[clang] [analyzer] Model overflow builtins (PR #102602)

[Balazs Benics via cfe-commits]

================
@@ -50,6 +101,44 @@ class BuiltinFunctionChecker : public Checker<eval::Call> {
 
 } // namespace
 
+void BuiltinFunctionChecker::HandleOverflowBuiltin(const CallEvent &Call,
+                                                   CheckerContext &C,
+                                                   BinaryOperator::Opcode Op,
+                                                   QualType ResultType) const {
+  // All __builtin_*_overflow functions take 3 argumets.
+  assert(Call.getNumArgs() == 3);
+
+  ProgramStateRef State = C.getState();
+  SValBuilder &SVB = C.getSValBuilder();
+  const Expr *CE = Call.getOriginExpr();
+
+  SVal Arg1 = Call.getArgSVal(0);
+  SVal Arg2 = Call.getArgSVal(1);
+
+  SVal RetVal = SVB.evalBinOp(State, Op, Arg1, Arg2, ResultType);
+
+  // TODO: Handle overflows with values that known to overflow. Like INT_MAX + 1
+  // should not produce state for non-overflow case and threat it as
----------------
steakhal wrote:

I thought the ConstraintAssignor does the decomposition of the SymSymExpr and tracks the potential value range. It's probably somewhat limited though.

https://github.com/llvm/llvm-project/pull/102602