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

[Florian Hahn via llvm-commits]

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@@ -838,11 +838,14 @@ OffsetSpan ObjectSizeOffsetVisitor::computeImpl(Value *V) {
 
   // We end up pointing on a location that's outside of the original object.
   if (ORT.knownBefore() && ORT.Before.isNegative()) {
-    // This is UB, and we'd rather return an empty location then.
+    // This means that we *may* be accessing memory before the allocation. It's
+    // unsure though, so bail out instead of returning a potentially misleading
+    // result.
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fhahn wrote:

```suggestion
    // This means that we *may* be accessing memory before the allocation. Conservatively return an unknown size.
```

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