Rollup merge of #118694 - celinval:smir-alloc-methods, r=ouz-a

Add instance evaluation and methods to read an allocation in StableMIR

The instance evaluation is needed to handle intrinsics such as `type_id` and `type_name`.

Since we now use Allocation to represent all evaluated constants, provide a few methods to help process the data inside an allocation.

I've also started to add a structured way to get information about the compilation target machine. For now, I've only added information needed to process an allocation.

r? ``````@ouz-a``````

compiler/rustc_smir/src/rustc_smir/alloc.rs

@@ -2,6 +2,7 @@ use rustc_middle::mir::{
     interpret::{alloc_range, AllocRange, Pointer},
     ConstValue,
 };
+use stable_mir::Error;
 
 use crate::rustc_smir::{Stable, Tables};
 use stable_mir::mir::Mutability;
@@ -26,23 +27,35 @@ pub fn new_allocation<'tcx>(
     const_value: ConstValue<'tcx>,
     tables: &mut Tables<'tcx>,
 ) -> Allocation {
-    match const_value {
+    try_new_allocation(ty, const_value, tables).unwrap()
+}
+
+#[allow(rustc::usage_of_qualified_ty)]
+pub fn try_new_allocation<'tcx>(
+    ty: rustc_middle::ty::Ty<'tcx>,
+    const_value: ConstValue<'tcx>,
+    tables: &mut Tables<'tcx>,
+) -> Result<Allocation, Error> {
+    Ok(match const_value {
         ConstValue::Scalar(scalar) => {
             let size = scalar.size();
             let align = tables
                 .tcx
                 .layout_of(rustc_middle::ty::ParamEnv::reveal_all().and(ty))
-                .unwrap()
+                .map_err(|e| e.stable(tables))?
                 .align;
             let mut allocation = rustc_middle::mir::interpret::Allocation::uninit(size, align.abi);
             allocation
                 .write_scalar(&tables.tcx, alloc_range(rustc_target::abi::Size::ZERO, size), scalar)
-                .unwrap();
+                .map_err(|e| e.stable(tables))?;
             allocation.stable(tables)
         }
         ConstValue::ZeroSized => {
-            let align =
-                tables.tcx.layout_of(rustc_middle::ty::ParamEnv::empty().and(ty)).unwrap().align;
+            let align = tables
+                .tcx
+                .layout_of(rustc_middle::ty::ParamEnv::empty().and(ty))
+                .map_err(|e| e.stable(tables))?
+                .align;
             new_empty_allocation(align.abi)
         }
         ConstValue::Slice { data, meta } => {
@@ -51,8 +64,10 @@ pub fn new_allocation<'tcx>(
             let scalar_ptr = rustc_middle::mir::interpret::Scalar::from_pointer(ptr, &tables.tcx);
             let scalar_meta =
                 rustc_middle::mir::interpret::Scalar::from_target_usize(meta, &tables.tcx);
-            let layout =
-                tables.tcx.layout_of(rustc_middle::ty::ParamEnv::reveal_all().and(ty)).unwrap();
+            let layout = tables
+                .tcx
+                .layout_of(rustc_middle::ty::ParamEnv::reveal_all().and(ty))
+                .map_err(|e| e.stable(tables))?;
             let mut allocation =
                 rustc_middle::mir::interpret::Allocation::uninit(layout.size, layout.align.abi);
             allocation
@@ -61,14 +76,14 @@ pub fn new_allocation<'tcx>(
                     alloc_range(rustc_target::abi::Size::ZERO, tables.tcx.data_layout.pointer_size),
                     scalar_ptr,
                 )
-                .unwrap();
+                .map_err(|e| e.stable(tables))?;
             allocation
                 .write_scalar(
                     &tables.tcx,
                     alloc_range(tables.tcx.data_layout.pointer_size, scalar_meta.size()),
                     scalar_meta,
                 )
-                .unwrap();
+                .map_err(|e| e.stable(tables))?;
             allocation.stable(tables)
         }
         ConstValue::Indirect { alloc_id, offset } => {
@@ -76,11 +91,11 @@ pub fn new_allocation<'tcx>(
             let ty_size = tables
                 .tcx
                 .layout_of(rustc_middle::ty::ParamEnv::reveal_all().and(ty))
-                .unwrap()
+                .map_err(|e| e.stable(tables))?
                 .size;
             allocation_filter(&alloc.0, alloc_range(offset, ty_size), tables)
         }
-    }
+    })
 }
 
 /// Creates an `Allocation` only from information within the `AllocRange`.

compiler/rustc_smir/src/rustc_smir/context.rs

@@ -11,18 +11,29 @@ use stable_mir::compiler_interface::Context;
 use stable_mir::mir::alloc::GlobalAlloc;
 use stable_mir::mir::mono::{InstanceDef, StaticDef};
 use stable_mir::mir::Body;
+use stable_mir::target::{MachineInfo, MachineSize};
 use stable_mir::ty::{
     AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, GenericArgs,
-    LineInfo, PolyFnSig, RigidTy, Span, TyKind, VariantDef,
+    LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind, VariantDef,
 };
 use stable_mir::{self, Crate, CrateItem, DefId, Error, Filename, ItemKind, Symbol};
 use std::cell::RefCell;
 
 use crate::rustc_internal::{internal, RustcInternal};
 use crate::rustc_smir::builder::BodyBuilder;
-use crate::rustc_smir::{new_item_kind, smir_crate, Stable, Tables};
+use crate::rustc_smir::{alloc, new_item_kind, smir_crate, Stable, Tables};
 
 impl<'tcx> Context for TablesWrapper<'tcx> {
+    fn target_info(&self) -> MachineInfo {
+        let mut tables = self.0.borrow_mut();
+        MachineInfo {
+            endian: tables.tcx.data_layout.endian.stable(&mut *tables),
+            pointer_width: MachineSize::from_bits(
+                tables.tcx.data_layout.pointer_size.bits().try_into().unwrap(),
+            ),
+        }
+    }
+
     fn entry_fn(&self) -> Option<stable_mir::CrateItem> {
         let mut tables = self.0.borrow_mut();
         let tcx = tables.tcx;
@@ -382,6 +393,21 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         Instance::resolve_closure(tables.tcx, def_id, args_ref, closure_kind).stable(&mut *tables)
     }
 
+    fn eval_instance(&self, def: InstanceDef, const_ty: Ty) -> Result<Allocation, Error> {
+        let mut tables = self.0.borrow_mut();
+        let instance = tables.instances[def];
+        let result = tables.tcx.const_eval_instance(
+            ParamEnv::reveal_all(),
+            instance,
+            Some(tables.tcx.def_span(instance.def_id())),
+        );
+        result
+            .map(|const_val| {
+                alloc::try_new_allocation(const_ty.internal(&mut *tables), const_val, &mut *tables)
+            })
+            .map_err(|e| e.stable(&mut *tables))?
+    }
+
     fn eval_static_initializer(&self, def: StaticDef) -> Result<Allocation, Error> {
         let mut tables = self.0.borrow_mut();
         let def_id = def.0.internal(&mut *tables);

compiler/rustc_smir/src/rustc_smir/convert/error.rs

@@ -0,0 +1,22 @@
+//! Handle the conversion of different internal errors into a stable version.
+//!
+//! Currently we encode everything as [stable_mir::Error], which is represented as a string.
+use crate::rustc_smir::{Stable, Tables};
+use rustc_middle::mir::interpret::AllocError;
+use rustc_middle::ty::layout::LayoutError;
+
+impl<'tcx> Stable<'tcx> for LayoutError<'tcx> {
+    type T = stable_mir::Error;
+
+    fn stable(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        stable_mir::Error::new(format!("{self:?}"))
+    }
+}
+
+impl<'tcx> Stable<'tcx> for AllocError {
+    type T = stable_mir::Error;
+
+    fn stable(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        stable_mir::Error::new(format!("{self:?}"))
+    }
+}

compiler/rustc_smir/src/rustc_smir/convert/mod.rs

@@ -5,6 +5,7 @@ use stable_mir::ty::{IndexedVal, VariantIdx};
 
 use crate::rustc_smir::{Stable, Tables};
 
+mod error;
 mod mir;
 mod ty;
 
@@ -76,3 +77,14 @@ impl<'tcx> Stable<'tcx> for rustc_span::Span {
         tables.create_span(*self)
     }
 }
+
+impl<'tcx> Stable<'tcx> for rustc_abi::Endian {
+    type T = stable_mir::target::Endian;
+
+    fn stable(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            rustc_abi::Endian::Little => stable_mir::target::Endian::Little,
+            rustc_abi::Endian::Big => stable_mir::target::Endian::Big,
+        }
+    }
+}