defineMacro(DefPrefix + "MIN_10_EXP__","("+llvm::Twine(Min10Exp)+")");
160  Builder.defineMacro(DefPrefix + "MIN_EXP__", "("+llvm::Twine(MinExp)+")");
161  Builder.defineMacro(DefPrefix + "MIN__", llvm::Twine(Min));
162}
163
164
165/// DefineTypeSize - Emit a macro to the predefines buffer that declares a macro
166/// named MacroName with the max value for a type with width 'TypeWidth' a
167/// signedness of 'isSigned' and with a value suffix of 'ValSuffix' (e.g. LL).
168static void DefineTypeSize(llvm::StringRef MacroName, unsigned TypeWidth,
169                           llvm::StringRef ValSuffix, bool isSigned,
170                           MacroBuilder& Builder) {
171  long long MaxVal;
172  if (isSigned)
173    MaxVal = (1LL << (TypeWidth - 1)) - 1;
174  else
175    MaxVal = ~0LL >> (64-TypeWidth);
176
177  Builder.defineMacro(MacroName, llvm::Twine(MaxVal) + ValSuffix);
178}
179
180/// DefineTypeSize - An overloaded helper that uses TargetInfo to determine
181/// the width, suffix, and signedness of the given type
182static void DefineTypeSize(llvm::StringRef MacroName, TargetInfo::IntType Ty,
183                           const TargetInfo &TI, MacroBuilder &Builder) {
184  DefineTypeSize(MacroName, TI.getTypeWidth(Ty), TI.getTypeConstantSuffix(Ty),
185                 TI.isTypeSigned(Ty), Builder);
186}
187
188static void DefineType(const llvm::Twine &MacroName, TargetInfo::IntType Ty,
189                       MacroBuilder &Builder) {
190  Builder.defineMacro(MacroName, TargetInfo::getTypeName(Ty));
191}
192
193static void DefineTypeWidth(llvm::StringRef MacroName, TargetInfo::IntType Ty,
194                            const TargetInfo &TI, MacroBuilder &Builder) {
195  Builder.defineMacro(MacroName, llvm::Twine(TI.getTypeWidth(Ty)));
196}
197
198static void DefineExactWidthIntType(TargetInfo::IntType Ty,
199                               const TargetInfo &TI, MacroBuilder &Builder) {
200  int TypeWidth = TI.getTypeWidth(Ty);
201  DefineType("__INT" + llvm::Twine(TypeWidth) + "_TYPE__", Ty, Builder);
202
203  llvm::StringRef ConstSuffix(TargetInfo::getTypeConstantSuffix(Ty));
204  if (!ConstSuffix.empty())
205    Builder.defineMacro("__INT" + llvm::Twine(TypeWidth) + "_C_SUFFIX__",
206                        ConstSuffix);
207}
208
209static void InitializePredefinedMacros(const TargetInfo &TI,
210                                       const LangOptions &LangOpts,
211                                       const FrontendOptions &FEOpts,
212                                       MacroBuilder &Builder) {
213  // Compiler version introspection macros.
214  Builder.defineMacro("__llvm__");  // LLVM Backend
215  Builder.defineMacro("__clang__"); // Clang Frontend
216#define TOSTR2(X) #X
217#define TOSTR(X) TOSTR2(X)
218  Builder.defineMacro("__clang_major__", TOSTR(CLANG_VERSION_MAJOR));
219  Builder.defineMacro("__clang_minor__", TOSTR(CLANG_VERSION_MINOR));
220#ifdef CLANG_VERSION_PATCHLEVEL
221  Builder.defineMacro("__clang_patchlevel__", TOSTR(CLANG_VERSION_PATCHLEVEL));
222#else
223  Builder.defineMacro("__clang_patchlevel__", "0");
224#endif
225  Builder.defineMacro("__clang_version__",
226                      "\"" CLANG_VERSION_STRING " ("
227                      + getClangFullRepositoryVersion() + ")\"");
228#undef TOSTR
229#undef TOSTR2
230  // Currently claim to be compatible with GCC 4.2.1-5621.
231  Builder.defineMacro("__GNUC_MINOR__", "2");
232  Builder.defineMacro("__GNUC_PATCHLEVEL__", "1");
233  Builder.defineMacro("__GNUC__", "4");
234  Builder.defineMacro("__GXX_ABI_VERSION", "1002");
235  Builder.defineMacro("__VERSION__", "\"4.2.1 Compatible Clang Compiler\"");
236
237  // Initialize language-specific preprocessor defines.
238
239  // These should all be defined in the preprocessor according to the
240  // current language configuration.
241  if (!LangOpts.Microsoft)
242    Builder.defineMacro("__STDC__");
243  if (LangOpts.AsmPreprocessor)
244    Builder.defineMacro("__ASSEMBLER__");
245
246  if (!LangOpts.CPlusPlus) {
247    if (LangOpts.C99)
248      Builder.defineMacro("__STDC_VERSION__", "199901L");
249    else if (!LangOpts.GNUMode && LangOpts.Digraphs)
250      Builder.defineMacro("__STDC_VERSION__", "199409L");
251  }
252
253  // Standard conforming mode?
254  if (!LangOpts.GNUMode)
255    Builder.defineMacro("__STRICT_ANSI__");
256
257  if (LangOpts.CPlusPlus0x)
258    Builder.defineMacro("__GXX_EXPERIMENTAL_CXX0X__");
259
260  if (LangOpts.Freestanding)
261    Builder.defineMacro("__STDC_HOSTED__", "0");
262  else
263    Builder.defineMacro("__STDC_HOSTED__");
264
265  if (LangOpts.ObjC1) {
266    Builder.defineMacro("__OBJC__");
267    if (LangOpts.ObjCNonFragileABI) {
268      Builder.defineMacro("__OBJC2__");
269      Builder.defineMacro("OBJC_ZEROCOST_EXCEPTIONS");
270    }
271
272    if (LangOpts.getGCMode() != LangOptions::NonGC)
273      Builder.defineMacro("__OBJC_GC__");
274
275    if (LangOpts.NeXTRuntime)
276      Builder.defineMacro("__NEXT_RUNTIME__");
277  }
278
279  // darwin_constant_cfstrings controls this. This is also dependent
280  // on other things like the runtime I believe.  This is set even for C code.
281  Builder.defineMacro("__CONSTANT_CFSTRINGS__");
282
283  if (LangOpts.ObjC2)
284    Builder.defineMacro("OBJC_NEW_PROPERTIES");
285
286  if (LangOpts.PascalStrings)
287    Builder.defineMacro("__PASCAL_STRINGS__");
288
289  if (LangOpts.Blocks) {
290    Builder.defineMacro("__block", "__attribute__((__blocks__(byref)))");
291    Builder.defineMacro("__BLOCKS__");
292  }
293
294  if (LangOpts.Exceptions)
295    Builder.defineMacro("__EXCEPTIONS");
296  if (LangOpts.SjLjExceptions)
297    Builder.defineMacro("__USING_SJLJ_EXCEPTIONS__");
298
299  if (LangOpts.CPlusPlus) {
300    Builder.defineMacro("__DEPRECATED");
301    Builder.defineMacro("__GNUG__", "4");
302    Builder.defineMacro("__GXX_WEAK__");
303    if (LangOpts.GNUMode)
304      Builder.defineMacro("__cplusplus");
305    else
306      // C++ [cpp.predefined]p1:
307      //   The name_ _cplusplusis defined to the value199711Lwhen compiling a
308      //   C++ translation unit.
309      Builder.defineMacro("__cplusplus", "199711L");
310    Builder.defineMacro("__private_extern__", "extern");
311  }
312
313  if (LangOpts.Microsoft) {
314    // Filter out some microsoft extensions when trying to parse in ms-compat
315    // mode.
316    Builder.defineMacro("__int8", "__INT8_TYPE__");
317    Builder.defineMacro("__int16", "__INT16_TYPE__");
318    Builder.defineMacro("__int32", "__INT32_TYPE__");
319    Builder.defineMacro("__int64", "__INT64_TYPE__");
320    // Both __PRETTY_FUNCTION__ and __FUNCTION__ are GCC extensions, however
321    // VC++ appears to only like __FUNCTION__.
322    Builder.defineMacro("__PRETTY_FUNCTION__", "__FUNCTION__");
323    // Work around some issues with Visual C++ headerws.
324    if (LangOpts.CPlusPlus) {
325      // Since we define wchar_t in C++ mode.
326      Builder.defineMacro("_WCHAR_T_DEFINED");
327      Builder.defineMacro("_NATIVE_WCHAR_T_DEFINED");
328      // FIXME:  This should be temporary until we have a __pragma
329      // solution, to avoid some errors flagged in VC++ headers.
330      Builder.defineMacro("_CRT_SECURE_CPP_OVERLOAD_SECURE_NAMES", "0");
331    }
332  }
333
334  if (LangOpts.Optimize)
335    Builder.defineMacro("__OPTIMIZE__");
336  if (LangOpts.OptimizeSize)
337    Builder.defineMacro("__OPTIMIZE_SIZE__");
338
339  // Initialize target-specific preprocessor defines.
340
341  // Define type sizing macros based on the target properties.
342  assert(TI.getCharWidth() == 8 && "Only support 8-bit char so far");
343  Builder.defineMacro("__CHAR_BIT__", "8");
344
345  DefineTypeSize("__SCHAR_MAX__", TI.getCharWidth(), "", true, Builder);
346  DefineTypeSize("__SHRT_MAX__", TargetInfo::SignedShort, TI, Builder);
347  DefineTypeSize("__INT_MAX__", TargetInfo::SignedInt, TI, Builder);
348  DefineTypeSize("__LONG_MAX__", TargetInfo::SignedLong, TI, Builder);
349  DefineTypeSize("__LONG_LONG_MAX__", TargetInfo::SignedLongLong, TI, Builder);
350  DefineTypeSize("__WCHAR_MAX__", TI.getWCharType(), TI, Builder);
351  DefineTypeSize("__INTMAX_MAX__", TI.getIntMaxType(), TI, Builder);
352
353  DefineType("__INTMAX_TYPE__", TI.getIntMaxType(), Builder);
354  DefineType("__UINTMAX_TYPE__", TI.getUIntMaxType(), Builder);
355  DefineTypeWidth("__INTMAX_WIDTH__",  TI.getIntMaxType(), TI, Builder);
356  DefineType("__PTRDIFF_TYPE__", TI.getPtrDiffType(0), Builder);
357  DefineTypeWidth("__PTRDIFF_WIDTH__", TI.getPtrDiffType(0), TI, Builder);
358  DefineType("__INTPTR_TYPE__", TI.getIntPtrType(), Builder);
359  DefineTypeWidth("__INTPTR_WIDTH__", TI.getIntPtrType(), TI, Builder);
360  DefineType("__SIZE_TYPE__", TI.getSizeType(), Builder);
361  DefineTypeWidth("__SIZE_WIDTH__", TI.getSizeType(), TI, Builder);
362  DefineType("__WCHAR_TYPE__", TI.getWCharType(), Builder);
363  DefineTypeWidth("__WCHAR_WIDTH__", TI.getWCharType(), TI, Builder);
364  DefineType("__WINT_TYPE__", TI.getWIntType(), Builder);
365  DefineTypeWidth("__WINT_WIDTH__", TI.getWIntType(), TI, Builder);
366  DefineTypeWidth("__SIG_ATOMIC_WIDTH__", TI.getSigAtomicType(), TI, Builder);
367
368  DefineFloatMacros(Builder, "FLT", &TI.getFloatFormat());
369  DefineFloatMacros(Builder, "DBL", &TI.getDoubleFormat());
370  DefineFloatMacros(Builder, "LDBL", &TI.getLongDoubleFormat());
371
372  // Define a __POINTER_WIDTH__ macro for stdint.h.
373  Builder.defineMacro("__POINTER_WIDTH__",
374                      llvm::Twine((int)TI.getPointerWidth(0)));
375
376  if (!LangOpts.CharIsSigned)
377    Builder.defineMacro("__CHAR_UNSIGNED__");
378
379  // Define exact-width integer types for stdint.h
380  Builder.defineMacro("__INT" + llvm::Twine(TI.getCharWidth()) + "_TYPE__",
381                      "char");
382
383  if (TI.getShortWidth() > TI.getCharWidth())
384    DefineExactWidthIntType(TargetInfo::SignedShort, TI, Builder);
385
386  if (TI.getIntWidth() > TI.getShortWidth())
387    DefineExactWidthIntType(TargetInfo::SignedInt, TI, Builder);
388
389  if (TI.getLongWidth() > TI.getIntWidth())
390    DefineExactWidthIntType(TargetInfo::SignedLong, TI, Builder);
391
392  if (TI.getLongLongWidth() > TI.getLongWidth())
393    DefineExactWidthIntType(TargetInfo::SignedLongLong, TI, Builder);
394
395  // Add __builtin_va_list typedef.
396  Builder.append(TI.getVAListDeclaration());
397
398  if (const char *Prefix = TI.getUserLabelPrefix())
399    Builder.defineMacro("__USER_LABEL_PREFIX__", Prefix);
400
401  // Build configuration options.  FIXME: these should be controlled by
402  // command line options or something.
403  Builder.defineMacro("__FINITE_MATH_ONLY__", "0");
404
405  if (LangOpts.GNUInline)
406    Builder.defineMacro("__GNUC_GNU_INLINE__");
407  else
408    Builder.defineMacro("__GNUC_STDC_INLINE__");
409
410  if (LangOpts.NoInline)
411    Builder.defineMacro("__NO_INLINE__");
412
413  if (unsigned PICLevel = LangOpts.PICLevel) {
414    Builder.defineMacro("__PIC__", llvm::Twine(PICLevel));
415    Builder.defineMacro("__pic__", llvm::Twine(PICLevel));
416  }
417
418  // Macros to control C99 numerics and <float.h>
419  Builder.defineMacro("__FLT_EVAL_METHOD__", "0");
420  Builder.defineMacro("__FLT_RADIX__", "2");
421  int Dig = PickFP(&TI.getLongDoubleFormat(), -1/*FIXME*/, 17, 21, 33, 36);
422  Builder.defineMacro("__DECIMAL_DIG__", llvm::Twine(Dig));
423
424  if (LangOpts.getStackProtectorMode() == LangOptions::SSPOn)
425    Builder.defineMacro("__SSP__");
426  else if (LangOpts.getStackProtectorMode() == LangOptions::SSPReq)
427    Builder.defineMacro("__SSP_ALL__", "2");
428
429  if (FEOpts.ProgramAction == frontend::RewriteObjC)
430    Builder.defineMacro("__weak", "__attribute__((objc_gc(weak)))");
431  // Get other target #defines.
432  TI.getTargetDefines(LangOpts, Builder);
433}
434
435// Initialize the remapping of files to alternative contents, e.g.,
436// those specified through other files.
437static void InitializeFileRemapping(Diagnostic &Diags,
438                                    SourceManager &SourceMgr,
439                                    FileManager &FileMgr,
440                                    const PreprocessorOptions &InitOpts) {
441  // Remap files in the source manager (with buffers).
442  for (PreprocessorOptions::remapped_file_buffer_iterator
443         Remap = InitOpts.remapped_file_buffer_begin(),
444         RemapEnd = InitOpts.remapped_file_buffer_end();
445       Remap != RemapEnd;
446       ++Remap) {
447    // Create the file entry for the file that we're mapping from.
448    const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
449                                                Remap->second->getBufferSize(),
450                                                       0);
451    if (!FromFile) {
452      Diags.Report(diag::err_fe_remap_missing_from_file)
453        << Remap->first;
454      delete Remap->second;
455      continue;
456    }
457
458    // Override the contents of the "from" file with the contents of
459    // the "to" file.
460    SourceMgr.overrideFileContents(FromFile, Remap->second);
461  }
462
463  // Remap files in the source manager (with other files).
464  for (PreprocessorOptions::remapped_file_iterator
465       Remap = InitOpts.remapped_file_begin(),
466       RemapEnd = InitOpts.remapped_file_end();
467       Remap != RemapEnd;
468       ++Remap) {
469    // Find the file that we're mapping to.
470    const FileEntry *ToFile = FileMgr.getFile(Remap->second);
471    if (!ToFile) {
472      Diags.Report(diag::err_fe_remap_missing_to_file)
473      << Remap->first << Remap->second;
474      continue;
475    }
476
477    // Create the file entry for the file that we're mapping from.
478    const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
479                                                       ToFile->getSize(),
480                                                       0);
481    if (!FromFile) {
482      Diags.Report(diag::err_fe_remap_missing_from_file)
483      << Remap->first;
484      continue;
485    }
486
487    // Load the contents of the file we're mapping to.
488    std::string ErrorStr;
489    const llvm::MemoryBuffer *Buffer
490    = llvm::MemoryBuffer::getFile(ToFile->getName(), &ErrorStr);
491    if (!Buffer) {
492      Diags.Report(diag::err_fe_error_opening)
493        << Remap->second << ErrorStr;
494      continue;
495    }
496
497    // Override the contents of the "from" file with the contents of
498    // the "to" file.
499    SourceMgr.overrideFileContents(FromFile, Buffer);
500  }
501}
502
503/// InitializePreprocessor - Initialize the preprocessor getting it and the
504/// environment ready to process a single file. This returns true on error.
505///
506void clang::InitializePreprocessor(Preprocessor &PP,
507                                   const PreprocessorOptions &InitOpts,
508                                   const HeaderSearchOptions &HSOpts,
509                                   const FrontendOptions &FEOpts) {
510  std::string PredefineBuffer;
511  PredefineBuffer.reserve(4080);
512  llvm::raw_string_ostream Predefines(PredefineBuffer);
513  MacroBuilder Builder(Predefines);
514
515  InitializeFileRemapping(PP.getDiagnostics(), PP.getSourceManager(),
516                          PP.getFileManager(), InitOpts);
517
518  // Emit line markers for various builtin sections of the file.  We don't do
519  // this in asm preprocessor mode, because "# 4" is not a line marker directive
520  // in this mode.
521  if (!PP.getLangOptions().AsmPreprocessor)
522    Builder.append("# 1 \"<built-in>\" 3");
523
524  // Install things like __POWERPC__, __GNUC__, etc into the macro table.
525  if (InitOpts.UsePredefines)
526    InitializePredefinedMacros(PP.getTargetInfo(), PP.getLangOptions(),
527                               FEOpts, Builder);
528
529  // Add on the predefines from the driver.  Wrap in a #line directive to report
530  // that they come from the command line.
531  if (!PP.getLangOptions().AsmPreprocessor)
532    Builder.append("# 1 \"<command line>\" 1");
533
534  // Process #define's and #undef's in the order they are given.
535  for (unsigned i = 0, e = InitOpts.Macros.size(); i != e; ++i) {
536    if (InitOpts.Macros[i].second)  // isUndef
537      Builder.undefineMacro(InitOpts.Macros[i].first);
538    else
539      DefineBuiltinMacro(Builder, InitOpts.Macros[i].first,
540                         PP.getDiagnostics());
541  }
542
543  // If -imacros are specified, include them now.  These are processed before
544  // any -include directives.
545  for (unsigned i = 0, e = InitOpts.MacroIncludes.size(); i != e; ++i)
546    AddImplicitIncludeMacros(Builder, InitOpts.MacroIncludes[i]);
547
548  // Process -include directives.
549  for (unsigned i = 0, e = InitOpts.Includes.size(); i != e; ++i) {
550    const std::string &Path = InitOpts.Includes[i];
551    if (Path == InitOpts.ImplicitPTHInclude)
552      AddImplicitIncludePTH(Builder, PP, Path);
553    else
554      AddImplicitInclude(Builder, Path);
555  }
556
557  // Exit the command line and go back to <built-in> (2 is LC_LEAVE).
558  if (!PP.getLangOptions().AsmPreprocessor)
559    Builder.append("# 1 \"<built-in>\" 2");
560
561  // Copy PredefinedBuffer into the Preprocessor.
562  PP.setPredefines(Predefines.str());
563
564  // Initialize the header search object.
565  ApplyHeaderSearchOptions(PP.getHeaderSearchInfo(), HSOpts,
566                           PP.getLangOptions(),
567                           PP.getTargetInfo().getTriple());
568}
569