From 8eb44a3bf861523e31b962db8c7fd1e7b6225e89 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Sat, 21 Dec 2019 16:55:07 +0100 Subject: [PATCH 07/18] Fix zero-sized aggregate ABI on powerpc For targets that pass zero-sized aggregates indirectly (generally those that pass all aggregates indirectly), we must allocate a register for passing the address of the ZST. Clean up the existing cases and add powerpc, which requires this as well. While there are not currently musl targets for s390x or sparc64, they would have the same ABI as gnu targets, so remove the env == "gnu" check in the Linux case. Ideally, since it is a property of the C ABI, the `!rust_abi` case would be handled entirely in `adjust_c_abi`. However, that would require updating each implementation of `compute_abi_info` to handle ZSTs. --- src/librustc/ty/layout.rs | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs index e82232ac..8bdf3436 100644 --- a/src/librustc/ty/layout.rs +++ b/src/librustc/ty/layout.rs @@ -2638,12 +2638,11 @@ where }; let target = &cx.tcx().sess.target.target; - let win_x64_gnu = - target.target_os == "windows" && target.arch == "x86_64" && target.target_env == "gnu"; - let linux_s390x = - target.target_os == "linux" && target.arch == "s390x" && target.target_env == "gnu"; - let linux_sparc64 = - target.target_os == "linux" && target.arch == "sparc64" && target.target_env == "gnu"; + let indirect_zst = match target.arch.as_ref() { + "powerpc" | "s390x" | "sparc64" => true, + "x86_64" => target.target_os == "windows" && target.target_env == "gnu", + _ => false, + }; let rust_abi = match sig.abi { RustIntrinsic | PlatformIntrinsic | Rust | RustCall => true, _ => false, @@ -2705,11 +2704,10 @@ where let is_return = arg_idx.is_none(); let mut arg = mk_arg_type(ty, arg_idx); if arg.layout.is_zst() { - // For some forsaken reason, x86_64-pc-windows-gnu - // doesn't ignore zero-sized struct arguments. - // The same is true for s390x-unknown-linux-gnu - // and sparc64-unknown-linux-gnu. - if is_return || rust_abi || (!win_x64_gnu && !linux_s390x && !linux_sparc64) { + // FIXME: The C ABI case should be handled in adjust_for_cabi. + // Zero-sized struct arguments cannot be ignored in the C ABI + // if they are passed indirectly. + if is_return || rust_abi || !indirect_zst { arg.mode = PassMode::Ignore; } } -- 2.24.0