Bug Summary

File:build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/clang/lib/AST/RecordLayoutBuilder.cpp
Warning:line 1181, column 10
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name RecordLayoutBuilder.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm -resource-dir /usr/lib/llvm-16/lib/clang/16.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/clang/lib/AST -I /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/clang/include -I tools/clang/include -I include -I /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-16/lib/clang/16.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fmacro-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-09-04-125545-48738-1 -x c++ /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/clang/lib/AST/RecordLayoutBuilder.cpp
1//=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
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#include "clang/AST/ASTContext.h"
10#include "clang/AST/ASTDiagnostic.h"
11#include "clang/AST/Attr.h"
12#include "clang/AST/CXXInheritance.h"
13#include "clang/AST/Decl.h"
14#include "clang/AST/DeclCXX.h"
15#include "clang/AST/DeclObjC.h"
16#include "clang/AST/Expr.h"
17#include "clang/AST/VTableBuilder.h"
18#include "clang/AST/RecordLayout.h"
19#include "clang/Basic/TargetInfo.h"
20#include "llvm/ADT/SmallSet.h"
21#include "llvm/Support/Format.h"
22#include "llvm/Support/MathExtras.h"
23
24using namespace clang;
25
26namespace {
27
28/// BaseSubobjectInfo - Represents a single base subobject in a complete class.
29/// For a class hierarchy like
30///
31/// class A { };
32/// class B : A { };
33/// class C : A, B { };
34///
35/// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
36/// instances, one for B and two for A.
37///
38/// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
39struct BaseSubobjectInfo {
40 /// Class - The class for this base info.
41 const CXXRecordDecl *Class;
42
43 /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
44 bool IsVirtual;
45
46 /// Bases - Information about the base subobjects.
47 SmallVector<BaseSubobjectInfo*, 4> Bases;
48
49 /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
50 /// of this base info (if one exists).
51 BaseSubobjectInfo *PrimaryVirtualBaseInfo;
52
53 // FIXME: Document.
54 const BaseSubobjectInfo *Derived;
55};
56
57/// Externally provided layout. Typically used when the AST source, such
58/// as DWARF, lacks all the information that was available at compile time, such
59/// as alignment attributes on fields and pragmas in effect.
60struct ExternalLayout {
61 ExternalLayout() : Size(0), Align(0) {}
62
63 /// Overall record size in bits.
64 uint64_t Size;
65
66 /// Overall record alignment in bits.
67 uint64_t Align;
68
69 /// Record field offsets in bits.
70 llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
71
72 /// Direct, non-virtual base offsets.
73 llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
74
75 /// Virtual base offsets.
76 llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
77
78 /// Get the offset of the given field. The external source must provide
79 /// entries for all fields in the record.
80 uint64_t getExternalFieldOffset(const FieldDecl *FD) {
81 assert(FieldOffsets.count(FD) &&(static_cast <bool> (FieldOffsets.count(FD) && "Field does not have an external offset"
) ? void (0) : __assert_fail ("FieldOffsets.count(FD) && \"Field does not have an external offset\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 82, __extension__ __PRETTY_FUNCTION__
))
82 "Field does not have an external offset")(static_cast <bool> (FieldOffsets.count(FD) && "Field does not have an external offset"
) ? void (0) : __assert_fail ("FieldOffsets.count(FD) && \"Field does not have an external offset\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 82, __extension__ __PRETTY_FUNCTION__
))
;
83 return FieldOffsets[FD];
84 }
85
86 bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
87 auto Known = BaseOffsets.find(RD);
88 if (Known == BaseOffsets.end())
89 return false;
90 BaseOffset = Known->second;
91 return true;
92 }
93
94 bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
95 auto Known = VirtualBaseOffsets.find(RD);
96 if (Known == VirtualBaseOffsets.end())
97 return false;
98 BaseOffset = Known->second;
99 return true;
100 }
101};
102
103/// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
104/// offsets while laying out a C++ class.
105class EmptySubobjectMap {
106 const ASTContext &Context;
107 uint64_t CharWidth;
108
109 /// Class - The class whose empty entries we're keeping track of.
110 const CXXRecordDecl *Class;
111
112 /// EmptyClassOffsets - A map from offsets to empty record decls.
113 typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
114 typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
115 EmptyClassOffsetsMapTy EmptyClassOffsets;
116
117 /// MaxEmptyClassOffset - The highest offset known to contain an empty
118 /// base subobject.
119 CharUnits MaxEmptyClassOffset;
120
121 /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
122 /// member subobject that is empty.
123 void ComputeEmptySubobjectSizes();
124
125 void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
126
127 void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
128 CharUnits Offset, bool PlacingEmptyBase);
129
130 void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
131 const CXXRecordDecl *Class, CharUnits Offset,
132 bool PlacingOverlappingField);
133 void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset,
134 bool PlacingOverlappingField);
135
136 /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
137 /// subobjects beyond the given offset.
138 bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
139 return Offset <= MaxEmptyClassOffset;
140 }
141
142 CharUnits
143 getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
144 uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
145 assert(FieldOffset % CharWidth == 0 &&(static_cast <bool> (FieldOffset % CharWidth == 0 &&
"Field offset not at char boundary!") ? void (0) : __assert_fail
("FieldOffset % CharWidth == 0 && \"Field offset not at char boundary!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 146, __extension__
__PRETTY_FUNCTION__))
146 "Field offset not at char boundary!")(static_cast <bool> (FieldOffset % CharWidth == 0 &&
"Field offset not at char boundary!") ? void (0) : __assert_fail
("FieldOffset % CharWidth == 0 && \"Field offset not at char boundary!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 146, __extension__
__PRETTY_FUNCTION__))
;
147
148 return Context.toCharUnitsFromBits(FieldOffset);
149 }
150
151protected:
152 bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
153 CharUnits Offset) const;
154
155 bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
156 CharUnits Offset);
157
158 bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
159 const CXXRecordDecl *Class,
160 CharUnits Offset) const;
161 bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
162 CharUnits Offset) const;
163
164public:
165 /// This holds the size of the largest empty subobject (either a base
166 /// or a member). Will be zero if the record being built doesn't contain
167 /// any empty classes.
168 CharUnits SizeOfLargestEmptySubobject;
169
170 EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
171 : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
172 ComputeEmptySubobjectSizes();
173 }
174
175 /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
176 /// at the given offset.
177 /// Returns false if placing the record will result in two components
178 /// (direct or indirect) of the same type having the same offset.
179 bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
180 CharUnits Offset);
181
182 /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
183 /// offset.
184 bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
185};
186
187void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
188 // Check the bases.
189 for (const CXXBaseSpecifier &Base : Class->bases()) {
190 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
191
192 CharUnits EmptySize;
193 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
194 if (BaseDecl->isEmpty()) {
195 // If the class decl is empty, get its size.
196 EmptySize = Layout.getSize();
197 } else {
198 // Otherwise, we get the largest empty subobject for the decl.
199 EmptySize = Layout.getSizeOfLargestEmptySubobject();
200 }
201
202 if (EmptySize > SizeOfLargestEmptySubobject)
203 SizeOfLargestEmptySubobject = EmptySize;
204 }
205
206 // Check the fields.
207 for (const FieldDecl *FD : Class->fields()) {
208 const RecordType *RT =
209 Context.getBaseElementType(FD->getType())->getAs<RecordType>();
210
211 // We only care about record types.
212 if (!RT)
213 continue;
214
215 CharUnits EmptySize;
216 const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
217 const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
218 if (MemberDecl->isEmpty()) {
219 // If the class decl is empty, get its size.
220 EmptySize = Layout.getSize();
221 } else {
222 // Otherwise, we get the largest empty subobject for the decl.
223 EmptySize = Layout.getSizeOfLargestEmptySubobject();
224 }
225
226 if (EmptySize > SizeOfLargestEmptySubobject)
227 SizeOfLargestEmptySubobject = EmptySize;
228 }
229}
230
231bool
232EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
233 CharUnits Offset) const {
234 // We only need to check empty bases.
235 if (!RD->isEmpty())
236 return true;
237
238 EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
239 if (I == EmptyClassOffsets.end())
240 return true;
241
242 const ClassVectorTy &Classes = I->second;
243 if (!llvm::is_contained(Classes, RD))
244 return true;
245
246 // There is already an empty class of the same type at this offset.
247 return false;
248}
249
250void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
251 CharUnits Offset) {
252 // We only care about empty bases.
253 if (!RD->isEmpty())
254 return;
255
256 // If we have empty structures inside a union, we can assign both
257 // the same offset. Just avoid pushing them twice in the list.
258 ClassVectorTy &Classes = EmptyClassOffsets[Offset];
259 if (llvm::is_contained(Classes, RD))
260 return;
261
262 Classes.push_back(RD);
263
264 // Update the empty class offset.
265 if (Offset > MaxEmptyClassOffset)
266 MaxEmptyClassOffset = Offset;
267}
268
269bool
270EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
271 CharUnits Offset) {
272 // We don't have to keep looking past the maximum offset that's known to
273 // contain an empty class.
274 if (!AnyEmptySubobjectsBeyondOffset(Offset))
275 return true;
276
277 if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
278 return false;
279
280 // Traverse all non-virtual bases.
281 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
282 for (const BaseSubobjectInfo *Base : Info->Bases) {
283 if (Base->IsVirtual)
284 continue;
285
286 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
287
288 if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
289 return false;
290 }
291
292 if (Info->PrimaryVirtualBaseInfo) {
293 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
294
295 if (Info == PrimaryVirtualBaseInfo->Derived) {
296 if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
297 return false;
298 }
299 }
300
301 // Traverse all member variables.
302 unsigned FieldNo = 0;
303 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
304 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
305 if (I->isBitField())
306 continue;
307
308 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
309 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
310 return false;
311 }
312
313 return true;
314}
315
316void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
317 CharUnits Offset,
318 bool PlacingEmptyBase) {
319 if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
320 // We know that the only empty subobjects that can conflict with empty
321 // subobject of non-empty bases, are empty bases that can be placed at
322 // offset zero. Because of this, we only need to keep track of empty base
323 // subobjects with offsets less than the size of the largest empty
324 // subobject for our class.
325 return;
326 }
327
328 AddSubobjectAtOffset(Info->Class, Offset);
329
330 // Traverse all non-virtual bases.
331 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
332 for (const BaseSubobjectInfo *Base : Info->Bases) {
333 if (Base->IsVirtual)
334 continue;
335
336 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
337 UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
338 }
339
340 if (Info->PrimaryVirtualBaseInfo) {
341 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
342
343 if (Info == PrimaryVirtualBaseInfo->Derived)
344 UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
345 PlacingEmptyBase);
346 }
347
348 // Traverse all member variables.
349 unsigned FieldNo = 0;
350 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
351 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
352 if (I->isBitField())
353 continue;
354
355 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
356 UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingEmptyBase);
357 }
358}
359
360bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
361 CharUnits Offset) {
362 // If we know this class doesn't have any empty subobjects we don't need to
363 // bother checking.
364 if (SizeOfLargestEmptySubobject.isZero())
365 return true;
366
367 if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
368 return false;
369
370 // We are able to place the base at this offset. Make sure to update the
371 // empty base subobject map.
372 UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
373 return true;
374}
375
376bool
377EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
378 const CXXRecordDecl *Class,
379 CharUnits Offset) const {
380 // We don't have to keep looking past the maximum offset that's known to
381 // contain an empty class.
382 if (!AnyEmptySubobjectsBeyondOffset(Offset))
383 return true;
384
385 if (!CanPlaceSubobjectAtOffset(RD, Offset))
386 return false;
387
388 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
389
390 // Traverse all non-virtual bases.
391 for (const CXXBaseSpecifier &Base : RD->bases()) {
392 if (Base.isVirtual())
393 continue;
394
395 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
396
397 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
398 if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
399 return false;
400 }
401
402 if (RD == Class) {
403 // This is the most derived class, traverse virtual bases as well.
404 for (const CXXBaseSpecifier &Base : RD->vbases()) {
405 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
406
407 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
408 if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
409 return false;
410 }
411 }
412
413 // Traverse all member variables.
414 unsigned FieldNo = 0;
415 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
416 I != E; ++I, ++FieldNo) {
417 if (I->isBitField())
418 continue;
419
420 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
421
422 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
423 return false;
424 }
425
426 return true;
427}
428
429bool
430EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
431 CharUnits Offset) const {
432 // We don't have to keep looking past the maximum offset that's known to
433 // contain an empty class.
434 if (!AnyEmptySubobjectsBeyondOffset(Offset))
435 return true;
436
437 QualType T = FD->getType();
438 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
439 return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
440
441 // If we have an array type we need to look at every element.
442 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
443 QualType ElemTy = Context.getBaseElementType(AT);
444 const RecordType *RT = ElemTy->getAs<RecordType>();
445 if (!RT)
446 return true;
447
448 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
449 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
450
451 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
452 CharUnits ElementOffset = Offset;
453 for (uint64_t I = 0; I != NumElements; ++I) {
454 // We don't have to keep looking past the maximum offset that's known to
455 // contain an empty class.
456 if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
457 return true;
458
459 if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
460 return false;
461
462 ElementOffset += Layout.getSize();
463 }
464 }
465
466 return true;
467}
468
469bool
470EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
471 CharUnits Offset) {
472 if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
473 return false;
474
475 // We are able to place the member variable at this offset.
476 // Make sure to update the empty field subobject map.
477 UpdateEmptyFieldSubobjects(FD, Offset, FD->hasAttr<NoUniqueAddressAttr>());
478 return true;
479}
480
481void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
482 const CXXRecordDecl *RD, const CXXRecordDecl *Class, CharUnits Offset,
483 bool PlacingOverlappingField) {
484 // We know that the only empty subobjects that can conflict with empty
485 // field subobjects are subobjects of empty bases and potentially-overlapping
486 // fields that can be placed at offset zero. Because of this, we only need to
487 // keep track of empty field subobjects with offsets less than the size of
488 // the largest empty subobject for our class.
489 //
490 // (Proof: we will only consider placing a subobject at offset zero or at
491 // >= the current dsize. The only cases where the earlier subobject can be
492 // placed beyond the end of dsize is if it's an empty base or a
493 // potentially-overlapping field.)
494 if (!PlacingOverlappingField && Offset >= SizeOfLargestEmptySubobject)
495 return;
496
497 AddSubobjectAtOffset(RD, Offset);
498
499 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
500
501 // Traverse all non-virtual bases.
502 for (const CXXBaseSpecifier &Base : RD->bases()) {
503 if (Base.isVirtual())
504 continue;
505
506 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
507
508 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
509 UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset,
510 PlacingOverlappingField);
511 }
512
513 if (RD == Class) {
514 // This is the most derived class, traverse virtual bases as well.
515 for (const CXXBaseSpecifier &Base : RD->vbases()) {
516 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
517
518 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
519 UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset,
520 PlacingOverlappingField);
521 }
522 }
523
524 // Traverse all member variables.
525 unsigned FieldNo = 0;
526 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
527 I != E; ++I, ++FieldNo) {
528 if (I->isBitField())
529 continue;
530
531 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
532
533 UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingOverlappingField);
534 }
535}
536
537void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
538 const FieldDecl *FD, CharUnits Offset, bool PlacingOverlappingField) {
539 QualType T = FD->getType();
540 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
541 UpdateEmptyFieldSubobjects(RD, RD, Offset, PlacingOverlappingField);
542 return;
543 }
544
545 // If we have an array type we need to update every element.
546 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
547 QualType ElemTy = Context.getBaseElementType(AT);
548 const RecordType *RT = ElemTy->getAs<RecordType>();
549 if (!RT)
550 return;
551
552 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
553 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
554
555 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
556 CharUnits ElementOffset = Offset;
557
558 for (uint64_t I = 0; I != NumElements; ++I) {
559 // We know that the only empty subobjects that can conflict with empty
560 // field subobjects are subobjects of empty bases that can be placed at
561 // offset zero. Because of this, we only need to keep track of empty field
562 // subobjects with offsets less than the size of the largest empty
563 // subobject for our class.
564 if (!PlacingOverlappingField &&
565 ElementOffset >= SizeOfLargestEmptySubobject)
566 return;
567
568 UpdateEmptyFieldSubobjects(RD, RD, ElementOffset,
569 PlacingOverlappingField);
570 ElementOffset += Layout.getSize();
571 }
572 }
573}
574
575typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
576
577class ItaniumRecordLayoutBuilder {
578protected:
579 // FIXME: Remove this and make the appropriate fields public.
580 friend class clang::ASTContext;
581
582 const ASTContext &Context;
583
584 EmptySubobjectMap *EmptySubobjects;
585
586 /// Size - The current size of the record layout.
587 uint64_t Size;
588
589 /// Alignment - The current alignment of the record layout.
590 CharUnits Alignment;
591
592 /// PreferredAlignment - The preferred alignment of the record layout.
593 CharUnits PreferredAlignment;
594
595 /// The alignment if attribute packed is not used.
596 CharUnits UnpackedAlignment;
597
598 /// \brief The maximum of the alignments of top-level members.
599 CharUnits UnadjustedAlignment;
600
601 SmallVector<uint64_t, 16> FieldOffsets;
602
603 /// Whether the external AST source has provided a layout for this
604 /// record.
605 unsigned UseExternalLayout : 1;
606
607 /// Whether we need to infer alignment, even when we have an
608 /// externally-provided layout.
609 unsigned InferAlignment : 1;
610
611 /// Packed - Whether the record is packed or not.
612 unsigned Packed : 1;
613
614 unsigned IsUnion : 1;
615
616 unsigned IsMac68kAlign : 1;
617
618 unsigned IsNaturalAlign : 1;
619
620 unsigned IsMsStruct : 1;
621
622 /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
623 /// this contains the number of bits in the last unit that can be used for
624 /// an adjacent bitfield if necessary. The unit in question is usually
625 /// a byte, but larger units are used if IsMsStruct.
626 unsigned char UnfilledBitsInLastUnit;
627
628 /// LastBitfieldStorageUnitSize - If IsMsStruct, represents the size of the
629 /// storage unit of the previous field if it was a bitfield.
630 unsigned char LastBitfieldStorageUnitSize;
631
632 /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
633 /// #pragma pack.
634 CharUnits MaxFieldAlignment;
635
636 /// DataSize - The data size of the record being laid out.
637 uint64_t DataSize;
638
639 CharUnits NonVirtualSize;
640 CharUnits NonVirtualAlignment;
641 CharUnits PreferredNVAlignment;
642
643 /// If we've laid out a field but not included its tail padding in Size yet,
644 /// this is the size up to the end of that field.
645 CharUnits PaddedFieldSize;
646
647 /// PrimaryBase - the primary base class (if one exists) of the class
648 /// we're laying out.
649 const CXXRecordDecl *PrimaryBase;
650
651 /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
652 /// out is virtual.
653 bool PrimaryBaseIsVirtual;
654
655 /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
656 /// pointer, as opposed to inheriting one from a primary base class.
657 bool HasOwnVFPtr;
658
659 /// the flag of field offset changing due to packed attribute.
660 bool HasPackedField;
661
662 /// HandledFirstNonOverlappingEmptyField - An auxiliary field used for AIX.
663 /// When there are OverlappingEmptyFields existing in the aggregate, the
664 /// flag shows if the following first non-empty or empty-but-non-overlapping
665 /// field has been handled, if any.
666 bool HandledFirstNonOverlappingEmptyField;
667
668 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
669
670 /// Bases - base classes and their offsets in the record.
671 BaseOffsetsMapTy Bases;
672
673 // VBases - virtual base classes and their offsets in the record.
674 ASTRecordLayout::VBaseOffsetsMapTy VBases;
675
676 /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
677 /// primary base classes for some other direct or indirect base class.
678 CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
679
680 /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
681 /// inheritance graph order. Used for determining the primary base class.
682 const CXXRecordDecl *FirstNearlyEmptyVBase;
683
684 /// VisitedVirtualBases - A set of all the visited virtual bases, used to
685 /// avoid visiting virtual bases more than once.
686 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
687
688 /// Valid if UseExternalLayout is true.
689 ExternalLayout External;
690
691 ItaniumRecordLayoutBuilder(const ASTContext &Context,
692 EmptySubobjectMap *EmptySubobjects)
693 : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
694 Alignment(CharUnits::One()), PreferredAlignment(CharUnits::One()),
695 UnpackedAlignment(CharUnits::One()),
696 UnadjustedAlignment(CharUnits::One()), UseExternalLayout(false),
697 InferAlignment(false), Packed(false), IsUnion(false),
698 IsMac68kAlign(false),
699 IsNaturalAlign(!Context.getTargetInfo().getTriple().isOSAIX()),
700 IsMsStruct(false), UnfilledBitsInLastUnit(0),
701 LastBitfieldStorageUnitSize(0), MaxFieldAlignment(CharUnits::Zero()),
702 DataSize(0), NonVirtualSize(CharUnits::Zero()),
703 NonVirtualAlignment(CharUnits::One()),
704 PreferredNVAlignment(CharUnits::One()),
705 PaddedFieldSize(CharUnits::Zero()), PrimaryBase(nullptr),
706 PrimaryBaseIsVirtual(false), HasOwnVFPtr(false), HasPackedField(false),
707 HandledFirstNonOverlappingEmptyField(false),
708 FirstNearlyEmptyVBase(nullptr) {}
709
710 void Layout(const RecordDecl *D);
711 void Layout(const CXXRecordDecl *D);
712 void Layout(const ObjCInterfaceDecl *D);
713
714 void LayoutFields(const RecordDecl *D);
715 void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
716 void LayoutWideBitField(uint64_t FieldSize, uint64_t StorageUnitSize,
717 bool FieldPacked, const FieldDecl *D);
718 void LayoutBitField(const FieldDecl *D);
719
720 TargetCXXABI getCXXABI() const {
721 return Context.getTargetInfo().getCXXABI();
722 }
723
724 /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
725 llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
726
727 typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
728 BaseSubobjectInfoMapTy;
729
730 /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
731 /// of the class we're laying out to their base subobject info.
732 BaseSubobjectInfoMapTy VirtualBaseInfo;
733
734 /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
735 /// class we're laying out to their base subobject info.
736 BaseSubobjectInfoMapTy NonVirtualBaseInfo;
737
738 /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
739 /// bases of the given class.
740 void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
741
742 /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
743 /// single class and all of its base classes.
744 BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
745 bool IsVirtual,
746 BaseSubobjectInfo *Derived);
747
748 /// DeterminePrimaryBase - Determine the primary base of the given class.
749 void DeterminePrimaryBase(const CXXRecordDecl *RD);
750
751 void SelectPrimaryVBase(const CXXRecordDecl *RD);
752
753 void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
754
755 /// LayoutNonVirtualBases - Determines the primary base class (if any) and
756 /// lays it out. Will then proceed to lay out all non-virtual base clasess.
757 void LayoutNonVirtualBases(const CXXRecordDecl *RD);
758
759 /// LayoutNonVirtualBase - Lays out a single non-virtual base.
760 void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
761
762 void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
763 CharUnits Offset);
764
765 /// LayoutVirtualBases - Lays out all the virtual bases.
766 void LayoutVirtualBases(const CXXRecordDecl *RD,
767 const CXXRecordDecl *MostDerivedClass);
768
769 /// LayoutVirtualBase - Lays out a single virtual base.
770 void LayoutVirtualBase(const BaseSubobjectInfo *Base);
771
772 /// LayoutBase - Will lay out a base and return the offset where it was
773 /// placed, in chars.
774 CharUnits LayoutBase(const BaseSubobjectInfo *Base);
775
776 /// InitializeLayout - Initialize record layout for the given record decl.
777 void InitializeLayout(const Decl *D);
778
779 /// FinishLayout - Finalize record layout. Adjust record size based on the
780 /// alignment.
781 void FinishLayout(const NamedDecl *D);
782
783 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment,
784 CharUnits PreferredAlignment);
785 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
786 UpdateAlignment(NewAlignment, UnpackedNewAlignment, NewAlignment);
787 }
788 void UpdateAlignment(CharUnits NewAlignment) {
789 UpdateAlignment(NewAlignment, NewAlignment, NewAlignment);
790 }
791
792 /// Retrieve the externally-supplied field offset for the given
793 /// field.
794 ///
795 /// \param Field The field whose offset is being queried.
796 /// \param ComputedOffset The offset that we've computed for this field.
797 uint64_t updateExternalFieldOffset(const FieldDecl *Field,
798 uint64_t ComputedOffset);
799
800 void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
801 uint64_t UnpackedOffset, unsigned UnpackedAlign,
802 bool isPacked, const FieldDecl *D);
803
804 DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
805
806 CharUnits getSize() const {
807 assert(Size % Context.getCharWidth() == 0)(static_cast <bool> (Size % Context.getCharWidth() == 0
) ? void (0) : __assert_fail ("Size % Context.getCharWidth() == 0"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 807, __extension__
__PRETTY_FUNCTION__))
;
808 return Context.toCharUnitsFromBits(Size);
809 }
810 uint64_t getSizeInBits() const { return Size; }
811
812 void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
813 void setSize(uint64_t NewSize) { Size = NewSize; }
814
815 CharUnits getAligment() const { return Alignment; }
816
817 CharUnits getDataSize() const {
818 assert(DataSize % Context.getCharWidth() == 0)(static_cast <bool> (DataSize % Context.getCharWidth() ==
0) ? void (0) : __assert_fail ("DataSize % Context.getCharWidth() == 0"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 818, __extension__
__PRETTY_FUNCTION__))
;
819 return Context.toCharUnitsFromBits(DataSize);
820 }
821 uint64_t getDataSizeInBits() const { return DataSize; }
822
823 void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
824 void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
825
826 ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
827 void operator=(const ItaniumRecordLayoutBuilder &) = delete;
828};
829} // end anonymous namespace
830
831void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
832 for (const auto &I : RD->bases()) {
833 assert(!I.getType()->isDependentType() &&(static_cast <bool> (!I.getType()->isDependentType()
&& "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!I.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 834, __extension__
__PRETTY_FUNCTION__))
834 "Cannot layout class with dependent bases.")(static_cast <bool> (!I.getType()->isDependentType()
&& "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!I.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 834, __extension__
__PRETTY_FUNCTION__))
;
835
836 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
837
838 // Check if this is a nearly empty virtual base.
839 if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
840 // If it's not an indirect primary base, then we've found our primary
841 // base.
842 if (!IndirectPrimaryBases.count(Base)) {
843 PrimaryBase = Base;
844 PrimaryBaseIsVirtual = true;
845 return;
846 }
847
848 // Is this the first nearly empty virtual base?
849 if (!FirstNearlyEmptyVBase)
850 FirstNearlyEmptyVBase = Base;
851 }
852
853 SelectPrimaryVBase(Base);
854 if (PrimaryBase)
855 return;
856 }
857}
858
859/// DeterminePrimaryBase - Determine the primary base of the given class.
860void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
861 // If the class isn't dynamic, it won't have a primary base.
862 if (!RD->isDynamicClass())
863 return;
864
865 // Compute all the primary virtual bases for all of our direct and
866 // indirect bases, and record all their primary virtual base classes.
867 RD->getIndirectPrimaryBases(IndirectPrimaryBases);
868
869 // If the record has a dynamic base class, attempt to choose a primary base
870 // class. It is the first (in direct base class order) non-virtual dynamic
871 // base class, if one exists.
872 for (const auto &I : RD->bases()) {
873 // Ignore virtual bases.
874 if (I.isVirtual())
875 continue;
876
877 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
878
879 if (Base->isDynamicClass()) {
880 // We found it.
881 PrimaryBase = Base;
882 PrimaryBaseIsVirtual = false;
883 return;
884 }
885 }
886
887 // Under the Itanium ABI, if there is no non-virtual primary base class,
888 // try to compute the primary virtual base. The primary virtual base is
889 // the first nearly empty virtual base that is not an indirect primary
890 // virtual base class, if one exists.
891 if (RD->getNumVBases() != 0) {
892 SelectPrimaryVBase(RD);
893 if (PrimaryBase)
894 return;
895 }
896
897 // Otherwise, it is the first indirect primary base class, if one exists.
898 if (FirstNearlyEmptyVBase) {
899 PrimaryBase = FirstNearlyEmptyVBase;
900 PrimaryBaseIsVirtual = true;
901 return;
902 }
903
904 assert(!PrimaryBase && "Should not get here with a primary base!")(static_cast <bool> (!PrimaryBase && "Should not get here with a primary base!"
) ? void (0) : __assert_fail ("!PrimaryBase && \"Should not get here with a primary base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 904, __extension__
__PRETTY_FUNCTION__))
;
905}
906
907BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
908 const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
909 BaseSubobjectInfo *Info;
910
911 if (IsVirtual) {
912 // Check if we already have info about this virtual base.
913 BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
914 if (InfoSlot) {
915 assert(InfoSlot->Class == RD && "Wrong class for virtual base info!")(static_cast <bool> (InfoSlot->Class == RD &&
"Wrong class for virtual base info!") ? void (0) : __assert_fail
("InfoSlot->Class == RD && \"Wrong class for virtual base info!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 915, __extension__
__PRETTY_FUNCTION__))
;
916 return InfoSlot;
917 }
918
919 // We don't, create it.
920 InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
921 Info = InfoSlot;
922 } else {
923 Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
924 }
925
926 Info->Class = RD;
927 Info->IsVirtual = IsVirtual;
928 Info->Derived = nullptr;
929 Info->PrimaryVirtualBaseInfo = nullptr;
930
931 const CXXRecordDecl *PrimaryVirtualBase = nullptr;
932 BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
933
934 // Check if this base has a primary virtual base.
935 if (RD->getNumVBases()) {
936 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
937 if (Layout.isPrimaryBaseVirtual()) {
938 // This base does have a primary virtual base.
939 PrimaryVirtualBase = Layout.getPrimaryBase();
940 assert(PrimaryVirtualBase && "Didn't have a primary virtual base!")(static_cast <bool> (PrimaryVirtualBase && "Didn't have a primary virtual base!"
) ? void (0) : __assert_fail ("PrimaryVirtualBase && \"Didn't have a primary virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 940, __extension__
__PRETTY_FUNCTION__))
;
941
942 // Now check if we have base subobject info about this primary base.
943 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
944
945 if (PrimaryVirtualBaseInfo) {
946 if (PrimaryVirtualBaseInfo->Derived) {
947 // We did have info about this primary base, and it turns out that it
948 // has already been claimed as a primary virtual base for another
949 // base.
950 PrimaryVirtualBase = nullptr;
951 } else {
952 // We can claim this base as our primary base.
953 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
954 PrimaryVirtualBaseInfo->Derived = Info;
955 }
956 }
957 }
958 }
959
960 // Now go through all direct bases.
961 for (const auto &I : RD->bases()) {
962 bool IsVirtual = I.isVirtual();
963
964 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
965
966 Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
967 }
968
969 if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
970 // Traversing the bases must have created the base info for our primary
971 // virtual base.
972 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
973 assert(PrimaryVirtualBaseInfo &&(static_cast <bool> (PrimaryVirtualBaseInfo && "Did not create a primary virtual base!"
) ? void (0) : __assert_fail ("PrimaryVirtualBaseInfo && \"Did not create a primary virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 974, __extension__
__PRETTY_FUNCTION__))
974 "Did not create a primary virtual base!")(static_cast <bool> (PrimaryVirtualBaseInfo && "Did not create a primary virtual base!"
) ? void (0) : __assert_fail ("PrimaryVirtualBaseInfo && \"Did not create a primary virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 974, __extension__
__PRETTY_FUNCTION__))
;
975
976 // Claim the primary virtual base as our primary virtual base.
977 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
978 PrimaryVirtualBaseInfo->Derived = Info;
979 }
980
981 return Info;
982}
983
984void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
985 const CXXRecordDecl *RD) {
986 for (const auto &I : RD->bases()) {
987 bool IsVirtual = I.isVirtual();
988
989 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
990
991 // Compute the base subobject info for this base.
992 BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
993 nullptr);
994
995 if (IsVirtual) {
996 // ComputeBaseInfo has already added this base for us.
997 assert(VirtualBaseInfo.count(BaseDecl) &&(static_cast <bool> (VirtualBaseInfo.count(BaseDecl) &&
"Did not add virtual base!") ? void (0) : __assert_fail ("VirtualBaseInfo.count(BaseDecl) && \"Did not add virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 998, __extension__
__PRETTY_FUNCTION__))
998 "Did not add virtual base!")(static_cast <bool> (VirtualBaseInfo.count(BaseDecl) &&
"Did not add virtual base!") ? void (0) : __assert_fail ("VirtualBaseInfo.count(BaseDecl) && \"Did not add virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 998, __extension__
__PRETTY_FUNCTION__))
;
999 } else {
1000 // Add the base info to the map of non-virtual bases.
1001 assert(!NonVirtualBaseInfo.count(BaseDecl) &&(static_cast <bool> (!NonVirtualBaseInfo.count(BaseDecl
) && "Non-virtual base already exists!") ? void (0) :
__assert_fail ("!NonVirtualBaseInfo.count(BaseDecl) && \"Non-virtual base already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1002, __extension__
__PRETTY_FUNCTION__))
1002 "Non-virtual base already exists!")(static_cast <bool> (!NonVirtualBaseInfo.count(BaseDecl
) && "Non-virtual base already exists!") ? void (0) :
__assert_fail ("!NonVirtualBaseInfo.count(BaseDecl) && \"Non-virtual base already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1002, __extension__
__PRETTY_FUNCTION__))
;
1003 NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
1004 }
1005 }
1006}
1007
1008void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
1009 CharUnits UnpackedBaseAlign) {
1010 CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;
1011
1012 // The maximum field alignment overrides base align.
1013 if (!MaxFieldAlignment.isZero()) {
1014 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1015 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1016 }
1017
1018 // Round up the current record size to pointer alignment.
1019 setSize(getSize().alignTo(BaseAlign));
1020
1021 // Update the alignment.
1022 UpdateAlignment(BaseAlign, UnpackedBaseAlign, BaseAlign);
1023}
1024
1025void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
1026 const CXXRecordDecl *RD) {
1027 // Then, determine the primary base class.
1028 DeterminePrimaryBase(RD);
1029
1030 // Compute base subobject info.
1031 ComputeBaseSubobjectInfo(RD);
1032
1033 // If we have a primary base class, lay it out.
1034 if (PrimaryBase) {
1035 if (PrimaryBaseIsVirtual) {
1036 // If the primary virtual base was a primary virtual base of some other
1037 // base class we'll have to steal it.
1038 BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1039 PrimaryBaseInfo->Derived = nullptr;
1040
1041 // We have a virtual primary base, insert it as an indirect primary base.
1042 IndirectPrimaryBases.insert(PrimaryBase);
1043
1044 assert(!VisitedVirtualBases.count(PrimaryBase) &&(static_cast <bool> (!VisitedVirtualBases.count(PrimaryBase
) && "vbase already visited!") ? void (0) : __assert_fail
("!VisitedVirtualBases.count(PrimaryBase) && \"vbase already visited!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1045, __extension__
__PRETTY_FUNCTION__))
1045 "vbase already visited!")(static_cast <bool> (!VisitedVirtualBases.count(PrimaryBase
) && "vbase already visited!") ? void (0) : __assert_fail
("!VisitedVirtualBases.count(PrimaryBase) && \"vbase already visited!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1045, __extension__
__PRETTY_FUNCTION__))
;
1046 VisitedVirtualBases.insert(PrimaryBase);
1047
1048 LayoutVirtualBase(PrimaryBaseInfo);
1049 } else {
1050 BaseSubobjectInfo *PrimaryBaseInfo =
1051 NonVirtualBaseInfo.lookup(PrimaryBase);
1052 assert(PrimaryBaseInfo &&(static_cast <bool> (PrimaryBaseInfo && "Did not find base info for non-virtual primary base!"
) ? void (0) : __assert_fail ("PrimaryBaseInfo && \"Did not find base info for non-virtual primary base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1053, __extension__
__PRETTY_FUNCTION__))
1053 "Did not find base info for non-virtual primary base!")(static_cast <bool> (PrimaryBaseInfo && "Did not find base info for non-virtual primary base!"
) ? void (0) : __assert_fail ("PrimaryBaseInfo && \"Did not find base info for non-virtual primary base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1053, __extension__
__PRETTY_FUNCTION__))
;
1054
1055 LayoutNonVirtualBase(PrimaryBaseInfo);
1056 }
1057
1058 // If this class needs a vtable/vf-table and didn't get one from a
1059 // primary base, add it in now.
1060 } else if (RD->isDynamicClass()) {
1061 assert(DataSize == 0 && "Vtable pointer must be at offset zero!")(static_cast <bool> (DataSize == 0 && "Vtable pointer must be at offset zero!"
) ? void (0) : __assert_fail ("DataSize == 0 && \"Vtable pointer must be at offset zero!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1061, __extension__
__PRETTY_FUNCTION__))
;
1062 CharUnits PtrWidth =
1063 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1064 CharUnits PtrAlign =
1065 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1066 EnsureVTablePointerAlignment(PtrAlign);
1067 HasOwnVFPtr = true;
1068
1069 assert(!IsUnion && "Unions cannot be dynamic classes.")(static_cast <bool> (!IsUnion && "Unions cannot be dynamic classes."
) ? void (0) : __assert_fail ("!IsUnion && \"Unions cannot be dynamic classes.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1069, __extension__
__PRETTY_FUNCTION__))
;
1070 HandledFirstNonOverlappingEmptyField = true;
1071
1072 setSize(getSize() + PtrWidth);
1073 setDataSize(getSize());
1074 }
1075
1076 // Now lay out the non-virtual bases.
1077 for (const auto &I : RD->bases()) {
1078
1079 // Ignore virtual bases.
1080 if (I.isVirtual())
1081 continue;
1082
1083 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1084
1085 // Skip the primary base, because we've already laid it out. The
1086 // !PrimaryBaseIsVirtual check is required because we might have a
1087 // non-virtual base of the same type as a primary virtual base.
1088 if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1089 continue;
1090
1091 // Lay out the base.
1092 BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1093 assert(BaseInfo && "Did not find base info for non-virtual base!")(static_cast <bool> (BaseInfo && "Did not find base info for non-virtual base!"
) ? void (0) : __assert_fail ("BaseInfo && \"Did not find base info for non-virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1093, __extension__
__PRETTY_FUNCTION__))
;
1094
1095 LayoutNonVirtualBase(BaseInfo);
1096 }
1097}
1098
1099void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1100 const BaseSubobjectInfo *Base) {
1101 // Layout the base.
1102 CharUnits Offset = LayoutBase(Base);
1103
1104 // Add its base class offset.
1105 assert(!Bases.count(Base->Class) && "base offset already exists!")(static_cast <bool> (!Bases.count(Base->Class) &&
"base offset already exists!") ? void (0) : __assert_fail ("!Bases.count(Base->Class) && \"base offset already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1105, __extension__
__PRETTY_FUNCTION__))
;
1106 Bases.insert(std::make_pair(Base->Class, Offset));
1107
1108 AddPrimaryVirtualBaseOffsets(Base, Offset);
1109}
1110
1111void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1112 const BaseSubobjectInfo *Info, CharUnits Offset) {
1113 // This base isn't interesting, it has no virtual bases.
1114 if (!Info->Class->getNumVBases())
1115 return;
1116
1117 // First, check if we have a virtual primary base to add offsets for.
1118 if (Info->PrimaryVirtualBaseInfo) {
1119 assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&(static_cast <bool> (Info->PrimaryVirtualBaseInfo->
IsVirtual && "Primary virtual base is not virtual!") ?
void (0) : __assert_fail ("Info->PrimaryVirtualBaseInfo->IsVirtual && \"Primary virtual base is not virtual!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1120, __extension__
__PRETTY_FUNCTION__))
1120 "Primary virtual base is not virtual!")(static_cast <bool> (Info->PrimaryVirtualBaseInfo->
IsVirtual && "Primary virtual base is not virtual!") ?
void (0) : __assert_fail ("Info->PrimaryVirtualBaseInfo->IsVirtual && \"Primary virtual base is not virtual!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1120, __extension__
__PRETTY_FUNCTION__))
;
1121 if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1122 // Add the offset.
1123 assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&(static_cast <bool> (!VBases.count(Info->PrimaryVirtualBaseInfo
->Class) && "primary vbase offset already exists!"
) ? void (0) : __assert_fail ("!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && \"primary vbase offset already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1124, __extension__
__PRETTY_FUNCTION__))
1124 "primary vbase offset already exists!")(static_cast <bool> (!VBases.count(Info->PrimaryVirtualBaseInfo
->Class) && "primary vbase offset already exists!"
) ? void (0) : __assert_fail ("!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && \"primary vbase offset already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1124, __extension__
__PRETTY_FUNCTION__))
;
1125 VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1126 ASTRecordLayout::VBaseInfo(Offset, false)));
1127
1128 // Traverse the primary virtual base.
1129 AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1130 }
1131 }
1132
1133 // Now go through all direct non-virtual bases.
1134 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1135 for (const BaseSubobjectInfo *Base : Info->Bases) {
1136 if (Base->IsVirtual)
1137 continue;
1138
1139 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1140 AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1141 }
1142}
1143
1144void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1145 const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1146 const CXXRecordDecl *PrimaryBase;
1147 bool PrimaryBaseIsVirtual;
1148
1149 if (MostDerivedClass
17.1
'MostDerivedClass' is equal to 'RD'
== RD) {
18
Taking true branch
1150 PrimaryBase = this->PrimaryBase;
1151 PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1152 } else {
1153 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1154 PrimaryBase = Layout.getPrimaryBase();
1155 PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1156 }
1157
1158 for (const CXXBaseSpecifier &Base : RD->bases()) {
19
Assuming '__begin1' is not equal to '__end1'
1159 assert(!Base.getType()->isDependentType() &&(static_cast <bool> (!Base.getType()->isDependentType
() && "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1160, __extension__
__PRETTY_FUNCTION__))
20
Assuming the condition is true
21
'?' condition is true
1160 "Cannot layout class with dependent bases.")(static_cast <bool> (!Base.getType()->isDependentType
() && "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1160, __extension__
__PRETTY_FUNCTION__))
;
1161
1162 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
22
'BaseDecl' initialized here
1163
1164 if (Base.isVirtual()) {
23
Assuming the condition is true
1165 if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
24
Assuming 'PrimaryBase' is equal to 'BaseDecl'
25
Assuming 'PrimaryBaseIsVirtual' is true
26
Taking false branch
1166 bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1167
1168 // Only lay out the virtual base if it's not an indirect primary base.
1169 if (!IndirectPrimaryBase) {
1170 // Only visit virtual bases once.
1171 if (!VisitedVirtualBases.insert(BaseDecl).second)
1172 continue;
1173
1174 const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1175 assert(BaseInfo && "Did not find virtual base info!")(static_cast <bool> (BaseInfo && "Did not find virtual base info!"
) ? void (0) : __assert_fail ("BaseInfo && \"Did not find virtual base info!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1175, __extension__
__PRETTY_FUNCTION__))
;
1176 LayoutVirtualBase(BaseInfo);
1177 }
1178 }
1179 }
1180
1181 if (!BaseDecl->getNumVBases()) {
27
Called C++ object pointer is null
1182 // This base isn't interesting since it doesn't have any virtual bases.
1183 continue;
1184 }
1185
1186 LayoutVirtualBases(BaseDecl, MostDerivedClass);
1187 }
1188}
1189
1190void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1191 const BaseSubobjectInfo *Base) {
1192 assert(!Base->Derived && "Trying to lay out a primary virtual base!")(static_cast <bool> (!Base->Derived && "Trying to lay out a primary virtual base!"
) ? void (0) : __assert_fail ("!Base->Derived && \"Trying to lay out a primary virtual base!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1192, __extension__
__PRETTY_FUNCTION__))
;
1193
1194 // Layout the base.
1195 CharUnits Offset = LayoutBase(Base);
1196
1197 // Add its base class offset.
1198 assert(!VBases.count(Base->Class) && "vbase offset already exists!")(static_cast <bool> (!VBases.count(Base->Class) &&
"vbase offset already exists!") ? void (0) : __assert_fail (
"!VBases.count(Base->Class) && \"vbase offset already exists!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1198, __extension__
__PRETTY_FUNCTION__))
;
1199 VBases.insert(std::make_pair(Base->Class,
1200 ASTRecordLayout::VBaseInfo(Offset, false)));
1201
1202 AddPrimaryVirtualBaseOffsets(Base, Offset);
1203}
1204
1205CharUnits
1206ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1207 assert(!IsUnion && "Unions cannot have base classes.")(static_cast <bool> (!IsUnion && "Unions cannot have base classes."
) ? void (0) : __assert_fail ("!IsUnion && \"Unions cannot have base classes.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1207, __extension__
__PRETTY_FUNCTION__))
;
1208
1209 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1210 CharUnits Offset;
1211
1212 // Query the external layout to see if it provides an offset.
1213 bool HasExternalLayout = false;
1214 if (UseExternalLayout) {
1215 if (Base->IsVirtual)
1216 HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1217 else
1218 HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1219 }
1220
1221 auto getBaseOrPreferredBaseAlignFromUnpacked = [&](CharUnits UnpackedAlign) {
1222 // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
1223 // Per GCC's documentation, it only applies to non-static data members.
1224 return (Packed && ((Context.getLangOpts().getClangABICompat() <=
1225 LangOptions::ClangABI::Ver6) ||
1226 Context.getTargetInfo().getTriple().isPS() ||
1227 Context.getTargetInfo().getTriple().isOSAIX()))
1228 ? CharUnits::One()
1229 : UnpackedAlign;
1230 };
1231
1232 CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1233 CharUnits UnpackedPreferredBaseAlign = Layout.getPreferredNVAlignment();
1234 CharUnits BaseAlign =
1235 getBaseOrPreferredBaseAlignFromUnpacked(UnpackedBaseAlign);
1236 CharUnits PreferredBaseAlign =
1237 getBaseOrPreferredBaseAlignFromUnpacked(UnpackedPreferredBaseAlign);
1238
1239 const bool DefaultsToAIXPowerAlignment =
1240 Context.getTargetInfo().defaultsToAIXPowerAlignment();
1241 if (DefaultsToAIXPowerAlignment) {
1242 // AIX `power` alignment does not apply the preferred alignment for
1243 // non-union classes if the source of the alignment (the current base in
1244 // this context) follows introduction of the first subobject with
1245 // exclusively allocated space or zero-extent array.
1246 if (!Base->Class->isEmpty() && !HandledFirstNonOverlappingEmptyField) {
1247 // By handling a base class that is not empty, we're handling the
1248 // "first (inherited) member".
1249 HandledFirstNonOverlappingEmptyField = true;
1250 } else if (!IsNaturalAlign) {
1251 UnpackedPreferredBaseAlign = UnpackedBaseAlign;
1252 PreferredBaseAlign = BaseAlign;
1253 }
1254 }
1255
1256 CharUnits UnpackedAlignTo = !DefaultsToAIXPowerAlignment
1257 ? UnpackedBaseAlign
1258 : UnpackedPreferredBaseAlign;
1259 // If we have an empty base class, try to place it at offset 0.
1260 if (Base->Class->isEmpty() &&
1261 (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1262 EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1263 setSize(std::max(getSize(), Layout.getSize()));
1264 // On PS4/PS5, don't update the alignment, to preserve compatibility.
1265 if (!Context.getTargetInfo().getTriple().isPS())
1266 UpdateAlignment(BaseAlign, UnpackedAlignTo, PreferredBaseAlign);
1267
1268 return CharUnits::Zero();
1269 }
1270
1271 // The maximum field alignment overrides the base align/(AIX-only) preferred
1272 // base align.
1273 if (!MaxFieldAlignment.isZero()) {
1274 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1275 PreferredBaseAlign = std::min(PreferredBaseAlign, MaxFieldAlignment);
1276 UnpackedAlignTo = std::min(UnpackedAlignTo, MaxFieldAlignment);
1277 }
1278
1279 CharUnits AlignTo =
1280 !DefaultsToAIXPowerAlignment ? BaseAlign : PreferredBaseAlign;
1281 if (!HasExternalLayout) {
1282 // Round up the current record size to the base's alignment boundary.
1283 Offset = getDataSize().alignTo(AlignTo);
1284
1285 // Try to place the base.
1286 while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1287 Offset += AlignTo;
1288 } else {
1289 bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1290 (void)Allowed;
1291 assert(Allowed && "Base subobject externally placed at overlapping offset")(static_cast <bool> (Allowed && "Base subobject externally placed at overlapping offset"
) ? void (0) : __assert_fail ("Allowed && \"Base subobject externally placed at overlapping offset\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1291, __extension__
__PRETTY_FUNCTION__))
;
1292
1293 if (InferAlignment && Offset < getDataSize().alignTo(AlignTo)) {
1294 // The externally-supplied base offset is before the base offset we
1295 // computed. Assume that the structure is packed.
1296 Alignment = CharUnits::One();
1297 InferAlignment = false;
1298 }
1299 }
1300
1301 if (!Base->Class->isEmpty()) {
1302 // Update the data size.
1303 setDataSize(Offset + Layout.getNonVirtualSize());
1304
1305 setSize(std::max(getSize(), getDataSize()));
1306 } else
1307 setSize(std::max(getSize(), Offset + Layout.getSize()));
1308
1309 // Remember max struct/class alignment.
1310 UpdateAlignment(BaseAlign, UnpackedAlignTo, PreferredBaseAlign);
1311
1312 return Offset;
1313}
1314
1315void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1316 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1317 IsUnion = RD->isUnion();
1318 IsMsStruct = RD->isMsStruct(Context);
1319 }
1320
1321 Packed = D->hasAttr<PackedAttr>();
1322
1323 // Honor the default struct packing maximum alignment flag.
1324 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1325 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1326 }
1327
1328 // mac68k alignment supersedes maximum field alignment and attribute aligned,
1329 // and forces all structures to have 2-byte alignment. The IBM docs on it
1330 // allude to additional (more complicated) semantics, especially with regard
1331 // to bit-fields, but gcc appears not to follow that.
1332 if (D->hasAttr<AlignMac68kAttr>()) {
1333 assert((static_cast <bool> (!D->hasAttr<AlignNaturalAttr
>() && "Having both mac68k and natural alignment on a decl is not allowed."
) ? void (0) : __assert_fail ("!D->hasAttr<AlignNaturalAttr>() && \"Having both mac68k and natural alignment on a decl is not allowed.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1335, __extension__
__PRETTY_FUNCTION__))
1334 !D->hasAttr<AlignNaturalAttr>() &&(static_cast <bool> (!D->hasAttr<AlignNaturalAttr
>() && "Having both mac68k and natural alignment on a decl is not allowed."
) ? void (0) : __assert_fail ("!D->hasAttr<AlignNaturalAttr>() && \"Having both mac68k and natural alignment on a decl is not allowed.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1335, __extension__
__PRETTY_FUNCTION__))
1335 "Having both mac68k and natural alignment on a decl is not allowed.")(static_cast <bool> (!D->hasAttr<AlignNaturalAttr
>() && "Having both mac68k and natural alignment on a decl is not allowed."
) ? void (0) : __assert_fail ("!D->hasAttr<AlignNaturalAttr>() && \"Having both mac68k and natural alignment on a decl is not allowed.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1335, __extension__
__PRETTY_FUNCTION__))
;
1336 IsMac68kAlign = true;
1337 MaxFieldAlignment = CharUnits::fromQuantity(2);
1338 Alignment = CharUnits::fromQuantity(2);
1339 PreferredAlignment = CharUnits::fromQuantity(2);
1340 } else {
1341 if (D->hasAttr<AlignNaturalAttr>())
1342 IsNaturalAlign = true;
1343
1344 if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1345 MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1346
1347 if (unsigned MaxAlign = D->getMaxAlignment())
1348 UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1349 }
1350
1351 HandledFirstNonOverlappingEmptyField =
1352 !Context.getTargetInfo().defaultsToAIXPowerAlignment() || IsNaturalAlign;
1353
1354 // If there is an external AST source, ask it for the various offsets.
1355 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1356 if (ExternalASTSource *Source = Context.getExternalSource()) {
1357 UseExternalLayout = Source->layoutRecordType(
1358 RD, External.Size, External.Align, External.FieldOffsets,
1359 External.BaseOffsets, External.VirtualBaseOffsets);
1360
1361 // Update based on external alignment.
1362 if (UseExternalLayout) {
1363 if (External.Align > 0) {
1364 Alignment = Context.toCharUnitsFromBits(External.Align);
1365 PreferredAlignment = Context.toCharUnitsFromBits(External.Align);
1366 } else {
1367 // The external source didn't have alignment information; infer it.
1368 InferAlignment = true;
1369 }
1370 }
1371 }
1372}
1373
1374void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1375 InitializeLayout(D);
1376 LayoutFields(D);
1377
1378 // Finally, round the size of the total struct up to the alignment of the
1379 // struct itself.
1380 FinishLayout(D);
1381}
1382
1383void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1384 InitializeLayout(RD);
1385
1386 // Lay out the vtable and the non-virtual bases.
1387 LayoutNonVirtualBases(RD);
1388
1389 LayoutFields(RD);
1390
1391 NonVirtualSize = Context.toCharUnitsFromBits(
1392 llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1393 NonVirtualAlignment = Alignment;
1394 PreferredNVAlignment = PreferredAlignment;
1395
1396 // Lay out the virtual bases and add the primary virtual base offsets.
1397 LayoutVirtualBases(RD, RD);
17
Calling 'ItaniumRecordLayoutBuilder::LayoutVirtualBases'
1398
1399 // Finally, round the size of the total struct up to the alignment
1400 // of the struct itself.
1401 FinishLayout(RD);
1402
1403#ifndef NDEBUG
1404 // Check that we have base offsets for all bases.
1405 for (const CXXBaseSpecifier &Base : RD->bases()) {
1406 if (Base.isVirtual())
1407 continue;
1408
1409 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1410
1411 assert(Bases.count(BaseDecl) && "Did not find base offset!")(static_cast <bool> (Bases.count(BaseDecl) && "Did not find base offset!"
) ? void (0) : __assert_fail ("Bases.count(BaseDecl) && \"Did not find base offset!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1411, __extension__
__PRETTY_FUNCTION__))
;
1412 }
1413
1414 // And all virtual bases.
1415 for (const CXXBaseSpecifier &Base : RD->vbases()) {
1416 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1417
1418 assert(VBases.count(BaseDecl) && "Did not find base offset!")(static_cast <bool> (VBases.count(BaseDecl) && "Did not find base offset!"
) ? void (0) : __assert_fail ("VBases.count(BaseDecl) && \"Did not find base offset!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1418, __extension__
__PRETTY_FUNCTION__))
;
1419 }
1420#endif
1421}
1422
1423void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1424 if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1425 const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1426
1427 UpdateAlignment(SL.getAlignment());
1428
1429 // We start laying out ivars not at the end of the superclass
1430 // structure, but at the next byte following the last field.
1431 setDataSize(SL.getDataSize());
1432 setSize(getDataSize());
1433 }
1434
1435 InitializeLayout(D);
1436 // Layout each ivar sequentially.
1437 for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1438 IVD = IVD->getNextIvar())
1439 LayoutField(IVD, false);
1440
1441 // Finally, round the size of the total struct up to the alignment of the
1442 // struct itself.
1443 FinishLayout(D);
1444}
1445
1446void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1447 // Layout each field, for now, just sequentially, respecting alignment. In
1448 // the future, this will need to be tweakable by targets.
1449 bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1450 bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1451 for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1452 auto Next(I);
1453 ++Next;
1454 LayoutField(*I,
1455 InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1456 }
1457}
1458
1459// Rounds the specified size to have it a multiple of the char size.
1460static uint64_t
1461roundUpSizeToCharAlignment(uint64_t Size,
1462 const ASTContext &Context) {
1463 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1464 return llvm::alignTo(Size, CharAlignment);
1465}
1466
1467void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1468 uint64_t StorageUnitSize,
1469 bool FieldPacked,
1470 const FieldDecl *D) {
1471 assert(Context.getLangOpts().CPlusPlus &&(static_cast <bool> (Context.getLangOpts().CPlusPlus &&
"Can only have wide bit-fields in C++!") ? void (0) : __assert_fail
("Context.getLangOpts().CPlusPlus && \"Can only have wide bit-fields in C++!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1472, __extension__
__PRETTY_FUNCTION__))
1472 "Can only have wide bit-fields in C++!")(static_cast <bool> (Context.getLangOpts().CPlusPlus &&
"Can only have wide bit-fields in C++!") ? void (0) : __assert_fail
("Context.getLangOpts().CPlusPlus && \"Can only have wide bit-fields in C++!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1472, __extension__
__PRETTY_FUNCTION__))
;
1473
1474 // Itanium C++ ABI 2.4:
1475 // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1476 // sizeof(T')*8 <= n.
1477
1478 QualType IntegralPODTypes[] = {
1479 Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1480 Context.UnsignedLongTy, Context.UnsignedLongLongTy
1481 };
1482
1483 QualType Type;
1484 for (const QualType &QT : IntegralPODTypes) {
1485 uint64_t Size = Context.getTypeSize(QT);
1486
1487 if (Size > FieldSize)
1488 break;
1489
1490 Type = QT;
1491 }
1492 assert(!Type.isNull() && "Did not find a type!")(static_cast <bool> (!Type.isNull() && "Did not find a type!"
) ? void (0) : __assert_fail ("!Type.isNull() && \"Did not find a type!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1492, __extension__
__PRETTY_FUNCTION__))
;
1493
1494 CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1495
1496 // We're not going to use any of the unfilled bits in the last byte.
1497 UnfilledBitsInLastUnit = 0;
1498 LastBitfieldStorageUnitSize = 0;
1499
1500 uint64_t FieldOffset;
1501 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1502
1503 if (IsUnion) {
1504 uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1505 Context);
1506 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1507 FieldOffset = 0;
1508 } else {
1509 // The bitfield is allocated starting at the next offset aligned
1510 // appropriately for T', with length n bits.
1511 FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1512
1513 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1514
1515 setDataSize(
1516 llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1517 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1518 }
1519
1520 // Place this field at the current location.
1521 FieldOffsets.push_back(FieldOffset);
1522
1523 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1524 Context.toBits(TypeAlign), FieldPacked, D);
1525
1526 // Update the size.
1527 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1528
1529 // Remember max struct/class alignment.
1530 UpdateAlignment(TypeAlign);
1531}
1532
1533static bool isAIXLayout(const ASTContext &Context) {
1534 return Context.getTargetInfo().getTriple().getOS() == llvm::Triple::AIX;
1535}
1536
1537void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1538 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1539 uint64_t FieldSize = D->getBitWidthValue(Context);
1540 TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1541 uint64_t StorageUnitSize = FieldInfo.Width;
1542 unsigned FieldAlign = FieldInfo.Align;
1543 bool AlignIsRequired = FieldInfo.isAlignRequired();
1544
1545 // UnfilledBitsInLastUnit is the difference between the end of the
1546 // last allocated bitfield (i.e. the first bit offset available for
1547 // bitfields) and the end of the current data size in bits (i.e. the
1548 // first bit offset available for non-bitfields). The current data
1549 // size in bits is always a multiple of the char size; additionally,
1550 // for ms_struct records it's also a multiple of the
1551 // LastBitfieldStorageUnitSize (if set).
1552
1553 // The struct-layout algorithm is dictated by the platform ABI,
1554 // which in principle could use almost any rules it likes. In
1555 // practice, UNIXy targets tend to inherit the algorithm described
1556 // in the System V generic ABI. The basic bitfield layout rule in
1557 // System V is to place bitfields at the next available bit offset
1558 // where the entire bitfield would fit in an aligned storage unit of
1559 // the declared type; it's okay if an earlier or later non-bitfield
1560 // is allocated in the same storage unit. However, some targets
1561 // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1562 // require this storage unit to be aligned, and therefore always put
1563 // the bitfield at the next available bit offset.
1564
1565 // ms_struct basically requests a complete replacement of the
1566 // platform ABI's struct-layout algorithm, with the high-level goal
1567 // of duplicating MSVC's layout. For non-bitfields, this follows
1568 // the standard algorithm. The basic bitfield layout rule is to
1569 // allocate an entire unit of the bitfield's declared type
1570 // (e.g. 'unsigned long'), then parcel it up among successive
1571 // bitfields whose declared types have the same size, making a new
1572 // unit as soon as the last can no longer store the whole value.
1573 // Since it completely replaces the platform ABI's algorithm,
1574 // settings like !useBitFieldTypeAlignment() do not apply.
1575
1576 // A zero-width bitfield forces the use of a new storage unit for
1577 // later bitfields. In general, this occurs by rounding up the
1578 // current size of the struct as if the algorithm were about to
1579 // place a non-bitfield of the field's formal type. Usually this
1580 // does not change the alignment of the struct itself, but it does
1581 // on some targets (those that useZeroLengthBitfieldAlignment(),
1582 // e.g. ARM). In ms_struct layout, zero-width bitfields are
1583 // ignored unless they follow a non-zero-width bitfield.
1584
1585 // A field alignment restriction (e.g. from #pragma pack) or
1586 // specification (e.g. from __attribute__((aligned))) changes the
1587 // formal alignment of the field. For System V, this alters the
1588 // required alignment of the notional storage unit that must contain
1589 // the bitfield. For ms_struct, this only affects the placement of
1590 // new storage units. In both cases, the effect of #pragma pack is
1591 // ignored on zero-width bitfields.
1592
1593 // On System V, a packed field (e.g. from #pragma pack or
1594 // __attribute__((packed))) always uses the next available bit
1595 // offset.
1596
1597 // In an ms_struct struct, the alignment of a fundamental type is
1598 // always equal to its size. This is necessary in order to mimic
1599 // the i386 alignment rules on targets which might not fully align
1600 // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1601
1602 // First, some simple bookkeeping to perform for ms_struct structs.
1603 if (IsMsStruct) {
1604 // The field alignment for integer types is always the size.
1605 FieldAlign = StorageUnitSize;
1606
1607 // If the previous field was not a bitfield, or was a bitfield
1608 // with a different storage unit size, or if this field doesn't fit into
1609 // the current storage unit, we're done with that storage unit.
1610 if (LastBitfieldStorageUnitSize != StorageUnitSize ||
1611 UnfilledBitsInLastUnit < FieldSize) {
1612 // Also, ignore zero-length bitfields after non-bitfields.
1613 if (!LastBitfieldStorageUnitSize && !FieldSize)
1614 FieldAlign = 1;
1615
1616 UnfilledBitsInLastUnit = 0;
1617 LastBitfieldStorageUnitSize = 0;
1618 }
1619 }
1620
1621 if (isAIXLayout(Context)) {
1622 if (StorageUnitSize < Context.getTypeSize(Context.UnsignedIntTy)) {
1623 // On AIX, [bool, char, short] bitfields have the same alignment
1624 // as [unsigned].
1625 StorageUnitSize = Context.getTypeSize(Context.UnsignedIntTy);
1626 } else if (StorageUnitSize > Context.getTypeSize(Context.UnsignedIntTy) &&
1627 Context.getTargetInfo().getTriple().isArch32Bit() &&
1628 FieldSize <= 32) {
1629 // Under 32-bit compile mode, the bitcontainer is 32 bits if a single
1630 // long long bitfield has length no greater than 32 bits.
1631 StorageUnitSize = 32;
1632
1633 if (!AlignIsRequired)
1634 FieldAlign = 32;
1635 }
1636
1637 if (FieldAlign < StorageUnitSize) {
1638 // The bitfield alignment should always be greater than or equal to
1639 // bitcontainer size.
1640 FieldAlign = StorageUnitSize;
1641 }
1642 }
1643
1644 // If the field is wider than its declared type, it follows
1645 // different rules in all cases, except on AIX.
1646 // On AIX, wide bitfield follows the same rules as normal bitfield.
1647 if (FieldSize > StorageUnitSize && !isAIXLayout(Context)) {
1648 LayoutWideBitField(FieldSize, StorageUnitSize, FieldPacked, D);
1649 return;
1650 }
1651
1652 // Compute the next available bit offset.
1653 uint64_t FieldOffset =
1654 IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1655
1656 // Handle targets that don't honor bitfield type alignment.
1657 if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1658 // Some such targets do honor it on zero-width bitfields.
1659 if (FieldSize == 0 &&
1660 Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
1661 // Some targets don't honor leading zero-width bitfield.
1662 if (!IsUnion && FieldOffset == 0 &&
1663 !Context.getTargetInfo().useLeadingZeroLengthBitfield())
1664 FieldAlign = 1;
1665 else {
1666 // The alignment to round up to is the max of the field's natural
1667 // alignment and a target-specific fixed value (sometimes zero).
1668 unsigned ZeroLengthBitfieldBoundary =
1669 Context.getTargetInfo().getZeroLengthBitfieldBoundary();
1670 FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1671 }
1672 // If that doesn't apply, just ignore the field alignment.
1673 } else {
1674 FieldAlign = 1;
1675 }
1676 }
1677
1678 // Remember the alignment we would have used if the field were not packed.
1679 unsigned UnpackedFieldAlign = FieldAlign;
1680
1681 // Ignore the field alignment if the field is packed unless it has zero-size.
1682 if (!IsMsStruct && FieldPacked && FieldSize != 0)
1683 FieldAlign = 1;
1684
1685 // But, if there's an 'aligned' attribute on the field, honor that.
1686 unsigned ExplicitFieldAlign = D->getMaxAlignment();
1687 if (ExplicitFieldAlign) {
1688 FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1689 UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1690 }
1691
1692 // But, if there's a #pragma pack in play, that takes precedent over
1693 // even the 'aligned' attribute, for non-zero-width bitfields.
1694 unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1695 if (!MaxFieldAlignment.isZero() && FieldSize) {
1696 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1697 if (FieldPacked)
1698 FieldAlign = UnpackedFieldAlign;
1699 else
1700 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1701 }
1702
1703 // But, ms_struct just ignores all of that in unions, even explicit
1704 // alignment attributes.
1705 if (IsMsStruct && IsUnion) {
1706 FieldAlign = UnpackedFieldAlign = 1;
1707 }
1708
1709 // For purposes of diagnostics, we're going to simultaneously
1710 // compute the field offsets that we would have used if we weren't
1711 // adding any alignment padding or if the field weren't packed.
1712 uint64_t UnpaddedFieldOffset = FieldOffset;
1713 uint64_t UnpackedFieldOffset = FieldOffset;
1714
1715 // Check if we need to add padding to fit the bitfield within an
1716 // allocation unit with the right size and alignment. The rules are
1717 // somewhat different here for ms_struct structs.
1718 if (IsMsStruct) {
1719 // If it's not a zero-width bitfield, and we can fit the bitfield
1720 // into the active storage unit (and we haven't already decided to
1721 // start a new storage unit), just do so, regardless of any other
1722 // other consideration. Otherwise, round up to the right alignment.
1723 if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1724 FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1725 UnpackedFieldOffset =
1726 llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1727 UnfilledBitsInLastUnit = 0;
1728 }
1729
1730 } else {
1731 // #pragma pack, with any value, suppresses the insertion of padding.
1732 bool AllowPadding = MaxFieldAlignment.isZero();
1733
1734 // Compute the real offset.
1735 if (FieldSize == 0 ||
1736 (AllowPadding &&
1737 (FieldOffset & (FieldAlign - 1)) + FieldSize > StorageUnitSize)) {
1738 FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1739 } else if (ExplicitFieldAlign &&
1740 (MaxFieldAlignmentInBits == 0 ||
1741 ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1742 Context.getTargetInfo().useExplicitBitFieldAlignment()) {
1743 // TODO: figure it out what needs to be done on targets that don't honor
1744 // bit-field type alignment like ARM APCS ABI.
1745 FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1746 }
1747
1748 // Repeat the computation for diagnostic purposes.
1749 if (FieldSize == 0 ||
1750 (AllowPadding &&
1751 (UnpackedFieldOffset & (UnpackedFieldAlign - 1)) + FieldSize >
1752 StorageUnitSize))
1753 UnpackedFieldOffset =
1754 llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1755 else if (ExplicitFieldAlign &&
1756 (MaxFieldAlignmentInBits == 0 ||
1757 ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1758 Context.getTargetInfo().useExplicitBitFieldAlignment())
1759 UnpackedFieldOffset =
1760 llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1761 }
1762
1763 // If we're using external layout, give the external layout a chance
1764 // to override this information.
1765 if (UseExternalLayout)
1766 FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1767
1768 // Okay, place the bitfield at the calculated offset.
1769 FieldOffsets.push_back(FieldOffset);
1770
1771 // Bookkeeping:
1772
1773 // Anonymous members don't affect the overall record alignment,
1774 // except on targets where they do.
1775 if (!IsMsStruct &&
1776 !Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
1777 !D->getIdentifier())
1778 FieldAlign = UnpackedFieldAlign = 1;
1779
1780 // On AIX, zero-width bitfields pad out to the natural alignment boundary,
1781 // but do not increase the alignment greater than the MaxFieldAlignment, or 1
1782 // if packed.
1783 if (isAIXLayout(Context) && !FieldSize) {
1784 if (FieldPacked)
1785 FieldAlign = 1;
1786 if (!MaxFieldAlignment.isZero()) {
1787 UnpackedFieldAlign =
1788 std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1789 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1790 }
1791 }
1792
1793 // Diagnose differences in layout due to padding or packing.
1794 if (!UseExternalLayout)
1795 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1796 UnpackedFieldAlign, FieldPacked, D);
1797
1798 // Update DataSize to include the last byte containing (part of) the bitfield.
1799
1800 // For unions, this is just a max operation, as usual.
1801 if (IsUnion) {
1802 // For ms_struct, allocate the entire storage unit --- unless this
1803 // is a zero-width bitfield, in which case just use a size of 1.
1804 uint64_t RoundedFieldSize;
1805 if (IsMsStruct) {
1806 RoundedFieldSize = (FieldSize ? StorageUnitSize
1807 : Context.getTargetInfo().getCharWidth());
1808
1809 // Otherwise, allocate just the number of bytes required to store
1810 // the bitfield.
1811 } else {
1812 RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1813 }
1814 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1815
1816 // For non-zero-width bitfields in ms_struct structs, allocate a new
1817 // storage unit if necessary.
1818 } else if (IsMsStruct && FieldSize) {
1819 // We should have cleared UnfilledBitsInLastUnit in every case
1820 // where we changed storage units.
1821 if (!UnfilledBitsInLastUnit) {
1822 setDataSize(FieldOffset + StorageUnitSize);
1823 UnfilledBitsInLastUnit = StorageUnitSize;
1824 }
1825 UnfilledBitsInLastUnit -= FieldSize;
1826 LastBitfieldStorageUnitSize = StorageUnitSize;
1827
1828 // Otherwise, bump the data size up to include the bitfield,
1829 // including padding up to char alignment, and then remember how
1830 // bits we didn't use.
1831 } else {
1832 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1833 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1834 setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1835 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1836
1837 // The only time we can get here for an ms_struct is if this is a
1838 // zero-width bitfield, which doesn't count as anything for the
1839 // purposes of unfilled bits.
1840 LastBitfieldStorageUnitSize = 0;
1841 }
1842
1843 // Update the size.
1844 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1845
1846 // Remember max struct/class alignment.
1847 UnadjustedAlignment =
1848 std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
1849 UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1850 Context.toCharUnitsFromBits(UnpackedFieldAlign));
1851}
1852
1853void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1854 bool InsertExtraPadding) {
1855 auto *FieldClass = D->getType()->getAsCXXRecordDecl();
1856 bool PotentiallyOverlapping = D->hasAttr<NoUniqueAddressAttr>() && FieldClass;
1857 bool IsOverlappingEmptyField =
1858 PotentiallyOverlapping && FieldClass->isEmpty();
1859
1860 CharUnits FieldOffset =
1861 (IsUnion || IsOverlappingEmptyField) ? CharUnits::Zero() : getDataSize();
1862
1863 const bool DefaultsToAIXPowerAlignment =
1864 Context.getTargetInfo().defaultsToAIXPowerAlignment();
1865 bool FoundFirstNonOverlappingEmptyFieldForAIX = false;
1866 if (DefaultsToAIXPowerAlignment && !HandledFirstNonOverlappingEmptyField) {
1867 assert(FieldOffset == CharUnits::Zero() &&(static_cast <bool> (FieldOffset == CharUnits::Zero() &&
"The first non-overlapping empty field should have been handled."
) ? void (0) : __assert_fail ("FieldOffset == CharUnits::Zero() && \"The first non-overlapping empty field should have been handled.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1868, __extension__
__PRETTY_FUNCTION__))
1868 "The first non-overlapping empty field should have been handled.")(static_cast <bool> (FieldOffset == CharUnits::Zero() &&
"The first non-overlapping empty field should have been handled."
) ? void (0) : __assert_fail ("FieldOffset == CharUnits::Zero() && \"The first non-overlapping empty field should have been handled.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1868, __extension__
__PRETTY_FUNCTION__))
;
1869
1870 if (!IsOverlappingEmptyField) {
1871 FoundFirstNonOverlappingEmptyFieldForAIX = true;
1872
1873 // We're going to handle the "first member" based on
1874 // `FoundFirstNonOverlappingEmptyFieldForAIX` during the current
1875 // invocation of this function; record it as handled for future
1876 // invocations (except for unions, because the current field does not
1877 // represent all "firsts").
1878 HandledFirstNonOverlappingEmptyField = !IsUnion;
1879 }
1880 }
1881
1882 if (D->isBitField()) {
1883 LayoutBitField(D);
1884 return;
1885 }
1886
1887 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1888 // Reset the unfilled bits.
1889 UnfilledBitsInLastUnit = 0;
1890 LastBitfieldStorageUnitSize = 0;
1891
1892 llvm::Triple Target = Context.getTargetInfo().getTriple();
1893 bool FieldPacked = (Packed && (!FieldClass || FieldClass->isPOD() ||
1894 Context.getLangOpts().getClangABICompat() <=
1895 LangOptions::ClangABI::Ver14 ||
1896 Target.isPS() || Target.isOSDarwin())) ||
1897 D->hasAttr<PackedAttr>();
1898
1899 AlignRequirementKind AlignRequirement = AlignRequirementKind::None;
1900 CharUnits FieldSize;
1901 CharUnits FieldAlign;
1902 // The amount of this class's dsize occupied by the field.
1903 // This is equal to FieldSize unless we're permitted to pack
1904 // into the field's tail padding.
1905 CharUnits EffectiveFieldSize;
1906
1907 auto setDeclInfo = [&](bool IsIncompleteArrayType) {
1908 auto TI = Context.getTypeInfoInChars(D->getType());
1909 FieldAlign = TI.Align;
1910 // Flexible array members don't have any size, but they have to be
1911 // aligned appropriately for their element type.
1912 EffectiveFieldSize = FieldSize =
1913 IsIncompleteArrayType ? CharUnits::Zero() : TI.Width;
1914 AlignRequirement = TI.AlignRequirement;
1915 };
1916
1917 if (D->getType()->isIncompleteArrayType()) {
1918 setDeclInfo(true /* IsIncompleteArrayType */);
1919 } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1920 unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1921 EffectiveFieldSize = FieldSize = Context.toCharUnitsFromBits(
1922 Context.getTargetInfo().getPointerWidth(AS));
1923 FieldAlign = Context.toCharUnitsFromBits(
1924 Context.getTargetInfo().getPointerAlign(AS));
1925 } else {
1926 setDeclInfo(false /* IsIncompleteArrayType */);
1927
1928 // A potentially-overlapping field occupies its dsize or nvsize, whichever
1929 // is larger.
1930 if (PotentiallyOverlapping) {
1931 const ASTRecordLayout &Layout = Context.getASTRecordLayout(FieldClass);
1932 EffectiveFieldSize =
1933 std::max(Layout.getNonVirtualSize(), Layout.getDataSize());
1934 }
1935
1936 if (IsMsStruct) {
1937 // If MS bitfield layout is required, figure out what type is being
1938 // laid out and align the field to the width of that type.
1939
1940 // Resolve all typedefs down to their base type and round up the field
1941 // alignment if necessary.
1942 QualType T = Context.getBaseElementType(D->getType());
1943 if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1944 CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1945
1946 if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1947 assert((static_cast <bool> (!Context.getTargetInfo().getTriple
().isWindowsMSVCEnvironment() && "Non PowerOf2 size in MSVC mode"
) ? void (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1949, __extension__
__PRETTY_FUNCTION__))
1948 !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&(static_cast <bool> (!Context.getTargetInfo().getTriple
().isWindowsMSVCEnvironment() && "Non PowerOf2 size in MSVC mode"
) ? void (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1949, __extension__
__PRETTY_FUNCTION__))
1949 "Non PowerOf2 size in MSVC mode")(static_cast <bool> (!Context.getTargetInfo().getTriple
().isWindowsMSVCEnvironment() && "Non PowerOf2 size in MSVC mode"
) ? void (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 1949, __extension__
__PRETTY_FUNCTION__))
;
1950 // Base types with sizes that aren't a power of two don't work
1951 // with the layout rules for MS structs. This isn't an issue in
1952 // MSVC itself since there are no such base data types there.
1953 // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1954 // Any structs involving that data type obviously can't be ABI
1955 // compatible with MSVC regardless of how it is laid out.
1956
1957 // Since ms_struct can be mass enabled (via a pragma or via the
1958 // -mms-bitfields command line parameter), this can trigger for
1959 // structs that don't actually need MSVC compatibility, so we
1960 // need to be able to sidestep the ms_struct layout for these types.
1961
1962 // Since the combination of -mms-bitfields together with structs
1963 // like max_align_t (which contains a long double) for mingw is
1964 // quite common (and GCC handles it silently), just handle it
1965 // silently there. For other targets that have ms_struct enabled
1966 // (most probably via a pragma or attribute), trigger a diagnostic
1967 // that defaults to an error.
1968 if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1969 Diag(D->getLocation(), diag::warn_npot_ms_struct);
1970 }
1971 if (TypeSize > FieldAlign &&
1972 llvm::isPowerOf2_64(TypeSize.getQuantity()))
1973 FieldAlign = TypeSize;
1974 }
1975 }
1976 }
1977
1978 // When used as part of a typedef, or together with a 'packed' attribute, the
1979 // 'aligned' attribute can be used to decrease alignment. In that case, it
1980 // overrides any computed alignment we have, and there is no need to upgrade
1981 // the alignment.
1982 auto alignedAttrCanDecreaseAIXAlignment = [AlignRequirement, FieldPacked] {
1983 // Enum alignment sources can be safely ignored here, because this only
1984 // helps decide whether we need the AIX alignment upgrade, which only
1985 // applies to floating-point types.
1986 return AlignRequirement == AlignRequirementKind::RequiredByTypedef ||
1987 (AlignRequirement == AlignRequirementKind::RequiredByRecord &&
1988 FieldPacked);
1989 };
1990
1991 // The AIX `power` alignment rules apply the natural alignment of the
1992 // "first member" if it is of a floating-point data type (or is an aggregate
1993 // whose recursively "first" member or element is such a type). The alignment
1994 // associated with these types for subsequent members use an alignment value
1995 // where the floating-point data type is considered to have 4-byte alignment.
1996 //
1997 // For the purposes of the foregoing: vtable pointers, non-empty base classes,
1998 // and zero-width bit-fields count as prior members; members of empty class
1999 // types marked `no_unique_address` are not considered to be prior members.
2000 CharUnits PreferredAlign = FieldAlign;
2001 if (DefaultsToAIXPowerAlignment && !alignedAttrCanDecreaseAIXAlignment() &&
2002 (FoundFirstNonOverlappingEmptyFieldForAIX || IsNaturalAlign)) {
2003 auto performBuiltinTypeAlignmentUpgrade = [&](const BuiltinType *BTy) {
2004 if (BTy->getKind() == BuiltinType::Double ||
2005 BTy->getKind() == BuiltinType::LongDouble) {
2006 assert(PreferredAlign == CharUnits::fromQuantity(4) &&(static_cast <bool> (PreferredAlign == CharUnits::fromQuantity
(4) && "No need to upgrade the alignment value.") ? void
(0) : __assert_fail ("PreferredAlign == CharUnits::fromQuantity(4) && \"No need to upgrade the alignment value.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2007, __extension__
__PRETTY_FUNCTION__))
2007 "No need to upgrade the alignment value.")(static_cast <bool> (PreferredAlign == CharUnits::fromQuantity
(4) && "No need to upgrade the alignment value.") ? void
(0) : __assert_fail ("PreferredAlign == CharUnits::fromQuantity(4) && \"No need to upgrade the alignment value.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2007, __extension__
__PRETTY_FUNCTION__))
;
2008 PreferredAlign = CharUnits::fromQuantity(8);
2009 }
2010 };
2011
2012 const Type *BaseTy = D->getType()->getBaseElementTypeUnsafe();
2013 if (const ComplexType *CTy = BaseTy->getAs<ComplexType>()) {
2014 performBuiltinTypeAlignmentUpgrade(
2015 CTy->getElementType()->castAs<BuiltinType>());
2016 } else if (const BuiltinType *BTy = BaseTy->getAs<BuiltinType>()) {
2017 performBuiltinTypeAlignmentUpgrade(BTy);
2018 } else if (const RecordType *RT = BaseTy->getAs<RecordType>()) {
2019 const RecordDecl *RD = RT->getDecl();
2020 assert(RD && "Expected non-null RecordDecl.")(static_cast <bool> (RD && "Expected non-null RecordDecl."
) ? void (0) : __assert_fail ("RD && \"Expected non-null RecordDecl.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2020, __extension__
__PRETTY_FUNCTION__))
;
2021 const ASTRecordLayout &FieldRecord = Context.getASTRecordLayout(RD);
2022 PreferredAlign = FieldRecord.getPreferredAlignment();
2023 }
2024 }
2025
2026 // The align if the field is not packed. This is to check if the attribute
2027 // was unnecessary (-Wpacked).
2028 CharUnits UnpackedFieldAlign =
2029 !DefaultsToAIXPowerAlignment ? FieldAlign : PreferredAlign;
2030 CharUnits UnpackedFieldOffset = FieldOffset;
2031 CharUnits OriginalFieldAlign = UnpackedFieldAlign;
2032
2033 if (FieldPacked) {
2034 FieldAlign = CharUnits::One();
2035 PreferredAlign = CharUnits::One();
2036 }
2037 CharUnits MaxAlignmentInChars =
2038 Context.toCharUnitsFromBits(D->getMaxAlignment());
2039 FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
2040 PreferredAlign = std::max(PreferredAlign, MaxAlignmentInChars);
2041 UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
2042
2043 // The maximum field alignment overrides the aligned attribute.
2044 if (!MaxFieldAlignment.isZero()) {
2045 FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
2046 PreferredAlign = std::min(PreferredAlign, MaxFieldAlignment);
2047 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
2048 }
2049
2050 CharUnits AlignTo =
2051 !DefaultsToAIXPowerAlignment ? FieldAlign : PreferredAlign;
2052 // Round up the current record size to the field's alignment boundary.
2053 FieldOffset = FieldOffset.alignTo(AlignTo);
2054 UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
2055
2056 if (UseExternalLayout) {
2057 FieldOffset = Context.toCharUnitsFromBits(
2058 updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
2059
2060 if (!IsUnion && EmptySubobjects) {
2061 // Record the fact that we're placing a field at this offset.
2062 bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
2063 (void)Allowed;
2064 assert(Allowed && "Externally-placed field cannot be placed here")(static_cast <bool> (Allowed && "Externally-placed field cannot be placed here"
) ? void (0) : __assert_fail ("Allowed && \"Externally-placed field cannot be placed here\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2064, __extension__
__PRETTY_FUNCTION__))
;
2065 }
2066 } else {
2067 if (!IsUnion && EmptySubobjects) {
2068 // Check if we can place the field at this offset.
2069 while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
2070 // We couldn't place the field at the offset. Try again at a new offset.
2071 // We try offset 0 (for an empty field) and then dsize(C) onwards.
2072 if (FieldOffset == CharUnits::Zero() &&
2073 getDataSize() != CharUnits::Zero())
2074 FieldOffset = getDataSize().alignTo(AlignTo);
2075 else
2076 FieldOffset += AlignTo;
2077 }
2078 }
2079 }
2080
2081 // Place this field at the current location.
2082 FieldOffsets.push_back(Context.toBits(FieldOffset));
2083
2084 if (!UseExternalLayout)
2085 CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
2086 Context.toBits(UnpackedFieldOffset),
2087 Context.toBits(UnpackedFieldAlign), FieldPacked, D);
2088
2089 if (InsertExtraPadding) {
2090 CharUnits ASanAlignment = CharUnits::fromQuantity(8);
2091 CharUnits ExtraSizeForAsan = ASanAlignment;
2092 if (FieldSize % ASanAlignment)
2093 ExtraSizeForAsan +=
2094 ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
2095 EffectiveFieldSize = FieldSize = FieldSize + ExtraSizeForAsan;
2096 }
2097
2098 // Reserve space for this field.
2099 if (!IsOverlappingEmptyField) {
2100 uint64_t EffectiveFieldSizeInBits = Context.toBits(EffectiveFieldSize);
2101 if (IsUnion)
2102 setDataSize(std::max(getDataSizeInBits(), EffectiveFieldSizeInBits));
2103 else
2104 setDataSize(FieldOffset + EffectiveFieldSize);
2105
2106 PaddedFieldSize = std::max(PaddedFieldSize, FieldOffset + FieldSize);
2107 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
2108 } else {
2109 setSize(std::max(getSizeInBits(),
2110 (uint64_t)Context.toBits(FieldOffset + FieldSize)));
2111 }
2112
2113 // Remember max struct/class ABI-specified alignment.
2114 UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
2115 UpdateAlignment(FieldAlign, UnpackedFieldAlign, PreferredAlign);
2116
2117 // For checking the alignment of inner fields against
2118 // the alignment of its parent record.
2119 if (const RecordDecl *RD = D->getParent()) {
2120 // Check if packed attribute or pragma pack is present.
2121 if (RD->hasAttr<PackedAttr>() || !MaxFieldAlignment.isZero())
2122 if (FieldAlign < OriginalFieldAlign)
2123 if (D->getType()->isRecordType()) {
2124 // If the offset is a multiple of the alignment of
2125 // the type, raise the warning.
2126 // TODO: Takes no account the alignment of the outer struct
2127 if (FieldOffset % OriginalFieldAlign != 0)
2128 Diag(D->getLocation(), diag::warn_unaligned_access)
2129 << Context.getTypeDeclType(RD) << D->getName() << D->getType();
2130 }
2131 }
2132}
2133
2134void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
2135 // In C++, records cannot be of size 0.
2136 if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
2137 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2138 // Compatibility with gcc requires a class (pod or non-pod)
2139 // which is not empty but of size 0; such as having fields of
2140 // array of zero-length, remains of Size 0
2141 if (RD->isEmpty())
2142 setSize(CharUnits::One());
2143 }
2144 else
2145 setSize(CharUnits::One());
2146 }
2147
2148 // If we have any remaining field tail padding, include that in the overall
2149 // size.
2150 setSize(std::max(getSizeInBits(), (uint64_t)Context.toBits(PaddedFieldSize)));
2151
2152 // Finally, round the size of the record up to the alignment of the
2153 // record itself.
2154 uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
2155 uint64_t UnpackedSizeInBits =
2156 llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
2157
2158 uint64_t RoundedSize = llvm::alignTo(
2159 getSizeInBits(),
2160 Context.toBits(!Context.getTargetInfo().defaultsToAIXPowerAlignment()
2161 ? Alignment
2162 : PreferredAlignment));
2163
2164 if (UseExternalLayout) {
2165 // If we're inferring alignment, and the external size is smaller than
2166 // our size after we've rounded up to alignment, conservatively set the
2167 // alignment to 1.
2168 if (InferAlignment && External.Size < RoundedSize) {
2169 Alignment = CharUnits::One();
2170 PreferredAlignment = CharUnits::One();
2171 InferAlignment = false;
2172 }
2173 setSize(External.Size);
2174 return;
2175 }
2176
2177 // Set the size to the final size.
2178 setSize(RoundedSize);
2179
2180 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2181 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
2182 // Warn if padding was introduced to the struct/class/union.
2183 if (getSizeInBits() > UnpaddedSize) {
2184 unsigned PadSize = getSizeInBits() - UnpaddedSize;
2185 bool InBits = true;
2186 if (PadSize % CharBitNum == 0) {
2187 PadSize = PadSize / CharBitNum;
2188 InBits = false;
2189 }
2190 Diag(RD->getLocation(), diag::warn_padded_struct_size)
2191 << Context.getTypeDeclType(RD)
2192 << PadSize
2193 << (InBits ? 1 : 0); // (byte|bit)
2194 }
2195
2196 // Warn if we packed it unnecessarily, when the unpacked alignment is not
2197 // greater than the one after packing, the size in bits doesn't change and
2198 // the offset of each field is identical.
2199 if (Packed && UnpackedAlignment <= Alignment &&
2200 UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
2201 Diag(D->getLocation(), diag::warn_unnecessary_packed)
2202 << Context.getTypeDeclType(RD);
2203 }
2204}
2205
2206void ItaniumRecordLayoutBuilder::UpdateAlignment(
2207 CharUnits NewAlignment, CharUnits UnpackedNewAlignment,
2208 CharUnits PreferredNewAlignment) {
2209 // The alignment is not modified when using 'mac68k' alignment or when
2210 // we have an externally-supplied layout that also provides overall alignment.
2211 if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
2212 return;
2213
2214 if (NewAlignment > Alignment) {
2215 assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&(static_cast <bool> (llvm::isPowerOf2_64(NewAlignment.getQuantity
()) && "Alignment not a power of 2") ? void (0) : __assert_fail
("llvm::isPowerOf2_64(NewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2216, __extension__
__PRETTY_FUNCTION__))
2216 "Alignment not a power of 2")(static_cast <bool> (llvm::isPowerOf2_64(NewAlignment.getQuantity
()) && "Alignment not a power of 2") ? void (0) : __assert_fail
("llvm::isPowerOf2_64(NewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2216, __extension__
__PRETTY_FUNCTION__))
;
2217 Alignment = NewAlignment;
2218 }
2219
2220 if (UnpackedNewAlignment > UnpackedAlignment) {
2221 assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&(static_cast <bool> (llvm::isPowerOf2_64(UnpackedNewAlignment
.getQuantity()) && "Alignment not a power of 2") ? void
(0) : __assert_fail ("llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2222, __extension__
__PRETTY_FUNCTION__))
2222 "Alignment not a power of 2")(static_cast <bool> (llvm::isPowerOf2_64(UnpackedNewAlignment
.getQuantity()) && "Alignment not a power of 2") ? void
(0) : __assert_fail ("llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2222, __extension__
__PRETTY_FUNCTION__))
;
2223 UnpackedAlignment = UnpackedNewAlignment;
2224 }
2225
2226 if (PreferredNewAlignment > PreferredAlignment) {
2227 assert(llvm::isPowerOf2_64(PreferredNewAlignment.getQuantity()) &&(static_cast <bool> (llvm::isPowerOf2_64(PreferredNewAlignment
.getQuantity()) && "Alignment not a power of 2") ? void
(0) : __assert_fail ("llvm::isPowerOf2_64(PreferredNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2228, __extension__
__PRETTY_FUNCTION__))
2228 "Alignment not a power of 2")(static_cast <bool> (llvm::isPowerOf2_64(PreferredNewAlignment
.getQuantity()) && "Alignment not a power of 2") ? void
(0) : __assert_fail ("llvm::isPowerOf2_64(PreferredNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2228, __extension__
__PRETTY_FUNCTION__))
;
2229 PreferredAlignment = PreferredNewAlignment;
2230 }
2231}
2232
2233uint64_t
2234ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
2235 uint64_t ComputedOffset) {
2236 uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
2237
2238 if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
2239 // The externally-supplied field offset is before the field offset we
2240 // computed. Assume that the structure is packed.
2241 Alignment = CharUnits::One();
2242 PreferredAlignment = CharUnits::One();
2243 InferAlignment = false;
2244 }
2245
2246 // Use the externally-supplied field offset.
2247 return ExternalFieldOffset;
2248}
2249
2250/// Get diagnostic %select index for tag kind for
2251/// field padding diagnostic message.
2252/// WARNING: Indexes apply to particular diagnostics only!
2253///
2254/// \returns diagnostic %select index.
2255static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
2256 switch (Tag) {
2257 case TTK_Struct: return 0;
2258 case TTK_Interface: return 1;
2259 case TTK_Class: return 2;
2260 default: llvm_unreachable("Invalid tag kind for field padding diagnostic!")::llvm::llvm_unreachable_internal("Invalid tag kind for field padding diagnostic!"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2260)
;
2261 }
2262}
2263
2264void ItaniumRecordLayoutBuilder::CheckFieldPadding(
2265 uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
2266 unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
2267 // We let objc ivars without warning, objc interfaces generally are not used
2268 // for padding tricks.
2269 if (isa<ObjCIvarDecl>(D))
2270 return;
2271
2272 // Don't warn about structs created without a SourceLocation. This can
2273 // be done by clients of the AST, such as codegen.
2274 if (D->getLocation().isInvalid())
2275 return;
2276
2277 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2278
2279 // Warn if padding was introduced to the struct/class.
2280 if (!IsUnion && Offset > UnpaddedOffset) {
2281 unsigned PadSize = Offset - UnpaddedOffset;
2282 bool InBits = true;
2283 if (PadSize % CharBitNum == 0) {
2284 PadSize = PadSize / CharBitNum;
2285 InBits = false;
2286 }
2287 if (D->getIdentifier())
2288 Diag(D->getLocation(), diag::warn_padded_struct_field)
2289 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
2290 << Context.getTypeDeclType(D->getParent())
2291 << PadSize
2292 << (InBits ? 1 : 0) // (byte|bit)
2293 << D->getIdentifier();
2294 else
2295 Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2296 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
2297 << Context.getTypeDeclType(D->getParent())
2298 << PadSize
2299 << (InBits ? 1 : 0); // (byte|bit)
2300 }
2301 if (isPacked && Offset != UnpackedOffset) {
2302 HasPackedField = true;
2303 }
2304}
2305
2306static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
2307 const CXXRecordDecl *RD) {
2308 // If a class isn't polymorphic it doesn't have a key function.
2309 if (!RD->isPolymorphic())
2310 return nullptr;
2311
2312 // A class that is not externally visible doesn't have a key function. (Or
2313 // at least, there's no point to assigning a key function to such a class;
2314 // this doesn't affect the ABI.)
2315 if (!RD->isExternallyVisible())
2316 return nullptr;
2317
2318 // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2319 // Same behavior as GCC.
2320 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
2321 if (TSK == TSK_ImplicitInstantiation ||
2322 TSK == TSK_ExplicitInstantiationDeclaration ||
2323 TSK == TSK_ExplicitInstantiationDefinition)
2324 return nullptr;
2325
2326 bool allowInlineFunctions =
2327 Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline();
2328
2329 for (const CXXMethodDecl *MD : RD->methods()) {
2330 if (!MD->isVirtual())
2331 continue;
2332
2333 if (MD->isPure())
2334 continue;
2335
2336 // Ignore implicit member functions, they are always marked as inline, but
2337 // they don't have a body until they're defined.
2338 if (MD->isImplicit())
2339 continue;
2340
2341 if (MD->isInlineSpecified() || MD->isConstexpr())
2342 continue;
2343
2344 if (MD->hasInlineBody())
2345 continue;
2346
2347 // Ignore inline deleted or defaulted functions.
2348 if (!MD->isUserProvided())
2349 continue;
2350
2351 // In certain ABIs, ignore functions with out-of-line inline definitions.
2352 if (!allowInlineFunctions) {
2353 const FunctionDecl *Def;
2354 if (MD->hasBody(Def) && Def->isInlineSpecified())
2355 continue;
2356 }
2357
2358 if (Context.getLangOpts().CUDA) {
2359 // While compiler may see key method in this TU, during CUDA
2360 // compilation we should ignore methods that are not accessible
2361 // on this side of compilation.
2362 if (Context.getLangOpts().CUDAIsDevice) {
2363 // In device mode ignore methods without __device__ attribute.
2364 if (!MD->hasAttr<CUDADeviceAttr>())
2365 continue;
2366 } else {
2367 // In host mode ignore __device__-only methods.
2368 if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2369 continue;
2370 }
2371 }
2372
2373 // If the key function is dllimport but the class isn't, then the class has
2374 // no key function. The DLL that exports the key function won't export the
2375 // vtable in this case.
2376 if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>() &&
2377 !Context.getTargetInfo().hasPS4DLLImportExport())
2378 return nullptr;
2379
2380 // We found it.
2381 return MD;
2382 }
2383
2384 return nullptr;
2385}
2386
2387DiagnosticBuilder ItaniumRecordLayoutBuilder::Diag(SourceLocation Loc,
2388 unsigned DiagID) {
2389 return Context.getDiagnostics().Report(Loc, DiagID);
2390}
2391
2392/// Does the target C++ ABI require us to skip over the tail-padding
2393/// of the given class (considering it as a base class) when allocating
2394/// objects?
2395static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2396 switch (ABI.getTailPaddingUseRules()) {
2397 case TargetCXXABI::AlwaysUseTailPadding:
2398 return false;
2399
2400 case TargetCXXABI::UseTailPaddingUnlessPOD03:
2401 // FIXME: To the extent that this is meant to cover the Itanium ABI
2402 // rules, we should implement the restrictions about over-sized
2403 // bitfields:
2404 //
2405 // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2406 // In general, a type is considered a POD for the purposes of
2407 // layout if it is a POD type (in the sense of ISO C++
2408 // [basic.types]). However, a POD-struct or POD-union (in the
2409 // sense of ISO C++ [class]) with a bitfield member whose
2410 // declared width is wider than the declared type of the
2411 // bitfield is not a POD for the purpose of layout. Similarly,
2412 // an array type is not a POD for the purpose of layout if the
2413 // element type of the array is not a POD for the purpose of
2414 // layout.
2415 //
2416 // Where references to the ISO C++ are made in this paragraph,
2417 // the Technical Corrigendum 1 version of the standard is
2418 // intended.
2419 return RD->isPOD();
2420
2421 case TargetCXXABI::UseTailPaddingUnlessPOD11:
2422 // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2423 // but with a lot of abstraction penalty stripped off. This does
2424 // assume that these properties are set correctly even in C++98
2425 // mode; fortunately, that is true because we want to assign
2426 // consistently semantics to the type-traits intrinsics (or at
2427 // least as many of them as possible).
2428 return RD->isTrivial() && RD->isCXX11StandardLayout();
2429 }
2430
2431 llvm_unreachable("bad tail-padding use kind")::llvm::llvm_unreachable_internal("bad tail-padding use kind"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2431)
;
2432}
2433
2434static bool isMsLayout(const ASTContext &Context) {
2435 return Context.getTargetInfo().getCXXABI().isMicrosoft();
2436}
2437
2438// This section contains an implementation of struct layout that is, up to the
2439// included tests, compatible with cl.exe (2013). The layout produced is
2440// significantly different than those produced by the Itanium ABI. Here we note
2441// the most important differences.
2442//
2443// * The alignment of bitfields in unions is ignored when computing the
2444// alignment of the union.
2445// * The existence of zero-width bitfield that occurs after anything other than
2446// a non-zero length bitfield is ignored.
2447// * There is no explicit primary base for the purposes of layout. All bases
2448// with vfptrs are laid out first, followed by all bases without vfptrs.
2449// * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2450// function pointer) and a vbptr (virtual base pointer). They can each be
2451// shared with a, non-virtual bases. These bases need not be the same. vfptrs
2452// always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2453// placed after the lexicographically last non-virtual base. This placement
2454// is always before fields but can be in the middle of the non-virtual bases
2455// due to the two-pass layout scheme for non-virtual-bases.
2456// * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2457// the virtual base and is used in conjunction with virtual overrides during
2458// construction and destruction. This is always a 4 byte value and is used as
2459// an alternative to constructor vtables.
2460// * vtordisps are allocated in a block of memory with size and alignment equal
2461// to the alignment of the completed structure (before applying __declspec(
2462// align())). The vtordisp always occur at the end of the allocation block,
2463// immediately prior to the virtual base.
2464// * vfptrs are injected after all bases and fields have been laid out. In
2465// order to guarantee proper alignment of all fields, the vfptr injection
2466// pushes all bases and fields back by the alignment imposed by those bases
2467// and fields. This can potentially add a significant amount of padding.
2468// vfptrs are always injected at offset 0.
2469// * vbptrs are injected after all bases and fields have been laid out. In
2470// order to guarantee proper alignment of all fields, the vfptr injection
2471// pushes all bases and fields back by the alignment imposed by those bases
2472// and fields. This can potentially add a significant amount of padding.
2473// vbptrs are injected immediately after the last non-virtual base as
2474// lexicographically ordered in the code. If this site isn't pointer aligned
2475// the vbptr is placed at the next properly aligned location. Enough padding
2476// is added to guarantee a fit.
2477// * The last zero sized non-virtual base can be placed at the end of the
2478// struct (potentially aliasing another object), or may alias with the first
2479// field, even if they are of the same type.
2480// * The last zero size virtual base may be placed at the end of the struct
2481// potentially aliasing another object.
2482// * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2483// between bases or vbases with specific properties. The criteria for
2484// additional padding between two bases is that the first base is zero sized
2485// or ends with a zero sized subobject and the second base is zero sized or
2486// trails with a zero sized base or field (sharing of vfptrs can reorder the
2487// layout of the so the leading base is not always the first one declared).
2488// This rule does take into account fields that are not records, so padding
2489// will occur even if the last field is, e.g. an int. The padding added for
2490// bases is 1 byte. The padding added between vbases depends on the alignment
2491// of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2492// * There is no concept of non-virtual alignment, non-virtual alignment and
2493// alignment are always identical.
2494// * There is a distinction between alignment and required alignment.
2495// __declspec(align) changes the required alignment of a struct. This
2496// alignment is _always_ obeyed, even in the presence of #pragma pack. A
2497// record inherits required alignment from all of its fields and bases.
2498// * __declspec(align) on bitfields has the effect of changing the bitfield's
2499// alignment instead of its required alignment. This is the only known way
2500// to make the alignment of a struct bigger than 8. Interestingly enough
2501// this alignment is also immune to the effects of #pragma pack and can be
2502// used to create structures with large alignment under #pragma pack.
2503// However, because it does not impact required alignment, such a structure,
2504// when used as a field or base, will not be aligned if #pragma pack is
2505// still active at the time of use.
2506//
2507// Known incompatibilities:
2508// * all: #pragma pack between fields in a record
2509// * 2010 and back: If the last field in a record is a bitfield, every object
2510// laid out after the record will have extra padding inserted before it. The
2511// extra padding will have size equal to the size of the storage class of the
2512// bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2513// padding can be avoided by adding a 0 sized bitfield after the non-zero-
2514// sized bitfield.
2515// * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2516// greater due to __declspec(align()) then a second layout phase occurs after
2517// The locations of the vf and vb pointers are known. This layout phase
2518// suffers from the "last field is a bitfield" bug in 2010 and results in
2519// _every_ field getting padding put in front of it, potentially including the
2520// vfptr, leaving the vfprt at a non-zero location which results in a fault if
2521// anything tries to read the vftbl. The second layout phase also treats
2522// bitfields as separate entities and gives them each storage rather than
2523// packing them. Additionally, because this phase appears to perform a
2524// (an unstable) sort on the members before laying them out and because merged
2525// bitfields have the same address, the bitfields end up in whatever order
2526// the sort left them in, a behavior we could never hope to replicate.
2527
2528namespace {
2529struct MicrosoftRecordLayoutBuilder {
2530 struct ElementInfo {
2531 CharUnits Size;
2532 CharUnits Alignment;
2533 };
2534 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2535 MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2536private:
2537 MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2538 void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2539public:
2540 void layout(const RecordDecl *RD);
2541 void cxxLayout(const CXXRecordDecl *RD);
2542 /// Initializes size and alignment and honors some flags.
2543 void initializeLayout(const RecordDecl *RD);
2544 /// Initialized C++ layout, compute alignment and virtual alignment and
2545 /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2546 /// laid out.
2547 void initializeCXXLayout(const CXXRecordDecl *RD);
2548 void layoutNonVirtualBases(const CXXRecordDecl *RD);
2549 void layoutNonVirtualBase(const CXXRecordDecl *RD,
2550 const CXXRecordDecl *BaseDecl,
2551 const ASTRecordLayout &BaseLayout,
2552 const ASTRecordLayout *&PreviousBaseLayout);
2553 void injectVFPtr(const CXXRecordDecl *RD);
2554 void injectVBPtr(const CXXRecordDecl *RD);
2555 /// Lays out the fields of the record. Also rounds size up to
2556 /// alignment.
2557 void layoutFields(const RecordDecl *RD);
2558 void layoutField(const FieldDecl *FD);
2559 void layoutBitField(const FieldDecl *FD);
2560 /// Lays out a single zero-width bit-field in the record and handles
2561 /// special cases associated with zero-width bit-fields.
2562 void layoutZeroWidthBitField(const FieldDecl *FD);
2563 void layoutVirtualBases(const CXXRecordDecl *RD);
2564 void finalizeLayout(const RecordDecl *RD);
2565 /// Gets the size and alignment of a base taking pragma pack and
2566 /// __declspec(align) into account.
2567 ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2568 /// Gets the size and alignment of a field taking pragma pack and
2569 /// __declspec(align) into account. It also updates RequiredAlignment as a
2570 /// side effect because it is most convenient to do so here.
2571 ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2572 /// Places a field at an offset in CharUnits.
2573 void placeFieldAtOffset(CharUnits FieldOffset) {
2574 FieldOffsets.push_back(Context.toBits(FieldOffset));
2575 }
2576 /// Places a bitfield at a bit offset.
2577 void placeFieldAtBitOffset(uint64_t FieldOffset) {
2578 FieldOffsets.push_back(FieldOffset);
2579 }
2580 /// Compute the set of virtual bases for which vtordisps are required.
2581 void computeVtorDispSet(
2582 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2583 const CXXRecordDecl *RD) const;
2584 const ASTContext &Context;
2585 /// The size of the record being laid out.
2586 CharUnits Size;
2587 /// The non-virtual size of the record layout.
2588 CharUnits NonVirtualSize;
2589 /// The data size of the record layout.
2590 CharUnits DataSize;
2591 /// The current alignment of the record layout.
2592 CharUnits Alignment;
2593 /// The maximum allowed field alignment. This is set by #pragma pack.
2594 CharUnits MaxFieldAlignment;
2595 /// The alignment that this record must obey. This is imposed by
2596 /// __declspec(align()) on the record itself or one of its fields or bases.
2597 CharUnits RequiredAlignment;
2598 /// The size of the allocation of the currently active bitfield.
2599 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2600 /// is true.
2601 CharUnits CurrentBitfieldSize;
2602 /// Offset to the virtual base table pointer (if one exists).
2603 CharUnits VBPtrOffset;
2604 /// Minimum record size possible.
2605 CharUnits MinEmptyStructSize;
2606 /// The size and alignment info of a pointer.
2607 ElementInfo PointerInfo;
2608 /// The primary base class (if one exists).
2609 const CXXRecordDecl *PrimaryBase;
2610 /// The class we share our vb-pointer with.
2611 const CXXRecordDecl *SharedVBPtrBase;
2612 /// The collection of field offsets.
2613 SmallVector<uint64_t, 16> FieldOffsets;
2614 /// Base classes and their offsets in the record.
2615 BaseOffsetsMapTy Bases;
2616 /// virtual base classes and their offsets in the record.
2617 ASTRecordLayout::VBaseOffsetsMapTy VBases;
2618 /// The number of remaining bits in our last bitfield allocation.
2619 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2620 /// true.
2621 unsigned RemainingBitsInField;
2622 bool IsUnion : 1;
2623 /// True if the last field laid out was a bitfield and was not 0
2624 /// width.
2625 bool LastFieldIsNonZeroWidthBitfield : 1;
2626 /// True if the class has its own vftable pointer.
2627 bool HasOwnVFPtr : 1;
2628 /// True if the class has a vbtable pointer.
2629 bool HasVBPtr : 1;
2630 /// True if the last sub-object within the type is zero sized or the
2631 /// object itself is zero sized. This *does not* count members that are not
2632 /// records. Only used for MS-ABI.
2633 bool EndsWithZeroSizedObject : 1;
2634 /// True if this class is zero sized or first base is zero sized or
2635 /// has this property. Only used for MS-ABI.
2636 bool LeadsWithZeroSizedBase : 1;
2637
2638 /// True if the external AST source provided a layout for this record.
2639 bool UseExternalLayout : 1;
2640
2641 /// The layout provided by the external AST source. Only active if
2642 /// UseExternalLayout is true.
2643 ExternalLayout External;
2644};
2645} // namespace
2646
2647MicrosoftRecordLayoutBuilder::ElementInfo
2648MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2649 const ASTRecordLayout &Layout) {
2650 ElementInfo Info;
2651 Info.Alignment = Layout.getAlignment();
2652 // Respect pragma pack.
2653 if (!MaxFieldAlignment.isZero())
2654 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2655 // Track zero-sized subobjects here where it's already available.
2656 EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2657 // Respect required alignment, this is necessary because we may have adjusted
2658 // the alignment in the case of pragma pack. Note that the required alignment
2659 // doesn't actually apply to the struct alignment at this point.
2660 Alignment = std::max(Alignment, Info.Alignment);
2661 RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2662 Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2663 Info.Size = Layout.getNonVirtualSize();
2664 return Info;
2665}
2666
2667MicrosoftRecordLayoutBuilder::ElementInfo
2668MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2669 const FieldDecl *FD) {
2670 // Get the alignment of the field type's natural alignment, ignore any
2671 // alignment attributes.
2672 auto TInfo =
2673 Context.getTypeInfoInChars(FD->getType()->getUnqualifiedDesugaredType());
2674 ElementInfo Info{TInfo.Width, TInfo.Align};
2675 // Respect align attributes on the field.
2676 CharUnits FieldRequiredAlignment =
2677 Context.toCharUnitsFromBits(FD->getMaxAlignment());
2678 // Respect align attributes on the type.
2679 if (Context.isAlignmentRequired(FD->getType()))
2680 FieldRequiredAlignment = std::max(
2681 Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2682 // Respect attributes applied to subobjects of the field.
2683 if (FD->isBitField())
2684 // For some reason __declspec align impacts alignment rather than required
2685 // alignment when it is applied to bitfields.
2686 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2687 else {
2688 if (auto RT =
2689 FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
2690 auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2691 EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2692 FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2693 Layout.getRequiredAlignment());
2694 }
2695 // Capture required alignment as a side-effect.
2696 RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2697 }
2698 // Respect pragma pack, attribute pack and declspec align
2699 if (!MaxFieldAlignment.isZero())
2700 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2701 if (FD->hasAttr<PackedAttr>())
2702 Info.Alignment = CharUnits::One();
2703 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2704 return Info;
2705}
2706
2707void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2708 // For C record layout, zero-sized records always have size 4.
2709 MinEmptyStructSize = CharUnits::fromQuantity(4);
2710 initializeLayout(RD);
2711 layoutFields(RD);
2712 DataSize = Size = Size.alignTo(Alignment);
2713 RequiredAlignment = std::max(
2714 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2715 finalizeLayout(RD);
2716}
2717
2718void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2719 // The C++ standard says that empty structs have size 1.
2720 MinEmptyStructSize = CharUnits::One();
2721 initializeLayout(RD);
2722 initializeCXXLayout(RD);
2723 layoutNonVirtualBases(RD);
2724 layoutFields(RD);
2725 injectVBPtr(RD);
2726 injectVFPtr(RD);
2727 if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2728 Alignment = std::max(Alignment, PointerInfo.Alignment);
2729 auto RoundingAlignment = Alignment;
2730 if (!MaxFieldAlignment.isZero())
2731 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2732 if (!UseExternalLayout)
2733 Size = Size.alignTo(RoundingAlignment);
2734 NonVirtualSize = Size;
2735 RequiredAlignment = std::max(
2736 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2737 layoutVirtualBases(RD);
2738 finalizeLayout(RD);
2739}
2740
2741void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2742 IsUnion = RD->isUnion();
2743 Size = CharUnits::Zero();
2744 Alignment = CharUnits::One();
2745 // In 64-bit mode we always perform an alignment step after laying out vbases.
2746 // In 32-bit mode we do not. The check to see if we need to perform alignment
2747 // checks the RequiredAlignment field and performs alignment if it isn't 0.
2748 RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2749 ? CharUnits::One()
2750 : CharUnits::Zero();
2751 // Compute the maximum field alignment.
2752 MaxFieldAlignment = CharUnits::Zero();
2753 // Honor the default struct packing maximum alignment flag.
2754 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2755 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2756 // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2757 // than the pointer size.
2758 if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2759 unsigned PackedAlignment = MFAA->getAlignment();
2760 if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2761 MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2762 }
2763 // Packed attribute forces max field alignment to be 1.
2764 if (RD->hasAttr<PackedAttr>())
2765 MaxFieldAlignment = CharUnits::One();
2766
2767 // Try to respect the external layout if present.
2768 UseExternalLayout = false;
2769 if (ExternalASTSource *Source = Context.getExternalSource())
2770 UseExternalLayout = Source->layoutRecordType(
2771 RD, External.Size, External.Align, External.FieldOffsets,
2772 External.BaseOffsets, External.VirtualBaseOffsets);
2773}
2774
2775void
2776MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2777 EndsWithZeroSizedObject = false;
2778 LeadsWithZeroSizedBase = false;
2779 HasOwnVFPtr = false;
2780 HasVBPtr = false;
2781 PrimaryBase = nullptr;
2782 SharedVBPtrBase = nullptr;
2783 // Calculate pointer size and alignment. These are used for vfptr and vbprt
2784 // injection.
2785 PointerInfo.Size =
2786 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2787 PointerInfo.Alignment =
2788 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2789 // Respect pragma pack.
2790 if (!MaxFieldAlignment.isZero())
2791 PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2792}
2793
2794void
2795MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2796 // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2797 // out any bases that do not contain vfptrs. We implement this as two passes
2798 // over the bases. This approach guarantees that the primary base is laid out
2799 // first. We use these passes to calculate some additional aggregated
2800 // information about the bases, such as required alignment and the presence of
2801 // zero sized members.
2802 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2803 bool HasPolymorphicBaseClass = false;
2804 // Iterate through the bases and lay out the non-virtual ones.
2805 for (const CXXBaseSpecifier &Base : RD->bases()) {
2806 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2807 HasPolymorphicBaseClass |= BaseDecl->isPolymorphic();
2808 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2809 // Mark and skip virtual bases.
2810 if (Base.isVirtual()) {
2811 HasVBPtr = true;
2812 continue;
2813 }
2814 // Check for a base to share a VBPtr with.
2815 if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2816 SharedVBPtrBase = BaseDecl;
2817 HasVBPtr = true;
2818 }
2819 // Only lay out bases with extendable VFPtrs on the first pass.
2820 if (!BaseLayout.hasExtendableVFPtr())
2821 continue;
2822 // If we don't have a primary base, this one qualifies.
2823 if (!PrimaryBase) {
2824 PrimaryBase = BaseDecl;
2825 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2826 }
2827 // Lay out the base.
2828 layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2829 }
2830 // Figure out if we need a fresh VFPtr for this class.
2831 if (RD->isPolymorphic()) {
2832 if (!HasPolymorphicBaseClass)
2833 // This class introduces polymorphism, so we need a vftable to store the
2834 // RTTI information.
2835 HasOwnVFPtr = true;
2836 else if (!PrimaryBase) {
2837 // We have a polymorphic base class but can't extend its vftable. Add a
2838 // new vfptr if we would use any vftable slots.
2839 for (CXXMethodDecl *M : RD->methods()) {
2840 if (MicrosoftVTableContext::hasVtableSlot(M) &&
2841 M->size_overridden_methods() == 0) {
2842 HasOwnVFPtr = true;
2843 break;
2844 }
2845 }
2846 }
2847 }
2848 // If we don't have a primary base then we have a leading object that could
2849 // itself lead with a zero-sized object, something we track.
2850 bool CheckLeadingLayout = !PrimaryBase;
2851 // Iterate through the bases and lay out the non-virtual ones.
2852 for (const CXXBaseSpecifier &Base : RD->bases()) {
2853 if (Base.isVirtual())
2854 continue;
2855 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2856 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2857 // Only lay out bases without extendable VFPtrs on the second pass.
2858 if (BaseLayout.hasExtendableVFPtr()) {
2859 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2860 continue;
2861 }
2862 // If this is the first layout, check to see if it leads with a zero sized
2863 // object. If it does, so do we.
2864 if (CheckLeadingLayout) {
2865 CheckLeadingLayout = false;
2866 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2867 }
2868 // Lay out the base.
2869 layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2870 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2871 }
2872 // Set our VBPtroffset if we know it at this point.
2873 if (!HasVBPtr)
2874 VBPtrOffset = CharUnits::fromQuantity(-1);
2875 else if (SharedVBPtrBase) {
2876 const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2877 VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2878 }
2879}
2880
2881static bool recordUsesEBO(const RecordDecl *RD) {
2882 if (!isa<CXXRecordDecl>(RD))
2883 return false;
2884 if (RD->hasAttr<EmptyBasesAttr>())
2885 return true;
2886 if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2887 // TODO: Double check with the next version of MSVC.
2888 if (LVA->getVersion() <= LangOptions::MSVC2015)
2889 return false;
2890 // TODO: Some later version of MSVC will change the default behavior of the
2891 // compiler to enable EBO by default. When this happens, we will need an
2892 // additional isCompatibleWithMSVC check.
2893 return false;
2894}
2895
2896void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2897 const CXXRecordDecl *RD,
2898 const CXXRecordDecl *BaseDecl,
2899 const ASTRecordLayout &BaseLayout,
2900 const ASTRecordLayout *&PreviousBaseLayout) {
2901 // Insert padding between two bases if the left first one is zero sized or
2902 // contains a zero sized subobject and the right is zero sized or one leads
2903 // with a zero sized base.
2904 bool MDCUsesEBO = recordUsesEBO(RD);
2905 if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2906 BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2907 Size++;
2908 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2909 CharUnits BaseOffset;
2910
2911 // Respect the external AST source base offset, if present.
2912 bool FoundBase = false;
2913 if (UseExternalLayout) {
2914 FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2915 if (FoundBase) {
2916 assert(BaseOffset >= Size && "base offset already allocated")(static_cast <bool> (BaseOffset >= Size && "base offset already allocated"
) ? void (0) : __assert_fail ("BaseOffset >= Size && \"base offset already allocated\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2916, __extension__
__PRETTY_FUNCTION__))
;
2917 Size = BaseOffset;
2918 }
2919 }
2920
2921 if (!FoundBase) {
2922 if (MDCUsesEBO && BaseDecl->isEmpty()) {
2923 assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero())(static_cast <bool> (BaseLayout.getNonVirtualSize() == CharUnits
::Zero()) ? void (0) : __assert_fail ("BaseLayout.getNonVirtualSize() == CharUnits::Zero()"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 2923, __extension__
__PRETTY_FUNCTION__))
;
2924 BaseOffset = CharUnits::Zero();
2925 } else {
2926 // Otherwise, lay the base out at the end of the MDC.
2927 BaseOffset = Size = Size.alignTo(Info.Alignment);
2928 }
2929 }
2930 Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2931 Size += BaseLayout.getNonVirtualSize();
2932 PreviousBaseLayout = &BaseLayout;
2933}
2934
2935void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2936 LastFieldIsNonZeroWidthBitfield = false;
2937 for (const FieldDecl *Field : RD->fields())
2938 layoutField(Field);
2939}
2940
2941void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2942 if (FD->isBitField()) {
2943 layoutBitField(FD);
2944 return;
2945 }
2946 LastFieldIsNonZeroWidthBitfield = false;
2947 ElementInfo Info = getAdjustedElementInfo(FD);
2948 Alignment = std::max(Alignment, Info.Alignment);
2949 CharUnits FieldOffset;
2950 if (UseExternalLayout)
2951 FieldOffset =
2952 Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2953 else if (IsUnion)
2954 FieldOffset = CharUnits::Zero();
2955 else
2956 FieldOffset = Size.alignTo(Info.Alignment);
2957 placeFieldAtOffset(FieldOffset);
2958 Size = std::max(Size, FieldOffset + Info.Size);
2959}
2960
2961void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2962 unsigned Width = FD->getBitWidthValue(Context);
2963 if (Width == 0) {
2964 layoutZeroWidthBitField(FD);
2965 return;
2966 }
2967 ElementInfo Info = getAdjustedElementInfo(FD);
2968 // Clamp the bitfield to a containable size for the sake of being able
2969 // to lay them out. Sema will throw an error.
2970 if (Width > Context.toBits(Info.Size))
2971 Width = Context.toBits(Info.Size);
2972 // Check to see if this bitfield fits into an existing allocation. Note:
2973 // MSVC refuses to pack bitfields of formal types with different sizes
2974 // into the same allocation.
2975 if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
2976 CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2977 placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2978 RemainingBitsInField -= Width;
2979 return;
2980 }
2981 LastFieldIsNonZeroWidthBitfield = true;
2982 CurrentBitfieldSize = Info.Size;
2983 if (UseExternalLayout) {
2984 auto FieldBitOffset = External.getExternalFieldOffset(FD);
2985 placeFieldAtBitOffset(FieldBitOffset);
2986 auto NewSize = Context.toCharUnitsFromBits(
2987 llvm::alignDown(FieldBitOffset, Context.toBits(Info.Alignment)) +
2988 Context.toBits(Info.Size));
2989 Size = std::max(Size, NewSize);
2990 Alignment = std::max(Alignment, Info.Alignment);
2991 } else if (IsUnion) {
2992 placeFieldAtOffset(CharUnits::Zero());
2993 Size = std::max(Size, Info.Size);
2994 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2995 } else {
2996 // Allocate a new block of memory and place the bitfield in it.
2997 CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2998 placeFieldAtOffset(FieldOffset);
2999 Size = FieldOffset + Info.Size;
3000 Alignment = std::max(Alignment, Info.Alignment);
3001 RemainingBitsInField = Context.toBits(Info.Size) - Width;
3002 }
3003}
3004
3005void
3006MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
3007 // Zero-width bitfields are ignored unless they follow a non-zero-width
3008 // bitfield.
3009 if (!LastFieldIsNonZeroWidthBitfield) {
3010 placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
3011 // TODO: Add a Sema warning that MS ignores alignment for zero
3012 // sized bitfields that occur after zero-size bitfields or non-bitfields.
3013 return;
3014 }
3015 LastFieldIsNonZeroWidthBitfield = false;
3016 ElementInfo Info = getAdjustedElementInfo(FD);
3017 if (IsUnion) {
3018 placeFieldAtOffset(CharUnits::Zero());
3019 Size = std::max(Size, Info.Size);
3020 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
3021 } else {
3022 // Round up the current record size to the field's alignment boundary.
3023 CharUnits FieldOffset = Size.alignTo(Info.Alignment);
3024 placeFieldAtOffset(FieldOffset);
3025 Size = FieldOffset;
3026 Alignment = std::max(Alignment, Info.Alignment);
3027 }
3028}
3029
3030void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
3031 if (!HasVBPtr || SharedVBPtrBase)
3032 return;
3033 // Inject the VBPointer at the injection site.
3034 CharUnits InjectionSite = VBPtrOffset;
3035 // But before we do, make sure it's properly aligned.
3036 VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
3037 // Determine where the first field should be laid out after the vbptr.
3038 CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
3039 // Shift everything after the vbptr down, unless we're using an external
3040 // layout.
3041 if (UseExternalLayout) {
3042 // It is possible that there were no fields or bases located after vbptr,
3043 // so the size was not adjusted before.
3044 if (Size < FieldStart)
3045 Size = FieldStart;
3046 return;
3047 }
3048 // Make sure that the amount we push the fields back by is a multiple of the
3049 // alignment.
3050 CharUnits Offset = (FieldStart - InjectionSite)
3051 .alignTo(std::max(RequiredAlignment, Alignment));
3052 Size += Offset;
3053 for (uint64_t &FieldOffset : FieldOffsets)
3054 FieldOffset += Context.toBits(Offset);
3055 for (BaseOffsetsMapTy::value_type &Base : Bases)
3056 if (Base.second >= InjectionSite)
3057 Base.second += Offset;
3058}
3059
3060void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
3061 if (!HasOwnVFPtr)
3062 return;
3063 // Make sure that the amount we push the struct back by is a multiple of the
3064 // alignment.
3065 CharUnits Offset =
3066 PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
3067 // Push back the vbptr, but increase the size of the object and push back
3068 // regular fields by the offset only if not using external record layout.
3069 if (HasVBPtr)
3070 VBPtrOffset += Offset;
3071
3072 if (UseExternalLayout) {
3073 // The class may have no bases or fields, but still have a vfptr
3074 // (e.g. it's an interface class). The size was not correctly set before
3075 // in this case.
3076 if (FieldOffsets.empty() && Bases.empty())
3077 Size += Offset;
3078 return;
3079 }
3080
3081 Size += Offset;
3082
3083 // If we're using an external layout, the fields offsets have already
3084 // accounted for this adjustment.
3085 for (uint64_t &FieldOffset : FieldOffsets)
3086 FieldOffset += Context.toBits(Offset);
3087 for (BaseOffsetsMapTy::value_type &Base : Bases)
3088 Base.second += Offset;
3089}
3090
3091void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
3092 if (!HasVBPtr)
3093 return;
3094 // Vtordisps are always 4 bytes (even in 64-bit mode)
3095 CharUnits VtorDispSize = CharUnits::fromQuantity(4);
3096 CharUnits VtorDispAlignment = VtorDispSize;
3097 // vtordisps respect pragma pack.
3098 if (!MaxFieldAlignment.isZero())
3099 VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
3100 // The alignment of the vtordisp is at least the required alignment of the
3101 // entire record. This requirement may be present to support vtordisp
3102 // injection.
3103 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
3104 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
3105 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
3106 RequiredAlignment =
3107 std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
3108 }
3109 VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
3110 // Compute the vtordisp set.
3111 llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
3112 computeVtorDispSet(HasVtorDispSet, RD);
3113 // Iterate through the virtual bases and lay them out.
3114 const ASTRecordLayout *PreviousBaseLayout = nullptr;
3115 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
3116 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
3117 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
3118 bool HasVtordisp = HasVtorDispSet.contains(BaseDecl);
3119 // Insert padding between two bases if the left first one is zero sized or
3120 // contains a zero sized subobject and the right is zero sized or one leads
3121 // with a zero sized base. The padding between virtual bases is 4
3122 // bytes (in both 32 and 64 bits modes) and always involves rounding up to
3123 // the required alignment, we don't know why.
3124 if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
3125 BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
3126 HasVtordisp) {
3127 Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
3128 Alignment = std::max(VtorDispAlignment, Alignment);
3129 }
3130 // Insert the virtual base.
3131 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
3132 CharUnits BaseOffset;
3133
3134 // Respect the external AST source base offset, if present.
3135 if (UseExternalLayout) {
3136 if (!External.getExternalVBaseOffset(BaseDecl, BaseOffset))
3137 BaseOffset = Size;
3138 } else
3139 BaseOffset = Size.alignTo(Info.Alignment);
3140
3141 assert(BaseOffset >= Size && "base offset already allocated")(static_cast <bool> (BaseOffset >= Size && "base offset already allocated"
) ? void (0) : __assert_fail ("BaseOffset >= Size && \"base offset already allocated\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3141, __extension__
__PRETTY_FUNCTION__))
;
3142
3143 VBases.insert(std::make_pair(BaseDecl,
3144 ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
3145 Size = BaseOffset + BaseLayout.getNonVirtualSize();
3146 PreviousBaseLayout = &BaseLayout;
3147 }
3148}
3149
3150void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
3151 // Respect required alignment. Note that in 32-bit mode Required alignment
3152 // may be 0 and cause size not to be updated.
3153 DataSize = Size;
3154 if (!RequiredAlignment.isZero()) {
3155 Alignment = std::max(Alignment, RequiredAlignment);
3156 auto RoundingAlignment = Alignment;
3157 if (!MaxFieldAlignment.isZero())
3158 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
3159 RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
3160 Size = Size.alignTo(RoundingAlignment);
3161 }
3162 if (Size.isZero()) {
3163 if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
3164 EndsWithZeroSizedObject = true;
3165 LeadsWithZeroSizedBase = true;
3166 }
3167 // Zero-sized structures have size equal to their alignment if a
3168 // __declspec(align) came into play.
3169 if (RequiredAlignment >= MinEmptyStructSize)
3170 Size = Alignment;
3171 else
3172 Size = MinEmptyStructSize;
3173 }
3174
3175 if (UseExternalLayout) {
3176 Size = Context.toCharUnitsFromBits(External.Size);
3177 if (External.Align)
3178 Alignment = Context.toCharUnitsFromBits(External.Align);
3179 }
3180}
3181
3182// Recursively walks the non-virtual bases of a class and determines if any of
3183// them are in the bases with overridden methods set.
3184static bool
3185RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
3186 BasesWithOverriddenMethods,
3187 const CXXRecordDecl *RD) {
3188 if (BasesWithOverriddenMethods.count(RD))
3189 return true;
3190 // If any of a virtual bases non-virtual bases (recursively) requires a
3191 // vtordisp than so does this virtual base.
3192 for (const CXXBaseSpecifier &Base : RD->bases())
3193 if (!Base.isVirtual() &&
3194 RequiresVtordisp(BasesWithOverriddenMethods,
3195 Base.getType()->getAsCXXRecordDecl()))
3196 return true;
3197 return false;
3198}
3199
3200void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
3201 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
3202 const CXXRecordDecl *RD) const {
3203 // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
3204 // vftables.
3205 if (RD->getMSVtorDispMode() == MSVtorDispMode::ForVFTable) {
3206 for (const CXXBaseSpecifier &Base : RD->vbases()) {
3207 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
3208 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
3209 if (Layout.hasExtendableVFPtr())
3210 HasVtordispSet.insert(BaseDecl);
3211 }
3212 return;
3213 }
3214
3215 // If any of our bases need a vtordisp for this type, so do we. Check our
3216 // direct bases for vtordisp requirements.
3217 for (const CXXBaseSpecifier &Base : RD->bases()) {
3218 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
3219 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
3220 for (const auto &bi : Layout.getVBaseOffsetsMap())
3221 if (bi.second.hasVtorDisp())
3222 HasVtordispSet.insert(bi.first);
3223 }
3224 // We don't introduce any additional vtordisps if either:
3225 // * A user declared constructor or destructor aren't declared.
3226 // * #pragma vtordisp(0) or the /vd0 flag are in use.
3227 if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
3228 RD->getMSVtorDispMode() == MSVtorDispMode::Never)
3229 return;
3230 // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
3231 // possible for a partially constructed object with virtual base overrides to
3232 // escape a non-trivial constructor.
3233 assert(RD->getMSVtorDispMode() == MSVtorDispMode::ForVBaseOverride)(static_cast <bool> (RD->getMSVtorDispMode() == MSVtorDispMode
::ForVBaseOverride) ? void (0) : __assert_fail ("RD->getMSVtorDispMode() == MSVtorDispMode::ForVBaseOverride"
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3233, __extension__
__PRETTY_FUNCTION__))
;
3234 // Compute a set of base classes which define methods we override. A virtual
3235 // base in this set will require a vtordisp. A virtual base that transitively
3236 // contains one of these bases as a non-virtual base will also require a
3237 // vtordisp.
3238 llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
3239 llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
3240 // Seed the working set with our non-destructor, non-pure virtual methods.
3241 for (const CXXMethodDecl *MD : RD->methods())
3242 if (MicrosoftVTableContext::hasVtableSlot(MD) &&
3243 !isa<CXXDestructorDecl>(MD) && !MD->isPure())
3244 Work.insert(MD);
3245 while (!Work.empty()) {
3246 const CXXMethodDecl *MD = *Work.begin();
3247 auto MethodRange = MD->overridden_methods();
3248 // If a virtual method has no-overrides it lives in its parent's vtable.
3249 if (MethodRange.begin() == MethodRange.end())
3250 BasesWithOverriddenMethods.insert(MD->getParent());
3251 else
3252 Work.insert(MethodRange.begin(), MethodRange.end());
3253 // We've finished processing this element, remove it from the working set.
3254 Work.erase(MD);
3255 }
3256 // For each of our virtual bases, check if it is in the set of overridden
3257 // bases or if it transitively contains a non-virtual base that is.
3258 for (const CXXBaseSpecifier &Base : RD->vbases()) {
3259 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
3260 if (!HasVtordispSet.count(BaseDecl) &&
3261 RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
3262 HasVtordispSet.insert(BaseDecl);
3263 }
3264}
3265
3266/// getASTRecordLayout - Get or compute information about the layout of the
3267/// specified record (struct/union/class), which indicates its size and field
3268/// position information.
3269const ASTRecordLayout &
3270ASTContext::getASTRecordLayout(const RecordDecl *D) const {
3271 // These asserts test different things. A record has a definition
3272 // as soon as we begin to parse the definition. That definition is
3273 // not a complete definition (which is what isDefinition() tests)
3274 // until we *finish* parsing the definition.
3275
3276 if (D->hasExternalLexicalStorage() && !D->getDefinition())
5
Assuming the condition is false
3277 getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
3278
3279 D = D->getDefinition();
3280 assert(D && "Cannot get layout of forward declarations!")(static_cast <bool> (D && "Cannot get layout of forward declarations!"
) ? void (0) : __assert_fail ("D && \"Cannot get layout of forward declarations!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3280, __extension__
__PRETTY_FUNCTION__))
;
6
'?' condition is true
3281 assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!")(static_cast <bool> (!D->isInvalidDecl() && "Cannot get layout of invalid decl!"
) ? void (0) : __assert_fail ("!D->isInvalidDecl() && \"Cannot get layout of invalid decl!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3281, __extension__
__PRETTY_FUNCTION__))
;
7
Assuming the condition is true
8
'?' condition is true
3282 assert(D->isCompleteDefinition() && "Cannot layout type before complete!")(static_cast <bool> (D->isCompleteDefinition() &&
"Cannot layout type before complete!") ? void (0) : __assert_fail
("D->isCompleteDefinition() && \"Cannot layout type before complete!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3282, __extension__
__PRETTY_FUNCTION__))
;
9
Assuming the condition is true
10
'?' condition is true
3283
3284 // Look up this layout, if already laid out, return what we have.
3285 // Note that we can't save a reference to the entry because this function
3286 // is recursive.
3287 const ASTRecordLayout *Entry = ASTRecordLayouts[D];
3288 if (Entry) return *Entry;
11
Assuming 'Entry' is null
12
Taking false branch
3289
3290 const ASTRecordLayout *NewEntry = nullptr;
3291
3292 if (isMsLayout(*this)) {
13
Taking false branch
3293 MicrosoftRecordLayoutBuilder Builder(*this);
3294 if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3295 Builder.cxxLayout(RD);
3296 NewEntry = new (*this) ASTRecordLayout(
3297 *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3298 Builder.Alignment, Builder.RequiredAlignment, Builder.HasOwnVFPtr,
3299 Builder.HasOwnVFPtr || Builder.PrimaryBase, Builder.VBPtrOffset,
3300 Builder.DataSize, Builder.FieldOffsets, Builder.NonVirtualSize,
3301 Builder.Alignment, Builder.Alignment, CharUnits::Zero(),
3302 Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
3303 Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
3304 Builder.Bases, Builder.VBases);
3305 } else {
3306 Builder.layout(D);
3307 NewEntry = new (*this) ASTRecordLayout(
3308 *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3309 Builder.Alignment, Builder.RequiredAlignment, Builder.Size,
3310 Builder.FieldOffsets);
3311 }
3312 } else {
3313 if (const auto *RD
14.1
'RD' is non-null
= dyn_cast<CXXRecordDecl>(D)) {
14
Assuming 'D' is a 'CastReturnType'
15
Taking true branch
3314 EmptySubobjectMap EmptySubobjects(*this, RD);
3315 ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
3316 Builder.Layout(RD);
16
Calling 'ItaniumRecordLayoutBuilder::Layout'
3317
3318 // In certain situations, we are allowed to lay out objects in the
3319 // tail-padding of base classes. This is ABI-dependent.
3320 // FIXME: this should be stored in the record layout.
3321 bool skipTailPadding =
3322 mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3323
3324 // FIXME: This should be done in FinalizeLayout.
3325 CharUnits DataSize =
3326 skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3327 CharUnits NonVirtualSize =
3328 skipTailPadding ? DataSize : Builder.NonVirtualSize;
3329 NewEntry = new (*this) ASTRecordLayout(
3330 *this, Builder.getSize(), Builder.Alignment,
3331 Builder.PreferredAlignment, Builder.UnadjustedAlignment,
3332 /*RequiredAlignment : used by MS-ABI)*/
3333 Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3334 CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3335 NonVirtualSize, Builder.NonVirtualAlignment,
3336 Builder.PreferredNVAlignment,
3337 EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3338 Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3339 Builder.VBases);
3340 } else {
3341 ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3342 Builder.Layout(D);
3343
3344 NewEntry = new (*this) ASTRecordLayout(
3345 *this, Builder.getSize(), Builder.Alignment,
3346 Builder.PreferredAlignment, Builder.UnadjustedAlignment,
3347 /*RequiredAlignment : used by MS-ABI)*/
3348 Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3349 }
3350 }
3351
3352 ASTRecordLayouts[D] = NewEntry;
3353
3354 if (getLangOpts().DumpRecordLayouts) {
3355 llvm::outs() << "\n*** Dumping AST Record Layout\n";
3356 DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3357 }
3358
3359 return *NewEntry;
3360}
3361
3362const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD) {
3363 if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3364 return nullptr;
3365
3366 assert(RD->getDefinition() && "Cannot get key function for forward decl!")(static_cast <bool> (RD->getDefinition() && "Cannot get key function for forward decl!"
) ? void (0) : __assert_fail ("RD->getDefinition() && \"Cannot get key function for forward decl!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3366, __extension__
__PRETTY_FUNCTION__))
;
3367 RD = RD->getDefinition();
3368
3369 // Beware:
3370 // 1) computing the key function might trigger deserialization, which might
3371 // invalidate iterators into KeyFunctions
3372 // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3373 // invalidate the LazyDeclPtr within the map itself
3374 LazyDeclPtr Entry = KeyFunctions[RD];
3375 const Decl *Result =
3376 Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3377
3378 // Store it back if it changed.
3379 if (Entry.isOffset() || Entry.isValid() != bool(Result))
3380 KeyFunctions[RD] = const_cast<Decl*>(Result);
3381
3382 return cast_or_null<CXXMethodDecl>(Result);
3383}
3384
3385void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
3386 assert(Method == Method->getFirstDecl() &&(static_cast <bool> (Method == Method->getFirstDecl(
) && "not working with method declaration from class definition"
) ? void (0) : __assert_fail ("Method == Method->getFirstDecl() && \"not working with method declaration from class definition\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3387, __extension__
__PRETTY_FUNCTION__))
3387 "not working with method declaration from class definition")(static_cast <bool> (Method == Method->getFirstDecl(
) && "not working with method declaration from class definition"
) ? void (0) : __assert_fail ("Method == Method->getFirstDecl() && \"not working with method declaration from class definition\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3387, __extension__
__PRETTY_FUNCTION__))
;
3388
3389 // Look up the cache entry. Since we're working with the first
3390 // declaration, its parent must be the class definition, which is
3391 // the correct key for the KeyFunctions hash.
3392 const auto &Map = KeyFunctions;
3393 auto I = Map.find(Method->getParent());
3394
3395 // If it's not cached, there's nothing to do.
3396 if (I == Map.end()) return;
3397
3398 // If it is cached, check whether it's the target method, and if so,
3399 // remove it from the cache. Note, the call to 'get' might invalidate
3400 // the iterator and the LazyDeclPtr object within the map.
3401 LazyDeclPtr Ptr = I->second;
3402 if (Ptr.get(getExternalSource()) == Method) {
3403 // FIXME: remember that we did this for module / chained PCH state?
3404 KeyFunctions.erase(Method->getParent());
3405 }
3406}
3407
3408static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3409 const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3410 return Layout.getFieldOffset(FD->getFieldIndex());
3411}
3412
3413uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3414 uint64_t OffsetInBits;
3415 if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3416 OffsetInBits = ::getFieldOffset(*this, FD);
3417 } else {
3418 const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3419
3420 OffsetInBits = 0;
3421 for (const NamedDecl *ND : IFD->chain())
3422 OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3423 }
3424
3425 return OffsetInBits;
3426}
3427
3428uint64_t ASTContext::lookupFieldBitOffset(const ObjCInterfaceDecl *OID,
3429 const ObjCImplementationDecl *ID,
3430 const ObjCIvarDecl *Ivar) const {
3431 Ivar = Ivar->getCanonicalDecl();
3432 const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3433
3434 // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3435 // in here; it should never be necessary because that should be the lexical
3436 // decl context for the ivar.
3437
3438 // If we know have an implementation (and the ivar is in it) then
3439 // look up in the implementation layout.
3440 const ASTRecordLayout *RL;
3441 if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3442 RL = &getASTObjCImplementationLayout(ID);
3443 else
3444 RL = &getASTObjCInterfaceLayout(Container);
3445
3446 // Compute field index.
3447 //
3448 // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3449 // implemented. This should be fixed to get the information from the layout
3450 // directly.
3451 unsigned Index = 0;
3452
3453 for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3454 IVD; IVD = IVD->getNextIvar()) {
3455 if (Ivar == IVD)
3456 break;
3457 ++Index;
3458 }
3459 assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!")(static_cast <bool> (Index < RL->getFieldCount() &&
"Ivar is not inside record layout!") ? void (0) : __assert_fail
("Index < RL->getFieldCount() && \"Ivar is not inside record layout!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3459, __extension__
__PRETTY_FUNCTION__))
;
3460
3461 return RL->getFieldOffset(Index);
3462}
3463
3464/// getObjCLayout - Get or compute information about the layout of the
3465/// given interface.
3466///
3467/// \param Impl - If given, also include the layout of the interface's
3468/// implementation. This may differ by including synthesized ivars.
3469const ASTRecordLayout &
3470ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3471 const ObjCImplementationDecl *Impl) const {
3472 // Retrieve the definition
3473 if (D->hasExternalLexicalStorage() && !D->getDefinition())
3474 getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3475 D = D->getDefinition();
3476 assert(D && !D->isInvalidDecl() && D->isThisDeclarationADefinition() &&(static_cast <bool> (D && !D->isInvalidDecl(
) && D->isThisDeclarationADefinition() && "Invalid interface decl!"
) ? void (0) : __assert_fail ("D && !D->isInvalidDecl() && D->isThisDeclarationADefinition() && \"Invalid interface decl!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3477, __extension__
__PRETTY_FUNCTION__))
3477 "Invalid interface decl!")(static_cast <bool> (D && !D->isInvalidDecl(
) && D->isThisDeclarationADefinition() && "Invalid interface decl!"
) ? void (0) : __assert_fail ("D && !D->isInvalidDecl() && D->isThisDeclarationADefinition() && \"Invalid interface decl!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3477, __extension__
__PRETTY_FUNCTION__))
;
3478
3479 // Look up this layout, if already laid out, return what we have.
3480 const ObjCContainerDecl *Key =
3481 Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3482 if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3483 return *Entry;
3484
3485 // Add in synthesized ivar count if laying out an implementation.
3486 if (Impl) {
3487 unsigned SynthCount = CountNonClassIvars(D);
3488 // If there aren't any synthesized ivars then reuse the interface
3489 // entry. Note we can't cache this because we simply free all
3490 // entries later; however we shouldn't look up implementations
3491 // frequently.
3492 if (SynthCount == 0)
3493 return getObjCLayout(D, nullptr);
3494 }
3495
3496 ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3497 Builder.Layout(D);
3498
3499 const ASTRecordLayout *NewEntry = new (*this) ASTRecordLayout(
3500 *this, Builder.getSize(), Builder.Alignment, Builder.PreferredAlignment,
3501 Builder.UnadjustedAlignment,
3502 /*RequiredAlignment : used by MS-ABI)*/
3503 Builder.Alignment, Builder.getDataSize(), Builder.FieldOffsets);
3504
3505 ObjCLayouts[Key] = NewEntry;
3506
3507 return *NewEntry;
3508}
3509
3510static void PrintOffset(raw_ostream &OS,
3511 CharUnits Offset, unsigned IndentLevel) {
3512 OS << llvm::format("%10" PRId64"l" "d" " | ", (int64_t)Offset.getQuantity());
3513 OS.indent(IndentLevel * 2);
3514}
3515
3516static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3517 unsigned Begin, unsigned Width,
3518 unsigned IndentLevel) {
3519 llvm::SmallString<10> Buffer;
3520 {
3521 llvm::raw_svector_ostream BufferOS(Buffer);
3522 BufferOS << Offset.getQuantity() << ':';
3523 if (Width == 0) {
3524 BufferOS << '-';
3525 } else {
3526 BufferOS << Begin << '-' << (Begin + Width - 1);
3527 }
3528 }
3529
3530 OS << llvm::right_justify(Buffer, 10) << " | ";
3531 OS.indent(IndentLevel * 2);
3532}
3533
3534static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3535 OS << " | ";
3536 OS.indent(IndentLevel * 2);
3537}
3538
3539static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3540 const ASTContext &C,
3541 CharUnits Offset,
3542 unsigned IndentLevel,
3543 const char* Description,
3544 bool PrintSizeInfo,
3545 bool IncludeVirtualBases) {
3546 const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
4
Calling 'ASTContext::getASTRecordLayout'
3547 auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3548
3549 PrintOffset(OS, Offset, IndentLevel);
3550 OS << C.getTypeDeclType(const_cast<RecordDecl *>(RD));
3551 if (Description)
3552 OS << ' ' << Description;
3553 if (CXXRD && CXXRD->isEmpty())
3554 OS << " (empty)";
3555 OS << '\n';
3556
3557 IndentLevel++;
3558
3559 // Dump bases.
3560 if (CXXRD) {
3561 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3562 bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3563 bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3564
3565 // Vtable pointer.
3566 if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3567 PrintOffset(OS, Offset, IndentLevel);
3568 OS << '(' << *RD << " vtable pointer)\n";
3569 } else if (HasOwnVFPtr) {
3570 PrintOffset(OS, Offset, IndentLevel);
3571 // vfptr (for Microsoft C++ ABI)
3572 OS << '(' << *RD << " vftable pointer)\n";
3573 }
3574
3575 // Collect nvbases.
3576 SmallVector<const CXXRecordDecl *, 4> Bases;
3577 for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3578 assert(!Base.getType()->isDependentType() &&(static_cast <bool> (!Base.getType()->isDependentType
() && "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3579, __extension__
__PRETTY_FUNCTION__))
3579 "Cannot layout class with dependent bases.")(static_cast <bool> (!Base.getType()->isDependentType
() && "Cannot layout class with dependent bases.") ? void
(0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3579, __extension__
__PRETTY_FUNCTION__))
;
3580 if (!Base.isVirtual())
3581 Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3582 }
3583
3584 // Sort nvbases by offset.
3585 llvm::stable_sort(
3586 Bases, [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3587 return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3588 });
3589
3590 // Dump (non-virtual) bases
3591 for (const CXXRecordDecl *Base : Bases) {
3592 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3593 DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3594 Base == PrimaryBase ? "(primary base)" : "(base)",
3595 /*PrintSizeInfo=*/false,
3596 /*IncludeVirtualBases=*/false);
3597 }
3598
3599 // vbptr (for Microsoft C++ ABI)
3600 if (HasOwnVBPtr) {
3601 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3602 OS << '(' << *RD << " vbtable pointer)\n";
3603 }
3604 }
3605
3606 // Dump fields.
3607 uint64_t FieldNo = 0;
3608 for (RecordDecl::field_iterator I = RD->field_begin(),
3609 E = RD->field_end(); I != E; ++I, ++FieldNo) {
3610 const FieldDecl &Field = **I;
3611 uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3612 CharUnits FieldOffset =
3613 Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3614
3615 // Recursively dump fields of record type.
3616 if (auto RT = Field.getType()->getAs<RecordType>()) {
3617 DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3618 Field.getName().data(),
3619 /*PrintSizeInfo=*/false,
3620 /*IncludeVirtualBases=*/true);
3621 continue;
3622 }
3623
3624 if (Field.isBitField()) {
3625 uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3626 unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3627 unsigned Width = Field.getBitWidthValue(C);
3628 PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3629 } else {
3630 PrintOffset(OS, FieldOffset, IndentLevel);
3631 }
3632 const QualType &FieldType = C.getLangOpts().DumpRecordLayoutsCanonical
3633 ? Field.getType().getCanonicalType()
3634 : Field.getType();
3635 OS << FieldType << ' ' << Field << '\n';
3636 }
3637
3638 // Dump virtual bases.
3639 if (CXXRD && IncludeVirtualBases) {
3640 const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3641 Layout.getVBaseOffsetsMap();
3642
3643 for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3644 assert(Base.isVirtual() && "Found non-virtual class!")(static_cast <bool> (Base.isVirtual() && "Found non-virtual class!"
) ? void (0) : __assert_fail ("Base.isVirtual() && \"Found non-virtual class!\""
, "clang/lib/AST/RecordLayoutBuilder.cpp", 3644, __extension__
__PRETTY_FUNCTION__))
;
3645 const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3646
3647 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3648
3649 if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3650 PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3651 OS << "(vtordisp for vbase " << *VBase << ")\n";
3652 }
3653
3654 DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3655 VBase == Layout.getPrimaryBase() ?
3656 "(primary virtual base)" : "(virtual base)",
3657 /*PrintSizeInfo=*/false,
3658 /*IncludeVirtualBases=*/false);
3659 }
3660 }
3661
3662 if (!PrintSizeInfo) return;
3663
3664 PrintIndentNoOffset(OS, IndentLevel - 1);
3665 OS << "[sizeof=" << Layout.getSize().getQuantity();
3666 if (CXXRD && !isMsLayout(C))
3667 OS << ", dsize=" << Layout.getDataSize().getQuantity();
3668 OS << ", align=" << Layout.getAlignment().getQuantity();
3669 if (C.getTargetInfo().defaultsToAIXPowerAlignment())
3670 OS << ", preferredalign=" << Layout.getPreferredAlignment().getQuantity();
3671
3672 if (CXXRD) {
3673 OS << ",\n";
3674 PrintIndentNoOffset(OS, IndentLevel - 1);
3675 OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3676 OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3677 if (C.getTargetInfo().defaultsToAIXPowerAlignment())
3678 OS << ", preferrednvalign="
3679 << Layout.getPreferredNVAlignment().getQuantity();
3680 }
3681 OS << "]\n";
3682}
3683
3684void ASTContext::DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS,
3685 bool Simple) const {
3686 if (!Simple) {
1
Assuming 'Simple' is false
2
Taking true branch
3687 ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3
Calling 'DumpRecordLayout'
3688 /*PrintSizeInfo*/ true,
3689 /*IncludeVirtualBases=*/true);
3690 return;
3691 }
3692
3693 // The "simple" format is designed to be parsed by the
3694 // layout-override testing code. There shouldn't be any external
3695 // uses of this format --- when LLDB overrides a layout, it sets up
3696 // the data structures directly --- so feel free to adjust this as
3697 // you like as long as you also update the rudimentary parser for it
3698 // in libFrontend.
3699
3700 const ASTRecordLayout &Info = getASTRecordLayout(RD);
3701 OS << "Type: " << getTypeDeclType(RD) << "\n";
3702 OS << "\nLayout: ";
3703 OS << "<ASTRecordLayout\n";
3704 OS << " Size:" << toBits(Info.getSize()) << "\n";
3705 if (!isMsLayout(*this))
3706 OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3707 OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3708 if (Target->defaultsToAIXPowerAlignment())
3709 OS << " PreferredAlignment:" << toBits(Info.getPreferredAlignment())
3710 << "\n";
3711 OS << " FieldOffsets: [";
3712 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3713 if (i)
3714 OS << ", ";
3715 OS << Info.getFieldOffset(i);
3716 }
3717 OS << "]>\n";
3718}