Rollup merge of #121598 - RalfJung:catch_unwind, r=oli-obk

rename 'try' intrinsic to 'catch_unwind'

The intrinsic has nothing to do with `try` blocks, and corresponds to the stable `catch_unwind` function, so this makes a lot more sense IMO.

Also rename Miri's special function while we are at it, to reflect the level of abstraction it works on: it's an unwinding mechanism, on which Rust implements panics.

src/concurrency/thread.rs

@@ -143,7 +143,7 @@ pub struct Thread<'mir, 'tcx> {
     join_status: ThreadJoinStatus,
 
     /// Stack of active panic payloads for the current thread. Used for storing
-    /// the argument of the call to `miri_start_panic` (the panic payload) when unwinding.
+    /// the argument of the call to `miri_start_unwind` (the panic payload) when unwinding.
     /// This is pointer-sized, and matches the `Payload` type in `src/libpanic_unwind/miri.rs`.
     ///
     /// In real unwinding, the payload gets passed as an argument to the landing pad,

src/shims/foreign_items.rs

@@ -68,9 +68,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let ret = match ret {
             None =>
                 match link_name.as_str() {
-                    "miri_start_panic" => {
-                        // `check_shim` happens inside `handle_miri_start_panic`.
-                        this.handle_miri_start_panic(abi, link_name, args, unwind)?;
+                    "miri_start_unwind" => {
+                        // `check_shim` happens inside `handle_miri_start_unwind`.
+                        this.handle_miri_start_unwind(abi, link_name, args, unwind)?;
                         return Ok(None);
                     }
                     // This matches calls to the foreign item `panic_impl`.

src/shims/intrinsics/mod.rs

@@ -54,7 +54,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
 
         // Some intrinsics are special and need the "ret".
         match intrinsic_name {
-            "try" => return this.handle_try(args, dest, ret),
+            "catch_unwind" => return this.handle_catch_unwind(args, dest, ret),
             _ => {}
         }
 

src/shims/panic.rs

@@ -3,9 +3,9 @@
 //! The core pieces of the runtime are:
 //! - An implementation of `__rust_maybe_catch_panic` that pushes the invoked stack frame with
 //!   some extra metadata derived from the panic-catching arguments of `__rust_maybe_catch_panic`.
-//! - A hack in `libpanic_unwind` that calls the `miri_start_panic` intrinsic instead of the
+//! - A hack in `libpanic_unwind` that calls the `miri_start_unwind` intrinsic instead of the
 //!   target-native panic runtime. (This lives in the rustc repo.)
-//! - An implementation of `miri_start_panic` that stores its argument (the panic payload), and then
+//! - An implementation of `miri_start_unwind` that stores its argument (the panic payload), and then
 //!   immediately returns, but on the *unwind* edge (not the normal return edge), thus initiating unwinding.
 //! - A hook executed each time a frame is popped, such that if the frame pushed by `__rust_maybe_catch_panic`
 //!   gets popped *during unwinding*, we take the panic payload and store it according to the extra
@@ -44,9 +44,9 @@ impl VisitProvenance for CatchUnwindData<'_> {
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
-    /// Handles the special `miri_start_panic` intrinsic, which is called
+    /// Handles the special `miri_start_unwind` intrinsic, which is called
     /// by libpanic_unwind to delegate the actual unwinding process to Miri.
-    fn handle_miri_start_panic(
+    fn handle_miri_start_unwind(
         &mut self,
         abi: Abi,
         link_name: Symbol,
@@ -55,7 +55,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
 
-        trace!("miri_start_panic: {:?}", this.frame().instance);
+        trace!("miri_start_unwind: {:?}", this.frame().instance);
 
         // Get the raw pointer stored in arg[0] (the panic payload).
         let [payload] = this.check_shim(abi, Abi::Rust, link_name, args)?;
@@ -69,7 +69,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     }
 
     /// Handles the `try` intrinsic, the underlying implementation of `std::panicking::try`.
-    fn handle_try(
+    fn handle_catch_unwind(
         &mut self,
         args: &[OpTy<'tcx, Provenance>],
         dest: &PlaceTy<'tcx, Provenance>,
@@ -85,7 +85,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         // what that is), and returns 1.
         // The `payload` is passed (by libstd) to `__rust_panic_cleanup`, which is then expected to
         // return a `Box<dyn Any + Send + 'static>`.
-        // In Miri, `miri_start_panic` is passed exactly that type, so we make the `payload` simply
+        // In Miri, `miri_start_unwind` is passed exactly that type, so we make the `payload` simply
         // a pointer to `Box<dyn Any + Send + 'static>`.
 
         // Get all the arguments.
@@ -141,7 +141,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             // We set the return value of `try` to 1, since there was a panic.
             this.write_scalar(Scalar::from_i32(1), &catch_unwind.dest)?;
 
-            // The Thread's `panic_payload` holds what was passed to `miri_start_panic`.
+            // The Thread's `panic_payload` holds what was passed to `miri_start_unwind`.
             // This is exactly the second argument we need to pass to `catch_fn`.
             let payload = this.active_thread_mut().panic_payloads.pop().unwrap();
 

tests/fail/function_calls/check_callback_abi.rs

@@ -8,7 +8,7 @@ fn main() {
     unsafe {
         // Make sure we check the ABI when Miri itself invokes a function
         // as part of a shim implementation.
-        std::intrinsics::r#try(
+        std::intrinsics::catch_unwind(
             //~^ ERROR: calling a function with ABI C using caller ABI Rust
             std::mem::transmute::<extern "C" fn(*mut u8), _>(try_fn),
             std::ptr::null_mut(),

tests/fail/function_calls/check_callback_abi.stderr

@@ -1,7 +1,7 @@
 error: Undefined Behavior: calling a function with ABI C using caller ABI Rust
   --> $DIR/check_callback_abi.rs:LL:CC
    |
-LL | /         std::intrinsics::r#try(
+LL | /         std::intrinsics::catch_unwind(
 LL | |
 LL | |             std::mem::transmute::<extern "C" fn(*mut u8), _>(try_fn),
 LL | |             std::ptr::null_mut(),

tests/fail/panic/bad_miri_start_panic.rs → tests/fail/panic/bad_miri_start_unwind.rs

@@ -3,10 +3,10 @@
 #![feature(c_unwind)]
 
 extern "C" {
-    fn miri_start_panic(payload: *mut u8) -> !;
+    fn miri_start_unwind(payload: *mut u8) -> !;
 }
 
 fn main() {
-    unsafe { miri_start_panic(&mut 0) }
+    unsafe { miri_start_unwind(&mut 0) }
     //~^ ERROR: unwinding past a stack frame that does not allow unwinding
 }

tests/fail/panic/bad_miri_start_panic.stderr → tests/fail/panic/bad_miri_start_unwind.stderr

@@ -1,15 +1,15 @@
 WARNING: the flag `-Zmiri-disable-abi-check` is deprecated and planned to be removed.
 If you have a use-case for it, please file an issue.
 error: Undefined Behavior: unwinding past a stack frame that does not allow unwinding
-  --> $DIR/bad_miri_start_panic.rs:LL:CC
+  --> $DIR/bad_miri_start_unwind.rs:LL:CC
    |
-LL |     unsafe { miri_start_panic(&mut 0) }
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^ unwinding past a stack frame that does not allow unwinding
+LL |     unsafe { miri_start_unwind(&mut 0) }
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^ unwinding past a stack frame that does not allow unwinding
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/bad_miri_start_panic.rs:LL:CC
+   = note: inside `main` at $DIR/bad_miri_start_unwind.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/panic/unwind_panic_abort.rs

@@ -3,11 +3,11 @@
 //! Unwinding despite `-C panic=abort` is an error.
 
 extern "Rust" {
-    fn miri_start_panic(payload: *mut u8) -> !;
+    fn miri_start_unwind(payload: *mut u8) -> !;
 }
 
 fn main() {
     unsafe {
-        miri_start_panic(&mut 0); //~ ERROR: unwinding past a stack frame that does not allow unwinding
+        miri_start_unwind(&mut 0); //~ ERROR: unwinding past a stack frame that does not allow unwinding
     }
 }

tests/fail/panic/unwind_panic_abort.stderr

@@ -1,8 +1,8 @@
 error: Undefined Behavior: unwinding past a stack frame that does not allow unwinding
   --> $DIR/unwind_panic_abort.rs:LL:CC
    |
-LL |         miri_start_panic(&mut 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^ unwinding past a stack frame that does not allow unwinding
+LL |         miri_start_unwind(&mut 0);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^ unwinding past a stack frame that does not allow unwinding
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/pass/function_calls/disable_abi_check.rs

@@ -15,7 +15,7 @@ fn main() {
     unsafe {
         let _ = malloc(0);
         std::mem::transmute::<fn(), extern "C" fn()>(foo)();
-        std::intrinsics::r#try(
+        std::intrinsics::catch_unwind(
             std::mem::transmute::<extern "C" fn(*mut u8), _>(try_fn),
             std::ptr::null_mut(),
             |_, _| unreachable!(),

tests/utils/miri_extern.rs

@@ -56,7 +56,7 @@ extern "Rust" {
     ///
     /// This is internal and unstable and should not be used; we give it here
     /// just to be complete.
-    pub fn miri_start_panic(payload: *mut u8) -> !;
+    pub fn miri_start_unwind(payload: *mut u8) -> !;
 
     /// Miri-provided extern function to get the internal unique identifier for the allocation that a pointer
     /// points to. If this pointer is invalid (not pointing to an allocation), interpretation will abort.