[analyzer] make peelOffOuterExpr in BugReporterVisitors recursively peel off select Exprs

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178685 91177308-0d34-0410-b5e6-96231b3b80d8

lib/StaticAnalyzer/Core/BugReporterVisitors.cpp

@@ -789,14 +789,13 @@ static const MemRegion *getLocationRegionIfReference(const Expr *E,
   return 0;
 }
 
-static const Expr *peelOffOuterExpr(const Stmt *S,
+static const Expr *peelOffOuterExpr(const Expr *Ex,
                                     const ExplodedNode *N) {
-  if (const Expr *Ex = dyn_cast<Expr>(S)) {
   Ex = Ex->IgnoreParenCasts();
   if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Ex))
-      return EWC->getSubExpr();
+    return peelOffOuterExpr(EWC->getSubExpr(), N);
   if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Ex))
-      return OVE->getSourceExpr();
+    return peelOffOuterExpr(OVE->getSourceExpr(), N);
 
   // Peel off the ternary operator.
   if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(Ex)) {
@@ -809,16 +808,14 @@ static const Expr *peelOffOuterExpr(const Stmt *S,
       ConditionTruthVal CondEvaluated = State->isNull(CondVal);
       if (CondEvaluated.isConstrained()) {
         if (CondEvaluated.isConstrainedTrue())
-            return CO->getFalseExpr();
+          return peelOffOuterExpr(CO->getFalseExpr(), N);
         else
-            return CO->getTrueExpr();
+          return peelOffOuterExpr(CO->getTrueExpr(), N);
       }
       N = N->getFirstPred();
     } while (N);
-      
   }
-  }
+  return Ex;
-  return 0;
 }
 
 bool bugreporter::trackNullOrUndefValue(const ExplodedNode *N,
@@ -828,8 +825,12 @@ bool bugreporter::trackNullOrUndefValue(const ExplodedNode *N,
   if (!S || !N)
     return false;
 
-  if (const Expr *Ex = peelOffOuterExpr(S, N))
+  if (const Expr *Ex = dyn_cast<Expr>(S)) {
-    S = Ex;
+    Ex = Ex->IgnoreParenCasts();
+    const Expr *PeeledEx = peelOffOuterExpr(Ex, N);
+    if (Ex != PeeledEx)
+      S = PeeledEx;
+  }
 
   const Expr *Inner = 0;
   if (const Expr *Ex = dyn_cast<Expr>(S)) {

test/Analysis/inlining/false-positive-suppression.c

@@ -240,4 +240,29 @@ int ternaryRetNull(char cond) {
 #endif
 }
 
+// Test suppression of nested conditional operators.
+int testConditionalOperatorSuppress(int x) {
+  return *(x ? getNull() : getPtr());
+#ifndef SUPPRESSED
+  // expected-warning@-2 {{Dereference of null pointer}}
+#endif
+}
+int testNestedConditionalOperatorSuppress(int x) {
+  return *(x ? (x ? getNull() : getPtr()) : getPtr());
+#ifndef SUPPRESSED
+  // expected-warning@-2 {{Dereference of null pointer}}
+#endif
+}
+int testConditionalOperator(int x) {
+  return *(x ? 0 : getPtr()); // expected-warning {{Dereference of null pointer}}
+}
+int testNestedConditionalOperator(int x) {
+  return *(x ? (x ? 0 : getPtr()) : getPtr()); // expected-warning {{Dereference of null pointer}}
+}
+
+// False Positve - we are unable to suppress this case because the condition is
+// float.
+int testConditionalOperatorSuppressFloatCond(float x) {
+  return *(x ? getNull() : getPtr()); // expected-warning {{Dereference of null pointer}}
+}