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

[Schrodinger ZHU Yifan via libc-commits]

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@@ -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.
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SchrodingerZhu wrote:

It may be nice to check __riscv_zihintpause.

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