PowerPC-sysV/eabi, harmonization of section attribute and small data optimization

[Geoff Keating]

Thierry Moreau <Thierry.Moreau@Connotech.com> writes:

> -       /* We have to be careful here, because it is the referenced address
> -         that must be 32k from _SDA_BASE_, not just the symbol.  */
>         summand = INTVAL (XEXP (sum, 1));
> !       if (summand < 0 || summand > g_switch_value)
>          return 0;
> 
>         sym_ref = XEXP (sum, 0);
> --- 1748,1755 ----
>         rtx sum = XEXP (op, 0);
>         HOST_WIDE_INT summand;
> 
>         summand = INTVAL (XEXP (sum, 1));
> !       if (summand < 0)
>          return 0;
> 
>         sym_ref = XEXP (sum, 0);

This reintroduces a bug that this code was designed to fix.  It is not OK.

Code that triggers the bug can look like:

static char array[4];
t = array[x + 80000];   // valid values of x are -80000 through -79997

GCC can internally optimise this into

t = (array + 80000)[x];

and 'array + 80000' can't be done with a SDA relocation.

-- 
- Geoffrey Keating <geoffk@geoffk.org>