From de7342b4446476a2d9375a7f93be54dc9f8707d1 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 1 Sep 2022 16:18:39 +0000
Subject: [PATCH] Implement core::hint::spin_loop() on AArch64

This is used in the futex based mutex implementation of libstd
---
 src/intrinsics/llvm.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/intrinsics/llvm.rs b/src/intrinsics/llvm.rs
index a799dca938e2..598c13e757ef 100644
--- a/src/intrinsics/llvm.rs
+++ b/src/intrinsics/llvm.rs
@@ -14,6 +14,10 @@ pub(crate) fn codegen_llvm_intrinsic_call<'tcx>(
     target: Option<BasicBlock>,
 ) {
     match intrinsic {
+        "llvm.x86.sse2.pause" | "llvm.aarch64.isb" => {
+            // Spin loop hint
+        }
+
         // Used by `_mm_movemask_epi8` and `_mm256_movemask_epi8`
         "llvm.x86.sse2.pmovmskb.128" | "llvm.x86.avx2.pmovmskb" | "llvm.x86.sse2.movmsk.pd" => {
             intrinsic_args!(fx, args => (a); intrinsic);