pub fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize;
/// Internal hook used by Miri to implement unwinding.
- /// Compiles to a NOP during non-Miri codegen.
+ /// ICEs when encountered during non-Miri codegen.
///
- /// Perma-unstable: do not use
- pub fn miri_start_panic(data: *mut (dyn crate::any::Any + crate::marker::Send)) -> ();
+ /// The `payload` ptr here will be exactly the one `do_catch` gets passed by `try`.
+ ///
+ /// Perma-unstable: do not use.
+ pub fn miri_start_panic(payload: *mut u8) -> !;
}
// Some functions are defined here because they accidentally got made
#![panic_runtime]
#![feature(panic_runtime)]
+// `real_imp` is unused with Miri, so silence warnings.
+#![cfg_attr(miri, allow(dead_code))]
+
use alloc::boxed::Box;
use core::any::Any;
use core::panic::BoxMeUp;
cfg_if::cfg_if! {
if #[cfg(target_os = "emscripten")] {
#[path = "emcc.rs"]
- mod imp;
+ mod real_imp;
} else if #[cfg(target_arch = "wasm32")] {
#[path = "dummy.rs"]
- mod imp;
+ mod real_imp;
} else if #[cfg(target_os = "hermit")] {
#[path = "hermit.rs"]
- mod imp;
+ mod real_imp;
} else if #[cfg(all(target_env = "msvc", target_arch = "aarch64"))] {
#[path = "dummy.rs"]
- mod imp;
+ mod real_imp;
} else if #[cfg(target_env = "msvc")] {
#[path = "seh.rs"]
- mod imp;
+ mod real_imp;
} else {
// Rust runtime's startup objects depend on these symbols, so make them public.
#[cfg(all(target_os="windows", target_arch = "x86", target_env="gnu"))]
- pub use imp::eh_frame_registry::*;
+ pub use real_imp::eh_frame_registry::*;
#[path = "gcc.rs"]
+ mod real_imp;
+ }
+}
+
+cfg_if::cfg_if! {
+ if #[cfg(miri)] {
+ // Use the Miri runtime.
+ // We still need to also load the normal runtime above, as rustc expects certain lang
+ // items from there to be defined.
+ #[path = "miri.rs"]
mod imp;
+ } else {
+ // Use the real runtime.
+ use real_imp as imp;
}
}
let payload = payload as *mut &mut dyn BoxMeUp;
let payload = (*payload).take_box();
- // Miri panic support: cfg'd out of normal builds just to be sure.
- // When going through normal codegen, `miri_start_panic` is a NOP, so the
- // Miri-enabled sysroot still supports normal unwinding. But when executed in
- // Miri, this line initiates unwinding.
- #[cfg(miri)]
- core::intrinsics::miri_start_panic(payload);
-
imp::panic(Box::from_raw(payload))
}
--- /dev/null
+//! Unwinding panics for Miri.
+use core::any::Any;
+use alloc::boxed::Box;
+
+// The type of the payload that the Miri engine propagates through unwinding for us.
+// Must be pointer-sized.
+type Payload = Box<Box<dyn Any + Send>>;
+
+pub unsafe fn panic(payload: Box<dyn Any + Send>) -> u32 {
+ // The payload we pass to `miri_start_panic` will be exactly the argument we get
+ // in `cleanup` below. So we just box it up once, to get something pointer-sized.
+ let payload_box: Payload = Box::new(payload);
+ core::intrinsics::miri_start_panic(Box::into_raw(payload_box) as *mut u8)
+}
+
+pub unsafe fn cleanup(payload_box: *mut u8) -> Box<dyn Any + Send> {
+ // Recover the underlying `Box`.
+ let payload_box: Payload = Box::from_raw(payload_box as *mut _);
+ *payload_box
+}