Rollup merge of #128687 - RalfJung:interpret-call-refactor, r=WaffleLapkin

interpret: refactor function call handling to be better-abstracted

Add a new function `init_stack_frame` that pushes a stack frame and passes the arguments, and use that basically everywhere that the raw underlying `push_stack_frame` used to be called. This splits the previous monster function `eval_fn_call` into two parts: figuring out the MIR to call and the arguments to pass, and then actually setting up the stack frame.

Also re-organize the files a bit:
- The previous `terminator.rs` is split into a new `call.rs` with all the argument-passing logic, and the rest goes into `step.rs` where the other main dispatcher functions already live (in particular, `eval_statement`).
- All the stack frame handling from `eval_context.rs` is moved to a new `stack.rs`.

Author: matthiaskrgr

src/concurrency/thread.rs

@@ -256,7 +256,7 @@ pub struct Thread<'tcx> {
     /// which then forwards it to 'Resume'. However this argument is implicit in MIR,
     /// so we have to store it out-of-band. When there are multiple active unwinds,
     /// the innermost one is always caught first, so we can store them as a stack.
-    pub(crate) panic_payloads: Vec<Scalar>,
+    pub(crate) panic_payloads: Vec<ImmTy<'tcx>>,
 
     /// Last OS error location in memory. It is a 32-bit integer.
     pub(crate) last_error: Option<MPlaceTy<'tcx>>,
@@ -377,10 +377,6 @@ impl VisitProvenance for Frame<'_, Provenance, FrameExtra<'_>> {
             return_place,
             locals,
             extra,
-            body: _,
-            instance: _,
-            return_to_block: _,
-            loc: _,
             // There are some private fields we cannot access; they contain no tags.
             ..
         } = self;
@@ -952,7 +948,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         this.call_function(
             instance,
             start_abi,
-            &[*func_arg],
+            &[func_arg],
             Some(&ret_place),
             StackPopCleanup::Root { cleanup: true },
         )?;

src/eval.rs

@@ -307,7 +307,8 @@ pub fn create_ecx<'tcx>(
     // First argument is constructed later, because it's skipped if the entry function uses #[start].
 
     // Second argument (argc): length of `config.args`.
-    let argc = Scalar::from_target_usize(u64::try_from(config.args.len()).unwrap(), &ecx);
+    let argc =
+        ImmTy::from_int(i64::try_from(config.args.len()).unwrap(), ecx.machine.layouts.isize);
     // Third argument (`argv`): created from `config.args`.
     let argv = {
         // Put each argument in memory, collect pointers.
@@ -334,21 +335,19 @@ pub fn create_ecx<'tcx>(
             ecx.write_immediate(arg, &place)?;
         }
         ecx.mark_immutable(&argvs_place);
-        // A pointer to that place is the 3rd argument for main.
-        let argv = argvs_place.to_ref(&ecx);
         // Store `argc` and `argv` for macOS `_NSGetArg{c,v}`.
         {
             let argc_place =
                 ecx.allocate(ecx.machine.layouts.isize, MiriMemoryKind::Machine.into())?;
-            ecx.write_scalar(argc, &argc_place)?;
+            ecx.write_immediate(*argc, &argc_place)?;
             ecx.mark_immutable(&argc_place);
             ecx.machine.argc = Some(argc_place.ptr());
 
             let argv_place = ecx.allocate(
                 ecx.layout_of(Ty::new_imm_ptr(tcx, tcx.types.unit))?,
                 MiriMemoryKind::Machine.into(),
             )?;
-            ecx.write_immediate(argv, &argv_place)?;
+            ecx.write_pointer(argvs_place.ptr(), &argv_place)?;
             ecx.mark_immutable(&argv_place);
             ecx.machine.argv = Some(argv_place.ptr());
         }
@@ -369,7 +368,7 @@ pub fn create_ecx<'tcx>(
             }
             ecx.mark_immutable(&cmd_place);
         }
-        argv
+        ecx.mplace_to_ref(&argvs_place)?
     };
 
     // Return place (in static memory so that it does not count as leak).
@@ -405,10 +404,14 @@ pub fn create_ecx<'tcx>(
                 start_instance,
                 Abi::Rust,
                 &[
-                    Scalar::from_pointer(main_ptr, &ecx).into(),
-                    argc.into(),
+                    ImmTy::from_scalar(
+                        Scalar::from_pointer(main_ptr, &ecx),
+                        // FIXME use a proper fn ptr type
+                        ecx.machine.layouts.const_raw_ptr,
+                    ),
+                    argc,
                     argv,
-                    Scalar::from_u8(sigpipe).into(),
+                    ImmTy::from_uint(sigpipe, ecx.machine.layouts.u8),
                 ],
                 Some(&ret_place),
                 StackPopCleanup::Root { cleanup: true },
@@ -418,7 +421,7 @@ pub fn create_ecx<'tcx>(
             ecx.call_function(
                 entry_instance,
                 Abi::Rust,
-                &[argc.into(), argv],
+                &[argc, argv],
                 Some(&ret_place),
                 StackPopCleanup::Root { cleanup: true },
             )?;

src/helpers.rs

@@ -12,13 +12,14 @@ use rustc_apfloat::Float;
 use rustc_hir::{
     def::{DefKind, Namespace},
     def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE},
+    Safety,
 };
 use rustc_index::IndexVec;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::mir;
-use rustc_middle::ty::layout::MaybeResult;
+use rustc_middle::ty::layout::{FnAbiOf, MaybeResult};
 use rustc_middle::ty::{
     self,
     layout::{LayoutOf, TyAndLayout},
@@ -492,48 +493,38 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         &mut self,
         f: ty::Instance<'tcx>,
         caller_abi: Abi,
-        args: &[Immediate<Provenance>],
+        args: &[ImmTy<'tcx>],
         dest: Option<&MPlaceTy<'tcx>>,
         stack_pop: StackPopCleanup,
     ) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
-        let param_env = ty::ParamEnv::reveal_all(); // in Miri this is always the param_env we use... and this.param_env is private.
-        let callee_abi = f.ty(*this.tcx, param_env).fn_sig(*this.tcx).abi();
-        if callee_abi != caller_abi {
-            throw_ub_format!(
-                "calling a function with ABI {} using caller ABI {}",
-                callee_abi.name(),
-                caller_abi.name()
-            )
-        }
 
-        // Push frame.
+        // Get MIR.
         let mir = this.load_mir(f.def, None)?;
         let dest = match dest {
             Some(dest) => dest.clone(),
             None => MPlaceTy::fake_alloc_zst(this.layout_of(mir.return_ty())?),
         };
-        this.push_stack_frame(f, mir, &dest, stack_pop)?;
-
-        // Initialize arguments.
-        let mut callee_args = this.frame().body.args_iter();
-        for arg in args {
-            let local = callee_args
-                .next()
-                .ok_or_else(|| err_ub_format!("callee has fewer arguments than expected"))?;
-            // Make the local live, and insert the initial value.
-            this.storage_live(local)?;
-            let callee_arg = this.local_to_place(local)?;
-            this.write_immediate(*arg, &callee_arg)?;
-        }
-        if callee_args.next().is_some() {
-            throw_ub_format!("callee has more arguments than expected");
-        }
-
-        // Initialize remaining locals.
-        this.storage_live_for_always_live_locals()?;
 
-        Ok(())
+        // Construct a function pointer type representing the caller perspective.
+        let sig = this.tcx.mk_fn_sig(
+            args.iter().map(|a| a.layout.ty),
+            dest.layout.ty,
+            /*c_variadic*/ false,
+            Safety::Safe,
+            caller_abi,
+        );
+        let caller_fn_abi = this.fn_abi_of_fn_ptr(ty::Binder::dummy(sig), ty::List::empty())?;
+
+        this.init_stack_frame(
+            f,
+            mir,
+            caller_fn_abi,
+            &args.iter().map(|a| FnArg::Copy(a.clone().into())).collect::<Vec<_>>(),
+            /*with_caller_location*/ false,
+            &dest,
+            stack_pop,
+        )
     }
 
     /// Visits the memory covered by `place`, sensitive to freezing: the 2nd parameter
@@ -1114,12 +1105,12 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // Make an attempt to get at the instance of the function this is inlined from.
         let instance: Option<_> = try {
             let scope = frame.current_source_info()?.scope;
-            let inlined_parent = frame.body.source_scopes[scope].inlined_parent_scope?;
-            let source = &frame.body.source_scopes[inlined_parent];
+            let inlined_parent = frame.body().source_scopes[scope].inlined_parent_scope?;
+            let source = &frame.body().source_scopes[inlined_parent];
             source.inlined.expect("inlined_parent_scope points to scope without inline info").0
         };
         // Fall back to the instance of the function itself.
-        let instance = instance.unwrap_or(frame.instance);
+        let instance = instance.unwrap_or(frame.instance());
         // Now check the crate it is in. We could try to be clever here and e.g. check if this is
         // the same crate as `start_fn`, but that would not work for running std tests in Miri, so
         // we'd need some more hacks anyway. So we just check the name of the crate. If someone
@@ -1359,9 +1350,9 @@ impl<'tcx> MiriMachine<'tcx> {
 
     /// This is the source of truth for the `is_user_relevant` flag in our `FrameExtra`.
     pub fn is_user_relevant(&self, frame: &Frame<'tcx, Provenance>) -> bool {
-        let def_id = frame.instance.def_id();
+        let def_id = frame.instance().def_id();
         (def_id.is_local() || self.local_crates.contains(&def_id.krate))
-            && !frame.instance.def.requires_caller_location(self.tcx)
+            && !frame.instance().def.requires_caller_location(self.tcx)
     }
 }
 

src/machine.rs

@@ -1352,7 +1352,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
     ) -> InterpResult<'tcx, Frame<'tcx, Provenance, FrameExtra<'tcx>>> {
         // Start recording our event before doing anything else
         let timing = if let Some(profiler) = ecx.machine.profiler.as_ref() {
-            let fn_name = frame.instance.to_string();
+            let fn_name = frame.instance().to_string();
             let entry = ecx.machine.string_cache.entry(fn_name.clone());
             let name = entry.or_insert_with(|| profiler.alloc_string(&*fn_name));
 
@@ -1443,7 +1443,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
         // tracing-tree can autoamtically annotate scope changes, but it gets very confused by our
         // concurrency and what it prints is just plain wrong. So we print our own information
         // instead. (Cc https://github.com/rust-lang/miri/issues/2266)
-        info!("Leaving {}", ecx.frame().instance);
+        info!("Leaving {}", ecx.frame().instance());
         Ok(())
     }
 
@@ -1473,7 +1473,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
         // Needs to be done after dropping frame to show up on the right nesting level.
         // (Cc https://github.com/rust-lang/miri/issues/2266)
         if !ecx.active_thread_stack().is_empty() {
-            info!("Continuing in {}", ecx.frame().instance);
+            info!("Continuing in {}", ecx.frame().instance());
         }
         res
     }
@@ -1486,7 +1486,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
         let Some(Provenance::Concrete { alloc_id, .. }) = mplace.ptr().provenance else {
             panic!("after_local_allocated should only be called on fresh allocations");
         };
-        let local_decl = &ecx.frame().body.local_decls[local];
+        let local_decl = &ecx.frame().body().local_decls[local];
         let span = local_decl.source_info.span;
         ecx.machine.allocation_spans.borrow_mut().insert(alloc_id, (span, None));
         Ok(())

src/shims/backtrace.rs

@@ -46,8 +46,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let mut data = Vec::new();
         for frame in this.active_thread_stack().iter().rev() {
             // Match behavior of debuginfo (`FunctionCx::adjusted_span_and_dbg_scope`).
-            let span = hygiene::walk_chain_collapsed(frame.current_span(), frame.body.span);
-            data.push((frame.instance, span.lo()));
+            let span = hygiene::walk_chain_collapsed(frame.current_span(), frame.body().span);
+            data.push((frame.instance(), span.lo()));
         }
 
         let ptrs: Vec<_> = data

src/shims/panic.rs

@@ -25,7 +25,7 @@ pub struct CatchUnwindData<'tcx> {
     /// The `catch_fn` callback to call in case of a panic.
     catch_fn: Pointer,
     /// The `data` argument for that callback.
-    data: Scalar,
+    data: ImmTy<'tcx>,
     /// The return place from the original call to `try`.
     dest: MPlaceTy<'tcx>,
     /// The return block from the original call to `try`.
@@ -48,9 +48,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn handle_miri_start_unwind(&mut self, payload: &OpTy<'tcx>) -> InterpResult<'tcx> {
         let this = self.eval_context_mut();
 
-        trace!("miri_start_unwind: {:?}", this.frame().instance);
+        trace!("miri_start_unwind: {:?}", this.frame().instance());
 
-        let payload = this.read_scalar(payload)?;
+        let payload = this.read_immediate(payload)?;
         let thread = this.active_thread_mut();
         thread.panic_payloads.push(payload);
 
@@ -80,7 +80,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // Get all the arguments.
         let [try_fn, data, catch_fn] = check_arg_count(args)?;
         let try_fn = this.read_pointer(try_fn)?;
-        let data = this.read_scalar(data)?;
+        let data = this.read_immediate(data)?;
         let catch_fn = this.read_pointer(catch_fn)?;
 
         // Now we make a function call, and pass `data` as first and only argument.
@@ -89,7 +89,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         this.call_function(
             f_instance,
             Abi::Rust,
-            &[data.into()],
+            &[data.clone()],
             None,
             // Directly return to caller.
             StackPopCleanup::Goto { ret, unwind: mir::UnwindAction::Continue },
@@ -124,7 +124,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             // and we are unwinding, so we should catch that.
             trace!(
                 "unwinding: found catch_panic frame during unwinding: {:?}",
-                this.frame().instance
+                this.frame().instance()
             );
 
             // We set the return value of `try` to 1, since there was a panic.
@@ -140,7 +140,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             this.call_function(
                 f_instance,
                 Abi::Rust,
-                &[catch_unwind.data.into(), payload.into()],
+                &[catch_unwind.data, payload],
                 None,
                 // Directly return to caller of `try`.
                 StackPopCleanup::Goto {
@@ -169,7 +169,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         this.call_function(
             panic,
             Abi::Rust,
-            &[msg.to_ref(this)],
+            &[this.mplace_to_ref(&msg)?],
             None,
             StackPopCleanup::Goto { ret: None, unwind },
         )
@@ -188,7 +188,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         this.call_function(
             panic,
             Abi::Rust,
-            &[msg.to_ref(this)],
+            &[this.mplace_to_ref(&msg)?],
             None,
             StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
         )
@@ -207,17 +207,17 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Forward to `panic_bounds_check` lang item.
 
                 // First arg: index.
-                let index = this.read_scalar(&this.eval_operand(index, None)?)?;
+                let index = this.read_immediate(&this.eval_operand(index, None)?)?;
                 // Second arg: len.
-                let len = this.read_scalar(&this.eval_operand(len, None)?)?;
+                let len = this.read_immediate(&this.eval_operand(len, None)?)?;
 
                 // Call the lang item.
                 let panic_bounds_check = this.tcx.lang_items().panic_bounds_check_fn().unwrap();
                 let panic_bounds_check = ty::Instance::mono(this.tcx.tcx, panic_bounds_check);
                 this.call_function(
                     panic_bounds_check,
                     Abi::Rust,
-                    &[index.into(), len.into()],
+                    &[index, len],
                     None,
                     StackPopCleanup::Goto { ret: None, unwind },
                 )?;
@@ -226,9 +226,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Forward to `panic_misaligned_pointer_dereference` lang item.
 
                 // First arg: required.
-                let required = this.read_scalar(&this.eval_operand(required, None)?)?;
+                let required = this.read_immediate(&this.eval_operand(required, None)?)?;
                 // Second arg: found.
-                let found = this.read_scalar(&this.eval_operand(found, None)?)?;
+                let found = this.read_immediate(&this.eval_operand(found, None)?)?;
 
                 // Call the lang item.
                 let panic_misaligned_pointer_dereference =
@@ -238,7 +238,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.call_function(
                     panic_misaligned_pointer_dereference,
                     Abi::Rust,
-                    &[required.into(), found.into()],
+                    &[required, found],
                     None,
                     StackPopCleanup::Goto { ret: None, unwind },
                 )?;