[Openmp-commits] [openmp] [OpenMP] Fix child processes to use affinity_none (PR #91391)

[Jonathan Peyton via Openmp-commits]

https://github.com/jpeyton52 created https://github.com/llvm/llvm-project/pull/91391

When a child process is forked with OpenMP already initialized, the child process resets its affinity mask and sets proc-bind-var to false so that the entire original affinity mask is used. This patch corrects an issue with the affinity initialization code setting affinity to compact instead of none for this special case of forked children.

The test trying to catch this only testing explicit setting of KMP_AFFINITY=none. Add test run for no KMP_AFFINITY setting.

Fixes: #91098

>From b353c30d565787ef356d5e3cdd4ce3fbd2cb57e8 Mon Sep 17 00:00:00 2001
From: Jonathan Peyton <jonathan.l.peyton at intel.com>
Date: Tue, 7 May 2024 14:58:12 -0500
Subject: [PATCH] [OpenMP] Fix child processes to use affinity_none

When a child process is forked with OpenMP already initialized, the
child process resets its affinity mask and sets proc-bind-var to false
so that the entire original affinity mask is used. This patch corrects
an issue with the affinity initialization code setting affinity to
compact instead of none for this special case of forked children.

Fixes: #91098
---
 openmp/runtime/src/kmp_settings.cpp     | 2 ++
 openmp/runtime/test/affinity/redetect.c | 1 +
 2 files changed, 3 insertions(+)

diff --git a/openmp/runtime/src/kmp_settings.cpp b/openmp/runtime/src/kmp_settings.cpp
index b9c8289b5c51c..8b6092cb1085c 100644
--- a/openmp/runtime/src/kmp_settings.cpp
+++ b/openmp/runtime/src/kmp_settings.cpp
@@ -6420,6 +6420,8 @@ void __kmp_env_initialize(char const *string) {
         }
         if ((__kmp_nested_proc_bind.bind_types[0] != proc_bind_intel) &&
             (__kmp_nested_proc_bind.bind_types[0] != proc_bind_default)) {
+          if (__kmp_nested_proc_bind.bind_types[0] == proc_bind_false)
+            __kmp_affinity.type = affinity_none;
           if (__kmp_affinity.type == affinity_default) {
             __kmp_affinity.type = affinity_compact;
             __kmp_affinity.flags.dups = FALSE;
diff --git a/openmp/runtime/test/affinity/redetect.c b/openmp/runtime/test/affinity/redetect.c
index dba83b72cc42e..4b96d1bd92ee7 100644
--- a/openmp/runtime/test/affinity/redetect.c
+++ b/openmp/runtime/test/affinity/redetect.c
@@ -1,4 +1,5 @@
 // RUN: %libomp-compile
+// RUN: %libomp-run
 // RUN: env KMP_AFFINITY=none %libomp-run
 // REQUIRES: linux