clang  8.0.0svn
SemaStmtAttr.cpp
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1 //===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//
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 stmt-related attribute processing.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/AST/ASTContext.h"
18 #include "clang/Sema/Lookup.h"
19 #include "clang/Sema/ScopeInfo.h"
20 #include "llvm/ADT/StringExtras.h"
21 
22 using namespace clang;
23 using namespace sema;
24 
25 static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,
26  SourceRange Range) {
27  FallThroughAttr Attr(A.getRange(), S.Context,
29  if (!isa<NullStmt>(St)) {
30  S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
31  << Attr.getSpelling() << St->getBeginLoc();
32  if (isa<SwitchCase>(St)) {
34  S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
35  << FixItHint::CreateInsertion(L, ";");
36  }
37  return nullptr;
38  }
39  auto *FnScope = S.getCurFunction();
40  if (FnScope->SwitchStack.empty()) {
41  S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
42  return nullptr;
43  }
44 
45  // If this is spelled as the standard C++17 attribute, but not in C++17, warn
46  // about using it as an extension.
47  if (!S.getLangOpts().CPlusPlus17 && A.isCXX11Attribute() &&
48  !A.getScopeName())
49  S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A.getName();
50 
51  FnScope->setHasFallthroughStmt();
52  return ::new (S.Context) auto(Attr);
53 }
54 
55 static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
56  SourceRange Range) {
57  if (A.getNumArgs() < 1) {
58  S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;
59  return nullptr;
60  }
61 
62  std::vector<StringRef> DiagnosticIdentifiers;
63  for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
64  StringRef RuleName;
65 
66  if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
67  return nullptr;
68 
69  // FIXME: Warn if the rule name is unknown. This is tricky because only
70  // clang-tidy knows about available rules.
71  DiagnosticIdentifiers.push_back(RuleName);
72  }
73 
74  return ::new (S.Context) SuppressAttr(
75  A.getRange(), S.Context, DiagnosticIdentifiers.data(),
76  DiagnosticIdentifiers.size(), A.getAttributeSpellingListIndex());
77 }
78 
79 static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
80  SourceRange) {
81  IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
82  IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
83  IdentifierLoc *StateLoc = A.getArgAsIdent(2);
84  Expr *ValueExpr = A.getArgAsExpr(3);
85 
86  bool PragmaUnroll = PragmaNameLoc->Ident->getName() == "unroll";
87  bool PragmaNoUnroll = PragmaNameLoc->Ident->getName() == "nounroll";
88  bool PragmaUnrollAndJam = PragmaNameLoc->Ident->getName() == "unroll_and_jam";
89  bool PragmaNoUnrollAndJam =
90  PragmaNameLoc->Ident->getName() == "nounroll_and_jam";
91  if (St->getStmtClass() != Stmt::DoStmtClass &&
92  St->getStmtClass() != Stmt::ForStmtClass &&
93  St->getStmtClass() != Stmt::CXXForRangeStmtClass &&
94  St->getStmtClass() != Stmt::WhileStmtClass) {
95  const char *Pragma =
96  llvm::StringSwitch<const char *>(PragmaNameLoc->Ident->getName())
97  .Case("unroll", "#pragma unroll")
98  .Case("nounroll", "#pragma nounroll")
99  .Case("unroll_and_jam", "#pragma unroll_and_jam")
100  .Case("nounroll_and_jam", "#pragma nounroll_and_jam")
101  .Default("#pragma clang loop");
102  S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
103  return nullptr;
104  }
105 
106  LoopHintAttr::Spelling Spelling =
107  LoopHintAttr::Spelling(A.getAttributeSpellingListIndex());
108  LoopHintAttr::OptionType Option;
109  LoopHintAttr::LoopHintState State;
110  if (PragmaNoUnroll) {
111  // #pragma nounroll
112  Option = LoopHintAttr::Unroll;
113  State = LoopHintAttr::Disable;
114  } else if (PragmaUnroll) {
115  if (ValueExpr) {
116  // #pragma unroll N
117  Option = LoopHintAttr::UnrollCount;
118  State = LoopHintAttr::Numeric;
119  } else {
120  // #pragma unroll
121  Option = LoopHintAttr::Unroll;
122  State = LoopHintAttr::Enable;
123  }
124  } else if (PragmaNoUnrollAndJam) {
125  // #pragma nounroll_and_jam
126  Option = LoopHintAttr::UnrollAndJam;
127  State = LoopHintAttr::Disable;
128  } else if (PragmaUnrollAndJam) {
129  if (ValueExpr) {
130  // #pragma unroll_and_jam N
131  Option = LoopHintAttr::UnrollAndJamCount;
132  State = LoopHintAttr::Numeric;
133  } else {
134  // #pragma unroll_and_jam
135  Option = LoopHintAttr::UnrollAndJam;
136  State = LoopHintAttr::Enable;
137  }
138  } else {
139  // #pragma clang loop ...
140  assert(OptionLoc && OptionLoc->Ident &&
141  "Attribute must have valid option info.");
142  Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
143  OptionLoc->Ident->getName())
144  .Case("vectorize", LoopHintAttr::Vectorize)
145  .Case("vectorize_width", LoopHintAttr::VectorizeWidth)
146  .Case("interleave", LoopHintAttr::Interleave)
147  .Case("interleave_count", LoopHintAttr::InterleaveCount)
148  .Case("unroll", LoopHintAttr::Unroll)
149  .Case("unroll_count", LoopHintAttr::UnrollCount)
150  .Case("distribute", LoopHintAttr::Distribute)
151  .Default(LoopHintAttr::Vectorize);
152  if (Option == LoopHintAttr::VectorizeWidth ||
153  Option == LoopHintAttr::InterleaveCount ||
154  Option == LoopHintAttr::UnrollCount) {
155  assert(ValueExpr && "Attribute must have a valid value expression.");
156  if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
157  return nullptr;
158  State = LoopHintAttr::Numeric;
159  } else if (Option == LoopHintAttr::Vectorize ||
160  Option == LoopHintAttr::Interleave ||
161  Option == LoopHintAttr::Unroll ||
162  Option == LoopHintAttr::Distribute) {
163  assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
164  if (StateLoc->Ident->isStr("disable"))
165  State = LoopHintAttr::Disable;
166  else if (StateLoc->Ident->isStr("assume_safety"))
167  State = LoopHintAttr::AssumeSafety;
168  else if (StateLoc->Ident->isStr("full"))
169  State = LoopHintAttr::Full;
170  else if (StateLoc->Ident->isStr("enable"))
171  State = LoopHintAttr::Enable;
172  else
173  llvm_unreachable("bad loop hint argument");
174  } else
175  llvm_unreachable("bad loop hint");
176  }
177 
178  return LoopHintAttr::CreateImplicit(S.Context, Spelling, Option, State,
179  ValueExpr, A.getRange());
180 }
181 
182 static void
184  const SmallVectorImpl<const Attr *> &Attrs) {
185  // There are 5 categories of loop hints attributes: vectorize, interleave,
186  // unroll, unroll_and_jam and distribute. Except for distribute they come
187  // in two variants: a state form and a numeric form. The state form
188  // selectively defaults/enables/disables the transformation for the loop
189  // (for unroll, default indicates full unrolling rather than enabling the
190  // transformation). The numeric form form provides an integer hint (for
191  // example, unroll count) to the transformer. The following array accumulates
192  // the hints encountered while iterating through the attributes to check for
193  // compatibility.
194  struct {
195  const LoopHintAttr *StateAttr;
196  const LoopHintAttr *NumericAttr;
197  } HintAttrs[] = {{nullptr, nullptr},
198  {nullptr, nullptr},
199  {nullptr, nullptr},
200  {nullptr, nullptr},
201  {nullptr, nullptr}};
202 
203  for (const auto *I : Attrs) {
204  const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
205 
206  // Skip non loop hint attributes
207  if (!LH)
208  continue;
209 
210  LoopHintAttr::OptionType Option = LH->getOption();
211  enum { Vectorize, Interleave, Unroll, UnrollAndJam, Distribute } Category;
212  switch (Option) {
213  case LoopHintAttr::Vectorize:
214  case LoopHintAttr::VectorizeWidth:
215  Category = Vectorize;
216  break;
217  case LoopHintAttr::Interleave:
218  case LoopHintAttr::InterleaveCount:
219  Category = Interleave;
220  break;
221  case LoopHintAttr::Unroll:
222  case LoopHintAttr::UnrollCount:
223  Category = Unroll;
224  break;
225  case LoopHintAttr::UnrollAndJam:
226  case LoopHintAttr::UnrollAndJamCount:
227  Category = UnrollAndJam;
228  break;
229  case LoopHintAttr::Distribute:
230  // Perform the check for duplicated 'distribute' hints.
231  Category = Distribute;
232  break;
233  };
234 
235  assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
236  auto &CategoryState = HintAttrs[Category];
237  const LoopHintAttr *PrevAttr;
238  if (Option == LoopHintAttr::Vectorize ||
239  Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
240  Option == LoopHintAttr::UnrollAndJam ||
241  Option == LoopHintAttr::Distribute) {
242  // Enable|Disable|AssumeSafety hint. For example, vectorize(enable).
243  PrevAttr = CategoryState.StateAttr;
244  CategoryState.StateAttr = LH;
245  } else {
246  // Numeric hint. For example, vectorize_width(8).
247  PrevAttr = CategoryState.NumericAttr;
248  CategoryState.NumericAttr = LH;
249  }
250 
251  PrintingPolicy Policy(S.Context.getLangOpts());
252  SourceLocation OptionLoc = LH->getRange().getBegin();
253  if (PrevAttr)
254  // Cannot specify same type of attribute twice.
255  S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
256  << /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
257  << LH->getDiagnosticName(Policy);
258 
259  if (CategoryState.StateAttr && CategoryState.NumericAttr &&
260  (Category == Unroll || Category == UnrollAndJam ||
261  CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
262  // Disable hints are not compatible with numeric hints of the same
263  // category. As a special case, numeric unroll hints are also not
264  // compatible with enable or full form of the unroll pragma because these
265  // directives indicate full unrolling.
266  S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
267  << /*Duplicate=*/false
268  << CategoryState.StateAttr->getDiagnosticName(Policy)
269  << CategoryState.NumericAttr->getDiagnosticName(Policy);
270  }
271  }
272 }
273 
274 static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,
275  SourceRange Range) {
276  // Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's
277  // useful for OpenCL 1.x too and doesn't require HW support.
278  // opencl_unroll_hint can have 0 arguments (compiler
279  // determines unrolling factor) or 1 argument (the unroll factor provided
280  // by the user).
281 
282  unsigned NumArgs = A.getNumArgs();
283 
284  if (NumArgs > 1) {
285  S.Diag(A.getLoc(), diag::err_attribute_too_many_arguments) << A << 1;
286  return nullptr;
287  }
288 
289  unsigned UnrollFactor = 0;
290 
291  if (NumArgs == 1) {
292  Expr *E = A.getArgAsExpr(0);
293  llvm::APSInt ArgVal(32);
294 
295  if (!E->isIntegerConstantExpr(ArgVal, S.Context)) {
296  S.Diag(A.getLoc(), diag::err_attribute_argument_type)
298  return nullptr;
299  }
300 
301  int Val = ArgVal.getSExtValue();
302 
303  if (Val <= 0) {
304  S.Diag(A.getRange().getBegin(),
305  diag::err_attribute_requires_positive_integer)
306  << A << /* positive */ 0;
307  return nullptr;
308  }
309  UnrollFactor = Val;
310  }
311 
312  return OpenCLUnrollHintAttr::CreateImplicit(S.Context, UnrollFactor);
313 }
314 
315 static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
316  SourceRange Range) {
317  switch (A.getKind()) {
319  S.Diag(A.getLoc(), A.isDeclspecAttribute() ?
320  diag::warn_unhandled_ms_attribute_ignored :
321  diag::warn_unknown_attribute_ignored) << A.getName();
322  return nullptr;
323  case ParsedAttr::AT_FallThrough:
324  return handleFallThroughAttr(S, St, A, Range);
325  case ParsedAttr::AT_LoopHint:
326  return handleLoopHintAttr(S, St, A, Range);
327  case ParsedAttr::AT_OpenCLUnrollHint:
328  return handleOpenCLUnrollHint(S, St, A, Range);
329  case ParsedAttr::AT_Suppress:
330  return handleSuppressAttr(S, St, A, Range);
331  default:
332  // if we're here, then we parsed a known attribute, but didn't recognize
333  // it as a statement attribute => it is declaration attribute
334  S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
335  << A.getName() << St->getBeginLoc();
336  return nullptr;
337  }
338 }
339 
341  const ParsedAttributesView &AttrList,
342  SourceRange Range) {
344  for (const ParsedAttr &AL : AttrList) {
345  if (Attr *a = ProcessStmtAttribute(*this, S, AL, Range))
346  Attrs.push_back(a);
347  }
348 
349  CheckForIncompatibleAttributes(*this, Attrs);
350 
351  if (Attrs.empty())
352  return S;
353 
354  return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
355 }
Defines the clang::ASTContext interface.
const char * getSpelling() const
bool CheckLoopHintExpr(Expr *E, SourceLocation Loc)
Definition: SemaExpr.cpp:3240
bool isDeclspecAttribute() const
Definition: ParsedAttr.h:403
static void CheckForIncompatibleAttributes(Sema &S, const SmallVectorImpl< const Attr *> &Attrs)
Stmt - This represents one statement.
Definition: Stmt.h:66
Defines the SourceManager interface.
SemaDiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID)
Emit a diagnostic.
Definition: Sema.h:1302
IdentifierInfo * Ident
Definition: ParsedAttr.h:97
Expr * getArgAsExpr(unsigned Arg) const
Definition: ParsedAttr.h:460
SourceLocation getLocForEndOfToken(SourceLocation Loc, unsigned Offset=0)
Calls Lexer::getLocForEndOfToken()
Definition: Sema.cpp:46
static Attr * handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A, SourceRange Range)
bool isCXX11Attribute() const
Definition: ParsedAttr.h:406
Describes how types, statements, expressions, and declarations should be printed. ...
Definition: PrettyPrinter.h:38
unsigned getAttributeSpellingListIndex() const
Get an index into the attribute spelling list defined in Attr.td.
Definition: ParsedAttr.cpp:157
bool isStr(const char(&Str)[StrLen]) const
Return true if this is the identifier for the specified string.
LineState State
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Stmt.cpp:288
int Category
Definition: Format.cpp:1632
unsigned getNumArgs() const
getNumArgs - Return the number of actual arguments to this attribute.
Definition: ParsedAttr.h:448
const LangOptions & getLangOpts() const
Definition: Sema.h:1225
Sema - This implements semantic analysis and AST building for C.
Definition: Sema.h:278
static Attr * handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A, SourceRange Range)
This represents one expression.
Definition: Expr.h:106
Kind getKind() const
Definition: ParsedAttr.h:443
Defines the classes clang::DelayedDiagnostic and clang::AccessedEntity.
SourceLocation getEnd() const
Wraps an identifier and optional source location for the identifier.
Definition: ParsedAttr.h:95
static Attr * ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A, SourceRange Range)
ActionResult - This structure is used while parsing/acting on expressions, stmts, etc...
Definition: Ownership.h:157
Encodes a location in the source.
ParsedAttr - Represents a syntactic attribute.
Definition: ParsedAttr.h:117
SourceRange getRange() const
Definition: ParsedAttr.h:380
StringRef getName() const
Return the actual identifier string.
Dataflow Directional Tag Classes.
StmtClass getStmtClass() const
Definition: Stmt.h:812
SourceLocation getLoc() const
Definition: ParsedAttr.h:379
bool isIntegerConstantExpr(llvm::APSInt &Result, const ASTContext &Ctx, SourceLocation *Loc=nullptr, bool isEvaluated=true) const
isIntegerConstantExpr - Return true if this expression is a valid integer constant expression...
IdentifierInfo * getName() const
Definition: ParsedAttr.h:378
static FixItHint CreateInsertion(SourceLocation InsertionLoc, StringRef Code, bool BeforePreviousInsertions=false)
Create a code modification hint that inserts the given code string at a specific location.
Definition: Diagnostic.h:92
StmtResult ProcessStmtAttributes(Stmt *Stmt, const ParsedAttributesView &Attrs, SourceRange Range)
Stmt attributes - this routine is the top level dispatcher.
sema::FunctionScopeInfo * getCurFunction() const
Definition: Sema.h:1352
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:276
static Attr * handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A, SourceRange Range)
bool checkStringLiteralArgumentAttr(const ParsedAttr &Attr, unsigned ArgNum, StringRef &Str, SourceLocation *ArgLocation=nullptr)
Check if the argument ArgNum of Attr is a ASCII string literal.
A trivial tuple used to represent a source range.
ASTContext & Context
Definition: Sema.h:320
SourceLocation getBegin() const
const LangOptions & getLangOpts() const
Definition: ASTContext.h:706
IdentifierLoc * getArgAsIdent(unsigned Arg) const
Definition: ParsedAttr.h:468
static Attr * handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A, SourceRange)
Attr - This represents one attribute.
Definition: Attr.h:43
IdentifierInfo * getScopeName() const
Definition: ParsedAttr.h:383