Re: [Tinycc-devel] jmp_buf align problem on win64

[grischka]

Christian Jullien wrote:
> Hi all,
>
> Today I managed to try tcc on win64 (i.e. tcc generates 64bit .exe)
> I bootstrapped tcc with a recent gcc win64 and got a workable tcc that
> compiles my OpenLisp quietly (www.eligis.com). It eventually runs but
> crashes depending on jmp_buf stack alignment. Very often, I found that
> 64bits processors require that jmp_buf are aligned to 16 bytes boundary.
>
> I checked with typedef _CRT_ALIGN(16) struct _JUMP_BUFFER with no success.

Yes, I remember that it was/is a problem when compiling tcc
with itself, too (there is a jmp_buf in TCCState).

Actually there is _CRT_ALIGN(16) for __x86_64 in include/setjmp.h,
but for some reason tcc has problems to remember it.

IIRC it works when used in combination with the variable directly,
such as:
    _CRT_ALIGN(16) jmp_buf buf;
or (translating the macro):
    __attribute__((aligned(16))) jmp_buf buf;

--- grischka

> - Works:
>
> #include <setjmp.h>
>
> int
> main()
> {
>         jmp_buf buf;
>         setjmp( buf );
>         printf("%x\n", _JBLEN);
> }
>
> - Fails:
> #include <setjmp.h>
>
> int
> main()
> {
>         char *p; // add 8 bytes
>         jmp_buf buf;
>         setjmp( buf );
>         printf("%x\n", _JBLEN);
> }
>
> - Works
> #include <setjmp.h>
>
> int
> main()
> {
>         char *p;  // add 8 bytes
>         char *p1; // add 8+8 = 16 bytes
>         jmp_buf buf;
>         setjmp( buf );
>         printf("%x\n", _JBLEN);
> }