Restrict the spilling of scalable types to the problematic ones.

Rather than not spilling any scalable SIMD types for debug info, we
only avoid spilling the ones that are going to cause a problem.
Currently the only ones known to cause a problem are the internal
svbool types for AArch64.

Author: JamieCunliffe

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -350,10 +350,23 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 if attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
                     return;
                 }
-                // FIXME: Don't spill scalable simd, this works for most of them however,
-                // some intermediate types can't be spilled e.g. `<vscale x 4 x i1>`
-                if operand.layout.ty.is_scalable_simd() {
-                    return;
+
+                // LLVM doesn't handle stores on some of the internal SVE types that we are required
+                // to use. Spilling to the stack here to create debug info for them will cause
+                // errors during instruction selection. The types that can't be spilled are an
+                // internal implementation detail to the intrinsic, the user should never see these
+                // types, and therefore shouldn't need any debug info for them.
+                if operand.layout.ty.is_scalable_simd() && bx.sess().target.arch == "aarch64" {
+                    if let ty::Adt(adt, args) = &operand.layout.ty.kind() {
+                        if let Some(f0) = adt.non_enum_variant().fields.get(FieldIdx::from_u32(0)) {
+                            let f0_ty = f0.ty(bx.tcx(), args);
+                            if let ty::Slice(e_ty) = f0_ty.kind() {
+                                if e_ty.is_bool() && adt.repr().scalable != Some(16) {
+                                    return;
+                                }
+                            }
+                        }
+                    }
                 }
 
                 Self::spill_operand_to_stack(*operand, name, bx)