From 77bd4dc65406ba3cedbc779e6f6280868231912e Mon Sep 17 00:00:00 2001 From: Josh Stone Date: Mon, 10 Jul 2017 17:06:38 -0700 Subject: [PATCH] Disable big-endian simd in swap_nonoverlapping_bytes This is a workaround for #42778, which was git-bisected to #40454's optimizations to `mem::swap`, later moved to `ptr` in #42819. Natively compiled rustc couldn't even compile stage1 libcore on powerpc64 and s390x, but they work fine without this `repr(simd)`. Since powerpc64le works OK, it seems probably related to being big-endian. The underlying problem is not yet known, but this at least makes those architectures functional again in the meantime. cc @arielb1 --- src/libcore/ptr.rs | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs index 92470299366ce..4f118f58441c4 100644 --- a/src/libcore/ptr.rs +++ b/src/libcore/ptr.rs @@ -160,7 +160,10 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) { // #[repr(simd)], even if we don't actually use this struct directly. // // FIXME repr(simd) broken on emscripten and redox - #[cfg_attr(not(any(target_os = "emscripten", target_os = "redox")), repr(simd))] + // It's also broken on big-endian powerpc64 and s390x. #42778 + #[cfg_attr(not(any(target_os = "emscripten", target_os = "redox", + target_endian = "big")), + repr(simd))] struct Block(u64, u64, u64, u64); struct UnalignedBlock(u64, u64, u64, u64);