Bug Summary

File:build/source/clang/lib/AST/ExprConstant.cpp
Warning:line 6059, column 57
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name ExprConstant.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -I tools/clang/lib/AST -I /build/source/clang/lib/AST -I /build/source/clang/include -I tools/clang/include -I include -I /build/source/llvm/include -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-05-10-133810-16478-1 -x c++ /build/source/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/SmallBitVector.h"
56#include "llvm/Support/Debug.h"
57#include "llvm/Support/SaveAndRestore.h"
58#include "llvm/Support/TimeProfiler.h"
59#include "llvm/Support/raw_ostream.h"
60#include <cstring>
61#include <functional>
62#include <optional>
63
64#define DEBUG_TYPE"exprconstant" "exprconstant"
65
66using namespace clang;
67using llvm::APFixedPoint;
68using llvm::APInt;
69using llvm::APSInt;
70using llvm::APFloat;
71using llvm::FixedPointSemantics;
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",
"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",
"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\""
, "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\""
, "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\""
, "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?\""
, "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\""
, "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\""
, "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\""
, "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\""
, "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", "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\""
, "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\""
, "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\""
, "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\""
, "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 ValueDecl *, 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 return nullptr;
596 }
597
598 // Return the current temporary for Key in the map.
599 APValue *getCurrentTemporary(const void *Key) {
600 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
601 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
602 return &std::prev(UB)->second;
603 return nullptr;
604 }
605
606 // Return the version number of the current temporary for Key.
607 unsigned getCurrentTemporaryVersion(const void *Key) const {
608 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
609 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
610 return std::prev(UB)->first.second;
611 return 0;
612 }
613
614 /// Allocate storage for an object of type T in this stack frame.
615 /// Populates LV with a handle to the created object. Key identifies
616 /// the temporary within the stack frame, and must not be reused without
617 /// bumping the temporary version number.
618 template<typename KeyT>
619 APValue &createTemporary(const KeyT *Key, QualType T,
620 ScopeKind Scope, LValue &LV);
621
622 /// Allocate storage for a parameter of a function call made in this frame.
623 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
624
625 void describe(llvm::raw_ostream &OS) override;
626
627 Frame *getCaller() const override { return Caller; }
628 SourceLocation getCallLocation() const override { return CallLoc; }
629 const FunctionDecl *getCallee() const override { return Callee; }
630
631 bool isStdFunction() const {
632 for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
633 if (DC->isStdNamespace())
634 return true;
635 return false;
636 }
637
638 private:
639 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
640 ScopeKind Scope);
641 };
642
643 /// Temporarily override 'this'.
644 class ThisOverrideRAII {
645 public:
646 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
647 : Frame(Frame), OldThis(Frame.This) {
648 if (Enable)
649 Frame.This = NewThis;
650 }
651 ~ThisOverrideRAII() {
652 Frame.This = OldThis;
653 }
654 private:
655 CallStackFrame &Frame;
656 const LValue *OldThis;
657 };
658
659 // A shorthand time trace scope struct, prints source range, for example
660 // {"name":"EvaluateAsRValue","args":{"detail":"<test.cc:8:21, col:25>"}}}
661 class ExprTimeTraceScope {
662 public:
663 ExprTimeTraceScope(const Expr *E, const ASTContext &Ctx, StringRef Name)
664 : TimeScope(Name, [E, &Ctx] {
665 return E->getSourceRange().printToString(Ctx.getSourceManager());
666 }) {}
667
668 private:
669 llvm::TimeTraceScope TimeScope;
670 };
671}
672
673static bool HandleDestruction(EvalInfo &Info, const Expr *E,
674 const LValue &This, QualType ThisType);
675static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
676 APValue::LValueBase LVBase, APValue &Value,
677 QualType T);
678
679namespace {
680 /// A cleanup, and a flag indicating whether it is lifetime-extended.
681 class Cleanup {
682 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
683 APValue::LValueBase Base;
684 QualType T;
685
686 public:
687 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
688 ScopeKind Scope)
689 : Value(Val, Scope), Base(Base), T(T) {}
690
691 /// Determine whether this cleanup should be performed at the end of the
692 /// given kind of scope.
693 bool isDestroyedAtEndOf(ScopeKind K) const {
694 return (int)Value.getInt() >= (int)K;
695 }
696 bool endLifetime(EvalInfo &Info, bool RunDestructors) {
697 if (RunDestructors) {
698 SourceLocation Loc;
699 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
700 Loc = VD->getLocation();
701 else if (const Expr *E = Base.dyn_cast<const Expr*>())
702 Loc = E->getExprLoc();
703 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
704 }
705 *Value.getPointer() = APValue();
706 return true;
707 }
708
709 bool hasSideEffect() {
710 return T.isDestructedType();
711 }
712 };
713
714 /// A reference to an object whose construction we are currently evaluating.
715 struct ObjectUnderConstruction {
716 APValue::LValueBase Base;
717 ArrayRef<APValue::LValuePathEntry> Path;
718 friend bool operator==(const ObjectUnderConstruction &LHS,
719 const ObjectUnderConstruction &RHS) {
720 return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
721 }
722 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
723 return llvm::hash_combine(Obj.Base, Obj.Path);
724 }
725 };
726 enum class ConstructionPhase {
727 None,
728 Bases,
729 AfterBases,
730 AfterFields,
731 Destroying,
732 DestroyingBases
733 };
734}
735
736namespace llvm {
737template<> struct DenseMapInfo<ObjectUnderConstruction> {
738 using Base = DenseMapInfo<APValue::LValueBase>;
739 static ObjectUnderConstruction getEmptyKey() {
740 return {Base::getEmptyKey(), {}}; }
741 static ObjectUnderConstruction getTombstoneKey() {
742 return {Base::getTombstoneKey(), {}};
743 }
744 static unsigned getHashValue(const ObjectUnderConstruction &Object) {
745 return hash_value(Object);
746 }
747 static bool isEqual(const ObjectUnderConstruction &LHS,
748 const ObjectUnderConstruction &RHS) {
749 return LHS == RHS;
750 }
751};
752}
753
754namespace {
755 /// A dynamically-allocated heap object.
756 struct DynAlloc {
757 /// The value of this heap-allocated object.
758 APValue Value;
759 /// The allocating expression; used for diagnostics. Either a CXXNewExpr
760 /// or a CallExpr (the latter is for direct calls to operator new inside
761 /// std::allocator<T>::allocate).
762 const Expr *AllocExpr = nullptr;
763
764 enum Kind {
765 New,
766 ArrayNew,
767 StdAllocator
768 };
769
770 /// Get the kind of the allocation. This must match between allocation
771 /// and deallocation.
772 Kind getKind() const {
773 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
774 return NE->isArray() ? ArrayNew : New;
775 assert(isa<CallExpr>(AllocExpr))(static_cast <bool> (isa<CallExpr>(AllocExpr)) ? void
(0) : __assert_fail ("isa<CallExpr>(AllocExpr)", "clang/lib/AST/ExprConstant.cpp"
, 775, __extension__ __PRETTY_FUNCTION__))
;
776 return StdAllocator;
777 }
778 };
779
780 struct DynAllocOrder {
781 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
782 return L.getIndex() < R.getIndex();
783 }
784 };
785
786 /// EvalInfo - This is a private struct used by the evaluator to capture
787 /// information about a subexpression as it is folded. It retains information
788 /// about the AST context, but also maintains information about the folded
789 /// expression.
790 ///
791 /// If an expression could be evaluated, it is still possible it is not a C
792 /// "integer constant expression" or constant expression. If not, this struct
793 /// captures information about how and why not.
794 ///
795 /// One bit of information passed *into* the request for constant folding
796 /// indicates whether the subexpression is "evaluated" or not according to C
797 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
798 /// evaluate the expression regardless of what the RHS is, but C only allows
799 /// certain things in certain situations.
800 class EvalInfo : public interp::State {
801 public:
802 ASTContext &Ctx;
803
804 /// EvalStatus - Contains information about the evaluation.
805 Expr::EvalStatus &EvalStatus;
806
807 /// CurrentCall - The top of the constexpr call stack.
808 CallStackFrame *CurrentCall;
809
810 /// CallStackDepth - The number of calls in the call stack right now.
811 unsigned CallStackDepth;
812
813 /// NextCallIndex - The next call index to assign.
814 unsigned NextCallIndex;
815
816 /// StepsLeft - The remaining number of evaluation steps we're permitted
817 /// to perform. This is essentially a limit for the number of statements
818 /// we will evaluate.
819 unsigned StepsLeft;
820
821 /// Enable the experimental new constant interpreter. If an expression is
822 /// not supported by the interpreter, an error is triggered.
823 bool EnableNewConstInterp;
824
825 /// BottomFrame - The frame in which evaluation started. This must be
826 /// initialized after CurrentCall and CallStackDepth.
827 CallStackFrame BottomFrame;
828
829 /// A stack of values whose lifetimes end at the end of some surrounding
830 /// evaluation frame.
831 llvm::SmallVector<Cleanup, 16> CleanupStack;
832
833 /// EvaluatingDecl - This is the declaration whose initializer is being
834 /// evaluated, if any.
835 APValue::LValueBase EvaluatingDecl;
836
837 enum class EvaluatingDeclKind {
838 None,
839 /// We're evaluating the construction of EvaluatingDecl.
840 Ctor,
841 /// We're evaluating the destruction of EvaluatingDecl.
842 Dtor,
843 };
844 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
845
846 /// EvaluatingDeclValue - This is the value being constructed for the
847 /// declaration whose initializer is being evaluated, if any.
848 APValue *EvaluatingDeclValue;
849
850 /// Set of objects that are currently being constructed.
851 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
852 ObjectsUnderConstruction;
853
854 /// Current heap allocations, along with the location where each was
855 /// allocated. We use std::map here because we need stable addresses
856 /// for the stored APValues.
857 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
858
859 /// The number of heap allocations performed so far in this evaluation.
860 unsigned NumHeapAllocs = 0;
861
862 struct EvaluatingConstructorRAII {
863 EvalInfo &EI;
864 ObjectUnderConstruction Object;
865 bool DidInsert;
866 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
867 bool HasBases)
868 : EI(EI), Object(Object) {
869 DidInsert =
870 EI.ObjectsUnderConstruction
871 .insert({Object, HasBases ? ConstructionPhase::Bases
872 : ConstructionPhase::AfterBases})
873 .second;
874 }
875 void finishedConstructingBases() {
876 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
877 }
878 void finishedConstructingFields() {
879 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
880 }
881 ~EvaluatingConstructorRAII() {
882 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
883 }
884 };
885
886 struct EvaluatingDestructorRAII {
887 EvalInfo &EI;
888 ObjectUnderConstruction Object;
889 bool DidInsert;
890 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
891 : EI(EI), Object(Object) {
892 DidInsert = EI.ObjectsUnderConstruction
893 .insert({Object, ConstructionPhase::Destroying})
894 .second;
895 }
896 void startedDestroyingBases() {
897 EI.ObjectsUnderConstruction[Object] =
898 ConstructionPhase::DestroyingBases;
899 }
900 ~EvaluatingDestructorRAII() {
901 if (DidInsert)
902 EI.ObjectsUnderConstruction.erase(Object);
903 }
904 };
905
906 ConstructionPhase
907 isEvaluatingCtorDtor(APValue::LValueBase Base,
908 ArrayRef<APValue::LValuePathEntry> Path) {
909 return ObjectsUnderConstruction.lookup({Base, Path});
910 }
911
912 /// If we're currently speculatively evaluating, the outermost call stack
913 /// depth at which we can mutate state, otherwise 0.
914 unsigned SpeculativeEvaluationDepth = 0;
915
916 /// The current array initialization index, if we're performing array
917 /// initialization.
918 uint64_t ArrayInitIndex = -1;
919
920 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
921 /// notes attached to it will also be stored, otherwise they will not be.
922 bool HasActiveDiagnostic;
923
924 /// Have we emitted a diagnostic explaining why we couldn't constant
925 /// fold (not just why it's not strictly a constant expression)?
926 bool HasFoldFailureDiagnostic;
927
928 /// Whether we're checking that an expression is a potential constant
929 /// expression. If so, do not fail on constructs that could become constant
930 /// later on (such as a use of an undefined global).
931 bool CheckingPotentialConstantExpression = false;
932
933 /// Whether we're checking for an expression that has undefined behavior.
934 /// If so, we will produce warnings if we encounter an operation that is
935 /// always undefined.
936 ///
937 /// Note that we still need to evaluate the expression normally when this
938 /// is set; this is used when evaluating ICEs in C.
939 bool CheckingForUndefinedBehavior = false;
940
941 enum EvaluationMode {
942 /// Evaluate as a constant expression. Stop if we find that the expression
943 /// is not a constant expression.
944 EM_ConstantExpression,
945
946 /// Evaluate as a constant expression. Stop if we find that the expression
947 /// is not a constant expression. Some expressions can be retried in the
948 /// optimizer if we don't constant fold them here, but in an unevaluated
949 /// context we try to fold them immediately since the optimizer never
950 /// gets a chance to look at it.
951 EM_ConstantExpressionUnevaluated,
952
953 /// Fold the expression to a constant. Stop if we hit a side-effect that
954 /// we can't model.
955 EM_ConstantFold,
956
957 /// Evaluate in any way we know how. Don't worry about side-effects that
958 /// can't be modeled.
959 EM_IgnoreSideEffects,
960 } EvalMode;
961
962 /// Are we checking whether the expression is a potential constant
963 /// expression?
964 bool checkingPotentialConstantExpression() const override {
965 return CheckingPotentialConstantExpression;
966 }
967
968 /// Are we checking an expression for overflow?
969 // FIXME: We should check for any kind of undefined or suspicious behavior
970 // in such constructs, not just overflow.
971 bool checkingForUndefinedBehavior() const override {
972 return CheckingForUndefinedBehavior;
973 }
974
975 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
976 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
977 CallStackDepth(0), NextCallIndex(1),
978 StepsLeft(C.getLangOpts().ConstexprStepLimit),
979 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
980 BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
981 EvaluatingDecl((const ValueDecl *)nullptr),
982 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
983 HasFoldFailureDiagnostic(false), EvalMode(Mode) {}
984
985 ~EvalInfo() {
986 discardCleanups();
987 }
988
989 ASTContext &getCtx() const override { return Ctx; }
990
991 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
992 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
993 EvaluatingDecl = Base;
994 IsEvaluatingDecl = EDK;
995 EvaluatingDeclValue = &Value;
996 }
997
998 bool CheckCallLimit(SourceLocation Loc) {
999 // Don't perform any constexpr calls (other than the call we're checking)
1000 // when checking a potential constant expression.
1001 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
1002 return false;
1003 if (NextCallIndex == 0) {
1004 // NextCallIndex has wrapped around.
1005 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1006 return false;
1007 }
1008 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1009 return true;
1010 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1011 << getLangOpts().ConstexprCallDepth;
1012 return false;
1013 }
1014
1015 std::pair<CallStackFrame *, unsigned>
1016 getCallFrameAndDepth(unsigned CallIndex) {
1017 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\""
, "clang/lib/AST/ExprConstant.cpp", 1017, __extension__ __PRETTY_FUNCTION__
))
;
1018 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
1019 // be null in this loop.
1020 unsigned Depth = CallStackDepth;
1021 CallStackFrame *Frame = CurrentCall;
1022 while (Frame->Index > CallIndex) {
1023 Frame = Frame->Caller;
1024 --Depth;
1025 }
1026 if (Frame->Index == CallIndex)
1027 return {Frame, Depth};
1028 return {nullptr, 0};
1029 }
1030
1031 bool nextStep(const Stmt *S) {
1032 if (!StepsLeft) {
1033 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1034 return false;
1035 }
1036 --StepsLeft;
1037 return true;
1038 }
1039
1040 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1041
1042 std::optional<DynAlloc *> lookupDynamicAlloc(DynamicAllocLValue DA) {
1043 std::optional<DynAlloc *> Result;
1044 auto It = HeapAllocs.find(DA);
1045 if (It != HeapAllocs.end())
1046 Result = &It->second;
1047 return Result;
1048 }
1049
1050 /// Get the allocated storage for the given parameter of the given call.
1051 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1052 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
1053 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
1054 : nullptr;
1055 }
1056
1057 /// Information about a stack frame for std::allocator<T>::[de]allocate.
1058 struct StdAllocatorCaller {
1059 unsigned FrameIndex;
1060 QualType ElemType;
1061 explicit operator bool() const { return FrameIndex != 0; };
1062 };
1063
1064 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1065 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1066 Call = Call->Caller) {
1067 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
1068 if (!MD)
1069 continue;
1070 const IdentifierInfo *FnII = MD->getIdentifier();
1071 if (!FnII || !FnII->isStr(FnName))
1072 continue;
1073
1074 const auto *CTSD =
1075 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
1076 if (!CTSD)
1077 continue;
1078
1079 const IdentifierInfo *ClassII = CTSD->getIdentifier();
1080 const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1081 if (CTSD->isInStdNamespace() && ClassII &&
1082 ClassII->isStr("allocator") && TAL.size() >= 1 &&
1083 TAL[0].getKind() == TemplateArgument::Type)
1084 return {Call->Index, TAL[0].getAsType()};
1085 }
1086
1087 return {};
1088 }
1089
1090 void performLifetimeExtension() {
1091 // Disable the cleanups for lifetime-extended temporaries.
1092 llvm::erase_if(CleanupStack, [](Cleanup &C) {
1093 return !C.isDestroyedAtEndOf(ScopeKind::FullExpression);
1094 });
1095 }
1096
1097 /// Throw away any remaining cleanups at the end of evaluation. If any
1098 /// cleanups would have had a side-effect, note that as an unmodeled
1099 /// side-effect and return false. Otherwise, return true.
1100 bool discardCleanups() {
1101 for (Cleanup &C : CleanupStack) {
1102 if (C.hasSideEffect() && !noteSideEffect()) {
1103 CleanupStack.clear();
1104 return false;
1105 }
1106 }
1107 CleanupStack.clear();
1108 return true;
1109 }
1110
1111 private:
1112 interp::Frame *getCurrentFrame() override { return CurrentCall; }
1113 const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1114
1115 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
1116 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1117
1118 void setFoldFailureDiagnostic(bool Flag) override {
1119 HasFoldFailureDiagnostic = Flag;
1120 }
1121
1122 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1123
1124 // If we have a prior diagnostic, it will be noting that the expression
1125 // isn't a constant expression. This diagnostic is more important,
1126 // unless we require this evaluation to produce a constant expression.
1127 //
1128 // FIXME: We might want to show both diagnostics to the user in
1129 // EM_ConstantFold mode.
1130 bool hasPriorDiagnostic() override {
1131 if (!EvalStatus.Diag->empty()) {
1132 switch (EvalMode) {
1133 case EM_ConstantFold:
1134 case EM_IgnoreSideEffects:
1135 if (!HasFoldFailureDiagnostic)
1136 break;
1137 // We've already failed to fold something. Keep that diagnostic.
1138 [[fallthrough]];
1139 case EM_ConstantExpression:
1140 case EM_ConstantExpressionUnevaluated:
1141 setActiveDiagnostic(false);
1142 return true;
1143 }
1144 }
1145 return false;
1146 }
1147
1148 unsigned getCallStackDepth() override { return CallStackDepth; }
1149
1150 public:
1151 /// Should we continue evaluation after encountering a side-effect that we
1152 /// couldn't model?
1153 bool keepEvaluatingAfterSideEffect() {
1154 switch (EvalMode) {
1155 case EM_IgnoreSideEffects:
1156 return true;
1157
1158 case EM_ConstantExpression:
1159 case EM_ConstantExpressionUnevaluated:
1160 case EM_ConstantFold:
1161 // By default, assume any side effect might be valid in some other
1162 // evaluation of this expression from a different context.
1163 return checkingPotentialConstantExpression() ||
1164 checkingForUndefinedBehavior();
1165 }
1166 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "clang/lib/AST/ExprConstant.cpp"
, 1166)
;
1167 }
1168
1169 /// Note that we have had a side-effect, and determine whether we should
1170 /// keep evaluating.
1171 bool noteSideEffect() {
1172 EvalStatus.HasSideEffects = true;
1173 return keepEvaluatingAfterSideEffect();
1174 }
1175
1176 /// Should we continue evaluation after encountering undefined behavior?
1177 bool keepEvaluatingAfterUndefinedBehavior() {
1178 switch (EvalMode) {
1179 case EM_IgnoreSideEffects:
1180 case EM_ConstantFold:
1181 return true;
1182
1183 case EM_ConstantExpression:
1184 case EM_ConstantExpressionUnevaluated:
1185 return checkingForUndefinedBehavior();
1186 }
1187 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "clang/lib/AST/ExprConstant.cpp"
, 1187)
;
1188 }
1189
1190 /// Note that we hit something that was technically undefined behavior, but
1191 /// that we can evaluate past it (such as signed overflow or floating-point
1192 /// division by zero.)
1193 bool noteUndefinedBehavior() override {
1194 EvalStatus.HasUndefinedBehavior = true;
1195 return keepEvaluatingAfterUndefinedBehavior();
1196 }
1197
1198 /// Should we continue evaluation as much as possible after encountering a
1199 /// construct which can't be reduced to a value?
1200 bool keepEvaluatingAfterFailure() const override {
1201 if (!StepsLeft)
1202 return false;
1203
1204 switch (EvalMode) {
1205 case EM_ConstantExpression:
1206 case EM_ConstantExpressionUnevaluated:
1207 case EM_ConstantFold:
1208 case EM_IgnoreSideEffects:
1209 return checkingPotentialConstantExpression() ||
1210 checkingForUndefinedBehavior();
1211 }
1212 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "clang/lib/AST/ExprConstant.cpp"
, 1212)
;
1213 }
1214
1215 /// Notes that we failed to evaluate an expression that other expressions
1216 /// directly depend on, and determine if we should keep evaluating. This
1217 /// should only be called if we actually intend to keep evaluating.
1218 ///
1219 /// Call noteSideEffect() instead if we may be able to ignore the value that
1220 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1221 ///
1222 /// (Foo(), 1) // use noteSideEffect
1223 /// (Foo() || true) // use noteSideEffect
1224 /// Foo() + 1 // use noteFailure
1225 [[nodiscard]] bool noteFailure() {
1226 // Failure when evaluating some expression often means there is some
1227 // subexpression whose evaluation was skipped. Therefore, (because we
1228 // don't track whether we skipped an expression when unwinding after an
1229 // evaluation failure) every evaluation failure that bubbles up from a
1230 // subexpression implies that a side-effect has potentially happened. We
1231 // skip setting the HasSideEffects flag to true until we decide to
1232 // continue evaluating after that point, which happens here.
1233 bool KeepGoing = keepEvaluatingAfterFailure();
1234 EvalStatus.HasSideEffects |= KeepGoing;
1235 return KeepGoing;
1236 }
1237
1238 class ArrayInitLoopIndex {
1239 EvalInfo &Info;
1240 uint64_t OuterIndex;
1241
1242 public:
1243 ArrayInitLoopIndex(EvalInfo &Info)
1244 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1245 Info.ArrayInitIndex = 0;
1246 }
1247 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1248
1249 operator uint64_t&() { return Info.ArrayInitIndex; }
1250 };
1251 };
1252
1253 /// Object used to treat all foldable expressions as constant expressions.
1254 struct FoldConstant {
1255 EvalInfo &Info;
1256 bool Enabled;
1257 bool HadNoPriorDiags;
1258 EvalInfo::EvaluationMode OldMode;
1259
1260 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1261 : Info(Info),
1262 Enabled(Enabled),
1263 HadNoPriorDiags(Info.EvalStatus.Diag &&
1264 Info.EvalStatus.Diag->empty() &&
1265 !Info.EvalStatus.HasSideEffects),
1266 OldMode(Info.EvalMode) {
1267 if (Enabled)
1268 Info.EvalMode = EvalInfo::EM_ConstantFold;
1269 }
1270 void keepDiagnostics() { Enabled = false; }
1271 ~FoldConstant() {
1272 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1273 !Info.EvalStatus.HasSideEffects)
1274 Info.EvalStatus.Diag->clear();
1275 Info.EvalMode = OldMode;
1276 }
1277 };
1278
1279 /// RAII object used to set the current evaluation mode to ignore
1280 /// side-effects.
1281 struct IgnoreSideEffectsRAII {
1282 EvalInfo &Info;
1283 EvalInfo::EvaluationMode OldMode;
1284 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1285 : Info(Info), OldMode(Info.EvalMode) {
1286 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1287 }
1288
1289 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1290 };
1291
1292 /// RAII object used to optionally suppress diagnostics and side-effects from
1293 /// a speculative evaluation.
1294 class SpeculativeEvaluationRAII {
1295 EvalInfo *Info = nullptr;
1296 Expr::EvalStatus OldStatus;
1297 unsigned OldSpeculativeEvaluationDepth;
1298
1299 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1300 Info = Other.Info;
1301 OldStatus = Other.OldStatus;
1302 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1303 Other.Info = nullptr;
1304 }
1305
1306 void maybeRestoreState() {
1307 if (!Info)
1308 return;
1309
1310 Info->EvalStatus = OldStatus;
1311 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1312 }
1313
1314 public:
1315 SpeculativeEvaluationRAII() = default;
1316
1317 SpeculativeEvaluationRAII(
1318 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1319 : Info(&Info), OldStatus(Info.EvalStatus),
1320 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1321 Info.EvalStatus.Diag = NewDiag;
1322 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1323 }
1324
1325 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1326 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1327 moveFromAndCancel(std::move(Other));
1328 }
1329
1330 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1331 maybeRestoreState();
1332 moveFromAndCancel(std::move(Other));
1333 return *this;
1334 }
1335
1336 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1337 };
1338
1339 /// RAII object wrapping a full-expression or block scope, and handling
1340 /// the ending of the lifetime of temporaries created within it.
1341 template<ScopeKind Kind>
1342 class ScopeRAII {
1343 EvalInfo &Info;
1344 unsigned OldStackSize;
1345 public:
1346 ScopeRAII(EvalInfo &Info)
1347 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1348 // Push a new temporary version. This is needed to distinguish between
1349 // temporaries created in different iterations of a loop.
1350 Info.CurrentCall->pushTempVersion();
1351 }
1352 bool destroy(bool RunDestructors = true) {
1353 bool OK = cleanup(Info, RunDestructors, OldStackSize);
1354 OldStackSize = -1U;
1355 return OK;
1356 }
1357 ~ScopeRAII() {
1358 if (OldStackSize != -1U)
1359 destroy(false);
1360 // Body moved to a static method to encourage the compiler to inline away
1361 // instances of this class.
1362 Info.CurrentCall->popTempVersion();
1363 }
1364 private:
1365 static bool cleanup(EvalInfo &Info, bool RunDestructors,
1366 unsigned OldStackSize) {
1367 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?\""
, "clang/lib/AST/ExprConstant.cpp", 1368, __extension__ __PRETTY_FUNCTION__
))
1368 "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?\""
, "clang/lib/AST/ExprConstant.cpp", 1368, __extension__ __PRETTY_FUNCTION__
))
;
1369
1370 // Run all cleanups for a block scope, and non-lifetime-extended cleanups
1371 // for a full-expression scope.
1372 bool Success = true;
1373 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1374 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
1375 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1376 Success = false;
1377 break;
1378 }
1379 }
1380 }
1381
1382 // Compact any retained cleanups.
1383 auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1384 if (Kind != ScopeKind::Block)
1385 NewEnd =
1386 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1387 return C.isDestroyedAtEndOf(Kind);
1388 });
1389 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
1390 return Success;
1391 }
1392 };
1393 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1394 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1395 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1396}
1397
1398bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1399 CheckSubobjectKind CSK) {
1400 if (Invalid)
1401 return false;
1402 if (isOnePastTheEnd()) {
1403 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1404 << CSK;
1405 setInvalid();
1406 return false;
1407 }
1408 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1409 // must actually be at least one array element; even a VLA cannot have a
1410 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1411 return true;
1412}
1413
1414void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1415 const Expr *E) {
1416 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1417 // Do not set the designator as invalid: we can represent this situation,
1418 // and correct handling of __builtin_object_size requires us to do so.
1419}
1420
1421void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1422 const Expr *E,
1423 const APSInt &N) {
1424 // If we're complaining, we must be able to statically determine the size of
1425 // the most derived array.
1426 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1427 Info.CCEDiag(E, diag::note_constexpr_array_index)
1428 << N << /*array*/ 0
1429 << static_cast<unsigned>(getMostDerivedArraySize());
1430 else
1431 Info.CCEDiag(E, diag::note_constexpr_array_index)
1432 << N << /*non-array*/ 1;
1433 setInvalid();
1434}
1435
1436CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1437 const FunctionDecl *Callee, const LValue *This,
1438 CallRef Call)
1439 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1440 Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1441 Info.CurrentCall = this;
1442 ++Info.CallStackDepth;
1443}
1444
1445CallStackFrame::~CallStackFrame() {
1446 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\""
, "clang/lib/AST/ExprConstant.cpp", 1446, __extension__ __PRETTY_FUNCTION__
))
;
1447 --Info.CallStackDepth;
1448 Info.CurrentCall = Caller;
1449}
1450
1451static bool isRead(AccessKinds AK) {
1452 return AK == AK_Read || AK == AK_ReadObjectRepresentation;
1453}
1454
1455static bool isModification(AccessKinds AK) {
1456 switch (AK) {
1457 case AK_Read:
1458 case AK_ReadObjectRepresentation:
1459 case AK_MemberCall:
1460 case AK_DynamicCast:
1461 case AK_TypeId:
1462 return false;
1463 case AK_Assign:
1464 case AK_Increment:
1465 case AK_Decrement:
1466 case AK_Construct:
1467 case AK_Destroy:
1468 return true;
1469 }
1470 llvm_unreachable("unknown access kind")::llvm::llvm_unreachable_internal("unknown access kind", "clang/lib/AST/ExprConstant.cpp"
, 1470)
;
1471}
1472
1473static bool isAnyAccess(AccessKinds AK) {
1474 return isRead(AK) || isModification(AK);
1475}
1476
1477/// Is this an access per the C++ definition?
1478static bool isFormalAccess(AccessKinds AK) {
1479 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
1480}
1481
1482/// Is this kind of axcess valid on an indeterminate object value?
1483static bool isValidIndeterminateAccess(AccessKinds AK) {
1484 switch (AK) {
1485 case AK_Read:
1486 case AK_Increment:
1487 case AK_Decrement:
1488 // These need the object's value.
1489 return false;
1490
1491 case AK_ReadObjectRepresentation:
1492 case AK_Assign:
1493 case AK_Construct:
1494 case AK_Destroy:
1495 // Construction and destruction don't need the value.
1496 return true;
1497
1498 case AK_MemberCall:
1499 case AK_DynamicCast:
1500 case AK_TypeId:
1501 // These aren't really meaningful on scalars.
1502 return true;
1503 }
1504 llvm_unreachable("unknown access kind")::llvm::llvm_unreachable_internal("unknown access kind", "clang/lib/AST/ExprConstant.cpp"
, 1504)
;
1505}
1506
1507namespace {
1508 struct ComplexValue {
1509 private:
1510 bool IsInt;
1511
1512 public:
1513 APSInt IntReal, IntImag;
1514 APFloat FloatReal, FloatImag;
1515
1516 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1517
1518 void makeComplexFloat() { IsInt = false; }
1519 bool isComplexFloat() const { return !IsInt; }
1520 APFloat &getComplexFloatReal() { return FloatReal; }
1521 APFloat &getComplexFloatImag() { return FloatImag; }
1522
1523 void makeComplexInt() { IsInt = true; }
1524 bool isComplexInt() const { return IsInt; }
1525 APSInt &getComplexIntReal() { return IntReal; }
1526 APSInt &getComplexIntImag() { return IntImag; }
1527
1528 void moveInto(APValue &v) const {
1529 if (isComplexFloat())
1530 v = APValue(FloatReal, FloatImag);
1531 else
1532 v = APValue(IntReal, IntImag);
1533 }
1534 void setFrom(const APValue &v) {
1535 assert(v.isComplexFloat() || v.isComplexInt())(static_cast <bool> (v.isComplexFloat() || v.isComplexInt
()) ? void (0) : __assert_fail ("v.isComplexFloat() || v.isComplexInt()"
, "clang/lib/AST/ExprConstant.cpp", 1535, __extension__ __PRETTY_FUNCTION__
))
;
1536 if (v.isComplexFloat()) {
1537 makeComplexFloat();
1538 FloatReal = v.getComplexFloatReal();
1539 FloatImag = v.getComplexFloatImag();
1540 } else {
1541 makeComplexInt();
1542 IntReal = v.getComplexIntReal();
1543 IntImag = v.getComplexIntImag();
1544 }
1545 }
1546 };
1547
1548 struct LValue {
1549 APValue::LValueBase Base;
1550 CharUnits Offset;
1551 SubobjectDesignator Designator;
1552 bool IsNullPtr : 1;
1553 bool InvalidBase : 1;
1554
1555 const APValue::LValueBase getLValueBase() const { return Base; }
1556 CharUnits &getLValueOffset() { return Offset; }
1557 const CharUnits &getLValueOffset() const { return Offset; }
1558 SubobjectDesignator &getLValueDesignator() { return Designator; }
1559 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1560 bool isNullPointer() const { return IsNullPtr;}
1561
1562 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1563 unsigned getLValueVersion() const { return Base.getVersion(); }
1564
1565 void moveInto(APValue &V) const {
1566 if (Designator.Invalid)
1567 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1568 else {
1569 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\""
, "clang/lib/AST/ExprConstant.cpp", 1569, __extension__ __PRETTY_FUNCTION__
))
;
1570 V = APValue(Base, Offset, Designator.Entries,
1571 Designator.IsOnePastTheEnd, IsNullPtr);
1572 }
1573 }
1574 void setFrom(ASTContext &Ctx, const APValue &V) {
1575 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?\""
, "clang/lib/AST/ExprConstant.cpp", 1575, __extension__ __PRETTY_FUNCTION__
))
;
1576 Base = V.getLValueBase();
1577 Offset = V.getLValueOffset();
1578 InvalidBase = false;
1579 Designator = SubobjectDesignator(Ctx, V);
1580 IsNullPtr = V.isNullPointer();
1581 }
1582
1583 void set(APValue::LValueBase B, bool BInvalid = false) {
1584#ifndef NDEBUG
1585 // We only allow a few types of invalid bases. Enforce that here.
1586 if (BInvalid) {
1587 const auto *E = B.get<const Expr *>();
1588 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\""
, "clang/lib/AST/ExprConstant.cpp", 1589, __extension__ __PRETTY_FUNCTION__
))
1589 "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\""
, "clang/lib/AST/ExprConstant.cpp", 1589, __extension__ __PRETTY_FUNCTION__
))
;
1590 }
1591#endif
1592
1593 Base = B;
1594 Offset = CharUnits::fromQuantity(0);
1595 InvalidBase = BInvalid;
1596 Designator = SubobjectDesignator(getType(B));
1597 IsNullPtr = false;
1598 }
1599
1600 void setNull(ASTContext &Ctx, QualType PointerTy) {
1601 Base = (const ValueDecl *)nullptr;
1602 Offset =
1603 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
1604 InvalidBase = false;
1605 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1606 IsNullPtr = true;
1607 }
1608
1609 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1610 set(B, true);
1611 }
1612
1613 std::string toString(ASTContext &Ctx, QualType T) const {
1614 APValue Printable;
1615 moveInto(Printable);
1616 return Printable.getAsString(Ctx, T);
1617 }
1618
1619 private:
1620 // Check that this LValue is not based on a null pointer. If it is, produce
1621 // a diagnostic and mark the designator as invalid.
1622 template <typename GenDiagType>
1623 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1624 if (Designator.Invalid)
1625 return false;
1626 if (IsNullPtr) {
1627 GenDiag();
1628 Designator.setInvalid();
1629 return false;
1630 }
1631 return true;
1632 }
1633
1634 public:
1635 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1636 CheckSubobjectKind CSK) {
1637 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1638 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1639 });
1640 }
1641
1642 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1643 AccessKinds AK) {
1644 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1645 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1646 });
1647 }
1648
1649 // Check this LValue refers to an object. If not, set the designator to be
1650 // invalid and emit a diagnostic.
1651 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1652 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1653 Designator.checkSubobject(Info, E, CSK);
1654 }
1655
1656 void addDecl(EvalInfo &Info, const Expr *E,
1657 const Decl *D, bool Virtual = false) {
1658 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1659 Designator.addDeclUnchecked(D, Virtual);
1660 }
1661 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1662 if (!Designator.Entries.empty()) {
1663 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1664 Designator.setInvalid();
1665 return;
1666 }
1667 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1668 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()"
, "clang/lib/AST/ExprConstant.cpp", 1668, __extension__ __PRETTY_FUNCTION__
))
;
1669 Designator.FirstEntryIsAnUnsizedArray = true;
1670 Designator.addUnsizedArrayUnchecked(ElemTy);
1671 }
1672 }
1673 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1674 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1675 Designator.addArrayUnchecked(CAT);
1676 }
1677 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1678 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1679 Designator.addComplexUnchecked(EltTy, Imag);
1680 }
1681 void clearIsNullPointer() {
1682 IsNullPtr = false;
1683 }
1684 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1685 const APSInt &Index, CharUnits ElementSize) {
1686 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1687 // but we're not required to diagnose it and it's valid in C++.)
1688 if (!Index)
1689 return;
1690
1691 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1692 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1693 // offsets.
1694 uint64_t Offset64 = Offset.getQuantity();
1695 uint64_t ElemSize64 = ElementSize.getQuantity();
1696 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1697 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1698
1699 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1700 Designator.adjustIndex(Info, E, Index);
1701 clearIsNullPointer();
1702 }
1703 void adjustOffset(CharUnits N) {
1704 Offset += N;
1705 if (N.getQuantity())
1706 clearIsNullPointer();
1707 }
1708 };
1709
1710 struct MemberPtr {
1711 MemberPtr() {}
1712 explicit MemberPtr(const ValueDecl *Decl)
1713 : DeclAndIsDerivedMember(Decl, false) {}
1714
1715 /// The member or (direct or indirect) field referred to by this member
1716 /// pointer, or 0 if this is a null member pointer.
1717 const ValueDecl *getDecl() const {
1718 return DeclAndIsDerivedMember.getPointer();
1719 }
1720 /// Is this actually a member of some type derived from the relevant class?
1721 bool isDerivedMember() const {
1722 return DeclAndIsDerivedMember.getInt();
1723 }
1724 /// Get the class which the declaration actually lives in.
1725 const CXXRecordDecl *getContainingRecord() const {
1726 return cast<CXXRecordDecl>(
1727 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1728 }
1729
1730 void moveInto(APValue &V) const {
1731 V = APValue(getDecl(), isDerivedMember(), Path);
1732 }
1733 void setFrom(const APValue &V) {
1734 assert(V.isMemberPointer())(static_cast <bool> (V.isMemberPointer()) ? void (0) : __assert_fail
("V.isMemberPointer()", "clang/lib/AST/ExprConstant.cpp", 1734
, __extension__ __PRETTY_FUNCTION__))
;
1735 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1736 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1737 Path.clear();
1738 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1739 Path.insert(Path.end(), P.begin(), P.end());
1740 }
1741
1742 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1743 /// whether the member is a member of some class derived from the class type
1744 /// of the member pointer.
1745 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1746 /// Path - The path of base/derived classes from the member declaration's
1747 /// class (exclusive) to the class type of the member pointer (inclusive).
1748 SmallVector<const CXXRecordDecl*, 4> Path;
1749
1750 /// Perform a cast towards the class of the Decl (either up or down the
1751 /// hierarchy).
1752 bool castBack(const CXXRecordDecl *Class) {
1753 assert(!Path.empty())(static_cast <bool> (!Path.empty()) ? void (0) : __assert_fail
("!Path.empty()", "clang/lib/AST/ExprConstant.cpp", 1753, __extension__
__PRETTY_FUNCTION__))
;
1754 const CXXRecordDecl *Expected;
1755 if (Path.size() >= 2)
1756 Expected = Path[Path.size() - 2];
1757 else
1758 Expected = getContainingRecord();
1759 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1760 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1761 // if B does not contain the original member and is not a base or
1762 // derived class of the class containing the original member, the result
1763 // of the cast is undefined.
1764 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1765 // (D::*). We consider that to be a language defect.
1766 return false;
1767 }
1768 Path.pop_back();
1769 return true;
1770 }
1771 /// Perform a base-to-derived member pointer cast.
1772 bool castToDerived(const CXXRecordDecl *Derived) {
1773 if (!getDecl())
1774 return true;
1775 if (!isDerivedMember()) {
1776 Path.push_back(Derived);
1777 return true;
1778 }
1779 if (!castBack(Derived))
1780 return false;
1781 if (Path.empty())
1782 DeclAndIsDerivedMember.setInt(false);
1783 return true;
1784 }
1785 /// Perform a derived-to-base member pointer cast.
1786 bool castToBase(const CXXRecordDecl *Base) {
1787 if (!getDecl())
1788 return true;
1789 if (Path.empty())
1790 DeclAndIsDerivedMember.setInt(true);
1791 if (isDerivedMember()) {
1792 Path.push_back(Base);
1793 return true;
1794 }
1795 return castBack(Base);
1796 }
1797 };
1798
1799 /// Compare two member pointers, which are assumed to be of the same type.
1800 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1801 if (!LHS.getDecl() || !RHS.getDecl())
1802 return !LHS.getDecl() && !RHS.getDecl();
1803 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1804 return false;
1805 return LHS.Path == RHS.Path;
1806 }
1807}
1808
1809static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1810static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1811 const LValue &This, const Expr *E,
1812 bool AllowNonLiteralTypes = false);
1813static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1814 bool InvalidBaseOK = false);
1815static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1816 bool InvalidBaseOK = false);
1817static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1818 EvalInfo &Info);
1819static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1820static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1821static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1822 EvalInfo &Info);
1823static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1824static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1825static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1826 EvalInfo &Info);
1827static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1828static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
1829 EvalInfo &Info);
1830
1831/// Evaluate an integer or fixed point expression into an APResult.
1832static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1833 EvalInfo &Info);
1834
1835/// Evaluate only a fixed point expression into an APResult.
1836static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1837 EvalInfo &Info);
1838
1839//===----------------------------------------------------------------------===//
1840// Misc utilities
1841//===----------------------------------------------------------------------===//
1842
1843/// Negate an APSInt in place, converting it to a signed form if necessary, and
1844/// preserving its value (by extending by up to one bit as needed).
1845static void negateAsSigned(APSInt &Int) {
1846 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1847 Int = Int.extend(Int.getBitWidth() + 1);
1848 Int.setIsSigned(true);
1849 }
1850 Int = -Int;
1851}
1852
1853template<typename KeyT>
1854APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1855 ScopeKind Scope, LValue &LV) {
1856 unsigned Version = getTempVersion();
1857 APValue::LValueBase Base(Key, Index, Version);
1858 LV.set(Base);
1859 return createLocal(Base, Key, T, Scope);
1860}
1861
1862/// Allocate storage for a parameter of a function call made in this frame.
1863APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1864 LValue &LV) {
1865 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\""
, "clang/lib/AST/ExprConstant.cpp", 1865, __extension__ __PRETTY_FUNCTION__
))
;
1866 APValue::LValueBase Base(PVD, Index, Args.Version);
1867 LV.set(Base);
1868 // We always destroy parameters at the end of the call, even if we'd allow
1869 // them to live to the end of the full-expression at runtime, in order to
1870 // give portable results and match other compilers.
1871 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
1872}
1873
1874APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1875 QualType T, ScopeKind Scope) {
1876 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\""
, "clang/lib/AST/ExprConstant.cpp", 1876, __extension__ __PRETTY_FUNCTION__
))
;
1877 unsigned Version = Base.getVersion();
1878 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1879 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\""
, "clang/lib/AST/ExprConstant.cpp", 1879, __extension__ __PRETTY_FUNCTION__
))
;
1880
1881 // If we're creating a local immediately in the operand of a speculative
1882 // evaluation, don't register a cleanup to be run outside the speculative
1883 // evaluation context, since we won't actually be able to initialize this
1884 // object.
1885 if (Index <= Info.SpeculativeEvaluationDepth) {
1886 if (T.isDestructedType())
1887 Info.noteSideEffect();
1888 } else {
1889 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
1890 }
1891 return Result;
1892}
1893
1894APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
1895 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
1896 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
1897 return nullptr;
1898 }
1899
1900 DynamicAllocLValue DA(NumHeapAllocs++);
1901 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
1902 auto Result = HeapAllocs.emplace(std::piecewise_construct,
1903 std::forward_as_tuple(DA), std::tuple<>());
1904 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?\""
, "clang/lib/AST/ExprConstant.cpp", 1904, __extension__ __PRETTY_FUNCTION__
))
;
1905 Result.first->second.AllocExpr = E;
1906 return &Result.first->second.Value;
1907}
1908
1909/// Produce a string describing the given constexpr call.
1910void CallStackFrame::describe(raw_ostream &Out) {
1911 unsigned ArgIndex = 0;
1912 bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
1913 !isa<CXXConstructorDecl>(Callee) &&
1914 cast<CXXMethodDecl>(Callee)->isInstance();
1915
1916 if (!IsMemberCall)
1917 Out << *Callee << '(';
1918
1919 if (This && IsMemberCall) {
1920 APValue Val;
1921 This->moveInto(Val);
1922 Val.printPretty(Out, Info.Ctx,
1923 This->Designator.MostDerivedType);
1924 // FIXME: Add parens around Val if needed.
1925 Out << "->" << *Callee << '(';
1926 IsMemberCall = false;
1927 }
1928
1929 for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
1930 E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
1931 if (ArgIndex > (unsigned)IsMemberCall)
1932 Out << ", ";
1933
1934 const ParmVarDecl *Param = *I;
1935 APValue *V = Info.getParamSlot(Arguments, Param);
1936 if (V)
1937 V->printPretty(Out, Info.Ctx, Param->getType());
1938 else
1939 Out << "<...>";
1940
1941 if (ArgIndex == 0 && IsMemberCall)
1942 Out << "->" << *Callee << '(';
1943 }
1944
1945 Out << ')';
1946}
1947
1948/// Evaluate an expression to see if it had side-effects, and discard its
1949/// result.
1950/// \return \c true if the caller should keep evaluating.
1951static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1952 assert(!E->isValueDependent())(static_cast <bool> (!E->isValueDependent()) ? void (
0) : __assert_fail ("!E->isValueDependent()", "clang/lib/AST/ExprConstant.cpp"
, 1952, __extension__ __PRETTY_FUNCTION__))
;
1953 APValue Scratch;
1954 if (!Evaluate(Scratch, Info, E))
1955 // We don't need the value, but we might have skipped a side effect here.
1956 return Info.noteSideEffect();
1957 return true;
1958}
1959
1960/// Should this call expression be treated as a no-op?
1961static bool IsNoOpCall(const CallExpr *E) {
1962 unsigned Builtin = E->getBuiltinCallee();
1963 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1964 Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
1965 Builtin == Builtin::BI__builtin_function_start);
1966}
1967
1968static bool IsGlobalLValue(APValue::LValueBase B) {
1969 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1970 // constant expression of pointer type that evaluates to...
1971
1972 // ... a null pointer value, or a prvalue core constant expression of type
1973 // std::nullptr_t.
1974 if (!B) return true;
1975
1976 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1977 // ... the address of an object with static storage duration,
1978 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1979 return VD->hasGlobalStorage();
1980 if (isa<TemplateParamObjectDecl>(D))
1981 return true;
1982 // ... the address of a function,
1983 // ... the address of a GUID [MS extension],
1984 // ... the address of an unnamed global constant
1985 return isa<FunctionDecl, MSGuidDecl, UnnamedGlobalConstantDecl>(D);
1986 }
1987
1988 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
1989 return true;
1990
1991 const Expr *E = B.get<const Expr*>();
1992 switch (E->getStmtClass()) {
1993 default:
1994 return false;
1995 case Expr::CompoundLiteralExprClass: {
1996 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1997 return CLE->isFileScope() && CLE->isLValue();
1998 }
1999 case Expr::MaterializeTemporaryExprClass:
2000 // A materialized temporary might have been lifetime-extended to static
2001 // storage duration.
2002 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
2003 // A string literal has static storage duration.
2004 case Expr::StringLiteralClass:
2005 case Expr::PredefinedExprClass:
2006 case Expr::ObjCStringLiteralClass:
2007 case Expr::ObjCEncodeExprClass:
2008 return true;
2009 case Expr::ObjCBoxedExprClass:
2010 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
2011 case Expr::CallExprClass:
2012 return IsNoOpCall(cast<CallExpr>(E));
2013 // For GCC compatibility, &&label has static storage duration.
2014 case Expr::AddrLabelExprClass:
2015 return true;
2016 // A Block literal expression may be used as the initialization value for
2017 // Block variables at global or local static scope.
2018 case Expr::BlockExprClass:
2019 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
2020 // The APValue generated from a __builtin_source_location will be emitted as a
2021 // literal.
2022 case Expr::SourceLocExprClass:
2023 return true;
2024 case Expr::ImplicitValueInitExprClass:
2025 // FIXME:
2026 // We can never form an lvalue with an implicit value initialization as its
2027 // base through expression evaluation, so these only appear in one case: the
2028 // implicit variable declaration we invent when checking whether a constexpr
2029 // constructor can produce a constant expression. We must assume that such
2030 // an expression might be a global lvalue.
2031 return true;
2032 }
2033}
2034
2035static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2036 return LVal.Base.dyn_cast<const ValueDecl*>();
2037}
2038
2039static bool IsLiteralLValue(const LValue &Value) {
2040 if (Value.getLValueCallIndex())
2041 return false;
2042 const Expr *E = Value.Base.dyn_cast<const Expr*>();
2043 return E && !isa<MaterializeTemporaryExpr>(E);
2044}
2045
2046static bool IsWeakLValue(const LValue &Value) {
2047 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2048 return Decl && Decl->isWeak();
2049}
2050
2051static bool isZeroSized(const LValue &Value) {
2052 const ValueDecl *Decl = GetLValueBaseDecl(Value);
2053 if (Decl && isa<VarDecl>(Decl)) {
2054 QualType Ty = Decl->getType();
2055 if (Ty->isArrayType())
2056 return Ty->isIncompleteType() ||
2057 Decl->getASTContext().getTypeSize(Ty) == 0;
2058 }
2059 return false;
2060}
2061
2062static bool HasSameBase(const LValue &A, const LValue &B) {
2063 if (!A.getLValueBase())
2064 return !B.getLValueBase();
2065 if (!B.getLValueBase())
2066 return false;
2067
2068 if (A.getLValueBase().getOpaqueValue() !=
2069 B.getLValueBase().getOpaqueValue())
2070 return false;
2071
2072 return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2073 A.getLValueVersion() == B.getLValueVersion();
2074}
2075
2076static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2077 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\""
, "clang/lib/AST/ExprConstant.cpp", 2077, __extension__ __PRETTY_FUNCTION__
))
;
2078 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2079
2080 // For a parameter, find the corresponding call stack frame (if it still
2081 // exists), and point at the parameter of the function definition we actually
2082 // invoked.
2083 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
2084 unsigned Idx = PVD->getFunctionScopeIndex();
2085 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2086 if (F->Arguments.CallIndex == Base.getCallIndex() &&
2087 F->Arguments.Version == Base.getVersion() && F->Callee &&
2088 Idx < F->Callee->getNumParams()) {
2089 VD = F->Callee->getParamDecl(Idx);
2090 break;
2091 }
2092 }
2093 }
2094
2095 if (VD)
2096 Info.Note(VD->getLocation(), diag::note_declared_at);
2097 else if (const Expr *E = Base.dyn_cast<const Expr*>())
2098 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2099 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2100 // FIXME: Produce a note for dangling pointers too.
2101 if (std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA))
2102 Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2103 diag::note_constexpr_dynamic_alloc_here);
2104 }
2105 // We have no information to show for a typeid(T) object.
2106}
2107
2108enum class CheckEvaluationResultKind {
2109 ConstantExpression,
2110 FullyInitialized,
2111};
2112
2113/// Materialized temporaries that we've already checked to determine if they're
2114/// initializsed by a constant expression.
2115using CheckedTemporaries =
2116 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2117
2118static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2119 EvalInfo &Info, SourceLocation DiagLoc,
2120 QualType Type, const APValue &Value,
2121 ConstantExprKind Kind,
2122 SourceLocation SubobjectLoc,
2123 CheckedTemporaries &CheckedTemps);
2124
2125/// Check that this reference or pointer core constant expression is a valid
2126/// value for an address or reference constant expression. Return true if we
2127/// can fold this expression, whether or not it's a constant expression.
2128static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2129 QualType Type, const LValue &LVal,
2130 ConstantExprKind Kind,
2131 CheckedTemporaries &CheckedTemps) {
2132 bool IsReferenceType = Type->isReferenceType();
2133
2134 APValue::LValueBase Base = LVal.getLValueBase();
2135 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2136
2137 const Expr *BaseE = Base.dyn_cast<const Expr *>();
2138 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2139
2140 // Additional restrictions apply in a template argument. We only enforce the
2141 // C++20 restrictions here; additional syntactic and semantic restrictions
2142 // are applied elsewhere.
2143 if (isTemplateArgument(Kind)) {
2144 int InvalidBaseKind = -1;
2145 StringRef Ident;
2146 if (Base.is<TypeInfoLValue>())
2147 InvalidBaseKind = 0;
2148 else if (isa_and_nonnull<StringLiteral>(BaseE))
2149 InvalidBaseKind = 1;
2150 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
2151 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
2152 InvalidBaseKind = 2;
2153 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
2154 InvalidBaseKind = 3;
2155 Ident = PE->getIdentKindName();
2156 }
2157
2158 if (InvalidBaseKind != -1) {
2159 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2160 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2161 << Ident;
2162 return false;
2163 }
2164 }
2165
2166 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
2167 if (FD->isConsteval()) {
2168 Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2169 << !Type->isAnyPointerType();
2170 Info.Note(FD->getLocation(), diag::note_declared_at);
2171 return false;
2172 }
2173 }
2174
2175 // Check that the object is a global. Note that the fake 'this' object we
2176 // manufacture when checking potential constant expressions is conservatively
2177 // assumed to be global here.
2178 if (!IsGlobalLValue(Base)) {
2179 if (Info.getLangOpts().CPlusPlus11) {
2180 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2181 << IsReferenceType << !Designator.Entries.empty() << !!BaseVD
2182 << BaseVD;
2183 auto *VarD = dyn_cast_or_null<VarDecl>(BaseVD);
2184 if (VarD && VarD->isConstexpr()) {
2185 // Non-static local constexpr variables have unintuitive semantics:
2186 // constexpr int a = 1;
2187 // constexpr const int *p = &a;
2188 // ... is invalid because the address of 'a' is not constant. Suggest
2189 // adding a 'static' in this case.
2190 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2191 << VarD
2192 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2193 } else {
2194 NoteLValueLocation(Info, Base);
2195 }
2196 } else {
2197 Info.FFDiag(Loc);
2198 }
2199 // Don't allow references to temporaries to escape.
2200 return false;
2201 }
2202 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\""
, "clang/lib/AST/ExprConstant.cpp", 2204, __extension__ __PRETTY_FUNCTION__
))
2203 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\""
, "clang/lib/AST/ExprConstant.cpp", 2204, __extension__ __PRETTY_FUNCTION__
))
2204 "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\""
, "clang/lib/AST/ExprConstant.cpp", 2204, __extension__ __PRETTY_FUNCTION__
))
;
2205
2206 if (Base.is<DynamicAllocLValue>()) {
2207 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2208 << IsReferenceType << !Designator.Entries.empty();
2209 NoteLValueLocation(Info, Base);
2210 return false;
2211 }
2212
2213 if (BaseVD) {
2214 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
2215 // Check if this is a thread-local variable.
2216 if (Var->getTLSKind())
2217 // FIXME: Diagnostic!
2218 return false;
2219
2220 // A dllimport variable never acts like a constant, unless we're
2221 // evaluating a value for use only in name mangling.
2222 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2223 // FIXME: Diagnostic!
2224 return false;
2225
2226 // In CUDA/HIP device compilation, only device side variables have
2227 // constant addresses.
2228 if (Info.getCtx().getLangOpts().CUDA &&
2229 Info.getCtx().getLangOpts().CUDAIsDevice &&
2230 Info.getCtx().CUDAConstantEvalCtx.NoWrongSidedVars) {
2231 if ((!Var->hasAttr<CUDADeviceAttr>() &&
2232 !Var->hasAttr<CUDAConstantAttr>() &&
2233 !Var->getType()->isCUDADeviceBuiltinSurfaceType() &&
2234 !Var->getType()->isCUDADeviceBuiltinTextureType()) ||
2235 Var->hasAttr<HIPManagedAttr>())
2236 return false;
2237 }
2238 }
2239 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
2240 // __declspec(dllimport) must be handled very carefully:
2241 // We must never initialize an expression with the thunk in C++.
2242 // Doing otherwise would allow the same id-expression to yield
2243 // different addresses for the same function in different translation
2244 // units. However, this means that we must dynamically initialize the
2245 // expression with the contents of the import address table at runtime.
2246 //
2247 // The C language has no notion of ODR; furthermore, it has no notion of
2248 // dynamic initialization. This means that we are permitted to
2249 // perform initialization with the address of the thunk.
2250 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2251 FD->hasAttr<DLLImportAttr>())
2252 // FIXME: Diagnostic!
2253 return false;
2254 }
2255 } else if (const auto *MTE =
2256 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
2257 if (CheckedTemps.insert(MTE).second) {
2258 QualType TempType = getType(Base);
2259 if (TempType.isDestructedType()) {
2260 Info.FFDiag(MTE->getExprLoc(),
2261 diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2262 << TempType;
2263 return false;
2264 }
2265
2266 APValue *V = MTE->getOrCreateValue(false);
2267 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\""
, "clang/lib/AST/ExprConstant.cpp", 2267, __extension__ __PRETTY_FUNCTION__
))
;
2268 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2269 Info, MTE->getExprLoc(), TempType, *V,
2270 Kind, SourceLocation(), CheckedTemps))
2271 return false;
2272 }
2273 }
2274
2275 // Allow address constant expressions to be past-the-end pointers. This is
2276 // an extension: the standard requires them to point to an object.
2277 if (!IsReferenceType)
2278 return true;
2279
2280 // A reference constant expression must refer to an object.
2281 if (!Base) {
2282 // FIXME: diagnostic
2283 Info.CCEDiag(Loc);
2284 return true;
2285 }
2286
2287 // Does this refer one past the end of some object?
2288 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2289 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2290 << !Designator.Entries.empty() << !!BaseVD << BaseVD;
2291 NoteLValueLocation(Info, Base);
2292 }
2293
2294 return true;
2295}
2296
2297/// Member pointers are constant expressions unless they point to a
2298/// non-virtual dllimport member function.
2299static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2300 SourceLocation Loc,
2301 QualType Type,
2302 const APValue &Value,
2303 ConstantExprKind Kind) {
2304 const ValueDecl *Member = Value.getMemberPointerDecl();
2305 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
2306 if (!FD)
2307 return true;
2308 if (FD->isConsteval()) {
2309 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2310 Info.Note(FD->getLocation(), diag::note_declared_at);
2311 return false;
2312 }
2313 return isForManglingOnly(Kind) || FD->isVirtual() ||
2314 !FD->hasAttr<DLLImportAttr>();
2315}
2316
2317/// Check that this core constant expression is of literal type, and if not,
2318/// produce an appropriate diagnostic.
2319static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2320 const LValue *This = nullptr) {
2321 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx))
2322 return true;
2323
2324 // C++1y: A constant initializer for an object o [...] may also invoke
2325 // constexpr constructors for o and its subobjects even if those objects
2326 // are of non-literal class types.
2327 //
2328 // C++11 missed this detail for aggregates, so classes like this:
2329 // struct foo_t { union { int i; volatile int j; } u; };
2330 // are not (obviously) initializable like so:
2331 // __attribute__((__require_constant_initialization__))
2332 // static const foo_t x = {{0}};
2333 // because "i" is a subobject with non-literal initialization (due to the
2334 // volatile member of the union). See:
2335 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2336 // Therefore, we use the C++1y behavior.
2337 if (This && Info.EvaluatingDecl == This->getLValueBase())
2338 return true;
2339
2340 // Prvalue constant expressions must be of literal types.
2341 if (Info.getLangOpts().CPlusPlus11)
2342 Info.FFDiag(E, diag::note_constexpr_nonliteral)
2343 << E->getType();
2344 else
2345 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2346 return false;
2347}
2348
2349static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2350 EvalInfo &Info, SourceLocation DiagLoc,
2351 QualType Type, const APValue &Value,
2352 ConstantExprKind Kind,
2353 SourceLocation SubobjectLoc,
2354 CheckedTemporaries &CheckedTemps) {
2355 if (!Value.hasValue()) {
2356 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2357 << true << Type;
2358 if (SubobjectLoc.isValid())
2359 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
2360 return false;
2361 }
2362
2363 // We allow _Atomic(T) to be initialized from anything that T can be
2364 // initialized from.
2365 if (const AtomicType *AT = Type->getAs<AtomicType>())
2366 Type = AT->getValueType();
2367
2368 // Core issue 1454: For a literal constant expression of array or class type,
2369 // each subobject of its value shall have been initialized by a constant
2370 // expression.
2371 if (Value.isArray()) {
2372 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2373 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2374 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2375 Value.getArrayInitializedElt(I), Kind,
2376 SubobjectLoc, CheckedTemps))
2377 return false;
2378 }
2379 if (!Value.hasArrayFiller())
2380 return true;
2381 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
2382 Value.getArrayFiller(), Kind, SubobjectLoc,
2383 CheckedTemps);
2384 }
2385 if (Value.isUnion() && Value.getUnionField()) {
2386 return CheckEvaluationResult(
2387 CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2388 Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
2389 CheckedTemps);
2390 }
2391 if (Value.isStruct()) {
2392 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2393 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
2394 unsigned BaseIndex = 0;
2395 for (const CXXBaseSpecifier &BS : CD->bases()) {
2396 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
2397 Value.getStructBase(BaseIndex), Kind,
2398 BS.getBeginLoc(), CheckedTemps))
2399 return false;
2400 ++BaseIndex;
2401 }
2402 }
2403 for (const auto *I : RD->fields()) {
2404 if (I->isUnnamedBitfield())
2405 continue;
2406
2407 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2408 Value.getStructField(I->getFieldIndex()),
2409 Kind, I->getLocation(), CheckedTemps))
2410 return false;
2411 }
2412 }
2413
2414 if (Value.isLValue() &&
2415 CERK == CheckEvaluationResultKind::ConstantExpression) {
2416 LValue LVal;
2417 LVal.setFrom(Info.Ctx, Value);
2418 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
2419 CheckedTemps);
2420 }
2421
2422 if (Value.isMemberPointer() &&
2423 CERK == CheckEvaluationResultKind::ConstantExpression)
2424 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
2425
2426 // Everything else is fine.
2427 return true;
2428}
2429
2430/// Check that this core constant expression value is a valid value for a
2431/// constant expression. If not, report an appropriate diagnostic. Does not
2432/// check that the expression is of literal type.
2433static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2434 QualType Type, const APValue &Value,
2435 ConstantExprKind Kind) {
2436 // Nothing to check for a constant expression of type 'cv void'.
2437 if (Type->isVoidType())
2438 return true;
2439
2440 CheckedTemporaries CheckedTemps;
2441 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2442 Info, DiagLoc, Type, Value, Kind,
2443 SourceLocation(), CheckedTemps);
2444}
2445
2446/// Check that this evaluated value is fully-initialized and can be loaded by
2447/// an lvalue-to-rvalue conversion.
2448static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2449 QualType Type, const APValue &Value) {
2450 CheckedTemporaries CheckedTemps;
2451 return CheckEvaluationResult(
2452 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2453 ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
2454}
2455
2456/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2457/// "the allocated storage is deallocated within the evaluation".
2458static bool CheckMemoryLeaks(EvalInfo &Info) {
2459 if (!Info.HeapAllocs.empty()) {
2460 // We can still fold to a constant despite a compile-time memory leak,
2461 // so long as the heap allocation isn't referenced in the result (we check
2462 // that in CheckConstantExpression).
2463 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2464 diag::note_constexpr_memory_leak)
2465 << unsigned(Info.HeapAllocs.size() - 1);
2466 }
2467 return true;
2468}
2469
2470static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2471 // A null base expression indicates a null pointer. These are always
2472 // evaluatable, and they are false unless the offset is zero.
2473 if (!Value.getLValueBase()) {
2474 // TODO: Should a non-null pointer with an offset of zero evaluate to true?
2475 Result = !Value.getLValueOffset().isZero();
2476 return true;
2477 }
2478
2479 // We have a non-null base. These are generally known to be true, but if it's
2480 // a weak declaration it can be null at runtime.
2481 Result = true;
2482 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2483 return !Decl || !Decl->isWeak();
2484}
2485
2486static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2487 // TODO: This function should produce notes if it fails.
2488 switch (Val.getKind()) {
2489 case APValue::None:
2490 case APValue::Indeterminate:
2491 return false;
2492 case APValue::Int:
2493 Result = Val.getInt().getBoolValue();
2494 return true;
2495 case APValue::FixedPoint:
2496 Result = Val.getFixedPoint().getBoolValue();
2497 return true;
2498 case APValue::Float:
2499 Result = !Val.getFloat().isZero();
2500 return true;
2501 case APValue::ComplexInt:
2502 Result = Val.getComplexIntReal().getBoolValue() ||
2503 Val.getComplexIntImag().getBoolValue();
2504 return true;
2505 case APValue::ComplexFloat:
2506 Result = !Val.getComplexFloatReal().isZero() ||
2507 !Val.getComplexFloatImag().isZero();
2508 return true;
2509 case APValue::LValue:
2510 return EvalPointerValueAsBool(Val, Result);
2511 case APValue::MemberPointer:
2512 if (Val.getMemberPointerDecl() && Val.getMemberPointerDecl()->isWeak()) {
2513 return false;
2514 }
2515 Result = Val.getMemberPointerDecl();
2516 return true;
2517 case APValue::Vector:
2518 case APValue::Array:
2519 case APValue::Struct:
2520 case APValue::Union:
2521 case APValue::AddrLabelDiff:
2522 return false;
2523 }
2524
2525 llvm_unreachable("unknown APValue kind")::llvm::llvm_unreachable_internal("unknown APValue kind", "clang/lib/AST/ExprConstant.cpp"
, 2525)
;
2526}
2527
2528static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2529 EvalInfo &Info) {
2530 assert(!E->isValueDependent())(static_cast <bool> (!E->isValueDependent()) ? void (
0) : __assert_fail ("!E->isValueDependent()", "clang/lib/AST/ExprConstant.cpp"
, 2530, __extension__ __PRETTY_FUNCTION__))
;
2531 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\""
, "clang/lib/AST/ExprConstant.cpp", 2531, __extension__ __PRETTY_FUNCTION__
))
;
2532 APValue Val;
2533 if (!Evaluate(Val, Info, E))
2534 return false;
2535 return HandleConversionToBool(Val, Result);
2536}
2537
2538template<typename T>
2539static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2540 const T &SrcValue, QualType DestType) {
2541 Info.CCEDiag(E, diag::note_constexpr_overflow)
2542 << SrcValue << DestType;
2543 return Info.noteUndefinedBehavior();
2544}
2545
2546static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2547 QualType SrcType, const APFloat &Value,
2548 QualType DestType, APSInt &Result) {
2549 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2550 // Determine whether we are converting to unsigned or signed.
2551 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2552
2553 Result = APSInt(DestWidth, !DestSigned);
2554 bool ignored;
2555 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2556 & APFloat::opInvalidOp)
2557 return HandleOverflow(Info, E, Value, DestType);
2558 return true;
2559}
2560
2561/// Get rounding mode to use in evaluation of the specified expression.
2562///
2563/// If rounding mode is unknown at compile time, still try to evaluate the
2564/// expression. If the result is exact, it does not depend on rounding mode.
2565/// So return "tonearest" mode instead of "dynamic".
2566static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E) {
2567 llvm::RoundingMode RM =
2568 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
2569 if (RM == llvm::RoundingMode::Dynamic)
2570 RM = llvm::RoundingMode::NearestTiesToEven;
2571 return RM;
2572}
2573
2574/// Check if the given evaluation result is allowed for constant evaluation.
2575static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2576 APFloat::opStatus St) {
2577 // In a constant context, assume that any dynamic rounding mode or FP
2578 // exception state matches the default floating-point environment.
2579 if (Info.InConstantContext)
2580 return true;
2581
2582 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
2583 if ((St & APFloat::opInexact) &&
2584 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2585 // Inexact result means that it depends on rounding mode. If the requested
2586 // mode is dynamic, the evaluation cannot be made in compile time.
2587 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2588 return false;
2589 }
2590
2591 if ((St != APFloat::opOK) &&
2592 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2593 FPO.getExceptionMode() != LangOptions::FPE_Ignore ||
2594 FPO.getAllowFEnvAccess())) {
2595 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2596 return false;
2597 }
2598
2599 if ((St & APFloat::opStatus::opInvalidOp) &&
2600 FPO.getExceptionMode() != LangOptions::FPE_Ignore) {
2601 // There is no usefully definable result.
2602 Info.FFDiag(E);
2603 return false;
2604 }
2605
2606 // FIXME: if:
2607 // - evaluation triggered other FP exception, and
2608 // - exception mode is not "ignore", and
2609 // - the expression being evaluated is not a part of global variable
2610 // initializer,
2611 // the evaluation probably need to be rejected.
2612 return true;
2613}
2614
2615static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2616 QualType SrcType, QualType DestType,
2617 APFloat &Result) {
2618 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)"
, "clang/lib/AST/ExprConstant.cpp", 2618, __extension__ __PRETTY_FUNCTION__
))
;
2619 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2620 APFloat::opStatus St;
2621 APFloat Value = Result;
2622 bool ignored;
2623 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
2624 return checkFloatingPointResult(Info, E, St);
2625}
2626
2627static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2628 QualType DestType, QualType SrcType,
2629 const APSInt &Value) {
2630 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2631 // Figure out if this is a truncate, extend or noop cast.
2632 // If the input is signed, do a sign extend, noop, or truncate.
2633 APSInt Result = Value.extOrTrunc(DestWidth);
2634 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2635 if (DestType->isBooleanType())
2636 Result = Value.getBoolValue();
2637 return Result;
2638}
2639
2640static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2641 const FPOptions FPO,
2642 QualType SrcType, const APSInt &Value,
2643 QualType DestType, APFloat &Result) {
2644 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2645 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2646 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), RM);
2647 return checkFloatingPointResult(Info, E, St);
2648}
2649
2650static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2651 APValue &Value, const FieldDecl *FD) {
2652 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\""
, "clang/lib/AST/ExprConstant.cpp", 2652, __extension__ __PRETTY_FUNCTION__
))
;
2653
2654 if (!Value.isInt()) {
2655 // Trying to store a pointer-cast-to-integer into a bitfield.
2656 // FIXME: In this case, we should provide the diagnostic for casting
2657 // a pointer to an integer.
2658 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?\""
, "clang/lib/AST/ExprConstant.cpp", 2658, __extension__ __PRETTY_FUNCTION__
))
;
2659 Info.FFDiag(E);
2660 return false;
2661 }
2662
2663 APSInt &Int = Value.getInt();
2664 unsigned OldBitWidth = Int.getBitWidth();
2665 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2666 if (NewBitWidth < OldBitWidth)
2667 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2668 return true;
2669}
2670
2671static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2672 llvm::APInt &Res) {
2673 APValue SVal;
2674 if (!Evaluate(SVal, Info, E))
2675 return false;
2676 if (SVal.isInt()) {
2677 Res = SVal.getInt();
2678 return true;
2679 }
2680 if (SVal.isFloat()) {
2681 Res = SVal.getFloat().bitcastToAPInt();
2682 return true;
2683 }
2684 if (SVal.isVector()) {
2685 QualType VecTy = E->getType();
2686 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2687 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2688 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2689 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2690 Res = llvm::APInt::getZero(VecSize);
2691 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2692 APValue &Elt = SVal.getVectorElt(i);
2693 llvm::APInt EltAsInt;
2694 if (Elt.isInt()) {
2695 EltAsInt = Elt.getInt();
2696 } else if (Elt.isFloat()) {
2697 EltAsInt = Elt.getFloat().bitcastToAPInt();
2698 } else {
2699 // Don't try to handle vectors of anything other than int or float
2700 // (not sure if it's possible to hit this case).
2701 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2702 return false;
2703 }
2704 unsigned BaseEltSize = EltAsInt.getBitWidth();
2705 if (BigEndian)
2706 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2707 else
2708 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2709 }
2710 return true;
2711 }
2712 // Give up if the input isn't an int, float, or vector. For example, we
2713 // reject "(v4i16)(intptr_t)&a".
2714 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2715 return false;
2716}
2717
2718/// Perform the given integer operation, which is known to need at most BitWidth
2719/// bits, and check for overflow in the original type (if that type was not an
2720/// unsigned type).
2721template<typename Operation>
2722static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2723 const APSInt &LHS, const APSInt &RHS,
2724 unsigned BitWidth, Operation Op,
2725 APSInt &Result) {
2726 if (LHS.isUnsigned()) {
2727 Result = Op(LHS, RHS);
2728 return true;
2729 }
2730
2731 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2732 Result = Value.trunc(LHS.getBitWidth());
2733 if (Result.extend(BitWidth) != Value) {
2734 if (Info.checkingForUndefinedBehavior())
2735 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2736 diag::warn_integer_constant_overflow)
2737 << toString(Result, 10) << E->getType();
2738 return HandleOverflow(Info, E, Value, E->getType());
2739 }
2740 return true;
2741}
2742
2743/// Perform the given binary integer operation.
2744static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2745 BinaryOperatorKind Opcode, APSInt RHS,
2746 APSInt &Result) {
2747 bool HandleOverflowResult = true;
2748 switch (Opcode) {
2749 default:
2750 Info.FFDiag(E);
2751 return false;
2752 case BO_Mul:
2753 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2754 std::multiplies<APSInt>(), Result);
2755 case BO_Add:
2756 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2757 std::plus<APSInt>(), Result);
2758 case BO_Sub:
2759 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2760 std::minus<APSInt>(), Result);
2761 case BO_And: Result = LHS & RHS; return true;
2762 case BO_Xor: Result = LHS ^ RHS; return true;
2763 case BO_Or: Result = LHS | RHS; return true;
2764 case BO_Div:
2765 case BO_Rem:
2766 if (RHS == 0) {
2767 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2768 return false;
2769 }
2770 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2771 // this operation and gives the two's complement result.
2772 if (RHS.isNegative() && RHS.isAllOnes() && LHS.isSigned() &&
2773 LHS.isMinSignedValue())
2774 HandleOverflowResult = HandleOverflow(
2775 Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
2776 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2777 return HandleOverflowResult;
2778 case BO_Shl: {
2779 if (Info.getLangOpts().OpenCL)
2780 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2781 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2782 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2783 RHS.isUnsigned());
2784 else if (RHS.isSigned() && RHS.isNegative()) {
2785 // During constant-folding, a negative shift is an opposite shift. Such
2786 // a shift is not a constant expression.
2787 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2788 RHS = -RHS;
2789 goto shift_right;
2790 }
2791 shift_left:
2792 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2793 // the shifted type.
2794 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2795 if (SA != RHS) {
2796 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2797 << RHS << E->getType() << LHS.getBitWidth();
2798 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
2799 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2800 // operand, and must not overflow the corresponding unsigned type.
2801 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
2802 // E1 x 2^E2 module 2^N.
2803 if (LHS.isNegative())
2804 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2805 else if (LHS.countl_zero() < SA)
2806 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2807 }
2808 Result = LHS << SA;
2809 return true;
2810 }
2811 case BO_Shr: {
2812 if (Info.getLangOpts().OpenCL)
2813 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2814 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2815 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2816 RHS.isUnsigned());
2817 else if (RHS.isSigned() && RHS.isNegative()) {
2818 // During constant-folding, a negative shift is an opposite shift. Such a
2819 // shift is not a constant expression.
2820 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2821 RHS = -RHS;
2822 goto shift_left;
2823 }
2824 shift_right:
2825 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2826 // shifted type.
2827 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2828 if (SA != RHS)
2829 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2830 << RHS << E->getType() << LHS.getBitWidth();
2831 Result = LHS >> SA;
2832 return true;
2833 }
2834
2835 case BO_LT: Result = LHS < RHS; return true;
2836 case BO_GT: Result = LHS > RHS; return true;
2837 case BO_LE: Result = LHS <= RHS; return true;
2838 case BO_GE: Result = LHS >= RHS; return true;
2839 case BO_EQ: Result = LHS == RHS; return true;
2840 case BO_NE: Result = LHS != RHS; return true;
2841 case BO_Cmp:
2842 llvm_unreachable("BO_Cmp should be handled elsewhere")::llvm::llvm_unreachable_internal("BO_Cmp should be handled elsewhere"
, "clang/lib/AST/ExprConstant.cpp", 2842)
;
2843 }
2844}
2845
2846/// Perform the given binary floating-point operation, in-place, on LHS.
2847static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
2848 APFloat &LHS, BinaryOperatorKind Opcode,
2849 const APFloat &RHS) {
2850 llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2851 APFloat::opStatus St;
2852 switch (Opcode) {
2853 default:
2854 Info.FFDiag(E);
2855 return false;
2856 case BO_Mul:
2857 St = LHS.multiply(RHS, RM);
2858 break;
2859 case BO_Add:
2860 St = LHS.add(RHS, RM);
2861 break;
2862 case BO_Sub:
2863 St = LHS.subtract(RHS, RM);
2864 break;
2865 case BO_Div:
2866 // [expr.mul]p4:
2867 // If the second operand of / or % is zero the behavior is undefined.
2868 if (RHS.isZero())
2869 Info.CCEDiag(E, diag::note_expr_divide_by_zero);
2870 St = LHS.divide(RHS, RM);
2871 break;
2872 }
2873
2874 // [expr.pre]p4:
2875 // If during the evaluation of an expression, the result is not
2876 // mathematically defined [...], the behavior is undefined.
2877 // FIXME: C++ rules require us to not conform to IEEE 754 here.
2878 if (LHS.isNaN()) {
2879 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2880 return Info.noteUndefinedBehavior();
2881 }
2882
2883 return checkFloatingPointResult(Info, E, St);
2884}
2885
2886static bool handleLogicalOpForVector(const APInt &LHSValue,
2887 BinaryOperatorKind Opcode,
2888 const APInt &RHSValue, APInt &Result) {
2889 bool LHS = (LHSValue != 0);
2890 bool RHS = (RHSValue != 0);
2891
2892 if (Opcode == BO_LAnd)
2893 Result = LHS && RHS;
2894 else
2895 Result = LHS || RHS;
2896 return true;
2897}
2898static bool handleLogicalOpForVector(const APFloat &LHSValue,
2899 BinaryOperatorKind Opcode,
2900 const APFloat &RHSValue, APInt &Result) {
2901 bool LHS = !LHSValue.isZero();
2902 bool RHS = !RHSValue.isZero();
2903
2904 if (Opcode == BO_LAnd)
2905 Result = LHS && RHS;
2906 else
2907 Result = LHS || RHS;
2908 return true;
2909}
2910
2911static bool handleLogicalOpForVector(const APValue &LHSValue,
2912 BinaryOperatorKind Opcode,
2913 const APValue &RHSValue, APInt &Result) {
2914 // The result is always an int type, however operands match the first.
2915 if (LHSValue.getKind() == APValue::Int)
2916 return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
2917 RHSValue.getInt(), Result);
2918 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\""
, "clang/lib/AST/ExprConstant.cpp", 2918, __extension__ __PRETTY_FUNCTION__
))
;
2919 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
2920 RHSValue.getFloat(), Result);
2921}
2922
2923template <typename APTy>
2924static bool
2925handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
2926 const APTy &RHSValue, APInt &Result) {
2927 switch (Opcode) {
2928 default:
2929 llvm_unreachable("unsupported binary operator")::llvm::llvm_unreachable_internal("unsupported binary operator"
, "clang/lib/AST/ExprConstant.cpp", 2929)
;
2930 case BO_EQ:
2931 Result = (LHSValue == RHSValue);
2932 break;
2933 case BO_NE:
2934 Result = (LHSValue != RHSValue);
2935 break;
2936 case BO_LT:
2937 Result = (LHSValue < RHSValue);
2938 break;
2939 case BO_GT:
2940 Result = (LHSValue > RHSValue);
2941 break;
2942 case BO_LE:
2943 Result = (LHSValue <= RHSValue);
2944 break;
2945 case BO_GE:
2946 Result = (LHSValue >= RHSValue);
2947 break;
2948 }
2949
2950 // The boolean operations on these vector types use an instruction that
2951 // results in a mask of '-1' for the 'truth' value. Ensure that we negate 1
2952 // to -1 to make sure that we produce the correct value.
2953 Result.negate();
2954
2955 return true;
2956}
2957
2958static bool handleCompareOpForVector(const APValue &LHSValue,
2959 BinaryOperatorKind Opcode,
2960 const APValue &RHSValue, APInt &Result) {
2961 // The result is always an int type, however operands match the first.
2962 if (LHSValue.getKind() == APValue::Int)
2963 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
2964 RHSValue.getInt(), Result);
2965 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\""
, "clang/lib/AST/ExprConstant.cpp", 2965, __extension__ __PRETTY_FUNCTION__
))
;
2966 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
2967 RHSValue.getFloat(), Result);
2968}
2969
2970// Perform binary operations for vector types, in place on the LHS.
2971static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
2972 BinaryOperatorKind Opcode,
2973 APValue &LHSValue,
2974 const APValue &RHSValue) {
2975 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\""
, "clang/lib/AST/ExprConstant.cpp", 2976, __extension__ __PRETTY_FUNCTION__
))
2976 "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\""
, "clang/lib/AST/ExprConstant.cpp", 2976, __extension__ __PRETTY_FUNCTION__
))
;
2977
2978 const auto *VT = E->getType()->castAs<VectorType>();
2979 unsigned NumElements = VT->getNumElements();
2980 QualType EltTy = VT->getElementType();
2981
2982 // In the cases (typically C as I've observed) where we aren't evaluating
2983 // constexpr but are checking for cases where the LHS isn't yet evaluatable,
2984 // just give up.
2985 if (!LHSValue.isVector()) {
2986 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\""
, "clang/lib/AST/ExprConstant.cpp", 2987, __extension__ __PRETTY_FUNCTION__
))
2987 "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\""
, "clang/lib/AST/ExprConstant.cpp", 2987, __extension__ __PRETTY_FUNCTION__
))
;
2988 Info.FFDiag(E);
2989 return false;
2990 }
2991
2992 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\""
, "clang/lib/AST/ExprConstant.cpp", 2993, __extension__ __PRETTY_FUNCTION__
))
2993 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\""
, "clang/lib/AST/ExprConstant.cpp", 2993, __extension__ __PRETTY_FUNCTION__
))
;
2994
2995 SmallVector<APValue, 4> ResultElements;
2996
2997 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
2998 APValue LHSElt = LHSValue.getVectorElt(EltNum);
2999 APValue RHSElt = RHSValue.getVectorElt(EltNum);
3000
3001 if (EltTy->isIntegerType()) {
3002 APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
3003 EltTy->isUnsignedIntegerType()};
3004 bool Success = true;
3005
3006 if (BinaryOperator::isLogicalOp(Opcode))
3007 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3008 else if (BinaryOperator::isComparisonOp(Opcode))
3009 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
3010 else
3011 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
3012 RHSElt.getInt(), EltResult);
3013
3014 if (!Success) {
3015 Info.FFDiag(E);
3016 return false;
3017 }
3018 ResultElements.emplace_back(EltResult);
3019
3020 } else if (EltTy->isFloatingType()) {
3021 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\""
, "clang/lib/AST/ExprConstant.cpp", 3023, __extension__ __PRETTY_FUNCTION__
))
3022 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\""
, "clang/lib/AST/ExprConstant.cpp", 3023, __extension__ __PRETTY_FUNCTION__
))
3023 "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\""
, "clang/lib/AST/ExprConstant.cpp", 3023, __extension__ __PRETTY_FUNCTION__
))
;
3024 APFloat LHSFloat = LHSElt.getFloat();
3025
3026 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
3027 RHSElt.getFloat())) {
3028 Info.FFDiag(E);
3029 return false;
3030 }
3031
3032 ResultElements.emplace_back(LHSFloat);
3033 }
3034 }
3035
3036 LHSValue = APValue(ResultElements.data(), ResultElements.size());
3037 return true;
3038}
3039
3040/// Cast an lvalue referring to a base subobject to a derived class, by
3041/// truncating the lvalue's path to the given length.
3042static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3043 const RecordDecl *TruncatedType,
3044 unsigned TruncatedElements) {
3045 SubobjectDesignator &D = Result.Designator;
3046
3047 // Check we actually point to a derived class object.
3048 if (TruncatedElements == D.Entries.size())
3049 return true;
3050 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\""
, "clang/lib/AST/ExprConstant.cpp", 3051, __extension__ __PRETTY_FUNCTION__
))
3051 "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\""
, "clang/lib/AST/ExprConstant.cpp", 3051, __extension__ __PRETTY_FUNCTION__
))
;
3052 if (!Result.checkSubobject(Info, E, CSK_Derived))
3053 return false;
3054
3055 // Truncate the path to the subobject, and remove any derived-to-base offsets.
3056 const RecordDecl *RD = TruncatedType;
3057 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3058 if (RD->isInvalidDecl()) return false;
3059 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
3060 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
3061 if (isVirtualBaseClass(D.Entries[I]))
3062 Result.Offset -= Layout.getVBaseClassOffset(Base);
3063 else
3064 Result.Offset -= Layout.getBaseClassOffset(Base);
3065 RD = Base;
3066 }
3067 D.Entries.resize(TruncatedElements);
3068 return true;
3069}
3070
3071static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3072 const CXXRecordDecl *Derived,
3073 const CXXRecordDecl *Base,
3074 const ASTRecordLayout *RL = nullptr) {
3075 if (!RL) {
3076 if (Derived->isInvalidDecl()) return false;
3077 RL = &Info.Ctx.getASTRecordLayout(Derived);
3078 }
3079
3080 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3081 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3082 return true;
3083}
3084
3085static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3086 const CXXRecordDecl *DerivedDecl,
3087 const CXXBaseSpecifier *Base) {
3088 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3089
3090 if (!Base->isVirtual())
3091 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
3092
3093 SubobjectDesignator &D = Obj.Designator;
3094 if (D.Invalid)
3095 return false;
3096
3097 // Extract most-derived object and corresponding type.
3098 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
3099 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3100 return false;
3101
3102 // Find the virtual base class.
3103 if (DerivedDecl->isInvalidDecl()) return false;
3104 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3105 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
3106 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3107 return true;
3108}
3109
3110static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3111 QualType Type, LValue &Result) {
3112 for (CastExpr::path_const_iterator PathI = E->path_begin(),
3113 PathE = E->path_end();
3114 PathI != PathE; ++PathI) {
3115 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3116 *PathI))
3117 return false;
3118 Type = (*PathI)->getType();
3119 }
3120 return true;
3121}
3122
3123/// Cast an lvalue referring to a derived class to a known base subobject.
3124static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3125 const CXXRecordDecl *DerivedRD,
3126 const CXXRecordDecl *BaseRD) {
3127 CXXBasePaths Paths(/*FindAmbiguities=*/false,
3128 /*RecordPaths=*/true, /*DetectVirtual=*/false);
3129 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
3130 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!"
, "clang/lib/AST/ExprConstant.cpp", 3130)
;
3131
3132 for (CXXBasePathElement &Elem : Paths.front())
3133 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
3134 return false;
3135 return true;
3136}
3137
3138/// Update LVal to refer to the given field, which must be a member of the type
3139/// currently described by LVal.
3140static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3141 const FieldDecl *FD,
3142 const ASTRecordLayout *RL = nullptr) {
3143 if (!RL) {
3144 if (FD->getParent()->isInvalidDecl()) return false;
3145 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
3146 }
3147
3148 unsigned I = FD->getFieldIndex();
3149 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
3150 LVal.addDecl(Info, E, FD);
3151 return true;
3152}
3153
3154/// Update LVal to refer to the given indirect field.
3155static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3156 LValue &LVal,
3157 const IndirectFieldDecl *IFD) {
3158 for (const auto *C : IFD->chain())
3159 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
3160 return false;
3161 return true;
3162}
3163
3164/// Get the size of the given type in char units.
3165static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
3166 QualType Type, CharUnits &Size) {
3167 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3168 // extension.
3169 if (Type->isVoidType() || Type->isFunctionType()) {
3170 Size = CharUnits::One();
3171 return true;
3172 }
3173
3174 if (Type->isDependentType()) {
3175 Info.FFDiag(Loc);
3176 return false;
3177 }
3178
3179 if (!Type->isConstantSizeType()) {
3180 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3181 // FIXME: Better diagnostic.
3182 Info.FFDiag(Loc);
3183 return false;
3184 }
3185
3186 Size = Info.Ctx.getTypeSizeInChars(Type);
3187 return true;
3188}
3189
3190/// Update a pointer value to model pointer arithmetic.
3191/// \param Info - Information about the ongoing evaluation.
3192/// \param E - The expression being evaluated, for diagnostic purposes.
3193/// \param LVal - The pointer value to be updated.
3194/// \param EltTy - The pointee type represented by LVal.
3195/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
3196static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3197 LValue &LVal, QualType EltTy,
3198 APSInt Adjustment) {
3199 CharUnits SizeOfPointee;
3200 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
3201 return false;
3202
3203 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
3204 return true;
3205}
3206
3207static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3208 LValue &LVal, QualType EltTy,
3209 int64_t Adjustment) {
3210 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3211 APSInt::get(Adjustment));
3212}
3213
3214/// Update an lvalue to refer to a component of a complex number.
3215/// \param Info - Information about the ongoing evaluation.
3216/// \param LVal - The lvalue to be updated.
3217/// \param EltTy - The complex number's component type.
3218/// \param Imag - False for the real component, true for the imaginary.
3219static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3220 LValue &LVal, QualType EltTy,
3221 bool Imag) {
3222 if (Imag) {
3223 CharUnits SizeOfComponent;
3224 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
3225 return false;
3226 LVal.Offset += SizeOfComponent;
3227 }
3228 LVal.addComplex(Info, E, EltTy, Imag);
3229 return true;
3230}
3231
3232/// Try to evaluate the initializer for a variable declaration.
3233///
3234/// \param Info Information about the ongoing evaluation.
3235/// \param E An expression to be used when printing diagnostics.
3236/// \param VD The variable whose initializer should be obtained.
3237/// \param Version The version of the variable within the frame.
3238/// \param Frame The frame in which the variable was created. Must be null
3239/// if this variable is not local to the evaluation.
3240/// \param Result Filled in with a pointer to the value of the variable.
3241static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3242 const VarDecl *VD, CallStackFrame *Frame,
3243 unsigned Version, APValue *&Result) {
3244 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3245
3246 // If this is a local variable, dig out its value.
3247 if (Frame) {
3248 Result = Frame->getTemporary(VD, Version);
3249 if (Result)
3250 return true;
3251
3252 if (!isa<ParmVarDecl>(VD)) {
3253 // Assume variables referenced within a lambda's call operator that were
3254 // not declared within the call operator are captures and during checking
3255 // of a potential constant expression, assume they are unknown constant
3256 // expressions.
3257 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\""
, "clang/lib/AST/ExprConstant.cpp", 3259, __extension__ __PRETTY_FUNCTION__
))
3258 (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\""
, "clang/lib/AST/ExprConstant.cpp", 3259, __extension__ __PRETTY_FUNCTION__
))
3259 "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\""
, "clang/lib/AST/ExprConstant.cpp", 3259, __extension__ __PRETTY_FUNCTION__
))
;
3260 if (Info.checkingPotentialConstantExpression())
3261 return false;
3262 // FIXME: This diagnostic is bogus; we do support captures. Is this code
3263 // still reachable at all?
3264 Info.FFDiag(E->getBeginLoc(),
3265 diag::note_unimplemented_constexpr_lambda_feature_ast)
3266 << "captures not currently allowed";
3267 return false;
3268 }
3269 }
3270
3271 // If we're currently evaluating the initializer of this declaration, use that
3272 // in-flight value.
3273 if (Info.EvaluatingDecl == Base) {
3274 Result = Info.EvaluatingDeclValue;
3275 return true;
3276 }
3277
3278 if (isa<ParmVarDecl>(VD)) {
3279 // Assume parameters of a potential constant expression are usable in
3280 // constant expressions.
3281 if (!Info.checkingPotentialConstantExpression() ||
3282 !Info.CurrentCall->Callee ||
3283 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
3284 if (Info.getLangOpts().CPlusPlus11) {
3285 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3286 << VD;
3287 NoteLValueLocation(Info, Base);
3288 } else {
3289 Info.FFDiag(E);
3290 }
3291 }
3292 return false;
3293 }
3294
3295 // Dig out the initializer, and use the declaration which it's attached to.
3296 // FIXME: We should eventually check whether the variable has a reachable
3297 // initializing declaration.
3298 const Expr *Init = VD->getAnyInitializer(VD);
3299 if (!Init) {
3300 // Don't diagnose during potential constant expression checking; an
3301 // initializer might be added later.
3302 if (!Info.checkingPotentialConstantExpression()) {
3303 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3304 << VD;
3305 NoteLValueLocation(Info, Base);
3306 }
3307 return false;
3308 }
3309
3310 if (Init->isValueDependent()) {
3311 // The DeclRefExpr is not value-dependent, but the variable it refers to
3312 // has a value-dependent initializer. This should only happen in
3313 // constant-folding cases, where the variable is not actually of a suitable
3314 // type for use in a constant expression (otherwise the DeclRefExpr would
3315 // have been value-dependent too), so diagnose that.
3316 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx))(static_cast <bool> (!VD->mightBeUsableInConstantExpressions
(Info.Ctx)) ? void (0) : __assert_fail ("!VD->mightBeUsableInConstantExpressions(Info.Ctx)"
, "clang/lib/AST/ExprConstant.cpp", 3316, __extension__ __PRETTY_FUNCTION__
))
;
3317 if (!Info.checkingPotentialConstantExpression()) {
3318 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3319 ? diag::note_constexpr_ltor_non_constexpr
3320 : diag::note_constexpr_ltor_non_integral, 1)
3321 << VD << VD->getType();
3322 NoteLValueLocation(Info, Base);
3323 }
3324 return false;
3325 }
3326
3327 // Check that we can fold the initializer. In C++, we will have already done
3328 // this in the cases where it matters for conformance.
3329 if (!VD->evaluateValue()) {
3330 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3331 NoteLValueLocation(Info, Base);
3332 return false;
3333 }
3334
3335 // Check that the variable is actually usable in constant expressions. For a
3336 // const integral variable or a reference, we might have a non-constant
3337 // initializer that we can nonetheless evaluate the initializer for. Such
3338 // variables are not usable in constant expressions. In C++98, the
3339 // initializer also syntactically needs to be an ICE.
3340 //
3341 // FIXME: We don't diagnose cases that aren't potentially usable in constant
3342 // expressions here; doing so would regress diagnostics for things like
3343 // reading from a volatile constexpr variable.
3344 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3345 VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
3346 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3347 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
3348 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3349 NoteLValueLocation(Info, Base);
3350 }
3351
3352 // Never use the initializer of a weak variable, not even for constant
3353 // folding. We can't be sure that this is the definition that will be used.
3354 if (VD->isWeak()) {
3355 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3356 NoteLValueLocation(Info, Base);
3357 return false;
3358 }
3359
3360 Result = VD->getEvaluatedValue();
3361 return true;
3362}
3363
3364/// Get the base index of the given base class within an APValue representing
3365/// the given derived class.
3366static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3367 const CXXRecordDecl *Base) {
3368 Base = Base->getCanonicalDecl();
3369 unsigned Index = 0;
3370 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3371 E = Derived->bases_end(); I != E; ++I, ++Index) {
3372 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3373 return Index;
3374 }
3375
3376 llvm_unreachable("base class missing from derived class's bases list")::llvm::llvm_unreachable_internal("base class missing from derived class's bases list"
, "clang/lib/AST/ExprConstant.cpp", 3376)
;
3377}
3378
3379/// Extract the value of a character from a string literal.
3380static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3381 uint64_t Index) {
3382 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\""
, "clang/lib/AST/ExprConstant.cpp", 3383, __extension__ __PRETTY_FUNCTION__
))
3383 "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\""
, "clang/lib/AST/ExprConstant.cpp", 3383, __extension__ __PRETTY_FUNCTION__
))
;
3384
3385 // FIXME: Support MakeStringConstant
3386 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
3387 std::string Str;
3388 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
3389 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\""
, "clang/lib/AST/ExprConstant.cpp", 3389, __extension__ __PRETTY_FUNCTION__
))
;
3390 return APSInt::getUnsigned(Str.c_str()[Index]);
3391 }
3392
3393 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
3394 Lit = PE->getFunctionName();
3395 const StringLiteral *S = cast<StringLiteral>(Lit);
3396 const ConstantArrayType *CAT =
3397 Info.Ctx.getAsConstantArrayType(S->getType());
3398 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\""
, "clang/lib/AST/ExprConstant.cpp", 3398, __extension__ __PRETTY_FUNCTION__
))
;
3399 QualType CharType = CAT->getElementType();
3400 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "clang/lib/AST/ExprConstant.cpp", 3400, __extension__ __PRETTY_FUNCTION__
))
;
3401
3402 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3403 CharType->isUnsignedIntegerType());
3404 if (Index < S->getLength())
3405 Value = S->getCodeUnit(Index);
3406 return Value;
3407}
3408
3409// Expand a string literal into an array of characters.
3410//
3411// FIXME: This is inefficient; we should probably introduce something similar
3412// to the LLVM ConstantDataArray to make this cheaper.
3413static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3414 APValue &Result,
3415 QualType AllocType = QualType()) {
3416 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3417 AllocType.isNull() ? S->getType() : AllocType);
3418 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\""
, "clang/lib/AST/ExprConstant.cpp", 3418, __extension__ __PRETTY_FUNCTION__
))
;
3419 QualType CharType = CAT->getElementType();
3420 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "clang/lib/AST/ExprConstant.cpp", 3420, __extension__ __PRETTY_FUNCTION__
))
;
3421
3422 unsigned Elts = CAT->getSize().getZExtValue();
3423 Result = APValue(APValue::UninitArray(),
3424 std::min(S->getLength(), Elts), Elts);
3425 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
3426 CharType->isUnsignedIntegerType());
3427 if (Result.hasArrayFiller())
3428 Result.getArrayFiller() = APValue(Value);
3429 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3430 Value = S->getCodeUnit(I);
3431 Result.getArrayInitializedElt(I) = APValue(Value);
3432 }
3433}
3434
3435// Expand an array so that it has more than Index filled elements.
3436static void expandArray(APValue &Array, unsigned Index) {
3437 unsigned Size = Array.getArraySize();
3438 assert(Index < Size)(static_cast <bool> (Index < Size) ? void (0) : __assert_fail
("Index < Size", "clang/lib/AST/ExprConstant.cpp", 3438, __extension__
__PRETTY_FUNCTION__))
;
3439
3440 // Always at least double the number of elements for which we store a value.
3441 unsigned OldElts = Array.getArrayInitializedElts();
3442 unsigned NewElts = std::max(Index+1, OldElts * 2);
3443 NewElts = std::min(Size, std::max(NewElts, 8u));
3444
3445 // Copy the data across.
3446 APValue NewValue(APValue::UninitArray(), NewElts, Size);
3447 for (unsigned I = 0; I != OldElts; ++I)
3448 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
3449 for (unsigned I = OldElts; I != NewElts; ++I)
3450 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3451 if (NewValue.hasArrayFiller())
3452 NewValue.getArrayFiller() = Array.getArrayFiller();
3453 Array.swap(NewValue);
3454}
3455
3456/// Determine whether a type would actually be read by an lvalue-to-rvalue
3457/// conversion. If it's of class type, we may assume that the copy operation
3458/// is trivial. Note that this is never true for a union type with fields
3459/// (because the copy always "reads" the active member) and always true for
3460/// a non-class type.
3461static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
3462static bool isReadByLvalueToRvalueConversion(QualType T) {
3463 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3464 return !RD || isReadByLvalueToRvalueConversion(RD);
3465}
3466static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3467 // FIXME: A trivial copy of a union copies the object representation, even if
3468 // the union is empty.
3469 if (RD->isUnion())
3470 return !RD->field_empty();
3471 if (RD->isEmpty())
3472 return false;
3473
3474 for (auto *Field : RD->fields())
3475 if (!Field->isUnnamedBitfield() &&
3476 isReadByLvalueToRvalueConversion(Field->getType()))
3477 return true;
3478
3479 for (auto &BaseSpec : RD->bases())
3480 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
3481 return true;
3482
3483 return false;
3484}
3485
3486/// Diagnose an attempt to read from any unreadable field within the specified
3487/// type, which might be a class type.
3488static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3489 QualType T) {
3490 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3491 if (!RD)
3492 return false;
3493
3494 if (!RD->hasMutableFields())
3495 return false;
3496
3497 for (auto *Field : RD->fields()) {
3498 // If we're actually going to read this field in some way, then it can't
3499 // be mutable. If we're in a union, then assigning to a mutable field
3500 // (even an empty one) can change the active member, so that's not OK.
3501 // FIXME: Add core issue number for the union case.
3502 if (Field->isMutable() &&
3503 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3504 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3505 Info.Note(Field->getLocation(), diag::note_declared_at);
3506 return true;
3507 }
3508
3509 if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3510 return true;
3511 }
3512
3513 for (auto &BaseSpec : RD->bases())
3514 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
3515 return true;
3516
3517 // All mutable fields were empty, and thus not actually read.
3518 return false;
3519}
3520
3521static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3522 APValue::LValueBase Base,
3523 bool MutableSubobject = false) {
3524 // A temporary or transient heap allocation we created.
3525 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3526 return true;
3527
3528 switch (Info.IsEvaluatingDecl) {
3529 case EvalInfo::EvaluatingDeclKind::None:
3530 return false;
3531
3532 case EvalInfo::EvaluatingDeclKind::Ctor:
3533 // The variable whose initializer we're evaluating.
3534 if (Info.EvaluatingDecl == Base)
3535 return true;
3536
3537 // A temporary lifetime-extended by the variable whose initializer we're
3538 // evaluating.
3539 if (auto *BaseE = Base.dyn_cast<const Expr *>())
3540 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
3541 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3542 return false;
3543
3544 case EvalInfo::EvaluatingDeclKind::Dtor:
3545 // C++2a [expr.const]p6:
3546 // [during constant destruction] the lifetime of a and its non-mutable
3547 // subobjects (but not its mutable subobjects) [are] considered to start
3548 // within e.
3549 if (MutableSubobject || Base != Info.EvaluatingDecl)
3550 return false;
3551 // FIXME: We can meaningfully extend this to cover non-const objects, but
3552 // we will need special handling: we should be able to access only
3553 // subobjects of such objects that are themselves declared const.
3554 QualType T = getType(Base);
3555 return T.isConstQualified() || T->isReferenceType();
3556 }
3557
3558 llvm_unreachable("unknown evaluating decl kind")::llvm::llvm_unreachable_internal("unknown evaluating decl kind"
, "clang/lib/AST/ExprConstant.cpp", 3558)
;
3559}
3560
3561namespace {
3562/// A handle to a complete object (an object that is not a subobject of
3563/// another object).
3564struct CompleteObject {
3565 /// The identity of the object.
3566 APValue::LValueBase Base;
3567 /// The value of the complete object.
3568 APValue *Value;
3569 /// The type of the complete object.
3570 QualType Type;
3571
3572 CompleteObject() : Value(nullptr) {}
3573 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3574 : Base(Base), Value(Value), Type(Type) {}
3575
3576 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3577 // If this isn't a "real" access (eg, if it's just accessing the type
3578 // info), allow it. We assume the type doesn't change dynamically for
3579 // subobjects of constexpr objects (even though we'd hit UB here if it
3580 // did). FIXME: Is this right?
3581 if (!isAnyAccess(AK))
3582 return true;
3583
3584 // In C++14 onwards, it is permitted to read a mutable member whose
3585 // lifetime began within the evaluation.
3586 // FIXME: Should we also allow this in C++11?
3587 if (!Info.getLangOpts().CPlusPlus14)
3588 return false;
3589 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3590 }
3591
3592 explicit operator bool() const { return !Type.isNull(); }
3593};
3594} // end anonymous namespace
3595
3596static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3597 bool IsMutable = false) {
3598 // C++ [basic.type.qualifier]p1:
3599 // - A const object is an object of type const T or a non-mutable subobject
3600 // of a const object.
3601 if (ObjType.isConstQualified() && !IsMutable)
3602 SubobjType.addConst();
3603 // - A volatile object is an object of type const T or a subobject of a
3604 // volatile object.
3605 if (ObjType.isVolatileQualified())
3606 SubobjType.addVolatile();
3607 return SubobjType;
3608}
3609
3610/// Find the designated sub-object of an rvalue.
3611template<typename SubobjectHandler>
3612typename SubobjectHandler::result_type
3613findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3614 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3615 if (Sub.Invalid)
3616 // A diagnostic will have already been produced.
3617 return handler.failed();
3618 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3619 if (Info.getLangOpts().CPlusPlus11)
3620 Info.FFDiag(E, Sub.isOnePastTheEnd()
3621 ? diag::note_constexpr_access_past_end
3622 : diag::note_constexpr_access_unsized_array)
3623 << handler.AccessKind;
3624 else
3625 Info.FFDiag(E);
3626 return handler.failed();
3627 }
3628
3629 APValue *O = Obj.Value;
3630 QualType ObjType = Obj.Type;
3631 const FieldDecl *LastField = nullptr;
3632 const FieldDecl *VolatileField = nullptr;
3633
3634 // Walk the designator's path to find the subobject.
3635 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3636 // Reading an indeterminate value is undefined, but assigning over one is OK.
3637 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3638 (O->isIndeterminate() &&
3639 !isValidIndeterminateAccess(handler.AccessKind))) {
3640 if (!Info.checkingPotentialConstantExpression())
3641 Info.FFDiag(E, diag::note_constexpr_access_uninit)
3642 << handler.AccessKind << O->isIndeterminate();
3643 return handler.failed();
3644 }
3645
3646 // C++ [class.ctor]p5, C++ [class.dtor]p5:
3647 // const and volatile semantics are not applied on an object under
3648 // {con,de}struction.
3649 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3650 ObjType->isRecordType() &&
3651 Info.isEvaluatingCtorDtor(
3652 Obj.Base,
3653 llvm::ArrayRef(Sub.Entries.begin(), Sub.Entries.begin() + I)) !=
3654 ConstructionPhase::None) {
3655 ObjType = Info.Ctx.getCanonicalType(ObjType);
3656 ObjType.removeLocalConst();
3657 ObjType.removeLocalVolatile();
3658 }
3659
3660 // If this is our last pass, check that the final object type is OK.
3661 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3662 // Accesses to volatile objects are prohibited.
3663 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3664 if (Info.getLangOpts().CPlusPlus) {
3665 int DiagKind;
3666 SourceLocation Loc;
3667 const NamedDecl *Decl = nullptr;
3668 if (VolatileField) {
3669 DiagKind = 2;
3670 Loc = VolatileField->getLocation();
3671 Decl = VolatileField;
3672 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
3673 DiagKind = 1;
3674 Loc = VD->getLocation();
3675 Decl = VD;
3676 } else {
3677 DiagKind = 0;
3678 if (auto *E = Obj.Base.dyn_cast<const Expr *>())
3679 Loc = E->getExprLoc();
3680 }
3681 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3682 << handler.AccessKind << DiagKind << Decl;
3683 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
3684 } else {
3685 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
3686 }
3687 return handler.failed();
3688 }
3689
3690 // If we are reading an object of class type, there may still be more
3691 // things we need to check: if there are any mutable subobjects, we
3692 // cannot perform this read. (This only happens when performing a trivial
3693 // copy or assignment.)
3694 if (ObjType->isRecordType() &&
3695 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
3696 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
3697 return handler.failed();
3698 }
3699
3700 if (I == N) {
3701 if (!handler.found(*O, ObjType))
3702 return false;
3703
3704 // If we modified a bit-field, truncate it to the right width.
3705 if (isModification(handler.AccessKind) &&
3706 LastField && LastField->isBitField() &&
3707 !truncateBitfieldValue(Info, E, *O, LastField))
3708 return false;
3709
3710 return true;
3711 }
3712
3713 LastField = nullptr;
3714 if (ObjType->isArrayType()) {
3715 // Next subobject is an array element.
3716 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
3717 assert(CAT && "vla in literal type?")(static_cast <bool> (CAT && "vla in literal type?"
) ? void (0) : __assert_fail ("CAT && \"vla in literal type?\""
, "clang/lib/AST/ExprConstant.cpp", 3717, __extension__ __PRETTY_FUNCTION__
))
;
3718 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3719 if (CAT->getSize().ule(Index)) {
3720 // Note, it should not be possible to form a pointer with a valid
3721 // designator which points more than one past the end of the array.
3722 if (Info.getLangOpts().CPlusPlus11)
3723 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3724 << handler.AccessKind;
3725 else
3726 Info.FFDiag(E);
3727 return handler.failed();
3728 }
3729
3730 ObjType = CAT->getElementType();
3731
3732 if (O->getArrayInitializedElts() > Index)
3733 O = &O->getArrayInitializedElt(Index);
3734 else if (!isRead(handler.AccessKind)) {
3735 expandArray(*O, Index);
3736 O = &O->getArrayInitializedElt(Index);
3737 } else
3738 O = &O->getArrayFiller();
3739 } else if (ObjType->isAnyComplexType()) {
3740 // Next subobject is a complex number.
3741 uint64_t Index = Sub.Entries[I].getAsArrayIndex();
3742 if (Index > 1) {
3743 if (Info.getLangOpts().CPlusPlus11)
3744 Info.FFDiag(E, diag::note_constexpr_access_past_end)
3745 << handler.AccessKind;
3746 else
3747 Info.FFDiag(E);
3748 return handler.failed();
3749 }
3750
3751 ObjType = getSubobjectType(
3752 ObjType, ObjType->castAs<ComplexType>()->getElementType());
3753
3754 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?\""
, "clang/lib/AST/ExprConstant.cpp", 3754, __extension__ __PRETTY_FUNCTION__
))
;
3755 if (O->isComplexInt()) {
3756 return handler.found(Index ? O->getComplexIntImag()
3757 : O->getComplexIntReal(), ObjType);
3758 } else {
3759 assert(O->isComplexFloat())(static_cast <bool> (O->isComplexFloat()) ? void (0)
: __assert_fail ("O->isComplexFloat()", "clang/lib/AST/ExprConstant.cpp"
, 3759, __extension__ __PRETTY_FUNCTION__))
;
3760 return handler.found(Index ? O->getComplexFloatImag()
3761 : O->getComplexFloatReal(), ObjType);
3762 }
3763 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
3764 if (Field->isMutable() &&
3765 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
3766 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
3767 << handler.AccessKind << Field;
3768 Info.Note(Field->getLocation(), diag::note_declared_at);
3769 return handler.failed();
3770 }
3771
3772 // Next subobject is a class, struct or union field.
3773 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
3774 if (RD->isUnion()) {
3775 const FieldDecl *UnionField = O->getUnionField();
3776 if (!UnionField ||
3777 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
3778 if (I == N - 1 && handler.AccessKind == AK_Construct) {
3779 // Placement new onto an inactive union member makes it active.
3780 O->setUnion(Field, APValue());
3781 } else {
3782 // FIXME: If O->getUnionValue() is absent, report that there's no
3783 // active union member rather than reporting the prior active union
3784 // member. We'll need to fix nullptr_t to not use APValue() as its
3785 // representation first.
3786 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
3787 << handler.AccessKind << Field << !UnionField << UnionField;
3788 return handler.failed();
3789 }
3790 }
3791 O = &O->getUnionValue();
3792 } else
3793 O = &O->getStructField(Field->getFieldIndex());
3794
3795 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
3796 LastField = Field;
3797 if (Field->getType().isVolatileQualified())
3798 VolatileField = Field;
3799 } else {
3800 // Next subobject is a base class.
3801 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
3802 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
3803 O = &O->getStructBase(getBaseIndex(Derived, Base));
3804
3805 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
3806 }
3807 }
3808}
3809
3810namespace {
3811struct ExtractSubobjectHandler {
3812 EvalInfo &Info;
3813 const Expr *E;
3814 APValue &Result;
3815 const AccessKinds AccessKind;
3816
3817 typedef bool result_type;
3818 bool failed() { return false; }
3819 bool found(APValue &Subobj, QualType SubobjType) {
3820 Result = Subobj;
3821 if (AccessKind == AK_ReadObjectRepresentation)
3822 return true;
3823 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
3824 }
3825 bool found(APSInt &Value, QualType SubobjType) {
3826 Result = APValue(Value);
3827 return true;
3828 }
3829 bool found(APFloat &Value, QualType SubobjType) {
3830 Result = APValue(Value);
3831 return true;
3832 }
3833};
3834} // end anonymous namespace
3835
3836/// Extract the designated sub-object of an rvalue.
3837static bool extractSubobject(EvalInfo &Info, const Expr *E,
3838 const CompleteObject &Obj,
3839 const SubobjectDesignator &Sub, APValue &Result,
3840 AccessKinds AK = AK_Read) {
3841 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"
, "clang/lib/AST/ExprConstant.cpp", 3841, __extension__ __PRETTY_FUNCTION__
))
;
3842 ExtractSubobjectHandler Handler = {Info, E, Result, AK};
3843 return findSubobject(Info, E, Obj, Sub, Handler);
3844}
3845
3846namespace {
3847struct ModifySubobjectHandler {
3848 EvalInfo &Info;
3849 APValue &NewVal;
3850 const Expr *E;
3851
3852 typedef bool result_type;
3853 static const AccessKinds AccessKind = AK_Assign;
3854
3855 bool checkConst(QualType QT) {
3856 // Assigning to a const object has undefined behavior.
3857 if (QT.isConstQualified()) {
3858 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3859 return false;
3860 }
3861 return true;
3862 }
3863
3864 bool failed() { return false; }
3865 bool found(APValue &Subobj, QualType SubobjType) {
3866 if (!checkConst(SubobjType))
3867 return false;
3868 // We've been given ownership of NewVal, so just swap it in.
3869 Subobj.swap(NewVal);
3870 return true;
3871 }
3872 bool found(APSInt &Value, QualType SubobjType) {
3873 if (!checkConst(SubobjType))
3874 return false;
3875 if (!NewVal.isInt()) {
3876 // Maybe trying to write a cast pointer value into a complex?
3877 Info.FFDiag(E);
3878 return false;
3879 }
3880 Value = NewVal.getInt();
3881 return true;
3882 }
3883 bool found(APFloat &Value, QualType SubobjType) {
3884 if (!checkConst(SubobjType))
3885 return false;
3886 Value = NewVal.getFloat();
3887 return true;
3888 }
3889};
3890} // end anonymous namespace
3891
3892const AccessKinds ModifySubobjectHandler::AccessKind;
3893
3894/// Update the designated sub-object of an rvalue to the given value.
3895static bool modifySubobject(EvalInfo &Info, const Expr *E,
3896 const CompleteObject &Obj,
3897 const SubobjectDesignator &Sub,
3898 APValue &NewVal) {
3899 ModifySubobjectHandler Handler = { Info, NewVal, E };
3900 return findSubobject(Info, E, Obj, Sub, Handler);
3901}
3902
3903/// Find the position where two subobject designators diverge, or equivalently
3904/// the length of the common initial subsequence.
3905static unsigned FindDesignatorMismatch(QualType ObjType,
3906 const SubobjectDesignator &A,
3907 const SubobjectDesignator &B,
3908 bool &WasArrayIndex) {
3909 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3910 for (/**/; I != N; ++I) {
3911 if (!ObjType.isNull() &&
3912 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3913 // Next subobject is an array element.
3914 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
3915 WasArrayIndex = true;
3916 return I;
3917 }
3918 if (ObjType->isAnyComplexType())
3919 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3920 else
3921 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3922 } else {
3923 if (A.Entries[I].getAsBaseOrMember() !=
3924 B.Entries[I].getAsBaseOrMember()) {
3925 WasArrayIndex = false;
3926 return I;
3927 }
3928 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3929 // Next subobject is a field.
3930 ObjType = FD->getType();
3931 else
3932 // Next subobject is a base class.
3933 ObjType = QualType();
3934 }
3935 }
3936 WasArrayIndex = false;
3937 return I;
3938}
3939
3940/// Determine whether the given subobject designators refer to elements of the
3941/// same array object.
3942static bool AreElementsOfSameArray(QualType ObjType,
3943 const SubobjectDesignator &A,
3944 const SubobjectDesignator &B) {
3945 if (A.Entries.size() != B.Entries.size())
3946 return false;
3947
3948 bool IsArray = A.MostDerivedIsArrayElement;
3949 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3950 // A is a subobject of the array element.
3951 return false;
3952
3953 // If A (and B) designates an array element, the last entry will be the array
3954 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3955 // of length 1' case, and the entire path must match.
3956 bool WasArrayIndex;
3957 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3958 return CommonLength >= A.Entries.size() - IsArray;
3959}
3960
3961/// Find the complete object to which an LValue refers.
3962static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3963 AccessKinds AK, const LValue &LVal,
3964 QualType LValType) {
3965 if (LVal.InvalidBase) {
3966 Info.FFDiag(E);
3967 return CompleteObject();
3968 }
3969
3970 if (!LVal.Base) {
3971 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3972 return CompleteObject();
3973 }
3974
3975 CallStackFrame *Frame = nullptr;
3976 unsigned Depth = 0;
3977 if (LVal.getLValueCallIndex()) {
3978 std::tie(Frame, Depth) =
3979 Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
3980 if (!Frame) {
3981 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3982 << AK << LVal.Base.is<const ValueDecl*>();
3983 NoteLValueLocation(Info, LVal.Base);
3984 return CompleteObject();
3985 }
3986 }
3987
3988 bool IsAccess = isAnyAccess(AK);
3989
3990 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3991 // is not a constant expression (even if the object is non-volatile). We also
3992 // apply this rule to C++98, in order to conform to the expected 'volatile'
3993 // semantics.
3994 if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
3995 if (Info.getLangOpts().CPlusPlus)
3996 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3997 << AK << LValType;
3998 else
3999 Info.FFDiag(E);
4000 return CompleteObject();
4001 }
4002
4003 // Compute value storage location and type of base object.
4004 APValue *BaseVal = nullptr;
4005 QualType BaseType = getType(LVal.Base);
4006
4007 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
4008 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4009 // This is the object whose initializer we're evaluating, so its lifetime
4010 // started in the current evaluation.
4011 BaseVal = Info.EvaluatingDeclValue;
4012 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
4013 // Allow reading from a GUID declaration.
4014 if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
4015 if (isModification(AK)) {
4016 // All the remaining cases do not permit modification of the object.
4017 Info.FFDiag(E, diag::note_constexpr_modify_global);
4018 return CompleteObject();
4019 }
4020 APValue &V = GD->getAsAPValue();
4021 if (V.isAbsent()) {
4022 Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4023 << GD->getType();
4024 return CompleteObject();
4025 }
4026 return CompleteObject(LVal.Base, &V, GD->getType());
4027 }
4028
4029 // Allow reading the APValue from an UnnamedGlobalConstantDecl.
4030 if (auto *GCD = dyn_cast<UnnamedGlobalConstantDecl>(D)) {
4031 if (isModification(AK)) {
4032 Info.FFDiag(E, diag::note_constexpr_modify_global);
4033 return CompleteObject();
4034 }
4035 return CompleteObject(LVal.Base, const_cast<APValue *>(&GCD->getValue()),
4036 GCD->getType());
4037 }
4038
4039 // Allow reading from template parameter objects.
4040 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
4041 if (isModification(AK)) {
4042 Info.FFDiag(E, diag::note_constexpr_modify_global);
4043 return CompleteObject();
4044 }
4045 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4046 TPO->getType());
4047 }
4048
4049 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4050 // In C++11, constexpr, non-volatile variables initialized with constant
4051 // expressions are constant expressions too. Inside constexpr functions,
4052 // parameters are constant expressions even if they're non-const.
4053 // In C++1y, objects local to a constant expression (those with a Frame) are
4054 // both readable and writable inside constant expressions.
4055 // In C, such things can also be folded, although they are not ICEs.
4056 const VarDecl *VD = dyn_cast<VarDecl>(D);
4057 if (VD) {
4058 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
4059 VD = VDef;
4060 }
4061 if (!VD || VD->isInvalidDecl()) {
4062 Info.FFDiag(E);
4063 return CompleteObject();
4064 }
4065
4066 bool IsConstant = BaseType.isConstant(Info.Ctx);
4067
4068 // Unless we're looking at a local variable or argument in a constexpr call,
4069 // the variable we're reading must be const.
4070 if (!Frame) {
4071 if (IsAccess && isa<ParmVarDecl>(VD)) {
4072 // Access of a parameter that's not associated with a frame isn't going
4073 // to work out, but we can leave it to evaluateVarDeclInit to provide a
4074 // suitable diagnostic.
4075 } else if (Info.getLangOpts().CPlusPlus14 &&
4076 lifetimeStartedInEvaluation(Info, LVal.Base)) {
4077 // OK, we can read and modify an object if we're in the process of
4078 // evaluating its initializer, because its lifetime began in this
4079 // evaluation.
4080 } else if (isModification(AK)) {
4081 // All the remaining cases do not permit modification of the object.
4082 Info.FFDiag(E, diag::note_constexpr_modify_global);
4083 return CompleteObject();
4084 } else if (VD->isConstexpr()) {
4085 // OK, we can read this variable.
4086 } else if (BaseType->isIntegralOrEnumerationType()) {
4087 if (!IsConstant) {
4088 if (!IsAccess)
4089 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4090 if (Info.getLangOpts().CPlusPlus) {
4091 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4092 Info.Note(VD->getLocation(), diag::note_declared_at);
4093 } else {
4094 Info.FFDiag(E);
4095 }
4096 return CompleteObject();
4097 }
4098 } else if (!IsAccess) {
4099 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4100 } else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4101 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
4102 // This variable might end up being constexpr. Don't diagnose it yet.
4103 } else if (IsConstant) {
4104 // Keep evaluating to see what we can do. In particular, we support
4105 // folding of const floating-point types, in order to make static const
4106 // data members of such types (supported as an extension) more useful.
4107 if (Info.getLangOpts().CPlusPlus) {
4108 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4109 ? diag::note_constexpr_ltor_non_constexpr
4110 : diag::note_constexpr_ltor_non_integral, 1)
4111 << VD << BaseType;
4112 Info.Note(VD->getLocation(), diag::note_declared_at);
4113 } else {
4114 Info.CCEDiag(E);
4115 }
4116 } else {
4117 // Never allow reading a non-const value.
4118 if (Info.getLangOpts().CPlusPlus) {
4119 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4120 ? diag::note_constexpr_ltor_non_constexpr
4121 : diag::note_constexpr_ltor_non_integral, 1)
4122 << VD << BaseType;
4123 Info.Note(VD->getLocation(), diag::note_declared_at);
4124 } else {
4125 Info.FFDiag(E);
4126 }
4127 return CompleteObject();
4128 }
4129 }
4130
4131 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
4132 return CompleteObject();
4133 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4134 std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
4135 if (!Alloc) {
4136 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4137 return CompleteObject();
4138 }
4139 return CompleteObject(LVal.Base, &(*Alloc)->Value,
4140 LVal.Base.getDynamicAllocType());
4141 } else {
4142 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4143
4144 if (!Frame) {
4145 if (const MaterializeTemporaryExpr *MTE =
4146 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
4147 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\""
, "clang/lib/AST/ExprConstant.cpp", 4148, __extension__ __PRETTY_FUNCTION__
))
4148 "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\""
, "clang/lib/AST/ExprConstant.cpp", 4148, __extension__ __PRETTY_FUNCTION__
))
;
4149
4150 // C++20 [expr.const]p4: [DR2126]
4151 // An object or reference is usable in constant expressions if it is
4152 // - a temporary object of non-volatile const-qualified literal type
4153 // whose lifetime is extended to that of a variable that is usable
4154 // in constant expressions
4155 //
4156 // C++20 [expr.const]p5:
4157 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4158 // - a non-volatile glvalue that refers to an object that is usable
4159 // in constant expressions, or
4160 // - a non-volatile glvalue of literal type that refers to a
4161 // non-volatile object whose lifetime began within the evaluation
4162 // of E;
4163 //
4164 // C++11 misses the 'began within the evaluation of e' check and
4165 // instead allows all temporaries, including things like:
4166 // int &&r = 1;
4167 // int x = ++r;
4168 // constexpr int k = r;
4169 // Therefore we use the C++14-onwards rules in C++11 too.
4170 //
4171 // Note that temporaries whose lifetimes began while evaluating a
4172 // variable's constructor are not usable while evaluating the
4173 // corresponding destructor, not even if they're of const-qualified
4174 // types.
4175 if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
4176 !lifetimeStartedInEvaluation(Info, LVal.Base)) {
4177 if (!IsAccess)
4178 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4179 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4180 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4181 return CompleteObject();
4182 }
4183
4184 BaseVal = MTE->getOrCreateValue(false);
4185 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\""
, "clang/lib/AST/ExprConstant.cpp", 4185, __extension__ __PRETTY_FUNCTION__
))
;
4186 } else {
4187 if (!IsAccess)
4188 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4189 APValue Val;
4190 LVal.moveInto(Val);
4191 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4192 << AK
4193 << Val.getAsString(Info.Ctx,
4194 Info.Ctx.getLValueReferenceType(LValType));
4195 NoteLValueLocation(Info, LVal.Base);
4196 return CompleteObject();
4197 }
4198 } else {
4199 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
4200 assert(BaseVal && "missing value for temporary")(static_cast <bool> (BaseVal && "missing value for temporary"
) ? void (0) : __assert_fail ("BaseVal && \"missing value for temporary\""
, "clang/lib/AST/ExprConstant.cpp", 4200, __extension__ __PRETTY_FUNCTION__
))
;
4201 }
4202 }
4203
4204 // In C++14, we can't safely access any mutable state when we might be
4205 // evaluating after an unmodeled side effect. Parameters are modeled as state
4206 // in the caller, but aren't visible once the call returns, so they can be
4207 // modified in a speculatively-evaluated call.
4208 //
4209 // FIXME: Not all local state is mutable. Allow local constant subobjects
4210 // to be read here (but take care with 'mutable' fields).
4211 unsigned VisibleDepth = Depth;
4212 if (llvm::isa_and_nonnull<ParmVarDecl>(
4213 LVal.Base.dyn_cast<const ValueDecl *>()))
4214 ++VisibleDepth;
4215 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4216 Info.EvalStatus.HasSideEffects) ||
4217 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4218 return CompleteObject();
4219
4220 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4221}
4222
4223/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4224/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4225/// glvalue referred to by an entity of reference type.
4226///
4227/// \param Info - Information about the ongoing evaluation.
4228/// \param Conv - The expression for which we are performing the conversion.
4229/// Used for diagnostics.
4230/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4231/// case of a non-class type).
4232/// \param LVal - The glvalue on which we are attempting to perform this action.
4233/// \param RVal - The produced value will be placed here.
4234/// \param WantObjectRepresentation - If true, we're looking for the object
4235/// representation rather than the value, and in particular,
4236/// there is no requirement that the result be fully initialized.
4237static bool
4238handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4239 const LValue &LVal, APValue &RVal,
4240 bool WantObjectRepresentation = false) {
4241 if (LVal.Designator.Invalid)
4242 return false;
4243
4244 // Check for special cases where there is no existing APValue to look at.
4245 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4246
4247 AccessKinds AK =
4248 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4249
4250 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4251 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
4252 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4253 // initializer until now for such expressions. Such an expression can't be
4254 // an ICE in C, so this only matters for fold.
4255 if (Type.isVolatileQualified()) {
4256 Info.FFDiag(Conv);
4257 return false;
4258 }
4259
4260 APValue Lit;
4261 if (!Evaluate(Lit, Info, CLE->getInitializer()))
4262 return false;
4263
4264 // According to GCC info page:
4265 //
4266 // 6.28 Compound Literals
4267 //
4268 // As an optimization, G++ sometimes gives array compound literals longer
4269 // lifetimes: when the array either appears outside a function or has a
4270 // const-qualified type. If foo and its initializer had elements of type
4271 // char *const rather than char *, or if foo were a global variable, the
4272 // array would have static storage duration. But it is probably safest
4273 // just to avoid the use of array compound literals in C++ code.
4274 //
4275 // Obey that rule by checking constness for converted array types.
4276
4277 QualType CLETy = CLE->getType();
4278 if (CLETy->isArrayType() && !Type->isArrayType()) {
4279 if (!CLETy.isConstant(Info.Ctx)) {
4280 Info.FFDiag(Conv);
4281 Info.Note(CLE->getExprLoc(), diag::note_declared_at);
4282 return false;
4283 }
4284 }
4285
4286 CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4287 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4288 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
4289 // Special-case character extraction so we don't have to construct an
4290 // APValue for the whole string.
4291 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\""
, "clang/lib/AST/ExprConstant.cpp", 4292, __extension__ __PRETTY_FUNCTION__
))
4292 "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\""
, "clang/lib/AST/ExprConstant.cpp", 4292, __extension__ __PRETTY_FUNCTION__
))
;
4293 if (LVal.Designator.Entries.empty()) {
4294 // Fail for now for LValue to RValue conversion of an array.
4295 // (This shouldn't show up in C/C++, but it could be triggered by a
4296 // weird EvaluateAsRValue call from a tool.)
4297 Info.FFDiag(Conv);
4298 return false;
4299 }
4300 if (LVal.Designator.isOnePastTheEnd()) {
4301 if (Info.getLangOpts().CPlusPlus11)
4302 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4303 else
4304 Info.FFDiag(Conv);
4305 return false;
4306 }
4307 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4308 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
4309 return true;
4310 }
4311 }
4312
4313 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
4314 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4315}
4316
4317/// Perform an assignment of Val to LVal. Takes ownership of Val.
4318static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4319 QualType LValType, APValue &Val) {
4320 if (LVal.Designator.Invalid)
4321 return false;
4322
4323 if (!Info.getLangOpts().CPlusPlus14) {
4324 Info.FFDiag(E);
4325 return false;
4326 }
4327
4328 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4329 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4330}
4331
4332namespace {
4333struct CompoundAssignSubobjectHandler {
4334 EvalInfo &Info;
4335 const CompoundAssignOperator *E;
4336 QualType PromotedLHSType;
4337 BinaryOperatorKind Opcode;
4338 const APValue &RHS;
4339
4340 static const AccessKinds AccessKind = AK_Assign;
4341
4342 typedef bool result_type;
4343
4344 bool checkConst(QualType QT) {
4345 // Assigning to a const object has undefined behavior.
4346 if (QT.isConstQualified()) {
4347 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4348 return false;
4349 }
4350 return true;
4351 }
4352
4353 bool failed() { return false; }
4354 bool found(APValue &Subobj, QualType SubobjType) {
4355 switch (Subobj.getKind()) {
4356 case APValue::Int:
4357 return found(Subobj.getInt(), SubobjType);
4358 case APValue::Float:
4359 return found(Subobj.getFloat(), SubobjType);
4360 case APValue::ComplexInt:
4361 case APValue::ComplexFloat:
4362 // FIXME: Implement complex compound assignment.
4363 Info.FFDiag(E);
4364 return false;
4365 case APValue::LValue:
4366 return foundPointer(Subobj, SubobjType);
4367 case APValue::Vector:
4368 return foundVector(Subobj, SubobjType);
4369 default:
4370 // FIXME: can this happen?
4371 Info.FFDiag(E);
4372 return false;
4373 }
4374 }
4375
4376 bool foundVector(APValue &Value, QualType SubobjType) {
4377 if (!checkConst(SubobjType))
4378 return false;
4379
4380 if (!SubobjType->isVectorType()) {
4381 Info.FFDiag(E);
4382 return false;
4383 }
4384 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4385 }
4386
4387 bool found(APSInt &Value, QualType SubobjType) {
4388 if (!checkConst(SubobjType))
4389 return false;
4390
4391 if (!SubobjType->isIntegerType()) {
4392 // We don't support compound assignment on integer-cast-to-pointer
4393 // values.
4394 Info.FFDiag(E);
4395 return false;
4396 }
4397
4398 if (RHS.isInt()) {
4399 APSInt LHS =
4400 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4401 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4402 return false;
4403 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4404 return true;
4405 } else if (RHS.isFloat()) {
4406 const FPOptions FPO = E->getFPFeaturesInEffect(
4407 Info.Ctx.getLangOpts());
4408 APFloat FValue(0.0);
4409 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4410 PromotedLHSType, FValue) &&
4411 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4412 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4413 Value);
4414 }
4415
4416 Info.FFDiag(E);
4417 return false;
4418 }
4419 bool found(APFloat &Value, QualType SubobjType) {
4420 return checkConst(SubobjType) &&
4421 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4422 Value) &&
4423 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4424 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4425 }
4426 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4427 if (!checkConst(SubobjType))
4428 return false;
4429
4430 QualType PointeeType;
4431 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4432 PointeeType = PT->getPointeeType();
4433
4434 if (PointeeType.isNull() || !RHS.isInt() ||
4435 (Opcode != BO_Add && Opcode != BO_Sub)) {
4436 Info.FFDiag(E);
4437 return false;
4438 }
4439
4440 APSInt Offset = RHS.getInt();
4441 if (Opcode == BO_Sub)
4442 negateAsSigned(Offset);
4443
4444 LValue LVal;
4445 LVal.setFrom(Info.Ctx, Subobj);
4446 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4447 return false;
4448 LVal.moveInto(Subobj);
4449 return true;
4450 }
4451};
4452} // end anonymous namespace
4453
4454const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4455
4456/// Perform a compound assignment of LVal <op>= RVal.
4457static bool handleCompoundAssignment(EvalInfo &Info,
4458 const CompoundAssignOperator *E,
4459 const LValue &LVal, QualType LValType,
4460 QualType PromotedLValType,
4461 BinaryOperatorKind Opcode,
4462 const APValue &RVal) {
4463 if (LVal.Designator.Invalid)
4464 return false;
4465
4466 if (!Info.getLangOpts().CPlusPlus14) {
4467 Info.FFDiag(E);
4468 return false;
4469 }
4470
4471 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4472 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4473 RVal };
4474 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4475}
4476
4477namespace {
4478struct IncDecSubobjectHandler {
4479 EvalInfo &Info;
4480 const UnaryOperator *E;
4481 AccessKinds AccessKind;
4482 APValue *Old;
4483
4484 typedef bool result_type;
4485
4486 bool checkConst(QualType QT) {
4487 // Assigning to a const object has undefined behavior.
4488 if (QT.isConstQualified()) {
4489 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4490 return false;
4491 }
4492 return true;
4493 }
4494
4495 bool failed() { return false; }
4496 bool found(APValue &Subobj, QualType SubobjType) {
4497 // Stash the old value. Also clear Old, so we don't clobber it later
4498 // if we're post-incrementing a complex.
4499 if (Old) {
4500 *Old = Subobj;
4501 Old = nullptr;
4502 }
4503
4504 switch (Subobj.getKind()) {
4505 case APValue::Int:
4506 return found(Subobj.getInt(), SubobjType);
4507 case APValue::Float:
4508 return found(Subobj.getFloat(), SubobjType);
4509 case APValue::ComplexInt:
4510 return found(Subobj.getComplexIntReal(),
4511 SubobjType->castAs<ComplexType>()->getElementType()
4512 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4513 case APValue::ComplexFloat:
4514 return found(Subobj.getComplexFloatReal(),
4515 SubobjType->castAs<ComplexType>()->getElementType()
4516 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
4517 case APValue::LValue:
4518 return foundPointer(Subobj, SubobjType);
4519 default:
4520 // FIXME: can this happen?
4521 Info.FFDiag(E);
4522 return false;
4523 }
4524 }
4525 bool found(APSInt &Value, QualType SubobjType) {
4526 if (!checkConst(SubobjType))
4527 return false;
4528
4529 if (!SubobjType->isIntegerType()) {
4530 // We don't support increment / decrement on integer-cast-to-pointer
4531 // values.
4532 Info.FFDiag(E);
4533 return false;
4534 }
4535
4536 if (Old) *Old = APValue(Value);
4537
4538 // bool arithmetic promotes to int, and the conversion back to bool
4539 // doesn't reduce mod 2^n, so special-case it.
4540 if (SubobjType->isBooleanType()) {
4541 if (AccessKind == AK_Increment)
4542 Value = 1;
4543 else
4544 Value = !Value;
4545 return true;
4546 }
4547
4548 bool WasNegative = Value.isNegative();
4549 if (AccessKind == AK_Increment) {
4550 ++Value;
4551
4552 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4553 APSInt ActualValue(Value, /*IsUnsigned*/true);
4554 return HandleOverflow(Info, E, ActualValue, SubobjType);
4555 }
4556 } else {
4557 --Value;
4558
4559 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4560 unsigned BitWidth = Value.getBitWidth();
4561 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
4562 ActualValue.setBit(BitWidth);
4563 return HandleOverflow(Info, E, ActualValue, SubobjType);
4564 }
4565 }
4566 return true;
4567 }
4568 bool found(APFloat &Value, QualType SubobjType) {
4569 if (!checkConst(SubobjType))
4570 return false;
4571
4572 if (Old) *Old = APValue(Value);
4573
4574 APFloat One(Value.getSemantics(), 1);
4575 if (AccessKind == AK_Increment)
4576 Value.add(One, APFloat::rmNearestTiesToEven);
4577 else
4578 Value.subtract(One, APFloat::rmNearestTiesToEven);
4579 return true;
4580 }
4581 bool foundPointer(APValue &Subobj, QualType SubobjType) {
4582 if (!checkConst(SubobjType))
4583 return false;
4584
4585 QualType PointeeType;
4586 if (const PointerType *PT = SubobjType->getAs<PointerType>())
4587 PointeeType = PT->getPointeeType();
4588 else {
4589 Info.FFDiag(E);
4590 return false;
4591 }
4592
4593 LValue LVal;
4594 LVal.setFrom(Info.Ctx, Subobj);
4595 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4596 AccessKind == AK_Increment ? 1 : -1))
4597 return false;
4598 LVal.moveInto(Subobj);
4599 return true;
4600 }
4601};
4602} // end anonymous namespace
4603
4604/// Perform an increment or decrement on LVal.
4605static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4606 QualType LValType, bool IsIncrement, APValue *Old) {
4607 if (LVal.Designator.Invalid)
4608 return false;
4609
4610 if (!Info.getLangOpts().CPlusPlus14) {
4611 Info.FFDiag(E);
4612 return false;
4613 }
4614
4615 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4616 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4617 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
4618 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4619}
4620
4621/// Build an lvalue for the object argument of a member function call.
4622static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4623 LValue &This) {
4624 if (Object->getType()->isPointerType() && Object->isPRValue())
4625 return EvaluatePointer(Object, This, Info);
4626
4627 if (Object->isGLValue())
4628 return EvaluateLValue(Object, This, Info);
4629
4630 if (Object->getType()->isLiteralType(Info.Ctx))
4631 return EvaluateTemporary(Object, This, Info);
4632
4633 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
4634 return false;
4635}
4636
4637/// HandleMemberPointerAccess - Evaluate a member access operation and build an
4638/// lvalue referring to the result.
4639///
4640/// \param Info - Information about the ongoing evaluation.
4641/// \param LV - An lvalue referring to the base of the member pointer.
4642/// \param RHS - The member pointer expression.
4643/// \param IncludeMember - Specifies whether the member itself is included in
4644/// the resulting LValue subobject designator. This is not possible when
4645/// creating a bound member function.
4646/// \return The field or method declaration to which the member pointer refers,
4647/// or 0 if evaluation fails.
4648static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4649 QualType LVType,
4650 LValue &LV,
4651 const Expr *RHS,
4652 bool IncludeMember = true) {
4653 MemberPtr MemPtr;
4654 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
4655 return nullptr;
4656
4657 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
4658 // member value, the behavior is undefined.
4659 if (!MemPtr.getDecl()) {
4660 // FIXME: Specific diagnostic.
4661 Info.FFDiag(RHS);
4662 return nullptr;
4663 }
4664
4665 if (MemPtr.isDerivedMember()) {
4666 // This is a member of some derived class. Truncate LV appropriately.
4667 // The end of the derived-to-base path for the base object must match the
4668 // derived-to-base path for the member pointer.
4669 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
4670 LV.Designator.Entries.size()) {
4671 Info.FFDiag(RHS);
4672 return nullptr;
4673 }
4674 unsigned PathLengthToMember =
4675 LV.Designator.Entries.size() - MemPtr.Path.size();
4676 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
4677 const CXXRecordDecl *LVDecl = getAsBaseClass(
4678 LV.Designator.Entries[PathLengthToMember + I]);
4679 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
4680 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
4681 Info.FFDiag(RHS);
4682 return nullptr;
4683 }
4684 }
4685
4686 // Truncate the lvalue to the appropriate derived class.
4687 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
4688 PathLengthToMember))
4689 return nullptr;
4690 } else if (!MemPtr.Path.empty()) {
4691 // Extend the LValue path with the member pointer's path.
4692 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
4693 MemPtr.Path.size() + IncludeMember);
4694
4695 // Walk down to the appropriate base class.
4696 if (const PointerType *PT = LVType->getAs<PointerType>())
4697 LVType = PT->getPointeeType();
4698 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
4699 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\""
, "clang/lib/AST/ExprConstant.cpp", 4699, __extension__ __PRETTY_FUNCTION__
))
;
4700 // The first class in the path is that of the lvalue.
4701 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
4702 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
4703 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
4704 return nullptr;
4705 RD = Base;
4706 }
4707 // Finally cast to the class containing the member.
4708 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
4709 MemPtr.getContainingRecord()))
4710 return nullptr;
4711 }
4712
4713 // Add the member. Note that we cannot build bound member functions here.
4714 if (IncludeMember) {
4715 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
4716 if (!HandleLValueMember(Info, RHS, LV, FD))
4717 return nullptr;
4718 } else if (const IndirectFieldDecl *IFD =
4719 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
4720 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
4721 return nullptr;
4722 } else {
4723 llvm_unreachable("can't construct reference to bound member function")::llvm::llvm_unreachable_internal("can't construct reference to bound member function"
, "clang/lib/AST/ExprConstant.cpp", 4723)
;
4724 }
4725 }
4726
4727 return MemPtr.getDecl();
4728}
4729
4730static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
4731 const BinaryOperator *BO,
4732 LValue &LV,
4733 bool IncludeMember = true) {
4734 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"
, "clang/lib/AST/ExprConstant.cpp", 4734, __extension__ __PRETTY_FUNCTION__
))
;
4735
4736 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
4737 if (Info.noteFailure()) {
4738 MemberPtr MemPtr;
4739 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
4740 }
4741 return nullptr;
4742 }
4743
4744 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
4745 BO->getRHS(), IncludeMember);
4746}
4747
4748/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
4749/// the provided lvalue, which currently refers to the base object.
4750static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
4751 LValue &Result) {
4752 SubobjectDesignator &D = Result.Designator;
4753 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
4754 return false;
4755
4756 QualType TargetQT = E->getType();
4757 if (const PointerType *PT = TargetQT->getAs<PointerType>())
4758 TargetQT = PT->getPointeeType();
4759
4760 // Check this cast lands within the final derived-to-base subobject path.
4761 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
4762 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4763 << D.MostDerivedType << TargetQT;
4764 return false;
4765 }
4766
4767 // Check the type of the final cast. We don't need to check the path,
4768 // since a cast can only be formed if the path is unique.
4769 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
4770 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
4771 const CXXRecordDecl *FinalType;
4772 if (NewEntriesSize == D.MostDerivedPathLength)
4773 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
4774 else
4775 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
4776 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
4777 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
4778 << D.MostDerivedType << TargetQT;
4779 return false;
4780 }
4781
4782 // Truncate the lvalue to the appropriate derived class.
4783 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
4784}
4785
4786/// Get the value to use for a default-initialized object of type T.
4787/// Return false if it encounters something invalid.
4788static bool getDefaultInitValue(QualType T, APValue &Result) {
4789 bool Success = true;
4790 if (auto *RD = T->getAsCXXRecordDecl()) {
4791 if (RD->isInvalidDecl()) {
4792 Result = APValue();
4793 return false;
4794 }
4795 if (RD->isUnion()) {
4796 Result = APValue((const FieldDecl *)nullptr);
4797 return true;
4798 }
4799 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4800 std::distance(RD->field_begin(), RD->field_end()));
4801
4802 unsigned Index = 0;
4803 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
4804 End = RD->bases_end();
4805 I != End; ++I, ++Index)
4806 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
4807
4808 for (const auto *I : RD->fields()) {
4809 if (I->isUnnamedBitfield())
4810 continue;
4811 Success &= getDefaultInitValue(I->getType(),
4812 Result.getStructField(I->getFieldIndex()));
4813 }
4814 return Success;
4815 }
4816
4817 if (auto *AT =
4818 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
4819 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
4820 if (Result.hasArrayFiller())
4821 Success &=
4822 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
4823
4824 return Success;
4825 }
4826
4827 Result = APValue::IndeterminateValue();
4828 return true;
4829}
4830
4831namespace {
4832enum EvalStmtResult {
4833 /// Evaluation failed.
4834 ESR_Failed,
4835 /// Hit a 'return' statement.
4836 ESR_Returned,
4837 /// Evaluation succeeded.
4838 ESR_Succeeded,
4839 /// Hit a 'continue' statement.
4840 ESR_Continue,
4841 /// Hit a 'break' statement.
4842 ESR_Break,
4843 /// Still scanning for 'case' or 'default' statement.
4844 ESR_CaseNotFound
4845};
4846}
4847
4848static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
4849 if (VD->isInvalidDecl())
4850 return false;
4851 // We don't need to evaluate the initializer for a static local.
4852 if (!VD->hasLocalStorage())
4853 return true;
4854
4855 LValue Result;
4856 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
4857 ScopeKind::Block, Result);
4858
4859 const Expr *InitE = VD->getInit();
4860 if (!InitE) {
4861 if (VD->getType()->isDependentType())
4862 return Info.noteSideEffect();
4863 return getDefaultInitValue(VD->getType(), Val);
4864 }
4865 if (InitE->isValueDependent())
4866 return false;
4867
4868 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
4869 // Wipe out any partially-computed value, to allow tracking that this
4870 // evaluation failed.
4871 Val = APValue();
4872 return false;
4873 }
4874
4875 return true;
4876}
4877
4878static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
4879 bool OK = true;
4880
4881 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
4882 OK &= EvaluateVarDecl(Info, VD);
4883
4884 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
4885 for (auto *BD : DD->bindings())
4886 if (auto *VD = BD->getHoldingVar())
4887 OK &= EvaluateDecl(Info, VD);
4888
4889 return OK;
4890}
4891
4892static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
4893 assert(E->isValueDependent())(static_cast <bool> (E->isValueDependent()) ? void (
0) : __assert_fail ("E->isValueDependent()", "clang/lib/AST/ExprConstant.cpp"
, 4893, __extension__ __PRETTY_FUNCTION__))
;
4894 if (Info.noteSideEffect())
4895 return true;
4896 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.\""
, "clang/lib/AST/ExprConstant.cpp", 4897, __extension__ __PRETTY_FUNCTION__
))
4897 "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.\""
, "clang/lib/AST/ExprConstant.cpp", 4897, __extension__ __PRETTY_FUNCTION__
))
;
4898 return false;
4899}
4900
4901/// Evaluate a condition (either a variable declaration or an expression).
4902static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
4903 const Expr *Cond, bool &Result) {
4904 if (Cond->isValueDependent())
4905 return false;
4906 FullExpressionRAII Scope(Info);
4907 if (CondDecl && !EvaluateDecl(Info, CondDecl))
4908 return false;
4909 if (!EvaluateAsBooleanCondition(Cond, Result, Info))
4910 return false;
4911 return Scope.destroy();
4912}
4913
4914namespace {
4915/// A location where the result (returned value) of evaluating a
4916/// statement should be stored.
4917struct StmtResult {
4918 /// The APValue that should be filled in with the returned value.
4919 APValue &Value;
4920 /// The location containing the result, if any (used to support RVO).
4921 const LValue *Slot;
4922};
4923
4924struct TempVersionRAII {
4925 CallStackFrame &Frame;
4926
4927 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
4928 Frame.pushTempVersion();
4929 }
4930
4931 ~TempVersionRAII() {
4932 Frame.popTempVersion();
4933 }
4934};
4935
4936}
4937
4938static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4939 const Stmt *S,
4940 const SwitchCase *SC = nullptr);
4941
4942/// Evaluate the body of a loop, and translate the result as appropriate.
4943static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
4944 const Stmt *Body,
4945 const SwitchCase *Case = nullptr) {
4946 BlockScopeRAII Scope(Info);
4947
4948 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
4949 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
4950 ESR = ESR_Failed;
4951
4952 switch (ESR) {
4953 case ESR_Break:
4954 return ESR_Succeeded;
4955 case ESR_Succeeded:
4956 case ESR_Continue:
4957 return ESR_Continue;
4958 case ESR_Failed:
4959 case ESR_Returned:
4960 case ESR_CaseNotFound:
4961 return ESR;
4962 }
4963 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "clang/lib/AST/ExprConstant.cpp"
, 4963)
;
4964}
4965
4966/// Evaluate a switch statement.
4967static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
4968 const SwitchStmt *SS) {
4969 BlockScopeRAII Scope(Info);
4970
4971 // Evaluate the switch condition.
4972 APSInt Value;
4973 {
4974 if (const Stmt *Init = SS->getInit()) {
4975 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4976 if (ESR != ESR_Succeeded) {
4977 if (ESR != ESR_Failed && !Scope.destroy())
4978 ESR = ESR_Failed;
4979 return ESR;
4980 }
4981 }
4982
4983 FullExpressionRAII CondScope(Info);
4984 if (SS->getConditionVariable() &&
4985 !EvaluateDecl(Info, SS->getConditionVariable()))
4986 return ESR_Failed;
4987 if (SS->getCond()->isValueDependent()) {
4988 if (!EvaluateDependentExpr(SS->getCond(), Info))
4989 return ESR_Failed;
4990 } else {
4991 if (!EvaluateInteger(SS->getCond(), Value, Info))
4992 return ESR_Failed;
4993 }
4994 if (!CondScope.destroy())
4995 return ESR_Failed;
4996 }
4997
4998 // Find the switch case corresponding to the value of the condition.
4999 // FIXME: Cache this lookup.
5000 const SwitchCase *Found = nullptr;
5001 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
5002 SC = SC->getNextSwitchCase()) {
5003 if (isa<DefaultStmt>(SC)) {
5004 Found = SC;
5005 continue;
5006 }
5007
5008 const CaseStmt *CS = cast<CaseStmt>(SC);
5009 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
5010 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
5011 : LHS;
5012 if (LHS <= Value && Value <= RHS) {
5013 Found = SC;
5014 break;
5015 }
5016 }
5017
5018 if (!Found)
5019 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5020
5021 // Search the switch body for the switch case and evaluate it from there.
5022 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
5023 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5024 return ESR_Failed;
5025
5026 switch (ESR) {
5027 case ESR_Break:
5028 return ESR_Succeeded;
5029 case ESR_Succeeded:
5030 case ESR_Continue:
5031 case ESR_Failed:
5032 case ESR_Returned:
5033 return ESR;
5034 case ESR_CaseNotFound:
5035 // This can only happen if the switch case is nested within a statement
5036 // expression. We have no intention of supporting that.
5037 Info.FFDiag(Found->getBeginLoc(),
5038 diag::note_constexpr_stmt_expr_unsupported);
5039 return ESR_Failed;
5040 }
5041 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "clang/lib/AST/ExprConstant.cpp"
, 5041)
;
5042}
5043
5044static bool CheckLocalVariableDeclaration(EvalInfo &Info, const VarDecl *VD) {
5045 // An expression E is a core constant expression unless the evaluation of E
5046 // would evaluate one of the following: [C++23] - a control flow that passes
5047 // through a declaration of a variable with static or thread storage duration
5048 // unless that variable is usable in constant expressions.
5049 if (VD->isLocalVarDecl() && VD->isStaticLocal() &&
5050 !VD->isUsableInConstantExpressions(Info.Ctx)) {
5051 Info.CCEDiag(VD->getLocation(), diag::note_constexpr_static_local)
5052 << (VD->getTSCSpec() == TSCS_unspecified ? 0 : 1) << VD;
5053 return false;
5054 }
5055 return true;
5056}
5057
5058// Evaluate a statement.
5059static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5060 const Stmt *S, const SwitchCase *Case) {
5061 if (!Info.nextStep(S))
5062 return ESR_Failed;
5063
5064 // If we're hunting down a 'case' or 'default' label, recurse through
5065 // substatements until we hit the label.
5066 if (Case) {
5067 switch (S->getStmtClass()) {
5068 case Stmt::CompoundStmtClass:
5069 // FIXME: Precompute which substatement of a compound statement we
5070 // would jump to, and go straight there rather than performing a
5071 // linear scan each time.
5072 case Stmt::LabelStmtClass:
5073 case Stmt::AttributedStmtClass:
5074 case Stmt::DoStmtClass:
5075 break;
5076
5077 case Stmt::CaseStmtClass:
5078 case Stmt::DefaultStmtClass:
5079 if (Case == S)
5080 Case = nullptr;
5081 break;
5082
5083 case Stmt::IfStmtClass: {
5084 // FIXME: Precompute which side of an 'if' we would jump to, and go
5085 // straight there rather than scanning both sides.
5086 const IfStmt *IS = cast<IfStmt>(S);
5087
5088 // Wrap the evaluation in a block scope, in case it's a DeclStmt
5089 // preceded by our switch label.
5090 BlockScopeRAII Scope(Info);
5091
5092 // Step into the init statement in case it brings an (uninitialized)
5093 // variable into scope.
5094 if (const Stmt *Init = IS->getInit()) {
5095 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5096 if (ESR != ESR_CaseNotFound) {
5097 assert(ESR != ESR_Succeeded)(static_cast <bool> (ESR != ESR_Succeeded) ? void (0) :
__assert_fail ("ESR != ESR_Succeeded", "clang/lib/AST/ExprConstant.cpp"
, 5097, __extension__ __PRETTY_FUNCTION__))
;
5098 return ESR;
5099 }
5100 }
5101
5102 // Condition variable must be initialized if it exists.
5103 // FIXME: We can skip evaluating the body if there's a condition
5104 // variable, as there can't be any case labels within it.
5105 // (The same is true for 'for' statements.)
5106
5107 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
5108 if (ESR == ESR_Failed)
5109 return ESR;
5110 if (ESR != ESR_CaseNotFound)
5111 return Scope.destroy() ? ESR : ESR_Failed;
5112 if (!IS->getElse())
5113 return ESR_CaseNotFound;
5114
5115 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
5116 if (ESR == ESR_Failed)
5117 return ESR;
5118 if (ESR != ESR_CaseNotFound)
5119 return Scope.destroy() ? ESR : ESR_Failed;
5120 return ESR_CaseNotFound;
5121 }
5122
5123 case Stmt::WhileStmtClass: {
5124 EvalStmtResult ESR =
5125 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
5126 if (ESR != ESR_Continue)
5127 return ESR;
5128 break;
5129 }
5130
5131 case Stmt::ForStmtClass: {
5132 const ForStmt *FS = cast<ForStmt>(S);
5133 BlockScopeRAII Scope(Info);
5134
5135 // Step into the init statement in case it brings an (uninitialized)
5136 // variable into scope.
5137 if (const Stmt *Init = FS->getInit()) {
5138 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
5139 if (ESR != ESR_CaseNotFound) {
5140 assert(ESR != ESR_Succeeded)(static_cast <bool> (ESR != ESR_Succeeded) ? void (0) :
__assert_fail ("ESR != ESR_Succeeded", "clang/lib/AST/ExprConstant.cpp"
, 5140, __extension__ __PRETTY_FUNCTION__))
;
5141 return ESR;
5142 }
5143 }
5144
5145 EvalStmtResult ESR =
5146 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
5147 if (ESR != ESR_Continue)
5148 return ESR;
5149 if (const auto *Inc = FS->getInc()) {
5150 if (Inc->isValueDependent()) {
5151 if (!EvaluateDependentExpr(Inc, Info))
5152 return ESR_Failed;
5153 } else {
5154 FullExpressionRAII IncScope(Info);
5155 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5156 return ESR_Failed;
5157 }
5158 }
5159 break;
5160 }
5161
5162 case Stmt::DeclStmtClass: {
5163 // Start the lifetime of any uninitialized variables we encounter. They
5164 // might be used by the selected branch of the switch.
5165 const DeclStmt *DS = cast<DeclStmt>(S);
5166 for (const auto *D : DS->decls()) {
5167 if (const auto *VD = dyn_cast<VarDecl>(D)) {
5168 if (!CheckLocalVariableDeclaration(Info, VD))
5169 return ESR_Failed;
5170 if (VD->hasLocalStorage() && !VD->getInit())
5171 if (!EvaluateVarDecl(Info, VD))
5172 return ESR_Failed;
5173 // FIXME: If the variable has initialization that can't be jumped
5174 // over, bail out of any immediately-surrounding compound-statement
5175 // too. There can't be any case labels here.
5176 }
5177 }
5178 return ESR_CaseNotFound;
5179 }
5180
5181 default:
5182 return ESR_CaseNotFound;
5183 }
5184 }
5185
5186 switch (S->getStmtClass()) {
5187 default:
5188 if (const Expr *E = dyn_cast<Expr>(S)) {
5189 if (E->isValueDependent()) {
5190 if (!EvaluateDependentExpr(E, Info))
5191 return ESR_Failed;
5192 } else {
5193 // Don't bother evaluating beyond an expression-statement which couldn't
5194 // be evaluated.
5195 // FIXME: Do we need the FullExpressionRAII object here?
5196 // VisitExprWithCleanups should create one when necessary.
5197 FullExpressionRAII Scope(Info);
5198 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5199 return ESR_Failed;
5200 }
5201 return ESR_Succeeded;
5202 }
5203
5204 Info.FFDiag(S->getBeginLoc());
5205 return ESR_Failed;
5206
5207 case Stmt::NullStmtClass:
5208 return ESR_Succeeded;
5209
5210 case Stmt::DeclStmtClass: {
5211 const DeclStmt *DS = cast<DeclStmt>(S);
5212 for (const auto *D : DS->decls()) {
5213 const VarDecl *VD = dyn_cast_or_null<VarDecl>(D);
5214 if (VD && !CheckLocalVariableDeclaration(Info, VD))
5215 return ESR_Failed;
5216 // Each declaration initialization is its own full-expression.
5217 FullExpressionRAII Scope(Info);
5218 if (!EvaluateDecl(Info, D) && !Info.noteFailure())
5219 return ESR_Failed;
5220 if (!Scope.destroy())
5221 return ESR_Failed;
5222 }
5223 return ESR_Succeeded;
5224 }
5225
5226 case Stmt::ReturnStmtClass: {
5227 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
5228 FullExpressionRAII Scope(Info);
5229 if (RetExpr && RetExpr->isValueDependent()) {
5230 EvaluateDependentExpr(RetExpr, Info);
5231 // We know we returned, but we don't know what the value is.
5232 return ESR_Failed;
5233 }
5234 if (RetExpr &&
5235 !(Result.Slot
5236 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
5237 : Evaluate(Result.Value, Info, RetExpr)))
5238 return ESR_Failed;
5239 return Scope.destroy() ? ESR_Returned : ESR_Failed;
5240 }
5241
5242 case Stmt::CompoundStmtClass: {
5243 BlockScopeRAII Scope(Info);
5244
5245 const CompoundStmt *CS = cast<CompoundStmt>(S);
5246 for (const auto *BI : CS->body()) {
5247 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
5248 if (ESR == ESR_Succeeded)
5249 Case = nullptr;
5250 else if (ESR != ESR_CaseNotFound) {
5251 if (ESR != ESR_Failed && !Scope.destroy())
5252 return ESR_Failed;
5253 return ESR;
5254 }
5255 }
5256 if (Case)
5257 return ESR_CaseNotFound;
5258 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5259 }
5260
5261 case Stmt::IfStmtClass: {
5262 const IfStmt *IS = cast<IfStmt>(S);
5263
5264 // Evaluate the condition, as either a var decl or as an expression.
5265 BlockScopeRAII Scope(Info);
5266 if (const Stmt *Init = IS->getInit()) {
5267 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
5268 if (ESR != ESR_Succeeded) {
5269 if (ESR != ESR_Failed && !Scope.destroy())
5270 return ESR_Failed;
5271 return ESR;
5272 }
5273 }
5274 bool Cond;
5275 if (IS->isConsteval()) {
5276 Cond = IS->isNonNegatedConsteval();
5277 // If we are not in a constant context, if consteval should not evaluate
5278 // to true.
5279 if (!Info.InConstantContext)
5280 Cond = !Cond;
5281 } else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
5282 Cond))
5283 return ESR_Failed;
5284
5285 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5286 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
5287 if (ESR != ESR_Succeeded) {
5288 if (ESR != ESR_Failed && !Scope.destroy())
5289 return ESR_Failed;
5290 return ESR;
5291 }
5292 }
5293 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5294 }
5295
5296 case Stmt::WhileStmtClass: {
5297 const WhileStmt *WS = cast<WhileStmt>(S);
5298 while (true) {
5299 BlockScopeRAII Scope(Info);
5300 bool Continue;
5301 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
5302 Continue))
5303 return ESR_Failed;
5304 if (!Continue)
5305 break;
5306
5307 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
5308 if (ESR != ESR_Continue) {
5309 if (ESR != ESR_Failed && !Scope.destroy())
5310 return ESR_Failed;
5311 return ESR;
5312 }
5313 if (!Scope.destroy())
5314 return ESR_Failed;
5315 }
5316 return ESR_Succeeded;
5317 }
5318
5319 case Stmt::DoStmtClass: {
5320 const DoStmt *DS = cast<DoStmt>(S);
5321 bool Continue;
5322 do {
5323 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
5324 if (ESR != ESR_Continue)
5325 return ESR;
5326 Case = nullptr;
5327
5328 if (DS->getCond()->isValueDependent()) {
5329 EvaluateDependentExpr(DS->getCond(), Info);
5330 // Bailout as we don't know whether to keep going or terminate the loop.
5331 return ESR_Failed;
5332 }
5333 FullExpressionRAII CondScope(Info);
5334 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
5335 !CondScope.destroy())
5336 return ESR_Failed;
5337 } while (Continue);
5338 return ESR_Succeeded;
5339 }
5340
5341 case Stmt::ForStmtClass: {
5342 const ForStmt *FS = cast<ForStmt>(S);
5343 BlockScopeRAII ForScope(Info);
5344 if (FS->getInit()) {
5345 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5346 if (ESR != ESR_Succeeded) {
5347 if (ESR != ESR_Failed && !ForScope.destroy())
5348 return ESR_Failed;
5349 return ESR;
5350 }
5351 }
5352 while (true) {
5353 BlockScopeRAII IterScope(Info);
5354 bool Continue = true;
5355 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
5356 FS->getCond(), Continue))
5357 return ESR_Failed;
5358 if (!Continue)
5359 break;
5360
5361 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5362 if (ESR != ESR_Continue) {
5363 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5364 return ESR_Failed;
5365 return ESR;
5366 }
5367
5368 if (const auto *Inc = FS->getInc()) {
5369 if (Inc->isValueDependent()) {
5370 if (!EvaluateDependentExpr(Inc, Info))
5371 return ESR_Failed;
5372 } else {
5373 FullExpressionRAII IncScope(Info);
5374 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
5375 return ESR_Failed;
5376 }
5377 }
5378
5379 if (!IterScope.destroy())
5380 return ESR_Failed;
5381 }
5382 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5383 }
5384
5385 case Stmt::CXXForRangeStmtClass: {
5386 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
5387 BlockScopeRAII Scope(Info);
5388
5389 // Evaluate the init-statement if present.
5390 if (FS->getInit()) {
5391 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
5392 if (ESR != ESR_Succeeded) {
5393 if (ESR != ESR_Failed && !Scope.destroy())
5394 return ESR_Failed;
5395 return ESR;
5396 }
5397 }
5398
5399 // Initialize the __range variable.
5400 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
5401 if (ESR != ESR_Succeeded) {
5402 if (ESR != ESR_Failed && !Scope.destroy())
5403 return ESR_Failed;
5404 return ESR;
5405 }
5406
5407 // In error-recovery cases it's possible to get here even if we failed to
5408 // synthesize the __begin and __end variables.
5409 if (!FS->getBeginStmt() || !FS->getEndStmt() || !FS->getCond())
5410 return ESR_Failed;
5411
5412 // Create the __begin and __end iterators.
5413 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
5414 if (ESR != ESR_Succeeded) {
5415 if (ESR != ESR_Failed && !Scope.destroy())
5416 return ESR_Failed;
5417 return ESR;
5418 }
5419 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
5420 if (ESR != ESR_Succeeded) {
5421 if (ESR != ESR_Failed && !Scope.destroy())
5422 return ESR_Failed;
5423 return ESR;
5424 }
5425
5426 while (true) {
5427 // Condition: __begin != __end.
5428 {
5429 if (FS->getCond()->isValueDependent()) {
5430 EvaluateDependentExpr(FS->getCond(), Info);
5431 // We don't know whether to keep going or terminate the loop.
5432 return ESR_Failed;
5433 }
5434 bool Continue = true;
5435 FullExpressionRAII CondExpr(Info);
5436 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
5437 return ESR_Failed;
5438 if (!Continue)
5439 break;
5440 }
5441
5442 // User's variable declaration, initialized by *__begin.
5443 BlockScopeRAII InnerScope(Info);
5444 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
5445 if (ESR != ESR_Succeeded) {
5446 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5447 return ESR_Failed;
5448 return ESR;
5449 }
5450
5451 // Loop body.
5452 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
5453 if (ESR != ESR_Continue) {
5454 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5455 return ESR_Failed;
5456 return ESR;
5457 }
5458 if (FS->getInc()->isValueDependent()) {
5459 if (!EvaluateDependentExpr(FS->getInc(), Info))
5460 return ESR_Failed;
5461 } else {
5462 // Increment: ++__begin
5463 if (!EvaluateIgnoredValue(Info, FS->getInc()))
5464 return ESR_Failed;
5465 }
5466
5467 if (!InnerScope.destroy())
5468 return ESR_Failed;
5469 }
5470
5471 return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5472 }
5473
5474 case Stmt::SwitchStmtClass:
5475 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
5476
5477 case Stmt::ContinueStmtClass:
5478 return ESR_Continue;
5479
5480 case Stmt::BreakStmtClass:
5481 return ESR_Break;
5482
5483 case Stmt::LabelStmtClass:
5484 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
5485
5486 case Stmt::AttributedStmtClass:
5487 // As a general principle, C++11 attributes can be ignored without
5488 // any semantic impact.
5489 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
5490 Case);
5491
5492 case Stmt::CaseStmtClass:
5493 case Stmt::DefaultStmtClass:
5494 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
5495 case Stmt::CXXTryStmtClass:
5496 // Evaluate try blocks by evaluating all sub statements.
5497 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
5498 }
5499}
5500
5501/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5502/// default constructor. If so, we'll fold it whether or not it's marked as
5503/// constexpr. If it is marked as constexpr, we will never implicitly define it,
5504/// so we need special handling.
5505static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5506 const CXXConstructorDecl *CD,
5507 bool IsValueInitialization) {
5508 if (!CD->isTrivial() || !CD->isDefaultConstructor())
5509 return false;
5510
5511 // Value-initialization does not call a trivial default constructor, so such a
5512 // call is a core constant expression whether or not the constructor is
5513 // constexpr.
5514 if (!CD->isConstexpr() && !IsValueInitialization) {
5515 if (Info.getLangOpts().CPlusPlus11) {
5516 // FIXME: If DiagDecl is an implicitly-declared special member function,
5517 // we should be much more explicit about why it's not constexpr.
5518 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5519 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5520 Info.Note(CD->getLocation(), diag::note_declared_at);
5521 } else {
5522 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5523 }
5524 }
5525 return true;
5526}
5527
5528/// CheckConstexprFunction - Check that a function can be called in a constant
5529/// expression.
5530static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5531 const FunctionDecl *Declaration,
5532 const FunctionDecl *Definition,
5533 const Stmt *Body) {
5534 // Potential constant expressions can contain calls to declared, but not yet
5535 // defined, constexpr functions.
5536 if (Info.checkingPotentialConstantExpression() && !Definition &&
5537 Declaration->isConstexpr())
5538 return false;
5539
5540 // Bail out if the function declaration itself is invalid. We will
5541 // have produced a relevant diagnostic while parsing it, so just
5542 // note the problematic sub-expression.
5543 if (Declaration->isInvalidDecl()) {
5544 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5545 return false;
5546 }
5547
5548 // DR1872: An instantiated virtual constexpr function can't be called in a
5549 // constant expression (prior to C++20). We can still constant-fold such a
5550 // call.
5551 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5552 cast<CXXMethodDecl>(Declaration)->isVirtual())
5553 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5554
5555 if (Definition && Definition->isInvalidDecl()) {
5556 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5557 return false;
5558 }
5559
5560 // Can we evaluate this function call?
5561 if (Definition && Definition->isConstexpr() && Body)
5562 return true;
5563
5564 if (Info.getLangOpts().CPlusPlus11) {
5565 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
5566
5567 // If this function is not constexpr because it is an inherited
5568 // non-constexpr constructor, diagnose that directly.
5569 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
5570 if (CD && CD->isInheritingConstructor()) {
5571 auto *Inherited = CD->getInheritedConstructor().getConstructor();
5572 if (!Inherited->isConstexpr())
5573 DiagDecl = CD = Inherited;
5574 }
5575
5576 // FIXME: If DiagDecl is an implicitly-declared special member function
5577 // or an inheriting constructor, we should be much more explicit about why
5578 // it's not constexpr.
5579 if (CD && CD->isInheritingConstructor())
5580 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
5581 << CD->getInheritedConstructor().getConstructor()->getParent();
5582 else
5583 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
5584 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
5585 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
5586 } else {
5587 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5588 }
5589 return false;
5590}
5591
5592namespace {
5593struct CheckDynamicTypeHandler {
5594 AccessKinds AccessKind;
5595 typedef bool result_type;
5596 bool failed() { return false; }
5597 bool found(APValue &Subobj, QualType SubobjType) { return true; }
5598 bool found(APSInt &Value, QualType SubobjType) { return true; }
5599 bool found(APFloat &Value, QualType SubobjType) { return true; }
5600};
5601} // end anonymous namespace
5602
5603/// Check that we can access the notional vptr of an object / determine its
5604/// dynamic type.
5605static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
5606 AccessKinds AK, bool Polymorphic) {
5607 if (This.Designator.Invalid)
5608 return false;
5609
5610 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
5611
5612 if (!Obj)
5613 return false;
5614
5615 if (!Obj.Value) {
5616 // The object is not usable in constant expressions, so we can't inspect
5617 // its value to see if it's in-lifetime or what the active union members
5618 // are. We can still check for a one-past-the-end lvalue.
5619 if (This.Designator.isOnePastTheEnd() ||
5620 This.Designator.isMostDerivedAnUnsizedArray()) {
5621 Info.FFDiag(E, This.Designator.isOnePastTheEnd()
5622 ? diag::note_constexpr_access_past_end
5623 : diag::note_constexpr_access_unsized_array)
5624 << AK;
5625 return false;
5626 } else if (Polymorphic) {
5627 // Conservatively refuse to perform a polymorphic operation if we would
5628 // not be able to read a notional 'vptr' value.
5629 APValue Val;
5630 This.moveInto(Val);
5631 QualType StarThisType =
5632 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
5633 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
5634 << AK << Val.getAsString(Info.Ctx, StarThisType);
5635 return false;
5636 }
5637 return true;
5638 }
5639
5640 CheckDynamicTypeHandler Handler{AK};
5641 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
5642}
5643
5644/// Check that the pointee of the 'this' pointer in a member function call is
5645/// either within its lifetime or in its period of construction or destruction.
5646static bool
5647checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
5648 const LValue &This,
5649 const CXXMethodDecl *NamedMember) {
5650 return checkDynamicType(
5651 Info, E, This,
5652 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
5653}
5654
5655struct DynamicType {
5656 /// The dynamic class type of the object.
5657 const CXXRecordDecl *Type;
5658 /// The corresponding path length in the lvalue.
5659 unsigned PathLength;
5660};
5661
5662static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
5663 unsigned PathLength) {
5664 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\""
, "clang/lib/AST/ExprConstant.cpp", 5665, __extension__ __PRETTY_FUNCTION__
))
5665 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\""
, "clang/lib/AST/ExprConstant.cpp", 5665, __extension__ __PRETTY_FUNCTION__
))
;
5666 return (PathLength == Designator.MostDerivedPathLength)
5667 ? Designator.MostDerivedType->getAsCXXRecordDecl()
5668 : getAsBaseClass(Designator.Entries[PathLength - 1]);
5669}
5670
5671/// Determine the dynamic type of an object.
5672static std::optional<DynamicType> ComputeDynamicType(EvalInfo &Info,
5673 const Expr *E,
5674 LValue &This,
5675 AccessKinds AK) {
5676 // If we don't have an lvalue denoting an object of class type, there is no
5677 // meaningful dynamic type. (We consider objects of non-class type to have no
5678 // dynamic type.)
5679 if (!checkDynamicType(Info, E, This, AK, true))
5680 return std::nullopt;
5681
5682 // Refuse to compute a dynamic type in the presence of virtual bases. This
5683 // shouldn't happen other than in constant-folding situations, since literal
5684 // types can't have virtual bases.
5685 //
5686 // Note that consumers of DynamicType assume that the type has no virtual
5687 // bases, and will need modifications if this restriction is relaxed.
5688 const CXXRecordDecl *Class =
5689 This.Designator.MostDerivedType->getAsCXXRecordDecl();
5690 if (!Class || Class->getNumVBases()) {
5691 Info.FFDiag(E);
5692 return std::nullopt;
5693 }
5694
5695 // FIXME: For very deep class hierarchies, it might be beneficial to use a
5696 // binary search here instead. But the overwhelmingly common case is that
5697 // we're not in the middle of a constructor, so it probably doesn't matter
5698 // in practice.
5699 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
5700 for (unsigned PathLength = This.Designator.MostDerivedPathLength;
5701 PathLength <= Path.size(); ++PathLength) {
5702 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
5703 Path.slice(0, PathLength))) {
5704 case ConstructionPhase::Bases:
5705 case ConstructionPhase::DestroyingBases:
5706 // We're constructing or destroying a base class. This is not the dynamic
5707 // type.
5708 break;
5709
5710 case ConstructionPhase::None:
5711 case ConstructionPhase::AfterBases:
5712 case ConstructionPhase::AfterFields:
5713 case ConstructionPhase::Destroying:
5714 // We've finished constructing the base classes and not yet started
5715 // destroying them again, so this is the dynamic type.
5716 return DynamicType{getBaseClassType(This.Designator, PathLength),
5717 PathLength};
5718 }
5719 }
5720
5721 // CWG issue 1517: we're constructing a base class of the object described by
5722 // 'This', so that object has not yet begun its period of construction and
5723 // any polymorphic operation on it results in undefined behavior.
5724 Info.FFDiag(E);
5725 return std::nullopt;
5726}
5727
5728/// Perform virtual dispatch.
5729static const CXXMethodDecl *HandleVirtualDispatch(
5730 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
5731 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
5732 std::optional<DynamicType> DynType = ComputeDynamicType(
5733 Info, E, This,
5734 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
5735 if (!DynType)
5736 return nullptr;
5737
5738 // Find the final overrider. It must be declared in one of the classes on the
5739 // path from the dynamic type to the static type.
5740 // FIXME: If we ever allow literal types to have virtual base classes, that
5741 // won't be true.
5742 const CXXMethodDecl *Callee = Found;
5743 unsigned PathLength = DynType->PathLength;
5744 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
5745 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
5746 const CXXMethodDecl *Overrider =
5747 Found->getCorrespondingMethodDeclaredInClass(Class, false);
5748 if (Overrider) {
5749 Callee = Overrider;
5750 break;
5751 }
5752 }
5753
5754 // C++2a [class.abstract]p6:
5755 // the effect of making a virtual call to a pure virtual function [...] is
5756 // undefined
5757 if (Callee->isPure()) {
5758 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
5759 Info.Note(Callee->getLocation(), diag::note_declared_at);
5760 return nullptr;
5761 }
5762
5763 // If necessary, walk the rest of the path to determine the sequence of
5764 // covariant adjustment steps to apply.
5765 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
5766 Found->getReturnType())) {
5767 CovariantAdjustmentPath.push_back(Callee->getReturnType());
5768 for (unsigned CovariantPathLength = PathLength + 1;
5769 CovariantPathLength != This.Designator.Entries.size();
5770 ++CovariantPathLength) {
5771 const CXXRecordDecl *NextClass =
5772 getBaseClassType(This.Designator, CovariantPathLength);
5773 const CXXMethodDecl *Next =
5774 Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
5775 if (Next && !Info.Ctx.hasSameUnqualifiedType(
5776 Next->getReturnType(), CovariantAdjustmentPath.back()))
5777 CovariantAdjustmentPath.push_back(Next->getReturnType());
5778 }
5779 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
5780 CovariantAdjustmentPath.back()))
5781 CovariantAdjustmentPath.push_back(Found->getReturnType());
5782 }
5783
5784 // Perform 'this' adjustment.
5785 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
5786 return nullptr;
5787
5788 return Callee;
5789}
5790
5791/// Perform the adjustment from a value returned by a virtual function to
5792/// a value of the statically expected type, which may be a pointer or
5793/// reference to a base class of the returned type.
5794static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
5795 APValue &Result,
5796 ArrayRef<QualType> Path) {
5797 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\""
, "clang/lib/AST/ExprConstant.cpp", 5798, __extension__ __PRETTY_FUNCTION__
))
5798 "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\""
, "clang/lib/AST/ExprConstant.cpp", 5798, __extension__ __PRETTY_FUNCTION__
))
;
5799 if (Result.isNullPointer())
5800 return true;
5801
5802 LValue LVal;
5803 LVal.setFrom(Info.Ctx, Result);
5804
5805 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
5806 for (unsigned I = 1; I != Path.size(); ++I) {
5807 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
5808 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\""
, "clang/lib/AST/ExprConstant.cpp", 5808, __extension__ __PRETTY_FUNCTION__
))
;
5809 if (OldClass != NewClass &&
5810 !CastToBaseClass(Info, E, LVal, OldClass, NewClass))
5811 return false;
5812 OldClass = NewClass;
5813 }
5814
5815 LVal.moveInto(Result);
5816 return true;
5817}
5818
5819/// Determine whether \p Base, which is known to be a direct base class of
5820/// \p Derived, is a public base class.
5821static bool isBaseClassPublic(const CXXRecordDecl *Derived,
5822 const CXXRecordDecl *Base) {
5823 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
5824 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
5825 if (BaseClass && declaresSameEntity(BaseClass, Base))
5826 return BaseSpec.getAccessSpecifier() == AS_public;
5827 }
5828 llvm_unreachable("Base is not a direct base of Derived")::llvm::llvm_unreachable_internal("Base is not a direct base of Derived"
, "clang/lib/AST/ExprConstant.cpp", 5828)
;
5829}
5830
5831/// Apply the given dynamic cast operation on the provided lvalue.
5832///
5833/// This implements the hard case of dynamic_cast, requiring a "runtime check"
5834/// to find a suitable target subobject.
5835static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
5836 LValue &Ptr) {
5837 // We can't do anything with a non-symbolic pointer value.
5838 SubobjectDesignator &D = Ptr.Designator;
5839 if (D.Invalid)
5840 return false;
5841
5842 // C++ [expr.dynamic.cast]p6:
5843 // If v is a null pointer value, the result is a null pointer value.
5844 if (Ptr.isNullPointer() && !E->isGLValue())
5845 return true;
5846
5847 // For all the other cases, we need the pointer to point to an object within
5848 // its lifetime / period of construction / destruction, and we need to know
5849 // its dynamic type.
5850 std::optional<DynamicType> DynType =
5851 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
5852 if (!DynType)
5853 return false;
5854
5855 // C++ [expr.dynamic.cast]p7:
5856 // If T is "pointer to cv void", then the result is a pointer to the most
5857 // derived object
5858 if (E->getType()->isVoidPointerType())
5859 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
5860
5861 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
5862 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\""
, "clang/lib/AST/ExprConstant.cpp", 5862, __extension__ __PRETTY_FUNCTION__
))
;
5863 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
5864
5865 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
5866 // C++ [expr.dynamic.cast]p9:
5867 if (!E->isGLValue()) {
5868 // The value of a failed cast to pointer type is the null pointer value
5869 // of the required result type.
5870 Ptr.setNull(Info.Ctx, E->getType());
5871 return true;
5872 }
5873
5874 // A failed cast to reference type throws [...] std::bad_cast.
5875