From c8f0b15a2dd7dfc0635cc682ebc3516ea358a0be Mon Sep 17 00:00:00 2001 From: bjorn3 <17426603+bjorn3@users.noreply.github.com> Date: Thu, 7 Nov 2024 15:54:40 +0000 Subject: [PATCH] Make fn_abi_sanity_check a bit stricter The Rust ABI must ignore all ZST arguments, all ignored arguments must be either ZST or uninhabited. And finally ScalarPair should never be passed as PassMode::Direct. --- compiler/rustc_ty_utils/src/abi.rs | 81 +++++++++++++++++++----------- 1 file changed, 51 insertions(+), 30 deletions(-) diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs index 0838978a891..0184e93acf1 100644 --- a/compiler/rustc_ty_utils/src/abi.rs +++ b/compiler/rustc_ty_utils/src/abi.rs @@ -463,43 +463,64 @@ fn fn_arg_sanity_check<'tcx>( arg: &ArgAbi<'tcx, Ty<'tcx>>, ) { let tcx = cx.tcx(); + + if spec_abi == ExternAbi::Rust + || spec_abi == ExternAbi::RustCall + || spec_abi == ExternAbi::RustCold + { + if arg.layout.is_zst() { + // Casting closures to function pointers depends on ZST closure types being + // omitted entirely in the calling convention. + assert!(arg.is_ignore()); + } + if let PassMode::Indirect { on_stack, .. } = arg.mode { + assert!(!on_stack, "rust abi shouldn't use on_stack"); + } + } + match &arg.mode { - PassMode::Ignore => {} + PassMode::Ignore => { + assert!(arg.layout.is_zst() || arg.layout.is_uninhabited()); + } PassMode::Direct(_) => { // Here the Rust type is used to determine the actual ABI, so we have to be very - // careful. Scalar/ScalarPair is fine, since backends will generally use - // `layout.abi` and ignore everything else. We should just reject `Aggregate` - // entirely here, but some targets need to be fixed first. - if matches!(arg.layout.backend_repr, BackendRepr::Memory { .. }) { - // For an unsized type we'd only pass the sized prefix, so there is no universe - // in which we ever want to allow this. - assert!( - arg.layout.is_sized(), - "`PassMode::Direct` for unsized type in ABI: {:#?}", - fn_abi - ); - // This really shouldn't happen even for sized aggregates, since - // `immediate_llvm_type` will use `layout.fields` to turn this Rust type into an - // LLVM type. This means all sorts of Rust type details leak into the ABI. - // However wasm sadly *does* currently use this mode so we have to allow it -- - // but we absolutely shouldn't let any more targets do that. - // (Also see .) - // - // The unstable abi `PtxKernel` also uses Direct for now. - // It needs to switch to something else before stabilization can happen. - // (See issue: https://github.com/rust-lang/rust/issues/117271) - assert!( - matches!(&*tcx.sess.target.arch, "wasm32" | "wasm64") - || matches!(spec_abi, ExternAbi::PtxKernel | ExternAbi::Unadjusted), - "`PassMode::Direct` for aggregates only allowed for \"unadjusted\" and \"ptx-kernel\" functions and on wasm\n\ + // careful. Scalar/Vector is fine, since backends will generally use + // `layout.backend_repr` and ignore everything else. We should just reject + //`Aggregate` entirely here, but some targets need to be fixed first. + match arg.layout.backend_repr { + BackendRepr::Uninhabited + | BackendRepr::Scalar(_) + | BackendRepr::Vector { .. } => {} + BackendRepr::ScalarPair(..) => { + panic!("`PassMode::Direct` used for ScalarPair type {}", arg.layout.ty) + } + BackendRepr::Memory { sized } => { + // For an unsized type we'd only pass the sized prefix, so there is no universe + // in which we ever want to allow this. + assert!(sized, "`PassMode::Direct` for unsized type in ABI: {:#?}", fn_abi); + // This really shouldn't happen even for sized aggregates, since + // `immediate_llvm_type` will use `layout.fields` to turn this Rust type into an + // LLVM type. This means all sorts of Rust type details leak into the ABI. + // However wasm sadly *does* currently use this mode so we have to allow it -- + // but we absolutely shouldn't let any more targets do that. + // (Also see .) + // + // The unstable abi `PtxKernel` also uses Direct for now. + // It needs to switch to something else before stabilization can happen. + // (See issue: https://github.com/rust-lang/rust/issues/117271) + assert!( + matches!(&*tcx.sess.target.arch, "wasm32" | "wasm64") + || matches!(spec_abi, ExternAbi::PtxKernel | ExternAbi::Unadjusted), + "`PassMode::Direct` for aggregates only allowed for \"unadjusted\" and \"ptx-kernel\" functions and on wasm\n\ Problematic type: {:#?}", - arg.layout, - ); + arg.layout, + ); + } } } PassMode::Pair(_, _) => { - // Similar to `Direct`, we need to make sure that backends use `layout.abi` and - // ignore the rest of the layout. + // Similar to `Direct`, we need to make sure that backends use `layout.backend_repr` + // and ignore the rest of the layout. assert!( matches!(arg.layout.backend_repr, BackendRepr::ScalarPair(..)), "PassMode::Pair for type {}",