Move some code around

Author: bjorn3

compiler/rustc_middle/src/ty/layout.rs

@@ -2514,7 +2514,7 @@ where
         extra_args: &[Ty<'tcx>],
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
-        mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>,
+        make_self_ptr_thin: bool,
     ) -> Self;
     fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
 }
@@ -2574,9 +2574,7 @@ where
         // Assume that fn pointers may always unwind
         let codegen_fn_attr_flags = CodegenFnAttrFlags::UNWIND;
 
-        call::FnAbi::new_internal(cx, sig, extra_args, None, codegen_fn_attr_flags, |ty, _| {
-            ArgAbi::new(cx.layout_of(ty))
-        })
+        call::FnAbi::new_internal(cx, sig, extra_args, None, codegen_fn_attr_flags, false)
     }
 
     fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
@@ -2590,55 +2588,14 @@ where
 
         let attrs = cx.tcx().codegen_fn_attrs(instance.def_id()).flags;
 
-        call::FnAbi::new_internal(cx, sig, extra_args, caller_location, attrs, |ty, arg_idx| {
-            let mut layout = cx.layout_of(ty);
-            // Don't pass the vtable, it's not an argument of the virtual fn.
-            // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
-            // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
-            if let (ty::InstanceDef::Virtual(..), Some(0)) = (&instance.def, arg_idx) {
-                let fat_pointer_ty = if layout.is_unsized() {
-                    // unsized `self` is passed as a pointer to `self`
-                    // FIXME (mikeyhew) change this to use &own if it is ever added to the language
-                    cx.tcx().mk_mut_ptr(layout.ty)
-                } else {
-                    match layout.abi {
-                        Abi::ScalarPair(..) => (),
-                        _ => bug!("receiver type has unsupported layout: {:?}", layout),
-                    }
-
-                    // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
-                    // with a Scalar (not ScalarPair) ABI. This is a hack that is understood
-                    // elsewhere in the compiler as a method on a `dyn Trait`.
-                    // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
-                    // get a built-in pointer type
-                    let mut fat_pointer_layout = layout;
-                    'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
-                        && !fat_pointer_layout.ty.is_region_ptr()
-                    {
-                        for i in 0..fat_pointer_layout.fields.count() {
-                            let field_layout = fat_pointer_layout.field(cx, i);
-
-                            if !field_layout.is_zst() {
-                                fat_pointer_layout = field_layout;
-                                continue 'descend_newtypes;
-                            }
-                        }
-
-                        bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
-                    }
-
-                    fat_pointer_layout.ty
-                };
-
-                // we now have a type like `*mut RcBox<dyn Trait>`
-                // change its layout to that of `*mut ()`, a thin pointer, but keep the same type
-                // this is understood as a special case elsewhere in the compiler
-                let unit_pointer_ty = cx.tcx().mk_mut_ptr(cx.tcx().mk_unit());
-                layout = cx.layout_of(unit_pointer_ty);
-                layout.ty = fat_pointer_ty;
-            }
-            ArgAbi::new(layout)
-        })
+        call::FnAbi::new_internal(
+            cx,
+            sig,
+            extra_args,
+            caller_location,
+            attrs,
+            matches!(instance.def, ty::InstanceDef::Virtual(..)),
+        )
     }
 
     fn new_internal(
@@ -2647,7 +2604,7 @@ where
         extra_args: &[Ty<'tcx>],
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
-        mk_arg_type: impl Fn(Ty<'tcx>, Option<usize>) -> ArgAbi<'tcx, Ty<'tcx>>,
+        force_thin_self_ptr: bool,
     ) -> Self {
         debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
 
@@ -2778,7 +2735,18 @@ where
 
         let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| {
             let is_return = arg_idx.is_none();
-            let mut arg = mk_arg_type(ty, arg_idx);
+
+            let layout = if force_thin_self_ptr && arg_idx == Some(0) {
+                // Don't pass the vtable, it's not an argument of the virtual fn.
+                // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
+                // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
+                make_thin_self_ptr(cx, cx.layout_of(ty))
+            } else {
+                cx.layout_of(ty)
+            };
+
+            let mut arg = ArgAbi::new(layout);
+
             if arg.layout.is_zst() {
                 // For some forsaken reason, x86_64-pc-windows-gnu
                 // doesn't ignore zero-sized struct arguments.
@@ -2912,3 +2880,56 @@ where
         }
     }
 }
+
+fn make_thin_self_ptr<'tcx, C>(
+    cx: &C,
+    mut layout: TyAndLayout<'tcx>,
+) -> TyAndLayout<'tcx>
+where C: LayoutOf<Ty = Ty<'tcx>, TyAndLayout = TyAndLayout<'tcx>>
+        //+ HasDataLayout
+        //+ HasTargetSpec
+        + HasTyCtxt<'tcx>
+        + HasParamEnv<'tcx>
+{
+    let fat_pointer_ty = if layout.is_unsized() {
+        // unsized `self` is passed as a pointer to `self`
+        // FIXME (mikeyhew) change this to use &own if it is ever added to the language
+        cx.tcx().mk_mut_ptr(layout.ty)
+    } else {
+        match layout.abi {
+            Abi::ScalarPair(..) => (),
+            _ => bug!("receiver type has unsupported layout: {:?}", layout),
+        }
+
+        // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
+        // with a Scalar (not ScalarPair) ABI. This is a hack that is understood
+        // elsewhere in the compiler as a method on a `dyn Trait`.
+        // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
+        // get a built-in pointer type
+        let mut fat_pointer_layout = layout;
+        'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
+            && !fat_pointer_layout.ty.is_region_ptr()
+        {
+            for i in 0..fat_pointer_layout.fields.count() {
+                let field_layout = fat_pointer_layout.field(cx, i);
+
+                if !field_layout.is_zst() {
+                    fat_pointer_layout = field_layout;
+                    continue 'descend_newtypes;
+                }
+            }
+
+            bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
+        }
+
+        fat_pointer_layout.ty
+    };
+
+    // we now have a type like `*mut RcBox<dyn Trait>`
+    // change its layout to that of `*mut ()`, a thin pointer, but keep the same type
+    // this is understood as a special case elsewhere in the compiler
+    let unit_pointer_ty = cx.tcx().mk_mut_ptr(cx.tcx().mk_unit());
+    layout = cx.layout_of(unit_pointer_ty);
+    layout.ty = fat_pointer_ty;
+    layout
+}