clang/lib/Sema/SemaStmtAttr.cpp

   1 //===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//
   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 stmt-related attribute processing.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/AST/ASTContext.h"
  14 #include "clang/AST/EvaluatedExprVisitor.h"
  15 #include "clang/Basic/TargetInfo.h"
  16 #include "clang/Sema/DelayedDiagnostic.h"
  17 #include "clang/Sema/ParsedAttr.h"
  18 #include "clang/Sema/ScopeInfo.h"
  19 #include <optional>
  20
  21 using namespace clang;
  22 using namespace sema;
  23
  24 static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,
  25                                    SourceRange Range) {
  26   FallThroughAttr Attr(S.Context, A);
  27   if (isa<SwitchCase>(St)) {
  28     S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
  29         << A << St->getBeginLoc();
  30     SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
  31     S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
  32         << FixItHint::CreateInsertion(L, ";");
  33     return nullptr;
  34   }
  35   auto *FnScope = S.getCurFunction();
  36   if (FnScope->SwitchStack.empty()) {
  37     S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
  38     return nullptr;
  39   }
  40
  41   // If this is spelled as the standard C++17 attribute, but not in C++17, warn
  42   // about using it as an extension.
  43   if (!S.getLangOpts().CPlusPlus17 && A.isCXX11Attribute() &&
  44       !A.getScopeName())
  45     S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A;
  46
  47   FnScope->setHasFallthroughStmt();
  48   return ::new (S.Context) FallThroughAttr(S.Context, A);
  49 }
  50
  51 static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
  52                                 SourceRange Range) {
  53   if (A.getAttributeSpellingListIndex() == SuppressAttr::CXX11_gsl_suppress &&
  54       A.getNumArgs() < 1) {
  55     // Suppression attribute with GSL spelling requires at least 1 argument.
  56     S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;
  57     return nullptr;
  58   }
  59
  60   std::vector<StringRef> DiagnosticIdentifiers;
  61   for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
  62     StringRef RuleName;
  63
  64     if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
  65       return nullptr;
  66
  67     DiagnosticIdentifiers.push_back(RuleName);
  68   }
  69
  70   return ::new (S.Context) SuppressAttr(
  71       S.Context, A, DiagnosticIdentifiers.data(), DiagnosticIdentifiers.size());
  72 }
  73
  74 static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
  75                                 SourceRange) {
  76   IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
  77   IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
  78   IdentifierLoc *StateLoc = A.getArgAsIdent(2);
  79   Expr *ValueExpr = A.getArgAsExpr(3);
  80
  81   StringRef PragmaName =
  82       llvm::StringSwitch<StringRef>(PragmaNameLoc->Ident->getName())
  83           .Cases("unroll", "nounroll", "unroll_and_jam", "nounroll_and_jam",
  84                  PragmaNameLoc->Ident->getName())
  85           .Default("clang loop");
  86
  87   // This could be handled automatically by adding a Subjects definition in
  88   // Attr.td, but that would make the diagnostic behavior worse in this case
  89   // because the user spells this attribute as a pragma.
  90   if (!isa<DoStmt, ForStmt, CXXForRangeStmt, WhileStmt>(St)) {
  91     std::string Pragma = "#pragma " + std::string(PragmaName);
  92     S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
  93     return nullptr;
  94   }
  95
  96   LoopHintAttr::OptionType Option;
  97   LoopHintAttr::LoopHintState State;
  98
  99   auto SetHints = [&Option, &State](LoopHintAttr::OptionType O,
 100                                     LoopHintAttr::LoopHintState S) {
 101     Option = O;
 102     State = S;
 103   };
 104
 105   if (PragmaName == "nounroll") {
 106     SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);
 107   } else if (PragmaName == "unroll") {
 108     // #pragma unroll N
 109     if (ValueExpr) {
 110       if (!ValueExpr->isValueDependent()) {
 111         auto Value = ValueExpr->EvaluateKnownConstInt(S.getASTContext());
 112         if (Value.isZero() || Value.isOne())
 113           SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);
 114         else
 115           SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
 116       } else
 117         SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
 118     } else
 119       SetHints(LoopHintAttr::Unroll, LoopHintAttr::Enable);
 120   } else if (PragmaName == "nounroll_and_jam") {
 121     SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Disable);
 122   } else if (PragmaName == "unroll_and_jam") {
 123     // #pragma unroll_and_jam N
 124     if (ValueExpr)
 125       SetHints(LoopHintAttr::UnrollAndJamCount, LoopHintAttr::Numeric);
 126     else
 127       SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Enable);
 128   } else {
 129     // #pragma clang loop ...
 130     assert(OptionLoc && OptionLoc->Ident &&
 131            "Attribute must have valid option info.");
 132     Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
 133                  OptionLoc->Ident->getName())
 134                  .Case("vectorize", LoopHintAttr::Vectorize)
 135                  .Case("vectorize_width", LoopHintAttr::VectorizeWidth)
 136                  .Case("interleave", LoopHintAttr::Interleave)
 137                  .Case("vectorize_predicate", LoopHintAttr::VectorizePredicate)
 138                  .Case("interleave_count", LoopHintAttr::InterleaveCount)
 139                  .Case("unroll", LoopHintAttr::Unroll)
 140                  .Case("unroll_count", LoopHintAttr::UnrollCount)
 141                  .Case("pipeline", LoopHintAttr::PipelineDisabled)
 142                  .Case("pipeline_initiation_interval",
 143                        LoopHintAttr::PipelineInitiationInterval)
 144                  .Case("distribute", LoopHintAttr::Distribute)
 145                  .Default(LoopHintAttr::Vectorize);
 146     if (Option == LoopHintAttr::VectorizeWidth) {
 147       assert((ValueExpr || (StateLoc && StateLoc->Ident)) &&
 148              "Attribute must have a valid value expression or argument.");
 149       if (ValueExpr && S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc(),
 150                                            /*AllowZero=*/false))
 151         return nullptr;
 152       if (StateLoc && StateLoc->Ident && StateLoc->Ident->isStr("scalable"))
 153         State = LoopHintAttr::ScalableWidth;
 154       else
 155         State = LoopHintAttr::FixedWidth;
 156     } else if (Option == LoopHintAttr::InterleaveCount ||
 157                Option == LoopHintAttr::UnrollCount ||
 158                Option == LoopHintAttr::PipelineInitiationInterval) {
 159       assert(ValueExpr && "Attribute must have a valid value expression.");
 160       if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc(),
 161                               /*AllowZero=*/false))
 162         return nullptr;
 163       State = LoopHintAttr::Numeric;
 164     } else if (Option == LoopHintAttr::Vectorize ||
 165                Option == LoopHintAttr::Interleave ||
 166                Option == LoopHintAttr::VectorizePredicate ||
 167                Option == LoopHintAttr::Unroll ||
 168                Option == LoopHintAttr::Distribute ||
 169                Option == LoopHintAttr::PipelineDisabled) {
 170       assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
 171       if (StateLoc->Ident->isStr("disable"))
 172         State = LoopHintAttr::Disable;
 173       else if (StateLoc->Ident->isStr("assume_safety"))
 174         State = LoopHintAttr::AssumeSafety;
 175       else if (StateLoc->Ident->isStr("full"))
 176         State = LoopHintAttr::Full;
 177       else if (StateLoc->Ident->isStr("enable"))
 178         State = LoopHintAttr::Enable;
 179       else
 180         llvm_unreachable("bad loop hint argument");
 181     } else
 182       llvm_unreachable("bad loop hint");
 183   }
 184
 185   return LoopHintAttr::CreateImplicit(S.Context, Option, State, ValueExpr, A);
 186 }
 187
 188 namespace {
 189 class CallExprFinder : public ConstEvaluatedExprVisitor<CallExprFinder> {
 190   bool FoundAsmStmt = false;
 191   std::vector<const CallExpr *> CallExprs;
 192
 193 public:
 194   typedef ConstEvaluatedExprVisitor<CallExprFinder> Inherited;
 195
 196   CallExprFinder(Sema &S, const Stmt *St) : Inherited(S.Context) { Visit(St); }
 197
 198   bool foundCallExpr() { return !CallExprs.empty(); }
 199   const std::vector<const CallExpr *> &getCallExprs() { return CallExprs; }
 200
 201   bool foundAsmStmt() { return FoundAsmStmt; }
 202
 203   void VisitCallExpr(const CallExpr *E) { CallExprs.push_back(E); }
 204
 205   void VisitAsmStmt(const AsmStmt *S) { FoundAsmStmt = true; }
 206
 207   void Visit(const Stmt *St) {
 208     if (!St)
 209       return;
 210     ConstEvaluatedExprVisitor<CallExprFinder>::Visit(St);
 211   }
 212 };
 213 } // namespace
 214
 215 static Attr *handleNoMergeAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 216                                SourceRange Range) {
 217   CallExprFinder CEF(S, St);
 218
 219   if (!CEF.foundCallExpr() && !CEF.foundAsmStmt()) {
 220     S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
 221         << A;
 222     return nullptr;
 223   }
 224
 225   return ::new (S.Context) NoMergeAttr(S.Context, A);
 226 }
 227
 228 static Attr *handleNoConvergentAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 229                                     SourceRange Range) {
 230   CallExprFinder CEF(S, St);
 231
 232   if (!CEF.foundCallExpr() && !CEF.foundAsmStmt()) {
 233     S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
 234         << A;
 235     return nullptr;
 236   }
 237
 238   return ::new (S.Context) NoConvergentAttr(S.Context, A);
 239 }
 240
 241 template <typename OtherAttr, int DiagIdx>
 242 static bool CheckStmtInlineAttr(Sema &SemaRef, const Stmt *OrigSt,
 243                                 const Stmt *CurSt,
 244                                 const AttributeCommonInfo &A) {
 245   CallExprFinder OrigCEF(SemaRef, OrigSt);
 246   CallExprFinder CEF(SemaRef, CurSt);
 247
 248   // If the call expressions lists are equal in size, we can skip
 249   // previously emitted diagnostics. However, if the statement has a pack
 250   // expansion, we have no way of telling which CallExpr is the instantiated
 251   // version of the other. In this case, we will end up re-diagnosing in the
 252   // instantiation.
 253   // ie: [[clang::always_inline]] non_dependent(), (other_call<Pack>()...)
 254   // will diagnose nondependent again.
 255   bool CanSuppressDiag =
 256       OrigSt && CEF.getCallExprs().size() == OrigCEF.getCallExprs().size();
 257
 258   if (!CEF.foundCallExpr()) {
 259     return SemaRef.Diag(CurSt->getBeginLoc(),
 260                         diag::warn_attribute_ignored_no_calls_in_stmt)
 261            << A;
 262   }
 263
 264   for (const auto &Tup :
 265        llvm::zip_longest(OrigCEF.getCallExprs(), CEF.getCallExprs())) {
 266     // If the original call expression already had a callee, we already
 267     // diagnosed this, so skip it here. We can't skip if there isn't a 1:1
 268     // relationship between the two lists of call expressions.
 269     if (!CanSuppressDiag || !(*std::get<0>(Tup))->getCalleeDecl()) {
 270       const Decl *Callee = (*std::get<1>(Tup))->getCalleeDecl();
 271       if (Callee &&
 272           (Callee->hasAttr<OtherAttr>() || Callee->hasAttr<FlattenAttr>())) {
 273         SemaRef.Diag(CurSt->getBeginLoc(),
 274                      diag::warn_function_stmt_attribute_precedence)
 275             << A << (Callee->hasAttr<OtherAttr>() ? DiagIdx : 1);
 276         SemaRef.Diag(Callee->getBeginLoc(), diag::note_conflicting_attribute);
 277       }
 278     }
 279   }
 280
 281   return false;
 282 }
 283
 284 bool Sema::CheckNoInlineAttr(const Stmt *OrigSt, const Stmt *CurSt,
 285                              const AttributeCommonInfo &A) {
 286   return CheckStmtInlineAttr<AlwaysInlineAttr, 0>(*this, OrigSt, CurSt, A);
 287 }
 288
 289 bool Sema::CheckAlwaysInlineAttr(const Stmt *OrigSt, const Stmt *CurSt,
 290                                  const AttributeCommonInfo &A) {
 291   return CheckStmtInlineAttr<NoInlineAttr, 2>(*this, OrigSt, CurSt, A);
 292 }
 293
 294 static Attr *handleNoInlineAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 295                                 SourceRange Range) {
 296   NoInlineAttr NIA(S.Context, A);
 297   if (!NIA.isStmtNoInline()) {
 298     S.Diag(St->getBeginLoc(), diag::warn_function_attribute_ignored_in_stmt)
 299         << "[[clang::noinline]]";
 300     return nullptr;
 301   }
 302
 303   if (S.CheckNoInlineAttr(/*OrigSt=*/nullptr, St, A))
 304     return nullptr;
 305
 306   return ::new (S.Context) NoInlineAttr(S.Context, A);
 307 }
 308
 309 static Attr *handleAlwaysInlineAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 310                                     SourceRange Range) {
 311   AlwaysInlineAttr AIA(S.Context, A);
 312   if (!AIA.isClangAlwaysInline()) {
 313     S.Diag(St->getBeginLoc(), diag::warn_function_attribute_ignored_in_stmt)
 314         << "[[clang::always_inline]]";
 315     return nullptr;
 316   }
 317
 318   if (S.CheckAlwaysInlineAttr(/*OrigSt=*/nullptr, St, A))
 319     return nullptr;
 320
 321   return ::new (S.Context) AlwaysInlineAttr(S.Context, A);
 322 }
 323
 324 static Attr *handleCXXAssumeAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 325                                  SourceRange Range) {
 326   ExprResult Res = S.ActOnCXXAssumeAttr(St, A, Range);
 327   if (!Res.isUsable())
 328     return nullptr;
 329
 330   return ::new (S.Context) CXXAssumeAttr(S.Context, A, Res.get());
 331 }
 332
 333 static Attr *handleMustTailAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 334                                 SourceRange Range) {
 335   // Validation is in Sema::ActOnAttributedStmt().
 336   return ::new (S.Context) MustTailAttr(S.Context, A);
 337 }
 338
 339 static Attr *handleLikely(Sema &S, Stmt *St, const ParsedAttr &A,
 340                           SourceRange Range) {
 341
 342   if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
 343     S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
 344
 345   return ::new (S.Context) LikelyAttr(S.Context, A);
 346 }
 347
 348 static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,
 349                             SourceRange Range) {
 350
 351   if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
 352     S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
 353
 354   return ::new (S.Context) UnlikelyAttr(S.Context, A);
 355 }
 356
 357 CodeAlignAttr *Sema::BuildCodeAlignAttr(const AttributeCommonInfo &CI,
 358                                         Expr *E) {
 359   if (!E->isValueDependent()) {
 360     llvm::APSInt ArgVal;
 361     ExprResult Res = VerifyIntegerConstantExpression(E, &ArgVal);
 362     if (Res.isInvalid())
 363       return nullptr;
 364     E = Res.get();
 365
 366     // This attribute requires an integer argument which is a constant power of
 367     // two between 1 and 4096 inclusive.
 368     if (ArgVal < CodeAlignAttr::MinimumAlignment ||
 369         ArgVal > CodeAlignAttr::MaximumAlignment || !ArgVal.isPowerOf2()) {
 370       if (std::optional<int64_t> Value = ArgVal.trySExtValue())
 371         Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
 372             << CI << CodeAlignAttr::MinimumAlignment
 373             << CodeAlignAttr::MaximumAlignment << Value.value();
 374       else
 375         Diag(CI.getLoc(), diag::err_attribute_power_of_two_in_range)
 376             << CI << CodeAlignAttr::MinimumAlignment
 377             << CodeAlignAttr::MaximumAlignment << E;
 378       return nullptr;
 379     }
 380   }
 381   return new (Context) CodeAlignAttr(Context, CI, E);
 382 }
 383
 384 static Attr *handleCodeAlignAttr(Sema &S, Stmt *St, const ParsedAttr &A) {
 385
 386   Expr *E = A.getArgAsExpr(0);
 387   return S.BuildCodeAlignAttr(A, E);
 388 }
 389
 390 // Diagnose non-identical duplicates as a 'conflicting' loop attributes
 391 // and suppress duplicate errors in cases where the two match.
 392 template <typename LoopAttrT>
 393 static void CheckForDuplicateLoopAttrs(Sema &S, ArrayRef<const Attr *> Attrs) {
 394   auto FindFunc = [](const Attr *A) { return isa<const LoopAttrT>(A); };
 395   const auto *FirstItr = std::find_if(Attrs.begin(), Attrs.end(), FindFunc);
 396
 397   if (FirstItr == Attrs.end()) // no attributes found
 398     return;
 399
 400   const auto *LastFoundItr = FirstItr;
 401   std::optional<llvm::APSInt> FirstValue;
 402
 403   const auto *CAFA =
 404       dyn_cast<ConstantExpr>(cast<LoopAttrT>(*FirstItr)->getAlignment());
 405   // Return early if first alignment expression is dependent (since we don't
 406   // know what the effective size will be), and skip the loop entirely.
 407   if (!CAFA)
 408     return;
 409
 410   while (Attrs.end() != (LastFoundItr = std::find_if(LastFoundItr + 1,
 411                                                      Attrs.end(), FindFunc))) {
 412     const auto *CASA =
 413         dyn_cast<ConstantExpr>(cast<LoopAttrT>(*LastFoundItr)->getAlignment());
 414     // If the value is dependent, we can not test anything.
 415     if (!CASA)
 416       return;
 417     // Test the attribute values.
 418     llvm::APSInt SecondValue = CASA->getResultAsAPSInt();
 419     if (!FirstValue)
 420       FirstValue = CAFA->getResultAsAPSInt();
 421
 422     if (FirstValue != SecondValue) {
 423       S.Diag((*LastFoundItr)->getLocation(), diag::err_loop_attr_conflict)
 424           << *FirstItr;
 425       S.Diag((*FirstItr)->getLocation(), diag::note_previous_attribute);
 426     }
 427   }
 428   return;
 429 }
 430
 431 static Attr *handleMSConstexprAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 432                                    SourceRange Range) {
 433   if (!S.getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2022_3)) {
 434     S.Diag(A.getLoc(), diag::warn_unknown_attribute_ignored)
 435         << A << A.getRange();
 436     return nullptr;
 437   }
 438   return ::new (S.Context) MSConstexprAttr(S.Context, A);
 439 }
 440
 441 #define WANT_STMT_MERGE_LOGIC
 442 #include "clang/Sema/AttrParsedAttrImpl.inc"
 443 #undef WANT_STMT_MERGE_LOGIC
 444
 445 static void
 446 CheckForIncompatibleAttributes(Sema &S,
 447                                const SmallVectorImpl<const Attr *> &Attrs) {
 448   // The vast majority of attributed statements will only have one attribute
 449   // on them, so skip all of the checking in the common case.
 450   if (Attrs.size() < 2)
 451     return;
 452
 453   // First, check for the easy cases that are table-generated for us.
 454   if (!DiagnoseMutualExclusions(S, Attrs))
 455     return;
 456
 457   enum CategoryType {
 458     // For the following categories, they come in two variants: a state form and
 459     // a numeric form. The state form may be one of default, enable, and
 460     // disable. The numeric form provides an integer hint (for example, unroll
 461     // count) to the transformer.
 462     Vectorize,
 463     Interleave,
 464     UnrollAndJam,
 465     Pipeline,
 466     // For unroll, default indicates full unrolling rather than enabling the
 467     // transformation.
 468     Unroll,
 469     // The loop distribution transformation only has a state form that is
 470     // exposed by #pragma clang loop distribute (enable | disable).
 471     Distribute,
 472     // The vector predication only has a state form that is exposed by
 473     // #pragma clang loop vectorize_predicate (enable | disable).
 474     VectorizePredicate,
 475     // This serves as a indicator to how many category are listed in this enum.
 476     NumberOfCategories
 477   };
 478   // The following array accumulates the hints encountered while iterating
 479   // through the attributes to check for compatibility.
 480   struct {
 481     const LoopHintAttr *StateAttr;
 482     const LoopHintAttr *NumericAttr;
 483   } HintAttrs[CategoryType::NumberOfCategories] = {};
 484
 485   for (const auto *I : Attrs) {
 486     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
 487
 488     // Skip non loop hint attributes
 489     if (!LH)
 490       continue;
 491
 492     CategoryType Category = CategoryType::NumberOfCategories;
 493     LoopHintAttr::OptionType Option = LH->getOption();
 494     switch (Option) {
 495     case LoopHintAttr::Vectorize:
 496     case LoopHintAttr::VectorizeWidth:
 497       Category = Vectorize;
 498       break;
 499     case LoopHintAttr::Interleave:
 500     case LoopHintAttr::InterleaveCount:
 501       Category = Interleave;
 502       break;
 503     case LoopHintAttr::Unroll:
 504     case LoopHintAttr::UnrollCount:
 505       Category = Unroll;
 506       break;
 507     case LoopHintAttr::UnrollAndJam:
 508     case LoopHintAttr::UnrollAndJamCount:
 509       Category = UnrollAndJam;
 510       break;
 511     case LoopHintAttr::Distribute:
 512       // Perform the check for duplicated 'distribute' hints.
 513       Category = Distribute;
 514       break;
 515     case LoopHintAttr::PipelineDisabled:
 516     case LoopHintAttr::PipelineInitiationInterval:
 517       Category = Pipeline;
 518       break;
 519     case LoopHintAttr::VectorizePredicate:
 520       Category = VectorizePredicate;
 521       break;
 522     };
 523
 524     assert(Category != NumberOfCategories && "Unhandled loop hint option");
 525     auto &CategoryState = HintAttrs[Category];
 526     const LoopHintAttr *PrevAttr;
 527     if (Option == LoopHintAttr::Vectorize ||
 528         Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
 529         Option == LoopHintAttr::UnrollAndJam ||
 530         Option == LoopHintAttr::VectorizePredicate ||
 531         Option == LoopHintAttr::PipelineDisabled ||
 532         Option == LoopHintAttr::Distribute) {
 533       // Enable|Disable|AssumeSafety hint.  For example, vectorize(enable).
 534       PrevAttr = CategoryState.StateAttr;
 535       CategoryState.StateAttr = LH;
 536     } else {
 537       // Numeric hint.  For example, vectorize_width(8).
 538       PrevAttr = CategoryState.NumericAttr;
 539       CategoryState.NumericAttr = LH;
 540     }
 541
 542     PrintingPolicy Policy(S.Context.getLangOpts());
 543     SourceLocation OptionLoc = LH->getRange().getBegin();
 544     if (PrevAttr)
 545       // Cannot specify same type of attribute twice.
 546       S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
 547           << /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
 548           << LH->getDiagnosticName(Policy);
 549
 550     if (CategoryState.StateAttr && CategoryState.NumericAttr &&
 551         (Category == Unroll || Category == UnrollAndJam ||
 552          CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
 553       // Disable hints are not compatible with numeric hints of the same
 554       // category.  As a special case, numeric unroll hints are also not
 555       // compatible with enable or full form of the unroll pragma because these
 556       // directives indicate full unrolling.
 557       S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
 558           << /*Duplicate=*/false
 559           << CategoryState.StateAttr->getDiagnosticName(Policy)
 560           << CategoryState.NumericAttr->getDiagnosticName(Policy);
 561     }
 562   }
 563 }
 564
 565 static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,
 566                                     SourceRange Range) {
 567   // Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's
 568   // useful for OpenCL 1.x too and doesn't require HW support.
 569   // opencl_unroll_hint can have 0 arguments (compiler
 570   // determines unrolling factor) or 1 argument (the unroll factor provided
 571   // by the user).
 572   unsigned UnrollFactor = 0;
 573   if (A.getNumArgs() == 1) {
 574     Expr *E = A.getArgAsExpr(0);
 575     std::optional<llvm::APSInt> ArgVal;
 576
 577     if (!(ArgVal = E->getIntegerConstantExpr(S.Context))) {
 578       S.Diag(A.getLoc(), diag::err_attribute_argument_type)
 579           << A << AANT_ArgumentIntegerConstant << E->getSourceRange();
 580       return nullptr;
 581     }
 582
 583     int Val = ArgVal->getSExtValue();
 584     if (Val <= 0) {
 585       S.Diag(A.getRange().getBegin(),
 586              diag::err_attribute_requires_positive_integer)
 587           << A << /* positive */ 0;
 588       return nullptr;
 589     }
 590     UnrollFactor = static_cast<unsigned>(Val);
 591   }
 592
 593   return ::new (S.Context) OpenCLUnrollHintAttr(S.Context, A, UnrollFactor);
 594 }
 595
 596 static Attr *handleHLSLLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
 597                                     SourceRange Range) {
 598
 599   if (A.getSemanticSpelling() == HLSLLoopHintAttr::Spelling::Microsoft_loop &&
 600       !A.checkAtMostNumArgs(S, 0))
 601     return nullptr;
 602
 603   unsigned UnrollFactor = 0;
 604   if (A.getNumArgs() == 1) {
 605     Expr *E = A.getArgAsExpr(0);
 606
 607     if (S.CheckLoopHintExpr(E, St->getBeginLoc(),
 608                             /*AllowZero=*/false))
 609       return nullptr;
 610
 611     std::optional<llvm::APSInt> ArgVal = E->getIntegerConstantExpr(S.Context);
 612     // CheckLoopHintExpr handles non int const cases
 613     assert(ArgVal != std::nullopt && "ArgVal should be an integer constant.");
 614     int Val = ArgVal->getSExtValue();
 615     // CheckLoopHintExpr handles negative and zero cases
 616     assert(Val > 0 && "Val should be a positive integer greater than zero.");
 617     UnrollFactor = static_cast<unsigned>(Val);
 618   }
 619   return ::new (S.Context) HLSLLoopHintAttr(S.Context, A, UnrollFactor);
 620 }
 621
 622 static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
 623                                   SourceRange Range) {
 624   if (A.isInvalid() || A.getKind() == ParsedAttr::IgnoredAttribute)
 625     return nullptr;
 626
 627   // Unknown attributes are automatically warned on. Target-specific attributes
 628   // which do not apply to the current target architecture are treated as
 629   // though they were unknown attributes.
 630   const TargetInfo *Aux = S.Context.getAuxTargetInfo();
 631   if (A.getKind() == ParsedAttr::UnknownAttribute ||
 632       !(A.existsInTarget(S.Context.getTargetInfo()) ||
 633         (S.Context.getLangOpts().SYCLIsDevice && Aux &&
 634          A.existsInTarget(*Aux)))) {
 635     S.Diag(A.getLoc(), A.isRegularKeywordAttribute()
 636                            ? (unsigned)diag::err_keyword_not_supported_on_target
 637                        : A.isDeclspecAttribute()
 638                            ? (unsigned)diag::warn_unhandled_ms_attribute_ignored
 639                            : (unsigned)diag::warn_unknown_attribute_ignored)
 640         << A << A.getRange();
 641     return nullptr;
 642   }
 643
 644   if (S.checkCommonAttributeFeatures(St, A))
 645     return nullptr;
 646
 647   switch (A.getKind()) {
 648   case ParsedAttr::AT_AlwaysInline:
 649     return handleAlwaysInlineAttr(S, St, A, Range);
 650   case ParsedAttr::AT_CXXAssume:
 651     return handleCXXAssumeAttr(S, St, A, Range);
 652   case ParsedAttr::AT_FallThrough:
 653     return handleFallThroughAttr(S, St, A, Range);
 654   case ParsedAttr::AT_LoopHint:
 655     return handleLoopHintAttr(S, St, A, Range);
 656   case ParsedAttr::AT_HLSLLoopHint:
 657     return handleHLSLLoopHintAttr(S, St, A, Range);
 658   case ParsedAttr::AT_OpenCLUnrollHint:
 659     return handleOpenCLUnrollHint(S, St, A, Range);
 660   case ParsedAttr::AT_Suppress:
 661     return handleSuppressAttr(S, St, A, Range);
 662   case ParsedAttr::AT_NoMerge:
 663     return handleNoMergeAttr(S, St, A, Range);
 664   case ParsedAttr::AT_NoInline:
 665     return handleNoInlineAttr(S, St, A, Range);
 666   case ParsedAttr::AT_MustTail:
 667     return handleMustTailAttr(S, St, A, Range);
 668   case ParsedAttr::AT_Likely:
 669     return handleLikely(S, St, A, Range);
 670   case ParsedAttr::AT_Unlikely:
 671     return handleUnlikely(S, St, A, Range);
 672   case ParsedAttr::AT_CodeAlign:
 673     return handleCodeAlignAttr(S, St, A);
 674   case ParsedAttr::AT_MSConstexpr:
 675     return handleMSConstexprAttr(S, St, A, Range);
 676   case ParsedAttr::AT_NoConvergent:
 677     return handleNoConvergentAttr(S, St, A, Range);
 678   case ParsedAttr::AT_Annotate:
 679     return S.CreateAnnotationAttr(A);
 680   default:
 681     if (Attr *AT = nullptr; A.getInfo().handleStmtAttribute(S, St, A, AT) !=
 682                             ParsedAttrInfo::NotHandled) {
 683       return AT;
 684     }
 685     // N.B., ClangAttrEmitter.cpp emits a diagnostic helper that ensures a
 686     // declaration attribute is not written on a statement, but this code is
 687     // needed for attributes in Attr.td that do not list any subjects.
 688     S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
 689         << A << A.isRegularKeywordAttribute() << St->getBeginLoc();
 690     return nullptr;
 691   }
 692 }
 693
 694 void Sema::ProcessStmtAttributes(Stmt *S, const ParsedAttributes &InAttrs,
 695                                  SmallVectorImpl<const Attr *> &OutAttrs) {
 696   for (const ParsedAttr &AL : InAttrs) {
 697     if (const Attr *A = ProcessStmtAttribute(*this, S, AL, InAttrs.Range))
 698       OutAttrs.push_back(A);
 699   }
 700
 701   CheckForIncompatibleAttributes(*this, OutAttrs);
 702   CheckForDuplicateLoopAttrs<CodeAlignAttr>(*this, OutAttrs);
 703 }
 704
 705 bool Sema::CheckRebuiltStmtAttributes(ArrayRef<const Attr *> Attrs) {
 706   CheckForDuplicateLoopAttrs<CodeAlignAttr>(*this, Attrs);
 707   return false;
 708 }
 709
 710 ExprResult Sema::ActOnCXXAssumeAttr(Stmt *St, const ParsedAttr &A,
 711                                     SourceRange Range) {
 712   if (A.getNumArgs() != 1 || !A.getArgAsExpr(0)) {
 713     Diag(A.getLoc(), diag::err_attribute_wrong_number_arguments)
 714         << A.getAttrName() << 1 << Range;
 715     return ExprError();
 716   }
 717
 718   auto *Assumption = A.getArgAsExpr(0);
 719
 720   if (DiagnoseUnexpandedParameterPack(Assumption)) {
 721     return ExprError();
 722   }
 723
 724   if (Assumption->getDependence() == ExprDependence::None) {
 725     ExprResult Res = BuildCXXAssumeExpr(Assumption, A.getAttrName(), Range);
 726     if (Res.isInvalid())
 727       return ExprError();
 728     Assumption = Res.get();
 729   }
 730
 731   if (!getLangOpts().CPlusPlus23 &&
 732       A.getSyntax() == AttributeCommonInfo::AS_CXX11)
 733     Diag(A.getLoc(), diag::ext_cxx23_attr) << A << Range;
 734
 735   return Assumption;
 736 }
 737
 738 ExprResult Sema::BuildCXXAssumeExpr(Expr *Assumption,
 739                                     const IdentifierInfo *AttrName,
 740                                     SourceRange Range) {
 741   ExprResult Res = CorrectDelayedTyposInExpr(Assumption);
 742   if (Res.isInvalid())
 743     return ExprError();
 744
 745   Res = CheckPlaceholderExpr(Res.get());
 746   if (Res.isInvalid())
 747     return ExprError();
 748
 749   Res = PerformContextuallyConvertToBool(Res.get());
 750   if (Res.isInvalid())
 751     return ExprError();
 752
 753   Assumption = Res.get();
 754   if (Assumption->HasSideEffects(Context))
 755     Diag(Assumption->getBeginLoc(), diag::warn_assume_side_effects)
 756         << AttrName << Range;
 757
 758   return Assumption;
 759 }