diff options
Diffstat (limited to 'src/Sema.zig')
| -rw-r--r-- | src/Sema.zig | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/src/Sema.zig b/src/Sema.zig index 5159d6f5d3..0cf449991d 100644 --- a/src/Sema.zig +++ b/src/Sema.zig @@ -18678,8 +18678,6 @@ fn structFieldPtrByIndex( const target = sema.mod.getTarget(); - // TODO handle when the struct pointer is overaligned, we should return a potentially - // over-aligned field pointer too. if (struct_obj.layout == .Packed) { comptime assert(Type.packed_struct_layout_version == 2); @@ -18700,6 +18698,27 @@ fn structFieldPtrByIndex( ptr_ty_data.host_size = struct_ptr_ty_info.host_size; ptr_ty_data.bit_offset += struct_ptr_ty_info.bit_offset; } + + const parent_align = if (struct_ptr_ty_info.@"align" != 0) + struct_ptr_ty_info.@"align" + else + struct_ptr_ty_info.pointee_type.abiAlignment(target); + ptr_ty_data.@"align" = parent_align; + + // If the field happens to be byte-aligned, simplify the pointer type. + // The pointee type bit size must match its ABI byte size so that loads and stores + // do not interfere with the surrounding packed bits. + if (parent_align != 0 and ptr_ty_data.bit_offset % 8 == 0) { + const byte_offset = ptr_ty_data.bit_offset / 8; + const elem_size_bytes = ptr_ty_data.pointee_type.abiSize(target); + const elem_size_bits = ptr_ty_data.pointee_type.bitSize(target); + if (elem_size_bytes * 8 == elem_size_bits) { + const new_align = @as(u32, 1) << @intCast(u5, @ctz(u64, byte_offset | parent_align)); + ptr_ty_data.bit_offset = 0; + ptr_ty_data.host_size = 0; + ptr_ty_data.@"align" = new_align; + } + } } else { ptr_ty_data.@"align" = field.abi_align; } |