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Re: Patch to improve PIC rtx_unstable_p & rtx_addr_can_trap
- To: John Wehle <john at feith dot com>
- Subject: Re: Patch to improve PIC rtx_unstable_p & rtx_addr_can_trap
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Tue, 22 Aug 2000 11:22:35 -0600
- cc: gcc-patches at gcc dot gnu dot org
- Reply-To: law at cygnus dot com
In message <200008211736.NAA01357@jwlab.FEITH.COM>you write:
> > > * rtlanal.c (rtx_unstable_p): The pic register is stable
> > > (within one function) and the actual rtx should be used
> > > when checking the registers.
> > This is not necessarily true. Consider a target where the PIC register
> > is call-clobbered. Probably the thing to do is check for that explicitly
> .
>
> I wondered about that, however the existing test in rtx_varies_p
> doesn't check PIC_OFFSET_TABLE_REG_CALL_CLOBBERED so I made a leap
> of faith and assumed that reload made sure that the pic register
> has a valid value in this case. I take it that this isn't true?
> Should I go ahead and install the patch changing the check in
> rtx_unstable_p from:
Based on Richard's comments, let's not worry about the problems with
call-clobbered PIC registers. In theory, they shouldn't cause any problems :-)
jeff