Bug Summary

File:tools/clang/lib/AST/ExprConstant.cpp
Warning:line 5387, column 57
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 ExprConstant.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~svn374814/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn374814/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn374814/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn374814/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn374814/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~svn374814/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn374814=. -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-2019-10-15-035155-28452-1 -x c++ /build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp

/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp

1//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
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// This file implements the Expr constant evaluator.
10//
11// Constant expression evaluation produces four main results:
12//
13// * A success/failure flag indicating whether constant folding was successful.
14// This is the 'bool' return value used by most of the code in this file. A
15// 'false' return value indicates that constant folding has failed, and any
16// appropriate diagnostic has already been produced.
17//
18// * An evaluated result, valid only if constant folding has not failed.
19//
20// * A flag indicating if evaluation encountered (unevaluated) side-effects.
21// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
22// where it is possible to determine the evaluated result regardless.
23//
24// * A set of notes indicating why the evaluation was not a constant expression
25// (under the C++11 / C++1y rules only, at the moment), or, if folding failed
26// too, why the expression could not be folded.
27//
28// If we are checking for a potential constant expression, failure to constant
29// fold a potential constant sub-expression will be indicated by a 'false'
30// return value (the expression could not be folded) and no diagnostic (the
31// expression is not necessarily non-constant).
32//
33//===----------------------------------------------------------------------===//
34
35#include <cstring>
36#include <functional>
37#include "Interp/Context.h"
38#include "Interp/Frame.h"
39#include "Interp/State.h"
40#include "clang/AST/APValue.h"
41#include "clang/AST/ASTContext.h"
42#include "clang/AST/ASTDiagnostic.h"
43#include "clang/AST/ASTLambda.h"
44#include "clang/AST/CXXInheritance.h"
45#include "clang/AST/CharUnits.h"
46#include "clang/AST/CurrentSourceLocExprScope.h"
47#include "clang/AST/Expr.h"
48#include "clang/AST/OSLog.h"
49#include "clang/AST/OptionalDiagnostic.h"
50#include "clang/AST/RecordLayout.h"
51#include "clang/AST/StmtVisitor.h"
52#include "clang/AST/TypeLoc.h"
53#include "clang/Basic/Builtins.h"
54#include "clang/Basic/FixedPoint.h"
55#include "clang/Basic/TargetInfo.h"
56#include "llvm/ADT/Optional.h"
57#include "llvm/ADT/SmallBitVector.h"
58#include "llvm/Support/SaveAndRestore.h"
59#include "llvm/Support/raw_ostream.h"
60
61#define DEBUG_TYPE"exprconstant" "exprconstant"
62
63using namespace clang;
64using llvm::APInt;
65using llvm::APSInt;
66using llvm::APFloat;
67using llvm::Optional;
68
69namespace {
70 struct LValue;
71 class CallStackFrame;
72 class EvalInfo;
73
74 using SourceLocExprScopeGuard =
75 CurrentSourceLocExprScope::SourceLocExprScopeGuard;
76
77 static QualType getType(APValue::LValueBase B) {
78 if (!B) return QualType();
79 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
80 // FIXME: It's unclear where we're supposed to take the type from, and
81 // this actually matters for arrays of unknown bound. Eg:
82 //
83 // extern int arr[]; void f() { extern int arr[3]; };
84 // constexpr int *p = &arr[1]; // valid?
85 //
86 // For now, we take the array bound from the most recent declaration.
87 for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl;
88 Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) {
89 QualType T = Redecl->getType();
90 if (!T->isIncompleteArrayType())
91 return T;
92 }
93 return D->getType();
94 }
95
96 if (B.is<TypeInfoLValue>())
97 return B.getTypeInfoType();
98
99 if (B.is<DynamicAllocLValue>())
100 return B.getDynamicAllocType();
101
102 const Expr *Base = B.get<const Expr*>();
103
104 // For a materialized temporary, the type of the temporary we materialized
105 // may not be the type of the expression.
106 if (const MaterializeTemporaryExpr *MTE =
107 dyn_cast<MaterializeTemporaryExpr>(Base)) {
108 SmallVector<const Expr *, 2> CommaLHSs;
109 SmallVector<SubobjectAdjustment, 2> Adjustments;
110 const Expr *Temp = MTE->GetTemporaryExpr();
111 const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
112 Adjustments);
113 // Keep any cv-qualifiers from the reference if we generated a temporary
114 // for it directly. Otherwise use the type after adjustment.
115 if (!Adjustments.empty())
116 return Inner->getType();
117 }
118
119 return Base->getType();
120 }
121
122 /// Get an LValue path entry, which is known to not be an array index, as a
123 /// field declaration.
124 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
125 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
126 }
127 /// Get an LValue path entry, which is known to not be an array index, as a
128 /// base class declaration.
129 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
130 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
131 }
132 /// Determine whether this LValue path entry for a base class names a virtual
133 /// base class.
134 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
135 return E.getAsBaseOrMember().getInt();
136 }
137
138 /// Given an expression, determine the type used to store the result of
139 /// evaluating that expression.
140 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
141 if (E->isRValue())
142 return E->getType();
143 return Ctx.getLValueReferenceType(E->getType());
144 }
145
146 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
147 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
148 const FunctionDecl *Callee = CE->getDirectCallee();
149 return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr;
150 }
151
152 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
153 /// This will look through a single cast.
154 ///
155 /// Returns null if we couldn't unwrap a function with alloc_size.
156 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
157 if (!E->getType()->isPointerType())
158 return nullptr;
159
160 E = E->IgnoreParens();
161 // If we're doing a variable assignment from e.g. malloc(N), there will
162 // probably be a cast of some kind. In exotic cases, we might also see a
163 // top-level ExprWithCleanups. Ignore them either way.
164 if (const auto *FE = dyn_cast<FullExpr>(E))
165 E = FE->getSubExpr()->IgnoreParens();
166
167 if (const auto *Cast = dyn_cast<CastExpr>(E))
168 E = Cast->getSubExpr()->IgnoreParens();
169
170 if (const auto *CE = dyn_cast<CallExpr>(E))
171 return getAllocSizeAttr(CE) ? CE : nullptr;
172 return nullptr;
173 }
174
175 /// Determines whether or not the given Base contains a call to a function
176 /// with the alloc_size attribute.
177 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
178 const auto *E = Base.dyn_cast<const Expr *>();
179 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
180 }
181
182 /// The bound to claim that an array of unknown bound has.
183 /// The value in MostDerivedArraySize is undefined in this case. So, set it
184 /// to an arbitrary value that's likely to loudly break things if it's used.
185 static const uint64_t AssumedSizeForUnsizedArray =
186 std::numeric_limits<uint64_t>::max() / 2;
187
188 /// Determines if an LValue with the given LValueBase will have an unsized
189 /// array in its designator.
190 /// Find the path length and type of the most-derived subobject in the given
191 /// path, and find the size of the containing array, if any.
192 static unsigned
193 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
194 ArrayRef<APValue::LValuePathEntry> Path,
195 uint64_t &ArraySize, QualType &Type, bool &IsArray,
196 bool &FirstEntryIsUnsizedArray) {
197 // This only accepts LValueBases from APValues, and APValues don't support
198 // arrays that lack size info.
199 assert(!isBaseAnAllocSizeCall(Base) &&((!isBaseAnAllocSizeCall(Base) && "Unsized arrays shouldn't appear here"
) ? static_cast<void> (0) : __assert_fail ("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 200, __PRETTY_FUNCTION__))
200 "Unsized arrays shouldn't appear here")((!isBaseAnAllocSizeCall(Base) && "Unsized arrays shouldn't appear here"
) ? static_cast<void> (0) : __assert_fail ("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 200, __PRETTY_FUNCTION__))
;
201 unsigned MostDerivedLength = 0;
202 Type = getType(Base);
203
204 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
205 if (Type->isArrayType()) {
206 const ArrayType *AT = Ctx.getAsArrayType(Type);
207 Type = AT->getElementType();
208 MostDerivedLength = I + 1;
209 IsArray = true;
210
211 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
212 ArraySize = CAT->getSize().getZExtValue();
213 } else {
214 assert(I == 0 && "unexpected unsized array designator")((I == 0 && "unexpected unsized array designator") ? static_cast
<void> (0) : __assert_fail ("I == 0 && \"unexpected unsized array designator\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 214, __PRETTY_FUNCTION__))
;
215 FirstEntryIsUnsizedArray = true;
216 ArraySize = AssumedSizeForUnsizedArray;
217 }
218 } else if (Type->isAnyComplexType()) {
219 const ComplexType *CT = Type->castAs<ComplexType>();
220 Type = CT->getElementType();
221 ArraySize = 2;
222 MostDerivedLength = I + 1;
223 IsArray = true;
224 } else if (const FieldDecl *FD = getAsField(Path[I])) {
225 Type = FD->getType();
226 ArraySize = 0;
227 MostDerivedLength = I + 1;
228 IsArray = false;
229 } else {
230 // Path[I] describes a base class.
231 ArraySize = 0;
232 IsArray = false;
233 }
234 }
235 return MostDerivedLength;
236 }
237
238 /// A path from a glvalue to a subobject of that glvalue.
239 struct SubobjectDesignator {
240 /// True if the subobject was named in a manner not supported by C++11. Such
241 /// lvalues can still be folded, but they are not core constant expressions
242 /// and we cannot perform lvalue-to-rvalue conversions on them.
243 unsigned Invalid : 1;
244
245 /// Is this a pointer one past the end of an object?
246 unsigned IsOnePastTheEnd : 1;
247
248 /// Indicator of whether the first entry is an unsized array.
249 unsigned FirstEntryIsAnUnsizedArray : 1;
250
251 /// Indicator of whether the most-derived object is an array element.
252 unsigned MostDerivedIsArrayElement : 1;
253
254 /// The length of the path to the most-derived object of which this is a
255 /// subobject.
256 unsigned MostDerivedPathLength : 28;
257
258 /// The size of the array of which the most-derived object is an element.
259 /// This will always be 0 if the most-derived object is not an array
260 /// element. 0 is not an indicator of whether or not the most-derived object
261 /// is an array, however, because 0-length arrays are allowed.
262 ///
263 /// If the current array is an unsized array, the value of this is
264 /// undefined.
265 uint64_t MostDerivedArraySize;
266
267 /// The type of the most derived object referred to by this address.
268 QualType MostDerivedType;
269
270 typedef APValue::LValuePathEntry PathEntry;
271
272 /// The entries on the path from the glvalue to the designated subobject.
273 SmallVector<PathEntry, 8> Entries;
274
275 SubobjectDesignator() : Invalid(true) {}
276
277 explicit SubobjectDesignator(QualType T)
278 : Invalid(false), IsOnePastTheEnd(false),
279 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
280 MostDerivedPathLength(0), MostDerivedArraySize(0),
281 MostDerivedType(T) {}
282
283 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
284 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
285 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
286 MostDerivedPathLength(0), MostDerivedArraySize(0) {
287 assert(V.isLValue() && "Non-LValue used to make an LValue designator?")((V.isLValue() && "Non-LValue used to make an LValue designator?"
) ? static_cast<void> (0) : __assert_fail ("V.isLValue() && \"Non-LValue used to make an LValue designator?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 287, __PRETTY_FUNCTION__))
;
288 if (!Invalid) {
289 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
290 ArrayRef<PathEntry> VEntries = V.getLValuePath();
291 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
292 if (V.getLValueBase()) {
293 bool IsArray = false;
294 bool FirstIsUnsizedArray = false;
295 MostDerivedPathLength = findMostDerivedSubobject(
296 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
297 MostDerivedType, IsArray, FirstIsUnsizedArray);
298 MostDerivedIsArrayElement = IsArray;
299 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
300 }
301 }
302 }
303
304 void truncate(ASTContext &Ctx, APValue::LValueBase Base,
305 unsigned NewLength) {
306 if (Invalid)
307 return;
308
309 assert(Base && "cannot truncate path for null pointer")((Base && "cannot truncate path for null pointer") ? static_cast
<void> (0) : __assert_fail ("Base && \"cannot truncate path for null pointer\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 309, __PRETTY_FUNCTION__))
;
310 assert(NewLength <= Entries.size() && "not a truncation")((NewLength <= Entries.size() && "not a truncation"
) ? static_cast<void> (0) : __assert_fail ("NewLength <= Entries.size() && \"not a truncation\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 310, __PRETTY_FUNCTION__))
;
311
312 if (NewLength == Entries.size())
313 return;
314 Entries.resize(NewLength);
315
316 bool IsArray = false;
317 bool FirstIsUnsizedArray = false;
318 MostDerivedPathLength = findMostDerivedSubobject(
319 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
320 FirstIsUnsizedArray);
321 MostDerivedIsArrayElement = IsArray;
322 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
323 }
324
325 void setInvalid() {
326 Invalid = true;
327 Entries.clear();
328 }
329
330 /// Determine whether the most derived subobject is an array without a
331 /// known bound.
332 bool isMostDerivedAnUnsizedArray() const {
333 assert(!Invalid && "Calling this makes no sense on invalid designators")((!Invalid && "Calling this makes no sense on invalid designators"
) ? static_cast<void> (0) : __assert_fail ("!Invalid && \"Calling this makes no sense on invalid designators\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 333, __PRETTY_FUNCTION__))
;
334 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
335 }
336
337 /// Determine what the most derived array's size is. Results in an assertion
338 /// failure if the most derived array lacks a size.
339 uint64_t getMostDerivedArraySize() const {
340 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size")((!isMostDerivedAnUnsizedArray() && "Unsized array has no size"
) ? static_cast<void> (0) : __assert_fail ("!isMostDerivedAnUnsizedArray() && \"Unsized array has no size\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 340, __PRETTY_FUNCTION__))
;
341 return MostDerivedArraySize;
342 }
343
344 /// Determine whether this is a one-past-the-end pointer.
345 bool isOnePastTheEnd() const {
346 assert(!Invalid)((!Invalid) ? static_cast<void> (0) : __assert_fail ("!Invalid"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 346, __PRETTY_FUNCTION__))
;
347 if (IsOnePastTheEnd)
348 return true;
349 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
350 Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
351 MostDerivedArraySize)
352 return true;
353 return false;
354 }
355
356 /// Get the range of valid index adjustments in the form
357 /// {maximum value that can be subtracted from this pointer,
358 /// maximum value that can be added to this pointer}
359 std::pair<uint64_t, uint64_t> validIndexAdjustments() {
360 if (Invalid || isMostDerivedAnUnsizedArray())
361 return {0, 0};
362
363 // [expr.add]p4: For the purposes of these operators, a pointer to a
364 // nonarray object behaves the same as a pointer to the first element of
365 // an array of length one with the type of the object as its element type.
366 bool IsArray = MostDerivedPathLength == Entries.size() &&
367 MostDerivedIsArrayElement;
368 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
369 : (uint64_t)IsOnePastTheEnd;
370 uint64_t ArraySize =
371 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
372 return {ArrayIndex, ArraySize - ArrayIndex};
373 }
374
375 /// Check that this refers to a valid subobject.
376 bool isValidSubobject() const {
377 if (Invalid)
378 return false;
379 return !isOnePastTheEnd();
380 }
381 /// Check that this refers to a valid subobject, and if not, produce a
382 /// relevant diagnostic and set the designator as invalid.
383 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
384
385 /// Get the type of the designated object.
386 QualType getType(ASTContext &Ctx) const {
387 assert(!Invalid && "invalid designator has no subobject type")((!Invalid && "invalid designator has no subobject type"
) ? static_cast<void> (0) : __assert_fail ("!Invalid && \"invalid designator has no subobject type\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 387, __PRETTY_FUNCTION__))
;
388 return MostDerivedPathLength == Entries.size()
389 ? MostDerivedType
390 : Ctx.getRecordType(getAsBaseClass(Entries.back()));
391 }
392
393 /// Update this designator to refer to the first element within this array.
394 void addArrayUnchecked(const ConstantArrayType *CAT) {
395 Entries.push_back(PathEntry::ArrayIndex(0));
396
397 // This is a most-derived object.
398 MostDerivedType = CAT->getElementType();
399 MostDerivedIsArrayElement = true;
400 MostDerivedArraySize = CAT->getSize().getZExtValue();
401 MostDerivedPathLength = Entries.size();
402 }
403 /// Update this designator to refer to the first element within the array of
404 /// elements of type T. This is an array of unknown size.
405 void addUnsizedArrayUnchecked(QualType ElemTy) {
406 Entries.push_back(PathEntry::ArrayIndex(0));
407
408 MostDerivedType = ElemTy;
409 MostDerivedIsArrayElement = true;
410 // The value in MostDerivedArraySize is undefined in this case. So, set it
411 // to an arbitrary value that's likely to loudly break things if it's
412 // used.
413 MostDerivedArraySize = AssumedSizeForUnsizedArray;
414 MostDerivedPathLength = Entries.size();
415 }
416 /// Update this designator to refer to the given base or member of this
417 /// object.
418 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
419 Entries.push_back(APValue::BaseOrMemberType(D, Virtual));
420
421 // If this isn't a base class, it's a new most-derived object.
422 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
423 MostDerivedType = FD->getType();
424 MostDerivedIsArrayElement = false;
425 MostDerivedArraySize = 0;
426 MostDerivedPathLength = Entries.size();
427 }
428 }
429 /// Update this designator to refer to the given complex component.
430 void addComplexUnchecked(QualType EltTy, bool Imag) {
431 Entries.push_back(PathEntry::ArrayIndex(Imag));
432
433 // This is technically a most-derived object, though in practice this
434 // is unlikely to matter.
435 MostDerivedType = EltTy;
436 MostDerivedIsArrayElement = true;
437 MostDerivedArraySize = 2;
438 MostDerivedPathLength = Entries.size();
439 }
440 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
441 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
442 const APSInt &N);
443 /// Add N to the address of this subobject.
444 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
445 if (Invalid || !N) return;
446 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
447 if (isMostDerivedAnUnsizedArray()) {
448 diagnoseUnsizedArrayPointerArithmetic(Info, E);
449 // Can't verify -- trust that the user is doing the right thing (or if
450 // not, trust that the caller will catch the bad behavior).
451 // FIXME: Should we reject if this overflows, at least?
452 Entries.back() = PathEntry::ArrayIndex(
453 Entries.back().getAsArrayIndex() + TruncatedN);
454 return;
455 }
456
457 // [expr.add]p4: For the purposes of these operators, a pointer to a
458 // nonarray object behaves the same as a pointer to the first element of
459 // an array of length one with the type of the object as its element type.
460 bool IsArray = MostDerivedPathLength == Entries.size() &&
461 MostDerivedIsArrayElement;
462 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
463 : (uint64_t)IsOnePastTheEnd;
464 uint64_t ArraySize =
465 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
466
467 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
468 // Calculate the actual index in a wide enough type, so we can include
469 // it in the note.
470 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
471 (llvm::APInt&)N += ArrayIndex;
472 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index")((N.ugt(ArraySize) && "bounds check failed for in-bounds index"
) ? static_cast<void> (0) : __assert_fail ("N.ugt(ArraySize) && \"bounds check failed for in-bounds index\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 472, __PRETTY_FUNCTION__))
;
473 diagnosePointerArithmetic(Info, E, N);
474 setInvalid();
475 return;
476 }
477
478 ArrayIndex += TruncatedN;
479 assert(ArrayIndex <= ArraySize &&((ArrayIndex <= ArraySize && "bounds check succeeded for out-of-bounds index"
) ? static_cast<void> (0) : __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 480, __PRETTY_FUNCTION__))
480 "bounds check succeeded for out-of-bounds index")((ArrayIndex <= ArraySize && "bounds check succeeded for out-of-bounds index"
) ? static_cast<void> (0) : __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 480, __PRETTY_FUNCTION__))
;
481
482 if (IsArray)
483 Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
484 else
485 IsOnePastTheEnd = (ArrayIndex != 0);
486 }
487 };
488
489 /// A stack frame in the constexpr call stack.
490 class CallStackFrame : public interp::Frame {
491 public:
492 EvalInfo &Info;
493
494 /// Parent - The caller of this stack frame.
495 CallStackFrame *Caller;
496
497 /// Callee - The function which was called.
498 const FunctionDecl *Callee;
499
500 /// This - The binding for the this pointer in this call, if any.
501 const LValue *This;
502
503 /// Arguments - Parameter bindings for this function call, indexed by
504 /// parameters' function scope indices.
505 APValue *Arguments;
506
507 /// Source location information about the default argument or default
508 /// initializer expression we're evaluating, if any.
509 CurrentSourceLocExprScope CurSourceLocExprScope;
510
511 // Note that we intentionally use std::map here so that references to
512 // values are stable.
513 typedef std::pair<const void *, unsigned> MapKeyTy;
514 typedef std::map<MapKeyTy, APValue> MapTy;
515 /// Temporaries - Temporary lvalues materialized within this stack frame.
516 MapTy Temporaries;
517
518 /// CallLoc - The location of the call expression for this call.
519 SourceLocation CallLoc;
520
521 /// Index - The call index of this call.
522 unsigned Index;
523
524 /// The stack of integers for tracking version numbers for temporaries.
525 SmallVector<unsigned, 2> TempVersionStack = {1};
526 unsigned CurTempVersion = TempVersionStack.back();
527
528 unsigned getTempVersion() const { return TempVersionStack.back(); }
529
530 void pushTempVersion() {
531 TempVersionStack.push_back(++CurTempVersion);
532 }
533
534 void popTempVersion() {
535 TempVersionStack.pop_back();
536 }
537
538 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
539 // on the overall stack usage of deeply-recursing constexpr evaluations.
540 // (We should cache this map rather than recomputing it repeatedly.)
541 // But let's try this and see how it goes; we can look into caching the map
542 // as a later change.
543
544 /// LambdaCaptureFields - Mapping from captured variables/this to
545 /// corresponding data members in the closure class.
546 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
547 FieldDecl *LambdaThisCaptureField;
548
549 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
550 const FunctionDecl *Callee, const LValue *This,
551 APValue *Arguments);
552 ~CallStackFrame();
553
554 // Return the temporary for Key whose version number is Version.
555 APValue *getTemporary(const void *Key, unsigned Version) {
556 MapKeyTy KV(Key, Version);
557 auto LB = Temporaries.lower_bound(KV);
558 if (LB != Temporaries.end() && LB->first == KV)
559 return &LB->second;
560 // Pair (Key,Version) wasn't found in the map. Check that no elements
561 // in the map have 'Key' as their key.
562 assert((LB == Temporaries.end() || LB->first.first != Key) &&(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 564, __PRETTY_FUNCTION__))
563 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 564, __PRETTY_FUNCTION__))
564 "Element with key 'Key' found in map")(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 564, __PRETTY_FUNCTION__))
;
565 return nullptr;
566 }
567
568 // Return the current temporary for Key in the map.
569 APValue *getCurrentTemporary(const void *Key) {
570 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
571 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
572 return &std::prev(UB)->second;
573 return nullptr;
574 }
575
576 // Return the version number of the current temporary for Key.
577 unsigned getCurrentTemporaryVersion(const void *Key) const {
578 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
579 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
580 return std::prev(UB)->first.second;
581 return 0;
582 }
583
584 /// Allocate storage for an object of type T in this stack frame.
585 /// Populates LV with a handle to the created object. Key identifies
586 /// the temporary within the stack frame, and must not be reused without
587 /// bumping the temporary version number.
588 template<typename KeyT>
589 APValue &createTemporary(const KeyT *Key, QualType T,
590 bool IsLifetimeExtended, LValue &LV);
591
592 void describe(llvm::raw_ostream &OS) override;
593
594 Frame *getCaller() const override { return Caller; }
595 SourceLocation getCallLocation() const override { return CallLoc; }
596 const FunctionDecl *getCallee() const override { return Callee; }
597
598 bool isStdFunction() const {
599 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
600 if (DC->isStdNamespace())
601 return true;
602 return false;
603 }
604 };
605
606 /// Temporarily override 'this'.
607 class ThisOverrideRAII {
608 public:
609 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
610 : Frame(Frame), OldThis(Frame.This) {
611 if (Enable)
612 Frame.This = NewThis;
613 }
614 ~ThisOverrideRAII() {
615 Frame.This = OldThis;
616 }
617 private:
618 CallStackFrame &Frame;
619 const LValue *OldThis;
620 };
621}
622
623static bool HandleDestruction(EvalInfo &Info, const Expr *E,
624 const LValue &This, QualType ThisType);
625static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
626 APValue::LValueBase LVBase, APValue &Value,
627 QualType T);
628
629namespace {
630 /// A cleanup, and a flag indicating whether it is lifetime-extended.
631 class Cleanup {
632 llvm::PointerIntPair<APValue*, 1, bool> Value;
633 APValue::LValueBase Base;
634 QualType T;
635
636 public:
637 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
638 bool IsLifetimeExtended)
639 : Value(Val, IsLifetimeExtended), Base(Base), T(T) {}
640
641 bool isLifetimeExtended() const { return Value.getInt(); }
642 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
643 if (RunDestructors) {
644 SourceLocation Loc;
645 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
646 Loc = VD->getLocation();
647 else if (const Expr *E = Base.dyn_cast<const Expr*>())
648 Loc = E->getExprLoc();
649 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
650 }
651 *Value.getPointer() = APValue();
652 return true;
653 }
654
655 bool hasSideEffect() {
656 return T.isDestructedType();
657 }
658 };
659
660 /// A reference to an object whose construction we are currently evaluating.
661 struct ObjectUnderConstruction {
662 APValue::LValueBase Base;
663 ArrayRef<APValue::LValuePathEntry> Path;
664 friend bool operator==(const ObjectUnderConstruction &LHS,
665 const ObjectUnderConstruction &RHS) {
666 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
667 }
668 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
669 return llvm::hash_combine(Obj.Base, Obj.Path);
670 }
671 };
672 enum class ConstructionPhase {
673 None,
674 Bases,
675 AfterBases,
676 Destroying,
677 DestroyingBases
678 };
679}
680
681namespace llvm {
682template<> struct DenseMapInfo<ObjectUnderConstruction> {
683 using Base = DenseMapInfo<APValue::LValueBase>;
684 static ObjectUnderConstruction getEmptyKey() {
685 return {Base::getEmptyKey(), {}}; }
686 static ObjectUnderConstruction getTombstoneKey() {
687 return {Base::getTombstoneKey(), {}};
688 }
689 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
690 return hash_value(Object);
691 }
692 static bool isEqual(const ObjectUnderConstruction &LHS,
693 const ObjectUnderConstruction &RHS) {
694 return LHS == RHS;
695 }
696};
697}
698
699namespace {
700 /// A dynamically-allocated heap object.
701 struct DynAlloc {
702 /// The value of this heap-allocated object.
703 APValue Value;
704 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
705 /// or a CallExpr (the latter is for direct calls to operator new inside
706 /// std::allocator<T>::allocate).
707 const Expr *AllocExpr = nullptr;
708
709 enum Kind {
710 New,
711 ArrayNew,
712 StdAllocator
713 };
714
715 /// Get the kind of the allocation. This must match between allocation
716 /// and deallocation.
717 Kind getKind() const {
718 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
719 return NE->isArray() ? ArrayNew : New;
720 assert(isa<CallExpr>(AllocExpr))((isa<CallExpr>(AllocExpr)) ? static_cast<void> (
0) : __assert_fail ("isa<CallExpr>(AllocExpr)", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 720, __PRETTY_FUNCTION__))
;
721 return StdAllocator;
722 }
723 };
724
725 struct DynAllocOrder {
726 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
727 return L.getIndex() < R.getIndex();
728 }
729 };
730
731 /// EvalInfo - This is a private struct used by the evaluator to capture
732 /// information about a subexpression as it is folded. It retains information
733 /// about the AST context, but also maintains information about the folded
734 /// expression.
735 ///
736 /// If an expression could be evaluated, it is still possible it is not a C
737 /// "integer constant expression" or constant expression. If not, this struct
738 /// captures information about how and why not.
739 ///
740 /// One bit of information passed *into* the request for constant folding
741 /// indicates whether the subexpression is "evaluated" or not according to C
742 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
743 /// evaluate the expression regardless of what the RHS is, but C only allows
744 /// certain things in certain situations.
745 class EvalInfo : public interp::State {
746 public:
747 ASTContext &Ctx;
748
749 /// EvalStatus - Contains information about the evaluation.
750 Expr::EvalStatus &EvalStatus;
751
752 /// CurrentCall - The top of the constexpr call stack.
753 CallStackFrame *CurrentCall;
754
755 /// CallStackDepth - The number of calls in the call stack right now.
756 unsigned CallStackDepth;
757
758 /// NextCallIndex - The next call index to assign.
759 unsigned NextCallIndex;
760
761 /// StepsLeft - The remaining number of evaluation steps we're permitted
762 /// to perform. This is essentially a limit for the number of statements
763 /// we will evaluate.
764 unsigned StepsLeft;
765
766 /// Force the use of the experimental new constant interpreter, bailing out
767 /// with an error if a feature is not supported.
768 bool ForceNewConstInterp;
769
770 /// Enable the experimental new constant interpreter.
771 bool EnableNewConstInterp;
772
773 /// BottomFrame - The frame in which evaluation started. This must be
774 /// initialized after CurrentCall and CallStackDepth.
775 CallStackFrame BottomFrame;
776
777 /// A stack of values whose lifetimes end at the end of some surrounding
778 /// evaluation frame.
779 llvm::SmallVector<Cleanup, 16> CleanupStack;
780
781 /// EvaluatingDecl - This is the declaration whose initializer is being
782 /// evaluated, if any.
783 APValue::LValueBase EvaluatingDecl;
784
785 enum class EvaluatingDeclKind {
786 None,
787 /// We're evaluating the construction of EvaluatingDecl.
788 Ctor,
789 /// We're evaluating the destruction of EvaluatingDecl.
790 Dtor,
791 };
792 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
793
794 /// EvaluatingDeclValue - This is the value being constructed for the
795 /// declaration whose initializer is being evaluated, if any.
796 APValue *EvaluatingDeclValue;
797
798 /// Set of objects that are currently being constructed.
799 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
800 ObjectsUnderConstruction;
801
802 /// Current heap allocations, along with the location where each was
803 /// allocated. We use std::map here because we need stable addresses
804 /// for the stored APValues.
805 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
806
807 /// The number of heap allocations performed so far in this evaluation.
808 unsigned NumHeapAllocs = 0;
809
810 struct EvaluatingConstructorRAII {
811 EvalInfo &EI;
812 ObjectUnderConstruction Object;
813 bool DidInsert;
814 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
815 bool HasBases)
816 : EI(EI), Object(Object) {
817 DidInsert =
818 EI.ObjectsUnderConstruction
819 .insert({Object, HasBases ? ConstructionPhase::Bases
820 : ConstructionPhase::AfterBases})
821 .second;
822 }
823 void finishedConstructingBases() {
824 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
825 }
826 ~EvaluatingConstructorRAII() {
827 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
828 }
829 };
830
831 struct EvaluatingDestructorRAII {
832 EvalInfo &EI;
833 ObjectUnderConstruction Object;
834 bool DidInsert;
835 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
836 : EI(EI), Object(Object) {
837 DidInsert = EI.ObjectsUnderConstruction
838 .insert({Object, ConstructionPhase::Destroying})
839 .second;
840 }
841 void startedDestroyingBases() {
842 EI.ObjectsUnderConstruction[Object] =
843 ConstructionPhase::DestroyingBases;
844 }
845 ~EvaluatingDestructorRAII() {
846 if (DidInsert)
847 EI.ObjectsUnderConstruction.erase(Object);
848 }
849 };
850
851 ConstructionPhase
852 isEvaluatingCtorDtor(APValue::LValueBase Base,
853 ArrayRef<APValue::LValuePathEntry> Path) {
854 return ObjectsUnderConstruction.lookup({Base, Path});
855 }
856
857 /// If we're currently speculatively evaluating, the outermost call stack
858 /// depth at which we can mutate state, otherwise 0.
859 unsigned SpeculativeEvaluationDepth = 0;
860
861 /// The current array initialization index, if we're performing array
862 /// initialization.
863 uint64_t ArrayInitIndex = -1;
864
865 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
866 /// notes attached to it will also be stored, otherwise they will not be.
867 bool HasActiveDiagnostic;
868
869 /// Have we emitted a diagnostic explaining why we couldn't constant
870 /// fold (not just why it's not strictly a constant expression)?
871 bool HasFoldFailureDiagnostic;
872
873 /// Whether or not we're in a context where the front end requires a
874 /// constant value.
875 bool InConstantContext;
876
877 /// Whether we're checking that an expression is a potential constant
878 /// expression. If so, do not fail on constructs that could become constant
879 /// later on (such as a use of an undefined global).
880 bool CheckingPotentialConstantExpression = false;
881
882 /// Whether we're checking for an expression that has undefined behavior.
883 /// If so, we will produce warnings if we encounter an operation that is
884 /// always undefined.
885 bool CheckingForUndefinedBehavior = false;
886
887 enum EvaluationMode {
888 /// Evaluate as a constant expression. Stop if we find that the expression
889 /// is not a constant expression.
890 EM_ConstantExpression,
891
892 /// Evaluate as a constant expression. Stop if we find that the expression
893 /// is not a constant expression. Some expressions can be retried in the
894 /// optimizer if we don't constant fold them here, but in an unevaluated
895 /// context we try to fold them immediately since the optimizer never
896 /// gets a chance to look at it.
897 EM_ConstantExpressionUnevaluated,
898
899 /// Fold the expression to a constant. Stop if we hit a side-effect that
900 /// we can't model.
901 EM_ConstantFold,
902
903 /// Evaluate in any way we know how. Don't worry about side-effects that
904 /// can't be modeled.
905 EM_IgnoreSideEffects,
906 } EvalMode;
907
908 /// Are we checking whether the expression is a potential constant
909 /// expression?
910 bool checkingPotentialConstantExpression() const override {
911 return CheckingPotentialConstantExpression;
912 }
913
914 /// Are we checking an expression for overflow?
915 // FIXME: We should check for any kind of undefined or suspicious behavior
916 // in such constructs, not just overflow.
917 bool checkingForUndefinedBehavior() const override {
918 return CheckingForUndefinedBehavior;
919 }
920
921 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
922 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
923 CallStackDepth(0), NextCallIndex(1),
924 StepsLeft(getLangOpts().ConstexprStepLimit),
925 ForceNewConstInterp(getLangOpts().ForceNewConstInterp),
926 EnableNewConstInterp(ForceNewConstInterp ||
927 getLangOpts().EnableNewConstInterp),
928 BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr),
929 EvaluatingDecl((const ValueDecl *)nullptr),
930 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
931 HasFoldFailureDiagnostic(false), InConstantContext(false),
932 EvalMode(Mode) {}
933
934 ~EvalInfo() {
935 discardCleanups();
936 }
937
938 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
939 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
940 EvaluatingDecl = Base;
941 IsEvaluatingDecl = EDK;
942 EvaluatingDeclValue = &Value;
943 }
944
945 bool CheckCallLimit(SourceLocation Loc) {
946 // Don't perform any constexpr calls (other than the call we're checking)
947 // when checking a potential constant expression.
948 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
37
Assuming the condition is false
949 return false;
950 if (NextCallIndex == 0) {
38
Assuming field 'NextCallIndex' is not equal to 0
39
Taking false branch
951 // NextCallIndex has wrapped around.
952 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
953 return false;
954 }
955 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
40
Assuming field 'CallStackDepth' is <= field 'ConstexprCallDepth'
41
Taking true branch
956 return true;
42
Returning the value 1, which participates in a condition later
957 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
958 << getLangOpts().ConstexprCallDepth;
959 return false;
960 }
961
962 std::pair<CallStackFrame *, unsigned>
963 getCallFrameAndDepth(unsigned CallIndex) {
964 assert(CallIndex && "no call index in getCallFrameAndDepth")((CallIndex && "no call index in getCallFrameAndDepth"
) ? static_cast<void> (0) : __assert_fail ("CallIndex && \"no call index in getCallFrameAndDepth\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 964, __PRETTY_FUNCTION__))
;
965 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
966 // be null in this loop.
967 unsigned Depth = CallStackDepth;
968 CallStackFrame *Frame = CurrentCall;
969 while (Frame->Index > CallIndex) {
970 Frame = Frame->Caller;
971 --Depth;
972 }
973 if (Frame->Index == CallIndex)
974 return {Frame, Depth};
975 return {nullptr, 0};
976 }
977
978 bool nextStep(const Stmt *S) {
979 if (!StepsLeft) {
980 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
981 return false;
982 }
983 --StepsLeft;
984 return true;
985 }
986
987 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
988
989 Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) {
990 Optional<DynAlloc*> Result;
991 auto It = HeapAllocs.find(DA);
992 if (It != HeapAllocs.end())
993 Result = &It->second;
994 return Result;
995 }
996
997 /// Information about a stack frame for std::allocator<T>::[de]allocate.
998 struct StdAllocatorCaller {
999 unsigned FrameIndex;
1000 QualType ElemType;
1001 explicit operator bool() const { return FrameIndex != 0; };
1002 };
1003
1004 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1005 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1006 Call = Call->Caller) {
1007 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1008 if (!MD)
1009 continue;
1010 const IdentifierInfo *FnII = MD->getIdentifier();
1011 if (!FnII || !FnII->isStr(FnName))
1012 continue;
1013
1014 const auto *CTSD =
1015 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1016 if (!CTSD)
1017 continue;
1018
1019 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1020 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1021 if (CTSD->isInStdNamespace() && ClassII &&
1022 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1023 TAL[0].getKind() == TemplateArgument::Type)
1024 return {Call->Index, TAL[0].getAsType()};
1025 }
1026
1027 return {};
1028 }
1029
1030 void performLifetimeExtension() {
1031 // Disable the cleanups for lifetime-extended temporaries.
1032 CleanupStack.erase(
1033 std::remove_if(CleanupStack.begin(), CleanupStack.end(),
1034 [](Cleanup &C) { return C.isLifetimeExtended(); }),
1035 CleanupStack.end());
1036 }
1037
1038 /// Throw away any remaining cleanups at the end of evaluation. If any
1039 /// cleanups would have had a side-effect, note that as an unmodeled
1040 /// side-effect and return false. Otherwise, return true.
1041 bool discardCleanups() {
1042 for (Cleanup &C : CleanupStack)
1043 if (C.hasSideEffect())
1044 if (!noteSideEffect())
1045 return false;
1046 return true;
1047 }
1048
1049 private:
1050 interp::Frame *getCurrentFrame() override { return CurrentCall; }
1051 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1052
1053 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
1054 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1055
1056 void setFoldFailureDiagnostic(bool Flag) override {
1057 HasFoldFailureDiagnostic = Flag;
1058 }
1059
1060 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1061
1062 ASTContext &getCtx() const override { return Ctx; }
1063
1064 // If we have a prior diagnostic, it will be noting that the expression
1065 // isn't a constant expression. This diagnostic is more important,
1066 // unless we require this evaluation to produce a constant expression.
1067 //
1068 // FIXME: We might want to show both diagnostics to the user in
1069 // EM_ConstantFold mode.
1070 bool hasPriorDiagnostic() override {
1071 if (!EvalStatus.Diag->empty()) {
1072 switch (EvalMode) {
1073 case EM_ConstantFold:
1074 case EM_IgnoreSideEffects:
1075 if (!HasFoldFailureDiagnostic)
1076 break;
1077 // We've already failed to fold something. Keep that diagnostic.
1078 LLVM_FALLTHROUGH[[gnu::fallthrough]];
1079 case EM_ConstantExpression:
1080 case EM_ConstantExpressionUnevaluated:
1081 setActiveDiagnostic(false);
1082 return true;
1083 }
1084 }
1085 return false;
1086 }
1087
1088 unsigned getCallStackDepth() override { return CallStackDepth; }
1089
1090 public:
1091 /// Should we continue evaluation after encountering a side-effect that we
1092 /// couldn't model?
1093 bool keepEvaluatingAfterSideEffect() {
1094 switch (EvalMode) {
1095 case EM_IgnoreSideEffects:
1096 return true;
1097
1098 case EM_ConstantExpression:
1099 case EM_ConstantExpressionUnevaluated:
1100 case EM_ConstantFold:
1101 // By default, assume any side effect might be valid in some other
1102 // evaluation of this expression from a different context.
1103 return checkingPotentialConstantExpression() ||
1104 checkingForUndefinedBehavior();
1105 }
1106 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1106)
;
1107 }
1108
1109 /// Note that we have had a side-effect, and determine whether we should
1110 /// keep evaluating.
1111 bool noteSideEffect() {
1112 EvalStatus.HasSideEffects = true;
1113 return keepEvaluatingAfterSideEffect();
1114 }
1115
1116 /// Should we continue evaluation after encountering undefined behavior?
1117 bool keepEvaluatingAfterUndefinedBehavior() {
1118 switch (EvalMode) {
1119 case EM_IgnoreSideEffects:
1120 case EM_ConstantFold:
1121 return true;
1122
1123 case EM_ConstantExpression:
1124 case EM_ConstantExpressionUnevaluated:
1125 return checkingForUndefinedBehavior();
1126 }
1127 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1127)
;
1128 }
1129
1130 /// Note that we hit something that was technically undefined behavior, but
1131 /// that we can evaluate past it (such as signed overflow or floating-point
1132 /// division by zero.)
1133 bool noteUndefinedBehavior() override {
1134 EvalStatus.HasUndefinedBehavior = true;
1135 return keepEvaluatingAfterUndefinedBehavior();
1136 }
1137
1138 /// Should we continue evaluation as much as possible after encountering a
1139 /// construct which can't be reduced to a value?
1140 bool keepEvaluatingAfterFailure() const override {
1141 if (!StepsLeft)
1142 return false;
1143
1144 switch (EvalMode) {
1145 case EM_ConstantExpression:
1146 case EM_ConstantExpressionUnevaluated:
1147 case EM_ConstantFold:
1148 case EM_IgnoreSideEffects:
1149 return checkingPotentialConstantExpression() ||
1150 checkingForUndefinedBehavior();
1151 }
1152 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1152)
;
1153 }
1154
1155 /// Notes that we failed to evaluate an expression that other expressions
1156 /// directly depend on, and determine if we should keep evaluating. This
1157 /// should only be called if we actually intend to keep evaluating.
1158 ///
1159 /// Call noteSideEffect() instead if we may be able to ignore the value that
1160 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1161 ///
1162 /// (Foo(), 1) // use noteSideEffect
1163 /// (Foo() || true) // use noteSideEffect
1164 /// Foo() + 1 // use noteFailure
1165 LLVM_NODISCARD[[clang::warn_unused_result]] bool noteFailure() {
1166 // Failure when evaluating some expression often means there is some
1167 // subexpression whose evaluation was skipped. Therefore, (because we
1168 // don't track whether we skipped an expression when unwinding after an
1169 // evaluation failure) every evaluation failure that bubbles up from a
1170 // subexpression implies that a side-effect has potentially happened. We
1171 // skip setting the HasSideEffects flag to true until we decide to
1172 // continue evaluating after that point, which happens here.
1173 bool KeepGoing = keepEvaluatingAfterFailure();
1174 EvalStatus.HasSideEffects |= KeepGoing;
1175 return KeepGoing;
1176 }
1177
1178 class ArrayInitLoopIndex {
1179 EvalInfo &Info;
1180 uint64_t OuterIndex;
1181
1182 public:
1183 ArrayInitLoopIndex(EvalInfo &Info)
1184 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1185 Info.ArrayInitIndex = 0;
1186 }
1187 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1188
1189 operator uint64_t&() { return Info.ArrayInitIndex; }
1190 };
1191 };
1192
1193 /// Object used to treat all foldable expressions as constant expressions.
1194 struct FoldConstant {
1195 EvalInfo &Info;
1196 bool Enabled;
1197 bool HadNoPriorDiags;
1198 EvalInfo::EvaluationMode OldMode;
1199
1200 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1201 : Info(Info),
1202 Enabled(Enabled),
1203 HadNoPriorDiags(Info.EvalStatus.Diag &&
1204 Info.EvalStatus.Diag->empty() &&
1205 !Info.EvalStatus.HasSideEffects),
1206 OldMode(Info.EvalMode) {
1207 if (Enabled)
1208 Info.EvalMode = EvalInfo::EM_ConstantFold;
1209 }
1210 void keepDiagnostics() { Enabled = false; }
1211 ~FoldConstant() {
1212 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1213 !Info.EvalStatus.HasSideEffects)
1214 Info.EvalStatus.Diag->clear();
1215 Info.EvalMode = OldMode;
1216 }
1217 };
1218
1219 /// RAII object used to set the current evaluation mode to ignore
1220 /// side-effects.
1221 struct IgnoreSideEffectsRAII {
1222 EvalInfo &Info;
1223 EvalInfo::EvaluationMode OldMode;
1224 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1225 : Info(Info), OldMode(Info.EvalMode) {
1226 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1227 }
1228
1229 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1230 };
1231
1232 /// RAII object used to optionally suppress diagnostics and side-effects from
1233 /// a speculative evaluation.
1234 class SpeculativeEvaluationRAII {
1235 EvalInfo *Info = nullptr;
1236 Expr::EvalStatus OldStatus;
1237 unsigned OldSpeculativeEvaluationDepth;
1238
1239 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1240 Info = Other.Info;
1241 OldStatus = Other.OldStatus;
1242 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1243 Other.Info = nullptr;
1244 }
1245
1246 void maybeRestoreState() {
1247 if (!Info)
1248 return;
1249
1250 Info->EvalStatus = OldStatus;
1251 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1252 }
1253
1254 public:
1255 SpeculativeEvaluationRAII() = default;
1256
1257 SpeculativeEvaluationRAII(
1258 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1259 : Info(&Info), OldStatus(Info.EvalStatus),
1260 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1261 Info.EvalStatus.Diag = NewDiag;
1262 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1263 }
1264
1265 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1266 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1267 moveFromAndCancel(std::move(Other));
1268 }
1269
1270 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1271 maybeRestoreState();
1272 moveFromAndCancel(std::move(Other));
1273 return *this;
1274 }
1275
1276 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1277 };
1278
1279 /// RAII object wrapping a full-expression or block scope, and handling
1280 /// the ending of the lifetime of temporaries created within it.
1281 template<bool IsFullExpression>
1282 class ScopeRAII {
1283 EvalInfo &Info;
1284 unsigned OldStackSize;
1285 public:
1286 ScopeRAII(EvalInfo &Info)
1287 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1288 // Push a new temporary version. This is needed to distinguish between
1289 // temporaries created in different iterations of a loop.
1290 Info.CurrentCall->pushTempVersion();
1291 }
1292 bool destroy(bool RunDestructors = true) {
1293 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1294 OldStackSize = -1U;
1295 return OK;
1296 }
1297 ~ScopeRAII() {
1298 if (OldStackSize != -1U)
1299 destroy(false);
1300 // Body moved to a static method to encourage the compiler to inline away
1301 // instances of this class.
1302 Info.CurrentCall->popTempVersion();
1303 }
1304 private:
1305 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1306 unsigned OldStackSize) {
1307 assert(OldStackSize <= Info.CleanupStack.size() &&((OldStackSize <= Info.CleanupStack.size() && "running cleanups out of order?"
) ? static_cast<void> (0) : __assert_fail ("OldStackSize <= Info.CleanupStack.size() && \"running cleanups out of order?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1308, __PRETTY_FUNCTION__))
1308 "running cleanups out of order?")((OldStackSize <= Info.CleanupStack.size() && "running cleanups out of order?"
) ? static_cast<void> (0) : __assert_fail ("OldStackSize <= Info.CleanupStack.size() && \"running cleanups out of order?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1308, __PRETTY_FUNCTION__))
;
1309
1310 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1311 // for a full-expression scope.
1312 bool Success = true;
1313 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1314 if (!(IsFullExpression &&
1315 Info.CleanupStack[I - 1].isLifetimeExtended())) {
1316 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1317 Success = false;
1318 break;
1319 }
1320 }
1321 }
1322
1323 // Compact lifetime-extended cleanups.
1324 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1325 if (IsFullExpression)
1326 NewEnd =
1327 std::remove_if(NewEnd, Info.CleanupStack.end(),
1328 [](Cleanup &C) { return !C.isLifetimeExtended(); });
1329 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1330 return Success;
1331 }
1332 };
1333 typedef ScopeRAII<false> BlockScopeRAII;
1334 typedef ScopeRAII<true> FullExpressionRAII;
1335}
1336
1337bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1338 CheckSubobjectKind CSK) {
1339 if (Invalid)
1340 return false;
1341 if (isOnePastTheEnd()) {
1342 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1343 << CSK;
1344 setInvalid();
1345 return false;
1346 }
1347 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1348 // must actually be at least one array element; even a VLA cannot have a
1349 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1350 return true;
1351}
1352
1353void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1354 const Expr *E) {
1355 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1356 // Do not set the designator as invalid: we can represent this situation,
1357 // and correct handling of __builtin_object_size requires us to do so.
1358}
1359
1360void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1361 const Expr *E,
1362 const APSInt &N) {
1363 // If we're complaining, we must be able to statically determine the size of
1364 // the most derived array.
1365 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1366 Info.CCEDiag(E, diag::note_constexpr_array_index)
1367 << N << /*array*/ 0
1368 << static_cast<unsigned>(getMostDerivedArraySize());
1369 else
1370 Info.CCEDiag(E, diag::note_constexpr_array_index)
1371 << N << /*non-array*/ 1;
1372 setInvalid();
1373}
1374
1375CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1376 const FunctionDecl *Callee, const LValue *This,
1377 APValue *Arguments)
1378 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1379 Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1380 Info.CurrentCall = this;
1381 ++Info.CallStackDepth;
1382}
1383
1384CallStackFrame::~CallStackFrame() {
1385 assert(Info.CurrentCall == this && "calls retired out of order")((Info.CurrentCall == this && "calls retired out of order"
) ? static_cast<void> (0) : __assert_fail ("Info.CurrentCall == this && \"calls retired out of order\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1385, __PRETTY_FUNCTION__))
;
1386 --Info.CallStackDepth;
1387 Info.CurrentCall = Caller;
1388}
1389
1390static bool isRead(AccessKinds AK) {
1391 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1392}
1393
1394static bool isModification(AccessKinds AK) {
1395 switch (AK) {
1396 case AK_Read:
1397 case AK_ReadObjectRepresentation:
1398 case AK_MemberCall:
1399 case AK_DynamicCast:
1400 case AK_TypeId:
1401 return false;
1402 case AK_Assign:
1403 case AK_Increment:
1404 case AK_Decrement:
1405 case AK_Construct:
1406 case AK_Destroy:
1407 return true;
1408 }
1409 llvm_unreachable("unknown access kind")::llvm::llvm_unreachable_internal("unknown access kind", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1409)
;
1410}
1411
1412static bool isAnyAccess(AccessKinds AK) {
1413 return isRead(AK) || isModification(AK);
1414}
1415
1416/// Is this an access per the C++ definition?
1417static bool isFormalAccess(AccessKinds AK) {
1418 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1419}
1420
1421namespace {
1422 struct ComplexValue {
1423 private:
1424 bool IsInt;
1425
1426 public:
1427 APSInt IntReal, IntImag;
1428 APFloat FloatReal, FloatImag;
1429
1430 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1431
1432 void makeComplexFloat() { IsInt = false; }
1433 bool isComplexFloat() const { return !IsInt; }
1434 APFloat &getComplexFloatReal() { return FloatReal; }
1435 APFloat &getComplexFloatImag() { return FloatImag; }
1436
1437 void makeComplexInt() { IsInt = true; }
1438 bool isComplexInt() const { return IsInt; }
1439 APSInt &getComplexIntReal() { return IntReal; }
1440 APSInt &getComplexIntImag() { return IntImag; }
1441
1442 void moveInto(APValue &v) const {
1443 if (isComplexFloat())
1444 v = APValue(FloatReal, FloatImag);
1445 else
1446 v = APValue(IntReal, IntImag);
1447 }
1448 void setFrom(const APValue &v) {
1449 assert(v.isComplexFloat() || v.isComplexInt())((v.isComplexFloat() || v.isComplexInt()) ? static_cast<void
> (0) : __assert_fail ("v.isComplexFloat() || v.isComplexInt()"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1449, __PRETTY_FUNCTION__))
;
1450 if (v.isComplexFloat()) {
1451 makeComplexFloat();
1452 FloatReal = v.getComplexFloatReal();
1453 FloatImag = v.getComplexFloatImag();
1454 } else {
1455 makeComplexInt();
1456 IntReal = v.getComplexIntReal();
1457 IntImag = v.getComplexIntImag();
1458 }
1459 }
1460 };
1461
1462 struct LValue {
1463 APValue::LValueBase Base;
1464 CharUnits Offset;
1465 SubobjectDesignator Designator;
1466 bool IsNullPtr : 1;
1467 bool InvalidBase : 1;
1468
1469 const APValue::LValueBase getLValueBase() const { return Base; }
1470 CharUnits &getLValueOffset() { return Offset; }
1471 const CharUnits &getLValueOffset() const { return Offset; }
1472 SubobjectDesignator &getLValueDesignator() { return Designator; }
1473 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1474 bool isNullPointer() const { return IsNullPtr;}
1475
1476 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1477 unsigned getLValueVersion() const { return Base.getVersion(); }
1478
1479 void moveInto(APValue &V) const {
1480 if (Designator.Invalid)
1481 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1482 else {
1483 assert(!InvalidBase && "APValues can't handle invalid LValue bases")((!InvalidBase && "APValues can't handle invalid LValue bases"
) ? static_cast<void> (0) : __assert_fail ("!InvalidBase && \"APValues can't handle invalid LValue bases\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1483, __PRETTY_FUNCTION__))
;
1484 V = APValue(Base, Offset, Designator.Entries,
1485 Designator.IsOnePastTheEnd, IsNullPtr);
1486 }
1487 }
1488 void setFrom(ASTContext &Ctx, const APValue &V) {
1489 assert(V.isLValue() && "Setting LValue from a non-LValue?")((V.isLValue() && "Setting LValue from a non-LValue?"
) ? static_cast<void> (0) : __assert_fail ("V.isLValue() && \"Setting LValue from a non-LValue?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1489, __PRETTY_FUNCTION__))
;
1490 Base = V.getLValueBase();
1491 Offset = V.getLValueOffset();
1492 InvalidBase = false;
1493 Designator = SubobjectDesignator(Ctx, V);
1494 IsNullPtr = V.isNullPointer();
1495 }
1496
1497 void set(APValue::LValueBase B, bool BInvalid = false) {
1498#ifndef NDEBUG
1499 // We only allow a few types of invalid bases. Enforce that here.
1500 if (BInvalid) {
1501 const auto *E = B.get<const Expr *>();
1502 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&(((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base") ? static_cast<void>
(0) : __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1503, __PRETTY_FUNCTION__))
1503 "Unexpected type of invalid base")(((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base") ? static_cast<void>
(0) : __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1503, __PRETTY_FUNCTION__))
;
1504 }
1505#endif
1506
1507 Base = B;
1508 Offset = CharUnits::fromQuantity(0);
1509 InvalidBase = BInvalid;
1510 Designator = SubobjectDesignator(getType(B));
1511 IsNullPtr = false;
1512 }
1513
1514 void setNull(ASTContext &Ctx, QualType PointerTy) {
1515 Base = (Expr *)nullptr;
1516 Offset =
1517 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
1518 InvalidBase = false;
1519 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1520 IsNullPtr = true;
1521 }
1522
1523 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1524 set(B, true);
1525 }
1526
1527 std::string toString(ASTContext &Ctx, QualType T) const {
1528 APValue Printable;
1529 moveInto(Printable);
1530 return Printable.getAsString(Ctx, T);
1531 }
1532
1533 private:
1534 // Check that this LValue is not based on a null pointer. If it is, produce
1535 // a diagnostic and mark the designator as invalid.
1536 template <typename GenDiagType>
1537 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1538 if (Designator.Invalid)
1539 return false;
1540 if (IsNullPtr) {
1541 GenDiag();
1542 Designator.setInvalid();
1543 return false;
1544 }
1545 return true;
1546 }
1547
1548 public:
1549 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1550 CheckSubobjectKind CSK) {
1551 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1552 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1553 });
1554 }
1555
1556 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1557 AccessKinds AK) {
1558 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1559 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1560 });
1561 }
1562
1563 // Check this LValue refers to an object. If not, set the designator to be
1564 // invalid and emit a diagnostic.
1565 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1566 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1567 Designator.checkSubobject(Info, E, CSK);
1568 }
1569
1570 void addDecl(EvalInfo &Info, const Expr *E,
1571 const Decl *D, bool Virtual = false) {
1572 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1573 Designator.addDeclUnchecked(D, Virtual);
1574 }
1575 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1576 if (!Designator.Entries.empty()) {
1577 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1578 Designator.setInvalid();
1579 return;
1580 }
1581 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1582 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType())((getType(Base)->isPointerType() || getType(Base)->isArrayType
()) ? static_cast<void> (0) : __assert_fail ("getType(Base)->isPointerType() || getType(Base)->isArrayType()"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1582, __PRETTY_FUNCTION__))
;
1583 Designator.FirstEntryIsAnUnsizedArray = true;
1584 Designator.addUnsizedArrayUnchecked(ElemTy);
1585 }
1586 }
1587 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1588 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1589 Designator.addArrayUnchecked(CAT);
1590 }
1591 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1592 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1593 Designator.addComplexUnchecked(EltTy, Imag);
1594 }
1595 void clearIsNullPointer() {
1596 IsNullPtr = false;
1597 }
1598 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1599 const APSInt &Index, CharUnits ElementSize) {
1600 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1601 // but we're not required to diagnose it and it's valid in C++.)
1602 if (!Index)
1603 return;
1604
1605 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1606 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1607 // offsets.
1608 uint64_t Offset64 = Offset.getQuantity();
1609 uint64_t ElemSize64 = ElementSize.getQuantity();
1610 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1611 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1612
1613 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1614 Designator.adjustIndex(Info, E, Index);
1615 clearIsNullPointer();
1616 }
1617 void adjustOffset(CharUnits N) {
1618 Offset += N;
1619 if (N.getQuantity())
1620 clearIsNullPointer();
1621 }
1622 };
1623
1624 struct MemberPtr {
1625 MemberPtr() {}
1626 explicit MemberPtr(const ValueDecl *Decl) :
1627 DeclAndIsDerivedMember(Decl, false), Path() {}
1628
1629 /// The member or (direct or indirect) field referred to by this member
1630 /// pointer, or 0 if this is a null member pointer.
1631 const ValueDecl *getDecl() const {
1632 return DeclAndIsDerivedMember.getPointer();
1633 }
1634 /// Is this actually a member of some type derived from the relevant class?
1635 bool isDerivedMember() const {
1636 return DeclAndIsDerivedMember.getInt();
1637 }
1638 /// Get the class which the declaration actually lives in.
1639 const CXXRecordDecl *getContainingRecord() const {
1640 return cast<CXXRecordDecl>(
1641 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1642 }
1643
1644 void moveInto(APValue &V) const {
1645 V = APValue(getDecl(), isDerivedMember(), Path);
1646 }
1647 void setFrom(const APValue &V) {
1648 assert(V.isMemberPointer())((V.isMemberPointer()) ? static_cast<void> (0) : __assert_fail
("V.isMemberPointer()", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1648, __PRETTY_FUNCTION__))
;
1649 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1650 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1651 Path.clear();
1652 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1653 Path.insert(Path.end(), P.begin(), P.end());
1654 }
1655
1656 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1657 /// whether the member is a member of some class derived from the class type
1658 /// of the member pointer.
1659 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1660 /// Path - The path of base/derived classes from the member declaration's
1661 /// class (exclusive) to the class type of the member pointer (inclusive).
1662 SmallVector<const CXXRecordDecl*, 4> Path;
1663
1664 /// Perform a cast towards the class of the Decl (either up or down the
1665 /// hierarchy).
1666 bool castBack(const CXXRecordDecl *Class) {
1667 assert(!Path.empty())((!Path.empty()) ? static_cast<void> (0) : __assert_fail
("!Path.empty()", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1667, __PRETTY_FUNCTION__))
;
1668 const CXXRecordDecl *Expected;
1669 if (Path.size() >= 2)
1670 Expected = Path[Path.size() - 2];
1671 else
1672 Expected = getContainingRecord();
1673 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1674 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1675 // if B does not contain the original member and is not a base or
1676 // derived class of the class containing the original member, the result
1677 // of the cast is undefined.
1678 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1679 // (D::*). We consider that to be a language defect.
1680 return false;
1681 }
1682 Path.pop_back();
1683 return true;
1684 }
1685 /// Perform a base-to-derived member pointer cast.
1686 bool castToDerived(const CXXRecordDecl *Derived) {
1687 if (!getDecl())
1688 return true;
1689 if (!isDerivedMember()) {
1690 Path.push_back(Derived);
1691 return true;
1692 }
1693 if (!castBack(Derived))
1694 return false;
1695 if (Path.empty())
1696 DeclAndIsDerivedMember.setInt(false);
1697 return true;
1698 }
1699 /// Perform a derived-to-base member pointer cast.
1700 bool castToBase(const CXXRecordDecl *Base) {
1701 if (!getDecl())
1702 return true;
1703 if (Path.empty())
1704 DeclAndIsDerivedMember.setInt(true);
1705 if (isDerivedMember()) {
1706 Path.push_back(Base);
1707 return true;
1708 }
1709 return castBack(Base);
1710 }
1711 };
1712
1713 /// Compare two member pointers, which are assumed to be of the same type.
1714 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1715 if (!LHS.getDecl() || !RHS.getDecl())
1716 return !LHS.getDecl() && !RHS.getDecl();
1717 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1718 return false;
1719 return LHS.Path == RHS.Path;
1720 }
1721}
1722
1723static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1724static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1725 const LValue &This, const Expr *E,
1726 bool AllowNonLiteralTypes = false);
1727static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1728 bool InvalidBaseOK = false);
1729static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1730 bool InvalidBaseOK = false);
1731static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1732 EvalInfo &Info);
1733static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1734static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1735static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1736 EvalInfo &Info);
1737static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1738static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1739static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1740 EvalInfo &Info);
1741static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1742
1743/// Evaluate an integer or fixed point expression into an APResult.
1744static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1745 EvalInfo &Info);
1746
1747/// Evaluate only a fixed point expression into an APResult.
1748static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1749 EvalInfo &Info);
1750
1751//===----------------------------------------------------------------------===//
1752// Misc utilities
1753//===----------------------------------------------------------------------===//
1754
1755/// Negate an APSInt in place, converting it to a signed form if necessary, and
1756/// preserving its value (by extending by up to one bit as needed).
1757static void negateAsSigned(APSInt &Int) {
1758 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1759 Int = Int.extend(Int.getBitWidth() + 1);
1760 Int.setIsSigned(true);
1761 }
1762 Int = -Int;
1763}
1764
1765template<typename KeyT>
1766APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1767 bool IsLifetimeExtended, LValue &LV) {
1768 unsigned Version = getTempVersion();
1769 APValue::LValueBase Base(Key, Index, Version);
1770 LV.set(Base);
1771 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1772 assert(Result.isAbsent() && "temporary created multiple times")((Result.isAbsent() && "temporary created multiple times"
) ? static_cast<void> (0) : __assert_fail ("Result.isAbsent() && \"temporary created multiple times\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1772, __PRETTY_FUNCTION__))
;
1773
1774 // If we're creating a temporary immediately in the operand of a speculative
1775 // evaluation, don't register a cleanup to be run outside the speculative
1776 // evaluation context, since we won't actually be able to initialize this
1777 // object.
1778 if (Index <= Info.SpeculativeEvaluationDepth) {
1779 if (T.isDestructedType())
1780 Info.noteSideEffect();
1781 } else {
1782 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, IsLifetimeExtended));
1783 }
1784 return Result;
1785}
1786
1787APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1788 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1789 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1790 return nullptr;
1791 }
1792
1793 DynamicAllocLValue DA(NumHeapAllocs++);
1794 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1795 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1796 std::forward_as_tuple(DA), std::tuple<>());
1797 assert(Result.second && "reused a heap alloc index?")((Result.second && "reused a heap alloc index?") ? static_cast
<void> (0) : __assert_fail ("Result.second && \"reused a heap alloc index?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1797, __PRETTY_FUNCTION__))
;
1798 Result.first->second.AllocExpr = E;
1799 return &Result.first->second.Value;
1800}
1801
1802/// Produce a string describing the given constexpr call.
1803void CallStackFrame::describe(raw_ostream &Out) {
1804 unsigned ArgIndex = 0;
1805 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1806 !isa<CXXConstructorDecl>(Callee) &&
1807 cast<CXXMethodDecl>(Callee)->isInstance();
1808
1809 if (!IsMemberCall)
1810 Out << *Callee << '(';
1811
1812 if (This && IsMemberCall) {
1813 APValue Val;
1814 This->moveInto(Val);
1815 Val.printPretty(Out, Info.Ctx,
1816 This->Designator.MostDerivedType);
1817 // FIXME: Add parens around Val if needed.
1818 Out << "->" << *Callee << '(';
1819 IsMemberCall = false;
1820 }
1821
1822 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1823 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1824 if (ArgIndex > (unsigned)IsMemberCall)
1825 Out << ", ";
1826
1827 const ParmVarDecl *Param = *I;
1828 const APValue &Arg = Arguments[ArgIndex];
1829 Arg.printPretty(Out, Info.Ctx, Param->getType());
1830
1831 if (ArgIndex == 0 && IsMemberCall)
1832 Out << "->" << *Callee << '(';
1833 }
1834
1835 Out << ')';
1836}
1837
1838/// Evaluate an expression to see if it had side-effects, and discard its
1839/// result.
1840/// \return \c true if the caller should keep evaluating.
1841static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1842 APValue Scratch;
1843 if (!Evaluate(Scratch, Info, E))
1844 // We don't need the value, but we might have skipped a side effect here.
1845 return Info.noteSideEffect();
1846 return true;
1847}
1848
1849/// Should this call expression be treated as a string literal?
1850static bool IsStringLiteralCall(const CallExpr *E) {
1851 unsigned Builtin = E->getBuiltinCallee();
1852 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1853 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1854}
1855
1856static bool IsGlobalLValue(APValue::LValueBase B) {
1857 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1858 // constant expression of pointer type that evaluates to...
1859
1860 // ... a null pointer value, or a prvalue core constant expression of type
1861 // std::nullptr_t.
1862 if (!B) return true;
1863
1864 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1865 // ... the address of an object with static storage duration,
1866 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1867 return VD->hasGlobalStorage();
1868 // ... the address of a function,
1869 return isa<FunctionDecl>(D);
1870 }
1871
1872 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1873 return true;
1874
1875 const Expr *E = B.get<const Expr*>();
1876 switch (E->getStmtClass()) {
1877 default:
1878 return false;
1879 case Expr::CompoundLiteralExprClass: {
1880 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1881 return CLE->isFileScope() && CLE->isLValue();
1882 }
1883 case Expr::MaterializeTemporaryExprClass:
1884 // A materialized temporary might have been lifetime-extended to static
1885 // storage duration.
1886 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
1887 // A string literal has static storage duration.
1888 case Expr::StringLiteralClass:
1889 case Expr::PredefinedExprClass:
1890 case Expr::ObjCStringLiteralClass:
1891 case Expr::ObjCEncodeExprClass:
1892 case Expr::CXXUuidofExprClass:
1893 return true;
1894 case Expr::ObjCBoxedExprClass:
1895 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
1896 case Expr::CallExprClass:
1897 return IsStringLiteralCall(cast<CallExpr>(E));
1898 // For GCC compatibility, &&label has static storage duration.
1899 case Expr::AddrLabelExprClass:
1900 return true;
1901 // A Block literal expression may be used as the initialization value for
1902 // Block variables at global or local static scope.
1903 case Expr::BlockExprClass:
1904 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
1905 case Expr::ImplicitValueInitExprClass:
1906 // FIXME:
1907 // We can never form an lvalue with an implicit value initialization as its
1908 // base through expression evaluation, so these only appear in one case: the
1909 // implicit variable declaration we invent when checking whether a constexpr
1910 // constructor can produce a constant expression. We must assume that such
1911 // an expression might be a global lvalue.
1912 return true;
1913 }
1914}
1915
1916static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
1917 return LVal.Base.dyn_cast<const ValueDecl*>();
1918}
1919
1920static bool IsLiteralLValue(const LValue &Value) {
1921 if (Value.getLValueCallIndex())
1922 return false;
1923 const Expr *E = Value.Base.dyn_cast<const Expr*>();
1924 return E && !isa<MaterializeTemporaryExpr>(E);
1925}
1926
1927static bool IsWeakLValue(const LValue &Value) {
1928 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1929 return Decl && Decl->isWeak();
1930}
1931
1932static bool isZeroSized(const LValue &Value) {
1933 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1934 if (Decl && isa<VarDecl>(Decl)) {
1935 QualType Ty = Decl->getType();
1936 if (Ty->isArrayType())
1937 return Ty->isIncompleteType() ||
1938 Decl->getASTContext().getTypeSize(Ty) == 0;
1939 }
1940 return false;
1941}
1942
1943static bool HasSameBase(const LValue &A, const LValue &B) {
1944 if (!A.getLValueBase())
1945 return !B.getLValueBase();
1946 if (!B.getLValueBase())
1947 return false;
1948
1949 if (A.getLValueBase().getOpaqueValue() !=
1950 B.getLValueBase().getOpaqueValue()) {
1951 const Decl *ADecl = GetLValueBaseDecl(A);
1952 if (!ADecl)
1953 return false;
1954 const Decl *BDecl = GetLValueBaseDecl(B);
1955 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
1956 return false;
1957 }
1958
1959 return IsGlobalLValue(A.getLValueBase()) ||
1960 (A.getLValueCallIndex() == B.getLValueCallIndex() &&
1961 A.getLValueVersion() == B.getLValueVersion());
1962}
1963
1964static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
1965 assert(Base && "no location for a null lvalue")((Base && "no location for a null lvalue") ? static_cast
<void> (0) : __assert_fail ("Base && \"no location for a null lvalue\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 1965, __PRETTY_FUNCTION__))
;
1966 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1967 if (VD)
1968 Info.Note(VD->getLocation(), diag::note_declared_at);
1969 else if (const Expr *E = Base.dyn_cast<const Expr*>())
1970 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
1971 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
1972 // FIXME: Produce a note for dangling pointers too.
1973 if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
1974 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
1975 diag::note_constexpr_dynamic_alloc_here);
1976 }
1977 // We have no information to show for a typeid(T) object.
1978}
1979
1980enum class CheckEvaluationResultKind {
1981 ConstantExpression,
1982 FullyInitialized,
1983};
1984
1985/// Materialized temporaries that we've already checked to determine if they're
1986/// initializsed by a constant expression.
1987using CheckedTemporaries =
1988 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
1989
1990static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
1991 EvalInfo &Info, SourceLocation DiagLoc,
1992 QualType Type, const APValue &Value,
1993 Expr::ConstExprUsage Usage,
1994 SourceLocation SubobjectLoc,
1995 CheckedTemporaries &CheckedTemps);
1996
1997/// Check that this reference or pointer core constant expression is a valid
1998/// value for an address or reference constant expression. Return true if we
1999/// can fold this expression, whether or not it's a constant expression.
2000static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2001 QualType Type, const LValue &LVal,
2002 Expr::ConstExprUsage Usage,
2003 CheckedTemporaries &CheckedTemps) {
2004 bool IsReferenceType = Type->isReferenceType();
2005
2006 APValue::LValueBase Base = LVal.getLValueBase();
2007 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2008
2009 // Check that the object is a global. Note that the fake 'this' object we
2010 // manufacture when checking potential constant expressions is conservatively
2011 // assumed to be global here.
2012 if (!IsGlobalLValue(Base)) {
2013 if (Info.getLangOpts().CPlusPlus11) {
2014 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2015 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2016 << IsReferenceType << !Designator.Entries.empty()
2017 << !!VD << VD;
2018 NoteLValueLocation(Info, Base);
2019 } else {
2020 Info.FFDiag(Loc);
2021 }
2022 // Don't allow references to temporaries to escape.
2023 return false;
2024 }
2025 assert((Info.checkingPotentialConstantExpression() ||(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2027, __PRETTY_FUNCTION__))
2026 LVal.getLValueCallIndex() == 0) &&(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2027, __PRETTY_FUNCTION__))
2027 "have call index for global lvalue")(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2027, __PRETTY_FUNCTION__))
;
2028
2029 if (Base.is<DynamicAllocLValue>()) {
2030 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2031 << IsReferenceType << !Designator.Entries.empty();
2032 NoteLValueLocation(Info, Base);
2033 return false;
2034 }
2035
2036 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
2037 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) {
2038 // Check if this is a thread-local variable.
2039 if (Var->getTLSKind())
2040 // FIXME: Diagnostic!
2041 return false;
2042
2043 // A dllimport variable never acts like a constant.
2044 if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr<DLLImportAttr>())
2045 // FIXME: Diagnostic!
2046 return false;
2047 }
2048 if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) {
2049 // __declspec(dllimport) must be handled very carefully:
2050 // We must never initialize an expression with the thunk in C++.
2051 // Doing otherwise would allow the same id-expression to yield
2052 // different addresses for the same function in different translation
2053 // units. However, this means that we must dynamically initialize the
2054 // expression with the contents of the import address table at runtime.
2055 //
2056 // The C language has no notion of ODR; furthermore, it has no notion of
2057 // dynamic initialization. This means that we are permitted to
2058 // perform initialization with the address of the thunk.
2059 if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen &&
2060 FD->hasAttr<DLLImportAttr>())
2061 // FIXME: Diagnostic!
2062 return false;
2063 }
2064 } else if (const auto *MTE = dyn_cast_or_null<MaterializeTemporaryExpr>(
2065 Base.dyn_cast<const Expr *>())) {
2066 if (CheckedTemps.insert(MTE).second) {
2067 QualType TempType = getType(Base);
2068 if (TempType.isDestructedType()) {
2069 Info.FFDiag(MTE->getExprLoc(),
2070 diag::note_constexpr_unsupported_tempoarary_nontrivial_dtor)
2071 << TempType;
2072 return false;
2073 }
2074
2075 APValue *V = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
2076 assert(V && "evasluation result refers to uninitialised temporary")((V && "evasluation result refers to uninitialised temporary"
) ? static_cast<void> (0) : __assert_fail ("V && \"evasluation result refers to uninitialised temporary\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2076, __PRETTY_FUNCTION__))
;
2077 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2078 Info, MTE->getExprLoc(), TempType, *V,
2079 Usage, SourceLocation(), CheckedTemps))
2080 return false;
2081 }
2082 }
2083
2084 // Allow address constant expressions to be past-the-end pointers. This is
2085 // an extension: the standard requires them to point to an object.
2086 if (!IsReferenceType)
2087 return true;
2088
2089 // A reference constant expression must refer to an object.
2090 if (!Base) {
2091 // FIXME: diagnostic
2092 Info.CCEDiag(Loc);
2093 return true;
2094 }
2095
2096 // Does this refer one past the end of some object?
2097 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2098 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2099 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2100 << !Designator.Entries.empty() << !!VD << VD;
2101 NoteLValueLocation(Info, Base);
2102 }
2103
2104 return true;
2105}
2106
2107/// Member pointers are constant expressions unless they point to a
2108/// non-virtual dllimport member function.
2109static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2110 SourceLocation Loc,
2111 QualType Type,
2112 const APValue &Value,
2113 Expr::ConstExprUsage Usage) {
2114 const ValueDecl *Member = Value.getMemberPointerDecl();
2115 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2116 if (!FD)
2117 return true;
2118 return Usage == Expr::EvaluateForMangling || FD->isVirtual() ||
2119 !FD->hasAttr<DLLImportAttr>();
2120}
2121
2122/// Check that this core constant expression is of literal type, and if not,
2123/// produce an appropriate diagnostic.
2124static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2125 const LValue *This = nullptr) {
2126 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
2127 return true;
2128
2129 // C++1y: A constant initializer for an object o [...] may also invoke
2130 // constexpr constructors for o and its subobjects even if those objects
2131 // are of non-literal class types.
2132 //
2133 // C++11 missed this detail for aggregates, so classes like this:
2134 // struct foo_t { union { int i; volatile int j; } u; };
2135 // are not (obviously) initializable like so:
2136 // __attribute__((__require_constant_initialization__))
2137 // static const foo_t x = {{0}};
2138 // because "i" is a subobject with non-literal initialization (due to the
2139 // volatile member of the union). See:
2140 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2141 // Therefore, we use the C++1y behavior.
2142 if (This && Info.EvaluatingDecl == This->getLValueBase())
2143 return true;
2144
2145 // Prvalue constant expressions must be of literal types.
2146 if (Info.getLangOpts().CPlusPlus11)
2147 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2148 << E->getType();
2149 else
2150 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2151 return false;
2152}
2153
2154static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2155 EvalInfo &Info, SourceLocation DiagLoc,
2156 QualType Type, const APValue &Value,
2157 Expr::ConstExprUsage Usage,
2158 SourceLocation SubobjectLoc,
2159 CheckedTemporaries &CheckedTemps) {
2160 if (!Value.hasValue()) {
2161 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2162 << true << Type;
2163 if (SubobjectLoc.isValid())
2164 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
2165 return false;
2166 }
2167
2168 // We allow _Atomic(T) to be initialized from anything that T can be
2169 // initialized from.
2170 if (const AtomicType *AT = Type->getAs<AtomicType>())
2171 Type = AT->getValueType();
2172
2173 // Core issue 1454: For a literal constant expression of array or class type,
2174 // each subobject of its value shall have been initialized by a constant
2175 // expression.
2176 if (Value.isArray()) {
2177 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2178 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2179 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2180 Value.getArrayInitializedElt(I), Usage,
2181 SubobjectLoc, CheckedTemps))
2182 return false;
2183 }
2184 if (!Value.hasArrayFiller())
2185 return true;
2186 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2187 Value.getArrayFiller(), Usage, SubobjectLoc,
2188 CheckedTemps);
2189 }
2190 if (Value.isUnion() && Value.getUnionField()) {
2191 return CheckEvaluationResult(
2192 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2193 Value.getUnionValue(), Usage, Value.getUnionField()->getLocation(),
2194 CheckedTemps);
2195 }
2196 if (Value.isStruct()) {
2197 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2198 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2199 unsigned BaseIndex = 0;
2200 for (const CXXBaseSpecifier &BS : CD->bases()) {
2201 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2202 Value.getStructBase(BaseIndex), Usage,
2203 BS.getBeginLoc(), CheckedTemps))
2204 return false;
2205 ++BaseIndex;
2206 }
2207 }
2208 for (const auto *I : RD->fields()) {
2209 if (I->isUnnamedBitfield())
2210 continue;
2211
2212 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2213 Value.getStructField(I->getFieldIndex()),
2214 Usage, I->getLocation(), CheckedTemps))
2215 return false;
2216 }
2217 }
2218
2219 if (Value.isLValue() &&
2220 CERK == CheckEvaluationResultKind::ConstantExpression) {
2221 LValue LVal;
2222 LVal.setFrom(Info.Ctx, Value);
2223 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage,
2224 CheckedTemps);
2225 }
2226
2227 if (Value.isMemberPointer() &&
2228 CERK == CheckEvaluationResultKind::ConstantExpression)
2229 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage);
2230
2231 // Everything else is fine.
2232 return true;
2233}
2234
2235/// Check that this core constant expression value is a valid value for a
2236/// constant expression. If not, report an appropriate diagnostic. Does not
2237/// check that the expression is of literal type.
2238static bool
2239CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type,
2240 const APValue &Value,
2241 Expr::ConstExprUsage Usage = Expr::EvaluateForCodeGen) {
2242 CheckedTemporaries CheckedTemps;
2243 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2244 Info, DiagLoc, Type, Value, Usage,
2245 SourceLocation(), CheckedTemps);
2246}
2247
2248/// Check that this evaluated value is fully-initialized and can be loaded by
2249/// an lvalue-to-rvalue conversion.
2250static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2251 QualType Type, const APValue &Value) {
2252 CheckedTemporaries CheckedTemps;
2253 return CheckEvaluationResult(
2254 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2255 Expr::EvaluateForCodeGen, SourceLocation(), CheckedTemps);
2256}
2257
2258/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2259/// "the allocated storage is deallocated within the evaluation".
2260static bool CheckMemoryLeaks(EvalInfo &Info) {
2261 if (!Info.HeapAllocs.empty()) {
2262 // We can still fold to a constant despite a compile-time memory leak,
2263 // so long as the heap allocation isn't referenced in the result (we check
2264 // that in CheckConstantExpression).
2265 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2266 diag::note_constexpr_memory_leak)
2267 << unsigned(Info.HeapAllocs.size() - 1);
2268 }
2269 return true;
2270}
2271
2272static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2273 // A null base expression indicates a null pointer. These are always
2274 // evaluatable, and they are false unless the offset is zero.
2275 if (!Value.getLValueBase()) {
2276 Result = !Value.getLValueOffset().isZero();
2277 return true;
2278 }
2279
2280 // We have a non-null base. These are generally known to be true, but if it's
2281 // a weak declaration it can be null at runtime.
2282 Result = true;
2283 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2284 return !Decl || !Decl->isWeak();
2285}
2286
2287static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2288 switch (Val.getKind()) {
2289 case APValue::None:
2290 case APValue::Indeterminate:
2291 return false;
2292 case APValue::Int:
2293 Result = Val.getInt().getBoolValue();
2294 return true;
2295 case APValue::FixedPoint:
2296 Result = Val.getFixedPoint().getBoolValue();
2297 return true;
2298 case APValue::Float:
2299 Result = !Val.getFloat().isZero();
2300 return true;
2301 case APValue::ComplexInt:
2302 Result = Val.getComplexIntReal().getBoolValue() ||
2303 Val.getComplexIntImag().getBoolValue();
2304 return true;
2305 case APValue::ComplexFloat:
2306 Result = !Val.getComplexFloatReal().isZero() ||
2307 !Val.getComplexFloatImag().isZero();
2308 return true;
2309 case APValue::LValue:
2310 return EvalPointerValueAsBool(Val, Result);
2311 case APValue::MemberPointer:
2312 Result = Val.getMemberPointerDecl();
2313 return true;
2314 case APValue::Vector:
2315 case APValue::Array:
2316 case APValue::Struct:
2317 case APValue::Union:
2318 case APValue::AddrLabelDiff:
2319 return false;
2320 }
2321
2322 llvm_unreachable("unknown APValue kind")::llvm::llvm_unreachable_internal("unknown APValue kind", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2322)
;
2323}
2324
2325static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2326 EvalInfo &Info) {
2327 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition")((E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"
) ? static_cast<void> (0) : __assert_fail ("E->isRValue() && \"missing lvalue-to-rvalue conv in bool condition\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2327, __PRETTY_FUNCTION__))
;
2328 APValue Val;
2329 if (!Evaluate(Val, Info, E))
2330 return false;
2331 return HandleConversionToBool(Val, Result);
2332}
2333
2334template<typename T>
2335static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2336 const T &SrcValue, QualType DestType) {
2337 Info.CCEDiag(E, diag::note_constexpr_overflow)
2338 << SrcValue << DestType;
2339 return Info.noteUndefinedBehavior();
2340}
2341
2342static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2343 QualType SrcType, const APFloat &Value,
2344 QualType DestType, APSInt &Result) {
2345 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2346 // Determine whether we are converting to unsigned or signed.
2347 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2348
2349 Result = APSInt(DestWidth, !DestSigned);
2350 bool ignored;
2351 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2352 & APFloat::opInvalidOp)
2353 return HandleOverflow(Info, E, Value, DestType);
2354 return true;
2355}
2356
2357static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2358 QualType SrcType, QualType DestType,
2359 APFloat &Result) {
2360 APFloat Value = Result;
2361 bool ignored;
2362 Result.convert(Info.Ctx.getFloatTypeSemantics(DestType),
2363 APFloat::rmNearestTiesToEven, &ignored);
2364 return true;
2365}
2366
2367static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2368 QualType DestType, QualType SrcType,
2369 const APSInt &Value) {
2370 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2371 // Figure out if this is a truncate, extend or noop cast.
2372 // If the input is signed, do a sign extend, noop, or truncate.
2373 APSInt Result = Value.extOrTrunc(DestWidth);
2374 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2375 if (DestType->isBooleanType())
2376 Result = Value.getBoolValue();
2377 return Result;
2378}
2379
2380static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2381 QualType SrcType, const APSInt &Value,
2382 QualType DestType, APFloat &Result) {
2383 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2384 Result.convertFromAPInt(Value, Value.isSigned(),
2385 APFloat::rmNearestTiesToEven);
2386 return true;
2387}
2388
2389static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2390 APValue &Value, const FieldDecl *FD) {
2391 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield")((FD->isBitField() && "truncateBitfieldValue on non-bitfield"
) ? static_cast<void> (0) : __assert_fail ("FD->isBitField() && \"truncateBitfieldValue on non-bitfield\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2391, __PRETTY_FUNCTION__))
;
2392
2393 if (!Value.isInt()) {
2394 // Trying to store a pointer-cast-to-integer into a bitfield.
2395 // FIXME: In this case, we should provide the diagnostic for casting
2396 // a pointer to an integer.
2397 assert(Value.isLValue() && "integral value neither int nor lvalue?")((Value.isLValue() && "integral value neither int nor lvalue?"
) ? static_cast<void> (0) : __assert_fail ("Value.isLValue() && \"integral value neither int nor lvalue?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2397, __PRETTY_FUNCTION__))
;
2398 Info.FFDiag(E);
2399 return false;
2400 }
2401
2402 APSInt &Int = Value.getInt();
2403 unsigned OldBitWidth = Int.getBitWidth();
2404 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2405 if (NewBitWidth < OldBitWidth)
2406 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2407 return true;
2408}
2409
2410static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2411 llvm::APInt &Res) {
2412 APValue SVal;
2413 if (!Evaluate(SVal, Info, E))
2414 return false;
2415 if (SVal.isInt()) {
2416 Res = SVal.getInt();
2417 return true;
2418 }
2419 if (SVal.isFloat()) {
2420 Res = SVal.getFloat().bitcastToAPInt();
2421 return true;
2422 }
2423 if (SVal.isVector()) {
2424 QualType VecTy = E->getType();
2425 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2426 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2427 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2428 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2429 Res = llvm::APInt::getNullValue(VecSize);
2430 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2431 APValue &Elt = SVal.getVectorElt(i);
2432 llvm::APInt EltAsInt;
2433 if (Elt.isInt()) {
2434 EltAsInt = Elt.getInt();
2435 } else if (Elt.isFloat()) {
2436 EltAsInt = Elt.getFloat().bitcastToAPInt();
2437 } else {
2438 // Don't try to handle vectors of anything other than int or float
2439 // (not sure if it's possible to hit this case).
2440 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2441 return false;
2442 }
2443 unsigned BaseEltSize = EltAsInt.getBitWidth();
2444 if (BigEndian)
2445 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2446 else
2447 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2448 }
2449 return true;
2450 }
2451 // Give up if the input isn't an int, float, or vector. For example, we
2452 // reject "(v4i16)(intptr_t)&a".
2453 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2454 return false;
2455}
2456
2457/// Perform the given integer operation, which is known to need at most BitWidth
2458/// bits, and check for overflow in the original type (if that type was not an
2459/// unsigned type).
2460template<typename Operation>
2461static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2462 const APSInt &LHS, const APSInt &RHS,
2463 unsigned BitWidth, Operation Op,
2464 APSInt &Result) {
2465 if (LHS.isUnsigned()) {
2466 Result = Op(LHS, RHS);
2467 return true;
2468 }
2469
2470 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2471 Result = Value.trunc(LHS.getBitWidth());
2472 if (Result.extend(BitWidth) != Value) {
2473 if (Info.checkingForUndefinedBehavior())
2474 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2475 diag::warn_integer_constant_overflow)
2476 << Result.toString(10) << E->getType();
2477 else
2478 return HandleOverflow(Info, E, Value, E->getType());
2479 }
2480 return true;
2481}
2482
2483/// Perform the given binary integer operation.
2484static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2485 BinaryOperatorKind Opcode, APSInt RHS,
2486 APSInt &Result) {
2487 switch (Opcode) {
2488 default:
2489 Info.FFDiag(E);
2490 return false;
2491 case BO_Mul:
2492 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2493 std::multiplies<APSInt>(), Result);
2494 case BO_Add:
2495 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2496 std::plus<APSInt>(), Result);
2497 case BO_Sub:
2498 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2499 std::minus<APSInt>(), Result);
2500 case BO_And: Result = LHS & RHS; return true;
2501 case BO_Xor: Result = LHS ^ RHS; return true;
2502 case BO_Or: Result = LHS | RHS; return true;
2503 case BO_Div:
2504 case BO_Rem:
2505 if (RHS == 0) {
2506 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2507 return false;
2508 }
2509 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2510 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2511 // this operation and gives the two's complement result.
2512 if (RHS.isNegative() && RHS.isAllOnesValue() &&
2513 LHS.isSigned() && LHS.isMinSignedValue())
2514 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2515 E->getType());
2516 return true;
2517 case BO_Shl: {
2518 if (Info.getLangOpts().OpenCL)
2519 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2520 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2521 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2522 RHS.isUnsigned());
2523 else if (RHS.isSigned() && RHS.isNegative()) {
2524 // During constant-folding, a negative shift is an opposite shift. Such
2525 // a shift is not a constant expression.
2526 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2527 RHS = -RHS;
2528 goto shift_right;
2529 }
2530 shift_left:
2531 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2532 // the shifted type.
2533 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2534 if (SA != RHS) {
2535 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2536 << RHS << E->getType() << LHS.getBitWidth();
2537 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus2a) {
2538 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2539 // operand, and must not overflow the corresponding unsigned type.
2540 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2541 // E1 x 2^E2 module 2^N.
2542 if (LHS.isNegative())
2543 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2544 else if (LHS.countLeadingZeros() < SA)
2545 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2546 }
2547 Result = LHS << SA;
2548 return true;
2549 }
2550 case BO_Shr: {
2551 if (Info.getLangOpts().OpenCL)
2552 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2553 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2554 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2555 RHS.isUnsigned());
2556 else if (RHS.isSigned() && RHS.isNegative()) {
2557 // During constant-folding, a negative shift is an opposite shift. Such a
2558 // shift is not a constant expression.
2559 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2560 RHS = -RHS;
2561 goto shift_left;
2562 }
2563 shift_right:
2564 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2565 // shifted type.
2566 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2567 if (SA != RHS)
2568 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2569 << RHS << E->getType() << LHS.getBitWidth();
2570 Result = LHS >> SA;
2571 return true;
2572 }
2573
2574 case BO_LT: Result = LHS < RHS; return true;
2575 case BO_GT: Result = LHS > RHS; return true;
2576 case BO_LE: Result = LHS <= RHS; return true;
2577 case BO_GE: Result = LHS >= RHS; return true;
2578 case BO_EQ: Result = LHS == RHS; return true;
2579 case BO_NE: Result = LHS != RHS; return true;
2580 case BO_Cmp:
2581 llvm_unreachable("BO_Cmp should be handled elsewhere")::llvm::llvm_unreachable_internal("BO_Cmp should be handled elsewhere"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2581)
;
2582 }
2583}
2584
2585/// Perform the given binary floating-point operation, in-place, on LHS.
2586static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E,
2587 APFloat &LHS, BinaryOperatorKind Opcode,
2588 const APFloat &RHS) {
2589 switch (Opcode) {
2590 default:
2591 Info.FFDiag(E);
2592 return false;
2593 case BO_Mul:
2594 LHS.multiply(RHS, APFloat::rmNearestTiesToEven);
2595 break;
2596 case BO_Add:
2597 LHS.add(RHS, APFloat::rmNearestTiesToEven);
2598 break;
2599 case BO_Sub:
2600 LHS.subtract(RHS, APFloat::rmNearestTiesToEven);
2601 break;
2602 case BO_Div:
2603 // [expr.mul]p4:
2604 // If the second operand of / or % is zero the behavior is undefined.
2605 if (RHS.isZero())
2606 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2607 LHS.divide(RHS, APFloat::rmNearestTiesToEven);
2608 break;
2609 }
2610
2611 // [expr.pre]p4:
2612 // If during the evaluation of an expression, the result is not
2613 // mathematically defined [...], the behavior is undefined.
2614 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2615 if (LHS.isNaN()) {
2616 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2617 return Info.noteUndefinedBehavior();
2618 }
2619 return true;
2620}
2621
2622/// Cast an lvalue referring to a base subobject to a derived class, by
2623/// truncating the lvalue's path to the given length.
2624static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
2625 const RecordDecl *TruncatedType,
2626 unsigned TruncatedElements) {
2627 SubobjectDesignator &D = Result.Designator;
2628
2629 // Check we actually point to a derived class object.
2630 if (TruncatedElements == D.Entries.size())
2631 return true;
2632 assert(TruncatedElements >= D.MostDerivedPathLength &&((TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"
) ? static_cast<void> (0) : __assert_fail ("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2633, __PRETTY_FUNCTION__))
2633 "not casting to a derived class")((TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"
) ? static_cast<void> (0) : __assert_fail ("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2633, __PRETTY_FUNCTION__))
;
2634 if (!Result.checkSubobject(Info, E, CSK_Derived))
2635 return false;
2636
2637 // Truncate the path to the subobject, and remove any derived-to-base offsets.
2638 const RecordDecl *RD = TruncatedType;
2639 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
2640 if (RD->isInvalidDecl()) return false;
2641 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
2642 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
2643 if (isVirtualBaseClass(D.Entries[I]))
2644 Result.Offset -= Layout.getVBaseClassOffset(Base);
2645 else
2646 Result.Offset -= Layout.getBaseClassOffset(Base);
2647 RD = Base;
2648 }
2649 D.Entries.resize(TruncatedElements);
2650 return true;
2651}
2652
2653static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2654 const CXXRecordDecl *Derived,
2655 const CXXRecordDecl *Base,
2656 const ASTRecordLayout *RL = nullptr) {
2657 if (!RL) {
2658 if (Derived->isInvalidDecl()) return false;
2659 RL = &Info.Ctx.getASTRecordLayout(Derived);
2660 }
2661
2662 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
2663 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
2664 return true;
2665}
2666
2667static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2668 const CXXRecordDecl *DerivedDecl,
2669 const CXXBaseSpecifier *Base) {
2670 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
2671
2672 if (!Base->isVirtual())
2673 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
2674
2675 SubobjectDesignator &D = Obj.Designator;
2676 if (D.Invalid)
2677 return false;
2678
2679 // Extract most-derived object and corresponding type.
2680 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
2681 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
2682 return false;
2683
2684 // Find the virtual base class.
2685 if (DerivedDecl->isInvalidDecl()) return false;
2686 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
2687 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
2688 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
2689 return true;
2690}
2691
2692static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
2693 QualType Type, LValue &Result) {
2694 for (CastExpr::path_const_iterator PathI = E->path_begin(),
2695 PathE = E->path_end();
2696 PathI != PathE; ++PathI) {
2697 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
2698 *PathI))
2699 return false;
2700 Type = (*PathI)->getType();
2701 }
2702 return true;
2703}
2704
2705/// Cast an lvalue referring to a derived class to a known base subobject.
2706static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
2707 const CXXRecordDecl *DerivedRD,
2708 const CXXRecordDecl *BaseRD) {
2709 CXXBasePaths Paths(/*FindAmbiguities=*/false,
2710 /*RecordPaths=*/true, /*DetectVirtual=*/false);
2711 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
2712 llvm_unreachable("Class must be derived from the passed in base class!")::llvm::llvm_unreachable_internal("Class must be derived from the passed in base class!"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2712)
;
2713
2714 for (CXXBasePathElement &Elem : Paths.front())
2715 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
2716 return false;
2717 return true;
2718}
2719
2720/// Update LVal to refer to the given field, which must be a member of the type
2721/// currently described by LVal.
2722static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
2723 const FieldDecl *FD,
2724 const ASTRecordLayout *RL = nullptr) {
2725 if (!RL) {
2726 if (FD->getParent()->isInvalidDecl()) return false;
2727 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
2728 }
2729
2730 unsigned I = FD->getFieldIndex();
2731 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
2732 LVal.addDecl(Info, E, FD);
2733 return true;
2734}
2735
2736/// Update LVal to refer to the given indirect field.
2737static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
2738 LValue &LVal,
2739 const IndirectFieldDecl *IFD) {
2740 for (const auto *C : IFD->chain())
2741 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
2742 return false;
2743 return true;
2744}
2745
2746/// Get the size of the given type in char units.
2747static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
2748 QualType Type, CharUnits &Size) {
2749 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
2750 // extension.
2751 if (Type->isVoidType() || Type->isFunctionType()) {
2752 Size = CharUnits::One();
2753 return true;
2754 }
2755
2756 if (Type->isDependentType()) {
2757 Info.FFDiag(Loc);
2758 return false;
2759 }
2760
2761 if (!Type->isConstantSizeType()) {
2762 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
2763 // FIXME: Better diagnostic.
2764 Info.FFDiag(Loc);
2765 return false;
2766 }
2767
2768 Size = Info.Ctx.getTypeSizeInChars(Type);
2769 return true;
2770}
2771
2772/// Update a pointer value to model pointer arithmetic.
2773/// \param Info - Information about the ongoing evaluation.
2774/// \param E - The expression being evaluated, for diagnostic purposes.
2775/// \param LVal - The pointer value to be updated.
2776/// \param EltTy - The pointee type represented by LVal.
2777/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
2778static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2779 LValue &LVal, QualType EltTy,
2780 APSInt Adjustment) {
2781 CharUnits SizeOfPointee;
2782 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
2783 return false;
2784
2785 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
2786 return true;
2787}
2788
2789static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2790 LValue &LVal, QualType EltTy,
2791 int64_t Adjustment) {
2792 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
2793 APSInt::get(Adjustment));
2794}
2795
2796/// Update an lvalue to refer to a component of a complex number.
2797/// \param Info - Information about the ongoing evaluation.
2798/// \param LVal - The lvalue to be updated.
2799/// \param EltTy - The complex number's component type.
2800/// \param Imag - False for the real component, true for the imaginary.
2801static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
2802 LValue &LVal, QualType EltTy,
2803 bool Imag) {
2804 if (Imag) {
2805 CharUnits SizeOfComponent;
2806 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
2807 return false;
2808 LVal.Offset += SizeOfComponent;
2809 }
2810 LVal.addComplex(Info, E, EltTy, Imag);
2811 return true;
2812}
2813
2814/// Try to evaluate the initializer for a variable declaration.
2815///
2816/// \param Info Information about the ongoing evaluation.
2817/// \param E An expression to be used when printing diagnostics.
2818/// \param VD The variable whose initializer should be obtained.
2819/// \param Frame The frame in which the variable was created. Must be null
2820/// if this variable is not local to the evaluation.
2821/// \param Result Filled in with a pointer to the value of the variable.
2822static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
2823 const VarDecl *VD, CallStackFrame *Frame,
2824 APValue *&Result, const LValue *LVal) {
2825
2826 // If this is a parameter to an active constexpr function call, perform
2827 // argument substitution.
2828 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
2829 // Assume arguments of a potential constant expression are unknown
2830 // constant expressions.
2831 if (Info.checkingPotentialConstantExpression())
2832 return false;
2833 if (!Frame || !Frame->Arguments) {
2834 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2835 return false;
2836 }
2837 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()];
2838 return true;
2839 }
2840
2841 // If this is a local variable, dig out its value.
2842 if (Frame) {
2843 Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion())
2844 : Frame->getCurrentTemporary(VD);
2845 if (!Result) {
2846 // Assume variables referenced within a lambda's call operator that were
2847 // not declared within the call operator are captures and during checking
2848 // of a potential constant expression, assume they are unknown constant
2849 // expressions.
2850 assert(isLambdaCallOperator(Frame->Callee) &&((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2852, __PRETTY_FUNCTION__))
2851 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2852, __PRETTY_FUNCTION__))
2852 "missing value for local variable")((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2852, __PRETTY_FUNCTION__))
;
2853 if (Info.checkingPotentialConstantExpression())
2854 return false;
2855 // FIXME: implement capture evaluation during constant expr evaluation.
2856 Info.FFDiag(E->getBeginLoc(),
2857 diag::note_unimplemented_constexpr_lambda_feature_ast)
2858 << "captures not currently allowed";
2859 return false;
2860 }
2861 return true;
2862 }
2863
2864 // Dig out the initializer, and use the declaration which it's attached to.
2865 const Expr *Init = VD->getAnyInitializer(VD);
2866 if (!Init || Init->isValueDependent()) {
2867 // If we're checking a potential constant expression, the variable could be
2868 // initialized later.
2869 if (!Info.checkingPotentialConstantExpression())
2870 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2871 return false;
2872 }
2873
2874 // If we're currently evaluating the initializer of this declaration, use that
2875 // in-flight value.
2876 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
2877 Result = Info.EvaluatingDeclValue;
2878 return true;
2879 }
2880
2881 // Never evaluate the initializer of a weak variable. We can't be sure that
2882 // this is the definition which will be used.
2883 if (VD->isWeak()) {
2884 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2885 return false;
2886 }
2887
2888 // Check that we can fold the initializer. In C++, we will have already done
2889 // this in the cases where it matters for conformance.
2890 SmallVector<PartialDiagnosticAt, 8> Notes;
2891 if (!VD->evaluateValue(Notes)) {
2892 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant,
2893 Notes.size() + 1) << VD;
2894 Info.Note(VD->getLocation(), diag::note_declared_at);
2895 Info.addNotes(Notes);
2896 return false;
2897 } else if (!VD->checkInitIsICE()) {
2898 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant,
2899 Notes.size() + 1) << VD;
2900 Info.Note(VD->getLocation(), diag::note_declared_at);
2901 Info.addNotes(Notes);
2902 }
2903
2904 Result = VD->getEvaluatedValue();
2905 return true;
2906}
2907
2908static bool IsConstNonVolatile(QualType T) {
2909 Qualifiers Quals = T.getQualifiers();
2910 return Quals.hasConst() && !Quals.hasVolatile();
2911}
2912
2913/// Get the base index of the given base class within an APValue representing
2914/// the given derived class.
2915static unsigned getBaseIndex(const CXXRecordDecl *Derived,
2916 const CXXRecordDecl *Base) {
2917 Base = Base->getCanonicalDecl();
2918 unsigned Index = 0;
2919 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
2920 E = Derived->bases_end(); I != E; ++I, ++Index) {
2921 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
2922 return Index;
2923 }
2924
2925 llvm_unreachable("base class missing from derived class's bases list")::llvm::llvm_unreachable_internal("base class missing from derived class's bases list"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2925)
;
2926}
2927
2928/// Extract the value of a character from a string literal.
2929static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
2930 uint64_t Index) {
2931 assert(!isa<SourceLocExpr>(Lit) &&((!isa<SourceLocExpr>(Lit) && "SourceLocExpr should have already been converted to a StringLiteral"
) ? static_cast<void> (0) : __assert_fail ("!isa<SourceLocExpr>(Lit) && \"SourceLocExpr should have already been converted to a StringLiteral\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2932, __PRETTY_FUNCTION__))
2932 "SourceLocExpr should have already been converted to a StringLiteral")((!isa<SourceLocExpr>(Lit) && "SourceLocExpr should have already been converted to a StringLiteral"
) ? static_cast<void> (0) : __assert_fail ("!isa<SourceLocExpr>(Lit) && \"SourceLocExpr should have already been converted to a StringLiteral\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2932, __PRETTY_FUNCTION__))
;
2933
2934 // FIXME: Support MakeStringConstant
2935 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
2936 std::string Str;
2937 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
2938 assert(Index <= Str.size() && "Index too large")((Index <= Str.size() && "Index too large") ? static_cast
<void> (0) : __assert_fail ("Index <= Str.size() && \"Index too large\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2938, __PRETTY_FUNCTION__))
;
2939 return APSInt::getUnsigned(Str.c_str()[Index]);
2940 }
2941
2942 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
2943 Lit = PE->getFunctionName();
2944 const StringLiteral *S = cast<StringLiteral>(Lit);
2945 const ConstantArrayType *CAT =
2946 Info.Ctx.getAsConstantArrayType(S->getType());
2947 assert(CAT && "string literal isn't an array")((CAT && "string literal isn't an array") ? static_cast
<void> (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2947, __PRETTY_FUNCTION__))
;
2948 QualType CharType = CAT->getElementType();
2949 assert(CharType->isIntegerType() && "unexpected character type")((CharType->isIntegerType() && "unexpected character type"
) ? static_cast<void> (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2949, __PRETTY_FUNCTION__))
;
2950
2951 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2952 CharType->isUnsignedIntegerType());
2953 if (Index < S->getLength())
2954 Value = S->getCodeUnit(Index);
2955 return Value;
2956}
2957
2958// Expand a string literal into an array of characters.
2959//
2960// FIXME: This is inefficient; we should probably introduce something similar
2961// to the LLVM ConstantDataArray to make this cheaper.
2962static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
2963 APValue &Result,
2964 QualType AllocType = QualType()) {
2965 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
2966 AllocType.isNull() ? S->getType() : AllocType);
2967 assert(CAT && "string literal isn't an array")((CAT && "string literal isn't an array") ? static_cast
<void> (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2967, __PRETTY_FUNCTION__))
;
2968 QualType CharType = CAT->getElementType();
2969 assert(CharType->isIntegerType() && "unexpected character type")((CharType->isIntegerType() && "unexpected character type"
) ? static_cast<void> (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2969, __PRETTY_FUNCTION__))
;
2970
2971 unsigned Elts = CAT->getSize().getZExtValue();
2972 Result = APValue(APValue::UninitArray(),
2973 std::min(S->getLength(), Elts), Elts);
2974 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2975 CharType->isUnsignedIntegerType());
2976 if (Result.hasArrayFiller())
2977 Result.getArrayFiller() = APValue(Value);
2978 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
2979 Value = S->getCodeUnit(I);
2980 Result.getArrayInitializedElt(I) = APValue(Value);
2981 }
2982}
2983
2984// Expand an array so that it has more than Index filled elements.
2985static void expandArray(APValue &Array, unsigned Index) {
2986 unsigned Size = Array.getArraySize();
2987 assert(Index < Size)((Index < Size) ? static_cast<void> (0) : __assert_fail
("Index < Size", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 2987, __PRETTY_FUNCTION__))
;
2988
2989 // Always at least double the number of elements for which we store a value.
2990 unsigned OldElts = Array.getArrayInitializedElts();
2991 unsigned NewElts = std::max(Index+1, OldElts * 2);
2992 NewElts = std::min(Size, std::max(NewElts, 8u));
2993
2994 // Copy the data across.
2995 APValue NewValue(APValue::UninitArray(), NewElts, Size);
2996 for (unsigned I = 0; I != OldElts; ++I)
2997 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
2998 for (unsigned I = OldElts; I != NewElts; ++I)
2999 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3000 if (NewValue.hasArrayFiller())
3001 NewValue.getArrayFiller() = Array.getArrayFiller();
3002 Array.swap(NewValue);
3003}
3004
3005/// Determine whether a type would actually be read by an lvalue-to-rvalue
3006/// conversion. If it's of class type, we may assume that the copy operation
3007/// is trivial. Note that this is never true for a union type with fields
3008/// (because the copy always "reads" the active member) and always true for
3009/// a non-class type.
3010static bool isReadByLvalueToRvalueConversion(QualType T) {
3011 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3012 if (!RD || (RD->isUnion() && !RD->field_empty()))
3013 return true;
3014 if (RD->isEmpty())
3015 return false;
3016
3017 for (auto *Field : RD->fields())
3018 if (isReadByLvalueToRvalueConversion(Field->getType()))
3019 return true;
3020
3021 for (auto &BaseSpec : RD->bases())
3022 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3023 return true;
3024
3025 return false;
3026}
3027
3028/// Diagnose an attempt to read from any unreadable field within the specified
3029/// type, which might be a class type.
3030static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3031 QualType T) {
3032 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3033 if (!RD)
3034 return false;
3035
3036 if (!RD->hasMutableFields())
3037 return false;
3038
3039 for (auto *Field : RD->fields()) {
3040 // If we're actually going to read this field in some way, then it can't
3041 // be mutable. If we're in a union, then assigning to a mutable field
3042 // (even an empty one) can change the active member, so that's not OK.
3043 // FIXME: Add core issue number for the union case.
3044 if (Field->isMutable() &&
3045 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3046 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3047 Info.Note(Field->getLocation(), diag::note_declared_at);
3048 return true;
3049 }
3050
3051 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3052 return true;
3053 }
3054
3055 for (auto &BaseSpec : RD->bases())
3056 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3057 return true;
3058
3059 // All mutable fields were empty, and thus not actually read.
3060 return false;
3061}
3062
3063static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3064 APValue::LValueBase Base,
3065 bool MutableSubobject = false) {
3066 // A temporary we created.
3067 if (Base.getCallIndex())
3068 return true;
3069
3070 auto *Evaluating = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
3071 if (!Evaluating)
3072 return false;
3073
3074 auto *BaseD = Base.dyn_cast<const ValueDecl*>();
3075
3076 switch (Info.IsEvaluatingDecl) {
3077 case EvalInfo::EvaluatingDeclKind::None:
3078 return false;
3079
3080 case EvalInfo::EvaluatingDeclKind::Ctor:
3081 // The variable whose initializer we're evaluating.
3082 if (BaseD)
3083 return declaresSameEntity(Evaluating, BaseD);
3084
3085 // A temporary lifetime-extended by the variable whose initializer we're
3086 // evaluating.
3087 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3088 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3089 return declaresSameEntity(BaseMTE->getExtendingDecl(), Evaluating);
3090 return false;
3091
3092 case EvalInfo::EvaluatingDeclKind::Dtor:
3093 // C++2a [expr.const]p6:
3094 // [during constant destruction] the lifetime of a and its non-mutable
3095 // subobjects (but not its mutable subobjects) [are] considered to start
3096 // within e.
3097 //
3098 // FIXME: We can meaningfully extend this to cover non-const objects, but
3099 // we will need special handling: we should be able to access only
3100 // subobjects of such objects that are themselves declared const.
3101 if (!BaseD ||
3102 !(BaseD->getType().isConstQualified() ||
3103 BaseD->getType()->isReferenceType()) ||
3104 MutableSubobject)
3105 return false;
3106 return declaresSameEntity(Evaluating, BaseD);
3107 }
3108
3109 llvm_unreachable("unknown evaluating decl kind")::llvm::llvm_unreachable_internal("unknown evaluating decl kind"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3109)
;
3110}
3111
3112namespace {
3113/// A handle to a complete object (an object that is not a subobject of
3114/// another object).
3115struct CompleteObject {
3116 /// The identity of the object.
3117 APValue::LValueBase Base;
3118 /// The value of the complete object.
3119 APValue *Value;
3120 /// The type of the complete object.
3121 QualType Type;
3122
3123 CompleteObject() : Value(nullptr) {}
3124 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3125 : Base(Base), Value(Value), Type(Type) {}
3126
3127 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3128 // In C++14 onwards, it is permitted to read a mutable member whose
3129 // lifetime began within the evaluation.
3130 // FIXME: Should we also allow this in C++11?
3131 if (!Info.getLangOpts().CPlusPlus14)
3132 return false;
3133 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3134 }
3135
3136 explicit operator bool() const { return !Type.isNull(); }
3137};
3138} // end anonymous namespace
3139
3140static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3141 bool IsMutable = false) {
3142 // C++ [basic.type.qualifier]p1:
3143 // - A const object is an object of type const T or a non-mutable subobject
3144 // of a const object.
3145 if (ObjType.isConstQualified() && !IsMutable)
3146 SubobjType.addConst();
3147 // - A volatile object is an object of type const T or a subobject of a
3148 // volatile object.
3149 if (ObjType.isVolatileQualified())
3150 SubobjType.addVolatile();
3151 return SubobjType;
3152}
3153
3154/// Find the designated sub-object of an rvalue.
3155template<typename SubobjectHandler>
3156typename SubobjectHandler::result_type
3157findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3158 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3159 if (Sub.Invalid)
3160 // A diagnostic will have already been produced.
3161 return handler.failed();
3162 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3163 if (Info.getLangOpts().CPlusPlus11)
3164 Info.FFDiag(E, Sub.isOnePastTheEnd()
3165 ? diag::note_constexpr_access_past_end
3166 : diag::note_constexpr_access_unsized_array)
3167 << handler.AccessKind;
3168 else
3169 Info.FFDiag(E);
3170 return handler.failed();
3171 }
3172
3173 APValue *O = Obj.Value;
3174 QualType ObjType = Obj.Type;
3175 const FieldDecl *LastField = nullptr;
3176 const FieldDecl *VolatileField = nullptr;
3177
3178 // Walk the designator's path to find the subobject.
3179 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3180 // Reading an indeterminate value is undefined, but assigning over one is OK.
3181 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3182 (O->isIndeterminate() && handler.AccessKind != AK_Construct &&
3183 handler.AccessKind != AK_Assign &&
3184 handler.AccessKind != AK_ReadObjectRepresentation)) {
3185 if (!Info.checkingPotentialConstantExpression())
3186 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3187 << handler.AccessKind << O->isIndeterminate();
3188 return handler.failed();
3189 }
3190
3191 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3192 // const and volatile semantics are not applied on an object under
3193 // {con,de}struction.
3194 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3195 ObjType->isRecordType() &&
3196 Info.isEvaluatingCtorDtor(
3197 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
3198 Sub.Entries.begin() + I)) !=
3199 ConstructionPhase::None) {
3200 ObjType = Info.Ctx.getCanonicalType(ObjType);
3201 ObjType.removeLocalConst();
3202 ObjType.removeLocalVolatile();
3203 }
3204
3205 // If this is our last pass, check that the final object type is OK.
3206 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3207 // Accesses to volatile objects are prohibited.
3208 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3209 if (Info.getLangOpts().CPlusPlus) {
3210 int DiagKind;
3211 SourceLocation Loc;
3212 const NamedDecl *Decl = nullptr;
3213 if (VolatileField) {
3214 DiagKind = 2;
3215 Loc = VolatileField->getLocation();
3216 Decl = VolatileField;
3217 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3218 DiagKind = 1;
3219 Loc = VD->getLocation();
3220 Decl = VD;
3221 } else {
3222 DiagKind = 0;
3223 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3224 Loc = E->getExprLoc();
3225 }
3226 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3227 << handler.AccessKind << DiagKind << Decl;
3228 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3229 } else {
3230 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3231 }
3232 return handler.failed();
3233 }
3234
3235 // If we are reading an object of class type, there may still be more
3236 // things we need to check: if there are any mutable subobjects, we
3237 // cannot perform this read. (This only happens when performing a trivial
3238 // copy or assignment.)
3239 if (ObjType->isRecordType() &&
3240 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3241 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3242 return handler.failed();
3243 }
3244
3245 if (I == N) {
3246 if (!handler.found(*O, ObjType))
3247 return false;
3248
3249 // If we modified a bit-field, truncate it to the right width.
3250 if (isModification(handler.AccessKind) &&
3251 LastField && LastField->isBitField() &&
3252 !truncateBitfieldValue(Info, E, *O, LastField))
3253 return false;
3254
3255 return true;
3256 }
3257
3258 LastField = nullptr;
3259 if (ObjType->isArrayType()) {
3260 // Next subobject is an array element.
3261 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3262 assert(CAT && "vla in literal type?")((CAT && "vla in literal type?") ? static_cast<void
> (0) : __assert_fail ("CAT && \"vla in literal type?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3262, __PRETTY_FUNCTION__))
;
3263 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3264 if (CAT->getSize().ule(Index)) {
3265 // Note, it should not be possible to form a pointer with a valid
3266 // designator which points more than one past the end of the array.
3267 if (Info.getLangOpts().CPlusPlus11)
3268 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3269 << handler.AccessKind;
3270 else
3271 Info.FFDiag(E);
3272 return handler.failed();
3273 }
3274
3275 ObjType = CAT->getElementType();
3276
3277 if (O->getArrayInitializedElts() > Index)
3278 O = &O->getArrayInitializedElt(Index);
3279 else if (!isRead(handler.AccessKind)) {
3280 expandArray(*O, Index);
3281 O = &O->getArrayInitializedElt(Index);
3282 } else
3283 O = &O->getArrayFiller();
3284 } else if (ObjType->isAnyComplexType()) {
3285 // Next subobject is a complex number.
3286 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3287 if (Index > 1) {
3288 if (Info.getLangOpts().CPlusPlus11)
3289 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3290 << handler.AccessKind;
3291 else
3292 Info.FFDiag(E);
3293 return handler.failed();
3294 }
3295
3296 ObjType = getSubobjectType(
3297 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3298
3299 assert(I == N - 1 && "extracting subobject of scalar?")((I == N - 1 && "extracting subobject of scalar?") ? static_cast
<void> (0) : __assert_fail ("I == N - 1 && \"extracting subobject of scalar?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3299, __PRETTY_FUNCTION__))
;
3300 if (O->isComplexInt()) {
3301 return handler.found(Index ? O->getComplexIntImag()
3302 : O->getComplexIntReal(), ObjType);
3303 } else {
3304 assert(O->isComplexFloat())((O->isComplexFloat()) ? static_cast<void> (0) : __assert_fail
("O->isComplexFloat()", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3304, __PRETTY_FUNCTION__))
;
3305 return handler.found(Index ? O->getComplexFloatImag()
3306 : O->getComplexFloatReal(), ObjType);
3307 }
3308 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3309 if (Field->isMutable() &&
3310 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3311 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3312 << handler.AccessKind << Field;
3313 Info.Note(Field->getLocation(), diag::note_declared_at);
3314 return handler.failed();
3315 }
3316
3317 // Next subobject is a class, struct or union field.
3318 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3319 if (RD->isUnion()) {
3320 const FieldDecl *UnionField = O->getUnionField();
3321 if (!UnionField ||
3322 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3323 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3324 // Placement new onto an inactive union member makes it active.
3325 O->setUnion(Field, APValue());
3326 } else {
3327 // FIXME: If O->getUnionValue() is absent, report that there's no
3328 // active union member rather than reporting the prior active union
3329 // member. We'll need to fix nullptr_t to not use APValue() as its
3330 // representation first.
3331 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3332 << handler.AccessKind << Field << !UnionField << UnionField;
3333 return handler.failed();
3334 }
3335 }
3336 O = &O->getUnionValue();
3337 } else
3338 O = &O->getStructField(Field->getFieldIndex());
3339
3340 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3341 LastField = Field;
3342 if (Field->getType().isVolatileQualified())
3343 VolatileField = Field;
3344 } else {
3345 // Next subobject is a base class.
3346 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3347 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3348 O = &O->getStructBase(getBaseIndex(Derived, Base));
3349
3350 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3351 }
3352 }
3353}
3354
3355namespace {
3356struct ExtractSubobjectHandler {
3357 EvalInfo &Info;
3358 const Expr *E;
3359 APValue &Result;
3360 const AccessKinds AccessKind;
3361
3362 typedef bool result_type;
3363 bool failed() { return false; }
3364 bool found(APValue &Subobj, QualType SubobjType) {
3365 Result = Subobj;
3366 if (AccessKind == AK_ReadObjectRepresentation)
3367 return true;
3368 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3369 }
3370 bool found(APSInt &Value, QualType SubobjType) {
3371 Result = APValue(Value);
3372 return true;
3373 }
3374 bool found(APFloat &Value, QualType SubobjType) {
3375 Result = APValue(Value);
3376 return true;
3377 }
3378};
3379} // end anonymous namespace
3380
3381/// Extract the designated sub-object of an rvalue.
3382static bool extractSubobject(EvalInfo &Info, const Expr *E,
3383 const CompleteObject &Obj,
3384 const SubobjectDesignator &Sub, APValue &Result,
3385 AccessKinds AK = AK_Read) {
3386 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation)((AK == AK_Read || AK == AK_ReadObjectRepresentation) ? static_cast
<void> (0) : __assert_fail ("AK == AK_Read || AK == AK_ReadObjectRepresentation"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3386, __PRETTY_FUNCTION__))
;
3387 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3388 return findSubobject(Info, E, Obj, Sub, Handler);
3389}
3390
3391namespace {
3392struct ModifySubobjectHandler {
3393 EvalInfo &Info;
3394 APValue &NewVal;
3395 const Expr *E;
3396
3397 typedef bool result_type;
3398 static const AccessKinds AccessKind = AK_Assign;
3399
3400 bool checkConst(QualType QT) {
3401 // Assigning to a const object has undefined behavior.
3402 if (QT.isConstQualified()) {
3403 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3404 return false;
3405 }
3406 return true;
3407 }
3408
3409 bool failed() { return false; }
3410 bool found(APValue &Subobj, QualType SubobjType) {
3411 if (!checkConst(SubobjType))
3412 return false;
3413 // We've been given ownership of NewVal, so just swap it in.
3414 Subobj.swap(NewVal);
3415 return true;
3416 }
3417 bool found(APSInt &Value, QualType SubobjType) {
3418 if (!checkConst(SubobjType))
3419 return false;
3420 if (!NewVal.isInt()) {
3421 // Maybe trying to write a cast pointer value into a complex?
3422 Info.FFDiag(E);
3423 return false;
3424 }
3425 Value = NewVal.getInt();
3426 return true;
3427 }
3428 bool found(APFloat &Value, QualType SubobjType) {
3429 if (!checkConst(SubobjType))
3430 return false;
3431 Value = NewVal.getFloat();
3432 return true;
3433 }
3434};
3435} // end anonymous namespace
3436
3437const AccessKinds ModifySubobjectHandler::AccessKind;
3438
3439/// Update the designated sub-object of an rvalue to the given value.
3440static bool modifySubobject(EvalInfo &Info, const Expr *E,
3441 const CompleteObject &Obj,
3442 const SubobjectDesignator &Sub,
3443 APValue &NewVal) {
3444 ModifySubobjectHandler Handler = { Info, NewVal, E };
3445 return findSubobject(Info, E, Obj, Sub, Handler);
3446}
3447
3448/// Find the position where two subobject designators diverge, or equivalently
3449/// the length of the common initial subsequence.
3450static unsigned FindDesignatorMismatch(QualType ObjType,
3451 const SubobjectDesignator &A,
3452 const SubobjectDesignator &B,
3453 bool &WasArrayIndex) {
3454 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3455 for (/**/; I != N; ++I) {
3456 if (!ObjType.isNull() &&
3457 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3458 // Next subobject is an array element.
3459 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3460 WasArrayIndex = true;
3461 return I;
3462 }
3463 if (ObjType->isAnyComplexType())
3464 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3465 else
3466 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3467 } else {
3468 if (A.Entries[I].getAsBaseOrMember() !=
3469 B.Entries[I].getAsBaseOrMember()) {
3470 WasArrayIndex = false;
3471 return I;
3472 }
3473 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3474 // Next subobject is a field.
3475 ObjType = FD->getType();
3476 else
3477 // Next subobject is a base class.
3478 ObjType = QualType();
3479 }
3480 }
3481 WasArrayIndex = false;
3482 return I;
3483}
3484
3485/// Determine whether the given subobject designators refer to elements of the
3486/// same array object.
3487static bool AreElementsOfSameArray(QualType ObjType,
3488 const SubobjectDesignator &A,
3489 const SubobjectDesignator &B) {
3490 if (A.Entries.size() != B.Entries.size())
3491 return false;
3492
3493 bool IsArray = A.MostDerivedIsArrayElement;
3494 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3495 // A is a subobject of the array element.
3496 return false;
3497
3498 // If A (and B) designates an array element, the last entry will be the array
3499 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3500 // of length 1' case, and the entire path must match.
3501 bool WasArrayIndex;
3502 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3503 return CommonLength >= A.Entries.size() - IsArray;
3504}
3505
3506/// Find the complete object to which an LValue refers.
3507static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3508 AccessKinds AK, const LValue &LVal,
3509 QualType LValType) {
3510 if (LVal.InvalidBase) {
3511 Info.FFDiag(E);
3512 return CompleteObject();
3513 }
3514
3515 if (!LVal.Base) {
3516 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3517 return CompleteObject();
3518 }
3519
3520 CallStackFrame *Frame = nullptr;
3521 unsigned Depth = 0;
3522 if (LVal.getLValueCallIndex()) {
3523 std::tie(Frame, Depth) =
3524 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3525 if (!Frame) {
3526 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3527 << AK << LVal.Base.is<const ValueDecl*>();
3528 NoteLValueLocation(Info, LVal.Base);
3529 return CompleteObject();
3530 }
3531 }
3532
3533 bool IsAccess = isAnyAccess(AK);
3534
3535 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3536 // is not a constant expression (even if the object is non-volatile). We also
3537 // apply this rule to C++98, in order to conform to the expected 'volatile'
3538 // semantics.
3539 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3540 if (Info.getLangOpts().CPlusPlus)
3541 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3542 << AK << LValType;
3543 else
3544 Info.FFDiag(E);
3545 return CompleteObject();
3546 }
3547
3548 // Compute value storage location and type of base object.
3549 APValue *BaseVal = nullptr;
3550 QualType BaseType = getType(LVal.Base);
3551
3552 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) {
3553 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
3554 // In C++11, constexpr, non-volatile variables initialized with constant
3555 // expressions are constant expressions too. Inside constexpr functions,
3556 // parameters are constant expressions even if they're non-const.
3557 // In C++1y, objects local to a constant expression (those with a Frame) are
3558 // both readable and writable inside constant expressions.
3559 // In C, such things can also be folded, although they are not ICEs.
3560 const VarDecl *VD = dyn_cast<VarDecl>(D);
3561 if (VD) {
3562 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
3563 VD = VDef;
3564 }
3565 if (!VD || VD->isInvalidDecl()) {
3566 Info.FFDiag(E);
3567 return CompleteObject();
3568 }
3569
3570 // Unless we're looking at a local variable or argument in a constexpr call,
3571 // the variable we're reading must be const.
3572 if (!Frame) {
3573 if (Info.getLangOpts().CPlusPlus14 &&
3574 lifetimeStartedInEvaluation(Info, LVal.Base)) {
3575 // OK, we can read and modify an object if we're in the process of
3576 // evaluating its initializer, because its lifetime began in this
3577 // evaluation.
3578 } else if (isModification(AK)) {
3579 // All the remaining cases do not permit modification of the object.
3580 Info.FFDiag(E, diag::note_constexpr_modify_global);
3581 return CompleteObject();
3582 } else if (VD->isConstexpr()) {
3583 // OK, we can read this variable.
3584 } else if (BaseType->isIntegralOrEnumerationType()) {
3585 // In OpenCL if a variable is in constant address space it is a const
3586 // value.
3587 if (!(BaseType.isConstQualified() ||
3588 (Info.getLangOpts().OpenCL &&
3589 BaseType.getAddressSpace() == LangAS::opencl_constant))) {
3590 if (!IsAccess)
3591 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
3592 if (Info.getLangOpts().CPlusPlus) {
3593 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
3594 Info.Note(VD->getLocation(), diag::note_declared_at);
3595 } else {
3596 Info.FFDiag(E);
3597 }
3598 return CompleteObject();
3599 }
3600 } else if (!IsAccess) {
3601 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
3602 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) {
3603 // We support folding of const floating-point types, in order to make
3604 // static const data members of such types (supported as an extension)
3605 // more useful.
3606 if (Info.getLangOpts().CPlusPlus11) {
3607 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3608 Info.Note(VD->getLocation(), diag::note_declared_at);
3609 } else {
3610 Info.CCEDiag(E);
3611 }
3612 } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
3613 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
3614 // Keep evaluating to see what we can do.
3615 } else {
3616 // FIXME: Allow folding of values of any literal type in all languages.
3617 if (Info.checkingPotentialConstantExpression() &&
3618 VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) {
3619 // The definition of this variable could be constexpr. We can't
3620 // access it right now, but may be able to in future.
3621 } else if (Info.getLangOpts().CPlusPlus11) {
3622 Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3623 Info.Note(VD->getLocation(), diag::note_declared_at);
3624 } else {
3625 Info.FFDiag(E);
3626 }
3627 return CompleteObject();
3628 }
3629 }
3630
3631 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal))
3632 return CompleteObject();
3633 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
3634 Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA);
3635 if (!Alloc) {
3636 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
3637 return CompleteObject();
3638 }
3639 return CompleteObject(LVal.Base, &(*Alloc)->Value,
3640 LVal.Base.getDynamicAllocType());
3641 } else {
3642 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3643
3644 if (!Frame) {
3645 if (const MaterializeTemporaryExpr *MTE =
3646 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
3647 assert(MTE->getStorageDuration() == SD_Static &&((MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"
) ? static_cast<void> (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3648, __PRETTY_FUNCTION__))
3648 "should have a frame for a non-global materialized temporary")((MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"
) ? static_cast<void> (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3648, __PRETTY_FUNCTION__))
;
3649
3650 // Per C++1y [expr.const]p2:
3651 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
3652 // - a [...] glvalue of integral or enumeration type that refers to
3653 // a non-volatile const object [...]
3654 // [...]
3655 // - a [...] glvalue of literal type that refers to a non-volatile
3656 // object whose lifetime began within the evaluation of e.
3657 //
3658 // C++11 misses the 'began within the evaluation of e' check and
3659 // instead allows all temporaries, including things like:
3660 // int &&r = 1;
3661 // int x = ++r;
3662 // constexpr int k = r;
3663 // Therefore we use the C++14 rules in C++11 too.
3664 //
3665 // Note that temporaries whose lifetimes began while evaluating a
3666 // variable's constructor are not usable while evaluating the
3667 // corresponding destructor, not even if they're of const-qualified
3668 // types.
3669 if (!(BaseType.isConstQualified() &&
3670 BaseType->isIntegralOrEnumerationType()) &&
3671 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
3672 if (!IsAccess)
3673 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
3674 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
3675 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
3676 return CompleteObject();
3677 }
3678
3679 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
3680 assert(BaseVal && "got reference to unevaluated temporary")((BaseVal && "got reference to unevaluated temporary"
) ? static_cast<void> (0) : __assert_fail ("BaseVal && \"got reference to unevaluated temporary\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3680, __PRETTY_FUNCTION__))
;
3681 } else {
3682 if (!IsAccess)
3683 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
3684 APValue Val;
3685 LVal.moveInto(Val);
3686 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
3687 << AK
3688 << Val.getAsString(Info.Ctx,
3689 Info.Ctx.getLValueReferenceType(LValType));
3690 NoteLValueLocation(Info, LVal.Base);
3691 return CompleteObject();
3692 }
3693 } else {
3694 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
3695 assert(BaseVal && "missing value for temporary")((BaseVal && "missing value for temporary") ? static_cast
<void> (0) : __assert_fail ("BaseVal && \"missing value for temporary\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3695, __PRETTY_FUNCTION__))
;
3696 }
3697 }
3698
3699 // In C++14, we can't safely access any mutable state when we might be
3700 // evaluating after an unmodeled side effect.
3701 //
3702 // FIXME: Not all local state is mutable. Allow local constant subobjects
3703 // to be read here (but take care with 'mutable' fields).
3704 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
3705 Info.EvalStatus.HasSideEffects) ||
3706 (isModification(AK) && Depth < Info.SpeculativeEvaluationDepth))
3707 return CompleteObject();
3708
3709 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
3710}
3711
3712/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
3713/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
3714/// glvalue referred to by an entity of reference type.
3715///
3716/// \param Info - Information about the ongoing evaluation.
3717/// \param Conv - The expression for which we are performing the conversion.
3718/// Used for diagnostics.
3719/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
3720/// case of a non-class type).
3721/// \param LVal - The glvalue on which we are attempting to perform this action.
3722/// \param RVal - The produced value will be placed here.
3723/// \param WantObjectRepresentation - If true, we're looking for the object
3724/// representation rather than the value, and in particular,
3725/// there is no requirement that the result be fully initialized.
3726static bool
3727handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
3728 const LValue &LVal, APValue &RVal,
3729 bool WantObjectRepresentation = false) {
3730 if (LVal.Designator.Invalid)
3731 return false;
3732
3733 // Check for special cases where there is no existing APValue to look at.
3734 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3735
3736 AccessKinds AK =
3737 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
3738
3739 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
3740 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
3741 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
3742 // initializer until now for such expressions. Such an expression can't be
3743 // an ICE in C, so this only matters for fold.
3744 if (Type.isVolatileQualified()) {
3745 Info.FFDiag(Conv);
3746 return false;
3747 }
3748 APValue Lit;
3749 if (!Evaluate(Lit, Info, CLE->getInitializer()))
3750 return false;
3751 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
3752 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
3753 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
3754 // Special-case character extraction so we don't have to construct an
3755 // APValue for the whole string.
3756 assert(LVal.Designator.Entries.size() <= 1 &&((LVal.Designator.Entries.size() <= 1 && "Can only read characters from string literals"
) ? static_cast<void> (0) : __assert_fail ("LVal.Designator.Entries.size() <= 1 && \"Can only read characters from string literals\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3757, __PRETTY_FUNCTION__))
3757 "Can only read characters from string literals")((LVal.Designator.Entries.size() <= 1 && "Can only read characters from string literals"
) ? static_cast<void> (0) : __assert_fail ("LVal.Designator.Entries.size() <= 1 && \"Can only read characters from string literals\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 3757, __PRETTY_FUNCTION__))
;
3758 if (LVal.Designator.Entries.empty()) {
3759 // Fail for now for LValue to RValue conversion of an array.
3760 // (This shouldn't show up in C/C++, but it could be triggered by a
3761 // weird EvaluateAsRValue call from a tool.)
3762 Info.FFDiag(Conv);
3763 return false;
3764 }
3765 if (LVal.Designator.isOnePastTheEnd()) {
3766 if (Info.getLangOpts().CPlusPlus11)
3767 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
3768 else
3769 Info.FFDiag(Conv);
3770 return false;
3771 }
3772 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
3773 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
3774 return true;
3775 }
3776 }
3777
3778 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
3779 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
3780}
3781
3782/// Perform an assignment of Val to LVal. Takes ownership of Val.
3783static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
3784 QualType LValType, APValue &Val) {
3785 if (LVal.Designator.Invalid)
3786 return false;
3787
3788 if (!Info.getLangOpts().CPlusPlus14) {
3789 Info.FFDiag(E);
3790 return false;
3791 }
3792
3793 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3794 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
3795}
3796
3797namespace {
3798struct CompoundAssignSubobjectHandler {
3799 EvalInfo &Info;
3800 const Expr *E;
3801 QualType PromotedLHSType;
3802 BinaryOperatorKind Opcode;
3803 const APValue &RHS;
3804
3805 static const AccessKinds AccessKind = AK_Assign;
3806
3807 typedef bool result_type;
3808
3809 bool checkConst(QualType QT) {
3810 // Assigning to a const object has undefined behavior.
3811 if (QT.isConstQualified()) {
3812 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3813 return false;
3814 }
3815 return true;
3816 }
3817
3818 bool failed() { return false; }
3819 bool found(APValue &Subobj, QualType SubobjType) {
3820 switch (Subobj.getKind()) {
3821 case APValue::Int:
3822 return found(Subobj.getInt(), SubobjType);
3823 case APValue::Float:
3824 return found(Subobj.getFloat(), SubobjType);
3825 case APValue::ComplexInt:
3826 case APValue::ComplexFloat:
3827 // FIXME: Implement complex compound assignment.
3828 Info.FFDiag(E);
3829 return false;
3830 case APValue::LValue:
3831 return foundPointer(Subobj, SubobjType);
3832 default:
3833 // FIXME: can this happen?
3834 Info.FFDiag(E);
3835 return false;
3836 }
3837 }
3838 bool found(APSInt &Value, QualType SubobjType) {
3839 if (!checkConst(SubobjType))
3840 return false;
3841
3842 if (!SubobjType->isIntegerType()) {
3843 // We don't support compound assignment on integer-cast-to-pointer
3844 // values.
3845 Info.FFDiag(E);
3846 return false;
3847 }
3848
3849 if (RHS.isInt()) {
3850 APSInt LHS =
3851 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
3852 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
3853 return false;
3854 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
3855 return true;
3856 } else if (RHS.isFloat()) {
3857 APFloat FValue(0.0);
3858 return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType,
3859 FValue) &&
3860 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
3861 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
3862 Value);
3863 }
3864
3865 Info.FFDiag(E);
3866 return false;
3867 }
3868 bool found(APFloat &Value, QualType SubobjType) {
3869 return checkConst(SubobjType) &&
3870 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
3871 Value) &&
3872 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
3873 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
3874 }
3875 bool foundPointer(APValue &Subobj, QualType SubobjType) {
3876 if (!checkConst(SubobjType))
3877 return false;
3878
3879 QualType PointeeType;
3880 if (const PointerType *PT = SubobjType->getAs<PointerType>())
3881 PointeeType = PT->getPointeeType();
3882
3883 if (PointeeType.isNull() || !RHS.isInt() ||
3884 (Opcode != BO_Add && Opcode != BO_Sub)) {
3885 Info.FFDiag(E);
3886 return false;
3887 }
3888
3889 APSInt Offset = RHS.getInt();
3890 if (Opcode == BO_Sub)
3891 negateAsSigned(Offset);
3892
3893 LValue LVal;
3894 LVal.setFrom(Info.Ctx, Subobj);
3895 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
3896 return false;
3897 LVal.moveInto(Subobj);
3898 return true;
3899 }
3900};
3901} // end anonymous namespace
3902
3903const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
3904
3905/// Perform a compound assignment of LVal <op>= RVal.
3906static bool handleCompoundAssignment(
3907 EvalInfo &Info, const Expr *E,
3908 const LValue &LVal, QualType LValType, QualType PromotedLValType,
3909 BinaryOperatorKind Opcode, const APValue &RVal) {
3910 if (LVal.Designator.Invalid)
3911 return false;
3912
3913 if (!Info.getLangOpts().CPlusPlus14) {
3914 Info.FFDiag(E);
3915 return false;
3916 }
3917
3918 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3919 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
3920 RVal };
3921 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3922}
3923
3924namespace {
3925struct IncDecSubobjectHandler {
3926 EvalInfo &Info;
3927 const UnaryOperator *E;
3928 AccessKinds AccessKind;
3929 APValue *Old;
3930
3931 typedef bool result_type;
3932
3933 bool checkConst(QualType QT) {
3934 // Assigning to a const object has undefined behavior.
3935 if (QT.isConstQualified()) {
3936 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3937 return false;
3938 }
3939 return true;
3940 }
3941
3942 bool failed() { return false; }
3943 bool found(APValue &Subobj, QualType SubobjType) {
3944 // Stash the old value. Also clear Old, so we don't clobber it later
3945 // if we're post-incrementing a complex.
3946 if (Old) {
3947 *Old = Subobj;
3948 Old = nullptr;
3949 }
3950
3951 switch (Subobj.getKind()) {
3952 case APValue::Int:
3953 return found(Subobj.getInt(), SubobjType);
3954 case APValue::Float:
3955 return found(Subobj.getFloat(), SubobjType);
3956 case APValue::ComplexInt:
3957 return found(Subobj.getComplexIntReal(),
3958 SubobjType->castAs<ComplexType>()->getElementType()
3959 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3960 case APValue::ComplexFloat:
3961 return found(Subobj.getComplexFloatReal(),
3962 SubobjType->castAs<ComplexType>()->getElementType()
3963 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3964 case APValue::LValue:
3965 return foundPointer(Subobj, SubobjType);
3966 default:
3967 // FIXME: can this happen?
3968 Info.FFDiag(E);
3969 return false;
3970 }
3971 }
3972 bool found(APSInt &Value, QualType SubobjType) {
3973 if (!checkConst(SubobjType))
3974 return false;
3975
3976 if (!SubobjType->isIntegerType()) {
3977 // We don't support increment / decrement on integer-cast-to-pointer
3978 // values.
3979 Info.FFDiag(E);
3980 return false;
3981 }
3982
3983 if (Old) *Old = APValue(Value);
3984
3985 // bool arithmetic promotes to int, and the conversion back to bool
3986 // doesn't reduce mod 2^n, so special-case it.
3987 if (SubobjType->isBooleanType()) {
3988 if (AccessKind == AK_Increment)
3989 Value = 1;
3990 else
3991 Value = !Value;
3992 return true;
3993 }
3994
3995 bool WasNegative = Value.isNegative();
3996 if (AccessKind == AK_Increment) {
3997 ++Value;
3998
3999 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4000 APSInt ActualValue(Value, /*IsUnsigned*/true);
4001 return HandleOverflow(Info, E, ActualValue, SubobjType);
4002 }
4003 } else {
4004 --Value;
4005
4006 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4007 unsigned BitWidth = Value.getBitWidth();
4008 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4009 ActualValue.setBit(BitWidth);
4010 return HandleOverflow(Info, E, ActualValue, SubobjType);
4011 }
4012 }
4013 return true;
4014 }
4015 bool found(APFloat &Value, QualType SubobjType) {
4016 if (!checkConst(SubobjType))
4017 return false;
4018
4019 if (Old) *Old = APValue(Value);
4020
4021 APFloat One(Value.getSemantics(), 1);
4022 if (AccessKind == AK_Increment)
4023 Value.add(One, APFloat::rmNearestTiesToEven);
4024 else
4025 Value.subtract(One, APFloat::rmNearestTiesToEven);
4026 return true;
4027 }
4028 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4029 if (!checkConst(SubobjType))
4030 return false;
4031
4032 QualType PointeeType;
4033 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4034 PointeeType = PT->getPointeeType();
4035 else {
4036 Info.FFDiag(E);
4037 return false;
4038 }
4039
4040 LValue LVal;
4041 LVal.setFrom(Info.Ctx, Subobj);
4042 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4043 AccessKind == AK_Increment ? 1 : -1))
4044 return false;
4045 LVal.moveInto(Subobj);
4046 return true;
4047 }
4048};
4049} // end anonymous namespace
4050
4051/// Perform an increment or decrement on LVal.
4052static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4053 QualType LValType, bool IsIncrement, APValue *Old) {
4054 if (LVal.Designator.Invalid)
4055 return false;
4056
4057 if (!Info.getLangOpts().CPlusPlus14) {
4058 Info.FFDiag(E);
4059 return false;
4060 }
4061
4062 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4063 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4064 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4065 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4066}
4067
4068/// Build an lvalue for the object argument of a member function call.
4069static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4070 LValue &This) {
4071 if (Object->getType()->isPointerType() && Object->isRValue())
4072 return EvaluatePointer(Object, This, Info);
4073
4074 if (Object->isGLValue())
4075 return EvaluateLValue(Object, This, Info);
4076
4077 if (Object->getType()->isLiteralType(Info.Ctx))
4078 return EvaluateTemporary(Object, This, Info);
4079
4080 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4081 return false;
4082}
4083
4084/// HandleMemberPointerAccess - Evaluate a member access operation and build an
4085/// lvalue referring to the result.
4086///
4087/// \param Info - Information about the ongoing evaluation.
4088/// \param LV - An lvalue referring to the base of the member pointer.
4089/// \param RHS - The member pointer expression.
4090/// \param IncludeMember - Specifies whether the member itself is included in
4091/// the resulting LValue subobject designator. This is not possible when
4092/// creating a bound member function.
4093/// \return The field or method declaration to which the member pointer refers,
4094/// or 0 if evaluation fails.
4095static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4096 QualType LVType,
4097 LValue &LV,
4098 const Expr *RHS,
4099 bool IncludeMember = true) {
4100 MemberPtr MemPtr;
4101 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4102 return nullptr;
4103
4104 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4105 // member value, the behavior is undefined.
4106 if (!MemPtr.getDecl()) {
4107 // FIXME: Specific diagnostic.
4108 Info.FFDiag(RHS);
4109 return nullptr;
4110 }
4111
4112 if (MemPtr.isDerivedMember()) {
4113 // This is a member of some derived class. Truncate LV appropriately.
4114 // The end of the derived-to-base path for the base object must match the
4115 // derived-to-base path for the member pointer.
4116 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4117 LV.Designator.Entries.size()) {
4118 Info.FFDiag(RHS);
4119 return nullptr;
4120 }
4121 unsigned PathLengthToMember =
4122 LV.Designator.Entries.size() - MemPtr.Path.size();
4123 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4124 const CXXRecordDecl *LVDecl = getAsBaseClass(
4125 LV.Designator.Entries[PathLengthToMember + I]);
4126 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4127 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4128 Info.FFDiag(RHS);
4129 return nullptr;
4130 }
4131 }
4132
4133 // Truncate the lvalue to the appropriate derived class.
4134 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4135 PathLengthToMember))
4136 return nullptr;
4137 } else if (!MemPtr.Path.empty()) {
4138 // Extend the LValue path with the member pointer's path.
4139 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4140 MemPtr.Path.size() + IncludeMember);
4141
4142 // Walk down to the appropriate base class.
4143 if (const PointerType *PT = LVType->getAs<PointerType>())
4144 LVType = PT->getPointeeType();
4145 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4146 assert(RD && "member pointer access on non-class-type expression")((RD && "member pointer access on non-class-type expression"
) ? static_cast<void> (0) : __assert_fail ("RD && \"member pointer access on non-class-type expression\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4146, __PRETTY_FUNCTION__))
;
4147 // The first class in the path is that of the lvalue.
4148 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4149 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4150 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4151 return nullptr;
4152 RD = Base;
4153 }
4154 // Finally cast to the class containing the member.
4155 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4156 MemPtr.getContainingRecord()))
4157 return nullptr;
4158 }
4159
4160 // Add the member. Note that we cannot build bound member functions here.
4161 if (IncludeMember) {
4162 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4163 if (!HandleLValueMember(Info, RHS, LV, FD))
4164 return nullptr;
4165 } else if (const IndirectFieldDecl *IFD =
4166 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4167 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4168 return nullptr;
4169 } else {
4170 llvm_unreachable("can't construct reference to bound member function")::llvm::llvm_unreachable_internal("can't construct reference to bound member function"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4170)
;
4171 }
4172 }
4173
4174 return MemPtr.getDecl();
4175}
4176
4177static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4178 const BinaryOperator *BO,
4179 LValue &LV,
4180 bool IncludeMember = true) {
4181 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI)((BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI
) ? static_cast<void> (0) : __assert_fail ("BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4181, __PRETTY_FUNCTION__))
;
4182
4183 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4184 if (Info.noteFailure()) {
4185 MemberPtr MemPtr;
4186 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4187 }
4188 return nullptr;
4189 }
4190
4191 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4192 BO->getRHS(), IncludeMember);
4193}
4194
4195/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4196/// the provided lvalue, which currently refers to the base object.
4197static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4198 LValue &Result) {
4199 SubobjectDesignator &D = Result.Designator;
4200 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4201 return false;
4202
4203 QualType TargetQT = E->getType();
4204 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4205 TargetQT = PT->getPointeeType();
4206
4207 // Check this cast lands within the final derived-to-base subobject path.
4208 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4209 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4210 << D.MostDerivedType << TargetQT;
4211 return false;
4212 }
4213
4214 // Check the type of the final cast. We don't need to check the path,
4215 // since a cast can only be formed if the path is unique.
4216 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4217 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4218 const CXXRecordDecl *FinalType;
4219 if (NewEntriesSize == D.MostDerivedPathLength)
4220 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4221 else
4222 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4223 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4224 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4225 << D.MostDerivedType << TargetQT;
4226 return false;
4227 }
4228
4229 // Truncate the lvalue to the appropriate derived class.
4230 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4231}
4232
4233/// Get the value to use for a default-initialized object of type T.
4234static APValue getDefaultInitValue(QualType T) {
4235 if (auto *RD = T->getAsCXXRecordDecl()) {
4236 if (RD->isUnion())
4237 return APValue((const FieldDecl*)nullptr);
4238
4239 APValue Struct(APValue::UninitStruct(), RD->getNumBases(),
4240 std::distance(RD->field_begin(), RD->field_end()));
4241
4242 unsigned Index = 0;
4243 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4244 End = RD->bases_end(); I != End; ++I, ++Index)
4245 Struct.getStructBase(Index) = getDefaultInitValue(I->getType());
4246
4247 for (const auto *I : RD->fields()) {
4248 if (I->isUnnamedBitfield())
4249 continue;
4250 Struct.getStructField(I->getFieldIndex()) =
4251 getDefaultInitValue(I->getType());
4252 }
4253 return Struct;
4254 }
4255
4256 if (auto *AT =
4257 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4258 APValue Array(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4259 if (Array.hasArrayFiller())
4260 Array.getArrayFiller() = getDefaultInitValue(AT->getElementType());
4261 return Array;
4262 }
4263
4264 return APValue::IndeterminateValue();
4265}
4266
4267namespace {
4268enum EvalStmtResult {
4269 /// Evaluation failed.
4270 ESR_Failed,
4271 /// Hit a 'return' statement.
4272 ESR_Returned,
4273 /// Evaluation succeeded.
4274 ESR_Succeeded,
4275 /// Hit a 'continue' statement.
4276 ESR_Continue,
4277 /// Hit a 'break' statement.
4278 ESR_Break,
4279 /// Still scanning for 'case' or 'default' statement.
4280 ESR_CaseNotFound
4281};
4282}
4283
4284static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4285 // We don't need to evaluate the initializer for a static local.
4286 if (!VD->hasLocalStorage())
4287 return true;
4288
4289 LValue Result;
4290 APValue &Val =
4291 Info.CurrentCall->createTemporary(VD, VD->getType(), true, Result);
4292
4293 const Expr *InitE = VD->getInit();
4294 if (!InitE) {
4295 Val = getDefaultInitValue(VD->getType());
4296 return true;
4297 }
4298
4299 if (InitE->isValueDependent())
4300 return false;
4301
4302 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4303 // Wipe out any partially-computed value, to allow tracking that this
4304 // evaluation failed.
4305 Val = APValue();
4306 return false;
4307 }
4308
4309 return true;
4310}
4311
4312static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4313 bool OK = true;
4314
4315 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4316 OK &= EvaluateVarDecl(Info, VD);
4317
4318 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4319 for (auto *BD : DD->bindings())
4320 if (auto *VD = BD->getHoldingVar())
4321 OK &= EvaluateDecl(Info, VD);
4322
4323 return OK;
4324}
4325
4326
4327/// Evaluate a condition (either a variable declaration or an expression).
4328static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4329 const Expr *Cond, bool &Result) {
4330 FullExpressionRAII Scope(Info);
4331 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4332 return false;
4333 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4334 return false;
4335 return Scope.destroy();
4336}
4337
4338namespace {
4339/// A location where the result (returned value) of evaluating a
4340/// statement should be stored.
4341struct StmtResult {
4342 /// The APValue that should be filled in with the returned value.
4343 APValue &Value;
4344 /// The location containing the result, if any (used to support RVO).
4345 const LValue *Slot;
4346};
4347
4348struct TempVersionRAII {
4349 CallStackFrame &Frame;
4350
4351 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4352 Frame.pushTempVersion();
4353 }
4354
4355 ~TempVersionRAII() {
4356 Frame.popTempVersion();
4357 }
4358};
4359
4360}
4361
4362static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4363 const Stmt *S,
4364 const SwitchCase *SC = nullptr);
4365
4366/// Evaluate the body of a loop, and translate the result as appropriate.
4367static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4368 const Stmt *Body,
4369 const SwitchCase *Case = nullptr) {
4370 BlockScopeRAII Scope(Info);
4371
4372 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4373 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4374 ESR = ESR_Failed;
4375
4376 switch (ESR) {
4377 case ESR_Break:
4378 return ESR_Succeeded;
4379 case ESR_Succeeded:
4380 case ESR_Continue:
4381 return ESR_Continue;
4382 case ESR_Failed:
4383 case ESR_Returned:
4384 case ESR_CaseNotFound:
4385 return ESR;
4386 }
4387 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4387)
;
4388}
4389
4390/// Evaluate a switch statement.
4391static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4392 const SwitchStmt *SS) {
4393 BlockScopeRAII Scope(Info);
4394
4395 // Evaluate the switch condition.
4396 APSInt Value;
4397 {
4398 if (const Stmt *Init = SS->getInit()) {
4399 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4400 if (ESR != ESR_Succeeded) {
4401 if (ESR != ESR_Failed && !Scope.destroy())
4402 ESR = ESR_Failed;
4403 return ESR;
4404 }
4405 }
4406
4407 FullExpressionRAII CondScope(Info);
4408 if (SS->getConditionVariable() &&
4409 !EvaluateDecl(Info, SS->getConditionVariable()))
4410 return ESR_Failed;
4411 if (!EvaluateInteger(SS->getCond(), Value, Info))
4412 return ESR_Failed;
4413 if (!CondScope.destroy())
4414 return ESR_Failed;
4415 }
4416
4417 // Find the switch case corresponding to the value of the condition.
4418 // FIXME: Cache this lookup.
4419 const SwitchCase *Found = nullptr;
4420 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
4421 SC = SC->getNextSwitchCase()) {
4422 if (isa<DefaultStmt>(SC)) {
4423 Found = SC;
4424 continue;
4425 }
4426
4427 const CaseStmt *CS = cast<CaseStmt>(SC);
4428 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
4429 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
4430 : LHS;
4431 if (LHS <= Value && Value <= RHS) {
4432 Found = SC;
4433 break;
4434 }
4435 }
4436
4437 if (!Found)
4438 return Scope.destroy() ? ESR_Failed : ESR_Succeeded;
4439
4440 // Search the switch body for the switch case and evaluate it from there.
4441 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
4442 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4443 return ESR_Failed;
4444
4445 switch (ESR) {
4446 case ESR_Break:
4447 return ESR_Succeeded;
4448 case ESR_Succeeded:
4449 case ESR_Continue:
4450 case ESR_Failed:
4451 case ESR_Returned:
4452 return ESR;
4453 case ESR_CaseNotFound:
4454 // This can only happen if the switch case is nested within a statement
4455 // expression. We have no intention of supporting that.
4456 Info.FFDiag(Found->getBeginLoc(),
4457 diag::note_constexpr_stmt_expr_unsupported);
4458 return ESR_Failed;
4459 }
4460 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4460)
;
4461}
4462
4463// Evaluate a statement.
4464static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4465 const Stmt *S, const SwitchCase *Case) {
4466 if (!Info.nextStep(S))
4467 return ESR_Failed;
4468
4469 // If we're hunting down a 'case' or 'default' label, recurse through
4470 // substatements until we hit the label.
4471 if (Case) {
4472 switch (S->getStmtClass()) {
4473 case Stmt::CompoundStmtClass:
4474 // FIXME: Precompute which substatement of a compound statement we
4475 // would jump to, and go straight there rather than performing a
4476 // linear scan each time.
4477 case Stmt::LabelStmtClass:
4478 case Stmt::AttributedStmtClass:
4479 case Stmt::DoStmtClass:
4480 break;
4481
4482 case Stmt::CaseStmtClass:
4483 case Stmt::DefaultStmtClass:
4484 if (Case == S)
4485 Case = nullptr;
4486 break;
4487
4488 case Stmt::IfStmtClass: {
4489 // FIXME: Precompute which side of an 'if' we would jump to, and go
4490 // straight there rather than scanning both sides.
4491 const IfStmt *IS = cast<IfStmt>(S);
4492
4493 // Wrap the evaluation in a block scope, in case it's a DeclStmt
4494 // preceded by our switch label.
4495 BlockScopeRAII Scope(Info);
4496
4497 // Step into the init statement in case it brings an (uninitialized)
4498 // variable into scope.
4499 if (const Stmt *Init = IS->getInit()) {
4500 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
4501 if (ESR != ESR_CaseNotFound) {
4502 assert(ESR != ESR_Succeeded)((ESR != ESR_Succeeded) ? static_cast<void> (0) : __assert_fail
("ESR != ESR_Succeeded", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4502, __PRETTY_FUNCTION__))
;
4503 return ESR;
4504 }
4505 }
4506
4507 // Condition variable must be initialized if it exists.
4508 // FIXME: We can skip evaluating the body if there's a condition
4509 // variable, as there can't be any case labels within it.
4510 // (The same is true for 'for' statements.)
4511
4512 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
4513 if (ESR == ESR_Failed)
4514 return ESR;
4515 if (ESR != ESR_CaseNotFound)
4516 return Scope.destroy() ? ESR : ESR_Failed;
4517 if (!IS->getElse())
4518 return ESR_CaseNotFound;
4519
4520 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
4521 if (ESR == ESR_Failed)
4522 return ESR;
4523 if (ESR != ESR_CaseNotFound)
4524 return Scope.destroy() ? ESR : ESR_Failed;
4525 return ESR_CaseNotFound;
4526 }
4527
4528 case Stmt::WhileStmtClass: {
4529 EvalStmtResult ESR =
4530 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
4531 if (ESR != ESR_Continue)
4532 return ESR;
4533 break;
4534 }
4535
4536 case Stmt::ForStmtClass: {
4537 const ForStmt *FS = cast<ForStmt>(S);
4538 BlockScopeRAII Scope(Info);
4539
4540 // Step into the init statement in case it brings an (uninitialized)
4541 // variable into scope.
4542 if (const Stmt *Init = FS->getInit()) {
4543 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
4544 if (ESR != ESR_CaseNotFound) {
4545 assert(ESR != ESR_Succeeded)((ESR != ESR_Succeeded) ? static_cast<void> (0) : __assert_fail
("ESR != ESR_Succeeded", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 4545, __PRETTY_FUNCTION__))
;
4546 return ESR;
4547 }
4548 }
4549
4550 EvalStmtResult ESR =
4551 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
4552 if (ESR != ESR_Continue)
4553 return ESR;
4554 if (FS->getInc()) {
4555 FullExpressionRAII IncScope(Info);
4556 if (!EvaluateIgnoredValue(Info, FS->getInc()) || !IncScope.destroy())
4557 return ESR_Failed;
4558 }
4559 break;
4560 }
4561
4562 case Stmt::DeclStmtClass: {
4563 // Start the lifetime of any uninitialized variables we encounter. They
4564 // might be used by the selected branch of the switch.
4565 const DeclStmt *DS = cast<DeclStmt>(S);
4566 for (const auto *D : DS->decls()) {
4567 if (const auto *VD = dyn_cast<VarDecl>(D)) {
4568 if (VD->hasLocalStorage() && !VD->getInit())
4569 if (!EvaluateVarDecl(Info, VD))
4570 return ESR_Failed;
4571 // FIXME: If the variable has initialization that can't be jumped
4572 // over, bail out of any immediately-surrounding compound-statement
4573 // too. There can't be any case labels here.
4574 }
4575 }
4576 return ESR_CaseNotFound;
4577 }
4578
4579 default:
4580 return ESR_CaseNotFound;
4581 }
4582 }
4583
4584 switch (S->getStmtClass()) {
4585 default:
4586 if (const Expr *E = dyn_cast<Expr>(S)) {
4587 // Don't bother evaluating beyond an expression-statement which couldn't
4588 // be evaluated.
4589 // FIXME: Do we need the FullExpressionRAII object here?
4590 // VisitExprWithCleanups should create one when necessary.
4591 FullExpressionRAII Scope(Info);
4592 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
4593 return ESR_Failed;
4594 return ESR_Succeeded;
4595 }
4596
4597 Info.FFDiag(S->getBeginLoc());
4598 return ESR_Failed;
4599
4600 case Stmt::NullStmtClass:
4601 return ESR_Succeeded;
4602
4603 case Stmt::DeclStmtClass: {
4604 const DeclStmt *DS = cast<DeclStmt>(S);
4605 for (const auto *D : DS->decls()) {
4606 // Each declaration initialization is its own full-expression.
4607 FullExpressionRAII Scope(Info);
4608 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
4609 return ESR_Failed;
4610 if (!Scope.destroy())
4611 return ESR_Failed;
4612 }
4613 return ESR_Succeeded;
4614 }
4615
4616 case Stmt::ReturnStmtClass: {
4617 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
4618 FullExpressionRAII Scope(Info);
4619 if (RetExpr &&
4620 !(Result.Slot
4621 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
4622 : Evaluate(Result.Value, Info, RetExpr)))
4623 return ESR_Failed;
4624 return Scope.destroy() ? ESR_Returned : ESR_Failed;
4625 }
4626
4627 case Stmt::CompoundStmtClass: {
4628 BlockScopeRAII Scope(Info);
4629
4630 const CompoundStmt *CS = cast<CompoundStmt>(S);
4631 for (const auto *BI : CS->body()) {
4632 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
4633 if (ESR == ESR_Succeeded)
4634 Case = nullptr;
4635 else if (ESR != ESR_CaseNotFound) {
4636 if (ESR != ESR_Failed && !Scope.destroy())
4637 return ESR_Failed;
4638 return ESR;
4639 }
4640 }
4641 if (Case)
4642 return ESR_CaseNotFound;
4643 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4644 }
4645
4646 case Stmt::IfStmtClass: {
4647 const IfStmt *IS = cast<IfStmt>(S);
4648
4649 // Evaluate the condition, as either a var decl or as an expression.
4650 BlockScopeRAII Scope(Info);
4651 if (const Stmt *Init = IS->getInit()) {
4652 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4653 if (ESR != ESR_Succeeded) {
4654 if (ESR != ESR_Failed && !Scope.destroy())
4655 return ESR_Failed;
4656 return ESR;
4657 }
4658 }
4659 bool Cond;
4660 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
4661 return ESR_Failed;
4662
4663 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
4664 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
4665 if (ESR != ESR_Succeeded) {
4666 if (ESR != ESR_Failed && !Scope.destroy())
4667 return ESR_Failed;
4668 return ESR;
4669 }
4670 }
4671 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4672 }
4673
4674 case Stmt::WhileStmtClass: {
4675 const WhileStmt *WS = cast<WhileStmt>(S);
4676 while (true) {
4677 BlockScopeRAII Scope(Info);
4678 bool Continue;
4679 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
4680 Continue))
4681 return ESR_Failed;
4682 if (!Continue)
4683 break;
4684
4685 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
4686 if (ESR != ESR_Continue) {
4687 if (ESR != ESR_Failed && !Scope.destroy())
4688 return ESR_Failed;
4689 return ESR;
4690 }
4691 if (!Scope.destroy())
4692 return ESR_Failed;
4693 }
4694 return ESR_Succeeded;
4695 }
4696
4697 case Stmt::DoStmtClass: {
4698 const DoStmt *DS = cast<DoStmt>(S);
4699 bool Continue;
4700 do {
4701 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
4702 if (ESR != ESR_Continue)
4703 return ESR;
4704 Case = nullptr;
4705
4706 FullExpressionRAII CondScope(Info);
4707 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
4708 !CondScope.destroy())
4709 return ESR_Failed;
4710 } while (Continue);
4711 return ESR_Succeeded;
4712 }
4713
4714 case Stmt::ForStmtClass: {
4715 const ForStmt *FS = cast<ForStmt>(S);
4716 BlockScopeRAII ForScope(Info);
4717 if (FS->getInit()) {
4718 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4719 if (ESR != ESR_Succeeded) {
4720 if (ESR != ESR_Failed && !ForScope.destroy())
4721 return ESR_Failed;
4722 return ESR;
4723 }
4724 }
4725 while (true) {
4726 BlockScopeRAII IterScope(Info);
4727 bool Continue = true;
4728 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
4729 FS->getCond(), Continue))
4730 return ESR_Failed;
4731 if (!Continue)
4732 break;
4733
4734 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4735 if (ESR != ESR_Continue) {
4736 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
4737 return ESR_Failed;
4738 return ESR;
4739 }
4740
4741 if (FS->getInc()) {
4742 FullExpressionRAII IncScope(Info);
4743 if (!EvaluateIgnoredValue(Info, FS->getInc()) || !IncScope.destroy())
4744 return ESR_Failed;
4745 }
4746
4747 if (!IterScope.destroy())
4748 return ESR_Failed;
4749 }
4750 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
4751 }
4752
4753 case Stmt::CXXForRangeStmtClass: {
4754 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
4755 BlockScopeRAII Scope(Info);
4756
4757 // Evaluate the init-statement if present.
4758 if (FS->getInit()) {
4759 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4760 if (ESR != ESR_Succeeded) {
4761 if (ESR != ESR_Failed && !Scope.destroy())
4762 return ESR_Failed;
4763 return ESR;
4764 }
4765 }
4766
4767 // Initialize the __range variable.
4768 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
4769 if (ESR != ESR_Succeeded) {
4770 if (ESR != ESR_Failed && !Scope.destroy())
4771 return ESR_Failed;
4772 return ESR;
4773 }
4774
4775 // Create the __begin and __end iterators.
4776 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
4777 if (ESR != ESR_Succeeded) {
4778 if (ESR != ESR_Failed && !Scope.destroy())
4779 return ESR_Failed;
4780 return ESR;
4781 }
4782 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
4783 if (ESR != ESR_Succeeded) {
4784 if (ESR != ESR_Failed && !Scope.destroy())
4785 return ESR_Failed;
4786 return ESR;
4787 }
4788
4789 while (true) {
4790 // Condition: __begin != __end.
4791 {
4792 bool Continue = true;
4793 FullExpressionRAII CondExpr(Info);
4794 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
4795 return ESR_Failed;
4796 if (!Continue)
4797 break;
4798 }
4799
4800 // User's variable declaration, initialized by *__begin.
4801 BlockScopeRAII InnerScope(Info);
4802 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
4803 if (ESR != ESR_Succeeded) {
4804 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
4805 return ESR_Failed;
4806 return ESR;
4807 }
4808
4809 // Loop body.
4810 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4811 if (ESR != ESR_Continue) {
4812 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
4813 return ESR_Failed;
4814 return ESR;
4815 }
4816
4817 // Increment: ++__begin
4818 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4819 return ESR_Failed;
4820
4821 if (!InnerScope.destroy())
4822 return ESR_Failed;
4823 }
4824
4825 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4826 }
4827
4828 case Stmt::SwitchStmtClass:
4829 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
4830
4831 case Stmt::ContinueStmtClass:
4832 return ESR_Continue;
4833
4834 case Stmt::BreakStmtClass:
4835 return ESR_Break;
4836
4837 case Stmt::LabelStmtClass:
4838 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
4839
4840 case Stmt::AttributedStmtClass:
4841 // As a general principle, C++11 attributes can be ignored without
4842 // any semantic impact.
4843 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
4844 Case);
4845
4846 case Stmt::CaseStmtClass:
4847 case Stmt::DefaultStmtClass:
4848 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
4849 case Stmt::CXXTryStmtClass:
4850 // Evaluate try blocks by evaluating all sub statements.
4851 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
4852 }
4853}
4854
4855/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
4856/// default constructor. If so, we'll fold it whether or not it's marked as
4857/// constexpr. If it is marked as constexpr, we will never implicitly define it,
4858/// so we need special handling.
4859static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
4860 const CXXConstructorDecl *CD,
4861 bool IsValueInitialization) {
4862 if (!CD->isTrivial() || !CD->isDefaultConstructor())
4863 return false;
4864
4865 // Value-initialization does not call a trivial default constructor, so such a
4866 // call is a core constant expression whether or not the constructor is
4867 // constexpr.
4868 if (!CD->isConstexpr() && !IsValueInitialization) {
4869 if (Info.getLangOpts().CPlusPlus11) {
4870 // FIXME: If DiagDecl is an implicitly-declared special member function,
4871 // we should be much more explicit about why it's not constexpr.
4872 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
4873 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
4874 Info.Note(CD->getLocation(), diag::note_declared_at);
4875 } else {
4876 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
4877 }
4878 }
4879 return true;
4880}
4881
4882/// CheckConstexprFunction - Check that a function can be called in a constant
4883/// expression.
4884static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
4885 const FunctionDecl *Declaration,
4886 const FunctionDecl *Definition,
4887 const Stmt *Body) {
4888 // Potential constant expressions can contain calls to declared, but not yet
4889 // defined, constexpr functions.
4890 if (Info.checkingPotentialConstantExpression() && !Definition &&
18
Assuming the condition is false
4891 Declaration->isConstexpr())
4892 return false;
4893
4894 // Bail out if the function declaration itself is invalid. We will
4895 // have produced a relevant diagnostic while parsing it, so just
4896 // note the problematic sub-expression.
4897 if (Declaration->isInvalidDecl()) {
19
Assuming the condition is false
20
Taking false branch
4898 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4899 return false;
4900 }
4901
4902 // DR1872: An instantiated virtual constexpr function can't be called in a
4903 // constant expression (prior to C++20). We can still constant-fold such a
4904 // call.
4905 if (!Info.Ctx.getLangOpts().CPlusPlus2a && isa<CXXMethodDecl>(Declaration) &&
21
Assuming field 'CPlusPlus2a' is not equal to 0
4906 cast<CXXMethodDecl>(Declaration)->isVirtual())
4907 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
4908
4909 if (Definition && Definition->isInvalidDecl()) {
22
Assuming 'Definition' is non-null
23
Assuming the condition is false
24
Taking false branch
4910 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4911 return false;
4912 }
4913
4914 // Can we evaluate this function call?
4915 if (Definition
24.1
'Definition' is non-null
24.1
'Definition' is non-null
24.1
'Definition' is non-null
&& Definition->isConstexpr() && Body)
25
Assuming 'Body' is non-null
26
Taking true branch
4916 return true;
4917
4918 if (Info.getLangOpts().CPlusPlus11) {
4919 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
4920
4921 // If this function is not constexpr because it is an inherited
4922 // non-constexpr constructor, diagnose that directly.
4923 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
4924 if (CD && CD->isInheritingConstructor()) {
4925 auto *Inherited = CD->getInheritedConstructor().getConstructor();
4926 if (!Inherited->isConstexpr())
4927 DiagDecl = CD = Inherited;
4928 }
4929
4930 // FIXME: If DiagDecl is an implicitly-declared special member function
4931 // or an inheriting constructor, we should be much more explicit about why
4932 // it's not constexpr.
4933 if (CD && CD->isInheritingConstructor())
4934 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
4935 << CD->getInheritedConstructor().getConstructor()->getParent();
4936 else
4937 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
4938 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
4939 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
4940 } else {
4941 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4942 }
4943 return false;
4944}
4945
4946namespace {
4947struct CheckDynamicTypeHandler {
4948 AccessKinds AccessKind;
4949 typedef bool result_type;
4950 bool failed() { return false; }
4951 bool found(APValue &Subobj, QualType SubobjType) { return true; }
4952 bool found(APSInt &Value, QualType SubobjType) { return true; }
4953 bool found(APFloat &Value, QualType SubobjType) { return true; }
4954};
4955} // end anonymous namespace
4956
4957/// Check that we can access the notional vptr of an object / determine its
4958/// dynamic type.
4959static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
4960 AccessKinds AK, bool Polymorphic) {
4961 if (This.Designator.Invalid)
4962 return false;
4963
4964 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
4965
4966 if (!Obj)
4967 return false;
4968
4969 if (!Obj.Value) {
4970 // The object is not usable in constant expressions, so we can't inspect
4971 // its value to see if it's in-lifetime or what the active union members
4972 // are. We can still check for a one-past-the-end lvalue.
4973 if (This.Designator.isOnePastTheEnd() ||
4974 This.Designator.isMostDerivedAnUnsizedArray()) {
4975 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
4976 ? diag::note_constexpr_access_past_end
4977 : diag::note_constexpr_access_unsized_array)
4978 << AK;
4979 return false;
4980 } else if (Polymorphic) {
4981 // Conservatively refuse to perform a polymorphic operation if we would
4982 // not be able to read a notional 'vptr' value.
4983 APValue Val;
4984 This.moveInto(Val);
4985 QualType StarThisType =
4986 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
4987 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
4988 << AK << Val.getAsString(Info.Ctx, StarThisType);
4989 return false;
4990 }
4991 return true;
4992 }
4993
4994 CheckDynamicTypeHandler Handler{AK};
4995 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
4996}
4997
4998/// Check that the pointee of the 'this' pointer in a member function call is
4999/// either within its lifetime or in its period of construction or destruction.
5000static bool
5001checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5002 const LValue &This,
5003 const CXXMethodDecl *NamedMember) {
5004 return checkDynamicType(
5005 Info, E, This,
5006 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5007}
5008
5009struct DynamicType {
5010 /// The dynamic class type of the object.
5011 const CXXRecordDecl *Type;
5012 /// The corresponding path length in the lvalue.
5013 unsigned PathLength;
5014};
5015
5016static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5017 unsigned PathLength) {
5018 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=((PathLength >= Designator.MostDerivedPathLength &&
PathLength <= Designator.Entries.size() && "invalid path length"
) ? static_cast<void> (0) : __assert_fail ("PathLength >= Designator.MostDerivedPathLength && PathLength <= Designator.Entries.size() && \"invalid path length\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5019, __PRETTY_FUNCTION__))
5019 Designator.Entries.size() && "invalid path length")((PathLength >= Designator.MostDerivedPathLength &&
PathLength <= Designator.Entries.size() && "invalid path length"
) ? static_cast<void> (0) : __assert_fail ("PathLength >= Designator.MostDerivedPathLength && PathLength <= Designator.Entries.size() && \"invalid path length\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5019, __PRETTY_FUNCTION__))
;
5020 return (PathLength == Designator.MostDerivedPathLength)
5021 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5022 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5023}
5024
5025/// Determine the dynamic type of an object.
5026static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E,
5027 LValue &This, AccessKinds AK) {
5028 // If we don't have an lvalue denoting an object of class type, there is no
5029 // meaningful dynamic type. (We consider objects of non-class type to have no
5030 // dynamic type.)
5031 if (!checkDynamicType(Info, E, This, AK, true))
5032 return None;
5033
5034 // Refuse to compute a dynamic type in the presence of virtual bases. This
5035 // shouldn't happen other than in constant-folding situations, since literal
5036 // types can't have virtual bases.
5037 //
5038 // Note that consumers of DynamicType assume that the type has no virtual
5039 // bases, and will need modifications if this restriction is relaxed.
5040 const CXXRecordDecl *Class =
5041 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5042 if (!Class || Class->getNumVBases()) {
5043 Info.FFDiag(E);
5044 return None;
5045 }
5046
5047 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5048 // binary search here instead. But the overwhelmingly common case is that
5049 // we're not in the middle of a constructor, so it probably doesn't matter
5050 // in practice.
5051 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5052 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5053 PathLength <= Path.size(); ++PathLength) {
5054 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5055 Path.slice(0, PathLength))) {
5056 case ConstructionPhase::Bases:
5057 case ConstructionPhase::DestroyingBases:
5058 // We're constructing or destroying a base class. This is not the dynamic
5059 // type.
5060 break;
5061
5062 case ConstructionPhase::None:
5063 case ConstructionPhase::AfterBases:
5064 case ConstructionPhase::Destroying:
5065 // We've finished constructing the base classes and not yet started
5066 // destroying them again, so this is the dynamic type.
5067 return DynamicType{getBaseClassType(This.Designator, PathLength),
5068 PathLength};
5069 }
5070 }
5071
5072 // CWG issue 1517: we're constructing a base class of the object described by
5073 // 'This', so that object has not yet begun its period of construction and
5074 // any polymorphic operation on it results in undefined behavior.
5075 Info.FFDiag(E);
5076 return None;
5077}
5078
5079/// Perform virtual dispatch.
5080static const CXXMethodDecl *HandleVirtualDispatch(
5081 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5082 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5083 Optional<DynamicType> DynType = ComputeDynamicType(
5084 Info, E, This,
5085 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5086 if (!DynType)
5087 return nullptr;
5088
5089 // Find the final overrider. It must be declared in one of the classes on the
5090 // path from the dynamic type to the static type.
5091 // FIXME: If we ever allow literal types to have virtual base classes, that
5092 // won't be true.
5093 const CXXMethodDecl *Callee = Found;
5094 unsigned PathLength = DynType->PathLength;
5095 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5096 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5097 const CXXMethodDecl *Overrider =
5098 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5099 if (Overrider) {
5100 Callee = Overrider;
5101 break;
5102 }
5103 }
5104
5105 // C++2a [class.abstract]p6:
5106 // the effect of making a virtual call to a pure virtual function [...] is
5107 // undefined
5108 if (Callee->isPure()) {
5109 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5110 Info.Note(Callee->getLocation(), diag::note_declared_at);
5111 return nullptr;
5112 }
5113
5114 // If necessary, walk the rest of the path to determine the sequence of
5115 // covariant adjustment steps to apply.
5116 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5117 Found->getReturnType())) {
5118 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5119 for (unsigned CovariantPathLength = PathLength + 1;
5120 CovariantPathLength != This.Designator.Entries.size();
5121 ++CovariantPathLength) {
5122 const CXXRecordDecl *NextClass =
5123 getBaseClassType(This.Designator, CovariantPathLength);
5124 const CXXMethodDecl *Next =
5125 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5126 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5127 Next->getReturnType(), CovariantAdjustmentPath.back()))
5128 CovariantAdjustmentPath.push_back(Next->getReturnType());
5129 }
5130 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5131 CovariantAdjustmentPath.back()))
5132 CovariantAdjustmentPath.push_back(Found->getReturnType());
5133 }
5134
5135 // Perform 'this' adjustment.
5136 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5137 return nullptr;
5138
5139 return Callee;
5140}
5141
5142/// Perform the adjustment from a value returned by a virtual function to
5143/// a value of the statically expected type, which may be a pointer or
5144/// reference to a base class of the returned type.
5145static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5146 APValue &Result,
5147 ArrayRef<QualType> Path) {
5148 assert(Result.isLValue() &&((Result.isLValue() && "unexpected kind of APValue for covariant return"
) ? static_cast<void> (0) : __assert_fail ("Result.isLValue() && \"unexpected kind of APValue for covariant return\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5149, __PRETTY_FUNCTION__))
5149 "unexpected kind of APValue for covariant return")((Result.isLValue() && "unexpected kind of APValue for covariant return"
) ? static_cast<void> (0) : __assert_fail ("Result.isLValue() && \"unexpected kind of APValue for covariant return\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5149, __PRETTY_FUNCTION__))
;
5150 if (Result.isNullPointer())
5151 return true;
5152
5153 LValue LVal;
5154 LVal.setFrom(Info.Ctx, Result);
5155
5156 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5157 for (unsigned I = 1; I != Path.size(); ++I) {
5158 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5159 assert(OldClass && NewClass && "unexpected kind of covariant return")((OldClass && NewClass && "unexpected kind of covariant return"
) ? static_cast<void> (0) : __assert_fail ("OldClass && NewClass && \"unexpected kind of covariant return\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5159, __PRETTY_FUNCTION__))
;
5160 if (OldClass != NewClass &&
5161 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5162 return false;
5163 OldClass = NewClass;
5164 }
5165
5166 LVal.moveInto(Result);
5167 return true;
5168}
5169
5170/// Determine whether \p Base, which is known to be a direct base class of
5171/// \p Derived, is a public base class.
5172static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5173 const CXXRecordDecl *Base) {
5174 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5175 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5176 if (BaseClass && declaresSameEntity(BaseClass, Base))
5177 return BaseSpec.getAccessSpecifier() == AS_public;
5178 }
5179 llvm_unreachable("Base is not a direct base of Derived")::llvm::llvm_unreachable_internal("Base is not a direct base of Derived"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5179)
;
5180}
5181
5182/// Apply the given dynamic cast operation on the provided lvalue.
5183///
5184/// This implements the hard case of dynamic_cast, requiring a "runtime check"
5185/// to find a suitable target subobject.
5186static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5187 LValue &Ptr) {
5188 // We can't do anything with a non-symbolic pointer value.
5189 SubobjectDesignator &D = Ptr.Designator;
5190 if (D.Invalid)
5191 return false;
5192
5193 // C++ [expr.dynamic.cast]p6:
5194 // If v is a null pointer value, the result is a null pointer value.
5195 if (Ptr.isNullPointer() && !E->isGLValue())
5196 return true;
5197
5198 // For all the other cases, we need the pointer to point to an object within
5199 // its lifetime / period of construction / destruction, and we need to know
5200 // its dynamic type.
5201 Optional<DynamicType> DynType =
5202 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5203 if (!DynType)
5204 return false;
5205
5206 // C++ [expr.dynamic.cast]p7:
5207 // If T is "pointer to cv void", then the result is a pointer to the most
5208 // derived object
5209 if (E->getType()->isVoidPointerType())
5210 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5211
5212 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5213 assert(C && "dynamic_cast target is not void pointer nor class")((C && "dynamic_cast target is not void pointer nor class"
) ? static_cast<void> (0) : __assert_fail ("C && \"dynamic_cast target is not void pointer nor class\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5213, __PRETTY_FUNCTION__))
;
5214 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5215
5216 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5217 // C++ [expr.dynamic.cast]p9:
5218 if (!E->isGLValue()) {
5219 // The value of a failed cast to pointer type is the null pointer value
5220 // of the required result type.
5221 Ptr.setNull(Info.Ctx, E->getType());
5222 return true;
5223 }
5224
5225 // A failed cast to reference type throws [...] std::bad_cast.
5226 unsigned DiagKind;
5227 if (!Paths && (declaresSameEntity(DynType->Type, C) ||
5228 DynType->Type->isDerivedFrom(C)))
5229 DiagKind = 0;
5230 else if (!Paths || Paths->begin() == Paths->end())
5231 DiagKind = 1;
5232 else if (Paths->isAmbiguous(CQT))
5233 DiagKind = 2;
5234 else {
5235 assert(Paths->front().Access != AS_public && "why did the cast fail?")((Paths->front().Access != AS_public && "why did the cast fail?"
) ? static_cast<void> (0) : __assert_fail ("Paths->front().Access != AS_public && \"why did the cast fail?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5235, __PRETTY_FUNCTION__))
;
5236 DiagKind = 3;
5237 }
5238 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
5239 << DiagKind << Ptr.Designator.getType(Info.Ctx)
5240 << Info.Ctx.getRecordType(DynType->Type)
5241 << E->getType().getUnqualifiedType();
5242 return false;
5243 };
5244
5245 // Runtime check, phase 1:
5246 // Walk from the base subobject towards the derived object looking for the
5247 // target type.
5248 for (int PathLength = Ptr.Designator.Entries.size();
5249 PathLength >= (int)DynType->PathLength; --PathLength) {
5250 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
5251 if (declaresSameEntity(Class, C))
5252 return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
5253 // We can only walk across public inheritance edges.
5254 if (PathLength > (int)DynType->PathLength &&
5255 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
5256 Class))
5257 return RuntimeCheckFailed(nullptr);
5258 }
5259
5260 // Runtime check, phase 2:
5261 // Search the dynamic type for an unambiguous public base of type C.
5262 CXXBasePaths Paths(/*FindAmbiguities=*/true,
5263 /*RecordPaths=*/true, /*DetectVirtual=*/false);
5264 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
5265 Paths.front().Access == AS_public) {
5266 // Downcast to the dynamic type...
5267 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
5268 return false;
5269 // ... then upcast to the chosen base class subobject.
5270 for (CXXBasePathElement &Elem : Paths.front())
5271 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
5272 return false;
5273 return true;
5274 }
5275
5276 // Otherwise, the runtime check fails.
5277 return RuntimeCheckFailed(&Paths);
5278}
5279
5280namespace {
5281struct StartLifetimeOfUnionMemberHandler {
5282 const FieldDecl *Field;
5283
5284 static const AccessKinds AccessKind = AK_Assign;
5285
5286 typedef bool result_type;
5287 bool failed() { return false; }
5288 bool found(APValue &Subobj, QualType SubobjType) {
5289 // We are supposed to perform no initialization but begin the lifetime of
5290 // the object. We interpret that as meaning to do what default
5291 // initialization of the object would do if all constructors involved were
5292 // trivial:
5293 // * All base, non-variant member, and array element subobjects' lifetimes
5294 // begin
5295 // * No variant members' lifetimes begin
5296 // * All scalar subobjects whose lifetimes begin have indeterminate values
5297 assert(SubobjType->isUnionType())((SubobjType->isUnionType()) ? static_cast<void> (0)
: __assert_fail ("SubobjType->isUnionType()", "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5297, __PRETTY_FUNCTION__))
;
5298 if (!declaresSameEntity(Subobj.getUnionField(), Field) ||
5299 !Subobj.getUnionValue().hasValue())
5300 Subobj.setUnion(Field, getDefaultInitValue(Field->getType()));
5301 return true;
5302 }
5303 bool found(APSInt &Value, QualType SubobjType) {
5304 llvm_unreachable("wrong value kind for union object")::llvm::llvm_unreachable_internal("wrong value kind for union object"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5304)
;
5305 }
5306 bool found(APFloat &Value, QualType SubobjType) {
5307 llvm_unreachable("wrong value kind for union object")::llvm::llvm_unreachable_internal("wrong value kind for union object"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5307)
;
5308 }
5309};
5310} // end anonymous namespace
5311
5312const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
5313
5314/// Handle a builtin simple-assignment or a call to a trivial assignment
5315/// operator whose left-hand side might involve a union member access. If it
5316/// does, implicitly start the lifetime of any accessed union elements per
5317/// C++20 [class.union]5.
5318static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr,
5319 const LValue &LHS) {
5320 if (LHS.InvalidBase || LHS.Designator.Invalid)
63
Assuming field 'InvalidBase' is false
64
Assuming field 'Invalid' is 0
65
Taking false branch
5321 return false;
5322
5323 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
5324 // C++ [class.union]p5:
5325 // define the set S(E) of subexpressions of E as follows:
5326 unsigned PathLength = LHS.Designator.Entries.size();
5327 for (const Expr *E = LHSExpr; E != nullptr;) {
66
Assuming the condition is false
67
Assuming pointer value is null
68
Loop condition is false. Execution continues on line 5381
5328 // -- If E is of the form A.B, S(E) contains the elements of S(A)...
5329 if (auto *ME = dyn_cast<MemberExpr>(E)) {
5330 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
5331 // Note that we can't implicitly start the lifetime of a reference,
5332 // so we don't need to proceed any further if we reach one.
5333 if (!FD || FD->getType()->isReferenceType())
5334 break;
5335
5336 // ... and also contains A.B if B names a union member
5337 if (FD->getParent()->isUnion())
5338 UnionPathLengths.push_back({PathLength - 1, FD});
5339
5340 E = ME->getBase();
5341 --PathLength;
5342 assert(declaresSameEntity(FD,((declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .
getAsBaseOrMember().getPointer())) ? static_cast<void> (
0) : __assert_fail ("declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5344, __PRETTY_FUNCTION__))
5343 LHS.Designator.Entries[PathLength]((declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .
getAsBaseOrMember().getPointer())) ? static_cast<void> (
0) : __assert_fail ("declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5344, __PRETTY_FUNCTION__))
5344 .getAsBaseOrMember().getPointer()))((declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .
getAsBaseOrMember().getPointer())) ? static_cast<void> (
0) : __assert_fail ("declaresSameEntity(FD, LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5344, __PRETTY_FUNCTION__))
;
5345
5346 // -- If E is of the form A[B] and is interpreted as a built-in array
5347 // subscripting operator, S(E) is [S(the array operand, if any)].
5348 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
5349 // Step over an ArrayToPointerDecay implicit cast.
5350 auto *Base = ASE->getBase()->IgnoreImplicit();
5351 if (!Base->getType()->isArrayType())
5352 break;
5353
5354 E = Base;
5355 --PathLength;
5356
5357 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
5358 // Step over a derived-to-base conversion.
5359 E = ICE->getSubExpr();
5360 if (ICE->getCastKind() == CK_NoOp)
5361 continue;
5362 if (ICE->getCastKind() != CK_DerivedToBase &&
5363 ICE->getCastKind() != CK_UncheckedDerivedToBase)
5364 break;
5365 // Walk path backwards as we walk up from the base to the derived class.
5366 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
5367 --PathLength;
5368 (void)Elt;
5369 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),((declaresSameEntity(Elt->getType()->getAsCXXRecordDecl
(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer
())) ? static_cast<void> (0) : __assert_fail ("declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5371, __PRETTY_FUNCTION__))
5370 LHS.Designator.Entries[PathLength]((declaresSameEntity(Elt->getType()->getAsCXXRecordDecl
(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer
())) ? static_cast<void> (0) : __assert_fail ("declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5371, __PRETTY_FUNCTION__))
5371 .getAsBaseOrMember().getPointer()))((declaresSameEntity(Elt->getType()->getAsCXXRecordDecl
(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer
())) ? static_cast<void> (0) : __assert_fail ("declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), LHS.Designator.Entries[PathLength] .getAsBaseOrMember().getPointer())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5371, __PRETTY_FUNCTION__))
;
5372 }
5373
5374 // -- Otherwise, S(E) is empty.
5375 } else {
5376 break;
5377 }
5378 }
5379
5380 // Common case: no unions' lifetimes are started.
5381 if (UnionPathLengths.empty())
69
Calling 'SmallVectorBase::empty'
72
Returning from 'SmallVectorBase::empty'
73
Taking false branch
5382 return true;
5383
5384 // if modification of X [would access an inactive union member], an object
5385 // of the type of X is implicitly created
5386 CompleteObject Obj =
5387 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType());
74
Called C++ object pointer is null
5388 if (!Obj)
5389 return false;
5390 for (std::pair<unsigned, const FieldDecl *> LengthAndField :
5391 llvm::reverse(UnionPathLengths)) {
5392 // Form a designator for the union object.
5393 SubobjectDesignator D = LHS.Designator;
5394 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first);
5395
5396 StartLifetimeOfUnionMemberHandler StartLifetime{LengthAndField.second};
5397 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime))
5398 return false;
5399 }
5400
5401 return true;
5402}
5403
5404/// Determine if a class has any fields that might need to be copied by a
5405/// trivial copy or move operation.
5406static bool hasFields(const CXXRecordDecl *RD) {
5407 if (!RD || RD->isEmpty())
5408 return false;
5409 for (auto *FD : RD->fields()) {
5410 if (FD->isUnnamedBitfield())
5411 continue;
5412 return true;
5413 }
5414 for (auto &Base : RD->bases())
5415 if (hasFields(Base.getType()->getAsCXXRecordDecl()))
5416 return true;
5417 return false;
5418}
5419
5420namespace {
5421typedef SmallVector<APValue, 8> ArgVector;
5422}
5423
5424/// EvaluateArgs - Evaluate the arguments to a function call.
5425static bool EvaluateArgs(ArrayRef<const Expr *> Args, ArgVector &ArgValues,
5426 EvalInfo &Info, const FunctionDecl *Callee) {
5427 bool Success = true;
5428 llvm::SmallBitVector ForbiddenNullArgs;
5429 if (Callee->hasAttr<NonNullAttr>()) {
30
Taking false branch
5430 ForbiddenNullArgs.resize(Args.size());
5431 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
5432 if (!Attr->args_size()) {
5433 ForbiddenNullArgs.set();
5434 break;
5435 } else
5436 for (auto Idx : Attr->args()) {
5437 unsigned ASTIdx = Idx.getASTIndex();
5438 if (ASTIdx >= Args.size())
5439 continue;
5440 ForbiddenNullArgs[ASTIdx] = 1;
5441 }
5442 }
5443 }
5444 for (unsigned Idx = 0; Idx < Args.size(); Idx++) {
31
Assuming the condition is false
32
Loop condition is false. Execution continues on line 5461
5445 if (!Evaluate(ArgValues[Idx], Info, Args[Idx])) {
5446 // If we're checking for a potential constant expression, evaluate all
5447 // initializers even if some of them fail.
5448 if (!Info.noteFailure())
5449 return false;
5450 Success = false;
5451 } else if (!ForbiddenNullArgs.empty() &&
5452 ForbiddenNullArgs[Idx] &&
5453 ArgValues[Idx].isLValue() &&
5454 ArgValues[Idx].isNullPointer()) {
5455 Info.CCEDiag(Args[Idx], diag::note_non_null_attribute_failed);
5456 if (!Info.noteFailure())
5457 return false;
5458 Success = false;
5459 }
5460 }
5461 return Success;
33
Returning the value 1 (loaded from 'Success'), which participates in a condition later
5462}
5463
5464/// Evaluate a function call.
5465static bool HandleFunctionCall(SourceLocation CallLoc,
5466 const FunctionDecl *Callee, const LValue *This,
5467 ArrayRef<const Expr*> Args, const Stmt *Body,
5468 EvalInfo &Info, APValue &Result,
5469 const LValue *ResultSlot) {
5470 ArgVector ArgValues(Args.size());
5471 if (!EvaluateArgs(Args, ArgValues, Info, Callee))
29
Calling 'EvaluateArgs'
34
Returning from 'EvaluateArgs'
35
Taking false branch
5472 return false;
5473
5474 if (!Info.CheckCallLimit(CallLoc))
36
Calling 'EvalInfo::CheckCallLimit'
43
Returning from 'EvalInfo::CheckCallLimit'
44
Taking false branch
5475 return false;
5476
5477 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
5478
5479 // For a trivial copy or move assignment, perform an APValue copy. This is
5480 // essential for unions, where the operations performed by the assignment
5481 // operator cannot be represented as statements.
5482 //
5483 // Skip this for non-union classes with no fields; in that case, the defaulted
5484 // copy/move does not actually read the object.
5485 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
45
Assuming 'Callee' is a 'CXXMethodDecl'
5486 if (MD
45.1
'MD' is non-null
45.1
'MD' is non-null
45.1
'MD' is non-null
&& MD->isDefaulted() &&
46
Assuming the condition is true
53
Taking true branch
5487 (MD->getParent()->isUnion() ||
47
Calling 'TagDecl::isUnion'
50
Returning from 'TagDecl::isUnion'
5488 (MD->isTrivial() && hasFields(MD->getParent())))) {
51
Assuming the condition is true
52
Assuming the condition is true
5489 assert
53.1
'This' is non-null
53.1
'This' is non-null
53.1
'This' is non-null
(This &&((This && (MD->isCopyAssignmentOperator() || MD->
isMoveAssignmentOperator())) ? static_cast<void> (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5490, __PRETTY_FUNCTION__))
54
Assuming the condition is false
55
Assuming the condition is true
56
'?' condition is true
5490 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()))((This && (MD->isCopyAssignmentOperator() || MD->
isMoveAssignmentOperator())) ? static_cast<void> (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5490, __PRETTY_FUNCTION__))
;
5491 LValue RHS;
5492 RHS.setFrom(Info.Ctx, ArgValues[0]);
5493 APValue RHSValue;
5494 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), RHS,
57
Assuming the condition is false
58
Taking false branch
5495 RHSValue, MD->getParent()->isUnion()))
5496 return false;
5497 if (Info.getLangOpts().CPlusPlus2a && MD->isTrivial() &&
59
Assuming field 'CPlusPlus2a' is not equal to 0
60
Assuming the condition is true
5498 !HandleUnionActiveMemberChange(Info, Args[0], *This))
61
Passing value via 2nd parameter 'LHSExpr'
62
Calling 'HandleUnionActiveMemberChange'
5499 return false;
5500 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
5501 RHSValue))
5502 return false;
5503 This->moveInto(Result);
5504 return true;
5505 } else if (MD && isLambdaCallOperator(MD)) {
5506 // We're in a lambda; determine the lambda capture field maps unless we're
5507 // just constexpr checking a lambda's call operator. constexpr checking is
5508 // done before the captures have been added to the closure object (unless
5509 // we're inferring constexpr-ness), so we don't have access to them in this
5510 // case. But since we don't need the captures to constexpr check, we can
5511 // just ignore them.
5512 if (!Info.checkingPotentialConstantExpression())
5513 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
5514 Frame.LambdaThisCaptureField);
5515 }
5516
5517 StmtResult Ret = {Result, ResultSlot};
5518 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
5519 if (ESR == ESR_Succeeded) {
5520 if (Callee->getReturnType()->isVoidType())
5521 return true;
5522 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
5523 }
5524 return ESR == ESR_Returned;
5525}
5526
5527/// Evaluate a constructor call.
5528static bool HandleConstructorCall(const Expr *E, const LValue &This,
5529 APValue *ArgValues,
5530 const CXXConstructorDecl *Definition,
5531 EvalInfo &Info, APValue &Result) {
5532 SourceLocation CallLoc = E->getExprLoc();
5533 if (!Info.CheckCallLimit(CallLoc))
5534 return false;
5535
5536 const CXXRecordDecl *RD = Definition->getParent();
5537 if (RD->getNumVBases()) {
5538 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
5539 return false;
5540 }
5541
5542 EvalInfo::EvaluatingConstructorRAII EvalObj(
5543 Info,
5544 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
5545 RD->getNumBases());
5546 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
5547
5548 // FIXME: Creating an APValue just to hold a nonexistent return value is
5549 // wasteful.
5550 APValue RetVal;
5551 StmtResult Ret = {RetVal, nullptr};
5552
5553 // If it's a delegating constructor, delegate.
5554 if (Definition->isDelegatingConstructor()) {
5555 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
5556 {
5557 FullExpressionRAII InitScope(Info);
5558 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) ||
5559 !InitScope.destroy())
5560 return false;
5561 }
5562 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
5563 }
5564
5565 // For a trivial copy or move constructor, perform an APValue copy. This is
5566 // essential for unions (or classes with anonymous union members), where the
5567 // operations performed by the constructor cannot be represented by
5568 // ctor-initializers.
5569 //
5570 // Skip this for empty non-union classes; we should not perform an
5571 // lvalue-to-rvalue conversion on them because their copy constructor does not
5572 // actually read them.
5573 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
5574 (Definition->getParent()->isUnion() ||
5575 (Definition->isTrivial() && hasFields(Definition->getParent())))) {
5576 LValue RHS;
5577 RHS.setFrom(Info.Ctx, ArgValues[0]);
5578 return handleLValueToRValueConversion(
5579 Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(),
5580 RHS, Result, Definition->getParent()->isUnion());
5581 }
5582
5583 // Reserve space for the struct members.
5584 if (!RD->isUnion() && !Result.hasValue())
5585 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
5586 std::distance(RD->field_begin(), RD->field_end()));
5587
5588 if (RD->isInvalidDecl()) return false;
5589 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
5590
5591 // A scope for temporaries lifetime-extended by reference members.
5592 BlockScopeRAII LifetimeExtendedScope(Info);
5593
5594 bool Success = true;
5595 unsigned BasesSeen = 0;
5596#ifndef NDEBUG
5597 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
5598#endif
5599 CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
5600 auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
5601 // We might be initializing the same field again if this is an indirect
5602 // field initialization.
5603 if (FieldIt == RD->field_end() ||
5604 FieldIt->getFieldIndex() > FD->getFieldIndex()) {
5605 assert(Indirect && "fields out of order?")((Indirect && "fields out of order?") ? static_cast<
void> (0) : __assert_fail ("Indirect && \"fields out of order?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5605, __PRETTY_FUNCTION__))
;
5606 return;
5607 }
5608
5609 // Default-initialize any fields with no explicit initializer.
5610 for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
5611 assert(FieldIt != RD->field_end() && "missing field?")((FieldIt != RD->field_end() && "missing field?") ?
static_cast<void> (0) : __assert_fail ("FieldIt != RD->field_end() && \"missing field?\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5611, __PRETTY_FUNCTION__))
;
5612 if (!FieldIt->isUnnamedBitfield())
5613 Result.getStructField(FieldIt->getFieldIndex()) =
5614 getDefaultInitValue(FieldIt->getType());
5615 }
5616 ++FieldIt;
5617 };
5618 for (const auto *I : Definition->inits()) {
5619 LValue Subobject = This;
5620 LValue SubobjectParent = This;
5621 APValue *Value = &Result;
5622
5623 // Determine the subobject to initialize.
5624 FieldDecl *FD = nullptr;
5625 if (I->isBaseInitializer()) {
5626 QualType BaseType(I->getBaseClass(), 0);
5627#ifndef NDEBUG
5628 // Non-virtual base classes are initialized in the order in the class
5629 // definition. We have already checked for virtual base classes.
5630 assert(!BaseIt->isVirtual() && "virtual base for literal type")((!BaseIt->isVirtual() && "virtual base for literal type"
) ? static_cast<void> (0) : __assert_fail ("!BaseIt->isVirtual() && \"virtual base for literal type\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5630, __PRETTY_FUNCTION__))
;
5631 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&((Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order") ? static_cast
<void> (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5632, __PRETTY_FUNCTION__))
5632 "base class initializers not in expected order")((Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order") ? static_cast
<void> (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5632, __PRETTY_FUNCTION__))
;
5633 ++BaseIt;
5634#endif
5635 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
5636 BaseType->getAsCXXRecordDecl(), &Layout))
5637 return false;
5638 Value = &Result.getStructBase(BasesSeen++);
5639 } else if ((FD = I->getMember())) {
5640 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
5641 return false;
5642 if (RD->isUnion()) {
5643 Result = APValue(FD);
5644 Value = &Result.getUnionValue();
5645 } else {
5646 SkipToField(FD, false);
5647 Value = &Result.getStructField(FD->getFieldIndex());
5648 }
5649 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
5650 // Walk the indirect field decl's chain to find the object to initialize,
5651 // and make sure we've initialized every step along it.
5652 auto IndirectFieldChain = IFD->chain();
5653 for (auto *C : IndirectFieldChain) {
5654 FD = cast<FieldDecl>(C);
5655 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
5656 // Switch the union field if it differs. This happens if we had
5657 // preceding zero-initialization, and we're now initializing a union
5658 // subobject other than the first.
5659 // FIXME: In this case, the values of the other subobjects are
5660 // specified, since zero-initialization sets all padding bits to zero.
5661 if (!Value->hasValue() ||
5662 (Value->isUnion() && Value->getUnionField() != FD)) {
5663 if (CD->isUnion())
5664 *Value = APValue(FD);
5665 else
5666 // FIXME: This immediately starts the lifetime of all members of an
5667 // anonymous struct. It would be preferable to strictly start member
5668 // lifetime in initialization order.
5669 *Value = getDefaultInitValue(Info.Ctx.getRecordType(CD));
5670 }
5671 // Store Subobject as its parent before updating it for the last element
5672 // in the chain.
5673 if (C == IndirectFieldChain.back())
5674 SubobjectParent = Subobject;
5675 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
5676 return false;
5677 if (CD->isUnion())
5678 Value = &Value->getUnionValue();
5679 else {
5680 if (C == IndirectFieldChain.front() && !RD->isUnion())
5681 SkipToField(FD, true);
5682 Value = &Value->getStructField(FD->getFieldIndex());
5683 }
5684 }
5685 } else {
5686 llvm_unreachable("unknown base initializer kind")::llvm::llvm_unreachable_internal("unknown base initializer kind"
, "/build/llvm-toolchain-snapshot-10~svn374814/tools/clang/lib/AST/ExprConstant.cpp"
, 5686)
;
5687 }
5688
5689 // Need to override This for implicit field initializers as in this case
5690 // This refers to innermost anonymous struct/union containing initializer,
5691 // not to currently constructed class.
5692 const Expr *Init = I->getInit();
5693 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
5694 isa<CXXDefaultInitExpr>(Init));
5695 FullExpressionRAII InitScope(Info);
5696 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
5697 (FD && FD->isBitField() &&
5698 !truncateBitfieldValue(Info, Init, *Value, FD))) {
5699 // If we're checking for a potential constant expression, evaluate all
5700 // initializers even if some of them fail.
5701 if (!Info.noteFailure())
5702 return false;
5703 Success = false;
5704 }
5705
5706 // This is the point at which the dynamic type of the object becomes this
5707 // class type.
5708 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
5709 EvalObj.finishedConstructingBases();
5710 }
5711
5712 // Default-initialize any remaining fields.
5713 if (!RD->isUnion()) {
5714 for (; FieldIt != RD->field_end(); ++FieldIt) {
5715 if (!FieldIt->isUnnamedBitfield())
5716 Result.getStructField(FieldIt->getFieldIndex()) =
5717 getDefaultInitValue(FieldIt->getType());
5718 }
5719 }
5720
5721 return Success &&
5722 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed &&
5723 LifetimeExtendedScope.destroy();
5724}
5725
5726static bool HandleConstructorCall(const Expr *E, const LValue &This,
5727 ArrayRef<const Expr*> Args,
5728 const CXXConstructorDecl *Definition,
5729 EvalInfo &Info, APValue &Result) {
5730 ArgVector ArgValues(Args.size());
5731 if (!EvaluateArgs(Args, ArgValues, Info, Definition))
5732 return false;
5733
5734 return HandleConstructorCall(E, This, ArgValues.data(), Definition,
5735 Info, Result);
5736}
5737
5738static bool HandleDestructionImpl(EvalInfo &Info, SourceLocation CallLoc,
5739 const LValue &This, APValue &Value,
5740 QualType T) {
5741 // Objects can only be destroyed while they're within their lifetimes.
5742 // FIXME: We have no representation for whether an object of type nullptr_t
5743 // is in its lifetime; it usually doesn't matter. Perhaps we should model it
5744 // as indeterminate instead?
5745 if (Value.isAbsent() && !T->isNullPtrType()) {
5746 APValue Printable;
5747 This.moveInto(Printable);
5748 Info.FFDiag(CallLoc, diag::note_constexpr_destroy_out_of_lifetime)
5749 << Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
5750 return false;
5751 }
5752
5753 // Invent an expression for location purposes.
5754 // FIXME: We shouldn't need to do this.
5755 OpaqueValueExpr LocE(CallLoc, Info.Ctx.IntTy, VK_RValue);
5756
5757 // For arrays, destroy elements right-to-left.
5758 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
5759 uint64_t Size = CAT->getSize().getZExtValue();
5760 QualTyp