SemaStmtAttr.cpp revision ef8225444452a1486bd721f3285301fe84643b00 
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
14#include "clang/Sema/SemaInternal.h"
15#include "clang/AST/ASTContext.h"
16#include "clang/Basic/SourceManager.h"
17#include "clang/Sema/DelayedDiagnostic.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
23using namespace clang;
24using namespace sema;
25
26static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const AttributeList &A,
27                                   SourceRange Range) {
28  if (!isa<NullStmt>(St)) {
29    S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
30        << St->getLocStart();
31    if (isa<SwitchCase>(St)) {
32      SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
33      S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
34          << FixItHint::CreateInsertion(L, ";");
35    }
36    return nullptr;
37  }
38  if (S.getCurFunction()->SwitchStack.empty()) {
39    S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
40    return nullptr;
41  }
42  return ::new (S.Context) FallThroughAttr(A.getRange(), S.Context,
43                                           A.getAttributeSpellingListIndex());
44}
45
46static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const AttributeList &A,
47                                SourceRange) {
48  if (St->getStmtClass() != Stmt::DoStmtClass &&
49      St->getStmtClass() != Stmt::ForStmtClass &&
50      St->getStmtClass() != Stmt::CXXForRangeStmtClass &&
51      St->getStmtClass() != Stmt::WhileStmtClass) {
52    S.Diag(St->getLocStart(), diag::err_pragma_loop_precedes_nonloop);
53    return nullptr;
54  }
55
56  IdentifierLoc *OptionLoc = A.getArgAsIdent(0);
57  IdentifierInfo *OptionInfo = OptionLoc->Ident;
58  IdentifierLoc *ValueLoc = A.getArgAsIdent(1);
59  IdentifierInfo *ValueInfo = ValueLoc->Ident;
60  Expr *ValueExpr = A.getArgAsExpr(2);
61
62  assert(OptionInfo && "Attribute must have valid option info.");
63
64  LoopHintAttr::OptionType Option =
65      llvm::StringSwitch<LoopHintAttr::OptionType>(OptionInfo->getName())
66          .Case("vectorize", LoopHintAttr::Vectorize)
67          .Case("vectorize_width", LoopHintAttr::VectorizeWidth)
68          .Case("interleave", LoopHintAttr::Interleave)
69          .Case("interleave_count", LoopHintAttr::InterleaveCount)
70          .Case("unroll", LoopHintAttr::Unroll)
71          .Case("unroll_count", LoopHintAttr::UnrollCount)
72          .Default(LoopHintAttr::Vectorize);
73
74  int ValueInt;
75  if (Option == LoopHintAttr::Vectorize || Option == LoopHintAttr::Interleave ||
76      Option == LoopHintAttr::Unroll) {
77    if (!ValueInfo) {
78      S.Diag(ValueLoc->Loc, diag::err_pragma_loop_invalid_keyword);
79      return nullptr;
80    }
81    if (ValueInfo->isStr("disable"))
82      ValueInt = 0;
83    else if (ValueInfo->isStr("enable"))
84      ValueInt = 1;
85    else {
86      S.Diag(ValueLoc->Loc, diag::err_pragma_loop_invalid_keyword);
87      return nullptr;
88    }
89  } else if (Option == LoopHintAttr::VectorizeWidth ||
90             Option == LoopHintAttr::InterleaveCount ||
91             Option == LoopHintAttr::UnrollCount) {
92    // FIXME: We should support template parameters for the loop hint value.
93    // See bug report #19610.
94    llvm::APSInt ValueAPS;
95    if (!ValueExpr || !ValueExpr->isIntegerConstantExpr(ValueAPS, S.Context) ||
96        (ValueInt = ValueAPS.getSExtValue()) < 1) {
97      S.Diag(ValueLoc->Loc, diag::err_pragma_loop_invalid_value);
98      return nullptr;
99    }
100  } else
101    llvm_unreachable("Unknown loop hint option");
102
103  return LoopHintAttr::CreateImplicit(S.Context, Option, ValueInt,
104                                      A.getRange());
105}
106
107static void
108CheckForIncompatibleAttributes(Sema &S, SmallVectorImpl<const Attr *> &Attrs) {
109  // There are 3 categories of loop hints: vectorize, interleave, and
110  // unroll. Each comes in two variants: an enable/disable form and a
111  // form which takes a numeric argument. For example:
112  // unroll(enable|disable) and unroll_count(N). The following array
113  // accumulate the hints encountered while iterating through the
114  // attributes to check for compatibility.
115  struct {
116    int EnableOptionId;
117    int NumericOptionId;
118    bool EnabledIsSet;
119    bool ValueIsSet;
120    bool Enabled;
121    int Value;
122  } Options[] = {{LoopHintAttr::Vectorize, LoopHintAttr::VectorizeWidth, false,
123                  false, false, 0},
124                 {LoopHintAttr::Interleave, LoopHintAttr::InterleaveCount,
125                  false, false, false, 0},
126                 {LoopHintAttr::Unroll, LoopHintAttr::UnrollCount, false, false,
127                  false, 0}};
128
129  for (const auto *I : Attrs) {
130    const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
131
132    // Skip non loop hint attributes
133    if (!LH)
134      continue;
135
136    int Option = LH->getOption();
137    int ValueInt = LH->getValue();
138
139    int Category;
140    switch (Option) {
141    case LoopHintAttr::Vectorize:
142    case LoopHintAttr::VectorizeWidth:
143      Category = 0;
144      break;
145    case LoopHintAttr::Interleave:
146    case LoopHintAttr::InterleaveCount:
147      Category = 1;
148      break;
149    case LoopHintAttr::Unroll:
150    case LoopHintAttr::UnrollCount:
151      Category = 2;
152      break;
153    };
154
155    auto &CategoryState = Options[Category];
156    SourceLocation ValueLoc = LH->getRange().getEnd();
157    if (Option == LoopHintAttr::Vectorize ||
158        Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll) {
159      // Enable|disable hint.  For example, vectorize(enable).
160      if (CategoryState.EnabledIsSet) {
161        // Cannot specify enable/disable state twice.
162        S.Diag(ValueLoc, diag::err_pragma_loop_compatibility)
163            << /*Duplicate=*/true << LoopHintAttr::getOptionName(Option)
164            << LoopHintAttr::getValueName(CategoryState.Enabled)
165            << LoopHintAttr::getOptionName(Option)
166            << LoopHintAttr::getValueName(ValueInt);
167      }
168      CategoryState.EnabledIsSet = true;
169      CategoryState.Enabled = ValueInt;
170    } else {
171      // Numeric hint.  For example, unroll_count(8).
172      if (CategoryState.ValueIsSet) {
173        // Cannot specify numeric hint twice.
174        S.Diag(ValueLoc, diag::err_pragma_loop_compatibility)
175            << /*Duplicate=*/true << LoopHintAttr::getOptionName(Option)
176            << CategoryState.Value << LoopHintAttr::getOptionName(Option)
177            << ValueInt;
178      }
179      CategoryState.ValueIsSet = true;
180      CategoryState.Value = ValueInt;
181    }
182
183    if (CategoryState.EnabledIsSet && !CategoryState.Enabled &&
184        CategoryState.ValueIsSet) {
185      // Disable hints are not compatible with numeric hints of the
186      // same category.
187      S.Diag(ValueLoc, diag::err_pragma_loop_compatibility)
188          << /*Duplicate=*/false
189          << LoopHintAttr::getOptionName(CategoryState.EnableOptionId)
190          << LoopHintAttr::getValueName(CategoryState.Enabled)
191          << LoopHintAttr::getOptionName(CategoryState.NumericOptionId)
192          << CategoryState.Value;
193    }
194  }
195}
196
197static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const AttributeList &A,
198                                  SourceRange Range) {
199  switch (A.getKind()) {
200  case AttributeList::UnknownAttribute:
201    S.Diag(A.getLoc(), A.isDeclspecAttribute() ?
202           diag::warn_unhandled_ms_attribute_ignored :
203           diag::warn_unknown_attribute_ignored) << A.getName();
204    return nullptr;
205  case AttributeList::AT_FallThrough:
206    return handleFallThroughAttr(S, St, A, Range);
207  case AttributeList::AT_LoopHint:
208    return handleLoopHintAttr(S, St, A, Range);
209  default:
210    // if we're here, then we parsed a known attribute, but didn't recognize
211    // it as a statement attribute => it is declaration attribute
212    S.Diag(A.getRange().getBegin(), diag::err_attribute_invalid_on_stmt)
213        << A.getName() << St->getLocStart();
214    return nullptr;
215  }
216}
217
218StmtResult Sema::ProcessStmtAttributes(Stmt *S, AttributeList *AttrList,
219                                       SourceRange Range) {
220  SmallVector<const Attr*, 8> Attrs;
221  for (const AttributeList* l = AttrList; l; l = l->getNext()) {
222    if (Attr *a = ProcessStmtAttribute(*this, S, *l, Range))
223      Attrs.push_back(a);
224  }
225
226  CheckForIncompatibleAttributes(*this, Attrs);
227
228  if (Attrs.empty())
229    return S;
230
231  return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
232}
233