[AVR] Ensure that function pointers stored within aggregates are annotated with the correct space

Before this patch, a function pointer stored within an aggregate like a
struct or an enum would always have the default address space `0`.

This patch removes this assumption and instead, introspects the inner
type being pointed at, storing the target address space in the PointeeInfo
struct so that downstream users may query it.

Author: dylanmckay

src/librustc_codegen_llvm/type_of.rs

@@ -311,12 +311,13 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
             F64 => cx.type_f64(),
             Pointer => {
                 // If we know the alignment, pick something better than i8.
-                let pointee = if let Some(pointee) = self.pointee_info_at(cx, offset) {
-                    cx.type_pointee_for_align(pointee.align)
-                } else {
-                    cx.type_i8()
-                };
-                cx.type_ptr_to(pointee, AddressSpace::default())
+                let (pointee, address_space) =
+                    if let Some(pointee) = self.pointee_info_at(cx, offset) {
+                        (cx.type_pointee_for_align(pointee.align), pointee.address_space)
+                    } else {
+                        (cx.type_i8(), AddressSpace::default())
+                    };
+                cx.type_ptr_to(pointee, address_space)
             }
         }
     }

src/librustc_middle/ty/layout.rs

@@ -2148,16 +2148,36 @@ where
     }
 
     fn pointee_info_at(this: TyAndLayout<'tcx>, cx: &C, offset: Size) -> Option<PointeeInfo> {
-        match this.ty.kind {
+        let addr_space_of_ty = |ty: Ty<'tcx>| {
+            if ty.is_fn() {
+                cx.data_layout().instruction_address_space
+            } else {
+                AddressSpace::default()
+            }
+        };
+
+        let pointee_info = match this.ty.kind {
             ty::RawPtr(mt) if offset.bytes() == 0 => {
                 cx.layout_of(mt.ty).to_result().ok().map(|layout| PointeeInfo {
                     size: layout.size,
                     align: layout.align.abi,
                     safe: None,
+                    address_space: addr_space_of_ty(mt.ty),
+                })
+            }
+            ty::FnPtr(fn_sig) if offset.bytes() == 0 => {
+                cx.layout_of(cx.tcx().mk_fn_ptr(fn_sig)).to_result().ok().map(|layout| {
+                    PointeeInfo {
+                        size: layout.size,
+                        align: layout.align.abi,
+                        safe: None,
+                        address_space: cx.data_layout().instruction_address_space,
+                    }
                 })
             }
-
             ty::Ref(_, ty, mt) if offset.bytes() == 0 => {
+                let address_space = addr_space_of_ty(ty);
+
                 let tcx = cx.tcx();
                 let is_freeze = ty.is_freeze(tcx, cx.param_env(), DUMMY_SP);
                 let kind = match mt {
@@ -2192,6 +2212,7 @@ where
                     size: layout.size,
                     align: layout.align.abi,
                     safe: Some(kind),
+                    address_space,
                 })
             }
 
@@ -2236,7 +2257,9 @@ where
                             result = field.to_result().ok().and_then(|field| {
                                 if ptr_end <= field_start + field.size {
                                     // We found the right field, look inside it.
-                                    field.pointee_info_at(cx, offset - field_start)
+                                    let field_info =
+                                        field.pointee_info_at(cx, offset - field_start);
+                                    field_info
                                 } else {
                                     None
                                 }
@@ -2259,7 +2282,14 @@ where
 
                 result
             }
-        }
+        };
+
+        debug!(
+            "pointee_info_at (offset={:?}, type kind: {:?}) => {:?}",
+            offset, this.ty.kind, pointee_info
+        );
+
+        pointee_info
     }
 }
 

src/librustc_target/abi/mod.rs

@@ -1024,7 +1024,7 @@ impl<T, E> MaybeResult<T> for Result<T, E> {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum PointerKind {
     /// Most general case, we know no restrictions to tell LLVM.
     Shared,
@@ -1039,11 +1039,12 @@ pub enum PointerKind {
     UniqueOwned,
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 pub struct PointeeInfo {
     pub size: Size,
     pub align: Align,
     pub safe: Option<PointerKind>,
+    pub address_space: AddressSpace,
 }
 
 pub trait TyAndLayoutMethods<'a, C: LayoutOf<Ty = Self>>: Sized {