[compiler-rt] [compiler-rt] [fuzzer] Skip trying to set the thread name on MinGW (PR #115167)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo created https://github.com/llvm/llvm-project/pull/115167

Since b4130bee6bfd34d8045f02fc9f951bcb5db9d85c, we check for _LIBCPP_HAS_THREAD_API_PTHREAD to decide between using SetThreadDescription or pthread_setname_np for setting the thread name.

c6f3b7bcd0596d30f8dabecdfb9e44f9a07b6e4c changed how libcxx defines their configuration macros - now they are always defined, but defined to 0 or 1, while they previously were either defined or undefined.

As these libcxx defines used to be defined to an empty string (rather than expanding to 1) if enabled, we can't easily produce an expression that works both with older and newer libcxx. Additionally, these defines are libcxx internal config macros that aren't a detail that isn't supported and isn't meant to be relied upon.

Simply skip trying to set thread name on MinGW as we can't easily know which kind of thread native handle we have. Setting the thread name is only a nice to have, quality of life improvement - things should work the same even without it.

Additionally, libfuzzer isn't generally usable on MinGW targets yet (Clang doesn't include it in the getSupportedSanitizers() method for the MinGW target), so this shouldn't make any difference in practice anyway.

>From c21d120f64d8f70b028a41321ede7364f32e055f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin at martin.st>
Date: Wed, 6 Nov 2024 14:02:16 +0200
Subject: [PATCH] [compiler-rt] [fuzzer] Skip trying to set the thread name on
 MinGW

Since b4130bee6bfd34d8045f02fc9f951bcb5db9d85c, we check for
_LIBCPP_HAS_THREAD_API_PTHREAD to decide between using
SetThreadDescription or pthread_setname_np for setting the thread
name.

c6f3b7bcd0596d30f8dabecdfb9e44f9a07b6e4c changed how libcxx
defines their configuration macros - now they are always defined,
but defined to 0 or 1, while they previously were either defined
or undefined.

As these libcxx defines used to be defined to an empty string
(rather than expanding to 1) if enabled, we can't easily produce
an expression that works both with older and newer libcxx.
Additionally, these defines are libcxx internal config macros
that aren't a detail that isn't supported and isn't meant to be
relied upon.

Simply skip trying to set thread name on MinGW as we can't easily
know which kind of thread native handle we have. Setting the thread
name is only a nice to have, quality of life improvement - things
should work the same even without it.

Additionally, libfuzzer isn't generally usable on MinGW targets
yet (Clang doesn't include it in the getSupportedSanitizers()
method for the MinGW target), so this shouldn't make any difference
in practice anyway.
---
 compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp b/compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp
index 37aecae7237ae9..2db2ea98d5c4f9 100644
--- a/compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp
@@ -239,10 +239,11 @@ size_t PageSize() {
 }
 
 void SetThreadName(std::thread &thread, const std::string &name) {
-#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD) ||                                 \
-    defined(_GLIBCXX_GCC_GTHR_POSIX_H)
-  (void)pthread_setname_np(thread.native_handle(), name.c_str());
-#else
+#ifndef __MINGW32__
+  // Not setting the thread name in MinGW environments. MinGW C++ standard
+  // libraries can either use native Windows threads or pthreads, so we
+  // don't know with certainty what kind of thread handle we're getting
+  // from thread.native_handle() here.
   typedef HRESULT(WINAPI * proc)(HANDLE, PCWSTR);
   HMODULE kbase = GetModuleHandleA("KernelBase.dll");
   proc ThreadNameProc = reinterpret_cast<proc>(