[llvm] Fix have pthread_getname for some system (PR #110854)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-support

Author: William Moses (wsmoses)

<details>
<summary>Changes</summary>

I'm on a system that has have_pthread_getname_np defined but set to 0. The correct behavior here is not to use the function, but presently the macros will attempt to use a non-existing function.

This previously worked before https://github.com/llvm/llvm-project/pull/106486/files

---
Full diff: https://github.com/llvm/llvm-project/pull/110854.diff


1 Files Affected:

- (modified) llvm/lib/Support/Unix/Threading.inc (+2-2) 


``````````diff
diff --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
index 0afd1d817f88e6..a354984cabb1ef 100644
--- a/llvm/lib/Support/Unix/Threading.inc
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -237,14 +237,14 @@ void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
   char Buffer[len] = {'\0'}; // FIXME: working around MSan false positive.
   if (0 == ::pthread_getname_np(::pthread_self(), Buffer, len))
     Name.append(Buffer, Buffer + strlen(Buffer));
-#elif defined(HAVE_PTHREAD_GET_NAME_NP)
+#elif defined(HAVE_PTHREAD_GET_NAME_NP) && HAVE_PTHREAD_GET_NAME_NP
   constexpr uint32_t len = get_max_thread_name_length_impl();
   char buf[len];
   ::pthread_get_name_np(::pthread_self(), buf, len);
 
   Name.append(buf, buf + strlen(buf));
 
-#elif defined(HAVE_PTHREAD_GETNAME_NP)
+#elif defined(HAVE_PTHREAD_GETNAME_NP) && HAVE_PTHREAD_GETNAME_NP
   constexpr uint32_t len = get_max_thread_name_length_impl();
   char buf[len];
   ::pthread_getname_np(::pthread_self(), buf, len);

``````````

</details>


https://github.com/llvm/llvm-project/pull/110854