1 //===-- Utilities for suspending threads ----------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H 10 #define LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H 11 12 #include "src/__support/macros/attributes.h" 13 #include "src/__support/macros/config.h" 14 15 namespace LIBC_NAMESPACE_DECL { 16 17 /// Suspend the thread briefly to assist the thread scheduler during busy loops. sleep_briefly()18LIBC_INLINE void sleep_briefly() { 19 #if defined(LIBC_TARGET_ARCH_IS_NVPTX) 20 if (__nvvm_reflect("__CUDA_ARCH") >= 700) 21 LIBC_INLINE_ASM("nanosleep.u32 64;" ::: "memory"); 22 #elif defined(LIBC_TARGET_ARCH_IS_AMDGPU) 23 __builtin_amdgcn_s_sleep(2); 24 #elif defined(LIBC_TARGET_ARCH_IS_X86) 25 __builtin_ia32_pause(); 26 #elif defined(LIBC_TARGET_ARCH_IS_AARCH64) && __has_builtin(__builtin_arm_isb) 27 __builtin_arm_isb(0xf); 28 #elif defined(LIBC_TARGET_ARCH_IS_AARCH64) 29 asm volatile("isb\n" ::: "memory"); 30 #else 31 // Simply do nothing if sleeping isn't supported on this platform. 32 #endif 33 } 34 35 } // namespace LIBC_NAMESPACE_DECL 36 37 #endif // LLVM_LIBC_SRC___SUPPORT_THREADS_SLEEP_H 38