Bug Summary

File:tools/clang/lib/AST/RecordLayoutBuilder.cpp
Warning:line 1155, column 10
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name RecordLayoutBuilder.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn374877/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn374877/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn374877=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-10-15-233810-7101-1 -x c++ /build/llvm-toolchain-snapshot-10~svn374877/tools/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/RecordLayout.h"
10#include "clang/AST/ASTContext.h"
11#include "clang/AST/ASTDiagnostic.h"
12#include "clang/AST/Attr.h"
13#include "clang/AST/CXXInheritance.h"
14#include "clang/AST/Decl.h"
15#include "clang/AST/DeclCXX.h"
16#include "clang/AST/DeclObjC.h"
17#include "clang/AST/Expr.h"
18#include "clang/Basic/TargetInfo.h"
19#include "llvm/ADT/SmallSet.h"
20#include "llvm/Support/Format.h"
21#include "llvm/Support/MathExtras.h"
22
23using namespace clang;
24
25namespace {
26
27/// BaseSubobjectInfo - Represents a single base subobject in a complete class.
28/// For a class hierarchy like
29///
30/// class A { };
31/// class B : A { };
32/// class C : A, B { };
33///
34/// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
35/// instances, one for B and two for A.
36///
37/// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
38struct BaseSubobjectInfo {
39 /// Class - The class for this base info.
40 const CXXRecordDecl *Class;
41
42 /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
43 bool IsVirtual;
44
45 /// Bases - Information about the base subobjects.
46 SmallVector<BaseSubobjectInfo*, 4> Bases;
47
48 /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
49 /// of this base info (if one exists).
50 BaseSubobjectInfo *PrimaryVirtualBaseInfo;
51
52 // FIXME: Document.
53 const BaseSubobjectInfo *Derived;
54};
55
56/// Externally provided layout. Typically used when the AST source, such
57/// as DWARF, lacks all the information that was available at compile time, such
58/// as alignment attributes on fields and pragmas in effect.
59struct ExternalLayout {
60 ExternalLayout() : Size(0), Align(0) {}
61
62 /// Overall record size in bits.
63 uint64_t Size;
64
65 /// Overall record alignment in bits.
66 uint64_t Align;
67
68 /// Record field offsets in bits.
69 llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
70
71 /// Direct, non-virtual base offsets.
72 llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
73
74 /// Virtual base offsets.
75 llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
76
77 /// Get the offset of the given field. The external source must provide
78 /// entries for all fields in the record.
79 uint64_t getExternalFieldOffset(const FieldDecl *FD) {
80 assert(FieldOffsets.count(FD) &&((FieldOffsets.count(FD) && "Field does not have an external offset"
) ? static_cast<void> (0) : __assert_fail ("FieldOffsets.count(FD) && \"Field does not have an external offset\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 81, __PRETTY_FUNCTION__))
81 "Field does not have an external offset")((FieldOffsets.count(FD) && "Field does not have an external offset"
) ? static_cast<void> (0) : __assert_fail ("FieldOffsets.count(FD) && \"Field does not have an external offset\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 81, __PRETTY_FUNCTION__))
;
82 return FieldOffsets[FD];
83 }
84
85 bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
86 auto Known = BaseOffsets.find(RD);
87 if (Known == BaseOffsets.end())
88 return false;
89 BaseOffset = Known->second;
90 return true;
91 }
92
93 bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
94 auto Known = VirtualBaseOffsets.find(RD);
95 if (Known == VirtualBaseOffsets.end())
96 return false;
97 BaseOffset = Known->second;
98 return true;
99 }
100};
101
102/// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
103/// offsets while laying out a C++ class.
104class EmptySubobjectMap {
105 const ASTContext &Context;
106 uint64_t CharWidth;
107
108 /// Class - The class whose empty entries we're keeping track of.
109 const CXXRecordDecl *Class;
110
111 /// EmptyClassOffsets - A map from offsets to empty record decls.
112 typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
113 typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
114 EmptyClassOffsetsMapTy EmptyClassOffsets;
115
116 /// MaxEmptyClassOffset - The highest offset known to contain an empty
117 /// base subobject.
118 CharUnits MaxEmptyClassOffset;
119
120 /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
121 /// member subobject that is empty.
122 void ComputeEmptySubobjectSizes();
123
124 void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
125
126 void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
127 CharUnits Offset, bool PlacingEmptyBase);
128
129 void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
130 const CXXRecordDecl *Class, CharUnits Offset,
131 bool PlacingOverlappingField);
132 void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset,
133 bool PlacingOverlappingField);
134
135 /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
136 /// subobjects beyond the given offset.
137 bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
138 return Offset <= MaxEmptyClassOffset;
139 }
140
141 CharUnits
142 getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
143 uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
144 assert(FieldOffset % CharWidth == 0 &&((FieldOffset % CharWidth == 0 && "Field offset not at char boundary!"
) ? static_cast<void> (0) : __assert_fail ("FieldOffset % CharWidth == 0 && \"Field offset not at char boundary!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 145, __PRETTY_FUNCTION__))
145 "Field offset not at char boundary!")((FieldOffset % CharWidth == 0 && "Field offset not at char boundary!"
) ? static_cast<void> (0) : __assert_fail ("FieldOffset % CharWidth == 0 && \"Field offset not at char boundary!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 145, __PRETTY_FUNCTION__))
;
146
147 return Context.toCharUnitsFromBits(FieldOffset);
148 }
149
150protected:
151 bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
152 CharUnits Offset) const;
153
154 bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
155 CharUnits Offset);
156
157 bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
158 const CXXRecordDecl *Class,
159 CharUnits Offset) const;
160 bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
161 CharUnits Offset) const;
162
163public:
164 /// This holds the size of the largest empty subobject (either a base
165 /// or a member). Will be zero if the record being built doesn't contain
166 /// any empty classes.
167 CharUnits SizeOfLargestEmptySubobject;
168
169 EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
170 : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
171 ComputeEmptySubobjectSizes();
172 }
173
174 /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
175 /// at the given offset.
176 /// Returns false if placing the record will result in two components
177 /// (direct or indirect) of the same type having the same offset.
178 bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
179 CharUnits Offset);
180
181 /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
182 /// offset.
183 bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
184};
185
186void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
187 // Check the bases.
188 for (const CXXBaseSpecifier &Base : Class->bases()) {
189 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
190
191 CharUnits EmptySize;
192 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
193 if (BaseDecl->isEmpty()) {
194 // If the class decl is empty, get its size.
195 EmptySize = Layout.getSize();
196 } else {
197 // Otherwise, we get the largest empty subobject for the decl.
198 EmptySize = Layout.getSizeOfLargestEmptySubobject();
199 }
200
201 if (EmptySize > SizeOfLargestEmptySubobject)
202 SizeOfLargestEmptySubobject = EmptySize;
203 }
204
205 // Check the fields.
206 for (const FieldDecl *FD : Class->fields()) {
207 const RecordType *RT =
208 Context.getBaseElementType(FD->getType())->getAs<RecordType>();
209
210 // We only care about record types.
211 if (!RT)
212 continue;
213
214 CharUnits EmptySize;
215 const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
216 const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
217 if (MemberDecl->isEmpty()) {
218 // If the class decl is empty, get its size.
219 EmptySize = Layout.getSize();
220 } else {
221 // Otherwise, we get the largest empty subobject for the decl.
222 EmptySize = Layout.getSizeOfLargestEmptySubobject();
223 }
224
225 if (EmptySize > SizeOfLargestEmptySubobject)
226 SizeOfLargestEmptySubobject = EmptySize;
227 }
228}
229
230bool
231EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
232 CharUnits Offset) const {
233 // We only need to check empty bases.
234 if (!RD->isEmpty())
235 return true;
236
237 EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
238 if (I == EmptyClassOffsets.end())
239 return true;
240
241 const ClassVectorTy &Classes = I->second;
242 if (llvm::find(Classes, RD) == Classes.end())
243 return true;
244
245 // There is already an empty class of the same type at this offset.
246 return false;
247}
248
249void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
250 CharUnits Offset) {
251 // We only care about empty bases.
252 if (!RD->isEmpty())
253 return;
254
255 // If we have empty structures inside a union, we can assign both
256 // the same offset. Just avoid pushing them twice in the list.
257 ClassVectorTy &Classes = EmptyClassOffsets[Offset];
258 if (llvm::is_contained(Classes, RD))
259 return;
260
261 Classes.push_back(RD);
262
263 // Update the empty class offset.
264 if (Offset > MaxEmptyClassOffset)
265 MaxEmptyClassOffset = Offset;
266}
267
268bool
269EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
270 CharUnits Offset) {
271 // We don't have to keep looking past the maximum offset that's known to
272 // contain an empty class.
273 if (!AnyEmptySubobjectsBeyondOffset(Offset))
274 return true;
275
276 if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
277 return false;
278
279 // Traverse all non-virtual bases.
280 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
281 for (const BaseSubobjectInfo *Base : Info->Bases) {
282 if (Base->IsVirtual)
283 continue;
284
285 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
286
287 if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
288 return false;
289 }
290
291 if (Info->PrimaryVirtualBaseInfo) {
292 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
293
294 if (Info == PrimaryVirtualBaseInfo->Derived) {
295 if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
296 return false;
297 }
298 }
299
300 // Traverse all member variables.
301 unsigned FieldNo = 0;
302 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
303 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
304 if (I->isBitField())
305 continue;
306
307 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
308 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
309 return false;
310 }
311
312 return true;
313}
314
315void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
316 CharUnits Offset,
317 bool PlacingEmptyBase) {
318 if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
319 // We know that the only empty subobjects that can conflict with empty
320 // subobject of non-empty bases, are empty bases that can be placed at
321 // offset zero. Because of this, we only need to keep track of empty base
322 // subobjects with offsets less than the size of the largest empty
323 // subobject for our class.
324 return;
325 }
326
327 AddSubobjectAtOffset(Info->Class, Offset);
328
329 // Traverse all non-virtual bases.
330 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
331 for (const BaseSubobjectInfo *Base : Info->Bases) {
332 if (Base->IsVirtual)
333 continue;
334
335 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
336 UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
337 }
338
339 if (Info->PrimaryVirtualBaseInfo) {
340 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
341
342 if (Info == PrimaryVirtualBaseInfo->Derived)
343 UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
344 PlacingEmptyBase);
345 }
346
347 // Traverse all member variables.
348 unsigned FieldNo = 0;
349 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
350 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
351 if (I->isBitField())
352 continue;
353
354 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
355 UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingEmptyBase);
356 }
357}
358
359bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
360 CharUnits Offset) {
361 // If we know this class doesn't have any empty subobjects we don't need to
362 // bother checking.
363 if (SizeOfLargestEmptySubobject.isZero())
364 return true;
365
366 if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
367 return false;
368
369 // We are able to place the base at this offset. Make sure to update the
370 // empty base subobject map.
371 UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
372 return true;
373}
374
375bool
376EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
377 const CXXRecordDecl *Class,
378 CharUnits Offset) const {
379 // We don't have to keep looking past the maximum offset that's known to
380 // contain an empty class.
381 if (!AnyEmptySubobjectsBeyondOffset(Offset))
382 return true;
383
384 if (!CanPlaceSubobjectAtOffset(RD, Offset))
385 return false;
386
387 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
388
389 // Traverse all non-virtual bases.
390 for (const CXXBaseSpecifier &Base : RD->bases()) {
391 if (Base.isVirtual())
392 continue;
393
394 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
395
396 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
397 if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
398 return false;
399 }
400
401 if (RD == Class) {
402 // This is the most derived class, traverse virtual bases as well.
403 for (const CXXBaseSpecifier &Base : RD->vbases()) {
404 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
405
406 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
407 if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
408 return false;
409 }
410 }
411
412 // Traverse all member variables.
413 unsigned FieldNo = 0;
414 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
415 I != E; ++I, ++FieldNo) {
416 if (I->isBitField())
417 continue;
418
419 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
420
421 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
422 return false;
423 }
424
425 return true;
426}
427
428bool
429EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
430 CharUnits Offset) const {
431 // We don't have to keep looking past the maximum offset that's known to
432 // contain an empty class.
433 if (!AnyEmptySubobjectsBeyondOffset(Offset))
434 return true;
435
436 QualType T = FD->getType();
437 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
438 return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
439
440 // If we have an array type we need to look at every element.
441 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
442 QualType ElemTy = Context.getBaseElementType(AT);
443 const RecordType *RT = ElemTy->getAs<RecordType>();
444 if (!RT)
445 return true;
446
447 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
448 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
449
450 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
451 CharUnits ElementOffset = Offset;
452 for (uint64_t I = 0; I != NumElements; ++I) {
453 // We don't have to keep looking past the maximum offset that's known to
454 // contain an empty class.
455 if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
456 return true;
457
458 if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
459 return false;
460
461 ElementOffset += Layout.getSize();
462 }
463 }
464
465 return true;
466}
467
468bool
469EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
470 CharUnits Offset) {
471 if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
472 return false;
473
474 // We are able to place the member variable at this offset.
475 // Make sure to update the empty field subobject map.
476 UpdateEmptyFieldSubobjects(FD, Offset, FD->hasAttr<NoUniqueAddressAttr>());
477 return true;
478}
479
480void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
481 const CXXRecordDecl *RD, const CXXRecordDecl *Class, CharUnits Offset,
482 bool PlacingOverlappingField) {
483 // We know that the only empty subobjects that can conflict with empty
484 // field subobjects are subobjects of empty bases and potentially-overlapping
485 // fields that can be placed at offset zero. Because of this, we only need to
486 // keep track of empty field subobjects with offsets less than the size of
487 // the largest empty subobject for our class.
488 //
489 // (Proof: we will only consider placing a subobject at offset zero or at
490 // >= the current dsize. The only cases where the earlier subobject can be
491 // placed beyond the end of dsize is if it's an empty base or a
492 // potentially-overlapping field.)
493 if (!PlacingOverlappingField && Offset >= SizeOfLargestEmptySubobject)
494 return;
495
496 AddSubobjectAtOffset(RD, Offset);
497
498 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
499
500 // Traverse all non-virtual bases.
501 for (const CXXBaseSpecifier &Base : RD->bases()) {
502 if (Base.isVirtual())
503 continue;
504
505 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
506
507 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
508 UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset,
509 PlacingOverlappingField);
510 }
511
512 if (RD == Class) {
513 // This is the most derived class, traverse virtual bases as well.
514 for (const CXXBaseSpecifier &Base : RD->vbases()) {
515 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
516
517 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
518 UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset,
519 PlacingOverlappingField);
520 }
521 }
522
523 // Traverse all member variables.
524 unsigned FieldNo = 0;
525 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
526 I != E; ++I, ++FieldNo) {
527 if (I->isBitField())
528 continue;
529
530 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
531
532 UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingOverlappingField);
533 }
534}
535
536void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
537 const FieldDecl *FD, CharUnits Offset, bool PlacingOverlappingField) {
538 QualType T = FD->getType();
539 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
540 UpdateEmptyFieldSubobjects(RD, RD, Offset, PlacingOverlappingField);
541 return;
542 }
543
544 // If we have an array type we need to update every element.
545 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
546 QualType ElemTy = Context.getBaseElementType(AT);
547 const RecordType *RT = ElemTy->getAs<RecordType>();
548 if (!RT)
549 return;
550
551 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
552 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
553
554 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
555 CharUnits ElementOffset = Offset;
556
557 for (uint64_t I = 0; I != NumElements; ++I) {
558 // We know that the only empty subobjects that can conflict with empty
559 // field subobjects are subobjects of empty bases that can be placed at
560 // offset zero. Because of this, we only need to keep track of empty field
561 // subobjects with offsets less than the size of the largest empty
562 // subobject for our class.
563 if (!PlacingOverlappingField &&
564 ElementOffset >= SizeOfLargestEmptySubobject)
565 return;
566
567 UpdateEmptyFieldSubobjects(RD, RD, ElementOffset,
568 PlacingOverlappingField);
569 ElementOffset += Layout.getSize();
570 }
571 }
572}
573
574typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
575
576class ItaniumRecordLayoutBuilder {
577protected:
578 // FIXME: Remove this and make the appropriate fields public.
579 friend class clang::ASTContext;
580
581 const ASTContext &Context;
582
583 EmptySubobjectMap *EmptySubobjects;
584
585 /// Size - The current size of the record layout.
586 uint64_t Size;
587
588 /// Alignment - The current alignment of the record layout.
589 CharUnits Alignment;
590
591 /// The alignment if attribute packed is not used.
592 CharUnits UnpackedAlignment;
593
594 /// \brief The maximum of the alignments of top-level members.
595 CharUnits UnadjustedAlignment;
596
597 SmallVector<uint64_t, 16> FieldOffsets;
598
599 /// Whether the external AST source has provided a layout for this
600 /// record.
601 unsigned UseExternalLayout : 1;
602
603 /// Whether we need to infer alignment, even when we have an
604 /// externally-provided layout.
605 unsigned InferAlignment : 1;
606
607 /// Packed - Whether the record is packed or not.
608 unsigned Packed : 1;
609
610 unsigned IsUnion : 1;
611
612 unsigned IsMac68kAlign : 1;
613
614 unsigned IsMsStruct : 1;
615
616 /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
617 /// this contains the number of bits in the last unit that can be used for
618 /// an adjacent bitfield if necessary. The unit in question is usually
619 /// a byte, but larger units are used if IsMsStruct.
620 unsigned char UnfilledBitsInLastUnit;
621 /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
622 /// of the previous field if it was a bitfield.
623 unsigned char LastBitfieldTypeSize;
624
625 /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
626 /// #pragma pack.
627 CharUnits MaxFieldAlignment;
628
629 /// DataSize - The data size of the record being laid out.
630 uint64_t DataSize;
631
632 CharUnits NonVirtualSize;
633 CharUnits NonVirtualAlignment;
634
635 /// If we've laid out a field but not included its tail padding in Size yet,
636 /// this is the size up to the end of that field.
637 CharUnits PaddedFieldSize;
638
639 /// PrimaryBase - the primary base class (if one exists) of the class
640 /// we're laying out.
641 const CXXRecordDecl *PrimaryBase;
642
643 /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
644 /// out is virtual.
645 bool PrimaryBaseIsVirtual;
646
647 /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
648 /// pointer, as opposed to inheriting one from a primary base class.
649 bool HasOwnVFPtr;
650
651 /// the flag of field offset changing due to packed attribute.
652 bool HasPackedField;
653
654 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
655
656 /// Bases - base classes and their offsets in the record.
657 BaseOffsetsMapTy Bases;
658
659 // VBases - virtual base classes and their offsets in the record.
660 ASTRecordLayout::VBaseOffsetsMapTy VBases;
661
662 /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
663 /// primary base classes for some other direct or indirect base class.
664 CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
665
666 /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
667 /// inheritance graph order. Used for determining the primary base class.
668 const CXXRecordDecl *FirstNearlyEmptyVBase;
669
670 /// VisitedVirtualBases - A set of all the visited virtual bases, used to
671 /// avoid visiting virtual bases more than once.
672 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
673
674 /// Valid if UseExternalLayout is true.
675 ExternalLayout External;
676
677 ItaniumRecordLayoutBuilder(const ASTContext &Context,
678 EmptySubobjectMap *EmptySubobjects)
679 : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
680 Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
681 UnadjustedAlignment(CharUnits::One()),
682 UseExternalLayout(false), InferAlignment(false), Packed(false),
683 IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
684 UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
685 MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
686 NonVirtualSize(CharUnits::Zero()),
687 NonVirtualAlignment(CharUnits::One()),
688 PaddedFieldSize(CharUnits::Zero()), PrimaryBase(nullptr),
689 PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
690 HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
691
692 void Layout(const RecordDecl *D);
693 void Layout(const CXXRecordDecl *D);
694 void Layout(const ObjCInterfaceDecl *D);
695
696 void LayoutFields(const RecordDecl *D);
697 void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
698 void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
699 bool FieldPacked, const FieldDecl *D);
700 void LayoutBitField(const FieldDecl *D);
701
702 TargetCXXABI getCXXABI() const {
703 return Context.getTargetInfo().getCXXABI();
704 }
705
706 /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
707 llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
708
709 typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
710 BaseSubobjectInfoMapTy;
711
712 /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
713 /// of the class we're laying out to their base subobject info.
714 BaseSubobjectInfoMapTy VirtualBaseInfo;
715
716 /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
717 /// class we're laying out to their base subobject info.
718 BaseSubobjectInfoMapTy NonVirtualBaseInfo;
719
720 /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
721 /// bases of the given class.
722 void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
723
724 /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
725 /// single class and all of its base classes.
726 BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
727 bool IsVirtual,
728 BaseSubobjectInfo *Derived);
729
730 /// DeterminePrimaryBase - Determine the primary base of the given class.
731 void DeterminePrimaryBase(const CXXRecordDecl *RD);
732
733 void SelectPrimaryVBase(const CXXRecordDecl *RD);
734
735 void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
736
737 /// LayoutNonVirtualBases - Determines the primary base class (if any) and
738 /// lays it out. Will then proceed to lay out all non-virtual base clasess.
739 void LayoutNonVirtualBases(const CXXRecordDecl *RD);
740
741 /// LayoutNonVirtualBase - Lays out a single non-virtual base.
742 void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
743
744 void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
745 CharUnits Offset);
746
747 /// LayoutVirtualBases - Lays out all the virtual bases.
748 void LayoutVirtualBases(const CXXRecordDecl *RD,
749 const CXXRecordDecl *MostDerivedClass);
750
751 /// LayoutVirtualBase - Lays out a single virtual base.
752 void LayoutVirtualBase(const BaseSubobjectInfo *Base);
753
754 /// LayoutBase - Will lay out a base and return the offset where it was
755 /// placed, in chars.
756 CharUnits LayoutBase(const BaseSubobjectInfo *Base);
757
758 /// InitializeLayout - Initialize record layout for the given record decl.
759 void InitializeLayout(const Decl *D);
760
761 /// FinishLayout - Finalize record layout. Adjust record size based on the
762 /// alignment.
763 void FinishLayout(const NamedDecl *D);
764
765 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
766 void UpdateAlignment(CharUnits NewAlignment) {
767 UpdateAlignment(NewAlignment, NewAlignment);
768 }
769
770 /// Retrieve the externally-supplied field offset for the given
771 /// field.
772 ///
773 /// \param Field The field whose offset is being queried.
774 /// \param ComputedOffset The offset that we've computed for this field.
775 uint64_t updateExternalFieldOffset(const FieldDecl *Field,
776 uint64_t ComputedOffset);
777
778 void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
779 uint64_t UnpackedOffset, unsigned UnpackedAlign,
780 bool isPacked, const FieldDecl *D);
781
782 DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
783
784 CharUnits getSize() const {
785 assert(Size % Context.getCharWidth() == 0)((Size % Context.getCharWidth() == 0) ? static_cast<void>
(0) : __assert_fail ("Size % Context.getCharWidth() == 0", "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 785, __PRETTY_FUNCTION__))
;
786 return Context.toCharUnitsFromBits(Size);
787 }
788 uint64_t getSizeInBits() const { return Size; }
789
790 void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
791 void setSize(uint64_t NewSize) { Size = NewSize; }
792
793 CharUnits getAligment() const { return Alignment; }
794
795 CharUnits getDataSize() const {
796 assert(DataSize % Context.getCharWidth() == 0)((DataSize % Context.getCharWidth() == 0) ? static_cast<void
> (0) : __assert_fail ("DataSize % Context.getCharWidth() == 0"
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 796, __PRETTY_FUNCTION__))
;
797 return Context.toCharUnitsFromBits(DataSize);
798 }
799 uint64_t getDataSizeInBits() const { return DataSize; }
800
801 void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
802 void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
803
804 ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
805 void operator=(const ItaniumRecordLayoutBuilder &) = delete;
806};
807} // end anonymous namespace
808
809void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
810 for (const auto &I : RD->bases()) {
811 assert(!I.getType()->isDependentType() &&((!I.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!I.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 812, __PRETTY_FUNCTION__))
812 "Cannot layout class with dependent bases.")((!I.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!I.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 812, __PRETTY_FUNCTION__))
;
813
814 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
815
816 // Check if this is a nearly empty virtual base.
817 if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
818 // If it's not an indirect primary base, then we've found our primary
819 // base.
820 if (!IndirectPrimaryBases.count(Base)) {
821 PrimaryBase = Base;
822 PrimaryBaseIsVirtual = true;
823 return;
824 }
825
826 // Is this the first nearly empty virtual base?
827 if (!FirstNearlyEmptyVBase)
828 FirstNearlyEmptyVBase = Base;
829 }
830
831 SelectPrimaryVBase(Base);
832 if (PrimaryBase)
833 return;
834 }
835}
836
837/// DeterminePrimaryBase - Determine the primary base of the given class.
838void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
839 // If the class isn't dynamic, it won't have a primary base.
840 if (!RD->isDynamicClass())
841 return;
842
843 // Compute all the primary virtual bases for all of our direct and
844 // indirect bases, and record all their primary virtual base classes.
845 RD->getIndirectPrimaryBases(IndirectPrimaryBases);
846
847 // If the record has a dynamic base class, attempt to choose a primary base
848 // class. It is the first (in direct base class order) non-virtual dynamic
849 // base class, if one exists.
850 for (const auto &I : RD->bases()) {
851 // Ignore virtual bases.
852 if (I.isVirtual())
853 continue;
854
855 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
856
857 if (Base->isDynamicClass()) {
858 // We found it.
859 PrimaryBase = Base;
860 PrimaryBaseIsVirtual = false;
861 return;
862 }
863 }
864
865 // Under the Itanium ABI, if there is no non-virtual primary base class,
866 // try to compute the primary virtual base. The primary virtual base is
867 // the first nearly empty virtual base that is not an indirect primary
868 // virtual base class, if one exists.
869 if (RD->getNumVBases() != 0) {
870 SelectPrimaryVBase(RD);
871 if (PrimaryBase)
872 return;
873 }
874
875 // Otherwise, it is the first indirect primary base class, if one exists.
876 if (FirstNearlyEmptyVBase) {
877 PrimaryBase = FirstNearlyEmptyVBase;
878 PrimaryBaseIsVirtual = true;
879 return;
880 }
881
882 assert(!PrimaryBase && "Should not get here with a primary base!")((!PrimaryBase && "Should not get here with a primary base!"
) ? static_cast<void> (0) : __assert_fail ("!PrimaryBase && \"Should not get here with a primary base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 882, __PRETTY_FUNCTION__))
;
883}
884
885BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
886 const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
887 BaseSubobjectInfo *Info;
888
889 if (IsVirtual) {
890 // Check if we already have info about this virtual base.
891 BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
892 if (InfoSlot) {
893 assert(InfoSlot->Class == RD && "Wrong class for virtual base info!")((InfoSlot->Class == RD && "Wrong class for virtual base info!"
) ? static_cast<void> (0) : __assert_fail ("InfoSlot->Class == RD && \"Wrong class for virtual base info!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 893, __PRETTY_FUNCTION__))
;
894 return InfoSlot;
895 }
896
897 // We don't, create it.
898 InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
899 Info = InfoSlot;
900 } else {
901 Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
902 }
903
904 Info->Class = RD;
905 Info->IsVirtual = IsVirtual;
906 Info->Derived = nullptr;
907 Info->PrimaryVirtualBaseInfo = nullptr;
908
909 const CXXRecordDecl *PrimaryVirtualBase = nullptr;
910 BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
911
912 // Check if this base has a primary virtual base.
913 if (RD->getNumVBases()) {
914 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
915 if (Layout.isPrimaryBaseVirtual()) {
916 // This base does have a primary virtual base.
917 PrimaryVirtualBase = Layout.getPrimaryBase();
918 assert(PrimaryVirtualBase && "Didn't have a primary virtual base!")((PrimaryVirtualBase && "Didn't have a primary virtual base!"
) ? static_cast<void> (0) : __assert_fail ("PrimaryVirtualBase && \"Didn't have a primary virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 918, __PRETTY_FUNCTION__))
;
919
920 // Now check if we have base subobject info about this primary base.
921 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
922
923 if (PrimaryVirtualBaseInfo) {
924 if (PrimaryVirtualBaseInfo->Derived) {
925 // We did have info about this primary base, and it turns out that it
926 // has already been claimed as a primary virtual base for another
927 // base.
928 PrimaryVirtualBase = nullptr;
929 } else {
930 // We can claim this base as our primary base.
931 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
932 PrimaryVirtualBaseInfo->Derived = Info;
933 }
934 }
935 }
936 }
937
938 // Now go through all direct bases.
939 for (const auto &I : RD->bases()) {
940 bool IsVirtual = I.isVirtual();
941
942 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
943
944 Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
945 }
946
947 if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
948 // Traversing the bases must have created the base info for our primary
949 // virtual base.
950 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
951 assert(PrimaryVirtualBaseInfo &&((PrimaryVirtualBaseInfo && "Did not create a primary virtual base!"
) ? static_cast<void> (0) : __assert_fail ("PrimaryVirtualBaseInfo && \"Did not create a primary virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 952, __PRETTY_FUNCTION__))
952 "Did not create a primary virtual base!")((PrimaryVirtualBaseInfo && "Did not create a primary virtual base!"
) ? static_cast<void> (0) : __assert_fail ("PrimaryVirtualBaseInfo && \"Did not create a primary virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 952, __PRETTY_FUNCTION__))
;
953
954 // Claim the primary virtual base as our primary virtual base.
955 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
956 PrimaryVirtualBaseInfo->Derived = Info;
957 }
958
959 return Info;
960}
961
962void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
963 const CXXRecordDecl *RD) {
964 for (const auto &I : RD->bases()) {
965 bool IsVirtual = I.isVirtual();
966
967 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
968
969 // Compute the base subobject info for this base.
970 BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
971 nullptr);
972
973 if (IsVirtual) {
974 // ComputeBaseInfo has already added this base for us.
975 assert(VirtualBaseInfo.count(BaseDecl) &&((VirtualBaseInfo.count(BaseDecl) && "Did not add virtual base!"
) ? static_cast<void> (0) : __assert_fail ("VirtualBaseInfo.count(BaseDecl) && \"Did not add virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 976, __PRETTY_FUNCTION__))
976 "Did not add virtual base!")((VirtualBaseInfo.count(BaseDecl) && "Did not add virtual base!"
) ? static_cast<void> (0) : __assert_fail ("VirtualBaseInfo.count(BaseDecl) && \"Did not add virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 976, __PRETTY_FUNCTION__))
;
977 } else {
978 // Add the base info to the map of non-virtual bases.
979 assert(!NonVirtualBaseInfo.count(BaseDecl) &&((!NonVirtualBaseInfo.count(BaseDecl) && "Non-virtual base already exists!"
) ? static_cast<void> (0) : __assert_fail ("!NonVirtualBaseInfo.count(BaseDecl) && \"Non-virtual base already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 980, __PRETTY_FUNCTION__))
980 "Non-virtual base already exists!")((!NonVirtualBaseInfo.count(BaseDecl) && "Non-virtual base already exists!"
) ? static_cast<void> (0) : __assert_fail ("!NonVirtualBaseInfo.count(BaseDecl) && \"Non-virtual base already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 980, __PRETTY_FUNCTION__))
;
981 NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
982 }
983 }
984}
985
986void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
987 CharUnits UnpackedBaseAlign) {
988 CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;
989
990 // The maximum field alignment overrides base align.
991 if (!MaxFieldAlignment.isZero()) {
992 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
993 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
994 }
995
996 // Round up the current record size to pointer alignment.
997 setSize(getSize().alignTo(BaseAlign));
998
999 // Update the alignment.
1000 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1001}
1002
1003void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
1004 const CXXRecordDecl *RD) {
1005 // Then, determine the primary base class.
1006 DeterminePrimaryBase(RD);
1007
1008 // Compute base subobject info.
1009 ComputeBaseSubobjectInfo(RD);
1010
1011 // If we have a primary base class, lay it out.
1012 if (PrimaryBase) {
1013 if (PrimaryBaseIsVirtual) {
1014 // If the primary virtual base was a primary virtual base of some other
1015 // base class we'll have to steal it.
1016 BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1017 PrimaryBaseInfo->Derived = nullptr;
1018
1019 // We have a virtual primary base, insert it as an indirect primary base.
1020 IndirectPrimaryBases.insert(PrimaryBase);
1021
1022 assert(!VisitedVirtualBases.count(PrimaryBase) &&((!VisitedVirtualBases.count(PrimaryBase) && "vbase already visited!"
) ? static_cast<void> (0) : __assert_fail ("!VisitedVirtualBases.count(PrimaryBase) && \"vbase already visited!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1023, __PRETTY_FUNCTION__))
1023 "vbase already visited!")((!VisitedVirtualBases.count(PrimaryBase) && "vbase already visited!"
) ? static_cast<void> (0) : __assert_fail ("!VisitedVirtualBases.count(PrimaryBase) && \"vbase already visited!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1023, __PRETTY_FUNCTION__))
;
1024 VisitedVirtualBases.insert(PrimaryBase);
1025
1026 LayoutVirtualBase(PrimaryBaseInfo);
1027 } else {
1028 BaseSubobjectInfo *PrimaryBaseInfo =
1029 NonVirtualBaseInfo.lookup(PrimaryBase);
1030 assert(PrimaryBaseInfo &&((PrimaryBaseInfo && "Did not find base info for non-virtual primary base!"
) ? static_cast<void> (0) : __assert_fail ("PrimaryBaseInfo && \"Did not find base info for non-virtual primary base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1031, __PRETTY_FUNCTION__))
1031 "Did not find base info for non-virtual primary base!")((PrimaryBaseInfo && "Did not find base info for non-virtual primary base!"
) ? static_cast<void> (0) : __assert_fail ("PrimaryBaseInfo && \"Did not find base info for non-virtual primary base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1031, __PRETTY_FUNCTION__))
;
1032
1033 LayoutNonVirtualBase(PrimaryBaseInfo);
1034 }
1035
1036 // If this class needs a vtable/vf-table and didn't get one from a
1037 // primary base, add it in now.
1038 } else if (RD->isDynamicClass()) {
1039 assert(DataSize == 0 && "Vtable pointer must be at offset zero!")((DataSize == 0 && "Vtable pointer must be at offset zero!"
) ? static_cast<void> (0) : __assert_fail ("DataSize == 0 && \"Vtable pointer must be at offset zero!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1039, __PRETTY_FUNCTION__))
;
1040 CharUnits PtrWidth =
1041 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1042 CharUnits PtrAlign =
1043 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1044 EnsureVTablePointerAlignment(PtrAlign);
1045 HasOwnVFPtr = true;
1046 setSize(getSize() + PtrWidth);
1047 setDataSize(getSize());
1048 }
1049
1050 // Now lay out the non-virtual bases.
1051 for (const auto &I : RD->bases()) {
1052
1053 // Ignore virtual bases.
1054 if (I.isVirtual())
1055 continue;
1056
1057 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1058
1059 // Skip the primary base, because we've already laid it out. The
1060 // !PrimaryBaseIsVirtual check is required because we might have a
1061 // non-virtual base of the same type as a primary virtual base.
1062 if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1063 continue;
1064
1065 // Lay out the base.
1066 BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1067 assert(BaseInfo && "Did not find base info for non-virtual base!")((BaseInfo && "Did not find base info for non-virtual base!"
) ? static_cast<void> (0) : __assert_fail ("BaseInfo && \"Did not find base info for non-virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1067, __PRETTY_FUNCTION__))
;
1068
1069 LayoutNonVirtualBase(BaseInfo);
1070 }
1071}
1072
1073void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1074 const BaseSubobjectInfo *Base) {
1075 // Layout the base.
1076 CharUnits Offset = LayoutBase(Base);
1077
1078 // Add its base class offset.
1079 assert(!Bases.count(Base->Class) && "base offset already exists!")((!Bases.count(Base->Class) && "base offset already exists!"
) ? static_cast<void> (0) : __assert_fail ("!Bases.count(Base->Class) && \"base offset already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1079, __PRETTY_FUNCTION__))
;
1080 Bases.insert(std::make_pair(Base->Class, Offset));
1081
1082 AddPrimaryVirtualBaseOffsets(Base, Offset);
1083}
1084
1085void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1086 const BaseSubobjectInfo *Info, CharUnits Offset) {
1087 // This base isn't interesting, it has no virtual bases.
1088 if (!Info->Class->getNumVBases())
1089 return;
1090
1091 // First, check if we have a virtual primary base to add offsets for.
1092 if (Info->PrimaryVirtualBaseInfo) {
1093 assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&((Info->PrimaryVirtualBaseInfo->IsVirtual && "Primary virtual base is not virtual!"
) ? static_cast<void> (0) : __assert_fail ("Info->PrimaryVirtualBaseInfo->IsVirtual && \"Primary virtual base is not virtual!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1094, __PRETTY_FUNCTION__))
1094 "Primary virtual base is not virtual!")((Info->PrimaryVirtualBaseInfo->IsVirtual && "Primary virtual base is not virtual!"
) ? static_cast<void> (0) : __assert_fail ("Info->PrimaryVirtualBaseInfo->IsVirtual && \"Primary virtual base is not virtual!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1094, __PRETTY_FUNCTION__))
;
1095 if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1096 // Add the offset.
1097 assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&((!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
"primary vbase offset already exists!") ? static_cast<void
> (0) : __assert_fail ("!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && \"primary vbase offset already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1098, __PRETTY_FUNCTION__))
1098 "primary vbase offset already exists!")((!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
"primary vbase offset already exists!") ? static_cast<void
> (0) : __assert_fail ("!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && \"primary vbase offset already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1098, __PRETTY_FUNCTION__))
;
1099 VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1100 ASTRecordLayout::VBaseInfo(Offset, false)));
1101
1102 // Traverse the primary virtual base.
1103 AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1104 }
1105 }
1106
1107 // Now go through all direct non-virtual bases.
1108 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1109 for (const BaseSubobjectInfo *Base : Info->Bases) {
1110 if (Base->IsVirtual)
1111 continue;
1112
1113 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1114 AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1115 }
1116}
1117
1118void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1119 const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1120 const CXXRecordDecl *PrimaryBase;
1121 bool PrimaryBaseIsVirtual;
1122
1123 if (MostDerivedClass
17.1
'MostDerivedClass' is equal to 'RD'
== RD) {
18
Taking true branch
1124 PrimaryBase = this->PrimaryBase;
1125 PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1126 } else {
1127 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1128 PrimaryBase = Layout.getPrimaryBase();
1129 PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1130 }
1131
1132 for (const CXXBaseSpecifier &Base : RD->bases()) {
19
Assuming '__begin1' is not equal to '__end1'
1133 assert(!Base.getType()->isDependentType() &&((!Base.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1134, __PRETTY_FUNCTION__))
20
Assuming the condition is true
21
'?' condition is true
1134 "Cannot layout class with dependent bases.")((!Base.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1134, __PRETTY_FUNCTION__))
;
1135
1136 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
22
'BaseDecl' initialized here
1137
1138 if (Base.isVirtual()) {
23
Assuming the condition is true
24
Taking true branch
1139 if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
25
Assuming 'PrimaryBase' is equal to 'BaseDecl'
26
Assuming pointer value is null
27
Assuming 'PrimaryBaseIsVirtual' is true
28
Taking false branch
1140 bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1141
1142 // Only lay out the virtual base if it's not an indirect primary base.
1143 if (!IndirectPrimaryBase) {
1144 // Only visit virtual bases once.
1145 if (!VisitedVirtualBases.insert(BaseDecl).second)
1146 continue;
1147
1148 const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1149 assert(BaseInfo && "Did not find virtual base info!")((BaseInfo && "Did not find virtual base info!") ? static_cast
<void> (0) : __assert_fail ("BaseInfo && \"Did not find virtual base info!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1149, __PRETTY_FUNCTION__))
;
1150 LayoutVirtualBase(BaseInfo);
1151 }
1152 }
1153 }
1154
1155 if (!BaseDecl->getNumVBases()) {
29
Called C++ object pointer is null
1156 // This base isn't interesting since it doesn't have any virtual bases.
1157 continue;
1158 }
1159
1160 LayoutVirtualBases(BaseDecl, MostDerivedClass);
1161 }
1162}
1163
1164void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1165 const BaseSubobjectInfo *Base) {
1166 assert(!Base->Derived && "Trying to lay out a primary virtual base!")((!Base->Derived && "Trying to lay out a primary virtual base!"
) ? static_cast<void> (0) : __assert_fail ("!Base->Derived && \"Trying to lay out a primary virtual base!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1166, __PRETTY_FUNCTION__))
;
1167
1168 // Layout the base.
1169 CharUnits Offset = LayoutBase(Base);
1170
1171 // Add its base class offset.
1172 assert(!VBases.count(Base->Class) && "vbase offset already exists!")((!VBases.count(Base->Class) && "vbase offset already exists!"
) ? static_cast<void> (0) : __assert_fail ("!VBases.count(Base->Class) && \"vbase offset already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1172, __PRETTY_FUNCTION__))
;
1173 VBases.insert(std::make_pair(Base->Class,
1174 ASTRecordLayout::VBaseInfo(Offset, false)));
1175
1176 AddPrimaryVirtualBaseOffsets(Base, Offset);
1177}
1178
1179CharUnits
1180ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1181 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1182
1183
1184 CharUnits Offset;
1185
1186 // Query the external layout to see if it provides an offset.
1187 bool HasExternalLayout = false;
1188 if (UseExternalLayout) {
1189 // FIXME: This appears to be reversed.
1190 if (Base->IsVirtual)
1191 HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1192 else
1193 HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1194 }
1195
1196 // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
1197 // Per GCC's documentation, it only applies to non-static data members.
1198 CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1199 CharUnits BaseAlign =
1200 (Packed && ((Context.getLangOpts().getClangABICompat() <=
1201 LangOptions::ClangABI::Ver6) ||
1202 Context.getTargetInfo().getTriple().isPS4()))
1203 ? CharUnits::One()
1204 : UnpackedBaseAlign;
1205
1206 // If we have an empty base class, try to place it at offset 0.
1207 if (Base->Class->isEmpty() &&
1208 (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1209 EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1210 setSize(std::max(getSize(), Layout.getSize()));
1211 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1212
1213 return CharUnits::Zero();
1214 }
1215
1216 // The maximum field alignment overrides base align.
1217 if (!MaxFieldAlignment.isZero()) {
1218 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1219 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1220 }
1221
1222 if (!HasExternalLayout) {
1223 // Round up the current record size to the base's alignment boundary.
1224 Offset = getDataSize().alignTo(BaseAlign);
1225
1226 // Try to place the base.
1227 while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1228 Offset += BaseAlign;
1229 } else {
1230 bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1231 (void)Allowed;
1232 assert(Allowed && "Base subobject externally placed at overlapping offset")((Allowed && "Base subobject externally placed at overlapping offset"
) ? static_cast<void> (0) : __assert_fail ("Allowed && \"Base subobject externally placed at overlapping offset\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1232, __PRETTY_FUNCTION__))
;
1233
1234 if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1235 // The externally-supplied base offset is before the base offset we
1236 // computed. Assume that the structure is packed.
1237 Alignment = CharUnits::One();
1238 InferAlignment = false;
1239 }
1240 }
1241
1242 if (!Base->Class->isEmpty()) {
1243 // Update the data size.
1244 setDataSize(Offset + Layout.getNonVirtualSize());
1245
1246 setSize(std::max(getSize(), getDataSize()));
1247 } else
1248 setSize(std::max(getSize(), Offset + Layout.getSize()));
1249
1250 // Remember max struct/class alignment.
1251 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1252
1253 return Offset;
1254}
1255
1256void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1257 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1258 IsUnion = RD->isUnion();
1259 IsMsStruct = RD->isMsStruct(Context);
1260 }
1261
1262 Packed = D->hasAttr<PackedAttr>();
1263
1264 // Honor the default struct packing maximum alignment flag.
1265 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1266 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1267 }
1268
1269 // mac68k alignment supersedes maximum field alignment and attribute aligned,
1270 // and forces all structures to have 2-byte alignment. The IBM docs on it
1271 // allude to additional (more complicated) semantics, especially with regard
1272 // to bit-fields, but gcc appears not to follow that.
1273 if (D->hasAttr<AlignMac68kAttr>()) {
1274 IsMac68kAlign = true;
1275 MaxFieldAlignment = CharUnits::fromQuantity(2);
1276 Alignment = CharUnits::fromQuantity(2);
1277 } else {
1278 if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1279 MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1280
1281 if (unsigned MaxAlign = D->getMaxAlignment())
1282 UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1283 }
1284
1285 // If there is an external AST source, ask it for the various offsets.
1286 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1287 if (ExternalASTSource *Source = Context.getExternalSource()) {
1288 UseExternalLayout = Source->layoutRecordType(
1289 RD, External.Size, External.Align, External.FieldOffsets,
1290 External.BaseOffsets, External.VirtualBaseOffsets);
1291
1292 // Update based on external alignment.
1293 if (UseExternalLayout) {
1294 if (External.Align > 0) {
1295 Alignment = Context.toCharUnitsFromBits(External.Align);
1296 } else {
1297 // The external source didn't have alignment information; infer it.
1298 InferAlignment = true;
1299 }
1300 }
1301 }
1302}
1303
1304void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1305 InitializeLayout(D);
1306 LayoutFields(D);
1307
1308 // Finally, round the size of the total struct up to the alignment of the
1309 // struct itself.
1310 FinishLayout(D);
1311}
1312
1313void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1314 InitializeLayout(RD);
1315
1316 // Lay out the vtable and the non-virtual bases.
1317 LayoutNonVirtualBases(RD);
1318
1319 LayoutFields(RD);
1320
1321 NonVirtualSize = Context.toCharUnitsFromBits(
1322 llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1323 NonVirtualAlignment = Alignment;
1324
1325 // Lay out the virtual bases and add the primary virtual base offsets.
1326 LayoutVirtualBases(RD, RD);
17
Calling 'ItaniumRecordLayoutBuilder::LayoutVirtualBases'
1327
1328 // Finally, round the size of the total struct up to the alignment
1329 // of the struct itself.
1330 FinishLayout(RD);
1331
1332#ifndef NDEBUG
1333 // Check that we have base offsets for all bases.
1334 for (const CXXBaseSpecifier &Base : RD->bases()) {
1335 if (Base.isVirtual())
1336 continue;
1337
1338 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1339
1340 assert(Bases.count(BaseDecl) && "Did not find base offset!")((Bases.count(BaseDecl) && "Did not find base offset!"
) ? static_cast<void> (0) : __assert_fail ("Bases.count(BaseDecl) && \"Did not find base offset!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1340, __PRETTY_FUNCTION__))
;
1341 }
1342
1343 // And all virtual bases.
1344 for (const CXXBaseSpecifier &Base : RD->vbases()) {
1345 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1346
1347 assert(VBases.count(BaseDecl) && "Did not find base offset!")((VBases.count(BaseDecl) && "Did not find base offset!"
) ? static_cast<void> (0) : __assert_fail ("VBases.count(BaseDecl) && \"Did not find base offset!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1347, __PRETTY_FUNCTION__))
;
1348 }
1349#endif
1350}
1351
1352void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1353 if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1354 const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1355
1356 UpdateAlignment(SL.getAlignment());
1357
1358 // We start laying out ivars not at the end of the superclass
1359 // structure, but at the next byte following the last field.
1360 setDataSize(SL.getDataSize());
1361 setSize(getDataSize());
1362 }
1363
1364 InitializeLayout(D);
1365 // Layout each ivar sequentially.
1366 for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1367 IVD = IVD->getNextIvar())
1368 LayoutField(IVD, false);
1369
1370 // Finally, round the size of the total struct up to the alignment of the
1371 // struct itself.
1372 FinishLayout(D);
1373}
1374
1375void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1376 // Layout each field, for now, just sequentially, respecting alignment. In
1377 // the future, this will need to be tweakable by targets.
1378 bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1379 bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1380 for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1381 auto Next(I);
1382 ++Next;
1383 LayoutField(*I,
1384 InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1385 }
1386}
1387
1388// Rounds the specified size to have it a multiple of the char size.
1389static uint64_t
1390roundUpSizeToCharAlignment(uint64_t Size,
1391 const ASTContext &Context) {
1392 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1393 return llvm::alignTo(Size, CharAlignment);
1394}
1395
1396void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1397 uint64_t TypeSize,
1398 bool FieldPacked,
1399 const FieldDecl *D) {
1400 assert(Context.getLangOpts().CPlusPlus &&((Context.getLangOpts().CPlusPlus && "Can only have wide bit-fields in C++!"
) ? static_cast<void> (0) : __assert_fail ("Context.getLangOpts().CPlusPlus && \"Can only have wide bit-fields in C++!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1401, __PRETTY_FUNCTION__))
1401 "Can only have wide bit-fields in C++!")((Context.getLangOpts().CPlusPlus && "Can only have wide bit-fields in C++!"
) ? static_cast<void> (0) : __assert_fail ("Context.getLangOpts().CPlusPlus && \"Can only have wide bit-fields in C++!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1401, __PRETTY_FUNCTION__))
;
1402
1403 // Itanium C++ ABI 2.4:
1404 // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1405 // sizeof(T')*8 <= n.
1406
1407 QualType IntegralPODTypes[] = {
1408 Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1409 Context.UnsignedLongTy, Context.UnsignedLongLongTy
1410 };
1411
1412 QualType Type;
1413 for (const QualType &QT : IntegralPODTypes) {
1414 uint64_t Size = Context.getTypeSize(QT);
1415
1416 if (Size > FieldSize)
1417 break;
1418
1419 Type = QT;
1420 }
1421 assert(!Type.isNull() && "Did not find a type!")((!Type.isNull() && "Did not find a type!") ? static_cast
<void> (0) : __assert_fail ("!Type.isNull() && \"Did not find a type!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1421, __PRETTY_FUNCTION__))
;
1422
1423 CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1424
1425 // We're not going to use any of the unfilled bits in the last byte.
1426 UnfilledBitsInLastUnit = 0;
1427 LastBitfieldTypeSize = 0;
1428
1429 uint64_t FieldOffset;
1430 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1431
1432 if (IsUnion) {
1433 uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1434 Context);
1435 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1436 FieldOffset = 0;
1437 } else {
1438 // The bitfield is allocated starting at the next offset aligned
1439 // appropriately for T', with length n bits.
1440 FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1441
1442 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1443
1444 setDataSize(
1445 llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1446 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1447 }
1448
1449 // Place this field at the current location.
1450 FieldOffsets.push_back(FieldOffset);
1451
1452 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1453 Context.toBits(TypeAlign), FieldPacked, D);
1454
1455 // Update the size.
1456 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1457
1458 // Remember max struct/class alignment.
1459 UpdateAlignment(TypeAlign);
1460}
1461
1462void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1463 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1464 uint64_t FieldSize = D->getBitWidthValue(Context);
1465 TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1466 uint64_t TypeSize = FieldInfo.Width;
1467 unsigned FieldAlign = FieldInfo.Align;
1468
1469 // UnfilledBitsInLastUnit is the difference between the end of the
1470 // last allocated bitfield (i.e. the first bit offset available for
1471 // bitfields) and the end of the current data size in bits (i.e. the
1472 // first bit offset available for non-bitfields). The current data
1473 // size in bits is always a multiple of the char size; additionally,
1474 // for ms_struct records it's also a multiple of the
1475 // LastBitfieldTypeSize (if set).
1476
1477 // The struct-layout algorithm is dictated by the platform ABI,
1478 // which in principle could use almost any rules it likes. In
1479 // practice, UNIXy targets tend to inherit the algorithm described
1480 // in the System V generic ABI. The basic bitfield layout rule in
1481 // System V is to place bitfields at the next available bit offset
1482 // where the entire bitfield would fit in an aligned storage unit of
1483 // the declared type; it's okay if an earlier or later non-bitfield
1484 // is allocated in the same storage unit. However, some targets
1485 // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1486 // require this storage unit to be aligned, and therefore always put
1487 // the bitfield at the next available bit offset.
1488
1489 // ms_struct basically requests a complete replacement of the
1490 // platform ABI's struct-layout algorithm, with the high-level goal
1491 // of duplicating MSVC's layout. For non-bitfields, this follows
1492 // the standard algorithm. The basic bitfield layout rule is to
1493 // allocate an entire unit of the bitfield's declared type
1494 // (e.g. 'unsigned long'), then parcel it up among successive
1495 // bitfields whose declared types have the same size, making a new
1496 // unit as soon as the last can no longer store the whole value.
1497 // Since it completely replaces the platform ABI's algorithm,
1498 // settings like !useBitFieldTypeAlignment() do not apply.
1499
1500 // A zero-width bitfield forces the use of a new storage unit for
1501 // later bitfields. In general, this occurs by rounding up the
1502 // current size of the struct as if the algorithm were about to
1503 // place a non-bitfield of the field's formal type. Usually this
1504 // does not change the alignment of the struct itself, but it does
1505 // on some targets (those that useZeroLengthBitfieldAlignment(),
1506 // e.g. ARM). In ms_struct layout, zero-width bitfields are
1507 // ignored unless they follow a non-zero-width bitfield.
1508
1509 // A field alignment restriction (e.g. from #pragma pack) or
1510 // specification (e.g. from __attribute__((aligned))) changes the
1511 // formal alignment of the field. For System V, this alters the
1512 // required alignment of the notional storage unit that must contain
1513 // the bitfield. For ms_struct, this only affects the placement of
1514 // new storage units. In both cases, the effect of #pragma pack is
1515 // ignored on zero-width bitfields.
1516
1517 // On System V, a packed field (e.g. from #pragma pack or
1518 // __attribute__((packed))) always uses the next available bit
1519 // offset.
1520
1521 // In an ms_struct struct, the alignment of a fundamental type is
1522 // always equal to its size. This is necessary in order to mimic
1523 // the i386 alignment rules on targets which might not fully align
1524 // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1525
1526 // First, some simple bookkeeping to perform for ms_struct structs.
1527 if (IsMsStruct) {
1528 // The field alignment for integer types is always the size.
1529 FieldAlign = TypeSize;
1530
1531 // If the previous field was not a bitfield, or was a bitfield
1532 // with a different storage unit size, or if this field doesn't fit into
1533 // the current storage unit, we're done with that storage unit.
1534 if (LastBitfieldTypeSize != TypeSize ||
1535 UnfilledBitsInLastUnit < FieldSize) {
1536 // Also, ignore zero-length bitfields after non-bitfields.
1537 if (!LastBitfieldTypeSize && !FieldSize)
1538 FieldAlign = 1;
1539
1540 UnfilledBitsInLastUnit = 0;
1541 LastBitfieldTypeSize = 0;
1542 }
1543 }
1544
1545 // If the field is wider than its declared type, it follows
1546 // different rules in all cases.
1547 if (FieldSize > TypeSize) {
1548 LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1549 return;
1550 }
1551
1552 // Compute the next available bit offset.
1553 uint64_t FieldOffset =
1554 IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1555
1556 // Handle targets that don't honor bitfield type alignment.
1557 if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1558 // Some such targets do honor it on zero-width bitfields.
1559 if (FieldSize == 0 &&
1560 Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
1561 // The alignment to round up to is the max of the field's natural
1562 // alignment and a target-specific fixed value (sometimes zero).
1563 unsigned ZeroLengthBitfieldBoundary =
1564 Context.getTargetInfo().getZeroLengthBitfieldBoundary();
1565 FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1566
1567 // If that doesn't apply, just ignore the field alignment.
1568 } else {
1569 FieldAlign = 1;
1570 }
1571 }
1572
1573 // Remember the alignment we would have used if the field were not packed.
1574 unsigned UnpackedFieldAlign = FieldAlign;
1575
1576 // Ignore the field alignment if the field is packed unless it has zero-size.
1577 if (!IsMsStruct && FieldPacked && FieldSize != 0)
1578 FieldAlign = 1;
1579
1580 // But, if there's an 'aligned' attribute on the field, honor that.
1581 unsigned ExplicitFieldAlign = D->getMaxAlignment();
1582 if (ExplicitFieldAlign) {
1583 FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1584 UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1585 }
1586
1587 // But, if there's a #pragma pack in play, that takes precedent over
1588 // even the 'aligned' attribute, for non-zero-width bitfields.
1589 unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1590 if (!MaxFieldAlignment.isZero() && FieldSize) {
1591 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1592 if (FieldPacked)
1593 FieldAlign = UnpackedFieldAlign;
1594 else
1595 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1596 }
1597
1598 // But, ms_struct just ignores all of that in unions, even explicit
1599 // alignment attributes.
1600 if (IsMsStruct && IsUnion) {
1601 FieldAlign = UnpackedFieldAlign = 1;
1602 }
1603
1604 // For purposes of diagnostics, we're going to simultaneously
1605 // compute the field offsets that we would have used if we weren't
1606 // adding any alignment padding or if the field weren't packed.
1607 uint64_t UnpaddedFieldOffset = FieldOffset;
1608 uint64_t UnpackedFieldOffset = FieldOffset;
1609
1610 // Check if we need to add padding to fit the bitfield within an
1611 // allocation unit with the right size and alignment. The rules are
1612 // somewhat different here for ms_struct structs.
1613 if (IsMsStruct) {
1614 // If it's not a zero-width bitfield, and we can fit the bitfield
1615 // into the active storage unit (and we haven't already decided to
1616 // start a new storage unit), just do so, regardless of any other
1617 // other consideration. Otherwise, round up to the right alignment.
1618 if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1619 FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1620 UnpackedFieldOffset =
1621 llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1622 UnfilledBitsInLastUnit = 0;
1623 }
1624
1625 } else {
1626 // #pragma pack, with any value, suppresses the insertion of padding.
1627 bool AllowPadding = MaxFieldAlignment.isZero();
1628
1629 // Compute the real offset.
1630 if (FieldSize == 0 ||
1631 (AllowPadding &&
1632 (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1633 FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1634 } else if (ExplicitFieldAlign &&
1635 (MaxFieldAlignmentInBits == 0 ||
1636 ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1637 Context.getTargetInfo().useExplicitBitFieldAlignment()) {
1638 // TODO: figure it out what needs to be done on targets that don't honor
1639 // bit-field type alignment like ARM APCS ABI.
1640 FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1641 }
1642
1643 // Repeat the computation for diagnostic purposes.
1644 if (FieldSize == 0 ||
1645 (AllowPadding &&
1646 (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1647 UnpackedFieldOffset =
1648 llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1649 else if (ExplicitFieldAlign &&
1650 (MaxFieldAlignmentInBits == 0 ||
1651 ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1652 Context.getTargetInfo().useExplicitBitFieldAlignment())
1653 UnpackedFieldOffset =
1654 llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1655 }
1656
1657 // If we're using external layout, give the external layout a chance
1658 // to override this information.
1659 if (UseExternalLayout)
1660 FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1661
1662 // Okay, place the bitfield at the calculated offset.
1663 FieldOffsets.push_back(FieldOffset);
1664
1665 // Bookkeeping:
1666
1667 // Anonymous members don't affect the overall record alignment,
1668 // except on targets where they do.
1669 if (!IsMsStruct &&
1670 !Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
1671 !D->getIdentifier())
1672 FieldAlign = UnpackedFieldAlign = 1;
1673
1674 // Diagnose differences in layout due to padding or packing.
1675 if (!UseExternalLayout)
1676 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1677 UnpackedFieldAlign, FieldPacked, D);
1678
1679 // Update DataSize to include the last byte containing (part of) the bitfield.
1680
1681 // For unions, this is just a max operation, as usual.
1682 if (IsUnion) {
1683 // For ms_struct, allocate the entire storage unit --- unless this
1684 // is a zero-width bitfield, in which case just use a size of 1.
1685 uint64_t RoundedFieldSize;
1686 if (IsMsStruct) {
1687 RoundedFieldSize =
1688 (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1689
1690 // Otherwise, allocate just the number of bytes required to store
1691 // the bitfield.
1692 } else {
1693 RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1694 }
1695 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1696
1697 // For non-zero-width bitfields in ms_struct structs, allocate a new
1698 // storage unit if necessary.
1699 } else if (IsMsStruct && FieldSize) {
1700 // We should have cleared UnfilledBitsInLastUnit in every case
1701 // where we changed storage units.
1702 if (!UnfilledBitsInLastUnit) {
1703 setDataSize(FieldOffset + TypeSize);
1704 UnfilledBitsInLastUnit = TypeSize;
1705 }
1706 UnfilledBitsInLastUnit -= FieldSize;
1707 LastBitfieldTypeSize = TypeSize;
1708
1709 // Otherwise, bump the data size up to include the bitfield,
1710 // including padding up to char alignment, and then remember how
1711 // bits we didn't use.
1712 } else {
1713 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1714 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1715 setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1716 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1717
1718 // The only time we can get here for an ms_struct is if this is a
1719 // zero-width bitfield, which doesn't count as anything for the
1720 // purposes of unfilled bits.
1721 LastBitfieldTypeSize = 0;
1722 }
1723
1724 // Update the size.
1725 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1726
1727 // Remember max struct/class alignment.
1728 UnadjustedAlignment =
1729 std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
1730 UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1731 Context.toCharUnitsFromBits(UnpackedFieldAlign));
1732}
1733
1734void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1735 bool InsertExtraPadding) {
1736 if (D->isBitField()) {
1737 LayoutBitField(D);
1738 return;
1739 }
1740
1741 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1742
1743 // Reset the unfilled bits.
1744 UnfilledBitsInLastUnit = 0;
1745 LastBitfieldTypeSize = 0;
1746
1747 auto *FieldClass = D->getType()->getAsCXXRecordDecl();
1748 bool PotentiallyOverlapping = D->hasAttr<NoUniqueAddressAttr>() && FieldClass;
1749 bool IsOverlappingEmptyField = PotentiallyOverlapping && FieldClass->isEmpty();
1750 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1751
1752 CharUnits FieldOffset = (IsUnion || IsOverlappingEmptyField)
1753 ? CharUnits::Zero()
1754 : getDataSize();
1755 CharUnits FieldSize;
1756 CharUnits FieldAlign;
1757 // The amount of this class's dsize occupied by the field.
1758 // This is equal to FieldSize unless we're permitted to pack
1759 // into the field's tail padding.
1760 CharUnits EffectiveFieldSize;
1761
1762 if (D->getType()->isIncompleteArrayType()) {
1763 // This is a flexible array member; we can't directly
1764 // query getTypeInfo about these, so we figure it out here.
1765 // Flexible array members don't have any size, but they
1766 // have to be aligned appropriately for their element type.
1767 EffectiveFieldSize = FieldSize = CharUnits::Zero();
1768 const ArrayType* ATy = Context.getAsArrayType(D->getType());
1769 FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1770 } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1771 unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1772 EffectiveFieldSize = FieldSize =
1773 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1774 FieldAlign =
1775 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1776 } else {
1777 std::pair<CharUnits, CharUnits> FieldInfo =
1778 Context.getTypeInfoInChars(D->getType());
1779 EffectiveFieldSize = FieldSize = FieldInfo.first;
1780 FieldAlign = FieldInfo.second;
1781
1782 // A potentially-overlapping field occupies its dsize or nvsize, whichever
1783 // is larger.
1784 if (PotentiallyOverlapping) {
1785 const ASTRecordLayout &Layout = Context.getASTRecordLayout(FieldClass);
1786 EffectiveFieldSize =
1787 std::max(Layout.getNonVirtualSize(), Layout.getDataSize());
1788 }
1789
1790 if (IsMsStruct) {
1791 // If MS bitfield layout is required, figure out what type is being
1792 // laid out and align the field to the width of that type.
1793
1794 // Resolve all typedefs down to their base type and round up the field
1795 // alignment if necessary.
1796 QualType T = Context.getBaseElementType(D->getType());
1797 if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1798 CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1799
1800 if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1801 assert(((!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment
() && "Non PowerOf2 size in MSVC mode") ? static_cast
<void> (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1803, __PRETTY_FUNCTION__))
1802 !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&((!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment
() && "Non PowerOf2 size in MSVC mode") ? static_cast
<void> (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1803, __PRETTY_FUNCTION__))
1803 "Non PowerOf2 size in MSVC mode")((!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment
() && "Non PowerOf2 size in MSVC mode") ? static_cast
<void> (0) : __assert_fail ("!Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() && \"Non PowerOf2 size in MSVC mode\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1803, __PRETTY_FUNCTION__))
;
1804 // Base types with sizes that aren't a power of two don't work
1805 // with the layout rules for MS structs. This isn't an issue in
1806 // MSVC itself since there are no such base data types there.
1807 // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1808 // Any structs involving that data type obviously can't be ABI
1809 // compatible with MSVC regardless of how it is laid out.
1810
1811 // Since ms_struct can be mass enabled (via a pragma or via the
1812 // -mms-bitfields command line parameter), this can trigger for
1813 // structs that don't actually need MSVC compatibility, so we
1814 // need to be able to sidestep the ms_struct layout for these types.
1815
1816 // Since the combination of -mms-bitfields together with structs
1817 // like max_align_t (which contains a long double) for mingw is
1818 // quite comon (and GCC handles it silently), just handle it
1819 // silently there. For other targets that have ms_struct enabled
1820 // (most probably via a pragma or attribute), trigger a diagnostic
1821 // that defaults to an error.
1822 if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1823 Diag(D->getLocation(), diag::warn_npot_ms_struct);
1824 }
1825 if (TypeSize > FieldAlign &&
1826 llvm::isPowerOf2_64(TypeSize.getQuantity()))
1827 FieldAlign = TypeSize;
1828 }
1829 }
1830 }
1831
1832 // The align if the field is not packed. This is to check if the attribute
1833 // was unnecessary (-Wpacked).
1834 CharUnits UnpackedFieldAlign = FieldAlign;
1835 CharUnits UnpackedFieldOffset = FieldOffset;
1836
1837 if (FieldPacked)
1838 FieldAlign = CharUnits::One();
1839 CharUnits MaxAlignmentInChars =
1840 Context.toCharUnitsFromBits(D->getMaxAlignment());
1841 FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1842 UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1843
1844 // The maximum field alignment overrides the aligned attribute.
1845 if (!MaxFieldAlignment.isZero()) {
1846 FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1847 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1848 }
1849
1850 // Round up the current record size to the field's alignment boundary.
1851 FieldOffset = FieldOffset.alignTo(FieldAlign);
1852 UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1853
1854 if (UseExternalLayout) {
1855 FieldOffset = Context.toCharUnitsFromBits(
1856 updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1857
1858 if (!IsUnion && EmptySubobjects) {
1859 // Record the fact that we're placing a field at this offset.
1860 bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1861 (void)Allowed;
1862 assert(Allowed && "Externally-placed field cannot be placed here")((Allowed && "Externally-placed field cannot be placed here"
) ? static_cast<void> (0) : __assert_fail ("Allowed && \"Externally-placed field cannot be placed here\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1862, __PRETTY_FUNCTION__))
;
1863 }
1864 } else {
1865 if (!IsUnion && EmptySubobjects) {
1866 // Check if we can place the field at this offset.
1867 while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1868 // We couldn't place the field at the offset. Try again at a new offset.
1869 // We try offset 0 (for an empty field) and then dsize(C) onwards.
1870 if (FieldOffset == CharUnits::Zero() &&
1871 getDataSize() != CharUnits::Zero())
1872 FieldOffset = getDataSize().alignTo(FieldAlign);
1873 else
1874 FieldOffset += FieldAlign;
1875 }
1876 }
1877 }
1878
1879 // Place this field at the current location.
1880 FieldOffsets.push_back(Context.toBits(FieldOffset));
1881
1882 if (!UseExternalLayout)
1883 CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1884 Context.toBits(UnpackedFieldOffset),
1885 Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1886
1887 if (InsertExtraPadding) {
1888 CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1889 CharUnits ExtraSizeForAsan = ASanAlignment;
1890 if (FieldSize % ASanAlignment)
1891 ExtraSizeForAsan +=
1892 ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1893 EffectiveFieldSize = FieldSize = FieldSize + ExtraSizeForAsan;
1894 }
1895
1896 // Reserve space for this field.
1897 if (!IsOverlappingEmptyField) {
1898 uint64_t EffectiveFieldSizeInBits = Context.toBits(EffectiveFieldSize);
1899 if (IsUnion)
1900 setDataSize(std::max(getDataSizeInBits(), EffectiveFieldSizeInBits));
1901 else
1902 setDataSize(FieldOffset + EffectiveFieldSize);
1903
1904 PaddedFieldSize = std::max(PaddedFieldSize, FieldOffset + FieldSize);
1905 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1906 } else {
1907 setSize(std::max(getSizeInBits(),
1908 (uint64_t)Context.toBits(FieldOffset + FieldSize)));
1909 }
1910
1911 // Remember max struct/class alignment.
1912 UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
1913 UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1914}
1915
1916void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1917 // In C++, records cannot be of size 0.
1918 if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1919 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1920 // Compatibility with gcc requires a class (pod or non-pod)
1921 // which is not empty but of size 0; such as having fields of
1922 // array of zero-length, remains of Size 0
1923 if (RD->isEmpty())
1924 setSize(CharUnits::One());
1925 }
1926 else
1927 setSize(CharUnits::One());
1928 }
1929
1930 // If we have any remaining field tail padding, include that in the overall
1931 // size.
1932 setSize(std::max(getSizeInBits(), (uint64_t)Context.toBits(PaddedFieldSize)));
1933
1934 // Finally, round the size of the record up to the alignment of the
1935 // record itself.
1936 uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1937 uint64_t UnpackedSizeInBits =
1938 llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1939 uint64_t RoundedSize =
1940 llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1941
1942 if (UseExternalLayout) {
1943 // If we're inferring alignment, and the external size is smaller than
1944 // our size after we've rounded up to alignment, conservatively set the
1945 // alignment to 1.
1946 if (InferAlignment && External.Size < RoundedSize) {
1947 Alignment = CharUnits::One();
1948 InferAlignment = false;
1949 }
1950 setSize(External.Size);
1951 return;
1952 }
1953
1954 // Set the size to the final size.
1955 setSize(RoundedSize);
1956
1957 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1958 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1959 // Warn if padding was introduced to the struct/class/union.
1960 if (getSizeInBits() > UnpaddedSize) {
1961 unsigned PadSize = getSizeInBits() - UnpaddedSize;
1962 bool InBits = true;
1963 if (PadSize % CharBitNum == 0) {
1964 PadSize = PadSize / CharBitNum;
1965 InBits = false;
1966 }
1967 Diag(RD->getLocation(), diag::warn_padded_struct_size)
1968 << Context.getTypeDeclType(RD)
1969 << PadSize
1970 << (InBits ? 1 : 0); // (byte|bit)
1971 }
1972
1973 // Warn if we packed it unnecessarily, when the unpacked alignment is not
1974 // greater than the one after packing, the size in bits doesn't change and
1975 // the offset of each field is identical.
1976 if (Packed && UnpackedAlignment <= Alignment &&
1977 UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1978 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1979 << Context.getTypeDeclType(RD);
1980 }
1981}
1982
1983void ItaniumRecordLayoutBuilder::UpdateAlignment(
1984 CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1985 // The alignment is not modified when using 'mac68k' alignment or when
1986 // we have an externally-supplied layout that also provides overall alignment.
1987 if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1988 return;
1989
1990 if (NewAlignment > Alignment) {
1991 assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&((llvm::isPowerOf2_64(NewAlignment.getQuantity()) && "Alignment not a power of 2"
) ? static_cast<void> (0) : __assert_fail ("llvm::isPowerOf2_64(NewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1992, __PRETTY_FUNCTION__))
1992 "Alignment not a power of 2")((llvm::isPowerOf2_64(NewAlignment.getQuantity()) && "Alignment not a power of 2"
) ? static_cast<void> (0) : __assert_fail ("llvm::isPowerOf2_64(NewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1992, __PRETTY_FUNCTION__))
;
1993 Alignment = NewAlignment;
1994 }
1995
1996 if (UnpackedNewAlignment > UnpackedAlignment) {
1997 assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&((llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
"Alignment not a power of 2") ? static_cast<void> (0) :
__assert_fail ("llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1998, __PRETTY_FUNCTION__))
1998 "Alignment not a power of 2")((llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
"Alignment not a power of 2") ? static_cast<void> (0) :
__assert_fail ("llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) && \"Alignment not a power of 2\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 1998, __PRETTY_FUNCTION__))
;
1999 UnpackedAlignment = UnpackedNewAlignment;
2000 }
2001}
2002
2003uint64_t
2004ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
2005 uint64_t ComputedOffset) {
2006 uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
2007
2008 if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
2009 // The externally-supplied field offset is before the field offset we
2010 // computed. Assume that the structure is packed.
2011 Alignment = CharUnits::One();
2012 InferAlignment = false;
2013 }
2014
2015 // Use the externally-supplied field offset.
2016 return ExternalFieldOffset;
2017}
2018
2019/// Get diagnostic %select index for tag kind for
2020/// field padding diagnostic message.
2021/// WARNING: Indexes apply to particular diagnostics only!
2022///
2023/// \returns diagnostic %select index.
2024static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
2025 switch (Tag) {
2026 case TTK_Struct: return 0;
2027 case TTK_Interface: return 1;
2028 case TTK_Class: return 2;
2029 default: llvm_unreachable("Invalid tag kind for field padding diagnostic!")::llvm::llvm_unreachable_internal("Invalid tag kind for field padding diagnostic!"
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2029)
;
2030 }
2031}
2032
2033void ItaniumRecordLayoutBuilder::CheckFieldPadding(
2034 uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
2035 unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
2036 // We let objc ivars without warning, objc interfaces generally are not used
2037 // for padding tricks.
2038 if (isa<ObjCIvarDecl>(D))
2039 return;
2040
2041 // Don't warn about structs created without a SourceLocation. This can
2042 // be done by clients of the AST, such as codegen.
2043 if (D->getLocation().isInvalid())
2044 return;
2045
2046 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2047
2048 // Warn if padding was introduced to the struct/class.
2049 if (!IsUnion && Offset > UnpaddedOffset) {
2050 unsigned PadSize = Offset - UnpaddedOffset;
2051 bool InBits = true;
2052 if (PadSize % CharBitNum == 0) {
2053 PadSize = PadSize / CharBitNum;
2054 InBits = false;
2055 }
2056 if (D->getIdentifier())
2057 Diag(D->getLocation(), diag::warn_padded_struct_field)
2058 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
2059 << Context.getTypeDeclType(D->getParent())
2060 << PadSize
2061 << (InBits ? 1 : 0) // (byte|bit)
2062 << D->getIdentifier();
2063 else
2064 Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2065 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
2066 << Context.getTypeDeclType(D->getParent())
2067 << PadSize
2068 << (InBits ? 1 : 0); // (byte|bit)
2069 }
2070 if (isPacked && Offset != UnpackedOffset) {
2071 HasPackedField = true;
2072 }
2073}
2074
2075static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
2076 const CXXRecordDecl *RD) {
2077 // If a class isn't polymorphic it doesn't have a key function.
2078 if (!RD->isPolymorphic())
2079 return nullptr;
2080
2081 // A class that is not externally visible doesn't have a key function. (Or
2082 // at least, there's no point to assigning a key function to such a class;
2083 // this doesn't affect the ABI.)
2084 if (!RD->isExternallyVisible())
2085 return nullptr;
2086
2087 // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2088 // Same behavior as GCC.
2089 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
2090 if (TSK == TSK_ImplicitInstantiation ||
2091 TSK == TSK_ExplicitInstantiationDeclaration ||
2092 TSK == TSK_ExplicitInstantiationDefinition)
2093 return nullptr;
2094
2095 bool allowInlineFunctions =
2096 Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline();
2097
2098 for (const CXXMethodDecl *MD : RD->methods()) {
2099 if (!MD->isVirtual())
2100 continue;
2101
2102 if (MD->isPure())
2103 continue;
2104
2105 // Ignore implicit member functions, they are always marked as inline, but
2106 // they don't have a body until they're defined.
2107 if (MD->isImplicit())
2108 continue;
2109
2110 if (MD->isInlineSpecified())
2111 continue;
2112
2113 if (MD->hasInlineBody())
2114 continue;
2115
2116 // Ignore inline deleted or defaulted functions.
2117 if (!MD->isUserProvided())
2118 continue;
2119
2120 // In certain ABIs, ignore functions with out-of-line inline definitions.
2121 if (!allowInlineFunctions) {
2122 const FunctionDecl *Def;
2123 if (MD->hasBody(Def) && Def->isInlineSpecified())
2124 continue;
2125 }
2126
2127 if (Context.getLangOpts().CUDA) {
2128 // While compiler may see key method in this TU, during CUDA
2129 // compilation we should ignore methods that are not accessible
2130 // on this side of compilation.
2131 if (Context.getLangOpts().CUDAIsDevice) {
2132 // In device mode ignore methods without __device__ attribute.
2133 if (!MD->hasAttr<CUDADeviceAttr>())
2134 continue;
2135 } else {
2136 // In host mode ignore __device__-only methods.
2137 if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2138 continue;
2139 }
2140 }
2141
2142 // If the key function is dllimport but the class isn't, then the class has
2143 // no key function. The DLL that exports the key function won't export the
2144 // vtable in this case.
2145 if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2146 return nullptr;
2147
2148 // We found it.
2149 return MD;
2150 }
2151
2152 return nullptr;
2153}
2154
2155DiagnosticBuilder ItaniumRecordLayoutBuilder::Diag(SourceLocation Loc,
2156 unsigned DiagID) {
2157 return Context.getDiagnostics().Report(Loc, DiagID);
2158}
2159
2160/// Does the target C++ ABI require us to skip over the tail-padding
2161/// of the given class (considering it as a base class) when allocating
2162/// objects?
2163static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2164 switch (ABI.getTailPaddingUseRules()) {
2165 case TargetCXXABI::AlwaysUseTailPadding:
2166 return false;
2167
2168 case TargetCXXABI::UseTailPaddingUnlessPOD03:
2169 // FIXME: To the extent that this is meant to cover the Itanium ABI
2170 // rules, we should implement the restrictions about over-sized
2171 // bitfields:
2172 //
2173 // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2174 // In general, a type is considered a POD for the purposes of
2175 // layout if it is a POD type (in the sense of ISO C++
2176 // [basic.types]). However, a POD-struct or POD-union (in the
2177 // sense of ISO C++ [class]) with a bitfield member whose
2178 // declared width is wider than the declared type of the
2179 // bitfield is not a POD for the purpose of layout. Similarly,
2180 // an array type is not a POD for the purpose of layout if the
2181 // element type of the array is not a POD for the purpose of
2182 // layout.
2183 //
2184 // Where references to the ISO C++ are made in this paragraph,
2185 // the Technical Corrigendum 1 version of the standard is
2186 // intended.
2187 return RD->isPOD();
2188
2189 case TargetCXXABI::UseTailPaddingUnlessPOD11:
2190 // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2191 // but with a lot of abstraction penalty stripped off. This does
2192 // assume that these properties are set correctly even in C++98
2193 // mode; fortunately, that is true because we want to assign
2194 // consistently semantics to the type-traits intrinsics (or at
2195 // least as many of them as possible).
2196 return RD->isTrivial() && RD->isCXX11StandardLayout();
2197 }
2198
2199 llvm_unreachable("bad tail-padding use kind")::llvm::llvm_unreachable_internal("bad tail-padding use kind"
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2199)
;
2200}
2201
2202static bool isMsLayout(const ASTContext &Context) {
2203 return Context.getTargetInfo().getCXXABI().isMicrosoft();
2204}
2205
2206// This section contains an implementation of struct layout that is, up to the
2207// included tests, compatible with cl.exe (2013). The layout produced is
2208// significantly different than those produced by the Itanium ABI. Here we note
2209// the most important differences.
2210//
2211// * The alignment of bitfields in unions is ignored when computing the
2212// alignment of the union.
2213// * The existence of zero-width bitfield that occurs after anything other than
2214// a non-zero length bitfield is ignored.
2215// * There is no explicit primary base for the purposes of layout. All bases
2216// with vfptrs are laid out first, followed by all bases without vfptrs.
2217// * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2218// function pointer) and a vbptr (virtual base pointer). They can each be
2219// shared with a, non-virtual bases. These bases need not be the same. vfptrs
2220// always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2221// placed after the lexicographically last non-virtual base. This placement
2222// is always before fields but can be in the middle of the non-virtual bases
2223// due to the two-pass layout scheme for non-virtual-bases.
2224// * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2225// the virtual base and is used in conjunction with virtual overrides during
2226// construction and destruction. This is always a 4 byte value and is used as
2227// an alternative to constructor vtables.
2228// * vtordisps are allocated in a block of memory with size and alignment equal
2229// to the alignment of the completed structure (before applying __declspec(
2230// align())). The vtordisp always occur at the end of the allocation block,
2231// immediately prior to the virtual base.
2232// * vfptrs are injected after all bases and fields have been laid out. In
2233// order to guarantee proper alignment of all fields, the vfptr injection
2234// pushes all bases and fields back by the alignment imposed by those bases
2235// and fields. This can potentially add a significant amount of padding.
2236// vfptrs are always injected at offset 0.
2237// * vbptrs are injected after all bases and fields have been laid out. In
2238// order to guarantee proper alignment of all fields, the vfptr injection
2239// pushes all bases and fields back by the alignment imposed by those bases
2240// and fields. This can potentially add a significant amount of padding.
2241// vbptrs are injected immediately after the last non-virtual base as
2242// lexicographically ordered in the code. If this site isn't pointer aligned
2243// the vbptr is placed at the next properly aligned location. Enough padding
2244// is added to guarantee a fit.
2245// * The last zero sized non-virtual base can be placed at the end of the
2246// struct (potentially aliasing another object), or may alias with the first
2247// field, even if they are of the same type.
2248// * The last zero size virtual base may be placed at the end of the struct
2249// potentially aliasing another object.
2250// * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2251// between bases or vbases with specific properties. The criteria for
2252// additional padding between two bases is that the first base is zero sized
2253// or ends with a zero sized subobject and the second base is zero sized or
2254// trails with a zero sized base or field (sharing of vfptrs can reorder the
2255// layout of the so the leading base is not always the first one declared).
2256// This rule does take into account fields that are not records, so padding
2257// will occur even if the last field is, e.g. an int. The padding added for
2258// bases is 1 byte. The padding added between vbases depends on the alignment
2259// of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2260// * There is no concept of non-virtual alignment, non-virtual alignment and
2261// alignment are always identical.
2262// * There is a distinction between alignment and required alignment.
2263// __declspec(align) changes the required alignment of a struct. This
2264// alignment is _always_ obeyed, even in the presence of #pragma pack. A
2265// record inherits required alignment from all of its fields and bases.
2266// * __declspec(align) on bitfields has the effect of changing the bitfield's
2267// alignment instead of its required alignment. This is the only known way
2268// to make the alignment of a struct bigger than 8. Interestingly enough
2269// this alignment is also immune to the effects of #pragma pack and can be
2270// used to create structures with large alignment under #pragma pack.
2271// However, because it does not impact required alignment, such a structure,
2272// when used as a field or base, will not be aligned if #pragma pack is
2273// still active at the time of use.
2274//
2275// Known incompatibilities:
2276// * all: #pragma pack between fields in a record
2277// * 2010 and back: If the last field in a record is a bitfield, every object
2278// laid out after the record will have extra padding inserted before it. The
2279// extra padding will have size equal to the size of the storage class of the
2280// bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2281// padding can be avoided by adding a 0 sized bitfield after the non-zero-
2282// sized bitfield.
2283// * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2284// greater due to __declspec(align()) then a second layout phase occurs after
2285// The locations of the vf and vb pointers are known. This layout phase
2286// suffers from the "last field is a bitfield" bug in 2010 and results in
2287// _every_ field getting padding put in front of it, potentially including the
2288// vfptr, leaving the vfprt at a non-zero location which results in a fault if
2289// anything tries to read the vftbl. The second layout phase also treats
2290// bitfields as separate entities and gives them each storage rather than
2291// packing them. Additionally, because this phase appears to perform a
2292// (an unstable) sort on the members before laying them out and because merged
2293// bitfields have the same address, the bitfields end up in whatever order
2294// the sort left them in, a behavior we could never hope to replicate.
2295
2296namespace {
2297struct MicrosoftRecordLayoutBuilder {
2298 struct ElementInfo {
2299 CharUnits Size;
2300 CharUnits Alignment;
2301 };
2302 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2303 MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2304private:
2305 MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2306 void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2307public:
2308 void layout(const RecordDecl *RD);
2309 void cxxLayout(const CXXRecordDecl *RD);
2310 /// Initializes size and alignment and honors some flags.
2311 void initializeLayout(const RecordDecl *RD);
2312 /// Initialized C++ layout, compute alignment and virtual alignment and
2313 /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2314 /// laid out.
2315 void initializeCXXLayout(const CXXRecordDecl *RD);
2316 void layoutNonVirtualBases(const CXXRecordDecl *RD);
2317 void layoutNonVirtualBase(const CXXRecordDecl *RD,
2318 const CXXRecordDecl *BaseDecl,
2319 const ASTRecordLayout &BaseLayout,
2320 const ASTRecordLayout *&PreviousBaseLayout);
2321 void injectVFPtr(const CXXRecordDecl *RD);
2322 void injectVBPtr(const CXXRecordDecl *RD);
2323 /// Lays out the fields of the record. Also rounds size up to
2324 /// alignment.
2325 void layoutFields(const RecordDecl *RD);
2326 void layoutField(const FieldDecl *FD);
2327 void layoutBitField(const FieldDecl *FD);
2328 /// Lays out a single zero-width bit-field in the record and handles
2329 /// special cases associated with zero-width bit-fields.
2330 void layoutZeroWidthBitField(const FieldDecl *FD);
2331 void layoutVirtualBases(const CXXRecordDecl *RD);
2332 void finalizeLayout(const RecordDecl *RD);
2333 /// Gets the size and alignment of a base taking pragma pack and
2334 /// __declspec(align) into account.
2335 ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2336 /// Gets the size and alignment of a field taking pragma pack and
2337 /// __declspec(align) into account. It also updates RequiredAlignment as a
2338 /// side effect because it is most convenient to do so here.
2339 ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2340 /// Places a field at an offset in CharUnits.
2341 void placeFieldAtOffset(CharUnits FieldOffset) {
2342 FieldOffsets.push_back(Context.toBits(FieldOffset));
2343 }
2344 /// Places a bitfield at a bit offset.
2345 void placeFieldAtBitOffset(uint64_t FieldOffset) {
2346 FieldOffsets.push_back(FieldOffset);
2347 }
2348 /// Compute the set of virtual bases for which vtordisps are required.
2349 void computeVtorDispSet(
2350 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2351 const CXXRecordDecl *RD) const;
2352 const ASTContext &Context;
2353 /// The size of the record being laid out.
2354 CharUnits Size;
2355 /// The non-virtual size of the record layout.
2356 CharUnits NonVirtualSize;
2357 /// The data size of the record layout.
2358 CharUnits DataSize;
2359 /// The current alignment of the record layout.
2360 CharUnits Alignment;
2361 /// The maximum allowed field alignment. This is set by #pragma pack.
2362 CharUnits MaxFieldAlignment;
2363 /// The alignment that this record must obey. This is imposed by
2364 /// __declspec(align()) on the record itself or one of its fields or bases.
2365 CharUnits RequiredAlignment;
2366 /// The size of the allocation of the currently active bitfield.
2367 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2368 /// is true.
2369 CharUnits CurrentBitfieldSize;
2370 /// Offset to the virtual base table pointer (if one exists).
2371 CharUnits VBPtrOffset;
2372 /// Minimum record size possible.
2373 CharUnits MinEmptyStructSize;
2374 /// The size and alignment info of a pointer.
2375 ElementInfo PointerInfo;
2376 /// The primary base class (if one exists).
2377 const CXXRecordDecl *PrimaryBase;
2378 /// The class we share our vb-pointer with.
2379 const CXXRecordDecl *SharedVBPtrBase;
2380 /// The collection of field offsets.
2381 SmallVector<uint64_t, 16> FieldOffsets;
2382 /// Base classes and their offsets in the record.
2383 BaseOffsetsMapTy Bases;
2384 /// virtual base classes and their offsets in the record.
2385 ASTRecordLayout::VBaseOffsetsMapTy VBases;
2386 /// The number of remaining bits in our last bitfield allocation.
2387 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2388 /// true.
2389 unsigned RemainingBitsInField;
2390 bool IsUnion : 1;
2391 /// True if the last field laid out was a bitfield and was not 0
2392 /// width.
2393 bool LastFieldIsNonZeroWidthBitfield : 1;
2394 /// True if the class has its own vftable pointer.
2395 bool HasOwnVFPtr : 1;
2396 /// True if the class has a vbtable pointer.
2397 bool HasVBPtr : 1;
2398 /// True if the last sub-object within the type is zero sized or the
2399 /// object itself is zero sized. This *does not* count members that are not
2400 /// records. Only used for MS-ABI.
2401 bool EndsWithZeroSizedObject : 1;
2402 /// True if this class is zero sized or first base is zero sized or
2403 /// has this property. Only used for MS-ABI.
2404 bool LeadsWithZeroSizedBase : 1;
2405
2406 /// True if the external AST source provided a layout for this record.
2407 bool UseExternalLayout : 1;
2408
2409 /// The layout provided by the external AST source. Only active if
2410 /// UseExternalLayout is true.
2411 ExternalLayout External;
2412};
2413} // namespace
2414
2415MicrosoftRecordLayoutBuilder::ElementInfo
2416MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2417 const ASTRecordLayout &Layout) {
2418 ElementInfo Info;
2419 Info.Alignment = Layout.getAlignment();
2420 // Respect pragma pack.
2421 if (!MaxFieldAlignment.isZero())
2422 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2423 // Track zero-sized subobjects here where it's already available.
2424 EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2425 // Respect required alignment, this is necessary because we may have adjusted
2426 // the alignment in the case of pragam pack. Note that the required alignment
2427 // doesn't actually apply to the struct alignment at this point.
2428 Alignment = std::max(Alignment, Info.Alignment);
2429 RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2430 Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2431 Info.Size = Layout.getNonVirtualSize();
2432 return Info;
2433}
2434
2435MicrosoftRecordLayoutBuilder::ElementInfo
2436MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2437 const FieldDecl *FD) {
2438 // Get the alignment of the field type's natural alignment, ignore any
2439 // alignment attributes.
2440 ElementInfo Info;
2441 std::tie(Info.Size, Info.Alignment) =
2442 Context.getTypeInfoInChars(FD->getType()->getUnqualifiedDesugaredType());
2443 // Respect align attributes on the field.
2444 CharUnits FieldRequiredAlignment =
2445 Context.toCharUnitsFromBits(FD->getMaxAlignment());
2446 // Respect align attributes on the type.
2447 if (Context.isAlignmentRequired(FD->getType()))
2448 FieldRequiredAlignment = std::max(
2449 Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2450 // Respect attributes applied to subobjects of the field.
2451 if (FD->isBitField())
2452 // For some reason __declspec align impacts alignment rather than required
2453 // alignment when it is applied to bitfields.
2454 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2455 else {
2456 if (auto RT =
2457 FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
2458 auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2459 EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2460 FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2461 Layout.getRequiredAlignment());
2462 }
2463 // Capture required alignment as a side-effect.
2464 RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2465 }
2466 // Respect pragma pack, attribute pack and declspec align
2467 if (!MaxFieldAlignment.isZero())
2468 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2469 if (FD->hasAttr<PackedAttr>())
2470 Info.Alignment = CharUnits::One();
2471 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2472 return Info;
2473}
2474
2475void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2476 // For C record layout, zero-sized records always have size 4.
2477 MinEmptyStructSize = CharUnits::fromQuantity(4);
2478 initializeLayout(RD);
2479 layoutFields(RD);
2480 DataSize = Size = Size.alignTo(Alignment);
2481 RequiredAlignment = std::max(
2482 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2483 finalizeLayout(RD);
2484}
2485
2486void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2487 // The C++ standard says that empty structs have size 1.
2488 MinEmptyStructSize = CharUnits::One();
2489 initializeLayout(RD);
2490 initializeCXXLayout(RD);
2491 layoutNonVirtualBases(RD);
2492 layoutFields(RD);
2493 injectVBPtr(RD);
2494 injectVFPtr(RD);
2495 if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2496 Alignment = std::max(Alignment, PointerInfo.Alignment);
2497 auto RoundingAlignment = Alignment;
2498 if (!MaxFieldAlignment.isZero())
2499 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2500 if (!UseExternalLayout)
2501 Size = Size.alignTo(RoundingAlignment);
2502 NonVirtualSize = Size;
2503 RequiredAlignment = std::max(
2504 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2505 layoutVirtualBases(RD);
2506 finalizeLayout(RD);
2507}
2508
2509void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2510 IsUnion = RD->isUnion();
2511 Size = CharUnits::Zero();
2512 Alignment = CharUnits::One();
2513 // In 64-bit mode we always perform an alignment step after laying out vbases.
2514 // In 32-bit mode we do not. The check to see if we need to perform alignment
2515 // checks the RequiredAlignment field and performs alignment if it isn't 0.
2516 RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2517 ? CharUnits::One()
2518 : CharUnits::Zero();
2519 // Compute the maximum field alignment.
2520 MaxFieldAlignment = CharUnits::Zero();
2521 // Honor the default struct packing maximum alignment flag.
2522 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2523 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2524 // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2525 // than the pointer size.
2526 if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2527 unsigned PackedAlignment = MFAA->getAlignment();
2528 if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2529 MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2530 }
2531 // Packed attribute forces max field alignment to be 1.
2532 if (RD->hasAttr<PackedAttr>())
2533 MaxFieldAlignment = CharUnits::One();
2534
2535 // Try to respect the external layout if present.
2536 UseExternalLayout = false;
2537 if (ExternalASTSource *Source = Context.getExternalSource())
2538 UseExternalLayout = Source->layoutRecordType(
2539 RD, External.Size, External.Align, External.FieldOffsets,
2540 External.BaseOffsets, External.VirtualBaseOffsets);
2541}
2542
2543void
2544MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2545 EndsWithZeroSizedObject = false;
2546 LeadsWithZeroSizedBase = false;
2547 HasOwnVFPtr = false;
2548 HasVBPtr = false;
2549 PrimaryBase = nullptr;
2550 SharedVBPtrBase = nullptr;
2551 // Calculate pointer size and alignment. These are used for vfptr and vbprt
2552 // injection.
2553 PointerInfo.Size =
2554 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2555 PointerInfo.Alignment =
2556 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2557 // Respect pragma pack.
2558 if (!MaxFieldAlignment.isZero())
2559 PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2560}
2561
2562void
2563MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2564 // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2565 // out any bases that do not contain vfptrs. We implement this as two passes
2566 // over the bases. This approach guarantees that the primary base is laid out
2567 // first. We use these passes to calculate some additional aggregated
2568 // information about the bases, such as required alignment and the presence of
2569 // zero sized members.
2570 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2571 // Iterate through the bases and lay out the non-virtual ones.
2572 for (const CXXBaseSpecifier &Base : RD->bases()) {
2573 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2574 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2575 // Mark and skip virtual bases.
2576 if (Base.isVirtual()) {
2577 HasVBPtr = true;
2578 continue;
2579 }
2580 // Check for a base to share a VBPtr with.
2581 if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2582 SharedVBPtrBase = BaseDecl;
2583 HasVBPtr = true;
2584 }
2585 // Only lay out bases with extendable VFPtrs on the first pass.
2586 if (!BaseLayout.hasExtendableVFPtr())
2587 continue;
2588 // If we don't have a primary base, this one qualifies.
2589 if (!PrimaryBase) {
2590 PrimaryBase = BaseDecl;
2591 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2592 }
2593 // Lay out the base.
2594 layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2595 }
2596 // Figure out if we need a fresh VFPtr for this class.
2597 if (!PrimaryBase && RD->isDynamicClass())
2598 for (CXXRecordDecl::method_iterator i = RD->method_begin(),
2599 e = RD->method_end();
2600 !HasOwnVFPtr && i != e; ++i)
2601 HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2602 // If we don't have a primary base then we have a leading object that could
2603 // itself lead with a zero-sized object, something we track.
2604 bool CheckLeadingLayout = !PrimaryBase;
2605 // Iterate through the bases and lay out the non-virtual ones.
2606 for (const CXXBaseSpecifier &Base : RD->bases()) {
2607 if (Base.isVirtual())
2608 continue;
2609 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2610 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2611 // Only lay out bases without extendable VFPtrs on the second pass.
2612 if (BaseLayout.hasExtendableVFPtr()) {
2613 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2614 continue;
2615 }
2616 // If this is the first layout, check to see if it leads with a zero sized
2617 // object. If it does, so do we.
2618 if (CheckLeadingLayout) {
2619 CheckLeadingLayout = false;
2620 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2621 }
2622 // Lay out the base.
2623 layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2624 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2625 }
2626 // Set our VBPtroffset if we know it at this point.
2627 if (!HasVBPtr)
2628 VBPtrOffset = CharUnits::fromQuantity(-1);
2629 else if (SharedVBPtrBase) {
2630 const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2631 VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2632 }
2633}
2634
2635static bool recordUsesEBO(const RecordDecl *RD) {
2636 if (!isa<CXXRecordDecl>(RD))
2637 return false;
2638 if (RD->hasAttr<EmptyBasesAttr>())
2639 return true;
2640 if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2641 // TODO: Double check with the next version of MSVC.
2642 if (LVA->getVersion() <= LangOptions::MSVC2015)
2643 return false;
2644 // TODO: Some later version of MSVC will change the default behavior of the
2645 // compiler to enable EBO by default. When this happens, we will need an
2646 // additional isCompatibleWithMSVC check.
2647 return false;
2648}
2649
2650void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2651 const CXXRecordDecl *RD,
2652 const CXXRecordDecl *BaseDecl,
2653 const ASTRecordLayout &BaseLayout,
2654 const ASTRecordLayout *&PreviousBaseLayout) {
2655 // Insert padding between two bases if the left first one is zero sized or
2656 // contains a zero sized subobject and the right is zero sized or one leads
2657 // with a zero sized base.
2658 bool MDCUsesEBO = recordUsesEBO(RD);
2659 if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2660 BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2661 Size++;
2662 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2663 CharUnits BaseOffset;
2664
2665 // Respect the external AST source base offset, if present.
2666 bool FoundBase = false;
2667 if (UseExternalLayout) {
2668 FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2669 if (FoundBase) {
2670 assert(BaseOffset >= Size && "base offset already allocated")((BaseOffset >= Size && "base offset already allocated"
) ? static_cast<void> (0) : __assert_fail ("BaseOffset >= Size && \"base offset already allocated\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2670, __PRETTY_FUNCTION__))
;
2671 Size = BaseOffset;
2672 }
2673 }
2674
2675 if (!FoundBase) {
2676 if (MDCUsesEBO && BaseDecl->isEmpty()) {
2677 assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero())((BaseLayout.getNonVirtualSize() == CharUnits::Zero()) ? static_cast
<void> (0) : __assert_fail ("BaseLayout.getNonVirtualSize() == CharUnits::Zero()"
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2677, __PRETTY_FUNCTION__))
;
2678 BaseOffset = CharUnits::Zero();
2679 } else {
2680 // Otherwise, lay the base out at the end of the MDC.
2681 BaseOffset = Size = Size.alignTo(Info.Alignment);
2682 }
2683 }
2684 Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2685 Size += BaseLayout.getNonVirtualSize();
2686 PreviousBaseLayout = &BaseLayout;
2687}
2688
2689void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2690 LastFieldIsNonZeroWidthBitfield = false;
2691 for (const FieldDecl *Field : RD->fields())
2692 layoutField(Field);
2693}
2694
2695void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2696 if (FD->isBitField()) {
2697 layoutBitField(FD);
2698 return;
2699 }
2700 LastFieldIsNonZeroWidthBitfield = false;
2701 ElementInfo Info = getAdjustedElementInfo(FD);
2702 Alignment = std::max(Alignment, Info.Alignment);
2703 CharUnits FieldOffset;
2704 if (UseExternalLayout)
2705 FieldOffset =
2706 Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2707 else if (IsUnion)
2708 FieldOffset = CharUnits::Zero();
2709 else
2710 FieldOffset = Size.alignTo(Info.Alignment);
2711 placeFieldAtOffset(FieldOffset);
2712 Size = std::max(Size, FieldOffset + Info.Size);
2713}
2714
2715void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2716 unsigned Width = FD->getBitWidthValue(Context);
2717 if (Width == 0) {
2718 layoutZeroWidthBitField(FD);
2719 return;
2720 }
2721 ElementInfo Info = getAdjustedElementInfo(FD);
2722 // Clamp the bitfield to a containable size for the sake of being able
2723 // to lay them out. Sema will throw an error.
2724 if (Width > Context.toBits(Info.Size))
2725 Width = Context.toBits(Info.Size);
2726 // Check to see if this bitfield fits into an existing allocation. Note:
2727 // MSVC refuses to pack bitfields of formal types with different sizes
2728 // into the same allocation.
2729 if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
2730 CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2731 placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2732 RemainingBitsInField -= Width;
2733 return;
2734 }
2735 LastFieldIsNonZeroWidthBitfield = true;
2736 CurrentBitfieldSize = Info.Size;
2737 if (UseExternalLayout) {
2738 auto FieldBitOffset = External.getExternalFieldOffset(FD);
2739 placeFieldAtBitOffset(FieldBitOffset);
2740 auto NewSize = Context.toCharUnitsFromBits(
2741 llvm::alignDown(FieldBitOffset, Context.toBits(Info.Alignment)) +
2742 Context.toBits(Info.Size));
2743 Size = std::max(Size, NewSize);
2744 Alignment = std::max(Alignment, Info.Alignment);
2745 } else if (IsUnion) {
2746 placeFieldAtOffset(CharUnits::Zero());
2747 Size = std::max(Size, Info.Size);
2748 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2749 } else {
2750 // Allocate a new block of memory and place the bitfield in it.
2751 CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2752 placeFieldAtOffset(FieldOffset);
2753 Size = FieldOffset + Info.Size;
2754 Alignment = std::max(Alignment, Info.Alignment);
2755 RemainingBitsInField = Context.toBits(Info.Size) - Width;
2756 }
2757}
2758
2759void
2760MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2761 // Zero-width bitfields are ignored unless they follow a non-zero-width
2762 // bitfield.
2763 if (!LastFieldIsNonZeroWidthBitfield) {
2764 placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2765 // TODO: Add a Sema warning that MS ignores alignment for zero
2766 // sized bitfields that occur after zero-size bitfields or non-bitfields.
2767 return;
2768 }
2769 LastFieldIsNonZeroWidthBitfield = false;
2770 ElementInfo Info = getAdjustedElementInfo(FD);
2771 if (IsUnion) {
2772 placeFieldAtOffset(CharUnits::Zero());
2773 Size = std::max(Size, Info.Size);
2774 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2775 } else {
2776 // Round up the current record size to the field's alignment boundary.
2777 CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2778 placeFieldAtOffset(FieldOffset);
2779 Size = FieldOffset;
2780 Alignment = std::max(Alignment, Info.Alignment);
2781 }
2782}
2783
2784void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2785 if (!HasVBPtr || SharedVBPtrBase)
2786 return;
2787 // Inject the VBPointer at the injection site.
2788 CharUnits InjectionSite = VBPtrOffset;
2789 // But before we do, make sure it's properly aligned.
2790 VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2791 // Determine where the first field should be laid out after the vbptr.
2792 CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2793 // Shift everything after the vbptr down, unless we're using an external
2794 // layout.
2795 if (UseExternalLayout) {
2796 // It is possible that there were no fields or bases located after vbptr,
2797 // so the size was not adjusted before.
2798 if (Size < FieldStart)
2799 Size = FieldStart;
2800 return;
2801 }
2802 // Make sure that the amount we push the fields back by is a multiple of the
2803 // alignment.
2804 CharUnits Offset = (FieldStart - InjectionSite)
2805 .alignTo(std::max(RequiredAlignment, Alignment));
2806 Size += Offset;
2807 for (uint64_t &FieldOffset : FieldOffsets)
2808 FieldOffset += Context.toBits(Offset);
2809 for (BaseOffsetsMapTy::value_type &Base : Bases)
2810 if (Base.second >= InjectionSite)
2811 Base.second += Offset;
2812}
2813
2814void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2815 if (!HasOwnVFPtr)
2816 return;
2817 // Make sure that the amount we push the struct back by is a multiple of the
2818 // alignment.
2819 CharUnits Offset =
2820 PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2821 // Push back the vbptr, but increase the size of the object and push back
2822 // regular fields by the offset only if not using external record layout.
2823 if (HasVBPtr)
2824 VBPtrOffset += Offset;
2825
2826 if (UseExternalLayout) {
2827 // The class may have no bases or fields, but still have a vfptr
2828 // (e.g. it's an interface class). The size was not correctly set before
2829 // in this case.
2830 if (FieldOffsets.empty() && Bases.empty())
2831 Size += Offset;
2832 return;
2833 }
2834
2835 Size += Offset;
2836
2837 // If we're using an external layout, the fields offsets have already
2838 // accounted for this adjustment.
2839 for (uint64_t &FieldOffset : FieldOffsets)
2840 FieldOffset += Context.toBits(Offset);
2841 for (BaseOffsetsMapTy::value_type &Base : Bases)
2842 Base.second += Offset;
2843}
2844
2845void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2846 if (!HasVBPtr)
2847 return;
2848 // Vtordisps are always 4 bytes (even in 64-bit mode)
2849 CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2850 CharUnits VtorDispAlignment = VtorDispSize;
2851 // vtordisps respect pragma pack.
2852 if (!MaxFieldAlignment.isZero())
2853 VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2854 // The alignment of the vtordisp is at least the required alignment of the
2855 // entire record. This requirement may be present to support vtordisp
2856 // injection.
2857 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2858 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2859 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2860 RequiredAlignment =
2861 std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2862 }
2863 VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2864 // Compute the vtordisp set.
2865 llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2866 computeVtorDispSet(HasVtorDispSet, RD);
2867 // Iterate through the virtual bases and lay them out.
2868 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2869 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2870 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2871 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2872 bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2873 // Insert padding between two bases if the left first one is zero sized or
2874 // contains a zero sized subobject and the right is zero sized or one leads
2875 // with a zero sized base. The padding between virtual bases is 4
2876 // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2877 // the required alignment, we don't know why.
2878 if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2879 BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2880 HasVtordisp) {
2881 Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2882 Alignment = std::max(VtorDispAlignment, Alignment);
2883 }
2884 // Insert the virtual base.
2885 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2886 CharUnits BaseOffset;
2887
2888 // Respect the external AST source base offset, if present.
2889 if (UseExternalLayout) {
2890 if (!External.getExternalVBaseOffset(BaseDecl, BaseOffset))
2891 BaseOffset = Size;
2892 } else
2893 BaseOffset = Size.alignTo(Info.Alignment);
2894
2895 assert(BaseOffset >= Size && "base offset already allocated")((BaseOffset >= Size && "base offset already allocated"
) ? static_cast<void> (0) : __assert_fail ("BaseOffset >= Size && \"base offset already allocated\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2895, __PRETTY_FUNCTION__))
;
2896
2897 VBases.insert(std::make_pair(BaseDecl,
2898 ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2899 Size = BaseOffset + BaseLayout.getNonVirtualSize();
2900 PreviousBaseLayout = &BaseLayout;
2901 }
2902}
2903
2904void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2905 // Respect required alignment. Note that in 32-bit mode Required alignment
2906 // may be 0 and cause size not to be updated.
2907 DataSize = Size;
2908 if (!RequiredAlignment.isZero()) {
2909 Alignment = std::max(Alignment, RequiredAlignment);
2910 auto RoundingAlignment = Alignment;
2911 if (!MaxFieldAlignment.isZero())
2912 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2913 RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2914 Size = Size.alignTo(RoundingAlignment);
2915 }
2916 if (Size.isZero()) {
2917 if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2918 EndsWithZeroSizedObject = true;
2919 LeadsWithZeroSizedBase = true;
2920 }
2921 // Zero-sized structures have size equal to their alignment if a
2922 // __declspec(align) came into play.
2923 if (RequiredAlignment >= MinEmptyStructSize)
2924 Size = Alignment;
2925 else
2926 Size = MinEmptyStructSize;
2927 }
2928
2929 if (UseExternalLayout) {
2930 Size = Context.toCharUnitsFromBits(External.Size);
2931 if (External.Align)
2932 Alignment = Context.toCharUnitsFromBits(External.Align);
2933 }
2934}
2935
2936// Recursively walks the non-virtual bases of a class and determines if any of
2937// them are in the bases with overridden methods set.
2938static bool
2939RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2940 BasesWithOverriddenMethods,
2941 const CXXRecordDecl *RD) {
2942 if (BasesWithOverriddenMethods.count(RD))
2943 return true;
2944 // If any of a virtual bases non-virtual bases (recursively) requires a
2945 // vtordisp than so does this virtual base.
2946 for (const CXXBaseSpecifier &Base : RD->bases())
2947 if (!Base.isVirtual() &&
2948 RequiresVtordisp(BasesWithOverriddenMethods,
2949 Base.getType()->getAsCXXRecordDecl()))
2950 return true;
2951 return false;
2952}
2953
2954void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2955 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2956 const CXXRecordDecl *RD) const {
2957 // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2958 // vftables.
2959 if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2960 for (const CXXBaseSpecifier &Base : RD->vbases()) {
2961 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2962 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2963 if (Layout.hasExtendableVFPtr())
2964 HasVtordispSet.insert(BaseDecl);
2965 }
2966 return;
2967 }
2968
2969 // If any of our bases need a vtordisp for this type, so do we. Check our
2970 // direct bases for vtordisp requirements.
2971 for (const CXXBaseSpecifier &Base : RD->bases()) {
2972 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2973 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2974 for (const auto &bi : Layout.getVBaseOffsetsMap())
2975 if (bi.second.hasVtorDisp())
2976 HasVtordispSet.insert(bi.first);
2977 }
2978 // We don't introduce any additional vtordisps if either:
2979 // * A user declared constructor or destructor aren't declared.
2980 // * #pragma vtordisp(0) or the /vd0 flag are in use.
2981 if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2982 RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2983 return;
2984 // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2985 // possible for a partially constructed object with virtual base overrides to
2986 // escape a non-trivial constructor.
2987 assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride)((RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride
) ? static_cast<void> (0) : __assert_fail ("RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride"
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 2987, __PRETTY_FUNCTION__))
;
2988 // Compute a set of base classes which define methods we override. A virtual
2989 // base in this set will require a vtordisp. A virtual base that transitively
2990 // contains one of these bases as a non-virtual base will also require a
2991 // vtordisp.
2992 llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2993 llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2994 // Seed the working set with our non-destructor, non-pure virtual methods.
2995 for (const CXXMethodDecl *MD : RD->methods())
2996 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2997 Work.insert(MD);
2998 while (!Work.empty()) {
2999 const CXXMethodDecl *MD = *Work.begin();
3000 auto MethodRange = MD->overridden_methods();
3001 // If a virtual method has no-overrides it lives in its parent's vtable.
3002 if (MethodRange.begin() == MethodRange.end())
3003 BasesWithOverriddenMethods.insert(MD->getParent());
3004 else
3005 Work.insert(MethodRange.begin(), MethodRange.end());
3006 // We've finished processing this element, remove it from the working set.
3007 Work.erase(MD);
3008 }
3009 // For each of our virtual bases, check if it is in the set of overridden
3010 // bases or if it transitively contains a non-virtual base that is.
3011 for (const CXXBaseSpecifier &Base : RD->vbases()) {
3012 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
3013 if (!HasVtordispSet.count(BaseDecl) &&
3014 RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
3015 HasVtordispSet.insert(BaseDecl);
3016 }
3017}
3018
3019/// getASTRecordLayout - Get or compute information about the layout of the
3020/// specified record (struct/union/class), which indicates its size and field
3021/// position information.
3022const ASTRecordLayout &
3023ASTContext::getASTRecordLayout(const RecordDecl *D) const {
3024 // These asserts test different things. A record has a definition
3025 // as soon as we begin to parse the definition. That definition is
3026 // not a complete definition (which is what isDefinition() tests)
3027 // until we *finish* parsing the definition.
3028
3029 if (D->hasExternalLexicalStorage() && !D->getDefinition())
5
Assuming the condition is false
3030 getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
3031
3032 D = D->getDefinition();
3033 assert
5.1
'D' is non-null
(D && "Cannot get layout of forward declarations!")((D && "Cannot get layout of forward declarations!") ?
static_cast<void> (0) : __assert_fail ("D && \"Cannot get layout of forward declarations!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3033, __PRETTY_FUNCTION__))
;
6
'?' condition is true
3034 assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!")((!D->isInvalidDecl() && "Cannot get layout of invalid decl!"
) ? static_cast<void> (0) : __assert_fail ("!D->isInvalidDecl() && \"Cannot get layout of invalid decl!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3034, __PRETTY_FUNCTION__))
;
7
Assuming the condition is true
8
'?' condition is true
3035 assert(D->isCompleteDefinition() && "Cannot layout type before complete!")((D->isCompleteDefinition() && "Cannot layout type before complete!"
) ? static_cast<void> (0) : __assert_fail ("D->isCompleteDefinition() && \"Cannot layout type before complete!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3035, __PRETTY_FUNCTION__))
;
9
Assuming the condition is true
10
'?' condition is true
3036
3037 // Look up this layout, if already laid out, return what we have.
3038 // Note that we can't save a reference to the entry because this function
3039 // is recursive.
3040 const ASTRecordLayout *Entry = ASTRecordLayouts[D];
3041 if (Entry) return *Entry;
11
Assuming 'Entry' is null
12
Taking false branch
3042
3043 const ASTRecordLayout *NewEntry = nullptr;
3044
3045 if (isMsLayout(*this)) {
13
Taking false branch
3046 MicrosoftRecordLayoutBuilder Builder(*this);
3047 if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3048 Builder.cxxLayout(RD);
3049 NewEntry = new (*this) ASTRecordLayout(
3050 *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3051 Builder.RequiredAlignment,
3052 Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
3053 Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
3054 Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
3055 Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
3056 Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
3057 Builder.Bases, Builder.VBases);
3058 } else {
3059 Builder.layout(D);
3060 NewEntry = new (*this) ASTRecordLayout(
3061 *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3062 Builder.RequiredAlignment,
3063 Builder.Size, Builder.FieldOffsets);
3064 }
3065 } else {
3066 if (const auto *RD
14.1
'RD' is non-null
= dyn_cast<CXXRecordDecl>(D)) {
14
Assuming 'D' is a 'CXXRecordDecl'
15
Taking true branch
3067 EmptySubobjectMap EmptySubobjects(*this, RD);
3068 ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
3069 Builder.Layout(RD);
16
Calling 'ItaniumRecordLayoutBuilder::Layout'
3070
3071 // In certain situations, we are allowed to lay out objects in the
3072 // tail-padding of base classes. This is ABI-dependent.
3073 // FIXME: this should be stored in the record layout.
3074 bool skipTailPadding =
3075 mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3076
3077 // FIXME: This should be done in FinalizeLayout.
3078 CharUnits DataSize =
3079 skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3080 CharUnits NonVirtualSize =
3081 skipTailPadding ? DataSize : Builder.NonVirtualSize;
3082 NewEntry = new (*this) ASTRecordLayout(
3083 *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3084 /*RequiredAlignment : used by MS-ABI)*/
3085 Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3086 CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3087 NonVirtualSize, Builder.NonVirtualAlignment,
3088 EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3089 Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3090 Builder.VBases);
3091 } else {
3092 ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3093 Builder.Layout(D);
3094
3095 NewEntry = new (*this) ASTRecordLayout(
3096 *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3097 /*RequiredAlignment : used by MS-ABI)*/
3098 Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3099 }
3100 }
3101
3102 ASTRecordLayouts[D] = NewEntry;
3103
3104 if (getLangOpts().DumpRecordLayouts) {
3105 llvm::outs() << "\n*** Dumping AST Record Layout\n";
3106 DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3107 }
3108
3109 return *NewEntry;
3110}
3111
3112const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD) {
3113 if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3114 return nullptr;
3115
3116 assert(RD->getDefinition() && "Cannot get key function for forward decl!")((RD->getDefinition() && "Cannot get key function for forward decl!"
) ? static_cast<void> (0) : __assert_fail ("RD->getDefinition() && \"Cannot get key function for forward decl!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3116, __PRETTY_FUNCTION__))
;
3117 RD = RD->getDefinition();
3118
3119 // Beware:
3120 // 1) computing the key function might trigger deserialization, which might
3121 // invalidate iterators into KeyFunctions
3122 // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3123 // invalidate the LazyDeclPtr within the map itself
3124 LazyDeclPtr Entry = KeyFunctions[RD];
3125 const Decl *Result =
3126 Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3127
3128 // Store it back if it changed.
3129 if (Entry.isOffset() || Entry.isValid() != bool(Result))
3130 KeyFunctions[RD] = const_cast<Decl*>(Result);
3131
3132 return cast_or_null<CXXMethodDecl>(Result);
3133}
3134
3135void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
3136 assert(Method == Method->getFirstDecl() &&((Method == Method->getFirstDecl() && "not working with method declaration from class definition"
) ? static_cast<void> (0) : __assert_fail ("Method == Method->getFirstDecl() && \"not working with method declaration from class definition\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3137, __PRETTY_FUNCTION__))
3137 "not working with method declaration from class definition")((Method == Method->getFirstDecl() && "not working with method declaration from class definition"
) ? static_cast<void> (0) : __assert_fail ("Method == Method->getFirstDecl() && \"not working with method declaration from class definition\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3137, __PRETTY_FUNCTION__))
;
3138
3139 // Look up the cache entry. Since we're working with the first
3140 // declaration, its parent must be the class definition, which is
3141 // the correct key for the KeyFunctions hash.
3142 const auto &Map = KeyFunctions;
3143 auto I = Map.find(Method->getParent());
3144
3145 // If it's not cached, there's nothing to do.
3146 if (I == Map.end()) return;
3147
3148 // If it is cached, check whether it's the target method, and if so,
3149 // remove it from the cache. Note, the call to 'get' might invalidate
3150 // the iterator and the LazyDeclPtr object within the map.
3151 LazyDeclPtr Ptr = I->second;
3152 if (Ptr.get(getExternalSource()) == Method) {
3153 // FIXME: remember that we did this for module / chained PCH state?
3154 KeyFunctions.erase(Method->getParent());
3155 }
3156}
3157
3158static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3159 const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3160 return Layout.getFieldOffset(FD->getFieldIndex());
3161}
3162
3163uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3164 uint64_t OffsetInBits;
3165 if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3166 OffsetInBits = ::getFieldOffset(*this, FD);
3167 } else {
3168 const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3169
3170 OffsetInBits = 0;
3171 for (const NamedDecl *ND : IFD->chain())
3172 OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3173 }
3174
3175 return OffsetInBits;
3176}
3177
3178uint64_t ASTContext::lookupFieldBitOffset(const ObjCInterfaceDecl *OID,
3179 const ObjCImplementationDecl *ID,
3180 const ObjCIvarDecl *Ivar) const {
3181 const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3182
3183 // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3184 // in here; it should never be necessary because that should be the lexical
3185 // decl context for the ivar.
3186
3187 // If we know have an implementation (and the ivar is in it) then
3188 // look up in the implementation layout.
3189 const ASTRecordLayout *RL;
3190 if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3191 RL = &getASTObjCImplementationLayout(ID);
3192 else
3193 RL = &getASTObjCInterfaceLayout(Container);
3194
3195 // Compute field index.
3196 //
3197 // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3198 // implemented. This should be fixed to get the information from the layout
3199 // directly.
3200 unsigned Index = 0;
3201
3202 for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3203 IVD; IVD = IVD->getNextIvar()) {
3204 if (Ivar == IVD)
3205 break;
3206 ++Index;
3207 }
3208 assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!")((Index < RL->getFieldCount() && "Ivar is not inside record layout!"
) ? static_cast<void> (0) : __assert_fail ("Index < RL->getFieldCount() && \"Ivar is not inside record layout!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3208, __PRETTY_FUNCTION__))
;
3209
3210 return RL->getFieldOffset(Index);
3211}
3212
3213/// getObjCLayout - Get or compute information about the layout of the
3214/// given interface.
3215///
3216/// \param Impl - If given, also include the layout of the interface's
3217/// implementation. This may differ by including synthesized ivars.
3218const ASTRecordLayout &
3219ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3220 const ObjCImplementationDecl *Impl) const {
3221 // Retrieve the definition
3222 if (D->hasExternalLexicalStorage() && !D->getDefinition())
3223 getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3224 D = D->getDefinition();
3225 assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!")((D && D->isThisDeclarationADefinition() &&
"Invalid interface decl!") ? static_cast<void> (0) : __assert_fail
("D && D->isThisDeclarationADefinition() && \"Invalid interface decl!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3225, __PRETTY_FUNCTION__))
;
3226
3227 // Look up this layout, if already laid out, return what we have.
3228 const ObjCContainerDecl *Key =
3229 Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3230 if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3231 return *Entry;
3232
3233 // Add in synthesized ivar count if laying out an implementation.
3234 if (Impl) {
3235 unsigned SynthCount = CountNonClassIvars(D);
3236 // If there aren't any synthesized ivars then reuse the interface
3237 // entry. Note we can't cache this because we simply free all
3238 // entries later; however we shouldn't look up implementations
3239 // frequently.
3240 if (SynthCount == 0)
3241 return getObjCLayout(D, nullptr);
3242 }
3243
3244 ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3245 Builder.Layout(D);
3246
3247 const ASTRecordLayout *NewEntry =
3248 new (*this) ASTRecordLayout(*this, Builder.getSize(),
3249 Builder.Alignment,
3250 Builder.UnadjustedAlignment,
3251 /*RequiredAlignment : used by MS-ABI)*/
3252 Builder.Alignment,
3253 Builder.getDataSize(),
3254 Builder.FieldOffsets);
3255
3256 ObjCLayouts[Key] = NewEntry;
3257
3258 return *NewEntry;
3259}
3260
3261static void PrintOffset(raw_ostream &OS,
3262 CharUnits Offset, unsigned IndentLevel) {
3263 OS << llvm::format("%10" PRId64"l" "d" " | ", (int64_t)Offset.getQuantity());
3264 OS.indent(IndentLevel * 2);
3265}
3266
3267static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3268 unsigned Begin, unsigned Width,
3269 unsigned IndentLevel) {
3270 llvm::SmallString<10> Buffer;
3271 {
3272 llvm::raw_svector_ostream BufferOS(Buffer);
3273 BufferOS << Offset.getQuantity() << ':';
3274 if (Width == 0) {
3275 BufferOS << '-';
3276 } else {
3277 BufferOS << Begin << '-' << (Begin + Width - 1);
3278 }
3279 }
3280
3281 OS << llvm::right_justify(Buffer, 10) << " | ";
3282 OS.indent(IndentLevel * 2);
3283}
3284
3285static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3286 OS << " | ";
3287 OS.indent(IndentLevel * 2);
3288}
3289
3290static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3291 const ASTContext &C,
3292 CharUnits Offset,
3293 unsigned IndentLevel,
3294 const char* Description,
3295 bool PrintSizeInfo,
3296 bool IncludeVirtualBases) {
3297 const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
4
Calling 'ASTContext::getASTRecordLayout'
3298 auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3299
3300 PrintOffset(OS, Offset, IndentLevel);
3301 OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3302 if (Description)
3303 OS << ' ' << Description;
3304 if (CXXRD && CXXRD->isEmpty())
3305 OS << " (empty)";
3306 OS << '\n';
3307
3308 IndentLevel++;
3309
3310 // Dump bases.
3311 if (CXXRD) {
3312 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3313 bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3314 bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3315
3316 // Vtable pointer.
3317 if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3318 PrintOffset(OS, Offset, IndentLevel);
3319 OS << '(' << *RD << " vtable pointer)\n";
3320 } else if (HasOwnVFPtr) {
3321 PrintOffset(OS, Offset, IndentLevel);
3322 // vfptr (for Microsoft C++ ABI)
3323 OS << '(' << *RD << " vftable pointer)\n";
3324 }
3325
3326 // Collect nvbases.
3327 SmallVector<const CXXRecordDecl *, 4> Bases;
3328 for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3329 assert(!Base.getType()->isDependentType() &&((!Base.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3330, __PRETTY_FUNCTION__))
3330 "Cannot layout class with dependent bases.")((!Base.getType()->isDependentType() && "Cannot layout class with dependent bases."
) ? static_cast<void> (0) : __assert_fail ("!Base.getType()->isDependentType() && \"Cannot layout class with dependent bases.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3330, __PRETTY_FUNCTION__))
;
3331 if (!Base.isVirtual())
3332 Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3333 }
3334
3335 // Sort nvbases by offset.
3336 llvm::stable_sort(
3337 Bases, [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3338 return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3339 });
3340
3341 // Dump (non-virtual) bases
3342 for (const CXXRecordDecl *Base : Bases) {
3343 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3344 DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3345 Base == PrimaryBase ? "(primary base)" : "(base)",
3346 /*PrintSizeInfo=*/false,
3347 /*IncludeVirtualBases=*/false);
3348 }
3349
3350 // vbptr (for Microsoft C++ ABI)
3351 if (HasOwnVBPtr) {
3352 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3353 OS << '(' << *RD << " vbtable pointer)\n";
3354 }
3355 }
3356
3357 // Dump fields.
3358 uint64_t FieldNo = 0;
3359 for (RecordDecl::field_iterator I = RD->field_begin(),
3360 E = RD->field_end(); I != E; ++I, ++FieldNo) {
3361 const FieldDecl &Field = **I;
3362 uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3363 CharUnits FieldOffset =
3364 Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3365
3366 // Recursively dump fields of record type.
3367 if (auto RT = Field.getType()->getAs<RecordType>()) {
3368 DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3369 Field.getName().data(),
3370 /*PrintSizeInfo=*/false,
3371 /*IncludeVirtualBases=*/true);
3372 continue;
3373 }
3374
3375 if (Field.isBitField()) {
3376 uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3377 unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3378 unsigned Width = Field.getBitWidthValue(C);
3379 PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3380 } else {
3381 PrintOffset(OS, FieldOffset, IndentLevel);
3382 }
3383 OS << Field.getType().getAsString() << ' ' << Field << '\n';
3384 }
3385
3386 // Dump virtual bases.
3387 if (CXXRD && IncludeVirtualBases) {
3388 const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3389 Layout.getVBaseOffsetsMap();
3390
3391 for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3392 assert(Base.isVirtual() && "Found non-virtual class!")((Base.isVirtual() && "Found non-virtual class!") ? static_cast
<void> (0) : __assert_fail ("Base.isVirtual() && \"Found non-virtual class!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/tools/clang/lib/AST/RecordLayoutBuilder.cpp"
, 3392, __PRETTY_FUNCTION__))
;
3393 const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3394
3395 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3396
3397 if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3398 PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3399 OS << "(vtordisp for vbase " << *VBase << ")\n";
3400 }
3401
3402 DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3403 VBase == Layout.getPrimaryBase() ?
3404 "(primary virtual base)" : "(virtual base)",
3405 /*PrintSizeInfo=*/false,
3406 /*IncludeVirtualBases=*/false);
3407 }
3408 }
3409
3410 if (!PrintSizeInfo) return;
3411
3412 PrintIndentNoOffset(OS, IndentLevel - 1);
3413 OS << "[sizeof=" << Layout.getSize().getQuantity();
3414 if (CXXRD && !isMsLayout(C))
3415 OS << ", dsize=" << Layout.getDataSize().getQuantity();
3416 OS << ", align=" << Layout.getAlignment().getQuantity();
3417
3418 if (CXXRD) {
3419 OS << ",\n";
3420 PrintIndentNoOffset(OS, IndentLevel - 1);
3421 OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3422 OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3423 }
3424 OS << "]\n";
3425}
3426
3427void ASTContext::DumpRecordLayout(const RecordDecl *RD,
3428 raw_ostream &OS,
3429 bool Simple) const {
3430 if (!Simple) {
1
Assuming 'Simple' is false
2
Taking true branch
3431 ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3
Calling 'DumpRecordLayout'
3432 /*PrintSizeInfo*/true,
3433 /*IncludeVirtualBases=*/true);
3434 return;
3435 }
3436
3437 // The "simple" format is designed to be parsed by the
3438 // layout-override testing code. There shouldn't be any external
3439 // uses of this format --- when LLDB overrides a layout, it sets up
3440 // the data structures directly --- so feel free to adjust this as
3441 // you like as long as you also update the rudimentary parser for it
3442 // in libFrontend.
3443
3444 const ASTRecordLayout &Info = getASTRecordLayout(RD);
3445 OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3446 OS << "\nLayout: ";
3447 OS << "<ASTRecordLayout\n";
3448 OS << " Size:" << toBits(Info.getSize()) << "\n";
3449 if (!isMsLayout(*this))
3450 OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3451 OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3452 OS << " FieldOffsets: [";
3453 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3454 if (i) OS << ", ";
3455 OS << Info.getFieldOffset(i);
3456 }
3457 OS << "]>\n";
3458}