Rollup merge of #143528 - RalfJung:stack-pop-cleanup, r=oli-obk

interpret: rename StackPopCleanup

The name `StackPopCleanup` stopped making sense a long time ago IMO -- in the common case, it has nothing to do with "cleanup", and everything with where the program should jump next. If we didn't have unwinding this would be just the return block, but given that we do have unwinding I figured maybe "continuation" would be a good name. This comes up in [continuation-passing style](https://en.wikipedia.org/wiki/Continuation-passing_style) and refers to where the program will *continue* when a function is done. So from a PL perspective it is the most fitting term I think -- but it may be too jargony.

r? `@oli-obk` what do you think?

Author: jieyouxu

src/concurrency/thread.rs

@@ -894,7 +894,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             start_abi,
             &[func_arg],
             Some(&ret_place),
-            StackPopCleanup::Root { cleanup: true },
+            ReturnContinuation::Stop { cleanup: true },
         )?;
 
         // Restore the old active thread frame.

src/eval.rs

@@ -436,7 +436,7 @@ pub fn create_ecx<'tcx>(
                     ImmTy::from_uint(sigpipe, ecx.machine.layouts.u8),
                 ],
                 Some(&ret_place),
-                StackPopCleanup::Root { cleanup: true },
+                ReturnContinuation::Stop { cleanup: true },
             )?;
         }
         MiriEntryFnType::MiriStart => {
@@ -445,7 +445,7 @@ pub fn create_ecx<'tcx>(
                 ExternAbi::Rust,
                 &[argc, argv],
                 Some(&ret_place),
-                StackPopCleanup::Root { cleanup: true },
+                ReturnContinuation::Stop { cleanup: true },
             )?;
         }
     }

src/helpers.rs

@@ -444,7 +444,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         caller_abi: ExternAbi,
         args: &[ImmTy<'tcx>],
         dest: Option<&MPlaceTy<'tcx>>,
-        stack_pop: StackPopCleanup,
+        cont: ReturnContinuation,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
 
@@ -472,7 +472,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             &args.iter().map(|a| FnArg::Copy(a.clone().into())).collect::<Vec<_>>(),
             /*with_caller_location*/ false,
             &dest.into(),
-            stack_pop,
+            cont,
         )
     }
 

src/machine.rs

@@ -1199,7 +1199,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
             ExternAbi::Rust,
             &[],
             None,
-            StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
+            ReturnContinuation::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
         )?;
         interp_ok(())
     }

src/shims/panic.rs

@@ -92,7 +92,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             &[data.clone()],
             None,
             // Directly return to caller.
-            StackPopCleanup::Goto { ret, unwind: mir::UnwindAction::Continue },
+            ReturnContinuation::Goto { ret, unwind: mir::UnwindAction::Continue },
         )?;
 
         // We ourselves will return `0`, eventually (will be overwritten if we catch a panic).
@@ -143,7 +143,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 &[catch_unwind.data, payload],
                 None,
                 // Directly return to caller of `catch_unwind`.
-                StackPopCleanup::Goto {
+                ReturnContinuation::Goto {
                     ret: catch_unwind.ret,
                     // `catch_fn` must not unwind.
                     unwind: mir::UnwindAction::Unreachable,
@@ -172,7 +172,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             ExternAbi::Rust,
             &[this.mplace_to_ref(&msg)?],
             None,
-            StackPopCleanup::Goto { ret: None, unwind },
+            ReturnContinuation::Goto { ret: None, unwind },
         )
     }
 
@@ -191,7 +191,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             ExternAbi::Rust,
             &[this.mplace_to_ref(&msg)?],
             None,
-            StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
+            ReturnContinuation::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
         )
     }
 
@@ -220,7 +220,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     ExternAbi::Rust,
                     &[index, len],
                     None,
-                    StackPopCleanup::Goto { ret: None, unwind },
+                    ReturnContinuation::Goto { ret: None, unwind },
                 )?;
             }
             MisalignedPointerDereference { required, found } => {
@@ -241,7 +241,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     ExternAbi::Rust,
                     &[required, found],
                     None,
-                    StackPopCleanup::Goto { ret: None, unwind },
+                    ReturnContinuation::Goto { ret: None, unwind },
                 )?;
             }
 
@@ -254,7 +254,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     ExternAbi::Rust,
                     &[],
                     None,
-                    StackPopCleanup::Goto { ret: None, unwind },
+                    ReturnContinuation::Goto { ret: None, unwind },
                 )?;
             }
         }

src/shims/tls.rs

@@ -325,7 +325,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             ExternAbi::System { unwind: false },
             &[null_ptr.clone(), ImmTy::from_scalar(reason, this.machine.layouts.u32), null_ptr],
             None,
-            StackPopCleanup::Root { cleanup: true },
+            ReturnContinuation::Stop { cleanup: true },
         )?;
         interp_ok(())
     }
@@ -346,7 +346,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 ExternAbi::C { unwind: false },
                 &[ImmTy::from_scalar(data, this.machine.layouts.mut_raw_ptr)],
                 None,
-                StackPopCleanup::Root { cleanup: true },
+                ReturnContinuation::Stop { cleanup: true },
             )?;
 
             return interp_ok(Poll::Pending);
@@ -383,7 +383,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 ExternAbi::C { unwind: false },
                 &[ImmTy::from_scalar(ptr, this.machine.layouts.mut_raw_ptr)],
                 None,
-                StackPopCleanup::Root { cleanup: true },
+                ReturnContinuation::Stop { cleanup: true },
             )?;
 
             return interp_ok(Poll::Pending);