[llvm] e9b2131 - [Support] computeHostNumPhysicalCores: use sched_getaffinity for all non-Android Linux with no custom implementation

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-08-13T01:36:13-07:00
New Revision: e9b213131ae9c57f4f151d3206916676135b31b0

URL: https://github.com/llvm/llvm-project/commit/e9b213131ae9c57f4f151d3206916676135b31b0
DIFF: https://github.com/llvm/llvm-project/commit/e9b213131ae9c57f4f151d3206916676135b31b0.diff

LOG: [Support] computeHostNumPhysicalCores: use sched_getaffinity for all non-Android Linux with no custom implementation

Make the sched_getaffinity based implementation available to all architectures
(except s390x/x86 which have a custom implementation). The `CPU_ALLOC(2048)`
code supports all `CONFIG_NR_CPUS` values in Linux kernel `arch/*/configs/`.

The function is mainly used by in-process ThinLTO to decide the default number
of threads. Returning -1 will use just one thread.

Android is excluded because of the higher API level requirement:
`sched_getaffinity; # introduced-arm=12 introduced-arm64=21 introduced-x86=12 introduced-x86_64=21`

Added: 
    

Modified: 
    llvm/lib/Support/Host.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/Host.cpp b/llvm/lib/Support/Host.cpp
index f67acd7416315..f163c8256adbd 100644
--- a/llvm/lib/Support/Host.cpp
+++ b/llvm/lib/Support/Host.cpp
@@ -1586,7 +1586,9 @@ int computeHostNumPhysicalCores() {
   }
   return CPU_COUNT(&Enabled);
 }
-#elif defined(__linux__) && defined(__powerpc__)
+#elif defined(__linux__) && defined(__s390x__)
+int computeHostNumPhysicalCores() { return sysconf(_SC_NPROCESSORS_ONLN); }
+#elif defined(__linux__) && !defined(__ANDROID__)
 int computeHostNumPhysicalCores() {
   cpu_set_t Affinity;
   if (sched_getaffinity(0, sizeof(Affinity), &Affinity) == 0)
@@ -1605,8 +1607,6 @@ int computeHostNumPhysicalCores() {
   }
   return -1;
 }
-#elif defined(__linux__) && defined(__s390x__)
-int computeHostNumPhysicalCores() { return sysconf(_SC_NPROCESSORS_ONLN); }
 #elif defined(__APPLE__)
 // Gets the number of *physical cores* on the machine.
 int computeHostNumPhysicalCores() {