Rollup merge of rust-lang#91548 - luojia65:hint-spin-loop-riscv, r=Am…

…anieu Add spin_loop hint for RISC-V architecture This commit uses the PAUSE instruction (rust-lang/stdarch#1262) to implement RISC-V spin loop, and updates `stdarch` submodule to use the merged PAUSE instruction.
matthiaskrgr · Dec 8, 2021 · 22afb94 · 22afb94
2 parents a713341 + 70855b2
commit 22afb94
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diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
@@ -137,6 +137,11 @@ pub fn spin_loop() {
             unsafe { crate::arch::arm::__yield() };
         }
     }
+
+    #[cfg(any(target_arch = "riscv32", target_arch = "riscv64"))]
+    {
+        crate::arch::riscv::pause();
+    }
 }
 
 /// An identity function that *__hints__* to the compiler to be maximally pessimistic about what

diff --git a/library/stdarch b/library/stdarch