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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@290505 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 1 deletions

diff --git a/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp b/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
index c5e0f9b862..0e512ff808 100644
--- a/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
+++ b/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
@@ -254,6 +254,19 @@ ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef State,
   assert(BinaryOperator::isComparisonOp(Op) &&
          "Non-comparison ops should be rewritten as comparisons to zero.");
 
+  SymbolRef Sym = LHS;
+
+  // Simplification: translate 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 into an assume of
+  // "exp comparison_op expr" to false.)
+  if (Int == 0 && (Op == BO_EQ || Op == BO_NE)) {
+    if (const BinarySymExpr *SE = dyn_cast<BinarySymExpr>(Sym))
+      if (BinaryOperator::isComparisonOp(SE->getOpcode()))
+        return assume(State, nonloc::SymbolVal(Sym), (Op == BO_NE ? true : false));
+  }
+
   // Get the type used for calculating wraparound.
   BasicValueFactory &BVF = getBasicVals();
   APSIntType WraparoundType = BVF.getAPSIntType(LHS->getType());
@@ -265,7 +278,6 @@ ProgramStateRef SimpleConstraintManager::assumeSymRel(ProgramStateRef State,
   // x < 4 has the solution [0, 3]. x+2 < 4 has the solution [0-2, 3-2], which
   // in modular arithmetic is [0, 1] U [UINT_MAX-1, UINT_MAX]. It's up to
   // the subclasses of SimpleConstraintManager to handle the adjustment.
-  SymbolRef Sym = LHS;
   llvm::APSInt Adjustment = WraparoundType.getZeroValue();
   computeAdjustment(Sym, Adjustment);