clang 10.0.0git

SimpleSValBuilder.cpp
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1 // SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- C++ -*-
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines SimpleSValBuilder, a basic implementation of SValBuilder.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
14 #include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
15 #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/SubEngine.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SValVisitor.h"
19
20 using namespace clang;
21 using namespace ento;
22
23 namespace {
24 class SimpleSValBuilder : public SValBuilder {
25 protected:
26 SVal dispatchCast(SVal val, QualType castTy) override;
27 SVal evalCastFromNonLoc(NonLoc val, QualType castTy) override;
28 SVal evalCastFromLoc(Loc val, QualType castTy) override;
29
30 public:
31 SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
32 ProgramStateManager &stateMgr)
33 : SValBuilder(alloc, context, stateMgr) {}
34 ~SimpleSValBuilder() override {}
35
36 SVal evalMinus(NonLoc val) override;
37 SVal evalComplement(NonLoc val) override;
38 SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
39 NonLoc lhs, NonLoc rhs, QualType resultTy) override;
40 SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
41 Loc lhs, Loc rhs, QualType resultTy) override;
42 SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
43 Loc lhs, NonLoc rhs, QualType resultTy) override;
44
45 /// getKnownValue - evaluates a given SVal. If the SVal has only one possible
46 /// (integer) value, that value is returned. Otherwise, returns NULL.
47 const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V) override;
48
49 /// Recursively descends into symbolic expressions and replaces symbols
50 /// with their known values (in the sense of the getKnownValue() method).
51 SVal simplifySVal(ProgramStateRef State, SVal V) override;
52
53 SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op,
54 const llvm::APSInt &RHS, QualType resultTy);
55 };
56 } // end anonymous namespace
57
58 SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
59 ASTContext &context,
60 ProgramStateManager &stateMgr) {
61 return new SimpleSValBuilder(alloc, context, stateMgr);
62 }
63
64 //===----------------------------------------------------------------------===//
65 // Transfer function for Casts.
66 //===----------------------------------------------------------------------===//
67
68 SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) {
69 assert(Val.getAs<Loc>() || Val.getAs<NonLoc>());
70 return Val.getAs<Loc>() ? evalCastFromLoc(Val.castAs<Loc>(), CastTy)
71 : evalCastFromNonLoc(Val.castAs<NonLoc>(), CastTy);
72 }
73
74 SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) {
75 bool isLocType = Loc::isLocType(castTy);
76 if (val.getAs<nonloc::PointerToMember>())
77 return val;
78
79 if (Optional<nonloc::LocAsInteger> LI = val.getAs<nonloc::LocAsInteger>()) {
80 if (isLocType)
81 return LI->getLoc();
82 // FIXME: Correctly support promotions/truncations.
83 unsigned castSize = Context.getIntWidth(castTy);
84 if (castSize == LI->getNumBits())
85 return val;
86 return makeLocAsInteger(LI->getLoc(), castSize);
87 }
88
89 if (const SymExpr *se = val.getAsSymbolicExpression()) {
90 QualType T = Context.getCanonicalType(se->getType());
91 // If types are the same or both are integers, ignore the cast.
92 // FIXME: Remove this hack when we support symbolic truncation/extension.
93 // HACK: If both castTy and T are integers, ignore the cast. This is
94 // not a permanent solution. Eventually we want to precisely handle
95 // extension/truncation of symbolic integers. This prevents us from losing
96 // precision when we assign 'x = y' and 'y' is symbolic and x and y are
97 // different integer types.
98 if (haveSameType(T, castTy))
99 return val;
100
101 if (!isLocType)
102 return makeNonLoc(se, T, castTy);
103 return UnknownVal();
104 }
105
106 // If value is a non-integer constant, produce unknown.
107 if (!val.getAs<nonloc::ConcreteInt>())
108 return UnknownVal();
109
110 // Handle casts to a boolean type.
111 if (castTy->isBooleanType()) {
112 bool b = val.castAs<nonloc::ConcreteInt>().getValue().getBoolValue();
113 return makeTruthVal(b, castTy);
114 }
115
116 // Only handle casts from integers to integers - if val is an integer constant
117 // being cast to a non-integer type, produce unknown.
118 if (!isLocType && !castTy->isIntegralOrEnumerationType())
119 return UnknownVal();
120
121 llvm::APSInt i = val.castAs<nonloc::ConcreteInt>().getValue();
122 BasicVals.getAPSIntType(castTy).apply(i);
123
124 if (isLocType)
125 return makeIntLocVal(i);
126 else
127 return makeIntVal(i);
128 }
129
130 SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) {
131
132 // Casts from pointers -> pointers, just return the lval.
133 //
134 // Casts from pointers -> references, just return the lval. These
135 // can be introduced by the frontend for corner cases, e.g
136 // casting from va_list* to __builtin_va_list&.
137 //
138 if (Loc::isLocType(castTy) || castTy->isReferenceType())
139 return val;
140
141 // FIXME: Handle transparent unions where a value can be "transparently"
142 // lifted into a union type.
143 if (castTy->isUnionType())
144 return UnknownVal();
145
146 // Casting a Loc to a bool will almost always be true,
147 // unless this is a weak function or a symbolic region.
148 if (castTy->isBooleanType()) {
149 switch (val.getSubKind()) {
150 case loc::MemRegionValKind: {
151 const MemRegion *R = val.castAs<loc::MemRegionVal>().getRegion();
152 if (const FunctionCodeRegion *FTR = dyn_cast<FunctionCodeRegion>(R))
153 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FTR->getDecl()))
154 if (FD->isWeak())
155 // FIXME: Currently we are using an extent symbol here,
156 // because there are no generic region address metadata
157 // symbols to use, only content metadata.
158 return nonloc::SymbolVal(SymMgr.getExtentSymbol(FTR));
159
160 if (const SymbolicRegion *SymR = R->getSymbolicBase())
161 return makeNonLoc(SymR->getSymbol(), BO_NE,
162 BasicVals.getZeroWithPtrWidth(), castTy);
163
164 // FALL-THROUGH
165 LLVM_FALLTHROUGH;
166 }
167
168 case loc::GotoLabelKind:
169 // Labels and non-symbolic memory regions are always true.
170 return makeTruthVal(true, castTy);
171 }
172 }
173
174 if (castTy->isIntegralOrEnumerationType()) {
175 unsigned BitWidth = Context.getIntWidth(castTy);
176
177 if (!val.getAs<loc::ConcreteInt>())
178 return makeLocAsInteger(val, BitWidth);
179
180 llvm::APSInt i = val.castAs<loc::ConcreteInt>().getValue();
181 BasicVals.getAPSIntType(castTy).apply(i);
182 return makeIntVal(i);
183 }
184
185 // All other cases: return 'UnknownVal'. This includes casting pointers
186 // to floats, which is probably badness it itself, but this is a good
187 // intermediate solution until we do something better.
188 return UnknownVal();
189 }
190
191 //===----------------------------------------------------------------------===//
192 // Transfer function for unary operators.
193 //===----------------------------------------------------------------------===//
194
195 SVal SimpleSValBuilder::evalMinus(NonLoc val) {
196 switch (val.getSubKind()) {
197 case nonloc::ConcreteIntKind:
198 return val.castAs<nonloc::ConcreteInt>().evalMinus(*this);
199 default:
200 return UnknownVal();
201 }
202 }
203
204 SVal SimpleSValBuilder::evalComplement(NonLoc X) {
205 switch (X.getSubKind()) {
206 case nonloc::ConcreteIntKind:
207 return X.castAs<nonloc::ConcreteInt>().evalComplement(*this);
208 default:
209 return UnknownVal();
210 }
211 }
212
213 //===----------------------------------------------------------------------===//
214 // Transfer function for binary operators.
215 //===----------------------------------------------------------------------===//
216
217 SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
218 BinaryOperator::Opcode op,
219 const llvm::APSInt &RHS,
220 QualType resultTy) {
221 bool isIdempotent = false;
222
223 // Check for a few special cases with known reductions first.
224 switch (op) {
225 default:
226 // We can't reduce this case; just treat it normally.
227 break;
228 case BO_Mul:
229 // a*0 and a*1
230 if (RHS == 0)
231 return makeIntVal(0, resultTy);
232 else if (RHS == 1)
233 isIdempotent = true;
234 break;
235 case BO_Div:
236 // a/0 and a/1
237 if (RHS == 0)
238 // This is also handled elsewhere.
239 return UndefinedVal();
240 else if (RHS == 1)
241 isIdempotent = true;
242 break;
243 case BO_Rem:
244 // a%0 and a%1
245 if (RHS == 0)
246 // This is also handled elsewhere.
247 return UndefinedVal();
248 else if (RHS == 1)
249 return makeIntVal(0, resultTy);
250 break;
251 case BO_Add:
252 case BO_Sub:
253 case BO_Shl:
254 case BO_Shr:
255 case BO_Xor:
256 // a+0, a-0, a<<0, a>>0, a^0
257 if (RHS == 0)
258 isIdempotent = true;
259 break;
260 case BO_And:
261 // a&0 and a&(~0)
262 if (RHS == 0)
263 return makeIntVal(0, resultTy);
264 else if (RHS.isAllOnesValue())
265 isIdempotent = true;
266 break;
267 case BO_Or:
268 // a|0 and a|(~0)
269 if (RHS == 0)
270 isIdempotent = true;
271 else if (RHS.isAllOnesValue()) {
272 const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
273 return nonloc::ConcreteInt(Result);
274 }
275 break;
276 }
277
278 // Idempotent ops (like a*1) can still change the type of an expression.
279 // Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
280 // dirty work.
281 if (isIdempotent)
282 return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);
283
284 // If we reach this point, the expression cannot be simplified.
285 // Make a SymbolVal for the entire expression, after converting the RHS.
286 const llvm::APSInt *ConvertedRHS = &RHS;
287 if (BinaryOperator::isComparisonOp(op)) {
288 // We're looking for a type big enough to compare the symbolic value
289 // with the given constant.
290 // FIXME: This is an approximation of Sema::UsualArithmeticConversions.
291 ASTContext &Ctx = getContext();
292 QualType SymbolType = LHS->getType();
293 uint64_t ValWidth = RHS.getBitWidth();
294 uint64_t TypeWidth = Ctx.getTypeSize(SymbolType);
295
296 if (ValWidth < TypeWidth) {
297 // If the value is too small, extend it.
298 ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
299 } else if (ValWidth == TypeWidth) {
300 // If the value is signed but the symbol is unsigned, do the comparison
301 // in unsigned space. [C99 6.3.1.8]
302 // (For the opposite case, the value is already unsigned.)
303 if (RHS.isSigned() && !SymbolType->isSignedIntegerOrEnumerationType())
304 ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
305 }
306 } else
307 ConvertedRHS = &BasicVals.Convert(resultTy, RHS);
308
309 return makeNonLoc(LHS, op, *ConvertedRHS, resultTy);
310 }
311
312 // See if Sym is known to be a relation Rel with Bound.
313 static bool isInRelation(BinaryOperator::Opcode Rel, SymbolRef Sym,
314 llvm::APSInt Bound, ProgramStateRef State) {
315 SValBuilder &SVB = State->getStateManager().getSValBuilder();
316 SVal Result =
317 SVB.evalBinOpNN(State, Rel, nonloc::SymbolVal(Sym),
318 nonloc::ConcreteInt(Bound), SVB.getConditionType());
319 if (auto DV = Result.getAs<DefinedSVal>()) {
320 return !State->assume(*DV, false);
321 }
322 return false;
323 }
324
325 // See if Sym is known to be within [min/4, max/4], where min and max
326 // are the bounds of the symbol's integral type. With such symbols,
327 // some manipulations can be performed without the risk of overflow.
328 // assume() doesn't cause infinite recursion because we should be dealing
329 // with simpler symbols on every recursive call.
330 static bool isWithinConstantOverflowBounds(SymbolRef Sym,
331 ProgramStateRef State) {
332 SValBuilder &SVB = State->getStateManager().getSValBuilder();
333 BasicValueFactory &BV = SVB.getBasicValueFactory();
334
335 QualType T = Sym->getType();
336 assert(T->isSignedIntegerOrEnumerationType() &&
337 "This only works with signed integers!");
338 APSIntType AT = BV.getAPSIntType(T);
339
340 llvm::APSInt Max = AT.getMaxValue() / AT.getValue(4), Min = -Max;
341 return isInRelation(BO_LE, Sym, Max, State) &&
342 isInRelation(BO_GE, Sym, Min, State);
343 }
344
345 // Same for the concrete integers: see if I is within [min/4, max/4].
346 static bool isWithinConstantOverflowBounds(llvm::APSInt I) {
347 APSIntType AT(I);
348 assert(!AT.isUnsigned() &&
349 "This only works with signed integers!");
350
351 llvm::APSInt Max = AT.getMaxValue() / AT.getValue(4), Min = -Max;
352 return (I <= Max) && (I >= -Max);
353 }
354
355 static std::pair<SymbolRef, llvm::APSInt>
356 decomposeSymbol(SymbolRef Sym, BasicValueFactory &BV) {
357 if (const auto *SymInt = dyn_cast<SymIntExpr>(Sym))
358 if (BinaryOperator::isAdditiveOp(SymInt->getOpcode()))
359 return std::make_pair(SymInt->getLHS(),
360 (SymInt->getOpcode() == BO_Add) ?
361 (SymInt->getRHS()) :
362 (-SymInt->getRHS()));
363
364 // Fail to decompose: "reduce" the problem to the "$x + 0" case.
365 return std::make_pair(Sym, BV.getValue(0, Sym->getType()));
366 }
367
368 // Simplify "(LSym + LInt) Op (RSym + RInt)" assuming all values are of the
369 // same signed integral type and no overflows occur (which should be checked
370 // by the caller).
371 static NonLoc doRearrangeUnchecked(ProgramStateRef State,
372 BinaryOperator::Opcode Op,
373 SymbolRef LSym, llvm::APSInt LInt,
374 SymbolRef RSym, llvm::APSInt RInt) {
375 SValBuilder &SVB = State->getStateManager().getSValBuilder();
376 BasicValueFactory &BV = SVB.getBasicValueFactory();
377 SymbolManager &SymMgr = SVB.getSymbolManager();
378
379 QualType SymTy = LSym->getType();
380 assert(SymTy == RSym->getType() &&
381 "Symbols are not of the same type!");
382 assert(APSIntType(LInt) == BV.getAPSIntType(SymTy) &&
383 "Integers are not of the same type as symbols!");
384 assert(APSIntType(RInt) == BV.getAPSIntType(SymTy) &&
385 "Integers are not of the same type as symbols!");
386
387 QualType ResultTy;
388 if (BinaryOperator::isComparisonOp(Op))
389 ResultTy = SVB.getConditionType();
390 else if (BinaryOperator::isAdditiveOp(Op))
391 ResultTy = SymTy;
392 else
393 llvm_unreachable("Operation not suitable for unchecked rearrangement!");
394
395 // FIXME: Can we use assume() without getting into an infinite recursion?
396 if (LSym == RSym)
397 return SVB.evalBinOpNN(State, Op, nonloc::ConcreteInt(LInt),
398 nonloc::ConcreteInt(RInt), ResultTy)
399 .castAs<NonLoc>();
400
401 SymbolRef ResultSym = nullptr;
402 BinaryOperator::Opcode ResultOp;
403 llvm::APSInt ResultInt;
404 if (BinaryOperator::isComparisonOp(Op)) {
405 // Prefer comparing to a non-negative number.
406 // FIXME: Maybe it'd be better to have consistency in
407 // "$x - $y" vs. "$y - $x" because those are solver's keys.
408 if (LInt > RInt) {
409 ResultSym = SymMgr.getSymSymExpr(RSym, BO_Sub, LSym, SymTy);
410 ResultOp = BinaryOperator::reverseComparisonOp(Op);
411 ResultInt = LInt - RInt; // Opposite order!
412 } else {
413 ResultSym = SymMgr.getSymSymExpr(LSym, BO_Sub, RSym, SymTy);
414 ResultOp = Op;
415 ResultInt = RInt - LInt; // Opposite order!
416 }
417 } else {
418 ResultSym = SymMgr.getSymSymExpr(LSym, Op, RSym, SymTy);
419 ResultInt = (Op == BO_Add) ? (LInt + RInt) : (LInt - RInt);
420 ResultOp = BO_Add;
421 // Bring back the cosmetic difference.
422 if (ResultInt < 0) {
423 ResultInt = -ResultInt;
424 ResultOp = BO_Sub;
425 } else if (ResultInt == 0) {
426 // Shortcut: Simplify "$x + 0" to "$x".
427 return nonloc::SymbolVal(ResultSym);
428 }
429 }
430 const llvm::APSInt &PersistentResultInt = BV.getValue(ResultInt);
431 return nonloc::SymbolVal(
432 SymMgr.getSymIntExpr(ResultSym, ResultOp, PersistentResultInt, ResultTy));
433 }
434
435 // Rearrange if symbol type matches the result type and if the operator is a
436 // comparison operator, both symbol and constant must be within constant
437 // overflow bounds.
438 static bool shouldRearrange(ProgramStateRef State, BinaryOperator::Opcode Op,
439 SymbolRef Sym, llvm::APSInt Int, QualType Ty) {
440 return Sym->getType() == Ty &&
441 (!BinaryOperator::isComparisonOp(Op) ||
442 (isWithinConstantOverflowBounds(Sym, State) &&
443 isWithinConstantOverflowBounds(Int)));
444 }
445
446 static Optional<NonLoc> tryRearrange(ProgramStateRef State,
447 BinaryOperator::Opcode Op, NonLoc Lhs,
448 NonLoc Rhs, QualType ResultTy) {
449 ProgramStateManager &StateMgr = State->getStateManager();
450 SValBuilder &SVB = StateMgr.getSValBuilder();
451
452 // We expect everything to be of the same type - this type.
453 QualType SingleTy;
454
455 auto &Opts =
456 StateMgr.getOwningEngine().getAnalysisManager().getAnalyzerOptions();
457
458 // FIXME: After putting complexity threshold to the symbols we can always
459 // rearrange additive operations but rearrange comparisons only if
460 // option is set.
461 if(!Opts.ShouldAggressivelySimplifyBinaryOperation)
462 return None;
463
464 SymbolRef LSym = Lhs.getAsSymbol();
465 if (!LSym)
466 return None;
467
468 if (BinaryOperator::isComparisonOp(Op)) {
469 SingleTy = LSym->getType();
470 if (ResultTy != SVB.getConditionType())
471 return None;
472 // Initialize SingleTy later with a symbol's type.
473 } else if (BinaryOperator::isAdditiveOp(Op)) {
474 SingleTy = ResultTy;
475 if (LSym->getType() != SingleTy)
476 return None;
477 } else {
478 // Don't rearrange other operations.
479 return None;
480 }
481
482 assert(!SingleTy.isNull() && "We should have figured out the type by now!");
483
484 // Rearrange signed symbolic expressions only
485 if (!SingleTy->isSignedIntegerOrEnumerationType())
486 return None;
487
488 SymbolRef RSym = Rhs.getAsSymbol();
489 if (!RSym || RSym->getType() != SingleTy)
490 return None;
491
492 BasicValueFactory &BV = State->getBasicVals();
493 llvm::APSInt LInt, RInt;
494 std::tie(LSym, LInt) = decomposeSymbol(LSym, BV);
495 std::tie(RSym, RInt) = decomposeSymbol(RSym, BV);
496 if (!shouldRearrange(State, Op, LSym, LInt, SingleTy) ||
497 !shouldRearrange(State, Op, RSym, RInt, SingleTy))
498 return None;
499
500 // We know that no overflows can occur anymore.
501 return doRearrangeUnchecked(State, Op, LSym, LInt, RSym, RInt);
502 }
503
504 SVal SimpleSValBuilder::evalBinOpNN(ProgramStateRef state,
505 BinaryOperator::Opcode op,
506 NonLoc lhs, NonLoc rhs,
507 QualType resultTy) {
508 NonLoc InputLHS = lhs;
509 NonLoc InputRHS = rhs;
510
511 // Handle trivial case where left-side and right-side are the same.
512 if (lhs == rhs)
513 switch (op) {
514 default:
515 break;
516 case BO_EQ:
517 case BO_LE:
518 case BO_GE:
519 return makeTruthVal(true, resultTy);
520 case BO_LT:
521 case BO_GT:
522 case BO_NE:
523 return makeTruthVal(false, resultTy);
524 case BO_Xor:
525 case BO_Sub:
526 if (resultTy->isIntegralOrEnumerationType())
527 return makeIntVal(0, resultTy);
528 return evalCastFromNonLoc(makeIntVal(0, /*isUnsigned=*/false), resultTy);
529 case BO_Or:
530 case BO_And:
531 return evalCastFromNonLoc(lhs, resultTy);
532 }
533
534 while (1) {
535 switch (lhs.getSubKind()) {
536 default:
537 return makeSymExprValNN(op, lhs, rhs, resultTy);
538 case nonloc::PointerToMemberKind: {
539 assert(rhs.getSubKind() == nonloc::PointerToMemberKind &&
540 "Both SVals should have pointer-to-member-type");
541 auto LPTM = lhs.castAs<nonloc::PointerToMember>(),
542 RPTM = rhs.castAs<nonloc::PointerToMember>();
543 auto LPTMD = LPTM.getPTMData(), RPTMD = RPTM.getPTMData();
544 switch (op) {
545 case BO_EQ:
546 return makeTruthVal(LPTMD == RPTMD, resultTy);
547 case BO_NE:
548 return makeTruthVal(LPTMD != RPTMD, resultTy);
549 default:
550 return UnknownVal();
551 }
552 }
553 case nonloc::LocAsIntegerKind: {
554 Loc lhsL = lhs.castAs<nonloc::LocAsInteger>().getLoc();
555 switch (rhs.getSubKind()) {
556 case nonloc::LocAsIntegerKind:
557 // FIXME: at the moment the implementation
558 // of modeling "pointers as integers" is not complete.
559 if (!BinaryOperator::isComparisonOp(op))
560 return UnknownVal();
561 return evalBinOpLL(state, op, lhsL,
562 rhs.castAs<nonloc::LocAsInteger>().getLoc(),
563 resultTy);
564 case nonloc::ConcreteIntKind: {
565 // FIXME: at the moment the implementation
566 // of modeling "pointers as integers" is not complete.
567 if (!BinaryOperator::isComparisonOp(op))
568 return UnknownVal();
569 // Transform the integer into a location and compare.
570 // FIXME: This only makes sense for comparisons. If we want to, say,
571 // add 1 to a LocAsInteger, we'd better unpack the Loc and add to it,
572 // then pack it back into a LocAsInteger.
573 llvm::APSInt i = rhs.castAs<nonloc::ConcreteInt>().getValue();
574 // If the region has a symbolic base, pay attention to the type; it
575 // might be coming from a non-default address space. For non-symbolic
576 // regions it doesn't matter that much because such comparisons would
577 // most likely evaluate to concrete false anyway. FIXME: We might
578 // still need to handle the non-comparison case.
579 if (SymbolRef lSym = lhs.getAsLocSymbol(true))
580 BasicVals.getAPSIntType(lSym->getType()).apply(i);
581 else
582 BasicVals.getAPSIntType(Context.VoidPtrTy).apply(i);
583 return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy);
584 }
585 default:
586 switch (op) {
587 case BO_EQ:
588 return makeTruthVal(false, resultTy);
589 case BO_NE:
590 return makeTruthVal(true, resultTy);
591 default:
592 // This case also handles pointer arithmetic.
593 return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
594 }
595 }
596 }
597 case nonloc::ConcreteIntKind: {
598 llvm::APSInt LHSValue = lhs.castAs<nonloc::ConcreteInt>().getValue();
599
600 // If we're dealing with two known constants, just perform the operation.
601 if (const llvm::APSInt *KnownRHSValue = getKnownValue(state, rhs)) {
602 llvm::APSInt RHSValue = *KnownRHSValue;
603 if (BinaryOperator::isComparisonOp(op)) {
604 // We're looking for a type big enough to compare the two values.
605 // FIXME: This is not correct. char + short will result in a promotion
606 // to int. Unfortunately we have lost types by this point.
607 APSIntType CompareType = std::max(APSIntType(LHSValue),
608 APSIntType(RHSValue));
609 CompareType.apply(LHSValue);
610 CompareType.apply(RHSValue);
611 } else if (!BinaryOperator::isShiftOp(op)) {
612 APSIntType IntType = BasicVals.getAPSIntType(resultTy);
613 IntType.apply(LHSValue);
614 IntType.apply(RHSValue);
615 }
616
617 const llvm::APSInt *Result =
618 BasicVals.evalAPSInt(op, LHSValue, RHSValue);
619 if (!Result)
620 return UndefinedVal();
621
622 return nonloc::ConcreteInt(*Result);
623 }
624
625 // Swap the left and right sides and flip the operator if doing so
626 // allows us to better reason about the expression (this is a form
627 // of expression canonicalization).
628 // While we're at it, catch some special cases for non-commutative ops.
629 switch (op) {
630 case BO_LT:
631 case BO_GT:
632 case BO_LE:
633 case BO_GE:
634 op = BinaryOperator::reverseComparisonOp(op);
635 LLVM_FALLTHROUGH;
636 case BO_EQ:
637 case BO_NE:
638 case BO_Add:
639 case BO_Mul:
640 case BO_And:
641 case BO_Xor:
642 case BO_Or:
643 std::swap(lhs, rhs);
644 continue;
645 case BO_Shr:
646 // (~0)>>a
647 if (LHSValue.isAllOnesValue() && LHSValue.isSigned())
648 return evalCastFromNonLoc(lhs, resultTy);
649 LLVM_FALLTHROUGH;
650 case BO_Shl:
651 // 0<<a and 0>>a
652 if (LHSValue == 0)
653 return evalCastFromNonLoc(lhs, resultTy);
654 return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
655 default:
656 return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
657 }
658 }
659 case nonloc::SymbolValKind: {
660 // We only handle LHS as simple symbols or SymIntExprs.
661 SymbolRef Sym = lhs.castAs<nonloc::SymbolVal>().getSymbol();
662
663 // LHS is a symbolic expression.
664 if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(Sym)) {
665
666 // Is this a logical not? (!x is represented as x == 0.)
667 if (op == BO_EQ && rhs.isZeroConstant()) {
668 // We know how to negate certain expressions. Simplify them here.
669
670 BinaryOperator::Opcode opc = symIntExpr->getOpcode();
671 switch (opc) {
672 default:
673 // We don't know how to negate this operation.
674 // Just handle it as if it were a normal comparison to 0.
675 break;
676 case BO_LAnd:
677 case BO_LOr:
678 llvm_unreachable("Logical operators handled by branching logic.");
679 case BO_Assign:
680 case BO_MulAssign:
681 case BO_DivAssign:
682 case BO_RemAssign:
683 case BO_AddAssign:
684 case BO_SubAssign:
685 case BO_ShlAssign:
686 case BO_ShrAssign:
687 case BO_AndAssign:
688 case BO_XorAssign:
689 case BO_OrAssign:
690 case BO_Comma:
691 llvm_unreachable("'=' and ',' operators handled by ExprEngine.");
692 case BO_PtrMemD:
693 case BO_PtrMemI:
694 llvm_unreachable("Pointer arithmetic not handled here.");
695 case BO_LT:
696 case BO_GT:
697 case BO_LE:
698 case BO_GE:
699 case BO_EQ:
700 case BO_NE:
701 assert(resultTy->isBooleanType() ||
702 resultTy == getConditionType());
703 assert(symIntExpr->getType()->isBooleanType() ||
704 getContext().hasSameUnqualifiedType(symIntExpr->getType(),
705 getConditionType()));
706 // Negate the comparison and make a value.
707 opc = BinaryOperator::negateComparisonOp(opc);
708 return makeNonLoc(symIntExpr->getLHS(), opc,
709 symIntExpr->getRHS(), resultTy);
710 }
711 }
712
713 // For now, only handle expressions whose RHS is a constant.
714 if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs)) {
715 // If both the LHS and the current expression are additive,
716 // fold their constants and try again.
717 if (BinaryOperator::isAdditiveOp(op)) {
718 BinaryOperator::Opcode lop = symIntExpr->getOpcode();
719 if (BinaryOperator::isAdditiveOp(lop)) {
720 // Convert the two constants to a common type, then combine them.
721
722 // resultTy may not be the best type to convert to, but it's
723 // probably the best choice in expressions with mixed type
724 // (such as x+1U+2LL). The rules for implicit conversions should
725 // choose a reasonable type to preserve the expression, and will
726 // at least match how the value is going to be used.
727 APSIntType IntType = BasicVals.getAPSIntType(resultTy);
728 const llvm::APSInt &first = IntType.convert(symIntExpr->getRHS());
729 const llvm::APSInt &second = IntType.convert(*RHSValue);
730
731 const llvm::APSInt *newRHS;
732 if (lop == op)
733 newRHS = BasicVals.evalAPSInt(BO_Add, first, second);
734 else
735 newRHS = BasicVals.evalAPSInt(BO_Sub, first, second);
736
737 assert(newRHS && "Invalid operation despite common type!");
738 rhs = nonloc::ConcreteInt(*newRHS);
739 lhs = nonloc::SymbolVal(symIntExpr->getLHS());
740 op = lop;
741 continue;
742 }
743 }
744
745 // Otherwise, make a SymIntExpr out of the expression.
746 return MakeSymIntVal(symIntExpr, op, *RHSValue, resultTy);
747 }
748 }
749
750 // Does the symbolic expression simplify to a constant?
751 // If so, "fold" the constant by setting 'lhs' to a ConcreteInt
752 // and try again.
753 SVal simplifiedLhs = simplifySVal(state, lhs);
754 if (simplifiedLhs != lhs)
755 if (auto simplifiedLhsAsNonLoc = simplifiedLhs.getAs<NonLoc>()) {
756 lhs = *simplifiedLhsAsNonLoc;
757 continue;
758 }
759
760 // Is the RHS a constant?
761 if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs))
762 return MakeSymIntVal(Sym, op, *RHSValue, resultTy);
763
764 if (Optional<NonLoc> V = tryRearrange(state, op, lhs, rhs, resultTy))
765 return *V;
766
767 // Give up -- this is not a symbolic expression we can handle.
768 return makeSymExprValNN(op, InputLHS, InputRHS, resultTy);
769 }
770 }
771 }
772 }
773
774 static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR,
775 const FieldRegion *RightFR,
776 BinaryOperator::Opcode op,
777 QualType resultTy,
778 SimpleSValBuilder &SVB) {
779 // Only comparisons are meaningful here!
780 if (!BinaryOperator::isComparisonOp(op))
781 return UnknownVal();
782
783 // Next, see if the two FRs have the same super-region.
784 // FIXME: This doesn't handle casts yet, and simply stripping the casts
785 // doesn't help.
786 if (LeftFR->getSuperRegion() != RightFR->getSuperRegion())
787 return UnknownVal();
788
789 const FieldDecl *LeftFD = LeftFR->getDecl();
790 const FieldDecl *RightFD = RightFR->getDecl();
791 const RecordDecl *RD = LeftFD->getParent();
792
793 // Make sure the two FRs are from the same kind of record. Just in case!
794 // FIXME: This is probably where inheritance would be a problem.
795 if (RD != RightFD->getParent())
796 return UnknownVal();
797
798 // We know for sure that the two fields are not the same, since that
799 // would have given us the same SVal.
800 if (op == BO_EQ)
801 return SVB.makeTruthVal(false, resultTy);
802 if (op == BO_NE)
803 return SVB.makeTruthVal(true, resultTy);
804
805 // Iterate through the fields and see which one comes first.
806 // [C99 6.7.2.1.13] "Within a structure object, the non-bit-field
807 // members and the units in which bit-fields reside have addresses that
808 // increase in the order in which they are declared."
809 bool leftFirst = (op == BO_LT || op == BO_LE);
810 for (const auto *I : RD->fields()) {
811 if (I == LeftFD)
812 return SVB.makeTruthVal(leftFirst, resultTy);
813 if (I == RightFD)
814 return SVB.makeTruthVal(!leftFirst, resultTy);
815 }
816
817 llvm_unreachable("Fields not found in parent record's definition");
818 }
819
820 // FIXME: all this logic will change if/when we have MemRegion::getLocation().
821 SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
822 BinaryOperator::Opcode op,
823 Loc lhs, Loc rhs,
824 QualType resultTy) {
825 // Only comparisons and subtractions are valid operations on two pointers.
826 // See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15].
827 // However, if a pointer is casted to an integer, evalBinOpNN may end up
828 // calling this function with another operation (PR7527). We don't attempt to
829 // model this for now, but it could be useful, particularly when the
830 // "location" is actually an integer value that's been passed through a void*.
831 if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub))
832 return UnknownVal();
833
834 // Special cases for when both sides are identical.
835 if (lhs == rhs) {
836 switch (op) {
837 default:
838 llvm_unreachable("Unimplemented operation for two identical values");
839 case BO_Sub:
840 return makeZeroVal(resultTy);
841 case BO_EQ:
842 case BO_LE:
843 case BO_GE:
844 return makeTruthVal(true, resultTy);
845 case BO_NE:
846 case BO_LT:
847 case BO_GT:
848 return makeTruthVal(false, resultTy);
849 }
850 }
851
852 switch (lhs.getSubKind()) {
853 default:
854 llvm_unreachable("Ordering not implemented for this Loc.");
855
856 case loc::GotoLabelKind:
857 // The only thing we know about labels is that they're non-null.
858 if (rhs.isZeroConstant()) {
859 switch (op) {
860 default:
861 break;
862 case BO_Sub:
863 return evalCastFromLoc(lhs, resultTy);
864 case BO_EQ:
865 case BO_LE:
866 case BO_LT:
867 return makeTruthVal(false, resultTy);
868 case BO_NE:
869 case BO_GT:
870 case BO_GE:
871 return makeTruthVal(true, resultTy);
872 }
873 }
874 // There may be two labels for the same location, and a function region may
875 // have the same address as a label at the start of the function (depending
876 // on the ABI).
877 // FIXME: we can probably do a comparison against other MemRegions, though.
878 // FIXME: is there a way to tell if two labels refer to the same location?
879 return UnknownVal();
880
881 case loc::ConcreteIntKind: {
882 // If one of the operands is a symbol and the other is a constant,
883 // build an expression for use by the constraint manager.
884 if (SymbolRef rSym = rhs.getAsLocSymbol()) {
885 // We can only build expressions with symbols on the left,
886 // so we need a reversible operator.
887 if (!BinaryOperator::isComparisonOp(op) || op == BO_Cmp)
888 return UnknownVal();
889
890 const llvm::APSInt &lVal = lhs.castAs<loc::ConcreteInt>().getValue();
891 op = BinaryOperator::reverseComparisonOp(op);
892 return makeNonLoc(rSym, op, lVal, resultTy);
893 }
894
895 // If both operands are constants, just perform the operation.
896 if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
897 SVal ResultVal =
898 lhs.castAs<loc::ConcreteInt>().evalBinOp(BasicVals, op, *rInt);
899 if (Optional<NonLoc> Result = ResultVal.getAs<NonLoc>())
900 return evalCastFromNonLoc(*Result, resultTy);
901
902 assert(!ResultVal.getAs<Loc>() && "Loc-Loc ops should not produce Locs");
903 return UnknownVal();
904 }
905
906 // Special case comparisons against NULL.
907 // This must come after the test if the RHS is a symbol, which is used to
908 // build constraints. The address of any non-symbolic region is guaranteed
909 // to be non-NULL, as is any label.
910 assert(rhs.getAs<loc::MemRegionVal>() || rhs.getAs<loc::GotoLabel>());
911 if (lhs.isZeroConstant()) {
912 switch (op) {
913 default:
914 break;
915 case BO_EQ:
916 case BO_GT:
917 case BO_GE:
918 return makeTruthVal(false, resultTy);
919 case BO_NE:
920 case BO_LT:
921 case BO_LE:
922 return makeTruthVal(true, resultTy);
923 }
924 }
925
926 // Comparing an arbitrary integer to a region or label address is
927 // completely unknowable.
928 return UnknownVal();
929 }
930 case loc::MemRegionValKind: {
931 if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
932 // If one of the operands is a symbol and the other is a constant,
933 // build an expression for use by the constraint manager.
934 if (SymbolRef lSym = lhs.getAsLocSymbol(true)) {
935 if (BinaryOperator::isComparisonOp(op))
936 return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy);
937 return UnknownVal();
938 }
939 // Special case comparisons to NULL.
940 // This must come after the test if the LHS is a symbol, which is used to
941 // build constraints. The address of any non-symbolic region is guaranteed
942 // to be non-NULL.
943 if (rInt->isZeroConstant()) {
944 if (op == BO_Sub)
945 return evalCastFromLoc(lhs, resultTy);
946
947 if (BinaryOperator::isComparisonOp(op)) {
948 QualType boolType = getContext().BoolTy;
949 NonLoc l = evalCastFromLoc(lhs, boolType).castAs<NonLoc>();
950 NonLoc r = makeTruthVal(false, boolType).castAs<NonLoc>();
951 return evalBinOpNN(state, op, l, r, resultTy);
952 }
953 }
954
955 // Comparing a region to an arbitrary integer is completely unknowable.
956 return UnknownVal();
957 }
958
959 // Get both values as regions, if possible.
960 const MemRegion *LeftMR = lhs.getAsRegion();
961 assert(LeftMR && "MemRegionValKind SVal doesn't have a region!");
962
963 const MemRegion *RightMR = rhs.getAsRegion();
964 if (!RightMR)
965 // The RHS is probably a label, which in theory could address a region.
966 // FIXME: we can probably make a more useful statement about non-code
967 // regions, though.
968 return UnknownVal();
969
970 const MemRegion *LeftBase = LeftMR->getBaseRegion();
971 const MemRegion *RightBase = RightMR->getBaseRegion();
972 const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
973 const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
974 const MemSpaceRegion *UnknownMS = MemMgr.getUnknownRegion();
975
976 // If the two regions are from different known memory spaces they cannot be
977 // equal. Also, assume that no symbolic region (whose memory space is
978 // unknown) is on the stack.
979 if (LeftMS != RightMS &&
980 ((LeftMS != UnknownMS && RightMS != UnknownMS) ||
981 (isa<StackSpaceRegion>(LeftMS) || isa<StackSpaceRegion>(RightMS)))) {
982 switch (op) {
983 default:
984 return UnknownVal();
985 case BO_EQ:
986 return makeTruthVal(false, resultTy);
987 case BO_NE:
988 return makeTruthVal(true, resultTy);
989 }
990 }
991
992 // If both values wrap regions, see if they're from different base regions.
993 // Note, heap base symbolic regions are assumed to not alias with
994 // each other; for example, we assume that malloc returns different address
995 // on each invocation.
996 // FIXME: ObjC object pointers always reside on the heap, but currently
997 // we treat their memory space as unknown, because symbolic pointers
998 // to ObjC objects may alias. There should be a way to construct
999 // possibly-aliasing heap-based regions. For instance, MacOSXApiChecker
1000 // guesses memory space for ObjC object pointers manually instead of
1001 // relying on us.
1002 if (LeftBase != RightBase &&
1003 ((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) ||
1004 (isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){
1005 switch (op) {
1006 default:
1007 return UnknownVal();
1008 case BO_EQ:
1009 return makeTruthVal(false, resultTy);
1010 case BO_NE:
1011 return makeTruthVal(true, resultTy);
1012 }
1013 }
1014
1015 // Handle special cases for when both regions are element regions.
1016 const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
1017 const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR);
1018 if (RightER && LeftER) {
1019 // Next, see if the two ERs have the same super-region and matching types.
1020 // FIXME: This should do something useful even if the types don't match,
1021 // though if both indexes are constant the RegionRawOffset path will
1022 // give the correct answer.
1023 if (LeftER->getSuperRegion() == RightER->getSuperRegion() &&
1024 LeftER->getElementType() == RightER->getElementType()) {
1025 // Get the left index and cast it to the correct type.
1026 // If the index is unknown or undefined, bail out here.
1027 SVal LeftIndexVal = LeftER->getIndex();
1028 Optional<NonLoc> LeftIndex = LeftIndexVal.getAs<NonLoc>();
1029 if (!LeftIndex)
1030 return UnknownVal();
1031 LeftIndexVal = evalCastFromNonLoc(*LeftIndex, ArrayIndexTy);
1032 LeftIndex = LeftIndexVal.getAs<NonLoc>();
1033 if (!LeftIndex)
1034 return UnknownVal();
1035
1036 // Do the same for the right index.
1037 SVal RightIndexVal = RightER->getIndex();
1038 Optional<NonLoc> RightIndex = RightIndexVal.getAs<NonLoc>();
1039 if (!RightIndex)
1040 return UnknownVal();
1041 RightIndexVal = evalCastFromNonLoc(*RightIndex, ArrayIndexTy);
1042 RightIndex = RightIndexVal.getAs<NonLoc>();
1043 if (!RightIndex)
1044 return UnknownVal();
1045
1046 // Actually perform the operation.
1047 // evalBinOpNN expects the two indexes to already be the right type.
1048 return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy);
1049 }
1050 }
1051
1052 // Special handling of the FieldRegions, even with symbolic offsets.
1053 const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
1054 const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR);
1055 if (RightFR && LeftFR) {
1056 SVal R = evalBinOpFieldRegionFieldRegion(LeftFR, RightFR, op, resultTy,
1057 *this);
1058 if (!R.isUnknown())
1059 return R;
1060 }
1061
1062 // Compare the regions using the raw offsets.
1063 RegionOffset LeftOffset = LeftMR->getAsOffset();
1064 RegionOffset RightOffset = RightMR->getAsOffset();
1065
1066 if (LeftOffset.getRegion() != nullptr &&
1067 LeftOffset.getRegion() == RightOffset.getRegion() &&
1068 !LeftOffset.hasSymbolicOffset() && !RightOffset.hasSymbolicOffset()) {
1069 int64_t left = LeftOffset.getOffset();
1070 int64_t right = RightOffset.getOffset();
1071
1072 switch (op) {
1073 default:
1074 return UnknownVal();
1075 case BO_LT:
1076 return makeTruthVal(left < right, resultTy);
1077 case BO_GT:
1078 return makeTruthVal(left > right, resultTy);
1079 case BO_LE:
1080 return makeTruthVal(left <= right, resultTy);
1081 case BO_GE:
1082 return makeTruthVal(left >= right, resultTy);
1083 case BO_EQ:
1084 return makeTruthVal(left == right, resultTy);
1085 case BO_NE:
1086 return makeTruthVal(left != right, resultTy);
1087 }
1088 }
1089
1090 // At this point we're not going to get a good answer, but we can try
1091 // conjuring an expression instead.
1092 SymbolRef LHSSym = lhs.getAsLocSymbol();
1093 SymbolRef RHSSym = rhs.getAsLocSymbol();
1094 if (LHSSym && RHSSym)
1095 return makeNonLoc(LHSSym, op, RHSSym, resultTy);
1096
1097 // If we get here, we have no way of comparing the regions.
1098 return UnknownVal();
1099 }
1100 }
1101 }
1102
1103 SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state,
1104 BinaryOperator::Opcode op,
1105 Loc lhs, NonLoc rhs, QualType resultTy) {
1106 if (op >= BO_PtrMemD && op <= BO_PtrMemI) {
1107 if (auto PTMSV = rhs.getAs<nonloc::PointerToMember>()) {
1108 if (PTMSV->isNullMemberPointer())
1109 return UndefinedVal();
1110 if (const FieldDecl *FD = PTMSV->getDeclAs<FieldDecl>()) {
1111 SVal Result = lhs;
1112
1113 for (const auto &I : *PTMSV)
1114 Result = StateMgr.getStoreManager().evalDerivedToBase(
1115 Result, I->getType(),I->isVirtual());
1116 return state->getLValue(FD, Result);
1117 }
1118 }
1119
1120 return rhs;
1121 }
1122
1123 assert(!BinaryOperator::isComparisonOp(op) &&
1124 "arguments to comparison ops must be of the same type");
1125
1126 // Special case: rhs is a zero constant.
1127 if (rhs.isZeroConstant())
1128 return lhs;
1129
1130 // Perserve the null pointer so that it can be found by the DerefChecker.
1131 if (lhs.isZeroConstant())
1132 return lhs;
1133
1134 // We are dealing with pointer arithmetic.
1135
1136 // Handle pointer arithmetic on constant values.
1137 if (Optional<nonloc::ConcreteInt> rhsInt = rhs.getAs<nonloc::ConcreteInt>()) {
1138 if (Optional<loc::ConcreteInt> lhsInt = lhs.getAs<loc::ConcreteInt>()) {
1139 const llvm::APSInt &leftI = lhsInt->getValue();
1140 assert(leftI.isUnsigned());
1141 llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true);
1142
1143 // Convert the bitwidth of rightI. This should deal with overflow
1144 // since we are dealing with concrete values.
1145 rightI = rightI.extOrTrunc(leftI.getBitWidth());
1146
1147 // Offset the increment by the pointer size.
1148 llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true);
1149 QualType pointeeType = resultTy->getPointeeType();
1150 Multiplicand = getContext().getTypeSizeInChars(pointeeType).getQuantity();
1151 rightI *= Multiplicand;
1152
1153 // Compute the adjusted pointer.
1154 switch (op) {
1155 case BO_Add:
1156 rightI = leftI + rightI;
1157 break;
1158 case BO_Sub:
1159 rightI = leftI - rightI;
1160 break;
1161 default:
1162 llvm_unreachable("Invalid pointer arithmetic operation");
1163 }
1164 return loc::ConcreteInt(getBasicValueFactory().getValue(rightI));
1165 }
1166 }
1167
1168 // Handle cases where 'lhs' is a region.
1169 if (const MemRegion *region = lhs.getAsRegion()) {
1170 rhs = convertToArrayIndex(rhs).castAs<NonLoc>();
1171 SVal index = UnknownVal();
1172 const SubRegion *superR = nullptr;
1173 // We need to know the type of the pointer in order to add an integer to it.
1174 // Depending on the type, different amount of bytes is added.
1175 QualType elementType;
1176
1177 if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) {
1178 assert(op == BO_Add || op == BO_Sub);
1179 index = evalBinOpNN(state, op, elemReg->getIndex(), rhs,
1180 getArrayIndexType());
1181 superR = cast<SubRegion>(elemReg->getSuperRegion());
1182 elementType = elemReg->getElementType();
1183 }
1184 else if (isa<SubRegion>(region)) {
1185 assert(op == BO_Add || op == BO_Sub);
1186 index = (op == BO_Add) ? rhs : evalMinus(rhs);
1187 superR = cast<SubRegion>(region);
1188 // TODO: Is this actually reliable? Maybe improving our MemRegion
1189 // hierarchy to provide typed regions for all non-void pointers would be
1190 // better. For instance, we cannot extend this towards LocAsInteger
1191 // operations, where result type of the expression is integer.
1192 if (resultTy->isAnyPointerType())
1193 elementType = resultTy->getPointeeType();
1194 }
1195
1196 // Represent arithmetic on void pointers as arithmetic on char pointers.
1197 // It is fine when a TypedValueRegion of char value type represents
1198 // a void pointer. Note that arithmetic on void pointers is a GCC extension.
1199 if (elementType->isVoidType())
1200 elementType = getContext().CharTy;
1201
1202 if (Optional<NonLoc> indexV = index.getAs<NonLoc>()) {
1203 return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
1204 superR, getContext()));
1205 }
1206 }
1207 return UnknownVal();
1208 }
1209
1210 const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
1211 SVal V) {
1212 V = simplifySVal(state, V);
1213 if (V.isUnknownOrUndef())
1214 return nullptr;
1215
1216 if (Optional<loc::ConcreteInt> X = V.getAs<loc::ConcreteInt>())
1217 return &X->getValue();
1218
1219 if (Optional<nonloc::ConcreteInt> X = V.getAs<nonloc::ConcreteInt>())
1220 return &X->getValue();
1221
1222 if (SymbolRef Sym = V.getAsSymbol())
1223 return state->getConstraintManager().getSymVal(state, Sym);
1224
1225 // FIXME: Add support for SymExprs.
1226 return nullptr;
1227 }
1228
1229 SVal SimpleSValBuilder::simplifySVal(ProgramStateRef State, SVal V) {
1230 // For now, this function tries to constant-fold symbols inside a
1231 // nonloc::SymbolVal, and does nothing else. More simplifications should
1232 // be possible, such as constant-folding an index in an ElementRegion.
1233
1234 class Simplifier : public FullSValVisitor<Simplifier, SVal> {
1235 ProgramStateRef State;
1236 SValBuilder &SVB;
1237
1238 // Cache results for the lifetime of the Simplifier. Results change every
1239 // time new constraints are added to the program state, which is the whole
1240 // point of simplifying, and for that very reason it's pointless to maintain
1241 // the same cache for the duration of the whole analysis.
1242 llvm::DenseMap<SymbolRef, SVal> Cached;
1243
1244 static bool isUnchanged(SymbolRef Sym, SVal Val) {
1245 return Sym == Val.getAsSymbol();
1246 }
1247
1248 SVal cache(SymbolRef Sym, SVal V) {
1249 Cached[Sym] = V;
1250 return V;
1251 }
1252
1253 SVal skip(SymbolRef Sym) {
1254 return cache(Sym, SVB.makeSymbolVal(Sym));
1255 }
1256
1257 public:
1258 Simplifier(ProgramStateRef State)
1259 : State(State), SVB(State->getStateManager().getSValBuilder()) {}
1260
1261 SVal VisitSymbolData(const SymbolData *S) {
1262 // No cache here.
1263 if (const llvm::APSInt *I =
1264 SVB.getKnownValue(State, SVB.makeSymbolVal(S)))
1265 return Loc::isLocType(S->getType()) ? (SVal)SVB.makeIntLocVal(*I)
1266 : (SVal)SVB.makeIntVal(*I);
1267 return SVB.makeSymbolVal(S);
1268 }
1269
1270 // TODO: Support SymbolCast. Support IntSymExpr when/if we actually
1271 // start producing them.
1272
1273 SVal VisitSymIntExpr(const SymIntExpr *S) {
1274 auto I = Cached.find(S);
1275 if (I != Cached.end())
1276 return I->second;
1277
1278 SVal LHS = Visit(S->getLHS());
1279 if (isUnchanged(S->getLHS(), LHS))
1280 return skip(S);
1281
1282 SVal RHS;
1283 // By looking at the APSInt in the right-hand side of S, we cannot
1284 // figure out if it should be treated as a Loc or as a NonLoc.
1285 // So make our guess by recalling that we cannot multiply pointers
1286 // or compare a pointer to an integer.
1287 if (Loc::isLocType(S->getLHS()->getType()) &&
1288 BinaryOperator::isComparisonOp(S->getOpcode())) {
1289 // The usual conversion of $sym to &SymRegion{$sym}, as they have
1290 // the same meaning for Loc-type symbols, but the latter form
1291 // is preferred in SVal computations for being Loc itself.
1292 if (SymbolRef Sym = LHS.getAsSymbol()) {
1293 assert(Loc::isLocType(Sym->getType()));
1294 LHS = SVB.makeLoc(Sym);
1295 }
1296 RHS = SVB.makeIntLocVal(S->getRHS());
1297 } else {
1298 RHS = SVB.makeIntVal(S->getRHS());
1299 }
1300
1301 return cache(
1302 S, SVB.evalBinOp(State, S->getOpcode(), LHS, RHS, S->getType()));
1303 }
1304
1305 SVal VisitSymSymExpr(const SymSymExpr *S) {
1306 auto I = Cached.find(S);
1307 if (I != Cached.end())
1308 return I->second;
1309
1310 // For now don't try to simplify mixed Loc/NonLoc expressions
1311 // because they often appear from LocAsInteger operations
1312 // and we don't know how to combine a LocAsInteger
1313 // with a concrete value.
1314 if (Loc::isLocType(S->getLHS()->getType()) !=
1315 Loc::isLocType(S->getRHS()->getType()))
1316 return skip(S);
1317
1318 SVal LHS = Visit(S->getLHS());
1319 SVal RHS = Visit(S->getRHS());
1320 if (isUnchanged(S->getLHS(), LHS) && isUnchanged(S->getRHS(), RHS))
1321 return skip(S);
1322
1323 return cache(
1324 S, SVB.evalBinOp(State, S->getOpcode(), LHS, RHS, S->getType()));
1325 }
1326
1327 SVal VisitSymExpr(SymbolRef S) { return nonloc::SymbolVal(S); }
1328
1329 SVal VisitMemRegion(const MemRegion *R) { return loc::MemRegionVal(R); }
1330
1331 SVal VisitNonLocSymbolVal(nonloc::SymbolVal V) {
1332 // Simplification is much more costly than computing complexity.
1333 // For high complexity, it may be not worth it.
1334 return Visit(V.getSymbol());
1335 }
1336
1337 SVal VisitSVal(SVal V) { return V; }
1338 };
1339
1340 // A crude way of preventing this function from calling itself from evalBinOp.
1341 static bool isReentering = false;
1342 if (isReentering)
1343 return V;
1344
1345 isReentering = true;
1346 SVal SimplifiedV = Simplifier(State).Visit(V);
1347 isReentering = false;
1348
1349 return SimplifiedV;
1350 }
ento
clang::FunctionDecl
Represents a function declaration or definition.
Definition: Decl.h:1783
clang::if
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
Definition: RecursiveASTVisitor.h:1045
clang::ASTContext::VoidPtrTy
CanQualType VoidPtrTy
Definition: ASTContext.h:1044
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:654
clang::ento::MemRegion
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
SubEngine.h
clang::ento::createSimpleSValBuilder
SValBuilder * createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context, ProgramStateManager &stateMgr)
Definition: SimpleSValBuilder.cpp:58
clang::Type::getPointeeType
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:557
isWithinConstantOverflowBounds
static bool isWithinConstantOverflowBounds(SymbolRef Sym, ProgramStateRef State)
Definition: SimpleSValBuilder.cpp:330
clang::ento::ProgramStateRef
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Definition: ProgramState_Fwd.h:37
clang::FieldDecl::getParent
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2918
clang::ento::nonloc::ConcreteInt
Value representing integer constant.
Definition: SVals.h:379
clang::ento::UndefinedVal
Definition: SVals.h:217
clang::BinaryOperator::isAdditiveOp
bool isAdditiveOp() const
Definition: Expr.h:3511
clang::ento::SymExpr
Symbolic value.
Definition: SymExpr.h:29
clang::RecordDecl
Represents a struct/union/class.
Definition: Decl.h:3748
clang::ento::MemRegion::getSymbolicBase
const SymbolicRegion * getSymbolicBase() const
If this is a symbolic region, returns the region.
Definition: MemRegion.cpp:1219
doRearrangeUnchecked
static NonLoc doRearrangeUnchecked(ProgramStateRef State, BinaryOperator::Opcode Op, SymbolRef LSym, llvm::APSInt LInt, SymbolRef RSym, llvm::APSInt RInt)
Definition: SimpleSValBuilder.cpp:371
clang::ento::SymbolRef
const SymExpr * SymbolRef
Definition: SymExpr.h:110
clang::BinaryOperator::reverseComparisonOp
static Opcode reverseComparisonOp(Opcode Opc)
Definition: Expr.h:3543
clang::ASTContext
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:168
isInRelation
static bool isInRelation(BinaryOperator::Opcode Rel, SymbolRef Sym, llvm::APSInt Bound, ProgramStateRef State)
Definition: SimpleSValBuilder.cpp:313
llvm::Optional
Definition: LLVM.h:37
clang::ento::nonloc::PointerToMember
Value representing pointer-to-member.
Definition: SVals.h:524
State
LineState State
Definition: UnwrappedLineFormatter.cpp:932
clang::RecordDecl::fields
field_range fields() const
Definition: Decl.h:3963
clang::FieldDecl
Represents a member of a struct/union/class.
Definition: Decl.h:2729
APSIntType.h
clang::Type::isReferenceType
bool isReferenceType() const
Definition: Type.h:6516
max
__DEVICE__ int max(int __a, int __b)
Definition: __clang_cuda_device_functions.h:1628
clang::CodeGen::state
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
Definition: CGOpenMPRuntime.h:802
clang::ento::SVal::getAsSymbolicExpression
const SymExpr * getAsSymbolicExpression() const
getAsSymbolicExpression - If this Sval wraps a symbolic expression then return that expression...
Definition: SVals.cpp:137
clang::Type::isIntegralOrEnumerationType
bool isIntegralOrEnumerationType() const
Determine whether this type is an integral or enumeration type.
Definition: Type.h:6881
clang::ento::Loc::isLocType
static bool isLocType(QualType T)
Definition: SVals.h:329
clang::BinaryOperatorKind
BinaryOperatorKind
Definition: OperationKinds.h:25
shouldRearrange
static bool shouldRearrange(ProgramStateRef State, BinaryOperator::Opcode Op, SymbolRef Sym, llvm::APSInt Int, QualType Ty)
Definition: SimpleSValBuilder.cpp:438
clang::ento::SymExpr::getType
virtual QualType getType() const =0
decomposeSymbol
static std::pair< SymbolRef, llvm::APSInt > decomposeSymbol(SymbolRef Sym, BasicValueFactory &BV)
Definition: SimpleSValBuilder.cpp:356
clang::BinaryOperator::negateComparisonOp
static Opcode negateComparisonOp(Opcode Opc)
Definition: Expr.h:3530
clang::ento::SVal::getSubKind
unsigned getSubKind() const
Definition: SVals.h:119
clang::ento::SymbolicRegion
SymbolicRegion - A special, "non-concrete" region.
Definition: MemRegion.h:764
V
#define V(N, I)
Definition: ASTContext.h:2941
ProgramState.h
AnalysisManager.h
getValue
static SVal getValue(SVal val, SValBuilder &svalBuilder)
Definition: ArrayBoundCheckerV2.cpp:277
clang::ento::NonLoc
Definition: SVals.h:298
clang::Type::isUnionType
bool isUnionType() const
Definition: Type.cpp:527
clang::QualType::isNull
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:719
clang::ento::SVal::getAs
Optional< T > getAs() const
Convert to the specified SVal type, returning None if this SVal is not of the desired type...
Definition: SVals.h:111
clang::BinaryOperator::isComparisonOp
bool isComparisonOp() const
Definition: Expr.h:3525
clang::ento::loc::ConcreteInt
Definition: SVals.h:640
clang::prec::PointerToMember
Definition: OperatorPrecedence.h:42
clang::ento::Loc
Definition: SVals.h:320
clang::ento::FunctionCodeRegion
FunctionCodeRegion - A region that represents code texts of function.
Definition: MemRegion.h:581
APSInt
llvm::APSInt APSInt
Definition: ByteCodeEmitter.cpp:18
clang::ento::SVal
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:75
clang::Type::isSignedIntegerOrEnumerationType
bool isSignedIntegerOrEnumerationType() const
Determines whether this is an integer type that is signed or an enumeration types whose underlying ty...
Definition: Type.cpp:1944
clang::Type::isAnyPointerType
bool isAnyPointerType() const
Definition: Type.h:6508
clang::ento::ProgramStateManager
Definition: ProgramState.h:456
SValBuilder.h
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
clang::BinaryOperator::isShiftOp
bool isShiftOp() const
Definition: Expr.h:3513
clang::Type::isBooleanType
bool isBooleanType() const
Definition: Type.h:6894
clang::ento::SValBuilder
Definition: SValBuilder.h:52
clang::ento::nonloc::SymbolVal
Represents symbolic expression that isn&#39;t a location.
Definition: SVals.h:349
SValVisitor.h
clang::ASTContext::getIntWidth
unsigned getIntWidth(QualType T) const
Definition: ASTContext.cpp:9465
clang::ento::SVal::castAs
T castAs() const
Convert to the specified SVal type, asserting that this SVal is of the desired type.
Definition: SVals.h:103
clang::ASTContext::getTypeSize
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2104
clang::ento::nonloc::LocAsInteger
Definition: SVals.h:410
clang::ASTContext::getCanonicalType
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2305
X
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:14780
clang::Type::isVoidType
bool isVoidType() const
Definition: Type.h:6777
tryRearrange
static Optional< NonLoc > tryRearrange(ProgramStateRef State, BinaryOperator::Opcode Op, NonLoc Lhs, NonLoc Rhs, QualType ResultTy)
Definition: SimpleSValBuilder.cpp:446
clang::ento::UnknownVal
Definition: SVals.h:250
clang::ento::loc::MemRegionVal
Definition: SVals.h:598
evalBinOpFieldRegionFieldRegion
static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR, const FieldRegion *RightFR, BinaryOperator::Opcode op, QualType resultTy, SimpleSValBuilder &SVB)
Definition: SimpleSValBuilder.cpp:774