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Re: Adding constants to LO_SUM
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Subject: Re: Adding constants to LO_SUM
- From: Geoff Keating <geoffk at geoffk dot org>
- Date: 09 Jul 2001 12:33:02 -0700
- CC: gcc-patches at gcc dot gnu dot org
- References: <10107091901.AA06814@vlsi1.ultra.nyu.edu>
kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:
> /* For now, this is just a wrapper for change_address, but eventually
> will do memref tracking. */
> ! rtx addr = XEXP (memref, 0);
> !
> ! /* If MEMREF is a LO_SUM and the offset is within the size of the
> ! object, we can merge it into the LO_SUM. */
> ! if (GET_MODE (memref) != BLKmode && GET_CODE (addr) == LO_SUM
> ! && offset >= 0 && offset < GET_MODE_SIZE (GET_MODE (memref)))
> ! addr = gen_rtx_LO_SUM (mode, XEXP (addr, 0),
> ! plus_constant (XEXP (addr, 1), offset));
> ! else
> ! addr = plus_constant (addr, offset);
> !
> ! return change_address (memref, mode, addr);
> }
This might fix the problem, but it isn't correct. Just because it
happens to work on rs6000 for 'long long', it doesn't follow it'll
work everywhere. It is an inherently target-dependent thing, because
LO_SUM is a target-dependent thing.
--
- Geoffrey Keating <geoffk@geoffk.org>