Author: Valeriy Savchenko Date: 2021-06-11T12:49:03+03:00 New Revision: 967c06b3e95ba776fb06ad0ea5aa699cf2e1b59a
URL: https://github.com/llvm/llvm-project/commit/967c06b3e95ba776fb06ad0ea5aa699cf2e1b59a DIFF: https://github.com/llvm/llvm-project/commit/967c06b3e95ba776fb06ad0ea5aa699cf2e1b59a.diff LOG: [analyzer] Reimplement trackExpressionValue as ExpressionHandler This commit moves trackExpressionValue into the Tracker interface as DefaultExpressionHandler. It still can be split into smaller handlers, but that can be a future change. Additionally, this commit doesn't remove the original trackExpressionValue interface, so it's not too big. One of the next commits will address it. Differential Revision: https://reviews.llvm.org/D103616 Added: Modified: clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp Removed: ################################################################################ diff --git a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp index 9359a5fe80f1..2df3687f2bb4 100644 --- a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp +++ b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp @@ -2050,7 +2050,166 @@ static void trackRValueExpression(const ExplodedNode *InputNode, const Expr *E, // Tracker implementation //===----------------------------------------------------------------------===// +class DefaultExpressionHandler final : public ExpressionHandler { +public: + using ExpressionHandler::ExpressionHandler; + + Tracker::Result handle(const Expr *Inner, const ExplodedNode *InputNode, + const ExplodedNode *LVNode, + TrackingOptions Opts) override { + ProgramStateRef LVState = LVNode->getState(); + const StackFrameContext *SFC = LVNode->getStackFrame(); + PathSensitiveBugReport &Report = getParentTracker().getReport(); + Tracker::Result Result; + + // We only track expressions if we believe that they are important. Chances + // are good that control dependencies to the tracking point are also + // important because of this, let's explain why we believe control reached + // this point. + // TODO: Shouldn't we track control dependencies of every bug location, + // rather than only tracked expressions? + if (LVState->getAnalysisManager() + .getAnalyzerOptions() + .ShouldTrackConditions) { + Report.addVisitor<TrackControlDependencyCondBRVisitor>(InputNode); + Result.FoundSomethingToTrack = true; + } + + // The message send could be nil due to the receiver being nil. + // At this point in the path, the receiver should be live since we are at + // the message send expr. If it is nil, start tracking it. + if (const Expr *Receiver = + NilReceiverBRVisitor::getNilReceiver(Inner, LVNode)) + Result.combineWith(getParentTracker().track(Receiver, LVNode, Opts)); + + // Track the index if this is an array subscript. + if (const auto *Arr = dyn_cast<ArraySubscriptExpr>(Inner)) + Result.combineWith(getParentTracker().track( + Arr->getIdx(), LVNode, + {Opts.Kind, /*EnableNullFPSuppression*/ false})); + + // See if the expression we're interested refers to a variable. + // If so, we can track both its contents and constraints on its value. + if (ExplodedGraph::isInterestingLValueExpr(Inner)) { + SVal LVal = LVNode->getSVal(Inner); + + const MemRegion *RR = getLocationRegionIfReference(Inner, LVNode); + bool LVIsNull = LVState->isNull(LVal).isConstrainedTrue(); + + // If this is a C++ reference to a null pointer, we are tracking the + // pointer. In addition, we should find the store at which the reference + // got initialized. + if (RR && !LVIsNull) + Result.combineWith(getParentTracker().track(LVal, RR, Opts, SFC)); + + // In case of C++ references, we want to diff erentiate between a null + // reference and reference to null pointer. + // If the LVal is null, check if we are dealing with null reference. + // For those, we want to track the location of the reference. + const MemRegion *R = + (RR && LVIsNull) ? RR : LVNode->getSVal(Inner).getAsRegion(); + + if (R) { + + // Mark both the variable region and its contents as interesting. + SVal V = LVState->getRawSVal(loc::MemRegionVal(R)); + Report.addVisitor<NoStoreFuncVisitor>(cast<SubRegion>(R), Opts.Kind); + + // When we got here, we do have something to track, and we will + // interrupt. + Result.FoundSomethingToTrack = true; + Result.WasInterrupted = true; + + MacroNullReturnSuppressionVisitor::addMacroVisitorIfNecessary( + LVNode, R, Opts.EnableNullFPSuppression, Report, V); + + Report.markInteresting(V, Opts.Kind); + Report.addVisitor<UndefOrNullArgVisitor>(R); + + // If the contents are symbolic and null, find out when they became + // null. + if (V.getAsLocSymbol(/*IncludeBaseRegions=*/true)) + if (LVState->isNull(V).isConstrainedTrue()) + Report.addVisitor<TrackConstraintBRVisitor>(V.castAs<DefinedSVal>(), + false); + + // Add visitor, which will suppress inline defensive checks. + if (auto DV = V.getAs<DefinedSVal>()) + if (!DV->isZeroConstant() && Opts.EnableNullFPSuppression) + // Note that LVNode may be too late (i.e., too far from the + // InputNode) because the lvalue may have been computed before the + // inlined call was evaluated. InputNode may as well be too early + // here, because the symbol is already dead; this, however, is fine + // because we can still find the node in which it collapsed to null + // previously. + Report.addVisitor<SuppressInlineDefensiveChecksVisitor>(*DV, + InputNode); + + getParentTracker().track(V, R, Opts, SFC); + + return Result; + } + } + + // If the expression is not an "lvalue expression", we can still + // track the constraints on its contents. + SVal V = LVState->getSValAsScalarOrLoc(Inner, LVNode->getLocationContext()); + + ReturnVisitor::addVisitorIfNecessary( + LVNode, Inner, Report, Opts.EnableNullFPSuppression, Opts.Kind); + + // Is it a symbolic value? + if (auto L = V.getAs<loc::MemRegionVal>()) { + // FIXME: this is a hack for fixing a later crash when attempting to + // dereference a void* pointer. + // We should not try to dereference pointers at all when we don't care + // what is written inside the pointer. + bool CanDereference = true; + if (const auto *SR = L->getRegionAs<SymbolicRegion>()) { + if (SR->getSymbol()->getType()->getPointeeType()->isVoidType()) + CanDereference = false; + } else if (L->getRegionAs<AllocaRegion>()) + CanDereference = false; + + // At this point we are dealing with the region's LValue. + // However, if the rvalue is a symbolic region, we should track it as + // well. Try to use the correct type when looking up the value. + SVal RVal; + if (ExplodedGraph::isInterestingLValueExpr(Inner)) + RVal = LVState->getRawSVal(L.getValue(), Inner->getType()); + else if (CanDereference) + RVal = LVState->getSVal(L->getRegion()); + + if (CanDereference) { + Report.addVisitor<UndefOrNullArgVisitor>(L->getRegion()); + Result.FoundSomethingToTrack = true; + + if (auto KV = RVal.getAs<KnownSVal>()) + Result.combineWith( + getParentTracker().track(*KV, L->getRegion(), Opts, SFC)); + } + + const MemRegion *RegionRVal = RVal.getAsRegion(); + if (isa_and_nonnull<SymbolicRegion>(RegionRVal)) { + Report.markInteresting(RegionRVal, Opts.Kind); + Report.addVisitor<TrackConstraintBRVisitor>( + loc::MemRegionVal(RegionRVal), + /*assumption=*/false); + Result.FoundSomethingToTrack = true; + } + } + + if (Inner->isPRValue()) + // TODO: Incorporate as Handler + trackRValueExpression(LVNode, Inner, Report, Opts.Kind, + Opts.EnableNullFPSuppression); + + return Result; + } +}; + Tracker::Tracker(PathSensitiveBugReport &Report) : Report(Report) { + addHighPriorityHandler<DefaultExpressionHandler>(); // TODO: split trackExpressionValue and FindLastStoreBRVisitor into handlers // and add them here. } @@ -2078,7 +2237,11 @@ Tracker::Result Tracker::track(const Expr *E, const ExplodedNode *N, Tracker::Result Tracker::track(SVal V, const MemRegion *R, TrackingOptions Opts, const StackFrameContext *Origin) { - // TODO: support this operation after dismantling FindLastStoreBRVisitor + if (auto KV = V.getAs<KnownSVal>()) { + Report.addVisitor<FindLastStoreBRVisitor>( + *KV, R, Opts.EnableNullFPSuppression, Opts.Kind, Origin); + return {true}; + } return {}; } @@ -2098,148 +2261,9 @@ bool bugreporter::trackExpressionValue(const ExplodedNode *InputNode, PathSensitiveBugReport &report, bugreporter::TrackingKind TKind, bool EnableNullFPSuppression) { - - if (!E || !InputNode) - return false; - - const Expr *Inner = peelOffOuterExpr(E, InputNode); - const ExplodedNode *LVNode = findNodeForExpression(InputNode, Inner); - if (!LVNode) - return false; - - ProgramStateRef LVState = LVNode->getState(); - const StackFrameContext *SFC = LVNode->getStackFrame(); - - // We only track expressions if we believe that they are important. Chances - // are good that control dependencies to the tracking point are also important - // because of this, let's explain why we believe control reached this point. - // TODO: Shouldn't we track control dependencies of every bug location, rather - // than only tracked expressions? - if (LVState->getAnalysisManager().getAnalyzerOptions().ShouldTrackConditions) - report.addVisitor<TrackControlDependencyCondBRVisitor>(InputNode); - - // The message send could be nil due to the receiver being nil. - // At this point in the path, the receiver should be live since we are at the - // message send expr. If it is nil, start tracking it. - if (const Expr *Receiver = NilReceiverBRVisitor::getNilReceiver(Inner, LVNode)) - trackExpressionValue( - LVNode, Receiver, report, TKind, EnableNullFPSuppression); - - // Track the index if this is an array subscript. - if (const auto *Arr = dyn_cast<ArraySubscriptExpr>(Inner)) - trackExpressionValue( - LVNode, Arr->getIdx(), report, TKind, /*EnableNullFPSuppression*/false); - - // See if the expression we're interested refers to a variable. - // If so, we can track both its contents and constraints on its value. - if (ExplodedGraph::isInterestingLValueExpr(Inner)) { - SVal LVal = LVNode->getSVal(Inner); - - const MemRegion *RR = getLocationRegionIfReference(Inner, LVNode); - bool LVIsNull = LVState->isNull(LVal).isConstrainedTrue(); - - // If this is a C++ reference to a null pointer, we are tracking the - // pointer. In addition, we should find the store at which the reference - // got initialized. - if (RR && !LVIsNull) - if (auto KV = LVal.getAs<KnownSVal>()) - report.addVisitor<FindLastStoreBRVisitor>( - *KV, RR, EnableNullFPSuppression, TKind, SFC); - - // In case of C++ references, we want to diff erentiate between a null - // reference and reference to null pointer. - // If the LVal is null, check if we are dealing with null reference. - // For those, we want to track the location of the reference. - const MemRegion *R = (RR && LVIsNull) ? RR : - LVNode->getSVal(Inner).getAsRegion(); - - if (R) { - - // Mark both the variable region and its contents as interesting. - SVal V = LVState->getRawSVal(loc::MemRegionVal(R)); - report.addVisitor<NoStoreFuncVisitor>(cast<SubRegion>(R), TKind); - - MacroNullReturnSuppressionVisitor::addMacroVisitorIfNecessary( - LVNode, R, EnableNullFPSuppression, report, V); - - report.markInteresting(V, TKind); - report.addVisitor<UndefOrNullArgVisitor>(R); - - // If the contents are symbolic and null, find out when they became null. - if (V.getAsLocSymbol(/*IncludeBaseRegions=*/true)) - if (LVState->isNull(V).isConstrainedTrue()) - report.addVisitor<TrackConstraintBRVisitor>(V.castAs<DefinedSVal>(), - false); - - // Add visitor, which will suppress inline defensive checks. - if (auto DV = V.getAs<DefinedSVal>()) - if (!DV->isZeroConstant() && EnableNullFPSuppression) { - // Note that LVNode may be too late (i.e., too far from the InputNode) - // because the lvalue may have been computed before the inlined call - // was evaluated. InputNode may as well be too early here, because - // the symbol is already dead; this, however, is fine because we can - // still find the node in which it collapsed to null previously. - report.addVisitor<SuppressInlineDefensiveChecksVisitor>(*DV, - InputNode); - } - - if (auto KV = V.getAs<KnownSVal>()) - report.addVisitor<FindLastStoreBRVisitor>( - *KV, R, EnableNullFPSuppression, TKind, SFC); - return true; - } - } - - // If the expression is not an "lvalue expression", we can still - // track the constraints on its contents. - SVal V = LVState->getSValAsScalarOrLoc(Inner, LVNode->getLocationContext()); - - ReturnVisitor::addVisitorIfNecessary( - LVNode, Inner, report, EnableNullFPSuppression, TKind); - - // Is it a symbolic value? - if (auto L = V.getAs<loc::MemRegionVal>()) { - // FIXME: this is a hack for fixing a later crash when attempting to - // dereference a void* pointer. - // We should not try to dereference pointers at all when we don't care - // what is written inside the pointer. - bool CanDereference = true; - if (const auto *SR = L->getRegionAs<SymbolicRegion>()) { - if (SR->getSymbol()->getType()->getPointeeType()->isVoidType()) - CanDereference = false; - } else if (L->getRegionAs<AllocaRegion>()) - CanDereference = false; - - // At this point we are dealing with the region's LValue. - // However, if the rvalue is a symbolic region, we should track it as well. - // Try to use the correct type when looking up the value. - SVal RVal; - if (ExplodedGraph::isInterestingLValueExpr(Inner)) - RVal = LVState->getRawSVal(L.getValue(), Inner->getType()); - else if (CanDereference) - RVal = LVState->getSVal(L->getRegion()); - - if (CanDereference) { - report.addVisitor<UndefOrNullArgVisitor>(L->getRegion()); - - if (auto KV = RVal.getAs<KnownSVal>()) - report.addVisitor<FindLastStoreBRVisitor>( - *KV, L->getRegion(), EnableNullFPSuppression, TKind, SFC); - } - - const MemRegion *RegionRVal = RVal.getAsRegion(); - if (isa_and_nonnull<SymbolicRegion>(RegionRVal)) { - report.markInteresting(RegionRVal, TKind); - report.addVisitor<TrackConstraintBRVisitor>(loc::MemRegionVal(RegionRVal), - /*assumption=*/false); - } - } - - if (Inner->isPRValue()) - trackRValueExpression(LVNode, Inner, report, TKind, - EnableNullFPSuppression); - - return true; + return Tracker(report) + .track(E, InputNode, {TKind, EnableNullFPSuppression}) + .FoundSomethingToTrack; } //===----------------------------------------------------------------------===// _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
