[Openmp-commits] [openmp] [OpenMP] Fix KMP_OS_AIX handling (PR #138499)

[Rainer Orth via Openmp-commits]

https://github.com/rorth created https://github.com/llvm/llvm-project/pull/138499

When building `openmp` on Linux/sparc64, I get

```
In file included fromopenmp/runtime/src/kmp_utility.cpp:16:
openmp/runtime/src/kmp_wrapper_getpid.h:47:2: warning: No gettid found, use getpid instead [-W#warnings]
   47 | #warning No gettid found, use getpid instead
      |  ^
```

This is highly confusing since `<sys/syscall.h>` **does** define `SYS_gettid` and the header is supposed to be included:

```
#if !defined(KMP_OS_AIX) && !defined(KMP_OS_HAIKU)
#include <sys/syscall.h>
#endif
```

However, this actually is **not** the case for two reasons:

- `KMP_OS_HAIKU` is always defined, either as 1 on Haiku or as 0 otherwise.
- `KMP_OS_AIX` is even worse: it is only defined as 1 on on AIX, but undefined otherwise.

All those `KMP_OS_*` macros are supposed to always be defined as 1/0 as appropriate, and to be checked with `#if`, not `#ifdef`.  AIX is violating this, causing the problem above.

Other targets probably get `<sys/syscall.h>` indirectly otherwise, but Linux/sparc64 does not.

This patch fixes this by also defining `KMP_OS_AIX` as 0 on other OSes and changing the checks to `#if` as necessary.

Tested on `sparc64-unknown-linux-gnu`, `sparcv9-sun-solaris2.11`, `amd64-pc-solaris2.11`, and `x86_64-pc-linux-gnu`.

>From 57e5bed2590b7e255c15608ba926b2d753fb3664 Mon Sep 17 00:00:00 2001
From: Rainer Orth <ro at gcc.gnu.org>
Date: Mon, 5 May 2025 11:50:29 +0200
Subject: [PATCH] [OpenMP] Fix KMP_OS_AIX handling

When building `openmp` on Linux/sparc64, I get

```
In file included fromopenmp/runtime/src/kmp_utility.cpp:16:
openmp/runtime/src/kmp_wrapper_getpid.h:47:2: warning: No gettid found, use getpid instead [-W#warnings]
   47 | #warning No gettid found, use getpid instead
      |  ^
```

This is highly confusing since `<sys/syscall.h>` **does** define
`SYS_gettid` and the header is supposed to be included:

```
#if !defined(KMP_OS_AIX) && !defined(KMP_OS_HAIKU)
#include <sys/syscall.h>
#endif
```

However, this actually is **not** the case for two reasons:

- `KMP_OS_HAIKU` is always defined, either as 1 on Haiku or as 0 otherwise.
- `KMP_OS_AIX` is even worse: it is only defined as 1 on on AIX, but
  undefined otherwise.

All those `KMP_OS_*` macros are supposed to always be defined as 1/0 as
appropriate, and to be checked with `#if`, not `#ifdef`.  AIX is violating
this, causing the problem above.

Other targets probably get `<sys/syscall.h>` indirectly otherwise, but
Linux/sparc64 does not.

This patch fixes this by also defining `KMP_OS_AIX` as 0 on other OSes and
changing the checks to `#if` as necessary.

Tested on `sparc64-unknown-linux-gnu`, `sparcv9-sun-solaris2.11`,
`amd64-pc-solaris2.11`, and `x86_64-pc-linux-gnu`.
---
 openmp/runtime/src/kmp.h                | 2 +-
 openmp/runtime/src/kmp_affinity.cpp     | 2 +-
 openmp/runtime/src/kmp_platform.h       | 5 +++--
 openmp/runtime/src/kmp_wrapper_getpid.h | 2 +-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/openmp/runtime/src/kmp.h b/openmp/runtime/src/kmp.h
index d5d667c32c643..a2cacc8792b15 100644
--- a/openmp/runtime/src/kmp.h
+++ b/openmp/runtime/src/kmp.h
@@ -821,7 +821,7 @@ class KMPAffinity {
 typedef KMPAffinity::Mask kmp_affin_mask_t;
 extern KMPAffinity *__kmp_affinity_dispatch;
 
-#ifndef KMP_OS_AIX
+#if !KMP_OS_AIX
 class kmp_affinity_raii_t {
   kmp_affin_mask_t *mask;
   bool restored;
diff --git a/openmp/runtime/src/kmp_affinity.cpp b/openmp/runtime/src/kmp_affinity.cpp
index f2520db145552..a6065fe792d55 100644
--- a/openmp/runtime/src/kmp_affinity.cpp
+++ b/openmp/runtime/src/kmp_affinity.cpp
@@ -5468,7 +5468,7 @@ void __kmp_affinity_bind_init_mask(int gtid) {
     __kmp_set_system_affinity(th->th.th_affin_mask, FALSE);
   } else
 #endif
-#ifndef KMP_OS_AIX
+#if !KMP_OS_AIX
     // Do not set the full mask as the init mask on AIX.
     __kmp_set_system_affinity(th->th.th_affin_mask, TRUE);
 #endif
diff --git a/openmp/runtime/src/kmp_platform.h b/openmp/runtime/src/kmp_platform.h
index 80afba6c6af2e..609b7c4688842 100644
--- a/openmp/runtime/src/kmp_platform.h
+++ b/openmp/runtime/src/kmp_platform.h
@@ -27,6 +27,7 @@
 #define KMP_OS_SOLARIS 0
 #define KMP_OS_WASI 0
 #define KMP_OS_EMSCRIPTEN 0
+#define KMP_OS_AIX 0
 #define KMP_OS_UNIX 0 /* disjunction of KMP_OS_LINUX, KMP_OS_DARWIN etc. */
 
 #ifdef _WIN32
@@ -163,11 +164,11 @@
 #undef KMP_ARCH_PPC64_ELFv1
 #define KMP_ARCH_PPC64_ELFv1 1
 #endif
-#elif defined KMP_OS_AIX
+#elif KMP_OS_AIX
 #undef KMP_ARCH_PPC64_XCOFF
 #define KMP_ARCH_PPC64_XCOFF 1
 #endif
-#elif defined(__powerpc__) && defined(KMP_OS_AIX)
+#elif defined(__powerpc__) && KMP_OS_AIX
 #undef KMP_ARCH_PPC_XCOFF
 #define KMP_ARCH_PPC_XCOFF 1
 #undef KMP_ARCH_PPC
diff --git a/openmp/runtime/src/kmp_wrapper_getpid.h b/openmp/runtime/src/kmp_wrapper_getpid.h
index 6b41dfcc20880..c6c7ac01799a0 100644
--- a/openmp/runtime/src/kmp_wrapper_getpid.h
+++ b/openmp/runtime/src/kmp_wrapper_getpid.h
@@ -17,7 +17,7 @@
 
 // On Unix-like systems (Linux* OS and OS X*) getpid() is declared in standard
 // headers.
-#if !defined(KMP_OS_AIX) && !defined(KMP_OS_HAIKU)
+#if !KMP_OS_AIX && !KMP_OS_HAIKU
 #include <sys/syscall.h>
 #endif
 #include <sys/types.h>