Re: Proposal: immediate strings

[Dmitry Antipov]

On 05/29/2012 07:24 PM, Paul Eggert wrote:

> That one's clever, but doesn't it grow the size of "struct Lisp_String"
> by a word, due to the padding bytes after the gcmarkbit member?
>
> Why does gcmarkbit have to be in the same place for the two kinds
> of strings?  If you could put gcmarkbit in different places in the
> different union members, you wouldn't need that padding.

IIUC this is the only possible layout which: 1) uses bitfields 2) not requires
__attribute__((packed)) and 3) provides 16-bytes Lisp_String with 10 bytes
for immediate data on 32-bit and 32-bytes Lisp_String with 22 bytes
for immediate data on 64-bit.

Dmitry