The discussion made me realize I don't need all sub-expressions to be live,
but only the logical expression tree leafs, so I changed LiveVariables
accordingly.
I also realized that non-leaf expressions are never removed from the live
set, unless I am missing something. So, basically, once a non-leaf expression
in the temporary destructor branch terminator is marked as live, it will stay
live forever. I didn't want to address this now, as this was always the case
and is not introduced by this change. I'll postpone that to an another patch.
Hi jordan_rose,
http://llvm-reviews.chandlerc.com/D1340
CHANGE SINCE LAST DIFF
http://llvm-reviews.chandlerc.com/D1340?vs=3382&id=3519#toc
Files:
lib/Analysis/LiveVariables.cpp
lib/StaticAnalyzer/Core/ExprEngine.cpp
lib/StaticAnalyzer/Core/ExprEngineC.cpp
test/Analysis/logical-ops.c
Index: lib/Analysis/LiveVariables.cpp
===================================================================
--- lib/Analysis/LiveVariables.cpp
+++ lib/Analysis/LiveVariables.cpp
@@ -212,6 +212,8 @@
LiveVariables::LivenessValues &val;
LiveVariables::Observer *observer;
const CFGBlock *currentBlock;
+
+ void MarkLogicalExprLeafs(const Expr *E);
public:
TransferFunctions(LiveVariablesImpl &im,
LiveVariables::LivenessValues &Val,
@@ -368,7 +370,23 @@
if (observer)
observer->observerKill(DR);
}
+ } else if (B->isLogicalOp()) {
+ // Leaf expressions in the logical operator tree are live until we reach the
+ // outermost logical operator. Static analyzer relies on this behaviour.
+ MarkLogicalExprLeafs(B->getLHS()->IgnoreParens());
+ MarkLogicalExprLeafs(B->getRHS()->IgnoreParens());
+ }
+}
+
+void TransferFunctions::MarkLogicalExprLeafs(const Expr *E) {
+ const BinaryOperator *B = dyn_cast<BinaryOperator>(E);
+ if (!B || !B->isLogicalOp()) {
+ val.liveStmts = LV.SSetFact.add(val.liveStmts, E);
+ return;
}
+
+ MarkLogicalExprLeafs(B->getLHS()->IgnoreParens());
+ MarkLogicalExprLeafs(B->getRHS()->IgnoreParens());
}
void TransferFunctions::VisitBlockExpr(BlockExpr *BE) {
Index: lib/StaticAnalyzer/Core/ExprEngine.cpp
===================================================================
--- lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1391,16 +1391,21 @@
}
}
+ ProgramStateRef StTrue, StFalse;
+
// If the condition is still unknown, give up.
if (X.isUnknownOrUndef()) {
- builder.generateNode(PrevState, true, PredI);
- builder.generateNode(PrevState, false, PredI);
+ SValBuilder &SVB = PrevState->getStateManager().getSValBuilder();
+
+ StTrue = PrevState->BindExpr(Condition, BldCtx.LC, SVB.makeTruthVal(true));
+ StFalse = PrevState->BindExpr(Condition, BldCtx.LC, SVB.makeTruthVal(false));
+
+ builder.generateNode(StTrue, true, PredI);
+ builder.generateNode(StFalse, false, PredI);
continue;
}
DefinedSVal V = X.castAs<DefinedSVal>();
-
- ProgramStateRef StTrue, StFalse;
tie(StTrue, StFalse) = PrevState->assume(V);
// Process the true branch.
Index: lib/StaticAnalyzer/Core/ExprEngineC.cpp
===================================================================
--- lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -501,72 +501,64 @@
}
}
+static ProgramStateRef EvaluateLogicalExpression(const Expr *E,
+ const LocationContext *LC,
+ ProgramStateRef State) {
+ SVal X = State->getSVal(E, LC);
+ if (! X.isUnknown())
+ return State;
+
+ const BinaryOperator *B = cast_or_null<BinaryOperator>(E->IgnoreParens());
+ if (!B || (B->getOpcode() != BO_LAnd && B->getOpcode() != BO_LOr))
+ return State;
+
+ State = EvaluateLogicalExpression(B->getLHS(), LC, State);
+ X = State->getSVal(B->getLHS(), LC);
+ QualType XType = B->getLHS()->getType();
+ assert(!X.isUnknownOrUndef() && "Value should have already been computed.");
+
+ ProgramStateRef StTrue, StFalse;
+ llvm::tie(StTrue, StFalse) = State->assume(X.castAs<DefinedOrUnknownSVal>());
+
+ assert(!StTrue != !StFalse && "Value should be evaluate to true or false.");
+ if(!StFalse == (B->getOpcode() == BO_LAnd)) {
+ // LHS not sufficient, we need to check RHS as well
+ State = EvaluateLogicalExpression(B->getRHS(), LC, State);
+ X = State->getSVal(B->getRHS(), LC);
+ XType = B->getRHS()->getType();
+ }
+
+ SValBuilder &SVB = State->getStateManager().getSValBuilder();
+ return State->BindExpr(E, LC, SVB.evalCast(X, B->getType(), XType));
+}
+
void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
ExplodedNodeSet &Dst) {
assert(B->getOpcode() == BO_LAnd ||
B->getOpcode() == BO_LOr);
StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
ProgramStateRef state = Pred->getState();
- ExplodedNode *N = Pred;
- while (!N->getLocation().getAs<BlockEntrance>()) {
- ProgramPoint P = N->getLocation();
- assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>());
- (void) P;
- assert(N->pred_size() == 1);
- N = *N->pred_begin();
- }
- assert(N->pred_size() == 1);
- N = *N->pred_begin();
- BlockEdge BE = N->getLocation().castAs<BlockEdge>();
- SVal X;
-
- // Determine the value of the expression by introspecting how we
- // got this location in the CFG. This requires looking at the previous
- // block we were in and what kind of control-flow transfer was involved.
- const CFGBlock *SrcBlock = BE.getSrc();
- // The only terminator (if there is one) that makes sense is a logical op.
- CFGTerminator T = SrcBlock->getTerminator();
- if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) {
- (void) Term;
- assert(Term->isLogicalOp());
- assert(SrcBlock->succ_size() == 2);
- // Did we take the true or false branch?
- unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0;
- X = svalBuilder.makeIntVal(constant, B->getType());
- }
- else {
- // If there is no terminator, by construction the last statement
- // in SrcBlock is the value of the enclosing expression.
- // However, we still need to constrain that value to be 0 or 1.
- assert(!SrcBlock->empty());
- CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>();
- const Expr *RHS = cast<Expr>(Elem.getStmt());
- SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext());
-
- if (RHSVal.isUndef()) {
- X = RHSVal;
- } else {
- DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>();
- ProgramStateRef StTrue, StFalse;
- llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS);
- if (StTrue) {
- if (StFalse) {
- // We can't constrain the value to 0 or 1.
- // The best we can do is a cast.
- X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType());
- } else {
- // The value is known to be true.
- X = getSValBuilder().makeIntVal(1, B->getType());
- }
- } else {
- // The value is known to be false.
- assert(StFalse && "Infeasible path!");
- X = getSValBuilder().makeIntVal(0, B->getType());
+ state = EvaluateLogicalExpression(B, Pred->getLocationContext(), state);
+ SVal X = state->getSVal(B, Pred->getLocationContext());
+
+ if (!X.isUndef()) {
+ DefinedOrUnknownSVal DefinedRHS = X.castAs<DefinedOrUnknownSVal>();
+ ProgramStateRef StTrue, StFalse;
+ llvm::tie(StTrue, StFalse) = state->assume(DefinedRHS);
+ if (StTrue) {
+ if (!StFalse) {
+ // The value is known to be true.
+ X = getSValBuilder().makeIntVal(1, B->getType());
}
+ } else {
+ // The value is known to be false.
+ assert(StFalse && "Infeasible path!");
+ X = getSValBuilder().makeIntVal(0, B->getType());
}
}
+
Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));
}
Index: test/Analysis/logical-ops.c
===================================================================
--- test/Analysis/logical-ops.c
+++ test/Analysis/logical-ops.c
@@ -25,3 +25,10 @@
return 1;
return 0;
}
+
+// this used to crash the analyzer
+int between(char *x) {
+ extern char start[];
+ extern char end[];
+ return x >= start && x < end;
+}
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