Hi,
I'm working on a new target port in which there are different base
registers
allowed depending on the offset:
r0-r7 are allowed as base register only when the offset is zero.
r6-r7 are allowed as base register for every offset.
I'm wondering if gcc is prepared for such scenario, examine the code in
find_reloads_address(), for the architecture I'm working on, it seems
the
condition here should be true, because it might not be valid because the
base reg isn't r6-r7, not only because the disp is too large.
Yet it fails because of REG_MODE_OK_FOR_BASE_P (XEXP (ad, 0), mode).
/* If we have address of a stack slot but it's not valid because the
displacement is too large, compute the sum in a register.
Handle all base registers here, not just fp/ap/sp, because on some
targets (namely SH) we can also get too large displacements from
big-endian corrections. */
else if (GET_CODE (ad) == PLUS
&& REG_P (XEXP (ad, 0))
&& REGNO (XEXP (ad, 0)) < FIRST_PSEUDO_REGISTER
&& REG_MODE_OK_FOR_BASE_P (XEXP (ad, 0), mode)
&& GET_CODE (XEXP (ad, 1)) == CONST_INT)
{
/* Unshare the MEM rtx so we can safely alter it. */
if (memrefloc)
{
*memrefloc = copy_rtx (*memrefloc);
loc = &XEXP (*memrefloc, 0);
if (removed_and)
loc = &XEXP (*loc, 0);
}
...
Is there any way to get along by defining r0-r7 as legal base regs and
deal
with r6-r7 in GO_IF_LEGITIMATE_ADDRESS and in the constraint
definitions,
or am I right with my assumption that gcc doesn't support that?
Does someone knows if there's a target with a similar behavior?
Thanks in advance,
Tal Agmon.
