1 //===--- SemaAttr.cpp - Semantic Analysis for Attributes ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements semantic analysis for non-trivial attributes and
10 // pragmas.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/AST/ASTConsumer.h"
15 #include "clang/AST/Attr.h"
16 #include "clang/AST/Expr.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Lex/Preprocessor.h"
19 #include "clang/Sema/Lookup.h"
20 #include "clang/Sema/SemaInternal.h"
21 using namespace clang;
22 
23 //===----------------------------------------------------------------------===//
24 // Pragma 'pack' and 'options align'
25 //===----------------------------------------------------------------------===//
26 
27 Sema::PragmaStackSentinelRAII::PragmaStackSentinelRAII(Sema &S,
28                                                        StringRef SlotLabel,
29                                                        bool ShouldAct)
30     : S(S), SlotLabel(SlotLabel), ShouldAct(ShouldAct) {
31   if (ShouldAct) {
32     S.VtorDispStack.SentinelAction(PSK_Push, SlotLabel);
33     S.DataSegStack.SentinelAction(PSK_Push, SlotLabel);
34     S.BSSSegStack.SentinelAction(PSK_Push, SlotLabel);
35     S.ConstSegStack.SentinelAction(PSK_Push, SlotLabel);
36     S.CodeSegStack.SentinelAction(PSK_Push, SlotLabel);
37   }
38 }
39 
40 Sema::PragmaStackSentinelRAII::~PragmaStackSentinelRAII() {
41   if (ShouldAct) {
42     S.VtorDispStack.SentinelAction(PSK_Pop, SlotLabel);
43     S.DataSegStack.SentinelAction(PSK_Pop, SlotLabel);
44     S.BSSSegStack.SentinelAction(PSK_Pop, SlotLabel);
45     S.ConstSegStack.SentinelAction(PSK_Pop, SlotLabel);
46     S.CodeSegStack.SentinelAction(PSK_Pop, SlotLabel);
47   }
48 }
49 
50 void Sema::AddAlignmentAttributesForRecord(RecordDecl *RD) {
51   AlignPackInfo InfoVal = AlignPackStack.CurrentValue;
52   AlignPackInfo::Mode M = InfoVal.getAlignMode();
53   bool IsPackSet = InfoVal.IsPackSet();
54   bool IsXLPragma = getLangOpts().XLPragmaPack;
55 
56   // If we are not under mac68k/natural alignment mode and also there is no pack
57   // value, we don't need any attributes.
58   if (!IsPackSet && M != AlignPackInfo::Mac68k && M != AlignPackInfo::Natural)
59     return;
60 
61   if (M == AlignPackInfo::Mac68k && (IsXLPragma || InfoVal.IsAlignAttr())) {
62     RD->addAttr(AlignMac68kAttr::CreateImplicit(Context));
63   } else if (IsPackSet) {
64     // Check to see if we need a max field alignment attribute.
65     RD->addAttr(MaxFieldAlignmentAttr::CreateImplicit(
66         Context, InfoVal.getPackNumber() * 8));
67   }
68 
69   if (IsXLPragma && M == AlignPackInfo::Natural)
70     RD->addAttr(AlignNaturalAttr::CreateImplicit(Context));
71 
72   if (AlignPackIncludeStack.empty())
73     return;
74   // The #pragma align/pack affected a record in an included file, so Clang
75   // should warn when that pragma was written in a file that included the
76   // included file.
77   for (auto &AlignPackedInclude : llvm::reverse(AlignPackIncludeStack)) {
78     if (AlignPackedInclude.CurrentPragmaLocation !=
79         AlignPackStack.CurrentPragmaLocation)
80       break;
81     if (AlignPackedInclude.HasNonDefaultValue)
82       AlignPackedInclude.ShouldWarnOnInclude = true;
83   }
84 }
85 
86 void Sema::AddMsStructLayoutForRecord(RecordDecl *RD) {
87   if (MSStructPragmaOn)
88     RD->addAttr(MSStructAttr::CreateImplicit(Context));
89 
90   // FIXME: We should merge AddAlignmentAttributesForRecord with
91   // AddMsStructLayoutForRecord into AddPragmaAttributesForRecord, which takes
92   // all active pragmas and applies them as attributes to class definitions.
93   if (VtorDispStack.CurrentValue != getLangOpts().getVtorDispMode())
94     RD->addAttr(MSVtorDispAttr::CreateImplicit(
95         Context, unsigned(VtorDispStack.CurrentValue)));
96 }
97 
98 template <typename Attribute>
99 static void addGslOwnerPointerAttributeIfNotExisting(ASTContext &Context,
100                                                      CXXRecordDecl *Record) {
101   if (Record->hasAttr<OwnerAttr>() || Record->hasAttr<PointerAttr>())
102     return;
103 
104   for (Decl *Redecl : Record->redecls())
105     Redecl->addAttr(Attribute::CreateImplicit(Context, /*DerefType=*/nullptr));
106 }
107 
108 void Sema::inferGslPointerAttribute(NamedDecl *ND,
109                                     CXXRecordDecl *UnderlyingRecord) {
110   if (!UnderlyingRecord)
111     return;
112 
113   const auto *Parent = dyn_cast<CXXRecordDecl>(ND->getDeclContext());
114   if (!Parent)
115     return;
116 
117   static llvm::StringSet<> Containers{
118       "array",
119       "basic_string",
120       "deque",
121       "forward_list",
122       "vector",
123       "list",
124       "map",
125       "multiset",
126       "multimap",
127       "priority_queue",
128       "queue",
129       "set",
130       "stack",
131       "unordered_set",
132       "unordered_map",
133       "unordered_multiset",
134       "unordered_multimap",
135   };
136 
137   static llvm::StringSet<> Iterators{"iterator", "const_iterator",
138                                      "reverse_iterator",
139                                      "const_reverse_iterator"};
140 
141   if (Parent->isInStdNamespace() && Iterators.count(ND->getName()) &&
142       Containers.count(Parent->getName()))
143     addGslOwnerPointerAttributeIfNotExisting<PointerAttr>(Context,
144                                                           UnderlyingRecord);
145 }
146 
147 void Sema::inferGslPointerAttribute(TypedefNameDecl *TD) {
148 
149   QualType Canonical = TD->getUnderlyingType().getCanonicalType();
150 
151   CXXRecordDecl *RD = Canonical->getAsCXXRecordDecl();
152   if (!RD) {
153     if (auto *TST =
154             dyn_cast<TemplateSpecializationType>(Canonical.getTypePtr())) {
155 
156       RD = dyn_cast_or_null<CXXRecordDecl>(
157           TST->getTemplateName().getAsTemplateDecl()->getTemplatedDecl());
158     }
159   }
160 
161   inferGslPointerAttribute(TD, RD);
162 }
163 
164 void Sema::inferGslOwnerPointerAttribute(CXXRecordDecl *Record) {
165   static llvm::StringSet<> StdOwners{
166       "any",
167       "array",
168       "basic_regex",
169       "basic_string",
170       "deque",
171       "forward_list",
172       "vector",
173       "list",
174       "map",
175       "multiset",
176       "multimap",
177       "optional",
178       "priority_queue",
179       "queue",
180       "set",
181       "stack",
182       "unique_ptr",
183       "unordered_set",
184       "unordered_map",
185       "unordered_multiset",
186       "unordered_multimap",
187       "variant",
188   };
189   static llvm::StringSet<> StdPointers{
190       "basic_string_view",
191       "reference_wrapper",
192       "regex_iterator",
193   };
194 
195   if (!Record->getIdentifier())
196     return;
197 
198   // Handle classes that directly appear in std namespace.
199   if (Record->isInStdNamespace()) {
200     if (Record->hasAttr<OwnerAttr>() || Record->hasAttr<PointerAttr>())
201       return;
202 
203     if (StdOwners.count(Record->getName()))
204       addGslOwnerPointerAttributeIfNotExisting<OwnerAttr>(Context, Record);
205     else if (StdPointers.count(Record->getName()))
206       addGslOwnerPointerAttributeIfNotExisting<PointerAttr>(Context, Record);
207 
208     return;
209   }
210 
211   // Handle nested classes that could be a gsl::Pointer.
212   inferGslPointerAttribute(Record, Record);
213 }
214 
215 void Sema::ActOnPragmaOptionsAlign(PragmaOptionsAlignKind Kind,
216                                    SourceLocation PragmaLoc) {
217   PragmaMsStackAction Action = Sema::PSK_Reset;
218   AlignPackInfo::Mode ModeVal = AlignPackInfo::Native;
219 
220   switch (Kind) {
221     // For most of the platforms we support, native and natural are the same.
222     // With XL, native is the same as power, natural means something else.
223     //
224     // FIXME: This is not true on Darwin/PPC.
225   case POAK_Native:
226   case POAK_Power:
227     Action = Sema::PSK_Push_Set;
228     break;
229   case POAK_Natural:
230     Action = Sema::PSK_Push_Set;
231     ModeVal = AlignPackInfo::Natural;
232     break;
233 
234     // Note that '#pragma options align=packed' is not equivalent to attribute
235     // packed, it has a different precedence relative to attribute aligned.
236   case POAK_Packed:
237     Action = Sema::PSK_Push_Set;
238     ModeVal = AlignPackInfo::Packed;
239     break;
240 
241   case POAK_Mac68k:
242     // Check if the target supports this.
243     if (!this->Context.getTargetInfo().hasAlignMac68kSupport()) {
244       Diag(PragmaLoc, diag::err_pragma_options_align_mac68k_target_unsupported);
245       return;
246     }
247     Action = Sema::PSK_Push_Set;
248     ModeVal = AlignPackInfo::Mac68k;
249     break;
250   case POAK_Reset:
251     // Reset just pops the top of the stack, or resets the current alignment to
252     // default.
253     Action = Sema::PSK_Pop;
254     if (AlignPackStack.Stack.empty()) {
255       if (AlignPackStack.CurrentValue.getAlignMode() != AlignPackInfo::Native ||
256           AlignPackStack.CurrentValue.IsPackAttr()) {
257         Action = Sema::PSK_Reset;
258       } else {
259         Diag(PragmaLoc, diag::warn_pragma_options_align_reset_failed)
260             << "stack empty";
261         return;
262       }
263     }
264     break;
265   }
266 
267   AlignPackInfo Info(ModeVal, getLangOpts().XLPragmaPack);
268 
269   AlignPackStack.Act(PragmaLoc, Action, StringRef(), Info);
270 }
271 
272 void Sema::ActOnPragmaClangSection(SourceLocation PragmaLoc,
273                                    PragmaClangSectionAction Action,
274                                    PragmaClangSectionKind SecKind,
275                                    StringRef SecName) {
276   PragmaClangSection *CSec;
277   int SectionFlags = ASTContext::PSF_Read;
278   switch (SecKind) {
279     case PragmaClangSectionKind::PCSK_BSS:
280       CSec = &PragmaClangBSSSection;
281       SectionFlags |= ASTContext::PSF_Write | ASTContext::PSF_ZeroInit;
282       break;
283     case PragmaClangSectionKind::PCSK_Data:
284       CSec = &PragmaClangDataSection;
285       SectionFlags |= ASTContext::PSF_Write;
286       break;
287     case PragmaClangSectionKind::PCSK_Rodata:
288       CSec = &PragmaClangRodataSection;
289       break;
290     case PragmaClangSectionKind::PCSK_Relro:
291       CSec = &PragmaClangRelroSection;
292       break;
293     case PragmaClangSectionKind::PCSK_Text:
294       CSec = &PragmaClangTextSection;
295       SectionFlags |= ASTContext::PSF_Execute;
296       break;
297     default:
298       llvm_unreachable("invalid clang section kind");
299   }
300 
301   if (Action == PragmaClangSectionAction::PCSA_Clear) {
302     CSec->Valid = false;
303     return;
304   }
305 
306   if (llvm::Error E = isValidSectionSpecifier(SecName)) {
307     Diag(PragmaLoc, diag::err_pragma_section_invalid_for_target)
308         << toString(std::move(E));
309     CSec->Valid = false;
310     return;
311   }
312 
313   if (UnifySection(SecName, SectionFlags, PragmaLoc))
314     return;
315 
316   CSec->Valid = true;
317   CSec->SectionName = std::string(SecName);
318   CSec->PragmaLocation = PragmaLoc;
319 }
320 
321 void Sema::ActOnPragmaPack(SourceLocation PragmaLoc, PragmaMsStackAction Action,
322                            StringRef SlotLabel, Expr *alignment) {
323   bool IsXLPragma = getLangOpts().XLPragmaPack;
324   // XL pragma pack does not support identifier syntax.
325   if (IsXLPragma && !SlotLabel.empty()) {
326     Diag(PragmaLoc, diag::err_pragma_pack_identifer_not_supported);
327     return;
328   }
329 
330   const AlignPackInfo CurVal = AlignPackStack.CurrentValue;
331   Expr *Alignment = static_cast<Expr *>(alignment);
332 
333   // If specified then alignment must be a "small" power of two.
334   unsigned AlignmentVal = 0;
335   AlignPackInfo::Mode ModeVal = CurVal.getAlignMode();
336 
337   if (Alignment) {
338     Optional<llvm::APSInt> Val;
339     Val = Alignment->getIntegerConstantExpr(Context);
340 
341     // pack(0) is like pack(), which just works out since that is what
342     // we use 0 for in PackAttr.
343     if (Alignment->isTypeDependent() || !Val ||
344         !(*Val == 0 || Val->isPowerOf2()) || Val->getZExtValue() > 16) {
345       Diag(PragmaLoc, diag::warn_pragma_pack_invalid_alignment);
346       return; // Ignore
347     }
348 
349     if (IsXLPragma && *Val == 0) {
350       // pack(0) does not work out with XL.
351       Diag(PragmaLoc, diag::err_pragma_pack_invalid_alignment);
352       return; // Ignore
353     }
354 
355     AlignmentVal = (unsigned)Val->getZExtValue();
356   }
357 
358   if (Action == Sema::PSK_Show) {
359     // Show the current alignment, making sure to show the right value
360     // for the default.
361     // FIXME: This should come from the target.
362     AlignmentVal = CurVal.IsPackSet() ? CurVal.getPackNumber() : 8;
363     if (ModeVal == AlignPackInfo::Mac68k &&
364         (IsXLPragma || CurVal.IsAlignAttr()))
365       Diag(PragmaLoc, diag::warn_pragma_pack_show) << "mac68k";
366     else
367       Diag(PragmaLoc, diag::warn_pragma_pack_show) << AlignmentVal;
368   }
369 
370   // MSDN, C/C++ Preprocessor Reference > Pragma Directives > pack:
371   // "#pragma pack(pop, identifier, n) is undefined"
372   if (Action & Sema::PSK_Pop) {
373     if (Alignment && !SlotLabel.empty())
374       Diag(PragmaLoc, diag::warn_pragma_pack_pop_identifier_and_alignment);
375     if (AlignPackStack.Stack.empty()) {
376       assert(CurVal.getAlignMode() == AlignPackInfo::Native &&
377              "Empty pack stack can only be at Native alignment mode.");
378       Diag(PragmaLoc, diag::warn_pragma_pop_failed) << "pack" << "stack empty";
379     }
380   }
381 
382   AlignPackInfo Info(ModeVal, AlignmentVal, IsXLPragma);
383 
384   AlignPackStack.Act(PragmaLoc, Action, SlotLabel, Info);
385 }
386 
387 void Sema::DiagnoseNonDefaultPragmaAlignPack(PragmaAlignPackDiagnoseKind Kind,
388                                              SourceLocation IncludeLoc) {
389   if (Kind == PragmaAlignPackDiagnoseKind::NonDefaultStateAtInclude) {
390     SourceLocation PrevLocation = AlignPackStack.CurrentPragmaLocation;
391     // Warn about non-default alignment at #includes (without redundant
392     // warnings for the same directive in nested includes).
393     // The warning is delayed until the end of the file to avoid warnings
394     // for files that don't have any records that are affected by the modified
395     // alignment.
396     bool HasNonDefaultValue =
397         AlignPackStack.hasValue() &&
398         (AlignPackIncludeStack.empty() ||
399          AlignPackIncludeStack.back().CurrentPragmaLocation != PrevLocation);
400     AlignPackIncludeStack.push_back(
401         {AlignPackStack.CurrentValue,
402          AlignPackStack.hasValue() ? PrevLocation : SourceLocation(),
403          HasNonDefaultValue, /*ShouldWarnOnInclude*/ false});
404     return;
405   }
406 
407   assert(Kind == PragmaAlignPackDiagnoseKind::ChangedStateAtExit &&
408          "invalid kind");
409   AlignPackIncludeState PrevAlignPackState =
410       AlignPackIncludeStack.pop_back_val();
411   // FIXME: AlignPackStack may contain both #pragma align and #pragma pack
412   // information, diagnostics below might not be accurate if we have mixed
413   // pragmas.
414   if (PrevAlignPackState.ShouldWarnOnInclude) {
415     // Emit the delayed non-default alignment at #include warning.
416     Diag(IncludeLoc, diag::warn_pragma_pack_non_default_at_include);
417     Diag(PrevAlignPackState.CurrentPragmaLocation, diag::note_pragma_pack_here);
418   }
419   // Warn about modified alignment after #includes.
420   if (PrevAlignPackState.CurrentValue != AlignPackStack.CurrentValue) {
421     Diag(IncludeLoc, diag::warn_pragma_pack_modified_after_include);
422     Diag(AlignPackStack.CurrentPragmaLocation, diag::note_pragma_pack_here);
423   }
424 }
425 
426 void Sema::DiagnoseUnterminatedPragmaAlignPack() {
427   if (AlignPackStack.Stack.empty())
428     return;
429   bool IsInnermost = true;
430 
431   // FIXME: AlignPackStack may contain both #pragma align and #pragma pack
432   // information, diagnostics below might not be accurate if we have mixed
433   // pragmas.
434   for (const auto &StackSlot : llvm::reverse(AlignPackStack.Stack)) {
435     Diag(StackSlot.PragmaPushLocation, diag::warn_pragma_pack_no_pop_eof);
436     // The user might have already reset the alignment, so suggest replacing
437     // the reset with a pop.
438     if (IsInnermost &&
439         AlignPackStack.CurrentValue == AlignPackStack.DefaultValue) {
440       auto DB = Diag(AlignPackStack.CurrentPragmaLocation,
441                      diag::note_pragma_pack_pop_instead_reset);
442       SourceLocation FixItLoc =
443           Lexer::findLocationAfterToken(AlignPackStack.CurrentPragmaLocation,
444                                         tok::l_paren, SourceMgr, LangOpts,
445                                         /*SkipTrailing=*/false);
446       if (FixItLoc.isValid())
447         DB << FixItHint::CreateInsertion(FixItLoc, "pop");
448     }
449     IsInnermost = false;
450   }
451 }
452 
453 void Sema::ActOnPragmaMSStruct(PragmaMSStructKind Kind) {
454   MSStructPragmaOn = (Kind == PMSST_ON);
455 }
456 
457 void Sema::ActOnPragmaMSComment(SourceLocation CommentLoc,
458                                 PragmaMSCommentKind Kind, StringRef Arg) {
459   auto *PCD = PragmaCommentDecl::Create(
460       Context, Context.getTranslationUnitDecl(), CommentLoc, Kind, Arg);
461   Context.getTranslationUnitDecl()->addDecl(PCD);
462   Consumer.HandleTopLevelDecl(DeclGroupRef(PCD));
463 }
464 
465 void Sema::ActOnPragmaDetectMismatch(SourceLocation Loc, StringRef Name,
466                                      StringRef Value) {
467   auto *PDMD = PragmaDetectMismatchDecl::Create(
468       Context, Context.getTranslationUnitDecl(), Loc, Name, Value);
469   Context.getTranslationUnitDecl()->addDecl(PDMD);
470   Consumer.HandleTopLevelDecl(DeclGroupRef(PDMD));
471 }
472 
473 void Sema::ActOnPragmaFPEvalMethod(SourceLocation Loc,
474                                    LangOptions::FPEvalMethodKind Value) {
475   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
476   switch (Value) {
477   default:
478     llvm_unreachable("invalid pragma eval_method kind");
479   case LangOptions::FEM_Source:
480     NewFPFeatures.setFPEvalMethodOverride(LangOptions::FEM_Source);
481     break;
482   case LangOptions::FEM_Double:
483     NewFPFeatures.setFPEvalMethodOverride(LangOptions::FEM_Double);
484     break;
485   case LangOptions::FEM_Extended:
486     NewFPFeatures.setFPEvalMethodOverride(LangOptions::FEM_Extended);
487     break;
488   }
489   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
490   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
491   PP.setCurrentFPEvalMethod(Loc, Value);
492 }
493 
494 void Sema::ActOnPragmaFloatControl(SourceLocation Loc,
495                                    PragmaMsStackAction Action,
496                                    PragmaFloatControlKind Value) {
497   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
498   if ((Action == PSK_Push_Set || Action == PSK_Push || Action == PSK_Pop) &&
499       !CurContext->getRedeclContext()->isFileContext()) {
500     // Push and pop can only occur at file or namespace scope, or within a
501     // language linkage declaration.
502     Diag(Loc, diag::err_pragma_fc_pp_scope);
503     return;
504   }
505   switch (Value) {
506   default:
507     llvm_unreachable("invalid pragma float_control kind");
508   case PFC_Precise:
509     NewFPFeatures.setFPPreciseEnabled(true);
510     FpPragmaStack.Act(Loc, Action, StringRef(), NewFPFeatures);
511     break;
512   case PFC_NoPrecise:
513     if (CurFPFeatures.getFPExceptionMode() == LangOptions::FPE_Strict)
514       Diag(Loc, diag::err_pragma_fc_noprecise_requires_noexcept);
515     else if (CurFPFeatures.getAllowFEnvAccess())
516       Diag(Loc, diag::err_pragma_fc_noprecise_requires_nofenv);
517     else
518       NewFPFeatures.setFPPreciseEnabled(false);
519     FpPragmaStack.Act(Loc, Action, StringRef(), NewFPFeatures);
520     break;
521   case PFC_Except:
522     if (!isPreciseFPEnabled())
523       Diag(Loc, diag::err_pragma_fc_except_requires_precise);
524     else
525       NewFPFeatures.setFPExceptionModeOverride(LangOptions::FPE_Strict);
526     FpPragmaStack.Act(Loc, Action, StringRef(), NewFPFeatures);
527     break;
528   case PFC_NoExcept:
529     NewFPFeatures.setFPExceptionModeOverride(LangOptions::FPE_Ignore);
530     FpPragmaStack.Act(Loc, Action, StringRef(), NewFPFeatures);
531     break;
532   case PFC_Push:
533     FpPragmaStack.Act(Loc, Sema::PSK_Push_Set, StringRef(), NewFPFeatures);
534     break;
535   case PFC_Pop:
536     if (FpPragmaStack.Stack.empty()) {
537       Diag(Loc, diag::warn_pragma_pop_failed) << "float_control"
538                                               << "stack empty";
539       return;
540     }
541     FpPragmaStack.Act(Loc, Action, StringRef(), NewFPFeatures);
542     NewFPFeatures = FpPragmaStack.CurrentValue;
543     break;
544   }
545   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
546 }
547 
548 void Sema::ActOnPragmaMSPointersToMembers(
549     LangOptions::PragmaMSPointersToMembersKind RepresentationMethod,
550     SourceLocation PragmaLoc) {
551   MSPointerToMemberRepresentationMethod = RepresentationMethod;
552   ImplicitMSInheritanceAttrLoc = PragmaLoc;
553 }
554 
555 void Sema::ActOnPragmaMSVtorDisp(PragmaMsStackAction Action,
556                                  SourceLocation PragmaLoc,
557                                  MSVtorDispMode Mode) {
558   if (Action & PSK_Pop && VtorDispStack.Stack.empty())
559     Diag(PragmaLoc, diag::warn_pragma_pop_failed) << "vtordisp"
560                                                   << "stack empty";
561   VtorDispStack.Act(PragmaLoc, Action, StringRef(), Mode);
562 }
563 
564 template <>
565 void Sema::PragmaStack<Sema::AlignPackInfo>::Act(SourceLocation PragmaLocation,
566                                                  PragmaMsStackAction Action,
567                                                  llvm::StringRef StackSlotLabel,
568                                                  AlignPackInfo Value) {
569   if (Action == PSK_Reset) {
570     CurrentValue = DefaultValue;
571     CurrentPragmaLocation = PragmaLocation;
572     return;
573   }
574   if (Action & PSK_Push)
575     Stack.emplace_back(Slot(StackSlotLabel, CurrentValue, CurrentPragmaLocation,
576                             PragmaLocation));
577   else if (Action & PSK_Pop) {
578     if (!StackSlotLabel.empty()) {
579       // If we've got a label, try to find it and jump there.
580       auto I = llvm::find_if(llvm::reverse(Stack), [&](const Slot &x) {
581         return x.StackSlotLabel == StackSlotLabel;
582       });
583       // We found the label, so pop from there.
584       if (I != Stack.rend()) {
585         CurrentValue = I->Value;
586         CurrentPragmaLocation = I->PragmaLocation;
587         Stack.erase(std::prev(I.base()), Stack.end());
588       }
589     } else if (Value.IsXLStack() && Value.IsAlignAttr() &&
590                CurrentValue.IsPackAttr()) {
591       // XL '#pragma align(reset)' would pop the stack until
592       // a current in effect pragma align is popped.
593       auto I = llvm::find_if(llvm::reverse(Stack), [&](const Slot &x) {
594         return x.Value.IsAlignAttr();
595       });
596       // If we found pragma align so pop from there.
597       if (I != Stack.rend()) {
598         Stack.erase(std::prev(I.base()), Stack.end());
599         if (Stack.empty()) {
600           CurrentValue = DefaultValue;
601           CurrentPragmaLocation = PragmaLocation;
602         } else {
603           CurrentValue = Stack.back().Value;
604           CurrentPragmaLocation = Stack.back().PragmaLocation;
605           Stack.pop_back();
606         }
607       }
608     } else if (!Stack.empty()) {
609       // xl '#pragma align' sets the baseline, and `#pragma pack` cannot pop
610       // over the baseline.
611       if (Value.IsXLStack() && Value.IsPackAttr() && CurrentValue.IsAlignAttr())
612         return;
613 
614       // We don't have a label, just pop the last entry.
615       CurrentValue = Stack.back().Value;
616       CurrentPragmaLocation = Stack.back().PragmaLocation;
617       Stack.pop_back();
618     }
619   }
620   if (Action & PSK_Set) {
621     CurrentValue = Value;
622     CurrentPragmaLocation = PragmaLocation;
623   }
624 }
625 
626 bool Sema::UnifySection(StringRef SectionName, int SectionFlags,
627                         NamedDecl *Decl) {
628   SourceLocation PragmaLocation;
629   if (auto A = Decl->getAttr<SectionAttr>())
630     if (A->isImplicit())
631       PragmaLocation = A->getLocation();
632   auto SectionIt = Context.SectionInfos.find(SectionName);
633   if (SectionIt == Context.SectionInfos.end()) {
634     Context.SectionInfos[SectionName] =
635         ASTContext::SectionInfo(Decl, PragmaLocation, SectionFlags);
636     return false;
637   }
638   // A pre-declared section takes precedence w/o diagnostic.
639   const auto &Section = SectionIt->second;
640   if (Section.SectionFlags == SectionFlags ||
641       ((SectionFlags & ASTContext::PSF_Implicit) &&
642        !(Section.SectionFlags & ASTContext::PSF_Implicit)))
643     return false;
644   Diag(Decl->getLocation(), diag::err_section_conflict) << Decl << Section;
645   if (Section.Decl)
646     Diag(Section.Decl->getLocation(), diag::note_declared_at)
647         << Section.Decl->getName();
648   if (PragmaLocation.isValid())
649     Diag(PragmaLocation, diag::note_pragma_entered_here);
650   if (Section.PragmaSectionLocation.isValid())
651     Diag(Section.PragmaSectionLocation, diag::note_pragma_entered_here);
652   return true;
653 }
654 
655 bool Sema::UnifySection(StringRef SectionName,
656                         int SectionFlags,
657                         SourceLocation PragmaSectionLocation) {
658   auto SectionIt = Context.SectionInfos.find(SectionName);
659   if (SectionIt != Context.SectionInfos.end()) {
660     const auto &Section = SectionIt->second;
661     if (Section.SectionFlags == SectionFlags)
662       return false;
663     if (!(Section.SectionFlags & ASTContext::PSF_Implicit)) {
664       Diag(PragmaSectionLocation, diag::err_section_conflict)
665           << "this" << Section;
666       if (Section.Decl)
667         Diag(Section.Decl->getLocation(), diag::note_declared_at)
668             << Section.Decl->getName();
669       if (Section.PragmaSectionLocation.isValid())
670         Diag(Section.PragmaSectionLocation, diag::note_pragma_entered_here);
671       return true;
672     }
673   }
674   Context.SectionInfos[SectionName] =
675       ASTContext::SectionInfo(nullptr, PragmaSectionLocation, SectionFlags);
676   return false;
677 }
678 
679 /// Called on well formed \#pragma bss_seg().
680 void Sema::ActOnPragmaMSSeg(SourceLocation PragmaLocation,
681                             PragmaMsStackAction Action,
682                             llvm::StringRef StackSlotLabel,
683                             StringLiteral *SegmentName,
684                             llvm::StringRef PragmaName) {
685   PragmaStack<StringLiteral *> *Stack =
686     llvm::StringSwitch<PragmaStack<StringLiteral *> *>(PragmaName)
687         .Case("data_seg", &DataSegStack)
688         .Case("bss_seg", &BSSSegStack)
689         .Case("const_seg", &ConstSegStack)
690         .Case("code_seg", &CodeSegStack);
691   if (Action & PSK_Pop && Stack->Stack.empty())
692     Diag(PragmaLocation, diag::warn_pragma_pop_failed) << PragmaName
693         << "stack empty";
694   if (SegmentName) {
695     if (!checkSectionName(SegmentName->getBeginLoc(), SegmentName->getString()))
696       return;
697 
698     if (SegmentName->getString() == ".drectve" &&
699         Context.getTargetInfo().getCXXABI().isMicrosoft())
700       Diag(PragmaLocation, diag::warn_attribute_section_drectve) << PragmaName;
701   }
702 
703   Stack->Act(PragmaLocation, Action, StackSlotLabel, SegmentName);
704 }
705 
706 /// Called on well formed \#pragma bss_seg().
707 void Sema::ActOnPragmaMSSection(SourceLocation PragmaLocation,
708                                 int SectionFlags, StringLiteral *SegmentName) {
709   UnifySection(SegmentName->getString(), SectionFlags, PragmaLocation);
710 }
711 
712 void Sema::ActOnPragmaMSInitSeg(SourceLocation PragmaLocation,
713                                 StringLiteral *SegmentName) {
714   // There's no stack to maintain, so we just have a current section.  When we
715   // see the default section, reset our current section back to null so we stop
716   // tacking on unnecessary attributes.
717   CurInitSeg = SegmentName->getString() == ".CRT$XCU" ? nullptr : SegmentName;
718   CurInitSegLoc = PragmaLocation;
719 }
720 
721 void Sema::ActOnPragmaUnused(const Token &IdTok, Scope *curScope,
722                              SourceLocation PragmaLoc) {
723 
724   IdentifierInfo *Name = IdTok.getIdentifierInfo();
725   LookupResult Lookup(*this, Name, IdTok.getLocation(), LookupOrdinaryName);
726   LookupParsedName(Lookup, curScope, nullptr, true);
727 
728   if (Lookup.empty()) {
729     Diag(PragmaLoc, diag::warn_pragma_unused_undeclared_var)
730       << Name << SourceRange(IdTok.getLocation());
731     return;
732   }
733 
734   VarDecl *VD = Lookup.getAsSingle<VarDecl>();
735   if (!VD) {
736     Diag(PragmaLoc, diag::warn_pragma_unused_expected_var_arg)
737       << Name << SourceRange(IdTok.getLocation());
738     return;
739   }
740 
741   // Warn if this was used before being marked unused.
742   if (VD->isUsed())
743     Diag(PragmaLoc, diag::warn_used_but_marked_unused) << Name;
744 
745   VD->addAttr(UnusedAttr::CreateImplicit(Context, IdTok.getLocation(),
746                                          AttributeCommonInfo::AS_Pragma,
747                                          UnusedAttr::GNU_unused));
748 }
749 
750 void Sema::AddCFAuditedAttribute(Decl *D) {
751   IdentifierInfo *Ident;
752   SourceLocation Loc;
753   std::tie(Ident, Loc) = PP.getPragmaARCCFCodeAuditedInfo();
754   if (!Loc.isValid()) return;
755 
756   // Don't add a redundant or conflicting attribute.
757   if (D->hasAttr<CFAuditedTransferAttr>() ||
758       D->hasAttr<CFUnknownTransferAttr>())
759     return;
760 
761   AttributeCommonInfo Info(Ident, SourceRange(Loc),
762                            AttributeCommonInfo::AS_Pragma);
763   D->addAttr(CFAuditedTransferAttr::CreateImplicit(Context, Info));
764 }
765 
766 namespace {
767 
768 Optional<attr::SubjectMatchRule>
769 getParentAttrMatcherRule(attr::SubjectMatchRule Rule) {
770   using namespace attr;
771   switch (Rule) {
772   default:
773     return None;
774 #define ATTR_MATCH_RULE(Value, Spelling, IsAbstract)
775 #define ATTR_MATCH_SUB_RULE(Value, Spelling, IsAbstract, Parent, IsNegated)    \
776   case Value:                                                                  \
777     return Parent;
778 #include "clang/Basic/AttrSubMatchRulesList.inc"
779   }
780 }
781 
782 bool isNegatedAttrMatcherSubRule(attr::SubjectMatchRule Rule) {
783   using namespace attr;
784   switch (Rule) {
785   default:
786     return false;
787 #define ATTR_MATCH_RULE(Value, Spelling, IsAbstract)
788 #define ATTR_MATCH_SUB_RULE(Value, Spelling, IsAbstract, Parent, IsNegated)    \
789   case Value:                                                                  \
790     return IsNegated;
791 #include "clang/Basic/AttrSubMatchRulesList.inc"
792   }
793 }
794 
795 CharSourceRange replacementRangeForListElement(const Sema &S,
796                                                SourceRange Range) {
797   // Make sure that the ',' is removed as well.
798   SourceLocation AfterCommaLoc = Lexer::findLocationAfterToken(
799       Range.getEnd(), tok::comma, S.getSourceManager(), S.getLangOpts(),
800       /*SkipTrailingWhitespaceAndNewLine=*/false);
801   if (AfterCommaLoc.isValid())
802     return CharSourceRange::getCharRange(Range.getBegin(), AfterCommaLoc);
803   else
804     return CharSourceRange::getTokenRange(Range);
805 }
806 
807 std::string
808 attrMatcherRuleListToString(ArrayRef<attr::SubjectMatchRule> Rules) {
809   std::string Result;
810   llvm::raw_string_ostream OS(Result);
811   for (const auto &I : llvm::enumerate(Rules)) {
812     if (I.index())
813       OS << (I.index() == Rules.size() - 1 ? ", and " : ", ");
814     OS << "'" << attr::getSubjectMatchRuleSpelling(I.value()) << "'";
815   }
816   return Result;
817 }
818 
819 } // end anonymous namespace
820 
821 void Sema::ActOnPragmaAttributeAttribute(
822     ParsedAttr &Attribute, SourceLocation PragmaLoc,
823     attr::ParsedSubjectMatchRuleSet Rules) {
824   Attribute.setIsPragmaClangAttribute();
825   SmallVector<attr::SubjectMatchRule, 4> SubjectMatchRules;
826   // Gather the subject match rules that are supported by the attribute.
827   SmallVector<std::pair<attr::SubjectMatchRule, bool>, 4>
828       StrictSubjectMatchRuleSet;
829   Attribute.getMatchRules(LangOpts, StrictSubjectMatchRuleSet);
830 
831   // Figure out which subject matching rules are valid.
832   if (StrictSubjectMatchRuleSet.empty()) {
833     // Check for contradicting match rules. Contradicting match rules are
834     // either:
835     //  - a top-level rule and one of its sub-rules. E.g. variable and
836     //    variable(is_parameter).
837     //  - a sub-rule and a sibling that's negated. E.g.
838     //    variable(is_thread_local) and variable(unless(is_parameter))
839     llvm::SmallDenseMap<int, std::pair<int, SourceRange>, 2>
840         RulesToFirstSpecifiedNegatedSubRule;
841     for (const auto &Rule : Rules) {
842       attr::SubjectMatchRule MatchRule = attr::SubjectMatchRule(Rule.first);
843       Optional<attr::SubjectMatchRule> ParentRule =
844           getParentAttrMatcherRule(MatchRule);
845       if (!ParentRule)
846         continue;
847       auto It = Rules.find(*ParentRule);
848       if (It != Rules.end()) {
849         // A sub-rule contradicts a parent rule.
850         Diag(Rule.second.getBegin(),
851              diag::err_pragma_attribute_matcher_subrule_contradicts_rule)
852             << attr::getSubjectMatchRuleSpelling(MatchRule)
853             << attr::getSubjectMatchRuleSpelling(*ParentRule) << It->second
854             << FixItHint::CreateRemoval(
855                    replacementRangeForListElement(*this, Rule.second));
856         // Keep going without removing this rule as it won't change the set of
857         // declarations that receive the attribute.
858         continue;
859       }
860       if (isNegatedAttrMatcherSubRule(MatchRule))
861         RulesToFirstSpecifiedNegatedSubRule.insert(
862             std::make_pair(*ParentRule, Rule));
863     }
864     bool IgnoreNegatedSubRules = false;
865     for (const auto &Rule : Rules) {
866       attr::SubjectMatchRule MatchRule = attr::SubjectMatchRule(Rule.first);
867       Optional<attr::SubjectMatchRule> ParentRule =
868           getParentAttrMatcherRule(MatchRule);
869       if (!ParentRule)
870         continue;
871       auto It = RulesToFirstSpecifiedNegatedSubRule.find(*ParentRule);
872       if (It != RulesToFirstSpecifiedNegatedSubRule.end() &&
873           It->second != Rule) {
874         // Negated sub-rule contradicts another sub-rule.
875         Diag(
876             It->second.second.getBegin(),
877             diag::
878                 err_pragma_attribute_matcher_negated_subrule_contradicts_subrule)
879             << attr::getSubjectMatchRuleSpelling(
880                    attr::SubjectMatchRule(It->second.first))
881             << attr::getSubjectMatchRuleSpelling(MatchRule) << Rule.second
882             << FixItHint::CreateRemoval(
883                    replacementRangeForListElement(*this, It->second.second));
884         // Keep going but ignore all of the negated sub-rules.
885         IgnoreNegatedSubRules = true;
886         RulesToFirstSpecifiedNegatedSubRule.erase(It);
887       }
888     }
889 
890     if (!IgnoreNegatedSubRules) {
891       for (const auto &Rule : Rules)
892         SubjectMatchRules.push_back(attr::SubjectMatchRule(Rule.first));
893     } else {
894       for (const auto &Rule : Rules) {
895         if (!isNegatedAttrMatcherSubRule(attr::SubjectMatchRule(Rule.first)))
896           SubjectMatchRules.push_back(attr::SubjectMatchRule(Rule.first));
897       }
898     }
899     Rules.clear();
900   } else {
901     // Each rule in Rules must be a strict subset of the attribute's
902     // SubjectMatch rules.  I.e. we're allowed to use
903     // `apply_to=variables(is_global)` on an attrubute with SubjectList<[Var]>,
904     // but should not allow `apply_to=variables` on an attribute which has
905     // `SubjectList<[GlobalVar]>`.
906     for (const auto &StrictRule : StrictSubjectMatchRuleSet) {
907       // First, check for exact match.
908       if (Rules.erase(StrictRule.first)) {
909         // Add the rule to the set of attribute receivers only if it's supported
910         // in the current language mode.
911         if (StrictRule.second)
912           SubjectMatchRules.push_back(StrictRule.first);
913       }
914     }
915     // Check remaining rules for subset matches.
916     auto RulesToCheck = Rules;
917     for (const auto &Rule : RulesToCheck) {
918       attr::SubjectMatchRule MatchRule = attr::SubjectMatchRule(Rule.first);
919       if (auto ParentRule = getParentAttrMatcherRule(MatchRule)) {
920         if (llvm::any_of(StrictSubjectMatchRuleSet,
921                          [ParentRule](const auto &StrictRule) {
922                            return StrictRule.first == *ParentRule &&
923                                   StrictRule.second; // IsEnabled
924                          })) {
925           SubjectMatchRules.push_back(MatchRule);
926           Rules.erase(MatchRule);
927         }
928       }
929     }
930   }
931 
932   if (!Rules.empty()) {
933     auto Diagnostic =
934         Diag(PragmaLoc, diag::err_pragma_attribute_invalid_matchers)
935         << Attribute;
936     SmallVector<attr::SubjectMatchRule, 2> ExtraRules;
937     for (const auto &Rule : Rules) {
938       ExtraRules.push_back(attr::SubjectMatchRule(Rule.first));
939       Diagnostic << FixItHint::CreateRemoval(
940           replacementRangeForListElement(*this, Rule.second));
941     }
942     Diagnostic << attrMatcherRuleListToString(ExtraRules);
943   }
944 
945   if (PragmaAttributeStack.empty()) {
946     Diag(PragmaLoc, diag::err_pragma_attr_attr_no_push);
947     return;
948   }
949 
950   PragmaAttributeStack.back().Entries.push_back(
951       {PragmaLoc, &Attribute, std::move(SubjectMatchRules), /*IsUsed=*/false});
952 }
953 
954 void Sema::ActOnPragmaAttributeEmptyPush(SourceLocation PragmaLoc,
955                                          const IdentifierInfo *Namespace) {
956   PragmaAttributeStack.emplace_back();
957   PragmaAttributeStack.back().Loc = PragmaLoc;
958   PragmaAttributeStack.back().Namespace = Namespace;
959 }
960 
961 void Sema::ActOnPragmaAttributePop(SourceLocation PragmaLoc,
962                                    const IdentifierInfo *Namespace) {
963   if (PragmaAttributeStack.empty()) {
964     Diag(PragmaLoc, diag::err_pragma_attribute_stack_mismatch) << 1;
965     return;
966   }
967 
968   // Dig back through the stack trying to find the most recently pushed group
969   // that in Namespace. Note that this works fine if no namespace is present,
970   // think of push/pops without namespaces as having an implicit "nullptr"
971   // namespace.
972   for (size_t Index = PragmaAttributeStack.size(); Index;) {
973     --Index;
974     if (PragmaAttributeStack[Index].Namespace == Namespace) {
975       for (const PragmaAttributeEntry &Entry :
976            PragmaAttributeStack[Index].Entries) {
977         if (!Entry.IsUsed) {
978           assert(Entry.Attribute && "Expected an attribute");
979           Diag(Entry.Attribute->getLoc(), diag::warn_pragma_attribute_unused)
980               << *Entry.Attribute;
981           Diag(PragmaLoc, diag::note_pragma_attribute_region_ends_here);
982         }
983       }
984       PragmaAttributeStack.erase(PragmaAttributeStack.begin() + Index);
985       return;
986     }
987   }
988 
989   if (Namespace)
990     Diag(PragmaLoc, diag::err_pragma_attribute_stack_mismatch)
991         << 0 << Namespace->getName();
992   else
993     Diag(PragmaLoc, diag::err_pragma_attribute_stack_mismatch) << 1;
994 }
995 
996 void Sema::AddPragmaAttributes(Scope *S, Decl *D) {
997   if (PragmaAttributeStack.empty())
998     return;
999   for (auto &Group : PragmaAttributeStack) {
1000     for (auto &Entry : Group.Entries) {
1001       ParsedAttr *Attribute = Entry.Attribute;
1002       assert(Attribute && "Expected an attribute");
1003       assert(Attribute->isPragmaClangAttribute() &&
1004              "expected #pragma clang attribute");
1005 
1006       // Ensure that the attribute can be applied to the given declaration.
1007       bool Applies = false;
1008       for (const auto &Rule : Entry.MatchRules) {
1009         if (Attribute->appliesToDecl(D, Rule)) {
1010           Applies = true;
1011           break;
1012         }
1013       }
1014       if (!Applies)
1015         continue;
1016       Entry.IsUsed = true;
1017       PragmaAttributeCurrentTargetDecl = D;
1018       ParsedAttributesView Attrs;
1019       Attrs.addAtEnd(Attribute);
1020       ProcessDeclAttributeList(S, D, Attrs);
1021       PragmaAttributeCurrentTargetDecl = nullptr;
1022     }
1023   }
1024 }
1025 
1026 void Sema::PrintPragmaAttributeInstantiationPoint() {
1027   assert(PragmaAttributeCurrentTargetDecl && "Expected an active declaration");
1028   Diags.Report(PragmaAttributeCurrentTargetDecl->getBeginLoc(),
1029                diag::note_pragma_attribute_applied_decl_here);
1030 }
1031 
1032 void Sema::DiagnoseUnterminatedPragmaAttribute() {
1033   if (PragmaAttributeStack.empty())
1034     return;
1035   Diag(PragmaAttributeStack.back().Loc, diag::err_pragma_attribute_no_pop_eof);
1036 }
1037 
1038 void Sema::ActOnPragmaOptimize(bool On, SourceLocation PragmaLoc) {
1039   if(On)
1040     OptimizeOffPragmaLocation = SourceLocation();
1041   else
1042     OptimizeOffPragmaLocation = PragmaLoc;
1043 }
1044 
1045 void Sema::AddRangeBasedOptnone(FunctionDecl *FD) {
1046   // In the future, check other pragmas if they're implemented (e.g. pragma
1047   // optimize 0 will probably map to this functionality too).
1048   if(OptimizeOffPragmaLocation.isValid())
1049     AddOptnoneAttributeIfNoConflicts(FD, OptimizeOffPragmaLocation);
1050 }
1051 
1052 void Sema::AddOptnoneAttributeIfNoConflicts(FunctionDecl *FD,
1053                                             SourceLocation Loc) {
1054   // Don't add a conflicting attribute. No diagnostic is needed.
1055   if (FD->hasAttr<MinSizeAttr>() || FD->hasAttr<AlwaysInlineAttr>())
1056     return;
1057 
1058   // Add attributes only if required. Optnone requires noinline as well, but if
1059   // either is already present then don't bother adding them.
1060   if (!FD->hasAttr<OptimizeNoneAttr>())
1061     FD->addAttr(OptimizeNoneAttr::CreateImplicit(Context, Loc));
1062   if (!FD->hasAttr<NoInlineAttr>())
1063     FD->addAttr(NoInlineAttr::CreateImplicit(Context, Loc));
1064 }
1065 
1066 typedef std::vector<std::pair<unsigned, SourceLocation> > VisStack;
1067 enum : unsigned { NoVisibility = ~0U };
1068 
1069 void Sema::AddPushedVisibilityAttribute(Decl *D) {
1070   if (!VisContext)
1071     return;
1072 
1073   NamedDecl *ND = dyn_cast<NamedDecl>(D);
1074   if (ND && ND->getExplicitVisibility(NamedDecl::VisibilityForValue))
1075     return;
1076 
1077   VisStack *Stack = static_cast<VisStack*>(VisContext);
1078   unsigned rawType = Stack->back().first;
1079   if (rawType == NoVisibility) return;
1080 
1081   VisibilityAttr::VisibilityType type
1082     = (VisibilityAttr::VisibilityType) rawType;
1083   SourceLocation loc = Stack->back().second;
1084 
1085   D->addAttr(VisibilityAttr::CreateImplicit(Context, type, loc));
1086 }
1087 
1088 /// FreeVisContext - Deallocate and null out VisContext.
1089 void Sema::FreeVisContext() {
1090   delete static_cast<VisStack*>(VisContext);
1091   VisContext = nullptr;
1092 }
1093 
1094 static void PushPragmaVisibility(Sema &S, unsigned type, SourceLocation loc) {
1095   // Put visibility on stack.
1096   if (!S.VisContext)
1097     S.VisContext = new VisStack;
1098 
1099   VisStack *Stack = static_cast<VisStack*>(S.VisContext);
1100   Stack->push_back(std::make_pair(type, loc));
1101 }
1102 
1103 void Sema::ActOnPragmaVisibility(const IdentifierInfo* VisType,
1104                                  SourceLocation PragmaLoc) {
1105   if (VisType) {
1106     // Compute visibility to use.
1107     VisibilityAttr::VisibilityType T;
1108     if (!VisibilityAttr::ConvertStrToVisibilityType(VisType->getName(), T)) {
1109       Diag(PragmaLoc, diag::warn_attribute_unknown_visibility) << VisType;
1110       return;
1111     }
1112     PushPragmaVisibility(*this, T, PragmaLoc);
1113   } else {
1114     PopPragmaVisibility(false, PragmaLoc);
1115   }
1116 }
1117 
1118 void Sema::ActOnPragmaFPContract(SourceLocation Loc,
1119                                  LangOptions::FPModeKind FPC) {
1120   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
1121   switch (FPC) {
1122   case LangOptions::FPM_On:
1123     NewFPFeatures.setAllowFPContractWithinStatement();
1124     break;
1125   case LangOptions::FPM_Fast:
1126     NewFPFeatures.setAllowFPContractAcrossStatement();
1127     break;
1128   case LangOptions::FPM_Off:
1129     NewFPFeatures.setDisallowFPContract();
1130     break;
1131   case LangOptions::FPM_FastHonorPragmas:
1132     llvm_unreachable("Should not happen");
1133   }
1134   FpPragmaStack.Act(Loc, Sema::PSK_Set, StringRef(), NewFPFeatures);
1135   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
1136 }
1137 
1138 void Sema::ActOnPragmaFPReassociate(SourceLocation Loc, bool IsEnabled) {
1139   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
1140   NewFPFeatures.setAllowFPReassociateOverride(IsEnabled);
1141   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
1142   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
1143 }
1144 
1145 void Sema::setRoundingMode(SourceLocation Loc, llvm::RoundingMode FPR) {
1146   // C2x: 7.6.2p3  If the FE_DYNAMIC mode is specified and FENV_ACCESS is "off",
1147   // the translator may assume that the default rounding mode is in effect.
1148   if (FPR == llvm::RoundingMode::Dynamic &&
1149       !CurFPFeatures.getAllowFEnvAccess() &&
1150       CurFPFeatures.getFPExceptionMode() == LangOptions::FPE_Ignore)
1151     FPR = llvm::RoundingMode::NearestTiesToEven;
1152 
1153   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
1154   NewFPFeatures.setRoundingModeOverride(FPR);
1155   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
1156   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
1157 }
1158 
1159 void Sema::setExceptionMode(SourceLocation Loc,
1160                             LangOptions::FPExceptionModeKind FPE) {
1161   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
1162   NewFPFeatures.setFPExceptionModeOverride(FPE);
1163   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
1164   CurFPFeatures = NewFPFeatures.applyOverrides(getLangOpts());
1165 }
1166 
1167 void Sema::ActOnPragmaFEnvAccess(SourceLocation Loc, bool IsEnabled) {
1168   FPOptionsOverride NewFPFeatures = CurFPFeatureOverrides();
1169   auto LO = getLangOpts();
1170   if (IsEnabled) {
1171     // Verify Microsoft restriction:
1172     // You can't enable fenv_access unless precise semantics are enabled.
1173     // Precise semantics can be enabled either by the float_control
1174     // pragma, or by using the /fp:precise or /fp:strict compiler options
1175     if (!isPreciseFPEnabled())
1176       Diag(Loc, diag::err_pragma_fenv_requires_precise);
1177     NewFPFeatures.setAllowFEnvAccessOverride(true);
1178     // Enabling FENV access sets the RoundingMode to Dynamic.
1179     // and ExceptionBehavior to Strict
1180     NewFPFeatures.setRoundingModeOverride(llvm::RoundingMode::Dynamic);
1181     NewFPFeatures.setFPExceptionModeOverride(LangOptions::FPE_Strict);
1182   } else {
1183     NewFPFeatures.setAllowFEnvAccessOverride(false);
1184   }
1185   FpPragmaStack.Act(Loc, PSK_Set, StringRef(), NewFPFeatures);
1186   CurFPFeatures = NewFPFeatures.applyOverrides(LO);
1187 }
1188 
1189 void Sema::ActOnPragmaFPExceptions(SourceLocation Loc,
1190                                    LangOptions::FPExceptionModeKind FPE) {
1191   setExceptionMode(Loc, FPE);
1192 }
1193 
1194 void Sema::PushNamespaceVisibilityAttr(const VisibilityAttr *Attr,
1195                                        SourceLocation Loc) {
1196   // Visibility calculations will consider the namespace's visibility.
1197   // Here we just want to note that we're in a visibility context
1198   // which overrides any enclosing #pragma context, but doesn't itself
1199   // contribute visibility.
1200   PushPragmaVisibility(*this, NoVisibility, Loc);
1201 }
1202 
1203 void Sema::PopPragmaVisibility(bool IsNamespaceEnd, SourceLocation EndLoc) {
1204   if (!VisContext) {
1205     Diag(EndLoc, diag::err_pragma_pop_visibility_mismatch);
1206     return;
1207   }
1208 
1209   // Pop visibility from stack
1210   VisStack *Stack = static_cast<VisStack*>(VisContext);
1211 
1212   const std::pair<unsigned, SourceLocation> *Back = &Stack->back();
1213   bool StartsWithPragma = Back->first != NoVisibility;
1214   if (StartsWithPragma && IsNamespaceEnd) {
1215     Diag(Back->second, diag::err_pragma_push_visibility_mismatch);
1216     Diag(EndLoc, diag::note_surrounding_namespace_ends_here);
1217 
1218     // For better error recovery, eat all pushes inside the namespace.
1219     do {
1220       Stack->pop_back();
1221       Back = &Stack->back();
1222       StartsWithPragma = Back->first != NoVisibility;
1223     } while (StartsWithPragma);
1224   } else if (!StartsWithPragma && !IsNamespaceEnd) {
1225     Diag(EndLoc, diag::err_pragma_pop_visibility_mismatch);
1226     Diag(Back->second, diag::note_surrounding_namespace_starts_here);
1227     return;
1228   }
1229 
1230   Stack->pop_back();
1231   // To simplify the implementation, never keep around an empty stack.
1232   if (Stack->empty())
1233     FreeVisContext();
1234 }
1235 
1236 template <typename Ty>
1237 static bool checkCommonAttributeFeatures(Sema &S, const Ty *Node,
1238                                          const ParsedAttr &A,
1239                                          bool SkipArgCountCheck) {
1240   // Several attributes carry different semantics than the parsing requires, so
1241   // those are opted out of the common argument checks.
1242   //
1243   // We also bail on unknown and ignored attributes because those are handled
1244   // as part of the target-specific handling logic.
1245   if (A.getKind() == ParsedAttr::UnknownAttribute)
1246     return false;
1247   // Check whether the attribute requires specific language extensions to be
1248   // enabled.
1249   if (!A.diagnoseLangOpts(S))
1250     return true;
1251   // Check whether the attribute appertains to the given subject.
1252   if (!A.diagnoseAppertainsTo(S, Node))
1253     return true;
1254   // Check whether the attribute is mutually exclusive with other attributes
1255   // that have already been applied to the declaration.
1256   if (!A.diagnoseMutualExclusion(S, Node))
1257     return true;
1258   // Check whether the attribute exists in the target architecture.
1259   if (S.CheckAttrTarget(A))
1260     return true;
1261 
1262   if (A.hasCustomParsing())
1263     return false;
1264 
1265   if (!SkipArgCountCheck) {
1266     if (A.getMinArgs() == A.getMaxArgs()) {
1267       // If there are no optional arguments, then checking for the argument
1268       // count is trivial.
1269       if (!A.checkExactlyNumArgs(S, A.getMinArgs()))
1270         return true;
1271     } else {
1272       // There are optional arguments, so checking is slightly more involved.
1273       if (A.getMinArgs() && !A.checkAtLeastNumArgs(S, A.getMinArgs()))
1274         return true;
1275       else if (!A.hasVariadicArg() && A.getMaxArgs() &&
1276                !A.checkAtMostNumArgs(S, A.getMaxArgs()))
1277         return true;
1278     }
1279   }
1280 
1281   return false;
1282 }
1283 
1284 bool Sema::checkCommonAttributeFeatures(const Decl *D, const ParsedAttr &A,
1285                                         bool SkipArgCountCheck) {
1286   return ::checkCommonAttributeFeatures(*this, D, A, SkipArgCountCheck);
1287 }
1288 bool Sema::checkCommonAttributeFeatures(const Stmt *S, const ParsedAttr &A,
1289                                         bool SkipArgCountCheck) {
1290   return ::checkCommonAttributeFeatures(*this, S, A, SkipArgCountCheck);
1291 }
1292