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add panic_fmt_nounwind for panicing without unwinding, and use it for panic_no_unwind

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This commit is contained in:
Ralf Jung 2022-10-06 12:40:43 +02:00
parent 2b50cd1877
commit 66282cb47d
2 changed files with 19 additions and 10 deletions
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7
compiler/rustc_hir_analysis/src/collect.rs
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@ -1582,13 +1582,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER; codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
} }
// The panic_no_unwind function called by TerminatorKind::Abort will never
// unwind. If the panic handler that it invokes unwind then it will simply
// call the panic handler again.
if Some(did.to_def_id()) == tcx.lang_items().panic_no_unwind() {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
}
let supported_target_features = tcx.supported_target_features(LOCAL_CRATE); let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
let mut inline_span = None; let mut inline_span = None;

22
library/core/src/panicking.rs
View file

@ -84,12 +84,27 @@ fn panic_bounds_check(index: usize, len: usize) -> ! {
panic!("index out of bounds: the len is {len} but the index is {index}") panic!("index out of bounds: the len is {len} but the index is {index}")
} }
// This function is called directly by the codegen backend, and must not have /// Panic because we cannot unwind out of a function.
// any extra arguments (including those synthesized by track_caller). ///
/// This function is called directly by the codegen backend, and must not have
/// any extra arguments (including those synthesized by track_caller).
#[cold] #[cold]
#[inline(never)] #[inline(never)]
#[lang = "panic_no_unwind"] // needed by codegen for panic in nounwind function #[lang = "panic_no_unwind"] // needed by codegen for panic in nounwind function
#[cfg_attr(not(bootstrap), rustc_nounwind)]
#[cfg_attr(bootstrap, rustc_allocator_nounwind)]
fn panic_no_unwind() -> ! { fn panic_no_unwind() -> ! {
panic_str_nounwind("panic in a function that cannot unwind")
}
/// Like panic_fmt, but without unwinding and track_caller to reduce the impact on codesize.
/// Also just works on `str`, as a `fmt::Arguments` needs more space to be passed.
#[cold]
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
#[cfg_attr(feature = "panic_immediate_abort", inline)]
#[cfg_attr(not(bootstrap), rustc_nounwind)]
#[cfg_attr(bootstrap, rustc_allocator_nounwind)]
pub fn panic_str_nounwind(msg: &'static str) -> ! {
if cfg!(feature = "panic_immediate_abort") { if cfg!(feature = "panic_immediate_abort") {
super::intrinsics::abort() super::intrinsics::abort()
} }
@ -102,7 +117,8 @@ fn panic_no_unwind() -> ! {
} }
// PanicInfo with the `can_unwind` flag set to false forces an abort. // PanicInfo with the `can_unwind` flag set to false forces an abort.
let fmt = format_args!("panic in a function that cannot unwind"); let pieces = [msg];
let fmt = fmt::Arguments::new_v1(&pieces, &[]);
let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), false); let pi = PanicInfo::internal_constructor(Some(&fmt), Location::caller(), false);
// SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call. // SAFETY: `panic_impl` is defined in safe Rust code and thus is safe to call.