Re: immediate strings #2

[Dmitry Antipov]

Hm, this is still 40 bytes on 64-bit (and so 20 on 32-bit):

struct Lisp_String
  {
    INTERVAL intervals;

    union {

      struct {
        unsigned gcmarkbit : 1;
        unsigned immbit : 1;
        EMACS_INT size : 7;
        EMACS_INT size_byte : 7;
        unsigned char data[STRING_IMM_MAX];
      } imm;

      struct {
        unsigned unused : 2;
        EMACS_INT size : BITS_PER_EMACS_INT - 1;
        EMACS_INT size_byte : BITS_PER_EMACS_INT - 1;
        unsigned char *data;
      } dat;

    } u;
  };

The only way I found to fit it within 32 (or 16, respectively) bytes is:

struct Lisp_String
  {
    INTERVAL intervals;

    union {

      struct {
        unsigned gcmarkbit : 1;
        unsigned immbit : 1;
        EMACS_INT size : 7;
        EMACS_INT size_byte : 7;
        unsigned char data[STRING_IMM_MAX];
      } imm;

      struct {
        unsigned unused : 2;
        EMACS_INT size : BITS_PER_EMACS_INT - 1;
        EMACS_INT size_byte : BITS_PER_EMACS_INT - 1;
        unsigned char *data;
      } __attribute__ ((packed)) dat;

    } u;
  };

It's worth mentioning that only DAT should be packed, not IMM.

Dmitry