[llvm] [llvm] Bail out when meeting pointer with negative offset instead of … (PR #120424)

[Florian Hahn via llvm-commits]

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@@ -841,8 +841,7 @@ OffsetSpan ObjectSizeOffsetVisitor::computeImpl(Value *V) {
     // This is UB, and we'd rather return an empty location then.
     if (Options.EvalMode == ObjectSizeOpts::Mode::Min ||
         Options.EvalMode == ObjectSizeOpts::Mode::Max) {
-      ORT.Before = APInt::getZero(ORT.Before.getBitWidth());
-      ORT.After = APInt::getZero(ORT.Before.getBitWidth());
+      return ObjectSizeOffsetVisitor::unknown();
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fhahn wrote:

Is the comment above incorrect? IIUC the case  @mstorsjo shared doesn't count UB

https://github.com/llvm/llvm-project/pull/120424