xref: /llvm-project/clang/lib/Frontend/InitPreprocessor.cpp (revision 61d818c0581bc7471addbd30a98bcbb80c2942f4)
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/FileSystem.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 #include "llvm/Support/Path.h"
28 using namespace clang;
29 
30 // Append a #define line to Buf for Macro.  Macro should be of the form XXX,
31 // in which case we emit "#define XXX 1" or "XXX=Y z W" in which case we emit
32 // "#define XXX Y z W".  To get a #define with no value, use "XXX=".
33 static void DefineBuiltinMacro(MacroBuilder &Builder, llvm::StringRef Macro,
34                                Diagnostic &Diags) {
35   std::pair<llvm::StringRef, llvm::StringRef> MacroPair = Macro.split('=');
36   llvm::StringRef MacroName = MacroPair.first;
37   llvm::StringRef MacroBody = MacroPair.second;
38   if (MacroName.size() != Macro.size()) {
39     // Per GCC -D semantics, the macro ends at \n if it exists.
40     llvm::StringRef::size_type End = MacroBody.find_first_of("\n\r");
41     if (End != llvm::StringRef::npos)
42       Diags.Report(diag::warn_fe_macro_contains_embedded_newline)
43         << MacroName;
44     Builder.defineMacro(MacroName, MacroBody.substr(0, End));
45   } else {
46     // Push "macroname 1".
47     Builder.defineMacro(Macro);
48   }
49 }
50 
51 std::string clang::NormalizeDashIncludePath(llvm::StringRef File,
52                                             FileManager &FileMgr) {
53   // Implicit include paths should be resolved relative to the current
54   // working directory first, and then use the regular header search
55   // mechanism. The proper way to handle this is to have the
56   // predefines buffer located at the current working directory, but
57   // it has no file entry. For now, workaround this by using an
58   // absolute path if we find the file here, and otherwise letting
59   // header search handle it.
60   llvm::SmallString<128> Path(File);
61   llvm::sys::fs::make_absolute(Path);
62   bool exists;
63   if (llvm::sys::fs::exists(Path.str(), exists) || !exists)
64     Path = File;
65   else if (exists)
66     FileMgr.getFile(File);
67 
68   return Lexer::Stringify(Path.str());
69 }
70 
71 /// AddImplicitInclude - Add an implicit #include of the specified file to the
72 /// predefines buffer.
73 static void AddImplicitInclude(MacroBuilder &Builder, llvm::StringRef File,
74                                FileManager &FileMgr) {
75   Builder.append("#include \"" +
76                  llvm::Twine(NormalizeDashIncludePath(File, FileMgr)) + "\"");
77 }
78 
79 static void AddImplicitIncludeMacros(MacroBuilder &Builder,
80                                      llvm::StringRef File,
81                                      FileManager &FileMgr) {
82   Builder.append("#__include_macros \"" +
83                  llvm::Twine(NormalizeDashIncludePath(File, FileMgr)) + "\"");
84   // Marker token to stop the __include_macros fetch loop.
85   Builder.append("##"); // ##?
86 }
87 
88 /// AddImplicitIncludePTH - Add an implicit #include using the original file
89 ///  used to generate a PTH cache.
90 static void AddImplicitIncludePTH(MacroBuilder &Builder, Preprocessor &PP,
91                                   llvm::StringRef ImplicitIncludePTH) {
92   PTHManager *P = PP.getPTHManager();
93   // Null check 'P' in the corner case where it couldn't be created.
94   const char *OriginalFile = P ? P->getOriginalSourceFile() : 0;
95 
96   if (!OriginalFile) {
97     PP.getDiagnostics().Report(diag::err_fe_pth_file_has_no_source_header)
98       << ImplicitIncludePTH;
99     return;
100   }
101 
102   AddImplicitInclude(Builder, OriginalFile, PP.getFileManager());
103 }
104 
105 /// PickFP - This is used to pick a value based on the FP semantics of the
106 /// specified FP model.
107 template <typename T>
108 static T PickFP(const llvm::fltSemantics *Sem, T IEEESingleVal,
109                 T IEEEDoubleVal, T X87DoubleExtendedVal, T PPCDoubleDoubleVal,
110                 T IEEEQuadVal) {
111   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEsingle)
112     return IEEESingleVal;
113   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEdouble)
114     return IEEEDoubleVal;
115   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::x87DoubleExtended)
116     return X87DoubleExtendedVal;
117   if (Sem == (const llvm::fltSemantics*)&llvm::APFloat::PPCDoubleDouble)
118     return PPCDoubleDoubleVal;
119   assert(Sem == (const llvm::fltSemantics*)&llvm::APFloat::IEEEquad);
120   return IEEEQuadVal;
121 }
122 
123 static void DefineFloatMacros(MacroBuilder &Builder, llvm::StringRef Prefix,
124                               const llvm::fltSemantics *Sem) {
125   const char *DenormMin, *Epsilon, *Max, *Min;
126   DenormMin = PickFP(Sem, "1.40129846e-45F", "4.9406564584124654e-324",
127                      "3.64519953188247460253e-4951L",
128                      "4.94065645841246544176568792868221e-324L",
129                      "6.47517511943802511092443895822764655e-4966L");
130   int Digits = PickFP(Sem, 6, 15, 18, 31, 33);
131   Epsilon = PickFP(Sem, "1.19209290e-7F", "2.2204460492503131e-16",
132                    "1.08420217248550443401e-19L",
133                    "4.94065645841246544176568792868221e-324L",
134                    "1.92592994438723585305597794258492732e-34L");
135   int MantissaDigits = PickFP(Sem, 24, 53, 64, 106, 113);
136   int Min10Exp = PickFP(Sem, -37, -307, -4931, -291, -4931);
137   int Max10Exp = PickFP(Sem, 38, 308, 4932, 308, 4932);
138   int MinExp = PickFP(Sem, -125, -1021, -16381, -968, -16381);
139   int MaxExp = PickFP(Sem, 128, 1024, 16384, 1024, 16384);
140   Min = PickFP(Sem, "1.17549435e-38F", "2.2250738585072014e-308",
141                "3.36210314311209350626e-4932L",
142                "2.00416836000897277799610805135016e-292L",
143                "3.36210314311209350626267781732175260e-4932L");
144   Max = PickFP(Sem, "3.40282347e+38F", "1.7976931348623157e+308",
145                "1.18973149535723176502e+4932L",
146                "1.79769313486231580793728971405301e+308L",
147                "1.18973149535723176508575932662800702e+4932L");
148 
149   llvm::SmallString<32> DefPrefix;
150   DefPrefix = "__";
151   DefPrefix += Prefix;
152   DefPrefix += "_";
153 
154   Builder.defineMacro(DefPrefix + "DENORM_MIN__", DenormMin);
155   Builder.defineMacro(DefPrefix + "HAS_DENORM__");
156   Builder.defineMacro(DefPrefix + "DIG__", llvm::Twine(Digits));
157   Builder.defineMacro(DefPrefix + "EPSILON__", llvm::Twine(Epsilon));
158   Builder.defineMacro(DefPrefix + "HAS_INFINITY__");
159   Builder.defineMacro(DefPrefix + "HAS_QUIET_NAN__");
160   Builder.defineMacro(DefPrefix + "MANT_DIG__", llvm::Twine(MantissaDigits));
161 
162   Builder.defineMacro(DefPrefix + "MAX_10_EXP__", llvm::Twine(Max10Exp));
163   Builder.defineMacro(DefPrefix + "MAX_EXP__", llvm::Twine(MaxExp));
164   Builder.defineMacro(DefPrefix + "MAX__", llvm::Twine(Max));
165 
166   Builder.defineMacro(DefPrefix + "MIN_10_EXP__","("+llvm::Twine(Min10Exp)+")");
167   Builder.defineMacro(DefPrefix + "MIN_EXP__", "("+llvm::Twine(MinExp)+")");
168   Builder.defineMacro(DefPrefix + "MIN__", llvm::Twine(Min));
169 }
170 
171 
172 /// DefineTypeSize - Emit a macro to the predefines buffer that declares a macro
173 /// named MacroName with the max value for a type with width 'TypeWidth' a
174 /// signedness of 'isSigned' and with a value suffix of 'ValSuffix' (e.g. LL).
175 static void DefineTypeSize(llvm::StringRef MacroName, unsigned TypeWidth,
176                            llvm::StringRef ValSuffix, bool isSigned,
177                            MacroBuilder &Builder) {
178   llvm::APInt MaxVal = isSigned ? llvm::APInt::getSignedMaxValue(TypeWidth)
179                                 : llvm::APInt::getMaxValue(TypeWidth);
180   Builder.defineMacro(MacroName, MaxVal.toString(10, isSigned) + ValSuffix);
181 }
182 
183 /// DefineTypeSize - An overloaded helper that uses TargetInfo to determine
184 /// the width, suffix, and signedness of the given type
185 static void DefineTypeSize(llvm::StringRef MacroName, TargetInfo::IntType Ty,
186                            const TargetInfo &TI, MacroBuilder &Builder) {
187   DefineTypeSize(MacroName, TI.getTypeWidth(Ty), TI.getTypeConstantSuffix(Ty),
188                  TI.isTypeSigned(Ty), Builder);
189 }
190 
191 static void DefineType(const llvm::Twine &MacroName, TargetInfo::IntType Ty,
192                        MacroBuilder &Builder) {
193   Builder.defineMacro(MacroName, TargetInfo::getTypeName(Ty));
194 }
195 
196 static void DefineTypeWidth(llvm::StringRef MacroName, TargetInfo::IntType Ty,
197                             const TargetInfo &TI, MacroBuilder &Builder) {
198   Builder.defineMacro(MacroName, llvm::Twine(TI.getTypeWidth(Ty)));
199 }
200 
201 static void DefineTypeSizeof(llvm::StringRef MacroName, unsigned BitWidth,
202                              const TargetInfo &TI, MacroBuilder &Builder) {
203   Builder.defineMacro(MacroName,
204                       llvm::Twine(BitWidth / TI.getCharWidth()));
205 }
206 
207 static void DefineExactWidthIntType(TargetInfo::IntType Ty,
208                                const TargetInfo &TI, MacroBuilder &Builder) {
209   int TypeWidth = TI.getTypeWidth(Ty);
210 
211   // Use the target specified int64 type, when appropriate, so that [u]int64_t
212   // ends up being defined in terms of the correct type.
213   if (TypeWidth == 64)
214     Ty = TI.getInt64Type();
215 
216   DefineType("__INT" + llvm::Twine(TypeWidth) + "_TYPE__", Ty, Builder);
217 
218   llvm::StringRef ConstSuffix(TargetInfo::getTypeConstantSuffix(Ty));
219   if (!ConstSuffix.empty())
220     Builder.defineMacro("__INT" + llvm::Twine(TypeWidth) + "_C_SUFFIX__",
221                         ConstSuffix);
222 }
223 
224 static void InitializePredefinedMacros(const TargetInfo &TI,
225                                        const LangOptions &LangOpts,
226                                        const FrontendOptions &FEOpts,
227                                        MacroBuilder &Builder) {
228   // Compiler version introspection macros.
229   Builder.defineMacro("__llvm__");  // LLVM Backend
230   Builder.defineMacro("__clang__"); // Clang Frontend
231 #define TOSTR2(X) #X
232 #define TOSTR(X) TOSTR2(X)
233   Builder.defineMacro("__clang_major__", TOSTR(CLANG_VERSION_MAJOR));
234   Builder.defineMacro("__clang_minor__", TOSTR(CLANG_VERSION_MINOR));
235 #ifdef CLANG_VERSION_PATCHLEVEL
236   Builder.defineMacro("__clang_patchlevel__", TOSTR(CLANG_VERSION_PATCHLEVEL));
237 #else
238   Builder.defineMacro("__clang_patchlevel__", "0");
239 #endif
240   Builder.defineMacro("__clang_version__",
241                       "\"" CLANG_VERSION_STRING " ("
242                       + getClangFullRepositoryVersion() + ")\"");
243 #undef TOSTR
244 #undef TOSTR2
245   // Currently claim to be compatible with GCC 4.2.1-5621.
246   Builder.defineMacro("__GNUC_MINOR__", "2");
247   Builder.defineMacro("__GNUC_PATCHLEVEL__", "1");
248   Builder.defineMacro("__GNUC__", "4");
249   Builder.defineMacro("__GXX_ABI_VERSION", "1002");
250 
251   // As sad as it is, enough software depends on the __VERSION__ for version
252   // checks that it is necessary to report 4.2.1 (the base GCC version we claim
253   // compatibility with) first.
254   Builder.defineMacro("__VERSION__", "\"4.2.1 Compatible " +
255                       llvm::Twine(getClangFullCPPVersion()) + "\"");
256 
257   // Initialize language-specific preprocessor defines.
258 
259   // These should all be defined in the preprocessor according to the
260   // current language configuration.
261   if (!LangOpts.Microsoft && !LangOpts.TraditionalCPP)
262     Builder.defineMacro("__STDC__");
263   if (LangOpts.AsmPreprocessor)
264     Builder.defineMacro("__ASSEMBLER__");
265 
266   if (!LangOpts.CPlusPlus) {
267     if (LangOpts.C99)
268       Builder.defineMacro("__STDC_VERSION__", "199901L");
269     else if (!LangOpts.GNUMode && LangOpts.Digraphs)
270       Builder.defineMacro("__STDC_VERSION__", "199409L");
271   }
272 
273   // Standard conforming mode?
274   if (!LangOpts.GNUMode)
275     Builder.defineMacro("__STRICT_ANSI__");
276 
277   if (LangOpts.CPlusPlus0x)
278     Builder.defineMacro("__GXX_EXPERIMENTAL_CXX0X__");
279 
280   if (LangOpts.Freestanding)
281     Builder.defineMacro("__STDC_HOSTED__", "0");
282   else
283     Builder.defineMacro("__STDC_HOSTED__");
284 
285   if (LangOpts.ObjC1) {
286     Builder.defineMacro("__OBJC__");
287     if (LangOpts.ObjCNonFragileABI) {
288       Builder.defineMacro("__OBJC2__");
289       Builder.defineMacro("OBJC_ZEROCOST_EXCEPTIONS");
290     }
291 
292     if (LangOpts.getGCMode() != LangOptions::NonGC)
293       Builder.defineMacro("__OBJC_GC__");
294 
295     if (LangOpts.NeXTRuntime)
296       Builder.defineMacro("__NEXT_RUNTIME__");
297   }
298 
299   // darwin_constant_cfstrings controls this. This is also dependent
300   // on other things like the runtime I believe.  This is set even for C code.
301   Builder.defineMacro("__CONSTANT_CFSTRINGS__");
302 
303   if (LangOpts.ObjC2)
304     Builder.defineMacro("OBJC_NEW_PROPERTIES");
305 
306   if (LangOpts.PascalStrings)
307     Builder.defineMacro("__PASCAL_STRINGS__");
308 
309   if (LangOpts.Blocks) {
310     Builder.defineMacro("__block", "__attribute__((__blocks__(byref)))");
311     Builder.defineMacro("__BLOCKS__");
312   }
313 
314   if (LangOpts.Exceptions)
315     Builder.defineMacro("__EXCEPTIONS");
316   if (LangOpts.RTTI)
317     Builder.defineMacro("__GXX_RTTI");
318   if (LangOpts.SjLjExceptions)
319     Builder.defineMacro("__USING_SJLJ_EXCEPTIONS__");
320 
321   if (LangOpts.Deprecated)
322     Builder.defineMacro("__DEPRECATED");
323 
324   if (LangOpts.CPlusPlus) {
325     Builder.defineMacro("__GNUG__", "4");
326     Builder.defineMacro("__GXX_WEAK__");
327     if (LangOpts.GNUMode)
328       Builder.defineMacro("__cplusplus");
329     else
330       // C++ [cpp.predefined]p1:
331       //   The name_ _cplusplusis defined to the value 199711L when compiling a
332       //   C++ translation unit.
333       Builder.defineMacro("__cplusplus", "199711L");
334     Builder.defineMacro("__private_extern__", "extern");
335   }
336 
337   if (LangOpts.Microsoft) {
338     // Both __PRETTY_FUNCTION__ and __FUNCTION__ are GCC extensions, however
339     // VC++ appears to only like __FUNCTION__.
340     Builder.defineMacro("__PRETTY_FUNCTION__", "__FUNCTION__");
341     // Work around some issues with Visual C++ headerws.
342     if (LangOpts.CPlusPlus) {
343       // Since we define wchar_t in C++ mode.
344       Builder.defineMacro("_WCHAR_T_DEFINED");
345       Builder.defineMacro("_NATIVE_WCHAR_T_DEFINED");
346       Builder.append("#define __identifier(x) x");
347       Builder.append("class type_info;");
348     }
349 
350     if (LangOpts.CPlusPlus0x) {
351       Builder.defineMacro("_HAS_CHAR16_T_LANGUAGE_SUPPORT", "1");
352     }
353   }
354 
355   if (LangOpts.Optimize)
356     Builder.defineMacro("__OPTIMIZE__");
357   if (LangOpts.OptimizeSize)
358     Builder.defineMacro("__OPTIMIZE_SIZE__");
359 
360   // Initialize target-specific preprocessor defines.
361 
362   // Define type sizing macros based on the target properties.
363   assert(TI.getCharWidth() == 8 && "Only support 8-bit char so far");
364   Builder.defineMacro("__CHAR_BIT__", "8");
365 
366   DefineTypeSize("__SCHAR_MAX__", TI.getCharWidth(), "", true, Builder);
367   DefineTypeSize("__SHRT_MAX__", TargetInfo::SignedShort, TI, Builder);
368   DefineTypeSize("__INT_MAX__", TargetInfo::SignedInt, TI, Builder);
369   DefineTypeSize("__LONG_MAX__", TargetInfo::SignedLong, TI, Builder);
370   DefineTypeSize("__LONG_LONG_MAX__", TargetInfo::SignedLongLong, TI, Builder);
371   DefineTypeSize("__WCHAR_MAX__", TI.getWCharType(), TI, Builder);
372   DefineTypeSize("__INTMAX_MAX__", TI.getIntMaxType(), TI, Builder);
373 
374   DefineTypeSizeof("__SIZEOF_DOUBLE__", TI.getDoubleWidth(), TI, Builder);
375   DefineTypeSizeof("__SIZEOF_FLOAT__", TI.getFloatWidth(), TI, Builder);
376   DefineTypeSizeof("__SIZEOF_INT__", TI.getIntWidth(), TI, Builder);
377   DefineTypeSizeof("__SIZEOF_LONG__", TI.getLongWidth(), TI, Builder);
378   DefineTypeSizeof("__SIZEOF_LONG_DOUBLE__",TI.getLongDoubleWidth(),TI,Builder);
379   DefineTypeSizeof("__SIZEOF_LONG_LONG__", TI.getLongLongWidth(), TI, Builder);
380   DefineTypeSizeof("__SIZEOF_POINTER__", TI.getPointerWidth(0), TI, Builder);
381   DefineTypeSizeof("__SIZEOF_SHORT__", TI.getShortWidth(), TI, Builder);
382   DefineTypeSizeof("__SIZEOF_PTRDIFF_T__",
383                    TI.getTypeWidth(TI.getPtrDiffType(0)), TI, Builder);
384   DefineTypeSizeof("__SIZEOF_SIZE_T__",
385                    TI.getTypeWidth(TI.getSizeType()), TI, Builder);
386   DefineTypeSizeof("__SIZEOF_WCHAR_T__",
387                    TI.getTypeWidth(TI.getWCharType()), TI, Builder);
388   DefineTypeSizeof("__SIZEOF_WINT_T__",
389                    TI.getTypeWidth(TI.getWIntType()), TI, Builder);
390 
391   DefineType("__INTMAX_TYPE__", TI.getIntMaxType(), Builder);
392   DefineType("__UINTMAX_TYPE__", TI.getUIntMaxType(), Builder);
393   DefineTypeWidth("__INTMAX_WIDTH__",  TI.getIntMaxType(), TI, Builder);
394   DefineType("__PTRDIFF_TYPE__", TI.getPtrDiffType(0), Builder);
395   DefineTypeWidth("__PTRDIFF_WIDTH__", TI.getPtrDiffType(0), TI, Builder);
396   DefineType("__INTPTR_TYPE__", TI.getIntPtrType(), Builder);
397   DefineTypeWidth("__INTPTR_WIDTH__", TI.getIntPtrType(), TI, Builder);
398   DefineType("__SIZE_TYPE__", TI.getSizeType(), Builder);
399   DefineTypeWidth("__SIZE_WIDTH__", TI.getSizeType(), TI, Builder);
400   DefineType("__WCHAR_TYPE__", TI.getWCharType(), Builder);
401   DefineTypeWidth("__WCHAR_WIDTH__", TI.getWCharType(), TI, Builder);
402   DefineType("__WINT_TYPE__", TI.getWIntType(), Builder);
403   DefineTypeWidth("__WINT_WIDTH__", TI.getWIntType(), TI, Builder);
404   DefineTypeWidth("__SIG_ATOMIC_WIDTH__", TI.getSigAtomicType(), TI, Builder);
405   DefineType("__CHAR16_TYPE__", TI.getChar16Type(), Builder);
406   DefineType("__CHAR32_TYPE__", TI.getChar32Type(), Builder);
407 
408   DefineFloatMacros(Builder, "FLT", &TI.getFloatFormat());
409   DefineFloatMacros(Builder, "DBL", &TI.getDoubleFormat());
410   DefineFloatMacros(Builder, "LDBL", &TI.getLongDoubleFormat());
411 
412   // Define a __POINTER_WIDTH__ macro for stdint.h.
413   Builder.defineMacro("__POINTER_WIDTH__",
414                       llvm::Twine((int)TI.getPointerWidth(0)));
415 
416   if (!LangOpts.CharIsSigned)
417     Builder.defineMacro("__CHAR_UNSIGNED__");
418 
419   if (!TargetInfo::isTypeSigned(TI.getWIntType()))
420     Builder.defineMacro("__WINT_UNSIGNED__");
421 
422   // Define exact-width integer types for stdint.h
423   Builder.defineMacro("__INT" + llvm::Twine(TI.getCharWidth()) + "_TYPE__",
424                       "char");
425 
426   if (TI.getShortWidth() > TI.getCharWidth())
427     DefineExactWidthIntType(TargetInfo::SignedShort, TI, Builder);
428 
429   if (TI.getIntWidth() > TI.getShortWidth())
430     DefineExactWidthIntType(TargetInfo::SignedInt, TI, Builder);
431 
432   if (TI.getLongWidth() > TI.getIntWidth())
433     DefineExactWidthIntType(TargetInfo::SignedLong, TI, Builder);
434 
435   if (TI.getLongLongWidth() > TI.getLongWidth())
436     DefineExactWidthIntType(TargetInfo::SignedLongLong, TI, Builder);
437 
438   // Add __builtin_va_list typedef.
439   Builder.append(TI.getVAListDeclaration());
440 
441   if (const char *Prefix = TI.getUserLabelPrefix())
442     Builder.defineMacro("__USER_LABEL_PREFIX__", Prefix);
443 
444   // Build configuration options.  FIXME: these should be controlled by
445   // command line options or something.
446   Builder.defineMacro("__FINITE_MATH_ONLY__", "0");
447 
448   if (LangOpts.GNUInline)
449     Builder.defineMacro("__GNUC_GNU_INLINE__");
450   else
451     Builder.defineMacro("__GNUC_STDC_INLINE__");
452 
453   if (LangOpts.NoInline)
454     Builder.defineMacro("__NO_INLINE__");
455 
456   if (unsigned PICLevel = LangOpts.PICLevel) {
457     Builder.defineMacro("__PIC__", llvm::Twine(PICLevel));
458     Builder.defineMacro("__pic__", llvm::Twine(PICLevel));
459   }
460 
461   // Macros to control C99 numerics and <float.h>
462   Builder.defineMacro("__FLT_EVAL_METHOD__", "0");
463   Builder.defineMacro("__FLT_RADIX__", "2");
464   int Dig = PickFP(&TI.getLongDoubleFormat(), -1/*FIXME*/, 17, 21, 33, 36);
465   Builder.defineMacro("__DECIMAL_DIG__", llvm::Twine(Dig));
466 
467   if (LangOpts.getStackProtectorMode() == LangOptions::SSPOn)
468     Builder.defineMacro("__SSP__");
469   else if (LangOpts.getStackProtectorMode() == LangOptions::SSPReq)
470     Builder.defineMacro("__SSP_ALL__", "2");
471 
472   if (FEOpts.ProgramAction == frontend::RewriteObjC)
473     Builder.defineMacro("__weak", "__attribute__((objc_gc(weak)))");
474 
475   // Define a macro that exists only when using the static analyzer.
476   if (FEOpts.ProgramAction == frontend::RunAnalysis)
477     Builder.defineMacro("__clang_analyzer__");
478 
479   if (LangOpts.FastRelaxedMath)
480     Builder.defineMacro("__FAST_RELAXED_MATH__");
481 
482   // Get other target #defines.
483   TI.getTargetDefines(LangOpts, Builder);
484 }
485 
486 // Initialize the remapping of files to alternative contents, e.g.,
487 // those specified through other files.
488 static void InitializeFileRemapping(Diagnostic &Diags,
489                                     SourceManager &SourceMgr,
490                                     FileManager &FileMgr,
491                                     const PreprocessorOptions &InitOpts) {
492   // Remap files in the source manager (with buffers).
493   for (PreprocessorOptions::const_remapped_file_buffer_iterator
494          Remap = InitOpts.remapped_file_buffer_begin(),
495          RemapEnd = InitOpts.remapped_file_buffer_end();
496        Remap != RemapEnd;
497        ++Remap) {
498     // Create the file entry for the file that we're mapping from.
499     const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
500                                                 Remap->second->getBufferSize(),
501                                                        0);
502     if (!FromFile) {
503       Diags.Report(diag::err_fe_remap_missing_from_file)
504         << Remap->first;
505       if (!InitOpts.RetainRemappedFileBuffers)
506         delete Remap->second;
507       continue;
508     }
509 
510     // Override the contents of the "from" file with the contents of
511     // the "to" file.
512     SourceMgr.overrideFileContents(FromFile, Remap->second,
513                                    InitOpts.RetainRemappedFileBuffers);
514   }
515 
516   // Remap files in the source manager (with other files).
517   for (PreprocessorOptions::const_remapped_file_iterator
518          Remap = InitOpts.remapped_file_begin(),
519          RemapEnd = InitOpts.remapped_file_end();
520        Remap != RemapEnd;
521        ++Remap) {
522     // Find the file that we're mapping to.
523     const FileEntry *ToFile = FileMgr.getFile(Remap->second);
524     if (!ToFile) {
525       Diags.Report(diag::err_fe_remap_missing_to_file)
526       << Remap->first << Remap->second;
527       continue;
528     }
529 
530     // Create the file entry for the file that we're mapping from.
531     const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
532                                                        ToFile->getSize(), 0);
533     if (!FromFile) {
534       Diags.Report(diag::err_fe_remap_missing_from_file)
535       << Remap->first;
536       continue;
537     }
538 
539     // Override the contents of the "from" file with the contents of
540     // the "to" file.
541     SourceMgr.overrideFileContents(FromFile, ToFile);
542   }
543 
544   SourceMgr.setOverridenFilesKeepOriginalName(
545                                         InitOpts.RemappedFilesKeepOriginalName);
546 }
547 
548 /// InitializePreprocessor - Initialize the preprocessor getting it and the
549 /// environment ready to process a single file. This returns true on error.
550 ///
551 void clang::InitializePreprocessor(Preprocessor &PP,
552                                    const PreprocessorOptions &InitOpts,
553                                    const HeaderSearchOptions &HSOpts,
554                                    const FrontendOptions &FEOpts) {
555   std::string PredefineBuffer;
556   PredefineBuffer.reserve(4080);
557   llvm::raw_string_ostream Predefines(PredefineBuffer);
558   MacroBuilder Builder(Predefines);
559 
560   InitializeFileRemapping(PP.getDiagnostics(), PP.getSourceManager(),
561                           PP.getFileManager(), InitOpts);
562 
563   // Emit line markers for various builtin sections of the file.  We don't do
564   // this in asm preprocessor mode, because "# 4" is not a line marker directive
565   // in this mode.
566   if (!PP.getLangOptions().AsmPreprocessor)
567     Builder.append("# 1 \"<built-in>\" 3");
568 
569   // Install things like __POWERPC__, __GNUC__, etc into the macro table.
570   if (InitOpts.UsePredefines)
571     InitializePredefinedMacros(PP.getTargetInfo(), PP.getLangOptions(),
572                                FEOpts, Builder);
573 
574   // Add on the predefines from the driver.  Wrap in a #line directive to report
575   // that they come from the command line.
576   if (!PP.getLangOptions().AsmPreprocessor)
577     Builder.append("# 1 \"<command line>\" 1");
578 
579   // Process #define's and #undef's in the order they are given.
580   for (unsigned i = 0, e = InitOpts.Macros.size(); i != e; ++i) {
581     if (InitOpts.Macros[i].second)  // isUndef
582       Builder.undefineMacro(InitOpts.Macros[i].first);
583     else
584       DefineBuiltinMacro(Builder, InitOpts.Macros[i].first,
585                          PP.getDiagnostics());
586   }
587 
588   // If -imacros are specified, include them now.  These are processed before
589   // any -include directives.
590   for (unsigned i = 0, e = InitOpts.MacroIncludes.size(); i != e; ++i)
591     AddImplicitIncludeMacros(Builder, InitOpts.MacroIncludes[i],
592                              PP.getFileManager());
593 
594   // Process -include directives.
595   for (unsigned i = 0, e = InitOpts.Includes.size(); i != e; ++i) {
596     const std::string &Path = InitOpts.Includes[i];
597     if (Path == InitOpts.ImplicitPTHInclude)
598       AddImplicitIncludePTH(Builder, PP, Path);
599     else
600       AddImplicitInclude(Builder, Path, PP.getFileManager());
601   }
602 
603   // Exit the command line and go back to <built-in> (2 is LC_LEAVE).
604   if (!PP.getLangOptions().AsmPreprocessor)
605     Builder.append("# 1 \"<built-in>\" 2");
606 
607   // Instruct the preprocessor to skip the preamble.
608   PP.setSkipMainFilePreamble(InitOpts.PrecompiledPreambleBytes.first,
609                              InitOpts.PrecompiledPreambleBytes.second);
610 
611   // Copy PredefinedBuffer into the Preprocessor.
612   PP.setPredefines(Predefines.str());
613 
614   // Initialize the header search object.
615   ApplyHeaderSearchOptions(PP.getHeaderSearchInfo(), HSOpts,
616                            PP.getLangOptions(),
617                            PP.getTargetInfo().getTriple());
618 }
619