Fix for PR15623 (corrected r290413 reverted at 290415). The patch eliminates unwanted ProgramState checker data propagation from an operand of the logical operation to operation result.

The patch also simplifies an assume of a constraint of the form: "(exp comparison_op expr) != 0" to true into an assume of "exp comparison_op expr" to true. (And similarly, an assume of the form "(exp comparison_op expr) == 0" to true as an assume of exp comparison_op expr to false.) which improves precision overall.
https://reviews.llvm.org/D22862

llvm-svn: 290505

1 files changed, 7 insertions, 17 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
index 217d2c65903..89fab1d56af 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -666,23 +666,13 @@ void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
     if (RHSVal.isUndef()) {
       X = RHSVal;
     } else {
-      DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>();
-      ProgramStateRef StTrue, StFalse;
-      std::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());
-      }
+      // We evaluate "RHSVal != 0" expression which result in 0 if the value is
+      // known to be false, 1 if the value is known to be true and a new symbol
+      // when the assumption is unknown.
+      nonloc::ConcreteInt Zero(getBasicVals().getValue(0, B->getType()));
+      X = evalBinOp(N->getState(), BO_NE, 
+                    svalBuilder.evalCast(RHSVal, B->getType(), RHS->getType()),
+                    Zero, B->getType());
     }
   }
   Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));