[llvm] [llvm-profgen] Fix bogus trace check (PR #225569)

[Kunal Pathak via llvm-commits]

================
@@ -881,6 +880,15 @@ void PerfScriptReader::warnIfMissingMMap() {
   }
 }
 
+// The unwinder requires that LBR tip belong to the leaf frame.
+// External addresses are not checked.
+static bool isValidTrace(ProfiledBinary *Binary, uint64_t StackLeaf,
+                         uint64_t LBRLeaf) {
+  if (StackLeaf == ExternalAddr || LBRLeaf == ExternalAddr)
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kunalspathak wrote:

Got it. What if we return `false` if BOTH `StackLeaf` and `LBRLeaf` are `ExternalAddr`? Do you know if such cases also gets filtered out and hence no need to return `false` here?

```c++
if (StackLeaf == ExternalAddr && LBRLeaf == ExternalAddr)
    return false;
```

https://github.com/llvm/llvm-project/pull/225569