1 files changed, 9 insertions, 1 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
index 290a0351792..8544f98b948 100644
--- a/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
@@ -100,17 +100,25 @@ bool BuiltinFunctionChecker::evalCall(const CallExpr *CE,
   case Builtin::BI__builtin_constant_p: {
     // This must be resolvable at compile time, so we defer to the constant
     // evaluator for a value.
+    SValBuilder &SVB = C.getSValBuilder();
     SVal V = UnknownVal();
     Expr::EvalResult EVResult;
     if (CE->EvaluateAsInt(EVResult, C.getASTContext(), Expr::SE_NoSideEffects)) {
       // Make sure the result has the correct type.
       llvm::APSInt Result = EVResult.Val.getInt();
-      SValBuilder &SVB = C.getSValBuilder();
       BasicValueFactory &BVF = SVB.getBasicValueFactory();
       BVF.getAPSIntType(CE->getType()).apply(Result);
       V = SVB.makeIntVal(Result);
     }
 
+    if (FD->getBuiltinID() == Builtin::BI__builtin_constant_p) {
+      // If we didn't manage to figure out if the value is constant or not,
+      // it is safe to assume that it's not constant and unsafe to assume
+      // that it's constant.
+      if (V.isUnknown())
+        V = SVB.makeIntVal(0, CE->getType());
+    }
+
     C.addTransition(state->BindExpr(CE, LCtx, V));
     return true;
   }