From 05b2d3f7dc623fc5304fa0edc9efeaf08ea1db26 Mon Sep 17 00:00:00 2001 From: Alex Crichton Date: Fri, 5 Jun 2020 10:14:53 -0700 Subject: [PATCH] std: Enable atomic.fence emission on wasm32 This commit removes the `#[cfg]` guards in `atomic::fence` on wasm targets. Since these guards were originally added the upstream wasm specification for threads gained an `atomic.fence` instruction, so LLVM no longer panics on these intrinsics. Although there aren't a ton of tests in-repo for this right now I've tested locally and all of these fences generate `atomic.fence` instructions in wasm. Closes #72997 --- src/libcore/sync/atomic.rs | 8 -------- 1 file changed, 8 deletions(-) diff --git a/src/libcore/sync/atomic.rs b/src/libcore/sync/atomic.rs index 449aac85bc7..d3196017848 100644 --- a/src/libcore/sync/atomic.rs +++ b/src/libcore/sync/atomic.rs @@ -2536,15 +2536,7 @@ unsafe fn atomic_umin(dst: *mut T, val: T, order: Ordering) -> T { /// [`Relaxed`]: enum.Ordering.html#variant.Relaxed #[inline] #[stable(feature = "rust1", since = "1.0.0")] -#[cfg_attr(target_arch = "wasm32", allow(unused_variables))] pub fn fence(order: Ordering) { - // On wasm32 it looks like fences aren't implemented in LLVM yet in that - // they will cause LLVM to abort. The wasm instruction set doesn't have - // fences right now. There's discussion online about the best way for tools - // to conventionally implement fences at - // https://github.com/WebAssembly/tool-conventions/issues/59. We should - // follow that discussion and implement a solution when one comes about! - #[cfg(not(target_arch = "wasm32"))] // SAFETY: using an atomic fence is safe. unsafe { match order {