[analyzer] Resolve the crash in ReturnUndefChecker
By making sure the returned value from getKnownSVal is consistent with
the value used inside expression engine.
PR38427
Differential Revision: https://reviews.llvm.org/D51252
llvm-svn: 340965
diff --git a/clang/lib/StaticAnalyzer/Checkers/UndefResultChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UndefResultChecker.cpp
index bbf3215..47faf69 100644
--- a/clang/lib/StaticAnalyzer/Checkers/UndefResultChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/UndefResultChecker.cpp
@@ -69,6 +69,7 @@
ProgramStateRef State = C.getState();
const llvm::APSInt *LHS = SB.getKnownValue(State, C.getSVal(B->getLHS()));
const llvm::APSInt *RHS = SB.getKnownValue(State, C.getSVal(B->getRHS()));
+ assert(LHS && RHS && "Values unknown, inconsistent state");
return (unsigned)RHS->getZExtValue() > LHS->countLeadingZeros();
}