[clang] [llvm] [BasicAA] Fix miscompilation with setjmp/longjmp due to missing longjmp re-entry paths in alias analysis (PR #212297)

[Antonio Frighetto via cfe-commits]

================
@@ -257,13 +257,29 @@ CaptureComponents EarliestEscapeAnalysis::getCapturesBefore(
       return isNotInCycle(I, &DT, LI, CI);
     }
 
-    return !isPotentiallyReachable(CaptureInst, I, nullptr, &DT, LI, CI);
+    if (isPotentiallyReachable(CaptureInst, I, nullptr, &DT, LI, CI))
+      return false;
+
+    // A `longjmp` may re-enter the function at any `returns_twice` call
+    // (e.g. `setjmp`), If the function contains such a call, conservatively
----------------
antoniofrighetto wrote:

```suggestion
    // (e.g. `setjmp`). If the function contains such a call, conservatively
```

https://github.com/llvm/llvm-project/pull/212297