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Re: Invalid alias info through crossjumping
- From: Michael Matz <matz at suse dot de>
- To: Andreas dot Krebbel at web dot de
- Cc: gcc at gcc dot gnu dot org
- Date: Mon, 2 Feb 2004 14:07:19 +0100 (CET)
- Subject: Re: Invalid alias info through crossjumping
- References: <200402021319.21837.krebbel1@de.ibm.com>
Hi,
On Mon, 2 Feb 2004, Andreas Krebbel wrote:
> I could imagine two solutions to fix this:
>
> 1.) The insn comparison during crossjumping analysis should draw the
> alias information into. Two insns with different alias data should
> never be considered "mergable".
>
> 2.) If insns get merged during crossjumping the memory reference in the
> resulting insn must be marked with a general alias constraint.
Each has its merits. I feel, that 1 would be the safer approach.
Currently insn_match_p() uses rtx_equal_p() and that one doesn't look into
the second slot of MEM exprs. I'm not sure if that's a good idea.
Ciao,
Michael.