================
@@ -420,6 +420,118 @@ AST_MATCHER(CXXConstructExpr,
isSafeSpanTwoParamConstruct) {
return false;
}
+class MaxValueEval : public RecursiveASTVisitor<MaxValueEval> {
+
+ std::vector<llvm::APInt> val;
+ ASTContext &Context;
+ llvm::APInt Max;
+ unsigned bit_width;
+
+public:
+ typedef RecursiveASTVisitor<MaxValueEval> VisitorBase;
+
+ explicit MaxValueEval(ASTContext &Ctx, const Expr *exp) : Context(Ctx) {
+ bit_width = Ctx.getIntWidth(exp->getType());
+ Max = llvm::APInt::getSignedMaxValue(bit_width);
+ val.clear();
+ }
+
+ bool findMatch(Expr *exp) {
+ TraverseStmt(exp);
+ return true;
+ }
+
+ bool VisitDeclRefExpr(DeclRefExpr *dre) {
+ val.push_back(Max);
+ return false;
+ }
+
+ bool VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
+ val.push_back(Max);
+ return false;
+ }
+
+ bool EvaluateExpression(Expr *exp) {
+ Expr::EvalResult EVResult;
+ if (exp->EvaluateAsInt(EVResult, Context)) {
+ llvm::APSInt Result = EVResult.Val.getInt();
+ val.push_back(Result);
+ return true;
+ }
+ return false;
+ }
+
+ bool VisitBinaryOperator(BinaryOperator *E) {
+
+ if (EvaluateExpression(E)) {
+ return false;
+ } else {
+ TraverseStmt(E->getLHS());
+ llvm::APInt LHS = val.back();
----------------
ziqingluo-90 wrote:
I think there is no guarantee of `val.size() > 0` here.
This expression will break it: `(unsigned long)"x" << 1`
I also tried `s.f << 1`. It doesn't crash because the DeclRefExpr `s` gets
visited and hence `val` is populated. But I guess such behavior is not what you
intended, because `val` should represent the approximation of `s.f` not `s`.
https://github.com/llvm/llvm-project/pull/112284
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