Bug Summary

File:tools/clang/lib/AST/ExprConstant.cpp
Warning:line 2431, column 27
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ExprConstant.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -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 -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-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-7~svn338205/tools/clang/include -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn338205/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/lib/AST -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -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-2018-07-29-043837-17923-1 -x c++ /build/llvm-toolchain-snapshot-7~svn338205/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/RecordLayout.h"
43#include "clang/AST/StmtVisitor.h"
44#include "clang/AST/TypeLoc.h"
45#include "clang/Basic/Builtins.h"
46#include "clang/Basic/TargetInfo.h"
47#include "llvm/Support/raw_ostream.h"
48#include <cstring>
49#include <functional>
50
51#define DEBUG_TYPE"exprconstant" "exprconstant"
52
53using namespace clang;
54using llvm::APSInt;
55using llvm::APFloat;
56
57static bool IsGlobalLValue(APValue::LValueBase B);
58
59namespace {
60 struct LValue;
61 struct CallStackFrame;
62 struct EvalInfo;
63
64 static QualType getType(APValue::LValueBase B) {
65 if (!B) return QualType();
66 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
67 // FIXME: It's unclear where we're supposed to take the type from, and
68 // this actually matters for arrays of unknown bound. Eg:
69 //
70 // extern int arr[]; void f() { extern int arr[3]; };
71 // constexpr int *p = &arr[1]; // valid?
72 //
73 // For now, we take the array bound from the most recent declaration.
74 for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl;
75 Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) {
76 QualType T = Redecl->getType();
77 if (!T->isIncompleteArrayType())
78 return T;
79 }
80 return D->getType();
81 }
82
83 const Expr *Base = B.get<const Expr*>();
84
85 // For a materialized temporary, the type of the temporary we materialized
86 // may not be the type of the expression.
87 if (const MaterializeTemporaryExpr *MTE =
88 dyn_cast<MaterializeTemporaryExpr>(Base)) {
89 SmallVector<const Expr *, 2> CommaLHSs;
90 SmallVector<SubobjectAdjustment, 2> Adjustments;
91 const Expr *Temp = MTE->GetTemporaryExpr();
92 const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
93 Adjustments);
94 // Keep any cv-qualifiers from the reference if we generated a temporary
95 // for it directly. Otherwise use the type after adjustment.
96 if (!Adjustments.empty())
97 return Inner->getType();
98 }
99
100 return Base->getType();
101 }
102
103 /// Get an LValue path entry, which is known to not be an array index, as a
104 /// field or base class.
105 static
106 APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) {
107 APValue::BaseOrMemberType Value;
108 Value.setFromOpaqueValue(E.BaseOrMember);
109 return Value;
110 }
111
112 /// Get an LValue path entry, which is known to not be an array index, as a
113 /// field declaration.
114 static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
115 return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer());
116 }
117 /// Get an LValue path entry, which is known to not be an array index, as a
118 /// base class declaration.
119 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
120 return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer());
121 }
122 /// Determine whether this LValue path entry for a base class names a virtual
123 /// base class.
124 static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
125 return getAsBaseOrMember(E).getInt();
126 }
127
128 /// Given a CallExpr, try to get the alloc_size attribute. May return null.
129 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
130 const FunctionDecl *Callee = CE->getDirectCallee();
131 return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr;
132 }
133
134 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
135 /// This will look through a single cast.
136 ///
137 /// Returns null if we couldn't unwrap a function with alloc_size.
138 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
139 if (!E->getType()->isPointerType())
140 return nullptr;
141
142 E = E->IgnoreParens();
143 // If we're doing a variable assignment from e.g. malloc(N), there will
144 // probably be a cast of some kind. In exotic cases, we might also see a
145 // top-level ExprWithCleanups. Ignore them either way.
146 if (const auto *EC = dyn_cast<ExprWithCleanups>(E))
147 E = EC->getSubExpr()->IgnoreParens();
148
149 if (const auto *Cast = dyn_cast<CastExpr>(E))
150 E = Cast->getSubExpr()->IgnoreParens();
151
152 if (const auto *CE = dyn_cast<CallExpr>(E))
153 return getAllocSizeAttr(CE) ? CE : nullptr;
154 return nullptr;
155 }
156
157 /// Determines whether or not the given Base contains a call to a function
158 /// with the alloc_size attribute.
159 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
160 const auto *E = Base.dyn_cast<const Expr *>();
161 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
162 }
163
164 /// The bound to claim that an array of unknown bound has.
165 /// The value in MostDerivedArraySize is undefined in this case. So, set it
166 /// to an arbitrary value that's likely to loudly break things if it's used.
167 static const uint64_t AssumedSizeForUnsizedArray =
168 std::numeric_limits<uint64_t>::max() / 2;
169
170 /// Determines if an LValue with the given LValueBase will have an unsized
171 /// array in its designator.
172 /// Find the path length and type of the most-derived subobject in the given
173 /// path, and find the size of the containing array, if any.
174 static unsigned
175 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
176 ArrayRef<APValue::LValuePathEntry> Path,
177 uint64_t &ArraySize, QualType &Type, bool &IsArray,
178 bool &FirstEntryIsUnsizedArray) {
179 // This only accepts LValueBases from APValues, and APValues don't support
180 // arrays that lack size info.
181 assert(!isBaseAnAllocSizeCall(Base) &&(static_cast <bool> (!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here") ? void (0) : __assert_fail
("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 182, __extension__ __PRETTY_FUNCTION__))
182 "Unsized arrays shouldn't appear here")(static_cast <bool> (!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here") ? void (0) : __assert_fail
("!isBaseAnAllocSizeCall(Base) && \"Unsized arrays shouldn't appear here\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 182, __extension__ __PRETTY_FUNCTION__))
;
183 unsigned MostDerivedLength = 0;
184 Type = getType(Base);
185
186 for (unsigned I = 0, N = Path.size(); I != N; ++I) {
187 if (Type->isArrayType()) {
188 const ArrayType *AT = Ctx.getAsArrayType(Type);
189 Type = AT->getElementType();
190 MostDerivedLength = I + 1;
191 IsArray = true;
192
193 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
194 ArraySize = CAT->getSize().getZExtValue();
195 } else {
196 assert(I == 0 && "unexpected unsized array designator")(static_cast <bool> (I == 0 && "unexpected unsized array designator"
) ? void (0) : __assert_fail ("I == 0 && \"unexpected unsized array designator\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 196, __extension__ __PRETTY_FUNCTION__))
;
197 FirstEntryIsUnsizedArray = true;
198 ArraySize = AssumedSizeForUnsizedArray;
199 }
200 } else if (Type->isAnyComplexType()) {
201 const ComplexType *CT = Type->castAs<ComplexType>();
202 Type = CT->getElementType();
203 ArraySize = 2;
204 MostDerivedLength = I + 1;
205 IsArray = true;
206 } else if (const FieldDecl *FD = getAsField(Path[I])) {
207 Type = FD->getType();
208 ArraySize = 0;
209 MostDerivedLength = I + 1;
210 IsArray = false;
211 } else {
212 // Path[I] describes a base class.
213 ArraySize = 0;
214 IsArray = false;
215 }
216 }
217 return MostDerivedLength;
218 }
219
220 // The order of this enum is important for diagnostics.
221 enum CheckSubobjectKind {
222 CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex,
223 CSK_This, CSK_Real, CSK_Imag
224 };
225
226 /// A path from a glvalue to a subobject of that glvalue.
227 struct SubobjectDesignator {
228 /// True if the subobject was named in a manner not supported by C++11. Such
229 /// lvalues can still be folded, but they are not core constant expressions
230 /// and we cannot perform lvalue-to-rvalue conversions on them.
231 unsigned Invalid : 1;
232
233 /// Is this a pointer one past the end of an object?
234 unsigned IsOnePastTheEnd : 1;
235
236 /// Indicator of whether the first entry is an unsized array.
237 unsigned FirstEntryIsAnUnsizedArray : 1;
238
239 /// Indicator of whether the most-derived object is an array element.
240 unsigned MostDerivedIsArrayElement : 1;
241
242 /// The length of the path to the most-derived object of which this is a
243 /// subobject.
244 unsigned MostDerivedPathLength : 28;
245
246 /// The size of the array of which the most-derived object is an element.
247 /// This will always be 0 if the most-derived object is not an array
248 /// element. 0 is not an indicator of whether or not the most-derived object
249 /// is an array, however, because 0-length arrays are allowed.
250 ///
251 /// If the current array is an unsized array, the value of this is
252 /// undefined.
253 uint64_t MostDerivedArraySize;
254
255 /// The type of the most derived object referred to by this address.
256 QualType MostDerivedType;
257
258 typedef APValue::LValuePathEntry PathEntry;
259
260 /// The entries on the path from the glvalue to the designated subobject.
261 SmallVector<PathEntry, 8> Entries;
262
263 SubobjectDesignator() : Invalid(true) {}
264
265 explicit SubobjectDesignator(QualType T)
266 : Invalid(false), IsOnePastTheEnd(false),
267 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
268 MostDerivedPathLength(0), MostDerivedArraySize(0),
269 MostDerivedType(T) {}
270
271 SubobjectDesignator(ASTContext &Ctx, const APValue &V)
272 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
273 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
274 MostDerivedPathLength(0), MostDerivedArraySize(0) {
275 assert(V.isLValue() && "Non-LValue used to make an LValue designator?")(static_cast <bool> (V.isLValue() && "Non-LValue used to make an LValue designator?"
) ? void (0) : __assert_fail ("V.isLValue() && \"Non-LValue used to make an LValue designator?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 275, __extension__ __PRETTY_FUNCTION__))
;
276 if (!Invalid) {
277 IsOnePastTheEnd = V.isLValueOnePastTheEnd();
278 ArrayRef<PathEntry> VEntries = V.getLValuePath();
279 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
280 if (V.getLValueBase()) {
281 bool IsArray = false;
282 bool FirstIsUnsizedArray = false;
283 MostDerivedPathLength = findMostDerivedSubobject(
284 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
285 MostDerivedType, IsArray, FirstIsUnsizedArray);
286 MostDerivedIsArrayElement = IsArray;
287 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
288 }
289 }
290 }
291
292 void setInvalid() {
293 Invalid = true;
294 Entries.clear();
295 }
296
297 /// Determine whether the most derived subobject is an array without a
298 /// known bound.
299 bool isMostDerivedAnUnsizedArray() const {
300 assert(!Invalid && "Calling this makes no sense on invalid designators")(static_cast <bool> (!Invalid && "Calling this makes no sense on invalid designators"
) ? void (0) : __assert_fail ("!Invalid && \"Calling this makes no sense on invalid designators\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 300, __extension__ __PRETTY_FUNCTION__))
;
301 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
302 }
303
304 /// Determine what the most derived array's size is. Results in an assertion
305 /// failure if the most derived array lacks a size.
306 uint64_t getMostDerivedArraySize() const {
307 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size")(static_cast <bool> (!isMostDerivedAnUnsizedArray() &&
"Unsized array has no size") ? void (0) : __assert_fail ("!isMostDerivedAnUnsizedArray() && \"Unsized array has no size\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 307, __extension__ __PRETTY_FUNCTION__))
;
308 return MostDerivedArraySize;
309 }
310
311 /// Determine whether this is a one-past-the-end pointer.
312 bool isOnePastTheEnd() const {
313 assert(!Invalid)(static_cast <bool> (!Invalid) ? void (0) : __assert_fail
("!Invalid", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 313, __extension__ __PRETTY_FUNCTION__))
;
314 if (IsOnePastTheEnd)
315 return true;
316 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
317 Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize)
318 return true;
319 return false;
320 }
321
322 /// Check that this refers to a valid subobject.
323 bool isValidSubobject() const {
324 if (Invalid)
325 return false;
326 return !isOnePastTheEnd();
327 }
328 /// Check that this refers to a valid subobject, and if not, produce a
329 /// relevant diagnostic and set the designator as invalid.
330 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
331
332 /// Update this designator to refer to the first element within this array.
333 void addArrayUnchecked(const ConstantArrayType *CAT) {
334 PathEntry Entry;
335 Entry.ArrayIndex = 0;
336 Entries.push_back(Entry);
337
338 // This is a most-derived object.
339 MostDerivedType = CAT->getElementType();
340 MostDerivedIsArrayElement = true;
341 MostDerivedArraySize = CAT->getSize().getZExtValue();
342 MostDerivedPathLength = Entries.size();
343 }
344 /// Update this designator to refer to the first element within the array of
345 /// elements of type T. This is an array of unknown size.
346 void addUnsizedArrayUnchecked(QualType ElemTy) {
347 PathEntry Entry;
348 Entry.ArrayIndex = 0;
349 Entries.push_back(Entry);
350
351 MostDerivedType = ElemTy;
352 MostDerivedIsArrayElement = true;
353 // The value in MostDerivedArraySize is undefined in this case. So, set it
354 // to an arbitrary value that's likely to loudly break things if it's
355 // used.
356 MostDerivedArraySize = AssumedSizeForUnsizedArray;
357 MostDerivedPathLength = Entries.size();
358 }
359 /// Update this designator to refer to the given base or member of this
360 /// object.
361 void addDeclUnchecked(const Decl *D, bool Virtual = false) {
362 PathEntry Entry;
363 APValue::BaseOrMemberType Value(D, Virtual);
364 Entry.BaseOrMember = Value.getOpaqueValue();
365 Entries.push_back(Entry);
366
367 // If this isn't a base class, it's a new most-derived object.
368 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
369 MostDerivedType = FD->getType();
370 MostDerivedIsArrayElement = false;
371 MostDerivedArraySize = 0;
372 MostDerivedPathLength = Entries.size();
373 }
374 }
375 /// Update this designator to refer to the given complex component.
376 void addComplexUnchecked(QualType EltTy, bool Imag) {
377 PathEntry Entry;
378 Entry.ArrayIndex = Imag;
379 Entries.push_back(Entry);
380
381 // This is technically a most-derived object, though in practice this
382 // is unlikely to matter.
383 MostDerivedType = EltTy;
384 MostDerivedIsArrayElement = true;
385 MostDerivedArraySize = 2;
386 MostDerivedPathLength = Entries.size();
387 }
388 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
389 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
390 const APSInt &N);
391 /// Add N to the address of this subobject.
392 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
393 if (Invalid || !N) return;
394 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
395 if (isMostDerivedAnUnsizedArray()) {
396 diagnoseUnsizedArrayPointerArithmetic(Info, E);
397 // Can't verify -- trust that the user is doing the right thing (or if
398 // not, trust that the caller will catch the bad behavior).
399 // FIXME: Should we reject if this overflows, at least?
400 Entries.back().ArrayIndex += TruncatedN;
401 return;
402 }
403
404 // [expr.add]p4: For the purposes of these operators, a pointer to a
405 // nonarray object behaves the same as a pointer to the first element of
406 // an array of length one with the type of the object as its element type.
407 bool IsArray = MostDerivedPathLength == Entries.size() &&
408 MostDerivedIsArrayElement;
409 uint64_t ArrayIndex =
410 IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
411 uint64_t ArraySize =
412 IsArray ? getMostDerivedArraySize() : (uint64_t)1;
413
414 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
415 // Calculate the actual index in a wide enough type, so we can include
416 // it in the note.
417 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
418 (llvm::APInt&)N += ArrayIndex;
419 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index")(static_cast <bool> (N.ugt(ArraySize) && "bounds check failed for in-bounds index"
) ? void (0) : __assert_fail ("N.ugt(ArraySize) && \"bounds check failed for in-bounds index\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 419, __extension__ __PRETTY_FUNCTION__))
;
420 diagnosePointerArithmetic(Info, E, N);
421 setInvalid();
422 return;
423 }
424
425 ArrayIndex += TruncatedN;
426 assert(ArrayIndex <= ArraySize &&(static_cast <bool> (ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index") ? void (0)
: __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 427, __extension__ __PRETTY_FUNCTION__))
427 "bounds check succeeded for out-of-bounds index")(static_cast <bool> (ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index") ? void (0)
: __assert_fail ("ArrayIndex <= ArraySize && \"bounds check succeeded for out-of-bounds index\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 427, __extension__ __PRETTY_FUNCTION__))
;
428
429 if (IsArray)
430 Entries.back().ArrayIndex = ArrayIndex;
431 else
432 IsOnePastTheEnd = (ArrayIndex != 0);
433 }
434 };
435
436 /// A stack frame in the constexpr call stack.
437 struct CallStackFrame {
438 EvalInfo &Info;
439
440 /// Parent - The caller of this stack frame.
441 CallStackFrame *Caller;
442
443 /// Callee - The function which was called.
444 const FunctionDecl *Callee;
445
446 /// This - The binding for the this pointer in this call, if any.
447 const LValue *This;
448
449 /// Arguments - Parameter bindings for this function call, indexed by
450 /// parameters' function scope indices.
451 APValue *Arguments;
452
453 // Note that we intentionally use std::map here so that references to
454 // values are stable.
455 typedef std::pair<const void *, unsigned> MapKeyTy;
456 typedef std::map<MapKeyTy, APValue> MapTy;
457 /// Temporaries - Temporary lvalues materialized within this stack frame.
458 MapTy Temporaries;
459
460 /// CallLoc - The location of the call expression for this call.
461 SourceLocation CallLoc;
462
463 /// Index - The call index of this call.
464 unsigned Index;
465
466 /// The stack of integers for tracking version numbers for temporaries.
467 SmallVector<unsigned, 2> TempVersionStack = {1};
468 unsigned CurTempVersion = TempVersionStack.back();
469
470 unsigned getTempVersion() const { return TempVersionStack.back(); }
471
472 void pushTempVersion() {
473 TempVersionStack.push_back(++CurTempVersion);
474 }
475
476 void popTempVersion() {
477 TempVersionStack.pop_back();
478 }
479
480 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
481 // on the overall stack usage of deeply-recursing constexpr evaluataions.
482 // (We should cache this map rather than recomputing it repeatedly.)
483 // But let's try this and see how it goes; we can look into caching the map
484 // as a later change.
485
486 /// LambdaCaptureFields - Mapping from captured variables/this to
487 /// corresponding data members in the closure class.
488 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
489 FieldDecl *LambdaThisCaptureField;
490
491 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
492 const FunctionDecl *Callee, const LValue *This,
493 APValue *Arguments);
494 ~CallStackFrame();
495
496 // Return the temporary for Key whose version number is Version.
497 APValue *getTemporary(const void *Key, unsigned Version) {
498 MapKeyTy KV(Key, Version);
499 auto LB = Temporaries.lower_bound(KV);
500 if (LB != Temporaries.end() && LB->first == KV)
501 return &LB->second;
502 // Pair (Key,Version) wasn't found in the map. Check that no elements
503 // in the map have 'Key' as their key.
504 assert((LB == Temporaries.end() || LB->first.first != Key) &&(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? void (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 506, __extension__ __PRETTY_FUNCTION__))
505 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? void (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 506, __extension__ __PRETTY_FUNCTION__))
506 "Element with key 'Key' found in map")(static_cast <bool> ((LB == Temporaries.end() || LB->
first.first != Key) && (LB == Temporaries.begin() || std
::prev(LB)->first.first != Key) && "Element with key 'Key' found in map"
) ? void (0) : __assert_fail ("(LB == Temporaries.end() || LB->first.first != Key) && (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && \"Element with key 'Key' found in map\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 506, __extension__ __PRETTY_FUNCTION__))
;
507 return nullptr;
508 }
509
510 // Return the current temporary for Key in the map.
511 APValue *getCurrentTemporary(const void *Key) {
512 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
513 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
514 return &std::prev(UB)->second;
515 return nullptr;
516 }
517
518 // Return the version number of the current temporary for Key.
519 unsigned getCurrentTemporaryVersion(const void *Key) const {
520 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX(2147483647 *2U +1U)));
521 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
522 return std::prev(UB)->first.second;
523 return 0;
524 }
525
526 APValue &createTemporary(const void *Key, bool IsLifetimeExtended);
527 };
528
529 /// Temporarily override 'this'.
530 class ThisOverrideRAII {
531 public:
532 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
533 : Frame(Frame), OldThis(Frame.This) {
534 if (Enable)
535 Frame.This = NewThis;
536 }
537 ~ThisOverrideRAII() {
538 Frame.This = OldThis;
539 }
540 private:
541 CallStackFrame &Frame;
542 const LValue *OldThis;
543 };
544
545 /// A partial diagnostic which we might know in advance that we are not going
546 /// to emit.
547 class OptionalDiagnostic {
548 PartialDiagnostic *Diag;
549
550 public:
551 explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr)
552 : Diag(Diag) {}
553
554 template<typename T>
555 OptionalDiagnostic &operator<<(const T &v) {
556 if (Diag)
557 *Diag << v;
558 return *this;
559 }
560
561 OptionalDiagnostic &operator<<(const APSInt &I) {
562 if (Diag) {
563 SmallVector<char, 32> Buffer;
564 I.toString(Buffer);
565 *Diag << StringRef(Buffer.data(), Buffer.size());
566 }
567 return *this;
568 }
569
570 OptionalDiagnostic &operator<<(const APFloat &F) {
571 if (Diag) {
572 // FIXME: Force the precision of the source value down so we don't
573 // print digits which are usually useless (we don't really care here if
574 // we truncate a digit by accident in edge cases). Ideally,
575 // APFloat::toString would automatically print the shortest
576 // representation which rounds to the correct value, but it's a bit
577 // tricky to implement.
578 unsigned precision =
579 llvm::APFloat::semanticsPrecision(F.getSemantics());
580 precision = (precision * 59 + 195) / 196;
581 SmallVector<char, 32> Buffer;
582 F.toString(Buffer, precision);
583 *Diag << StringRef(Buffer.data(), Buffer.size());
584 }
585 return *this;
586 }
587 };
588
589 /// A cleanup, and a flag indicating whether it is lifetime-extended.
590 class Cleanup {
591 llvm::PointerIntPair<APValue*, 1, bool> Value;
592
593 public:
594 Cleanup(APValue *Val, bool IsLifetimeExtended)
595 : Value(Val, IsLifetimeExtended) {}
596
597 bool isLifetimeExtended() const { return Value.getInt(); }
598 void endLifetime() {
599 *Value.getPointer() = APValue();
600 }
601 };
602
603 /// EvalInfo - This is a private struct used by the evaluator to capture
604 /// information about a subexpression as it is folded. It retains information
605 /// about the AST context, but also maintains information about the folded
606 /// expression.
607 ///
608 /// If an expression could be evaluated, it is still possible it is not a C
609 /// "integer constant expression" or constant expression. If not, this struct
610 /// captures information about how and why not.
611 ///
612 /// One bit of information passed *into* the request for constant folding
613 /// indicates whether the subexpression is "evaluated" or not according to C
614 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
615 /// evaluate the expression regardless of what the RHS is, but C only allows
616 /// certain things in certain situations.
617 struct EvalInfo {
618 ASTContext &Ctx;
619
620 /// EvalStatus - Contains information about the evaluation.
621 Expr::EvalStatus &EvalStatus;
622
623 /// CurrentCall - The top of the constexpr call stack.
624 CallStackFrame *CurrentCall;
625
626 /// CallStackDepth - The number of calls in the call stack right now.
627 unsigned CallStackDepth;
628
629 /// NextCallIndex - The next call index to assign.
630 unsigned NextCallIndex;
631
632 /// StepsLeft - The remaining number of evaluation steps we're permitted
633 /// to perform. This is essentially a limit for the number of statements
634 /// we will evaluate.
635 unsigned StepsLeft;
636
637 /// BottomFrame - The frame in which evaluation started. This must be
638 /// initialized after CurrentCall and CallStackDepth.
639 CallStackFrame BottomFrame;
640
641 /// A stack of values whose lifetimes end at the end of some surrounding
642 /// evaluation frame.
643 llvm::SmallVector<Cleanup, 16> CleanupStack;
644
645 /// EvaluatingDecl - This is the declaration whose initializer is being
646 /// evaluated, if any.
647 APValue::LValueBase EvaluatingDecl;
648
649 /// EvaluatingDeclValue - This is the value being constructed for the
650 /// declaration whose initializer is being evaluated, if any.
651 APValue *EvaluatingDeclValue;
652
653 /// EvaluatingObject - Pair of the AST node that an lvalue represents and
654 /// the call index that that lvalue was allocated in.
655 typedef std::pair<APValue::LValueBase, std::pair<unsigned, unsigned>>
656 EvaluatingObject;
657
658 /// EvaluatingConstructors - Set of objects that are currently being
659 /// constructed.
660 llvm::DenseSet<EvaluatingObject> EvaluatingConstructors;
661
662 struct EvaluatingConstructorRAII {
663 EvalInfo &EI;
664 EvaluatingObject Object;
665 bool DidInsert;
666 EvaluatingConstructorRAII(EvalInfo &EI, EvaluatingObject Object)
667 : EI(EI), Object(Object) {
668 DidInsert = EI.EvaluatingConstructors.insert(Object).second;
669 }
670 ~EvaluatingConstructorRAII() {
671 if (DidInsert) EI.EvaluatingConstructors.erase(Object);
672 }
673 };
674
675 bool isEvaluatingConstructor(APValue::LValueBase Decl, unsigned CallIndex,
676 unsigned Version) {
677 return EvaluatingConstructors.count(
678 EvaluatingObject(Decl, {CallIndex, Version}));
679 }
680
681 /// The current array initialization index, if we're performing array
682 /// initialization.
683 uint64_t ArrayInitIndex = -1;
684
685 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
686 /// notes attached to it will also be stored, otherwise they will not be.
687 bool HasActiveDiagnostic;
688
689 /// Have we emitted a diagnostic explaining why we couldn't constant
690 /// fold (not just why it's not strictly a constant expression)?
691 bool HasFoldFailureDiagnostic;
692
693 /// Whether or not we're currently speculatively evaluating.
694 bool IsSpeculativelyEvaluating;
695
696 enum EvaluationMode {
697 /// Evaluate as a constant expression. Stop if we find that the expression
698 /// is not a constant expression.
699 EM_ConstantExpression,
700
701 /// Evaluate as a potential constant expression. Keep going if we hit a
702 /// construct that we can't evaluate yet (because we don't yet know the
703 /// value of something) but stop if we hit something that could never be
704 /// a constant expression.
705 EM_PotentialConstantExpression,
706
707 /// Fold the expression to a constant. Stop if we hit a side-effect that
708 /// we can't model.
709 EM_ConstantFold,
710
711 /// Evaluate the expression looking for integer overflow and similar
712 /// issues. Don't worry about side-effects, and try to visit all
713 /// subexpressions.
714 EM_EvaluateForOverflow,
715
716 /// Evaluate in any way we know how. Don't worry about side-effects that
717 /// can't be modeled.
718 EM_IgnoreSideEffects,
719
720 /// Evaluate as a constant expression. Stop if we find that the expression
721 /// is not a constant expression. Some expressions can be retried in the
722 /// optimizer if we don't constant fold them here, but in an unevaluated
723 /// context we try to fold them immediately since the optimizer never
724 /// gets a chance to look at it.
725 EM_ConstantExpressionUnevaluated,
726
727 /// Evaluate as a potential constant expression. Keep going if we hit a
728 /// construct that we can't evaluate yet (because we don't yet know the
729 /// value of something) but stop if we hit something that could never be
730 /// a constant expression. Some expressions can be retried in the
731 /// optimizer if we don't constant fold them here, but in an unevaluated
732 /// context we try to fold them immediately since the optimizer never
733 /// gets a chance to look at it.
734 EM_PotentialConstantExpressionUnevaluated,
735
736 /// Evaluate as a constant expression. In certain scenarios, if:
737 /// - we find a MemberExpr with a base that can't be evaluated, or
738 /// - we find a variable initialized with a call to a function that has
739 /// the alloc_size attribute on it
740 /// then we may consider evaluation to have succeeded.
741 ///
742 /// In either case, the LValue returned shall have an invalid base; in the
743 /// former, the base will be the invalid MemberExpr, in the latter, the
744 /// base will be either the alloc_size CallExpr or a CastExpr wrapping
745 /// said CallExpr.
746 EM_OffsetFold,
747 } EvalMode;
748
749 /// Are we checking whether the expression is a potential constant
750 /// expression?
751 bool checkingPotentialConstantExpression() const {
752 return EvalMode == EM_PotentialConstantExpression ||
753 EvalMode == EM_PotentialConstantExpressionUnevaluated;
754 }
755
756 /// Are we checking an expression for overflow?
757 // FIXME: We should check for any kind of undefined or suspicious behavior
758 // in such constructs, not just overflow.
759 bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; }
760
761 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
762 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
763 CallStackDepth(0), NextCallIndex(1),
764 StepsLeft(getLangOpts().ConstexprStepLimit),
765 BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr),
766 EvaluatingDecl((const ValueDecl *)nullptr),
767 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
768 HasFoldFailureDiagnostic(false), IsSpeculativelyEvaluating(false),
769 EvalMode(Mode) {}
770
771 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
772 EvaluatingDecl = Base;
773 EvaluatingDeclValue = &Value;
774 EvaluatingConstructors.insert({Base, {0, 0}});
775 }
776
777 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
778
779 bool CheckCallLimit(SourceLocation Loc) {
780 // Don't perform any constexpr calls (other than the call we're checking)
781 // when checking a potential constant expression.
782 if (checkingPotentialConstantExpression() && CallStackDepth > 1)
783 return false;
784 if (NextCallIndex == 0) {
785 // NextCallIndex has wrapped around.
786 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
787 return false;
788 }
789 if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
790 return true;
791 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
792 << getLangOpts().ConstexprCallDepth;
793 return false;
794 }
795
796 CallStackFrame *getCallFrame(unsigned CallIndex) {
797 assert(CallIndex && "no call index in getCallFrame")(static_cast <bool> (CallIndex && "no call index in getCallFrame"
) ? void (0) : __assert_fail ("CallIndex && \"no call index in getCallFrame\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 797, __extension__ __PRETTY_FUNCTION__))
;
798 // We will eventually hit BottomFrame, which has Index 1, so Frame can't
799 // be null in this loop.
800 CallStackFrame *Frame = CurrentCall;
801 while (Frame->Index > CallIndex)
802 Frame = Frame->Caller;
803 return (Frame->Index == CallIndex) ? Frame : nullptr;
804 }
805
806 bool nextStep(const Stmt *S) {
807 if (!StepsLeft) {
808 FFDiag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded);
809 return false;
810 }
811 --StepsLeft;
812 return true;
813 }
814
815 private:
816 /// Add a diagnostic to the diagnostics list.
817 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) {
818 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator());
819 EvalStatus.Diag->push_back(std::make_pair(Loc, PD));
820 return EvalStatus.Diag->back().second;
821 }
822
823 /// Add notes containing a call stack to the current point of evaluation.
824 void addCallStack(unsigned Limit);
825
826 private:
827 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId,
828 unsigned ExtraNotes, bool IsCCEDiag) {
829
830 if (EvalStatus.Diag) {
831 // If we have a prior diagnostic, it will be noting that the expression
832 // isn't a constant expression. This diagnostic is more important,
833 // unless we require this evaluation to produce a constant expression.
834 //
835 // FIXME: We might want to show both diagnostics to the user in
836 // EM_ConstantFold mode.
837 if (!EvalStatus.Diag->empty()) {
838 switch (EvalMode) {
839 case EM_ConstantFold:
840 case EM_IgnoreSideEffects:
841 case EM_EvaluateForOverflow:
842 if (!HasFoldFailureDiagnostic)
843 break;
844 // We've already failed to fold something. Keep that diagnostic.
845 LLVM_FALLTHROUGH[[clang::fallthrough]];
846 case EM_ConstantExpression:
847 case EM_PotentialConstantExpression:
848 case EM_ConstantExpressionUnevaluated:
849 case EM_PotentialConstantExpressionUnevaluated:
850 case EM_OffsetFold:
851 HasActiveDiagnostic = false;
852 return OptionalDiagnostic();
853 }
854 }
855
856 unsigned CallStackNotes = CallStackDepth - 1;
857 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit();
858 if (Limit)
859 CallStackNotes = std::min(CallStackNotes, Limit + 1);
860 if (checkingPotentialConstantExpression())
861 CallStackNotes = 0;
862
863 HasActiveDiagnostic = true;
864 HasFoldFailureDiagnostic = !IsCCEDiag;
865 EvalStatus.Diag->clear();
866 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes);
867 addDiag(Loc, DiagId);
868 if (!checkingPotentialConstantExpression())
869 addCallStack(Limit);
870 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second);
871 }
872 HasActiveDiagnostic = false;
873 return OptionalDiagnostic();
874 }
875 public:
876 // Diagnose that the evaluation could not be folded (FF => FoldFailure)
877 OptionalDiagnostic
878 FFDiag(SourceLocation Loc,
879 diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
880 unsigned ExtraNotes = 0) {
881 return Diag(Loc, DiagId, ExtraNotes, false);
882 }
883
884 OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId
885 = diag::note_invalid_subexpr_in_const_expr,
886 unsigned ExtraNotes = 0) {
887 if (EvalStatus.Diag)
888 return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false);
889 HasActiveDiagnostic = false;
890 return OptionalDiagnostic();
891 }
892
893 /// Diagnose that the evaluation does not produce a C++11 core constant
894 /// expression.
895 ///
896 /// FIXME: Stop evaluating if we're in EM_ConstantExpression or
897 /// EM_PotentialConstantExpression mode and we produce one of these.
898 OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId
899 = diag::note_invalid_subexpr_in_const_expr,
900 unsigned ExtraNotes = 0) {
901 // Don't override a previous diagnostic. Don't bother collecting
902 // diagnostics if we're evaluating for overflow.
903 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) {
904 HasActiveDiagnostic = false;
905 return OptionalDiagnostic();
906 }
907 return Diag(Loc, DiagId, ExtraNotes, true);
908 }
909 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId
910 = diag::note_invalid_subexpr_in_const_expr,
911 unsigned ExtraNotes = 0) {
912 return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes);
913 }
914 /// Add a note to a prior diagnostic.
915 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) {
916 if (!HasActiveDiagnostic)
917 return OptionalDiagnostic();
918 return OptionalDiagnostic(&addDiag(Loc, DiagId));
919 }
920
921 /// Add a stack of notes to a prior diagnostic.
922 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) {
923 if (HasActiveDiagnostic) {
924 EvalStatus.Diag->insert(EvalStatus.Diag->end(),
925 Diags.begin(), Diags.end());
926 }
927 }
928
929 /// Should we continue evaluation after encountering a side-effect that we
930 /// couldn't model?
931 bool keepEvaluatingAfterSideEffect() {
932 switch (EvalMode) {
933 case EM_PotentialConstantExpression:
934 case EM_PotentialConstantExpressionUnevaluated:
935 case EM_EvaluateForOverflow:
936 case EM_IgnoreSideEffects:
937 return true;
938
939 case EM_ConstantExpression:
940 case EM_ConstantExpressionUnevaluated:
941 case EM_ConstantFold:
942 case EM_OffsetFold:
943 return false;
944 }
945 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 945)
;
946 }
947
948 /// Note that we have had a side-effect, and determine whether we should
949 /// keep evaluating.
950 bool noteSideEffect() {
951 EvalStatus.HasSideEffects = true;
952 return keepEvaluatingAfterSideEffect();
953 }
954
955 /// Should we continue evaluation after encountering undefined behavior?
956 bool keepEvaluatingAfterUndefinedBehavior() {
957 switch (EvalMode) {
958 case EM_EvaluateForOverflow:
959 case EM_IgnoreSideEffects:
960 case EM_ConstantFold:
961 case EM_OffsetFold:
962 return true;
963
964 case EM_PotentialConstantExpression:
965 case EM_PotentialConstantExpressionUnevaluated:
966 case EM_ConstantExpression:
967 case EM_ConstantExpressionUnevaluated:
968 return false;
969 }
970 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 970)
;
971 }
972
973 /// Note that we hit something that was technically undefined behavior, but
974 /// that we can evaluate past it (such as signed overflow or floating-point
975 /// division by zero.)
976 bool noteUndefinedBehavior() {
977 EvalStatus.HasUndefinedBehavior = true;
978 return keepEvaluatingAfterUndefinedBehavior();
979 }
980
981 /// Should we continue evaluation as much as possible after encountering a
982 /// construct which can't be reduced to a value?
983 bool keepEvaluatingAfterFailure() {
984 if (!StepsLeft)
985 return false;
986
987 switch (EvalMode) {
988 case EM_PotentialConstantExpression:
989 case EM_PotentialConstantExpressionUnevaluated:
990 case EM_EvaluateForOverflow:
991 return true;
992
993 case EM_ConstantExpression:
994 case EM_ConstantExpressionUnevaluated:
995 case EM_ConstantFold:
996 case EM_IgnoreSideEffects:
997 case EM_OffsetFold:
998 return false;
999 }
1000 llvm_unreachable("Missed EvalMode case")::llvm::llvm_unreachable_internal("Missed EvalMode case", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1000)
;
1001 }
1002
1003 /// Notes that we failed to evaluate an expression that other expressions
1004 /// directly depend on, and determine if we should keep evaluating. This
1005 /// should only be called if we actually intend to keep evaluating.
1006 ///
1007 /// Call noteSideEffect() instead if we may be able to ignore the value that
1008 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1009 ///
1010 /// (Foo(), 1) // use noteSideEffect
1011 /// (Foo() || true) // use noteSideEffect
1012 /// Foo() + 1 // use noteFailure
1013 LLVM_NODISCARD[[clang::warn_unused_result]] bool noteFailure() {
1014 // Failure when evaluating some expression often means there is some
1015 // subexpression whose evaluation was skipped. Therefore, (because we
1016 // don't track whether we skipped an expression when unwinding after an
1017 // evaluation failure) every evaluation failure that bubbles up from a
1018 // subexpression implies that a side-effect has potentially happened. We
1019 // skip setting the HasSideEffects flag to true until we decide to
1020 // continue evaluating after that point, which happens here.
1021 bool KeepGoing = keepEvaluatingAfterFailure();
1022 EvalStatus.HasSideEffects |= KeepGoing;
1023 return KeepGoing;
1024 }
1025
1026 class ArrayInitLoopIndex {
1027 EvalInfo &Info;
1028 uint64_t OuterIndex;
1029
1030 public:
1031 ArrayInitLoopIndex(EvalInfo &Info)
1032 : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1033 Info.ArrayInitIndex = 0;
1034 }
1035 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1036
1037 operator uint64_t&() { return Info.ArrayInitIndex; }
1038 };
1039 };
1040
1041 /// Object used to treat all foldable expressions as constant expressions.
1042 struct FoldConstant {
1043 EvalInfo &Info;
1044 bool Enabled;
1045 bool HadNoPriorDiags;
1046 EvalInfo::EvaluationMode OldMode;
1047
1048 explicit FoldConstant(EvalInfo &Info, bool Enabled)
1049 : Info(Info),
1050 Enabled(Enabled),
1051 HadNoPriorDiags(Info.EvalStatus.Diag &&
1052 Info.EvalStatus.Diag->empty() &&
1053 !Info.EvalStatus.HasSideEffects),
1054 OldMode(Info.EvalMode) {
1055 if (Enabled &&
1056 (Info.EvalMode == EvalInfo::EM_ConstantExpression ||
1057 Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated))
1058 Info.EvalMode = EvalInfo::EM_ConstantFold;
1059 }
1060 void keepDiagnostics() { Enabled = false; }
1061 ~FoldConstant() {
1062 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1063 !Info.EvalStatus.HasSideEffects)
1064 Info.EvalStatus.Diag->clear();
1065 Info.EvalMode = OldMode;
1066 }
1067 };
1068
1069 /// RAII object used to treat the current evaluation as the correct pointer
1070 /// offset fold for the current EvalMode
1071 struct FoldOffsetRAII {
1072 EvalInfo &Info;
1073 EvalInfo::EvaluationMode OldMode;
1074 explicit FoldOffsetRAII(EvalInfo &Info)
1075 : Info(Info), OldMode(Info.EvalMode) {
1076 if (!Info.checkingPotentialConstantExpression())
1077 Info.EvalMode = EvalInfo::EM_OffsetFold;
1078 }
1079
1080 ~FoldOffsetRAII() { Info.EvalMode = OldMode; }
1081 };
1082
1083 /// RAII object used to optionally suppress diagnostics and side-effects from
1084 /// a speculative evaluation.
1085 class SpeculativeEvaluationRAII {
1086 EvalInfo *Info = nullptr;
1087 Expr::EvalStatus OldStatus;
1088 bool OldIsSpeculativelyEvaluating;
1089
1090 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1091 Info = Other.Info;
1092 OldStatus = Other.OldStatus;
1093 OldIsSpeculativelyEvaluating = Other.OldIsSpeculativelyEvaluating;
1094 Other.Info = nullptr;
1095 }
1096
1097 void maybeRestoreState() {
1098 if (!Info)
1099 return;
1100
1101 Info->EvalStatus = OldStatus;
1102 Info->IsSpeculativelyEvaluating = OldIsSpeculativelyEvaluating;
1103 }
1104
1105 public:
1106 SpeculativeEvaluationRAII() = default;
1107
1108 SpeculativeEvaluationRAII(
1109 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1110 : Info(&Info), OldStatus(Info.EvalStatus),
1111 OldIsSpeculativelyEvaluating(Info.IsSpeculativelyEvaluating) {
1112 Info.EvalStatus.Diag = NewDiag;
1113 Info.IsSpeculativelyEvaluating = true;
1114 }
1115
1116 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1117 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1118 moveFromAndCancel(std::move(Other));
1119 }
1120
1121 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1122 maybeRestoreState();
1123 moveFromAndCancel(std::move(Other));
1124 return *this;
1125 }
1126
1127 ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1128 };
1129
1130 /// RAII object wrapping a full-expression or block scope, and handling
1131 /// the ending of the lifetime of temporaries created within it.
1132 template<bool IsFullExpression>
1133 class ScopeRAII {
1134 EvalInfo &Info;
1135 unsigned OldStackSize;
1136 public:
1137 ScopeRAII(EvalInfo &Info)
1138 : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1139 // Push a new temporary version. This is needed to distinguish between
1140 // temporaries created in different iterations of a loop.
1141 Info.CurrentCall->pushTempVersion();
1142 }
1143 ~ScopeRAII() {
1144 // Body moved to a static method to encourage the compiler to inline away
1145 // instances of this class.
1146 cleanup(Info, OldStackSize);
1147 Info.CurrentCall->popTempVersion();
1148 }
1149 private:
1150 static void cleanup(EvalInfo &Info, unsigned OldStackSize) {
1151 unsigned NewEnd = OldStackSize;
1152 for (unsigned I = OldStackSize, N = Info.CleanupStack.size();
1153 I != N; ++I) {
1154 if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) {
1155 // Full-expression cleanup of a lifetime-extended temporary: nothing
1156 // to do, just move this cleanup to the right place in the stack.
1157 std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]);
1158 ++NewEnd;
1159 } else {
1160 // End the lifetime of the object.
1161 Info.CleanupStack[I].endLifetime();
1162 }
1163 }
1164 Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd,
1165 Info.CleanupStack.end());
1166 }
1167 };
1168 typedef ScopeRAII<false> BlockScopeRAII;
1169 typedef ScopeRAII<true> FullExpressionRAII;
1170}
1171
1172bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1173 CheckSubobjectKind CSK) {
1174 if (Invalid)
1175 return false;
1176 if (isOnePastTheEnd()) {
1177 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1178 << CSK;
1179 setInvalid();
1180 return false;
1181 }
1182 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1183 // must actually be at least one array element; even a VLA cannot have a
1184 // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1185 return true;
1186}
1187
1188void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1189 const Expr *E) {
1190 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1191 // Do not set the designator as invalid: we can represent this situation,
1192 // and correct handling of __builtin_object_size requires us to do so.
1193}
1194
1195void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1196 const Expr *E,
1197 const APSInt &N) {
1198 // If we're complaining, we must be able to statically determine the size of
1199 // the most derived array.
1200 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1201 Info.CCEDiag(E, diag::note_constexpr_array_index)
1202 << N << /*array*/ 0
1203 << static_cast<unsigned>(getMostDerivedArraySize());
1204 else
1205 Info.CCEDiag(E, diag::note_constexpr_array_index)
1206 << N << /*non-array*/ 1;
1207 setInvalid();
1208}
1209
1210CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1211 const FunctionDecl *Callee, const LValue *This,
1212 APValue *Arguments)
1213 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1214 Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1215 Info.CurrentCall = this;
1216 ++Info.CallStackDepth;
1217}
1218
1219CallStackFrame::~CallStackFrame() {
1220 assert(Info.CurrentCall == this && "calls retired out of order")(static_cast <bool> (Info.CurrentCall == this &&
"calls retired out of order") ? void (0) : __assert_fail ("Info.CurrentCall == this && \"calls retired out of order\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1220, __extension__ __PRETTY_FUNCTION__))
;
1221 --Info.CallStackDepth;
1222 Info.CurrentCall = Caller;
1223}
1224
1225APValue &CallStackFrame::createTemporary(const void *Key,
1226 bool IsLifetimeExtended) {
1227 unsigned Version = Info.CurrentCall->getTempVersion();
1228 APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1229 assert(Result.isUninit() && "temporary created multiple times")(static_cast <bool> (Result.isUninit() && "temporary created multiple times"
) ? void (0) : __assert_fail ("Result.isUninit() && \"temporary created multiple times\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1229, __extension__ __PRETTY_FUNCTION__))
;
1230 Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended));
1231 return Result;
1232}
1233
1234static void describeCall(CallStackFrame *Frame, raw_ostream &Out);
1235
1236void EvalInfo::addCallStack(unsigned Limit) {
1237 // Determine which calls to skip, if any.
1238 unsigned ActiveCalls = CallStackDepth - 1;
1239 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart;
1240 if (Limit && Limit < ActiveCalls) {
1241 SkipStart = Limit / 2 + Limit % 2;
1242 SkipEnd = ActiveCalls - Limit / 2;
1243 }
1244
1245 // Walk the call stack and add the diagnostics.
1246 unsigned CallIdx = 0;
1247 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame;
1248 Frame = Frame->Caller, ++CallIdx) {
1249 // Skip this call?
1250 if (CallIdx >= SkipStart && CallIdx < SkipEnd) {
1251 if (CallIdx == SkipStart) {
1252 // Note that we're skipping calls.
1253 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed)
1254 << unsigned(ActiveCalls - Limit);
1255 }
1256 continue;
1257 }
1258
1259 // Use a different note for an inheriting constructor, because from the
1260 // user's perspective it's not really a function at all.
1261 if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) {
1262 if (CD->isInheritingConstructor()) {
1263 addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here)
1264 << CD->getParent();
1265 continue;
1266 }
1267 }
1268
1269 SmallVector<char, 128> Buffer;
1270 llvm::raw_svector_ostream Out(Buffer);
1271 describeCall(Frame, Out);
1272 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str();
1273 }
1274}
1275
1276namespace {
1277 struct ComplexValue {
1278 private:
1279 bool IsInt;
1280
1281 public:
1282 APSInt IntReal, IntImag;
1283 APFloat FloatReal, FloatImag;
1284
1285 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1286
1287 void makeComplexFloat() { IsInt = false; }
1288 bool isComplexFloat() const { return !IsInt; }
1289 APFloat &getComplexFloatReal() { return FloatReal; }
1290 APFloat &getComplexFloatImag() { return FloatImag; }
1291
1292 void makeComplexInt() { IsInt = true; }
1293 bool isComplexInt() const { return IsInt; }
1294 APSInt &getComplexIntReal() { return IntReal; }
1295 APSInt &getComplexIntImag() { return IntImag; }
1296
1297 void moveInto(APValue &v) const {
1298 if (isComplexFloat())
1299 v = APValue(FloatReal, FloatImag);
1300 else
1301 v = APValue(IntReal, IntImag);
1302 }
1303 void setFrom(const APValue &v) {
1304 assert(v.isComplexFloat() || v.isComplexInt())(static_cast <bool> (v.isComplexFloat() || v.isComplexInt
()) ? void (0) : __assert_fail ("v.isComplexFloat() || v.isComplexInt()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1304, __extension__ __PRETTY_FUNCTION__))
;
1305 if (v.isComplexFloat()) {
1306 makeComplexFloat();
1307 FloatReal = v.getComplexFloatReal();
1308 FloatImag = v.getComplexFloatImag();
1309 } else {
1310 makeComplexInt();
1311 IntReal = v.getComplexIntReal();
1312 IntImag = v.getComplexIntImag();
1313 }
1314 }
1315 };
1316
1317 struct LValue {
1318 APValue::LValueBase Base;
1319 CharUnits Offset;
1320 SubobjectDesignator Designator;
1321 bool IsNullPtr : 1;
1322 bool InvalidBase : 1;
1323
1324 const APValue::LValueBase getLValueBase() const { return Base; }
1325 CharUnits &getLValueOffset() { return Offset; }
1326 const CharUnits &getLValueOffset() const { return Offset; }
1327 SubobjectDesignator &getLValueDesignator() { return Designator; }
1328 const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1329 bool isNullPointer() const { return IsNullPtr;}
1330
1331 unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1332 unsigned getLValueVersion() const { return Base.getVersion(); }
1333
1334 void moveInto(APValue &V) const {
1335 if (Designator.Invalid)
1336 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1337 else {
1338 assert(!InvalidBase && "APValues can't handle invalid LValue bases")(static_cast <bool> (!InvalidBase && "APValues can't handle invalid LValue bases"
) ? void (0) : __assert_fail ("!InvalidBase && \"APValues can't handle invalid LValue bases\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1338, __extension__ __PRETTY_FUNCTION__))
;
1339 V = APValue(Base, Offset, Designator.Entries,
1340 Designator.IsOnePastTheEnd, IsNullPtr);
1341 }
1342 }
1343 void setFrom(ASTContext &Ctx, const APValue &V) {
1344 assert(V.isLValue() && "Setting LValue from a non-LValue?")(static_cast <bool> (V.isLValue() && "Setting LValue from a non-LValue?"
) ? void (0) : __assert_fail ("V.isLValue() && \"Setting LValue from a non-LValue?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1344, __extension__ __PRETTY_FUNCTION__))
;
1345 Base = V.getLValueBase();
1346 Offset = V.getLValueOffset();
1347 InvalidBase = false;
1348 Designator = SubobjectDesignator(Ctx, V);
1349 IsNullPtr = V.isNullPointer();
1350 }
1351
1352 void set(APValue::LValueBase B, bool BInvalid = false) {
1353#ifndef NDEBUG
1354 // We only allow a few types of invalid bases. Enforce that here.
1355 if (BInvalid) {
1356 const auto *E = B.get<const Expr *>();
1357 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&(static_cast <bool> ((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall
(E)) && "Unexpected type of invalid base") ? void (0)
: __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1358, __extension__ __PRETTY_FUNCTION__))
1358 "Unexpected type of invalid base")(static_cast <bool> ((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall
(E)) && "Unexpected type of invalid base") ? void (0)
: __assert_fail ("(isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && \"Unexpected type of invalid base\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1358, __extension__ __PRETTY_FUNCTION__))
;
1359 }
1360#endif
1361
1362 Base = B;
1363 Offset = CharUnits::fromQuantity(0);
1364 InvalidBase = BInvalid;
1365 Designator = SubobjectDesignator(getType(B));
1366 IsNullPtr = false;
1367 }
1368
1369 void setNull(QualType PointerTy, uint64_t TargetVal) {
1370 Base = (Expr *)nullptr;
1371 Offset = CharUnits::fromQuantity(TargetVal);
1372 InvalidBase = false;
1373 Designator = SubobjectDesignator(PointerTy->getPointeeType());
1374 IsNullPtr = true;
1375 }
1376
1377 void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1378 set(B, true);
1379 }
1380
1381 // Check that this LValue is not based on a null pointer. If it is, produce
1382 // a diagnostic and mark the designator as invalid.
1383 bool checkNullPointer(EvalInfo &Info, const Expr *E,
1384 CheckSubobjectKind CSK) {
1385 if (Designator.Invalid)
1386 return false;
1387 if (IsNullPtr) {
1388 Info.CCEDiag(E, diag::note_constexpr_null_subobject)
1389 << CSK;
1390 Designator.setInvalid();
1391 return false;
1392 }
1393 return true;
1394 }
1395
1396 // Check this LValue refers to an object. If not, set the designator to be
1397 // invalid and emit a diagnostic.
1398 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1399 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1400 Designator.checkSubobject(Info, E, CSK);
1401 }
1402
1403 void addDecl(EvalInfo &Info, const Expr *E,
1404 const Decl *D, bool Virtual = false) {
1405 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1406 Designator.addDeclUnchecked(D, Virtual);
1407 }
1408 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1409 if (!Designator.Entries.empty()) {
1410 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1411 Designator.setInvalid();
1412 return;
1413 }
1414 if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1415 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType())(static_cast <bool> (getType(Base)->isPointerType() ||
getType(Base)->isArrayType()) ? void (0) : __assert_fail (
"getType(Base)->isPointerType() || getType(Base)->isArrayType()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1415, __extension__ __PRETTY_FUNCTION__))
;
1416 Designator.FirstEntryIsAnUnsizedArray = true;
1417 Designator.addUnsizedArrayUnchecked(ElemTy);
1418 }
1419 }
1420 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1421 if (checkSubobject(Info, E, CSK_ArrayToPointer))
1422 Designator.addArrayUnchecked(CAT);
1423 }
1424 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1425 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1426 Designator.addComplexUnchecked(EltTy, Imag);
1427 }
1428 void clearIsNullPointer() {
1429 IsNullPtr = false;
1430 }
1431 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1432 const APSInt &Index, CharUnits ElementSize) {
1433 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1434 // but we're not required to diagnose it and it's valid in C++.)
1435 if (!Index)
1436 return;
1437
1438 // Compute the new offset in the appropriate width, wrapping at 64 bits.
1439 // FIXME: When compiling for a 32-bit target, we should use 32-bit
1440 // offsets.
1441 uint64_t Offset64 = Offset.getQuantity();
1442 uint64_t ElemSize64 = ElementSize.getQuantity();
1443 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1444 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1445
1446 if (checkNullPointer(Info, E, CSK_ArrayIndex))
1447 Designator.adjustIndex(Info, E, Index);
1448 clearIsNullPointer();
1449 }
1450 void adjustOffset(CharUnits N) {
1451 Offset += N;
1452 if (N.getQuantity())
1453 clearIsNullPointer();
1454 }
1455 };
1456
1457 struct MemberPtr {
1458 MemberPtr() {}
1459 explicit MemberPtr(const ValueDecl *Decl) :
1460 DeclAndIsDerivedMember(Decl, false), Path() {}
1461
1462 /// The member or (direct or indirect) field referred to by this member
1463 /// pointer, or 0 if this is a null member pointer.
1464 const ValueDecl *getDecl() const {
1465 return DeclAndIsDerivedMember.getPointer();
1466 }
1467 /// Is this actually a member of some type derived from the relevant class?
1468 bool isDerivedMember() const {
1469 return DeclAndIsDerivedMember.getInt();
1470 }
1471 /// Get the class which the declaration actually lives in.
1472 const CXXRecordDecl *getContainingRecord() const {
1473 return cast<CXXRecordDecl>(
1474 DeclAndIsDerivedMember.getPointer()->getDeclContext());
1475 }
1476
1477 void moveInto(APValue &V) const {
1478 V = APValue(getDecl(), isDerivedMember(), Path);
1479 }
1480 void setFrom(const APValue &V) {
1481 assert(V.isMemberPointer())(static_cast <bool> (V.isMemberPointer()) ? void (0) : __assert_fail
("V.isMemberPointer()", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1481, __extension__ __PRETTY_FUNCTION__))
;
1482 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1483 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1484 Path.clear();
1485 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
1486 Path.insert(Path.end(), P.begin(), P.end());
1487 }
1488
1489 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1490 /// whether the member is a member of some class derived from the class type
1491 /// of the member pointer.
1492 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1493 /// Path - The path of base/derived classes from the member declaration's
1494 /// class (exclusive) to the class type of the member pointer (inclusive).
1495 SmallVector<const CXXRecordDecl*, 4> Path;
1496
1497 /// Perform a cast towards the class of the Decl (either up or down the
1498 /// hierarchy).
1499 bool castBack(const CXXRecordDecl *Class) {
1500 assert(!Path.empty())(static_cast <bool> (!Path.empty()) ? void (0) : __assert_fail
("!Path.empty()", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1500, __extension__ __PRETTY_FUNCTION__))
;
1501 const CXXRecordDecl *Expected;
1502 if (Path.size() >= 2)
1503 Expected = Path[Path.size() - 2];
1504 else
1505 Expected = getContainingRecord();
1506 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1507 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1508 // if B does not contain the original member and is not a base or
1509 // derived class of the class containing the original member, the result
1510 // of the cast is undefined.
1511 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1512 // (D::*). We consider that to be a language defect.
1513 return false;
1514 }
1515 Path.pop_back();
1516 return true;
1517 }
1518 /// Perform a base-to-derived member pointer cast.
1519 bool castToDerived(const CXXRecordDecl *Derived) {
1520 if (!getDecl())
1521 return true;
1522 if (!isDerivedMember()) {
1523 Path.push_back(Derived);
1524 return true;
1525 }
1526 if (!castBack(Derived))
1527 return false;
1528 if (Path.empty())
1529 DeclAndIsDerivedMember.setInt(false);
1530 return true;
1531 }
1532 /// Perform a derived-to-base member pointer cast.
1533 bool castToBase(const CXXRecordDecl *Base) {
1534 if (!getDecl())
1535 return true;
1536 if (Path.empty())
1537 DeclAndIsDerivedMember.setInt(true);
1538 if (isDerivedMember()) {
1539 Path.push_back(Base);
1540 return true;
1541 }
1542 return castBack(Base);
1543 }
1544 };
1545
1546 /// Compare two member pointers, which are assumed to be of the same type.
1547 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1548 if (!LHS.getDecl() || !RHS.getDecl())
1549 return !LHS.getDecl() && !RHS.getDecl();
1550 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1551 return false;
1552 return LHS.Path == RHS.Path;
1553 }
1554}
1555
1556static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1557static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1558 const LValue &This, const Expr *E,
1559 bool AllowNonLiteralTypes = false);
1560static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1561 bool InvalidBaseOK = false);
1562static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1563 bool InvalidBaseOK = false);
1564static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1565 EvalInfo &Info);
1566static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1567static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1568static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1569 EvalInfo &Info);
1570static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1571static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1572static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1573 EvalInfo &Info);
1574static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1575
1576//===----------------------------------------------------------------------===//
1577// Misc utilities
1578//===----------------------------------------------------------------------===//
1579
1580/// A helper function to create a temporary and set an LValue.
1581template <class KeyTy>
1582static APValue &createTemporary(const KeyTy *Key, bool IsLifetimeExtended,
1583 LValue &LV, CallStackFrame &Frame) {
1584 LV.set({Key, Frame.Info.CurrentCall->Index,
1585 Frame.Info.CurrentCall->getTempVersion()});
1586 return Frame.createTemporary(Key, IsLifetimeExtended);
1587}
1588
1589/// Negate an APSInt in place, converting it to a signed form if necessary, and
1590/// preserving its value (by extending by up to one bit as needed).
1591static void negateAsSigned(APSInt &Int) {
1592 if (Int.isUnsigned() || Int.isMinSignedValue()) {
1593 Int = Int.extend(Int.getBitWidth() + 1);
1594 Int.setIsSigned(true);
1595 }
1596 Int = -Int;
1597}
1598
1599/// Produce a string describing the given constexpr call.
1600static void describeCall(CallStackFrame *Frame, raw_ostream &Out) {
1601 unsigned ArgIndex = 0;
1602 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) &&
1603 !isa<CXXConstructorDecl>(Frame->Callee) &&
1604 cast<CXXMethodDecl>(Frame->Callee)->isInstance();
1605
1606 if (!IsMemberCall)
1607 Out << *Frame->Callee << '(';
1608
1609 if (Frame->This && IsMemberCall) {
1610 APValue Val;
1611 Frame->This->moveInto(Val);
1612 Val.printPretty(Out, Frame->Info.Ctx,
1613 Frame->This->Designator.MostDerivedType);
1614 // FIXME: Add parens around Val if needed.
1615 Out << "->" << *Frame->Callee << '(';
1616 IsMemberCall = false;
1617 }
1618
1619 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(),
1620 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) {
1621 if (ArgIndex > (unsigned)IsMemberCall)
1622 Out << ", ";
1623
1624 const ParmVarDecl *Param = *I;
1625 const APValue &Arg = Frame->Arguments[ArgIndex];
1626 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType());
1627
1628 if (ArgIndex == 0 && IsMemberCall)
1629 Out << "->" << *Frame->Callee << '(';
1630 }
1631
1632 Out << ')';
1633}
1634
1635/// Evaluate an expression to see if it had side-effects, and discard its
1636/// result.
1637/// \return \c true if the caller should keep evaluating.
1638static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1639 APValue Scratch;
1640 if (!Evaluate(Scratch, Info, E))
1641 // We don't need the value, but we might have skipped a side effect here.
1642 return Info.noteSideEffect();
1643 return true;
1644}
1645
1646/// Should this call expression be treated as a string literal?
1647static bool IsStringLiteralCall(const CallExpr *E) {
1648 unsigned Builtin = E->getBuiltinCallee();
1649 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1650 Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1651}
1652
1653static bool IsGlobalLValue(APValue::LValueBase B) {
1654 // C++11 [expr.const]p3 An address constant expression is a prvalue core
1655 // constant expression of pointer type that evaluates to...
1656
1657 // ... a null pointer value, or a prvalue core constant expression of type
1658 // std::nullptr_t.
1659 if (!B) return true;
1660
1661 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1662 // ... the address of an object with static storage duration,
1663 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1664 return VD->hasGlobalStorage();
1665 // ... the address of a function,
1666 return isa<FunctionDecl>(D);
1667 }
1668
1669 const Expr *E = B.get<const Expr*>();
1670 switch (E->getStmtClass()) {
1671 default:
1672 return false;
1673 case Expr::CompoundLiteralExprClass: {
1674 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1675 return CLE->isFileScope() && CLE->isLValue();
1676 }
1677 case Expr::MaterializeTemporaryExprClass:
1678 // A materialized temporary might have been lifetime-extended to static
1679 // storage duration.
1680 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
1681 // A string literal has static storage duration.
1682 case Expr::StringLiteralClass:
1683 case Expr::PredefinedExprClass:
1684 case Expr::ObjCStringLiteralClass:
1685 case Expr::ObjCEncodeExprClass:
1686 case Expr::CXXTypeidExprClass:
1687 case Expr::CXXUuidofExprClass:
1688 return true;
1689 case Expr::CallExprClass:
1690 return IsStringLiteralCall(cast<CallExpr>(E));
1691 // For GCC compatibility, &&label has static storage duration.
1692 case Expr::AddrLabelExprClass:
1693 return true;
1694 // A Block literal expression may be used as the initialization value for
1695 // Block variables at global or local static scope.
1696 case Expr::BlockExprClass:
1697 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
1698 case Expr::ImplicitValueInitExprClass:
1699 // FIXME:
1700 // We can never form an lvalue with an implicit value initialization as its
1701 // base through expression evaluation, so these only appear in one case: the
1702 // implicit variable declaration we invent when checking whether a constexpr
1703 // constructor can produce a constant expression. We must assume that such
1704 // an expression might be a global lvalue.
1705 return true;
1706 }
1707}
1708
1709static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
1710 assert(Base && "no location for a null lvalue")(static_cast <bool> (Base && "no location for a null lvalue"
) ? void (0) : __assert_fail ("Base && \"no location for a null lvalue\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1710, __extension__ __PRETTY_FUNCTION__))
;
1711 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1712 if (VD)
1713 Info.Note(VD->getLocation(), diag::note_declared_at);
1714 else
1715 Info.Note(Base.get<const Expr*>()->getExprLoc(),
1716 diag::note_constexpr_temporary_here);
1717}
1718
1719/// Check that this reference or pointer core constant expression is a valid
1720/// value for an address or reference constant expression. Return true if we
1721/// can fold this expression, whether or not it's a constant expression.
1722static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
1723 QualType Type, const LValue &LVal,
1724 Expr::ConstExprUsage Usage) {
1725 bool IsReferenceType = Type->isReferenceType();
1726
1727 APValue::LValueBase Base = LVal.getLValueBase();
1728 const SubobjectDesignator &Designator = LVal.getLValueDesignator();
1729
1730 // Check that the object is a global. Note that the fake 'this' object we
1731 // manufacture when checking potential constant expressions is conservatively
1732 // assumed to be global here.
1733 if (!IsGlobalLValue(Base)) {
1734 if (Info.getLangOpts().CPlusPlus11) {
1735 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1736 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
1737 << IsReferenceType << !Designator.Entries.empty()
1738 << !!VD << VD;
1739 NoteLValueLocation(Info, Base);
1740 } else {
1741 Info.FFDiag(Loc);
1742 }
1743 // Don't allow references to temporaries to escape.
1744 return false;
1745 }
1746 assert((Info.checkingPotentialConstantExpression() ||(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1748, __extension__ __PRETTY_FUNCTION__))
1747 LVal.getLValueCallIndex() == 0) &&(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1748, __extension__ __PRETTY_FUNCTION__))
1748 "have call index for global lvalue")(static_cast <bool> ((Info.checkingPotentialConstantExpression
() || LVal.getLValueCallIndex() == 0) && "have call index for global lvalue"
) ? void (0) : __assert_fail ("(Info.checkingPotentialConstantExpression() || LVal.getLValueCallIndex() == 0) && \"have call index for global lvalue\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1748, __extension__ __PRETTY_FUNCTION__))
;
1749
1750 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
1751 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) {
1752 // Check if this is a thread-local variable.
1753 if (Var->getTLSKind())
1754 return false;
1755
1756 // A dllimport variable never acts like a constant.
1757 if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr<DLLImportAttr>())
1758 return false;
1759 }
1760 if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) {
1761 // __declspec(dllimport) must be handled very carefully:
1762 // We must never initialize an expression with the thunk in C++.
1763 // Doing otherwise would allow the same id-expression to yield
1764 // different addresses for the same function in different translation
1765 // units. However, this means that we must dynamically initialize the
1766 // expression with the contents of the import address table at runtime.
1767 //
1768 // The C language has no notion of ODR; furthermore, it has no notion of
1769 // dynamic initialization. This means that we are permitted to
1770 // perform initialization with the address of the thunk.
1771 if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen &&
1772 FD->hasAttr<DLLImportAttr>())
1773 return false;
1774 }
1775 }
1776
1777 // Allow address constant expressions to be past-the-end pointers. This is
1778 // an extension: the standard requires them to point to an object.
1779 if (!IsReferenceType)
1780 return true;
1781
1782 // A reference constant expression must refer to an object.
1783 if (!Base) {
1784 // FIXME: diagnostic
1785 Info.CCEDiag(Loc);
1786 return true;
1787 }
1788
1789 // Does this refer one past the end of some object?
1790 if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
1791 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1792 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
1793 << !Designator.Entries.empty() << !!VD << VD;
1794 NoteLValueLocation(Info, Base);
1795 }
1796
1797 return true;
1798}
1799
1800/// Member pointers are constant expressions unless they point to a
1801/// non-virtual dllimport member function.
1802static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
1803 SourceLocation Loc,
1804 QualType Type,
1805 const APValue &Value,
1806 Expr::ConstExprUsage Usage) {
1807 const ValueDecl *Member = Value.getMemberPointerDecl();
1808 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
1809 if (!FD)
1810 return true;
1811 return Usage == Expr::EvaluateForMangling || FD->isVirtual() ||
1812 !FD->hasAttr<DLLImportAttr>();
1813}
1814
1815/// Check that this core constant expression is of literal type, and if not,
1816/// produce an appropriate diagnostic.
1817static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
1818 const LValue *This = nullptr) {
1819 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
1820 return true;
1821
1822 // C++1y: A constant initializer for an object o [...] may also invoke
1823 // constexpr constructors for o and its subobjects even if those objects
1824 // are of non-literal class types.
1825 //
1826 // C++11 missed this detail for aggregates, so classes like this:
1827 // struct foo_t { union { int i; volatile int j; } u; };
1828 // are not (obviously) initializable like so:
1829 // __attribute__((__require_constant_initialization__))
1830 // static const foo_t x = {{0}};
1831 // because "i" is a subobject with non-literal initialization (due to the
1832 // volatile member of the union). See:
1833 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
1834 // Therefore, we use the C++1y behavior.
1835 if (This && Info.EvaluatingDecl == This->getLValueBase())
1836 return true;
1837
1838 // Prvalue constant expressions must be of literal types.
1839 if (Info.getLangOpts().CPlusPlus11)
1840 Info.FFDiag(E, diag::note_constexpr_nonliteral)
1841 << E->getType();
1842 else
1843 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
1844 return false;
1845}
1846
1847/// Check that this core constant expression value is a valid value for a
1848/// constant expression. If not, report an appropriate diagnostic. Does not
1849/// check that the expression is of literal type.
1850static bool
1851CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type,
1852 const APValue &Value,
1853 Expr::ConstExprUsage Usage = Expr::EvaluateForCodeGen) {
1854 if (Value.isUninit()) {
1855 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
1856 << true << Type;
1857 return false;
1858 }
1859
1860 // We allow _Atomic(T) to be initialized from anything that T can be
1861 // initialized from.
1862 if (const AtomicType *AT = Type->getAs<AtomicType>())
1863 Type = AT->getValueType();
1864
1865 // Core issue 1454: For a literal constant expression of array or class type,
1866 // each subobject of its value shall have been initialized by a constant
1867 // expression.
1868 if (Value.isArray()) {
1869 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
1870 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
1871 if (!CheckConstantExpression(Info, DiagLoc, EltTy,
1872 Value.getArrayInitializedElt(I), Usage))
1873 return false;
1874 }
1875 if (!Value.hasArrayFiller())
1876 return true;
1877 return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller(),
1878 Usage);
1879 }
1880 if (Value.isUnion() && Value.getUnionField()) {
1881 return CheckConstantExpression(Info, DiagLoc,
1882 Value.getUnionField()->getType(),
1883 Value.getUnionValue(), Usage);
1884 }
1885 if (Value.isStruct()) {
1886 RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
1887 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
1888 unsigned BaseIndex = 0;
1889 for (const CXXBaseSpecifier &BS : CD->bases()) {
1890 if (!CheckConstantExpression(Info, DiagLoc, BS.getType(),
1891 Value.getStructBase(BaseIndex), Usage))
1892 return false;
1893 ++BaseIndex;
1894 }
1895 }
1896 for (const auto *I : RD->fields()) {
1897 if (I->isUnnamedBitfield())
1898 continue;
1899
1900 if (!CheckConstantExpression(Info, DiagLoc, I->getType(),
1901 Value.getStructField(I->getFieldIndex()),
1902 Usage))
1903 return false;
1904 }
1905 }
1906
1907 if (Value.isLValue()) {
1908 LValue LVal;
1909 LVal.setFrom(Info.Ctx, Value);
1910 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage);
1911 }
1912
1913 if (Value.isMemberPointer())
1914 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage);
1915
1916 // Everything else is fine.
1917 return true;
1918}
1919
1920static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
1921 return LVal.Base.dyn_cast<const ValueDecl*>();
1922}
1923
1924static bool IsLiteralLValue(const LValue &Value) {
1925 if (Value.getLValueCallIndex())
1926 return false;
1927 const Expr *E = Value.Base.dyn_cast<const Expr*>();
1928 return E && !isa<MaterializeTemporaryExpr>(E);
1929}
1930
1931static bool IsWeakLValue(const LValue &Value) {
1932 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1933 return Decl && Decl->isWeak();
1934}
1935
1936static bool isZeroSized(const LValue &Value) {
1937 const ValueDecl *Decl = GetLValueBaseDecl(Value);
1938 if (Decl && isa<VarDecl>(Decl)) {
1939 QualType Ty = Decl->getType();
1940 if (Ty->isArrayType())
1941 return Ty->isIncompleteType() ||
1942 Decl->getASTContext().getTypeSize(Ty) == 0;
1943 }
1944 return false;
1945}
1946
1947static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
1948 // A null base expression indicates a null pointer. These are always
1949 // evaluatable, and they are false unless the offset is zero.
1950 if (!Value.getLValueBase()) {
1951 Result = !Value.getLValueOffset().isZero();
1952 return true;
1953 }
1954
1955 // We have a non-null base. These are generally known to be true, but if it's
1956 // a weak declaration it can be null at runtime.
1957 Result = true;
1958 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
1959 return !Decl || !Decl->isWeak();
1960}
1961
1962static bool HandleConversionToBool(const APValue &Val, bool &Result) {
1963 switch (Val.getKind()) {
1964 case APValue::Uninitialized:
1965 return false;
1966 case APValue::Int:
1967 Result = Val.getInt().getBoolValue();
1968 return true;
1969 case APValue::Float:
1970 Result = !Val.getFloat().isZero();
1971 return true;
1972 case APValue::ComplexInt:
1973 Result = Val.getComplexIntReal().getBoolValue() ||
1974 Val.getComplexIntImag().getBoolValue();
1975 return true;
1976 case APValue::ComplexFloat:
1977 Result = !Val.getComplexFloatReal().isZero() ||
1978 !Val.getComplexFloatImag().isZero();
1979 return true;
1980 case APValue::LValue:
1981 return EvalPointerValueAsBool(Val, Result);
1982 case APValue::MemberPointer:
1983 Result = Val.getMemberPointerDecl();
1984 return true;
1985 case APValue::Vector:
1986 case APValue::Array:
1987 case APValue::Struct:
1988 case APValue::Union:
1989 case APValue::AddrLabelDiff:
1990 return false;
1991 }
1992
1993 llvm_unreachable("unknown APValue kind")::llvm::llvm_unreachable_internal("unknown APValue kind", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1993)
;
1994}
1995
1996static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
1997 EvalInfo &Info) {
1998 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition")(static_cast <bool> (E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"
) ? void (0) : __assert_fail ("E->isRValue() && \"missing lvalue-to-rvalue conv in bool condition\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 1998, __extension__ __PRETTY_FUNCTION__))
;
1999 APValue Val;
2000 if (!Evaluate(Val, Info, E))
2001 return false;
2002 return HandleConversionToBool(Val, Result);
2003}
2004
2005template<typename T>
2006static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2007 const T &SrcValue, QualType DestType) {
2008 Info.CCEDiag(E, diag::note_constexpr_overflow)
2009 << SrcValue << DestType;
2010 return Info.noteUndefinedBehavior();
2011}
2012
2013static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2014 QualType SrcType, const APFloat &Value,
2015 QualType DestType, APSInt &Result) {
2016 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2017 // Determine whether we are converting to unsigned or signed.
2018 bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2019
2020 Result = APSInt(DestWidth, !DestSigned);
2021 bool ignored;
2022 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2023 & APFloat::opInvalidOp)
2024 return HandleOverflow(Info, E, Value, DestType);
2025 return true;
2026}
2027
2028static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2029 QualType SrcType, QualType DestType,
2030 APFloat &Result) {
2031 APFloat Value = Result;
2032 bool ignored;
2033 if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType),
2034 APFloat::rmNearestTiesToEven, &ignored)
2035 & APFloat::opOverflow)
2036 return HandleOverflow(Info, E, Value, DestType);
2037 return true;
2038}
2039
2040static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2041 QualType DestType, QualType SrcType,
2042 const APSInt &Value) {
2043 unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2044 APSInt Result = Value;
2045 // Figure out if this is a truncate, extend or noop cast.
2046 // If the input is signed, do a sign extend, noop, or truncate.
2047 Result = Result.extOrTrunc(DestWidth);
2048 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2049 return Result;
2050}
2051
2052static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2053 QualType SrcType, const APSInt &Value,
2054 QualType DestType, APFloat &Result) {
2055 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2056 if (Result.convertFromAPInt(Value, Value.isSigned(),
2057 APFloat::rmNearestTiesToEven)
2058 & APFloat::opOverflow)
2059 return HandleOverflow(Info, E, Value, DestType);
2060 return true;
2061}
2062
2063static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2064 APValue &Value, const FieldDecl *FD) {
2065 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield")(static_cast <bool> (FD->isBitField() && "truncateBitfieldValue on non-bitfield"
) ? void (0) : __assert_fail ("FD->isBitField() && \"truncateBitfieldValue on non-bitfield\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2065, __extension__ __PRETTY_FUNCTION__))
;
2066
2067 if (!Value.isInt()) {
2068 // Trying to store a pointer-cast-to-integer into a bitfield.
2069 // FIXME: In this case, we should provide the diagnostic for casting
2070 // a pointer to an integer.
2071 assert(Value.isLValue() && "integral value neither int nor lvalue?")(static_cast <bool> (Value.isLValue() && "integral value neither int nor lvalue?"
) ? void (0) : __assert_fail ("Value.isLValue() && \"integral value neither int nor lvalue?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2071, __extension__ __PRETTY_FUNCTION__))
;
2072 Info.FFDiag(E);
2073 return false;
2074 }
2075
2076 APSInt &Int = Value.getInt();
2077 unsigned OldBitWidth = Int.getBitWidth();
2078 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2079 if (NewBitWidth < OldBitWidth)
2080 Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2081 return true;
2082}
2083
2084static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2085 llvm::APInt &Res) {
2086 APValue SVal;
2087 if (!Evaluate(SVal, Info, E))
2088 return false;
2089 if (SVal.isInt()) {
2090 Res = SVal.getInt();
2091 return true;
2092 }
2093 if (SVal.isFloat()) {
2094 Res = SVal.getFloat().bitcastToAPInt();
2095 return true;
2096 }
2097 if (SVal.isVector()) {
2098 QualType VecTy = E->getType();
2099 unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2100 QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2101 unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2102 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2103 Res = llvm::APInt::getNullValue(VecSize);
2104 for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2105 APValue &Elt = SVal.getVectorElt(i);
2106 llvm::APInt EltAsInt;
2107 if (Elt.isInt()) {
2108 EltAsInt = Elt.getInt();
2109 } else if (Elt.isFloat()) {
2110 EltAsInt = Elt.getFloat().bitcastToAPInt();
2111 } else {
2112 // Don't try to handle vectors of anything other than int or float
2113 // (not sure if it's possible to hit this case).
2114 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2115 return false;
2116 }
2117 unsigned BaseEltSize = EltAsInt.getBitWidth();
2118 if (BigEndian)
2119 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2120 else
2121 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2122 }
2123 return true;
2124 }
2125 // Give up if the input isn't an int, float, or vector. For example, we
2126 // reject "(v4i16)(intptr_t)&a".
2127 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2128 return false;
2129}
2130
2131/// Perform the given integer operation, which is known to need at most BitWidth
2132/// bits, and check for overflow in the original type (if that type was not an
2133/// unsigned type).
2134template<typename Operation>
2135static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2136 const APSInt &LHS, const APSInt &RHS,
2137 unsigned BitWidth, Operation Op,
2138 APSInt &Result) {
2139 if (LHS.isUnsigned()) {
2140 Result = Op(LHS, RHS);
2141 return true;
2142 }
2143
2144 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2145 Result = Value.trunc(LHS.getBitWidth());
2146 if (Result.extend(BitWidth) != Value) {
2147 if (Info.checkingForOverflow())
2148 Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2149 diag::warn_integer_constant_overflow)
2150 << Result.toString(10) << E->getType();
2151 else
2152 return HandleOverflow(Info, E, Value, E->getType());
2153 }
2154 return true;
2155}
2156
2157/// Perform the given binary integer operation.
2158static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2159 BinaryOperatorKind Opcode, APSInt RHS,
2160 APSInt &Result) {
2161 switch (Opcode) {
2162 default:
2163 Info.FFDiag(E);
2164 return false;
2165 case BO_Mul:
2166 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2167 std::multiplies<APSInt>(), Result);
2168 case BO_Add:
2169 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2170 std::plus<APSInt>(), Result);
2171 case BO_Sub:
2172 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2173 std::minus<APSInt>(), Result);
2174 case BO_And: Result = LHS & RHS; return true;
2175 case BO_Xor: Result = LHS ^ RHS; return true;
2176 case BO_Or: Result = LHS | RHS; return true;
2177 case BO_Div:
2178 case BO_Rem:
2179 if (RHS == 0) {
2180 Info.FFDiag(E, diag::note_expr_divide_by_zero);
2181 return false;
2182 }
2183 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2184 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2185 // this operation and gives the two's complement result.
2186 if (RHS.isNegative() && RHS.isAllOnesValue() &&
2187 LHS.isSigned() && LHS.isMinSignedValue())
2188 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2189 E->getType());
2190 return true;
2191 case BO_Shl: {
2192 if (Info.getLangOpts().OpenCL)
2193 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2194 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2195 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2196 RHS.isUnsigned());
2197 else if (RHS.isSigned() && RHS.isNegative()) {
2198 // During constant-folding, a negative shift is an opposite shift. Such
2199 // a shift is not a constant expression.
2200 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2201 RHS = -RHS;
2202 goto shift_right;
2203 }
2204 shift_left:
2205 // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2206 // the shifted type.
2207 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2208 if (SA != RHS) {
2209 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2210 << RHS << E->getType() << LHS.getBitWidth();
2211 } else if (LHS.isSigned()) {
2212 // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2213 // operand, and must not overflow the corresponding unsigned type.
2214 if (LHS.isNegative())
2215 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2216 else if (LHS.countLeadingZeros() < SA)
2217 Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2218 }
2219 Result = LHS << SA;
2220 return true;
2221 }
2222 case BO_Shr: {
2223 if (Info.getLangOpts().OpenCL)
2224 // OpenCL 6.3j: shift values are effectively % word size of LHS.
2225 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2226 static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2227 RHS.isUnsigned());
2228 else if (RHS.isSigned() && RHS.isNegative()) {
2229 // During constant-folding, a negative shift is an opposite shift. Such a
2230 // shift is not a constant expression.
2231 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2232 RHS = -RHS;
2233 goto shift_left;
2234 }
2235 shift_right:
2236 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2237 // shifted type.
2238 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2239 if (SA != RHS)
2240 Info.CCEDiag(E, diag::note_constexpr_large_shift)
2241 << RHS << E->getType() << LHS.getBitWidth();
2242 Result = LHS >> SA;
2243 return true;
2244 }
2245
2246 case BO_LT: Result = LHS < RHS; return true;
2247 case BO_GT: Result = LHS > RHS; return true;
2248 case BO_LE: Result = LHS <= RHS; return true;
2249 case BO_GE: Result = LHS >= RHS; return true;
2250 case BO_EQ: Result = LHS == RHS; return true;
2251 case BO_NE: Result = LHS != RHS; return true;
2252 case BO_Cmp:
2253 llvm_unreachable("BO_Cmp should be handled elsewhere")::llvm::llvm_unreachable_internal("BO_Cmp should be handled elsewhere"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2253)
;
2254 }
2255}
2256
2257/// Perform the given binary floating-point operation, in-place, on LHS.
2258static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E,
2259 APFloat &LHS, BinaryOperatorKind Opcode,
2260 const APFloat &RHS) {
2261 switch (Opcode) {
2262 default:
2263 Info.FFDiag(E);
2264 return false;
2265 case BO_Mul:
2266 LHS.multiply(RHS, APFloat::rmNearestTiesToEven);
2267 break;
2268 case BO_Add:
2269 LHS.add(RHS, APFloat::rmNearestTiesToEven);
2270 break;
2271 case BO_Sub:
2272 LHS.subtract(RHS, APFloat::rmNearestTiesToEven);
2273 break;
2274 case BO_Div:
2275 LHS.divide(RHS, APFloat::rmNearestTiesToEven);
2276 break;
2277 }
2278
2279 if (LHS.isInfinity() || LHS.isNaN()) {
2280 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2281 return Info.noteUndefinedBehavior();
2282 }
2283 return true;
2284}
2285
2286/// Cast an lvalue referring to a base subobject to a derived class, by
2287/// truncating the lvalue's path to the given length.
2288static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
2289 const RecordDecl *TruncatedType,
2290 unsigned TruncatedElements) {
2291 SubobjectDesignator &D = Result.Designator;
2292
2293 // Check we actually point to a derived class object.
2294 if (TruncatedElements == D.Entries.size())
2295 return true;
2296 assert(TruncatedElements >= D.MostDerivedPathLength &&(static_cast <bool> (TruncatedElements >= D.MostDerivedPathLength
&& "not casting to a derived class") ? void (0) : __assert_fail
("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2297, __extension__ __PRETTY_FUNCTION__))
2297 "not casting to a derived class")(static_cast <bool> (TruncatedElements >= D.MostDerivedPathLength
&& "not casting to a derived class") ? void (0) : __assert_fail
("TruncatedElements >= D.MostDerivedPathLength && \"not casting to a derived class\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2297, __extension__ __PRETTY_FUNCTION__))
;
2298 if (!Result.checkSubobject(Info, E, CSK_Derived))
2299 return false;
2300
2301 // Truncate the path to the subobject, and remove any derived-to-base offsets.
2302 const RecordDecl *RD = TruncatedType;
2303 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
2304 if (RD->isInvalidDecl()) return false;
2305 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
2306 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
2307 if (isVirtualBaseClass(D.Entries[I]))
2308 Result.Offset -= Layout.getVBaseClassOffset(Base);
2309 else
2310 Result.Offset -= Layout.getBaseClassOffset(Base);
2311 RD = Base;
2312 }
2313 D.Entries.resize(TruncatedElements);
2314 return true;
2315}
2316
2317static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2318 const CXXRecordDecl *Derived,
2319 const CXXRecordDecl *Base,
2320 const ASTRecordLayout *RL = nullptr) {
2321 if (!RL) {
2322 if (Derived->isInvalidDecl()) return false;
2323 RL = &Info.Ctx.getASTRecordLayout(Derived);
2324 }
2325
2326 Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
2327 Obj.addDecl(Info, E, Base, /*Virtual*/ false);
2328 return true;
2329}
2330
2331static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2332 const CXXRecordDecl *DerivedDecl,
2333 const CXXBaseSpecifier *Base) {
2334 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
2335
2336 if (!Base->isVirtual())
2337 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
2338
2339 SubobjectDesignator &D = Obj.Designator;
2340 if (D.Invalid)
2341 return false;
2342
2343 // Extract most-derived object and corresponding type.
2344 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
2345 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
2346 return false;
2347
2348 // Find the virtual base class.
2349 if (DerivedDecl->isInvalidDecl()) return false;
2350 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
2351 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
2352 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
2353 return true;
2354}
2355
2356static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
2357 QualType Type, LValue &Result) {
2358 for (CastExpr::path_const_iterator PathI = E->path_begin(),
2359 PathE = E->path_end();
2360 PathI != PathE; ++PathI) {
2361 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
2362 *PathI))
2363 return false;
2364 Type = (*PathI)->getType();
2365 }
2366 return true;
2367}
2368
2369/// Update LVal to refer to the given field, which must be a member of the type
2370/// currently described by LVal.
2371static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
2372 const FieldDecl *FD,
2373 const ASTRecordLayout *RL = nullptr) {
2374 if (!RL) {
2375 if (FD->getParent()->isInvalidDecl()) return false;
2376 RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
2377 }
2378
2379 unsigned I = FD->getFieldIndex();
2380 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
2381 LVal.addDecl(Info, E, FD);
2382 return true;
2383}
2384
2385/// Update LVal to refer to the given indirect field.
2386static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
2387 LValue &LVal,
2388 const IndirectFieldDecl *IFD) {
2389 for (const auto *C : IFD->chain())
2390 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
2391 return false;
2392 return true;
2393}
2394
2395/// Get the size of the given type in char units.
2396static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
2397 QualType Type, CharUnits &Size) {
2398 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
2399 // extension.
2400 if (Type->isVoidType() || Type->isFunctionType()) {
2401 Size = CharUnits::One();
2402 return true;
2403 }
2404
2405 if (Type->isDependentType()) {
2406 Info.FFDiag(Loc);
2407 return false;
2408 }
2409
2410 if (!Type->isConstantSizeType()) {
2411 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
2412 // FIXME: Better diagnostic.
2413 Info.FFDiag(Loc);
2414 return false;
2415 }
2416
2417 Size = Info.Ctx.getTypeSizeInChars(Type);
2418 return true;
2419}
2420
2421/// Update a pointer value to model pointer arithmetic.
2422/// \param Info - Information about the ongoing evaluation.
2423/// \param E - The expression being evaluated, for diagnostic purposes.
2424/// \param LVal - The pointer value to be updated.
2425/// \param EltTy - The pointee type represented by LVal.
2426/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
2427static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2428 LValue &LVal, QualType EltTy,
2429 APSInt Adjustment) {
2430 CharUnits SizeOfPointee;
2431 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
20
Called C++ object pointer is null
2432 return false;
2433
2434 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
2435 return true;
2436}
2437
2438static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2439 LValue &LVal, QualType EltTy,
2440 int64_t Adjustment) {
2441 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
18
Passing null pointer value via 2nd parameter 'E'
19
Calling 'HandleLValueArrayAdjustment'
2442 APSInt::get(Adjustment));
2443}
2444
2445/// Update an lvalue to refer to a component of a complex number.
2446/// \param Info - Information about the ongoing evaluation.
2447/// \param LVal - The lvalue to be updated.
2448/// \param EltTy - The complex number's component type.
2449/// \param Imag - False for the real component, true for the imaginary.
2450static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
2451 LValue &LVal, QualType EltTy,
2452 bool Imag) {
2453 if (Imag) {
2454 CharUnits SizeOfComponent;
2455 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
2456 return false;
2457 LVal.Offset += SizeOfComponent;
2458 }
2459 LVal.addComplex(Info, E, EltTy, Imag);
2460 return true;
2461}
2462
2463static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
2464 QualType Type, const LValue &LVal,
2465 APValue &RVal);
2466
2467/// Try to evaluate the initializer for a variable declaration.
2468///
2469/// \param Info Information about the ongoing evaluation.
2470/// \param E An expression to be used when printing diagnostics.
2471/// \param VD The variable whose initializer should be obtained.
2472/// \param Frame The frame in which the variable was created. Must be null
2473/// if this variable is not local to the evaluation.
2474/// \param Result Filled in with a pointer to the value of the variable.
2475static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
2476 const VarDecl *VD, CallStackFrame *Frame,
2477 APValue *&Result, const LValue *LVal) {
2478
2479 // If this is a parameter to an active constexpr function call, perform
2480 // argument substitution.
2481 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
2482 // Assume arguments of a potential constant expression are unknown
2483 // constant expressions.
2484 if (Info.checkingPotentialConstantExpression())
2485 return false;
2486 if (!Frame || !Frame->Arguments) {
2487 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2488 return false;
2489 }
2490 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()];
2491 return true;
2492 }
2493
2494 // If this is a local variable, dig out its value.
2495 if (Frame) {
2496 Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion())
2497 : Frame->getCurrentTemporary(VD);
2498 if (!Result) {
2499 // Assume variables referenced within a lambda's call operator that were
2500 // not declared within the call operator are captures and during checking
2501 // of a potential constant expression, assume they are unknown constant
2502 // expressions.
2503 assert(isLambdaCallOperator(Frame->Callee) &&(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2505, __extension__ __PRETTY_FUNCTION__))
2504 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2505, __extension__ __PRETTY_FUNCTION__))
2505 "missing value for local variable")(static_cast <bool> (isLambdaCallOperator(Frame->Callee
) && (VD->getDeclContext() != Frame->Callee || VD
->isInitCapture()) && "missing value for local variable"
) ? void (0) : __assert_fail ("isLambdaCallOperator(Frame->Callee) && (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && \"missing value for local variable\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2505, __extension__ __PRETTY_FUNCTION__))
;
2506 if (Info.checkingPotentialConstantExpression())
2507 return false;
2508 // FIXME: implement capture evaluation during constant expr evaluation.
2509 Info.FFDiag(E->getLocStart(),
2510 diag::note_unimplemented_constexpr_lambda_feature_ast)
2511 << "captures not currently allowed";
2512 return false;
2513 }
2514 return true;
2515 }
2516
2517 // Dig out the initializer, and use the declaration which it's attached to.
2518 const Expr *Init = VD->getAnyInitializer(VD);
2519 if (!Init || Init->isValueDependent()) {
2520 // If we're checking a potential constant expression, the variable could be
2521 // initialized later.
2522 if (!Info.checkingPotentialConstantExpression())
2523 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2524 return false;
2525 }
2526
2527 // If we're currently evaluating the initializer of this declaration, use that
2528 // in-flight value.
2529 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
2530 Result = Info.EvaluatingDeclValue;
2531 return true;
2532 }
2533
2534 // Never evaluate the initializer of a weak variable. We can't be sure that
2535 // this is the definition which will be used.
2536 if (VD->isWeak()) {
2537 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2538 return false;
2539 }
2540
2541 // Check that we can fold the initializer. In C++, we will have already done
2542 // this in the cases where it matters for conformance.
2543 SmallVector<PartialDiagnosticAt, 8> Notes;
2544 if (!VD->evaluateValue(Notes)) {
2545 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant,
2546 Notes.size() + 1) << VD;
2547 Info.Note(VD->getLocation(), diag::note_declared_at);
2548 Info.addNotes(Notes);
2549 return false;
2550 } else if (!VD->checkInitIsICE()) {
2551 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant,
2552 Notes.size() + 1) << VD;
2553 Info.Note(VD->getLocation(), diag::note_declared_at);
2554 Info.addNotes(Notes);
2555 }
2556
2557 Result = VD->getEvaluatedValue();
2558 return true;
2559}
2560
2561static bool IsConstNonVolatile(QualType T) {
2562 Qualifiers Quals = T.getQualifiers();
2563 return Quals.hasConst() && !Quals.hasVolatile();
2564}
2565
2566/// Get the base index of the given base class within an APValue representing
2567/// the given derived class.
2568static unsigned getBaseIndex(const CXXRecordDecl *Derived,
2569 const CXXRecordDecl *Base) {
2570 Base = Base->getCanonicalDecl();
2571 unsigned Index = 0;
2572 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
2573 E = Derived->bases_end(); I != E; ++I, ++Index) {
2574 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
2575 return Index;
2576 }
2577
2578 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2578)
;
2579}
2580
2581/// Extract the value of a character from a string literal.
2582static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
2583 uint64_t Index) {
2584 // FIXME: Support MakeStringConstant
2585 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
2586 std::string Str;
2587 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
2588 assert(Index <= Str.size() && "Index too large")(static_cast <bool> (Index <= Str.size() && "Index too large"
) ? void (0) : __assert_fail ("Index <= Str.size() && \"Index too large\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2588, __extension__ __PRETTY_FUNCTION__))
;
2589 return APSInt::getUnsigned(Str.c_str()[Index]);
2590 }
2591
2592 if (auto PE = dyn_cast<PredefinedExpr>(Lit))
2593 Lit = PE->getFunctionName();
2594 const StringLiteral *S = cast<StringLiteral>(Lit);
2595 const ConstantArrayType *CAT =
2596 Info.Ctx.getAsConstantArrayType(S->getType());
2597 assert(CAT && "string literal isn't an array")(static_cast <bool> (CAT && "string literal isn't an array"
) ? void (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2597, __extension__ __PRETTY_FUNCTION__))
;
2598 QualType CharType = CAT->getElementType();
2599 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2599, __extension__ __PRETTY_FUNCTION__))
;
2600
2601 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2602 CharType->isUnsignedIntegerType());
2603 if (Index < S->getLength())
2604 Value = S->getCodeUnit(Index);
2605 return Value;
2606}
2607
2608// Expand a string literal into an array of characters.
2609static void expandStringLiteral(EvalInfo &Info, const Expr *Lit,
2610 APValue &Result) {
2611 const StringLiteral *S = cast<StringLiteral>(Lit);
2612 const ConstantArrayType *CAT =
2613 Info.Ctx.getAsConstantArrayType(S->getType());
2614 assert(CAT && "string literal isn't an array")(static_cast <bool> (CAT && "string literal isn't an array"
) ? void (0) : __assert_fail ("CAT && \"string literal isn't an array\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2614, __extension__ __PRETTY_FUNCTION__))
;
2615 QualType CharType = CAT->getElementType();
2616 assert(CharType->isIntegerType() && "unexpected character type")(static_cast <bool> (CharType->isIntegerType() &&
"unexpected character type") ? void (0) : __assert_fail ("CharType->isIntegerType() && \"unexpected character type\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2616, __extension__ __PRETTY_FUNCTION__))
;
2617
2618 unsigned Elts = CAT->getSize().getZExtValue();
2619 Result = APValue(APValue::UninitArray(),
2620 std::min(S->getLength(), Elts), Elts);
2621 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2622 CharType->isUnsignedIntegerType());
2623 if (Result.hasArrayFiller())
2624 Result.getArrayFiller() = APValue(Value);
2625 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
2626 Value = S->getCodeUnit(I);
2627 Result.getArrayInitializedElt(I) = APValue(Value);
2628 }
2629}
2630
2631// Expand an array so that it has more than Index filled elements.
2632static void expandArray(APValue &Array, unsigned Index) {
2633 unsigned Size = Array.getArraySize();
2634 assert(Index < Size)(static_cast <bool> (Index < Size) ? void (0) : __assert_fail
("Index < Size", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2634, __extension__ __PRETTY_FUNCTION__))
;
2635
2636 // Always at least double the number of elements for which we store a value.
2637 unsigned OldElts = Array.getArrayInitializedElts();
2638 unsigned NewElts = std::max(Index+1, OldElts * 2);
2639 NewElts = std::min(Size, std::max(NewElts, 8u));
2640
2641 // Copy the data across.
2642 APValue NewValue(APValue::UninitArray(), NewElts, Size);
2643 for (unsigned I = 0; I != OldElts; ++I)
2644 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
2645 for (unsigned I = OldElts; I != NewElts; ++I)
2646 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
2647 if (NewValue.hasArrayFiller())
2648 NewValue.getArrayFiller() = Array.getArrayFiller();
2649 Array.swap(NewValue);
2650}
2651
2652/// Determine whether a type would actually be read by an lvalue-to-rvalue
2653/// conversion. If it's of class type, we may assume that the copy operation
2654/// is trivial. Note that this is never true for a union type with fields
2655/// (because the copy always "reads" the active member) and always true for
2656/// a non-class type.
2657static bool isReadByLvalueToRvalueConversion(QualType T) {
2658 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
2659 if (!RD || (RD->isUnion() && !RD->field_empty()))
2660 return true;
2661 if (RD->isEmpty())
2662 return false;
2663
2664 for (auto *Field : RD->fields())
2665 if (isReadByLvalueToRvalueConversion(Field->getType()))
2666 return true;
2667
2668 for (auto &BaseSpec : RD->bases())
2669 if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
2670 return true;
2671
2672 return false;
2673}
2674
2675/// Diagnose an attempt to read from any unreadable field within the specified
2676/// type, which might be a class type.
2677static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E,
2678 QualType T) {
2679 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
2680 if (!RD)
2681 return false;
2682
2683 if (!RD->hasMutableFields())
2684 return false;
2685
2686 for (auto *Field : RD->fields()) {
2687 // If we're actually going to read this field in some way, then it can't
2688 // be mutable. If we're in a union, then assigning to a mutable field
2689 // (even an empty one) can change the active member, so that's not OK.
2690 // FIXME: Add core issue number for the union case.
2691 if (Field->isMutable() &&
2692 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
2693 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field;
2694 Info.Note(Field->getLocation(), diag::note_declared_at);
2695 return true;
2696 }
2697
2698 if (diagnoseUnreadableFields(Info, E, Field->getType()))
2699 return true;
2700 }
2701
2702 for (auto &BaseSpec : RD->bases())
2703 if (diagnoseUnreadableFields(Info, E, BaseSpec.getType()))
2704 return true;
2705
2706 // All mutable fields were empty, and thus not actually read.
2707 return false;
2708}
2709
2710/// Kinds of access we can perform on an object, for diagnostics.
2711enum AccessKinds {
2712 AK_Read,
2713 AK_Assign,
2714 AK_Increment,
2715 AK_Decrement
2716};
2717
2718namespace {
2719/// A handle to a complete object (an object that is not a subobject of
2720/// another object).
2721struct CompleteObject {
2722 /// The value of the complete object.
2723 APValue *Value;
2724 /// The type of the complete object.
2725 QualType Type;
2726 bool LifetimeStartedInEvaluation;
2727
2728 CompleteObject() : Value(nullptr) {}
2729 CompleteObject(APValue *Value, QualType Type,
2730 bool LifetimeStartedInEvaluation)
2731 : Value(Value), Type(Type),
2732 LifetimeStartedInEvaluation(LifetimeStartedInEvaluation) {
2733 assert(Value && "missing value for complete object")(static_cast <bool> (Value && "missing value for complete object"
) ? void (0) : __assert_fail ("Value && \"missing value for complete object\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2733, __extension__ __PRETTY_FUNCTION__))
;
2734 }
2735
2736 explicit operator bool() const { return Value; }
2737};
2738} // end anonymous namespace
2739
2740/// Find the designated sub-object of an rvalue.
2741template<typename SubobjectHandler>
2742typename SubobjectHandler::result_type
2743findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
2744 const SubobjectDesignator &Sub, SubobjectHandler &handler) {
2745 if (Sub.Invalid)
2746 // A diagnostic will have already been produced.
2747 return handler.failed();
2748 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
2749 if (Info.getLangOpts().CPlusPlus11)
2750 Info.FFDiag(E, Sub.isOnePastTheEnd()
2751 ? diag::note_constexpr_access_past_end
2752 : diag::note_constexpr_access_unsized_array)
2753 << handler.AccessKind;
2754 else
2755 Info.FFDiag(E);
2756 return handler.failed();
2757 }
2758
2759 APValue *O = Obj.Value;
2760 QualType ObjType = Obj.Type;
2761 const FieldDecl *LastField = nullptr;
2762 const bool MayReadMutableMembers =
2763 Obj.LifetimeStartedInEvaluation && Info.getLangOpts().CPlusPlus14;
2764
2765 // Walk the designator's path to find the subobject.
2766 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
2767 if (O->isUninit()) {
2768 if (!Info.checkingPotentialConstantExpression())
2769 Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind;
2770 return handler.failed();
2771 }
2772
2773 if (I == N) {
2774 // If we are reading an object of class type, there may still be more
2775 // things we need to check: if there are any mutable subobjects, we
2776 // cannot perform this read. (This only happens when performing a trivial
2777 // copy or assignment.)
2778 if (ObjType->isRecordType() && handler.AccessKind == AK_Read &&
2779 !MayReadMutableMembers && diagnoseUnreadableFields(Info, E, ObjType))
2780 return handler.failed();
2781
2782 if (!handler.found(*O, ObjType))
2783 return false;
2784
2785 // If we modified a bit-field, truncate it to the right width.
2786 if (handler.AccessKind != AK_Read &&
2787 LastField && LastField->isBitField() &&
2788 !truncateBitfieldValue(Info, E, *O, LastField))
2789 return false;
2790
2791 return true;
2792 }
2793
2794 LastField = nullptr;
2795 if (ObjType->isArrayType()) {
2796 // Next subobject is an array element.
2797 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
2798 assert(CAT && "vla in literal type?")(static_cast <bool> (CAT && "vla in literal type?"
) ? void (0) : __assert_fail ("CAT && \"vla in literal type?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2798, __extension__ __PRETTY_FUNCTION__))
;
2799 uint64_t Index = Sub.Entries[I].ArrayIndex;
2800 if (CAT->getSize().ule(Index)) {
2801 // Note, it should not be possible to form a pointer with a valid
2802 // designator which points more than one past the end of the array.
2803 if (Info.getLangOpts().CPlusPlus11)
2804 Info.FFDiag(E, diag::note_constexpr_access_past_end)
2805 << handler.AccessKind;
2806 else
2807 Info.FFDiag(E);
2808 return handler.failed();
2809 }
2810
2811 ObjType = CAT->getElementType();
2812
2813 // An array object is represented as either an Array APValue or as an
2814 // LValue which refers to a string literal.
2815 if (O->isLValue()) {
2816 assert(I == N - 1 && "extracting subobject of character?")(static_cast <bool> (I == N - 1 && "extracting subobject of character?"
) ? void (0) : __assert_fail ("I == N - 1 && \"extracting subobject of character?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2816, __extension__ __PRETTY_FUNCTION__))
;
2817 assert(!O->hasLValuePath() || O->getLValuePath().empty())(static_cast <bool> (!O->hasLValuePath() || O->getLValuePath
().empty()) ? void (0) : __assert_fail ("!O->hasLValuePath() || O->getLValuePath().empty()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2817, __extension__ __PRETTY_FUNCTION__))
;
2818 if (handler.AccessKind != AK_Read)
2819 expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(),
2820 *O);
2821 else
2822 return handler.foundString(*O, ObjType, Index);
2823 }
2824
2825 if (O->getArrayInitializedElts() > Index)
2826 O = &O->getArrayInitializedElt(Index);
2827 else if (handler.AccessKind != AK_Read) {
2828 expandArray(*O, Index);
2829 O = &O->getArrayInitializedElt(Index);
2830 } else
2831 O = &O->getArrayFiller();
2832 } else if (ObjType->isAnyComplexType()) {
2833 // Next subobject is a complex number.
2834 uint64_t Index = Sub.Entries[I].ArrayIndex;
2835 if (Index > 1) {
2836 if (Info.getLangOpts().CPlusPlus11)
2837 Info.FFDiag(E, diag::note_constexpr_access_past_end)
2838 << handler.AccessKind;
2839 else
2840 Info.FFDiag(E);
2841 return handler.failed();
2842 }
2843
2844 bool WasConstQualified = ObjType.isConstQualified();
2845 ObjType = ObjType->castAs<ComplexType>()->getElementType();
2846 if (WasConstQualified)
2847 ObjType.addConst();
2848
2849 assert(I == N - 1 && "extracting subobject of scalar?")(static_cast <bool> (I == N - 1 && "extracting subobject of scalar?"
) ? void (0) : __assert_fail ("I == N - 1 && \"extracting subobject of scalar?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2849, __extension__ __PRETTY_FUNCTION__))
;
2850 if (O->isComplexInt()) {
2851 return handler.found(Index ? O->getComplexIntImag()
2852 : O->getComplexIntReal(), ObjType);
2853 } else {
2854 assert(O->isComplexFloat())(static_cast <bool> (O->isComplexFloat()) ? void (0)
: __assert_fail ("O->isComplexFloat()", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 2854, __extension__ __PRETTY_FUNCTION__))
;
2855 return handler.found(Index ? O->getComplexFloatImag()
2856 : O->getComplexFloatReal(), ObjType);
2857 }
2858 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
2859 // In C++14 onwards, it is permitted to read a mutable member whose
2860 // lifetime began within the evaluation.
2861 // FIXME: Should we also allow this in C++11?
2862 if (Field->isMutable() && handler.AccessKind == AK_Read &&
2863 !MayReadMutableMembers) {
2864 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1)
2865 << Field;
2866 Info.Note(Field->getLocation(), diag::note_declared_at);
2867 return handler.failed();
2868 }
2869
2870 // Next subobject is a class, struct or union field.
2871 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
2872 if (RD->isUnion()) {
2873 const FieldDecl *UnionField = O->getUnionField();
2874 if (!UnionField ||
2875 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
2876 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
2877 << handler.AccessKind << Field << !UnionField << UnionField;
2878 return handler.failed();
2879 }
2880 O = &O->getUnionValue();
2881 } else
2882 O = &O->getStructField(Field->getFieldIndex());
2883
2884 bool WasConstQualified = ObjType.isConstQualified();
2885 ObjType = Field->getType();
2886 if (WasConstQualified && !Field->isMutable())
2887 ObjType.addConst();
2888
2889 if (ObjType.isVolatileQualified()) {
2890 if (Info.getLangOpts().CPlusPlus) {
2891 // FIXME: Include a description of the path to the volatile subobject.
2892 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
2893 << handler.AccessKind << 2 << Field;
2894 Info.Note(Field->getLocation(), diag::note_declared_at);
2895 } else {
2896 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2897 }
2898 return handler.failed();
2899 }
2900
2901 LastField = Field;
2902 } else {
2903 // Next subobject is a base class.
2904 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
2905 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
2906 O = &O->getStructBase(getBaseIndex(Derived, Base));
2907
2908 bool WasConstQualified = ObjType.isConstQualified();
2909 ObjType = Info.Ctx.getRecordType(Base);
2910 if (WasConstQualified)
2911 ObjType.addConst();
2912 }
2913 }
2914}
2915
2916namespace {
2917struct ExtractSubobjectHandler {
2918 EvalInfo &Info;
2919 APValue &Result;
2920
2921 static const AccessKinds AccessKind = AK_Read;
2922
2923 typedef bool result_type;
2924 bool failed() { return false; }
2925 bool found(APValue &Subobj, QualType SubobjType) {
2926 Result = Subobj;
2927 return true;
2928 }
2929 bool found(APSInt &Value, QualType SubobjType) {
2930 Result = APValue(Value);
2931 return true;
2932 }
2933 bool found(APFloat &Value, QualType SubobjType) {
2934 Result = APValue(Value);
2935 return true;
2936 }
2937 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
2938 Result = APValue(extractStringLiteralCharacter(
2939 Info, Subobj.getLValueBase().get<const Expr *>(), Character));
2940 return true;
2941 }
2942};
2943} // end anonymous namespace
2944
2945const AccessKinds ExtractSubobjectHandler::AccessKind;
2946
2947/// Extract the designated sub-object of an rvalue.
2948static bool extractSubobject(EvalInfo &Info, const Expr *E,
2949 const CompleteObject &Obj,
2950 const SubobjectDesignator &Sub,
2951 APValue &Result) {
2952 ExtractSubobjectHandler Handler = { Info, Result };
2953 return findSubobject(Info, E, Obj, Sub, Handler);
2954}
2955
2956namespace {
2957struct ModifySubobjectHandler {
2958 EvalInfo &Info;
2959 APValue &NewVal;
2960 const Expr *E;
2961
2962 typedef bool result_type;
2963 static const AccessKinds AccessKind = AK_Assign;
2964
2965 bool checkConst(QualType QT) {
2966 // Assigning to a const object has undefined behavior.
2967 if (QT.isConstQualified()) {
2968 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
2969 return false;
2970 }
2971 return true;
2972 }
2973
2974 bool failed() { return false; }
2975 bool found(APValue &Subobj, QualType SubobjType) {
2976 if (!checkConst(SubobjType))
2977 return false;
2978 // We've been given ownership of NewVal, so just swap it in.
2979 Subobj.swap(NewVal);
2980 return true;
2981 }
2982 bool found(APSInt &Value, QualType SubobjType) {
2983 if (!checkConst(SubobjType))
2984 return false;
2985 if (!NewVal.isInt()) {
2986 // Maybe trying to write a cast pointer value into a complex?
2987 Info.FFDiag(E);
2988 return false;
2989 }
2990 Value = NewVal.getInt();
2991 return true;
2992 }
2993 bool found(APFloat &Value, QualType SubobjType) {
2994 if (!checkConst(SubobjType))
2995 return false;
2996 Value = NewVal.getFloat();
2997 return true;
2998 }
2999 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3000 llvm_unreachable("shouldn't encounter string elements with ExpandArrays")::llvm::llvm_unreachable_internal("shouldn't encounter string elements with ExpandArrays"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3000)
;
3001 }
3002};
3003} // end anonymous namespace
3004
3005const AccessKinds ModifySubobjectHandler::AccessKind;
3006
3007/// Update the designated sub-object of an rvalue to the given value.
3008static bool modifySubobject(EvalInfo &Info, const Expr *E,
3009 const CompleteObject &Obj,
3010 const SubobjectDesignator &Sub,
3011 APValue &NewVal) {
3012 ModifySubobjectHandler Handler = { Info, NewVal, E };
3013 return findSubobject(Info, E, Obj, Sub, Handler);
3014}
3015
3016/// Find the position where two subobject designators diverge, or equivalently
3017/// the length of the common initial subsequence.
3018static unsigned FindDesignatorMismatch(QualType ObjType,
3019 const SubobjectDesignator &A,
3020 const SubobjectDesignator &B,
3021 bool &WasArrayIndex) {
3022 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3023 for (/**/; I != N; ++I) {
3024 if (!ObjType.isNull() &&
3025 (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3026 // Next subobject is an array element.
3027 if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) {
3028 WasArrayIndex = true;
3029 return I;
3030 }
3031 if (ObjType->isAnyComplexType())
3032 ObjType = ObjType->castAs<ComplexType>()->getElementType();
3033 else
3034 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3035 } else {
3036 if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) {
3037 WasArrayIndex = false;
3038 return I;
3039 }
3040 if (const FieldDecl *FD = getAsField(A.Entries[I]))
3041 // Next subobject is a field.
3042 ObjType = FD->getType();
3043 else
3044 // Next subobject is a base class.
3045 ObjType = QualType();
3046 }
3047 }
3048 WasArrayIndex = false;
3049 return I;
3050}
3051
3052/// Determine whether the given subobject designators refer to elements of the
3053/// same array object.
3054static bool AreElementsOfSameArray(QualType ObjType,
3055 const SubobjectDesignator &A,
3056 const SubobjectDesignator &B) {
3057 if (A.Entries.size() != B.Entries.size())
3058 return false;
3059
3060 bool IsArray = A.MostDerivedIsArrayElement;
3061 if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3062 // A is a subobject of the array element.
3063 return false;
3064
3065 // If A (and B) designates an array element, the last entry will be the array
3066 // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3067 // of length 1' case, and the entire path must match.
3068 bool WasArrayIndex;
3069 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3070 return CommonLength >= A.Entries.size() - IsArray;
3071}
3072
3073/// Find the complete object to which an LValue refers.
3074static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3075 AccessKinds AK, const LValue &LVal,
3076 QualType LValType) {
3077 if (!LVal.Base) {
3078 Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3079 return CompleteObject();
3080 }
3081
3082 CallStackFrame *Frame = nullptr;
3083 if (LVal.getLValueCallIndex()) {
3084 Frame = Info.getCallFrame(LVal.getLValueCallIndex());
3085 if (!Frame) {
3086 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3087 << AK << LVal.Base.is<const ValueDecl*>();
3088 NoteLValueLocation(Info, LVal.Base);
3089 return CompleteObject();
3090 }
3091 }
3092
3093 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3094 // is not a constant expression (even if the object is non-volatile). We also
3095 // apply this rule to C++98, in order to conform to the expected 'volatile'
3096 // semantics.
3097 if (LValType.isVolatileQualified()) {
3098 if (Info.getLangOpts().CPlusPlus)
3099 Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3100 << AK << LValType;
3101 else
3102 Info.FFDiag(E);
3103 return CompleteObject();
3104 }
3105
3106 // Compute value storage location and type of base object.
3107 APValue *BaseVal = nullptr;
3108 QualType BaseType = getType(LVal.Base);
3109 bool LifetimeStartedInEvaluation = Frame;
3110
3111 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) {
3112 // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
3113 // In C++11, constexpr, non-volatile variables initialized with constant
3114 // expressions are constant expressions too. Inside constexpr functions,
3115 // parameters are constant expressions even if they're non-const.
3116 // In C++1y, objects local to a constant expression (those with a Frame) are
3117 // both readable and writable inside constant expressions.
3118 // In C, such things can also be folded, although they are not ICEs.
3119 const VarDecl *VD = dyn_cast<VarDecl>(D);
3120 if (VD) {
3121 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
3122 VD = VDef;
3123 }
3124 if (!VD || VD->isInvalidDecl()) {
3125 Info.FFDiag(E);
3126 return CompleteObject();
3127 }
3128
3129 // Accesses of volatile-qualified objects are not allowed.
3130 if (BaseType.isVolatileQualified()) {
3131 if (Info.getLangOpts().CPlusPlus) {
3132 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3133 << AK << 1 << VD;
3134 Info.Note(VD->getLocation(), diag::note_declared_at);
3135 } else {
3136 Info.FFDiag(E);
3137 }
3138 return CompleteObject();
3139 }
3140
3141 // Unless we're looking at a local variable or argument in a constexpr call,
3142 // the variable we're reading must be const.
3143 if (!Frame) {
3144 if (Info.getLangOpts().CPlusPlus14 &&
3145 VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) {
3146 // OK, we can read and modify an object if we're in the process of
3147 // evaluating its initializer, because its lifetime began in this
3148 // evaluation.
3149 } else if (AK != AK_Read) {
3150 // All the remaining cases only permit reading.
3151 Info.FFDiag(E, diag::note_constexpr_modify_global);
3152 return CompleteObject();
3153 } else if (VD->isConstexpr()) {
3154 // OK, we can read this variable.
3155 } else if (BaseType->isIntegralOrEnumerationType()) {
3156 // In OpenCL if a variable is in constant address space it is a const value.
3157 if (!(BaseType.isConstQualified() ||
3158 (Info.getLangOpts().OpenCL &&
3159 BaseType.getAddressSpace() == LangAS::opencl_constant))) {
3160 if (Info.getLangOpts().CPlusPlus) {
3161 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
3162 Info.Note(VD->getLocation(), diag::note_declared_at);
3163 } else {
3164 Info.FFDiag(E);
3165 }
3166 return CompleteObject();
3167 }
3168 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) {
3169 // We support folding of const floating-point types, in order to make
3170 // static const data members of such types (supported as an extension)
3171 // more useful.
3172 if (Info.getLangOpts().CPlusPlus11) {
3173 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3174 Info.Note(VD->getLocation(), diag::note_declared_at);
3175 } else {
3176 Info.CCEDiag(E);
3177 }
3178 } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
3179 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
3180 // Keep evaluating to see what we can do.
3181 } else {
3182 // FIXME: Allow folding of values of any literal type in all languages.
3183 if (Info.checkingPotentialConstantExpression() &&
3184 VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) {
3185 // The definition of this variable could be constexpr. We can't
3186 // access it right now, but may be able to in future.
3187 } else if (Info.getLangOpts().CPlusPlus11) {
3188 Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3189 Info.Note(VD->getLocation(), diag::note_declared_at);
3190 } else {
3191 Info.FFDiag(E);
3192 }
3193 return CompleteObject();
3194 }
3195 }
3196
3197 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal))
3198 return CompleteObject();
3199 } else {
3200 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3201
3202 if (!Frame) {
3203 if (const MaterializeTemporaryExpr *MTE =
3204 dyn_cast<MaterializeTemporaryExpr>(Base)) {
3205 assert(MTE->getStorageDuration() == SD_Static &&(static_cast <bool> (MTE->getStorageDuration() == SD_Static
&& "should have a frame for a non-global materialized temporary"
) ? void (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3206, __extension__ __PRETTY_FUNCTION__))
3206 "should have a frame for a non-global materialized temporary")(static_cast <bool> (MTE->getStorageDuration() == SD_Static
&& "should have a frame for a non-global materialized temporary"
) ? void (0) : __assert_fail ("MTE->getStorageDuration() == SD_Static && \"should have a frame for a non-global materialized temporary\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3206, __extension__ __PRETTY_FUNCTION__))
;
3207
3208 // Per C++1y [expr.const]p2:
3209 // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
3210 // - a [...] glvalue of integral or enumeration type that refers to
3211 // a non-volatile const object [...]
3212 // [...]
3213 // - a [...] glvalue of literal type that refers to a non-volatile
3214 // object whose lifetime began within the evaluation of e.
3215 //
3216 // C++11 misses the 'began within the evaluation of e' check and
3217 // instead allows all temporaries, including things like:
3218 // int &&r = 1;
3219 // int x = ++r;
3220 // constexpr int k = r;
3221 // Therefore we use the C++14 rules in C++11 too.
3222 const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
3223 const ValueDecl *ED = MTE->getExtendingDecl();
3224 if (!(BaseType.isConstQualified() &&
3225 BaseType->isIntegralOrEnumerationType()) &&
3226 !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) {
3227 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
3228 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
3229 return CompleteObject();
3230 }
3231
3232 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
3233 assert(BaseVal && "got reference to unevaluated temporary")(static_cast <bool> (BaseVal && "got reference to unevaluated temporary"
) ? void (0) : __assert_fail ("BaseVal && \"got reference to unevaluated temporary\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3233, __extension__ __PRETTY_FUNCTION__))
;
3234 LifetimeStartedInEvaluation = true;
3235 } else {
3236 Info.FFDiag(E);
3237 return CompleteObject();
3238 }
3239 } else {
3240 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
3241 assert(BaseVal && "missing value for temporary")(static_cast <bool> (BaseVal && "missing value for temporary"
) ? void (0) : __assert_fail ("BaseVal && \"missing value for temporary\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3241, __extension__ __PRETTY_FUNCTION__))
;
3242 }
3243
3244 // Volatile temporary objects cannot be accessed in constant expressions.
3245 if (BaseType.isVolatileQualified()) {
3246 if (Info.getLangOpts().CPlusPlus) {
3247 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3248 << AK << 0;
3249 Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here);
3250 } else {
3251 Info.FFDiag(E);
3252 }
3253 return CompleteObject();
3254 }
3255 }
3256
3257 // During the construction of an object, it is not yet 'const'.
3258 // FIXME: This doesn't do quite the right thing for const subobjects of the
3259 // object under construction.
3260 if (Info.isEvaluatingConstructor(LVal.getLValueBase(),
3261 LVal.getLValueCallIndex(),
3262 LVal.getLValueVersion())) {
3263 BaseType = Info.Ctx.getCanonicalType(BaseType);
3264 BaseType.removeLocalConst();
3265 LifetimeStartedInEvaluation = true;
3266 }
3267
3268 // In C++14, we can't safely access any mutable state when we might be
3269 // evaluating after an unmodeled side effect.
3270 //
3271 // FIXME: Not all local state is mutable. Allow local constant subobjects
3272 // to be read here (but take care with 'mutable' fields).
3273 if ((Frame && Info.getLangOpts().CPlusPlus14 &&
3274 Info.EvalStatus.HasSideEffects) ||
3275 (AK != AK_Read && Info.IsSpeculativelyEvaluating))
3276 return CompleteObject();
3277
3278 return CompleteObject(BaseVal, BaseType, LifetimeStartedInEvaluation);
3279}
3280
3281/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
3282/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
3283/// glvalue referred to by an entity of reference type.
3284///
3285/// \param Info - Information about the ongoing evaluation.
3286/// \param Conv - The expression for which we are performing the conversion.
3287/// Used for diagnostics.
3288/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
3289/// case of a non-class type).
3290/// \param LVal - The glvalue on which we are attempting to perform this action.
3291/// \param RVal - The produced value will be placed here.
3292static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
3293 QualType Type,
3294 const LValue &LVal, APValue &RVal) {
3295 if (LVal.Designator.Invalid)
3296 return false;
3297
3298 // Check for special cases where there is no existing APValue to look at.
3299 const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3300 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
3301 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
3302 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
3303 // initializer until now for such expressions. Such an expression can't be
3304 // an ICE in C, so this only matters for fold.
3305 if (Type.isVolatileQualified()) {
3306 Info.FFDiag(Conv);
3307 return false;
3308 }
3309 APValue Lit;
3310 if (!Evaluate(Lit, Info, CLE->getInitializer()))
3311 return false;
3312 CompleteObject LitObj(&Lit, Base->getType(), false);
3313 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal);
3314 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
3315 // We represent a string literal array as an lvalue pointing at the
3316 // corresponding expression, rather than building an array of chars.
3317 // FIXME: Support ObjCEncodeExpr, MakeStringConstant
3318 APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0);
3319 CompleteObject StrObj(&Str, Base->getType(), false);
3320 return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal);
3321 }
3322 }
3323
3324 CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type);
3325 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal);
3326}
3327
3328/// Perform an assignment of Val to LVal. Takes ownership of Val.
3329static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
3330 QualType LValType, APValue &Val) {
3331 if (LVal.Designator.Invalid)
3332 return false;
3333
3334 if (!Info.getLangOpts().CPlusPlus14) {
3335 Info.FFDiag(E);
3336 return false;
3337 }
3338
3339 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3340 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
3341}
3342
3343namespace {
3344struct CompoundAssignSubobjectHandler {
3345 EvalInfo &Info;
3346 const Expr *E;
3347 QualType PromotedLHSType;
3348 BinaryOperatorKind Opcode;
3349 const APValue &RHS;
3350
3351 static const AccessKinds AccessKind = AK_Assign;
3352
3353 typedef bool result_type;
3354
3355 bool checkConst(QualType QT) {
3356 // Assigning to a const object has undefined behavior.
3357 if (QT.isConstQualified()) {
3358 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3359 return false;
3360 }
3361 return true;
3362 }
3363
3364 bool failed() { return false; }
3365 bool found(APValue &Subobj, QualType SubobjType) {
3366 switch (Subobj.getKind()) {
3367 case APValue::Int:
3368 return found(Subobj.getInt(), SubobjType);
3369 case APValue::Float:
3370 return found(Subobj.getFloat(), SubobjType);
3371 case APValue::ComplexInt:
3372 case APValue::ComplexFloat:
3373 // FIXME: Implement complex compound assignment.
3374 Info.FFDiag(E);
3375 return false;
3376 case APValue::LValue:
3377 return foundPointer(Subobj, SubobjType);
3378 default:
3379 // FIXME: can this happen?
3380 Info.FFDiag(E);
3381 return false;
3382 }
3383 }
3384 bool found(APSInt &Value, QualType SubobjType) {
3385 if (!checkConst(SubobjType))
3386 return false;
3387
3388 if (!SubobjType->isIntegerType() || !RHS.isInt()) {
3389 // We don't support compound assignment on integer-cast-to-pointer
3390 // values.
3391 Info.FFDiag(E);
3392 return false;
3393 }
3394
3395 APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType,
3396 SubobjType, Value);
3397 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
3398 return false;
3399 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
3400 return true;
3401 }
3402 bool found(APFloat &Value, QualType SubobjType) {
3403 return checkConst(SubobjType) &&
3404 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
3405 Value) &&
3406 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
3407 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
3408 }
3409 bool foundPointer(APValue &Subobj, QualType SubobjType) {
3410 if (!checkConst(SubobjType))
3411 return false;
3412
3413 QualType PointeeType;
3414 if (const PointerType *PT = SubobjType->getAs<PointerType>())
3415 PointeeType = PT->getPointeeType();
3416
3417 if (PointeeType.isNull() || !RHS.isInt() ||
3418 (Opcode != BO_Add && Opcode != BO_Sub)) {
3419 Info.FFDiag(E);
3420 return false;
3421 }
3422
3423 APSInt Offset = RHS.getInt();
3424 if (Opcode == BO_Sub)
3425 negateAsSigned(Offset);
3426
3427 LValue LVal;
3428 LVal.setFrom(Info.Ctx, Subobj);
3429 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
3430 return false;
3431 LVal.moveInto(Subobj);
3432 return true;
3433 }
3434 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3435 llvm_unreachable("shouldn't encounter string elements here")::llvm::llvm_unreachable_internal("shouldn't encounter string elements here"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3435)
;
3436 }
3437};
3438} // end anonymous namespace
3439
3440const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
3441
3442/// Perform a compound assignment of LVal <op>= RVal.
3443static bool handleCompoundAssignment(
3444 EvalInfo &Info, const Expr *E,
3445 const LValue &LVal, QualType LValType, QualType PromotedLValType,
3446 BinaryOperatorKind Opcode, const APValue &RVal) {
3447 if (LVal.Designator.Invalid)
3448 return false;
3449
3450 if (!Info.getLangOpts().CPlusPlus14) {
3451 Info.FFDiag(E);
3452 return false;
3453 }
3454
3455 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3456 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
3457 RVal };
3458 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3459}
3460
3461namespace {
3462struct IncDecSubobjectHandler {
3463 EvalInfo &Info;
3464 const UnaryOperator *E;
3465 AccessKinds AccessKind;
3466 APValue *Old;
3467
3468 typedef bool result_type;
3469
3470 bool checkConst(QualType QT) {
3471 // Assigning to a const object has undefined behavior.
3472 if (QT.isConstQualified()) {
3473 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3474 return false;
3475 }
3476 return true;
3477 }
3478
3479 bool failed() { return false; }
3480 bool found(APValue &Subobj, QualType SubobjType) {
3481 // Stash the old value. Also clear Old, so we don't clobber it later
3482 // if we're post-incrementing a complex.
3483 if (Old) {
3484 *Old = Subobj;
3485 Old = nullptr;
3486 }
3487
3488 switch (Subobj.getKind()) {
3489 case APValue::Int:
3490 return found(Subobj.getInt(), SubobjType);
3491 case APValue::Float:
3492 return found(Subobj.getFloat(), SubobjType);
3493 case APValue::ComplexInt:
3494 return found(Subobj.getComplexIntReal(),
3495 SubobjType->castAs<ComplexType>()->getElementType()
3496 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3497 case APValue::ComplexFloat:
3498 return found(Subobj.getComplexFloatReal(),
3499 SubobjType->castAs<ComplexType>()->getElementType()
3500 .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3501 case APValue::LValue:
3502 return foundPointer(Subobj, SubobjType);
3503 default:
3504 // FIXME: can this happen?
3505 Info.FFDiag(E);
3506 return false;
3507 }
3508 }
3509 bool found(APSInt &Value, QualType SubobjType) {
3510 if (!checkConst(SubobjType))
3511 return false;
3512
3513 if (!SubobjType->isIntegerType()) {
3514 // We don't support increment / decrement on integer-cast-to-pointer
3515 // values.
3516 Info.FFDiag(E);
3517 return false;
3518 }
3519
3520 if (Old) *Old = APValue(Value);
3521
3522 // bool arithmetic promotes to int, and the conversion back to bool
3523 // doesn't reduce mod 2^n, so special-case it.
3524 if (SubobjType->isBooleanType()) {
3525 if (AccessKind == AK_Increment)
3526 Value = 1;
3527 else
3528 Value = !Value;
3529 return true;
3530 }
3531
3532 bool WasNegative = Value.isNegative();
3533 if (AccessKind == AK_Increment) {
3534 ++Value;
3535
3536 if (!WasNegative && Value.isNegative() && E->canOverflow()) {
3537 APSInt ActualValue(Value, /*IsUnsigned*/true);
3538 return HandleOverflow(Info, E, ActualValue, SubobjType);
3539 }
3540 } else {
3541 --Value;
3542
3543 if (WasNegative && !Value.isNegative() && E->canOverflow()) {
3544 unsigned BitWidth = Value.getBitWidth();
3545 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
3546 ActualValue.setBit(BitWidth);
3547 return HandleOverflow(Info, E, ActualValue, SubobjType);
3548 }
3549 }
3550 return true;
3551 }
3552 bool found(APFloat &Value, QualType SubobjType) {
3553 if (!checkConst(SubobjType))
3554 return false;
3555
3556 if (Old) *Old = APValue(Value);
3557
3558 APFloat One(Value.getSemantics(), 1);
3559 if (AccessKind == AK_Increment)
3560 Value.add(One, APFloat::rmNearestTiesToEven);
3561 else
3562 Value.subtract(One, APFloat::rmNearestTiesToEven);
3563 return true;
3564 }
3565 bool foundPointer(APValue &Subobj, QualType SubobjType) {
3566 if (!checkConst(SubobjType))
3567 return false;
3568
3569 QualType PointeeType;
3570 if (const PointerType *PT = SubobjType->getAs<PointerType>())
3571 PointeeType = PT->getPointeeType();
3572 else {
3573 Info.FFDiag(E);
3574 return false;
3575 }
3576
3577 LValue LVal;
3578 LVal.setFrom(Info.Ctx, Subobj);
3579 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
3580 AccessKind == AK_Increment ? 1 : -1))
3581 return false;
3582 LVal.moveInto(Subobj);
3583 return true;
3584 }
3585 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3586 llvm_unreachable("shouldn't encounter string elements here")::llvm::llvm_unreachable_internal("shouldn't encounter string elements here"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3586)
;
3587 }
3588};
3589} // end anonymous namespace
3590
3591/// Perform an increment or decrement on LVal.
3592static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
3593 QualType LValType, bool IsIncrement, APValue *Old) {
3594 if (LVal.Designator.Invalid)
3595 return false;
3596
3597 if (!Info.getLangOpts().CPlusPlus14) {
3598 Info.FFDiag(E);
3599 return false;
3600 }
3601
3602 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
3603 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
3604 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
3605 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3606}
3607
3608/// Build an lvalue for the object argument of a member function call.
3609static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
3610 LValue &This) {
3611 if (Object->getType()->isPointerType())
3612 return EvaluatePointer(Object, This, Info);
3613
3614 if (Object->isGLValue())
3615 return EvaluateLValue(Object, This, Info);
3616
3617 if (Object->getType()->isLiteralType(Info.Ctx))
3618 return EvaluateTemporary(Object, This, Info);
3619
3620 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
3621 return false;
3622}
3623
3624/// HandleMemberPointerAccess - Evaluate a member access operation and build an
3625/// lvalue referring to the result.
3626///
3627/// \param Info - Information about the ongoing evaluation.
3628/// \param LV - An lvalue referring to the base of the member pointer.
3629/// \param RHS - The member pointer expression.
3630/// \param IncludeMember - Specifies whether the member itself is included in
3631/// the resulting LValue subobject designator. This is not possible when
3632/// creating a bound member function.
3633/// \return The field or method declaration to which the member pointer refers,
3634/// or 0 if evaluation fails.
3635static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3636 QualType LVType,
3637 LValue &LV,
3638 const Expr *RHS,
3639 bool IncludeMember = true) {
3640 MemberPtr MemPtr;
3641 if (!EvaluateMemberPointer(RHS, MemPtr, Info))
3642 return nullptr;
3643
3644 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
3645 // member value, the behavior is undefined.
3646 if (!MemPtr.getDecl()) {
3647 // FIXME: Specific diagnostic.
3648 Info.FFDiag(RHS);
3649 return nullptr;
3650 }
3651
3652 if (MemPtr.isDerivedMember()) {
3653 // This is a member of some derived class. Truncate LV appropriately.
3654 // The end of the derived-to-base path for the base object must match the
3655 // derived-to-base path for the member pointer.
3656 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
3657 LV.Designator.Entries.size()) {
3658 Info.FFDiag(RHS);
3659 return nullptr;
3660 }
3661 unsigned PathLengthToMember =
3662 LV.Designator.Entries.size() - MemPtr.Path.size();
3663 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
3664 const CXXRecordDecl *LVDecl = getAsBaseClass(
3665 LV.Designator.Entries[PathLengthToMember + I]);
3666 const CXXRecordDecl *MPDecl = MemPtr.Path[I];
3667 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
3668 Info.FFDiag(RHS);
3669 return nullptr;
3670 }
3671 }
3672
3673 // Truncate the lvalue to the appropriate derived class.
3674 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
3675 PathLengthToMember))
3676 return nullptr;
3677 } else if (!MemPtr.Path.empty()) {
3678 // Extend the LValue path with the member pointer's path.
3679 LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
3680 MemPtr.Path.size() + IncludeMember);
3681
3682 // Walk down to the appropriate base class.
3683 if (const PointerType *PT = LVType->getAs<PointerType>())
3684 LVType = PT->getPointeeType();
3685 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
3686 assert(RD && "member pointer access on non-class-type expression")(static_cast <bool> (RD && "member pointer access on non-class-type expression"
) ? void (0) : __assert_fail ("RD && \"member pointer access on non-class-type expression\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3686, __extension__ __PRETTY_FUNCTION__))
;
3687 // The first class in the path is that of the lvalue.
3688 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
3689 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
3690 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
3691 return nullptr;
3692 RD = Base;
3693 }
3694 // Finally cast to the class containing the member.
3695 if (!HandleLValueDirectBase(Info, RHS, LV, RD,
3696 MemPtr.getContainingRecord()))
3697 return nullptr;
3698 }
3699
3700 // Add the member. Note that we cannot build bound member functions here.
3701 if (IncludeMember) {
3702 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
3703 if (!HandleLValueMember(Info, RHS, LV, FD))
3704 return nullptr;
3705 } else if (const IndirectFieldDecl *IFD =
3706 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
3707 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
3708 return nullptr;
3709 } else {
3710 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3710)
;
3711 }
3712 }
3713
3714 return MemPtr.getDecl();
3715}
3716
3717static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3718 const BinaryOperator *BO,
3719 LValue &LV,
3720 bool IncludeMember = true) {
3721 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI)(static_cast <bool> (BO->getOpcode() == BO_PtrMemD ||
BO->getOpcode() == BO_PtrMemI) ? void (0) : __assert_fail
("BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3721, __extension__ __PRETTY_FUNCTION__))
;
3722
3723 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
3724 if (Info.noteFailure()) {
3725 MemberPtr MemPtr;
3726 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
3727 }
3728 return nullptr;
3729 }
3730
3731 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
3732 BO->getRHS(), IncludeMember);
3733}
3734
3735/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
3736/// the provided lvalue, which currently refers to the base object.
3737static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
3738 LValue &Result) {
3739 SubobjectDesignator &D = Result.Designator;
3740 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
3741 return false;
3742
3743 QualType TargetQT = E->getType();
3744 if (const PointerType *PT = TargetQT->getAs<PointerType>())
3745 TargetQT = PT->getPointeeType();
3746
3747 // Check this cast lands within the final derived-to-base subobject path.
3748 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
3749 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3750 << D.MostDerivedType << TargetQT;
3751 return false;
3752 }
3753
3754 // Check the type of the final cast. We don't need to check the path,
3755 // since a cast can only be formed if the path is unique.
3756 unsigned NewEntriesSize = D.Entries.size() - E->path_size();
3757 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
3758 const CXXRecordDecl *FinalType;
3759 if (NewEntriesSize == D.MostDerivedPathLength)
3760 FinalType = D.MostDerivedType->getAsCXXRecordDecl();
3761 else
3762 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
3763 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
3764 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3765 << D.MostDerivedType << TargetQT;
3766 return false;
3767 }
3768
3769 // Truncate the lvalue to the appropriate derived class.
3770 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
3771}
3772
3773namespace {
3774enum EvalStmtResult {
3775 /// Evaluation failed.
3776 ESR_Failed,
3777 /// Hit a 'return' statement.
3778 ESR_Returned,
3779 /// Evaluation succeeded.
3780 ESR_Succeeded,
3781 /// Hit a 'continue' statement.
3782 ESR_Continue,
3783 /// Hit a 'break' statement.
3784 ESR_Break,
3785 /// Still scanning for 'case' or 'default' statement.
3786 ESR_CaseNotFound
3787};
3788}
3789
3790static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
3791 // We don't need to evaluate the initializer for a static local.
3792 if (!VD->hasLocalStorage())
3793 return true;
3794
3795 LValue Result;
3796 APValue &Val = createTemporary(VD, true, Result, *Info.CurrentCall);
3797
3798 const Expr *InitE = VD->getInit();
3799 if (!InitE) {
3800 Info.FFDiag(VD->getLocStart(), diag::note_constexpr_uninitialized)
3801 << false << VD->getType();
3802 Val = APValue();
3803 return false;
3804 }
3805
3806 if (InitE->isValueDependent())
3807 return false;
3808
3809 if (!EvaluateInPlace(Val, Info, Result, InitE)) {
3810 // Wipe out any partially-computed value, to allow tracking that this
3811 // evaluation failed.
3812 Val = APValue();
3813 return false;
3814 }
3815
3816 return true;
3817}
3818
3819static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
3820 bool OK = true;
3821
3822 if (const VarDecl *VD = dyn_cast<VarDecl>(D))
3823 OK &= EvaluateVarDecl(Info, VD);
3824
3825 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
3826 for (auto *BD : DD->bindings())
3827 if (auto *VD = BD->getHoldingVar())
3828 OK &= EvaluateDecl(Info, VD);
3829
3830 return OK;
3831}
3832
3833
3834/// Evaluate a condition (either a variable declaration or an expression).
3835static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
3836 const Expr *Cond, bool &Result) {
3837 FullExpressionRAII Scope(Info);
3838 if (CondDecl && !EvaluateDecl(Info, CondDecl))
3839 return false;
3840 return EvaluateAsBooleanCondition(Cond, Result, Info);
3841}
3842
3843namespace {
3844/// A location where the result (returned value) of evaluating a
3845/// statement should be stored.
3846struct StmtResult {
3847 /// The APValue that should be filled in with the returned value.
3848 APValue &Value;
3849 /// The location containing the result, if any (used to support RVO).
3850 const LValue *Slot;
3851};
3852
3853struct TempVersionRAII {
3854 CallStackFrame &Frame;
3855
3856 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
3857 Frame.pushTempVersion();
3858 }
3859
3860 ~TempVersionRAII() {
3861 Frame.popTempVersion();
3862 }
3863};
3864
3865}
3866
3867static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
3868 const Stmt *S,
3869 const SwitchCase *SC = nullptr);
3870
3871/// Evaluate the body of a loop, and translate the result as appropriate.
3872static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
3873 const Stmt *Body,
3874 const SwitchCase *Case = nullptr) {
3875 BlockScopeRAII Scope(Info);
3876 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) {
3877 case ESR_Break:
3878 return ESR_Succeeded;
3879 case ESR_Succeeded:
3880 case ESR_Continue:
3881 return ESR_Continue;
3882 case ESR_Failed:
3883 case ESR_Returned:
3884 case ESR_CaseNotFound:
3885 return ESR;
3886 }
3887 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3887)
;
3888}
3889
3890/// Evaluate a switch statement.
3891static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
3892 const SwitchStmt *SS) {
3893 BlockScopeRAII Scope(Info);
3894
3895 // Evaluate the switch condition.
3896 APSInt Value;
3897 {
3898 FullExpressionRAII Scope(Info);
3899 if (const Stmt *Init = SS->getInit()) {
3900 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
3901 if (ESR != ESR_Succeeded)
3902 return ESR;
3903 }
3904 if (SS->getConditionVariable() &&
3905 !EvaluateDecl(Info, SS->getConditionVariable()))
3906 return ESR_Failed;
3907 if (!EvaluateInteger(SS->getCond(), Value, Info))
3908 return ESR_Failed;
3909 }
3910
3911 // Find the switch case corresponding to the value of the condition.
3912 // FIXME: Cache this lookup.
3913 const SwitchCase *Found = nullptr;
3914 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
3915 SC = SC->getNextSwitchCase()) {
3916 if (isa<DefaultStmt>(SC)) {
3917 Found = SC;
3918 continue;
3919 }
3920
3921 const CaseStmt *CS = cast<CaseStmt>(SC);
3922 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
3923 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
3924 : LHS;
3925 if (LHS <= Value && Value <= RHS) {
3926 Found = SC;
3927 break;
3928 }
3929 }
3930
3931 if (!Found)
3932 return ESR_Succeeded;
3933
3934 // Search the switch body for the switch case and evaluate it from there.
3935 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) {
3936 case ESR_Break:
3937 return ESR_Succeeded;
3938 case ESR_Succeeded:
3939 case ESR_Continue:
3940 case ESR_Failed:
3941 case ESR_Returned:
3942 return ESR;
3943 case ESR_CaseNotFound:
3944 // This can only happen if the switch case is nested within a statement
3945 // expression. We have no intention of supporting that.
3946 Info.FFDiag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported);
3947 return ESR_Failed;
3948 }
3949 llvm_unreachable("Invalid EvalStmtResult!")::llvm::llvm_unreachable_internal("Invalid EvalStmtResult!", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 3949)
;
3950}
3951
3952// Evaluate a statement.
3953static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
3954 const Stmt *S, const SwitchCase *Case) {
3955 if (!Info.nextStep(S))
3956 return ESR_Failed;
3957
3958 // If we're hunting down a 'case' or 'default' label, recurse through
3959 // substatements until we hit the label.
3960 if (Case) {
3961 // FIXME: We don't start the lifetime of objects whose initialization we
3962 // jump over. However, such objects must be of class type with a trivial
3963 // default constructor that initialize all subobjects, so must be empty,
3964 // so this almost never matters.
3965 switch (S->getStmtClass()) {
3966 case Stmt::CompoundStmtClass:
3967 // FIXME: Precompute which substatement of a compound statement we
3968 // would jump to, and go straight there rather than performing a
3969 // linear scan each time.
3970 case Stmt::LabelStmtClass:
3971 case Stmt::AttributedStmtClass:
3972 case Stmt::DoStmtClass:
3973 break;
3974
3975 case Stmt::CaseStmtClass:
3976 case Stmt::DefaultStmtClass:
3977 if (Case == S)
3978 Case = nullptr;
3979 break;
3980
3981 case Stmt::IfStmtClass: {
3982 // FIXME: Precompute which side of an 'if' we would jump to, and go
3983 // straight there rather than scanning both sides.
3984 const IfStmt *IS = cast<IfStmt>(S);
3985
3986 // Wrap the evaluation in a block scope, in case it's a DeclStmt
3987 // preceded by our switch label.
3988 BlockScopeRAII Scope(Info);
3989
3990 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
3991 if (ESR != ESR_CaseNotFound || !IS->getElse())
3992 return ESR;
3993 return EvaluateStmt(Result, Info, IS->getElse(), Case);
3994 }
3995
3996 case Stmt::WhileStmtClass: {
3997 EvalStmtResult ESR =
3998 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
3999 if (ESR != ESR_Continue)
4000 return ESR;
4001 break;
4002 }
4003
4004 case Stmt::ForStmtClass: {
4005 const ForStmt *FS = cast<ForStmt>(S);
4006 EvalStmtResult ESR =
4007 EvaluateLoopBody(Result, Info, FS->getBody(), Case);
4008 if (ESR != ESR_Continue)
4009 return ESR;
4010 if (FS->getInc()) {
4011 FullExpressionRAII IncScope(Info);
4012 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4013 return ESR_Failed;
4014 }
4015 break;
4016 }
4017
4018 case Stmt::DeclStmtClass:
4019 // FIXME: If the variable has initialization that can't be jumped over,
4020 // bail out of any immediately-surrounding compound-statement too.
4021 default:
4022 return ESR_CaseNotFound;
4023 }
4024 }
4025
4026 switch (S->getStmtClass()) {
4027 default:
4028 if (const Expr *E = dyn_cast<Expr>(S)) {
4029 // Don't bother evaluating beyond an expression-statement which couldn't
4030 // be evaluated.
4031 FullExpressionRAII Scope(Info);
4032 if (!EvaluateIgnoredValue(Info, E))
4033 return ESR_Failed;
4034 return ESR_Succeeded;
4035 }
4036
4037 Info.FFDiag(S->getLocStart());
4038 return ESR_Failed;
4039
4040 case Stmt::NullStmtClass:
4041 return ESR_Succeeded;
4042
4043 case Stmt::DeclStmtClass: {
4044 const DeclStmt *DS = cast<DeclStmt>(S);
4045 for (const auto *DclIt : DS->decls()) {
4046 // Each declaration initialization is its own full-expression.
4047 // FIXME: This isn't quite right; if we're performing aggregate
4048 // initialization, each braced subexpression is its own full-expression.
4049 FullExpressionRAII Scope(Info);
4050 if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure())
4051 return ESR_Failed;
4052 }
4053 return ESR_Succeeded;
4054 }
4055
4056 case Stmt::ReturnStmtClass: {
4057 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
4058 FullExpressionRAII Scope(Info);
4059 if (RetExpr &&
4060 !(Result.Slot
4061 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
4062 : Evaluate(Result.Value, Info, RetExpr)))
4063 return ESR_Failed;
4064 return ESR_Returned;
4065 }
4066
4067 case Stmt::CompoundStmtClass: {
4068 BlockScopeRAII Scope(Info);
4069
4070 const CompoundStmt *CS = cast<CompoundStmt>(S);
4071 for (const auto *BI : CS->body()) {
4072 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
4073 if (ESR == ESR_Succeeded)
4074 Case = nullptr;
4075 else if (ESR != ESR_CaseNotFound)
4076 return ESR;
4077 }
4078 return Case ? ESR_CaseNotFound : ESR_Succeeded;
4079 }
4080
4081 case Stmt::IfStmtClass: {
4082 const IfStmt *IS = cast<IfStmt>(S);
4083
4084 // Evaluate the condition, as either a var decl or as an expression.
4085 BlockScopeRAII Scope(Info);
4086 if (const Stmt *Init = IS->getInit()) {
4087 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4088 if (ESR != ESR_Succeeded)
4089 return ESR;
4090 }
4091 bool Cond;
4092 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
4093 return ESR_Failed;
4094
4095 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
4096 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
4097 if (ESR != ESR_Succeeded)
4098 return ESR;
4099 }
4100 return ESR_Succeeded;
4101 }
4102
4103 case Stmt::WhileStmtClass: {
4104 const WhileStmt *WS = cast<WhileStmt>(S);
4105 while (true) {
4106 BlockScopeRAII Scope(Info);
4107 bool Continue;
4108 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
4109 Continue))
4110 return ESR_Failed;
4111 if (!Continue)
4112 break;
4113
4114 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
4115 if (ESR != ESR_Continue)
4116 return ESR;
4117 }
4118 return ESR_Succeeded;
4119 }
4120
4121 case Stmt::DoStmtClass: {
4122 const DoStmt *DS = cast<DoStmt>(S);
4123 bool Continue;
4124 do {
4125 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
4126 if (ESR != ESR_Continue)
4127 return ESR;
4128 Case = nullptr;
4129
4130 FullExpressionRAII CondScope(Info);
4131 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info))
4132 return ESR_Failed;
4133 } while (Continue);
4134 return ESR_Succeeded;
4135 }
4136
4137 case Stmt::ForStmtClass: {
4138 const ForStmt *FS = cast<ForStmt>(S);
4139 BlockScopeRAII Scope(Info);
4140 if (FS->getInit()) {
4141 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4142 if (ESR != ESR_Succeeded)
4143 return ESR;
4144 }
4145 while (true) {
4146 BlockScopeRAII Scope(Info);
4147 bool Continue = true;
4148 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
4149 FS->getCond(), Continue))
4150 return ESR_Failed;
4151 if (!Continue)
4152 break;
4153
4154 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4155 if (ESR != ESR_Continue)
4156 return ESR;
4157
4158 if (FS->getInc()) {
4159 FullExpressionRAII IncScope(Info);
4160 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4161 return ESR_Failed;
4162 }
4163 }
4164 return ESR_Succeeded;
4165 }
4166
4167 case Stmt::CXXForRangeStmtClass: {
4168 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
4169 BlockScopeRAII Scope(Info);
4170
4171 // Initialize the __range variable.
4172 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
4173 if (ESR != ESR_Succeeded)
4174 return ESR;
4175
4176 // Create the __begin and __end iterators.
4177 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
4178 if (ESR != ESR_Succeeded)
4179 return ESR;
4180 ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
4181 if (ESR != ESR_Succeeded)
4182 return ESR;
4183
4184 while (true) {
4185 // Condition: __begin != __end.
4186 {
4187 bool Continue = true;
4188 FullExpressionRAII CondExpr(Info);
4189 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
4190 return ESR_Failed;
4191 if (!Continue)
4192 break;
4193 }
4194
4195 // User's variable declaration, initialized by *__begin.
4196 BlockScopeRAII InnerScope(Info);
4197 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
4198 if (ESR != ESR_Succeeded)
4199 return ESR;
4200
4201 // Loop body.
4202 ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4203 if (ESR != ESR_Continue)
4204 return ESR;
4205
4206 // Increment: ++__begin
4207 if (!EvaluateIgnoredValue(Info, FS->getInc()))
4208 return ESR_Failed;
4209 }
4210
4211 return ESR_Succeeded;
4212 }
4213
4214 case Stmt::SwitchStmtClass:
4215 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
4216
4217 case Stmt::ContinueStmtClass:
4218 return ESR_Continue;
4219
4220 case Stmt::BreakStmtClass:
4221 return ESR_Break;
4222
4223 case Stmt::LabelStmtClass:
4224 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
4225
4226 case Stmt::AttributedStmtClass:
4227 // As a general principle, C++11 attributes can be ignored without
4228 // any semantic impact.
4229 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
4230 Case);
4231
4232 case Stmt::CaseStmtClass:
4233 case Stmt::DefaultStmtClass:
4234 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
4235 }
4236}
4237
4238/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
4239/// default constructor. If so, we'll fold it whether or not it's marked as
4240/// constexpr. If it is marked as constexpr, we will never implicitly define it,
4241/// so we need special handling.
4242static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
4243 const CXXConstructorDecl *CD,
4244 bool IsValueInitialization) {
4245 if (!CD->isTrivial() || !CD->isDefaultConstructor())
4246 return false;
4247
4248 // Value-initialization does not call a trivial default constructor, so such a
4249 // call is a core constant expression whether or not the constructor is
4250 // constexpr.
4251 if (!CD->isConstexpr() && !IsValueInitialization) {
4252 if (Info.getLangOpts().CPlusPlus11) {
4253 // FIXME: If DiagDecl is an implicitly-declared special member function,
4254 // we should be much more explicit about why it's not constexpr.
4255 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
4256 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
4257 Info.Note(CD->getLocation(), diag::note_declared_at);
4258 } else {
4259 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
4260 }
4261 }
4262 return true;
4263}
4264
4265/// CheckConstexprFunction - Check that a function can be called in a constant
4266/// expression.
4267static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
4268 const FunctionDecl *Declaration,
4269 const FunctionDecl *Definition,
4270 const Stmt *Body) {
4271 // Potential constant expressions can contain calls to declared, but not yet
4272 // defined, constexpr functions.
4273 if (Info.checkingPotentialConstantExpression() && !Definition &&
4274 Declaration->isConstexpr())
4275 return false;
4276
4277 // Bail out with no diagnostic if the function declaration itself is invalid.
4278 // We will have produced a relevant diagnostic while parsing it.
4279 if (Declaration->isInvalidDecl())
4280 return false;
4281
4282 // Can we evaluate this function call?
4283 if (Definition && Definition->isConstexpr() &&
4284 !Definition->isInvalidDecl() && Body)
4285 return true;
4286
4287 if (Info.getLangOpts().CPlusPlus11) {
4288 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
4289
4290 // If this function is not constexpr because it is an inherited
4291 // non-constexpr constructor, diagnose that directly.
4292 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
4293 if (CD && CD->isInheritingConstructor()) {
4294 auto *Inherited = CD->getInheritedConstructor().getConstructor();
4295 if (!Inherited->isConstexpr())
4296 DiagDecl = CD = Inherited;
4297 }
4298
4299 // FIXME: If DiagDecl is an implicitly-declared special member function
4300 // or an inheriting constructor, we should be much more explicit about why
4301 // it's not constexpr.
4302 if (CD && CD->isInheritingConstructor())
4303 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
4304 << CD->getInheritedConstructor().getConstructor()->getParent();
4305 else
4306 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
4307 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
4308 Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
4309 } else {
4310 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4311 }
4312 return false;
4313}
4314
4315/// Determine if a class has any fields that might need to be copied by a
4316/// trivial copy or move operation.
4317static bool hasFields(const CXXRecordDecl *RD) {
4318 if (!RD || RD->isEmpty())
4319 return false;
4320 for (auto *FD : RD->fields()) {
4321 if (FD->isUnnamedBitfield())
4322 continue;
4323 return true;
4324 }
4325 for (auto &Base : RD->bases())
4326 if (hasFields(Base.getType()->getAsCXXRecordDecl()))
4327 return true;
4328 return false;
4329}
4330
4331namespace {
4332typedef SmallVector<APValue, 8> ArgVector;
4333}
4334
4335/// EvaluateArgs - Evaluate the arguments to a function call.
4336static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues,
4337 EvalInfo &Info) {
4338 bool Success = true;
4339 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
4340 I != E; ++I) {
4341 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) {
4342 // If we're checking for a potential constant expression, evaluate all
4343 // initializers even if some of them fail.
4344 if (!Info.noteFailure())
4345 return false;
4346 Success = false;
4347 }
4348 }
4349 return Success;
4350}
4351
4352/// Evaluate a function call.
4353static bool HandleFunctionCall(SourceLocation CallLoc,
4354 const FunctionDecl *Callee, const LValue *This,
4355 ArrayRef<const Expr*> Args, const Stmt *Body,
4356 EvalInfo &Info, APValue &Result,
4357 const LValue *ResultSlot) {
4358 ArgVector ArgValues(Args.size());
4359 if (!EvaluateArgs(Args, ArgValues, Info))
4360 return false;
4361
4362 if (!Info.CheckCallLimit(CallLoc))
4363 return false;
4364
4365 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
4366
4367 // For a trivial copy or move assignment, perform an APValue copy. This is
4368 // essential for unions, where the operations performed by the assignment
4369 // operator cannot be represented as statements.
4370 //
4371 // Skip this for non-union classes with no fields; in that case, the defaulted
4372 // copy/move does not actually read the object.
4373 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
4374 if (MD && MD->isDefaulted() &&
4375 (MD->getParent()->isUnion() ||
4376 (MD->isTrivial() && hasFields(MD->getParent())))) {
4377 assert(This &&(static_cast <bool> (This && (MD->isCopyAssignmentOperator
() || MD->isMoveAssignmentOperator())) ? void (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4378, __extension__ __PRETTY_FUNCTION__))
4378 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()))(static_cast <bool> (This && (MD->isCopyAssignmentOperator
() || MD->isMoveAssignmentOperator())) ? void (0) : __assert_fail
("This && (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4378, __extension__ __PRETTY_FUNCTION__))
;
4379 LValue RHS;
4380 RHS.setFrom(Info.Ctx, ArgValues[0]);
4381 APValue RHSValue;
4382 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(),
4383 RHS, RHSValue))
4384 return false;
4385 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx),
4386 RHSValue))
4387 return false;
4388 This->moveInto(Result);
4389 return true;
4390 } else if (MD && isLambdaCallOperator(MD)) {
4391 // We're in a lambda; determine the lambda capture field maps unless we're
4392 // just constexpr checking a lambda's call operator. constexpr checking is
4393 // done before the captures have been added to the closure object (unless
4394 // we're inferring constexpr-ness), so we don't have access to them in this
4395 // case. But since we don't need the captures to constexpr check, we can
4396 // just ignore them.
4397 if (!Info.checkingPotentialConstantExpression())
4398 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
4399 Frame.LambdaThisCaptureField);
4400 }
4401
4402 StmtResult Ret = {Result, ResultSlot};
4403 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
4404 if (ESR == ESR_Succeeded) {
4405 if (Callee->getReturnType()->isVoidType())
4406 return true;
4407 Info.FFDiag(Callee->getLocEnd(), diag::note_constexpr_no_return);
4408 }
4409 return ESR == ESR_Returned;
4410}
4411
4412/// Evaluate a constructor call.
4413static bool HandleConstructorCall(const Expr *E, const LValue &This,
4414 APValue *ArgValues,
4415 const CXXConstructorDecl *Definition,
4416 EvalInfo &Info, APValue &Result) {
4417 SourceLocation CallLoc = E->getExprLoc();
4418 if (!Info.CheckCallLimit(CallLoc))
4419 return false;
4420
4421 const CXXRecordDecl *RD = Definition->getParent();
4422 if (RD->getNumVBases()) {
4423 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
4424 return false;
4425 }
4426
4427 EvalInfo::EvaluatingConstructorRAII EvalObj(
4428 Info, {This.getLValueBase(),
4429 {This.getLValueCallIndex(), This.getLValueVersion()}});
4430 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
4431
4432 // FIXME: Creating an APValue just to hold a nonexistent return value is
4433 // wasteful.
4434 APValue RetVal;
4435 StmtResult Ret = {RetVal, nullptr};
4436
4437 // If it's a delegating constructor, delegate.
4438 if (Definition->isDelegatingConstructor()) {
4439 CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
4440 {
4441 FullExpressionRAII InitScope(Info);
4442 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
4443 return false;
4444 }
4445 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4446 }
4447
4448 // For a trivial copy or move constructor, perform an APValue copy. This is
4449 // essential for unions (or classes with anonymous union members), where the
4450 // operations performed by the constructor cannot be represented by
4451 // ctor-initializers.
4452 //
4453 // Skip this for empty non-union classes; we should not perform an
4454 // lvalue-to-rvalue conversion on them because their copy constructor does not
4455 // actually read them.
4456 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
4457 (Definition->getParent()->isUnion() ||
4458 (Definition->isTrivial() && hasFields(Definition->getParent())))) {
4459 LValue RHS;
4460 RHS.setFrom(Info.Ctx, ArgValues[0]);
4461 return handleLValueToRValueConversion(
4462 Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(),
4463 RHS, Result);
4464 }
4465
4466 // Reserve space for the struct members.
4467 if (!RD->isUnion() && Result.isUninit())
4468 Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4469 std::distance(RD->field_begin(), RD->field_end()));
4470
4471 if (RD->isInvalidDecl()) return false;
4472 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
4473
4474 // A scope for temporaries lifetime-extended by reference members.
4475 BlockScopeRAII LifetimeExtendedScope(Info);
4476
4477 bool Success = true;
4478 unsigned BasesSeen = 0;
4479#ifndef NDEBUG
4480 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
4481#endif
4482 for (const auto *I : Definition->inits()) {
4483 LValue Subobject = This;
4484 LValue SubobjectParent = This;
4485 APValue *Value = &Result;
4486
4487 // Determine the subobject to initialize.
4488 FieldDecl *FD = nullptr;
4489 if (I->isBaseInitializer()) {
4490 QualType BaseType(I->getBaseClass(), 0);
4491#ifndef NDEBUG
4492 // Non-virtual base classes are initialized in the order in the class
4493 // definition. We have already checked for virtual base classes.
4494 assert(!BaseIt->isVirtual() && "virtual base for literal type")(static_cast <bool> (!BaseIt->isVirtual() &&
"virtual base for literal type") ? void (0) : __assert_fail (
"!BaseIt->isVirtual() && \"virtual base for literal type\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4494, __extension__ __PRETTY_FUNCTION__))
;
4495 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&(static_cast <bool> (Info.Ctx.hasSameType(BaseIt->getType
(), BaseType) && "base class initializers not in expected order"
) ? void (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4496, __extension__ __PRETTY_FUNCTION__))
4496 "base class initializers not in expected order")(static_cast <bool> (Info.Ctx.hasSameType(BaseIt->getType
(), BaseType) && "base class initializers not in expected order"
) ? void (0) : __assert_fail ("Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && \"base class initializers not in expected order\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4496, __extension__ __PRETTY_FUNCTION__))
;
4497 ++BaseIt;
4498#endif
4499 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
4500 BaseType->getAsCXXRecordDecl(), &Layout))
4501 return false;
4502 Value = &Result.getStructBase(BasesSeen++);
4503 } else if ((FD = I->getMember())) {
4504 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
4505 return false;
4506 if (RD->isUnion()) {
4507 Result = APValue(FD);
4508 Value = &Result.getUnionValue();
4509 } else {
4510 Value = &Result.getStructField(FD->getFieldIndex());
4511 }
4512 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
4513 // Walk the indirect field decl's chain to find the object to initialize,
4514 // and make sure we've initialized every step along it.
4515 auto IndirectFieldChain = IFD->chain();
4516 for (auto *C : IndirectFieldChain) {
4517 FD = cast<FieldDecl>(C);
4518 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
4519 // Switch the union field if it differs. This happens if we had
4520 // preceding zero-initialization, and we're now initializing a union
4521 // subobject other than the first.
4522 // FIXME: In this case, the values of the other subobjects are
4523 // specified, since zero-initialization sets all padding bits to zero.
4524 if (Value->isUninit() ||
4525 (Value->isUnion() && Value->getUnionField() != FD)) {
4526 if (CD->isUnion())
4527 *Value = APValue(FD);
4528 else
4529 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(),
4530 std::distance(CD->field_begin(), CD->field_end()));
4531 }
4532 // Store Subobject as its parent before updating it for the last element
4533 // in the chain.
4534 if (C == IndirectFieldChain.back())
4535 SubobjectParent = Subobject;
4536 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
4537 return false;
4538 if (CD->isUnion())
4539 Value = &Value->getUnionValue();
4540 else
4541 Value = &Value->getStructField(FD->getFieldIndex());
4542 }
4543 } else {
4544 llvm_unreachable("unknown base initializer kind")::llvm::llvm_unreachable_internal("unknown base initializer kind"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4544)
;
4545 }
4546
4547 // Need to override This for implicit field initializers as in this case
4548 // This refers to innermost anonymous struct/union containing initializer,
4549 // not to currently constructed class.
4550 const Expr *Init = I->getInit();
4551 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
4552 isa<CXXDefaultInitExpr>(Init));
4553 FullExpressionRAII InitScope(Info);
4554 if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
4555 (FD && FD->isBitField() &&
4556 !truncateBitfieldValue(Info, Init, *Value, FD))) {
4557 // If we're checking for a potential constant expression, evaluate all
4558 // initializers even if some of them fail.
4559 if (!Info.noteFailure())
4560 return false;
4561 Success = false;
4562 }
4563 }
4564
4565 return Success &&
4566 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4567}
4568
4569static bool HandleConstructorCall(const Expr *E, const LValue &This,
4570 ArrayRef<const Expr*> Args,
4571 const CXXConstructorDecl *Definition,
4572 EvalInfo &Info, APValue &Result) {
4573 ArgVector ArgValues(Args.size());
4574 if (!EvaluateArgs(Args, ArgValues, Info))
4575 return false;
4576
4577 return HandleConstructorCall(E, This, ArgValues.data(), Definition,
4578 Info, Result);
4579}
4580
4581//===----------------------------------------------------------------------===//
4582// Generic Evaluation
4583//===----------------------------------------------------------------------===//
4584namespace {
4585
4586template <class Derived>
4587class ExprEvaluatorBase
4588 : public ConstStmtVisitor<Derived, bool> {
4589private:
4590 Derived &getDerived() { return static_cast<Derived&>(*this); }
4591 bool DerivedSuccess(const APValue &V, const Expr *E) {
4592 return getDerived().Success(V, E);
4593 }
4594 bool DerivedZeroInitialization(const Expr *E) {
4595 return getDerived().ZeroInitialization(E);
4596 }
4597
4598 // Check whether a conditional operator with a non-constant condition is a
4599 // potential constant expression. If neither arm is a potential constant
4600 // expression, then the conditional operator is not either.
4601 template<typename ConditionalOperator>
4602 void CheckPotentialConstantConditional(const ConditionalOperator *E) {
4603 assert(Info.checkingPotentialConstantExpression())(static_cast <bool> (Info.checkingPotentialConstantExpression
()) ? void (0) : __assert_fail ("Info.checkingPotentialConstantExpression()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4603, __extension__ __PRETTY_FUNCTION__))
;
4604
4605 // Speculatively evaluate both arms.
4606 SmallVector<PartialDiagnosticAt, 8> Diag;
4607 {
4608 SpeculativeEvaluationRAII Speculate(Info, &Diag);
4609 StmtVisitorTy::Visit(E->getFalseExpr());
4610 if (Diag.empty())
4611 return;
4612 }
4613
4614 {
4615 SpeculativeEvaluationRAII Speculate(Info, &Diag);
4616 Diag.clear();
4617 StmtVisitorTy::Visit(E->getTrueExpr());
4618 if (Diag.empty())
4619 return;
4620 }
4621
4622 Error(E, diag::note_constexpr_conditional_never_const);
4623 }
4624
4625
4626 template<typename ConditionalOperator>
4627 bool HandleConditionalOperator(const ConditionalOperator *E) {
4628 bool BoolResult;
4629 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
4630 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
4631 CheckPotentialConstantConditional(E);
4632 return false;
4633 }
4634 if (Info.noteFailure()) {
4635 StmtVisitorTy::Visit(E->getTrueExpr());
4636 StmtVisitorTy::Visit(E->getFalseExpr());
4637 }
4638 return false;
4639 }
4640
4641 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
4642 return StmtVisitorTy::Visit(EvalExpr);
4643 }
4644
4645protected:
4646 EvalInfo &Info;
4647 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
4648 typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
4649
4650 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
4651 return Info.CCEDiag(E, D);
4652 }
4653
4654 bool ZeroInitialization(const Expr *E) { return Error(E); }
4655
4656public:
4657 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
4658
4659 EvalInfo &getEvalInfo() { return Info; }
4660
4661 /// Report an evaluation error. This should only be called when an error is
4662 /// first discovered. When propagating an error, just return false.
4663 bool Error(const Expr *E, diag::kind D) {
4664 Info.FFDiag(E, D);
4665 return false;
4666 }
4667 bool Error(const Expr *E) {
4668 return Error(E, diag::note_invalid_subexpr_in_const_expr);
4669 }
4670
4671 bool VisitStmt(const Stmt *) {
4672 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4672)
;
4673 }
4674 bool VisitExpr(const Expr *E) {
4675 return Error(E);
4676 }
4677
4678 bool VisitParenExpr(const ParenExpr *E)
4679 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4680 bool VisitUnaryExtension(const UnaryOperator *E)
4681 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4682 bool VisitUnaryPlus(const UnaryOperator *E)
4683 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4684 bool VisitChooseExpr(const ChooseExpr *E)
4685 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
4686 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
4687 { return StmtVisitorTy::Visit(E->getResultExpr()); }
4688 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
4689 { return StmtVisitorTy::Visit(E->getReplacement()); }
4690 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
4691 TempVersionRAII RAII(*Info.CurrentCall);
4692 return StmtVisitorTy::Visit(E->getExpr());
4693 }
4694 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
4695 TempVersionRAII RAII(*Info.CurrentCall);
4696 // The initializer may not have been parsed yet, or might be erroneous.
4697 if (!E->getExpr())
4698 return Error(E);
4699 return StmtVisitorTy::Visit(E->getExpr());
4700 }
4701 // We cannot create any objects for which cleanups are required, so there is
4702 // nothing to do here; all cleanups must come from unevaluated subexpressions.
4703 bool VisitExprWithCleanups(const ExprWithCleanups *E)
4704 { return StmtVisitorTy::Visit(E->getSubExpr()); }
4705
4706 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
4707 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
4708 return static_cast<Derived*>(this)->VisitCastExpr(E);
4709 }
4710 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
4711 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
4712 return static_cast<Derived*>(this)->VisitCastExpr(E);
4713 }
4714
4715 bool VisitBinaryOperator(const BinaryOperator *E) {
4716 switch (E->getOpcode()) {
4717 default:
4718 return Error(E);
4719
4720 case BO_Comma:
4721 VisitIgnoredValue(E->getLHS());
4722 return StmtVisitorTy::Visit(E->getRHS());
4723
4724 case BO_PtrMemD:
4725 case BO_PtrMemI: {
4726 LValue Obj;
4727 if (!HandleMemberPointerAccess(Info, E, Obj))
4728 return false;
4729 APValue Result;
4730 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
4731 return false;
4732 return DerivedSuccess(Result, E);
4733 }
4734 }
4735 }
4736
4737 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
4738 // Evaluate and cache the common expression. We treat it as a temporary,
4739 // even though it's not quite the same thing.
4740 if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false),
4741 Info, E->getCommon()))
4742 return false;
4743
4744 return HandleConditionalOperator(E);
4745 }
4746
4747 bool VisitConditionalOperator(const ConditionalOperator *E) {
4748 bool IsBcpCall = false;
4749 // If the condition (ignoring parens) is a __builtin_constant_p call,
4750 // the result is a constant expression if it can be folded without
4751 // side-effects. This is an important GNU extension. See GCC PR38377
4752 // for discussion.
4753 if (const CallExpr *CallCE =
4754 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
4755 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
4756 IsBcpCall = true;
4757
4758 // Always assume __builtin_constant_p(...) ? ... : ... is a potential
4759 // constant expression; we can't check whether it's potentially foldable.
4760 if (Info.checkingPotentialConstantExpression() && IsBcpCall)
4761 return false;
4762
4763 FoldConstant Fold(Info, IsBcpCall);
4764 if (!HandleConditionalOperator(E)) {
4765 Fold.keepDiagnostics();
4766 return false;
4767 }
4768
4769 return true;
4770 }
4771
4772 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
4773 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
4774 return DerivedSuccess(*Value, E);
4775
4776 const Expr *Source = E->getSourceExpr();
4777 if (!Source)
4778 return Error(E);
4779 if (Source == E) { // sanity checking.
4780 assert(0 && "OpaqueValueExpr recursively refers to itself")(static_cast <bool> (0 && "OpaqueValueExpr recursively refers to itself"
) ? void (0) : __assert_fail ("0 && \"OpaqueValueExpr recursively refers to itself\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4780, __extension__ __PRETTY_FUNCTION__))
;
4781 return Error(E);
4782 }
4783 return StmtVisitorTy::Visit(Source);
4784 }
4785
4786 bool VisitCallExpr(const CallExpr *E) {
4787 APValue Result;
4788 if (!handleCallExpr(E, Result, nullptr))
4789 return false;
4790 return DerivedSuccess(Result, E);
4791 }
4792
4793 bool handleCallExpr(const CallExpr *E, APValue &Result,
4794 const LValue *ResultSlot) {
4795 const Expr *Callee = E->getCallee()->IgnoreParens();
4796 QualType CalleeType = Callee->getType();
4797
4798 const FunctionDecl *FD = nullptr;
4799 LValue *This = nullptr, ThisVal;
4800 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
4801 bool HasQualifier = false;
4802
4803 // Extract function decl and 'this' pointer from the callee.
4804 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
4805 const ValueDecl *Member = nullptr;
4806 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
4807 // Explicit bound member calls, such as x.f() or p->g();
4808 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
4809 return false;
4810 Member = ME->getMemberDecl();
4811 This = &ThisVal;
4812 HasQualifier = ME->hasQualifier();
4813 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
4814 // Indirect bound member calls ('.*' or '->*').
4815 Member = HandleMemberPointerAccess(Info, BE, ThisVal, false);
4816 if (!Member) return false;
4817 This = &ThisVal;
4818 } else
4819 return Error(Callee);
4820
4821 FD = dyn_cast<FunctionDecl>(Member);
4822 if (!FD)
4823 return Error(Callee);
4824 } else if (CalleeType->isFunctionPointerType()) {
4825 LValue Call;
4826 if (!EvaluatePointer(Callee, Call, Info))
4827 return false;
4828
4829 if (!Call.getLValueOffset().isZero())
4830 return Error(Callee);
4831 FD = dyn_cast_or_null<FunctionDecl>(
4832 Call.getLValueBase().dyn_cast<const ValueDecl*>());
4833 if (!FD)
4834 return Error(Callee);
4835 // Don't call function pointers which have been cast to some other type.
4836 // Per DR (no number yet), the caller and callee can differ in noexcept.
4837 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
4838 CalleeType->getPointeeType(), FD->getType())) {
4839 return Error(E);
4840 }
4841
4842 // Overloaded operator calls to member functions are represented as normal
4843 // calls with '*this' as the first argument.
4844 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
4845 if (MD && !MD->isStatic()) {
4846 // FIXME: When selecting an implicit conversion for an overloaded
4847 // operator delete, we sometimes try to evaluate calls to conversion
4848 // operators without a 'this' parameter!
4849 if (Args.empty())
4850 return Error(E);
4851
4852 if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
4853 return false;
4854 This = &ThisVal;
4855 Args = Args.slice(1);
4856 } else if (MD && MD->isLambdaStaticInvoker()) {
4857 // Map the static invoker for the lambda back to the call operator.
4858 // Conveniently, we don't have to slice out the 'this' argument (as is
4859 // being done for the non-static case), since a static member function
4860 // doesn't have an implicit argument passed in.
4861 const CXXRecordDecl *ClosureClass = MD->getParent();
4862 assert((static_cast <bool> (ClosureClass->captures_begin() ==
ClosureClass->captures_end() && "Number of captures must be zero for conversion to function-ptr"
) ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4864, __extension__ __PRETTY_FUNCTION__))
4863 ClosureClass->captures_begin() == ClosureClass->captures_end() &&(static_cast <bool> (ClosureClass->captures_begin() ==
ClosureClass->captures_end() && "Number of captures must be zero for conversion to function-ptr"
) ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4864, __extension__ __PRETTY_FUNCTION__))
4864 "Number of captures must be zero for conversion to function-ptr")(static_cast <bool> (ClosureClass->captures_begin() ==
ClosureClass->captures_end() && "Number of captures must be zero for conversion to function-ptr"
) ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4864, __extension__ __PRETTY_FUNCTION__))
;
4865
4866 const CXXMethodDecl *LambdaCallOp =
4867 ClosureClass->getLambdaCallOperator();
4868
4869 // Set 'FD', the function that will be called below, to the call
4870 // operator. If the closure object represents a generic lambda, find
4871 // the corresponding specialization of the call operator.
4872
4873 if (ClosureClass->isGenericLambda()) {
4874 assert(MD->isFunctionTemplateSpecialization() &&(static_cast <bool> (MD->isFunctionTemplateSpecialization
() && "A generic lambda's static-invoker function must be a "
"template specialization") ? void (0) : __assert_fail ("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4876, __extension__ __PRETTY_FUNCTION__))
4875 "A generic lambda's static-invoker function must be a "(static_cast <bool> (MD->isFunctionTemplateSpecialization
() && "A generic lambda's static-invoker function must be a "
"template specialization") ? void (0) : __assert_fail ("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4876, __extension__ __PRETTY_FUNCTION__))
4876 "template specialization")(static_cast <bool> (MD->isFunctionTemplateSpecialization
() && "A generic lambda's static-invoker function must be a "
"template specialization") ? void (0) : __assert_fail ("MD->isFunctionTemplateSpecialization() && \"A generic lambda's static-invoker function must be a \" \"template specialization\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4876, __extension__ __PRETTY_FUNCTION__))
;
4877 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
4878 FunctionTemplateDecl *CallOpTemplate =
4879 LambdaCallOp->getDescribedFunctionTemplate();
4880 void *InsertPos = nullptr;
4881 FunctionDecl *CorrespondingCallOpSpecialization =
4882 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
4883 assert(CorrespondingCallOpSpecialization &&(static_cast <bool> (CorrespondingCallOpSpecialization &&
"We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4885, __extension__ __PRETTY_FUNCTION__))
4884 "We must always have a function call operator specialization "(static_cast <bool> (CorrespondingCallOpSpecialization &&
"We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4885, __extension__ __PRETTY_FUNCTION__))
4885 "that corresponds to our static invoker specialization")(static_cast <bool> (CorrespondingCallOpSpecialization &&
"We must always have a function call operator specialization "
"that corresponds to our static invoker specialization") ? 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-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4885, __extension__ __PRETTY_FUNCTION__))
;
4886 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
4887 } else
4888 FD = LambdaCallOp;
4889 }
4890
4891
4892 } else
4893 return Error(E);
4894
4895 if (This && !This->checkSubobject(Info, E, CSK_This))
4896 return false;
4897
4898 // DR1358 allows virtual constexpr functions in some cases. Don't allow
4899 // calls to such functions in constant expressions.
4900 if (This && !HasQualifier &&
4901 isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual())
4902 return Error(E, diag::note_constexpr_virtual_call);
4903
4904 const FunctionDecl *Definition = nullptr;
4905 Stmt *Body = FD->getBody(Definition);
4906
4907 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
4908 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info,
4909 Result, ResultSlot))
4910 return false;
4911
4912 return true;
4913 }
4914
4915 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
4916 return StmtVisitorTy::Visit(E->getInitializer());
4917 }
4918 bool VisitInitListExpr(const InitListExpr *E) {
4919 if (E->getNumInits() == 0)
4920 return DerivedZeroInitialization(E);
4921 if (E->getNumInits() == 1)
4922 return StmtVisitorTy::Visit(E->getInit(0));
4923 return Error(E);
4924 }
4925 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
4926 return DerivedZeroInitialization(E);
4927 }
4928 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
4929 return DerivedZeroInitialization(E);
4930 }
4931 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
4932 return DerivedZeroInitialization(E);
4933 }
4934
4935 /// A member expression where the object is a prvalue is itself a prvalue.
4936 bool VisitMemberExpr(const MemberExpr *E) {
4937 assert(!E->isArrow() && "missing call to bound member function?")(static_cast <bool> (!E->isArrow() && "missing call to bound member function?"
) ? void (0) : __assert_fail ("!E->isArrow() && \"missing call to bound member function?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4937, __extension__ __PRETTY_FUNCTION__))
;
4938
4939 APValue Val;
4940 if (!Evaluate(Val, Info, E->getBase()))
4941 return false;
4942
4943 QualType BaseTy = E->getBase()->getType();
4944
4945 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
4946 if (!FD) return Error(E);
4947 assert(!FD->getType()->isReferenceType() && "prvalue reference?")(static_cast <bool> (!FD->getType()->isReferenceType
() && "prvalue reference?") ? void (0) : __assert_fail
("!FD->getType()->isReferenceType() && \"prvalue reference?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4947, __extension__ __PRETTY_FUNCTION__))
;
4948 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==(static_cast <bool> (BaseTy->castAs<RecordType>
()->getDecl()->getCanonicalDecl() == FD->getParent()
->getCanonicalDecl() && "record / field mismatch")
? void (0) : __assert_fail ("BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4949, __extension__ __PRETTY_FUNCTION__))
4949 FD->getParent()->getCanonicalDecl() && "record / field mismatch")(static_cast <bool> (BaseTy->castAs<RecordType>
()->getDecl()->getCanonicalDecl() == FD->getParent()
->getCanonicalDecl() && "record / field mismatch")
? void (0) : __assert_fail ("BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 4949, __extension__ __PRETTY_FUNCTION__))
;
4950
4951 CompleteObject Obj(&Val, BaseTy, true);
4952 SubobjectDesignator Designator(BaseTy);
4953 Designator.addDeclUnchecked(FD);
4954
4955 APValue Result;
4956 return extractSubobject(Info, E, Obj, Designator, Result) &&
4957 DerivedSuccess(Result, E);
4958 }
4959
4960 bool VisitCastExpr(const CastExpr *E) {
4961 switch (E->getCastKind()) {
4962 default:
4963 break;
4964
4965 case CK_AtomicToNonAtomic: {
4966 APValue AtomicVal;
4967 // This does not need to be done in place even for class/array types:
4968 // atomic-to-non-atomic conversion implies copying the object
4969 // representation.
4970 if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
4971 return false;
4972 return DerivedSuccess(AtomicVal, E);
4973 }
4974
4975 case CK_NoOp:
4976 case CK_UserDefinedConversion:
4977 return StmtVisitorTy::Visit(E->getSubExpr());
4978
4979 case CK_LValueToRValue: {
4980 LValue LVal;
4981 if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
4982 return false;
4983 APValue RVal;
4984 // Note, we use the subexpression's type in order to retain cv-qualifiers.
4985 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
4986 LVal, RVal))
4987 return false;
4988 return DerivedSuccess(RVal, E);
4989 }
4990 }
4991
4992 return Error(E);
4993 }
4994
4995 bool VisitUnaryPostInc(const UnaryOperator *UO) {
4996 return VisitUnaryPostIncDec(UO);
4997 }
4998 bool VisitUnaryPostDec(const UnaryOperator *UO) {
4999 return VisitUnaryPostIncDec(UO);
5000 }
5001 bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
5002 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5003 return Error(UO);
5004
5005 LValue LVal;
5006 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
5007 return false;
5008 APValue RVal;
5009 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
5010 UO->isIncrementOp(), &RVal))
5011 return false;
5012 return DerivedSuccess(RVal, UO);
5013 }
5014
5015 bool VisitStmtExpr(const StmtExpr *E) {
5016 // We will have checked the full-expressions inside the statement expression
5017 // when they were completed, and don't need to check them again now.
5018 if (Info.checkingForOverflow())
5019 return Error(E);
5020
5021 BlockScopeRAII Scope(Info);
5022 const CompoundStmt *CS = E->getSubStmt();
5023 if (CS->body_empty())
5024 return true;
5025
5026 for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
5027 BE = CS->body_end();
5028 /**/; ++BI) {
5029 if (BI + 1 == BE) {
5030 const Expr *FinalExpr = dyn_cast<Expr>(*BI);
5031 if (!FinalExpr) {
5032 Info.FFDiag((*BI)->getLocStart(),
5033 diag::note_constexpr_stmt_expr_unsupported);
5034 return false;
5035 }
5036 return this->Visit(FinalExpr);
5037 }
5038
5039 APValue ReturnValue;
5040 StmtResult Result = { ReturnValue, nullptr };
5041 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
5042 if (ESR != ESR_Succeeded) {
5043 // FIXME: If the statement-expression terminated due to 'return',
5044 // 'break', or 'continue', it would be nice to propagate that to
5045 // the outer statement evaluation rather than bailing out.
5046 if (ESR != ESR_Failed)
5047 Info.FFDiag((*BI)->getLocStart(),
5048 diag::note_constexpr_stmt_expr_unsupported);
5049 return false;
5050 }
5051 }
5052
5053 llvm_unreachable("Return from function from the loop above.")::llvm::llvm_unreachable_internal("Return from function from the loop above."
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5053)
;
5054 }
5055
5056 /// Visit a value which is evaluated, but whose value is ignored.
5057 void VisitIgnoredValue(const Expr *E) {
5058 EvaluateIgnoredValue(Info, E);
5059 }
5060
5061 /// Potentially visit a MemberExpr's base expression.
5062 void VisitIgnoredBaseExpression(const Expr *E) {
5063 // While MSVC doesn't evaluate the base expression, it does diagnose the
5064 // presence of side-effecting behavior.
5065 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
5066 return;
5067 VisitIgnoredValue(E);
5068 }
5069};
5070
5071} // namespace
5072
5073//===----------------------------------------------------------------------===//
5074// Common base class for lvalue and temporary evaluation.
5075//===----------------------------------------------------------------------===//
5076namespace {
5077template<class Derived>
5078class LValueExprEvaluatorBase
5079 : public ExprEvaluatorBase<Derived> {
5080protected:
5081 LValue &Result;
5082 bool InvalidBaseOK;
5083 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
5084 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
5085
5086 bool Success(APValue::LValueBase B) {
5087 Result.set(B);
5088 return true;
5089 }
5090
5091 bool evaluatePointer(const Expr *E, LValue &Result) {
5092 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
5093 }
5094
5095public:
5096 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
5097 : ExprEvaluatorBaseTy(Info), Result(Result),
5098 InvalidBaseOK(InvalidBaseOK) {}
5099
5100 bool Success(const APValue &V, const Expr *E) {
5101 Result.setFrom(this->Info.Ctx, V);
5102 return true;
5103 }
5104
5105 bool VisitMemberExpr(const MemberExpr *E) {
5106 // Handle non-static data members.
5107 QualType BaseTy;
5108 bool EvalOK;
5109 if (E->isArrow()) {
5110 EvalOK = evaluatePointer(E->getBase(), Result);
5111 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
5112 } else if (E->getBase()->isRValue()) {
5113 assert(E->getBase()->getType()->isRecordType())(static_cast <bool> (E->getBase()->getType()->
isRecordType()) ? void (0) : __assert_fail ("E->getBase()->getType()->isRecordType()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5113, __extension__ __PRETTY_FUNCTION__))
;
5114 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
5115 BaseTy = E->getBase()->getType();
5116 } else {
5117 EvalOK = this->Visit(E->getBase());
5118 BaseTy = E->getBase()->getType();
5119 }
5120 if (!EvalOK) {
5121 if (!InvalidBaseOK)
5122 return false;
5123 Result.setInvalid(E);
5124 return true;
5125 }
5126
5127 const ValueDecl *MD = E->getMemberDecl();
5128 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
5129 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() ==(static_cast <bool> (BaseTy->getAs<RecordType>
()->getDecl()->getCanonicalDecl() == FD->getParent()
->getCanonicalDecl() && "record / field mismatch")
? void (0) : __assert_fail ("BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5130, __extension__ __PRETTY_FUNCTION__))
5130 FD->getParent()->getCanonicalDecl() && "record / field mismatch")(static_cast <bool> (BaseTy->getAs<RecordType>
()->getDecl()->getCanonicalDecl() == FD->getParent()
->getCanonicalDecl() && "record / field mismatch")
? void (0) : __assert_fail ("BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == FD->getParent()->getCanonicalDecl() && \"record / field mismatch\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5130, __extension__ __PRETTY_FUNCTION__))
;
5131 (void)BaseTy;
5132 if (!HandleLValueMember(this->Info, E, Result, FD))
5133 return false;
5134 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
5135 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
5136 return false;
5137 } else
5138 return this->Error(E);
5139
5140 if (MD->getType()->isReferenceType()) {
5141 APValue RefValue;
5142 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
5143 RefValue))
5144 return false;
5145 return Success(RefValue, E);
5146 }
5147 return true;
5148 }
5149
5150 bool VisitBinaryOperator(const BinaryOperator *E) {
5151 switch (E->getOpcode()) {
5152 default:
5153 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5154
5155 case BO_PtrMemD:
5156 case BO_PtrMemI:
5157 return HandleMemberPointerAccess(this->Info, E, Result);
5158 }
5159 }
5160
5161 bool VisitCastExpr(const CastExpr *E) {
5162 switch (E->getCastKind()) {
5163 default:
5164 return ExprEvaluatorBaseTy::VisitCastExpr(E);
5165
5166 case CK_DerivedToBase:
5167 case CK_UncheckedDerivedToBase:
5168 if (!this->Visit(E->getSubExpr()))
5169 return false;
5170
5171 // Now figure out the necessary offset to add to the base LV to get from
5172 // the derived class to the base class.
5173 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
5174 Result);
5175 }
5176 }
5177};
5178}
5179
5180//===----------------------------------------------------------------------===//
5181// LValue Evaluation
5182//
5183// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
5184// function designators (in C), decl references to void objects (in C), and
5185// temporaries (if building with -Wno-address-of-temporary).
5186//
5187// LValue evaluation produces values comprising a base expression of one of the
5188// following types:
5189// - Declarations
5190// * VarDecl
5191// * FunctionDecl
5192// - Literals
5193// * CompoundLiteralExpr in C (and in global scope in C++)
5194// * StringLiteral
5195// * CXXTypeidExpr
5196// * PredefinedExpr
5197// * ObjCStringLiteralExpr
5198// * ObjCEncodeExpr
5199// * AddrLabelExpr
5200// * BlockExpr
5201// * CallExpr for a MakeStringConstant builtin
5202// - Locals and temporaries
5203// * MaterializeTemporaryExpr
5204// * Any Expr, with a CallIndex indicating the function in which the temporary
5205// was evaluated, for cases where the MaterializeTemporaryExpr is missing
5206// from the AST (FIXME).
5207// * A MaterializeTemporaryExpr that has static storage duration, with no
5208// CallIndex, for a lifetime-extended temporary.
5209// plus an offset in bytes.
5210//===----------------------------------------------------------------------===//
5211namespace {
5212class LValueExprEvaluator
5213 : public LValueExprEvaluatorBase<LValueExprEvaluator> {
5214public:
5215 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
5216 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
5217
5218 bool VisitVarDecl(const Expr *E, const VarDecl *VD);
5219 bool VisitUnaryPreIncDec(const UnaryOperator *UO);
5220
5221 bool VisitDeclRefExpr(const DeclRefExpr *E);
5222 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
5223 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
5224 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
5225 bool VisitMemberExpr(const MemberExpr *E);
5226 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
5227 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
5228 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
5229 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
5230 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
5231 bool VisitUnaryDeref(const UnaryOperator *E);
5232 bool VisitUnaryReal(const UnaryOperator *E);
5233 bool VisitUnaryImag(const UnaryOperator *E);
5234 bool VisitUnaryPreInc(const UnaryOperator *UO) {
5235 return VisitUnaryPreIncDec(UO);
5236 }
5237 bool VisitUnaryPreDec(const UnaryOperator *UO) {
5238 return VisitUnaryPreIncDec(UO);
5239 }
5240 bool VisitBinAssign(const BinaryOperator *BO);
5241 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
5242
5243 bool VisitCastExpr(const CastExpr *E) {
5244 switch (E->getCastKind()) {
5245 default:
5246 return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
5247
5248 case CK_LValueBitCast:
5249 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5250 if (!Visit(E->getSubExpr()))
5251 return false;
5252 Result.Designator.setInvalid();
5253 return true;
5254
5255 case CK_BaseToDerived:
5256 if (!Visit(E->getSubExpr()))
5257 return false;
5258 return HandleBaseToDerivedCast(Info, E, Result);
5259 }
5260 }
5261};
5262} // end anonymous namespace
5263
5264/// Evaluate an expression as an lvalue. This can be legitimately called on
5265/// expressions which are not glvalues, in three cases:
5266/// * function designators in C, and
5267/// * "extern void" objects
5268/// * @selector() expressions in Objective-C
5269static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
5270 bool InvalidBaseOK) {
5271 assert(E->isGLValue() || E->getType()->isFunctionType() ||(static_cast <bool> (E->isGLValue() || E->getType
()->isFunctionType() || E->getType()->isVoidType() ||
isa<ObjCSelectorExpr>(E)) ? void (0) : __assert_fail (
"E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5272, __extension__ __PRETTY_FUNCTION__))
5272 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E))(static_cast <bool> (E->isGLValue() || E->getType
()->isFunctionType() || E->getType()->isVoidType() ||
isa<ObjCSelectorExpr>(E)) ? void (0) : __assert_fail (
"E->isGLValue() || E->getType()->isFunctionType() || E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5272, __extension__ __PRETTY_FUNCTION__))
;
5273 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5274}
5275
5276bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
5277 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl()))
5278 return Success(FD);
5279 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
5280 return VisitVarDecl(E, VD);
5281 if (const BindingDecl *BD = dyn_cast<BindingDecl>(E->getDecl()))
5282 return Visit(BD->getBinding());
5283 return Error(E);
5284}
5285
5286
5287bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
5288
5289 // If we are within a lambda's call operator, check whether the 'VD' referred
5290 // to within 'E' actually represents a lambda-capture that maps to a
5291 // data-member/field within the closure object, and if so, evaluate to the
5292 // field or what the field refers to.
5293 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
5294 isa<DeclRefExpr>(E) &&
5295 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
5296 // We don't always have a complete capture-map when checking or inferring if
5297 // the function call operator meets the requirements of a constexpr function
5298 // - but we don't need to evaluate the captures to determine constexprness
5299 // (dcl.constexpr C++17).
5300 if (Info.checkingPotentialConstantExpression())
5301 return false;
5302
5303 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
5304 // Start with 'Result' referring to the complete closure object...
5305 Result = *Info.CurrentCall->This;
5306 // ... then update it to refer to the field of the closure object
5307 // that represents the capture.
5308 if (!HandleLValueMember(Info, E, Result, FD))
5309 return false;
5310 // And if the field is of reference type, update 'Result' to refer to what
5311 // the field refers to.
5312 if (FD->getType()->isReferenceType()) {
5313 APValue RVal;
5314 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
5315 RVal))
5316 return false;
5317 Result.setFrom(Info.Ctx, RVal);
5318 }
5319 return true;
5320 }
5321 }
5322 CallStackFrame *Frame = nullptr;
5323 if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
5324 // Only if a local variable was declared in the function currently being
5325 // evaluated, do we expect to be able to find its value in the current
5326 // frame. (Otherwise it was likely declared in an enclosing context and
5327 // could either have a valid evaluatable value (for e.g. a constexpr
5328 // variable) or be ill-formed (and trigger an appropriate evaluation
5329 // diagnostic)).
5330 if (Info.CurrentCall->Callee &&
5331 Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
5332 Frame = Info.CurrentCall;
5333 }
5334 }
5335
5336 if (!VD->getType()->isReferenceType()) {
5337 if (Frame) {
5338 Result.set({VD, Frame->Index,
5339 Info.CurrentCall->getCurrentTemporaryVersion(VD)});
5340 return true;
5341 }
5342 return Success(VD);
5343 }
5344
5345 APValue *V;
5346 if (!evaluateVarDeclInit(Info, E, VD, Frame, V, nullptr))
5347 return false;
5348 if (V->isUninit()) {
5349 if (!Info.checkingPotentialConstantExpression())
5350 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
5351 return false;
5352 }
5353 return Success(*V, E);
5354}
5355
5356bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
5357 const MaterializeTemporaryExpr *E) {
5358 // Walk through the expression to find the materialized temporary itself.
5359 SmallVector<const Expr *, 2> CommaLHSs;
5360 SmallVector<SubobjectAdjustment, 2> Adjustments;
5361 const Expr *Inner = E->GetTemporaryExpr()->
5362 skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
5363
5364 // If we passed any comma operators, evaluate their LHSs.
5365 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
5366 if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
5367 return false;
5368
5369 // A materialized temporary with static storage duration can appear within the
5370 // result of a constant expression evaluation, so we need to preserve its
5371 // value for use outside this evaluation.
5372 APValue *Value;
5373 if (E->getStorageDuration() == SD_Static) {
5374 Value = Info.Ctx.getMaterializedTemporaryValue(E, true);
5375 *Value = APValue();
5376 Result.set(E);
5377 } else {
5378 Value = &createTemporary(E, E->getStorageDuration() == SD_Automatic, Result,
5379 *Info.CurrentCall);
5380 }
5381
5382 QualType Type = Inner->getType();
5383
5384 // Materialize the temporary itself.
5385 if (!EvaluateInPlace(*Value, Info, Result, Inner) ||
5386 (E->getStorageDuration() == SD_Static &&
5387 !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) {
5388 *Value = APValue();
5389 return false;
5390 }
5391
5392 // Adjust our lvalue to refer to the desired subobject.
5393 for (unsigned I = Adjustments.size(); I != 0; /**/) {
5394 --I;
5395 switch (Adjustments[I].Kind) {
5396 case SubobjectAdjustment::DerivedToBaseAdjustment:
5397 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
5398 Type, Result))
5399 return false;
5400 Type = Adjustments[I].DerivedToBase.BasePath->getType();
5401 break;
5402
5403 case SubobjectAdjustment::FieldAdjustment:
5404 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
5405 return false;
5406 Type = Adjustments[I].Field->getType();
5407 break;
5408
5409 case SubobjectAdjustment::MemberPointerAdjustment:
5410 if (!HandleMemberPointerAccess(this->Info, Type, Result,
5411 Adjustments[I].Ptr.RHS))
5412 return false;
5413 Type = Adjustments[I].Ptr.MPT->getPointeeType();
5414 break;
5415 }
5416 }
5417
5418 return true;
5419}
5420
5421bool
5422LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
5423 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&(static_cast <bool> ((!Info.getLangOpts().CPlusPlus || E
->isFileScope()) && "lvalue compound literal in c++?"
) ? void (0) : __assert_fail ("(!Info.getLangOpts().CPlusPlus || E->isFileScope()) && \"lvalue compound literal in c++?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5424, __extension__ __PRETTY_FUNCTION__))
5424 "lvalue compound literal in c++?")(static_cast <bool> ((!Info.getLangOpts().CPlusPlus || E
->isFileScope()) && "lvalue compound literal in c++?"
) ? void (0) : __assert_fail ("(!Info.getLangOpts().CPlusPlus || E->isFileScope()) && \"lvalue compound literal in c++?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5424, __extension__ __PRETTY_FUNCTION__))
;
5425 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
5426 // only see this when folding in C, so there's no standard to follow here.
5427 return Success(E);
5428}
5429
5430bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
5431 if (!E->isPotentiallyEvaluated())
5432 return Success(E);
5433
5434 Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic)
5435 << E->getExprOperand()->getType()
5436 << E->getExprOperand()->getSourceRange();
5437 return false;
5438}
5439
5440bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
5441 return Success(E);
5442}
5443
5444bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
5445 // Handle static data members.
5446 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
5447 VisitIgnoredBaseExpression(E->getBase());
5448 return VisitVarDecl(E, VD);
5449 }
5450
5451 // Handle static member functions.
5452 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
5453 if (MD->isStatic()) {
5454 VisitIgnoredBaseExpression(E->getBase());
5455 return Success(MD);
5456 }
5457 }
5458
5459 // Handle non-static data members.
5460 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
5461}
5462
5463bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
5464 // FIXME: Deal with vectors as array subscript bases.
5465 if (E->getBase()->getType()->isVectorType())
5466 return Error(E);
5467
5468 bool Success = true;
5469 if (!evaluatePointer(E->getBase(), Result)) {
5470 if (!Info.noteFailure())
5471 return false;
5472 Success = false;
5473 }
5474
5475 APSInt Index;
5476 if (!EvaluateInteger(E->getIdx(), Index, Info))
5477 return false;
5478
5479 return Success &&
5480 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
5481}
5482
5483bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
5484 return evaluatePointer(E->getSubExpr(), Result);
5485}
5486
5487bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
5488 if (!Visit(E->getSubExpr()))
5489 return false;
5490 // __real is a no-op on scalar lvalues.
5491 if (E->getSubExpr()->getType()->isAnyComplexType())
5492 HandleLValueComplexElement(Info, E, Result, E->getType(), false);
5493 return true;
5494}
5495
5496bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
5497 assert(E->getSubExpr()->getType()->isAnyComplexType() &&(static_cast <bool> (E->getSubExpr()->getType()->
isAnyComplexType() && "lvalue __imag__ on scalar?") ?
void (0) : __assert_fail ("E->getSubExpr()->getType()->isAnyComplexType() && \"lvalue __imag__ on scalar?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5498, __extension__ __PRETTY_FUNCTION__))
5498 "lvalue __imag__ on scalar?")(static_cast <bool> (E->getSubExpr()->getType()->
isAnyComplexType() && "lvalue __imag__ on scalar?") ?
void (0) : __assert_fail ("E->getSubExpr()->getType()->isAnyComplexType() && \"lvalue __imag__ on scalar?\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5498, __extension__ __PRETTY_FUNCTION__))
;
5499 if (!Visit(E->getSubExpr()))
5500 return false;
5501 HandleLValueComplexElement(Info, E, Result, E->getType(), true);
5502 return true;
5503}
5504
5505bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
5506 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5507 return Error(UO);
5508
5509 if (!this->Visit(UO->getSubExpr()))
5510 return false;
5511
5512 return handleIncDec(
5513 this->Info, UO, Result, UO->getSubExpr()->getType(),
5514 UO->isIncrementOp(), nullptr);
5515}
5516
5517bool LValueExprEvaluator::VisitCompoundAssignOperator(
5518 const CompoundAssignOperator *CAO) {
5519 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5520 return Error(CAO);
5521
5522 APValue RHS;
5523
5524 // The overall lvalue result is the result of evaluating the LHS.
5525 if (!this->Visit(CAO->getLHS())) {
5526 if (Info.noteFailure())
5527 Evaluate(RHS, this->Info, CAO->getRHS());
5528 return false;
5529 }
5530
5531 if (!Evaluate(RHS, this->Info, CAO->getRHS()))
5532 return false;
5533
5534 return handleCompoundAssignment(
5535 this->Info, CAO,
5536 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
5537 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
5538}
5539
5540bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
5541 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5542 return Error(E);
5543
5544 APValue NewVal;
5545
5546 if (!this->Visit(E->getLHS())) {
5547 if (Info.noteFailure())
5548 Evaluate(NewVal, this->Info, E->getRHS());
5549 return false;
5550 }
5551
5552 if (!Evaluate(NewVal, this->Info, E->getRHS()))
5553 return false;
5554
5555 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
5556 NewVal);
5557}
5558
5559//===----------------------------------------------------------------------===//
5560// Pointer Evaluation
5561//===----------------------------------------------------------------------===//
5562
5563/// Attempts to compute the number of bytes available at the pointer
5564/// returned by a function with the alloc_size attribute. Returns true if we
5565/// were successful. Places an unsigned number into `Result`.
5566///
5567/// This expects the given CallExpr to be a call to a function with an
5568/// alloc_size attribute.
5569static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
5570 const CallExpr *Call,
5571 llvm::APInt &Result) {
5572 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
5573
5574 assert(AllocSize && AllocSize->getElemSizeParam().isValid())(static_cast <bool> (AllocSize && AllocSize->
getElemSizeParam().isValid()) ? void (0) : __assert_fail ("AllocSize && AllocSize->getElemSizeParam().isValid()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5574, __extension__ __PRETTY_FUNCTION__))
;
5575 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
5576 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
5577 if (Call->getNumArgs() <= SizeArgNo)
5578 return false;
5579
5580 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
5581 if (!E->EvaluateAsInt(Into, Ctx, Expr::SE_AllowSideEffects))
5582 return false;
5583 if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
5584 return false;
5585 Into = Into.zextOrSelf(BitsInSizeT);
5586 return true;
5587 };
5588
5589 APSInt SizeOfElem;
5590 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
5591 return false;
5592
5593 if (!AllocSize->getNumElemsParam().isValid()) {
5594 Result = std::move(SizeOfElem);
5595 return true;
5596 }
5597
5598 APSInt NumberOfElems;
5599 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
5600 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
5601 return false;
5602
5603 bool Overflow;
5604 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
5605 if (Overflow)
5606 return false;
5607
5608 Result = std::move(BytesAvailable);
5609 return true;
5610}
5611
5612/// Convenience function. LVal's base must be a call to an alloc_size
5613/// function.
5614static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
5615 const LValue &LVal,
5616 llvm::APInt &Result) {
5617 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&(static_cast <bool> (isBaseAnAllocSizeCall(LVal.getLValueBase
()) && "Can't get the size of a non alloc_size function"
) ? void (0) : __assert_fail ("isBaseAnAllocSizeCall(LVal.getLValueBase()) && \"Can't get the size of a non alloc_size function\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5618, __extension__ __PRETTY_FUNCTION__))
5618 "Can't get the size of a non alloc_size function")(static_cast <bool> (isBaseAnAllocSizeCall(LVal.getLValueBase
()) && "Can't get the size of a non alloc_size function"
) ? void (0) : __assert_fail ("isBaseAnAllocSizeCall(LVal.getLValueBase()) && \"Can't get the size of a non alloc_size function\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5618, __extension__ __PRETTY_FUNCTION__))
;
5619 const auto *Base = LVal.getLValueBase().get<const Expr *>();
5620 const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
5621 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
5622}
5623
5624/// Attempts to evaluate the given LValueBase as the result of a call to
5625/// a function with the alloc_size attribute. If it was possible to do so, this
5626/// function will return true, make Result's Base point to said function call,
5627/// and mark Result's Base as invalid.
5628static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
5629 LValue &Result) {
5630 if (Base.isNull())
5631 return false;
5632
5633 // Because we do no form of static analysis, we only support const variables.
5634 //
5635 // Additionally, we can't support parameters, nor can we support static
5636 // variables (in the latter case, use-before-assign isn't UB; in the former,
5637 // we have no clue what they'll be assigned to).
5638 const auto *VD =
5639 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
5640 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
5641 return false;
5642
5643 const Expr *Init = VD->getAnyInitializer();
5644 if (!Init)
5645 return false;
5646
5647 const Expr *E = Init->IgnoreParens();
5648 if (!tryUnwrapAllocSizeCall(E))
5649 return false;
5650
5651 // Store E instead of E unwrapped so that the type of the LValue's base is
5652 // what the user wanted.
5653 Result.setInvalid(E);
5654
5655 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
5656 Result.addUnsizedArray(Info, E, Pointee);
5657 return true;
5658}
5659
5660namespace {
5661class PointerExprEvaluator
5662 : public ExprEvaluatorBase<PointerExprEvaluator> {
5663 LValue &Result;
5664 bool InvalidBaseOK;
5665
5666 bool Success(const Expr *E) {
5667 Result.set(E);
5668 return true;
5669 }
5670
5671 bool evaluateLValue(const Expr *E, LValue &Result) {
5672 return EvaluateLValue(E, Result, Info, InvalidBaseOK);
5673 }
5674
5675 bool evaluatePointer(const Expr *E, LValue &Result) {
5676 return EvaluatePointer(E, Result, Info, InvalidBaseOK);
5677 }
5678
5679 bool visitNonBuiltinCallExpr(const CallExpr *E);
5680public:
5681
5682 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
5683 : ExprEvaluatorBaseTy(info), Result(Result),
5684 InvalidBaseOK(InvalidBaseOK) {}
5685
5686 bool Success(const APValue &V, const Expr *E) {
5687 Result.setFrom(Info.Ctx, V);
5688 return true;
5689 }
5690 bool ZeroInitialization(const Expr *E) {
5691 auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType());
5692 Result.setNull(E->getType(), TargetVal);
5693 return true;
5694 }
5695
5696 bool VisitBinaryOperator(const BinaryOperator *E);
5697 bool VisitCastExpr(const CastExpr* E);
5698 bool VisitUnaryAddrOf(const UnaryOperator *E);
5699 bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
5700 { return Success(E); }
5701 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
5702 if (Info.noteFailure())
5703 EvaluateIgnoredValue(Info, E->getSubExpr());
5704 return Error(E);
5705 }
5706 bool VisitAddrLabelExpr(const AddrLabelExpr *E)
5707 { return Success(E); }
5708 bool VisitCallExpr(const CallExpr *E);
5709 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
5710 bool VisitBlockExpr(const BlockExpr *E) {
5711 if (!E->getBlockDecl()->hasCaptures())
5712 return Success(E);
5713 return Error(E);
5714 }
5715 bool VisitCXXThisExpr(const CXXThisExpr *E) {
5716 // Can't look at 'this' when checking a potential constant expression.
5717 if (Info.checkingPotentialConstantExpression())
5718 return false;
5719 if (!Info.CurrentCall->This) {
5720 if (Info.getLangOpts().CPlusPlus11)
5721 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
5722 else
5723 Info.FFDiag(E);
5724 return false;
5725 }
5726 Result = *Info.CurrentCall->This;
5727 // If we are inside a lambda's call operator, the 'this' expression refers
5728 // to the enclosing '*this' object (either by value or reference) which is
5729 // either copied into the closure object's field that represents the '*this'
5730 // or refers to '*this'.
5731 if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
5732 // Update 'Result' to refer to the data member/field of the closure object
5733 // that represents the '*this' capture.
5734 if (!HandleLValueMember(Info, E, Result,
5735 Info.CurrentCall->LambdaThisCaptureField))
5736 return false;
5737 // If we captured '*this' by reference, replace the field with its referent.
5738 if (Info.CurrentCall->LambdaThisCaptureField->getType()
5739 ->isPointerType()) {
5740 APValue RVal;
5741 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
5742 RVal))
5743 return false;
5744
5745 Result.setFrom(Info.Ctx, RVal);
5746 }
5747 }
5748 return true;
5749 }
5750
5751 // FIXME: Missing: @protocol, @selector
5752};
5753} // end anonymous namespace
5754
5755static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
5756 bool InvalidBaseOK) {
5757 assert(E->isRValue() && E->getType()->hasPointerRepresentation())(static_cast <bool> (E->isRValue() && E->
getType()->hasPointerRepresentation()) ? void (0) : __assert_fail
("E->isRValue() && E->getType()->hasPointerRepresentation()"
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/AST/ExprConstant.cpp"
, 5757, __extension__ __PRETTY_FUNCTION__))
;
5758 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5759}
5760
5761bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
5762 if (E->getOpcode() != BO_Add &&
5763 E->getOpcode() != BO_Sub)
5764 return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5765
5766 const Expr *PExp = E->getLHS();
5767 const Expr *IExp = E->getRHS();
5768 if (IExp->getType()->isPointerType())
5769 std::swap(PExp, IExp);
5770
5771 bool EvalPtrOK = evaluatePointer(PExp, Result);
5772 if (!EvalPtrOK && !Info.noteFailure())
5773 return false;
5774
5775 llvm::APSInt Offset;
5776 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
5777 return false;
5778
5779 if (E->getOpcode() == BO_Sub)
5780 negateAsSigned(Offset);
5781
5782 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
5783 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
5784}
5785
5786bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
5787 return evaluateLValue(E->getSubExpr(), Result);
5788}
5789
5790bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
5791 const Expr *SubExpr = E->getSubExpr();
5792
5793 switch (E->getCastKind()) {
5794 default:
5795 break;
5796
5797 case CK_BitCast:
5798 case CK_CPointerToObjCPointerCast:
5799 case CK_BlockPointerToObjCPointerCast:
5800 case CK_AnyPointerToBlockPointerCast:
5801 case CK_AddressSpaceConversion:
5802 if (!Visit(SubExpr))
5803 return false;
5804 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
5805 // permitted in constant expressions in C++11. Bitcasts from cv void* are
5806 // also static_casts, but we disallow them as a resolution to DR1312.
5807 if (!E->getType()->isVoidPointerType()) {
5808 // If we changed anything other than cvr-qualifiers, we can't use this
5809 // value for constant folding. FIXME: Qualification conversions should
5810 // always be CK_NoOp, but we get this wrong in C.
5811 if (!Info.Ctx.hasCvrSimilarType(E->getType(), E->getSubExpr()->getType()))
5812 Result.Designator.setInvalid();
5813 if (SubExpr->getType()->isVoidPointerType())
5814 CCEDiag(E, diag::note_constexpr_invalid_cast)
5815 << 3 << SubExpr->getType();
5816 else
5817 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5818 }
5819 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
5820 ZeroInitialization(E);
5821 return true;
5822
5823 case CK_DerivedToBase:
5824 case CK_UncheckedDerivedToBase:
5825 if (!evaluatePointer(E->getSubExpr(), Result))
5826 return false;
5827 if (!Result.Base && Result.Offset.isZero())
5828 return true;
5829
5830 // Now figure out the necessary offset to add to the base LV to get from
5831 // the derived class to the base class.
5832 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
5833 castAs<PointerType>()->getPointeeType(),
5834 Result);
5835
5836 case CK_BaseToDerived:
5837 if (!Visit(E->getSubExpr()))
5838 return false;
5839 if (!Result.Base && Result.Offset.isZero())
5840 return true;
5841 return HandleBaseToDerivedCast(Info, E, Result);
5842
5843 case CK_NullToPointer:
5844 VisitIgnoredValue(E->getSubExpr());
5845 return ZeroInitialization(E);
5846
5847 case CK_IntegralToPointer: {
5848 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5849
5850 APValue Value;
5851 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
5852 break;
5853
5854 if (Value.isInt()) {
5855 unsigned Size = Info.Ctx.getTypeSize(E->getType());
5856 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
5857 Result.Base = (Expr*)nullptr;
5858 Result.InvalidBase = false;
5859 Result.Offset = CharUnits::fromQuantity(N);
5860 Result.Designator.setInvalid();
5861 Result.IsNullPtr = false;
5862 return true;
5863 } else {
5864 // Cast is of an lvalue, no need to change value.
5865 Result.setFrom(Info.Ctx, Value);
5866 return true;
5867 }
5868 }
5869
5870 case CK_ArrayToPointerDecay: {
5871 if (SubExpr->isGLValue()) {
5872 if (!evaluateLValue(SubExpr, Result))
5873 return false;
5874 } else {
5875 APValue &Value = createTemporary(SubExpr, false, Result,
5876 *Info.CurrentCall);
5877 if (!EvaluateInPlace(Value, Info, Result, SubExpr))
5878 return false;
5879 }
5880 // The result is a pointer to the first element of the array.
5881 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
5882 if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
5883 Result.addArray(Info, E, CAT);
5884 else
5885 Result.addUnsizedArray(Info, E, AT->getElementType());
5886 return true;
5887 }
5888
5889 case CK_FunctionToPointerDecay:
5890 return evaluateLValue(SubExpr, Result);
5891
5892 case CK_LValueToRValue: {
5893 LValue LVal;
5894 if (!evaluateLValue(E->getSubExpr(), LVal))
5895 return false;
5896
5897 APValue RVal;
5898 // Note, we use the subexpression's type in order to retain cv-qualifiers.
5899 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
5900 LVal, RVal))
5901 return InvalidBaseOK &&
5902 evaluateLValueAsAllocSize(Info, LVal.Base, Result);
5903 return Success(RVal, E);
5904 }
5905 }
5906
5907 return ExprEvaluatorBaseTy::VisitCastExpr(E);