1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
|
//===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements stmt-related attribute processing.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTContext.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Sema/DelayedDiagnostic.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/StringExtras.h"
using namespace clang;
using namespace sema;
static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
FallThroughAttr Attr(S.Context, A);
if (isa<SwitchCase>(St)) {
S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)
<< A << St->getBeginLoc();
SourceLocation L = S.getLocForEndOfToken(Range.getEnd());
S.Diag(L, diag::note_fallthrough_insert_semi_fixit)
<< FixItHint::CreateInsertion(L, ";");
return nullptr;
}
auto *FnScope = S.getCurFunction();
if (FnScope->SwitchStack.empty()) {
S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);
return nullptr;
}
// If this is spelled as the standard C++17 attribute, but not in C++17, warn
// about using it as an extension.
if (!S.getLangOpts().CPlusPlus17 && A.isCXX11Attribute() &&
!A.getScopeName())
S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A;
FnScope->setHasFallthroughStmt();
return ::new (S.Context) FallThroughAttr(S.Context, A);
}
static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
std::vector<StringRef> DiagnosticIdentifiers;
for (unsigned I = 0, E = A.getNumArgs(); I != E; ++I) {
StringRef RuleName;
if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))
return nullptr;
// FIXME: Warn if the rule name is unknown. This is tricky because only
// clang-tidy knows about available rules.
DiagnosticIdentifiers.push_back(RuleName);
}
return ::new (S.Context) SuppressAttr(
S.Context, A, DiagnosticIdentifiers.data(), DiagnosticIdentifiers.size());
}
static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange) {
IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);
IdentifierLoc *OptionLoc = A.getArgAsIdent(1);
IdentifierLoc *StateLoc = A.getArgAsIdent(2);
Expr *ValueExpr = A.getArgAsExpr(3);
StringRef PragmaName =
llvm::StringSwitch<StringRef>(PragmaNameLoc->Ident->getName())
.Cases("unroll", "nounroll", "unroll_and_jam", "nounroll_and_jam",
PragmaNameLoc->Ident->getName())
.Default("clang loop");
// This could be handled automatically by adding a Subjects definition in
// Attr.td, but that would make the diagnostic behavior worse in this case
// because the user spells this attribute as a pragma.
if (!isa<DoStmt, ForStmt, CXXForRangeStmt, WhileStmt>(St)) {
std::string Pragma = "#pragma " + std::string(PragmaName);
S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;
return nullptr;
}
LoopHintAttr::OptionType Option;
LoopHintAttr::LoopHintState State;
auto SetHints = [&Option, &State](LoopHintAttr::OptionType O,
LoopHintAttr::LoopHintState S) {
Option = O;
State = S;
};
if (PragmaName == "nounroll") {
SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);
} else if (PragmaName == "unroll") {
// #pragma unroll N
if (ValueExpr)
SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
else
SetHints(LoopHintAttr::Unroll, LoopHintAttr::Enable);
} else if (PragmaName == "nounroll_and_jam") {
SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Disable);
} else if (PragmaName == "unroll_and_jam") {
// #pragma unroll_and_jam N
if (ValueExpr)
SetHints(LoopHintAttr::UnrollAndJamCount, LoopHintAttr::Numeric);
else
SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Enable);
} else {
// #pragma clang loop ...
assert(OptionLoc && OptionLoc->Ident &&
"Attribute must have valid option info.");
Option = llvm::StringSwitch<LoopHintAttr::OptionType>(
OptionLoc->Ident->getName())
.Case("vectorize", LoopHintAttr::Vectorize)
.Case("vectorize_width", LoopHintAttr::VectorizeWidth)
.Case("interleave", LoopHintAttr::Interleave)
.Case("vectorize_predicate", LoopHintAttr::VectorizePredicate)
.Case("interleave_count", LoopHintAttr::InterleaveCount)
.Case("unroll", LoopHintAttr::Unroll)
.Case("unroll_count", LoopHintAttr::UnrollCount)
.Case("pipeline", LoopHintAttr::PipelineDisabled)
.Case("pipeline_initiation_interval",
LoopHintAttr::PipelineInitiationInterval)
.Case("distribute", LoopHintAttr::Distribute)
.Default(LoopHintAttr::Vectorize);
if (Option == LoopHintAttr::VectorizeWidth) {
assert((ValueExpr || (StateLoc && StateLoc->Ident)) &&
"Attribute must have a valid value expression or argument.");
if (ValueExpr && S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
return nullptr;
if (StateLoc && StateLoc->Ident && StateLoc->Ident->isStr("scalable"))
State = LoopHintAttr::ScalableWidth;
else
State = LoopHintAttr::FixedWidth;
} else if (Option == LoopHintAttr::InterleaveCount ||
Option == LoopHintAttr::UnrollCount ||
Option == LoopHintAttr::PipelineInitiationInterval) {
assert(ValueExpr && "Attribute must have a valid value expression.");
if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
return nullptr;
State = LoopHintAttr::Numeric;
} else if (Option == LoopHintAttr::Vectorize ||
Option == LoopHintAttr::Interleave ||
Option == LoopHintAttr::VectorizePredicate ||
Option == LoopHintAttr::Unroll ||
Option == LoopHintAttr::Distribute ||
Option == LoopHintAttr::PipelineDisabled) {
assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");
if (StateLoc->Ident->isStr("disable"))
State = LoopHintAttr::Disable;
else if (StateLoc->Ident->isStr("assume_safety"))
State = LoopHintAttr::AssumeSafety;
else if (StateLoc->Ident->isStr("full"))
State = LoopHintAttr::Full;
else if (StateLoc->Ident->isStr("enable"))
State = LoopHintAttr::Enable;
else
llvm_unreachable("bad loop hint argument");
} else
llvm_unreachable("bad loop hint");
}
return LoopHintAttr::CreateImplicit(S.Context, Option, State, ValueExpr, A);
}
namespace {
class CallExprFinder : public ConstEvaluatedExprVisitor<CallExprFinder> {
bool FoundAsmStmt = false;
std::vector<const CallExpr *> CallExprs;
public:
typedef ConstEvaluatedExprVisitor<CallExprFinder> Inherited;
CallExprFinder(Sema &S, const Stmt *St) : Inherited(S.Context) { Visit(St); }
bool foundCallExpr() { return !CallExprs.empty(); }
const std::vector<const CallExpr *> &getCallExprs() { return CallExprs; }
bool foundAsmStmt() { return FoundAsmStmt; }
void VisitCallExpr(const CallExpr *E) { CallExprs.push_back(E); }
void VisitAsmStmt(const AsmStmt *S) { FoundAsmStmt = true; }
void Visit(const Stmt *St) {
if (!St)
return;
ConstEvaluatedExprVisitor<CallExprFinder>::Visit(St);
}
};
} // namespace
static Attr *handleNoMergeAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
NoMergeAttr NMA(S.Context, A);
CallExprFinder CEF(S, St);
if (!CEF.foundCallExpr() && !CEF.foundAsmStmt()) {
S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
<< A;
return nullptr;
}
return ::new (S.Context) NoMergeAttr(S.Context, A);
}
static Attr *handleNoInlineAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
NoInlineAttr NIA(S.Context, A);
if (!NIA.isClangNoInline()) {
S.Diag(St->getBeginLoc(), diag::warn_function_attribute_ignored_in_stmt)
<< "[[clang::noinline]]";
return nullptr;
}
CallExprFinder CEF(S, St);
if (!CEF.foundCallExpr()) {
S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
<< A;
return nullptr;
}
for (const auto *CallExpr : CEF.getCallExprs()) {
const Decl *Decl = CallExpr->getCalleeDecl();
if (Decl->hasAttr<AlwaysInlineAttr>() || Decl->hasAttr<FlattenAttr>())
S.Diag(St->getBeginLoc(), diag::warn_function_stmt_attribute_precedence)
<< A << (Decl->hasAttr<AlwaysInlineAttr>() ? 0 : 1);
}
return ::new (S.Context) NoInlineAttr(S.Context, A);
}
static Attr *handleAlwaysInlineAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
AlwaysInlineAttr AIA(S.Context, A);
if (!AIA.isClangAlwaysInline()) {
S.Diag(St->getBeginLoc(), diag::warn_function_attribute_ignored_in_stmt)
<< "[[clang::always_inline]]";
return nullptr;
}
CallExprFinder CEF(S, St);
if (!CEF.foundCallExpr()) {
S.Diag(St->getBeginLoc(), diag::warn_attribute_ignored_no_calls_in_stmt)
<< A;
return nullptr;
}
for (const auto *CallExpr : CEF.getCallExprs()) {
const Decl *Decl = CallExpr->getCalleeDecl();
if (Decl->hasAttr<NoInlineAttr>() || Decl->hasAttr<FlattenAttr>())
S.Diag(St->getBeginLoc(), diag::warn_function_stmt_attribute_precedence)
<< A << (Decl->hasAttr<NoInlineAttr>() ? 2 : 1);
}
return ::new (S.Context) AlwaysInlineAttr(S.Context, A);
}
static Attr *handleMustTailAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
// Validation is in Sema::ActOnAttributedStmt().
return ::new (S.Context) MustTailAttr(S.Context, A);
}
static Attr *handleLikely(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
return ::new (S.Context) LikelyAttr(S.Context, A);
}
static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;
return ::new (S.Context) UnlikelyAttr(S.Context, A);
}
#define WANT_STMT_MERGE_LOGIC
#include "clang/Sema/AttrParsedAttrImpl.inc"
#undef WANT_STMT_MERGE_LOGIC
static void
CheckForIncompatibleAttributes(Sema &S,
const SmallVectorImpl<const Attr *> &Attrs) {
// The vast majority of attributed statements will only have one attribute
// on them, so skip all of the checking in the common case.
if (Attrs.size() < 2)
return;
// First, check for the easy cases that are table-generated for us.
if (!DiagnoseMutualExclusions(S, Attrs))
return;
// There are 6 categories of loop hints attributes: vectorize, interleave,
// unroll, unroll_and_jam, pipeline and distribute. Except for distribute they
// come in two variants: a state form and a numeric form. The state form
// selectively defaults/enables/disables the transformation for the loop
// (for unroll, default indicates full unrolling rather than enabling the
// transformation). The numeric form form provides an integer hint (for
// example, unroll count) to the transformer. The following array accumulates
// the hints encountered while iterating through the attributes to check for
// compatibility.
struct {
const LoopHintAttr *StateAttr;
const LoopHintAttr *NumericAttr;
} HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},
{nullptr, nullptr}};
for (const auto *I : Attrs) {
const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);
// Skip non loop hint attributes
if (!LH)
continue;
LoopHintAttr::OptionType Option = LH->getOption();
enum {
Vectorize,
Interleave,
Unroll,
UnrollAndJam,
Distribute,
Pipeline,
VectorizePredicate
} Category;
switch (Option) {
case LoopHintAttr::Vectorize:
case LoopHintAttr::VectorizeWidth:
Category = Vectorize;
break;
case LoopHintAttr::Interleave:
case LoopHintAttr::InterleaveCount:
Category = Interleave;
break;
case LoopHintAttr::Unroll:
case LoopHintAttr::UnrollCount:
Category = Unroll;
break;
case LoopHintAttr::UnrollAndJam:
case LoopHintAttr::UnrollAndJamCount:
Category = UnrollAndJam;
break;
case LoopHintAttr::Distribute:
// Perform the check for duplicated 'distribute' hints.
Category = Distribute;
break;
case LoopHintAttr::PipelineDisabled:
case LoopHintAttr::PipelineInitiationInterval:
Category = Pipeline;
break;
case LoopHintAttr::VectorizePredicate:
Category = VectorizePredicate;
break;
};
assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));
auto &CategoryState = HintAttrs[Category];
const LoopHintAttr *PrevAttr;
if (Option == LoopHintAttr::Vectorize ||
Option == LoopHintAttr::Interleave || Option == LoopHintAttr::Unroll ||
Option == LoopHintAttr::UnrollAndJam ||
Option == LoopHintAttr::VectorizePredicate ||
Option == LoopHintAttr::PipelineDisabled ||
Option == LoopHintAttr::Distribute) {
// Enable|Disable|AssumeSafety hint. For example, vectorize(enable).
PrevAttr = CategoryState.StateAttr;
CategoryState.StateAttr = LH;
} else {
// Numeric hint. For example, vectorize_width(8).
PrevAttr = CategoryState.NumericAttr;
CategoryState.NumericAttr = LH;
}
PrintingPolicy Policy(S.Context.getLangOpts());
SourceLocation OptionLoc = LH->getRange().getBegin();
if (PrevAttr)
// Cannot specify same type of attribute twice.
S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
<< /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)
<< LH->getDiagnosticName(Policy);
if (CategoryState.StateAttr && CategoryState.NumericAttr &&
(Category == Unroll || Category == UnrollAndJam ||
CategoryState.StateAttr->getState() == LoopHintAttr::Disable)) {
// Disable hints are not compatible with numeric hints of the same
// category. As a special case, numeric unroll hints are also not
// compatible with enable or full form of the unroll pragma because these
// directives indicate full unrolling.
S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)
<< /*Duplicate=*/false
<< CategoryState.StateAttr->getDiagnosticName(Policy)
<< CategoryState.NumericAttr->getDiagnosticName(Policy);
}
}
}
static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
// Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's
// useful for OpenCL 1.x too and doesn't require HW support.
// opencl_unroll_hint can have 0 arguments (compiler
// determines unrolling factor) or 1 argument (the unroll factor provided
// by the user).
unsigned UnrollFactor = 0;
if (A.getNumArgs() == 1) {
Expr *E = A.getArgAsExpr(0);
Optional<llvm::APSInt> ArgVal;
if (!(ArgVal = E->getIntegerConstantExpr(S.Context))) {
S.Diag(A.getLoc(), diag::err_attribute_argument_type)
<< A << AANT_ArgumentIntegerConstant << E->getSourceRange();
return nullptr;
}
int Val = ArgVal->getSExtValue();
if (Val <= 0) {
S.Diag(A.getRange().getBegin(),
diag::err_attribute_requires_positive_integer)
<< A << /* positive */ 0;
return nullptr;
}
UnrollFactor = static_cast<unsigned>(Val);
}
return ::new (S.Context) OpenCLUnrollHintAttr(S.Context, A, UnrollFactor);
}
static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,
SourceRange Range) {
if (A.isInvalid() || A.getKind() == ParsedAttr::IgnoredAttribute)
return nullptr;
// Unknown attributes are automatically warned on. Target-specific attributes
// which do not apply to the current target architecture are treated as
// though they were unknown attributes.
const TargetInfo *Aux = S.Context.getAuxTargetInfo();
if (A.getKind() == ParsedAttr::UnknownAttribute ||
!(A.existsInTarget(S.Context.getTargetInfo()) ||
(S.Context.getLangOpts().SYCLIsDevice && Aux &&
A.existsInTarget(*Aux)))) {
S.Diag(A.getLoc(), A.isDeclspecAttribute()
? (unsigned)diag::warn_unhandled_ms_attribute_ignored
: (unsigned)diag::warn_unknown_attribute_ignored)
<< A << A.getRange();
return nullptr;
}
if (S.checkCommonAttributeFeatures(St, A))
return nullptr;
switch (A.getKind()) {
case ParsedAttr::AT_AlwaysInline:
return handleAlwaysInlineAttr(S, St, A, Range);
case ParsedAttr::AT_FallThrough:
return handleFallThroughAttr(S, St, A, Range);
case ParsedAttr::AT_LoopHint:
return handleLoopHintAttr(S, St, A, Range);
case ParsedAttr::AT_OpenCLUnrollHint:
return handleOpenCLUnrollHint(S, St, A, Range);
case ParsedAttr::AT_Suppress:
return handleSuppressAttr(S, St, A, Range);
case ParsedAttr::AT_NoMerge:
return handleNoMergeAttr(S, St, A, Range);
case ParsedAttr::AT_NoInline:
return handleNoInlineAttr(S, St, A, Range);
case ParsedAttr::AT_MustTail:
return handleMustTailAttr(S, St, A, Range);
case ParsedAttr::AT_Likely:
return handleLikely(S, St, A, Range);
case ParsedAttr::AT_Unlikely:
return handleUnlikely(S, St, A, Range);
default:
// N.B., ClangAttrEmitter.cpp emits a diagnostic helper that ensures a
// declaration attribute is not written on a statement, but this code is
// needed for attributes in Attr.td that do not list any subjects.
S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
<< A << St->getBeginLoc();
return nullptr;
}
}
void Sema::ProcessStmtAttributes(Stmt *S, const ParsedAttributes &InAttrs,
SmallVectorImpl<const Attr *> &OutAttrs) {
for (const ParsedAttr &AL : InAttrs) {
if (const Attr *A = ProcessStmtAttribute(*this, S, AL, InAttrs.Range))
OutAttrs.push_back(A);
}
CheckForIncompatibleAttributes(*this, OutAttrs);
}
|