diff --git a/src/librustc_codegen_llvm/attributes.rs b/src/librustc_codegen_llvm/attributes.rs index e4d6d7d8af90e..ac2bbd4b2aea4 100644 --- a/src/librustc_codegen_llvm/attributes.rs +++ b/src/librustc_codegen_llvm/attributes.rs @@ -13,8 +13,6 @@ use rustc_middle::ty::query::Providers; use rustc_middle::ty::{self, Ty, TyCtxt}; use rustc_session::config::{OptLevel, Sanitizer}; use rustc_session::Session; -use rustc_target::abi::call::Conv; -use rustc_target::spec::PanicStrategy; use crate::abi::FnAbi; use crate::attributes; @@ -315,45 +313,7 @@ pub fn from_fn_attrs( } sanitize(cx, codegen_fn_attrs.flags, llfn); - unwind( - llfn, - if cx.tcx.sess.panic_strategy() != PanicStrategy::Unwind { - // In panic=abort mode we assume nothing can unwind anywhere, so - // optimize based on this! - false - } else if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::UNWIND) { - // If a specific #[unwind] attribute is present, use that. - true - } else if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND) { - // Special attribute for allocator functions, which can't unwind. - false - } else { - if fn_abi.conv == Conv::Rust { - // Any Rust method (or `extern "Rust" fn` or `extern - // "rust-call" fn`) is explicitly allowed to unwind - // (unless it has no-unwind attribute, handled above). - true - } else { - // Anything else is either: - // - // 1. A foreign item using a non-Rust ABI (like `extern "C" { fn foo(); }`), or - // - // 2. A Rust item using a non-Rust ABI (like `extern "C" fn foo() { ... }`). - // - // Foreign items (case 1) are assumed to not unwind; it is - // UB otherwise. (At least for now; see also - // rust-lang/rust#63909 and Rust RFC 2753.) - // - // Items defined in Rust with non-Rust ABIs (case 2) are also - // not supposed to unwind. Whether this should be enforced - // (versus stating it is UB) and *how* it would be enforced - // is currently under discussion; see rust-lang/rust#58794. - // - // In either case, we mark item as explicitly nounwind. - false - } - }, - ); + unwind(llfn, fn_abi.can_unwind); // Always annotate functions with the target-cpu they are compiled for. // Without this, ThinLTO won't inline Rust functions into Clang generated diff --git a/src/librustc_middle/ty/layout.rs b/src/librustc_middle/ty/layout.rs index 54fde52ba3a77..17c93922b0023 100644 --- a/src/librustc_middle/ty/layout.rs +++ b/src/librustc_middle/ty/layout.rs @@ -1,4 +1,5 @@ use crate::ich::StableHashingContext; +use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; use crate::mir::{GeneratorLayout, GeneratorSavedLocal}; use crate::ty::subst::Subst; use crate::ty::{self, subst::SubstsRef, ReprOptions, Ty, TyCtxt, TypeFoldable}; @@ -15,7 +16,7 @@ use rustc_target::abi::call::{ ArgAbi, ArgAttribute, ArgAttributes, Conv, FnAbi, PassMode, Reg, RegKind, }; pub use rustc_target::abi::*; -use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec}; +use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy}; use std::cmp; use std::fmt; @@ -2368,11 +2369,55 @@ where sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>], caller_location: Option>, + codegen_fn_attr_flags: CodegenFnAttrFlags, mk_arg_type: impl Fn(Ty<'tcx>, Option) -> ArgAbi<'tcx, Ty<'tcx>>, ) -> Self; fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi); } +fn fn_can_unwind( + panic_strategy: PanicStrategy, + codegen_fn_attr_flags: CodegenFnAttrFlags, + call_conv: Conv, +) -> bool { + if panic_strategy != PanicStrategy::Unwind { + // In panic=abort mode we assume nothing can unwind anywhere, so + // optimize based on this! + false + } else if codegen_fn_attr_flags.contains(CodegenFnAttrFlags::UNWIND) { + // If a specific #[unwind] attribute is present, use that. + true + } else if codegen_fn_attr_flags.contains(CodegenFnAttrFlags::RUSTC_ALLOCATOR_NOUNWIND) { + // Special attribute for allocator functions, which can't unwind. + false + } else { + if call_conv == Conv::Rust { + // Any Rust method (or `extern "Rust" fn` or `extern + // "rust-call" fn`) is explicitly allowed to unwind + // (unless it has no-unwind attribute, handled above). + true + } else { + // Anything else is either: + // + // 1. A foreign item using a non-Rust ABI (like `extern "C" { fn foo(); }`), or + // + // 2. A Rust item using a non-Rust ABI (like `extern "C" fn foo() { ... }`). + // + // Foreign items (case 1) are assumed to not unwind; it is + // UB otherwise. (At least for now; see also + // rust-lang/rust#63909 and Rust RFC 2753.) + // + // Items defined in Rust with non-Rust ABIs (case 2) are also + // not supposed to unwind. Whether this should be enforced + // (versus stating it is UB) and *how* it would be enforced + // is currently under discussion; see rust-lang/rust#58794. + // + // In either case, we mark item as explicitly nounwind. + false + } + } +} + impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>> where C: LayoutOf, TyAndLayout = TyAndLayout<'tcx>> @@ -2382,7 +2427,12 @@ where + HasParamEnv<'tcx>, { fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { - call::FnAbi::new_internal(cx, sig, extra_args, None, |ty, _| ArgAbi::new(cx.layout_of(ty))) + // Assume that fn pointers may always unwind + let codegen_fn_attr_flags = CodegenFnAttrFlags::UNWIND; + + call::FnAbi::new_internal(cx, sig, extra_args, None, codegen_fn_attr_flags, |ty, _| { + ArgAbi::new(cx.layout_of(ty)) + }) } fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { @@ -2394,7 +2444,9 @@ where None }; - call::FnAbi::new_internal(cx, sig, extra_args, caller_location, |ty, arg_idx| { + let attrs = cx.tcx().codegen_fn_attrs(instance.def_id()).flags; + + call::FnAbi::new_internal(cx, sig, extra_args, caller_location, attrs, |ty, arg_idx| { let mut layout = cx.layout_of(ty); // Don't pass the vtable, it's not an argument of the virtual fn. // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait` @@ -2450,6 +2502,7 @@ where sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>], caller_location: Option>, + codegen_fn_attr_flags: CodegenFnAttrFlags, mk_arg_type: impl Fn(Ty<'tcx>, Option) -> ArgAbi<'tcx, Ty<'tcx>>, ) -> Self { debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args); @@ -2639,6 +2692,7 @@ where c_variadic: sig.c_variadic, fixed_count: inputs.len(), conv, + can_unwind: fn_can_unwind(cx.tcx().sess.panic_strategy(), codegen_fn_attr_flags, conv), }; fn_abi.adjust_for_abi(cx, sig.abi); fn_abi diff --git a/src/librustc_target/abi/call/mod.rs b/src/librustc_target/abi/call/mod.rs index ffc85c153c9cd..72768c31e3077 100644 --- a/src/librustc_target/abi/call/mod.rs +++ b/src/librustc_target/abi/call/mod.rs @@ -546,6 +546,8 @@ pub struct FnAbi<'a, Ty> { pub fixed_count: usize, pub conv: Conv, + + pub can_unwind: bool, } impl<'a, Ty> FnAbi<'a, Ty> {