Re: PATCH: PR c++/16276: Group jump table with function

[Richard Henderson <rth at redhat dot com>]

On Fri, Jul 09, 2004 at 11:31:28AM -0700, H. J. Lu wrote:
> -  if (!(flags & SECTION_DEBUG))
> -    *f++ = 'a';
> -  if (flags & SECTION_WRITE)
> -    *f++ = 'w';
> -  if (flags & SECTION_CODE)
> -    *f++ = 'x';
> -  if (flags & SECTION_SMALL)
> -    *f++ = 's';
> -  if (flags & SECTION_MERGE)
> -    *f++ = 'M';
> -  if (flags & SECTION_STRINGS)
> -    *f++ = 'S';
> -  if (flags & SECTION_TLS)
> -    *f++ = 'T';
> -  *f = '\0';

I think you most certainly do not want to be pulling out the flags
as a string into the caller.  They do not line up 100% between the
targets.

> +#ifdef HAVE_GAS_COMDAT_GROUP
> +#define PUT_JUMP_TABLES_IN_TEXT_SECTION JUMP_TABLES_IN_TEXT_SECTION
> +#else
> +#define PUT_JUMP_TABLES_IN_TEXT_SECTION \
> +  (JUMP_TABLES_IN_TEXT_SECTION || DECL_ONE_ONLY (current_function_decl))
> +#endif

I think the !COMDAT case is wrong.

Suppose SUPPORTS_ONE_ONLY is false, but SUPPORTS_WEAK is true.  In that
case we don't actually have to worry about what section jump tables go in.

Suppose it's a strict harvard architecture machine.  In which case you 
can't go putting *any* data in the text section.

I think the only workable solution is to put all the private read-only
data for a function in an rodata linkonce section for the function.

> +#ifdef READONLY_DATA_SECTION_IN_FUNCTION_GROUP 
> +    READONLY_DATA_SECTION_IN_FUNCTION_GROUP (decl);
> +#else

Now I think you're inventing macros that no one will ever use.


r~