[libc-commits] [libc] 9ffde19 - [libc] Add PAUSE instruction for the RPC spin loop

[Joseph Huber via libc-commits]

Author: Joseph Huber
Date: 2023-07-28T18:09:01-05:00
New Revision: 9ffde19d112e71ac5716d07f48fa20d85232adf9

URL: https://github.com/llvm/llvm-project/commit/9ffde19d112e71ac5716d07f48fa20d85232adf9
DIFF: https://github.com/llvm/llvm-project/commit/9ffde19d112e71ac5716d07f48fa20d85232adf9.diff

LOG: [libc] Add PAUSE instruction for the RPC spin loop

The other architectures use a brief sleep to defer work during this spin
loop that checks the RPC mailboxes. This patch adds one for x64 to
improve usage when running the server.

Reviewed By: tianshilei1992

Differential Revision: https://reviews.llvm.org/D156566

Added: 
    

Modified: 
    libc/src/__support/RPC/rpc_util.h

Removed: 
    


################################################################################
diff  --git a/libc/src/__support/RPC/rpc_util.h b/libc/src/__support/RPC/rpc_util.h
index 910eceece12887..f4f5a9a4573777 100644
--- a/libc/src/__support/RPC/rpc_util.h
+++ b/libc/src/__support/RPC/rpc_util.h
@@ -26,6 +26,8 @@ LIBC_INLINE void sleep_briefly() {
   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