[llvm] 052d588 - [Support] Properly zero initialize CPU set when querying affinity (#142924)

[via llvm-commits]

Author: Christian Ulmann
Date: 2025-06-06T11:24:46+02:00
New Revision: 052d5889f871f792def285c92bd91182d07789cd

URL: https://github.com/llvm/llvm-project/commit/052d5889f871f792def285c92bd91182d07789cd
DIFF: https://github.com/llvm/llvm-project/commit/052d5889f871f792def285c92bd91182d07789cd.diff

LOG: [Support] Properly zero initialize CPU set when querying affinity (#142924)

This commit resolves a potential issue of working with uninitialized
memory when querying the CPU's affinity. The man page of
`sched_getaffinity` does not guarantee that the memory will be fully
overwritten, so this change should ensure that issues are avoided.

Added: 
    

Modified: 
    llvm/lib/Support/Unix/Threading.inc

Removed: 
    


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diff  --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
index 742660d5bea75..562971aae32fd 100644
--- a/llvm/lib/Support/Unix/Threading.inc
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -318,6 +318,7 @@ static int computeHostNumHardwareThreads() {
     return CPU_COUNT(&mask);
 #elif defined(__linux__)
   cpu_set_t Set;
+  CPU_ZERO(&Set);
   if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
     return CPU_COUNT(&Set);
 #endif