Bug Summary

File:clang/lib/AST/ExprConstant.cpp
Warning:line 3263, column 10
Access to field 'Callee' results in a dereference of a null pointer (loaded from field 'CurrentCall')

Annotated Source Code

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clang -cc1 -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 -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/build-llvm/tools/clang/lib/AST -resource-dir /usr/lib/llvm-13/lib/clang/13.0.0 -D CLANG_ROUND_TRIP_CC1_ARGS=ON -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/include -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/build-llvm/include -I /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/llvm/include -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-13/lib/clang/13.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-07-26-235520-9401-1 -x c++ /build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp

/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/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 "Interp/Context.h"
36#include "Interp/Frame.h"
37#include "Interp/State.h"
38#include "clang/AST/APValue.h"
39#include "clang/AST/ASTContext.h"
40#include "clang/AST/ASTDiagnostic.h"
41#include "clang/AST/ASTLambda.h"
42#include "clang/AST/Attr.h"
43#include "clang/AST/CXXInheritance.h"
44#include "clang/AST/CharUnits.h"
45#include "clang/AST/CurrentSourceLocExprScope.h"
46#include "clang/AST/Expr.h"
47#include "clang/AST/OSLog.h"
48#include "clang/AST/OptionalDiagnostic.h"
49#include "clang/AST/RecordLayout.h"
50#include "clang/AST/StmtVisitor.h"
51#include "clang/AST/TypeLoc.h"
52#include "clang/Basic/Builtins.h"
53#include "clang/Basic/TargetInfo.h"
54#include "llvm/ADT/APFixedPoint.h"
55#include "llvm/ADT/Optional.h"
56#include "llvm/ADT/SmallBitVector.h"
57#include "llvm/Support/Debug.h"
58#include "llvm/Support/SaveAndRestore.h"
59#include "llvm/Support/raw_ostream.h"
60#include <cstring>
61#include <functional>
62
63#define DEBUG_TYPE"exprconstant" "exprconstant"
64
65using namespace clang;
66using llvm::APFixedPoint;
67using llvm::APInt;
68using llvm::APSInt;
69using llvm::APFloat;
70using llvm::FixedPointSemantics;
71using llvm::Optional;
72
73namespace {
74 struct LValue;
75 class CallStackFrame;
76 class EvalInfo;
77
78 using SourceLocExprScopeGuard =
79 CurrentSourceLocExprScope::SourceLocExprScopeGuard;
80
81 static QualType getType(APValue::LValueBase B) {
82 return B.getType();
83 }
84
85 /// Get an LValue path entry, which is known to not be an array index, as a
86 /// field declaration.
87 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
88 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
89 }
90 /// Get an LValue path entry, which is known to not be an array index, as a
91 /// base class declaration.
92 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
93 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
94 }
95 /// Determine whether this LValue path entry for a base class names a virtual
96 /// base class.
97 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
98 return E.getAsBaseOrMember().getInt();
99 }
100
101 /// Given an expression, determine the type used to store the result of
102 /// evaluating that expression.
103 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
104 if (E->isPRValue())
105 return E->getType();
106 return Ctx.getLValueReferenceType(E->getType());
107 }
108
109 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
110 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
111 if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
112 return DirectCallee->getAttr<AllocSizeAttr>();
113 if (const Decl *IndirectCallee = CE->getCalleeDecl())
114 return IndirectCallee->getAttr<AllocSizeAttr>();
115 return nullptr;
116 }
117
118 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
119 /// This will look through a single cast.
120 ///
121 /// Returns null if we couldn't unwrap a function with alloc_size.
122 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
123 if (!E->getType()->isPointerType())
124 return nullptr;
125
126 E = E->IgnoreParens();
127 // If we're doing a variable assignment from e.g. malloc(N), there will
128 // probably be a cast of some kind. In exotic cases, we might also see a
129 // top-level ExprWithCleanups. Ignore them either way.
130 if (const auto *FE = dyn_cast<FullExpr>(E))
131 E = FE->getSubExpr()->IgnoreParens();
132
133 if (const auto *Cast = dyn_cast<CastExpr>(E))
134 E = Cast->getSubExpr()->IgnoreParens();
135
136 if (const auto *CE = dyn_cast<CallExpr>(E))
137 return getAllocSizeAttr(CE) ? CE : nullptr;
138 return nullptr;
139 }
140
141 /// Determines whether or not the given Base contains a call to a function
142 /// with the alloc_size attribute.
143 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
144 const auto *E = Base.dyn_cast<const Expr *>();
145 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
146 }
147
148 /// Determines whether the given kind of constant expression is only ever
149 /// used for name mangling. If so, it's permitted to reference things that we
150 /// can't generate code for (in particular, dllimported functions).
151 static bool isForManglingOnly(ConstantExprKind Kind) {
152 switch (Kind) {
153 case ConstantExprKind::Normal:
154 case ConstantExprKind::ClassTemplateArgument:
155 case ConstantExprKind::ImmediateInvocation:
156 // Note that non-type template arguments of class type are emitted as
157 // template parameter objects.
158 return false;
159
160 case ConstantExprKind::NonClassTemplateArgument:
161 return true;
162 }
163 llvm_unreachable("unknown ConstantExprKind")::llvm::llvm_unreachable_internal("unknown ConstantExprKind",
"/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 163)
;
164 }
165
166 static bool isTemplateArgument(ConstantExprKind Kind) {
167 switch (Kind) {
168 case ConstantExprKind::Normal:
169 case ConstantExprKind::ImmediateInvocation:
170 return false;
171
172 case ConstantExprKind::ClassTemplateArgument:
173 case ConstantExprKind::NonClassTemplateArgument:
174 return true;
175 }
176 llvm_unreachable("unknown ConstantExprKind")::llvm::llvm_unreachable_internal("unknown ConstantExprKind",
"/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 176)
;
177 }
178
179 /// The bound to claim that an array of unknown bound has.
180 /// The value in MostDerivedArraySize is undefined in this case. So, set it
181 /// to an arbitrary value that's likely to loudly break things if it's used.
182 static const uint64_t AssumedSizeForUnsizedArray =
183 std::numeric_limits<uint64_t>::max() / 2;
184
185 /// Determines if an LValue with the given LValueBase will have an unsized
186 /// array in its designator.
187 /// Find the path length and type of the most-derived subobject in the given
188 /// path, and find the size of the containing array, if any.
189 static unsigned
190 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
191 ArrayRef<APValue::LValuePathEntry> Path,
192 uint64_t &ArraySize, QualType &Type, bool &IsArray,
193 bool &FirstEntryIsUnsizedArray) {
194 // This only accepts LValueBases from APValues, and APValues don't support
195 // arrays that lack size info.
196 assert(!isBaseAnAllocSizeCall(Base) &&(static_cast <bool> (!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here") ? void (0) : __assert_fail
("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 197, __extension__ __PRETTY_FUNCTION__))
197 "Unsized arrays shouldn't appear here")(static_cast <bool> (!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here") ? void (0) : __assert_fail
("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 197, __extension__ __PRETTY_FUNCTION__))
;
198 unsigned MostDerivedLength = 0;
199 Type = getType(Base);
200
201 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
202 if (Type->isArrayType()) {
203 const ArrayType *AT = Ctx.getAsArrayType(Type);
204 Type = AT->getElementType();
205 MostDerivedLength = I + 1;
206 IsArray = true;
207
208 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
209 ArraySize = CAT->getSize().getZExtValue();
210 } else {
211 assert(I == 0 && "unexpected unsized array designator")(static_cast <bool> (I == 0 && "unexpected unsized array designator"
) ? void (0) : __assert_fail ("I == 0 && \"unexpected unsized array designator\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 211, __extension__ __PRETTY_FUNCTION__))
;
212 FirstEntryIsUnsizedArray = true;
213 ArraySize = AssumedSizeForUnsizedArray;
214 }
215 } else if (Type->isAnyComplexType()) {
216 const ComplexType *CT = Type->castAs<ComplexType>();
217 Type = CT->getElementType();
218 ArraySize = 2;
219 MostDerivedLength = I + 1;
220 IsArray = true;
221 } else if (const FieldDecl *FD = getAsField(Path[I])) {
222 Type = FD->getType();
223 ArraySize = 0;
224 MostDerivedLength = I + 1;
225 IsArray = false;
226 } else {
227 // Path[I] describes a base class.
228 ArraySize = 0;
229 IsArray = false;
230 }
231 }
232 return MostDerivedLength;
233 }
234
235 /// A path from a glvalue to a subobject of that glvalue.
236 struct SubobjectDesignator {
237 /// True if the subobject was named in a manner not supported by C++11. Such
238 /// lvalues can still be folded, but they are not core constant expressions
239 /// and we cannot perform lvalue-to-rvalue conversions on them.
240 unsigned Invalid : 1;
241
242 /// Is this a pointer one past the end of an object?
243 unsigned IsOnePastTheEnd : 1;
244
245 /// Indicator of whether the first entry is an unsized array.
246 unsigned FirstEntryIsAnUnsizedArray : 1;
247
248 /// Indicator of whether the most-derived object is an array element.
249 unsigned MostDerivedIsArrayElement : 1;
250
251 /// The length of the path to the most-derived object of which this is a
252 /// subobject.
253 unsigned MostDerivedPathLength : 28;
254
255 /// The size of the array of which the most-derived object is an element.
256 /// This will always be 0 if the most-derived object is not an array
257 /// element. 0 is not an indicator of whether or not the most-derived object
258 /// is an array, however, because 0-length arrays are allowed.
259 ///
260 /// If the current array is an unsized array, the value of this is
261 /// undefined.
262 uint64_t MostDerivedArraySize;
263
264 /// The type of the most derived object referred to by this address.
265 QualType MostDerivedType;
266
267 typedef APValue::LValuePathEntry PathEntry;
268
269 /// The entries on the path from the glvalue to the designated subobject.
270 SmallVector<PathEntry, 8> Entries;
271
272 SubobjectDesignator() : Invalid(true) {}
273
274 explicit SubobjectDesignator(QualType T)
275 : Invalid(false), IsOnePastTheEnd(false),
276 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
277 MostDerivedPathLength(0), MostDerivedArraySize(0),
278 MostDerivedType(T) {}
279
280 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
281 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
282 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
283 MostDerivedPathLength(0), MostDerivedArraySize(0) {
284 assert(V.isLValue() && "Non-LValue used to make an LValue designator?")(static_cast <bool> (V.isLValue() && "Non-LValue used to make an LValue designator?"
) ? void (0) : __assert_fail ("V.isLValue() && \"Non-LValue used to make an LValue designator?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 284, __extension__ __PRETTY_FUNCTION__))
;
285 if (!Invalid) {
286 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
287 ArrayRef<PathEntry> VEntries = V.getLValuePath();
288 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
289 if (V.getLValueBase()) {
290 bool IsArray = false;
291 bool FirstIsUnsizedArray = false;
292 MostDerivedPathLength = findMostDerivedSubobject(
293 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
294 MostDerivedType, IsArray, FirstIsUnsizedArray);
295 MostDerivedIsArrayElement = IsArray;
296 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
297 }
298 }
299 }
300
301 void truncate(ASTContext &Ctx, APValue::LValueBase Base,
302 unsigned NewLength) {
303 if (Invalid)
304 return;
305
306 assert(Base && "cannot truncate path for null pointer")(static_cast <bool> (Base && "cannot truncate path for null pointer"
) ? void (0) : __assert_fail ("Base && \"cannot truncate path for null pointer\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 306, __extension__ __PRETTY_FUNCTION__))
;
307 assert(NewLength <= Entries.size() && "not a truncation")(static_cast <bool> (NewLength <= Entries.size() &&
"not a truncation") ? void (0) : __assert_fail ("NewLength <= Entries.size() && \"not a truncation\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 307, __extension__ __PRETTY_FUNCTION__))
;
308
309 if (NewLength == Entries.size())
310 return;
311 Entries.resize(NewLength);
312
313 bool IsArray = false;
314 bool FirstIsUnsizedArray = false;
315 MostDerivedPathLength = findMostDerivedSubobject(
316 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
317 FirstIsUnsizedArray);
318 MostDerivedIsArrayElement = IsArray;
319 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
320 }
321
322 void setInvalid() {
323 Invalid = true;
324 Entries.clear();
325 }
326
327 /// Determine whether the most derived subobject is an array without a
328 /// known bound.
329 bool isMostDerivedAnUnsizedArray() const {
330 assert(!Invalid && "Calling this makes no sense on invalid designators")(static_cast <bool> (!Invalid && "Calling this makes no sense on invalid designators"
) ? void (0) : __assert_fail ("!Invalid && \"Calling this makes no sense on invalid designators\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 330, __extension__ __PRETTY_FUNCTION__))
;
331 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
332 }
333
334 /// Determine what the most derived array's size is. Results in an assertion
335 /// failure if the most derived array lacks a size.
336 uint64_t getMostDerivedArraySize() const {
337 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size")(static_cast <bool> (!isMostDerivedAnUnsizedArray() &&
"Unsized array has no size") ? void (0) : __assert_fail ("!isMostDerivedAnUnsizedArray() && \"Unsized array has no size\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 337, __extension__ __PRETTY_FUNCTION__))
;
338 return MostDerivedArraySize;
339 }
340
341 /// Determine whether this is a one-past-the-end pointer.
342 bool isOnePastTheEnd() const {
343 assert(!Invalid)(static_cast <bool> (!Invalid) ? void (0) : __assert_fail
("!Invalid", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 343, __extension__ __PRETTY_FUNCTION__))
;
344 if (IsOnePastTheEnd)
345 return true;
346 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
347 Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
348 MostDerivedArraySize)
349 return true;
350 return false;
351 }
352
353 /// Get the range of valid index adjustments in the form
354 /// {maximum value that can be subtracted from this pointer,
355 /// maximum value that can be added to this pointer}
356 std::pair<uint64_t, uint64_t> validIndexAdjustments() {
357 if (Invalid || isMostDerivedAnUnsizedArray())
358 return {0, 0};
359
360 // [expr.add]p4: For the purposes of these operators, a pointer to a
361 // nonarray object behaves the same as a pointer to the first element of
362 // an array of length one with the type of the object as its element type.
363 bool IsArray = MostDerivedPathLength == Entries.size() &&
364 MostDerivedIsArrayElement;
365 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
366 : (uint64_t)IsOnePastTheEnd;
367 uint64_t ArraySize =
368 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
369 return {ArrayIndex, ArraySize - ArrayIndex};
370 }
371
372 /// Check that this refers to a valid subobject.
373 bool isValidSubobject() const {
374 if (Invalid)
375 return false;
376 return !isOnePastTheEnd();
377 }
378 /// Check that this refers to a valid subobject, and if not, produce a
379 /// relevant diagnostic and set the designator as invalid.
380 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
381
382 /// Get the type of the designated object.
383 QualType getType(ASTContext &Ctx) const {
384 assert(!Invalid && "invalid designator has no subobject type")(static_cast <bool> (!Invalid && "invalid designator has no subobject type"
) ? void (0) : __assert_fail ("!Invalid && \"invalid designator has no subobject type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 384, __extension__ __PRETTY_FUNCTION__))
;
385 return MostDerivedPathLength == Entries.size()
386 ? MostDerivedType
387 : Ctx.getRecordType(getAsBaseClass(Entries.back()));
388 }
389
390 /// Update this designator to refer to the first element within this array.
391 void addArrayUnchecked(const ConstantArrayType *CAT) {
392 Entries.push_back(PathEntry::ArrayIndex(0));
393
394 // This is a most-derived object.
395 MostDerivedType = CAT->getElementType();
396 MostDerivedIsArrayElement = true;
397 MostDerivedArraySize = CAT->getSize().getZExtValue();
398 MostDerivedPathLength = Entries.size();
399 }
400 /// Update this designator to refer to the first element within the array of
401 /// elements of type T. This is an array of unknown size.
402 void addUnsizedArrayUnchecked(QualType ElemTy) {
403 Entries.push_back(PathEntry::ArrayIndex(0));
404
405 MostDerivedType = ElemTy;
406 MostDerivedIsArrayElement = true;
407 // The value in MostDerivedArraySize is undefined in this case. So, set it
408 // to an arbitrary value that's likely to loudly break things if it's
409 // used.
410 MostDerivedArraySize = AssumedSizeForUnsizedArray;
411 MostDerivedPathLength = Entries.size();
412 }
413 /// Update this designator to refer to the given base or member of this
414 /// object.
415 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
416 Entries.push_back(APValue::BaseOrMemberType(D, Virtual));
417
418 // If this isn't a base class, it's a new most-derived object.
419 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
420 MostDerivedType = FD->getType();
421 MostDerivedIsArrayElement = false;
422 MostDerivedArraySize = 0;
423 MostDerivedPathLength = Entries.size();
424 }
425 }
426 /// Update this designator to refer to the given complex component.
427 void addComplexUnchecked(QualType EltTy, bool Imag) {
428 Entries.push_back(PathEntry::ArrayIndex(Imag));
429
430 // This is technically a most-derived object, though in practice this
431 // is unlikely to matter.
432 MostDerivedType = EltTy;
433 MostDerivedIsArrayElement = true;
434 MostDerivedArraySize = 2;
435 MostDerivedPathLength = Entries.size();
436 }
437 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
438 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
439 const APSInt &N);
440 /// Add N to the address of this subobject.
441 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
442 if (Invalid || !N) return;
443 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
444 if (isMostDerivedAnUnsizedArray()) {
445 diagnoseUnsizedArrayPointerArithmetic(Info, E);
446 // Can't verify -- trust that the user is doing the right thing (or if
447 // not, trust that the caller will catch the bad behavior).
448 // FIXME: Should we reject if this overflows, at least?
449 Entries.back() = PathEntry::ArrayIndex(
450 Entries.back().getAsArrayIndex() + TruncatedN);
451 return;
452 }
453
454 // [expr.add]p4: For the purposes of these operators, a pointer to a
455 // nonarray object behaves the same as a pointer to the first element of
456 // an array of length one with the type of the object as its element type.
457 bool IsArray = MostDerivedPathLength == Entries.size() &&
458 MostDerivedIsArrayElement;
459 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
460 : (uint64_t)IsOnePastTheEnd;
461 uint64_t ArraySize =
462 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
463
464 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
465 // Calculate the actual index in a wide enough type, so we can include
466 // it in the note.
467 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
468 (llvm::APInt&)N += ArrayIndex;
469 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index")(static_cast <bool> (N.ugt(ArraySize) && "bounds check failed for in-bounds index"
) ? void (0) : __assert_fail ("N.ugt(ArraySize) && \"bounds check failed for in-bounds index\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 469, __extension__ __PRETTY_FUNCTION__))
;
470 diagnosePointerArithmetic(Info, E, N);
471 setInvalid();
472 return;
473 }
474
475 ArrayIndex += TruncatedN;
476 assert(ArrayIndex <= ArraySize &&(static_cast <bool> (ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index") ? void (0)
: __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 477, __extension__ __PRETTY_FUNCTION__))
477 "bounds check succeeded for out-of-bounds index")(static_cast <bool> (ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index") ? void (0)
: __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 477, __extension__ __PRETTY_FUNCTION__))
;
478
479 if (IsArray)
480 Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
481 else
482 IsOnePastTheEnd = (ArrayIndex != 0);
483 }
484 };
485
486 /// A scope at the end of which an object can need to be destroyed.
487 enum class ScopeKind {
488 Block,
489 FullExpression,
490 Call
491 };
492
493 /// A reference to a particular call and its arguments.
494 struct CallRef {
495 CallRef() : OrigCallee(), CallIndex(0), Version() {}
496 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
497 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
498
499 explicit operator bool() const { return OrigCallee; }
500
501 /// Get the parameter that the caller initialized, corresponding to the
502 /// given parameter in the callee.
503 const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
504 return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex())
505 : PVD;
506 }
507
508 /// The callee at the point where the arguments were evaluated. This might
509 /// be different from the actual callee (a different redeclaration, or a
510 /// virtual override), but this function's parameters are the ones that
511 /// appear in the parameter map.
512 const FunctionDecl *OrigCallee;
513 /// The call index of the frame that holds the argument values.
514 unsigned CallIndex;
515 /// The version of the parameters corresponding to this call.
516 unsigned Version;
517 };
518
519 /// A stack frame in the constexpr call stack.
520 class CallStackFrame : public interp::Frame {
521 public:
522 EvalInfo &Info;
523
524 /// Parent - The caller of this stack frame.
525 CallStackFrame *Caller;
526
527 /// Callee - The function which was called.
528 const FunctionDecl *Callee;
529
530 /// This - The binding for the this pointer in this call, if any.
531 const LValue *This;
532
533 /// Information on how to find the arguments to this call. Our arguments
534 /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
535 /// key and this value as the version.
536 CallRef Arguments;
537
538 /// Source location information about the default argument or default
539 /// initializer expression we're evaluating, if any.
540 CurrentSourceLocExprScope CurSourceLocExprScope;
541
542 // Note that we intentionally use std::map here so that references to
543 // values are stable.
544 typedef std::pair<const void *, unsigned> MapKeyTy;
545 typedef std::map<MapKeyTy, APValue> MapTy;
546 /// Temporaries - Temporary lvalues materialized within this stack frame.
547 MapTy Temporaries;
548
549 /// CallLoc - The location of the call expression for this call.
550 SourceLocation CallLoc;
551
552 /// Index - The call index of this call.
553 unsigned Index;
554
555 /// The stack of integers for tracking version numbers for temporaries.
556 SmallVector<unsigned, 2> TempVersionStack = {1};
557 unsigned CurTempVersion = TempVersionStack.back();
558
559 unsigned getTempVersion() const { return TempVersionStack.back(); }
560
561 void pushTempVersion() {
562 TempVersionStack.push_back(++CurTempVersion);
563 }
564
565 void popTempVersion() {
566 TempVersionStack.pop_back();
567 }
568
569 CallRef createCall(const FunctionDecl *Callee) {
570 return {Callee, Index, ++CurTempVersion};
571 }
572
573 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
574 // on the overall stack usage of deeply-recursing constexpr evaluations.
575 // (We should cache this map rather than recomputing it repeatedly.)
576 // But let's try this and see how it goes; we can look into caching the map
577 // as a later change.
578
579 /// LambdaCaptureFields - Mapping from captured variables/this to
580 /// corresponding data members in the closure class.
581 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
582 FieldDecl *LambdaThisCaptureField;
583
584 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
585 const FunctionDecl *Callee, const LValue *This,
586 CallRef Arguments);
587 ~CallStackFrame();
588
589 // Return the temporary for Key whose version number is Version.
590 APValue *getTemporary(const void *Key, unsigned Version) {
591 MapKeyTy KV(Key, Version);
592 auto LB = Temporaries.lower_bound(KV);
593 if (LB != Temporaries.end() && LB->first == KV)
594 return &LB->second;
595 // Pair (Key,Version) wasn't found in the map. Check that no elements
596 // in the map have 'Key' as their key.
597 assert((LB == Temporaries.end() || LB->first.first != Key) &&(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 599, __extension__ __PRETTY_FUNCTION__))
598 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 599, __extension__ __PRETTY_FUNCTION__))
599 "Element with key 'Key' found in map")(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 599, __extension__ __PRETTY_FUNCTION__))
;
600 return nullptr;
601 }
602
603 // Return the current temporary for Key in the map.
604 APValue *getCurrentTemporary(const void *Key) {
605 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
606 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
607 return &std::prev(UB)->second;
608 return nullptr;
609 }
610
611 // Return the version number of the current temporary for Key.
612 unsigned getCurrentTemporaryVersion(const void *Key) const {
613 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
614 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
615 return std::prev(UB)->first.second;
616 return 0;
617 }
618
619 /// Allocate storage for an object of type T in this stack frame.
620 /// Populates LV with a handle to the created object. Key identifies
621 /// the temporary within the stack frame, and must not be reused without
622 /// bumping the temporary version number.
623 template<typename KeyT>
624 APValue &createTemporary(const KeyT *Key, QualType T,
625 ScopeKind Scope, LValue &LV);
626
627 /// Allocate storage for a parameter of a function call made in this frame.
628 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
629
630 void describe(llvm::raw_ostream &OS) override;
631
632 Frame *getCaller() const override { return Caller; }
633 SourceLocation getCallLocation() const override { return CallLoc; }
634 const FunctionDecl *getCallee() const override { return Callee; }
635
636 bool isStdFunction() const {
637 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
638 if (DC->isStdNamespace())
639 return true;
640 return false;
641 }
642
643 private:
644 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
645 ScopeKind Scope);
646 };
647
648 /// Temporarily override 'this'.
649 class ThisOverrideRAII {
650 public:
651 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
652 : Frame(Frame), OldThis(Frame.This) {
653 if (Enable)
654 Frame.This = NewThis;
655 }
656 ~ThisOverrideRAII() {
657 Frame.This = OldThis;
658 }
659 private:
660 CallStackFrame &Frame;
661 const LValue *OldThis;
662 };
663}
664
665static bool HandleDestruction(EvalInfo &Info, const Expr *E,
666 const LValue &This, QualType ThisType);
667static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
668 APValue::LValueBase LVBase, APValue &Value,
669 QualType T);
670
671namespace {
672 /// A cleanup, and a flag indicating whether it is lifetime-extended.
673 class Cleanup {
674 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
675 APValue::LValueBase Base;
676 QualType T;
677
678 public:
679 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
680 ScopeKind Scope)
681 : Value(Val, Scope), Base(Base), T(T) {}
682
683 /// Determine whether this cleanup should be performed at the end of the
684 /// given kind of scope.
685 bool isDestroyedAtEndOf(ScopeKind K) const {
686 return (int)Value.getInt() >= (int)K;
687 }
688 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
689 if (RunDestructors) {
690 SourceLocation Loc;
691 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
692 Loc = VD->getLocation();
693 else if (const Expr *E = Base.dyn_cast<const Expr*>())
694 Loc = E->getExprLoc();
695 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
696 }
697 *Value.getPointer() = APValue();
698 return true;
699 }
700
701 bool hasSideEffect() {
702 return T.isDestructedType();
703 }
704 };
705
706 /// A reference to an object whose construction we are currently evaluating.
707 struct ObjectUnderConstruction {
708 APValue::LValueBase Base;
709 ArrayRef<APValue::LValuePathEntry> Path;
710 friend bool operator==(const ObjectUnderConstruction &LHS,
711 const ObjectUnderConstruction &RHS) {
712 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
713 }
714 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
715 return llvm::hash_combine(Obj.Base, Obj.Path);
716 }
717 };
718 enum class ConstructionPhase {
719 None,
720 Bases,
721 AfterBases,
722 AfterFields,
723 Destroying,
724 DestroyingBases
725 };
726}
727
728namespace llvm {
729template<> struct DenseMapInfo<ObjectUnderConstruction> {
730 using Base = DenseMapInfo<APValue::LValueBase>;
731 static ObjectUnderConstruction getEmptyKey() {
732 return {Base::getEmptyKey(), {}}; }
733 static ObjectUnderConstruction getTombstoneKey() {
734 return {Base::getTombstoneKey(), {}};
735 }
736 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
737 return hash_value(Object);
738 }
739 static bool isEqual(const ObjectUnderConstruction &LHS,
740 const ObjectUnderConstruction &RHS) {
741 return LHS == RHS;
742 }
743};
744}
745
746namespace {
747 /// A dynamically-allocated heap object.
748 struct DynAlloc {
749 /// The value of this heap-allocated object.
750 APValue Value;
751 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
752 /// or a CallExpr (the latter is for direct calls to operator new inside
753 /// std::allocator<T>::allocate).
754 const Expr *AllocExpr = nullptr;
755
756 enum Kind {
757 New,
758 ArrayNew,
759 StdAllocator
760 };
761
762 /// Get the kind of the allocation. This must match between allocation
763 /// and deallocation.
764 Kind getKind() const {
765 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
766 return NE->isArray() ? ArrayNew : New;
767 assert(isa<CallExpr>(AllocExpr))(static_cast <bool> (isa<CallExpr>(AllocExpr)) ? void
(0) : __assert_fail ("isa<CallExpr>(AllocExpr)", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 767, __extension__ __PRETTY_FUNCTION__))
;
768 return StdAllocator;
769 }
770 };
771
772 struct DynAllocOrder {
773 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
774 return L.getIndex() < R.getIndex();
775 }
776 };
777
778 /// EvalInfo - This is a private struct used by the evaluator to capture
779 /// information about a subexpression as it is folded. It retains information
780 /// about the AST context, but also maintains information about the folded
781 /// expression.
782 ///
783 /// If an expression could be evaluated, it is still possible it is not a C
784 /// "integer constant expression" or constant expression. If not, this struct
785 /// captures information about how and why not.
786 ///
787 /// One bit of information passed *into* the request for constant folding
788 /// indicates whether the subexpression is "evaluated" or not according to C
789 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
790 /// evaluate the expression regardless of what the RHS is, but C only allows
791 /// certain things in certain situations.
792 class EvalInfo : public interp::State {
793 public:
794 ASTContext &Ctx;
795
796 /// EvalStatus - Contains information about the evaluation.
797 Expr::EvalStatus &EvalStatus;
798
799 /// CurrentCall - The top of the constexpr call stack.
800 CallStackFrame *CurrentCall;
801
802 /// CallStackDepth - The number of calls in the call stack right now.
803 unsigned CallStackDepth;
804
805 /// NextCallIndex - The next call index to assign.
806 unsigned NextCallIndex;
807
808 /// StepsLeft - The remaining number of evaluation steps we're permitted
809 /// to perform. This is essentially a limit for the number of statements
810 /// we will evaluate.
811 unsigned StepsLeft;
812
813 /// Enable the experimental new constant interpreter. If an expression is
814 /// not supported by the interpreter, an error is triggered.
815 bool EnableNewConstInterp;
816
817 /// BottomFrame - The frame in which evaluation started. This must be
818 /// initialized after CurrentCall and CallStackDepth.
819 CallStackFrame BottomFrame;
820
821 /// A stack of values whose lifetimes end at the end of some surrounding
822 /// evaluation frame.
823 llvm::SmallVector<Cleanup, 16> CleanupStack;
824
825 /// EvaluatingDecl - This is the declaration whose initializer is being
826 /// evaluated, if any.
827 APValue::LValueBase EvaluatingDecl;
828
829 enum class EvaluatingDeclKind {
830 None,
831 /// We're evaluating the construction of EvaluatingDecl.
832 Ctor,
833 /// We're evaluating the destruction of EvaluatingDecl.
834 Dtor,
835 };
836 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
837
838 /// EvaluatingDeclValue - This is the value being constructed for the
839 /// declaration whose initializer is being evaluated, if any.
840 APValue *EvaluatingDeclValue;
841
842 /// Set of objects that are currently being constructed.
843 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
844 ObjectsUnderConstruction;
845
846 /// Current heap allocations, along with the location where each was
847 /// allocated. We use std::map here because we need stable addresses
848 /// for the stored APValues.
849 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
850
851 /// The number of heap allocations performed so far in this evaluation.
852 unsigned NumHeapAllocs = 0;
853
854 struct EvaluatingConstructorRAII {
855 EvalInfo &EI;
856 ObjectUnderConstruction Object;
857 bool DidInsert;
858 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
859 bool HasBases)
860 : EI(EI), Object(Object) {
861 DidInsert =
862 EI.ObjectsUnderConstruction
863 .insert({Object, HasBases ? ConstructionPhase::Bases
864 : ConstructionPhase::AfterBases})
865 .second;
866 }
867 void finishedConstructingBases() {
868 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
869 }
870 void finishedConstructingFields() {
871 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
872 }
873 ~EvaluatingConstructorRAII() {
874 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
875 }
876 };
877
878 struct EvaluatingDestructorRAII {
879 EvalInfo &EI;
880 ObjectUnderConstruction Object;
881 bool DidInsert;
882 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
883 : EI(EI), Object(Object) {
884 DidInsert = EI.ObjectsUnderConstruction
885 .insert({Object, ConstructionPhase::Destroying})
886 .second;
887 }
888 void startedDestroyingBases() {
889 EI.ObjectsUnderConstruction[Object] =
890 ConstructionPhase::DestroyingBases;
891 }
892 ~EvaluatingDestructorRAII() {
893 if (DidInsert)
894 EI.ObjectsUnderConstruction.erase(Object);
895 }
896 };
897
898 ConstructionPhase
899 isEvaluatingCtorDtor(APValue::LValueBase Base,
900 ArrayRef<APValue::LValuePathEntry> Path) {
901 return ObjectsUnderConstruction.lookup({Base, Path});
902 }
903
904 /// If we're currently speculatively evaluating, the outermost call stack
905 /// depth at which we can mutate state, otherwise 0.
906 unsigned SpeculativeEvaluationDepth = 0;
907
908 /// The current array initialization index, if we're performing array
909 /// initialization.
910 uint64_t ArrayInitIndex = -1;
911
912 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
913 /// notes attached to it will also be stored, otherwise they will not be.
914 bool HasActiveDiagnostic;
915
916 /// Have we emitted a diagnostic explaining why we couldn't constant
917 /// fold (not just why it's not strictly a constant expression)?
918 bool HasFoldFailureDiagnostic;
919
920 /// Whether or not we're in a context where the front end requires a
921 /// constant value.
922 bool InConstantContext;
923
924 /// Whether we're checking that an expression is a potential constant
925 /// expression. If so, do not fail on constructs that could become constant
926 /// later on (such as a use of an undefined global).
927 bool CheckingPotentialConstantExpression = false;
928
929 /// Whether we're checking for an expression that has undefined behavior.
930 /// If so, we will produce warnings if we encounter an operation that is
931 /// always undefined.
932 ///
933 /// Note that we still need to evaluate the expression normally when this
934 /// is set; this is used when evaluating ICEs in C.
935 bool CheckingForUndefinedBehavior = false;
936
937 enum EvaluationMode {
938 /// Evaluate as a constant expression. Stop if we find that the expression
939 /// is not a constant expression.
940 EM_ConstantExpression,
941
942 /// Evaluate as a constant expression. Stop if we find that the expression
943 /// is not a constant expression. Some expressions can be retried in the
944 /// optimizer if we don't constant fold them here, but in an unevaluated
945 /// context we try to fold them immediately since the optimizer never
946 /// gets a chance to look at it.
947 EM_ConstantExpressionUnevaluated,
948
949 /// Fold the expression to a constant. Stop if we hit a side-effect that
950 /// we can't model.
951 EM_ConstantFold,
952
953 /// Evaluate in any way we know how. Don't worry about side-effects that
954 /// can't be modeled.
955 EM_IgnoreSideEffects,
956 } EvalMode;
957
958 /// Are we checking whether the expression is a potential constant
959 /// expression?
960 bool checkingPotentialConstantExpression() const override {
961 return CheckingPotentialConstantExpression;
962 }
963
964 /// Are we checking an expression for overflow?
965 // FIXME: We should check for any kind of undefined or suspicious behavior
966 // in such constructs, not just overflow.
967 bool checkingForUndefinedBehavior() const override {
968 return CheckingForUndefinedBehavior;
969 }
970
971 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
972 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
973 CallStackDepth(0), NextCallIndex(1),
974 StepsLeft(C.getLangOpts().ConstexprStepLimit),
975 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
976 BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
977 EvaluatingDecl((const ValueDecl *)nullptr),
978 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
979 HasFoldFailureDiagnostic(false), InConstantContext(false),
980 EvalMode(Mode) {}
981
982 ~EvalInfo() {
983 discardCleanups();
984 }
985
986 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
987 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
988 EvaluatingDecl = Base;
989 IsEvaluatingDecl = EDK;
990 EvaluatingDeclValue = &Value;
991 }
992
993 bool CheckCallLimit(SourceLocation Loc) {
994 // Don't perform any constexpr calls (other than the call we're checking)
995 // when checking a potential constant expression.
996 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
997 return false;
998 if (NextCallIndex == 0) {
999 // NextCallIndex has wrapped around.
1000 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1001 return false;
1002 }
1003 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1004 return true;
1005 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1006 << getLangOpts().ConstexprCallDepth;
1007 return false;
1008 }
1009
1010 std::pair<CallStackFrame *, unsigned>
1011 getCallFrameAndDepth(unsigned CallIndex) {
1012 assert(CallIndex && "no call index in getCallFrameAndDepth")(static_cast <bool> (CallIndex && "no call index in getCallFrameAndDepth"
) ? void (0) : __assert_fail ("CallIndex && \"no call index in getCallFrameAndDepth\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1012, __extension__ __PRETTY_FUNCTION__))
;
1013 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
1014 // be null in this loop.
1015 unsigned Depth = CallStackDepth;
1016 CallStackFrame *Frame = CurrentCall;
1017 while (Frame->Index > CallIndex) {
1018 Frame = Frame->Caller;
1019 --Depth;
1020 }
1021 if (Frame->Index == CallIndex)
1022 return {Frame, Depth};
1023 return {nullptr, 0};
1024 }
1025
1026 bool nextStep(const Stmt *S) {
1027 if (!StepsLeft) {
1028 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1029 return false;
1030 }
1031 --StepsLeft;
1032 return true;
1033 }
1034
1035 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1036
1037 Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) {
1038 Optional<DynAlloc*> Result;
1039 auto It = HeapAllocs.find(DA);
1040 if (It != HeapAllocs.end())
1041 Result = &It->second;
1042 return Result;
1043 }
1044
1045 /// Get the allocated storage for the given parameter of the given call.
1046 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1047 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
1048 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
1049 : nullptr;
1050 }
1051
1052 /// Information about a stack frame for std::allocator<T>::[de]allocate.
1053 struct StdAllocatorCaller {
1054 unsigned FrameIndex;
1055 QualType ElemType;
1056 explicit operator bool() const { return FrameIndex != 0; };
1057 };
1058
1059 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1060 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1061 Call = Call->Caller) {
1062 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1063 if (!MD)
1064 continue;
1065 const IdentifierInfo *FnII = MD->getIdentifier();
1066 if (!FnII || !FnII->isStr(FnName))
1067 continue;
1068
1069 const auto *CTSD =
1070 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1071 if (!CTSD)
1072 continue;
1073
1074 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1075 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1076 if (CTSD->isInStdNamespace() && ClassII &&
1077 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1078 TAL[0].getKind() == TemplateArgument::Type)
1079 return {Call->Index, TAL[0].getAsType()};
1080 }
1081
1082 return {};
1083 }
1084
1085 void performLifetimeExtension() {
1086 // Disable the cleanups for lifetime-extended temporaries.
1087 CleanupStack.erase(std::remove_if(CleanupStack.begin(),
1088 CleanupStack.end(),
1089 [](Cleanup &C) {
1090 return !C.isDestroyedAtEndOf(
1091 ScopeKind::FullExpression);
1092 }),
1093 CleanupStack.end());
1094 }
1095
1096 /// Throw away any remaining cleanups at the end of evaluation. If any
1097 /// cleanups would have had a side-effect, note that as an unmodeled
1098 /// side-effect and return false. Otherwise, return true.
1099 bool discardCleanups() {
1100 for (Cleanup &C : CleanupStack) {
1101 if (C.hasSideEffect() && !noteSideEffect()) {
1102 CleanupStack.clear();
1103 return false;
1104 }
1105 }
1106 CleanupStack.clear();
1107 return true;
1108 }
1109
1110 private:
1111 interp::Frame *getCurrentFrame() override { return CurrentCall; }
1112 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1113
1114 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
1115 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1116
1117 void setFoldFailureDiagnostic(bool Flag) override {
1118 HasFoldFailureDiagnostic = Flag;
1119 }
1120
1121 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1122
1123 ASTContext &getCtx() const override { return Ctx; }
1124
1125 // If we have a prior diagnostic, it will be noting that the expression
1126 // isn't a constant expression. This diagnostic is more important,
1127 // unless we require this evaluation to produce a constant expression.
1128 //
1129 // FIXME: We might want to show both diagnostics to the user in
1130 // EM_ConstantFold mode.
1131 bool hasPriorDiagnostic() override {
1132 if (!EvalStatus.Diag->empty()) {
1133 switch (EvalMode) {
1134 case EM_ConstantFold:
1135 case EM_IgnoreSideEffects:
1136 if (!HasFoldFailureDiagnostic)
1137 break;
1138 // We've already failed to fold something. Keep that diagnostic.
1139 LLVM_FALLTHROUGH[[gnu::fallthrough]];
1140 case EM_ConstantExpression:
1141 case EM_ConstantExpressionUnevaluated:
1142 setActiveDiagnostic(false);
1143 return true;
1144 }
1145 }
1146 return false;
1147 }
1148
1149 unsigned getCallStackDepth() override { return CallStackDepth; }
1150
1151 public:
1152 /// Should we continue evaluation after encountering a side-effect that we
1153 /// couldn't model?
1154 bool keepEvaluatingAfterSideEffect() {
1155 switch (EvalMode) {
1156 case EM_IgnoreSideEffects:
1157 return true;
1158
1159 case EM_ConstantExpression:
1160 case EM_ConstantExpressionUnevaluated:
1161 case EM_ConstantFold:
1162 // By default, assume any side effect might be valid in some other
1163 // evaluation of this expression from a different context.
1164 return checkingPotentialConstantExpression() ||
1165 checkingForUndefinedBehavior();
1166 }
1167 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1167)
;
1168 }
1169
1170 /// Note that we have had a side-effect, and determine whether we should
1171 /// keep evaluating.
1172 bool noteSideEffect() {
1173 EvalStatus.HasSideEffects = true;
1174 return keepEvaluatingAfterSideEffect();
1175 }
1176
1177 /// Should we continue evaluation after encountering undefined behavior?
1178 bool keepEvaluatingAfterUndefinedBehavior() {
1179 switch (EvalMode) {
1180 case EM_IgnoreSideEffects:
1181 case EM_ConstantFold:
1182 return true;
1183
1184 case EM_ConstantExpression:
1185 case EM_ConstantExpressionUnevaluated:
1186 return checkingForUndefinedBehavior();
1187 }
1188 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1188)
;
1189 }
1190
1191 /// Note that we hit something that was technically undefined behavior, but
1192 /// that we can evaluate past it (such as signed overflow or floating-point
1193 /// division by zero.)
1194 bool noteUndefinedBehavior() override {
1195 EvalStatus.HasUndefinedBehavior = true;
1196 return keepEvaluatingAfterUndefinedBehavior();
1197 }
1198
1199 /// Should we continue evaluation as much as possible after encountering a
1200 /// construct which can't be reduced to a value?
1201 bool keepEvaluatingAfterFailure() const override {
1202 if (!StepsLeft)
1203 return false;
1204
1205 switch (EvalMode) {
1206 case EM_ConstantExpression:
1207 case EM_ConstantExpressionUnevaluated:
1208 case EM_ConstantFold:
1209 case EM_IgnoreSideEffects:
1210 return checkingPotentialConstantExpression() ||
1211 checkingForUndefinedBehavior();
1212 }
1213 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1213)
;
1214 }
1215
1216 /// Notes that we failed to evaluate an expression that other expressions
1217 /// directly depend on, and determine if we should keep evaluating. This
1218 /// should only be called if we actually intend to keep evaluating.
1219 ///
1220 /// Call noteSideEffect() instead if we may be able to ignore the value that
1221 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1222 ///
1223 /// (Foo(), 1) // use noteSideEffect
1224 /// (Foo() || true) // use noteSideEffect
1225 /// Foo() + 1 // use noteFailure
1226 LLVM_NODISCARD[[clang::warn_unused_result]] bool noteFailure() {
1227 // Failure when evaluating some expression often means there is some
1228 // subexpression whose evaluation was skipped. Therefore, (because we
1229 // don't track whether we skipped an expression when unwinding after an
1230 // evaluation failure) every evaluation failure that bubbles up from a
1231 // subexpression implies that a side-effect has potentially happened. We
1232 // skip setting the HasSideEffects flag to true until we decide to
1233 // continue evaluating after that point, which happens here.
1234 bool KeepGoing = keepEvaluatingAfterFailure();
1235 EvalStatus.HasSideEffects |= KeepGoing;
1236 return KeepGoing;
1237 }
1238
1239 class ArrayInitLoopIndex {
1240 EvalInfo &Info;
1241 uint64_t OuterIndex;
1242
1243 public:
1244 ArrayInitLoopIndex(EvalInfo &Info)
1245 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1246 Info.ArrayInitIndex = 0;
1247 }
1248 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1249
1250 operator uint64_t&() { return Info.ArrayInitIndex; }
1251 };
1252 };
1253
1254 /// Object used to treat all foldable expressions as constant expressions.
1255 struct FoldConstant {
1256 EvalInfo &Info;
1257 bool Enabled;
1258 bool HadNoPriorDiags;
1259 EvalInfo::EvaluationMode OldMode;
1260
1261 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1262 : Info(Info),
1263 Enabled(Enabled),
1264 HadNoPriorDiags(Info.EvalStatus.Diag &&
1265 Info.EvalStatus.Diag->empty() &&
1266 !Info.EvalStatus.HasSideEffects),
1267 OldMode(Info.EvalMode) {
1268 if (Enabled)
1269 Info.EvalMode = EvalInfo::EM_ConstantFold;
1270 }
1271 void keepDiagnostics() { Enabled = false; }
1272 ~FoldConstant() {
1273 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1274 !Info.EvalStatus.HasSideEffects)
1275 Info.EvalStatus.Diag->clear();
1276 Info.EvalMode = OldMode;
1277 }
1278 };
1279
1280 /// RAII object used to set the current evaluation mode to ignore
1281 /// side-effects.
1282 struct IgnoreSideEffectsRAII {
1283 EvalInfo &Info;
1284 EvalInfo::EvaluationMode OldMode;
1285 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1286 : Info(Info), OldMode(Info.EvalMode) {
1287 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1288 }
1289
1290 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1291 };
1292
1293 /// RAII object used to optionally suppress diagnostics and side-effects from
1294 /// a speculative evaluation.
1295 class SpeculativeEvaluationRAII {
1296 EvalInfo *Info = nullptr;
1297 Expr::EvalStatus OldStatus;
1298 unsigned OldSpeculativeEvaluationDepth;
1299
1300 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1301 Info = Other.Info;
1302 OldStatus = Other.OldStatus;
1303 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1304 Other.Info = nullptr;
1305 }
1306
1307 void maybeRestoreState() {
1308 if (!Info)
1309 return;
1310
1311 Info->EvalStatus = OldStatus;
1312 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1313 }
1314
1315 public:
1316 SpeculativeEvaluationRAII() = default;
1317
1318 SpeculativeEvaluationRAII(
1319 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1320 : Info(&Info), OldStatus(Info.EvalStatus),
1321 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1322 Info.EvalStatus.Diag = NewDiag;
1323 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1324 }
1325
1326 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1327 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1328 moveFromAndCancel(std::move(Other));
1329 }
1330
1331 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1332 maybeRestoreState();
1333 moveFromAndCancel(std::move(Other));
1334 return *this;
1335 }
1336
1337 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1338 };
1339
1340 /// RAII object wrapping a full-expression or block scope, and handling
1341 /// the ending of the lifetime of temporaries created within it.
1342 template<ScopeKind Kind>
1343 class ScopeRAII {
1344 EvalInfo &Info;
1345 unsigned OldStackSize;
1346 public:
1347 ScopeRAII(EvalInfo &Info)
1348 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1349 // Push a new temporary version. This is needed to distinguish between
1350 // temporaries created in different iterations of a loop.
1351 Info.CurrentCall->pushTempVersion();
1352 }
1353 bool destroy(bool RunDestructors = true) {
1354 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1355 OldStackSize = -1U;
1356 return OK;
1357 }
1358 ~ScopeRAII() {
1359 if (OldStackSize != -1U)
1360 destroy(false);
1361 // Body moved to a static method to encourage the compiler to inline away
1362 // instances of this class.
1363 Info.CurrentCall->popTempVersion();
1364 }
1365 private:
1366 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1367 unsigned OldStackSize) {
1368 assert(OldStackSize <= Info.CleanupStack.size() &&(static_cast <bool> (OldStackSize <= Info.CleanupStack
.size() && "running cleanups out of order?") ? void (
0) : __assert_fail ("OldStackSize <= Info.CleanupStack.size() && \"running cleanups out of order?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1369, __extension__ __PRETTY_FUNCTION__))
1369 "running cleanups out of order?")(static_cast <bool> (OldStackSize <= Info.CleanupStack
.size() && "running cleanups out of order?") ? void (
0) : __assert_fail ("OldStackSize <= Info.CleanupStack.size() && \"running cleanups out of order?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1369, __extension__ __PRETTY_FUNCTION__))
;
1370
1371 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1372 // for a full-expression scope.
1373 bool Success = true;
1374 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1375 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
1376 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1377 Success = false;
1378 break;
1379 }
1380 }
1381 }
1382
1383 // Compact any retained cleanups.
1384 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1385 if (Kind != ScopeKind::Block)
1386 NewEnd =
1387 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1388 return C.isDestroyedAtEndOf(Kind);
1389 });
1390 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1391 return Success;
1392 }
1393 };
1394 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1395 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1396 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1397}
1398
1399bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1400 CheckSubobjectKind CSK) {
1401 if (Invalid)
1402 return false;
1403 if (isOnePastTheEnd()) {
1404 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1405 << CSK;
1406 setInvalid();
1407 return false;
1408 }
1409 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1410 // must actually be at least one array element; even a VLA cannot have a
1411 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1412 return true;
1413}
1414
1415void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1416 const Expr *E) {
1417 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1418 // Do not set the designator as invalid: we can represent this situation,
1419 // and correct handling of __builtin_object_size requires us to do so.
1420}
1421
1422void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1423 const Expr *E,
1424 const APSInt &N) {
1425 // If we're complaining, we must be able to statically determine the size of
1426 // the most derived array.
1427 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1428 Info.CCEDiag(E, diag::note_constexpr_array_index)
1429 << N << /*array*/ 0
1430 << static_cast<unsigned>(getMostDerivedArraySize());
1431 else
1432 Info.CCEDiag(E, diag::note_constexpr_array_index)
1433 << N << /*non-array*/ 1;
1434 setInvalid();
1435}
1436
1437CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1438 const FunctionDecl *Callee, const LValue *This,
1439 CallRef Call)
1440 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1441 Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1442 Info.CurrentCall = this;
1443 ++Info.CallStackDepth;
1444}
1445
1446CallStackFrame::~CallStackFrame() {
1447 assert(Info.CurrentCall == this && "calls retired out of order")(static_cast <bool> (Info.CurrentCall == this &&
"calls retired out of order") ? void (0) : __assert_fail ("Info.CurrentCall == this && \"calls retired out of order\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1447, __extension__ __PRETTY_FUNCTION__))
;
1448 --Info.CallStackDepth;
1449 Info.CurrentCall = Caller;
1450}
1451
1452static bool isRead(AccessKinds AK) {
1453 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1454}
1455
1456static bool isModification(AccessKinds AK) {
1457 switch (AK) {
1458 case AK_Read:
1459 case AK_ReadObjectRepresentation:
1460 case AK_MemberCall:
1461 case AK_DynamicCast:
1462 case AK_TypeId:
1463 return false;
1464 case AK_Assign:
1465 case AK_Increment:
1466 case AK_Decrement:
1467 case AK_Construct:
1468 case AK_Destroy:
1469 return true;
1470 }
1471 llvm_unreachable("unknown access kind")::llvm::llvm_unreachable_internal("unknown access kind", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1471)
;
1472}
1473
1474static bool isAnyAccess(AccessKinds AK) {
1475 return isRead(AK) || isModification(AK);
1476}
1477
1478/// Is this an access per the C++ definition?
1479static bool isFormalAccess(AccessKinds AK) {
1480 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1481}
1482
1483/// Is this kind of axcess valid on an indeterminate object value?
1484static bool isValidIndeterminateAccess(AccessKinds AK) {
1485 switch (AK) {
1486 case AK_Read:
1487 case AK_Increment:
1488 case AK_Decrement:
1489 // These need the object's value.
1490 return false;
1491
1492 case AK_ReadObjectRepresentation:
1493 case AK_Assign:
1494 case AK_Construct:
1495 case AK_Destroy:
1496 // Construction and destruction don't need the value.
1497 return true;
1498
1499 case AK_MemberCall:
1500 case AK_DynamicCast:
1501 case AK_TypeId:
1502 // These aren't really meaningful on scalars.
1503 return true;
1504 }
1505 llvm_unreachable("unknown access kind")::llvm::llvm_unreachable_internal("unknown access kind", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1505)
;
1506}
1507
1508namespace {
1509 struct ComplexValue {
1510 private:
1511 bool IsInt;
1512
1513 public:
1514 APSInt IntReal, IntImag;
1515 APFloat FloatReal, FloatImag;
1516
1517 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1518
1519 void makeComplexFloat() { IsInt = false; }
1520 bool isComplexFloat() const { return !IsInt; }
1521 APFloat &getComplexFloatReal() { return FloatReal; }
1522 APFloat &getComplexFloatImag() { return FloatImag; }
1523
1524 void makeComplexInt() { IsInt = true; }
1525 bool isComplexInt() const { return IsInt; }
1526 APSInt &getComplexIntReal() { return IntReal; }
1527 APSInt &getComplexIntImag() { return IntImag; }
1528
1529 void moveInto(APValue &v) const {
1530 if (isComplexFloat())
1531 v = APValue(FloatReal, FloatImag);
1532 else
1533 v = APValue(IntReal, IntImag);
1534 }
1535 void setFrom(const APValue &v) {
1536 assert(v.isComplexFloat() || v.isComplexInt())(static_cast <bool> (v.isComplexFloat() || v.isComplexInt
()) ? void (0) : __assert_fail ("v.isComplexFloat() || v.isComplexInt()"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1536, __extension__ __PRETTY_FUNCTION__))
;
1537 if (v.isComplexFloat()) {
1538 makeComplexFloat();
1539 FloatReal = v.getComplexFloatReal();
1540 FloatImag = v.getComplexFloatImag();
1541 } else {
1542 makeComplexInt();
1543 IntReal = v.getComplexIntReal();
1544 IntImag = v.getComplexIntImag();
1545 }
1546 }
1547 };
1548
1549 struct LValue {
1550 APValue::LValueBase Base;
1551 CharUnits Offset;
1552 SubobjectDesignator Designator;
1553 bool IsNullPtr : 1;
1554 bool InvalidBase : 1;
1555
1556 const APValue::LValueBase getLValueBase() const { return Base; }
1557 CharUnits &getLValueOffset() { return Offset; }
1558 const CharUnits &getLValueOffset() const { return Offset; }
1559 SubobjectDesignator &getLValueDesignator() { return Designator; }
1560 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1561 bool isNullPointer() const { return IsNullPtr;}
1562
1563 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1564 unsigned getLValueVersion() const { return Base.getVersion(); }
1565
1566 void moveInto(APValue &V) const {
1567 if (Designator.Invalid)
1568 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1569 else {
1570 assert(!InvalidBase && "APValues can't handle invalid LValue bases")(static_cast <bool> (!InvalidBase && "APValues can't handle invalid LValue bases"
) ? void (0) : __assert_fail ("!InvalidBase && \"APValues can't handle invalid LValue bases\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1570, __extension__ __PRETTY_FUNCTION__))
;
1571 V = APValue(Base, Offset, Designator.Entries,
1572 Designator.IsOnePastTheEnd, IsNullPtr);
1573 }
1574 }
1575 void setFrom(ASTContext &Ctx, const APValue &V) {
1576 assert(V.isLValue() && "Setting LValue from a non-LValue?")(static_cast <bool> (V.isLValue() && "Setting LValue from a non-LValue?"
) ? void (0) : __assert_fail ("V.isLValue() && \"Setting LValue from a non-LValue?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1576, __extension__ __PRETTY_FUNCTION__))
;
1577 Base = V.getLValueBase();
1578 Offset = V.getLValueOffset();
1579 InvalidBase = false;
1580 Designator = SubobjectDesignator(Ctx, V);
1581 IsNullPtr = V.isNullPointer();
1582 }
1583
1584 void set(APValue::LValueBase B, bool BInvalid = false) {
1585#ifndef NDEBUG
1586 // We only allow a few types of invalid bases. Enforce that here.
1587 if (BInvalid) {
1588 const auto *E = B.get<const Expr *>();
1589 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&(static_cast <bool> ((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall
(E)) && "Unexpected type of invalid base") ? void (0)
: __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1590, __extension__ __PRETTY_FUNCTION__))
1590 "Unexpected type of invalid base")(static_cast <bool> ((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall
(E)) && "Unexpected type of invalid base") ? void (0)
: __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1590, __extension__ __PRETTY_FUNCTION__))
;
1591 }
1592#endif
1593
1594 Base = B;
1595 Offset = CharUnits::fromQuantity(0);
1596 InvalidBase = BInvalid;
1597 Designator = SubobjectDesignator(getType(B));
1598 IsNullPtr = false;
1599 }
1600
1601 void setNull(ASTContext &Ctx, QualType PointerTy) {
1602 Base = (const ValueDecl *)nullptr;
1603 Offset =
1604 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
1605 InvalidBase = false;
1606 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1607 IsNullPtr = true;
1608 }
1609
1610 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1611 set(B, true);
1612 }
1613
1614 std::string toString(ASTContext &Ctx, QualType T) const {
1615 APValue Printable;
1616 moveInto(Printable);
1617 return Printable.getAsString(Ctx, T);
1618 }
1619
1620 private:
1621 // Check that this LValue is not based on a null pointer. If it is, produce
1622 // a diagnostic and mark the designator as invalid.
1623 template <typename GenDiagType>
1624 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1625 if (Designator.Invalid)
1626 return false;
1627 if (IsNullPtr) {
1628 GenDiag();
1629 Designator.setInvalid();
1630 return false;
1631 }
1632 return true;
1633 }
1634
1635 public:
1636 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1637 CheckSubobjectKind CSK) {
1638 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1639 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1640 });
1641 }
1642
1643 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1644 AccessKinds AK) {
1645 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1646 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1647 });
1648 }
1649
1650 // Check this LValue refers to an object. If not, set the designator to be
1651 // invalid and emit a diagnostic.
1652 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1653 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1654 Designator.checkSubobject(Info, E, CSK);
1655 }
1656
1657 void addDecl(EvalInfo &Info, const Expr *E,
1658 const Decl *D, bool Virtual = false) {
1659 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1660 Designator.addDeclUnchecked(D, Virtual);
1661 }
1662 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1663 if (!Designator.Entries.empty()) {
1664 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1665 Designator.setInvalid();
1666 return;
1667 }
1668 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1669 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType())(static_cast <bool> (getType(Base)->isPointerType() ||
getType(Base)->isArrayType()) ? void (0) : __assert_fail (
"getType(Base)->isPointerType() || getType(Base)->isArrayType()"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1669, __extension__ __PRETTY_FUNCTION__))
;
1670 Designator.FirstEntryIsAnUnsizedArray = true;
1671 Designator.addUnsizedArrayUnchecked(ElemTy);
1672 }
1673 }
1674 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1675 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1676 Designator.addArrayUnchecked(CAT);
1677 }
1678 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1679 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1680 Designator.addComplexUnchecked(EltTy, Imag);
1681 }
1682 void clearIsNullPointer() {
1683 IsNullPtr = false;
1684 }
1685 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1686 const APSInt &Index, CharUnits ElementSize) {
1687 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1688 // but we're not required to diagnose it and it's valid in C++.)
1689 if (!Index)
1690 return;
1691
1692 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1693 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1694 // offsets.
1695 uint64_t Offset64 = Offset.getQuantity();
1696 uint64_t ElemSize64 = ElementSize.getQuantity();
1697 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1698 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1699
1700 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1701 Designator.adjustIndex(Info, E, Index);
1702 clearIsNullPointer();
1703 }
1704 void adjustOffset(CharUnits N) {
1705 Offset += N;
1706 if (N.getQuantity())
1707 clearIsNullPointer();
1708 }
1709 };
1710
1711 struct MemberPtr {
1712 MemberPtr() {}
1713 explicit MemberPtr(const ValueDecl *Decl) :
1714 DeclAndIsDerivedMember(Decl, false), Path() {}
1715
1716 /// The member or (direct or indirect) field referred to by this member
1717 /// pointer, or 0 if this is a null member pointer.
1718 const ValueDecl *getDecl() const {
1719 return DeclAndIsDerivedMember.getPointer();
1720 }
1721 /// Is this actually a member of some type derived from the relevant class?
1722 bool isDerivedMember() const {
1723 return DeclAndIsDerivedMember.getInt();
1724 }
1725 /// Get the class which the declaration actually lives in.
1726 const CXXRecordDecl *getContainingRecord() const {
1727 return cast<CXXRecordDecl>(
1728 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1729 }
1730
1731 void moveInto(APValue &V) const {
1732 V = APValue(getDecl(), isDerivedMember(), Path);
1733 }
1734 void setFrom(const APValue &V) {
1735 assert(V.isMemberPointer())(static_cast <bool> (V.isMemberPointer()) ? void (0) : __assert_fail
("V.isMemberPointer()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1735, __extension__ __PRETTY_FUNCTION__))
;
1736 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1737 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1738 Path.clear();
1739 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1740 Path.insert(Path.end(), P.begin(), P.end());
1741 }
1742
1743 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1744 /// whether the member is a member of some class derived from the class type
1745 /// of the member pointer.
1746 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1747 /// Path - The path of base/derived classes from the member declaration's
1748 /// class (exclusive) to the class type of the member pointer (inclusive).
1749 SmallVector<const CXXRecordDecl*, 4> Path;
1750
1751 /// Perform a cast towards the class of the Decl (either up or down the
1752 /// hierarchy).
1753 bool castBack(const CXXRecordDecl *Class) {
1754 assert(!Path.empty())(static_cast <bool> (!Path.empty()) ? void (0) : __assert_fail
("!Path.empty()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1754, __extension__ __PRETTY_FUNCTION__))
;
1755 const CXXRecordDecl *Expected;
1756 if (Path.size() >= 2)
1757 Expected = Path[Path.size() - 2];
1758 else
1759 Expected = getContainingRecord();
1760 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1761 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1762 // if B does not contain the original member and is not a base or
1763 // derived class of the class containing the original member, the result
1764 // of the cast is undefined.
1765 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1766 // (D::*). We consider that to be a language defect.
1767 return false;
1768 }
1769 Path.pop_back();
1770 return true;
1771 }
1772 /// Perform a base-to-derived member pointer cast.
1773 bool castToDerived(const CXXRecordDecl *Derived) {
1774 if (!getDecl())
1775 return true;
1776 if (!isDerivedMember()) {
1777 Path.push_back(Derived);
1778 return true;
1779 }
1780 if (!castBack(Derived))
1781 return false;
1782 if (Path.empty())
1783 DeclAndIsDerivedMember.setInt(false);
1784 return true;
1785 }
1786 /// Perform a derived-to-base member pointer cast.
1787 bool castToBase(const CXXRecordDecl *Base) {
1788 if (!getDecl())
1789 return true;
1790 if (Path.empty())
1791 DeclAndIsDerivedMember.setInt(true);
1792 if (isDerivedMember()) {
1793 Path.push_back(Base);
1794 return true;
1795 }
1796 return castBack(Base);
1797 }
1798 };
1799
1800 /// Compare two member pointers, which are assumed to be of the same type.
1801 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1802 if (!LHS.getDecl() || !RHS.getDecl())
1803 return !LHS.getDecl() && !RHS.getDecl();
1804 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1805 return false;
1806 return LHS.Path == RHS.Path;
1807 }
1808}
1809
1810static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1811static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1812 const LValue &This, const Expr *E,
1813 bool AllowNonLiteralTypes = false);
1814static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1815 bool InvalidBaseOK = false);
1816static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1817 bool InvalidBaseOK = false);
1818static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1819 EvalInfo &Info);
1820static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1821static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1822static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1823 EvalInfo &Info);
1824static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1825static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1826static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1827 EvalInfo &Info);
1828static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1829
1830/// Evaluate an integer or fixed point expression into an APResult.
1831static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1832 EvalInfo &Info);
1833
1834/// Evaluate only a fixed point expression into an APResult.
1835static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1836 EvalInfo &Info);
1837
1838//===----------------------------------------------------------------------===//
1839// Misc utilities
1840//===----------------------------------------------------------------------===//
1841
1842/// Negate an APSInt in place, converting it to a signed form if necessary, and
1843/// preserving its value (by extending by up to one bit as needed).
1844static void negateAsSigned(APSInt &Int) {
1845 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1846 Int = Int.extend(Int.getBitWidth() + 1);
1847 Int.setIsSigned(true);
1848 }
1849 Int = -Int;
1850}
1851
1852template<typename KeyT>
1853APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1854 ScopeKind Scope, LValue &LV) {
1855 unsigned Version = getTempVersion();
1856 APValue::LValueBase Base(Key, Index, Version);
1857 LV.set(Base);
1858 return createLocal(Base, Key, T, Scope);
1859}
1860
1861/// Allocate storage for a parameter of a function call made in this frame.
1862APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1863 LValue &LV) {
1864 assert(Args.CallIndex == Index && "creating parameter in wrong frame")(static_cast <bool> (Args.CallIndex == Index &&
"creating parameter in wrong frame") ? void (0) : __assert_fail
("Args.CallIndex == Index && \"creating parameter in wrong frame\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1864, __extension__ __PRETTY_FUNCTION__))
;
1865 APValue::LValueBase Base(PVD, Index, Args.Version);
1866 LV.set(Base);
1867 // We always destroy parameters at the end of the call, even if we'd allow
1868 // them to live to the end of the full-expression at runtime, in order to
1869 // give portable results and match other compilers.
1870 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1871}
1872
1873APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1874 QualType T, ScopeKind Scope) {
1875 assert(Base.getCallIndex() == Index && "lvalue for wrong frame")(static_cast <bool> (Base.getCallIndex() == Index &&
"lvalue for wrong frame") ? void (0) : __assert_fail ("Base.getCallIndex() == Index && \"lvalue for wrong frame\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1875, __extension__ __PRETTY_FUNCTION__))
;
1876 unsigned Version = Base.getVersion();
1877 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1878 assert(Result.isAbsent() && "local created multiple times")(static_cast <bool> (Result.isAbsent() && "local created multiple times"
) ? void (0) : __assert_fail ("Result.isAbsent() && \"local created multiple times\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1878, __extension__ __PRETTY_FUNCTION__))
;
1879
1880 // If we're creating a local immediately in the operand of a speculative
1881 // evaluation, don't register a cleanup to be run outside the speculative
1882 // evaluation context, since we won't actually be able to initialize this
1883 // object.
1884 if (Index <= Info.SpeculativeEvaluationDepth) {
1885 if (T.isDestructedType())
1886 Info.noteSideEffect();
1887 } else {
1888 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1889 }
1890 return Result;
1891}
1892
1893APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1894 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1895 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1896 return nullptr;
1897 }
1898
1899 DynamicAllocLValue DA(NumHeapAllocs++);
1900 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1901 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1902 std::forward_as_tuple(DA), std::tuple<>());
1903 assert(Result.second && "reused a heap alloc index?")(static_cast <bool> (Result.second && "reused a heap alloc index?"
) ? void (0) : __assert_fail ("Result.second && \"reused a heap alloc index?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1903, __extension__ __PRETTY_FUNCTION__))
;
1904 Result.first->second.AllocExpr = E;
1905 return &Result.first->second.Value;
1906}
1907
1908/// Produce a string describing the given constexpr call.
1909void CallStackFrame::describe(raw_ostream &Out) {
1910 unsigned ArgIndex = 0;
1911 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1912 !isa<CXXConstructorDecl>(Callee) &&
1913 cast<CXXMethodDecl>(Callee)->isInstance();
1914
1915 if (!IsMemberCall)
1916 Out << *Callee << '(';
1917
1918 if (This && IsMemberCall) {
1919 APValue Val;
1920 This->moveInto(Val);
1921 Val.printPretty(Out, Info.Ctx,
1922 This->Designator.MostDerivedType);
1923 // FIXME: Add parens around Val if needed.
1924 Out << "->" << *Callee << '(';
1925 IsMemberCall = false;
1926 }
1927
1928 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1929 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1930 if (ArgIndex > (unsigned)IsMemberCall)
1931 Out << ", ";
1932
1933 const ParmVarDecl *Param = *I;
1934 APValue *V = Info.getParamSlot(Arguments, Param);
1935 if (V)
1936 V->printPretty(Out, Info.Ctx, Param->getType());
1937 else
1938 Out << "<...>";
1939
1940 if (ArgIndex == 0 && IsMemberCall)
1941 Out << "->" << *Callee << '(';
1942 }
1943
1944 Out << ')';
1945}
1946
1947/// Evaluate an expression to see if it had side-effects, and discard its
1948/// result.
1949/// \return \c true if the caller should keep evaluating.
1950static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1951 assert(!E->isValueDependent())(static_cast <bool> (!E->isValueDependent()) ? void (
0) : __assert_fail ("!E->isValueDependent()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 1951, __extension__ __PRETTY_FUNCTION__))
;
1952 APValue Scratch;
1953 if (!Evaluate(Scratch, Info, E))
1954 // We don't need the value, but we might have skipped a side effect here.
1955 return Info.noteSideEffect();
1956 return true;
1957}
1958
1959/// Should this call expression be treated as a string literal?
1960static bool IsStringLiteralCall(const CallExpr *E) {
1961 unsigned Builtin = E->getBuiltinCallee();
1962 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1963 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1964}
1965
1966static bool IsGlobalLValue(APValue::LValueBase B) {
1967 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1968 // constant expression of pointer type that evaluates to...
1969
1970 // ... a null pointer value, or a prvalue core constant expression of type
1971 // std::nullptr_t.
1972 if (!B) return true;
1973
1974 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1975 // ... the address of an object with static storage duration,
1976 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1977 return VD->hasGlobalStorage();
1978 if (isa<TemplateParamObjectDecl>(D))
1979 return true;
1980 // ... the address of a function,
1981 // ... the address of a GUID [MS extension],
1982 return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D);
1983 }
1984
1985 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1986 return true;
1987
1988 const Expr *E = B.get<const Expr*>();
1989 switch (E->getStmtClass()) {
1990 default:
1991 return false;
1992 case Expr::CompoundLiteralExprClass: {
1993 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1994 return CLE->isFileScope() && CLE->isLValue();
1995 }
1996 case Expr::MaterializeTemporaryExprClass:
1997 // A materialized temporary might have been lifetime-extended to static
1998 // storage duration.
1999 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2000 // A string literal has static storage duration.
2001 case Expr::StringLiteralClass:
2002 case Expr::PredefinedExprClass:
2003 case Expr::ObjCStringLiteralClass:
2004 case Expr::ObjCEncodeExprClass:
2005 return true;
2006 case Expr::ObjCBoxedExprClass:
2007 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2008 case Expr::CallExprClass:
2009 return IsStringLiteralCall(cast<CallExpr>(E));
2010 // For GCC compatibility, &&label has static storage duration.
2011 case Expr::AddrLabelExprClass:
2012 return true;
2013 // A Block literal expression may be used as the initialization value for
2014 // Block variables at global or local static scope.
2015 case Expr::BlockExprClass:
2016 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2017 case Expr::ImplicitValueInitExprClass:
2018 // FIXME:
2019 // We can never form an lvalue with an implicit value initialization as its
2020 // base through expression evaluation, so these only appear in one case: the
2021 // implicit variable declaration we invent when checking whether a constexpr
2022 // constructor can produce a constant expression. We must assume that such
2023 // an expression might be a global lvalue.
2024 return true;
2025 }
2026}
2027
2028static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2029 return LVal.Base.dyn_cast<const ValueDecl*>();
2030}
2031
2032static bool IsLiteralLValue(const LValue &Value) {
2033 if (Value.getLValueCallIndex())
2034 return false;
2035 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2036 return E && !isa<MaterializeTemporaryExpr>(E);
2037}
2038
2039static bool IsWeakLValue(const LValue &Value) {
2040 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2041 return Decl && Decl->isWeak();
2042}
2043
2044static bool isZeroSized(const LValue &Value) {
2045 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2046 if (Decl && isa<VarDecl>(Decl)) {
2047 QualType Ty = Decl->getType();
2048 if (Ty->isArrayType())
2049 return Ty->isIncompleteType() ||
2050 Decl->getASTContext().getTypeSize(Ty) == 0;
2051 }
2052 return false;
2053}
2054
2055static bool HasSameBase(const LValue &A, const LValue &B) {
2056 if (!A.getLValueBase())
2057 return !B.getLValueBase();
2058 if (!B.getLValueBase())
2059 return false;
2060
2061 if (A.getLValueBase().getOpaqueValue() !=
2062 B.getLValueBase().getOpaqueValue())
2063 return false;
2064
2065 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2066 A.getLValueVersion() == B.getLValueVersion();
2067}
2068
2069static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2070 assert(Base && "no location for a null lvalue")(static_cast <bool> (Base && "no location for a null lvalue"
) ? void (0) : __assert_fail ("Base && \"no location for a null lvalue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2070, __extension__ __PRETTY_FUNCTION__))
;
2071 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2072
2073 // For a parameter, find the corresponding call stack frame (if it still
2074 // exists), and point at the parameter of the function definition we actually
2075 // invoked.
2076 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2077 unsigned Idx = PVD->getFunctionScopeIndex();
2078 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2079 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2080 F->Arguments.Version == Base.getVersion() && F->Callee &&
2081 Idx < F->Callee->getNumParams()) {
2082 VD = F->Callee->getParamDecl(Idx);
2083 break;
2084 }
2085 }
2086 }
2087
2088 if (VD)
2089 Info.Note(VD->getLocation(), diag::note_declared_at);
2090 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2091 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2092 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2093 // FIXME: Produce a note for dangling pointers too.
2094 if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
2095 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2096 diag::note_constexpr_dynamic_alloc_here);
2097 }
2098 // We have no information to show for a typeid(T) object.
2099}
2100
2101enum class CheckEvaluationResultKind {
2102 ConstantExpression,
2103 FullyInitialized,
2104};
2105
2106/// Materialized temporaries that we've already checked to determine if they're
2107/// initializsed by a constant expression.
2108using CheckedTemporaries =
2109 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2110
2111static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2112 EvalInfo &Info, SourceLocation DiagLoc,
2113 QualType Type, const APValue &Value,
2114 ConstantExprKind Kind,
2115 SourceLocation SubobjectLoc,
2116 CheckedTemporaries &CheckedTemps);
2117
2118/// Check that this reference or pointer core constant expression is a valid
2119/// value for an address or reference constant expression. Return true if we
2120/// can fold this expression, whether or not it's a constant expression.
2121static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2122 QualType Type, const LValue &LVal,
2123 ConstantExprKind Kind,
2124 CheckedTemporaries &CheckedTemps) {
2125 bool IsReferenceType = Type->isReferenceType();
2126
2127 APValue::LValueBase Base = LVal.getLValueBase();
2128 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2129
2130 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2131 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2132
2133 // Additional restrictions apply in a template argument. We only enforce the
2134 // C++20 restrictions here; additional syntactic and semantic restrictions
2135 // are applied elsewhere.
2136 if (isTemplateArgument(Kind)) {
2137 int InvalidBaseKind = -1;
2138 StringRef Ident;
2139 if (Base.is<TypeInfoLValue>())
2140 InvalidBaseKind = 0;
2141 else if (isa_and_nonnull<StringLiteral>(BaseE))
2142 InvalidBaseKind = 1;
2143 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2144 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2145 InvalidBaseKind = 2;
2146 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2147 InvalidBaseKind = 3;
2148 Ident = PE->getIdentKindName();
2149 }
2150
2151 if (InvalidBaseKind != -1) {
2152 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2153 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2154 << Ident;
2155 return false;
2156 }
2157 }
2158
2159 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
2160 if (FD->isConsteval()) {
2161 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2162 << !Type->isAnyPointerType();
2163 Info.Note(FD->getLocation(), diag::note_declared_at);
2164 return false;
2165 }
2166 }
2167
2168 // Check that the object is a global. Note that the fake 'this' object we
2169 // manufacture when checking potential constant expressions is conservatively
2170 // assumed to be global here.
2171 if (!IsGlobalLValue(Base)) {
2172 if (Info.getLangOpts().CPlusPlus11) {
2173 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2174 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2175 << IsReferenceType << !Designator.Entries.empty()
2176 << !!VD << VD;
2177
2178 auto *VarD = dyn_cast_or_null<VarDecl>(VD);
2179 if (VarD && VarD->isConstexpr()) {
2180 // Non-static local constexpr variables have unintuitive semantics:
2181 // constexpr int a = 1;
2182 // constexpr const int *p = &a;
2183 // ... is invalid because the address of 'a' is not constant. Suggest
2184 // adding a 'static' in this case.
2185 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2186 << VarD
2187 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2188 } else {
2189 NoteLValueLocation(Info, Base);
2190 }
2191 } else {
2192 Info.FFDiag(Loc);
2193 }
2194 // Don't allow references to temporaries to escape.
2195 return false;
2196 }
2197 assert((Info.checkingPotentialConstantExpression() ||(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2199, __extension__ __PRETTY_FUNCTION__))
2198 LVal.getLValueCallIndex() == 0) &&(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2199, __extension__ __PRETTY_FUNCTION__))
2199 "have call index for global lvalue")(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2199, __extension__ __PRETTY_FUNCTION__))
;
2200
2201 if (Base.is<DynamicAllocLValue>()) {
2202 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2203 << IsReferenceType << !Designator.Entries.empty();
2204 NoteLValueLocation(Info, Base);
2205 return false;
2206 }
2207
2208 if (BaseVD) {
2209 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2210 // Check if this is a thread-local variable.
2211 if (Var->getTLSKind())
2212 // FIXME: Diagnostic!
2213 return false;
2214
2215 // A dllimport variable never acts like a constant, unless we're
2216 // evaluating a value for use only in name mangling.
2217 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2218 // FIXME: Diagnostic!
2219 return false;
2220 }
2221 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2222 // __declspec(dllimport) must be handled very carefully:
2223 // We must never initialize an expression with the thunk in C++.
2224 // Doing otherwise would allow the same id-expression to yield
2225 // different addresses for the same function in different translation
2226 // units. However, this means that we must dynamically initialize the
2227 // expression with the contents of the import address table at runtime.
2228 //
2229 // The C language has no notion of ODR; furthermore, it has no notion of
2230 // dynamic initialization. This means that we are permitted to
2231 // perform initialization with the address of the thunk.
2232 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2233 FD->hasAttr<DLLImportAttr>())
2234 // FIXME: Diagnostic!
2235 return false;
2236 }
2237 } else if (const auto *MTE =
2238 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2239 if (CheckedTemps.insert(MTE).second) {
2240 QualType TempType = getType(Base);
2241 if (TempType.isDestructedType()) {
2242 Info.FFDiag(MTE->getExprLoc(),
2243 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2244 << TempType;
2245 return false;
2246 }
2247
2248 APValue *V = MTE->getOrCreateValue(false);
2249 assert(V && "evasluation result refers to uninitialised temporary")(static_cast <bool> (V && "evasluation result refers to uninitialised temporary"
) ? void (0) : __assert_fail ("V && \"evasluation result refers to uninitialised temporary\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2249, __extension__ __PRETTY_FUNCTION__))
;
2250 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2251 Info, MTE->getExprLoc(), TempType, *V,
2252 Kind, SourceLocation(), CheckedTemps))
2253 return false;
2254 }
2255 }
2256
2257 // Allow address constant expressions to be past-the-end pointers. This is
2258 // an extension: the standard requires them to point to an object.
2259 if (!IsReferenceType)
2260 return true;
2261
2262 // A reference constant expression must refer to an object.
2263 if (!Base) {
2264 // FIXME: diagnostic
2265 Info.CCEDiag(Loc);
2266 return true;
2267 }
2268
2269 // Does this refer one past the end of some object?
2270 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2271 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2272 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2273 NoteLValueLocation(Info, Base);
2274 }
2275
2276 return true;
2277}
2278
2279/// Member pointers are constant expressions unless they point to a
2280/// non-virtual dllimport member function.
2281static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2282 SourceLocation Loc,
2283 QualType Type,
2284 const APValue &Value,
2285 ConstantExprKind Kind) {
2286 const ValueDecl *Member = Value.getMemberPointerDecl();
2287 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2288 if (!FD)
2289 return true;
2290 if (FD->isConsteval()) {
2291 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2292 Info.Note(FD->getLocation(), diag::note_declared_at);
2293 return false;
2294 }
2295 return isForManglingOnly(Kind) || FD->isVirtual() ||
2296 !FD->hasAttr<DLLImportAttr>();
2297}
2298
2299/// Check that this core constant expression is of literal type, and if not,
2300/// produce an appropriate diagnostic.
2301static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2302 const LValue *This = nullptr) {
2303 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
2304 return true;
2305
2306 // C++1y: A constant initializer for an object o [...] may also invoke
2307 // constexpr constructors for o and its subobjects even if those objects
2308 // are of non-literal class types.
2309 //
2310 // C++11 missed this detail for aggregates, so classes like this:
2311 // struct foo_t { union { int i; volatile int j; } u; };
2312 // are not (obviously) initializable like so:
2313 // __attribute__((__require_constant_initialization__))
2314 // static const foo_t x = {{0}};
2315 // because "i" is a subobject with non-literal initialization (due to the
2316 // volatile member of the union). See:
2317 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2318 // Therefore, we use the C++1y behavior.
2319 if (This && Info.EvaluatingDecl == This->getLValueBase())
2320 return true;
2321
2322 // Prvalue constant expressions must be of literal types.
2323 if (Info.getLangOpts().CPlusPlus11)
2324 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2325 << E->getType();
2326 else
2327 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2328 return false;
2329}
2330
2331static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2332 EvalInfo &Info, SourceLocation DiagLoc,
2333 QualType Type, const APValue &Value,
2334 ConstantExprKind Kind,
2335 SourceLocation SubobjectLoc,
2336 CheckedTemporaries &CheckedTemps) {
2337 if (!Value.hasValue()) {
2338 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2339 << true << Type;
2340 if (SubobjectLoc.isValid())
2341 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
2342 return false;
2343 }
2344
2345 // We allow _Atomic(T) to be initialized from anything that T can be
2346 // initialized from.
2347 if (const AtomicType *AT = Type->getAs<AtomicType>())
2348 Type = AT->getValueType();
2349
2350 // Core issue 1454: For a literal constant expression of array or class type,
2351 // each subobject of its value shall have been initialized by a constant
2352 // expression.
2353 if (Value.isArray()) {
2354 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2355 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2356 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2357 Value.getArrayInitializedElt(I), Kind,
2358 SubobjectLoc, CheckedTemps))
2359 return false;
2360 }
2361 if (!Value.hasArrayFiller())
2362 return true;
2363 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2364 Value.getArrayFiller(), Kind, SubobjectLoc,
2365 CheckedTemps);
2366 }
2367 if (Value.isUnion() && Value.getUnionField()) {
2368 return CheckEvaluationResult(
2369 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2370 Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
2371 CheckedTemps);
2372 }
2373 if (Value.isStruct()) {
2374 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2375 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2376 unsigned BaseIndex = 0;
2377 for (const CXXBaseSpecifier &BS : CD->bases()) {
2378 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2379 Value.getStructBase(BaseIndex), Kind,
2380 BS.getBeginLoc(), CheckedTemps))
2381 return false;
2382 ++BaseIndex;
2383 }
2384 }
2385 for (const auto *I : RD->fields()) {
2386 if (I->isUnnamedBitfield())
2387 continue;
2388
2389 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2390 Value.getStructField(I->getFieldIndex()),
2391 Kind, I->getLocation(), CheckedTemps))
2392 return false;
2393 }
2394 }
2395
2396 if (Value.isLValue() &&
2397 CERK == CheckEvaluationResultKind::ConstantExpression) {
2398 LValue LVal;
2399 LVal.setFrom(Info.Ctx, Value);
2400 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2401 CheckedTemps);
2402 }
2403
2404 if (Value.isMemberPointer() &&
2405 CERK == CheckEvaluationResultKind::ConstantExpression)
2406 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2407
2408 // Everything else is fine.
2409 return true;
2410}
2411
2412/// Check that this core constant expression value is a valid value for a
2413/// constant expression. If not, report an appropriate diagnostic. Does not
2414/// check that the expression is of literal type.
2415static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2416 QualType Type, const APValue &Value,
2417 ConstantExprKind Kind) {
2418 // Nothing to check for a constant expression of type 'cv void'.
2419 if (Type->isVoidType())
2420 return true;
2421
2422 CheckedTemporaries CheckedTemps;
2423 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2424 Info, DiagLoc, Type, Value, Kind,
2425 SourceLocation(), CheckedTemps);
2426}
2427
2428/// Check that this evaluated value is fully-initialized and can be loaded by
2429/// an lvalue-to-rvalue conversion.
2430static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2431 QualType Type, const APValue &Value) {
2432 CheckedTemporaries CheckedTemps;
2433 return CheckEvaluationResult(
2434 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2435 ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
2436}
2437
2438/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2439/// "the allocated storage is deallocated within the evaluation".
2440static bool CheckMemoryLeaks(EvalInfo &Info) {
2441 if (!Info.HeapAllocs.empty()) {
2442 // We can still fold to a constant despite a compile-time memory leak,
2443 // so long as the heap allocation isn't referenced in the result (we check
2444 // that in CheckConstantExpression).
2445 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2446 diag::note_constexpr_memory_leak)
2447 << unsigned(Info.HeapAllocs.size() - 1);
2448 }
2449 return true;
2450}
2451
2452static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2453 // A null base expression indicates a null pointer. These are always
2454 // evaluatable, and they are false unless the offset is zero.
2455 if (!Value.getLValueBase()) {
2456 Result = !Value.getLValueOffset().isZero();
2457 return true;
2458 }
2459
2460 // We have a non-null base. These are generally known to be true, but if it's
2461 // a weak declaration it can be null at runtime.
2462 Result = true;
2463 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2464 return !Decl || !Decl->isWeak();
2465}
2466
2467static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2468 switch (Val.getKind()) {
2469 case APValue::None:
2470 case APValue::Indeterminate:
2471 return false;
2472 case APValue::Int:
2473 Result = Val.getInt().getBoolValue();
2474 return true;
2475 case APValue::FixedPoint:
2476 Result = Val.getFixedPoint().getBoolValue();
2477 return true;
2478 case APValue::Float:
2479 Result = !Val.getFloat().isZero();
2480 return true;
2481 case APValue::ComplexInt:
2482 Result = Val.getComplexIntReal().getBoolValue() ||
2483 Val.getComplexIntImag().getBoolValue();
2484 return true;
2485 case APValue::ComplexFloat:
2486 Result = !Val.getComplexFloatReal().isZero() ||
2487 !Val.getComplexFloatImag().isZero();
2488 return true;
2489 case APValue::LValue:
2490 return EvalPointerValueAsBool(Val, Result);
2491 case APValue::MemberPointer:
2492 Result = Val.getMemberPointerDecl();
2493 return true;
2494 case APValue::Vector:
2495 case APValue::Array:
2496 case APValue::Struct:
2497 case APValue::Union:
2498 case APValue::AddrLabelDiff:
2499 return false;
2500 }
2501
2502 llvm_unreachable("unknown APValue kind")::llvm::llvm_unreachable_internal("unknown APValue kind", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2502)
;
2503}
2504
2505static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2506 EvalInfo &Info) {
2507 assert(!E->isValueDependent())(static_cast <bool> (!E->isValueDependent()) ? void (
0) : __assert_fail ("!E->isValueDependent()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2507, __extension__ __PRETTY_FUNCTION__))
;
2508 assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition")(static_cast <bool> (E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition"
) ? void (0) : __assert_fail ("E->isPRValue() && \"missing lvalue-to-rvalue conv in bool condition\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2508, __extension__ __PRETTY_FUNCTION__))
;
2509 APValue Val;
2510 if (!Evaluate(Val, Info, E))
2511 return false;
2512 return HandleConversionToBool(Val, Result);
2513}
2514
2515template<typename T>
2516static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2517 const T &SrcValue, QualType DestType) {
2518 Info.CCEDiag(E, diag::note_constexpr_overflow)
2519 << SrcValue << DestType;
2520 return Info.noteUndefinedBehavior();
2521}
2522
2523static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2524 QualType SrcType, const APFloat &Value,
2525 QualType DestType, APSInt &Result) {
2526 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2527 // Determine whether we are converting to unsigned or signed.
2528 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2529
2530 Result = APSInt(DestWidth, !DestSigned);
2531 bool ignored;
2532 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2533 & APFloat::opInvalidOp)
2534 return HandleOverflow(Info, E, Value, DestType);
2535 return true;
2536}
2537
2538/// Get rounding mode used for evaluation of the specified expression.
2539/// \param[out] DynamicRM Is set to true is the requested rounding mode is
2540/// dynamic.
2541/// If rounding mode is unknown at compile time, still try to evaluate the
2542/// expression. If the result is exact, it does not depend on rounding mode.
2543/// So return "tonearest" mode instead of "dynamic".
2544static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E,
2545 bool &DynamicRM) {
2546 llvm::RoundingMode RM =
2547 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2548 DynamicRM = (RM == llvm::RoundingMode::Dynamic);
2549 if (DynamicRM)
2550 RM = llvm::RoundingMode::NearestTiesToEven;
2551 return RM;
2552}
2553
2554/// Check if the given evaluation result is allowed for constant evaluation.
2555static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2556 APFloat::opStatus St) {
2557 // In a constant context, assume that any dynamic rounding mode or FP
2558 // exception state matches the default floating-point environment.
2559 if (Info.InConstantContext)
2560 return true;
2561
2562 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2563 if ((St & APFloat::opInexact) &&
2564 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2565 // Inexact result means that it depends on rounding mode. If the requested
2566 // mode is dynamic, the evaluation cannot be made in compile time.
2567 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2568 return false;
2569 }
2570
2571 if ((St != APFloat::opOK) &&
2572 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2573 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore ||
2574 FPO.getAllowFEnvAccess())) {
2575 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2576 return false;
2577 }
2578
2579 if ((St & APFloat::opStatus::opInvalidOp) &&
2580 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) {
2581 // There is no usefully definable result.
2582 Info.FFDiag(E);
2583 return false;
2584 }
2585
2586 // FIXME: if:
2587 // - evaluation triggered other FP exception, and
2588 // - exception mode is not "ignore", and
2589 // - the expression being evaluated is not a part of global variable
2590 // initializer,
2591 // the evaluation probably need to be rejected.
2592 return true;
2593}
2594
2595static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2596 QualType SrcType, QualType DestType,
2597 APFloat &Result) {
2598 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E))(static_cast <bool> (isa<CastExpr>(E) || isa<CompoundAssignOperator
>(E)) ? void (0) : __assert_fail ("isa<CastExpr>(E) || isa<CompoundAssignOperator>(E)"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2598, __extension__ __PRETTY_FUNCTION__))
;
2599 bool DynamicRM;
2600 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2601 APFloat::opStatus St;
2602 APFloat Value = Result;
2603 bool ignored;
2604 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2605 return checkFloatingPointResult(Info, E, St);
2606}
2607
2608static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2609 QualType DestType, QualType SrcType,
2610 const APSInt &Value) {
2611 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2612 // Figure out if this is a truncate, extend or noop cast.
2613 // If the input is signed, do a sign extend, noop, or truncate.
2614 APSInt Result = Value.extOrTrunc(DestWidth);
2615 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2616 if (DestType->isBooleanType())
2617 Result = Value.getBoolValue();
2618 return Result;
2619}
2620
2621static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2622 const FPOptions FPO,
2623 QualType SrcType, const APSInt &Value,
2624 QualType DestType, APFloat &Result) {
2625 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2626 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
2627 APFloat::rmNearestTiesToEven);
2628 if (!Info.InConstantContext && St != llvm::APFloatBase::opOK &&
2629 FPO.isFPConstrained()) {
2630 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2631 return false;
2632 }
2633 return true;
2634}
2635
2636static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2637 APValue &Value, const FieldDecl *FD) {
2638 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield")(static_cast <bool> (FD->isBitField() && "truncateBitfieldValue on non-bitfield"
) ? void (0) : __assert_fail ("FD->isBitField() && \"truncateBitfieldValue on non-bitfield\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2638, __extension__ __PRETTY_FUNCTION__))
;
2639
2640 if (!Value.isInt()) {
2641 // Trying to store a pointer-cast-to-integer into a bitfield.
2642 // FIXME: In this case, we should provide the diagnostic for casting
2643 // a pointer to an integer.
2644 assert(Value.isLValue() && "integral value neither int nor lvalue?")(static_cast <bool> (Value.isLValue() && "integral value neither int nor lvalue?"
) ? void (0) : __assert_fail ("Value.isLValue() && \"integral value neither int nor lvalue?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2644, __extension__ __PRETTY_FUNCTION__))
;
2645 Info.FFDiag(E);
2646 return false;
2647 }
2648
2649 APSInt &Int = Value.getInt();
2650 unsigned OldBitWidth = Int.getBitWidth();
2651 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2652 if (NewBitWidth < OldBitWidth)
2653 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2654 return true;
2655}
2656
2657static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2658 llvm::APInt &Res) {
2659 APValue SVal;
2660 if (!Evaluate(SVal, Info, E))
2661 return false;
2662 if (SVal.isInt()) {
2663 Res = SVal.getInt();
2664 return true;
2665 }
2666 if (SVal.isFloat()) {
2667 Res = SVal.getFloat().bitcastToAPInt();
2668 return true;
2669 }
2670 if (SVal.isVector()) {
2671 QualType VecTy = E->getType();
2672 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2673 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2674 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2675 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2676 Res = llvm::APInt::getNullValue(VecSize);
2677 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2678 APValue &Elt = SVal.getVectorElt(i);
2679 llvm::APInt EltAsInt;
2680 if (Elt.isInt()) {
2681 EltAsInt = Elt.getInt();
2682 } else if (Elt.isFloat()) {
2683 EltAsInt = Elt.getFloat().bitcastToAPInt();
2684 } else {
2685 // Don't try to handle vectors of anything other than int or float
2686 // (not sure if it's possible to hit this case).
2687 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2688 return false;
2689 }
2690 unsigned BaseEltSize = EltAsInt.getBitWidth();
2691 if (BigEndian)
2692 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2693 else
2694 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2695 }
2696 return true;
2697 }
2698 // Give up if the input isn't an int, float, or vector. For example, we
2699 // reject "(v4i16)(intptr_t)&a".
2700 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2701 return false;
2702}
2703
2704/// Perform the given integer operation, which is known to need at most BitWidth
2705/// bits, and check for overflow in the original type (if that type was not an
2706/// unsigned type).
2707template<typename Operation>
2708static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2709 const APSInt &LHS, const APSInt &RHS,
2710 unsigned BitWidth, Operation Op,
2711 APSInt &Result) {
2712 if (LHS.isUnsigned()) {
2713 Result = Op(LHS, RHS);
2714 return true;
2715 }
2716
2717 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2718 Result = Value.trunc(LHS.getBitWidth());
2719 if (Result.extend(BitWidth) != Value) {
2720 if (Info.checkingForUndefinedBehavior())
2721 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2722 diag::warn_integer_constant_overflow)
2723 << toString(Result, 10) << E->getType();
2724 return HandleOverflow(Info, E, Value, E->getType());
2725 }
2726 return true;
2727}
2728
2729/// Perform the given binary integer operation.
2730static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2731 BinaryOperatorKind Opcode, APSInt RHS,
2732 APSInt &Result) {
2733 switch (Opcode) {
2734 default:
2735 Info.FFDiag(E);
2736 return false;
2737 case BO_Mul:
2738 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2739 std::multiplies<APSInt>(), Result);
2740 case BO_Add:
2741 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2742 std::plus<APSInt>(), Result);
2743 case BO_Sub:
2744 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2745 std::minus<APSInt>(), Result);
2746 case BO_And: Result = LHS & RHS; return true;
2747 case BO_Xor: Result = LHS ^ RHS; return true;
2748 case BO_Or: Result = LHS | RHS; return true;
2749 case BO_Div:
2750 case BO_Rem:
2751 if (RHS == 0) {
2752 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2753 return false;
2754 }
2755 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2756 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2757 // this operation and gives the two's complement result.
2758 if (RHS.isNegative() && RHS.isAllOnesValue() &&
2759 LHS.isSigned() && LHS.isMinSignedValue())
2760 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2761 E->getType());
2762 return true;
2763 case BO_Shl: {
2764 if (Info.getLangOpts().OpenCL)
2765 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2766 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2767 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2768 RHS.isUnsigned());
2769 else if (RHS.isSigned() && RHS.isNegative()) {
2770 // During constant-folding, a negative shift is an opposite shift. Such
2771 // a shift is not a constant expression.
2772 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2773 RHS = -RHS;
2774 goto shift_right;
2775 }
2776 shift_left:
2777 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2778 // the shifted type.
2779 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2780 if (SA != RHS) {
2781 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2782 << RHS << E->getType() << LHS.getBitWidth();
2783 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2784 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2785 // operand, and must not overflow the corresponding unsigned type.
2786 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2787 // E1 x 2^E2 module 2^N.
2788 if (LHS.isNegative())
2789 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2790 else if (LHS.countLeadingZeros() < SA)
2791 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2792 }
2793 Result = LHS << SA;
2794 return true;
2795 }
2796 case BO_Shr: {
2797 if (Info.getLangOpts().OpenCL)
2798 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2799 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2800 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2801 RHS.isUnsigned());
2802 else if (RHS.isSigned() && RHS.isNegative()) {
2803 // During constant-folding, a negative shift is an opposite shift. Such a
2804 // shift is not a constant expression.
2805 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2806 RHS = -RHS;
2807 goto shift_left;
2808 }
2809 shift_right:
2810 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2811 // shifted type.
2812 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2813 if (SA != RHS)
2814 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2815 << RHS << E->getType() << LHS.getBitWidth();
2816 Result = LHS >> SA;
2817 return true;
2818 }
2819
2820 case BO_LT: Result = LHS < RHS; return true;
2821 case BO_GT: Result = LHS > RHS; return true;
2822 case BO_LE: Result = LHS <= RHS; return true;
2823 case BO_GE: Result = LHS >= RHS; return true;
2824 case BO_EQ: Result = LHS == RHS; return true;
2825 case BO_NE: Result = LHS != RHS; return true;
2826 case BO_Cmp:
2827 llvm_unreachable("BO_Cmp should be handled elsewhere")::llvm::llvm_unreachable_internal("BO_Cmp should be handled elsewhere"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2827)
;
2828 }
2829}
2830
2831/// Perform the given binary floating-point operation, in-place, on LHS.
2832static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2833 APFloat &LHS, BinaryOperatorKind Opcode,
2834 const APFloat &RHS) {
2835 bool DynamicRM;
2836 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
2837 APFloat::opStatus St;
2838 switch (Opcode) {
2839 default:
2840 Info.FFDiag(E);
2841 return false;
2842 case BO_Mul:
2843 St = LHS.multiply(RHS, RM);
2844 break;
2845 case BO_Add:
2846 St = LHS.add(RHS, RM);
2847 break;
2848 case BO_Sub:
2849 St = LHS.subtract(RHS, RM);
2850 break;
2851 case BO_Div:
2852 // [expr.mul]p4:
2853 // If the second operand of / or % is zero the behavior is undefined.
2854 if (RHS.isZero())
2855 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2856 St = LHS.divide(RHS, RM);
2857 break;
2858 }
2859
2860 // [expr.pre]p4:
2861 // If during the evaluation of an expression, the result is not
2862 // mathematically defined [...], the behavior is undefined.
2863 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2864 if (LHS.isNaN()) {
2865 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2866 return Info.noteUndefinedBehavior();
2867 }
2868
2869 return checkFloatingPointResult(Info, E, St);
2870}
2871
2872static bool handleLogicalOpForVector(const APInt &LHSValue,
2873 BinaryOperatorKind Opcode,
2874 const APInt &RHSValue, APInt &Result) {
2875 bool LHS = (LHSValue != 0);
2876 bool RHS = (RHSValue != 0);
2877
2878 if (Opcode == BO_LAnd)
2879 Result = LHS && RHS;
2880 else
2881 Result = LHS || RHS;
2882 return true;
2883}
2884static bool handleLogicalOpForVector(const APFloat &LHSValue,
2885 BinaryOperatorKind Opcode,
2886 const APFloat &RHSValue, APInt &Result) {
2887 bool LHS = !LHSValue.isZero();
2888 bool RHS = !RHSValue.isZero();
2889
2890 if (Opcode == BO_LAnd)
2891 Result = LHS && RHS;
2892 else
2893 Result = LHS || RHS;
2894 return true;
2895}
2896
2897static bool handleLogicalOpForVector(const APValue &LHSValue,
2898 BinaryOperatorKind Opcode,
2899 const APValue &RHSValue, APInt &Result) {
2900 // The result is always an int type, however operands match the first.
2901 if (LHSValue.getKind() == APValue::Int)
2902 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2903 RHSValue.getInt(), Result);
2904 assert(LHSValue.getKind() == APValue::Float && "Should be no other options")(static_cast <bool> (LHSValue.getKind() == APValue::Float
&& "Should be no other options") ? void (0) : __assert_fail
("LHSValue.getKind() == APValue::Float && \"Should be no other options\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2904, __extension__ __PRETTY_FUNCTION__))
;
2905 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2906 RHSValue.getFloat(), Result);
2907}
2908
2909template <typename APTy>
2910static bool
2911handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
2912 const APTy &RHSValue, APInt &Result) {
2913 switch (Opcode) {
2914 default:
2915 llvm_unreachable("unsupported binary operator")::llvm::llvm_unreachable_internal("unsupported binary operator"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2915)
;
2916 case BO_EQ:
2917 Result = (LHSValue == RHSValue);
2918 break;
2919 case BO_NE:
2920 Result = (LHSValue != RHSValue);
2921 break;
2922 case BO_LT:
2923 Result = (LHSValue < RHSValue);
2924 break;
2925 case BO_GT:
2926 Result = (LHSValue > RHSValue);
2927 break;
2928 case BO_LE:
2929 Result = (LHSValue <= RHSValue);
2930 break;
2931 case BO_GE:
2932 Result = (LHSValue >= RHSValue);
2933 break;
2934 }
2935
2936 return true;
2937}
2938
2939static bool handleCompareOpForVector(const APValue &LHSValue,
2940 BinaryOperatorKind Opcode,
2941 const APValue &RHSValue, APInt &Result) {
2942 // The result is always an int type, however operands match the first.
2943 if (LHSValue.getKind() == APValue::Int)
2944 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
2945 RHSValue.getInt(), Result);
2946 assert(LHSValue.getKind() == APValue::Float && "Should be no other options")(static_cast <bool> (LHSValue.getKind() == APValue::Float
&& "Should be no other options") ? void (0) : __assert_fail
("LHSValue.getKind() == APValue::Float && \"Should be no other options\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2946, __extension__ __PRETTY_FUNCTION__))
;
2947 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
2948 RHSValue.getFloat(), Result);
2949}
2950
2951// Perform binary operations for vector types, in place on the LHS.
2952static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
2953 BinaryOperatorKind Opcode,
2954 APValue &LHSValue,
2955 const APValue &RHSValue) {
2956 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&(static_cast <bool> (Opcode != BO_PtrMemD && Opcode
!= BO_PtrMemI && "Operation not supported on vector types"
) ? void (0) : __assert_fail ("Opcode != BO_PtrMemD && Opcode != BO_PtrMemI && \"Operation not supported on vector types\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2957, __extension__ __PRETTY_FUNCTION__))
2957 "Operation not supported on vector types")(static_cast <bool> (Opcode != BO_PtrMemD && Opcode
!= BO_PtrMemI && "Operation not supported on vector types"
) ? void (0) : __assert_fail ("Opcode != BO_PtrMemD && Opcode != BO_PtrMemI && \"Operation not supported on vector types\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2957, __extension__ __PRETTY_FUNCTION__))
;
2958
2959 const auto *VT = E->getType()->castAs<VectorType>();
2960 unsigned NumElements = VT->getNumElements();
2961 QualType EltTy = VT->getElementType();
2962
2963 // In the cases (typically C as I've observed) where we aren't evaluating
2964 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
2965 // just give up.
2966 if (!LHSValue.isVector()) {
2967 assert(LHSValue.isLValue() &&(static_cast <bool> (LHSValue.isLValue() && "A vector result that isn't a vector OR uncalculated LValue"
) ? void (0) : __assert_fail ("LHSValue.isLValue() && \"A vector result that isn't a vector OR uncalculated LValue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2968, __extension__ __PRETTY_FUNCTION__))
2968 "A vector result that isn't a vector OR uncalculated LValue")(static_cast <bool> (LHSValue.isLValue() && "A vector result that isn't a vector OR uncalculated LValue"
) ? void (0) : __assert_fail ("LHSValue.isLValue() && \"A vector result that isn't a vector OR uncalculated LValue\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2968, __extension__ __PRETTY_FUNCTION__))
;
2969 Info.FFDiag(E);
2970 return false;
2971 }
2972
2973 assert(LHSValue.getVectorLength() == NumElements &&(static_cast <bool> (LHSValue.getVectorLength() == NumElements
&& RHSValue.getVectorLength() == NumElements &&
"Different vector sizes") ? void (0) : __assert_fail ("LHSValue.getVectorLength() == NumElements && RHSValue.getVectorLength() == NumElements && \"Different vector sizes\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2974, __extension__ __PRETTY_FUNCTION__))
2974 RHSValue.getVectorLength() == NumElements && "Different vector sizes")(static_cast <bool> (LHSValue.getVectorLength() == NumElements
&& RHSValue.getVectorLength() == NumElements &&
"Different vector sizes") ? void (0) : __assert_fail ("LHSValue.getVectorLength() == NumElements && RHSValue.getVectorLength() == NumElements && \"Different vector sizes\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 2974, __extension__ __PRETTY_FUNCTION__))
;
2975
2976 SmallVector<APValue, 4> ResultElements;
2977
2978 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
2979 APValue LHSElt = LHSValue.getVectorElt(EltNum);
2980 APValue RHSElt = RHSValue.getVectorElt(EltNum);
2981
2982 if (EltTy->isIntegerType()) {
2983 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
2984 EltTy->isUnsignedIntegerType()};
2985 bool Success = true;
2986
2987 if (BinaryOperator::isLogicalOp(Opcode))
2988 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2989 else if (BinaryOperator::isComparisonOp(Opcode))
2990 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
2991 else
2992 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
2993 RHSElt.getInt(), EltResult);
2994
2995 if (!Success) {
2996 Info.FFDiag(E);
2997 return false;
2998 }
2999 ResultElements.emplace_back(EltResult);
3000
3001 } else if (EltTy->isFloatingType()) {
3002 assert(LHSElt.getKind() == APValue::Float &&(static_cast <bool> (LHSElt.getKind() == APValue::Float
&& RHSElt.getKind() == APValue::Float && "Mismatched LHS/RHS/Result Type"
) ? void (0) : __assert_fail ("LHSElt.getKind() == APValue::Float && RHSElt.getKind() == APValue::Float && \"Mismatched LHS/RHS/Result Type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3004, __extension__ __PRETTY_FUNCTION__))
3003 RHSElt.getKind() == APValue::Float &&(static_cast <bool> (LHSElt.getKind() == APValue::Float
&& RHSElt.getKind() == APValue::Float && "Mismatched LHS/RHS/Result Type"
) ? void (0) : __assert_fail ("LHSElt.getKind() == APValue::Float && RHSElt.getKind() == APValue::Float && \"Mismatched LHS/RHS/Result Type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3004, __extension__ __PRETTY_FUNCTION__))
3004 "Mismatched LHS/RHS/Result Type")(static_cast <bool> (LHSElt.getKind() == APValue::Float
&& RHSElt.getKind() == APValue::Float && "Mismatched LHS/RHS/Result Type"
) ? void (0) : __assert_fail ("LHSElt.getKind() == APValue::Float && RHSElt.getKind() == APValue::Float && \"Mismatched LHS/RHS/Result Type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3004, __extension__ __PRETTY_FUNCTION__))
;
3005 APFloat LHSFloat = LHSElt.getFloat();
3006
3007 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3008 RHSElt.getFloat())) {
3009 Info.FFDiag(E);
3010 return false;
3011 }
3012
3013 ResultElements.emplace_back(LHSFloat);
3014 }
3015 }
3016
3017 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3018 return true;
3019}
3020
3021/// Cast an lvalue referring to a base subobject to a derived class, by
3022/// truncating the lvalue's path to the given length.
3023static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3024 const RecordDecl *TruncatedType,
3025 unsigned TruncatedElements) {
3026 SubobjectDesignator &D = Result.Designator;
3027
3028 // Check we actually point to a derived class object.
3029 if (TruncatedElements == D.Entries.size())
3030 return true;
3031 assert(TruncatedElements >= D.MostDerivedPathLength &&(static_cast <bool> (TruncatedElements >= D.MostDerivedPathLength
&& "not casting to a derived class") ? void (0) : __assert_fail
("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3032, __extension__ __PRETTY_FUNCTION__))
3032 "not casting to a derived class")(static_cast <bool> (TruncatedElements >= D.MostDerivedPathLength
&& "not casting to a derived class") ? void (0) : __assert_fail
("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3032, __extension__ __PRETTY_FUNCTION__))
;
3033 if (!Result.checkSubobject(Info, E, CSK_Derived))
3034 return false;
3035
3036 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3037 const RecordDecl *RD = TruncatedType;
3038 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3039 if (RD->isInvalidDecl()) return false;
3040 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3041 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3042 if (isVirtualBaseClass(D.Entries[I]))
3043 Result.Offset -= Layout.getVBaseClassOffset(Base);
3044 else
3045 Result.Offset -= Layout.getBaseClassOffset(Base);
3046 RD = Base;
3047 }
3048 D.Entries.resize(TruncatedElements);
3049 return true;
3050}
3051
3052static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3053 const CXXRecordDecl *Derived,
3054 const CXXRecordDecl *Base,
3055 const ASTRecordLayout *RL = nullptr) {
3056 if (!RL) {
3057 if (Derived->isInvalidDecl()) return false;
3058 RL = &Info.Ctx.getASTRecordLayout(Derived);
3059 }
3060
3061 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3062 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3063 return true;
3064}
3065
3066static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3067 const CXXRecordDecl *DerivedDecl,
3068 const CXXBaseSpecifier *Base) {
3069 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3070
3071 if (!Base->isVirtual())
3072 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3073
3074 SubobjectDesignator &D = Obj.Designator;
3075 if (D.Invalid)
3076 return false;
3077
3078 // Extract most-derived object and corresponding type.
3079 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3080 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3081 return false;
3082
3083 // Find the virtual base class.
3084 if (DerivedDecl->isInvalidDecl()) return false;
3085 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3086 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3087 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3088 return true;
3089}
3090
3091static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3092 QualType Type, LValue &Result) {
3093 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3094 PathE = E->path_end();
3095 PathI != PathE; ++PathI) {
3096 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3097 *PathI))
3098 return false;
3099 Type = (*PathI)->getType();
3100 }
3101 return true;
3102}
3103
3104/// Cast an lvalue referring to a derived class to a known base subobject.
3105static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3106 const CXXRecordDecl *DerivedRD,
3107 const CXXRecordDecl *BaseRD) {
3108 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3109 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3110 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3111 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3111)
;
3112
3113 for (CXXBasePathElement &Elem : Paths.front())
3114 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3115 return false;
3116 return true;
3117}
3118
3119/// Update LVal to refer to the given field, which must be a member of the type
3120/// currently described by LVal.
3121static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3122 const FieldDecl *FD,
3123 const ASTRecordLayout *RL = nullptr) {
3124 if (!RL) {
3125 if (FD->getParent()->isInvalidDecl()) return false;
3126 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3127 }
3128
3129 unsigned I = FD->getFieldIndex();
3130 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3131 LVal.addDecl(Info, E, FD);
3132 return true;
3133}
3134
3135/// Update LVal to refer to the given indirect field.
3136static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3137 LValue &LVal,
3138 const IndirectFieldDecl *IFD) {
3139 for (const auto *C : IFD->chain())
3140 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3141 return false;
3142 return true;
3143}
3144
3145/// Get the size of the given type in char units.
3146static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
3147 QualType Type, CharUnits &Size) {
3148 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3149 // extension.
3150 if (Type->isVoidType() || Type->isFunctionType()) {
3151 Size = CharUnits::One();
3152 return true;
3153 }
3154
3155 if (Type->isDependentType()) {
3156 Info.FFDiag(Loc);
3157 return false;
3158 }
3159
3160 if (!Type->isConstantSizeType()) {
3161 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3162 // FIXME: Better diagnostic.
3163 Info.FFDiag(Loc);
3164 return false;
3165 }
3166
3167 Size = Info.Ctx.getTypeSizeInChars(Type);
3168 return true;
3169}
3170
3171/// Update a pointer value to model pointer arithmetic.
3172/// \param Info - Information about the ongoing evaluation.
3173/// \param E - The expression being evaluated, for diagnostic purposes.
3174/// \param LVal - The pointer value to be updated.
3175/// \param EltTy - The pointee type represented by LVal.
3176/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
3177static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3178 LValue &LVal, QualType EltTy,
3179 APSInt Adjustment) {
3180 CharUnits SizeOfPointee;
3181 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3182 return false;
3183
3184 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3185 return true;
3186}
3187
3188static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3189 LValue &LVal, QualType EltTy,
3190 int64_t Adjustment) {
3191 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3192 APSInt::get(Adjustment));
3193}
3194
3195/// Update an lvalue to refer to a component of a complex number.
3196/// \param Info - Information about the ongoing evaluation.
3197/// \param LVal - The lvalue to be updated.
3198/// \param EltTy - The complex number's component type.
3199/// \param Imag - False for the real component, true for the imaginary.
3200static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3201 LValue &LVal, QualType EltTy,
3202 bool Imag) {
3203 if (Imag) {
3204 CharUnits SizeOfComponent;
3205 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3206 return false;
3207 LVal.Offset += SizeOfComponent;
3208 }
3209 LVal.addComplex(Info, E, EltTy, Imag);
3210 return true;
3211}
3212
3213/// Try to evaluate the initializer for a variable declaration.
3214///
3215/// \param Info Information about the ongoing evaluation.
3216/// \param E An expression to be used when printing diagnostics.
3217/// \param VD The variable whose initializer should be obtained.
3218/// \param Version The version of the variable within the frame.
3219/// \param Frame The frame in which the variable was created. Must be null
3220/// if this variable is not local to the evaluation.
3221/// \param Result Filled in with a pointer to the value of the variable.
3222static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3223 const VarDecl *VD, CallStackFrame *Frame,
3224 unsigned Version, APValue *&Result) {
3225 APValue::LValueBase Base(VD, Frame
13.1
'Frame' is null
13.1
'Frame' is null
? Frame->Index : 0, Version);
14
'?' condition is false
3226
3227 // If this is a local variable, dig out its value.
3228 if (Frame
14.1
'Frame' is null
14.1
'Frame' is null
) {
15
Taking false branch
3229 Result = Frame->getTemporary(VD, Version);
3230 if (Result)
3231 return true;
3232
3233 if (!isa<ParmVarDecl>(VD)) {
3234 // Assume variables referenced within a lambda's call operator that were
3235 // not declared within the call operator are captures and during checking
3236 // of a potential constant expression, assume they are unknown constant
3237 // expressions.
3238 assert(isLambdaCallOperator(Frame->Callee) &&(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3240, __extension__ __PRETTY_FUNCTION__))
3239 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3240, __extension__ __PRETTY_FUNCTION__))
3240 "missing value for local variable")(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3240, __extension__ __PRETTY_FUNCTION__))
;
3241 if (Info.checkingPotentialConstantExpression())
3242 return false;
3243 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3244 // still reachable at all?
3245 Info.FFDiag(E->getBeginLoc(),
3246 diag::note_unimplemented_constexpr_lambda_feature_ast)
3247 << "captures not currently allowed";
3248 return false;
3249 }
3250 }
3251
3252 // If we're currently evaluating the initializer of this declaration, use that
3253 // in-flight value.
3254 if (Info.EvaluatingDecl == Base) {
16
Assuming the condition is false
17
Taking false branch
3255 Result = Info.EvaluatingDeclValue;
3256 return true;
3257 }
3258
3259 if (isa<ParmVarDecl>(VD)) {
18
Assuming 'VD' is a 'ParmVarDecl'
19
Taking true branch
3260 // Assume parameters of a potential constant expression are usable in
3261 // constant expressions.
3262 if (!Info.checkingPotentialConstantExpression() ||
20
Assuming the condition is false
3263 !Info.CurrentCall->Callee ||
21
Access to field 'Callee' results in a dereference of a null pointer (loaded from field 'CurrentCall')
3264 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3265 if (Info.getLangOpts().CPlusPlus11) {
3266 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3267 << VD;
3268 NoteLValueLocation(Info, Base);
3269 } else {
3270 Info.FFDiag(E);
3271 }
3272 }
3273 return false;
3274 }
3275
3276 // Dig out the initializer, and use the declaration which it's attached to.
3277 // FIXME: We should eventually check whether the variable has a reachable
3278 // initializing declaration.
3279 const Expr *Init = VD->getAnyInitializer(VD);
3280 if (!Init) {
3281 // Don't diagnose during potential constant expression checking; an
3282 // initializer might be added later.
3283 if (!Info.checkingPotentialConstantExpression()) {
3284 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3285 << VD;
3286 NoteLValueLocation(Info, Base);
3287 }
3288 return false;
3289 }
3290
3291 if (Init->isValueDependent()) {
3292 // The DeclRefExpr is not value-dependent, but the variable it refers to
3293 // has a value-dependent initializer. This should only happen in
3294 // constant-folding cases, where the variable is not actually of a suitable
3295 // type for use in a constant expression (otherwise the DeclRefExpr would
3296 // have been value-dependent too), so diagnose that.
3297 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx))(static_cast <bool> (!VD->mightBeUsableInConstantExpressions
(Info.Ctx)) ? void (0) : __assert_fail ("!VD->mightBeUsableInConstantExpressions(Info.Ctx)"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3297, __extension__ __PRETTY_FUNCTION__))
;
3298 if (!Info.checkingPotentialConstantExpression()) {
3299 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3300 ? diag::note_constexpr_ltor_non_constexpr
3301 : diag::note_constexpr_ltor_non_integral, 1)
3302 << VD << VD->getType();
3303 NoteLValueLocation(Info, Base);
3304 }
3305 return false;
3306 }
3307
3308 // Check that we can fold the initializer. In C++, we will have already done
3309 // this in the cases where it matters for conformance.
3310 if (!VD->evaluateValue()) {
3311 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3312 NoteLValueLocation(Info, Base);
3313 return false;
3314 }
3315
3316 // Check that the variable is actually usable in constant expressions. For a
3317 // const integral variable or a reference, we might have a non-constant
3318 // initializer that we can nonetheless evaluate the initializer for. Such
3319 // variables are not usable in constant expressions. In C++98, the
3320 // initializer also syntactically needs to be an ICE.
3321 //
3322 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3323 // expressions here; doing so would regress diagnostics for things like
3324 // reading from a volatile constexpr variable.
3325 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3326 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3327 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3328 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3329 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3330 NoteLValueLocation(Info, Base);
3331 }
3332
3333 // Never use the initializer of a weak variable, not even for constant
3334 // folding. We can't be sure that this is the definition that will be used.
3335 if (VD->isWeak()) {
3336 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3337 NoteLValueLocation(Info, Base);
3338 return false;
3339 }
3340
3341 Result = VD->getEvaluatedValue();
3342 return true;
3343}
3344
3345/// Get the base index of the given base class within an APValue representing
3346/// the given derived class.
3347static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3348 const CXXRecordDecl *Base) {
3349 Base = Base->getCanonicalDecl();
3350 unsigned Index = 0;
3351 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3352 E = Derived->bases_end(); I != E; ++I, ++Index) {
3353 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3354 return Index;
3355 }
3356
3357 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3357)
;
3358}
3359
3360/// Extract the value of a character from a string literal.
3361static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3362 uint64_t Index) {
3363 assert(!isa<SourceLocExpr>(Lit) &&(static_cast <bool> (!isa<SourceLocExpr>(Lit) &&
"SourceLocExpr should have already been converted to a StringLiteral"
) ? void (0) : __assert_fail ("!isa<SourceLocExpr>(Lit) && \"SourceLocExpr should have already been converted to a StringLiteral\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3364, __extension__ __PRETTY_FUNCTION__))
3364 "SourceLocExpr should have already been converted to a StringLiteral")(static_cast <bool> (!isa<SourceLocExpr>(Lit) &&
"SourceLocExpr should have already been converted to a StringLiteral"
) ? void (0) : __assert_fail ("!isa<SourceLocExpr>(Lit) && \"SourceLocExpr should have already been converted to a StringLiteral\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3364, __extension__ __PRETTY_FUNCTION__))
;
3365
3366 // FIXME: Support MakeStringConstant
3367 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3368 std::string Str;
3369 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3370 assert(Index <= Str.size() && "Index too large")(static_cast <bool> (Index <= Str.size() && "Index too large"
) ? void (0) : __assert_fail ("Index <= Str.size() && \"Index too large\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3370, __extension__ __PRETTY_FUNCTION__))
;
3371 return APSInt::getUnsigned(Str.c_str()[Index]);
3372 }
3373
3374 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3375 Lit = PE->getFunctionName();
3376 const StringLiteral *S = cast<StringLiteral>(Lit);
3377 const ConstantArrayType *CAT =
3378 Info.Ctx.getAsConstantArrayType(S->getType());
3379 assert(CAT && "string literal isn't an array")(static_cast <bool> (CAT && "string literal isn't an array"
) ? void (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3379, __extension__ __PRETTY_FUNCTION__))
;
3380 QualType CharType = CAT->getElementType();
3381 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3381, __extension__ __PRETTY_FUNCTION__))
;
3382
3383 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3384 CharType->isUnsignedIntegerType());
3385 if (Index < S->getLength())
3386 Value = S->getCodeUnit(Index);
3387 return Value;
3388}
3389
3390// Expand a string literal into an array of characters.
3391//
3392// FIXME: This is inefficient; we should probably introduce something similar
3393// to the LLVM ConstantDataArray to make this cheaper.
3394static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3395 APValue &Result,
3396 QualType AllocType = QualType()) {
3397 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3398 AllocType.isNull() ? S->getType() : AllocType);
3399 assert(CAT && "string literal isn't an array")(static_cast <bool> (CAT && "string literal isn't an array"
) ? void (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3399, __extension__ __PRETTY_FUNCTION__))
;
3400 QualType CharType = CAT->getElementType();
3401 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3401, __extension__ __PRETTY_FUNCTION__))
;
3402
3403 unsigned Elts = CAT->getSize().getZExtValue();
3404 Result = APValue(APValue::UninitArray(),
3405 std::min(S->getLength(), Elts), Elts);
3406 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3407 CharType->isUnsignedIntegerType());
3408 if (Result.hasArrayFiller())
3409 Result.getArrayFiller() = APValue(Value);
3410 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3411 Value = S->getCodeUnit(I);
3412 Result.getArrayInitializedElt(I) = APValue(Value);
3413 }
3414}
3415
3416// Expand an array so that it has more than Index filled elements.
3417static void expandArray(APValue &Array, unsigned Index) {
3418 unsigned Size = Array.getArraySize();
3419 assert(Index < Size)(static_cast <bool> (Index < Size) ? void (0) : __assert_fail
("Index < Size", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3419, __extension__ __PRETTY_FUNCTION__))
;
3420
3421 // Always at least double the number of elements for which we store a value.
3422 unsigned OldElts = Array.getArrayInitializedElts();
3423 unsigned NewElts = std::max(Index+1, OldElts * 2);
3424 NewElts = std::min(Size, std::max(NewElts, 8u));
3425
3426 // Copy the data across.
3427 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3428 for (unsigned I = 0; I != OldElts; ++I)
3429 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3430 for (unsigned I = OldElts; I != NewElts; ++I)
3431 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3432 if (NewValue.hasArrayFiller())
3433 NewValue.getArrayFiller() = Array.getArrayFiller();
3434 Array.swap(NewValue);
3435}
3436
3437/// Determine whether a type would actually be read by an lvalue-to-rvalue
3438/// conversion. If it's of class type, we may assume that the copy operation
3439/// is trivial. Note that this is never true for a union type with fields
3440/// (because the copy always "reads" the active member) and always true for
3441/// a non-class type.
3442static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
3443static bool isReadByLvalueToRvalueConversion(QualType T) {
3444 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3445 return !RD || isReadByLvalueToRvalueConversion(RD);
3446}
3447static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3448 // FIXME: A trivial copy of a union copies the object representation, even if
3449 // the union is empty.
3450 if (RD->isUnion())
3451 return !RD->field_empty();
3452 if (RD->isEmpty())
3453 return false;
3454
3455 for (auto *Field : RD->fields())
3456 if (!Field->isUnnamedBitfield() &&
3457 isReadByLvalueToRvalueConversion(Field->getType()))
3458 return true;
3459
3460 for (auto &BaseSpec : RD->bases())
3461 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3462 return true;
3463
3464 return false;
3465}
3466
3467/// Diagnose an attempt to read from any unreadable field within the specified
3468/// type, which might be a class type.
3469static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3470 QualType T) {
3471 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3472 if (!RD)
3473 return false;
3474
3475 if (!RD->hasMutableFields())
3476 return false;
3477
3478 for (auto *Field : RD->fields()) {
3479 // If we're actually going to read this field in some way, then it can't
3480 // be mutable. If we're in a union, then assigning to a mutable field
3481 // (even an empty one) can change the active member, so that's not OK.
3482 // FIXME: Add core issue number for the union case.
3483 if (Field->isMutable() &&
3484 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3485 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3486 Info.Note(Field->getLocation(), diag::note_declared_at);
3487 return true;
3488 }
3489
3490 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3491 return true;
3492 }
3493
3494 for (auto &BaseSpec : RD->bases())
3495 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3496 return true;
3497
3498 // All mutable fields were empty, and thus not actually read.
3499 return false;
3500}
3501
3502static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3503 APValue::LValueBase Base,
3504 bool MutableSubobject = false) {
3505 // A temporary or transient heap allocation we created.
3506 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3507 return true;
3508
3509 switch (Info.IsEvaluatingDecl) {
3510 case EvalInfo::EvaluatingDeclKind::None:
3511 return false;
3512
3513 case EvalInfo::EvaluatingDeclKind::Ctor:
3514 // The variable whose initializer we're evaluating.
3515 if (Info.EvaluatingDecl == Base)
3516 return true;
3517
3518 // A temporary lifetime-extended by the variable whose initializer we're
3519 // evaluating.
3520 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3521 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3522 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3523 return false;
3524
3525 case EvalInfo::EvaluatingDeclKind::Dtor:
3526 // C++2a [expr.const]p6:
3527 // [during constant destruction] the lifetime of a and its non-mutable
3528 // subobjects (but not its mutable subobjects) [are] considered to start
3529 // within e.
3530 if (MutableSubobject || Base != Info.EvaluatingDecl)
3531 return false;
3532 // FIXME: We can meaningfully extend this to cover non-const objects, but
3533 // we will need special handling: we should be able to access only
3534 // subobjects of such objects that are themselves declared const.
3535 QualType T = getType(Base);
3536 return T.isConstQualified() || T->isReferenceType();
3537 }
3538
3539 llvm_unreachable("unknown evaluating decl kind")::llvm::llvm_unreachable_internal("unknown evaluating decl kind"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3539)
;
3540}
3541
3542namespace {
3543/// A handle to a complete object (an object that is not a subobject of
3544/// another object).
3545struct CompleteObject {
3546 /// The identity of the object.
3547 APValue::LValueBase Base;
3548 /// The value of the complete object.
3549 APValue *Value;
3550 /// The type of the complete object.
3551 QualType Type;
3552
3553 CompleteObject() : Value(nullptr) {}
3554 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3555 : Base(Base), Value(Value), Type(Type) {}
3556
3557 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3558 // If this isn't a "real" access (eg, if it's just accessing the type
3559 // info), allow it. We assume the type doesn't change dynamically for
3560 // subobjects of constexpr objects (even though we'd hit UB here if it
3561 // did). FIXME: Is this right?
3562 if (!isAnyAccess(AK))
3563 return true;
3564
3565 // In C++14 onwards, it is permitted to read a mutable member whose
3566 // lifetime began within the evaluation.
3567 // FIXME: Should we also allow this in C++11?
3568 if (!Info.getLangOpts().CPlusPlus14)
3569 return false;
3570 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3571 }
3572
3573 explicit operator bool() const { return !Type.isNull(); }
3574};
3575} // end anonymous namespace
3576
3577static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3578 bool IsMutable = false) {
3579 // C++ [basic.type.qualifier]p1:
3580 // - A const object is an object of type const T or a non-mutable subobject
3581 // of a const object.
3582 if (ObjType.isConstQualified() && !IsMutable)
3583 SubobjType.addConst();
3584 // - A volatile object is an object of type const T or a subobject of a
3585 // volatile object.
3586 if (ObjType.isVolatileQualified())
3587 SubobjType.addVolatile();
3588 return SubobjType;
3589}
3590
3591/// Find the designated sub-object of an rvalue.
3592template<typename SubobjectHandler>
3593typename SubobjectHandler::result_type
3594findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3595 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3596 if (Sub.Invalid)
3597 // A diagnostic will have already been produced.
3598 return handler.failed();
3599 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3600 if (Info.getLangOpts().CPlusPlus11)
3601 Info.FFDiag(E, Sub.isOnePastTheEnd()
3602 ? diag::note_constexpr_access_past_end
3603 : diag::note_constexpr_access_unsized_array)
3604 << handler.AccessKind;
3605 else
3606 Info.FFDiag(E);
3607 return handler.failed();
3608 }
3609
3610 APValue *O = Obj.Value;
3611 QualType ObjType = Obj.Type;
3612 const FieldDecl *LastField = nullptr;
3613 const FieldDecl *VolatileField = nullptr;
3614
3615 // Walk the designator's path to find the subobject.
3616 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3617 // Reading an indeterminate value is undefined, but assigning over one is OK.
3618 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3619 (O->isIndeterminate() &&
3620 !isValidIndeterminateAccess(handler.AccessKind))) {
3621 if (!Info.checkingPotentialConstantExpression())
3622 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3623 << handler.AccessKind << O->isIndeterminate();
3624 return handler.failed();
3625 }
3626
3627 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3628 // const and volatile semantics are not applied on an object under
3629 // {con,de}struction.
3630 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3631 ObjType->isRecordType() &&
3632 Info.isEvaluatingCtorDtor(
3633 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
3634 Sub.Entries.begin() + I)) !=
3635 ConstructionPhase::None) {
3636 ObjType = Info.Ctx.getCanonicalType(ObjType);
3637 ObjType.removeLocalConst();
3638 ObjType.removeLocalVolatile();
3639 }
3640
3641 // If this is our last pass, check that the final object type is OK.
3642 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3643 // Accesses to volatile objects are prohibited.
3644 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3645 if (Info.getLangOpts().CPlusPlus) {
3646 int DiagKind;
3647 SourceLocation Loc;
3648 const NamedDecl *Decl = nullptr;
3649 if (VolatileField) {
3650 DiagKind = 2;
3651 Loc = VolatileField->getLocation();
3652 Decl = VolatileField;
3653 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3654 DiagKind = 1;
3655 Loc = VD->getLocation();
3656 Decl = VD;
3657 } else {
3658 DiagKind = 0;
3659 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3660 Loc = E->getExprLoc();
3661 }
3662 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3663 << handler.AccessKind << DiagKind << Decl;
3664 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3665 } else {
3666 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3667 }
3668 return handler.failed();
3669 }
3670
3671 // If we are reading an object of class type, there may still be more
3672 // things we need to check: if there are any mutable subobjects, we
3673 // cannot perform this read. (This only happens when performing a trivial
3674 // copy or assignment.)
3675 if (ObjType->isRecordType() &&
3676 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3677 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3678 return handler.failed();
3679 }
3680
3681 if (I == N) {
3682 if (!handler.found(*O, ObjType))
3683 return false;
3684
3685 // If we modified a bit-field, truncate it to the right width.
3686 if (isModification(handler.AccessKind) &&
3687 LastField && LastField->isBitField() &&
3688 !truncateBitfieldValue(Info, E, *O, LastField))
3689 return false;
3690
3691 return true;
3692 }
3693
3694 LastField = nullptr;
3695 if (ObjType->isArrayType()) {
3696 // Next subobject is an array element.
3697 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3698 assert(CAT && "vla in literal type?")(static_cast <bool> (CAT && "vla in literal type?"
) ? void (0) : __assert_fail ("CAT && \"vla in literal type?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3698, __extension__ __PRETTY_FUNCTION__))
;
3699 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3700 if (CAT->getSize().ule(Index)) {
3701 // Note, it should not be possible to form a pointer with a valid
3702 // designator which points more than one past the end of the array.
3703 if (Info.getLangOpts().CPlusPlus11)
3704 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3705 << handler.AccessKind;
3706 else
3707 Info.FFDiag(E);
3708 return handler.failed();
3709 }
3710
3711 ObjType = CAT->getElementType();
3712
3713 if (O->getArrayInitializedElts() > Index)
3714 O = &O->getArrayInitializedElt(Index);
3715 else if (!isRead(handler.AccessKind)) {
3716 expandArray(*O, Index);
3717 O = &O->getArrayInitializedElt(Index);
3718 } else
3719 O = &O->getArrayFiller();
3720 } else if (ObjType->isAnyComplexType()) {
3721 // Next subobject is a complex number.
3722 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3723 if (Index > 1) {
3724 if (Info.getLangOpts().CPlusPlus11)
3725 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3726 << handler.AccessKind;
3727 else
3728 Info.FFDiag(E);
3729 return handler.failed();
3730 }
3731
3732 ObjType = getSubobjectType(
3733 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3734
3735 assert(I == N - 1 && "extracting subobject of scalar?")(static_cast <bool> (I == N - 1 && "extracting subobject of scalar?"
) ? void (0) : __assert_fail ("I == N - 1 && \"extracting subobject of scalar?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3735, __extension__ __PRETTY_FUNCTION__))
;
3736 if (O->isComplexInt()) {
3737 return handler.found(Index ? O->getComplexIntImag()
3738 : O->getComplexIntReal(), ObjType);
3739 } else {
3740 assert(O->isComplexFloat())(static_cast <bool> (O->isComplexFloat()) ? void (0)
: __assert_fail ("O->isComplexFloat()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3740, __extension__ __PRETTY_FUNCTION__))
;
3741 return handler.found(Index ? O->getComplexFloatImag()
3742 : O->getComplexFloatReal(), ObjType);
3743 }
3744 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3745 if (Field->isMutable() &&
3746 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3747 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3748 << handler.AccessKind << Field;
3749 Info.Note(Field->getLocation(), diag::note_declared_at);
3750 return handler.failed();
3751 }
3752
3753 // Next subobject is a class, struct or union field.
3754 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3755 if (RD->isUnion()) {
3756 const FieldDecl *UnionField = O->getUnionField();
3757 if (!UnionField ||
3758 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3759 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3760 // Placement new onto an inactive union member makes it active.
3761 O->setUnion(Field, APValue());
3762 } else {
3763 // FIXME: If O->getUnionValue() is absent, report that there's no
3764 // active union member rather than reporting the prior active union
3765 // member. We'll need to fix nullptr_t to not use APValue() as its
3766 // representation first.
3767 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3768 << handler.AccessKind << Field << !UnionField << UnionField;
3769 return handler.failed();
3770 }
3771 }
3772 O = &O->getUnionValue();
3773 } else
3774 O = &O->getStructField(Field->getFieldIndex());
3775
3776 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3777 LastField = Field;
3778 if (Field->getType().isVolatileQualified())
3779 VolatileField = Field;
3780 } else {
3781 // Next subobject is a base class.
3782 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3783 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3784 O = &O->getStructBase(getBaseIndex(Derived, Base));
3785
3786 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3787 }
3788 }
3789}
3790
3791namespace {
3792struct ExtractSubobjectHandler {
3793 EvalInfo &Info;
3794 const Expr *E;
3795 APValue &Result;
3796 const AccessKinds AccessKind;
3797
3798 typedef bool result_type;
3799 bool failed() { return false; }
3800 bool found(APValue &Subobj, QualType SubobjType) {
3801 Result = Subobj;
3802 if (AccessKind == AK_ReadObjectRepresentation)
3803 return true;
3804 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3805 }
3806 bool found(APSInt &Value, QualType SubobjType) {
3807 Result = APValue(Value);
3808 return true;
3809 }
3810 bool found(APFloat &Value, QualType SubobjType) {
3811 Result = APValue(Value);
3812 return true;
3813 }
3814};
3815} // end anonymous namespace
3816
3817/// Extract the designated sub-object of an rvalue.
3818static bool extractSubobject(EvalInfo &Info, const Expr *E,
3819 const CompleteObject &Obj,
3820 const SubobjectDesignator &Sub, APValue &Result,
3821 AccessKinds AK = AK_Read) {
3822 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation)(static_cast <bool> (AK == AK_Read || AK == AK_ReadObjectRepresentation
) ? void (0) : __assert_fail ("AK == AK_Read || AK == AK_ReadObjectRepresentation"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 3822, __extension__ __PRETTY_FUNCTION__))
;
3823 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3824 return findSubobject(Info, E, Obj, Sub, Handler);
3825}
3826
3827namespace {
3828struct ModifySubobjectHandler {
3829 EvalInfo &Info;
3830 APValue &NewVal;
3831 const Expr *E;
3832
3833 typedef bool result_type;
3834 static const AccessKinds AccessKind = AK_Assign;
3835
3836 bool checkConst(QualType QT) {
3837 // Assigning to a const object has undefined behavior.
3838 if (QT.isConstQualified()) {
3839 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3840 return false;
3841 }
3842 return true;
3843 }
3844
3845 bool failed() { return false; }
3846 bool found(APValue &Subobj, QualType SubobjType) {
3847 if (!checkConst(SubobjType))
3848 return false;
3849 // We've been given ownership of NewVal, so just swap it in.
3850 Subobj.swap(NewVal);
3851 return true;
3852 }
3853 bool found(APSInt &Value, QualType SubobjType) {
3854 if (!checkConst(SubobjType))
3855 return false;
3856 if (!NewVal.isInt()) {
3857 // Maybe trying to write a cast pointer value into a complex?
3858 Info.FFDiag(E);
3859 return false;
3860 }
3861 Value = NewVal.getInt();
3862 return true;
3863 }
3864 bool found(APFloat &Value, QualType SubobjType) {
3865 if (!checkConst(SubobjType))
3866 return false;
3867 Value = NewVal.getFloat();
3868 return true;
3869 }
3870};
3871} // end anonymous namespace
3872
3873const AccessKinds ModifySubobjectHandler::AccessKind;
3874
3875/// Update the designated sub-object of an rvalue to the given value.
3876static bool modifySubobject(EvalInfo &Info, const Expr *E,
3877 const CompleteObject &Obj,
3878 const SubobjectDesignator &Sub,
3879 APValue &NewVal) {
3880 ModifySubobjectHandler Handler = { Info, NewVal, E };
3881 return findSubobject(Info, E, Obj, Sub, Handler);
3882}
3883
3884/// Find the position where two subobject designators diverge, or equivalently
3885/// the length of the common initial subsequence.
3886static unsigned FindDesignatorMismatch(QualType ObjType,
3887 const SubobjectDesignator &A,
3888 const SubobjectDesignator &B,
3889 bool &WasArrayIndex) {
3890 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3891 for (/**/; I != N; ++I) {
3892 if (!ObjType.isNull() &&
3893 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3894 // Next subobject is an array element.
3895 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3896 WasArrayIndex = true;
3897 return I;
3898 }
3899 if (ObjType->isAnyComplexType())
3900 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3901 else
3902 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3903 } else {
3904 if (A.Entries[I].getAsBaseOrMember() !=
3905 B.Entries[I].getAsBaseOrMember()) {
3906 WasArrayIndex = false;
3907 return I;
3908 }
3909 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3910 // Next subobject is a field.
3911 ObjType = FD->getType();
3912 else
3913 // Next subobject is a base class.
3914 ObjType = QualType();
3915 }
3916 }
3917 WasArrayIndex = false;
3918 return I;
3919}
3920
3921/// Determine whether the given subobject designators refer to elements of the
3922/// same array object.
3923static bool AreElementsOfSameArray(QualType ObjType,
3924 const SubobjectDesignator &A,
3925 const SubobjectDesignator &B) {
3926 if (A.Entries.size() != B.Entries.size())
3927 return false;
3928
3929 bool IsArray = A.MostDerivedIsArrayElement;
3930 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3931 // A is a subobject of the array element.
3932 return false;
3933
3934 // If A (and B) designates an array element, the last entry will be the array
3935 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3936 // of length 1' case, and the entire path must match.
3937 bool WasArrayIndex;
3938 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3939 return CommonLength >= A.Entries.size() - IsArray;
3940}
3941
3942/// Find the complete object to which an LValue refers.
3943static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3944 AccessKinds AK, const LValue &LVal,
3945 QualType LValType) {
3946 if (LVal.InvalidBase) {
3947 Info.FFDiag(E);
3948 return CompleteObject();
3949 }
3950
3951 if (!LVal.Base) {
3952 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3953 return CompleteObject();
3954 }
3955
3956 CallStackFrame *Frame = nullptr;
3957 unsigned Depth = 0;
3958 if (LVal.getLValueCallIndex()) {
3959 std::tie(Frame, Depth) =
3960 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3961 if (!Frame) {
3962 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3963 << AK << LVal.Base.is<const ValueDecl*>();
3964 NoteLValueLocation(Info, LVal.Base);
3965 return CompleteObject();
3966 }
3967 }
3968
3969 bool IsAccess = isAnyAccess(AK);
3970
3971 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3972 // is not a constant expression (even if the object is non-volatile). We also
3973 // apply this rule to C++98, in order to conform to the expected 'volatile'
3974 // semantics.
3975 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3976 if (Info.getLangOpts().CPlusPlus)
3977 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3978 << AK << LValType;
3979 else
3980 Info.FFDiag(E);
3981 return CompleteObject();
3982 }
3983
3984 // Compute value storage location and type of base object.
3985 APValue *BaseVal = nullptr;
3986 QualType BaseType = getType(LVal.Base);
3987
3988 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
3989 lifetimeStartedInEvaluation(Info, LVal.Base)) {
3990 // This is the object whose initializer we're evaluating, so its lifetime
3991 // started in the current evaluation.
3992 BaseVal = Info.EvaluatingDeclValue;
3993 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
3994 // Allow reading from a GUID declaration.
3995 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
3996 if (isModification(AK)) {
3997 // All the remaining cases do not permit modification of the object.
3998 Info.FFDiag(E, diag::note_constexpr_modify_global);
3999 return CompleteObject();
4000 }
4001 APValue &V = GD->getAsAPValue();
4002 if (V.isAbsent()) {
4003 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4004 << GD->getType();
4005 return CompleteObject();
4006 }
4007 return CompleteObject(LVal.Base, &V, GD->getType());
4008 }
4009
4010 // Allow reading from template parameter objects.
4011 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4012 if (isModification(AK)) {
4013 Info.FFDiag(E, diag::note_constexpr_modify_global);
4014 return CompleteObject();
4015 }
4016 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4017 TPO->getType());
4018 }
4019
4020 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4021 // In C++11, constexpr, non-volatile variables initialized with constant
4022 // expressions are constant expressions too. Inside constexpr functions,
4023 // parameters are constant expressions even if they're non-const.
4024 // In C++1y, objects local to a constant expression (those with a Frame) are
4025 // both readable and writable inside constant expressions.
4026 // In C, such things can also be folded, although they are not ICEs.
4027 const VarDecl *VD = dyn_cast<VarDecl>(D);
4028 if (VD) {
4029 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4030 VD = VDef;
4031 }
4032 if (!VD || VD->isInvalidDecl()) {
4033 Info.FFDiag(E);
4034 return CompleteObject();
4035 }
4036
4037 bool IsConstant = BaseType.isConstant(Info.Ctx);
4038
4039 // Unless we're looking at a local variable or argument in a constexpr call,
4040 // the variable we're reading must be const.
4041 if (!Frame) {
4042 if (IsAccess && isa<ParmVarDecl>(VD)) {
4043 // Access of a parameter that's not associated with a frame isn't going
4044 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4045 // suitable diagnostic.
4046 } else if (Info.getLangOpts().CPlusPlus14 &&
4047 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4048 // OK, we can read and modify an object if we're in the process of
4049 // evaluating its initializer, because its lifetime began in this
4050 // evaluation.
4051 } else if (isModification(AK)) {
4052 // All the remaining cases do not permit modification of the object.
4053 Info.FFDiag(E, diag::note_constexpr_modify_global);
4054 return CompleteObject();
4055 } else if (VD->isConstexpr()) {
4056 // OK, we can read this variable.
4057 } else if (BaseType->isIntegralOrEnumerationType()) {
4058 if (!IsConstant) {
4059 if (!IsAccess)
4060 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4061 if (Info.getLangOpts().CPlusPlus) {
4062 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4063 Info.Note(VD->getLocation(), diag::note_declared_at);
4064 } else {
4065 Info.FFDiag(E);
4066 }
4067 return CompleteObject();
4068 }
4069 } else if (!IsAccess) {
4070 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4071 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4072 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4073 // This variable might end up being constexpr. Don't diagnose it yet.
4074 } else if (IsConstant) {
4075 // Keep evaluating to see what we can do. In particular, we support
4076 // folding of const floating-point types, in order to make static const
4077 // data members of such types (supported as an extension) more useful.
4078 if (Info.getLangOpts().CPlusPlus) {
4079 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4080 ? diag::note_constexpr_ltor_non_constexpr
4081 : diag::note_constexpr_ltor_non_integral, 1)
4082 << VD << BaseType;
4083 Info.Note(VD->getLocation(), diag::note_declared_at);
4084 } else {
4085 Info.CCEDiag(E);
4086 }
4087 } else {
4088 // Never allow reading a non-const value.
4089 if (Info.getLangOpts().CPlusPlus) {
4090 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4091 ? diag::note_constexpr_ltor_non_constexpr
4092 : diag::note_constexpr_ltor_non_integral, 1)
4093 << VD << BaseType;
4094 Info.Note(VD->getLocation(), diag::note_declared_at);
4095 } else {
4096 Info.FFDiag(E);
4097 }
4098 return CompleteObject();
4099 }
4100 }
4101
4102 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4103 return CompleteObject();
4104 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4105 Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA);
4106 if (!Alloc) {
4107 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4108 return CompleteObject();
4109 }
4110 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4111 LVal.Base.getDynamicAllocType());
4112 } else {
4113 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4114
4115 if (!Frame) {
4116 if (const MaterializeTemporaryExpr *MTE =
4117 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4118 assert(MTE->getStorageDuration() == SD_Static &&(static_cast <bool> (MTE->getStorageDuration() == SD_Static
&& "should have a frame for a non-global materialized temporary"
) ? void (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4119, __extension__ __PRETTY_FUNCTION__))
4119 "should have a frame for a non-global materialized temporary")(static_cast <bool> (MTE->getStorageDuration() == SD_Static
&& "should have a frame for a non-global materialized temporary"
) ? void (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4119, __extension__ __PRETTY_FUNCTION__))
;
4120
4121 // C++20 [expr.const]p4: [DR2126]
4122 // An object or reference is usable in constant expressions if it is
4123 // - a temporary object of non-volatile const-qualified literal type
4124 // whose lifetime is extended to that of a variable that is usable
4125 // in constant expressions
4126 //
4127 // C++20 [expr.const]p5:
4128 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4129 // - a non-volatile glvalue that refers to an object that is usable
4130 // in constant expressions, or
4131 // - a non-volatile glvalue of literal type that refers to a
4132 // non-volatile object whose lifetime began within the evaluation
4133 // of E;
4134 //
4135 // C++11 misses the 'began within the evaluation of e' check and
4136 // instead allows all temporaries, including things like:
4137 // int &&r = 1;
4138 // int x = ++r;
4139 // constexpr int k = r;
4140 // Therefore we use the C++14-onwards rules in C++11 too.
4141 //
4142 // Note that temporaries whose lifetimes began while evaluating a
4143 // variable's constructor are not usable while evaluating the
4144 // corresponding destructor, not even if they're of const-qualified
4145 // types.
4146 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4147 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4148 if (!IsAccess)
4149 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4150 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4151 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4152 return CompleteObject();
4153 }
4154
4155 BaseVal = MTE->getOrCreateValue(false);
4156 assert(BaseVal && "got reference to unevaluated temporary")(static_cast <bool> (BaseVal && "got reference to unevaluated temporary"
) ? void (0) : __assert_fail ("BaseVal && \"got reference to unevaluated temporary\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4156, __extension__ __PRETTY_FUNCTION__))
;
4157 } else {
4158 if (!IsAccess)
4159 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4160 APValue Val;
4161 LVal.moveInto(Val);
4162 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4163 << AK
4164 << Val.getAsString(Info.Ctx,
4165 Info.Ctx.getLValueReferenceType(LValType));
4166 NoteLValueLocation(Info, LVal.Base);
4167 return CompleteObject();
4168 }
4169 } else {
4170 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4171 assert(BaseVal && "missing value for temporary")(static_cast <bool> (BaseVal && "missing value for temporary"
) ? void (0) : __assert_fail ("BaseVal && \"missing value for temporary\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4171, __extension__ __PRETTY_FUNCTION__))
;
4172 }
4173 }
4174
4175 // In C++14, we can't safely access any mutable state when we might be
4176 // evaluating after an unmodeled side effect. Parameters are modeled as state
4177 // in the caller, but aren't visible once the call returns, so they can be
4178 // modified in a speculatively-evaluated call.
4179 //
4180 // FIXME: Not all local state is mutable. Allow local constant subobjects
4181 // to be read here (but take care with 'mutable' fields).
4182 unsigned VisibleDepth = Depth;
4183 if (llvm::isa_and_nonnull<ParmVarDecl>(
4184 LVal.Base.dyn_cast<const ValueDecl *>()))
4185 ++VisibleDepth;
4186 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4187 Info.EvalStatus.HasSideEffects) ||
4188 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4189 return CompleteObject();
4190
4191 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4192}
4193
4194/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4195/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4196/// glvalue referred to by an entity of reference type.
4197///
4198/// \param Info - Information about the ongoing evaluation.
4199/// \param Conv - The expression for which we are performing the conversion.
4200/// Used for diagnostics.
4201/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4202/// case of a non-class type).
4203/// \param LVal - The glvalue on which we are attempting to perform this action.
4204/// \param RVal - The produced value will be placed here.
4205/// \param WantObjectRepresentation - If true, we're looking for the object
4206/// representation rather than the value, and in particular,
4207/// there is no requirement that the result be fully initialized.
4208static bool
4209handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4210 const LValue &LVal, APValue &RVal,
4211 bool WantObjectRepresentation = false) {
4212 if (LVal.Designator.Invalid)
4213 return false;
4214
4215 // Check for special cases where there is no existing APValue to look at.
4216 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4217
4218 AccessKinds AK =
4219 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4220
4221 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4222 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4223 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4224 // initializer until now for such expressions. Such an expression can't be
4225 // an ICE in C, so this only matters for fold.
4226 if (Type.isVolatileQualified()) {
4227 Info.FFDiag(Conv);
4228 return false;
4229 }
4230 APValue Lit;
4231 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4232 return false;
4233 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4234 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4235 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4236 // Special-case character extraction so we don't have to construct an
4237 // APValue for the whole string.
4238 assert(LVal.Designator.Entries.size() <= 1 &&(static_cast <bool> (LVal.Designator.Entries.size() <=
1 && "Can only read characters from string literals"
) ? void (0) : __assert_fail ("LVal.Designator.Entries.size() <= 1 && \"Can only read characters from string literals\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4239, __extension__ __PRETTY_FUNCTION__))
4239 "Can only read characters from string literals")(static_cast <bool> (LVal.Designator.Entries.size() <=
1 && "Can only read characters from string literals"
) ? void (0) : __assert_fail ("LVal.Designator.Entries.size() <= 1 && \"Can only read characters from string literals\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4239, __extension__ __PRETTY_FUNCTION__))
;
4240 if (LVal.Designator.Entries.empty()) {
4241 // Fail for now for LValue to RValue conversion of an array.
4242 // (This shouldn't show up in C/C++, but it could be triggered by a
4243 // weird EvaluateAsRValue call from a tool.)
4244 Info.FFDiag(Conv);
4245 return false;
4246 }
4247 if (LVal.Designator.isOnePastTheEnd()) {
4248 if (Info.getLangOpts().CPlusPlus11)
4249 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4250 else
4251 Info.FFDiag(Conv);
4252 return false;
4253 }
4254 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4255 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4256 return true;
4257 }
4258 }
4259
4260 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4261 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4262}
4263
4264/// Perform an assignment of Val to LVal. Takes ownership of Val.
4265static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4266 QualType LValType, APValue &Val) {
4267 if (LVal.Designator.Invalid)
4268 return false;
4269
4270 if (!Info.getLangOpts().CPlusPlus14) {
4271 Info.FFDiag(E);
4272 return false;
4273 }
4274
4275 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4276 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4277}
4278
4279namespace {
4280struct CompoundAssignSubobjectHandler {
4281 EvalInfo &Info;
4282 const CompoundAssignOperator *E;
4283 QualType PromotedLHSType;
4284 BinaryOperatorKind Opcode;
4285 const APValue &RHS;
4286
4287 static const AccessKinds AccessKind = AK_Assign;
4288
4289 typedef bool result_type;
4290
4291 bool checkConst(QualType QT) {
4292 // Assigning to a const object has undefined behavior.
4293 if (QT.isConstQualified()) {
4294 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4295 return false;
4296 }
4297 return true;
4298 }
4299
4300 bool failed() { return false; }
4301 bool found(APValue &Subobj, QualType SubobjType) {
4302 switch (Subobj.getKind()) {
4303 case APValue::Int:
4304 return found(Subobj.getInt(), SubobjType);
4305 case APValue::Float:
4306 return found(Subobj.getFloat(), SubobjType);
4307 case APValue::ComplexInt:
4308 case APValue::ComplexFloat:
4309 // FIXME: Implement complex compound assignment.
4310 Info.FFDiag(E);
4311 return false;
4312 case APValue::LValue:
4313 return foundPointer(Subobj, SubobjType);
4314 case APValue::Vector:
4315 return foundVector(Subobj, SubobjType);
4316 default:
4317 // FIXME: can this happen?
4318 Info.FFDiag(E);
4319 return false;
4320 }
4321 }
4322
4323 bool foundVector(APValue &Value, QualType SubobjType) {
4324 if (!checkConst(SubobjType))
4325 return false;
4326
4327 if (!SubobjType->isVectorType()) {
4328 Info.FFDiag(E);
4329 return false;
4330 }
4331 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4332 }
4333
4334 bool found(APSInt &Value, QualType SubobjType) {
4335 if (!checkConst(SubobjType))
4336 return false;
4337
4338 if (!SubobjType->isIntegerType()) {
4339 // We don't support compound assignment on integer-cast-to-pointer
4340 // values.
4341 Info.FFDiag(E);
4342 return false;
4343 }
4344
4345 if (RHS.isInt()) {
4346 APSInt LHS =
4347 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4348 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4349 return false;
4350 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4351 return true;
4352 } else if (RHS.isFloat()) {
4353 const FPOptions FPO = E->getFPFeaturesInEffect(
4354 Info.Ctx.getLangOpts());
4355 APFloat FValue(0.0);
4356 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4357 PromotedLHSType, FValue) &&
4358 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4359 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4360 Value);
4361 }
4362
4363 Info.FFDiag(E);
4364 return false;
4365 }
4366 bool found(APFloat &Value, QualType SubobjType) {
4367 return checkConst(SubobjType) &&
4368 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4369 Value) &&
4370 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4371 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4372 }
4373 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4374 if (!checkConst(SubobjType))
4375 return false;
4376
4377 QualType PointeeType;
4378 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4379 PointeeType = PT->getPointeeType();
4380
4381 if (PointeeType.isNull() || !RHS.isInt() ||
4382 (Opcode != BO_Add && Opcode != BO_Sub)) {
4383 Info.FFDiag(E);
4384 return false;
4385 }
4386
4387 APSInt Offset = RHS.getInt();
4388 if (Opcode == BO_Sub)
4389 negateAsSigned(Offset);
4390
4391 LValue LVal;
4392 LVal.setFrom(Info.Ctx, Subobj);
4393 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4394 return false;
4395 LVal.moveInto(Subobj);
4396 return true;
4397 }
4398};
4399} // end anonymous namespace
4400
4401const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4402
4403/// Perform a compound assignment of LVal <op>= RVal.
4404static bool handleCompoundAssignment(EvalInfo &Info,
4405 const CompoundAssignOperator *E,
4406 const LValue &LVal, QualType LValType,
4407 QualType PromotedLValType,
4408 BinaryOperatorKind Opcode,
4409 const APValue &RVal) {
4410 if (LVal.Designator.Invalid)
4411 return false;
4412
4413 if (!Info.getLangOpts().CPlusPlus14) {
4414 Info.FFDiag(E);
4415 return false;
4416 }
4417
4418 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4419 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4420 RVal };
4421 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4422}
4423
4424namespace {
4425struct IncDecSubobjectHandler {
4426 EvalInfo &Info;
4427 const UnaryOperator *E;
4428 AccessKinds AccessKind;
4429 APValue *Old;
4430
4431 typedef bool result_type;
4432
4433 bool checkConst(QualType QT) {
4434 // Assigning to a const object has undefined behavior.
4435 if (QT.isConstQualified()) {
4436 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4437 return false;
4438 }
4439 return true;
4440 }
4441
4442 bool failed() { return false; }
4443 bool found(APValue &Subobj, QualType SubobjType) {
4444 // Stash the old value. Also clear Old, so we don't clobber it later
4445 // if we're post-incrementing a complex.
4446 if (Old) {
4447 *Old = Subobj;
4448 Old = nullptr;
4449 }
4450
4451 switch (Subobj.getKind()) {
4452 case APValue::Int:
4453 return found(Subobj.getInt(), SubobjType);
4454 case APValue::Float:
4455 return found(Subobj.getFloat(), SubobjType);
4456 case APValue::ComplexInt:
4457 return found(Subobj.getComplexIntReal(),
4458 SubobjType->castAs<ComplexType>()->getElementType()
4459 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4460 case APValue::ComplexFloat:
4461 return found(Subobj.getComplexFloatReal(),
4462 SubobjType->castAs<ComplexType>()->getElementType()
4463 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4464 case APValue::LValue:
4465 return foundPointer(Subobj, SubobjType);
4466 default:
4467 // FIXME: can this happen?
4468 Info.FFDiag(E);
4469 return false;
4470 }
4471 }
4472 bool found(APSInt &Value, QualType SubobjType) {
4473 if (!checkConst(SubobjType))
4474 return false;
4475
4476 if (!SubobjType->isIntegerType()) {
4477 // We don't support increment / decrement on integer-cast-to-pointer
4478 // values.
4479 Info.FFDiag(E);
4480 return false;
4481 }
4482
4483 if (Old) *Old = APValue(Value);
4484
4485 // bool arithmetic promotes to int, and the conversion back to bool
4486 // doesn't reduce mod 2^n, so special-case it.
4487 if (SubobjType->isBooleanType()) {
4488 if (AccessKind == AK_Increment)
4489 Value = 1;
4490 else
4491 Value = !Value;
4492 return true;
4493 }
4494
4495 bool WasNegative = Value.isNegative();
4496 if (AccessKind == AK_Increment) {
4497 ++Value;
4498
4499 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4500 APSInt ActualValue(Value, /*IsUnsigned*/true);
4501 return HandleOverflow(Info, E, ActualValue, SubobjType);
4502 }
4503 } else {
4504 --Value;
4505
4506 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4507 unsigned BitWidth = Value.getBitWidth();
4508 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4509 ActualValue.setBit(BitWidth);
4510 return HandleOverflow(Info, E, ActualValue, SubobjType);
4511 }
4512 }
4513 return true;
4514 }
4515 bool found(APFloat &Value, QualType SubobjType) {
4516 if (!checkConst(SubobjType))
4517 return false;
4518
4519 if (Old) *Old = APValue(Value);
4520
4521 APFloat One(Value.getSemantics(), 1);
4522 if (AccessKind == AK_Increment)
4523 Value.add(One, APFloat::rmNearestTiesToEven);
4524 else
4525 Value.subtract(One, APFloat::rmNearestTiesToEven);
4526 return true;
4527 }
4528 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4529 if (!checkConst(SubobjType))
4530 return false;
4531
4532 QualType PointeeType;
4533 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4534 PointeeType = PT->getPointeeType();
4535 else {
4536 Info.FFDiag(E);
4537 return false;
4538 }
4539
4540 LValue LVal;
4541 LVal.setFrom(Info.Ctx, Subobj);
4542 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4543 AccessKind == AK_Increment ? 1 : -1))
4544 return false;
4545 LVal.moveInto(Subobj);
4546 return true;
4547 }
4548};
4549} // end anonymous namespace
4550
4551/// Perform an increment or decrement on LVal.
4552static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4553 QualType LValType, bool IsIncrement, APValue *Old) {
4554 if (LVal.Designator.Invalid)
4555 return false;
4556
4557 if (!Info.getLangOpts().CPlusPlus14) {
4558 Info.FFDiag(E);
4559 return false;
4560 }
4561
4562 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4563 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4564 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4565 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4566}
4567
4568/// Build an lvalue for the object argument of a member function call.
4569static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4570 LValue &This) {
4571 if (Object->getType()->isPointerType() && Object->isPRValue())
4572 return EvaluatePointer(Object, This, Info);
4573
4574 if (Object->isGLValue())
4575 return EvaluateLValue(Object, This, Info);
4576
4577 if (Object->getType()->isLiteralType(Info.Ctx))
4578 return EvaluateTemporary(Object, This, Info);
4579
4580 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4581 return false;
4582}
4583
4584/// HandleMemberPointerAccess - Evaluate a member access operation and build an
4585/// lvalue referring to the result.
4586///
4587/// \param Info - Information about the ongoing evaluation.
4588/// \param LV - An lvalue referring to the base of the member pointer.
4589/// \param RHS - The member pointer expression.
4590/// \param IncludeMember - Specifies whether the member itself is included in
4591/// the resulting LValue subobject designator. This is not possible when
4592/// creating a bound member function.
4593/// \return The field or method declaration to which the member pointer refers,
4594/// or 0 if evaluation fails.
4595static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4596 QualType LVType,
4597 LValue &LV,
4598 const Expr *RHS,
4599 bool IncludeMember = true) {
4600 MemberPtr MemPtr;
4601 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4602 return nullptr;
4603
4604 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4605 // member value, the behavior is undefined.
4606 if (!MemPtr.getDecl()) {
4607 // FIXME: Specific diagnostic.
4608 Info.FFDiag(RHS);
4609 return nullptr;
4610 }
4611
4612 if (MemPtr.isDerivedMember()) {
4613 // This is a member of some derived class. Truncate LV appropriately.
4614 // The end of the derived-to-base path for the base object must match the
4615 // derived-to-base path for the member pointer.
4616 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4617 LV.Designator.Entries.size()) {
4618 Info.FFDiag(RHS);
4619 return nullptr;
4620 }
4621 unsigned PathLengthToMember =
4622 LV.Designator.Entries.size() - MemPtr.Path.size();
4623 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4624 const CXXRecordDecl *LVDecl = getAsBaseClass(
4625 LV.Designator.Entries[PathLengthToMember + I]);
4626 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4627 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4628 Info.FFDiag(RHS);
4629 return nullptr;
4630 }
4631 }
4632
4633 // Truncate the lvalue to the appropriate derived class.
4634 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4635 PathLengthToMember))
4636 return nullptr;
4637 } else if (!MemPtr.Path.empty()) {
4638 // Extend the LValue path with the member pointer's path.
4639 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4640 MemPtr.Path.size() + IncludeMember);
4641
4642 // Walk down to the appropriate base class.
4643 if (const PointerType *PT = LVType->getAs<PointerType>())
4644 LVType = PT->getPointeeType();
4645 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4646 assert(RD && "member pointer access on non-class-type expression")(static_cast <bool> (RD && "member pointer access on non-class-type expression"
) ? void (0) : __assert_fail ("RD && \"member pointer access on non-class-type expression\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4646, __extension__ __PRETTY_FUNCTION__))
;
4647 // The first class in the path is that of the lvalue.
4648 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4649 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4650 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4651 return nullptr;
4652 RD = Base;
4653 }
4654 // Finally cast to the class containing the member.
4655 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4656 MemPtr.getContainingRecord()))
4657 return nullptr;
4658 }
4659
4660 // Add the member. Note that we cannot build bound member functions here.
4661 if (IncludeMember) {
4662 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4663 if (!HandleLValueMember(Info, RHS, LV, FD))
4664 return nullptr;
4665 } else if (const IndirectFieldDecl *IFD =
4666 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4667 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4668 return nullptr;
4669 } else {
4670 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4670)
;
4671 }
4672 }
4673
4674 return MemPtr.getDecl();
4675}
4676
4677static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4678 const BinaryOperator *BO,
4679 LValue &LV,
4680 bool IncludeMember = true) {
4681 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI)(static_cast <bool> (BO->getOpcode() == BO_PtrMemD ||
BO->getOpcode() == BO_PtrMemI) ? void (0) : __assert_fail
("BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI"
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4681, __extension__ __PRETTY_FUNCTION__))
;
4682
4683 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4684 if (Info.noteFailure()) {
4685 MemberPtr MemPtr;
4686 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4687 }
4688 return nullptr;
4689 }
4690
4691 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4692 BO->getRHS(), IncludeMember);
4693}
4694
4695/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4696/// the provided lvalue, which currently refers to the base object.
4697static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4698 LValue &Result) {
4699 SubobjectDesignator &D = Result.Designator;
4700 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4701 return false;
4702
4703 QualType TargetQT = E->getType();
4704 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4705 TargetQT = PT->getPointeeType();
4706
4707 // Check this cast lands within the final derived-to-base subobject path.
4708 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4709 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4710 << D.MostDerivedType << TargetQT;
4711 return false;
4712 }
4713
4714 // Check the type of the final cast. We don't need to check the path,
4715 // since a cast can only be formed if the path is unique.
4716 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4717 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4718 const CXXRecordDecl *FinalType;
4719 if (NewEntriesSize == D.MostDerivedPathLength)
4720 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4721 else
4722 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4723 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4724 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4725 << D.MostDerivedType << TargetQT;
4726 return false;
4727 }
4728
4729 // Truncate the lvalue to the appropriate derived class.
4730 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4731}
4732
4733/// Get the value to use for a default-initialized object of type T.
4734/// Return false if it encounters something invalid.
4735static bool getDefaultInitValue(QualType T, APValue &Result) {
4736 bool Success = true;
4737 if (auto *RD = T->getAsCXXRecordDecl()) {
4738 if (RD->isInvalidDecl()) {
4739 Result = APValue();
4740 return false;
4741 }
4742 if (RD->isUnion()) {
4743 Result = APValue((const FieldDecl *)nullptr);
4744 return true;
4745 }
4746 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4747 std::distance(RD->field_begin(), RD->field_end()));
4748
4749 unsigned Index = 0;
4750 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4751 End = RD->bases_end();
4752 I != End; ++I, ++Index)
4753 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
4754
4755 for (const auto *I : RD->fields()) {
4756 if (I->isUnnamedBitfield())
4757 continue;
4758 Success &= getDefaultInitValue(I->getType(),
4759 Result.getStructField(I->getFieldIndex()));
4760 }
4761 return Success;
4762 }
4763
4764 if (auto *AT =
4765 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4766 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4767 if (Result.hasArrayFiller())
4768 Success &=
4769 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4770
4771 return Success;
4772 }
4773
4774 Result = APValue::IndeterminateValue();
4775 return true;
4776}
4777
4778namespace {
4779enum EvalStmtResult {
4780 /// Evaluation failed.
4781 ESR_Failed,
4782 /// Hit a 'return' statement.
4783 ESR_Returned,
4784 /// Evaluation succeeded.
4785 ESR_Succeeded,
4786 /// Hit a 'continue' statement.
4787 ESR_Continue,
4788 /// Hit a 'break' statement.
4789 ESR_Break,
4790 /// Still scanning for 'case' or 'default' statement.
4791 ESR_CaseNotFound
4792};
4793}
4794
4795static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4796 // We don't need to evaluate the initializer for a static local.
4797 if (!VD->hasLocalStorage())
4798 return true;
4799
4800 LValue Result;
4801 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4802 ScopeKind::Block, Result);
4803
4804 const Expr *InitE = VD->getInit();
4805 if (!InitE) {
4806 if (VD->getType()->isDependentType())
4807 return Info.noteSideEffect();
4808 return getDefaultInitValue(VD->getType(), Val);
4809 }
4810 if (InitE->isValueDependent())
4811 return false;
4812
4813 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4814 // Wipe out any partially-computed value, to allow tracking that this
4815 // evaluation failed.
4816 Val = APValue();
4817 return false;
4818 }
4819
4820 return true;
4821}
4822
4823static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4824 bool OK = true;
4825
4826 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4827 OK &= EvaluateVarDecl(Info, VD);
4828
4829 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4830 for (auto *BD : DD->bindings())
4831 if (auto *VD = BD->getHoldingVar())
4832 OK &= EvaluateDecl(Info, VD);
4833
4834 return OK;
4835}
4836
4837static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4838 assert(E->isValueDependent())(static_cast <bool> (E->isValueDependent()) ? void (
0) : __assert_fail ("E->isValueDependent()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4838, __extension__ __PRETTY_FUNCTION__))
;
4839 if (Info.noteSideEffect())
4840 return true;
4841 assert(E->containsErrors() && "valid value-dependent expression should never "(static_cast <bool> (E->containsErrors() && "valid value-dependent expression should never "
"reach invalid code path.") ? void (0) : __assert_fail ("E->containsErrors() && \"valid value-dependent expression should never \" \"reach invalid code path.\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4842, __extension__ __PRETTY_FUNCTION__))
4842 "reach invalid code path.")(static_cast <bool> (E->containsErrors() && "valid value-dependent expression should never "
"reach invalid code path.") ? void (0) : __assert_fail ("E->containsErrors() && \"valid value-dependent expression should never \" \"reach invalid code path.\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4842, __extension__ __PRETTY_FUNCTION__))
;
4843 return false;
4844}
4845
4846/// Evaluate a condition (either a variable declaration or an expression).
4847static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4848 const Expr *Cond, bool &Result) {
4849 if (Cond->isValueDependent())
4850 return false;
4851 FullExpressionRAII Scope(Info);
4852 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4853 return false;
4854 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4855 return false;
4856 return Scope.destroy();
4857}
4858
4859namespace {
4860/// A location where the result (returned value) of evaluating a
4861/// statement should be stored.
4862struct StmtResult {
4863 /// The APValue that should be filled in with the returned value.
4864 APValue &Value;
4865 /// The location containing the result, if any (used to support RVO).
4866 const LValue *Slot;
4867};
4868
4869struct TempVersionRAII {
4870 CallStackFrame &Frame;
4871
4872 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4873 Frame.pushTempVersion();
4874 }
4875
4876 ~TempVersionRAII() {
4877 Frame.popTempVersion();
4878 }
4879};
4880
4881}
4882
4883static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4884 const Stmt *S,
4885 const SwitchCase *SC = nullptr);
4886
4887/// Evaluate the body of a loop, and translate the result as appropriate.
4888static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4889 const Stmt *Body,
4890 const SwitchCase *Case = nullptr) {
4891 BlockScopeRAII Scope(Info);
4892
4893 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4894 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4895 ESR = ESR_Failed;
4896
4897 switch (ESR) {
4898 case ESR_Break:
4899 return ESR_Succeeded;
4900 case ESR_Succeeded:
4901 case ESR_Continue:
4902 return ESR_Continue;
4903 case ESR_Failed:
4904 case ESR_Returned:
4905 case ESR_CaseNotFound:
4906 return ESR;
4907 }
4908 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4908)
;
4909}
4910
4911/// Evaluate a switch statement.
4912static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4913 const SwitchStmt *SS) {
4914 BlockScopeRAII Scope(Info);
4915
4916 // Evaluate the switch condition.
4917 APSInt Value;
4918 {
4919 if (const Stmt *Init = SS->getInit()) {
4920 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4921 if (ESR != ESR_Succeeded) {
4922 if (ESR != ESR_Failed && !Scope.destroy())
4923 ESR = ESR_Failed;
4924 return ESR;
4925 }
4926 }
4927
4928 FullExpressionRAII CondScope(Info);
4929 if (SS->getConditionVariable() &&
4930 !EvaluateDecl(Info, SS->getConditionVariable()))
4931 return ESR_Failed;
4932 if (!EvaluateInteger(SS->getCond(), Value, Info))
4933 return ESR_Failed;
4934 if (!CondScope.destroy())
4935 return ESR_Failed;
4936 }
4937
4938 // Find the switch case corresponding to the value of the condition.
4939 // FIXME: Cache this lookup.
4940 const SwitchCase *Found = nullptr;
4941 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
4942 SC = SC->getNextSwitchCase()) {
4943 if (isa<DefaultStmt>(SC)) {
4944 Found = SC;
4945 continue;
4946 }
4947
4948 const CaseStmt *CS = cast<CaseStmt>(SC);
4949 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
4950 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
4951 : LHS;
4952 if (LHS <= Value && Value <= RHS) {
4953 Found = SC;
4954 break;
4955 }
4956 }
4957
4958 if (!Found)
4959 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
4960
4961 // Search the switch body for the switch case and evaluate it from there.
4962 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
4963 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4964 return ESR_Failed;
4965
4966 switch (ESR) {
4967 case ESR_Break:
4968 return ESR_Succeeded;
4969 case ESR_Succeeded:
4970 case ESR_Continue:
4971 case ESR_Failed:
4972 case ESR_Returned:
4973 return ESR;
4974 case ESR_CaseNotFound:
4975 // This can only happen if the switch case is nested within a statement
4976 // expression. We have no intention of supporting that.
4977 Info.FFDiag(Found->getBeginLoc(),
4978 diag::note_constexpr_stmt_expr_unsupported);
4979 return ESR_Failed;
4980 }
4981 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 4981)
;
4982}
4983
4984// Evaluate a statement.
4985static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4986 const Stmt *S, const SwitchCase *Case) {
4987 if (!Info.nextStep(S))
4988 return ESR_Failed;
4989
4990 // If we're hunting down a 'case' or 'default' label, recurse through
4991 // substatements until we hit the label.
4992 if (Case) {
4993 switch (S->getStmtClass()) {
4994 case Stmt::CompoundStmtClass:
4995 // FIXME: Precompute which substatement of a compound statement we
4996 // would jump to, and go straight there rather than performing a
4997 // linear scan each time.
4998 case Stmt::LabelStmtClass:
4999 case Stmt::AttributedStmtClass:
5000 case Stmt::DoStmtClass:
5001 break;
5002
5003 case Stmt::CaseStmtClass:
5004 case Stmt::DefaultStmtClass:
5005 if (Case == S)
5006 Case = nullptr;
5007 break;
5008
5009 case Stmt::IfStmtClass: {
5010 // FIXME: Precompute which side of an 'if' we would jump to, and go
5011 // straight there rather than scanning both sides.
5012 const IfStmt *IS = cast<IfStmt>(S);
5013
5014 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5015 // preceded by our switch label.
5016 BlockScopeRAII Scope(Info);
5017
5018 // Step into the init statement in case it brings an (uninitialized)
5019 // variable into scope.
5020 if (const Stmt *Init = IS->getInit()) {
5021 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5022 if (ESR != ESR_CaseNotFound) {
5023 assert(ESR != ESR_Succeeded)(static_cast <bool> (ESR != ESR_Succeeded) ? void (0) :
__assert_fail ("ESR != ESR_Succeeded", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5023, __extension__ __PRETTY_FUNCTION__))
;
5024 return ESR;
5025 }
5026 }
5027
5028 // Condition variable must be initialized if it exists.
5029 // FIXME: We can skip evaluating the body if there's a condition
5030 // variable, as there can't be any case labels within it.
5031 // (The same is true for 'for' statements.)
5032
5033 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5034 if (ESR == ESR_Failed)
5035 return ESR;
5036 if (ESR != ESR_CaseNotFound)
5037 return Scope.destroy() ? ESR : ESR_Failed;
5038 if (!IS->getElse())
5039 return ESR_CaseNotFound;
5040
5041 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5042 if (ESR == ESR_Failed)
5043 return ESR;
5044 if (ESR != ESR_CaseNotFound)
5045 return Scope.destroy() ? ESR : ESR_Failed;
5046 return ESR_CaseNotFound;
5047 }
5048
5049 case Stmt::WhileStmtClass: {
5050 EvalStmtResult ESR =
5051 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5052 if (ESR != ESR_Continue)
5053 return ESR;
5054 break;
5055 }
5056
5057 case Stmt::ForStmtClass: {
5058 const ForStmt *FS = cast<ForStmt>(S);
5059 BlockScopeRAII Scope(Info);
5060
5061 // Step into the init statement in case it brings an (uninitialized)
5062 // variable into scope.
5063 if (const Stmt *Init = FS->getInit()) {
5064 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5065 if (ESR != ESR_CaseNotFound) {
5066 assert(ESR != ESR_Succeeded)(static_cast <bool> (ESR != ESR_Succeeded) ? void (0) :
__assert_fail ("ESR != ESR_Succeeded", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5066, __extension__ __PRETTY_FUNCTION__))
;
5067 return ESR;
5068 }
5069 }
5070
5071 EvalStmtResult ESR =
5072 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5073 if (ESR != ESR_Continue)
5074 return ESR;
5075 if (const auto *Inc = FS->getInc()) {
5076 if (Inc->isValueDependent()) {
5077 if (!EvaluateDependentExpr(Inc, Info))
5078 return ESR_Failed;
5079 } else {
5080 FullExpressionRAII IncScope(Info);
5081 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5082 return ESR_Failed;
5083 }
5084 }
5085 break;
5086 }
5087
5088 case Stmt::DeclStmtClass: {
5089 // Start the lifetime of any uninitialized variables we encounter. They
5090 // might be used by the selected branch of the switch.
5091 const DeclStmt *DS = cast<DeclStmt>(S);
5092 for (const auto *D : DS->decls()) {
5093 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5094 if (VD->hasLocalStorage() && !VD->getInit())
5095 if (!EvaluateVarDecl(Info, VD))
5096 return ESR_Failed;
5097 // FIXME: If the variable has initialization that can't be jumped
5098 // over, bail out of any immediately-surrounding compound-statement
5099 // too. There can't be any case labels here.
5100 }
5101 }
5102 return ESR_CaseNotFound;
5103 }
5104
5105 default:
5106 return ESR_CaseNotFound;
5107 }
5108 }
5109
5110 switch (S->getStmtClass()) {
5111 default:
5112 if (const Expr *E = dyn_cast<Expr>(S)) {
5113 if (E->isValueDependent()) {
5114 if (!EvaluateDependentExpr(E, Info))
5115 return ESR_Failed;
5116 } else {
5117 // Don't bother evaluating beyond an expression-statement which couldn't
5118 // be evaluated.
5119 // FIXME: Do we need the FullExpressionRAII object here?
5120 // VisitExprWithCleanups should create one when necessary.
5121 FullExpressionRAII Scope(Info);
5122 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5123 return ESR_Failed;
5124 }
5125 return ESR_Succeeded;
5126 }
5127
5128 Info.FFDiag(S->getBeginLoc());
5129 return ESR_Failed;
5130
5131 case Stmt::NullStmtClass:
5132 return ESR_Succeeded;
5133
5134 case Stmt::DeclStmtClass: {
5135 const DeclStmt *DS = cast<DeclStmt>(S);
5136 for (const auto *D : DS->decls()) {
5137 // Each declaration initialization is its own full-expression.
5138 FullExpressionRAII Scope(Info);
5139 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5140 return ESR_Failed;
5141 if (!Scope.destroy())
5142 return ESR_Failed;
5143 }
5144 return ESR_Succeeded;
5145 }
5146
5147 case Stmt::ReturnStmtClass: {
5148 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5149 FullExpressionRAII Scope(Info);
5150 if (RetExpr && RetExpr->isValueDependent()) {
5151 EvaluateDependentExpr(RetExpr, Info);
5152 // We know we returned, but we don't know what the value is.
5153 return ESR_Failed;
5154 }
5155 if (RetExpr &&
5156 !(Result.Slot
5157 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5158 : Evaluate(Result.Value, Info, RetExpr)))
5159 return ESR_Failed;
5160 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5161 }
5162
5163 case Stmt::CompoundStmtClass: {
5164 BlockScopeRAII Scope(Info);
5165
5166 const CompoundStmt *CS = cast<CompoundStmt>(S);
5167 for (const auto *BI : CS->body()) {
5168 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5169 if (ESR == ESR_Succeeded)
5170 Case = nullptr;
5171 else if (ESR != ESR_CaseNotFound) {
5172 if (ESR != ESR_Failed && !Scope.destroy())
5173 return ESR_Failed;
5174 return ESR;
5175 }
5176 }
5177 if (Case)
5178 return ESR_CaseNotFound;
5179 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5180 }
5181
5182 case Stmt::IfStmtClass: {
5183 const IfStmt *IS = cast<IfStmt>(S);
5184
5185 // Evaluate the condition, as either a var decl or as an expression.
5186 BlockScopeRAII Scope(Info);
5187 if (const Stmt *Init = IS->getInit()) {
5188 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5189 if (ESR != ESR_Succeeded) {
5190 if (ESR != ESR_Failed && !Scope.destroy())
5191 return ESR_Failed;
5192 return ESR;
5193 }
5194 }
5195 bool Cond;
5196 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
5197 return ESR_Failed;
5198
5199 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5200 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5201 if (ESR != ESR_Succeeded) {
5202 if (ESR != ESR_Failed && !Scope.destroy())
5203 return ESR_Failed;
5204 return ESR;
5205 }
5206 }
5207 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5208 }
5209
5210 case Stmt::WhileStmtClass: {
5211 const WhileStmt *WS = cast<WhileStmt>(S);
5212 while (true) {
5213 BlockScopeRAII Scope(Info);
5214 bool Continue;
5215 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5216 Continue))
5217 return ESR_Failed;
5218 if (!Continue)
5219 break;
5220
5221 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5222 if (ESR != ESR_Continue) {
5223 if (ESR != ESR_Failed && !Scope.destroy())
5224 return ESR_Failed;
5225 return ESR;
5226 }
5227 if (!Scope.destroy())
5228 return ESR_Failed;
5229 }
5230 return ESR_Succeeded;
5231 }
5232
5233 case Stmt::DoStmtClass: {
5234 const DoStmt *DS = cast<DoStmt>(S);
5235 bool Continue;
5236 do {
5237 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5238 if (ESR != ESR_Continue)
5239 return ESR;
5240 Case = nullptr;
5241
5242 if (DS->getCond()->isValueDependent()) {
5243 EvaluateDependentExpr(DS->getCond(), Info);
5244 // Bailout as we don't know whether to keep going or terminate the loop.
5245 return ESR_Failed;
5246 }
5247 FullExpressionRAII CondScope(Info);
5248 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5249 !CondScope.destroy())
5250 return ESR_Failed;
5251 } while (Continue);
5252 return ESR_Succeeded;
5253 }
5254
5255 case Stmt::ForStmtClass: {
5256 const ForStmt *FS = cast<ForStmt>(S);
5257 BlockScopeRAII ForScope(Info);
5258 if (FS->getInit()) {
5259 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5260 if (ESR != ESR_Succeeded) {
5261 if (ESR != ESR_Failed && !ForScope.destroy())
5262 return ESR_Failed;
5263 return ESR;
5264 }
5265 }
5266 while (true) {
5267 BlockScopeRAII IterScope(Info);
5268 bool Continue = true;
5269 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5270 FS->getCond(), Continue))
5271 return ESR_Failed;
5272 if (!Continue)
5273 break;
5274
5275 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5276 if (ESR != ESR_Continue) {
5277 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5278 return ESR_Failed;
5279 return ESR;
5280 }
5281
5282 if (const auto *Inc = FS->getInc()) {
5283 if (Inc->isValueDependent()) {
5284 if (!EvaluateDependentExpr(Inc, Info))
5285 return ESR_Failed;
5286 } else {
5287 FullExpressionRAII IncScope(Info);
5288 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5289 return ESR_Failed;
5290 }
5291 }
5292
5293 if (!IterScope.destroy())
5294 return ESR_Failed;
5295 }
5296 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5297 }
5298
5299 case Stmt::CXXForRangeStmtClass: {
5300 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5301 BlockScopeRAII Scope(Info);
5302
5303 // Evaluate the init-statement if present.
5304 if (FS->getInit()) {
5305 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5306 if (ESR != ESR_Succeeded) {
5307 if (ESR != ESR_Failed && !Scope.destroy())
5308 return ESR_Failed;
5309 return ESR;
5310 }
5311 }
5312
5313 // Initialize the __range variable.
5314 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5315 if (ESR != ESR_Succeeded) {
5316 if (ESR != ESR_Failed && !Scope.destroy())
5317 return ESR_Failed;
5318 return ESR;
5319 }
5320
5321 // Create the __begin and __end iterators.
5322 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5323 if (ESR != ESR_Succeeded) {
5324 if (ESR != ESR_Failed && !Scope.destroy())
5325 return ESR_Failed;
5326 return ESR;
5327 }
5328 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5329 if (ESR != ESR_Succeeded) {
5330 if (ESR != ESR_Failed && !Scope.destroy())
5331 return ESR_Failed;
5332 return ESR;
5333 }
5334
5335 while (true) {
5336 // Condition: __begin != __end.
5337 {
5338 if (FS->getCond()->isValueDependent()) {
5339 EvaluateDependentExpr(FS->getCond(), Info);
5340 // We don't know whether to keep going or terminate the loop.
5341 return ESR_Failed;
5342 }
5343 bool Continue = true;
5344 FullExpressionRAII CondExpr(Info);
5345 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5346 return ESR_Failed;
5347 if (!Continue)
5348 break;
5349 }
5350
5351 // User's variable declaration, initialized by *__begin.
5352 BlockScopeRAII InnerScope(Info);
5353 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5354 if (ESR != ESR_Succeeded) {
5355 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5356 return ESR_Failed;
5357 return ESR;
5358 }
5359
5360 // Loop body.
5361 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5362 if (ESR != ESR_Continue) {
5363 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5364 return ESR_Failed;
5365 return ESR;
5366 }
5367 if (FS->getInc()->isValueDependent()) {
5368 if (!EvaluateDependentExpr(FS->getInc(), Info))
5369 return ESR_Failed;
5370 } else {
5371 // Increment: ++__begin
5372 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5373 return ESR_Failed;
5374 }
5375
5376 if (!InnerScope.destroy())
5377 return ESR_Failed;
5378 }
5379
5380 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5381 }
5382
5383 case Stmt::SwitchStmtClass:
5384 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5385
5386 case Stmt::ContinueStmtClass:
5387 return ESR_Continue;
5388
5389 case Stmt::BreakStmtClass:
5390 return ESR_Break;
5391
5392 case Stmt::LabelStmtClass:
5393 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5394
5395 case Stmt::AttributedStmtClass:
5396 // As a general principle, C++11 attributes can be ignored without
5397 // any semantic impact.
5398 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
5399 Case);
5400
5401 case Stmt::CaseStmtClass:
5402 case Stmt::DefaultStmtClass:
5403 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5404 case Stmt::CXXTryStmtClass:
5405 // Evaluate try blocks by evaluating all sub statements.
5406 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5407 }
5408}
5409
5410/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5411/// default constructor. If so, we'll fold it whether or not it's marked as
5412/// constexpr. If it is marked as constexpr, we will never implicitly define it,
5413/// so we need special handling.
5414static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5415 const CXXConstructorDecl *CD,
5416 bool IsValueInitialization) {
5417 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5418 return false;
5419
5420 // Value-initialization does not call a trivial default constructor, so such a
5421 // call is a core constant expression whether or not the constructor is
5422 // constexpr.
5423 if (!CD->isConstexpr() && !IsValueInitialization) {
5424 if (Info.getLangOpts().CPlusPlus11) {
5425 // FIXME: If DiagDecl is an implicitly-declared special member function,
5426 // we should be much more explicit about why it's not constexpr.
5427 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5428 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5429 Info.Note(CD->getLocation(), diag::note_declared_at);
5430 } else {
5431 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5432 }
5433 }
5434 return true;
5435}
5436
5437/// CheckConstexprFunction - Check that a function can be called in a constant
5438/// expression.
5439static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5440 const FunctionDecl *Declaration,
5441 const FunctionDecl *Definition,
5442 const Stmt *Body) {
5443 // Potential constant expressions can contain calls to declared, but not yet
5444 // defined, constexpr functions.
5445 if (Info.checkingPotentialConstantExpression() && !Definition &&
5446 Declaration->isConstexpr())
5447 return false;
5448
5449 // Bail out if the function declaration itself is invalid. We will
5450 // have produced a relevant diagnostic while parsing it, so just
5451 // note the problematic sub-expression.
5452 if (Declaration->isInvalidDecl()) {
5453 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5454 return false;
5455 }
5456
5457 // DR1872: An instantiated virtual constexpr function can't be called in a
5458 // constant expression (prior to C++20). We can still constant-fold such a
5459 // call.
5460 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5461 cast<CXXMethodDecl>(Declaration)->isVirtual())
5462 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5463
5464 if (Definition && Definition->isInvalidDecl()) {
5465 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5466 return false;
5467 }
5468
5469 // Can we evaluate this function call?
5470 if (Definition && Definition->isConstexpr() && Body)
5471 return true;
5472
5473 if (Info.getLangOpts().CPlusPlus11) {
5474 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5475
5476 // If this function is not constexpr because it is an inherited
5477 // non-constexpr constructor, diagnose that directly.
5478 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5479 if (CD && CD->isInheritingConstructor()) {
5480 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5481 if (!Inherited->isConstexpr())
5482 DiagDecl = CD = Inherited;
5483 }
5484
5485 // FIXME: If DiagDecl is an implicitly-declared special member function
5486 // or an inheriting constructor, we should be much more explicit about why
5487 // it's not constexpr.
5488 if (CD && CD->isInheritingConstructor())
5489 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5490 << CD->getInheritedConstructor().getConstructor()->getParent();
5491 else
5492 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5493 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5494 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5495 } else {
5496 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5497 }
5498 return false;
5499}
5500
5501namespace {
5502struct CheckDynamicTypeHandler {
5503 AccessKinds AccessKind;
5504 typedef bool result_type;
5505 bool failed() { return false; }
5506 bool found(APValue &Subobj, QualType SubobjType) { return true; }
5507 bool found(APSInt &Value, QualType SubobjType) { return true; }
5508 bool found(APFloat &Value, QualType SubobjType) { return true; }
5509};
5510} // end anonymous namespace
5511
5512/// Check that we can access the notional vptr of an object / determine its
5513/// dynamic type.
5514static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5515 AccessKinds AK, bool Polymorphic) {
5516 if (This.Designator.Invalid)
5517 return false;
5518
5519 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5520
5521 if (!Obj)
5522 return false;
5523
5524 if (!Obj.Value) {
5525 // The object is not usable in constant expressions, so we can't inspect
5526 // its value to see if it's in-lifetime or what the active union members
5527 // are. We can still check for a one-past-the-end lvalue.
5528 if (This.Designator.isOnePastTheEnd() ||
5529 This.Designator.isMostDerivedAnUnsizedArray()) {
5530 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
5531 ? diag::note_constexpr_access_past_end
5532 : diag::note_constexpr_access_unsized_array)
5533 << AK;
5534 return false;
5535 } else if (Polymorphic) {
5536 // Conservatively refuse to perform a polymorphic operation if we would
5537 // not be able to read a notional 'vptr' value.
5538 APValue Val;
5539 This.moveInto(Val);
5540 QualType StarThisType =
5541 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
5542 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
5543 << AK << Val.getAsString(Info.Ctx, StarThisType);
5544 return false;
5545 }
5546 return true;
5547 }
5548
5549 CheckDynamicTypeHandler Handler{AK};
5550 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
5551}
5552
5553/// Check that the pointee of the 'this' pointer in a member function call is
5554/// either within its lifetime or in its period of construction or destruction.
5555static bool
5556checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5557 const LValue &This,
5558 const CXXMethodDecl *NamedMember) {
5559 return checkDynamicType(
5560 Info, E, This,
5561 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5562}
5563
5564struct DynamicType {
5565 /// The dynamic class type of the object.
5566 const CXXRecordDecl *Type;
5567 /// The corresponding path length in the lvalue.
5568 unsigned PathLength;
5569};
5570
5571static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5572 unsigned PathLength) {
5573 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=(static_cast <bool> (PathLength >= Designator.MostDerivedPathLength
&& PathLength <= Designator.Entries.size() &&
"invalid path length") ? void (0) : __assert_fail ("PathLength >= Designator.MostDerivedPathLength && PathLength <= Designator.Entries.size() && \"invalid path length\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5574, __extension__ __PRETTY_FUNCTION__))
5574 Designator.Entries.size() && "invalid path length")(static_cast <bool> (PathLength >= Designator.MostDerivedPathLength
&& PathLength <= Designator.Entries.size() &&
"invalid path length") ? void (0) : __assert_fail ("PathLength >= Designator.MostDerivedPathLength && PathLength <= Designator.Entries.size() && \"invalid path length\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5574, __extension__ __PRETTY_FUNCTION__))
;
5575 return (PathLength == Designator.MostDerivedPathLength)
5576 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5577 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5578}
5579
5580/// Determine the dynamic type of an object.
5581static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E,
5582 LValue &This, AccessKinds AK) {
5583 // If we don't have an lvalue denoting an object of class type, there is no
5584 // meaningful dynamic type. (We consider objects of non-class type to have no
5585 // dynamic type.)
5586 if (!checkDynamicType(Info, E, This, AK, true))
5587 return None;
5588
5589 // Refuse to compute a dynamic type in the presence of virtual bases. This
5590 // shouldn't happen other than in constant-folding situations, since literal
5591 // types can't have virtual bases.
5592 //
5593 // Note that consumers of DynamicType assume that the type has no virtual
5594 // bases, and will need modifications if this restriction is relaxed.
5595 const CXXRecordDecl *Class =
5596 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5597 if (!Class || Class->getNumVBases()) {
5598 Info.FFDiag(E);
5599 return None;
5600 }
5601
5602 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5603 // binary search here instead. But the overwhelmingly common case is that
5604 // we're not in the middle of a constructor, so it probably doesn't matter
5605 // in practice.
5606 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5607 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5608 PathLength <= Path.size(); ++PathLength) {
5609 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5610 Path.slice(0, PathLength))) {
5611 case ConstructionPhase::Bases:
5612 case ConstructionPhase::DestroyingBases:
5613 // We're constructing or destroying a base class. This is not the dynamic
5614 // type.
5615 break;
5616
5617 case ConstructionPhase::None:
5618 case ConstructionPhase::AfterBases:
5619 case ConstructionPhase::AfterFields:
5620 case ConstructionPhase::Destroying:
5621 // We've finished constructing the base classes and not yet started
5622 // destroying them again, so this is the dynamic type.
5623 return DynamicType{getBaseClassType(This.Designator, PathLength),
5624 PathLength};
5625 }
5626 }
5627
5628 // CWG issue 1517: we're constructing a base class of the object described by
5629 // 'This', so that object has not yet begun its period of construction and
5630 // any polymorphic operation on it results in undefined behavior.
5631 Info.FFDiag(E);
5632 return None;
5633}
5634
5635/// Perform virtual dispatch.
5636static const CXXMethodDecl *HandleVirtualDispatch(
5637 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5638 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5639 Optional<DynamicType> DynType = ComputeDynamicType(
5640 Info, E, This,
5641 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5642 if (!DynType)
5643 return nullptr;
5644
5645 // Find the final overrider. It must be declared in one of the classes on the
5646 // path from the dynamic type to the static type.
5647 // FIXME: If we ever allow literal types to have virtual base classes, that
5648 // won't be true.
5649 const CXXMethodDecl *Callee = Found;
5650 unsigned PathLength = DynType->PathLength;
5651 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5652 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5653 const CXXMethodDecl *Overrider =
5654 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5655 if (Overrider) {
5656 Callee = Overrider;
5657 break;
5658 }
5659 }
5660
5661 // C++2a [class.abstract]p6:
5662 // the effect of making a virtual call to a pure virtual function [...] is
5663 // undefined
5664 if (Callee->isPure()) {
5665 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5666 Info.Note(Callee->getLocation(), diag::note_declared_at);
5667 return nullptr;
5668 }
5669
5670 // If necessary, walk the rest of the path to determine the sequence of
5671 // covariant adjustment steps to apply.
5672 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5673 Found->getReturnType())) {
5674 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5675 for (unsigned CovariantPathLength = PathLength + 1;
5676 CovariantPathLength != This.Designator.Entries.size();
5677 ++CovariantPathLength) {
5678 const CXXRecordDecl *NextClass =
5679 getBaseClassType(This.Designator, CovariantPathLength);
5680 const CXXMethodDecl *Next =
5681 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5682 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5683 Next->getReturnType(), CovariantAdjustmentPath.back()))
5684 CovariantAdjustmentPath.push_back(Next->getReturnType());
5685 }
5686 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5687 CovariantAdjustmentPath.back()))
5688 CovariantAdjustmentPath.push_back(Found->getReturnType());
5689 }
5690
5691 // Perform 'this' adjustment.
5692 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5693 return nullptr;
5694
5695 return Callee;
5696}
5697
5698/// Perform the adjustment from a value returned by a virtual function to
5699/// a value of the statically expected type, which may be a pointer or
5700/// reference to a base class of the returned type.
5701static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5702 APValue &Result,
5703 ArrayRef<QualType> Path) {
5704 assert(Result.isLValue() &&(static_cast <bool> (Result.isLValue() && "unexpected kind of APValue for covariant return"
) ? void (0) : __assert_fail ("Result.isLValue() && \"unexpected kind of APValue for covariant return\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5705, __extension__ __PRETTY_FUNCTION__))
5705 "unexpected kind of APValue for covariant return")(static_cast <bool> (Result.isLValue() && "unexpected kind of APValue for covariant return"
) ? void (0) : __assert_fail ("Result.isLValue() && \"unexpected kind of APValue for covariant return\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5705, __extension__ __PRETTY_FUNCTION__))
;
5706 if (Result.isNullPointer())
5707 return true;
5708
5709 LValue LVal;
5710 LVal.setFrom(Info.Ctx, Result);
5711
5712 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5713 for (unsigned I = 1; I != Path.size(); ++I) {
5714 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5715 assert(OldClass && NewClass && "unexpected kind of covariant return")(static_cast <bool> (OldClass && NewClass &&
"unexpected kind of covariant return") ? void (0) : __assert_fail
("OldClass && NewClass && \"unexpected kind of covariant return\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5715, __extension__ __PRETTY_FUNCTION__))
;
5716 if (OldClass != NewClass &&
5717 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5718 return false;
5719 OldClass = NewClass;
5720 }
5721
5722 LVal.moveInto(Result);
5723 return true;
5724}
5725
5726/// Determine whether \p Base, which is known to be a direct base class of
5727/// \p Derived, is a public base class.
5728static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5729 const CXXRecordDecl *Base) {
5730 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5731 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5732 if (BaseClass && declaresSameEntity(BaseClass, Base))
5733 return BaseSpec.getAccessSpecifier() == AS_public;
5734 }
5735 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-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5735)
;
5736}
5737
5738/// Apply the given dynamic cast operation on the provided lvalue.
5739///
5740/// This implements the hard case of dynamic_cast, requiring a "runtime check"
5741/// to find a suitable target subobject.
5742static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5743 LValue &Ptr) {
5744 // We can't do anything with a non-symbolic pointer value.
5745 SubobjectDesignator &D = Ptr.Designator;
5746 if (D.Invalid)
5747 return false;
5748
5749 // C++ [expr.dynamic.cast]p6:
5750 // If v is a null pointer value, the result is a null pointer value.
5751 if (Ptr.isNullPointer() && !E->isGLValue())
5752 return true;
5753
5754 // For all the other cases, we need the pointer to point to an object within
5755 // its lifetime / period of construction / destruction, and we need to know
5756 // its dynamic type.
5757 Optional<DynamicType> DynType =
5758 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5759 if (!DynType)
5760 return false;
5761
5762 // C++ [expr.dynamic.cast]p7:
5763 // If T is "pointer to cv void", then the result is a pointer to the most
5764 // derived object
5765 if (E->getType()->isVoidPointerType())
5766 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5767
5768 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5769 assert(C && "dynamic_cast target is not void pointer nor class")(static_cast <bool> (C && "dynamic_cast target is not void pointer nor class"
) ? void (0) : __assert_fail ("C && \"dynamic_cast target is not void pointer nor class\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5769, __extension__ __PRETTY_FUNCTION__))
;
5770 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5771
5772 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5773 // C++ [expr.dynamic.cast]p9:
5774 if (!E->isGLValue()) {
5775 // The value of a failed cast to pointer type is the null pointer value
5776 // of the required result type.
5777 Ptr.setNull(Info.Ctx, E->getType());
5778 return true;
5779 }
5780
5781 // A failed cast to reference type throws [...] std::bad_cast.
5782 unsigned DiagKind;
5783 if (!Paths && (declaresSameEntity(DynType->Type, C) ||
5784 DynType->Type->isDerivedFrom(C)))
5785 DiagKind = 0;
5786 else if (!Paths || Paths->begin() == Paths->end())
5787 DiagKind = 1;
5788 else if (Paths->isAmbiguous(CQT))
5789 DiagKind = 2;
5790 else {
5791 assert(Paths->front().Access != AS_public && "why did the cast fail?")(static_cast <bool> (Paths->front().Access != AS_public
&& "why did the cast fail?") ? void (0) : __assert_fail
("Paths->front().Access != AS_public && \"why did the cast fail?\""
, "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5791, __extension__ __PRETTY_FUNCTION__))
;
5792 DiagKind = 3;
5793 }
5794 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
5795 << DiagKind << Ptr.Designator.getType(Info.Ctx)
5796 << Info.Ctx.getRecordType(DynType->Type)
5797 << E->getType().getUnqualifiedType();
5798 return false;
5799 };
5800
5801 // Runtime check, phase 1:
5802 // Walk from the base subobject towards the derived object looking for the
5803 // target type.
5804 for (int PathLength = Ptr.Designator.Entries.size();
5805 PathLength >= (int)DynType->PathLength; --PathLength) {
5806 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
5807 if (declaresSameEntity(Class, C))
5808 return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
5809 // We can only walk across public inheritance edges.
5810 if (PathLength > (int)DynType->PathLength &&
5811 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
5812 Class))
5813 return RuntimeCheckFailed(nullptr);
5814 }
5815
5816 // Runtime check, phase 2:
5817 // Search the dynamic type for an unambiguous public base of type C.
5818 CXXBasePaths Paths(/*FindAmbiguities=*/true,
5819 /*RecordPaths=*/true, /*DetectVirtual=*/false);
5820 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
5821 Paths.front().Access == AS_public) {
5822 // Downcast to the dynamic type...
5823 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
5824 return false;
5825 // ... then upcast to the chosen base class subobject.
5826 for (CXXBasePathElement &Elem : Paths.front())
5827 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
5828 return false;
5829 return true;
5830 }
5831
5832 // Otherwise, the runtime check fails.
5833 return RuntimeCheckFailed(&Paths);
5834}
5835
5836namespace {
5837struct StartLifetimeOfUnionMemberHandler {
5838 EvalInfo &Info;
5839 const Expr *LHSExpr;
5840 const FieldDecl *Field;
5841 bool DuringInit;
5842 bool Failed = false;
5843 static const AccessKinds AccessKind = AK_Assign;
5844
5845 typedef bool result_type;
5846 bool failed() { return Failed; }
5847 bool found(APValue &Subobj, QualType SubobjType) {
5848 // We are supposed to perform no initialization but begin the lifetime of
5849 // the object. We interpret that as meaning to do what default
5850 // initialization of the object would do if all constructors involved were
5851 // trivial:
5852 // * All base, non-variant member, and array element subobjects' lifetimes
5853 // begin
5854 // * No variant members' lifetimes begin
5855 // * All scalar subobjects whose lifetimes begin have indeterminate values
5856 assert(SubobjType->isUnionType())(static_cast <bool> (SubobjType->isUnionType()) ? void
(0) : __assert_fail ("SubobjType->isUnionType()", "/build/llvm-toolchain-snapshot-13~++20210726100616+dead50d4427c/clang/lib/AST/ExprConstant.cpp"
, 5856, __extension__ __PRETTY_FUNCTION__))
;
5857 if (declaresSameEntity(Subobj.getUnionField(), Field)) {
5858 // This union member is already active. If it's also in-lifetime, there's
5859 // nothing to do.
5860 if (Subobj.getUnionValue().hasValue())
5861 return true;
5862 } else if (DuringInit) {
5863 // We're currently in the process of initializing a different union
5864 // member. If we carried on, that initialization would attempt to
5865 // store to an inactive union member, resulting in undefined behavior.
5866 Info.FFDiag(LHSExpr,
5867 diag::note_constexpr_union_member_change_during_init);
5868 return false;
5869 }