"Pinski, Andrew" <andrew.pin...@caviumnetworks.com> writes:
> This patch implements a simple mips_delegitimize_address for this and
> some related cases.
The problem is that these:
> +/* In the name of slightly smaller debug output, and to cater to
> + general assembler lossage, recognize various UNSPEC sequences
> + and turn them back into a direct symbol reference. */
> +
> +static rtx
> +mips_delegitimize_address (rtx orig_x)
> +{
> + orig_x = delegitimize_mem_from_attrs (orig_x);
> +
> + /* Turn (PLUS:DI (XX)
> + (CONST:DI (UNSPEC:DI [(A)] SYMBOL_64_LOW)))
> + into A. */
> + /* Turn (PLUS:DI (XX)
> + (CONST:DI (PLUS:DI (UNSPEC:DI [(A)] SYMBOL_64_LOW)
> (const_int)))
> + into (PLUS:DI A (const_int)). */
> + /* Turn (PLUS:DI (ASHIFT:DI (CONST:DI (UNSPEC:DI [(A)] SYMBOL_64_HIGH))
> (32) )
> + (XX))
> + into A. */
> + /* Turn (PLUS:DI (ASHIFT:DI (CONST:DI (PLUS:DI (UNSPEC:DI [(A)]
> SYMBOL_64_HIGH)
> + (const_int))) (32))
> + (XX))
> + into (PLUS:DI A (const_int)). */
aren't trustworthy on their own. The CONSTs are just fragments of
addresses, and while the whole expression would typically reference
A(+CONST_INT), it might instead reference A(+CONST_INT)+SOMETHING,
with the SOMETHING typically being added before the final low part.
We can't tell from looking at the CONST alone whether there's a
non-constant offset or not.
I think this is similar to:
/* MEMs without MEM_OFFSETs may have been offset, so we can't just
use their base addresses as equivalent. */
in the default hook.
Richard
