[compiler-rt] [asan] Implement interception on AIX (PR #131870)

[Fangrui Song via llvm-commits]

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@@ -275,7 +285,12 @@ INTERCEPTOR(int, pthread_create, void *thread, void *attr,
 #    endif
     asanThreadArgRetval().Create(detached, {start_routine, arg}, [&]() -> uptr {
       result = REAL(pthread_create)(thread, attr, asan_thread_start, t);
+// AIX pthread_t is unsigned int.
+#    if SANITIZER_AIX
+      return result ? 0 : *(unsigned int *)(thread);
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MaskRay wrote:

prefer unsigned to unsigned int

https://github.com/llvm/llvm-project/pull/131870