[libc-commits] [libc] [libc][NFC] Move 'sleep_briefly' function to common header (PR #83074)

[Joseph Huber via libc-commits]

https://github.com/jhuber6 updated https://github.com/llvm/llvm-project/pull/83074

>From a21487118ffa01a906cfda799e3108f9ecdf121b Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Mon, 26 Feb 2024 16:25:59 -0600
Subject: [PATCH] [libc][NFC] Move 'sleep_briefly' function to common header

Summary:
The https://github.com/llvm/llvm-project/pull/83026 patch has another
use for this function. Additionally add support for the Arm instruction
barrier if this is ever used by other targets.
---
 libc/src/__support/RPC/rpc_util.h         | 17 ++----------
 libc/src/__support/threads/CMakeLists.txt |  6 ++++
 libc/src/__support/threads/sleep.h        | 34 +++++++++++++++++++++++
 3 files changed, 42 insertions(+), 15 deletions(-)
 create mode 100644 libc/src/__support/threads/sleep.h

diff --git a/libc/src/__support/RPC/rpc_util.h b/libc/src/__support/RPC/rpc_util.h
index cc2a11a1108e01..11d2f751355d34 100644
--- a/libc/src/__support/RPC/rpc_util.h
+++ b/libc/src/__support/RPC/rpc_util.h
@@ -11,28 +11,15 @@
 
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/GPU/utils.h"
-#include "src/__support/macros/attributes.h" // LIBC_INLINE
+#include "src/__support/macros/attributes.h"
 #include "src/__support/macros/properties/architectures.h"
+#include "src/__support/threads/sleep.h"
 #include "src/string/memory_utils/generic/byte_per_byte.h"
 #include "src/string/memory_utils/inline_memcpy.h"
 
 namespace LIBC_NAMESPACE {
 namespace rpc {
 
-/// Suspend the thread briefly to assist the thread scheduler during busy loops.
-LIBC_INLINE void sleep_briefly() {
-#if defined(LIBC_TARGET_ARCH_IS_NVPTX)
-  if (__nvvm_reflect("__CUDA_ARCH") >= 700)
-    LIBC_INLINE_ASM("nanosleep.u32 64;" ::: "memory");
-#elif defined(LIBC_TARGET_ARCH_IS_AMDGPU)
-  __builtin_amdgcn_s_sleep(2);
-#elif defined(LIBC_TARGET_ARCH_IS_X86)
-  __builtin_ia32_pause();
-#else
-  // Simply do nothing if sleeping isn't supported on this platform.
-#endif
-}
-
 /// Conditional to indicate if this process is running on the GPU.
 LIBC_INLINE constexpr bool is_process_gpu() {
 #if defined(LIBC_TARGET_ARCH_IS_GPU)
diff --git a/libc/src/__support/threads/CMakeLists.txt b/libc/src/__support/threads/CMakeLists.txt
index 0feeda0c179b9f..731adf6f9c8e4e 100644
--- a/libc/src/__support/threads/CMakeLists.txt
+++ b/libc/src/__support/threads/CMakeLists.txt
@@ -4,6 +4,12 @@ add_header_library(
     mutex_common.h
 )
 
+add_header_library(
+  sleep
+  HDRS
+    sleep.h
+)
+
 if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
   add_subdirectory(${LIBC_TARGET_OS})
 endif()
diff --git a/libc/src/__support/threads/sleep.h b/libc/src/__support/threads/sleep.h
new file mode 100644
index 00000000000000..9a2dff598ece8b
--- /dev/null
+++ b/libc/src/__support/threads/sleep.h
@@ -0,0 +1,34 @@
+//===-- Utilities for suspending threads ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H
+#define LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H
+
+#include "src/__support/macros/attributes.h"
+
+namespace LIBC_NAMESPACE {
+
+/// Suspend the thread briefly to assist the thread scheduler during busy loops.
+LIBC_INLINE void sleep_briefly() {
+#if defined(LIBC_TARGET_ARCH_IS_NVPTX)
+  if (__nvvm_reflect("__CUDA_ARCH") >= 700)
+    LIBC_INLINE_ASM("nanosleep.u32 64;" ::: "memory");
+#elif defined(LIBC_TARGET_ARCH_IS_AMDGPU)
+  __builtin_amdgcn_s_sleep(2);
+#elif defined(LIBC_TARGET_ARCH_IS_X86)
+  __builtin_ia32_pause();
+#elif defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  __builtin_arm_isb(0xf);
+#else
+  // Simply do nothing if sleeping isn't supported on this platform.
+#endif
+}
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H