Change CopyNonOverlapping::codegen_ssa

Fixes copy_non_overlapping codegen_ssa to properly handle pointees,
and use bytes instead of elem count

Author: JulianKnodt

compiler/rustc_codegen_ssa/src/mir/statement.rs

@@ -122,19 +122,21 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             }) => {
                 let dst_val = self.codegen_operand(&mut bx, dst);
                 let src_val = self.codegen_operand(&mut bx, src);
-                let count_val = self.codegen_operand(&mut bx, count);
-                let count = count_val.immediate_or_packed_pair(&mut bx);
-                let dst = dst_val.immediate_or_packed_pair(&mut bx);
-                let src = src_val.immediate_or_packed_pair(&mut bx);
-                let flags = crate::MemFlags::empty();
-                bx.memcpy(
-                    dst,
-                    dst_val.layout.layout.align.pref,
-                    src,
-                    src_val.layout.layout.align.pref,
-                    count,
-                    flags,
-                );
+                let count = self.codegen_operand(&mut bx, count).immediate();
+                let get_val_align = |oper_ref: crate::mir::OperandRef<'_, _>| match oper_ref.val {
+                    OperandValue::Ref(val, _, align) => (val, align),
+                    _ => unreachable!(),
+                };
+                let pointee_layout = dst_val
+                    .layout
+                    .pointee_info_at(&mut bx, rustc_target::abi::Size::ZERO)
+                    .expect("Expected pointer");
+                let elem_size = bx.const_u64(pointee_layout.size.bytes());
+                let byte_count = bx.mul(count, elem_size);
+
+                let (dst, dst_align) = get_val_align(dst_val);
+                let (src, src_align) = get_val_align(src_val);
+                bx.memcpy(dst, dst_align, src, src_align, byte_count, crate::MemFlags::empty());
                 bx
             }
             mir::StatementKind::FakeRead(..)