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/LoopHint.h"
20 #include "clang/Sema/ScopeInfo.h"
21 #include "llvm/ADT/StringExtras.h"
22 
23 using namespace clang;
24 using namespace sema;
25 
26 static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,
27  SourceRange Range) {
28  FallThroughAttr Attr(A.getRange(), S.Context,
30  if (!isa<NullStmt>(St)) {
31  S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
32  << Attr.getSpelling() << St->getBeginLoc();
33  if (isa<SwitchCase>(St)) {
35  S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
36  << FixItHint::CreateInsertion(L, ";");
37  }
38  return nullptr;
39  }
40  auto *FnScope = S.getCurFunction();
41  if (FnScope->SwitchStack.empty()) {
42  S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
43  return nullptr;
44  }
45 
46  // If this is spelled as the standard C++17 attribute, but not in C++17, warn
47  // about using it as an extension.
48  if (!S.getLangOpts().CPlusPlus17 && A.isCXX11Attribute() &&
49  !A.getScopeName())
50  S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A.getName();
51 
52  FnScope->setHasFallthroughStmt();
53  return ::new (S.Context) auto(Attr);
54 }
55 
56 static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
57  SourceRange Range) {
58  if (A.getNumArgs() < 1) {
59  S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;
60  return nullptr;
61  }
62 
63  std::vector<StringRef> DiagnosticIdentifiers;
64  for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
65  StringRef RuleName;
66 
67  if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
68  return nullptr;
69 
70  // FIXME: Warn if the rule name is unknown. This is tricky because only
71  // clang-tidy knows about available rules.
72  DiagnosticIdentifiers.push_back(RuleName);
73  }
74 
75  return ::new (S.Context) SuppressAttr(
76  A.getRange(), S.Context, DiagnosticIdentifiers.data(),
77  DiagnosticIdentifiers.size(), A.getAttributeSpellingListIndex());
78 }
79 
80 static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
81  SourceRange) {
82  IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
83  IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
84  IdentifierLoc *StateLoc = A.getArgAsIdent(2);
85  Expr *ValueExpr = A.getArgAsExpr(3);
86 
87  bool PragmaUnroll = PragmaNameLoc->Ident->getName() == "unroll";
88  bool PragmaNoUnroll = PragmaNameLoc->Ident->getName() == "nounroll";
89  bool PragmaUnrollAndJam = PragmaNameLoc->Ident->getName() == "unroll_and_jam";
90  bool PragmaNoUnrollAndJam =
91  PragmaNameLoc->Ident->getName() == "nounroll_and_jam";
92  if (St->getStmtClass() != Stmt::DoStmtClass &&
93  St->getStmtClass() != Stmt::ForStmtClass &&
94  St->getStmtClass() != Stmt::CXXForRangeStmtClass &&
95  St->getStmtClass() != Stmt::WhileStmtClass) {
96  const char *Pragma =
97  llvm::StringSwitch<const char *>(PragmaNameLoc->Ident->getName())
98  .Case("unroll", "#pragma unroll")
99  .Case("nounroll", "#pragma nounroll")
100  .Case("unroll_and_jam", "#pragma unroll_and_jam")
101  .Case("nounroll_and_jam", "#pragma nounroll_and_jam")
102  .Default("#pragma clang loop");
103  S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
104  return nullptr;
105  }
106 
107  LoopHintAttr::Spelling Spelling =
108  LoopHintAttr::Spelling(A.getAttributeSpellingListIndex());
109  LoopHintAttr::OptionType Option;
110  LoopHintAttr::LoopHintState State;
111  if (PragmaNoUnroll) {
112  // #pragma nounroll
113  Option = LoopHintAttr::Unroll;
114  State = LoopHintAttr::Disable;
115  } else if (PragmaUnroll) {
116  if (ValueExpr) {
117  // #pragma unroll N
118  Option = LoopHintAttr::UnrollCount;
119  State = LoopHintAttr::Numeric;
120  } else {
121  // #pragma unroll
122  Option = LoopHintAttr::Unroll;
123  State = LoopHintAttr::Enable;
124  }
125  } else if (PragmaNoUnrollAndJam) {
126  // #pragma nounroll_and_jam
127  Option = LoopHintAttr::UnrollAndJam;
128  State = LoopHintAttr::Disable;
129  } else if (PragmaUnrollAndJam) {
130  if (ValueExpr) {
131  // #pragma unroll_and_jam N
132  Option = LoopHintAttr::UnrollAndJamCount;
133  State = LoopHintAttr::Numeric;
134  } else {
135  // #pragma unroll_and_jam
136  Option = LoopHintAttr::UnrollAndJam;
137  State = LoopHintAttr::Enable;
138  }
139  } else {
140  // #pragma clang loop ...
141  assert(OptionLoc && OptionLoc->Ident &&
142  "Attribute must have valid option info.");
143  Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
144  OptionLoc->Ident->getName())
145  .Case("vectorize", LoopHintAttr::Vectorize)
146  .Case("vectorize_width", LoopHintAttr::VectorizeWidth)
147  .Case("interleave", LoopHintAttr::Interleave)
148  .Case("interleave_count", LoopHintAttr::InterleaveCount)
149  .Case("unroll", LoopHintAttr::Unroll)
150  .Case("unroll_count", LoopHintAttr::UnrollCount)
151  .Case("distribute", LoopHintAttr::Distribute)
152  .Default(LoopHintAttr::Vectorize);
153  if (Option == LoopHintAttr::VectorizeWidth ||
154  Option == LoopHintAttr::InterleaveCount ||
155  Option == LoopHintAttr::UnrollCount) {
156  assert(ValueExpr && "Attribute must have a valid value expression.");
157  if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
158  return nullptr;
159  State = LoopHintAttr::Numeric;
160  } else if (Option == LoopHintAttr::Vectorize ||
161  Option == LoopHintAttr::Interleave ||
162  Option == LoopHintAttr::Unroll ||
163  Option == LoopHintAttr::Distribute) {
164  assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
165  if (StateLoc->Ident->isStr("disable"))
166  State = LoopHintAttr::Disable;
167  else if (StateLoc->Ident->isStr("assume_safety"))
168  State = LoopHintAttr::AssumeSafety;
169  else if (StateLoc->Ident->isStr("full"))
170  State = LoopHintAttr::Full;
171  else if (StateLoc->Ident->isStr("enable"))
172  State = LoopHintAttr::Enable;
173  else
174  llvm_unreachable("bad loop hint argument");
175  } else
176  llvm_unreachable("bad loop hint");
177  }
178 
179  return LoopHintAttr::CreateImplicit(S.Context, Spelling, Option, State,
180  ValueExpr, A.getRange());
181 }
182 
183 static void
185  const SmallVectorImpl<const Attr *> &Attrs) {
186  // There are 5 categories of loop hints attributes: vectorize, interleave,
187  // unroll, unroll_and_jam and distribute. Except for distribute they come
188  // in two variants: a state form and a numeric form. The state form
189  // selectively defaults/enables/disables the transformation for the loop
190  // (for unroll, default indicates full unrolling rather than enabling the
191  // transformation). The numeric form form provides an integer hint (for
192  // example, unroll count) to the transformer. The following array accumulates
193  // the hints encountered while iterating through the attributes to check for
194  // compatibility.
195  struct {
196  const LoopHintAttr *StateAttr;
197  const LoopHintAttr *NumericAttr;
198  } HintAttrs[] = {{nullptr, nullptr},
199  {nullptr, nullptr},
200  {nullptr, nullptr},
201  {nullptr, nullptr},
202  {nullptr, nullptr}};
203 
204  for (const auto *I : Attrs) {
205  const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
206 
207  // Skip non loop hint attributes
208  if (!LH)
209  continue;
210 
211  LoopHintAttr::OptionType Option = LH->getOption();
212  enum { Vectorize, Interleave, Unroll, UnrollAndJam, Distribute } Category;
213  switch (Option) {
214  case LoopHintAttr::Vectorize:
215  case LoopHintAttr::VectorizeWidth:
216  Category = Vectorize;
217  break;
218  case LoopHintAttr::Interleave:
219  case LoopHintAttr::InterleaveCount:
220  Category = Interleave;
221  break;
222  case LoopHintAttr::Unroll:
223  case LoopHintAttr::UnrollCount:
224  Category = Unroll;
225  break;
226  case LoopHintAttr::UnrollAndJam:
227  case LoopHintAttr::UnrollAndJamCount:
228  Category = UnrollAndJam;
229  break;
230  case LoopHintAttr::Distribute:
231  // Perform the check for duplicated 'distribute' hints.
232  Category = Distribute;
233  break;
234  };
235 
236  assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
237  auto &CategoryState = HintAttrs[Category];
238  const LoopHintAttr *PrevAttr;
239  if (Option == LoopHintAttr::Vectorize ||
240  Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
241  Option == LoopHintAttr::UnrollAndJam ||
242  Option == LoopHintAttr::Distribute) {
243  // Enable|Disable|AssumeSafety hint. For example, vectorize(enable).
244  PrevAttr = CategoryState.StateAttr;
245  CategoryState.StateAttr = LH;
246  } else {
247  // Numeric hint. For example, vectorize_width(8).
248  PrevAttr = CategoryState.NumericAttr;
249  CategoryState.NumericAttr = LH;
250  }
251 
252  PrintingPolicy Policy(S.Context.getLangOpts());
253  SourceLocation OptionLoc = LH->getRange().getBegin();
254  if (PrevAttr)
255  // Cannot specify same type of attribute twice.
256  S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
257  << /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
258  << LH->getDiagnosticName(Policy);
259 
260  if (CategoryState.StateAttr && CategoryState.NumericAttr &&
261  (Category == Unroll || Category == UnrollAndJam ||
262  CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
263  // Disable hints are not compatible with numeric hints of the same
264  // category. As a special case, numeric unroll hints are also not
265  // compatible with enable or full form of the unroll pragma because these
266  // directives indicate full unrolling.
267  S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
268  << /*Duplicate=*/false
269  << CategoryState.StateAttr->getDiagnosticName(Policy)
270  << CategoryState.NumericAttr->getDiagnosticName(Policy);
271  }
272  }
273 }
274 
275 static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,
276  SourceRange Range) {
277  // Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's
278  // useful for OpenCL 1.x too and doesn't require HW support.
279  // opencl_unroll_hint can have 0 arguments (compiler
280  // determines unrolling factor) or 1 argument (the unroll factor provided
281  // by the user).
282 
283  unsigned NumArgs = A.getNumArgs();
284 
285  if (NumArgs > 1) {
286  S.Diag(A.getLoc(), diag::err_attribute_too_many_arguments) << A << 1;
287  return nullptr;
288  }
289 
290  unsigned UnrollFactor = 0;
291 
292  if (NumArgs == 1) {
293  Expr *E = A.getArgAsExpr(0);
294  llvm::APSInt ArgVal(32);
295 
296  if (!E->isIntegerConstantExpr(ArgVal, S.Context)) {
297  S.Diag(A.getLoc(), diag::err_attribute_argument_type)
299  return nullptr;
300  }
301 
302  int Val = ArgVal.getSExtValue();
303 
304  if (Val <= 0) {
305  S.Diag(A.getRange().getBegin(),
306  diag::err_attribute_requires_positive_integer)
307  << A << /* positive */ 0;
308  return nullptr;
309  }
310  UnrollFactor = Val;
311  }
312 
313  return OpenCLUnrollHintAttr::CreateImplicit(S.Context, UnrollFactor);
314 }
315 
316 static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
317  SourceRange Range) {
318  switch (A.getKind()) {
320  S.Diag(A.getLoc(), A.isDeclspecAttribute() ?
321  diag::warn_unhandled_ms_attribute_ignored :
322  diag::warn_unknown_attribute_ignored) << A.getName();
323  return nullptr;
324  case ParsedAttr::AT_FallThrough:
325  return handleFallThroughAttr(S, St, A, Range);
326  case ParsedAttr::AT_LoopHint:
327  return handleLoopHintAttr(S, St, A, Range);
328  case ParsedAttr::AT_OpenCLUnrollHint:
329  return handleOpenCLUnrollHint(S, St, A, Range);
330  case ParsedAttr::AT_Suppress:
331  return handleSuppressAttr(S, St, A, Range);
332  default:
333  // if we're here, then we parsed a known attribute, but didn't recognize
334  // it as a statement attribute => it is declaration attribute
335  S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
336  << A.getName() << St->getBeginLoc();
337  return nullptr;
338  }
339 }
340 
342  const ParsedAttributesView &AttrList,
343  SourceRange Range) {
345  for (const ParsedAttr &AL : AttrList) {
346  if (Attr *a = ProcessStmtAttribute(*this, S, AL, Range))
347  Attrs.push_back(a);
348  }
349 
350  CheckForIncompatibleAttributes(*this, Attrs);
351 
352  if (Attrs.empty())
353  return S;
354 
355  return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
356 }
Defines the clang::ASTContext interface.
const char * getSpelling() const
bool CheckLoopHintExpr(Expr *E, SourceLocation Loc)
Definition: SemaExpr.cpp:3201
bool isDeclspecAttribute() const
Definition: ParsedAttr.h:398
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:1290
IdentifierInfo * Ident
Definition: ParsedAttr.h:97
Expr * getArgAsExpr(unsigned Arg) const
Definition: ParsedAttr.h:455
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:401
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:141
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:280
int Category
Definition: Format.cpp:1623
unsigned getNumArgs() const
getNumArgs - Return the number of actual arguments to this attribute.
Definition: ParsedAttr.h:443
const LangOptions & getLangOpts() const
Definition: Sema.h:1213
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:105
Kind getKind() const
Definition: ParsedAttr.h:438
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:391
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:1340
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:268
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:716
IdentifierLoc * getArgAsIdent(unsigned Arg) const
Definition: ParsedAttr.h:463
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