Bug Summary

File:tools/clang/lib/AST/ExprConstant.cpp
Warning:line 5405, column 32
Access to field 'Index' results in a dereference of a null pointer (loaded from field 'CurrentCall')

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ExprConstant.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-8/lib/clang/8.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn350071/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn350071/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-8~svn350071=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-12-27-042839-1215-1 -x c++ /build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp -faddrsig
1//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the Expr constant evaluator.
11//
12// Constant expression evaluation produces four main results:
13//
14// * A success/failure flag indicating whether constant folding was successful.
15// This is the 'bool' return value used by most of the code in this file. A
16// 'false' return value indicates that constant folding has failed, and any
17// appropriate diagnostic has already been produced.
18//
19// * An evaluated result, valid only if constant folding has not failed.
20//
21// * A flag indicating if evaluation encountered (unevaluated) side-effects.
22// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
23// where it is possible to determine the evaluated result regardless.
24//
25// * A set of notes indicating why the evaluation was not a constant expression
26// (under the C++11 / C++1y rules only, at the moment), or, if folding failed
27// too, why the expression could not be folded.
28//
29// If we are checking for a potential constant expression, failure to constant
30// fold a potential constant sub-expression will be indicated by a 'false'
31// return value (the expression could not be folded) and no diagnostic (the
32// expression is not necessarily non-constant).
33//
34//===----------------------------------------------------------------------===//
35
36#include "clang/AST/APValue.h"
37#include "clang/AST/ASTContext.h"
38#include "clang/AST/ASTDiagnostic.h"
39#include "clang/AST/ASTLambda.h"
40#include "clang/AST/CharUnits.h"
41#include "clang/AST/Expr.h"
42#include "clang/AST/OSLog.h"
43#include "clang/AST/RecordLayout.h"
44#include "clang/AST/StmtVisitor.h"
45#include "clang/AST/TypeLoc.h"
46#include "clang/Basic/Builtins.h"
47#include "clang/Basic/TargetInfo.h"
48#include "llvm/Support/SaveAndRestore.h"
49#include "llvm/Support/raw_ostream.h"
50#include <cstring>
51#include <functional>
52
53#define DEBUG_TYPE"exprconstant" "exprconstant"
54
55using namespace clang;
56using llvm::APSInt;
57using llvm::APFloat;
58
59static bool IsGlobalLValue(APValue::LValueBase B);
60
61namespace {
62 struct LValue;
63 struct CallStackFrame;
64 struct EvalInfo;
65
66 static QualType getType(APValue::LValueBase B) {
67 if (!B) return QualType();
68 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
69 // FIXME: It's unclear where we're supposed to take the type from, and
70 // this actually matters for arrays of unknown bound. Eg:
71 //
72 // extern int arr[]; void f() { extern int arr[3]; };
73 // constexpr int *p = &arr[1]; // valid?
74 //
75 // For now, we take the array bound from the most recent declaration.
76 for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl;
77 Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) {
78 QualType T = Redecl->getType();
79 if (!T->isIncompleteArrayType())
80 return T;
81 }
82 return D->getType();
83 }
84
85 const Expr *Base = B.get<const Expr*>();
86
87 // For a materialized temporary, the type of the temporary we materialized
88 // may not be the type of the expression.
89 if (const MaterializeTemporaryExpr *MTE =
90 dyn_cast<MaterializeTemporaryExpr>(Base)) {
91 SmallVector<const Expr *, 2> CommaLHSs;
92 SmallVector<SubobjectAdjustment, 2> Adjustments;
93 const Expr *Temp = MTE->GetTemporaryExpr();
94 const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
95 Adjustments);
96 // Keep any cv-qualifiers from the reference if we generated a temporary
97 // for it directly. Otherwise use the type after adjustment.
98 if (!Adjustments.empty())
99 return Inner->getType();
100 }
101
102 return Base->getType();
103 }
104
105 /// Get an LValue path entry, which is known to not be an array index, as a
106 /// field or base class.
107 static
108 APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) {
109 APValue::BaseOrMemberType Value;
110 Value.setFromOpaqueValue(E.BaseOrMember);
111 return Value;
112 }
113
114 /// Get an LValue path entry, which is known to not be an array index, as a
115 /// field declaration.
116 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
117 return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer());
118 }
119 /// Get an LValue path entry, which is known to not be an array index, as a
120 /// base class declaration.
121 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
122 return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer());
123 }
124 /// Determine whether this LValue path entry for a base class names a virtual
125 /// base class.
126 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
127 return getAsBaseOrMember(E).getInt();
128 }
129
130 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
131 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
132 const FunctionDecl *Callee = CE->getDirectCallee();
133 return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr;
134 }
135
136 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
137 /// This will look through a single cast.
138 ///
139 /// Returns null if we couldn't unwrap a function with alloc_size.
140 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
141 if (!E->getType()->isPointerType())
142 return nullptr;
143
144 E = E->IgnoreParens();
145 // If we're doing a variable assignment from e.g. malloc(N), there will
146 // probably be a cast of some kind. In exotic cases, we might also see a
147 // top-level ExprWithCleanups. Ignore them either way.
148 if (const auto *FE = dyn_cast<FullExpr>(E))
149 E = FE->getSubExpr()->IgnoreParens();
150
151 if (const auto *Cast = dyn_cast<CastExpr>(E))
152 E = Cast->getSubExpr()->IgnoreParens();
153
154 if (const auto *CE = dyn_cast<CallExpr>(E))
155 return getAllocSizeAttr(CE) ? CE : nullptr;
156 return nullptr;
157 }
158
159 /// Determines whether or not the given Base contains a call to a function
160 /// with the alloc_size attribute.
161 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
162 const auto *E = Base.dyn_cast<const Expr *>();
163 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
164 }
165
166 /// The bound to claim that an array of unknown bound has.
167 /// The value in MostDerivedArraySize is undefined in this case. So, set it
168 /// to an arbitrary value that's likely to loudly break things if it's used.
169 static const uint64_t AssumedSizeForUnsizedArray =
170 std::numeric_limits<uint64_t>::max() / 2;
171
172 /// Determines if an LValue with the given LValueBase will have an unsized
173 /// array in its designator.
174 /// Find the path length and type of the most-derived subobject in the given
175 /// path, and find the size of the containing array, if any.
176 static unsigned
177 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
178 ArrayRef<APValue::LValuePathEntry> Path,
179 uint64_t &ArraySize, QualType &Type, bool &IsArray,
180 bool &FirstEntryIsUnsizedArray) {
181 // This only accepts LValueBases from APValues, and APValues don't support
182 // arrays that lack size info.
183 assert(!isBaseAnAllocSizeCall(Base) &&((!isBaseAnAllocSizeCall(Base) && "Unsized arrays shouldn't appear here"
) ? static_cast<void> (0) : __assert_fail ("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 184, __PRETTY_FUNCTION__))
184 "Unsized arrays shouldn't appear here")((!isBaseAnAllocSizeCall(Base) && "Unsized arrays shouldn't appear here"
) ? static_cast<void> (0) : __assert_fail ("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 184, __PRETTY_FUNCTION__))
;
185 unsigned MostDerivedLength = 0;
186 Type = getType(Base);
187
188 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
189 if (Type->isArrayType()) {
190 const ArrayType *AT = Ctx.getAsArrayType(Type);
191 Type = AT->getElementType();
192 MostDerivedLength = I + 1;
193 IsArray = true;
194
195 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
196 ArraySize = CAT->getSize().getZExtValue();
197 } else {
198 assert(I == 0 && "unexpected unsized array designator")((I == 0 && "unexpected unsized array designator") ? static_cast
<void> (0) : __assert_fail ("I == 0 && \"unexpected unsized array designator\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 198, __PRETTY_FUNCTION__))
;
199 FirstEntryIsUnsizedArray = true;
200 ArraySize = AssumedSizeForUnsizedArray;
201 }
202 } else if (Type->isAnyComplexType()) {
203 const ComplexType *CT = Type->castAs<ComplexType>();
204 Type = CT->getElementType();
205 ArraySize = 2;
206 MostDerivedLength = I + 1;
207 IsArray = true;
208 } else if (const FieldDecl *FD = getAsField(Path[I])) {
209 Type = FD->getType();
210 ArraySize = 0;
211 MostDerivedLength = I + 1;
212 IsArray = false;
213 } else {
214 // Path[I] describes a base class.
215 ArraySize = 0;
216 IsArray = false;
217 }
218 }
219 return MostDerivedLength;
220 }
221
222 // The order of this enum is important for diagnostics.
223 enum CheckSubobjectKind {
224 CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex,
225 CSK_This, CSK_Real, CSK_Imag
226 };
227
228 /// A path from a glvalue to a subobject of that glvalue.
229 struct SubobjectDesignator {
230 /// True if the subobject was named in a manner not supported by C++11. Such
231 /// lvalues can still be folded, but they are not core constant expressions
232 /// and we cannot perform lvalue-to-rvalue conversions on them.
233 unsigned Invalid : 1;
234
235 /// Is this a pointer one past the end of an object?
236 unsigned IsOnePastTheEnd : 1;
237
238 /// Indicator of whether the first entry is an unsized array.
239 unsigned FirstEntryIsAnUnsizedArray : 1;
240
241 /// Indicator of whether the most-derived object is an array element.
242 unsigned MostDerivedIsArrayElement : 1;
243
244 /// The length of the path to the most-derived object of which this is a
245 /// subobject.
246 unsigned MostDerivedPathLength : 28;
247
248 /// The size of the array of which the most-derived object is an element.
249 /// This will always be 0 if the most-derived object is not an array
250 /// element. 0 is not an indicator of whether or not the most-derived object
251 /// is an array, however, because 0-length arrays are allowed.
252 ///
253 /// If the current array is an unsized array, the value of this is
254 /// undefined.
255 uint64_t MostDerivedArraySize;
256
257 /// The type of the most derived object referred to by this address.
258 QualType MostDerivedType;
259
260 typedef APValue::LValuePathEntry PathEntry;
261
262 /// The entries on the path from the glvalue to the designated subobject.
263 SmallVector<PathEntry, 8> Entries;
264
265 SubobjectDesignator() : Invalid(true) {}
266
267 explicit SubobjectDesignator(QualType T)
268 : Invalid(false), IsOnePastTheEnd(false),
269 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
270 MostDerivedPathLength(0), MostDerivedArraySize(0),
271 MostDerivedType(T) {}
272
273 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
274 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
275 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
276 MostDerivedPathLength(0), MostDerivedArraySize(0) {
277 assert(V.isLValue() && "Non-LValue used to make an LValue designator?")((V.isLValue() && "Non-LValue used to make an LValue designator?"
) ? static_cast<void> (0) : __assert_fail ("V.isLValue() && \"Non-LValue used to make an LValue designator?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 277, __PRETTY_FUNCTION__))
;
278 if (!Invalid) {
279 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
280 ArrayRef<PathEntry> VEntries = V.getLValuePath();
281 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
282 if (V.getLValueBase()) {
283 bool IsArray = false;
284 bool FirstIsUnsizedArray = false;
285 MostDerivedPathLength = findMostDerivedSubobject(
286 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
287 MostDerivedType, IsArray, FirstIsUnsizedArray);
288 MostDerivedIsArrayElement = IsArray;
289 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
290 }
291 }
292 }
293
294 void setInvalid() {
295 Invalid = true;
296 Entries.clear();
297 }
298
299 /// Determine whether the most derived subobject is an array without a
300 /// known bound.
301 bool isMostDerivedAnUnsizedArray() const {
302 assert(!Invalid && "Calling this makes no sense on invalid designators")((!Invalid && "Calling this makes no sense on invalid designators"
) ? static_cast<void> (0) : __assert_fail ("!Invalid && \"Calling this makes no sense on invalid designators\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 302, __PRETTY_FUNCTION__))
;
303 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
304 }
305
306 /// Determine what the most derived array's size is. Results in an assertion
307 /// failure if the most derived array lacks a size.
308 uint64_t getMostDerivedArraySize() const {
309 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size")((!isMostDerivedAnUnsizedArray() && "Unsized array has no size"
) ? static_cast<void> (0) : __assert_fail ("!isMostDerivedAnUnsizedArray() && \"Unsized array has no size\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 309, __PRETTY_FUNCTION__))
;
310 return MostDerivedArraySize;
311 }
312
313 /// Determine whether this is a one-past-the-end pointer.
314 bool isOnePastTheEnd() const {
315 assert(!Invalid)((!Invalid) ? static_cast<void> (0) : __assert_fail ("!Invalid"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 315, __PRETTY_FUNCTION__))
;
316 if (IsOnePastTheEnd)
317 return true;
318 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
319 Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize)
320 return true;
321 return false;
322 }
323
324 /// Get the range of valid index adjustments in the form
325 /// {maximum value that can be subtracted from this pointer,
326 /// maximum value that can be added to this pointer}
327 std::pair<uint64_t, uint64_t> validIndexAdjustments() {
328 if (Invalid || isMostDerivedAnUnsizedArray())
329 return {0, 0};
330
331 // [expr.add]p4: For the purposes of these operators, a pointer to a
332 // nonarray object behaves the same as a pointer to the first element of
333 // an array of length one with the type of the object as its element type.
334 bool IsArray = MostDerivedPathLength == Entries.size() &&
335 MostDerivedIsArrayElement;
336 uint64_t ArrayIndex =
337 IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
338 uint64_t ArraySize =
339 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
340 return {ArrayIndex, ArraySize - ArrayIndex};
341 }
342
343 /// Check that this refers to a valid subobject.
344 bool isValidSubobject() const {
345 if (Invalid)
346 return false;
347 return !isOnePastTheEnd();
348 }
349 /// Check that this refers to a valid subobject, and if not, produce a
350 /// relevant diagnostic and set the designator as invalid.
351 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
352
353 /// Get the type of the designated object.
354 QualType getType(ASTContext &Ctx) const {
355 assert(!Invalid && "invalid designator has no subobject type")((!Invalid && "invalid designator has no subobject type"
) ? static_cast<void> (0) : __assert_fail ("!Invalid && \"invalid designator has no subobject type\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 355, __PRETTY_FUNCTION__))
;
356 return MostDerivedPathLength == Entries.size()
357 ? MostDerivedType
358 : Ctx.getRecordType(getAsBaseClass(Entries.back()));
359 }
360
361 /// Update this designator to refer to the first element within this array.
362 void addArrayUnchecked(const ConstantArrayType *CAT) {
363 PathEntry Entry;
364 Entry.ArrayIndex = 0;
365 Entries.push_back(Entry);
366
367 // This is a most-derived object.
368 MostDerivedType = CAT->getElementType();
369 MostDerivedIsArrayElement = true;
370 MostDerivedArraySize = CAT->getSize().getZExtValue();
371 MostDerivedPathLength = Entries.size();
372 }
373 /// Update this designator to refer to the first element within the array of
374 /// elements of type T. This is an array of unknown size.
375 void addUnsizedArrayUnchecked(QualType ElemTy) {
376 PathEntry Entry;
377 Entry.ArrayIndex = 0;
378 Entries.push_back(Entry);
379
380 MostDerivedType = ElemTy;
381 MostDerivedIsArrayElement = true;
382 // The value in MostDerivedArraySize is undefined in this case. So, set it
383 // to an arbitrary value that's likely to loudly break things if it's
384 // used.
385 MostDerivedArraySize = AssumedSizeForUnsizedArray;
386 MostDerivedPathLength = Entries.size();
387 }
388 /// Update this designator to refer to the given base or member of this
389 /// object.
390 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
391 PathEntry Entry;
392 APValue::BaseOrMemberType Value(D, Virtual);
393 Entry.BaseOrMember = Value.getOpaqueValue();
394 Entries.push_back(Entry);
395
396 // If this isn't a base class, it's a new most-derived object.
397 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
398 MostDerivedType = FD->getType();
399 MostDerivedIsArrayElement = false;
400 MostDerivedArraySize = 0;
401 MostDerivedPathLength = Entries.size();
402 }
403 }
404 /// Update this designator to refer to the given complex component.
405 void addComplexUnchecked(QualType EltTy, bool Imag) {
406 PathEntry Entry;
407 Entry.ArrayIndex = Imag;
408 Entries.push_back(Entry);
409
410 // This is technically a most-derived object, though in practice this
411 // is unlikely to matter.
412 MostDerivedType = EltTy;
413 MostDerivedIsArrayElement = true;
414 MostDerivedArraySize = 2;
415 MostDerivedPathLength = Entries.size();
416 }
417 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
418 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
419 const APSInt &N);
420 /// Add N to the address of this subobject.
421 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
422 if (Invalid || !N) return;
423 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
424 if (isMostDerivedAnUnsizedArray()) {
425 diagnoseUnsizedArrayPointerArithmetic(Info, E);
426 // Can't verify -- trust that the user is doing the right thing (or if
427 // not, trust that the caller will catch the bad behavior).
428 // FIXME: Should we reject if this overflows, at least?
429 Entries.back().ArrayIndex += TruncatedN;
430 return;
431 }
432
433 // [expr.add]p4: For the purposes of these operators, a pointer to a
434 // nonarray object behaves the same as a pointer to the first element of
435 // an array of length one with the type of the object as its element type.
436 bool IsArray = MostDerivedPathLength == Entries.size() &&
437 MostDerivedIsArrayElement;
438 uint64_t ArrayIndex =
439 IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
440 uint64_t ArraySize =
441 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
442
443 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
444 // Calculate the actual index in a wide enough type, so we can include
445 // it in the note.
446 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
447 (llvm::APInt&)N += ArrayIndex;
448 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index")((N.ugt(ArraySize) && "bounds check failed for in-bounds index"
) ? static_cast<void> (0) : __assert_fail ("N.ugt(ArraySize) && \"bounds check failed for in-bounds index\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 448, __PRETTY_FUNCTION__))
;
449 diagnosePointerArithmetic(Info, E, N);
450 setInvalid();
451 return;
452 }
453
454 ArrayIndex += TruncatedN;
455 assert(ArrayIndex <= ArraySize &&((ArrayIndex <= ArraySize && "bounds check succeeded for out-of-bounds index"
) ? static_cast<void> (0) : __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 456, __PRETTY_FUNCTION__))
456 "bounds check succeeded for out-of-bounds index")((ArrayIndex <= ArraySize && "bounds check succeeded for out-of-bounds index"
) ? static_cast<void> (0) : __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 456, __PRETTY_FUNCTION__))
;
457
458 if (IsArray)
459 Entries.back().ArrayIndex = ArrayIndex;
460 else
461 IsOnePastTheEnd = (ArrayIndex != 0);
462 }
463 };
464
465 /// A stack frame in the constexpr call stack.
466 struct CallStackFrame {
467 EvalInfo &Info;
468
469 /// Parent - The caller of this stack frame.
470 CallStackFrame *Caller;
471
472 /// Callee - The function which was called.
473 const FunctionDecl *Callee;
474
475 /// This - The binding for the this pointer in this call, if any.
476 const LValue *This;
477
478 /// Arguments - Parameter bindings for this function call, indexed by
479 /// parameters' function scope indices.
480 APValue *Arguments;
481
482 // Note that we intentionally use std::map here so that references to
483 // values are stable.
484 typedef std::pair<const void *, unsigned> MapKeyTy;
485 typedef std::map<MapKeyTy, APValue> MapTy;
486 /// Temporaries - Temporary lvalues materialized within this stack frame.
487 MapTy Temporaries;
488
489 /// CallLoc - The location of the call expression for this call.
490 SourceLocation CallLoc;
491
492 /// Index - The call index of this call.
493 unsigned Index;
494
495 /// The stack of integers for tracking version numbers for temporaries.
496 SmallVector<unsigned, 2> TempVersionStack = {1};
497 unsigned CurTempVersion = TempVersionStack.back();
498
499 unsigned getTempVersion() const { return TempVersionStack.back(); }
500
501 void pushTempVersion() {
502 TempVersionStack.push_back(++CurTempVersion);
503 }
504
505 void popTempVersion() {
506 TempVersionStack.pop_back();
507 }
508
509 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
510 // on the overall stack usage of deeply-recursing constexpr evaluations.
511 // (We should cache this map rather than recomputing it repeatedly.)
512 // But let's try this and see how it goes; we can look into caching the map
513 // as a later change.
514
515 /// LambdaCaptureFields - Mapping from captured variables/this to
516 /// corresponding data members in the closure class.
517 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
518 FieldDecl *LambdaThisCaptureField;
519
520 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
521 const FunctionDecl *Callee, const LValue *This,
522 APValue *Arguments);
523 ~CallStackFrame();
524
525 // Return the temporary for Key whose version number is Version.
526 APValue *getTemporary(const void *Key, unsigned Version) {
527 MapKeyTy KV(Key, Version);
528 auto LB = Temporaries.lower_bound(KV);
529 if (LB != Temporaries.end() && LB->first == KV)
530 return &LB->second;
531 // Pair (Key,Version) wasn't found in the map. Check that no elements
532 // in the map have 'Key' as their key.
533 assert((LB == Temporaries.end() || LB->first.first != Key) &&(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 535, __PRETTY_FUNCTION__))
534 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 535, __PRETTY_FUNCTION__))
535 "Element with key 'Key' found in map")(((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first !=
Key) && "Element with key 'Key' found in map") ? static_cast
<void> (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 535, __PRETTY_FUNCTION__))
;
536 return nullptr;
537 }
538
539 // Return the current temporary for Key in the map.
540 APValue *getCurrentTemporary(const void *Key) {
541 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
542 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
543 return &std::prev(UB)->second;
544 return nullptr;
545 }
546
547 // Return the version number of the current temporary for Key.
548 unsigned getCurrentTemporaryVersion(const void *Key) const {
549 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
550 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
551 return std::prev(UB)->first.second;
552 return 0;
553 }
554
555 APValue &createTemporary(const void *Key, bool IsLifetimeExtended);
556 };
557
558 /// Temporarily override 'this'.
559 class ThisOverrideRAII {
560 public:
561 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
562 : Frame(Frame), OldThis(Frame.This) {
563 if (Enable)
564 Frame.This = NewThis;
565 }
566 ~ThisOverrideRAII() {
567 Frame.This = OldThis;
568 }
569 private:
570 CallStackFrame &Frame;
571 const LValue *OldThis;
572 };
573
574 /// A partial diagnostic which we might know in advance that we are not going
575 /// to emit.
576 class OptionalDiagnostic {
577 PartialDiagnostic *Diag;
578
579 public:
580 explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr)
581 : Diag(Diag) {}
582
583 template<typename T>
584 OptionalDiagnostic &operator<<(const T &v) {
585 if (Diag)
586 *Diag << v;
587 return *this;
588 }
589
590 OptionalDiagnostic &operator<<(const APSInt &I) {
591 if (Diag) {
592 SmallVector<char, 32> Buffer;
593 I.toString(Buffer);
594 *Diag << StringRef(Buffer.data(), Buffer.size());
595 }
596 return *this;
597 }
598
599 OptionalDiagnostic &operator<<(const APFloat &F) {
600 if (Diag) {
601 // FIXME: Force the precision of the source value down so we don't
602 // print digits which are usually useless (we don't really care here if
603 // we truncate a digit by accident in edge cases). Ideally,
604 // APFloat::toString would automatically print the shortest
605 // representation which rounds to the correct value, but it's a bit
606 // tricky to implement.
607 unsigned precision =
608 llvm::APFloat::semanticsPrecision(F.getSemantics());
609 precision = (precision * 59 + 195) / 196;
610 SmallVector<char, 32> Buffer;
611 F.toString(Buffer, precision);
612 *Diag << StringRef(Buffer.data(), Buffer.size());
613 }
614 return *this;
615 }
616 };
617
618 /// A cleanup, and a flag indicating whether it is lifetime-extended.
619 class Cleanup {
620 llvm::PointerIntPair<APValue*, 1, bool> Value;
621
622 public:
623 Cleanup(APValue *Val, bool IsLifetimeExtended)
624 : Value(Val, IsLifetimeExtended) {}
625
626 bool isLifetimeExtended() const { return Value.getInt(); }
627 void endLifetime() {
628 *Value.getPointer() = APValue();
629 }
630 };
631
632 /// EvalInfo - This is a private struct used by the evaluator to capture
633 /// information about a subexpression as it is folded. It retains information
634 /// about the AST context, but also maintains information about the folded
635 /// expression.
636 ///
637 /// If an expression could be evaluated, it is still possible it is not a C
638 /// "integer constant expression" or constant expression. If not, this struct
639 /// captures information about how and why not.
640 ///
641 /// One bit of information passed *into* the request for constant folding
642 /// indicates whether the subexpression is "evaluated" or not according to C
643 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
644 /// evaluate the expression regardless of what the RHS is, but C only allows
645 /// certain things in certain situations.
646 struct EvalInfo {
647 ASTContext &Ctx;
648
649 /// EvalStatus - Contains information about the evaluation.
650 Expr::EvalStatus &EvalStatus;
651
652 /// CurrentCall - The top of the constexpr call stack.
653 CallStackFrame *CurrentCall;
654
655 /// CallStackDepth - The number of calls in the call stack right now.
656 unsigned CallStackDepth;
657
658 /// NextCallIndex - The next call index to assign.
659 unsigned NextCallIndex;
660
661 /// StepsLeft - The remaining number of evaluation steps we're permitted
662 /// to perform. This is essentially a limit for the number of statements
663 /// we will evaluate.
664 unsigned StepsLeft;
665
666 /// BottomFrame - The frame in which evaluation started. This must be
667 /// initialized after CurrentCall and CallStackDepth.
668 CallStackFrame BottomFrame;
669
670 /// A stack of values whose lifetimes end at the end of some surrounding
671 /// evaluation frame.
672 llvm::SmallVector<Cleanup, 16> CleanupStack;
673
674 /// EvaluatingDecl - This is the declaration whose initializer is being
675 /// evaluated, if any.
676 APValue::LValueBase EvaluatingDecl;
677
678 /// EvaluatingDeclValue - This is the value being constructed for the
679 /// declaration whose initializer is being evaluated, if any.
680 APValue *EvaluatingDeclValue;
681
682 /// EvaluatingObject - Pair of the AST node that an lvalue represents and
683 /// the call index that that lvalue was allocated in.
684 typedef std::pair<APValue::LValueBase, std::pair<unsigned, unsigned>>
685 EvaluatingObject;
686
687 /// EvaluatingConstructors - Set of objects that are currently being
688 /// constructed.
689 llvm::DenseSet<EvaluatingObject> EvaluatingConstructors;
690
691 struct EvaluatingConstructorRAII {
692 EvalInfo &EI;
693 EvaluatingObject Object;
694 bool DidInsert;
695 EvaluatingConstructorRAII(EvalInfo &EI, EvaluatingObject Object)
696 : EI(EI), Object(Object) {
697 DidInsert = EI.EvaluatingConstructors.insert(Object).second;
698 }
699 ~EvaluatingConstructorRAII() {
700 if (DidInsert) EI.EvaluatingConstructors.erase(Object);
701 }
702 };
703
704 bool isEvaluatingConstructor(APValue::LValueBase Decl, unsigned CallIndex,
705 unsigned Version) {
706 return EvaluatingConstructors.count(
707 EvaluatingObject(Decl, {CallIndex, Version}));
708 }
709
710 /// The current array initialization index, if we're performing array
711 /// initialization.
712 uint64_t ArrayInitIndex = -1;
713
714 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
715 /// notes attached to it will also be stored, otherwise they will not be.
716 bool HasActiveDiagnostic;
717
718 /// Have we emitted a diagnostic explaining why we couldn't constant
719 /// fold (not just why it's not strictly a constant expression)?
720 bool HasFoldFailureDiagnostic;
721
722 /// Whether or not we're currently speculatively evaluating.
723 bool IsSpeculativelyEvaluating;
724
725 /// Whether or not we're in a context where the front end requires a
726 /// constant value.
727 bool InConstantContext;
728
729 enum EvaluationMode {
730 /// Evaluate as a constant expression. Stop if we find that the expression
731 /// is not a constant expression.
732 EM_ConstantExpression,
733
734 /// Evaluate as a potential constant expression. Keep going if we hit a
735 /// construct that we can't evaluate yet (because we don't yet know the
736 /// value of something) but stop if we hit something that could never be
737 /// a constant expression.
738 EM_PotentialConstantExpression,
739
740 /// Fold the expression to a constant. Stop if we hit a side-effect that
741 /// we can't model.
742 EM_ConstantFold,
743
744 /// Evaluate the expression looking for integer overflow and similar
745 /// issues. Don't worry about side-effects, and try to visit all
746 /// subexpressions.
747 EM_EvaluateForOverflow,
748
749 /// Evaluate in any way we know how. Don't worry about side-effects that
750 /// can't be modeled.
751 EM_IgnoreSideEffects,
752
753 /// Evaluate as a constant expression. Stop if we find that the expression
754 /// is not a constant expression. Some expressions can be retried in the
755 /// optimizer if we don't constant fold them here, but in an unevaluated
756 /// context we try to fold them immediately since the optimizer never
757 /// gets a chance to look at it.
758 EM_ConstantExpressionUnevaluated,
759
760 /// Evaluate as a potential constant expression. Keep going if we hit a
761 /// construct that we can't evaluate yet (because we don't yet know the
762 /// value of something) but stop if we hit something that could never be
763 /// a constant expression. Some expressions can be retried in the
764 /// optimizer if we don't constant fold them here, but in an unevaluated
765 /// context we try to fold them immediately since the optimizer never
766 /// gets a chance to look at it.
767 EM_PotentialConstantExpressionUnevaluated,
768 } EvalMode;
769
770 /// Are we checking whether the expression is a potential constant
771 /// expression?
772 bool checkingPotentialConstantExpression() const {
773 return EvalMode == EM_PotentialConstantExpression ||
774 EvalMode == EM_PotentialConstantExpressionUnevaluated;
775 }
776
777 /// Are we checking an expression for overflow?
778 // FIXME: We should check for any kind of undefined or suspicious behavior
779 // in such constructs, not just overflow.
780 bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; }
781
782 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
783 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
784 CallStackDepth(0), NextCallIndex(1),
785 StepsLeft(getLangOpts().ConstexprStepLimit),
786 BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr),
787 EvaluatingDecl((const ValueDecl *)nullptr),
788 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
789 HasFoldFailureDiagnostic(false), IsSpeculativelyEvaluating(false),
790 InConstantContext(false), EvalMode(Mode) {}
791
792 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
793 EvaluatingDecl = Base;
794 EvaluatingDeclValue = &Value;
795 EvaluatingConstructors.insert({Base, {0, 0}});
796 }
797
798 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
799
800 bool CheckCallLimit(SourceLocation Loc) {
801 // Don't perform any constexpr calls (other than the call we're checking)
802 // when checking a potential constant expression.
803 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
804 return false;
805 if (NextCallIndex == 0) {
806 // NextCallIndex has wrapped around.
807 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
808 return false;
809 }
810 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
811 return true;
812 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
813 << getLangOpts().ConstexprCallDepth;
814 return false;
815 }
816
817 CallStackFrame *getCallFrame(unsigned CallIndex) {
818 assert(CallIndex && "no call index in getCallFrame")((CallIndex && "no call index in getCallFrame") ? static_cast
<void> (0) : __assert_fail ("CallIndex && \"no call index in getCallFrame\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 818, __PRETTY_FUNCTION__))
;
819 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
820 // be null in this loop.
821 CallStackFrame *Frame = CurrentCall;
822 while (Frame->Index > CallIndex)
823 Frame = Frame->Caller;
824 return (Frame->Index == CallIndex) ? Frame : nullptr;
825 }
826
827 bool nextStep(const Stmt *S) {
828 if (!StepsLeft) {
829 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
830 return false;
831 }
832 --StepsLeft;
833 return true;
834 }
835
836 private:
837 /// Add a diagnostic to the diagnostics list.
838 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) {
839 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator());
840 EvalStatus.Diag->push_back(std::make_pair(Loc, PD));
841 return EvalStatus.Diag->back().second;
842 }
843
844 /// Add notes containing a call stack to the current point of evaluation.
845 void addCallStack(unsigned Limit);
846
847 private:
848 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId,
849 unsigned ExtraNotes, bool IsCCEDiag) {
850
851 if (EvalStatus.Diag) {
852 // If we have a prior diagnostic, it will be noting that the expression
853 // isn't a constant expression. This diagnostic is more important,
854 // unless we require this evaluation to produce a constant expression.
855 //
856 // FIXME: We might want to show both diagnostics to the user in
857 // EM_ConstantFold mode.
858 if (!EvalStatus.Diag->empty()) {
859 switch (EvalMode) {
860 case EM_ConstantFold:
861 case EM_IgnoreSideEffects:
862 case EM_EvaluateForOverflow:
863 if (!HasFoldFailureDiagnostic)
864 break;
865 // We've already failed to fold something. Keep that diagnostic.
866 LLVM_FALLTHROUGH[[clang::fallthrough]];
867 case EM_ConstantExpression:
868 case EM_PotentialConstantExpression:
869 case EM_ConstantExpressionUnevaluated:
870 case EM_PotentialConstantExpressionUnevaluated:
871 HasActiveDiagnostic = false;
872 return OptionalDiagnostic();
873 }
874 }
875
876 unsigned CallStackNotes = CallStackDepth - 1;
877 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit();
878 if (Limit)
879 CallStackNotes = std::min(CallStackNotes, Limit + 1);
880 if (checkingPotentialConstantExpression())
881 CallStackNotes = 0;
882
883 HasActiveDiagnostic = true;
884 HasFoldFailureDiagnostic = !IsCCEDiag;
885 EvalStatus.Diag->clear();
886 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes);
887 addDiag(Loc, DiagId);
888 if (!checkingPotentialConstantExpression())
889 addCallStack(Limit);
890 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second);
891 }
892 HasActiveDiagnostic = false;
893 return OptionalDiagnostic();
894 }
895 public:
896 // Diagnose that the evaluation could not be folded (FF => FoldFailure)
897 OptionalDiagnostic
898 FFDiag(SourceLocation Loc,
899 diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
900 unsigned ExtraNotes = 0) {
901 return Diag(Loc, DiagId, ExtraNotes, false);
902 }
903
904 OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId
905 = diag::note_invalid_subexpr_in_const_expr,
906 unsigned ExtraNotes = 0) {
907 if (EvalStatus.Diag)
908 return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false);
909 HasActiveDiagnostic = false;
910 return OptionalDiagnostic();
911 }
912
913 /// Diagnose that the evaluation does not produce a C++11 core constant
914 /// expression.
915 ///
916 /// FIXME: Stop evaluating if we're in EM_ConstantExpression or
917 /// EM_PotentialConstantExpression mode and we produce one of these.
918 OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId
919 = diag::note_invalid_subexpr_in_const_expr,
920 unsigned ExtraNotes = 0) {
921 // Don't override a previous diagnostic. Don't bother collecting
922 // diagnostics if we're evaluating for overflow.
923 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) {
924 HasActiveDiagnostic = false;
925 return OptionalDiagnostic();
926 }
927 return Diag(Loc, DiagId, ExtraNotes, true);
928 }
929 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId
930 = diag::note_invalid_subexpr_in_const_expr,
931 unsigned ExtraNotes = 0) {
932 return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes);
933 }
934 /// Add a note to a prior diagnostic.
935 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) {
936 if (!HasActiveDiagnostic)
937 return OptionalDiagnostic();
938 return OptionalDiagnostic(&addDiag(Loc, DiagId));
939 }
940
941 /// Add a stack of notes to a prior diagnostic.
942 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) {
943 if (HasActiveDiagnostic) {
944 EvalStatus.Diag->insert(EvalStatus.Diag->end(),
945 Diags.begin(), Diags.end());
946 }
947 }
948
949 /// Should we continue evaluation after encountering a side-effect that we
950 /// couldn't model?
951 bool keepEvaluatingAfterSideEffect() {
952 switch (EvalMode) {
953 case EM_PotentialConstantExpression:
954 case EM_PotentialConstantExpressionUnevaluated:
955 case EM_EvaluateForOverflow:
956 case EM_IgnoreSideEffects:
957 return true;
958
959 case EM_ConstantExpression:
960 case EM_ConstantExpressionUnevaluated:
961 case EM_ConstantFold:
962 return false;
963 }
964 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 964)
;
965 }
966
967 /// Note that we have had a side-effect, and determine whether we should
968 /// keep evaluating.
969 bool noteSideEffect() {
970 EvalStatus.HasSideEffects = true;
971 return keepEvaluatingAfterSideEffect();
972 }
973
974 /// Should we continue evaluation after encountering undefined behavior?
975 bool keepEvaluatingAfterUndefinedBehavior() {
976 switch (EvalMode) {
977 case EM_EvaluateForOverflow:
978 case EM_IgnoreSideEffects:
979 case EM_ConstantFold:
980 return true;
981
982 case EM_PotentialConstantExpression:
983 case EM_PotentialConstantExpressionUnevaluated:
984 case EM_ConstantExpression:
985 case EM_ConstantExpressionUnevaluated:
986 return false;
987 }
988 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 988)
;
989 }
990
991 /// Note that we hit something that was technically undefined behavior, but
992 /// that we can evaluate past it (such as signed overflow or floating-point
993 /// division by zero.)
994 bool noteUndefinedBehavior() {
995 EvalStatus.HasUndefinedBehavior = true;
996 return keepEvaluatingAfterUndefinedBehavior();
997 }
998
999 /// Should we continue evaluation as much as possible after encountering a
1000 /// construct which can't be reduced to a value?
1001 bool keepEvaluatingAfterFailure() {
1002 if (!StepsLeft)
1003 return false;
1004
1005 switch (EvalMode) {
1006 case EM_PotentialConstantExpression:
1007 case EM_PotentialConstantExpressionUnevaluated:
1008 case EM_EvaluateForOverflow:
1009 return true;
1010
1011 case EM_ConstantExpression:
1012 case EM_ConstantExpressionUnevaluated:
1013 case EM_ConstantFold:
1014 case EM_IgnoreSideEffects:
1015 return false;
1016 }
1017 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1017)
;
1018 }
1019
1020 /// Notes that we failed to evaluate an expression that other expressions
1021 /// directly depend on, and determine if we should keep evaluating. This
1022 /// should only be called if we actually intend to keep evaluating.
1023 ///
1024 /// Call noteSideEffect() instead if we may be able to ignore the value that
1025 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1026 ///
1027 /// (Foo(), 1) // use noteSideEffect
1028 /// (Foo() || true) // use noteSideEffect
1029 /// Foo() + 1 // use noteFailure
1030 LLVM_NODISCARD[[clang::warn_unused_result]] bool noteFailure() {
1031 // Failure when evaluating some expression often means there is some
1032 // subexpression whose evaluation was skipped. Therefore, (because we
1033 // don't track whether we skipped an expression when unwinding after an
1034 // evaluation failure) every evaluation failure that bubbles up from a
1035 // subexpression implies that a side-effect has potentially happened. We
1036 // skip setting the HasSideEffects flag to true until we decide to
1037 // continue evaluating after that point, which happens here.
1038 bool KeepGoing = keepEvaluatingAfterFailure();
1039 EvalStatus.HasSideEffects |= KeepGoing;
1040 return KeepGoing;
1041 }
1042
1043 class ArrayInitLoopIndex {
1044 EvalInfo &Info;
1045 uint64_t OuterIndex;
1046
1047 public:
1048 ArrayInitLoopIndex(EvalInfo &Info)
1049 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1050 Info.ArrayInitIndex = 0;
1051 }
1052 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1053
1054 operator uint64_t&() { return Info.ArrayInitIndex; }
1055 };
1056 };
1057
1058 /// Object used to treat all foldable expressions as constant expressions.
1059 struct FoldConstant {
1060 EvalInfo &Info;
1061 bool Enabled;
1062 bool HadNoPriorDiags;
1063 EvalInfo::EvaluationMode OldMode;
1064
1065 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1066 : Info(Info),
1067 Enabled(Enabled),
1068 HadNoPriorDiags(Info.EvalStatus.Diag &&
1069 Info.EvalStatus.Diag->empty() &&
1070 !Info.EvalStatus.HasSideEffects),
1071 OldMode(Info.EvalMode) {
1072 if (Enabled &&
1073 (Info.EvalMode == EvalInfo::EM_ConstantExpression ||
1074 Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated))
1075 Info.EvalMode = EvalInfo::EM_ConstantFold;
1076 }
1077 void keepDiagnostics() { Enabled = false; }
1078 ~FoldConstant() {
1079 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1080 !Info.EvalStatus.HasSideEffects)
1081 Info.EvalStatus.Diag->clear();
1082 Info.EvalMode = OldMode;
1083 }
1084 };
1085
1086 /// RAII object used to set the current evaluation mode to ignore
1087 /// side-effects.
1088 struct IgnoreSideEffectsRAII {
1089 EvalInfo &Info;
1090 EvalInfo::EvaluationMode OldMode;
1091 explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1092 : Info(Info), OldMode(Info.EvalMode) {
1093 if (!Info.checkingPotentialConstantExpression())
1094 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1095 }
1096
1097 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1098 };
1099
1100 /// RAII object used to optionally suppress diagnostics and side-effects from
1101 /// a speculative evaluation.
1102 class SpeculativeEvaluationRAII {
1103 EvalInfo *Info = nullptr;
1104 Expr::EvalStatus OldStatus;
1105 bool OldIsSpeculativelyEvaluating;
1106
1107 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1108 Info = Other.Info;
1109 OldStatus = Other.OldStatus;
1110 OldIsSpeculativelyEvaluating = Other.OldIsSpeculativelyEvaluating;
1111 Other.Info = nullptr;
1112 }
1113
1114 void maybeRestoreState() {
1115 if (!Info)
1116 return;
1117
1118 Info->EvalStatus = OldStatus;
1119 Info->IsSpeculativelyEvaluating = OldIsSpeculativelyEvaluating;
1120 }
1121
1122 public:
1123 SpeculativeEvaluationRAII() = default;
1124
1125 SpeculativeEvaluationRAII(
1126 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1127 : Info(&Info), OldStatus(Info.EvalStatus),
1128 OldIsSpeculativelyEvaluating(Info.IsSpeculativelyEvaluating) {
1129 Info.EvalStatus.Diag = NewDiag;
1130 Info.IsSpeculativelyEvaluating = true;
1131 }
1132
1133 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1134 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1135 moveFromAndCancel(std::move(Other));
1136 }
1137
1138 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1139 maybeRestoreState();
1140 moveFromAndCancel(std::move(Other));
1141 return *this;
1142 }
1143
1144 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1145 };
1146
1147 /// RAII object wrapping a full-expression or block scope, and handling
1148 /// the ending of the lifetime of temporaries created within it.
1149 template<bool IsFullExpression>
1150 class ScopeRAII {
1151 EvalInfo &Info;
1152 unsigned OldStackSize;
1153 public:
1154 ScopeRAII(EvalInfo &Info)
1155 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1156 // Push a new temporary version. This is needed to distinguish between
1157 // temporaries created in different iterations of a loop.
1158 Info.CurrentCall->pushTempVersion();
1159 }
1160 ~ScopeRAII() {
1161 // Body moved to a static method to encourage the compiler to inline away
1162 // instances of this class.
1163 cleanup(Info, OldStackSize);
1164 Info.CurrentCall->popTempVersion();
1165 }
1166 private:
1167 static void cleanup(EvalInfo &Info, unsigned OldStackSize) {
1168 unsigned NewEnd = OldStackSize;
1169 for (unsigned I = OldStackSize, N = Info.CleanupStack.size();
1170 I != N; ++I) {
1171 if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) {
1172 // Full-expression cleanup of a lifetime-extended temporary: nothing
1173 // to do, just move this cleanup to the right place in the stack.
1174 std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]);
1175 ++NewEnd;
1176 } else {
1177 // End the lifetime of the object.
1178 Info.CleanupStack[I].endLifetime();
1179 }
1180 }
1181 Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd,
1182 Info.CleanupStack.end());
1183 }
1184 };
1185 typedef ScopeRAII<false> BlockScopeRAII;
1186 typedef ScopeRAII<true> FullExpressionRAII;
1187}
1188
1189bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1190 CheckSubobjectKind CSK) {
1191 if (Invalid)
1192 return false;
1193 if (isOnePastTheEnd()) {
1194 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1195 << CSK;
1196 setInvalid();
1197 return false;
1198 }
1199 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1200 // must actually be at least one array element; even a VLA cannot have a
1201 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1202 return true;
1203}
1204
1205void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1206 const Expr *E) {
1207 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1208 // Do not set the designator as invalid: we can represent this situation,
1209 // and correct handling of __builtin_object_size requires us to do so.
1210}
1211
1212void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1213 const Expr *E,
1214 const APSInt &N) {
1215 // If we're complaining, we must be able to statically determine the size of
1216 // the most derived array.
1217 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1218 Info.CCEDiag(E, diag::note_constexpr_array_index)
1219 << N << /*array*/ 0
1220 << static_cast<unsigned>(getMostDerivedArraySize());
1221 else
1222 Info.CCEDiag(E, diag::note_constexpr_array_index)
1223 << N << /*non-array*/ 1;
1224 setInvalid();
1225}
1226
1227CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1228 const FunctionDecl *Callee, const LValue *This,
1229 APValue *Arguments)
1230 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1231 Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1232 Info.CurrentCall = this;
1233 ++Info.CallStackDepth;
1234}
1235
1236CallStackFrame::~CallStackFrame() {
1237 assert(Info.CurrentCall == this && "calls retired out of order")((Info.CurrentCall == this && "calls retired out of order"
) ? static_cast<void> (0) : __assert_fail ("Info.CurrentCall == this && \"calls retired out of order\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1237, __PRETTY_FUNCTION__))
;
1238 --Info.CallStackDepth;
1239 Info.CurrentCall = Caller;
1240}
1241
1242APValue &CallStackFrame::createTemporary(const void *Key,
1243 bool IsLifetimeExtended) {
1244 unsigned Version = Info.CurrentCall->getTempVersion();
1245 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1246 assert(Result.isUninit() && "temporary created multiple times")((Result.isUninit() && "temporary created multiple times"
) ? static_cast<void> (0) : __assert_fail ("Result.isUninit() && \"temporary created multiple times\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1246, __PRETTY_FUNCTION__))
;
1247 Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended));
1248 return Result;
1249}
1250
1251static void describeCall(CallStackFrame *Frame, raw_ostream &Out);
1252
1253void EvalInfo::addCallStack(unsigned Limit) {
1254 // Determine which calls to skip, if any.
1255 unsigned ActiveCalls = CallStackDepth - 1;
1256 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart;
1257 if (Limit && Limit < ActiveCalls) {
1258 SkipStart = Limit / 2 + Limit % 2;
1259 SkipEnd = ActiveCalls - Limit / 2;
1260 }
1261
1262 // Walk the call stack and add the diagnostics.
1263 unsigned CallIdx = 0;
1264 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame;
1265 Frame = Frame->Caller, ++CallIdx) {
1266 // Skip this call?
1267 if (CallIdx >= SkipStart && CallIdx < SkipEnd) {
1268 if (CallIdx == SkipStart) {
1269 // Note that we're skipping calls.
1270 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed)
1271 << unsigned(ActiveCalls - Limit);
1272 }
1273 continue;
1274 }
1275
1276 // Use a different note for an inheriting constructor, because from the
1277 // user's perspective it's not really a function at all.
1278 if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) {
1279 if (CD->isInheritingConstructor()) {
1280 addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here)
1281 << CD->getParent();
1282 continue;
1283 }
1284 }
1285
1286 SmallVector<char, 128> Buffer;
1287 llvm::raw_svector_ostream Out(Buffer);
1288 describeCall(Frame, Out);
1289 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str();
1290 }
1291}
1292
1293/// Kinds of access we can perform on an object, for diagnostics.
1294enum AccessKinds {
1295 AK_Read,
1296 AK_Assign,
1297 AK_Increment,
1298 AK_Decrement
1299};
1300
1301namespace {
1302 struct ComplexValue {
1303 private:
1304 bool IsInt;
1305
1306 public:
1307 APSInt IntReal, IntImag;
1308 APFloat FloatReal, FloatImag;
1309
1310 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1311
1312 void makeComplexFloat() { IsInt = false; }
1313 bool isComplexFloat() const { return !IsInt; }
1314 APFloat &getComplexFloatReal() { return FloatReal; }
1315 APFloat &getComplexFloatImag() { return FloatImag; }
1316
1317 void makeComplexInt() { IsInt = true; }
1318 bool isComplexInt() const { return IsInt; }
1319 APSInt &getComplexIntReal() { return IntReal; }
1320 APSInt &getComplexIntImag() { return IntImag; }
1321
1322 void moveInto(APValue &v) const {
1323 if (isComplexFloat())
1324 v = APValue(FloatReal, FloatImag);
1325 else
1326 v = APValue(IntReal, IntImag);
1327 }
1328 void setFrom(const APValue &v) {
1329 assert(v.isComplexFloat() || v.isComplexInt())((v.isComplexFloat() || v.isComplexInt()) ? static_cast<void
> (0) : __assert_fail ("v.isComplexFloat() || v.isComplexInt()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1329, __PRETTY_FUNCTION__))
;
1330 if (v.isComplexFloat()) {
1331 makeComplexFloat();
1332 FloatReal = v.getComplexFloatReal();
1333 FloatImag = v.getComplexFloatImag();
1334 } else {
1335 makeComplexInt();
1336 IntReal = v.getComplexIntReal();
1337 IntImag = v.getComplexIntImag();
1338 }
1339 }
1340 };
1341
1342 struct LValue {
1343 APValue::LValueBase Base;
1344 CharUnits Offset;
1345 SubobjectDesignator Designator;
1346 bool IsNullPtr : 1;
1347 bool InvalidBase : 1;
1348
1349 const APValue::LValueBase getLValueBase() const { return Base; }
1350 CharUnits &getLValueOffset() { return Offset; }
1351 const CharUnits &getLValueOffset() const { return Offset; }
1352 SubobjectDesignator &getLValueDesignator() { return Designator; }
1353 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1354 bool isNullPointer() const { return IsNullPtr;}
1355
1356 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1357 unsigned getLValueVersion() const { return Base.getVersion(); }
1358
1359 void moveInto(APValue &V) const {
1360 if (Designator.Invalid)
1361 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1362 else {
1363 assert(!InvalidBase && "APValues can't handle invalid LValue bases")((!InvalidBase && "APValues can't handle invalid LValue bases"
) ? static_cast<void> (0) : __assert_fail ("!InvalidBase && \"APValues can't handle invalid LValue bases\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1363, __PRETTY_FUNCTION__))
;
1364 V = APValue(Base, Offset, Designator.Entries,
1365 Designator.IsOnePastTheEnd, IsNullPtr);
1366 }
1367 }
1368 void setFrom(ASTContext &Ctx, const APValue &V) {
1369 assert(V.isLValue() && "Setting LValue from a non-LValue?")((V.isLValue() && "Setting LValue from a non-LValue?"
) ? static_cast<void> (0) : __assert_fail ("V.isLValue() && \"Setting LValue from a non-LValue?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1369, __PRETTY_FUNCTION__))
;
1370 Base = V.getLValueBase();
1371 Offset = V.getLValueOffset();
1372 InvalidBase = false;
1373 Designator = SubobjectDesignator(Ctx, V);
1374 IsNullPtr = V.isNullPointer();
1375 }
1376
1377 void set(APValue::LValueBase B, bool BInvalid = false) {
1378#ifndef NDEBUG
1379 // We only allow a few types of invalid bases. Enforce that here.
1380 if (BInvalid) {
1381 const auto *E = B.get<const Expr *>();
1382 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&(((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base") ? static_cast<void>
(0) : __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1383, __PRETTY_FUNCTION__))
1383 "Unexpected type of invalid base")(((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base") ? static_cast<void>
(0) : __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1383, __PRETTY_FUNCTION__))
;
1384 }
1385#endif
1386
1387 Base = B;
1388 Offset = CharUnits::fromQuantity(0);
1389 InvalidBase = BInvalid;
1390 Designator = SubobjectDesignator(getType(B));
1391 IsNullPtr = false;
1392 }
1393
1394 void setNull(QualType PointerTy, uint64_t TargetVal) {
1395 Base = (Expr *)nullptr;
1396 Offset = CharUnits::fromQuantity(TargetVal);
1397 InvalidBase = false;
1398 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1399 IsNullPtr = true;
1400 }
1401
1402 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1403 set(B, true);
1404 }
1405
1406 private:
1407 // Check that this LValue is not based on a null pointer. If it is, produce
1408 // a diagnostic and mark the designator as invalid.
1409 template <typename GenDiagType>
1410 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1411 if (Designator.Invalid)
1412 return false;
1413 if (IsNullPtr) {
1414 GenDiag();
1415 Designator.setInvalid();
1416 return false;
1417 }
1418 return true;
1419 }
1420
1421 public:
1422 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1423 CheckSubobjectKind CSK) {
1424 return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1425 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1426 });
1427 }
1428
1429 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1430 AccessKinds AK) {
1431 return checkNullPointerDiagnosingWith([&Info, E, AK] {
1432 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1433 });
1434 }
1435
1436 // Check this LValue refers to an object. If not, set the designator to be
1437 // invalid and emit a diagnostic.
1438 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1439 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1440 Designator.checkSubobject(Info, E, CSK);
1441 }
1442
1443 void addDecl(EvalInfo &Info, const Expr *E,
1444 const Decl *D, bool Virtual = false) {
1445 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1446 Designator.addDeclUnchecked(D, Virtual);
1447 }
1448 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1449 if (!Designator.Entries.empty()) {
1450 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1451 Designator.setInvalid();
1452 return;
1453 }
1454 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1455 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType())((getType(Base)->isPointerType() || getType(Base)->isArrayType
()) ? static_cast<void> (0) : __assert_fail ("getType(Base)->isPointerType() || getType(Base)->isArrayType()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1455, __PRETTY_FUNCTION__))
;
1456 Designator.FirstEntryIsAnUnsizedArray = true;
1457 Designator.addUnsizedArrayUnchecked(ElemTy);
1458 }
1459 }
1460 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1461 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1462 Designator.addArrayUnchecked(CAT);
1463 }
1464 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1465 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1466 Designator.addComplexUnchecked(EltTy, Imag);
1467 }
1468 void clearIsNullPointer() {
1469 IsNullPtr = false;
1470 }
1471 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1472 const APSInt &Index, CharUnits ElementSize) {
1473 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1474 // but we're not required to diagnose it and it's valid in C++.)
1475 if (!Index)
1476 return;
1477
1478 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1479 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1480 // offsets.
1481 uint64_t Offset64 = Offset.getQuantity();
1482 uint64_t ElemSize64 = ElementSize.getQuantity();
1483 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1484 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1485
1486 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1487 Designator.adjustIndex(Info, E, Index);
1488 clearIsNullPointer();
1489 }
1490 void adjustOffset(CharUnits N) {
1491 Offset += N;
1492 if (N.getQuantity())
1493 clearIsNullPointer();
1494 }
1495 };
1496
1497 struct MemberPtr {
1498 MemberPtr() {}
1499 explicit MemberPtr(const ValueDecl *Decl) :
1500 DeclAndIsDerivedMember(Decl, false), Path() {}
1501
1502 /// The member or (direct or indirect) field referred to by this member
1503 /// pointer, or 0 if this is a null member pointer.
1504 const ValueDecl *getDecl() const {
1505 return DeclAndIsDerivedMember.getPointer();
1506 }
1507 /// Is this actually a member of some type derived from the relevant class?
1508 bool isDerivedMember() const {
1509 return DeclAndIsDerivedMember.getInt();
1510 }
1511 /// Get the class which the declaration actually lives in.
1512 const CXXRecordDecl *getContainingRecord() const {
1513 return cast<CXXRecordDecl>(
1514 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1515 }
1516
1517 void moveInto(APValue &V) const {
1518 V = APValue(getDecl(), isDerivedMember(), Path);
1519 }
1520 void setFrom(const APValue &V) {
1521 assert(V.isMemberPointer())((V.isMemberPointer()) ? static_cast<void> (0) : __assert_fail
("V.isMemberPointer()", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1521, __PRETTY_FUNCTION__))
;
1522 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1523 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1524 Path.clear();
1525 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1526 Path.insert(Path.end(), P.begin(), P.end());
1527 }
1528
1529 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1530 /// whether the member is a member of some class derived from the class type
1531 /// of the member pointer.
1532 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1533 /// Path - The path of base/derived classes from the member declaration's
1534 /// class (exclusive) to the class type of the member pointer (inclusive).
1535 SmallVector<const CXXRecordDecl*, 4> Path;
1536
1537 /// Perform a cast towards the class of the Decl (either up or down the
1538 /// hierarchy).
1539 bool castBack(const CXXRecordDecl *Class) {
1540 assert(!Path.empty())((!Path.empty()) ? static_cast<void> (0) : __assert_fail
("!Path.empty()", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1540, __PRETTY_FUNCTION__))
;
1541 const CXXRecordDecl *Expected;
1542 if (Path.size() >= 2)
1543 Expected = Path[Path.size() - 2];
1544 else
1545 Expected = getContainingRecord();
1546 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1547 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1548 // if B does not contain the original member and is not a base or
1549 // derived class of the class containing the original member, the result
1550 // of the cast is undefined.
1551 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1552 // (D::*). We consider that to be a language defect.
1553 return false;
1554 }
1555 Path.pop_back();
1556 return true;
1557 }
1558 /// Perform a base-to-derived member pointer cast.
1559 bool castToDerived(const CXXRecordDecl *Derived) {
1560 if (!getDecl())
1561 return true;
1562 if (!isDerivedMember()) {
1563 Path.push_back(Derived);
1564 return true;
1565 }
1566 if (!castBack(Derived))
1567 return false;
1568 if (Path.empty())
1569 DeclAndIsDerivedMember.setInt(false);
1570 return true;
1571 }
1572 /// Perform a derived-to-base member pointer cast.
1573 bool castToBase(const CXXRecordDecl *Base) {
1574 if (!getDecl())
1575 return true;
1576 if (Path.empty())
1577 DeclAndIsDerivedMember.setInt(true);
1578 if (isDerivedMember()) {
1579 Path.push_back(Base);
1580 return true;
1581 }
1582 return castBack(Base);
1583 }
1584 };
1585
1586 /// Compare two member pointers, which are assumed to be of the same type.
1587 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1588 if (!LHS.getDecl() || !RHS.getDecl())
1589 return !LHS.getDecl() && !RHS.getDecl();
1590 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1591 return false;
1592 return LHS.Path == RHS.Path;
1593 }
1594}
1595
1596static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1597static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1598 const LValue &This, const Expr *E,
1599 bool AllowNonLiteralTypes = false);
1600static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1601 bool InvalidBaseOK = false);
1602static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1603 bool InvalidBaseOK = false);
1604static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1605 EvalInfo &Info);
1606static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1607static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1608static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1609 EvalInfo &Info);
1610static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1611static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1612static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1613 EvalInfo &Info);
1614static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1615
1616//===----------------------------------------------------------------------===//
1617// Misc utilities
1618//===----------------------------------------------------------------------===//
1619
1620/// A helper function to create a temporary and set an LValue.
1621template <class KeyTy>
1622static APValue &createTemporary(const KeyTy *Key, bool IsLifetimeExtended,
1623 LValue &LV, CallStackFrame &Frame) {
1624 LV.set({Key, Frame.Info.CurrentCall->Index,
1625 Frame.Info.CurrentCall->getTempVersion()});
1626 return Frame.createTemporary(Key, IsLifetimeExtended);
1627}
1628
1629/// Negate an APSInt in place, converting it to a signed form if necessary, and
1630/// preserving its value (by extending by up to one bit as needed).
1631static void negateAsSigned(APSInt &Int) {
1632 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1633 Int = Int.extend(Int.getBitWidth() + 1);
1634 Int.setIsSigned(true);
1635 }
1636 Int = -Int;
1637}
1638
1639/// Produce a string describing the given constexpr call.
1640static void describeCall(CallStackFrame *Frame, raw_ostream &Out) {
1641 unsigned ArgIndex = 0;
1642 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) &&
1643 !isa<CXXConstructorDecl>(Frame->Callee) &&
1644 cast<CXXMethodDecl>(Frame->Callee)->isInstance();
1645
1646 if (!IsMemberCall)
1647 Out << *Frame->Callee << '(';
1648
1649 if (Frame->This && IsMemberCall) {
1650 APValue Val;
1651 Frame->This->moveInto(Val);
1652 Val.printPretty(Out, Frame->Info.Ctx,
1653 Frame->This->Designator.MostDerivedType);
1654 // FIXME: Add parens around Val if needed.
1655 Out << "->" << *Frame->Callee << '(';
1656 IsMemberCall = false;
1657 }
1658
1659 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(),
1660 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) {
1661 if (ArgIndex > (unsigned)IsMemberCall)
1662 Out << ", ";
1663
1664 const ParmVarDecl *Param = *I;
1665 const APValue &Arg = Frame->Arguments[ArgIndex];
1666 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType());
1667
1668 if (ArgIndex == 0 && IsMemberCall)
1669 Out << "->" << *Frame->Callee << '(';
1670 }
1671
1672 Out << ')';
1673}
1674
1675/// Evaluate an expression to see if it had side-effects, and discard its
1676/// result.
1677/// \return \c true if the caller should keep evaluating.
1678static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1679 APValue Scratch;
1680 if (!Evaluate(Scratch, Info, E))
6
Value assigned to field 'CurrentCall'
7
Assuming the condition is false
8
Taking false branch
1681 // We don't need the value, but we might have skipped a side effect here.
1682 return Info.noteSideEffect();
1683 return true;
1684}
1685
1686/// Should this call expression be treated as a string literal?
1687static bool IsStringLiteralCall(const CallExpr *E) {
1688 unsigned Builtin = E->getBuiltinCallee();
1689 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1690 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1691}
1692
1693static bool IsGlobalLValue(APValue::LValueBase B) {
1694 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1695 // constant expression of pointer type that evaluates to...
1696
1697 // ... a null pointer value, or a prvalue core constant expression of type
1698 // std::nullptr_t.
1699 if (!B) return true;
1700
1701 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1702 // ... the address of an object with static storage duration,
1703 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1704 return VD->hasGlobalStorage();
1705 // ... the address of a function,
1706 return isa<FunctionDecl>(D);
1707 }
1708
1709 const Expr *E = B.get<const Expr*>();
1710 switch (E->getStmtClass()) {
1711 default:
1712 return false;
1713 case Expr::CompoundLiteralExprClass: {
1714 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1715 return CLE->isFileScope() && CLE->isLValue();
1716 }
1717 case Expr::MaterializeTemporaryExprClass:
1718 // A materialized temporary might have been lifetime-extended to static
1719 // storage duration.
1720 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
1721 // A string literal has static storage duration.
1722 case Expr::StringLiteralClass:
1723 case Expr::PredefinedExprClass:
1724 case Expr::ObjCStringLiteralClass:
1725 case Expr::ObjCEncodeExprClass:
1726 case Expr::CXXTypeidExprClass:
1727 case Expr::CXXUuidofExprClass:
1728 return true;
1729 case Expr::CallExprClass:
1730 return IsStringLiteralCall(cast<CallExpr>(E));
1731 // For GCC compatibility, &&label has static storage duration.
1732 case Expr::AddrLabelExprClass:
1733 return true;
1734 // A Block literal expression may be used as the initialization value for
1735 // Block variables at global or local static scope.
1736 case Expr::BlockExprClass:
1737 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
1738 case Expr::ImplicitValueInitExprClass:
1739 // FIXME:
1740 // We can never form an lvalue with an implicit value initialization as its
1741 // base through expression evaluation, so these only appear in one case: the
1742 // implicit variable declaration we invent when checking whether a constexpr
1743 // constructor can produce a constant expression. We must assume that such
1744 // an expression might be a global lvalue.
1745 return true;
1746 }
1747}
1748
1749static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
1750 return LVal.Base.dyn_cast<const ValueDecl*>();
1751}
1752
1753static bool IsLiteralLValue(const LValue &Value) {
1754 if (Value.getLValueCallIndex())
1755 return false;
1756 const Expr *E = Value.Base.dyn_cast<const Expr*>();
1757 return E && !isa<MaterializeTemporaryExpr>(E);
1758}
1759
1760static bool IsWeakLValue(const LValue &Value) {
1761 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1762 return Decl && Decl->isWeak();
1763}
1764
1765static bool isZeroSized(const LValue &Value) {
1766 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1767 if (Decl && isa<VarDecl>(Decl)) {
1768 QualType Ty = Decl->getType();
1769 if (Ty->isArrayType())
1770 return Ty->isIncompleteType() ||
1771 Decl->getASTContext().getTypeSize(Ty) == 0;
1772 }
1773 return false;
1774}
1775
1776static bool HasSameBase(const LValue &A, const LValue &B) {
1777 if (!A.getLValueBase())
1778 return !B.getLValueBase();
1779 if (!B.getLValueBase())
1780 return false;
1781
1782 if (A.getLValueBase().getOpaqueValue() !=
1783 B.getLValueBase().getOpaqueValue()) {
1784 const Decl *ADecl = GetLValueBaseDecl(A);
1785 if (!ADecl)
1786 return false;
1787 const Decl *BDecl = GetLValueBaseDecl(B);
1788 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
1789 return false;
1790 }
1791
1792 return IsGlobalLValue(A.getLValueBase()) ||
1793 (A.getLValueCallIndex() == B.getLValueCallIndex() &&
1794 A.getLValueVersion() == B.getLValueVersion());
1795}
1796
1797static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
1798 assert(Base && "no location for a null lvalue")((Base && "no location for a null lvalue") ? static_cast
<void> (0) : __assert_fail ("Base && \"no location for a null lvalue\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1798, __PRETTY_FUNCTION__))
;
1799 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1800 if (VD)
1801 Info.Note(VD->getLocation(), diag::note_declared_at);
1802 else
1803 Info.Note(Base.get<const Expr*>()->getExprLoc(),
1804 diag::note_constexpr_temporary_here);
1805}
1806
1807/// Check that this reference or pointer core constant expression is a valid
1808/// value for an address or reference constant expression. Return true if we
1809/// can fold this expression, whether or not it's a constant expression.
1810static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
1811 QualType Type, const LValue &LVal,
1812 Expr::ConstExprUsage Usage) {
1813 bool IsReferenceType = Type->isReferenceType();
1814
1815 APValue::LValueBase Base = LVal.getLValueBase();
1816 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
1817
1818 // Check that the object is a global. Note that the fake 'this' object we
1819 // manufacture when checking potential constant expressions is conservatively
1820 // assumed to be global here.
1821 if (!IsGlobalLValue(Base)) {
1822 if (Info.getLangOpts().CPlusPlus11) {
1823 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1824 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
1825 << IsReferenceType << !Designator.Entries.empty()
1826 << !!VD << VD;
1827 NoteLValueLocation(Info, Base);
1828 } else {
1829 Info.FFDiag(Loc);
1830 }
1831 // Don't allow references to temporaries to escape.
1832 return false;
1833 }
1834 assert((Info.checkingPotentialConstantExpression() ||(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1836, __PRETTY_FUNCTION__))
1835 LVal.getLValueCallIndex() == 0) &&(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1836, __PRETTY_FUNCTION__))
1836 "have call index for global lvalue")(((Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex
() == 0) && "have call index for global lvalue") ? static_cast
<void> (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 1836, __PRETTY_FUNCTION__))
;
1837
1838 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
1839 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) {
1840 // Check if this is a thread-local variable.
1841 if (Var->getTLSKind())
1842 return false;
1843
1844 // A dllimport variable never acts like a constant.
1845 if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr<DLLImportAttr>())
1846 return false;
1847 }
1848 if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) {
1849 // __declspec(dllimport) must be handled very carefully:
1850 // We must never initialize an expression with the thunk in C++.
1851 // Doing otherwise would allow the same id-expression to yield
1852 // different addresses for the same function in different translation
1853 // units. However, this means that we must dynamically initialize the
1854 // expression with the contents of the import address table at runtime.
1855 //
1856 // The C language has no notion of ODR; furthermore, it has no notion of
1857 // dynamic initialization. This means that we are permitted to
1858 // perform initialization with the address of the thunk.
1859 if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen &&
1860 FD->hasAttr<DLLImportAttr>())
1861 return false;
1862 }
1863 }
1864
1865 // Allow address constant expressions to be past-the-end pointers. This is
1866 // an extension: the standard requires them to point to an object.
1867 if (!IsReferenceType)
1868 return true;
1869
1870 // A reference constant expression must refer to an object.
1871 if (!Base) {
1872 // FIXME: diagnostic
1873 Info.CCEDiag(Loc);
1874 return true;
1875 }
1876
1877 // Does this refer one past the end of some object?
1878 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
1879 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1880 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
1881 << !Designator.Entries.empty() << !!VD << VD;
1882 NoteLValueLocation(Info, Base);
1883 }
1884
1885 return true;
1886}
1887
1888/// Member pointers are constant expressions unless they point to a
1889/// non-virtual dllimport member function.
1890static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
1891 SourceLocation Loc,
1892 QualType Type,
1893 const APValue &Value,
1894 Expr::ConstExprUsage Usage) {
1895 const ValueDecl *Member = Value.getMemberPointerDecl();
1896 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
1897 if (!FD)
1898 return true;
1899 return Usage == Expr::EvaluateForMangling || FD->isVirtual() ||
1900 !FD->hasAttr<DLLImportAttr>();
1901}
1902
1903/// Check that this core constant expression is of literal type, and if not,
1904/// produce an appropriate diagnostic.
1905static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
1906 const LValue *This = nullptr) {
1907 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
1908 return true;
1909
1910 // C++1y: A constant initializer for an object o [...] may also invoke
1911 // constexpr constructors for o and its subobjects even if those objects
1912 // are of non-literal class types.
1913 //
1914 // C++11 missed this detail for aggregates, so classes like this:
1915 // struct foo_t { union { int i; volatile int j; } u; };
1916 // are not (obviously) initializable like so:
1917 // __attribute__((__require_constant_initialization__))
1918 // static const foo_t x = {{0}};
1919 // because "i" is a subobject with non-literal initialization (due to the
1920 // volatile member of the union). See:
1921 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
1922 // Therefore, we use the C++1y behavior.
1923 if (This && Info.EvaluatingDecl == This->getLValueBase())
1924 return true;
1925
1926 // Prvalue constant expressions must be of literal types.
1927 if (Info.getLangOpts().CPlusPlus11)
1928 Info.FFDiag(E, diag::note_constexpr_nonliteral)
1929 << E->getType();
1930 else
1931 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
1932 return false;
1933}
1934
1935/// Check that this core constant expression value is a valid value for a
1936/// constant expression. If not, report an appropriate diagnostic. Does not
1937/// check that the expression is of literal type.
1938static bool
1939CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type,
1940 const APValue &Value,
1941 Expr::ConstExprUsage Usage = Expr::EvaluateForCodeGen) {
1942 if (Value.isUninit()) {
1943 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
1944 << true << Type;
1945 return false;
1946 }
1947
1948 // We allow _Atomic(T) to be initialized from anything that T can be
1949 // initialized from.
1950 if (const AtomicType *AT = Type->getAs<AtomicType>())
1951 Type = AT->getValueType();
1952
1953 // Core issue 1454: For a literal constant expression of array or class type,
1954 // each subobject of its value shall have been initialized by a constant
1955 // expression.
1956 if (Value.isArray()) {
1957 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
1958 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
1959 if (!CheckConstantExpression(Info, DiagLoc, EltTy,
1960 Value.getArrayInitializedElt(I), Usage))
1961 return false;
1962 }
1963 if (!Value.hasArrayFiller())
1964 return true;
1965 return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller(),
1966 Usage);
1967 }
1968 if (Value.isUnion() && Value.getUnionField()) {
1969 return CheckConstantExpression(Info, DiagLoc,
1970 Value.getUnionField()->getType(),
1971 Value.getUnionValue(), Usage);
1972 }
1973 if (Value.isStruct()) {
1974 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
1975 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
1976 unsigned BaseIndex = 0;
1977 for (const CXXBaseSpecifier &BS : CD->bases()) {
1978 if (!CheckConstantExpression(Info, DiagLoc, BS.getType(),
1979 Value.getStructBase(BaseIndex), Usage))
1980 return false;
1981 ++BaseIndex;
1982 }
1983 }
1984 for (const auto *I : RD->fields()) {
1985 if (I->isUnnamedBitfield())
1986 continue;
1987
1988 if (!CheckConstantExpression(Info, DiagLoc, I->getType(),
1989 Value.getStructField(I->getFieldIndex()),
1990 Usage))
1991 return false;
1992 }
1993 }
1994
1995 if (Value.isLValue()) {
1996 LValue LVal;
1997 LVal.setFrom(Info.Ctx, Value);
1998 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage);
1999 }
2000
2001 if (Value.isMemberPointer())
2002 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage);
2003
2004 // Everything else is fine.
2005 return true;
2006}
2007
2008static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2009 // A null base expression indicates a null pointer. These are always
2010 // evaluatable, and they are false unless the offset is zero.
2011 if (!Value.getLValueBase()) {
2012 Result = !Value.getLValueOffset().isZero();
2013 return true;
2014 }
2015
2016 // We have a non-null base. These are generally known to be true, but if it's
2017 // a weak declaration it can be null at runtime.
2018 Result = true;
2019 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2020 return !Decl || !Decl->isWeak();
2021}
2022
2023static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2024 switch (Val.getKind()) {
2025 case APValue::Uninitialized:
2026 return false;
2027 case APValue::Int:
2028 Result = Val.getInt().getBoolValue();
2029 return true;
2030 case APValue::Float:
2031 Result = !Val.getFloat().isZero();
2032 return true;
2033 case APValue::ComplexInt:
2034 Result = Val.getComplexIntReal().getBoolValue() ||
2035 Val.getComplexIntImag().getBoolValue();
2036 return true;
2037 case APValue::ComplexFloat:
2038 Result = !Val.getComplexFloatReal().isZero() ||
2039 !Val.getComplexFloatImag().isZero();
2040 return true;
2041 case APValue::LValue:
2042 return EvalPointerValueAsBool(Val, Result);
2043 case APValue::MemberPointer:
2044 Result = Val.getMemberPointerDecl();
2045 return true;
2046 case APValue::Vector:
2047 case APValue::Array:
2048 case APValue::Struct:
2049 case APValue::Union:
2050 case APValue::AddrLabelDiff:
2051 return false;
2052 }
2053
2054 llvm_unreachable("unknown APValue kind")::llvm::llvm_unreachable_internal("unknown APValue kind", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2054)
;
2055}
2056
2057static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2058 EvalInfo &Info) {
2059 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition")((E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"
) ? static_cast<void> (0) : __assert_fail ("E->isRValue() && \"missing lvalue-to-rvalue conv in bool condition\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2059, __PRETTY_FUNCTION__))
;
2060 APValue Val;
2061 if (!Evaluate(Val, Info, E))
2062 return false;
2063 return HandleConversionToBool(Val, Result);
2064}
2065
2066template<typename T>
2067static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2068 const T &SrcValue, QualType DestType) {
2069 Info.CCEDiag(E, diag::note_constexpr_overflow)
2070 << SrcValue << DestType;
2071 return Info.noteUndefinedBehavior();
2072}
2073
2074static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2075 QualType SrcType, const APFloat &Value,
2076 QualType DestType, APSInt &Result) {
2077 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2078 // Determine whether we are converting to unsigned or signed.
2079 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2080
2081 Result = APSInt(DestWidth, !DestSigned);
2082 bool ignored;
2083 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2084 & APFloat::opInvalidOp)
2085 return HandleOverflow(Info, E, Value, DestType);
2086 return true;
2087}
2088
2089static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2090 QualType SrcType, QualType DestType,
2091 APFloat &Result) {
2092 APFloat Value = Result;
2093 bool ignored;
2094 if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType),
2095 APFloat::rmNearestTiesToEven, &ignored)
2096 & APFloat::opOverflow)
2097 return HandleOverflow(Info, E, Value, DestType);
2098 return true;
2099}
2100
2101static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2102 QualType DestType, QualType SrcType,
2103 const APSInt &Value) {
2104 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2105 // Figure out if this is a truncate, extend or noop cast.
2106 // If the input is signed, do a sign extend, noop, or truncate.
2107 APSInt Result = Value.extOrTrunc(DestWidth);
2108 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2109 if (DestType->isBooleanType())
2110 Result = Value.getBoolValue();
2111 return Result;
2112}
2113
2114static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2115 QualType SrcType, const APSInt &Value,
2116 QualType DestType, APFloat &Result) {
2117 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2118 if (Result.convertFromAPInt(Value, Value.isSigned(),
2119 APFloat::rmNearestTiesToEven)
2120 & APFloat::opOverflow)
2121 return HandleOverflow(Info, E, Value, DestType);
2122 return true;
2123}
2124
2125static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2126 APValue &Value, const FieldDecl *FD) {
2127 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield")((FD->isBitField() && "truncateBitfieldValue on non-bitfield"
) ? static_cast<void> (0) : __assert_fail ("FD->isBitField() && \"truncateBitfieldValue on non-bitfield\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2127, __PRETTY_FUNCTION__))
;
2128
2129 if (!Value.isInt()) {
2130 // Trying to store a pointer-cast-to-integer into a bitfield.
2131 // FIXME: In this case, we should provide the diagnostic for casting
2132 // a pointer to an integer.
2133 assert(Value.isLValue() && "integral value neither int nor lvalue?")((Value.isLValue() && "integral value neither int nor lvalue?"
) ? static_cast<void> (0) : __assert_fail ("Value.isLValue() && \"integral value neither int nor lvalue?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2133, __PRETTY_FUNCTION__))
;
2134 Info.FFDiag(E);
2135 return false;
2136 }
2137
2138 APSInt &Int = Value.getInt();
2139 unsigned OldBitWidth = Int.getBitWidth();
2140 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2141 if (NewBitWidth < OldBitWidth)
2142 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2143 return true;
2144}
2145
2146static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2147 llvm::APInt &Res) {
2148 APValue SVal;
2149 if (!Evaluate(SVal, Info, E))
2150 return false;
2151 if (SVal.isInt()) {
2152 Res = SVal.getInt();
2153 return true;
2154 }
2155 if (SVal.isFloat()) {
2156 Res = SVal.getFloat().bitcastToAPInt();
2157 return true;
2158 }
2159 if (SVal.isVector()) {
2160 QualType VecTy = E->getType();
2161 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2162 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2163 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2164 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2165 Res = llvm::APInt::getNullValue(VecSize);
2166 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2167 APValue &Elt = SVal.getVectorElt(i);
2168 llvm::APInt EltAsInt;
2169 if (Elt.isInt()) {
2170 EltAsInt = Elt.getInt();
2171 } else if (Elt.isFloat()) {
2172 EltAsInt = Elt.getFloat().bitcastToAPInt();
2173 } else {
2174 // Don't try to handle vectors of anything other than int or float
2175 // (not sure if it's possible to hit this case).
2176 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2177 return false;
2178 }
2179 unsigned BaseEltSize = EltAsInt.getBitWidth();
2180 if (BigEndian)
2181 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2182 else
2183 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2184 }
2185 return true;
2186 }
2187 // Give up if the input isn't an int, float, or vector. For example, we
2188 // reject "(v4i16)(intptr_t)&a".
2189 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2190 return false;
2191}
2192
2193/// Perform the given integer operation, which is known to need at most BitWidth
2194/// bits, and check for overflow in the original type (if that type was not an
2195/// unsigned type).
2196template<typename Operation>
2197static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2198 const APSInt &LHS, const APSInt &RHS,
2199 unsigned BitWidth, Operation Op,
2200 APSInt &Result) {
2201 if (LHS.isUnsigned()) {
2202 Result = Op(LHS, RHS);
2203 return true;
2204 }
2205
2206 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2207 Result = Value.trunc(LHS.getBitWidth());
2208 if (Result.extend(BitWidth) != Value) {
2209 if (Info.checkingForOverflow())
2210 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2211 diag::warn_integer_constant_overflow)
2212 << Result.toString(10) << E->getType();
2213 else
2214 return HandleOverflow(Info, E, Value, E->getType());
2215 }
2216 return true;
2217}
2218
2219/// Perform the given binary integer operation.
2220static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2221 BinaryOperatorKind Opcode, APSInt RHS,
2222 APSInt &Result) {
2223 switch (Opcode) {
2224 default:
2225 Info.FFDiag(E);
2226 return false;
2227 case BO_Mul:
2228 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2229 std::multiplies<APSInt>(), Result);
2230 case BO_Add:
2231 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2232 std::plus<APSInt>(), Result);
2233 case BO_Sub:
2234 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2235 std::minus<APSInt>(), Result);
2236 case BO_And: Result = LHS & RHS; return true;
2237 case BO_Xor: Result = LHS ^ RHS; return true;
2238 case BO_Or: Result = LHS | RHS; return true;
2239 case BO_Div:
2240 case BO_Rem:
2241 if (RHS == 0) {
2242 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2243 return false;
2244 }
2245 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2246 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2247 // this operation and gives the two's complement result.
2248 if (RHS.isNegative() && RHS.isAllOnesValue() &&
2249 LHS.isSigned() && LHS.isMinSignedValue())
2250 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2251 E->getType());
2252 return true;
2253 case BO_Shl: {
2254 if (Info.getLangOpts().OpenCL)
2255 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2256 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2257 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2258 RHS.isUnsigned());
2259 else if (RHS.isSigned() && RHS.isNegative()) {
2260 // During constant-folding, a negative shift is an opposite shift. Such
2261 // a shift is not a constant expression.
2262 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2263 RHS = -RHS;
2264 goto shift_right;
2265 }
2266 shift_left:
2267 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2268 // the shifted type.
2269 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2270 if (SA != RHS) {
2271 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2272 << RHS << E->getType() << LHS.getBitWidth();
2273 } else if (LHS.isSigned()) {
2274 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2275 // operand, and must not overflow the corresponding unsigned type.
2276 if (LHS.isNegative())
2277 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2278 else if (LHS.countLeadingZeros() < SA)
2279 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2280 }
2281 Result = LHS << SA;
2282 return true;
2283 }
2284 case BO_Shr: {
2285 if (Info.getLangOpts().OpenCL)
2286 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2287 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2288 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2289 RHS.isUnsigned());
2290 else if (RHS.isSigned() && RHS.isNegative()) {
2291 // During constant-folding, a negative shift is an opposite shift. Such a
2292 // shift is not a constant expression.
2293 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2294 RHS = -RHS;
2295 goto shift_left;
2296 }
2297 shift_right:
2298 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2299 // shifted type.
2300 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2301 if (SA != RHS)
2302 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2303 << RHS << E->getType() << LHS.getBitWidth();
2304 Result = LHS >> SA;
2305 return true;
2306 }
2307
2308 case BO_LT: Result = LHS < RHS; return true;
2309 case BO_GT: Result = LHS > RHS; return true;
2310 case BO_LE: Result = LHS <= RHS; return true;
2311 case BO_GE: Result = LHS >= RHS; return true;
2312 case BO_EQ: Result = LHS == RHS; return true;
2313 case BO_NE: Result = LHS != RHS; return true;
2314 case BO_Cmp:
2315 llvm_unreachable("BO_Cmp should be handled elsewhere")::llvm::llvm_unreachable_internal("BO_Cmp should be handled elsewhere"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2315)
;
2316 }
2317}
2318
2319/// Perform the given binary floating-point operation, in-place, on LHS.
2320static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E,
2321 APFloat &LHS, BinaryOperatorKind Opcode,
2322 const APFloat &RHS) {
2323 switch (Opcode) {
2324 default:
2325 Info.FFDiag(E);
2326 return false;
2327 case BO_Mul:
2328 LHS.multiply(RHS, APFloat::rmNearestTiesToEven);
2329 break;
2330 case BO_Add:
2331 LHS.add(RHS, APFloat::rmNearestTiesToEven);
2332 break;
2333 case BO_Sub:
2334 LHS.subtract(RHS, APFloat::rmNearestTiesToEven);
2335 break;
2336 case BO_Div:
2337 LHS.divide(RHS, APFloat::rmNearestTiesToEven);
2338 break;
2339 }
2340
2341 if (LHS.isInfinity() || LHS.isNaN()) {
2342 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2343 return Info.noteUndefinedBehavior();
2344 }
2345 return true;
2346}
2347
2348/// Cast an lvalue referring to a base subobject to a derived class, by
2349/// truncating the lvalue's path to the given length.
2350static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
2351 const RecordDecl *TruncatedType,
2352 unsigned TruncatedElements) {
2353 SubobjectDesignator &D = Result.Designator;
2354
2355 // Check we actually point to a derived class object.
2356 if (TruncatedElements == D.Entries.size())
2357 return true;
2358 assert(TruncatedElements >= D.MostDerivedPathLength &&((TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"
) ? static_cast<void> (0) : __assert_fail ("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2359, __PRETTY_FUNCTION__))
2359 "not casting to a derived class")((TruncatedElements >= D.MostDerivedPathLength && "not casting to a derived class"
) ? static_cast<void> (0) : __assert_fail ("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2359, __PRETTY_FUNCTION__))
;
2360 if (!Result.checkSubobject(Info, E, CSK_Derived))
2361 return false;
2362
2363 // Truncate the path to the subobject, and remove any derived-to-base offsets.
2364 const RecordDecl *RD = TruncatedType;
2365 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
2366 if (RD->isInvalidDecl()) return false;
2367 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
2368 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
2369 if (isVirtualBaseClass(D.Entries[I]))
2370 Result.Offset -= Layout.getVBaseClassOffset(Base);
2371 else
2372 Result.Offset -= Layout.getBaseClassOffset(Base);
2373 RD = Base;
2374 }
2375 D.Entries.resize(TruncatedElements);
2376 return true;
2377}
2378
2379static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2380 const CXXRecordDecl *Derived,
2381 const CXXRecordDecl *Base,
2382 const ASTRecordLayout *RL = nullptr) {
2383 if (!RL) {
2384 if (Derived->isInvalidDecl()) return false;
2385 RL = &Info.Ctx.getASTRecordLayout(Derived);
2386 }
2387
2388 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
2389 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
2390 return true;
2391}
2392
2393static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2394 const CXXRecordDecl *DerivedDecl,
2395 const CXXBaseSpecifier *Base) {
2396 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
2397
2398 if (!Base->isVirtual())
2399 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
2400
2401 SubobjectDesignator &D = Obj.Designator;
2402 if (D.Invalid)
2403 return false;
2404
2405 // Extract most-derived object and corresponding type.
2406 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
2407 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
2408 return false;
2409
2410 // Find the virtual base class.
2411 if (DerivedDecl->isInvalidDecl()) return false;
2412 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
2413 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
2414 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
2415 return true;
2416}
2417
2418static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
2419 QualType Type, LValue &Result) {
2420 for (CastExpr::path_const_iterator PathI = E->path_begin(),
2421 PathE = E->path_end();
2422 PathI != PathE; ++PathI) {
2423 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
2424 *PathI))
2425 return false;
2426 Type = (*PathI)->getType();
2427 }
2428 return true;
2429}
2430
2431/// Update LVal to refer to the given field, which must be a member of the type
2432/// currently described by LVal.
2433static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
2434 const FieldDecl *FD,
2435 const ASTRecordLayout *RL = nullptr) {
2436 if (!RL) {
2437 if (FD->getParent()->isInvalidDecl()) return false;
2438 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
2439 }
2440
2441 unsigned I = FD->getFieldIndex();
2442 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
2443 LVal.addDecl(Info, E, FD);
2444 return true;
2445}
2446
2447/// Update LVal to refer to the given indirect field.
2448static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
2449 LValue &LVal,
2450 const IndirectFieldDecl *IFD) {
2451 for (const auto *C : IFD->chain())
2452 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
2453 return false;
2454 return true;
2455}
2456
2457/// Get the size of the given type in char units.
2458static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
2459 QualType Type, CharUnits &Size) {
2460 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
2461 // extension.
2462 if (Type->isVoidType() || Type->isFunctionType()) {
2463 Size = CharUnits::One();
2464 return true;
2465 }
2466
2467 if (Type->isDependentType()) {
2468 Info.FFDiag(Loc);
2469 return false;
2470 }
2471
2472 if (!Type->isConstantSizeType()) {
2473 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
2474 // FIXME: Better diagnostic.
2475 Info.FFDiag(Loc);
2476 return false;
2477 }
2478
2479 Size = Info.Ctx.getTypeSizeInChars(Type);
2480 return true;
2481}
2482
2483/// Update a pointer value to model pointer arithmetic.
2484/// \param Info - Information about the ongoing evaluation.
2485/// \param E - The expression being evaluated, for diagnostic purposes.
2486/// \param LVal - The pointer value to be updated.
2487/// \param EltTy - The pointee type represented by LVal.
2488/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
2489static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2490 LValue &LVal, QualType EltTy,
2491 APSInt Adjustment) {
2492 CharUnits SizeOfPointee;
2493 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
2494 return false;
2495
2496 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
2497 return true;
2498}
2499
2500static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2501 LValue &LVal, QualType EltTy,
2502 int64_t Adjustment) {
2503 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
2504 APSInt::get(Adjustment));
2505}
2506
2507/// Update an lvalue to refer to a component of a complex number.
2508/// \param Info - Information about the ongoing evaluation.
2509/// \param LVal - The lvalue to be updated.
2510/// \param EltTy - The complex number's component type.
2511/// \param Imag - False for the real component, true for the imaginary.
2512static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
2513 LValue &LVal, QualType EltTy,
2514 bool Imag) {
2515 if (Imag) {
2516 CharUnits SizeOfComponent;
2517 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
2518 return false;
2519 LVal.Offset += SizeOfComponent;
2520 }
2521 LVal.addComplex(Info, E, EltTy, Imag);
2522 return true;
2523}
2524
2525static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
2526 QualType Type, const LValue &LVal,
2527 APValue &RVal);
2528
2529/// Try to evaluate the initializer for a variable declaration.
2530///
2531/// \param Info Information about the ongoing evaluation.
2532/// \param E An expression to be used when printing diagnostics.
2533/// \param VD The variable whose initializer should be obtained.
2534/// \param Frame The frame in which the variable was created. Must be null
2535/// if this variable is not local to the evaluation.
2536/// \param Result Filled in with a pointer to the value of the variable.
2537static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
2538 const VarDecl *VD, CallStackFrame *Frame,
2539 APValue *&Result, const LValue *LVal) {
2540
2541 // If this is a parameter to an active constexpr function call, perform
2542 // argument substitution.
2543 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
2544 // Assume arguments of a potential constant expression are unknown
2545 // constant expressions.
2546 if (Info.checkingPotentialConstantExpression())
2547 return false;
2548 if (!Frame || !Frame->Arguments) {
2549 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2550 return false;
2551 }
2552 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()];
2553 return true;
2554 }
2555
2556 // If this is a local variable, dig out its value.
2557 if (Frame) {
2558 Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion())
2559 : Frame->getCurrentTemporary(VD);
2560 if (!Result) {
2561 // Assume variables referenced within a lambda's call operator that were
2562 // not declared within the call operator are captures and during checking
2563 // of a potential constant expression, assume they are unknown constant
2564 // expressions.
2565 assert(isLambdaCallOperator(Frame->Callee) &&((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2567, __PRETTY_FUNCTION__))
2566 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2567, __PRETTY_FUNCTION__))
2567 "missing value for local variable")((isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext
() != Frame->Callee || VD->isInitCapture()) && "missing value for local variable"
) ? static_cast<void> (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2567, __PRETTY_FUNCTION__))
;
2568 if (Info.checkingPotentialConstantExpression())
2569 return false;
2570 // FIXME: implement capture evaluation during constant expr evaluation.
2571 Info.FFDiag(E->getBeginLoc(),
2572 diag::note_unimplemented_constexpr_lambda_feature_ast)
2573 << "captures not currently allowed";
2574 return false;
2575 }
2576 return true;
2577 }
2578
2579 // Dig out the initializer, and use the declaration which it's attached to.
2580 const Expr *Init = VD->getAnyInitializer(VD);
2581 if (!Init || Init->isValueDependent()) {
2582 // If we're checking a potential constant expression, the variable could be
2583 // initialized later.
2584 if (!Info.checkingPotentialConstantExpression())
2585 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2586 return false;
2587 }
2588
2589 // If we're currently evaluating the initializer of this declaration, use that
2590 // in-flight value.
2591 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
2592 Result = Info.EvaluatingDeclValue;
2593 return true;
2594 }
2595
2596 // Never evaluate the initializer of a weak variable. We can't be sure that
2597 // this is the definition which will be used.
2598 if (VD->isWeak()) {
2599 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2600 return false;
2601 }
2602
2603 // Check that we can fold the initializer. In C++, we will have already done
2604 // this in the cases where it matters for conformance.
2605 SmallVector<PartialDiagnosticAt, 8> Notes;
2606 if (!VD->evaluateValue(Notes)) {
2607 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant,
2608 Notes.size() + 1) << VD;
2609 Info.Note(VD->getLocation(), diag::note_declared_at);
2610 Info.addNotes(Notes);
2611 return false;
2612 } else if (!VD->checkInitIsICE()) {
2613 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant,
2614 Notes.size() + 1) << VD;
2615 Info.Note(VD->getLocation(), diag::note_declared_at);
2616 Info.addNotes(Notes);
2617 }
2618
2619 Result = VD->getEvaluatedValue();
2620 return true;
2621}
2622
2623static bool IsConstNonVolatile(QualType T) {
2624 Qualifiers Quals = T.getQualifiers();
2625 return Quals.hasConst() && !Quals.hasVolatile();
2626}
2627
2628/// Get the base index of the given base class within an APValue representing
2629/// the given derived class.
2630static unsigned getBaseIndex(const CXXRecordDecl *Derived,
2631 const CXXRecordDecl *Base) {
2632 Base = Base->getCanonicalDecl();
2633 unsigned Index = 0;
2634 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
2635 E = Derived->bases_end(); I != E; ++I, ++Index) {
2636 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
2637 return Index;
2638 }
2639
2640 llvm_unreachable("base class missing from derived class's bases list")::llvm::llvm_unreachable_internal("base class missing from derived class's bases list"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2640)
;
2641}
2642
2643/// Extract the value of a character from a string literal.
2644static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
2645 uint64_t Index) {
2646 // FIXME: Support MakeStringConstant
2647 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
2648 std::string Str;
2649 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
2650 assert(Index <= Str.size() && "Index too large")((Index <= Str.size() && "Index too large") ? static_cast
<void> (0) : __assert_fail ("Index <= Str.size() && \"Index too large\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2650, __PRETTY_FUNCTION__))
;
2651 return APSInt::getUnsigned(Str.c_str()[Index]);
2652 }
2653
2654 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
2655 Lit = PE->getFunctionName();
2656 const StringLiteral *S = cast<StringLiteral>(Lit);
2657 const ConstantArrayType *CAT =
2658 Info.Ctx.getAsConstantArrayType(S->getType());
2659 assert(CAT && "string literal isn't an array")((CAT && "string literal isn't an array") ? static_cast
<void> (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2659, __PRETTY_FUNCTION__))
;
2660 QualType CharType = CAT->getElementType();
2661 assert(CharType->isIntegerType() && "unexpected character type")((CharType->isIntegerType() && "unexpected character type"
) ? static_cast<void> (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2661, __PRETTY_FUNCTION__))
;
2662
2663 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2664 CharType->isUnsignedIntegerType());
2665 if (Index < S->getLength())
2666 Value = S->getCodeUnit(Index);
2667 return Value;
2668}
2669
2670// Expand a string literal into an array of characters.
2671static void expandStringLiteral(EvalInfo &Info, const Expr *Lit,
2672 APValue &Result) {
2673 const StringLiteral *S = cast<StringLiteral>(Lit);
2674 const ConstantArrayType *CAT =
2675 Info.Ctx.getAsConstantArrayType(S->getType());
2676 assert(CAT && "string literal isn't an array")((CAT && "string literal isn't an array") ? static_cast
<void> (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2676, __PRETTY_FUNCTION__))
;
2677 QualType CharType = CAT->getElementType();
2678 assert(CharType->isIntegerType() && "unexpected character type")((CharType->isIntegerType() && "unexpected character type"
) ? static_cast<void> (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2678, __PRETTY_FUNCTION__))
;
2679
2680 unsigned Elts = CAT->getSize().getZExtValue();
2681 Result = APValue(APValue::UninitArray(),
2682 std::min(S->getLength(), Elts), Elts);
2683 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2684 CharType->isUnsignedIntegerType());
2685 if (Result.hasArrayFiller())
2686 Result.getArrayFiller() = APValue(Value);
2687 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
2688 Value = S->getCodeUnit(I);
2689 Result.getArrayInitializedElt(I) = APValue(Value);
2690 }
2691}
2692
2693// Expand an array so that it has more than Index filled elements.
2694static void expandArray(APValue &Array, unsigned Index) {
2695 unsigned Size = Array.getArraySize();
2696 assert(Index < Size)((Index < Size) ? static_cast<void> (0) : __assert_fail
("Index < Size", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2696, __PRETTY_FUNCTION__))
;
2697
2698 // Always at least double the number of elements for which we store a value.
2699 unsigned OldElts = Array.getArrayInitializedElts();
2700 unsigned NewElts = std::max(Index+1, OldElts * 2);
2701 NewElts = std::min(Size, std::max(NewElts, 8u));
2702
2703 // Copy the data across.
2704 APValue NewValue(APValue::UninitArray(), NewElts, Size);
2705 for (unsigned I = 0; I != OldElts; ++I)
2706 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
2707 for (unsigned I = OldElts; I != NewElts; ++I)
2708 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
2709 if (NewValue.hasArrayFiller())
2710 NewValue.getArrayFiller() = Array.getArrayFiller();
2711 Array.swap(NewValue);
2712}
2713
2714/// Determine whether a type would actually be read by an lvalue-to-rvalue
2715/// conversion. If it's of class type, we may assume that the copy operation
2716/// is trivial. Note that this is never true for a union type with fields
2717/// (because the copy always "reads" the active member) and always true for
2718/// a non-class type.
2719static bool isReadByLvalueToRvalueConversion(QualType T) {
2720 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
2721 if (!RD || (RD->isUnion() && !RD->field_empty()))
2722 return true;
2723 if (RD->isEmpty())
2724 return false;
2725
2726 for (auto *Field : RD->fields())
2727 if (isReadByLvalueToRvalueConversion(Field->getType()))
2728 return true;
2729
2730 for (auto &BaseSpec : RD->bases())
2731 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
2732 return true;
2733
2734 return false;
2735}
2736
2737/// Diagnose an attempt to read from any unreadable field within the specified
2738/// type, which might be a class type.
2739static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E,
2740 QualType T) {
2741 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
2742 if (!RD)
2743 return false;
2744
2745 if (!RD->hasMutableFields())
2746 return false;
2747
2748 for (auto *Field : RD->fields()) {
2749 // If we're actually going to read this field in some way, then it can't
2750 // be mutable. If we're in a union, then assigning to a mutable field
2751 // (even an empty one) can change the active member, so that's not OK.
2752 // FIXME: Add core issue number for the union case.
2753 if (Field->isMutable() &&
2754 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
2755 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field;
2756 Info.Note(Field->getLocation(), diag::note_declared_at);
2757 return true;
2758 }
2759
2760 if (diagnoseUnreadableFields(Info, E, Field->getType()))
2761 return true;
2762 }
2763
2764 for (auto &BaseSpec : RD->bases())
2765 if (diagnoseUnreadableFields(Info, E, BaseSpec.getType()))
2766 return true;
2767
2768 // All mutable fields were empty, and thus not actually read.
2769 return false;
2770}
2771
2772namespace {
2773/// A handle to a complete object (an object that is not a subobject of
2774/// another object).
2775struct CompleteObject {
2776 /// The value of the complete object.
2777 APValue *Value;
2778 /// The type of the complete object.
2779 QualType Type;
2780 bool LifetimeStartedInEvaluation;
2781
2782 CompleteObject() : Value(nullptr) {}
2783 CompleteObject(APValue *Value, QualType Type,
2784 bool LifetimeStartedInEvaluation)
2785 : Value(Value), Type(Type),
2786 LifetimeStartedInEvaluation(LifetimeStartedInEvaluation) {
2787 assert(Value && "missing value for complete object")((Value && "missing value for complete object") ? static_cast
<void> (0) : __assert_fail ("Value && \"missing value for complete object\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2787, __PRETTY_FUNCTION__))
;
2788 }
2789
2790 explicit operator bool() const { return Value; }
2791};
2792} // end anonymous namespace
2793
2794/// Find the designated sub-object of an rvalue.
2795template<typename SubobjectHandler>
2796typename SubobjectHandler::result_type
2797findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
2798 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
2799 if (Sub.Invalid)
2800 // A diagnostic will have already been produced.
2801 return handler.failed();
2802 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
2803 if (Info.getLangOpts().CPlusPlus11)
2804 Info.FFDiag(E, Sub.isOnePastTheEnd()
2805 ? diag::note_constexpr_access_past_end
2806 : diag::note_constexpr_access_unsized_array)
2807 << handler.AccessKind;
2808 else
2809 Info.FFDiag(E);
2810 return handler.failed();
2811 }
2812
2813 APValue *O = Obj.Value;
2814 QualType ObjType = Obj.Type;
2815 const FieldDecl *LastField = nullptr;
2816 const bool MayReadMutableMembers =
2817 Obj.LifetimeStartedInEvaluation && Info.getLangOpts().CPlusPlus14;
2818
2819 // Walk the designator's path to find the subobject.
2820 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
2821 if (O->isUninit()) {
2822 if (!Info.checkingPotentialConstantExpression())
2823 Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind;
2824 return handler.failed();
2825 }
2826
2827 if (I == N) {
2828 // If we are reading an object of class type, there may still be more
2829 // things we need to check: if there are any mutable subobjects, we
2830 // cannot perform this read. (This only happens when performing a trivial
2831 // copy or assignment.)
2832 if (ObjType->isRecordType() && handler.AccessKind == AK_Read &&
2833 !MayReadMutableMembers && diagnoseUnreadableFields(Info, E, ObjType))
2834 return handler.failed();
2835
2836 if (!handler.found(*O, ObjType))
2837 return false;
2838
2839 // If we modified a bit-field, truncate it to the right width.
2840 if (handler.AccessKind != AK_Read &&
2841 LastField && LastField->isBitField() &&
2842 !truncateBitfieldValue(Info, E, *O, LastField))
2843 return false;
2844
2845 return true;
2846 }
2847
2848 LastField = nullptr;
2849 if (ObjType->isArrayType()) {
2850 // Next subobject is an array element.
2851 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
2852 assert(CAT && "vla in literal type?")((CAT && "vla in literal type?") ? static_cast<void
> (0) : __assert_fail ("CAT && \"vla in literal type?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2852, __PRETTY_FUNCTION__))
;
2853 uint64_t Index = Sub.Entries[I].ArrayIndex;
2854 if (CAT->getSize().ule(Index)) {
2855 // Note, it should not be possible to form a pointer with a valid
2856 // designator which points more than one past the end of the array.
2857 if (Info.getLangOpts().CPlusPlus11)
2858 Info.FFDiag(E, diag::note_constexpr_access_past_end)
2859 << handler.AccessKind;
2860 else
2861 Info.FFDiag(E);
2862 return handler.failed();
2863 }
2864
2865 ObjType = CAT->getElementType();
2866
2867 // An array object is represented as either an Array APValue or as an
2868 // LValue which refers to a string literal.
2869 if (O->isLValue()) {
2870 assert(I == N - 1 && "extracting subobject of character?")((I == N - 1 && "extracting subobject of character?")
? static_cast<void> (0) : __assert_fail ("I == N - 1 && \"extracting subobject of character?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2870, __PRETTY_FUNCTION__))
;
2871 assert(!O->hasLValuePath() || O->getLValuePath().empty())((!O->hasLValuePath() || O->getLValuePath().empty()) ? static_cast
<void> (0) : __assert_fail ("!O->hasLValuePath() || O->getLValuePath().empty()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2871, __PRETTY_FUNCTION__))
;
2872 if (handler.AccessKind != AK_Read)
2873 expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(),
2874 *O);
2875 else
2876 return handler.foundString(*O, ObjType, Index);
2877 }
2878
2879 if (O->getArrayInitializedElts() > Index)
2880 O = &O->getArrayInitializedElt(Index);
2881 else if (handler.AccessKind != AK_Read) {
2882 expandArray(*O, Index);
2883 O = &O->getArrayInitializedElt(Index);
2884 } else
2885 O = &O->getArrayFiller();
2886 } else if (ObjType->isAnyComplexType()) {
2887 // Next subobject is a complex number.
2888 uint64_t Index = Sub.Entries[I].ArrayIndex;
2889 if (Index > 1) {
2890 if (Info.getLangOpts().CPlusPlus11)
2891 Info.FFDiag(E, diag::note_constexpr_access_past_end)
2892 << handler.AccessKind;
2893 else
2894 Info.FFDiag(E);
2895 return handler.failed();
2896 }
2897
2898 bool WasConstQualified = ObjType.isConstQualified();
2899 ObjType = ObjType->castAs<ComplexType>()->getElementType();
2900 if (WasConstQualified)
2901 ObjType.addConst();
2902
2903 assert(I == N - 1 && "extracting subobject of scalar?")((I == N - 1 && "extracting subobject of scalar?") ? static_cast
<void> (0) : __assert_fail ("I == N - 1 && \"extracting subobject of scalar?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2903, __PRETTY_FUNCTION__))
;
2904 if (O->isComplexInt()) {
2905 return handler.found(Index ? O->getComplexIntImag()
2906 : O->getComplexIntReal(), ObjType);
2907 } else {
2908 assert(O->isComplexFloat())((O->isComplexFloat()) ? static_cast<void> (0) : __assert_fail
("O->isComplexFloat()", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 2908, __PRETTY_FUNCTION__))
;
2909 return handler.found(Index ? O->getComplexFloatImag()
2910 : O->getComplexFloatReal(), ObjType);
2911 }
2912 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
2913 // In C++14 onwards, it is permitted to read a mutable member whose
2914 // lifetime began within the evaluation.
2915 // FIXME: Should we also allow this in C++11?
2916 if (Field->isMutable() && handler.AccessKind == AK_Read &&
2917 !MayReadMutableMembers) {
2918 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1)
2919 << Field;
2920 Info.Note(Field->getLocation(), diag::note_declared_at);
2921 return handler.failed();
2922 }
2923
2924 // Next subobject is a class, struct or union field.
2925 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
2926 if (RD->isUnion()) {
2927 const FieldDecl *UnionField = O->getUnionField();
2928 if (!UnionField ||
2929 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
2930 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
2931 << handler.AccessKind << Field << !UnionField << UnionField;
2932 return handler.failed();
2933 }
2934 O = &O->getUnionValue();
2935 } else
2936 O = &O->getStructField(Field->getFieldIndex());
2937
2938 bool WasConstQualified = ObjType.isConstQualified();
2939 ObjType = Field->getType();
2940 if (WasConstQualified && !Field->isMutable())
2941 ObjType.addConst();
2942
2943 if (ObjType.isVolatileQualified()) {
2944 if (Info.getLangOpts().CPlusPlus) {
2945 // FIXME: Include a description of the path to the volatile subobject.
2946 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
2947 << handler.AccessKind << 2 << Field;
2948 Info.Note(Field->getLocation(), diag::note_declared_at);
2949 } else {
2950 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2951 }
2952 return handler.failed();
2953 }
2954
2955 LastField = Field;
2956 } else {
2957 // Next subobject is a base class.
2958 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
2959 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
2960 O = &O->getStructBase(getBaseIndex(Derived, Base));
2961
2962 bool WasConstQualified = ObjType.isConstQualified();
2963 ObjType = Info.Ctx.getRecordType(Base);
2964 if (WasConstQualified)
2965 ObjType.addConst();
2966 }
2967 }
2968}
2969
2970namespace {
2971struct ExtractSubobjectHandler {
2972 EvalInfo &Info;
2973 APValue &Result;
2974
2975 static const AccessKinds AccessKind = AK_Read;
2976
2977 typedef bool result_type;
2978 bool failed() { return false; }
2979 bool found(APValue &Subobj, QualType SubobjType) {
2980 Result = Subobj;
2981 return true;
2982 }
2983 bool found(APSInt &Value, QualType SubobjType) {
2984 Result = APValue(Value);
2985 return true;
2986 }
2987 bool found(APFloat &Value, QualType SubobjType) {
2988 Result = APValue(Value);
2989 return true;
2990 }
2991 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
2992 Result = APValue(extractStringLiteralCharacter(
2993 Info, Subobj.getLValueBase().get<const Expr *>(), Character));
2994 return true;
2995 }
2996};
2997} // end anonymous namespace
2998
2999const AccessKinds ExtractSubobjectHandler::AccessKind;
3000
3001/// Extract the designated sub-object of an rvalue.
3002static bool extractSubobject(EvalInfo &Info, const Expr *E,
3003 const CompleteObject &Obj,
3004 const SubobjectDesignator &Sub,
3005 APValue &Result) {
3006 ExtractSubobjectHandler Handler = { Info, Result };
3007 return findSubobject(Info, E, Obj, Sub, Handler);
3008}
3009
3010namespace {
3011struct ModifySubobjectHandler {
3012 EvalInfo &Info;
3013 APValue &NewVal;
3014 const Expr *E;
3015
3016 typedef bool result_type;
3017 static const AccessKinds AccessKind = AK_Assign;
3018
3019 bool checkConst(QualType QT) {
3020 // Assigning to a const object has undefined behavior.
3021 if (QT.isConstQualified()) {
3022 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3023 return false;
3024 }
3025 return true;
3026 }
3027
3028 bool failed() { return false; }
3029 bool found(APValue &Subobj, QualType SubobjType) {
3030 if (!checkConst(SubobjType))
3031 return false;
3032 // We've been given ownership of NewVal, so just swap it in.
3033 Subobj.swap(NewVal);
3034 return true;
3035 }
3036 bool found(APSInt &Value, QualType SubobjType) {
3037 if (!checkConst(SubobjType))
3038 return false;
3039 if (!NewVal.isInt()) {
3040 // Maybe trying to write a cast pointer value into a complex?
3041 Info.FFDiag(E);
3042 return false;
3043 }
3044 Value = NewVal.getInt();
3045 return true;
3046 }
3047 bool found(APFloat &Value, QualType SubobjType) {
3048 if (!checkConst(SubobjType))
3049 return false;
3050 Value = NewVal.getFloat();
3051 return true;
3052 }
3053 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3054 llvm_unreachable("shouldn't encounter string elements with ExpandArrays")::llvm::llvm_unreachable_internal("shouldn't encounter string elements with ExpandArrays"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3054)
;
3055 }
3056};
3057} // end anonymous namespace
3058
3059const AccessKinds ModifySubobjectHandler::AccessKind;
3060
3061/// Update the designated sub-object of an rvalue to the given value.
3062static bool modifySubobject(EvalInfo &Info, const Expr *E,
3063 const CompleteObject &Obj,
3064 const SubobjectDesignator &Sub,
3065 APValue &NewVal) {
3066 ModifySubobjectHandler Handler = { Info, NewVal, E };
3067 return findSubobject(Info, E, Obj, Sub, Handler);
3068}
3069
3070/// Find the position where two subobject designators diverge, or equivalently
3071/// the length of the common initial subsequence.
3072static unsigned FindDesignatorMismatch(QualType ObjType,
3073 const SubobjectDesignator &A,
3074 const SubobjectDesignator &B,
3075 bool &WasArrayIndex) {
3076 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3077 for (/**/; I != N; ++I) {
3078 if (!ObjType.isNull() &&
3079 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3080 // Next subobject is an array element.
3081 if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) {
3082 WasArrayIndex = true;
3083 return I;
3084 }
3085 if (ObjType->isAnyComplexType())
3086 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3087 else
3088 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3089 } else {
3090 if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) {
3091 WasArrayIndex = false;
3092 return I;
3093 }
3094 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3095 // Next subobject is a field.
3096 ObjType = FD->getType();
3097 else
3098 // Next subobject is a base class.
3099 ObjType = QualType();
3100 }
3101 }
3102 WasArrayIndex = false;
3103 return I;
3104}
3105
3106/// Determine whether the given subobject designators refer to elements of the
3107/// same array object.
3108static bool AreElementsOfSameArray(QualType ObjType,
3109 const SubobjectDesignator &A,
3110 const SubobjectDesignator &B) {
3111 if (A.Entries.size() != B.Entries.size())
3112 return false;
3113
3114 bool IsArray = A.MostDerivedIsArrayElement;
3115 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3116 // A is a subobject of the array element.
3117 return false;
3118
3119 // If A (and B) designates an array element, the last entry will be the array
3120 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3121 // of length 1' case, and the entire path must match.
3122 bool WasArrayIndex;
3123 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3124 return CommonLength >= A.Entries.size() - IsArray;
3125}
3126
3127/// Find the complete object to which an LValue refers.
3128static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3129 AccessKinds AK, const LValue &LVal,
3130 QualType LValType) {
3131 if (!LVal.Base) {
3132 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3133 return CompleteObject();
3134 }
3135
3136 CallStackFrame *Frame = nullptr;
3137 if (LVal.getLValueCallIndex()) {
3138 Frame = Info.getCallFrame(LVal.getLValueCallIndex());
3139 if (!Frame) {
3140 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3141 << AK << LVal.Base.is<const ValueDecl*>();
3142 NoteLValueLocation(Info, LVal.Base);
3143 return CompleteObject();
3144 }
3145 }
3146
3147 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3148 // is not a constant expression (even if the object is non-volatile). We also
3149 // apply this rule to C++98, in order to conform to the expected 'volatile'
3150 // semantics.
3151 if (LValType.isVolatileQualified()) {
3152 if (Info.getLangOpts().CPlusPlus)
3153 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3154 << AK << LValType;
3155 else
3156 Info.FFDiag(E);
3157 return CompleteObject();
3158 }
3159
3160 // Compute value storage location and type of base object.
3161 APValue *BaseVal = nullptr;
3162 QualType BaseType = getType(LVal.Base);
3163 bool LifetimeStartedInEvaluation = Frame;
3164
3165 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) {
3166 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
3167 // In C++11, constexpr, non-volatile variables initialized with constant
3168 // expressions are constant expressions too. Inside constexpr functions,
3169 // parameters are constant expressions even if they're non-const.
3170 // In C++1y, objects local to a constant expression (those with a Frame) are
3171 // both readable and writable inside constant expressions.
3172 // In C, such things can also be folded, although they are not ICEs.
3173 const VarDecl *VD = dyn_cast<VarDecl>(D);
3174 if (VD) {
3175 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
3176 VD = VDef;
3177 }
3178 if (!VD || VD->isInvalidDecl()) {
3179 Info.FFDiag(E);
3180 return CompleteObject();
3181 }
3182
3183 // Accesses of volatile-qualified objects are not allowed.
3184 if (BaseType.isVolatileQualified()) {
3185 if (Info.getLangOpts().CPlusPlus) {
3186 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3187 << AK << 1 << VD;
3188 Info.Note(VD->getLocation(), diag::note_declared_at);
3189 } else {
3190 Info.FFDiag(E);
3191 }
3192 return CompleteObject();
3193 }
3194
3195 // Unless we're looking at a local variable or argument in a constexpr call,
3196 // the variable we're reading must be const.
3197 if (!Frame) {
3198 if (Info.getLangOpts().CPlusPlus14 &&
3199 VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) {
3200 // OK, we can read and modify an object if we're in the process of
3201 // evaluating its initializer, because its lifetime began in this
3202 // evaluation.
3203 } else if (AK != AK_Read) {
3204 // All the remaining cases only permit reading.
3205 Info.FFDiag(E, diag::note_constexpr_modify_global);
3206 return CompleteObject();
3207 } else if (VD->isConstexpr()) {
3208 // OK, we can read this variable.
3209 } else if (BaseType->isIntegralOrEnumerationType()) {
3210 // In OpenCL if a variable is in constant address space it is a const value.
3211 if (!(BaseType.isConstQualified() ||
3212 (Info.getLangOpts().OpenCL &&
3213 BaseType.getAddressSpace() == LangAS::opencl_constant))) {
3214 if (Info.getLangOpts().CPlusPlus) {
3215 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
3216 Info.Note(VD->getLocation(), diag::note_declared_at);
3217 } else {
3218 Info.FFDiag(E);
3219 }
3220 return CompleteObject();
3221 }
3222 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) {
3223 // We support folding of const floating-point types, in order to make
3224 // static const data members of such types (supported as an extension)
3225 // more useful.
3226 if (Info.getLangOpts().CPlusPlus11) {
3227 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3228 Info.Note(VD->getLocation(), diag::note_declared_at);
3229 } else {
3230 Info.CCEDiag(E);
3231 }
3232 } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
3233 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
3234 // Keep evaluating to see what we can do.
3235 } else {
3236 // FIXME: Allow folding of values of any literal type in all languages.
3237 if (Info.checkingPotentialConstantExpression() &&
3238 VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) {
3239 // The definition of this variable could be constexpr. We can't
3240 // access it right now, but may be able to in future.
3241 } else if (Info.getLangOpts().CPlusPlus11) {
3242 Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3243 Info.Note(VD->getLocation(), diag::note_declared_at);
3244 } else {
3245 Info.FFDiag(E);
3246 }
3247 return CompleteObject();
3248 }
3249 }
3250
3251 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal))
3252 return CompleteObject();
3253 } else {
3254 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3255
3256 if (!Frame) {
3257 if (const MaterializeTemporaryExpr *MTE =
3258 dyn_cast<MaterializeTemporaryExpr>(Base)) {
3259 assert(MTE->getStorageDuration() == SD_Static &&((MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"
) ? static_cast<void> (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3260, __PRETTY_FUNCTION__))
3260 "should have a frame for a non-global materialized temporary")((MTE->getStorageDuration() == SD_Static && "should have a frame for a non-global materialized temporary"
) ? static_cast<void> (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3260, __PRETTY_FUNCTION__))
;
3261
3262 // Per C++1y [expr.const]p2:
3263 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
3264 // - a [...] glvalue of integral or enumeration type that refers to
3265 // a non-volatile const object [...]
3266 // [...]
3267 // - a [...] glvalue of literal type that refers to a non-volatile
3268 // object whose lifetime began within the evaluation of e.
3269 //
3270 // C++11 misses the 'began within the evaluation of e' check and
3271 // instead allows all temporaries, including things like:
3272 // int &&r = 1;
3273 // int x = ++r;
3274 // constexpr int k = r;
3275 // Therefore we use the C++14 rules in C++11 too.
3276 const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
3277 const ValueDecl *ED = MTE->getExtendingDecl();
3278 if (!(BaseType.isConstQualified() &&
3279 BaseType->isIntegralOrEnumerationType()) &&
3280 !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) {
3281 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
3282 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
3283 return CompleteObject();
3284 }
3285
3286 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
3287 assert(BaseVal && "got reference to unevaluated temporary")((BaseVal && "got reference to unevaluated temporary"
) ? static_cast<void> (0) : __assert_fail ("BaseVal && \"got reference to unevaluated temporary\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3287, __PRETTY_FUNCTION__))
;
3288 LifetimeStartedInEvaluation = true;
3289 } else {
3290 Info.FFDiag(E);
3291 return CompleteObject();
3292 }
3293 } else {
3294 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
3295 assert(BaseVal && "missing value for temporary")((BaseVal && "missing value for temporary") ? static_cast
<void> (0) : __assert_fail ("BaseVal && \"missing value for temporary\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3295, __PRETTY_FUNCTION__))
;
3296 }
3297
3298 // Volatile temporary objects cannot be accessed in constant expressions.
3299 if (BaseType.isVolatileQualified()) {
3300 if (Info.getLangOpts().CPlusPlus) {
3301 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3302 << AK << 0;
3303 Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here);
3304 } else {
3305 Info.FFDiag(E);
3306 }
3307 return CompleteObject();
3308 }
3309 }
3310
3311 // During the construction of an object, it is not yet 'const'.
3312 // FIXME: This doesn't do quite the right thing for const subobjects of the
3313 // object under construction.
3314 if (Info.isEvaluatingConstructor(LVal.getLValueBase(),
3315 LVal.getLValueCallIndex(),
3316 LVal.getLValueVersion())) {
3317 BaseType = Info.Ctx.getCanonicalType(BaseType);
3318 BaseType.removeLocalConst();
3319 LifetimeStartedInEvaluation = true;
3320 }
3321
3322 // In C++14, we can't safely access any mutable state when we might be
3323 // evaluating after an unmodeled side effect.
3324 //
3325 // FIXME: Not all local state is mutable. Allow local constant subobjects
3326 // to be read here (but take care with 'mutable' fields).
3327 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
3328 Info.EvalStatus.HasSideEffects) ||
3329 (AK != AK_Read && Info.IsSpeculativelyEvaluating))
3330 return CompleteObject();
3331
3332 return CompleteObject(BaseVal, BaseType, LifetimeStartedInEvaluation);
3333}
3334
3335/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
3336/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
3337/// glvalue referred to by an entity of reference type.
3338///
3339/// \param Info - Information about the ongoing evaluation.
3340/// \param Conv - The expression for which we are performing the conversion.
3341/// Used for diagnostics.
3342/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
3343/// case of a non-class type).
3344/// \param LVal - The glvalue on which we are attempting to perform this action.
3345/// \param RVal - The produced value will be placed here.
3346static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
3347 QualType Type,
3348 const LValue &LVal, APValue &RVal) {
3349 if (LVal.Designator.Invalid)
3350 return false;
3351
3352 // Check for special cases where there is no existing APValue to look at.
3353 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3354 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
3355 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
3356 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
3357 // initializer until now for such expressions. Such an expression can't be
3358 // an ICE in C, so this only matters for fold.
3359 if (Type.isVolatileQualified()) {
3360 Info.FFDiag(Conv);
3361 return false;
3362 }
3363 APValue Lit;
3364 if (!Evaluate(Lit, Info, CLE->getInitializer()))
3365 return false;
3366 CompleteObject LitObj(&Lit, Base->getType(), false);
3367 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal);
3368 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
3369 // We represent a string literal array as an lvalue pointing at the
3370 // corresponding expression, rather than building an array of chars.
3371 // FIXME: Support ObjCEncodeExpr, MakeStringConstant
3372 APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0);
3373 CompleteObject StrObj(&Str, Base->getType(), false);
3374 return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal);
3375 }
3376 }
3377
3378 CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type);
3379 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal);
3380}
3381
3382/// Perform an assignment of Val to LVal. Takes ownership of Val.
3383static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
3384 QualType LValType, APValue &Val) {
3385 if (LVal.Designator.Invalid)
3386 return false;
3387
3388 if (!Info.getLangOpts().CPlusPlus14) {
3389 Info.FFDiag(E);
3390 return false;
3391 }
3392
3393 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3394 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
3395}
3396
3397namespace {
3398struct CompoundAssignSubobjectHandler {
3399 EvalInfo &Info;
3400 const Expr *E;
3401 QualType PromotedLHSType;
3402 BinaryOperatorKind Opcode;
3403 const APValue &RHS;
3404
3405 static const AccessKinds AccessKind = AK_Assign;
3406
3407 typedef bool result_type;
3408
3409 bool checkConst(QualType QT) {
3410 // Assigning to a const object has undefined behavior.
3411 if (QT.isConstQualified()) {
3412 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3413 return false;
3414 }
3415 return true;
3416 }
3417
3418 bool failed() { return false; }
3419 bool found(APValue &Subobj, QualType SubobjType) {
3420 switch (Subobj.getKind()) {
3421 case APValue::Int:
3422 return found(Subobj.getInt(), SubobjType);
3423 case APValue::Float:
3424 return found(Subobj.getFloat(), SubobjType);
3425 case APValue::ComplexInt:
3426 case APValue::ComplexFloat:
3427 // FIXME: Implement complex compound assignment.
3428 Info.FFDiag(E);
3429 return false;
3430 case APValue::LValue:
3431 return foundPointer(Subobj, SubobjType);
3432 default:
3433 // FIXME: can this happen?
3434 Info.FFDiag(E);
3435 return false;
3436 }
3437 }
3438 bool found(APSInt &Value, QualType SubobjType) {
3439 if (!checkConst(SubobjType))
3440 return false;
3441
3442 if (!SubobjType->isIntegerType()) {
3443 // We don't support compound assignment on integer-cast-to-pointer
3444 // values.
3445 Info.FFDiag(E);
3446 return false;
3447 }
3448
3449 if (RHS.isInt()) {
3450 APSInt LHS =
3451 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
3452 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
3453 return false;
3454 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
3455 return true;
3456 } else if (RHS.isFloat()) {
3457 APFloat FValue(0.0);
3458 return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType,
3459 FValue) &&
3460 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
3461 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
3462 Value);
3463 }
3464
3465 Info.FFDiag(E);
3466 return false;
3467 }
3468 bool found(APFloat &Value, QualType SubobjType) {
3469 return checkConst(SubobjType) &&
3470 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
3471 Value) &&
3472 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
3473 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
3474 }
3475 bool foundPointer(APValue &Subobj, QualType SubobjType) {
3476 if (!checkConst(SubobjType))
3477 return false;
3478
3479 QualType PointeeType;
3480 if (const PointerType *PT = SubobjType->getAs<PointerType>())
3481 PointeeType = PT->getPointeeType();
3482
3483 if (PointeeType.isNull() || !RHS.isInt() ||
3484 (Opcode != BO_Add && Opcode != BO_Sub)) {
3485 Info.FFDiag(E);
3486 return false;
3487 }
3488
3489 APSInt Offset = RHS.getInt();
3490 if (Opcode == BO_Sub)
3491 negateAsSigned(Offset);
3492
3493 LValue LVal;
3494 LVal.setFrom(Info.Ctx, Subobj);
3495 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
3496 return false;
3497 LVal.moveInto(Subobj);
3498 return true;
3499 }
3500 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3501 llvm_unreachable("shouldn't encounter string elements here")::llvm::llvm_unreachable_internal("shouldn't encounter string elements here"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3501)
;
3502 }
3503};
3504} // end anonymous namespace
3505
3506const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
3507
3508/// Perform a compound assignment of LVal <op>= RVal.
3509static bool handleCompoundAssignment(
3510 EvalInfo &Info, const Expr *E,
3511 const LValue &LVal, QualType LValType, QualType PromotedLValType,
3512 BinaryOperatorKind Opcode, const APValue &RVal) {
3513 if (LVal.Designator.Invalid)
3514 return false;
3515
3516 if (!Info.getLangOpts().CPlusPlus14) {
3517 Info.FFDiag(E);
3518 return false;
3519 }
3520
3521 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3522 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
3523 RVal };
3524 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3525}
3526
3527namespace {
3528struct IncDecSubobjectHandler {
3529 EvalInfo &Info;
3530 const UnaryOperator *E;
3531 AccessKinds AccessKind;
3532 APValue *Old;
3533
3534 typedef bool result_type;
3535
3536 bool checkConst(QualType QT) {
3537 // Assigning to a const object has undefined behavior.
3538 if (QT.isConstQualified()) {
3539 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3540 return false;
3541 }
3542 return true;
3543 }
3544
3545 bool failed() { return false; }
3546 bool found(APValue &Subobj, QualType SubobjType) {
3547 // Stash the old value. Also clear Old, so we don't clobber it later
3548 // if we're post-incrementing a complex.
3549 if (Old) {
3550 *Old = Subobj;
3551 Old = nullptr;
3552 }
3553
3554 switch (Subobj.getKind()) {
3555 case APValue::Int:
3556 return found(Subobj.getInt(), SubobjType);
3557 case APValue::Float:
3558 return found(Subobj.getFloat(), SubobjType);
3559 case APValue::ComplexInt:
3560 return found(Subobj.getComplexIntReal(),
3561 SubobjType->castAs<ComplexType>()->getElementType()
3562 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3563 case APValue::ComplexFloat:
3564 return found(Subobj.getComplexFloatReal(),
3565 SubobjType->castAs<ComplexType>()->getElementType()
3566 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3567 case APValue::LValue:
3568 return foundPointer(Subobj, SubobjType);
3569 default:
3570 // FIXME: can this happen?
3571 Info.FFDiag(E);
3572 return false;
3573 }
3574 }
3575 bool found(APSInt &Value, QualType SubobjType) {
3576 if (!checkConst(SubobjType))
3577 return false;
3578
3579 if (!SubobjType->isIntegerType()) {
3580 // We don't support increment / decrement on integer-cast-to-pointer
3581 // values.
3582 Info.FFDiag(E);
3583 return false;
3584 }
3585
3586 if (Old) *Old = APValue(Value);
3587
3588 // bool arithmetic promotes to int, and the conversion back to bool
3589 // doesn't reduce mod 2^n, so special-case it.
3590 if (SubobjType->isBooleanType()) {
3591 if (AccessKind == AK_Increment)
3592 Value = 1;
3593 else
3594 Value = !Value;
3595 return true;
3596 }
3597
3598 bool WasNegative = Value.isNegative();
3599 if (AccessKind == AK_Increment) {
3600 ++Value;
3601
3602 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
3603 APSInt ActualValue(Value, /*IsUnsigned*/true);
3604 return HandleOverflow(Info, E, ActualValue, SubobjType);
3605 }
3606 } else {
3607 --Value;
3608
3609 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
3610 unsigned BitWidth = Value.getBitWidth();
3611 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
3612 ActualValue.setBit(BitWidth);
3613 return HandleOverflow(Info, E, ActualValue, SubobjType);
3614 }
3615 }
3616 return true;
3617 }
3618 bool found(APFloat &Value, QualType SubobjType) {
3619 if (!checkConst(SubobjType))
3620 return false;
3621
3622 if (Old) *Old = APValue(Value);
3623
3624 APFloat One(Value.getSemantics(), 1);
3625 if (AccessKind == AK_Increment)
3626 Value.add(One, APFloat::rmNearestTiesToEven);
3627 else
3628 Value.subtract(One, APFloat::rmNearestTiesToEven);
3629 return true;
3630 }
3631 bool foundPointer(APValue &Subobj, QualType SubobjType) {
3632 if (!checkConst(SubobjType))
3633 return false;
3634
3635 QualType PointeeType;
3636 if (const PointerType *PT = SubobjType->getAs<PointerType>())
3637 PointeeType = PT->getPointeeType();
3638 else {
3639 Info.FFDiag(E);
3640 return false;
3641 }
3642
3643 LValue LVal;
3644 LVal.setFrom(Info.Ctx, Subobj);
3645 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
3646 AccessKind == AK_Increment ? 1 : -1))
3647 return false;
3648 LVal.moveInto(Subobj);
3649 return true;
3650 }
3651 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3652 llvm_unreachable("shouldn't encounter string elements here")::llvm::llvm_unreachable_internal("shouldn't encounter string elements here"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3652)
;
3653 }
3654};
3655} // end anonymous namespace
3656
3657/// Perform an increment or decrement on LVal.
3658static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
3659 QualType LValType, bool IsIncrement, APValue *Old) {
3660 if (LVal.Designator.Invalid)
3661 return false;
3662
3663 if (!Info.getLangOpts().CPlusPlus14) {
3664 Info.FFDiag(E);
3665 return false;
3666 }
3667
3668 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
3669 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
3670 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
3671 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3672}
3673
3674/// Build an lvalue for the object argument of a member function call.
3675static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
3676 LValue &This) {
3677 if (Object->getType()->isPointerType())
3678 return EvaluatePointer(Object, This, Info);
3679
3680 if (Object->isGLValue())
3681 return EvaluateLValue(Object, This, Info);
3682
3683 if (Object->getType()->isLiteralType(Info.Ctx))
3684 return EvaluateTemporary(Object, This, Info);
3685
3686 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
3687 return false;
3688}
3689
3690/// HandleMemberPointerAccess - Evaluate a member access operation and build an
3691/// lvalue referring to the result.
3692///
3693/// \param Info - Information about the ongoing evaluation.
3694/// \param LV - An lvalue referring to the base of the member pointer.
3695/// \param RHS - The member pointer expression.
3696/// \param IncludeMember - Specifies whether the member itself is included in
3697/// the resulting LValue subobject designator. This is not possible when
3698/// creating a bound member function.
3699/// \return The field or method declaration to which the member pointer refers,
3700/// or 0 if evaluation fails.
3701static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3702 QualType LVType,
3703 LValue &LV,
3704 const Expr *RHS,
3705 bool IncludeMember = true) {
3706 MemberPtr MemPtr;
3707 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
3708 return nullptr;
3709
3710 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
3711 // member value, the behavior is undefined.
3712 if (!MemPtr.getDecl()) {
3713 // FIXME: Specific diagnostic.
3714 Info.FFDiag(RHS);
3715 return nullptr;
3716 }
3717
3718 if (MemPtr.isDerivedMember()) {
3719 // This is a member of some derived class. Truncate LV appropriately.
3720 // The end of the derived-to-base path for the base object must match the
3721 // derived-to-base path for the member pointer.
3722 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
3723 LV.Designator.Entries.size()) {
3724 Info.FFDiag(RHS);
3725 return nullptr;
3726 }
3727 unsigned PathLengthToMember =
3728 LV.Designator.Entries.size() - MemPtr.Path.size();
3729 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
3730 const CXXRecordDecl *LVDecl = getAsBaseClass(
3731 LV.Designator.Entries[PathLengthToMember + I]);
3732 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
3733 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
3734 Info.FFDiag(RHS);
3735 return nullptr;
3736 }
3737 }
3738
3739 // Truncate the lvalue to the appropriate derived class.
3740 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
3741 PathLengthToMember))
3742 return nullptr;
3743 } else if (!MemPtr.Path.empty()) {
3744 // Extend the LValue path with the member pointer's path.
3745 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
3746 MemPtr.Path.size() + IncludeMember);
3747
3748 // Walk down to the appropriate base class.
3749 if (const PointerType *PT = LVType->getAs<PointerType>())
3750 LVType = PT->getPointeeType();
3751 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
3752 assert(RD && "member pointer access on non-class-type expression")((RD && "member pointer access on non-class-type expression"
) ? static_cast<void> (0) : __assert_fail ("RD && \"member pointer access on non-class-type expression\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3752, __PRETTY_FUNCTION__))
;
3753 // The first class in the path is that of the lvalue.
3754 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
3755 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
3756 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
3757 return nullptr;
3758 RD = Base;
3759 }
3760 // Finally cast to the class containing the member.
3761 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
3762 MemPtr.getContainingRecord()))
3763 return nullptr;
3764 }
3765
3766 // Add the member. Note that we cannot build bound member functions here.
3767 if (IncludeMember) {
3768 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
3769 if (!HandleLValueMember(Info, RHS, LV, FD))
3770 return nullptr;
3771 } else if (const IndirectFieldDecl *IFD =
3772 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
3773 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
3774 return nullptr;
3775 } else {
3776 llvm_unreachable("can't construct reference to bound member function")::llvm::llvm_unreachable_internal("can't construct reference to bound member function"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3776)
;
3777 }
3778 }
3779
3780 return MemPtr.getDecl();
3781}
3782
3783static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3784 const BinaryOperator *BO,
3785 LValue &LV,
3786 bool IncludeMember = true) {
3787 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI)((BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI
) ? static_cast<void> (0) : __assert_fail ("BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3787, __PRETTY_FUNCTION__))
;
3788
3789 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
3790 if (Info.noteFailure()) {
3791 MemberPtr MemPtr;
3792 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
3793 }
3794 return nullptr;
3795 }
3796
3797 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
3798 BO->getRHS(), IncludeMember);
3799}
3800
3801/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
3802/// the provided lvalue, which currently refers to the base object.
3803static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
3804 LValue &Result) {
3805 SubobjectDesignator &D = Result.Designator;
3806 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
3807 return false;
3808
3809 QualType TargetQT = E->getType();
3810 if (const PointerType *PT = TargetQT->getAs<PointerType>())
3811 TargetQT = PT->getPointeeType();
3812
3813 // Check this cast lands within the final derived-to-base subobject path.
3814 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
3815 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3816 << D.MostDerivedType << TargetQT;
3817 return false;
3818 }
3819
3820 // Check the type of the final cast. We don't need to check the path,
3821 // since a cast can only be formed if the path is unique.
3822 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
3823 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
3824 const CXXRecordDecl *FinalType;
3825 if (NewEntriesSize == D.MostDerivedPathLength)
3826 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
3827 else
3828 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
3829 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
3830 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3831 << D.MostDerivedType << TargetQT;
3832 return false;
3833 }
3834
3835 // Truncate the lvalue to the appropriate derived class.
3836 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
3837}
3838
3839namespace {
3840enum EvalStmtResult {
3841 /// Evaluation failed.
3842 ESR_Failed,
3843 /// Hit a 'return' statement.
3844 ESR_Returned,
3845 /// Evaluation succeeded.
3846 ESR_Succeeded,
3847 /// Hit a 'continue' statement.
3848 ESR_Continue,
3849 /// Hit a 'break' statement.
3850 ESR_Break,
3851 /// Still scanning for 'case' or 'default' statement.
3852 ESR_CaseNotFound
3853};
3854}
3855
3856static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
3857 // We don't need to evaluate the initializer for a static local.
3858 if (!VD->hasLocalStorage())
3859 return true;
3860
3861 LValue Result;
3862 APValue &Val = createTemporary(VD, true, Result, *Info.CurrentCall);
3863
3864 const Expr *InitE = VD->getInit();
3865 if (!InitE) {
3866 Info.FFDiag(VD->getBeginLoc(), diag::note_constexpr_uninitialized)
3867 << false << VD->getType();
3868 Val = APValue();
3869 return false;
3870 }
3871
3872 if (InitE->isValueDependent())
3873 return false;
3874
3875 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
3876 // Wipe out any partially-computed value, to allow tracking that this
3877 // evaluation failed.
3878 Val = APValue();
3879 return false;
3880 }
3881
3882 return true;
3883}
3884
3885static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
3886 bool OK = true;
3887
3888 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
3889 OK &= EvaluateVarDecl(Info, VD);
3890
3891 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
3892 for (auto *BD : DD->bindings())
3893 if (auto *VD = BD->getHoldingVar())
3894 OK &= EvaluateDecl(Info, VD);
3895
3896 return OK;
3897}
3898
3899
3900/// Evaluate a condition (either a variable declaration or an expression).
3901static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
3902 const Expr *Cond, bool &Result) {
3903 FullExpressionRAII Scope(Info);
3904 if (CondDecl && !EvaluateDecl(Info, CondDecl))
3905 return false;
3906 return EvaluateAsBooleanCondition(Cond, Result, Info);
3907}
3908
3909namespace {
3910/// A location where the result (returned value) of evaluating a
3911/// statement should be stored.
3912struct StmtResult {
3913 /// The APValue that should be filled in with the returned value.
3914 APValue &Value;
3915 /// The location containing the result, if any (used to support RVO).
3916 const LValue *Slot;
3917};
3918
3919struct TempVersionRAII {
3920 CallStackFrame &Frame;
3921
3922 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
3923 Frame.pushTempVersion();
3924 }
3925
3926 ~TempVersionRAII() {
3927 Frame.popTempVersion();
3928 }
3929};
3930
3931}
3932
3933static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
3934 const Stmt *S,
3935 const SwitchCase *SC = nullptr);
3936
3937/// Evaluate the body of a loop, and translate the result as appropriate.
3938static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
3939 const Stmt *Body,
3940 const SwitchCase *Case = nullptr) {
3941 BlockScopeRAII Scope(Info);
3942 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) {
3943 case ESR_Break:
3944 return ESR_Succeeded;
3945 case ESR_Succeeded:
3946 case ESR_Continue:
3947 return ESR_Continue;
3948 case ESR_Failed:
3949 case ESR_Returned:
3950 case ESR_CaseNotFound:
3951 return ESR;
3952 }
3953 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 3953)
;
3954}
3955
3956/// Evaluate a switch statement.
3957static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
3958 const SwitchStmt *SS) {
3959 BlockScopeRAII Scope(Info);
3960
3961 // Evaluate the switch condition.
3962 APSInt Value;
3963 {
3964 FullExpressionRAII Scope(Info);
3965 if (const Stmt *Init = SS->getInit()) {
3966 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
3967 if (ESR != ESR_Succeeded)
3968 return ESR;
3969 }
3970 if (SS->getConditionVariable() &&
3971 !EvaluateDecl(Info, SS->getConditionVariable()))
3972 return ESR_Failed;
3973 if (!EvaluateInteger(SS->getCond(), Value, Info))
3974 return ESR_Failed;
3975 }
3976
3977 // Find the switch case corresponding to the value of the condition.
3978 // FIXME: Cache this lookup.
3979 const SwitchCase *Found = nullptr;
3980 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
3981 SC = SC->getNextSwitchCase()) {
3982 if (isa<DefaultStmt>(SC)) {
3983 Found = SC;
3984 continue;
3985 }
3986
3987 const CaseStmt *CS = cast<CaseStmt>(SC);
3988 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
3989 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
3990 : LHS;
3991 if (LHS <= Value && Value <= RHS) {
3992 Found = SC;
3993 break;
3994 }
3995 }
3996
3997 if (!Found)
3998 return ESR_Succeeded;
3999
4000 // Search the switch body for the switch case and evaluate it from there.
4001 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) {
4002 case ESR_Break:
4003 return ESR_Succeeded;
4004 case ESR_Succeeded:
4005 case ESR_Continue:
4006 case ESR_Failed:
4007 case ESR_Returned:
4008 return ESR;
4009 case ESR_CaseNotFound:
4010 // This can only happen if the switch case is nested within a statement
4011 // expression. We have no intention of supporting that.
4012 Info.FFDiag(Found->getBeginLoc(),
4013 diag::note_constexpr_stmt_expr_unsupported);
4014 return ESR_Failed;
4015 }
4016 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4016)
;
4017}
4018
4019// Evaluate a statement.
4020static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4021 const Stmt *S, const SwitchCase *Case) {
4022 if (!Info.nextStep(S))
4023 return ESR_Failed;
4024
4025 // If we're hunting down a 'case' or 'default' label, recurse through
4026 // substatements until we hit the label.
4027 if (Case) {
4028 // FIXME: We don't start the lifetime of objects whose initialization we
4029 // jump over. However, such objects must be of class type with a trivial
4030 // default constructor that initialize all subobjects, so must be empty,
4031 // so this almost never matters.
4032 switch (S->getStmtClass()) {
4033 case Stmt::CompoundStmtClass:
4034 // FIXME: Precompute which substatement of a compound statement we
4035 // would jump to, and go straight there rather than performing a
4036 // linear scan each time.
4037 case Stmt::LabelStmtClass:
4038 case Stmt::AttributedStmtClass:
4039 case Stmt::DoStmtClass:
4040 break;
4041
4042 case Stmt::CaseStmtClass:
4043 case Stmt::DefaultStmtClass:
4044 if (Case == S)
4045 Case = nullptr;
4046 break;
4047
4048 case Stmt::IfStmtClass: {
4049 // FIXME: Precompute which side of an 'if' we would jump to, and go
4050 // straight there rather than scanning both sides.
4051 const IfStmt *IS = cast<IfStmt>(S);
4052
4053 // Wrap the evaluation in a block scope, in case it's a DeclStmt
4054 // preceded by our switch label.
4055 BlockScopeRAII Scope(Info);
4056
4057 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
4058 if (ESR != ESR_CaseNotFound || !IS->getElse())
4059 return ESR;
4060 return EvaluateStmt(Result, Info, IS->getElse(), Case);
4061 }
4062
4063 case Stmt::WhileStmtClass: {
4064 EvalStmtResult ESR =
4065 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
4066 if (ESR != ESR_Continue)
4067 return ESR;
4068 break;
4069 }
4070
4071 case Stmt::ForStmtClass: {
4072 const ForStmt *FS = cast<ForStmt>(S);
4073 EvalStmtResult ESR =
4074 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
4075 if (ESR != ESR_Continue)
4076 return ESR;
4077 if (FS->getInc()) {
4078 FullExpressionRAII IncScope(Info);
4079 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4080 return ESR_Failed;
4081 }
4082 break;
4083 }
4084
4085 case Stmt::DeclStmtClass:
4086 // FIXME: If the variable has initialization that can't be jumped over,
4087 // bail out of any immediately-surrounding compound-statement too.
4088 default:
4089 return ESR_CaseNotFound;
4090 }
4091 }
4092
4093 switch (S->getStmtClass()) {
4094 default:
4095 if (const Expr *E = dyn_cast<Expr>(S)) {
4096 // Don't bother evaluating beyond an expression-statement which couldn't
4097 // be evaluated.
4098 FullExpressionRAII Scope(Info);
4099 if (!EvaluateIgnoredValue(Info, E))
4100 return ESR_Failed;
4101 return ESR_Succeeded;
4102 }
4103
4104 Info.FFDiag(S->getBeginLoc());
4105 return ESR_Failed;
4106
4107 case Stmt::NullStmtClass:
4108 return ESR_Succeeded;
4109
4110 case Stmt::DeclStmtClass: {
4111 const DeclStmt *DS = cast<DeclStmt>(S);
4112 for (const auto *DclIt : DS->decls()) {
4113 // Each declaration initialization is its own full-expression.
4114 // FIXME: This isn't quite right; if we're performing aggregate
4115 // initialization, each braced subexpression is its own full-expression.
4116 FullExpressionRAII Scope(Info);
4117 if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure())
4118 return ESR_Failed;
4119 }
4120 return ESR_Succeeded;
4121 }
4122
4123 case Stmt::ReturnStmtClass: {
4124 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
4125 FullExpressionRAII Scope(Info);
4126 if (RetExpr &&
4127 !(Result.Slot
4128 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
4129 : Evaluate(Result.Value, Info, RetExpr)))
4130 return ESR_Failed;
4131 return ESR_Returned;
4132 }
4133
4134 case Stmt::CompoundStmtClass: {
4135 BlockScopeRAII Scope(Info);
4136
4137 const CompoundStmt *CS = cast<CompoundStmt>(S);
4138 for (const auto *BI : CS->body()) {
4139 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
4140 if (ESR == ESR_Succeeded)
4141 Case = nullptr;
4142 else if (ESR != ESR_CaseNotFound)
4143 return ESR;
4144 }
4145 return Case ? ESR_CaseNotFound : ESR_Succeeded;
4146 }
4147
4148 case Stmt::IfStmtClass: {
4149 const IfStmt *IS = cast<IfStmt>(S);
4150
4151 // Evaluate the condition, as either a var decl or as an expression.
4152 BlockScopeRAII Scope(Info);
4153 if (const Stmt *Init = IS->getInit()) {
4154 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4155 if (ESR != ESR_Succeeded)
4156 return ESR;
4157 }
4158 bool Cond;
4159 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
4160 return ESR_Failed;
4161
4162 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
4163 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
4164 if (ESR != ESR_Succeeded)
4165 return ESR;
4166 }
4167 return ESR_Succeeded;
4168 }
4169
4170 case Stmt::WhileStmtClass: {
4171 const WhileStmt *WS = cast<WhileStmt>(S);
4172 while (true) {
4173 BlockScopeRAII Scope(Info);
4174 bool Continue;
4175 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
4176 Continue))
4177 return ESR_Failed;
4178 if (!Continue)
4179 break;
4180
4181 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
4182 if (ESR != ESR_Continue)
4183 return ESR;
4184 }
4185 return ESR_Succeeded;
4186 }
4187
4188 case Stmt::DoStmtClass: {
4189 const DoStmt *DS = cast<DoStmt>(S);
4190 bool Continue;
4191 do {
4192 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
4193 if (ESR != ESR_Continue)
4194 return ESR;
4195 Case = nullptr;
4196
4197 FullExpressionRAII CondScope(Info);
4198 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info))
4199 return ESR_Failed;
4200 } while (Continue);
4201 return ESR_Succeeded;
4202 }
4203
4204 case Stmt::ForStmtClass: {
4205 const ForStmt *FS = cast<ForStmt>(S);
4206 BlockScopeRAII Scope(Info);
4207 if (FS->getInit()) {
4208 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4209 if (ESR != ESR_Succeeded)
4210 return ESR;
4211 }
4212 while (true) {
4213 BlockScopeRAII Scope(Info);
4214 bool Continue = true;
4215 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
4216 FS->getCond(), Continue))
4217 return ESR_Failed;
4218 if (!Continue)
4219 break;
4220
4221 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4222 if (ESR != ESR_Continue)
4223 return ESR;
4224
4225 if (FS->getInc()) {
4226 FullExpressionRAII IncScope(Info);
4227 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4228 return ESR_Failed;
4229 }
4230 }
4231 return ESR_Succeeded;
4232 }
4233
4234 case Stmt::CXXForRangeStmtClass: {
4235 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
4236 BlockScopeRAII Scope(Info);
4237
4238 // Evaluate the init-statement if present.
4239 if (FS->getInit()) {
4240 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4241 if (ESR != ESR_Succeeded)
4242 return ESR;
4243 }
4244
4245 // Initialize the __range variable.
4246 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
4247 if (ESR != ESR_Succeeded)
4248 return ESR;
4249
4250 // Create the __begin and __end iterators.
4251 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
4252 if (ESR != ESR_Succeeded)
4253 return ESR;
4254 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
4255 if (ESR != ESR_Succeeded)
4256 return ESR;
4257
4258 while (true) {
4259 // Condition: __begin != __end.
4260 {
4261 bool Continue = true;
4262 FullExpressionRAII CondExpr(Info);
4263 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
4264 return ESR_Failed;
4265 if (!Continue)
4266 break;
4267 }
4268
4269 // User's variable declaration, initialized by *__begin.
4270 BlockScopeRAII InnerScope(Info);
4271 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
4272 if (ESR != ESR_Succeeded)
4273 return ESR;
4274
4275 // Loop body.
4276 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4277 if (ESR != ESR_Continue)
4278 return ESR;
4279
4280 // Increment: ++__begin
4281 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4282 return ESR_Failed;
4283 }
4284
4285 return ESR_Succeeded;
4286 }
4287
4288 case Stmt::SwitchStmtClass:
4289 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
4290
4291 case Stmt::ContinueStmtClass:
4292 return ESR_Continue;
4293
4294 case Stmt::BreakStmtClass:
4295 return ESR_Break;
4296
4297 case Stmt::LabelStmtClass:
4298 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
4299
4300 case Stmt::AttributedStmtClass:
4301 // As a general principle, C++11 attributes can be ignored without
4302 // any semantic impact.
4303 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
4304 Case);
4305
4306 case Stmt::CaseStmtClass:
4307 case Stmt::DefaultStmtClass:
4308 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
4309 case Stmt::CXXTryStmtClass:
4310 // Evaluate try blocks by evaluating all sub statements.
4311 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
4312 }
4313}
4314
4315/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
4316/// default constructor. If so, we'll fold it whether or not it's marked as
4317/// constexpr. If it is marked as constexpr, we will never implicitly define it,
4318/// so we need special handling.
4319static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
4320 const CXXConstructorDecl *CD,
4321 bool IsValueInitialization) {
4322 if (!CD->isTrivial() || !CD->isDefaultConstructor())
4323 return false;
4324
4325 // Value-initialization does not call a trivial default constructor, so such a
4326 // call is a core constant expression whether or not the constructor is
4327 // constexpr.
4328 if (!CD->isConstexpr() && !IsValueInitialization) {
4329 if (Info.getLangOpts().CPlusPlus11) {
4330 // FIXME: If DiagDecl is an implicitly-declared special member function,
4331 // we should be much more explicit about why it's not constexpr.
4332 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
4333 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
4334 Info.Note(CD->getLocation(), diag::note_declared_at);
4335 } else {
4336 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
4337 }
4338 }
4339 return true;
4340}
4341
4342/// CheckConstexprFunction - Check that a function can be called in a constant
4343/// expression.
4344static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
4345 const FunctionDecl *Declaration,
4346 const FunctionDecl *Definition,
4347 const Stmt *Body) {
4348 // Potential constant expressions can contain calls to declared, but not yet
4349 // defined, constexpr functions.
4350 if (Info.checkingPotentialConstantExpression() && !Definition &&
4351 Declaration->isConstexpr())
4352 return false;
4353
4354 // Bail out if the function declaration itself is invalid. We will
4355 // have produced a relevant diagnostic while parsing it, so just
4356 // note the problematic sub-expression.
4357 if (Declaration->isInvalidDecl()) {
4358 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4359 return false;
4360 }
4361
4362 // Can we evaluate this function call?
4363 if (Definition && Definition->isConstexpr() &&
4364 !Definition->isInvalidDecl() && Body)
4365 return true;
4366
4367 if (Info.getLangOpts().CPlusPlus11) {
4368 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
4369
4370 // If this function is not constexpr because it is an inherited
4371 // non-constexpr constructor, diagnose that directly.
4372 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
4373 if (CD && CD->isInheritingConstructor()) {
4374 auto *Inherited = CD->getInheritedConstructor().getConstructor();
4375 if (!Inherited->isConstexpr())
4376 DiagDecl = CD = Inherited;
4377 }
4378
4379 // FIXME: If DiagDecl is an implicitly-declared special member function
4380 // or an inheriting constructor, we should be much more explicit about why
4381 // it's not constexpr.
4382 if (CD && CD->isInheritingConstructor())
4383 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
4384 << CD->getInheritedConstructor().getConstructor()->getParent();
4385 else
4386 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
4387 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
4388 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
4389 } else {
4390 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4391 }
4392 return false;
4393}
4394
4395/// Determine if a class has any fields that might need to be copied by a
4396/// trivial copy or move operation.
4397static bool hasFields(const CXXRecordDecl *RD) {
4398 if (!RD || RD->isEmpty())
4399 return false;
4400 for (auto *FD : RD->fields()) {
4401 if (FD->isUnnamedBitfield())
4402 continue;
4403 return true;
4404 }
4405 for (auto &Base : RD->bases())
4406 if (hasFields(Base.getType()->getAsCXXRecordDecl()))
4407 return true;
4408 return false;
4409}
4410
4411namespace {
4412typedef SmallVector<APValue, 8> ArgVector;
4413}
4414
4415/// EvaluateArgs - Evaluate the arguments to a function call.
4416static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues,
4417 EvalInfo &Info) {
4418 bool Success = true;
4419 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
4420 I != E; ++I) {
4421 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) {
4422 // If we're checking for a potential constant expression, evaluate all
4423 // initializers even if some of them fail.
4424 if (!Info.noteFailure())
4425 return false;
4426 Success = false;
4427 }
4428 }
4429 return Success;
4430}
4431
4432/// Evaluate a function call.
4433static bool HandleFunctionCall(SourceLocation CallLoc,
4434 const FunctionDecl *Callee, const LValue *This,
4435 ArrayRef<const Expr*> Args, const Stmt *Body,
4436 EvalInfo &Info, APValue &Result,
4437 const LValue *ResultSlot) {
4438 ArgVector ArgValues(Args.size());
4439 if (!EvaluateArgs(Args, ArgValues, Info))
4440 return false;
4441
4442 if (!Info.CheckCallLimit(CallLoc))
4443 return false;
4444
4445 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
4446
4447 // For a trivial copy or move assignment, perform an APValue copy. This is
4448 // essential for unions, where the operations performed by the assignment
4449 // operator cannot be represented as statements.
4450 //
4451 // Skip this for non-union classes with no fields; in that case, the defaulted
4452 // copy/move does not actually read the object.
4453 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
4454 if (MD && MD->isDefaulted() &&
4455 (MD->getParent()->isUnion() ||
4456 (MD->isTrivial() && hasFields(MD->getParent())))) {
4457 assert(This &&((This && (MD->isCopyAssignmentOperator() || MD->
isMoveAssignmentOperator())) ? static_cast<void> (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4458, __PRETTY_FUNCTION__))
4458 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()))((This && (MD->isCopyAssignmentOperator() || MD->
isMoveAssignmentOperator())) ? static_cast<void> (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4458, __PRETTY_FUNCTION__))
;
4459 LValue RHS;
4460 RHS.setFrom(Info.Ctx, ArgValues[0]);
4461 APValue RHSValue;
4462 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(),
4463 RHS, RHSValue))
4464 return false;
4465 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx),
4466 RHSValue))
4467 return false;
4468 This->moveInto(Result);
4469 return true;
4470 } else if (MD && isLambdaCallOperator(MD)) {
4471 // We're in a lambda; determine the lambda capture field maps unless we're
4472 // just constexpr checking a lambda's call operator. constexpr checking is
4473 // done before the captures have been added to the closure object (unless
4474 // we're inferring constexpr-ness), so we don't have access to them in this
4475 // case. But since we don't need the captures to constexpr check, we can
4476 // just ignore them.
4477 if (!Info.checkingPotentialConstantExpression())
4478 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
4479 Frame.LambdaThisCaptureField);
4480 }
4481
4482 StmtResult Ret = {Result, ResultSlot};
4483 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
4484 if (ESR == ESR_Succeeded) {
4485 if (Callee->getReturnType()->isVoidType())
4486 return true;
4487 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
4488 }
4489 return ESR == ESR_Returned;
4490}
4491
4492/// Evaluate a constructor call.
4493static bool HandleConstructorCall(const Expr *E, const LValue &This,
4494 APValue *ArgValues,
4495 const CXXConstructorDecl *Definition,
4496 EvalInfo &Info, APValue &Result) {
4497 SourceLocation CallLoc = E->getExprLoc();
4498 if (!Info.CheckCallLimit(CallLoc))
4499 return false;
4500
4501 const CXXRecordDecl *RD = Definition->getParent();
4502 if (RD->getNumVBases()) {
4503 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
4504 return false;
4505 }
4506
4507 EvalInfo::EvaluatingConstructorRAII EvalObj(
4508 Info, {This.getLValueBase(),
4509 {This.getLValueCallIndex(), This.getLValueVersion()}});
4510 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
4511
4512 // FIXME: Creating an APValue just to hold a nonexistent return value is
4513 // wasteful.
4514 APValue RetVal;
4515 StmtResult Ret = {RetVal, nullptr};
4516
4517 // If it's a delegating constructor, delegate.
4518 if (Definition->isDelegatingConstructor()) {
4519 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
4520 {
4521 FullExpressionRAII InitScope(Info);
4522 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
4523 return false;
4524 }
4525 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4526 }
4527
4528 // For a trivial copy or move constructor, perform an APValue copy. This is
4529 // essential for unions (or classes with anonymous union members), where the
4530 // operations performed by the constructor cannot be represented by
4531 // ctor-initializers.
4532 //
4533 // Skip this for empty non-union classes; we should not perform an
4534 // lvalue-to-rvalue conversion on them because their copy constructor does not
4535 // actually read them.
4536 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
4537 (Definition->getParent()->isUnion() ||
4538 (Definition->isTrivial() && hasFields(Definition->getParent())))) {
4539 LValue RHS;
4540 RHS.setFrom(Info.Ctx, ArgValues[0]);
4541 return handleLValueToRValueConversion(
4542 Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(),
4543 RHS, Result);
4544 }
4545
4546 // Reserve space for the struct members.
4547 if (!RD->isUnion() && Result.isUninit())
4548 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4549 std::distance(RD->field_begin(), RD->field_end()));
4550
4551 if (RD->isInvalidDecl()) return false;
4552 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
4553
4554 // A scope for temporaries lifetime-extended by reference members.
4555 BlockScopeRAII LifetimeExtendedScope(Info);
4556
4557 bool Success = true;
4558 unsigned BasesSeen = 0;
4559#ifndef NDEBUG
4560 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
4561#endif
4562 for (const auto *I : Definition->inits()) {
4563 LValue Subobject = This;
4564 LValue SubobjectParent = This;
4565 APValue *Value = &Result;
4566
4567 // Determine the subobject to initialize.
4568 FieldDecl *FD = nullptr;
4569 if (I->isBaseInitializer()) {
4570 QualType BaseType(I->getBaseClass(), 0);
4571#ifndef NDEBUG
4572 // Non-virtual base classes are initialized in the order in the class
4573 // definition. We have already checked for virtual base classes.
4574 assert(!BaseIt->isVirtual() && "virtual base for literal type")((!BaseIt->isVirtual() && "virtual base for literal type"
) ? static_cast<void> (0) : __assert_fail ("!BaseIt->isVirtual() && \"virtual base for literal type\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4574, __PRETTY_FUNCTION__))
;
4575 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&((Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order") ? static_cast
<void> (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4576, __PRETTY_FUNCTION__))
4576 "base class initializers not in expected order")((Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order") ? static_cast
<void> (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4576, __PRETTY_FUNCTION__))
;
4577 ++BaseIt;
4578#endif
4579 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
4580 BaseType->getAsCXXRecordDecl(), &Layout))
4581 return false;
4582 Value = &Result.getStructBase(BasesSeen++);
4583 } else if ((FD = I->getMember())) {
4584 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
4585 return false;
4586 if (RD->isUnion()) {
4587 Result = APValue(FD);
4588 Value = &Result.getUnionValue();
4589 } else {
4590 Value = &Result.getStructField(FD->getFieldIndex());
4591 }
4592 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
4593 // Walk the indirect field decl's chain to find the object to initialize,
4594 // and make sure we've initialized every step along it.
4595 auto IndirectFieldChain = IFD->chain();
4596 for (auto *C : IndirectFieldChain) {
4597 FD = cast<FieldDecl>(C);
4598 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
4599 // Switch the union field if it differs. This happens if we had
4600 // preceding zero-initialization, and we're now initializing a union
4601 // subobject other than the first.
4602 // FIXME: In this case, the values of the other subobjects are
4603 // specified, since zero-initialization sets all padding bits to zero.
4604 if (Value->isUninit() ||
4605 (Value->isUnion() && Value->getUnionField() != FD)) {
4606 if (CD->isUnion())
4607 *Value = APValue(FD);
4608 else
4609 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(),
4610 std::distance(CD->field_begin(), CD->field_end()));
4611 }
4612 // Store Subobject as its parent before updating it for the last element
4613 // in the chain.
4614 if (C == IndirectFieldChain.back())
4615 SubobjectParent = Subobject;
4616 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
4617 return false;
4618 if (CD->isUnion())
4619 Value = &Value->getUnionValue();
4620 else
4621 Value = &Value->getStructField(FD->getFieldIndex());
4622 }
4623 } else {
4624 llvm_unreachable("unknown base initializer kind")::llvm::llvm_unreachable_internal("unknown base initializer kind"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4624)
;
4625 }
4626
4627 // Need to override This for implicit field initializers as in this case
4628 // This refers to innermost anonymous struct/union containing initializer,
4629 // not to currently constructed class.
4630 const Expr *Init = I->getInit();
4631 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
4632 isa<CXXDefaultInitExpr>(Init));
4633 FullExpressionRAII InitScope(Info);
4634 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
4635 (FD && FD->isBitField() &&
4636 !truncateBitfieldValue(Info, Init, *Value, FD))) {
4637 // If we're checking for a potential constant expression, evaluate all
4638 // initializers even if some of them fail.
4639 if (!Info.noteFailure())
4640 return false;
4641 Success = false;
4642 }
4643 }
4644
4645 return Success &&
4646 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4647}
4648
4649static bool HandleConstructorCall(const Expr *E, const LValue &This,
4650 ArrayRef<const Expr*> Args,
4651 const CXXConstructorDecl *Definition,
4652 EvalInfo &Info, APValue &Result) {
4653 ArgVector ArgValues(Args.size());
4654 if (!EvaluateArgs(Args, ArgValues, Info))
4655 return false;
4656
4657 return HandleConstructorCall(E, This, ArgValues.data(), Definition,
4658 Info, Result);
4659}
4660
4661//===----------------------------------------------------------------------===//
4662// Generic Evaluation
4663//===----------------------------------------------------------------------===//
4664namespace {
4665
4666template <class Derived>
4667class ExprEvaluatorBase
4668 : public ConstStmtVisitor<Derived, bool> {
4669private:
4670 Derived &getDerived() { return static_cast<Derived&>(*this); }
4671 bool DerivedSuccess(const APValue &V, const Expr *E) {
4672 return getDerived().Success(V, E);
4673 }
4674 bool DerivedZeroInitialization(const Expr *E) {
4675 return getDerived().ZeroInitialization(E);
4676 }
4677
4678 // Check whether a conditional operator with a non-constant condition is a
4679 // potential constant expression. If neither arm is a potential constant
4680 // expression, then the conditional operator is not either.
4681 template<typename ConditionalOperator>
4682 void CheckPotentialConstantConditional(const ConditionalOperator *E) {
4683 assert(Info.checkingPotentialConstantExpression())((Info.checkingPotentialConstantExpression()) ? static_cast<
void> (0) : __assert_fail ("Info.checkingPotentialConstantExpression()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4683, __PRETTY_FUNCTION__))
;
4684
4685 // Speculatively evaluate both arms.
4686 SmallVector<PartialDiagnosticAt, 8> Diag;
4687 {
4688 SpeculativeEvaluationRAII Speculate(Info, &Diag);
4689 StmtVisitorTy::Visit(E->getFalseExpr());
4690 if (Diag.empty())
4691 return;
4692 }
4693
4694 {
4695 SpeculativeEvaluationRAII Speculate(Info, &Diag);
4696 Diag.clear();
4697 StmtVisitorTy::Visit(E->getTrueExpr());
4698 if (Diag.empty())
4699 return;
4700 }
4701
4702 Error(E, diag::note_constexpr_conditional_never_const);
4703 }
4704
4705
4706 template<typename ConditionalOperator>
4707 bool HandleConditionalOperator(const ConditionalOperator *E) {
4708 bool BoolResult;
4709 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
4710 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
4711 CheckPotentialConstantConditional(E);
4712 return false;
4713 }
4714 if (Info.noteFailure()) {
4715 StmtVisitorTy::Visit(E->getTrueExpr());
4716 StmtVisitorTy::Visit(E->getFalseExpr());
4717 }
4718 return false;
4719 }
4720
4721 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
4722 return StmtVisitorTy::Visit(EvalExpr);
4723 }
4724
4725protected:
4726 EvalInfo &Info;
4727 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
4728 typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
4729
4730 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
4731 return Info.CCEDiag(E, D);
4732 }
4733
4734 bool ZeroInitialization(const Expr *E) { return Error(E); }
4735
4736public:
4737 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
4738
4739 EvalInfo &getEvalInfo() { return Info; }
4740
4741 /// Report an evaluation error. This should only be called when an error is
4742 /// first discovered. When propagating an error, just return false.
4743 bool Error(const Expr *E, diag::kind D) {
4744 Info.FFDiag(E, D);
4745 return false;
4746 }
4747 bool Error(const Expr *E) {
4748 return Error(E, diag::note_invalid_subexpr_in_const_expr);
4749 }
4750
4751 bool VisitStmt(const Stmt *) {
4752 llvm_unreachable("Expression evaluator should not be called on stmts")::llvm::llvm_unreachable_internal("Expression evaluator should not be called on stmts"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4752)
;
4753 }
4754 bool VisitExpr(const Expr *E) {
4755 return Error(E);
4756 }
4757
4758 bool VisitConstantExpr(const ConstantExpr *E)
4759 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4760 bool VisitParenExpr(const ParenExpr *E)
4761 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4762 bool VisitUnaryExtension(const UnaryOperator *E)
4763 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4764 bool VisitUnaryPlus(const UnaryOperator *E)
4765 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4766 bool VisitChooseExpr(const ChooseExpr *E)
4767 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
4768 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
4769 { return StmtVisitorTy::Visit(E->getResultExpr()); }
4770 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
4771 { return StmtVisitorTy::Visit(E->getReplacement()); }
4772 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
4773 TempVersionRAII RAII(*Info.CurrentCall);
4774 return StmtVisitorTy::Visit(E->getExpr());
4775 }
4776 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
4777 TempVersionRAII RAII(*Info.CurrentCall);
4778 // The initializer may not have been parsed yet, or might be erroneous.
4779 if (!E->getExpr())
4780 return Error(E);
4781 return StmtVisitorTy::Visit(E->getExpr());
4782 }
4783 // We cannot create any objects for which cleanups are required, so there is
4784 // nothing to do here; all cleanups must come from unevaluated subexpressions.
4785 bool VisitExprWithCleanups(const ExprWithCleanups *E)
4786 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4787
4788 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
4789 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
4790 return static_cast<Derived*>(this)->VisitCastExpr(E);
4791 }
4792 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
4793 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
4794 return static_cast<Derived*>(this)->VisitCastExpr(E);
4795 }
4796
4797 bool VisitBinaryOperator(const BinaryOperator *E) {
4798 switch (E->getOpcode()) {
4799 default:
4800 return Error(E);
4801
4802 case BO_Comma:
4803 VisitIgnoredValue(E->getLHS());
4804 return StmtVisitorTy::Visit(E->getRHS());
4805
4806 case BO_PtrMemD:
4807 case BO_PtrMemI: {
4808 LValue Obj;
4809 if (!HandleMemberPointerAccess(Info, E, Obj))
4810 return false;
4811 APValue Result;
4812 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
4813 return false;
4814 return DerivedSuccess(Result, E);
4815 }
4816 }
4817 }
4818
4819 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
4820 // Evaluate and cache the common expression. We treat it as a temporary,
4821 // even though it's not quite the same thing.
4822 if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false),
4823 Info, E->getCommon()))
4824 return false;
4825
4826 return HandleConditionalOperator(E);
4827 }
4828
4829 bool VisitConditionalOperator(const ConditionalOperator *E) {
4830 bool IsBcpCall = false;
4831 // If the condition (ignoring parens) is a __builtin_constant_p call,
4832 // the result is a constant expression if it can be folded without
4833 // side-effects. This is an important GNU extension. See GCC PR38377
4834 // for discussion.
4835 if (const CallExpr *CallCE =
4836 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
4837 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
4838 IsBcpCall = true;
4839
4840 // Always assume __builtin_constant_p(...) ? ... : ... is a potential
4841 // constant expression; we can't check whether it's potentially foldable.
4842 if (Info.checkingPotentialConstantExpression() && IsBcpCall)
4843 return false;
4844
4845 FoldConstant Fold(Info, IsBcpCall);
4846 if (!HandleConditionalOperator(E)) {
4847 Fold.keepDiagnostics();
4848 return false;
4849 }
4850
4851 return true;
4852 }
4853
4854 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
4855 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
4856 return DerivedSuccess(*Value, E);
4857
4858 const Expr *Source = E->getSourceExpr();
4859 if (!Source)
4860 return Error(E);
4861 if (Source == E) { // sanity checking.
4862 assert(0 && "OpaqueValueExpr recursively refers to itself")((0 && "OpaqueValueExpr recursively refers to itself"
) ? static_cast<void> (0) : __assert_fail ("0 && \"OpaqueValueExpr recursively refers to itself\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4862, __PRETTY_FUNCTION__))
;
4863 return Error(E);
4864 }
4865 return StmtVisitorTy::Visit(Source);
4866 }
4867
4868 bool VisitCallExpr(const CallExpr *E) {
4869 APValue Result;
4870 if (!handleCallExpr(E, Result, nullptr))
4871 return false;
4872 return DerivedSuccess(Result, E);
4873 }
4874
4875 bool handleCallExpr(const CallExpr *E, APValue &Result,
4876 const LValue *ResultSlot) {
4877 const Expr *Callee = E->getCallee()->IgnoreParens();
4878 QualType CalleeType = Callee->getType();
4879
4880 const FunctionDecl *FD = nullptr;
4881 LValue *This = nullptr, ThisVal;
4882 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
4883 bool HasQualifier = false;
4884
4885 // Extract function decl and 'this' pointer from the callee.
4886 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
4887 const ValueDecl *Member = nullptr;
4888 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
4889 // Explicit bound member calls, such as x.f() or p->g();
4890 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
4891 return false;
4892 Member = ME->getMemberDecl();
4893 This = &ThisVal;
4894 HasQualifier = ME->hasQualifier();
4895 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
4896 // Indirect bound member calls ('.*' or '->*').
4897 Member = HandleMemberPointerAccess(Info, BE, ThisVal, false);
4898 if (!Member) return false;
4899 This = &ThisVal;
4900 } else
4901 return Error(Callee);
4902
4903 FD = dyn_cast<FunctionDecl>(Member);
4904 if (!FD)
4905 return Error(Callee);
4906 } else if (CalleeType->isFunctionPointerType()) {
4907 LValue Call;
4908 if (!EvaluatePointer(Callee, Call, Info))
4909 return false;
4910
4911 if (!Call.getLValueOffset().isZero())
4912 return Error(Callee);
4913 FD = dyn_cast_or_null<FunctionDecl>(
4914 Call.getLValueBase().dyn_cast<const ValueDecl*>());
4915 if (!FD)
4916 return Error(Callee);
4917 // Don't call function pointers which have been cast to some other type.
4918 // Per DR (no number yet), the caller and callee can differ in noexcept.
4919 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
4920 CalleeType->getPointeeType(), FD->getType())) {
4921 return Error(E);
4922 }
4923
4924 // Overloaded operator calls to member functions are represented as normal
4925 // calls with '*this' as the first argument.
4926 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
4927 if (MD && !MD->isStatic()) {
4928 // FIXME: When selecting an implicit conversion for an overloaded
4929 // operator delete, we sometimes try to evaluate calls to conversion
4930 // operators without a 'this' parameter!
4931 if (Args.empty())
4932 return Error(E);
4933
4934 if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
4935 return false;
4936 This = &ThisVal;
4937 Args = Args.slice(1);
4938 } else if (MD && MD->isLambdaStaticInvoker()) {
4939 // Map the static invoker for the lambda back to the call operator.
4940 // Conveniently, we don't have to slice out the 'this' argument (as is
4941 // being done for the non-static case), since a static member function
4942 // doesn't have an implicit argument passed in.
4943 const CXXRecordDecl *ClosureClass = MD->getParent();
4944 assert(((ClosureClass->captures_begin() == ClosureClass->captures_end
() && "Number of captures must be zero for conversion to function-ptr"
) ? static_cast<void> (0) : __assert_fail ("ClosureClass->captures_begin() == ClosureClass->captures_end() && \"Number of captures must be zero for conversion to function-ptr\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4946, __PRETTY_FUNCTION__))
4945 ClosureClass->captures_begin() == ClosureClass->captures_end() &&((ClosureClass->captures_begin() == ClosureClass->captures_end
() && "Number of captures must be zero for conversion to function-ptr"
) ? static_cast<void> (0) : __assert_fail ("ClosureClass->captures_begin() == ClosureClass->captures_end() && \"Number of captures must be zero for conversion to function-ptr\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4946, __PRETTY_FUNCTION__))
4946 "Number of captures must be zero for conversion to function-ptr")((ClosureClass->captures_begin() == ClosureClass->captures_end
() && "Number of captures must be zero for conversion to function-ptr"
) ? static_cast<void> (0) : __assert_fail ("ClosureClass->captures_begin() == ClosureClass->captures_end() && \"Number of captures must be zero for conversion to function-ptr\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4946, __PRETTY_FUNCTION__))
;
4947
4948 const CXXMethodDecl *LambdaCallOp =
4949 ClosureClass->getLambdaCallOperator();
4950
4951 // Set 'FD', the function that will be called below, to the call
4952 // operator. If the closure object represents a generic lambda, find
4953 // the corresponding specialization of the call operator.
4954
4955 if (ClosureClass->isGenericLambda()) {
4956 assert(MD->isFunctionTemplateSpecialization() &&((MD->isFunctionTemplateSpecialization() && "A generic lambda's static-invoker function must be a "
"template specialization") ? static_cast<void> (0) : __assert_fail
("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4958, __PRETTY_FUNCTION__))
4957 "A generic lambda's static-invoker function must be a "((MD->isFunctionTemplateSpecialization() && "A generic lambda's static-invoker function must be a "
"template specialization") ? static_cast<void> (0) : __assert_fail
("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4958, __PRETTY_FUNCTION__))
4958 "template specialization")((MD->isFunctionTemplateSpecialization() && "A generic lambda's static-invoker function must be a "
"template specialization") ? static_cast<void> (0) : __assert_fail
("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4958, __PRETTY_FUNCTION__))
;
4959 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
4960 FunctionTemplateDecl *CallOpTemplate =
4961 LambdaCallOp->getDescribedFunctionTemplate();
4962 void *InsertPos = nullptr;
4963 FunctionDecl *CorrespondingCallOpSpecialization =
4964 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
4965 assert(CorrespondingCallOpSpecialization &&((CorrespondingCallOpSpecialization && "We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? static_cast
<void> (0) : __assert_fail ("CorrespondingCallOpSpecialization && \"We must always have a function call operator specialization \" \"that corresponds to our static invoker specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4967, __PRETTY_FUNCTION__))
4966 "We must always have a function call operator specialization "((CorrespondingCallOpSpecialization && "We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? static_cast
<void> (0) : __assert_fail ("CorrespondingCallOpSpecialization && \"We must always have a function call operator specialization \" \"that corresponds to our static invoker specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4967, __PRETTY_FUNCTION__))
4967 "that corresponds to our static invoker specialization")((CorrespondingCallOpSpecialization && "We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? static_cast
<void> (0) : __assert_fail ("CorrespondingCallOpSpecialization && \"We must always have a function call operator specialization \" \"that corresponds to our static invoker specialization\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 4967, __PRETTY_FUNCTION__))
;
4968 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
4969 } else
4970 FD = LambdaCallOp;
4971 }
4972
4973
4974 } else
4975 return Error(E);
4976
4977 if (This && !This->checkSubobject(Info, E, CSK_This))
4978 return false;
4979
4980 // DR1358 allows virtual constexpr functions in some cases. Don't allow
4981 // calls to such functions in constant expressions.
4982 if (This && !HasQualifier &&
4983 isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual())
4984 return Error(E, diag::note_constexpr_virtual_call);
4985
4986 const FunctionDecl *Definition = nullptr;
4987 Stmt *Body = FD->getBody(Definition);
4988
4989 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
4990 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info,
4991 Result, ResultSlot))
4992 return false;
4993
4994 return true;
4995 }
4996
4997 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
4998 return StmtVisitorTy::Visit(E->getInitializer());
4999 }
5000 bool VisitInitListExpr(const InitListExpr *E) {
5001 if (E->getNumInits() == 0)
5002 return DerivedZeroInitialization(E);
5003 if (E->getNumInits() == 1)
5004 return StmtVisitorTy::Visit(E->getInit(0));
5005 return Error(E);
5006 }
5007 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
5008 return DerivedZeroInitialization(E);
5009 }
5010 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
5011 return DerivedZeroInitialization(E);
5012 }
5013 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
5014 return DerivedZeroInitialization(E);
5015 }
5016
5017 /// A member expression where the object is a prvalue is itself a prvalue.
5018 bool VisitMemberExpr(const MemberExpr *E) {
5019 assert(!E->isArrow() && "missing call to bound member function?")((!E->isArrow() && "missing call to bound member function?"
) ? static_cast<void> (0) : __assert_fail ("!E->isArrow() && \"missing call to bound member function?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5019, __PRETTY_FUNCTION__))
;
5020
5021 APValue Val;
5022 if (!Evaluate(Val, Info, E->getBase()))
5023 return false;
5024
5025 QualType BaseTy = E->getBase()->getType();
5026
5027 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
5028 if (!FD) return Error(E);
5029 assert(!FD->getType()->isReferenceType() && "prvalue reference?")((!FD->getType()->isReferenceType() && "prvalue reference?"
) ? static_cast<void> (0) : __assert_fail ("!FD->getType()->isReferenceType() && \"prvalue reference?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5029, __PRETTY_FUNCTION__))
;
5030 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==((BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl
() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"
) ? static_cast<void> (0) : __assert_fail ("BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5031, __PRETTY_FUNCTION__))
5031 FD->getParent()->getCanonicalDecl() && "record / field mismatch")((BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl
() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"
) ? static_cast<void> (0) : __assert_fail ("BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5031, __PRETTY_FUNCTION__))
;
5032
5033 CompleteObject Obj(&Val, BaseTy, true);
5034 SubobjectDesignator Designator(BaseTy);
5035 Designator.addDeclUnchecked(FD);
5036
5037 APValue Result;
5038 return extractSubobject(Info, E, Obj, Designator, Result) &&
5039 DerivedSuccess(Result, E);
5040 }
5041
5042 bool VisitCastExpr(const CastExpr *E) {
5043 switch (E->getCastKind()) {
5044 default:
5045 break;
5046
5047 case CK_AtomicToNonAtomic: {
5048 APValue AtomicVal;
5049 // This does not need to be done in place even for class/array types:
5050 // atomic-to-non-atomic conversion implies copying the object
5051 // representation.
5052 if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
5053 return false;
5054 return DerivedSuccess(AtomicVal, E);
5055 }
5056
5057 case CK_NoOp:
5058 case CK_UserDefinedConversion:
5059 return StmtVisitorTy::Visit(E->getSubExpr());
5060
5061 case CK_LValueToRValue: {
5062 LValue LVal;
5063 if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
5064 return false;
5065 APValue RVal;
5066 // Note, we use the subexpression's type in order to retain cv-qualifiers.
5067 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
5068 LVal, RVal))
5069 return false;
5070 return DerivedSuccess(RVal, E);
5071 }
5072 }
5073
5074 return Error(E);
5075 }
5076
5077 bool VisitUnaryPostInc(const UnaryOperator *UO) {
5078 return VisitUnaryPostIncDec(UO);
5079 }
5080 bool VisitUnaryPostDec(const UnaryOperator *UO) {
5081 return VisitUnaryPostIncDec(UO);
5082 }
5083 bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
5084 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5085 return Error(UO);
5086
5087 LValue LVal;
5088 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
5089 return false;
5090 APValue RVal;
5091 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
5092 UO->isIncrementOp(), &RVal))
5093 return false;
5094 return DerivedSuccess(RVal, UO);
5095 }
5096
5097 bool VisitStmtExpr(const StmtExpr *E) {
5098 // We will have checked the full-expressions inside the statement expression
5099 // when they were completed, and don't need to check them again now.
5100 if (Info.checkingForOverflow())
5101 return Error(E);
5102
5103 BlockScopeRAII Scope(Info);
5104 const CompoundStmt *CS = E->getSubStmt();
5105 if (CS->body_empty())
5106 return true;
5107
5108 for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
5109 BE = CS->body_end();
5110 /**/; ++BI) {
5111 if (BI + 1 == BE) {
5112 const Expr *FinalExpr = dyn_cast<Expr>(*BI);
5113 if (!FinalExpr) {
5114 Info.FFDiag((*BI)->getBeginLoc(),
5115 diag::note_constexpr_stmt_expr_unsupported);
5116 return false;
5117 }
5118 return this->Visit(FinalExpr);
5119 }
5120
5121 APValue ReturnValue;
5122 StmtResult Result = { ReturnValue, nullptr };
5123 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
5124 if (ESR != ESR_Succeeded) {
5125 // FIXME: If the statement-expression terminated due to 'return',
5126 // 'break', or 'continue', it would be nice to propagate that to
5127 // the outer statement evaluation rather than bailing out.
5128 if (ESR != ESR_Failed)
5129 Info.FFDiag((*BI)->getBeginLoc(),
5130 diag::note_constexpr_stmt_expr_unsupported);
5131 return false;
5132 }
5133 }
5134
5135 llvm_unreachable("Return from function from the loop above.")::llvm::llvm_unreachable_internal("Return from function from the loop above."
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5135)
;
5136 }
5137
5138 /// Visit a value which is evaluated, but whose value is ignored.
5139 void VisitIgnoredValue(const Expr *E) {
5140 EvaluateIgnoredValue(Info, E);
5
Calling 'EvaluateIgnoredValue'
9
Returning from 'EvaluateIgnoredValue'
5141 }
5142
5143 /// Potentially visit a MemberExpr's base expression.
5144 void VisitIgnoredBaseExpression(const Expr *E) {
5145 // While MSVC doesn't evaluate the base expression, it does diagnose the
5146 // presence of side-effecting behavior.
5147 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
3
Assuming the condition is false
5148 return;
5149 VisitIgnoredValue(E);
4
Calling 'ExprEvaluatorBase::VisitIgnoredValue'
10
Returning from 'ExprEvaluatorBase::VisitIgnoredValue'
5150 }
5151};
5152
5153} // namespace
5154
5155//===----------------------------------------------------------------------===//
5156// Common base class for lvalue and temporary evaluation.
5157//===----------------------------------------------------------------------===//
5158namespace {
5159template<class Derived>
5160class LValueExprEvaluatorBase
5161 : public ExprEvaluatorBase<Derived> {
5162protected:
5163 LValue &Result;
5164 bool InvalidBaseOK;
5165 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
5166 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
5167
5168 bool Success(APValue::LValueBase B) {
5169 Result.set(B);
5170 return true;
5171 }
5172
5173 bool evaluatePointer(const Expr *E, LValue &Result) {
5174 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
5175 }
5176
5177public:
5178 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
5179 : ExprEvaluatorBaseTy(Info), Result(Result),
5180 InvalidBaseOK(InvalidBaseOK) {}
5181
5182 bool Success(const APValue &V, const Expr *E) {
5183 Result.setFrom(this->Info.Ctx, V);
5184 return true;
5185 }
5186
5187 bool VisitMemberExpr(const MemberExpr *E) {
5188 // Handle non-static data members.
5189 QualType BaseTy;
5190 bool EvalOK;
5191 if (E->isArrow()) {
5192 EvalOK = evaluatePointer(E->getBase(), Result);
5193 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
5194 } else if (E->getBase()->isRValue()) {
5195 assert(E->getBase()->getType()->isRecordType())((E->getBase()->getType()->isRecordType()) ? static_cast
<void> (0) : __assert_fail ("E->getBase()->getType()->isRecordType()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5195, __PRETTY_FUNCTION__))
;
5196 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
5197 BaseTy = E->getBase()->getType();
5198 } else {
5199 EvalOK = this->Visit(E->getBase());
5200 BaseTy = E->getBase()->getType();
5201 }
5202 if (!EvalOK) {
5203 if (!InvalidBaseOK)
5204 return false;
5205 Result.setInvalid(E);
5206 return true;
5207 }
5208
5209 const ValueDecl *MD = E->getMemberDecl();
5210 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
5211 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() ==((BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl
() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"
) ? static_cast<void> (0) : __assert_fail ("BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5212, __PRETTY_FUNCTION__))
5212 FD->getParent()->getCanonicalDecl() && "record / field mismatch")((BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl
() == FD->getParent()->getCanonicalDecl() && "record / field mismatch"
) ? static_cast<void> (0) : __assert_fail ("BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5212, __PRETTY_FUNCTION__))
;
5213 (void)BaseTy;
5214 if (!HandleLValueMember(this->Info, E, Result, FD))
5215 return false;
5216 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
5217 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
5218 return false;
5219 } else
5220 return this->Error(E);
5221
5222 if (MD->getType()->isReferenceType()) {
5223 APValue RefValue;
5224 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
5225 RefValue))
5226 return false;
5227 return Success(RefValue, E);
5228 }
5229 return true;
5230 }
5231
5232 bool VisitBinaryOperator(const BinaryOperator *E) {
5233 switch (E->getOpcode()) {
5234 default:
5235 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5236
5237 case BO_PtrMemD:
5238 case BO_PtrMemI:
5239 return HandleMemberPointerAccess(this->Info, E, Result);
5240 }
5241 }
5242
5243 bool VisitCastExpr(const CastExpr *E) {
5244 switch (E->getCastKind()) {
5245 default:
5246 return ExprEvaluatorBaseTy::VisitCastExpr(E);
5247
5248 case CK_DerivedToBase:
5249 case CK_UncheckedDerivedToBase:
5250 if (!this->Visit(E->getSubExpr()))
5251 return false;
5252
5253 // Now figure out the necessary offset to add to the base LV to get from
5254 // the derived class to the base class.
5255 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
5256 Result);
5257 }
5258 }
5259};
5260}
5261
5262//===----------------------------------------------------------------------===//
5263// LValue Evaluation
5264//
5265// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
5266// function designators (in C), decl references to void objects (in C), and
5267// temporaries (if building with -Wno-address-of-temporary).
5268//
5269// LValue evaluation produces values comprising a base expression of one of the
5270// following types:
5271// - Declarations
5272// * VarDecl
5273// * FunctionDecl
5274// - Literals
5275// * CompoundLiteralExpr in C (and in global scope in C++)
5276// * StringLiteral
5277// * CXXTypeidExpr
5278// * PredefinedExpr
5279// * ObjCStringLiteralExpr
5280// * ObjCEncodeExpr
5281// * AddrLabelExpr
5282// * BlockExpr
5283// * CallExpr for a MakeStringConstant builtin
5284// - Locals and temporaries
5285// * MaterializeTemporaryExpr
5286// * Any Expr, with a CallIndex indicating the function in which the temporary
5287// was evaluated, for cases where the MaterializeTemporaryExpr is missing
5288// from the AST (FIXME).
5289// * A MaterializeTemporaryExpr that has static storage duration, with no
5290// CallIndex, for a lifetime-extended temporary.
5291// plus an offset in bytes.
5292//===----------------------------------------------------------------------===//
5293namespace {
5294class LValueExprEvaluator
5295 : public LValueExprEvaluatorBase<LValueExprEvaluator> {
5296public:
5297 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
5298 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
5299
5300 bool VisitVarDecl(const Expr *E, const VarDecl *VD);
5301 bool VisitUnaryPreIncDec(const UnaryOperator *UO);
5302
5303 bool VisitDeclRefExpr(const DeclRefExpr *E);
5304 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
5305 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
5306 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
5307 bool VisitMemberExpr(const MemberExpr *E);
5308 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
5309 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
5310 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
5311 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
5312 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
5313 bool VisitUnaryDeref(const UnaryOperator *E);
5314 bool VisitUnaryReal(const UnaryOperator *E);
5315 bool VisitUnaryImag(const UnaryOperator *E);
5316 bool VisitUnaryPreInc(const UnaryOperator *UO) {
5317 return VisitUnaryPreIncDec(UO);
5318 }
5319 bool VisitUnaryPreDec(const UnaryOperator *UO) {
5320 return VisitUnaryPreIncDec(UO);
5321 }
5322 bool VisitBinAssign(const BinaryOperator *BO);
5323 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
5324
5325 bool VisitCastExpr(const CastExpr *E) {
5326 switch (E->getCastKind()) {
5327 default:
5328 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
5329
5330 case CK_LValueBitCast:
5331 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5332 if (!Visit(E->getSubExpr()))
5333 return false;
5334 Result.Designator.setInvalid();
5335 return true;
5336
5337 case CK_BaseToDerived:
5338 if (!Visit(E->getSubExpr()))
5339 return false;
5340 return HandleBaseToDerivedCast(Info, E, Result);
5341 }
5342 }
5343};
5344} // end anonymous namespace
5345
5346/// Evaluate an expression as an lvalue. This can be legitimately called on
5347/// expressions which are not glvalues, in three cases:
5348/// * function designators in C, and
5349/// * "extern void" objects
5350/// * @selector() expressions in Objective-C
5351static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
5352 bool InvalidBaseOK) {
5353 assert(E->isGLValue() || E->getType()->isFunctionType() ||((E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType() || isa<ObjCSelectorExpr>
(E)) ? static_cast<void> (0) : __assert_fail ("E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5354, __PRETTY_FUNCTION__))
5354 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E))((E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType() || isa<ObjCSelectorExpr>
(E)) ? static_cast<void> (0) : __assert_fail ("E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5354, __PRETTY_FUNCTION__))
;
5355 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5356}
5357
5358bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
5359 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl()))
5360 return Success(FD);
5361 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
5362 return VisitVarDecl(E, VD);
5363 if (const BindingDecl *BD = dyn_cast<BindingDecl>(E->getDecl()))
5364 return Visit(BD->getBinding());
5365 return Error(E);
5366}
5367
5368
5369bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
5370
5371 // If we are within a lambda's call operator, check whether the 'VD' referred
5372 // to within 'E' actually represents a lambda-capture that maps to a
5373 // data-member/field within the closure object, and if so, evaluate to the
5374 // field or what the field refers to.
5375 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
13
Assuming pointer value is null
5376 isa<DeclRefExpr>(E) &&
5377 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
5378 // We don't always have a complete capture-map when checking or inferring if
5379 // the function call operator meets the requirements of a constexpr function
5380 // - but we don't need to evaluate the captures to determine constexprness
5381 // (dcl.constexpr C++17).
5382 if (Info.checkingPotentialConstantExpression())
5383 return false;
5384
5385 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
5386 // Start with 'Result' referring to the complete closure object...
5387 Result = *Info.CurrentCall->This;
5388 // ... then update it to refer to the field of the closure object
5389 // that represents the capture.
5390 if (!HandleLValueMember(Info, E, Result, FD))
5391 return false;
5392 // And if the field is of reference type, update 'Result' to refer to what
5393 // the field refers to.
5394 if (FD->getType()->isReferenceType()) {
5395 APValue RVal;
5396 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
5397 RVal))
5398 return false;
5399 Result.setFrom(Info.Ctx, RVal);
5400 }
5401 return true;
5402 }
5403 }
5404 CallStackFrame *Frame = nullptr;
5405 if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
14
Access to field 'Index' results in a dereference of a null pointer (loaded from field 'CurrentCall')
5406 // Only if a local variable was declared in the function currently being
5407 // evaluated, do we expect to be able to find its value in the current
5408 // frame. (Otherwise it was likely declared in an enclosing context and
5409 // could either have a valid evaluatable value (for e.g. a constexpr
5410 // variable) or be ill-formed (and trigger an appropriate evaluation
5411 // diagnostic)).
5412 if (Info.CurrentCall->Callee &&
5413 Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
5414 Frame = Info.CurrentCall;
5415 }
5416 }
5417
5418 if (!VD->getType()->isReferenceType()) {
5419 if (Frame) {
5420 Result.set({VD, Frame->Index,
5421 Info.CurrentCall->getCurrentTemporaryVersion(VD)});
5422 return true;
5423 }
5424 return Success(VD);
5425 }
5426
5427 APValue *V;
5428 if (!evaluateVarDeclInit(Info, E, VD, Frame, V, nullptr))
5429 return false;
5430 if (V->isUninit()) {
5431 if (!Info.checkingPotentialConstantExpression())
5432 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
5433 return false;
5434 }
5435 return Success(*V, E);
5436}
5437
5438bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
5439 const MaterializeTemporaryExpr *E) {
5440 // Walk through the expression to find the materialized temporary itself.
5441 SmallVector<const Expr *, 2> CommaLHSs;
5442 SmallVector<SubobjectAdjustment, 2> Adjustments;
5443 const Expr *Inner = E->GetTemporaryExpr()->
5444 skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
5445
5446 // If we passed any comma operators, evaluate their LHSs.
5447 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
5448 if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
5449 return false;
5450
5451 // A materialized temporary with static storage duration can appear within the
5452 // result of a constant expression evaluation, so we need to preserve its
5453 // value for use outside this evaluation.
5454 APValue *Value;
5455 if (E->getStorageDuration() == SD_Static) {
5456 Value = Info.Ctx.getMaterializedTemporaryValue(E, true);
5457 *Value = APValue();
5458 Result.set(E);
5459 } else {
5460 Value = &createTemporary(E, E->getStorageDuration() == SD_Automatic, Result,
5461 *Info.CurrentCall);
5462 }
5463
5464 QualType Type = Inner->getType();
5465
5466 // Materialize the temporary itself.
5467 if (!EvaluateInPlace(*Value, Info, Result, Inner) ||
5468 (E->getStorageDuration() == SD_Static &&
5469 !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) {
5470 *Value = APValue();
5471 return false;
5472 }
5473
5474 // Adjust our lvalue to refer to the desired subobject.
5475 for (unsigned I = Adjustments.size(); I != 0; /**/) {
5476 --I;
5477 switch (Adjustments[I].Kind) {
5478 case SubobjectAdjustment::DerivedToBaseAdjustment:
5479 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
5480 Type, Result))
5481 return false;
5482 Type = Adjustments[I].DerivedToBase.BasePath->getType();
5483 break;
5484
5485 case SubobjectAdjustment::FieldAdjustment:
5486 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
5487 return false;
5488 Type = Adjustments[I].Field->getType();
5489 break;
5490
5491 case SubobjectAdjustment::MemberPointerAdjustment:
5492 if (!HandleMemberPointerAccess(this->Info, Type, Result,
5493 Adjustments[I].Ptr.RHS))
5494 return false;
5495 Type = Adjustments[I].Ptr.MPT->getPointeeType();
5496 break;
5497 }
5498 }
5499
5500 return true;
5501}
5502
5503bool
5504LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
5505 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&(((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
"lvalue compound literal in c++?") ? static_cast<void>
(0) : __assert_fail ("(!Info.getLangOpts().CPlusPlus || E->isFileScope()) && \"lvalue compound literal in c++?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5506, __PRETTY_FUNCTION__))
5506 "lvalue compound literal in c++?")(((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
"lvalue compound literal in c++?") ? static_cast<void>
(0) : __assert_fail ("(!Info.getLangOpts().CPlusPlus || E->isFileScope()) && \"lvalue compound literal in c++?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5506, __PRETTY_FUNCTION__))
;
5507 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
5508 // only see this when folding in C, so there's no standard to follow here.
5509 return Success(E);
5510}
5511
5512bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
5513 if (!E->isPotentiallyEvaluated())
5514 return Success(E);
5515
5516 Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic)
5517 << E->getExprOperand()->getType()
5518 << E->getExprOperand()->getSourceRange();
5519 return false;
5520}
5521
5522bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
5523 return Success(E);
5524}
5525
5526bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
5527 // Handle static data members.
5528 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
1
Taking true branch
5529 VisitIgnoredBaseExpression(E->getBase());
2
Calling 'ExprEvaluatorBase::VisitIgnoredBaseExpression'
11
Returning from 'ExprEvaluatorBase::VisitIgnoredBaseExpression'
5530 return VisitVarDecl(E, VD);
12
Calling 'LValueExprEvaluator::VisitVarDecl'
5531 }
5532
5533 // Handle static member functions.
5534 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
5535 if (MD->isStatic()) {
5536 VisitIgnoredBaseExpression(E->getBase());
5537 return Success(MD);
5538 }
5539 }
5540
5541 // Handle non-static data members.
5542 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
5543}
5544
5545bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
5546 // FIXME: Deal with vectors as array subscript bases.
5547 if (E->getBase()->getType()->isVectorType())
5548 return Error(E);
5549
5550 bool Success = true;
5551 if (!evaluatePointer(E->getBase(), Result)) {
5552 if (!Info.noteFailure())
5553 return false;
5554 Success = false;
5555 }
5556
5557 APSInt Index;
5558 if (!EvaluateInteger(E->getIdx(), Index, Info))
5559 return false;
5560
5561 return Success &&
5562 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
5563}
5564
5565bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
5566 return evaluatePointer(E->getSubExpr(), Result);
5567}
5568
5569bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
5570 if (!Visit(E->getSubExpr()))
5571 return false;
5572 // __real is a no-op on scalar lvalues.
5573 if (E->getSubExpr()->getType()->isAnyComplexType())
5574 HandleLValueComplexElement(Info, E, Result, E->getType(), false);
5575 return true;
5576}
5577
5578bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
5579 assert(E->getSubExpr()->getType()->isAnyComplexType() &&((E->getSubExpr()->getType()->isAnyComplexType() &&
"lvalue __imag__ on scalar?") ? static_cast<void> (0) :
__assert_fail ("E->getSubExpr()->getType()->isAnyComplexType() && \"lvalue __imag__ on scalar?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5580, __PRETTY_FUNCTION__))
5580 "lvalue __imag__ on scalar?")((E->getSubExpr()->getType()->isAnyComplexType() &&
"lvalue __imag__ on scalar?") ? static_cast<void> (0) :
__assert_fail ("E->getSubExpr()->getType()->isAnyComplexType() && \"lvalue __imag__ on scalar?\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5580, __PRETTY_FUNCTION__))
;
5581 if (!Visit(E->getSubExpr()))
5582 return false;
5583 HandleLValueComplexElement(Info, E, Result, E->getType(), true);
5584 return true;
5585}
5586
5587bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
5588 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5589 return Error(UO);
5590
5591 if (!this->Visit(UO->getSubExpr()))
5592 return false;
5593
5594 return handleIncDec(
5595 this->Info, UO, Result, UO->getSubExpr()->getType(),
5596 UO->isIncrementOp(), nullptr);
5597}
5598
5599bool LValueExprEvaluator::VisitCompoundAssignOperator(
5600 const CompoundAssignOperator *CAO) {
5601 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5602 return Error(CAO);
5603
5604 APValue RHS;
5605
5606 // The overall lvalue result is the result of evaluating the LHS.
5607 if (!this->Visit(CAO->getLHS())) {
5608 if (Info.noteFailure())
5609 Evaluate(RHS, this->Info, CAO->getRHS());
5610 return false;
5611 }
5612
5613 if (!Evaluate(RHS, this->Info, CAO->getRHS()))
5614 return false;
5615
5616 return handleCompoundAssignment(
5617 this->Info, CAO,
5618 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
5619 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
5620}
5621
5622bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
5623 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5624 return Error(E);
5625
5626 APValue NewVal;
5627
5628 if (!this->Visit(E->getLHS())) {
5629 if (Info.noteFailure())
5630 Evaluate(NewVal, this->Info, E->getRHS());
5631 return false;
5632 }
5633
5634 if (!Evaluate(NewVal, this->Info, E->getRHS()))
5635 return false;
5636
5637 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
5638 NewVal);
5639}
5640
5641//===----------------------------------------------------------------------===//
5642// Pointer Evaluation
5643//===----------------------------------------------------------------------===//
5644
5645/// Attempts to compute the number of bytes available at the pointer
5646/// returned by a function with the alloc_size attribute. Returns true if we
5647/// were successful. Places an unsigned number into `Result`.
5648///
5649/// This expects the given CallExpr to be a call to a function with an
5650/// alloc_size attribute.
5651static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
5652 const CallExpr *Call,
5653 llvm::APInt &Result) {
5654 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
5655
5656 assert(AllocSize && AllocSize->getElemSizeParam().isValid())((AllocSize && AllocSize->getElemSizeParam().isValid
()) ? static_cast<void> (0) : __assert_fail ("AllocSize && AllocSize->getElemSizeParam().isValid()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5656, __PRETTY_FUNCTION__))
;
5657 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
5658 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
5659 if (Call->getNumArgs() <= SizeArgNo)
5660 return false;
5661
5662 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
5663 Expr::EvalResult ExprResult;
5664 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
5665 return false;
5666 Into = ExprResult.Val.getInt();
5667 if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
5668 return false;
5669 Into = Into.zextOrSelf(BitsInSizeT);
5670 return true;
5671 };
5672
5673 APSInt SizeOfElem;
5674 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
5675 return false;
5676
5677 if (!AllocSize->getNumElemsParam().isValid()) {
5678 Result = std::move(SizeOfElem);
5679 return true;
5680 }
5681
5682 APSInt NumberOfElems;
5683 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
5684 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
5685 return false;
5686
5687 bool Overflow;
5688 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
5689 if (Overflow)
5690 return false;
5691
5692 Result = std::move(BytesAvailable);
5693 return true;
5694}
5695
5696/// Convenience function. LVal's base must be a call to an alloc_size
5697/// function.
5698static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
5699 const LValue &LVal,
5700 llvm::APInt &Result) {
5701 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&((isBaseAnAllocSizeCall(LVal.getLValueBase()) && "Can't get the size of a non alloc_size function"
) ? static_cast<void> (0) : __assert_fail ("isBaseAnAllocSizeCall(LVal.getLValueBase()) && \"Can't get the size of a non alloc_size function\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5702, __PRETTY_FUNCTION__))
5702 "Can't get the size of a non alloc_size function")((isBaseAnAllocSizeCall(LVal.getLValueBase()) && "Can't get the size of a non alloc_size function"
) ? static_cast<void> (0) : __assert_fail ("isBaseAnAllocSizeCall(LVal.getLValueBase()) && \"Can't get the size of a non alloc_size function\""
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5702, __PRETTY_FUNCTION__))
;
5703 const auto *Base = LVal.getLValueBase().get<const Expr *>();
5704 const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
5705 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
5706}
5707
5708/// Attempts to evaluate the given LValueBase as the result of a call to
5709/// a function with the alloc_size attribute. If it was possible to do so, this
5710/// function will return true, make Result's Base point to said function call,
5711/// and mark Result's Base as invalid.
5712static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
5713 LValue &Result) {
5714 if (Base.isNull())
5715 return false;
5716
5717 // Because we do no form of static analysis, we only support const variables.
5718 //
5719 // Additionally, we can't support parameters, nor can we support static
5720 // variables (in the latter case, use-before-assign isn't UB; in the former,
5721 // we have no clue what they'll be assigned to).
5722 const auto *VD =
5723 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
5724 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
5725 return false;
5726
5727 const Expr *Init = VD->getAnyInitializer();
5728 if (!Init)
5729 return false;
5730
5731 const Expr *E = Init->IgnoreParens();
5732 if (!tryUnwrapAllocSizeCall(E))
5733 return false;
5734
5735 // Store E instead of E unwrapped so that the type of the LValue's base is
5736 // what the user wanted.
5737 Result.setInvalid(E);
5738
5739 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
5740 Result.addUnsizedArray(Info, E, Pointee);
5741 return true;
5742}
5743
5744namespace {
5745class PointerExprEvaluator
5746 : public ExprEvaluatorBase<PointerExprEvaluator> {
5747 LValue &Result;
5748 bool InvalidBaseOK;
5749
5750 bool Success(const Expr *E) {
5751 Result.set(E);
5752 return true;
5753 }
5754
5755 bool evaluateLValue(const Expr *E, LValue &Result) {
5756 return EvaluateLValue(E, Result, Info, InvalidBaseOK);
5757 }
5758
5759 bool evaluatePointer(const Expr *E, LValue &Result) {
5760 return EvaluatePointer(E, Result, Info, InvalidBaseOK);
5761 }
5762
5763 bool visitNonBuiltinCallExpr(const CallExpr *E);
5764public:
5765
5766 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
5767 : ExprEvaluatorBaseTy(info), Result(Result),
5768 InvalidBaseOK(InvalidBaseOK) {}
5769
5770 bool Success(const APValue &V, const Expr *E) {
5771 Result.setFrom(Info.Ctx, V);
5772 return true;
5773 }
5774 bool ZeroInitialization(const Expr *E) {
5775 auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType());
5776 Result.setNull(E->getType(), TargetVal);
5777 return true;
5778 }
5779
5780 bool VisitBinaryOperator(const BinaryOperator *E);
5781 bool VisitCastExpr(const CastExpr* E);
5782 bool VisitUnaryAddrOf(const UnaryOperator *E);
5783 bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
5784 { return Success(E); }
5785 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
5786 if (Info.noteFailure())
5787 EvaluateIgnoredValue(Info, E->getSubExpr());
5788 return Error(E);
5789 }
5790 bool VisitAddrLabelExpr(const AddrLabelExpr *E)
5791 { return Success(E); }
5792 bool VisitCallExpr(const CallExpr *E);
5793 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
5794 bool VisitBlockExpr(const BlockExpr *E) {
5795 if (!E->getBlockDecl()->hasCaptures())
5796 return Success(E);
5797 return Error(E);
5798 }
5799 bool VisitCXXThisExpr(const CXXThisExpr *E) {
5800 // Can't look at 'this' when checking a potential constant expression.
5801 if (Info.checkingPotentialConstantExpression())
5802 return false;
5803 if (!Info.CurrentCall->This) {
5804 if (Info.getLangOpts().CPlusPlus11)
5805 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
5806 else
5807 Info.FFDiag(E);
5808 return false;
5809 }
5810 Result = *Info.CurrentCall->This;
5811 // If we are inside a lambda's call operator, the 'this' expression refers
5812 // to the enclosing '*this' object (either by value or reference) which is
5813 // either copied into the closure object's field that represents the '*this'
5814 // or refers to '*this'.
5815 if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
5816 // Update 'Result' to refer to the data member/field of the closure object
5817 // that represents the '*this' capture.
5818 if (!HandleLValueMember(Info, E, Result,
5819 Info.CurrentCall->LambdaThisCaptureField))
5820 return false;
5821 // If we captured '*this' by reference, replace the field with its referent.
5822 if (Info.CurrentCall->LambdaThisCaptureField->getType()
5823 ->isPointerType()) {
5824 APValue RVal;
5825 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
5826 RVal))
5827 return false;
5828
5829 Result.setFrom(Info.Ctx, RVal);
5830 }
5831 }
5832 return true;
5833 }
5834
5835 // FIXME: Missing: @protocol, @selector
5836};
5837} // end anonymous namespace
5838
5839static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
5840 bool InvalidBaseOK) {
5841 assert(E->isRValue() && E->getType()->hasPointerRepresentation())((E->isRValue() && E->getType()->hasPointerRepresentation
()) ? static_cast<void> (0) : __assert_fail ("E->isRValue() && E->getType()->hasPointerRepresentation()"
, "/build/llvm-toolchain-snapshot-8~svn350071/tools/clang/lib/AST/ExprConstant.cpp"
, 5841, __PRETTY_FUNCTION__))
;
5842 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5843}
5844
5845bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
5846 if (E->getOpcode() != BO_Add &&
5847 E->getOpcode() != BO_Sub)
5848 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5849
5850 const Expr *PExp = E->getLHS();
5851 const Expr *IExp = E->getRHS();
5852 if (IExp->getType()->isPointerType())
5853 std::swap(PExp, IExp);
5854
5855 bool EvalPtrOK = evaluatePointer(PExp, Result);
5856 if (!EvalPtrOK && !Info.noteFailure())
5857 return false;
5858
5859 llvm::APSInt Offset;
5860 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
5861 return false;
5862
5863 if (E->getOpcode() == BO_Sub)
5864 negateAsSigned(Offset);
5865
5866 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
5867 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
5868}
5869
5870bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
5871 return evaluateLValue(E->getSubExpr(), Result);
5872}
5873
5874bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
5875 const Expr *SubExpr = E->getSubExpr();
5876
5877 switch (E->getCastKind()) {
5878 default:
5879 break;
5880
5881 case CK_BitCast:
5882 case CK_CPointerToObjCPointerCast:
5883 case CK_BlockPointerToObjCPointerCast:
5884 case CK_AnyPointerToBlockPointerCast:
5885 case CK_AddressSpaceConversion:
5886 if (!Visit(SubExpr))
5887 return false;
5888 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are