Pinging another patch that I think is important, particularly for -msse users.

Note that gcc / libstdc++ also expect 16-byte alignment, as evidenced by
alignof(std::max_align_t) == 16, the macro __STDCPP_DEFAULT_NEW_ALIGNMENT__
(defined to 16), and the fact that it always bumps the stack pointer by
multiples of 16.

On 2021-11-25 16:13, J.W. Jagersma wrote:
> The section alignment patch I posted here earlier has been accepted in binutils,
> so that will be available in the next release.
>
> Now in libc only these two lines need to be adjusted, and then all code, data,
> stack and heap will be aligned to 16 byte boundaries.
>
> Should be good for SSE, hopefully it will help resolve the gcc 11 Ada issue too.
>
> ---
> src/libc/ansi/stdlib/nmalcdef.h | 2 +-
> src/libc/crt0/crt0.S | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/libc/ansi/stdlib/nmalcdef.h b/src/libc/ansi/stdlib/nmalcdef.h
> index cb41f619..495c63a6 100644
> --- a/src/libc/ansi/stdlib/nmalcdef.h
> +++ b/src/libc/ansi/stdlib/nmalcdef.h
> @@ -188,7 +188,7 @@ typedef struct memblock {
> /* conversion and access macros */
> #define MEMBLKp(p) (memblockp)((byte*)(p) - DATAOFFSET)
> #define PTR(m) (void*)((byte*)(m) + DATAOFFSET)
> -#define ALIGN 8
> +#define ALIGN 16
>
> #define ALIGNMASK (ALIGN-1)
>
> diff --git a/src/libc/crt0/crt0.S b/src/libc/crt0/crt0.S
> index 446a989b..226f0cb9 100644
> --- a/src/libc/crt0/crt0.S
> +++ b/src/libc/crt0/crt0.S
> @@ -315,7 +315,7 @@ use_stubinfo_stack_size:
> addl __stklen, %eax
> movw %ds, %dx /* set stack */
> movw %dx, %ss
> - andb $0xf8, %al /* align to 8-byte boundary */
> + andb $0xf0, %al /* align to 16-byte boundary */
> movl %eax, %esp
> movl %eax, ___djgpp_stack_top /* Top of stack */
> subl ___djgpp_stack_limit, %eax

On Thu, Jan 26, 2023 at 12:50 AM J.W. Jagersma (jwjagersma@gmail.com)
[via djgpp@delorie.com] <djgpp@delorie.com> wrote:
>
> Pinging another patch that I think is important, particularly for -msse users.
>
> Note that gcc / libstdc++ also expect 16-byte alignment, as evidenced by
> alignof(std::max_align_t) == 16, the macro __STDCPP_DEFAULT_NEW_ALIGNMENT__
> (defined to 16), and the fact that it always bumps the stack pointer by
> multiples of 16.
>
>
> On 2021-11-25 16:13, J.W. Jagersma wrote:
> > The section alignment patch I posted here earlier has been accepted in binutils,
> > so that will be available in the next release.
> >
> > Now in libc only these two lines need to be adjusted, and then all code, data,
> > stack and heap will be aligned to 16 byte boundaries.
> >
> > Should be good for SSE, hopefully it will help resolve the gcc 11 Ada issue too.
> >
> > ---
> > src/libc/ansi/stdlib/nmalcdef.h | 2 +-
> > src/libc/crt0/crt0.S | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/libc/ansi/stdlib/nmalcdef.h b/src/libc/ansi/stdlib/nmalcdef.h
> > index cb41f619..495c63a6 100644
> > --- a/src/libc/ansi/stdlib/nmalcdef.h
> > +++ b/src/libc/ansi/stdlib/nmalcdef.h
> > @@ -188,7 +188,7 @@ typedef struct memblock {
> > /* conversion and access macros */
> > #define MEMBLKp(p) (memblockp)((byte*)(p) - DATAOFFSET)
> > #define PTR(m) (void*)((byte*)(m) + DATAOFFSET)
> > -#define ALIGN 8
> > +#define ALIGN 16
> >
> > #define ALIGNMASK (ALIGN-1)
> >
> > diff --git a/src/libc/crt0/crt0.S b/src/libc/crt0/crt0.S
> > index 446a989b..226f0cb9 100644
> > --- a/src/libc/crt0/crt0.S
> > +++ b/src/libc/crt0/crt0.S
> > @@ -315,7 +315,7 @@ use_stubinfo_stack_size:
> > addl __stklen, %eax
> > movw %ds, %dx /* set stack */
> > movw %dx, %ss
> > - andb $0xf8, %al /* align to 8-byte boundary */
> > + andb $0xf0, %al /* align to 16-byte boundary */
> > movl %eax, %esp
> > movl %eax, ___djgpp_stack_top /* Top of stack */
> > subl ___djgpp_stack_limit, %eax
>

PING? Has anyone reviewed this?